Electronic Test Equipment

Abstract

A type of tester apparatus is described that tests wafers by contacting terminals on the wafer. A dielectric gas is used to reduce arcing between the contacts. The stationary and portable structures have complementary gas connection portions that engage when the portable structure engages the stationary structure. The gas box has a channeling block connected to a dielectric gas pressure regulator and a nitrogen gas pressure regulator and to gas supply passages to selectively supply nitrogen or dielectric gas to the gas supply passages. The tray is conductive and has a portion that contacts the back wafer terminals and a vacuum passage, each vacuum passage having an enlarged section to reduce arcing.

Description

[Background technology]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS]

[0001] This application claims priority from U.S. Provisional Patent Application No. 63 / 477,916, filed December 30, 2022, the entire contents of which are incorporated by reference into this application.

[0002]

[0002] 1) Field of the invention

[0003] The present invention relates to tester apparatus used to test microelectronic circuits.

[0003] 2) Consideration of related technologies

[0004] Microelectronic circuits are typically fabricated within and on top of semiconductor wafers. Such wafers are then "singulated" or "diced" into individual die. Such die are typically attached to a support plate to provide rigidity to the support plate and to electronically communicate with the integrated circuits or microelectronic circuits of the die. Final packaging may include encapsulation of the die, and the resulting package can be shipped to a customer.

[0004]

[0005] Dies or packages must be tested before shipping to customers. Ideally, dies should be tested at an early stage to identify defects that occur during early manufacturing. Wafer-level testing involves providing contacts to a processor and contactor, then using the processor to move the wafer so that its contacts make contact with the contactor contacts. Power and electronic signals are then passed through the contactor to and from the microelectronic circuits formed on the wafer. Summary of the Invention [Problem to be solved by the invention]

[0005]

[0006] According to various embodiments, a wafer includes a substrate, such as a silicon substrate or a printed circuit board, and one or more devices fabricated within or attached to the substrate.

[0006]

[0007] Alternatively, the wafers can be placed in a portable wafer pack with an electrical interface and a thermal chuck, which can be heated or cooled to thermally control the temperature of the wafer while power and signals can be transferred to and from the wafer via the electrical interface.

[0007]

[0008] After the wafer is singulated, the individual die may need to be tested again, and the die may need to be tested again after it is attached to a support plate. [Means for solving the problem]

[0008]

[0009] The present invention provides a tester apparatus comprising first and second components for holding a substrate therebetween, the substrate carrying a microelectronic circuit and having a plurality of terminals connected to the microelectronic circuit, a plurality of contacts on the second component corresponding to and contacting the terminals, a cavity seal between the first and second components and forming an enclosed cavity together with surfaces of the first and second components, a reduced pressure passage formed through one of the components and having an inlet opening in the enclosed cavity and an outlet opening outside the enclosed cavity, a reduced pressure supply connected to the reduced pressure passage, the opening of which ensures that gas leaves the enclosed cavity and the closing of which prevents gas from entering the enclosed cavity, and an electrical tester connected to the microelectronic circuit for testing the microelectronic circuit.

[0009]

[0010] The present invention also provides a tester apparatus comprising first and second components for holding a substrate therebetween, the substrate comprising the first and second components carrying a microelectronic circuit and having a plurality of terminals connected to the microelectronic circuit, a plurality of contacts on the second component and matching with and contacting the terminals, a cavity seal between the first and second components and forming an enclosed cavity together with surfaces of the first and second components, and a reducer formed through one of the components and having an inlet opening in the enclosed cavity and an outlet opening outside the enclosed cavity. a pressure passage; a reduced pressure supply connected to the reduced pressure passage, the opening of which ensures that gas leaves the enclosed cavity and the closing of which prevents gas from entering the enclosed cavity; an electrical tester connected to the microelectronic circuit for testing the microelectronic circuit; a gas supply passage formed through one of the components and having an inlet opening outside the enclosed cavity and an outlet opening in the enclosed cavity; and a gas inlet supply connected to the gas supply passage, the opening of which ensures that gas enters the enclosed cavity and the space between the contacts.

[0010]

[0011] The present invention further provides a tester apparatus, the tester apparatus comprising: a portable support structure including first and second components for holding a substrate therebetween, the substrate carrying a microelectronic circuit and having a plurality of terminals connected to the microelectronic circuit, the first component being a wafer chuck in the form of a flat piece having a flat surface; a plurality of contacts on the second component that align with and contact the terminals; and a cavity seal between the first and second components and forming an enclosed cavity together with the surfaces of the first and second components. a reduced pressure passage formed through one of the components and having an inlet opening in the enclosed cavity and an outlet opening outside the enclosed cavity; a reduced pressure supply connected to the reduced pressure passage, the opening of which ensures that gas is outside the enclosed cavity and the closing of which prevents gas from entering the enclosed cavity; a first electrical connection on the portable support structure and connected to the contact; a portable structure gas removal connection on the portable structure; a stationary structure receivable to hold the portable support structure and from which the portable support structure is removable; and a second electrical connection on the stationary structure, connected to the first electrical connection when the portable structure is held by the stationary structure and which is removable when the portable support structure is removed from the stationary structure. a second electrical connection portion that is disconnected from the first electrical connection portion when the portable structure is removed; an electrical tester connected to the terminal via the second electrical connection portion, the first electrical connection portion, and the contact; a thermal chuck in a stationary structure, the planar surface of the thermal chuck being movable toward the planar surface of the thermal chuck; a gas removal conduit forming part of the stationary structure; a stationary structure gas removal connection portion forming part of the stationary structure, the stationary structure gas removal connection portion shaped to mate with the portable structure gas removal connection portion when the wafer chuck moves toward the thermal chuck, thereby connecting the outlet opening of the reduced pressure passage to the stationary structure gas removal conduit; and an electrical tester connected to the microelectronic circuit for testing the microelectronic circuit.

[0011]

[0012] The present invention also provides a tester apparatus, the tester apparatus including: a tray for releasably holding a wafer, the tray having at least a portion that is conductive and has an exposed surface for contacting a backside wafer terminal on the backside of the wafer; a contactor board having contactor front contacts mounted thereon, each contactor front contact having a surface arranged to contact a respective front wafer terminal on the front side of the wafer; an electrical tester connected to the contactor front contacts, such that, in use, current conducts between the wafer and a circuit on the wafer for testing via the front side wafer contacts and the contactor front contact; and an electrical conductor connected to the conductive portion, such that, in use, the circuit is connected to the electrical tester via the backside wafer contacts, the exposed surfaces of the conductive portion, and an electrical path.

[0012]

[0013] The present invention further provides a tester apparatus including a wafer chuck, a tray for releasably holding a wafer and releasably positioned on the wafer chuck, the wafer chuck having a vacuum passage therethrough and the tray having a plurality of vacuum openings therethrough, each vacuum opening connecting the backside of the wafer to a vacuum passage in the wafer chuck so that when a vacuum is applied to the vacuum passage, the vacuum secures the backside of the wafer to the tray, a contactor board having contactor contacts mounted thereon, each contactor contact having a surface positioned to contact a respective front wafer terminal on the front side of the wafer, and an electrical tester connected to the contactor contacts so that, in use, current is conducted to and from circuitry on the wafer through the front side wafer contacts and the contactor contacts to test the circuitry.

[0013]

[0014] The present invention further provides a tester apparatus comprising: a vacuum conduit forming a vacuum path; a wafer holder for releasably holding a wafer; the wafer holder having a plurality of vacuum openings therethrough, each vacuum opening connecting a backside of the wafer to the vacuum path so that when a vacuum is applied to the vacuum path, the vacuum secures the backside of the wafer to the wafer holder; each vacuum opening having an entrance opening at the wafer, an exit opening remote from the wafer, and an enlarged section between the entrance and exit openings for reducing arcing between the openings; a contactor board having contactor contacts mounted thereon, each contactor contact having a surface positioned to contact a respective front wafer terminal on the front side of the wafer; and an electrical tester connected to the contactor contacts so that, in use, current is conducted to and from circuitry on the wafer through the front side wafer contacts and the contactor contacts to test the circuitry.

[0014]

[0015] The present invention also provides a gas box, the gas box including: a vacuum regulator connectable to the reduced pressure passage and controlling the flow of gas through the reduced pressure passage; a dielectric gas pressure regulator connectable to the gas supply passage and controlling the flow of dielectric gas to the gas supply passage; a nitrogen gas pressure regulator for controlling the flow of nitrogen gas to the gas supply passage; and a channeling block connected to the dielectric gas pressure regulator and the nitrogen gas pressure regulator and connectable to the gas supply passage and for selectively supplying nitrogen gas or dielectric gas to the gas supply passage.

[0015]

[0016] The present invention further provides a wafer pack, the wafer pack comprising first and second components for holding a substrate therebetween, the substrate comprising: a portable support structure carrying a microelectronic circuit and having a plurality of terminals connected to the microelectronic circuit; a plurality of contacts on the second component and matching and contacting the terminals; a cavity seal between the first and second components and forming an enclosed cavity together with surfaces of the first and second components; a reduced pressure passage formed through one of the components and having an inlet opening in the enclosed cavity and an outlet opening outside the enclosed cavity; a reduced pressure supply connected to the reduced pressure passage, the opening of which ensures gas exits the enclosed cavity and the closing of which prevents gas from entering the enclosed cavity; and a first electrical connection part on the portable support structure and connected to the contacts, the first electrical connection part being connected to a second electrical connection part on the stationary structure when the portable support structure is removably held by the stationary structure.

[0016]

[0017] The present invention also provides a wafer pack, the wafer pack comprising a portable support structure including first and second components for holding a substrate therebetween, the substrate carrying a microelectronic circuit and having a plurality of terminals connected to the microelectronic circuit; a plurality of contacts on the second component that mate with and contact the terminals; a cavity seal between the first and second components and forming an enclosed cavity together with surfaces of the first and second components; a vacuum passage formed through one of the components and having an inlet opening in the enclosed cavity and an outlet opening outside the enclosed cavity; and a vacuum supply connected to the vacuum passage, the opening of which allows gas to enter the enclosed cavity. a reduced pressure supply ensuring gas exits the enclosed cavity and preventing gas from entering the enclosed cavity upon closure thereof; a first electrical connection portion on the portable support structure and connected to the contacts, the first electrical connection portion being connected to a second electrical connection portion on the stationary structure when the portable support structure is removably held by the stationary structure; a gas supply passage formed through one of the components, the gas supply passage having an inlet opening outside the enclosed cavity and an outlet opening in the enclosed cavity; and a gas inlet supply connected to the gas supply passage, the opening of which ensures gas enters the enclosed cavity and the space between the contacts.

[0017]

[0018] The present invention further provides a wafer pack, the wafer pack comprising a portable support structure including first and second components for holding a substrate therebetween, the substrate carrying a microelectronic circuit and having a plurality of terminals connected to the microelectronic circuit, the first component being a wafer chuck in the form of a flat piece having a flat surface movable towards a flat surface of a stationary thermal chuck, a plurality of contacts on the second component for matching with and contacting the terminals, and a plurality of contacts between the first and second components and forming an enclosed cavity together with the surfaces of the first and second components. a cavity seal for connecting the vacuum passage formed through one of the components, the vacuum passage having an inlet opening in the enclosed cavity and an outlet opening outside the enclosed cavity; a vacuum supply connected to the vacuum passage, the opening of which ensures gas exits the enclosed cavity and the closing of which prevents gas from entering the enclosed cavity; a first electrical connection portion on the portable support structure and connected to the contact, the first electrical connection portion being on the portable support structure and connecting to a second electrical connection portion on the stationary structure when the portable support structure is removably held by the stationary structure; and a portable structure gas removal connection portion shaped to mate with the stationary structure gas removal connection portion when the wafer chuck moves towards the thermal chuck, thereby connecting the outlet opening of the vacuum passage to a gas removal conduit of the stationary structure.

[0018]

[0019] The present invention also provides a method for testing a microelectronic circuit carried by a substrate, the method comprising the steps of: holding the substrate between first and second components, the second component having contacts that press against terminals of the substrate connected to the microelectronic circuit; disposing a cavity seal between the first and second components to form a cavity surrounded by surfaces of the first and second components and the cavity seal; and transmitting signals between an electrical tester and the microelectronic circuit to test the microelectronic circuit.

[0019]

[0020] The present invention further provides a method for testing a microelectronic circuit carried by a substrate, the method comprising the steps of: holding the substrate between first and second components, the second component having contacts that press against terminals of the substrate connected to the microelectronic circuit; disposing a cavity seal between the first and second components to form a cavity enclosed by surfaces of the first and second components and the cavity seal; transmitting signals between an electrical tester and the microelectronic circuit to test the microelectronic circuit; and ensuring that a dielectric gas is introduced into the enclosed cavity and into the space between the contacts.

[0020]

[0021] The present invention also provides a method for testing a microelectronic circuit carried by a substrate, the method comprising the steps of: holding the substrate between first and second components, the second component having contacts that press against terminals of the substrate connected to the microelectronic circuit, the first component being a wafer chuck in the form of a flat piece having a flat surface; disposing a cavity seal between the first and second components to form a cavity surrounded by the surfaces of the first and second components and the cavity seal; and connecting a first electrical connection portion on the portable support structure to a second electrical connection portion on the stationary structure. the stationary structure with the portable support structure connected to the wafer chuck; moving the flat surface of the wafer chuck toward the flat surface of the thermal chuck of the stationary structure to further couple the portable structure gas removal connection portion with the stationary structure gas removal connection portion, thereby connecting the outlet opening of the reduced pressure passage to the gas removal conduit of the stationary structure; and transmitting a signal between the electrical tester and the microelectronic circuit to test the microelectronic circuit, the signal being transmitted between the electrical tester and the microelectronic circuit via the terminals, contacts, and first and second electrical connection portions to test the microelectronic circuit.

[0021]

[0022] The present invention further provides a method for testing wafers, the method including the steps of: holding wafers on a tray, the tray having at least portions that are conductive and have exposed surfaces that contact backside wafer terminals on the backside of the wafers; moving the contact plate and the tray relative to one another so that surfaces of contactor contacts mounted on the contactor plate contact respective frontside wafer contacts on the frontside of the wafers; conducting current between an electrical tester and circuits on the wafers through the frontside wafer contacts and the contactor contacts to test the circuits, the circuits being connected to the electrical tester via the backside wafer terminals, the exposed surfaces of the conductive portions, and electrical paths; and removing the wafers from the tray.

[0022]

[0023] The present invention also provides a method for testing wafers, the method including the steps of holding wafers in a tray; placing the tray on a wafer chuck; applying a vacuum to a vacuum passage through the wafer chuck, the tray having a plurality of vacuum openings therethrough, each vacuum opening connecting a backside of the wafer to a vacuum passage in the wafer chuck so that the vacuum secures the backside of the wafer to the tray; moving the contactor board and the tray relatively toward each other so that surfaces of contactor contacts mounted on the contactor board contact respective front wafer contacts on the front side of the wafer; conducting current between an electrical tester and circuitry on the wafer through the front side wafer contacts and the contactor contacts to test the circuitry; and removing the wafer from the tray.

[0023]

[0024] The present invention further provides a method for testing wafers, the method including the steps of releasably holding a wafer in a wafer holder, the wafer holder having a plurality of vacuum openings therethrough, each vacuum opening connecting a backside of the wafer to a vacuum passage; applying a vacuum to the vacuum passage, the vacuum securing the backside of the wafer to the wafer holder; moving a contactor panel and a tray relative to one another so that surfaces of contactor contacts mounted on the contactor panel contact respective front wafer contacts on the front side of the wafer; conducting current between an electrical tester and circuits on the wafer through the front side wafer contacts and the contactor contacts to test the circuits, each vacuum opening having an entrance opening at the wafer, an exit opening away from the wafer, and an enlarged section between the entrance and exit openings to reduce arcing between the openings; and removing the wafer from the tray.

[0024]

[0025] The invention will now be further described, by way of example only, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a cross-sectional side view of a tester device having a slot assembly according to one embodiment of the invention. [Figure 2] FIG. 2 is a cross-sectional side view of the tester device of FIG. 1 taken along line 2-2. [Figure 3] FIG. 3 is a cross-sectional side view of the tester device of FIG. 1 taken along line 3-3. [Figure 4] FIG. 4 is a cross-sectional side view of the tester apparatus of FIGS. 2 and 3 taken along line 4-4. [Figure 5A] FIG. 1 is a perspective view of the tester apparatus showing the insertion and removal of the portable wafer pack into and from the oven defined by the frame. [Figure 5B] FIG. 1 is a perspective view of the tester apparatus showing the insertion and removal of the portable wafer pack into and from the oven defined by the frame. [Figure 5C] FIG. 1 is a perspective view of the tester apparatus showing the insertion and removal of the portable wafer pack into and from the oven defined by the frame. [Figure 6]1 is a timing diagram showing how one wafer pack is inserted into the wafer electronics and used for testing, followed by the insertion of another wafer pack. [Figure 7] FIG. 10 is a perspective view of the tester device showing the insertion or removal of one slot assembly. [Figure 8A] FIG. 8 is a cross-sectional side view illustrating the use of standoffs in the wafer pack configuration described with respect to FIGS. 1-7. [Figure 8B] FIG. 8 is a cross-sectional side view illustrating the use of standoffs in the wafer pack configuration described with respect to FIGS. 1-7. [Figure 9A] FIG. 1 is a side view showing a device used to transfer portable wafer packs to and from an oven. [Figure 9B] FIG. 1 is a side view showing a device used to transfer portable wafer packs to and from an oven. [Figure 10] FIG. 1 is a side view showing a device used to transfer portable wafer packs to and from an oven. [Figure 11] FIG. 2 is a perspective view of the first wafer pack as seen from above. [Figure 12] FIG. 2 is a perspective view of the first wafer pack as seen from below. [Figure 13] 13 is a cross-sectional view of the first wafer pack taken along line 13-13 of FIGS. 11 and 12. FIG. [Figure 14] FIG. 14 is a cross-sectional view of the first wafer pack taken along line 14-14 of FIG. 13. [Figure 15] 15 is a cross-sectional view of the first wafer pack taken along line 15-15 of FIG. 12. FIG. [Figure 16] 15 from the direction of arrow A with components removed from FIG. 15. FIG. [Figure 17] FIG. 17 is a cross-sectional view of FIG. 15 taken along line 17-17. [Figure 18A(i)] 15 in the direction of arrow A with the latch mechanism in the unlocked configuration. FIG. [Figure 18A(ii)]15 in the direction of arrow B with the latch mechanism in the unlocked configuration. [Figure 18B(i)] FIG. 18A(i) is a view similar to FIG. 18A(i), but with the latch mechanism in the locked position. [Figure 18B(ii)] 18A(ii) is a view similar to FIG. 18A(ii), but with the latch mechanism in the locked position. [Figure 19] FIG. 10 is a perspective view showing how shims are used to set the height of the winglets of the latch mechanism. [Figure 20] FIG. 1 is a perspective view showing components of a pressure monitoring system. [Figure 21] FIG. 10 is a perspective view showing further components of the pressure monitoring system. [Figure 22A] FIG. 1 is a perspective view showing the components prior to engagement with the pressure monitoring system. [Figure 22B] FIG. 1 is a side view showing the components prior to engagement with the pressure monitoring system. [Figure 23A] FIG. 22B is a view similar to FIG. 22A showing the components of the pressure monitoring system after engagement. [Figure 23B] FIG. 22C is a view similar to FIG. 22B showing the components of the pressure monitoring system after engagement. [Figure 24] FIG. 2 is a block diagram illustrating components of a tester apparatus used to introduce a dielectric gas. [Figure 25] FIG. 2 is a plan view of the slot assembly. [Figure 26] FIG. 26 is a cross-sectional side view taken along 26A-26B of FIG. 25. [Figure 27] FIG. 27 is a cross-sectional side view taken along 27A-27B of FIG. 25. [Figure 28] FIG. 27 is a detailed view of the area marked "C" in FIG. 26. [Figure 29] FIG. 28 is a detailed view of the area marked "D" in FIG. 27. [Figure 30] FIG. 2 is a perspective view of a slot assembly. [Figure 31] FIG. 10 is a partially cutaway perspective view of a bus box used in the slot assembly. [Figure 32]FIG. 10 is a partially cutaway perspective view of a bus box used in the slot assembly. [Figure 33] FIG. 1 is a cross-sectional side view showing a portion of a wafer pack and slot assembly. [Figure 34] FIG. 34 is a detailed view of the area marked "E" in FIG. 33. [Figure 35] FIG. 34 is a cross-sectional perspective view of a wafer chuck and a tray of the wafer pack shown in FIG. 33. [Figure 36] 35 is a cross-sectional perspective view of the wafer chuck and tray of the wafer pack shown in FIG. 33, taken at a right angle to FIG. 35. DETAILED DESCRIPTION OF THE INVENTION

[0026]

[0060] 1 of the accompanying drawings shows a tester apparatus 10 according to one embodiment of the invention, the tester apparatus 10 comprising (i) a stationary structure including a tester 12, a frame 14, a power bus 16, first and second slot assemblies 18A and 18B, a tester cable 20, a power cable 22, a cooling liquid supply line 24A, a cooling liquid return line 24B, a control liquid supply line 24C, a control liquid return line 24D, and a vacuum line 24E, (ii) a portable support apparatus including first and second wafer packs 28A and 28B, and (iii) first and second wafers 30A and 30B. The first and second wafer packs 28A and 28B are referred to herein as "wafer packs," and their use for testing wafers is described. It should be understood that the first and second wafer packs 28A and 28B may be used generally for testing microelectronic circuits and may alternatively be classified as "first and second microelectronic circuit test packs 28A and 28B."

[0027]

[0061] The slot assembly 18A includes a slot assembly body 32, a thermal chuck 34, a temperature detector 36, a temperature compensation device in the form of a heating resistor 38, a first slot assembly connection portion 40 and a plurality of second slot assembly connection portions, the second slot assembly connection portions including a control connection portion 44, a power connection portion 46 and a coolant supply connection portion 48A, a coolant return connection portion 48B, a control liquid supply connection portion 48C, a control liquid return connection portion 48D and a vacuum connection portion 48E.

[0028]

[0062] A first slot assembly connection portion 40 is disposed within and attaches to the slot assembly body 32. A second electrical connection portion in the form of a control connection portion 44, a power connection portion 46, and connection portions 48A-48E attaches to the left wall of the slot assembly body 32.

[0029]

[0063] Slot assembly 18A can be inserted into frame 14 from left to right and removed from frame 14 from right to left. Tester cable 20, power cable 22, and various lines 24A to 24E are manually connected to control connection portion 44, power connection portion 46, and connections 48A to 48E, respectively. Before removing slot assembly 18A from frame 14, tester cable 20, power cable 22, and various lines 24A to 24E are first manually disconnected from control connection portion 44, power connection portion 46, and connections 48A to 48E, respectively.

[0030]

[0064] The slot assembly 18A includes a motherboard 60 with test electronics, a plurality of channel module boards 62 with test electronics, a flexible connector 64, and a connection board 66. The control connection portion 44 and the power connection portion 46 are connected to the motherboard 60, and the thermal controller 50 is attached to the motherboard 60. The channel module boards 62 are electrically connected to the motherboard 60. The flexible connector 64 connects the channel module boards 62 to the connection board 66. Control functions are provided via conductors connecting the control connection portion 44 to the motherboard 60. Power is provided to the motherboard 60 via the power connection portion 46. Both power and control are provided to the channel module boards 62 from the motherboard 60 via conductors. The flexible connector 64 provides conductors connecting the channel module boards 62 to the connection board 66. The connection board 66 includes conductors connecting the flexible connector 64 to the first slot assembly connection portion 40. This first slot assembly connection portion 40 is connected to the control connection portion 44 and the power connection portion 46 via various conductors so that power and control can be supplied to the first slot assembly connection portion 40 via the control connection portion 44 and the power connection portion 46.

[0031]

[0065] The second slot assembly 18B includes similar components to the first slot assembly 18A, and like reference numerals indicate like components. The second slot assembly 18B is inserted into the frame 14, and the control connection portion 44, the power connection portion 46, and the connection portions 48A-48E of the second slot assembly 18B are manually connected to a set of separate connection structure components, including the separate tester cable 20, the separate power supply cable 22, and the separate lines 24A-24E, respectively.

[0032]

[0066] Wafer pack 28A includes a wafer pack body formed by wafer chuck 72 and backplate 74. Wafer 30A has multiple microelectronic devices formed thereon. Wafer 30A is inserted within the wafer pack body between wafer chuck 72 and backplate 74. Multiple wafer pack contacts 76 contact respective contacts (not shown) on wafer 30A. Wafer pack 28A further includes a wafer pack connecting portion 78 on backplate 74. Conductors in backplate 74 connect wafer pack connecting portion 78 to wafer pack contacts 76.

[0033]

[0067] Wafer pack 28A has a lip seal 77 (also referred to herein as a "pressure differential cavity seal") connected between backplate 74 and wafer chuck 72. A vacuum is applied to the area defined by lip seal 77, backplate 74, and wafer chuck 72. The vacuum holds wafer pack 28A together and ensures proper contact between wafer pack contacts 76 and contacts on wafers 30A.

[0034]

[0068] Temperature detector 36 is positioned within thermal chuck 34 and is therefore close to wafer 30A or within 5 degrees Celsius, preferably 1 or 2 degrees Celsius, of wafer 30A to detect the temperature of wafer 30A.

[0035]

[0069] The slot assembly 18A further includes a door 82 connected to the slot assembly body 32 by a hinge 84. When the door 82 is rotated to an open position, the wafer pack 28A can be inserted into the slot assembly body 32 through a door opening 86. The wafer pack 28A is then lowered onto the thermal chuck 34, and the door 82 is closed. The thermal chuck 34 attaches to the slot assembly body 32. The thermal chuck 34 thus essentially forms a stationary holder with a test station for the wafer.

[0036]

[0070] Slot assembly 18A further includes a thermal interface cavity seal 88 disposed between thermal chuck 34 and wafer chuck 72. A vacuum is applied to the area defined by thermal interface cavity seal 88, thermal chuck 34, and wafer chuck 72 via vacuum interface 48E and vacuum line 90. This provides a good thermal connection between thermal chuck 34 and wafer chuck 72. When heat is generated by heating resistor 38, the heat is conducted through thermal chuck 34 and wafer chuck 72 to wafer 30A. When thermal chuck 34 is at a lower temperature than wafer 30A, heat is conducted in the opposite direction.

[0037]

[0071] The wafer pack connection portion 78 is engaged with the first slot assembly connection portion 40. Power and signals are supplied to the wafer 30A via the first slot assembly connection portion 40, the wafer pack connection portion 78, and the wafer pack contacts 76. The performance of the devices in the wafer 30A is measured via the wafer pack contacts 76, the wafer pack connection portion 78, and the first slot assembly connection portion 40.

[0038]

[0072] Door 82 of slot assembly 18B is shown in the closed position. A front seal 100 is attached to the top of slot assembly 18A and seals against the underside of slot assembly 18B. A front seal 102 is attached to the top of slot assembly 18B and seals against the underside of frame 14. Doors 82 and front seals 100 and 102 of slot assemblies 18A and 18B provide a continuous, sealed front wall 104.

[0039]

[0073] The slot assembly 18A further includes a thermal controller 50. The temperature detector 36 is connected to the thermal controller 50 via a temperature feedback line 52. Power is supplied to the heating resistor 38 through the power connection 46 and a power line 54 so that the heating resistor 38 heats up. The heating resistor 38, in turn, heats the thermal chuck 34 and the wafer 30A thereon. The heating resistor 38 is controlled by the thermal controller 50 based on the temperature detected by the temperature detector 36.

[0040]

[0074] Thermal chuck 34 has thermal fluid passages 224 formed therein. Thermal fluid passages 224 hold a thermal fluid. The thermal fluid is preferably a liquid rather than a gas because liquids are incompressible and heat convects to and from liquids more quickly. Different thermal fluids are used for different applications, with oil being used for the highest temperature applications.

[0041]

[0075] Control fluid supply and return lines 226 and 228 connect opposite ends of the thermal fluid passage 224 to cooling fluid supply and return connections 48C and 48D, respectively. Heating resistor 38 serves as a fixed-position heater that heats the thermal chuck 34, which in turn heats the thermal fluid. By recirculating the thermal fluid through thermal fluid passage 224, thermal chuck 222 provides a more uniform heat distribution to the thermal chuck 34 and ultimately to the wafer 30A. The temperature of the fluid can also be controlled to heat or cool the thermal chuck 34.

[0042]

[0076] The tester apparatus 10 further includes a cooling system 240, a temperature control system 242, and a vacuum pump 244. Two cooling liquid supply lines 24A connected to the first and second slot assemblies 18A and 18B are also connected to the cooling system 240 via a manifold (not shown). Additional manifolds connect the cooling liquid return line 24B to the cooling system 240, the control liquid supply line 24C to the temperature control system 242, the control liquid return line 24D to the temperature control system 242, and the vacuum line 24E to the vacuum pump 244. Each slot assembly 18A or 18B has a respective cooling plate 246 with a respective fluid passage 248. The cooling system 240 circulates fluid through the fluid passages 248 to cool the cooling plate 246. The cooling plate 246, in turn, keeps the channel module board 62 cool. A temperature control system 242 circulates fluid through thermal fluid passages 224 to control the temperature of thermal chuck 34 and to transfer heat to and from wafers 30A and 30B. A vacuum pump 244 supplies air at vacuum pressure to vacuum line 90.

[0043]

[0077] Slot assembly 18A includes a separator seal 108 that is attached to the upper surface of slot assembly body 32 above inner wall 106. Separator seal 108 seals against the underside of slot assembly 18B. Slot assembly 18B has a separator seal 110 attached to the upper surface of its slot assembly body 32. Separator seal 108 seals against the underside of frame 14. The inner walls 106 of slot assemblies 18A and 18B and separator seals 108 and 110 provide a continuously sealed separator wall 112.

[0044]

[0078] Figure 2 is a diagram of the tester apparatus 10 of Figure 1 taken along line 2-2. The frame 14 defines a first closed-loop air path 120. Air inlet and outlet openings (not shown) can be opened to convert the first closed-loop air path 120 to an open air path in which room temperature air flows through the frame 14 without recirculation. A closed-loop path is particularly useful in cleanroom environments because cleanroom environments emit less particulate matter into the air.

[0045]

[0079] The tester apparatus 10 further includes temperature compensation equipment in the form of a first fan 122 , a first fan motor 124 and a water cooler 126 .

[0046]

[0080] A first fan 122 and a first fan motor 124 are mounted in the upper portion of the first closed-loop air path 120. A water chiller 126 is mounted to the frame 14 within the upper portion of the first closed-loop air path 120.

[0047]

[0081] Wafer packs 28A and 28B are positioned with slot assemblies 18A and 18B within the bottom half of first closed-loop air path 120.

[0048]

[0082] In use, current is supplied to the first fan motor 124. The first fan motor 124 rotates the first fan 122. The first fan 122 recirculates air through the first closed-loop air path 120 in a clockwise direction.

[0049]

[0083] The water chiller 126 then cools the air in the first closed-loop air path 120. The air then flows through one lot assembly 18A and 18B and over the wafer pack 28A or 28B, which is then cooled by the convective air.

[0050]

[0084] Figure 3 is a diagram of the tester apparatus 10 of Figure 1 taken along line 3-3. The frame 14 defines a second closed-loop air path 150. The tester apparatus 10 further includes temperature compensation equipment in the form of a second fan 152, a second fan motor 154, and a water chiller 156. No electric heaters or dampers are provided as shown in Figure 2. The air inlet and outlet openings (not shown) can be opened to convert the second closed-loop air path 150 to an open air path in which room temperature air passes through the frame 14 without being recirculated.

[0051]

[0085] Closed-loop paths are particularly useful in clean room environments because they emit less particulate matter into the air. A second fan 152 and a second fan motor 154 are located in the upper portion of the second closed-loop air path 150. A water chiller 156 is located slightly downstream from the second fan 152 within the second closed-loop air path 150. The motherboard 60 and the channel module board 62, which form part of the slot assemblies 18A and 18B, are located within the lower half of the second closed-loop air path 150.

[0052]

[0086] In use, current is supplied to the second fan motor 154, causing the second fan 152 to rotate. The second fan 152 then recirculates the air in a clockwise direction through the second closed-loop air path 150. The air is cooled by the water cooler 156. The cooled air is then channeled over the motherboard 60 and channel module boards 62, resulting in heat being transferred by convection from the motherboard 60 and channel module boards 62 to the air.

[0053]

[0087] The air recirculating through the first closed-loop air path 120, Figure 2, is separated from the air in the second closed-loop air path 150, Figure 3, by the continuously sealed separator wall 112, shown in Figure 1. The continuously sealed front wall 104, shown in Figure 1, prevents air from leaking from the first closed-loop air path 120.

[0054]

[0088] 2 and 3, the same cooling system 240 used in Figure 1 is also used to cool the water chiller 126. As shown in Figure 4, a plenum 160 separates the first closed-loop air path 120 from the second closed-loop air path 150 in all areas except the area provided by the continuously sealed separator wall 112. The frame 14 has left and right walls 162, 164 that further define the closed-loop air paths 120 and 150.

[0055]

[0089] Figures 5A, 5B, and 5C illustrate how wafer packs 30C, 30D, and 30E can be inserted or removed at any time, while all other wafer packs are used to test wafer devices and are subject to various temperature gradients. Figure 6 illustrates the concept in more detail. At time T1, a first wafer pack is inserted into frame 14 while a second wafer pack is outside of frame 14. At T1, heating of the first wafer pack begins. Between T1 and T2, the temperature of the first wafer pack increases from room temperature, approximately 22°C, to a test temperature of 50°C to 150°C above room temperature at T2. At T2, power is applied to the first wafer pack, and the devices within the first wafer pack are tested. At T3, a second wafer pack is inserted into frame 14, and heating of the second wafer pack begins. At T4, testing of the first wafer pack ends. At T4, cooling of the first wafer pack also begins. At T5, the second wafer pack reaches the test temperature, power is applied to the second wafer pack, and the wafers in the second wafer pack are tested. At T6, the second wafer pack reaches a temperature near room temperature and is removed from frame 14. A third wafer pack can then be inserted in place of the first wafer pack. At T7, testing of the second wafer pack ends and cooling begins. At T8, the second wafer pack is cooled to room temperature or near room temperature and is removed from frame 14.

[0056]

[0090] Various tests can be performed at various temperatures. As an example, a wafer pack can be inserted and the test can proceed at room temperature. Another test can be performed while the temperature is increased. Further tests can continue at the increased temperature. Further tests can be performed while the temperature is decreased. Two of these tests can be a single test that continues from one temperature step to the next.

[0057]

[0091] As shown in Figure 7, one slot assembly 18A can be removed from or inserted into frame 14. While slot assembly 18A can be inserted or removed, other slot assemblies in frame 14 can be used to test wafer devices, as will be described with reference to Figure 6.

[0058]

[0092] Also shown in FIG. 8A are a signal distribution board 500, a contactor board 502, a plurality of wafer contact pins 504, a contactor retainer ring 506, fasteners 508 and support posts 510.

[0059]

[0093] Signal distribution board 500 is made primarily of insulating material and has circuitry (not shown) formed therein. Contacts 512 are formed on an underside 514 of signal distribution board 500. Threaded openings 516 are formed in underside 514.

[0060]

[0094] The contactor panel 502 has a plurality of pin openings 518, post openings 520, and fastener openings 522 formed therethrough from a top side 524 to a bottom side 526. Each one of the pin openings 518 has a first area 528 and a second area 530. The first and second areas 528 and 530 are both circular when viewed in a plan view. The first area 528 has a larger diameter than the second area 530. Because the diameter of the first area 528 is larger compared to the diameter of the second area 530, the first area 528 is wider than the second area 530 when viewed in the cross-sectional side view of FIG. 8A .

[0061]

[0095] The post opening 520 has a first section 534 and a second section 536. The first section 534 and the second section 536 are both circular when viewed in plan. The diameter of the first section 534 is larger than the diameter of the second section 536. Because the diameter of the first section 534 is larger than the diameter of the second section 536, the first section 534 is wider than the second section 536 when viewed in the cross-sectional side view of FIG. 8A . The first and second sections 534 and 536 have vertical sidewalls. A horizontal landing 538 connects the vertical sidewalls of the first and second sections 534 and 536.

[0062]

[0096] Each pin 504 includes a conductive retaining portion 542, a coil spring 544, and first and second end pieces 546 and 548. The first end piece 546 has a first inner portion 550 and a first tip 552. The second end piece 548 has a second inner portion 554 and a second tip 556. The coil spring 544 and the first and second inner portions 550 and 554 are retained by the retaining portion 542, with the coil spring 544 disposed between the first and second inner portions 550 and 554. The first and second tips 552 and 556 protrude from the upper and lower ends of the retaining portion 542, respectively.

[0063]

[0097] The upper surface of first tip 552 forms terminal 560. The lower end of second tip 556 forms contactor front contact 562. Coil spring 544 and first and second end pieces 546 and 548 are made of a metallic and therefore electrically conductive material. Coil spring 544 and first and second end pieces 546 and 548 form a conductor capable of conducting electrical current between terminal 560 and contactor front contact 562.

[0064]

[0098] Each pin is inserted through the top side 524 and into a respective pin opening 518. The second tip 556 is slightly narrower than the second section 530 so as to extend through the second section 530 and out the bottom side 526. The retention section 542 is slightly narrower than the first section 528 but wider than the second section 530 to prevent the pins 504 from slipping out the bottom side 526. When the pins 504 are fully inserted into the pin openings 518 and before the contactor board 502 is installed in the signal distribution board 500, the first tip 552 still protrudes above the top side 524 of the contactor board 502.

[0065]

[0099] The post 510 has a stand-off 564, a force transmission portion 566, and a force delivery portion 568. The post 510 is made from a single piece of metal or other material selected for its strength compared to the strength and brittleness of the ceramic material of the contactor board 502.

[0066]

[0100] The post 510 is inserted into the post opening 520 through the upper side 524. The standoff 564 and force transfer portion 566 are slightly narrower than the second section 536. The force transfer portion 568 is slightly narrower than the first section 534 but wider than the second section 536. A lower surface 570 of the force transfer portion 568 abuts the landing 538. This prevents the post 510 from slipping out of the underside 526.

[0067]

[0101] Post 510 has a surface 572 that lies in a plane parallel to and below the surface of lower side 526 when post 510 is fully inserted, as shown in Figure 8A. Force-delivery portion 568 has a surface 574 that lies in the same plane as upper side 524 when post 510 is fully inserted.

[0068]

[0102] Signal distribution board 500 is positioned on top of contactor board 502. Each one of contacts 512 contacts a respective one of terminals 560. Lower side 514 is initially spaced apart from upper side 524 because terminals 560 lie in a plane above the plane of upper side 524.

[0069]

[0103] Fastener 508 has a threaded shaft 578 and a head 580. Contactor retainer ring 506 has a ring opening 582. Contactor retainer ring 506 is positioned on the underside 584 of contactor board 502. Threaded shaft 578 passes through ring opening 582 from the bottom and then through fastener opening 522. Head 580 contacts the underside of contactor retainer ring 506. Head 580 is rotated, causing the threads of threaded shaft 578 to thread into the threads of threaded opening 516. The threading action brings signal distribution board 500 closer to contactor board 502 and contactor retainer ring 506. Underside 514 eventually contacts upper side 524. Contacts 512 lower first end piece 546 into pin opening 518 until terminals 560 are flush with upper side 524. The coil spring 544 compresses and therefore deforms slightly, allowing relative movement of the first end piece 546 towards the second end piece 548 .

[0070]

[0104] The underside 514 has an area that rests against a surface 574 that forms part of the mast 510. The mast 510 abuts the signal distribution board 500 and is therefore in a position to transmit forces through the surface 574 to the signal distribution board 500.

[0071]

[0105] The first wafer 32A has a plurality of electronic devices formed thereon, each having a plurality of terminals 588 on a top surface 590 of the first wafer 32A. When the backplate 74 and the first wafer 32A are brought together, the first wafer 32A, aligned with the backplate 74, ensures that each one of the terminals 588 contacts each one of the contactor front contacts 562.

[0072]

[0106] A vacuum pressure is created in the region between upper surface 590 and underside 526, while the pressure below lower surface 592 of wafer chuck 72 and at upper surface 594 of signal distribution board 500 remains at atmospheric pressure. The pressure differential generates equal and opposite forces F1 and F2 on signal distribution board 500 and on wafer chuck 72.

[0073]

[0107] As shown in FIG. 8B , forces F1 and F2 cause relative movement of the backplate 74 toward the first wafer 32A and wafer chuck 72. The coil springs 544 further compress, allowing the second end pieces 548 to move into the pin openings 518. Each coil spring 544 deforms against its spring force, e.g., F3. However, force F1 is still greater than the sum of all forces F3 combined. The top surface 590 ultimately rests on the surface 572 of the standoff 564. Because the support posts 510 abut against the signal distribution board 500, the standoff 564 prevents the top surface 590 from approaching and contacting the underside 526 of the contactor board 502. The first wafer 32A transmits force F4 to the standoff 564. The force transmitting portion 566 transmits force F4 through the second section 536 of the support post opening 520. Force delivery portion 568 receives force F4 from force transmission portion 566 and delivers force F4 to signal distribution board 500 via surface 574.

[0074]

[0108] It can thus be seen that force F4 is not transmitted through contactor board 502, thereby preventing stresses that could damage the brittle ceramic material of contactor board 502. Instead, force F4 is transmitted directly from the electronics in the form of first wafer 32A through support posts 510 to signal distribution board 500.

[0075]

[0109] 8A and 8B, a contactor board 502 serves as a support plate having post openings 520 therethrough. A signal distribution board 500 serves as a backing structure including at least a circuit board on a first side of the support plate and having contacts 512. Pins 504 serve as conductors having contactor front contacts 562 for contacting terminals 588 on electronic equipment positioned on a second side of the support plate opposite the first side of the support plate. A retainer 542 serves as part of the conductor retained by the support plate. The conductor further has terminals 560 that connect to the contacts 512 on the signal distribution board 500. A spring 544 in the form of a coil spring is provided. The wafer chuck 72 serves as a force-generating device for the electronics in the form of the first wafer 32A opposite the support plate. The force-generating device and the support plate are movable relative to one another to move the electronics closer to the support plate and to deform the springs. The support post 510 has a standoff 564 with a surface 572 located in a plane spaced apart from the plane of the surface of the support plate, and a force-transfer portion 566 extending from the standoff 564 and at least partially through the support post opening 520 to a force-transfer portion 568, which is held by a backing structure.

[0076]

[0110] 9A shows a portion of tester apparatus 10 that is used to insert and remove wafer packs into and from each slot assembly, such as slot assembly 18A. The components of tester apparatus 10 shown in FIG. 9A are stationary structural components, including frame 300, a portion of first slot assembly 18A, first slot assembly connecting portion 40, retaining structure 302, horizontal transfer device 304, vertical transfer device 306, push bar vanes 308, and locking device 310.

[0077]

[0111] Frame 300 includes first and second spaced apart mounts 312 and 314. Horizontal transfer device 304 is a slide mounted between first and second mounts 312 and 314. Retaining structure 302 is mounted for sliding movement along horizontal transfer device 304. Opposite ends of push bar vanes 308 are mounted to first and second mounts 312 and 314, respectively.

[0078]

[0112] The locking device 310 includes a connecting lever 316, a control lever 318, and a pressure lever 320. The control lever 318 attaches to the first mount 312 at a pivot connection 322. The vertical transfer device 306 is a rigid beam. A connection 324 connects the vertical transfer device 306 and the pushrod vane 308 at their center points. The pressure lever 320 has a first link 326 rotatably connected to the control lever 318 and a second link 328 rotatably connected to the end of the vertical transfer device 306. In the unlocked configuration shown in FIG. 9A , a line 330 connects the pivot connection 322 to the second link 328, with the first link 326 to the left of the line 330.

[0079]

[0113] In use, the first wafer pack 28A is placed on the holding structure 302. The first wafer pack 28A then moves from left to right along with the holding structure 302 into the first slot assembly 18A. The placement and movement of the first wafer pack 28A can be performed manually or using a robot.

[0080]

[0114] The retaining structure 302 slides along the horizontal transfer device 304. A connecting lever 316 connects an end of a control lever 318 to the retaining structure 302. As the retaining structure 302 moves horizontally along the horizontal transfer device 304, the connecting lever 316 causes the control lever 318 to rotate counterclockwise about the pivot connection 322.

[0081]

[0115] The first link 326 rotates counterclockwise with the control lever 318. The pressure lever 320 converts the movement of the first link 326 into downward movement of the second link 328. Initially, the downward movement is minimal, but once the first wafer pack 28A is fully inserted into the first slot assembly 18A, the vertical movement becomes more significant and the vertical transport device 306 engages the first wafer pack 28A with the first slot assembly 18A. The horizontal transfer device 304 is therefore operable to move the first wafer pack 28A horizontally from a first position to a second position into the first slot assembly 18A, and the vertical transfer device 306 is operable to move the first wafer pack 28A and the first slot assembly 18A relative to each other in a first vertical direction so that the slot assembly connection portion 40 engages with the wafer pack connection portion on the first wafer pack 28A.

[0082]

[0116] The control lever 318 is shown in FIG. 9A in an unlocked position, in which the first link 326 is on a first side of a line 330 connecting the pivot connection 322 and the second link 328. As the control lever 318 rotates from the unlocked position shown in FIG. 9A through a compressed position, the push bar vane 308 is deflected by the vertical transfer device 306 through connection 324, bending the push bar vane 308 against its spring force, and the first link 326 is aligned with the pivot connection 322 and the second link 328. As shown in FIGS. 9B and 10, the control lever 318 continues to rotate from the compressed position to the locked position. In the locked position, the first link 326 is to the right of the line 330, and therefore on a second side of the line 330 opposite the first side. As the first link 326 passes through the wire 330 and the push bar vane 308 deforms against its spring force, the first wafer pack 28 A is locked in place relative to the slot assembly connecting portion 40 .

[0083]

[0117] The system can be unlocked by moving the retaining structure 302 from right to left. The control lever 318 rotates clockwise, and the first link 326 moves from right to left past the line 330. The vertical transfer device 306 moves upward, i.e., in a second vertical direction opposite the first vertical direction, to release the first wafer pack 28A from the slot assembly connection portion 40. Further movement of the retaining structure 302 along the horizontal transfer device 304 removes the first wafer pack 28A from the slot assembly connection portion 40.

[0084]

[0118] 11 and 12 show further components of the first wafer pack 28A, including a pressure reducing check valve 600, a vacuum relief check valve 602, latch system components including first, second, third and fourth latch assemblies 604A to 604D, and an electrical pressure sensor connection 606 that forms part of a pressure monitoring system.

[0085]

[0119] 11 and 12. A pressure reduction passage 608 is formed in the back plate 74. The pressure reduction passage 608 has an outlet opening 610 and an intermediate location 612 arranged in the same plane. The outlet opening 610 is connected to the pressure reduction check valve 600. The intermediate location 612 is closer to the center point of the back plate 74 than the outlet opening 610. The pressure reduction passage 608 is formed by first drilling four passages in the back plate 74 and then closing one end of three of the passages, so that the resulting pressure reduction passage 608 is completely isolated from atmospheric pressure outside the back plate 74.

[0086]

[0120] FIG. 14 is a cross-sectional view taken along line 14-14 of FIG. 13. The pressure reduction passage 608 extends downward from the intermediate arrangement 612 through the back plate 74 and the signal distribution board 500. The pressure reduction passage 608 has an inlet opening 624 that communicates with the pressure differential cavity 622. The lip seal 77 is disposed within a recess in the wafer chuck 72. The pressure differential cavity 622 is jointly formed by the wafer chuck 72, the contactor board 502, and the contactor retainer ring 506, which form the lower side of the pressure differential cavity 622; the signal distribution board 500, which form the upper side of the pressure differential cavity 622; and the lip seal 77, which forms the connection between the upper and lower sides of the pressure differential cavity 622. The lip seal 77 is perfectly circular and completely surrounds the contactor board 502 and the wafer disposed between the contactor board 502 and the wafer chuck 72.

[0087]

[0121] 14 form a portable support structure 626. The portable support structure 626 has a first component 628 including the signal distribution board 500 and the backplate 74, and a second component 630 including the wafer chuck 72.

[0088]

[0122] In use, the first component 628 separates from the second component 630. The wafer is then placed on the wafer chuck 72. The first component 628 is then positioned over the second component 630. The upper edge of the lip seal 77 contacts the signal distribution board 500. The wafer is thus held within the portable support structure 626.

[0089]

[0123] 13 and 14 in combination, a pump is connected to the pressure-reducing check valve 600. The pressure-reducing check valve 600 is then opened. The pressure-reducing passage 608 can initially be at atmospheric pressure, after which the pump reduces the pressure in the pressure-reducing passage 608. The pressure differential cavity 622 is exposed to a pressure lower than atmospheric pressure. The outer surface of the first wafer pack 28A remains exposed to atmospheric pressure. As a pressure differential is created between the pressure differential cavity 622 and the outer surface of the first wafer pack 28A, the spring in the contactor board 502 compresses, as described above with reference to FIG. 8B. The lip seal 77 is made of a resilient elastomeric material, which causes the lip seal to compress against its spring force. As the lip seal 77 compresses against its spring force, an improved seal is formed between the lip seal 77 and the signal distribution board 500, thereby maintaining pressure in the pressure differential cavity 622. The pressure-reducing check valve 600 is then closed, thereby isolating the pressure-reducing passage 608 from the outside atmospheric pressure. The pump can then be disconnected from the pressure-reducing check valve 600.

[0090]

[0124] The first wafer pack 28A, with wafers loaded therein, can now be moved within the assembly environment without being connected to a pump or tester. If the wafers need to be removed later, positive pressure can be applied to the vacuum relief check valve 602 shown in FIGS. 11 and 12. The vacuum relief check valve 602 is spring-loaded, requiring a predetermined amount of pressure to be applied before it opens. Air can then flow through the vacuum relief passage in the backplate 74 into the pressure differential cavity 622, bringing the pressure differential cavity 622 to atmospheric pressure. The first and second components 628 and 630 can then be separated from each other, and the wafers can be removed. When the first wafer pack 28A is loaded with new wafers and the pressure in the pressure differential cavity 622 needs to be reduced using the pressure reduction check valve 600, the vacuum relief check valve 602 then closes.

[0091]

[0125] Figure 15 is a cross-sectional view taken along line 15-15 of Figure 12. The first latch assembly 604A includes a first part 640, a second part 642, a connecting part 644, an engagement mechanism 646, a matching block 648, a lock nut 650, a spacer 652A, a shim 652B, and a snap mechanism 654.

[0092]

[0126] First piece 640 and connecting piece 644 are machined from one piece and are therefore secured together. First piece 640 has a length 660 and a width 662. Only half of width 662 is shown in cross section. Length 660 is greater than width 662. Length 660 is greater than the diameter of connecting piece 644. First piece 640 has a tool pin opening 664 formed therein.

[0093]

[0127] Second component 642 has a body 666 and first and second winglets 668A and 668B extending from body 666. Second component 642 has a length 670, which includes winglets 668A and 668B, and a width 672. Only half of width 672 is visible in the cross-sectional view. Because first and second winglets 668A and 668B form part of length 670 but not part of width 672, length 670 is much greater than width 672. Body 666 further has an opening 674 through which connecting component 644 can be inserted.

[0094]

[0128] The connecting piece 644 includes a first portion 678 and a second portion 680. The second portion 680 has external threads formed thereon.

[0095]

[0129] The engagement feature 646 is formed by opposing surfaces that define a width 662 of the first part 640. The opposing surfaces that form the engagement feature 646 are parallel to one another, which facilitates engagement between parallel surfaces on the jaws of a tool that may rotate the first part 640.

[0096]

[0130] Harmonic block 648 is attached to spacer 652A in a fixed position. Wafer chuck 72 includes metal portion 682 and protective piece 684. Protective piece 684 forms a shoulder 686 on wafer chuck 72. Shim 652B is positioned between spacer 652A and signal distribution board 500. Only a single shim 652B is shown. Additional shims are inserted, typically one above the other, until leveling surface 690 of harmonic block 648 is at the same vertical height as shoulder 686.

[0097]

[0131] The snap mechanism 654 includes a retainer body 694, a spherical ball 696, and a spring 698. The body 666 of the second part 642 forms part of the snap mechanism 654 because the body 666 has a first snap recess 700A formed therein.

[0098]

[0132] The retainer body 694 has an outer surface with threads 702. The retainer body 694 further has an end with a slot 704 formed therein, which can receive a tool such as a screwdriver. A spring 698 is disposed within the retainer body 694. A spherical ball 696 is positioned within the mouth of the retainer body 694. The mouth of the retainer body 694 is slightly reduced in size to prevent the spherical ball 696 from slipping out of the retainer body 694. The outer surface of the spherical ball 696 forms a snap surface 706. The threads 702 engage complementary threads in the matching block 648. A tool such as a screwdriver is inserted into the slot 704 and then rotated to adjust the spacing of the snap surface 706 from the matching block 648.

[0099]

[0133] The intermediate protective component 708 is inserted into a complementary recess in the upper surface of the back plate 74. Openings 710, 712, and 714 are formed in the intermediate protective component 708, the back plate 74, and the signal distribution board 500, respectively. The second portion 680 of the connection component 644 is inserted through the openings 710, 712, and 714 from above. The length 660 of the first component 640 is greater than the length of any one of the openings 710, 712, and 714 in the same direction, thereby preventing the first component 640 from entering the openings 710, 712, and 714. The lower surface of the first component 640 rests on the upper surface formed in the intermediate protective component 708. The first portion 678 of the connection component 644 is then placed in the openings 710, 712, and 714, and the second portion 680 of the connection component 644 is placed below the openings 710, 712, and 714. The spring loaded washer 720, shim 652B and spacer 652A are then positioned from below over the connecting piece 644. The second piece 642 is then positioned from below over the connecting piece 644. The opening 674 forms a snug fit with the outer diameter of the threads on the second portion 680 of the connecting piece 644.

[0100]

[0134] As the second part 642 slides upward over the connecting part 644, the first snap recess 700A also contacts the snap surface 706. The spherical ball 696 moves a small distance from right to left against the force of the spring 698. The lock nut 650 then engages the protruding end of the second part 680. Rotating the lock nut 650 tightens the body 666 of the second part 642 against the spring force of the washer 720. A feeler gauge or other tool can be used to determine the clearance between the second wing 668B and the leveling surface 690. The lock nut 650 can be rotated until an acceptable clearance is formed between the second wing 668B and the leveling surface 690. This clearance will generally be the same as the desired clearance between the first wing 668A and the shoulder 686. Thus, the first part 640, the second part 642 and the connecting part 644 form a locking mechanism.

[0101]

[0135] As the lock nut 650 is rotated, the first snap recess 700A also moves upward. The first snap recess 700A is an elongated slot. Thus, the snap surface 706 and the first snap recess 700A can slide over each other as the second part 642 continues to move upward with continued rotation of the lock nut 650.

[0102]

[0136] As shown in the drawings, the wafer chuck 72 is in place while the first latch assembly 604A is assembled. Additionally, a negative pressure exists in the pressure differential cavity 622. By placing the first wafer pack 28A in compression, it is possible to measure whether the first and second wing pieces 668A and 668B are equally spaced from the shoulder 686 and the leveling surface 690. If the leveling surface 690 is set to the correct height using one or more shims, such as shim 652B, the first latch assembly 604A can also be assembled without the wafer chuck 72 in place by simply measuring the spacing between the second wing piece 668B and the leveling surface 690.

[0103]

[0137] FIG. 16 is a view seen from the direction A in FIG. 15, but shows only the connection part 644 and the signal distribution board 500.

[0104]

[0138] The opening 712 has a first dimension 724 along an axis 726 toward a center point of the signal distribution board 500 that is greater than a second dimension 728 transverse to the axis 726. In the direction of the axis 726, a first portion 678 of the connecting piece 644 is smaller than the first dimension 724 to allow for thermal expansion of the signal distribution board 500 and the back plate 74 (see FIG. 15 ) relative to one another. The first portion 678 is dimensioned to slidably fit within the second dimension 728 to prevent movement of the signal distribution board 500 relative to the back plate 74 in a direction transverse to the axis 726.

[0105]

[0139] The second portion 680 of the connecting piece 644 has a first thickness 730 and a second thickness 732. The first thickness 730 is capable of fitting into the opening 712 along the axis 726 and is larger than the second dimension 728 of the opening 712. The second thickness 732 is transverse to the first thickness 730 and is capable of fitting into the second dimension 728 of the opening 712. Because the second dimension 728 is relatively large, a thread can be formed thereon and still be relatively strong. The entire second portion 680 is positioned below the opening 712, which allows the connecting piece 644 to rotate about its longitudinal axis without the second portion 680 hitting the relatively narrow opening 712. The first portion 678 has a circular cross-section whose diameter is less than or equal to the second dimension 728, which allows the first portion 678 to rotate freely within the relatively narrow second dimension 728 of the opening 712.

[0106]

[0140] An additional opening 734 is formed in the signal distribution board 500 to further fasten one or more shims. The opening 734 is similarly proportioned to the opening 712, with a longer dimension along an axis 736 toward the center point of the signal distribution board 500. The fasteners passing through the opening 734 do not need to rotate when used in an assembly environment, and the size of the opening 734 only serves to allow for thermal expansion of the signal distribution board 500 relative to the back plate 74.

[0107]

[0141] Figure 17 is a cross-sectional view taken along line 17-17 of Figure 15. Fasteners 740 are inserted through openings 734 shown in Figure 16 to secure spacers 652A and shims 652B to backplate 74. Fasteners 740 include a bolt and nut with the bolt head on one side and the nut on the other side.

[0108]

[0142] The body 666 has a circular outer surface 742 with first, second, third, and fourth snap recesses 700A-700D formed therein. The snap surface 706 of the spherical ball 696 is positioned within the first snap recess 700A, thereby preventing the body 666 from rotating. The opening 674 in the body 666 is keyed to receive the shape of the second part 680, such that the second part 680 cannot rotate when the body 666 is stationary.

[0109]

[0143] A small torque is required to rotate the body 666 and eject the spherical ball 696 from the first snap indentation 700A. When the body 666 rotates clockwise, the snap surface 706 rests on the circular outer surface 742 between the first snap indentation 700A and the second snap indentation 700B. As the body 666 rotates, the second portion 680 rotates with the body 666 through the same angle. As the body 666 approaches 90 degrees of rotation, the snap surface 706 snaps into the second snap indentation 700B. The second snap indentation 700B then resists rotation of the body 666 and second portion 680. The first through fourth snap indentations 700A through 700D lightly lock the body 666 at four different rotational angles, including 0, 90, 180, and 270 degrees.

[0110]

[0144] FIGS. 18A(i) and 18A(ii) show views from the direction of arrows A and B shown in FIG. 15 with the locking mechanism rotated to the unlocked position. The operator can compare the orientation of the first part 640 with the reference 750 on the top surface of the wafer chuck 72, which indicates that the first latch assembly 604A is unlocked in FIG. 18A(ii). The shoulder 686 is not obstructed from below by either the first wing 668A or the second wing 668B. The wing pieces 668A and 668B are held in the position shown in FIG. 18A(i) by the snap mechanism 654 shown in FIGS. 15 and 17. With the pressure released within the first wafer pack 28A, the wafer chuck 72 can be removed for inserting or converting wafers. After converting the wafers, the pressure within the first wafer pack 28A is again released, and the first wafer pack 28A is held together.

[0111]

[0145] When the first wafer pack 28A is fully assembled, an additional fail-safe may be required to maintain electrical contact with the wafers even if a system failure prevents the negative pressure within the first wafer pack 28A from being maintained. An operator may use a tool (not shown) having jaws and pins. The pins are inserted into the tool pin openings 664. The tool pin openings 664 are tapered, so that the further the pins are inserted into the tool pin openings 664, the better the tool aligns with the first component 640. The operator then engages the opposing parallel surfaces of the tool's jaws with the opposing parallel surfaces formed by the engagement feature 646. Once the tool engages the engagement feature 646, the operator rotates the tool, which rotates the first component 640. The connecting component 644 and the second component 642, together with their first and second wings 668A and 668B, rotate with the first component 640. 17, the snap surface 706 slides away from the fourth snap recess 700D over the circular outer surface 742. The snap surface 706 then snaps into the first snap recess 700A.

[0112]

[0146] 18B(i) and 18B(ii) show the first latch assembly after the first and second parts 640 and 642 have been rotated through a 90-degree angle. The operator can verify that the orientation of the first part 640 is aligned with the locked position, as indicated by datum 750. The first wing 668A is now positioned above the shoulder 686, preventing the wafer chuck 72 from moving vertically downward and away from the remainder of the wafer pack 28A. The second wing 668B is positioned above the matching block 648. The first wing 668A can be disengaged from the shoulder 686 by rotating the first part 640 through a 90-degree angle in either a clockwise or counterclockwise direction. Either wing 668A or 668B can be used to lock the wafer chuck 72 in place.

[0113]

[0147] 19 shows how one or more shims 652B-652F can be used to adjust the height of the leveling surface 690 of the matching block 648. Ideally, the matching block 648 should be flush with the shoulder 686. Because the matching block 648 is attached to the spacer 652A, it moves up and down with the spacer 652A as more shims 652B-652F are inserted. If the leveling surface 690 is below the shoulder 686, more shims can be inserted to raise the leveling surface 690, or if the leveling surface 690 is above the height of the shoulder 686, a shim can be removed.

[0114]

[0148] The engagement feature 646 is conveniently located directly on the first component 640. In alternative configurations, the engagement feature can be formed directly on the second component 642 or directly on the connecting component 644.

[0115]

[0149] In further embodiments, the engagement feature can be a feature separate from the first and second parts 640 and 642 and separate from the connecting part 644. For example, a worm gear can be formed on the connecting part 644 and the engagement feature can be a separate rotatable feature that rotates the worm gear.

[0116]

[0150] The engagement mechanism can also be located between the first part 640 and the connecting part 644. For example, the first winglet 668A can be pivoted downwardly away from and back toward the shoulder 686 using a cam system located between the first part 640 and the connecting part 644. Alternatively, a cam system can be located between the connecting part 644 and the second part 642 to serve as the engagement mechanism. Alternatively, the connecting part 644 can be made of two parts, and the engagement mechanism can connect the two parts and adjust the spacing between them, which allows the winglet to pivot.

[0117]

[0151] The first latch assembly 604A uses primarily incompressible and inflexible materials. In alternative embodiments, straps or other flexible materials may be used, with the same or similar materials in mind.

[0118]

[0152] Instead of having the engagement feature 646 on the exterior surface of the first component 640, the engagement feature can instead be located on the interior surface of either component.

[0119]

[0153] 12 , the first, second, third, and fourth latch assemblies 604A through 604D are identical except for their respective locations and orientations. The first and third latch assemblies 604A and 604C are on opposite sides of the wafer chuck 72, and the second and fourth latch assemblies 604B and 604D are on opposite sides of the wafer chuck 72. The latch assemblies 604A through 604D are positioned on more than one side of the wafer chuck 72, i.e., they cover 180 degrees or more around the edge of the wafer chuck 72, so that the four latch assemblies can collectively hold all sides of the wafer chuck 72 in place around the entire edge of the wafer chuck 72.

[0120]

[0154] The latching system provided by the first, second, third, and fourth latch assemblies 604A-604D facilitates easy movement of the first wafer pack 28A through the assembly environment without the need for human supervision. Without the latching system, human supervision may be required to determine when the wafers 28A break apart due to a lack of negative pressure within the first wafer pack 28A. The latching system provides a structural fail-safe to prevent the first wafer pack 28A from breaking apart, even if air is introduced from the outside.

[0121]

[0155] Figures 20, 21, 22A and 22B show various further components of the pressure monitoring system, including a pressure sensing passage 760 (Figure 21), a pressure sensor 762 (Figures 22A and 22B), the electrical pressure sensor connection 606 described with reference to Figure 11 (Figures 20, 21, 22A and 22B), an electrical pressure connector connection 764, a mounting bracket 766, a ribbon cable 768 having first and second connectors 770 and 772 at opposite ends (Figures 20, 22A and 22B), a connector block 774, and a stiffener plate 776 (Figure 20).

[0122]

[0156] The pressure sensing passage 760 is formed in the back plate 74 in a manner similar to the reduced pressure passage 608 described with reference to Figure 13. The pressure sensing passage 760 has a first end within the pressure differential cavity 622 shown in Figure 14. The pressure sensing passage 760 has a second end opposite the first end near the outer edge of the back plate 74.

[0123]

[0157] The electrical pressure sensor connection portion 606 is in the form of a printed circuit board having a substrate 780 and a plurality of contacts including first, second and third contacts 782A, 782B and 782C formed on the substrate 780.

[0124]

[0158] The pressure sensor 762 is mounted on the substrate 780, i.e., on the side of the substrate 780 opposite the first, second, and third contacts 782A, 782B, and 782C. The pressure sensor 762 is electrically connected to the first, second, and third contacts 782A, 782B, and 782C through the substrate 780. The pressure sensor 762 can sense the pressure of a gas, in this case air, and convert the pressure into an electrical signal, with the magnitude of the pressure indicated by the signal magnitude or another variable. Pressure can conveniently be detected using a diaphragm that displaces a known distance as pressure increases or decreases. Other pressure sensors, such as pressure sensors using piezoelectric crystals or pressure sensors using stress gauges, are also within the scope of the invention. In the case of a movable diaphragm, the movement can be converted into a voltage, for example by moving an induction coil, and the magnitude then indicates the displacement and therefore the pressure. The pressure sensor can be, for example, the MLX90809 sold by Melexis (www.melexis.com). The electrical pressure sensor interface 606 is attached to the backplate 74 using fasteners 784. The diaphragm of the pressure sensor 762 is then exposed to air at the second end of the pressure sensing passage 760. The pressure sensor 762 can therefore sense the pressure within the pressure differential cavity 622.

[0125]

[0159] The electrical pressure connector interface 764 has a base plate 790 and a plurality of terminals, including first through sixth terminals 792A through 792F, secured to the base plate 790. The base plate 790 is attached to a mounting bracket 766 via fasteners 794. A stiffener plate 776 is secured between the two push bar vanes 308. The mounting bracket 766 is secured to the stiffener plate 776 using fasteners 796. The slot assembly body 32, together with the push bar vanes 308 and the stiffener plate 776, form part of a stationary structure, and thus the electrical pressure connector interface 764 is attached to the stationary structure.

[0126]

[0160] Connector block 774 attaches to slot assembly body 32. Connectors 770 and 772 are connected to electrical pressure connector interface 764 and connector block 774, respectively. First through sixth terminals 792A through 792F are connected to the pressure sensing board of the electrical tester by first connector 770, ribbon cable 768 and second connector 772.

[0127]

[0161] 23A and 23B show the engagement between the electrical pressure sensor interface 606 and the electrical pressure connector interface 764 when the first wafer pack 28A is inserted into the slot assembly. The first, second, and third contacts 782A, 782B, and 782C initially contact the first, second, and third terminals 792A, 792B, and 792C, respectively. As the electrical pressure sensor interface 606 moves further, the first, second, and third contacts 782A, 782B, and 782C engage the fourth, fifth, and sixth terminals 792D, 792E, and 792F, respectively. Thus, the first contact 782A contacts both the first terminal 792A and the fourth terminal 792D. Similarly, each one of contacts 782B and 782C contacts two of terminals 792B, 792C, 792E and 792F.

[0128]

[0162] Terminals 792A through 792F can be resiliently depressed against substrate 790 to ensure proper contact with contacts 782A through 782C. Ribbon cable 768 allows stiffener plate 776 to move slightly relative to slot assembly body 32 when first wafer pack 28A is inserted.

[0129]

[0163] While the wafer is being tested, the pressure within pressure differential cavity 622 can be monitored throughout the process. If a wafer fails to test, the tester can be programmed to determine if such test is due to insufficient negative pressure within pressure differential cavity 622.

[0130]

[0164] Figure 24 shows other components of the tester apparatus 10 and slot assemblies 18A and 18B. Figure 24 also shows other components present in the manufacturing environment, such as a nitrogen gas tank 802, a dielectric gas tank 804, and a vacuum pump 806. The nitrogen gas tank 802 and vacuum pump 806 represent nitrogen gas lines and vacuum lines present in the manufacturing environment.

[0131]

[0165] The tester apparatus 10 includes a first nitrogen gas pressure regulator 810 and three manifolds 812, 814, and 816. The slot assembly 18A has three couplings 820A, 822A, and 824A. Similarly, the slot assembly 18B has three couplings 820B, 822B, and 824B.

[0132]

[0166] In use, when slot assembly 18A is inserted into tester fixture 10, couplings 820A, 822A, and 824A connect to manifolds 812, 814, and 816. When slot assembly 18B is inserted into tester fixture 10, couplings 820B, 822B, and 824B simultaneously engage manifolds 812, 814, and 816. Couplings 820A and 820B connect slot assemblies 18A and 18B to nitrogen gas pressure regulator 810 via manifold 814. First nitrogen gas pressure regulator 810 is connected to nitrogen gas tank 802 via a nitrogen gas inlet supply. Couplings 822A and 822B connect slot assemblies 18A and 18B to dielectric gas tank 804 via manifold 814 and a dielectric gas inlet supply. Couplings 824 A and 824 B connect slot assemblies 18 A and 18 B through manifold 816 to vacuum pump 806 , which then applies a vacuum to manifold 816 .

[0133]

[0167] Slot assemblies 18A and 18B are similar, and for ease of explanation, only the other components of slot assembly 18A will be described, but it should be understood that slot assembly 18B has similar components.

[0134]

[0168] Slot assembly 18A further includes a second nitrogen gas pressure regulator 830, a dielectric gas pressure regulator 834, an inlet orifice 838, an outlet orifice 840, a vacuum regulator 844, and a heater control board 848. Second nitrogen gas pressure regulator 830 and dielectric gas pressure regulator 834 are connected to couplings 820A and 822A, respectively. Inlet orifice 838 is connected to second nitrogen gas pressure regulator 830 and dielectric gas pressure regulator 834.

[0135]

[0169] The first wafer pack 28A has a gas supply valve 850 connected to the inlet orifice 838. The gas supply valve 850 is similar to the vacuum relief check valve 602, except that it operates at a different pressure. A gas supply passage 852 has an inlet connected to the gas supply valve 850 and an outlet at the pressure differential cavity 622 shown in FIG. 14 .

[0136]

[0170] Outlet orifice 840 is connected to pressure reducing check valve 600. Outlet orifice 840 is connected through vacuum regulator 844 to coupling 824A.

[0137]

[0171] The heater control board 848 is connected to the electrical pressure sensor interface 606 and is connected to the second nitrogen gas pressure regulator 830, the dielectric gas pressure regulator 834, and the vacuum regulator 844. The heater control board 848 controls the second nitrogen gas pressure regulator 830, the dielectric gas pressure regulator 834, and the vacuum regulator 844 based on input from the electrical pressure sensor interface 606.

[0138]

[0172] In use, the heater control board 848 opens the vacuum regulator 844. The vacuum created by the vacuum pump 806 is then applied to the pressure-reducing check valve 600, opening it. The heater control board 848 maintains the dielectric gas pressure regulator 834 in a closed state. The heater control board 848 then opens the second nitrogen gas pressure regulator 830. Nitrogen gas then flows from the nitrogen gas tank 802 through the nitrogen gas inlet supply, the nitrogen gas pressure regulator 810, the manifold 812, the coupling 820A, the second nitrogen gas pressure regulator 830, the inlet orifice 838, the gas supply valve 850, and the gas supply passage 852 to the pressure differential cavity 622. The nitrogen gas then fills pressure differential cavity 622, thereby displacing all air within pressure differential cavity 622 through pressure reducing check valve 600, outlet orifice 840, vacuum regulator 844, coupling 824A and vacuum pump 806. Referring also to Figure 8B, the nitrogen gas then fills the space between contactor front contacts 562.

[0139]

[0173] 24 , heater control board 848 then closes second nitrogen gas pressure regulator 830 and opens dielectric gas pressure regulator 834. Dielectric gas then flows from gas tank 804 through dielectric gas inlet supply, manifold 814, coupling 822A, dielectric gas pressure regulator 834, inlet orifice 838, gas supply valve 850, gas supply passage 852, pressure differential cavity 622, pressure-reducing check valve 600, outlet orifice 840, vacuum regulator 844, coupling 824A, and vacuum pump 806. The direction of dielectric gas flow across pressure differential cavity 622 is indicated by arrow 858. The flow rate of the dielectric gas is controlled by the size of inlet orifice 838 and outlet orifice 840.

[0140]

[0174] Once the space between the contactor front contacts 562, shown in FIG. 8B, is filled with dielectric gas, the heater control board 848 partially closes the dielectric gas pressure regulator 834 and the vacuum regulator 844 to reduce the flow rate of the dielectric gas. The flow rate of the dielectric gas is low, only enough to compensate for the dielectric gas leaking from the pressure differential cavity 622. Throughout the process of introducing the nitrogen gas and the dielectric gas into the pressure differential cavity 622, the heater control board 848 controls the vacuum regulator 844 to maintain the negative pressure created to compress the coil spring 544, as shown in FIG. 8B.

[0141]

[0175] The dielectric gas is selected to reduce arcing between the contactor front contacts 562 shown in FIG. 8A compared to air. Examples of gases that can be used as the dielectric gas include Novec® 4710 insulating gas sold by 3M and commercially available octafluorocyclobutane. Both of these gases have higher dielectric constants and dielectric strengths than air, thereby reducing arcing compared to air. Therefore, more power can be delivered through the contactor front contacts 562 when testing the first wafer 32A, as shown in FIG. 8B. After testing is complete, the dielectric gas is replaced with nitrogen gas, and the above procedure is reversed, allowing the first wafer pack 28A to be removed from the slot assembly 18A. Throughout the process, excess nitrogen and dielectric gases are removed from the first wafer pack 28A through the outlet orifice 840, vacuum regulator 844, coupling 824A, and vacuum pump 806. A manufacturing facility may have a gas purifier that separates the gases after they leave the vacuum pump 806. Another manufacturing facility may have a cryogenic pump that separates the gas after it leaves the tester apparatus 10 and before it enters the vacuum pump 806 .

[0142]

[0176] As mentioned above, each slot assembly 18A, 18B, etc. has its own heater control board 848 and other similar components. The heater control board 848 independently controls the introduction of nitrogen gas and dielectric gas to the contacts of each first wafer pack 28A, second wafer pack 28B, etc.

[0143]

[0177] Figure 25 is a plan view of slot assembly 18A holding first wafer pack 28A. Figure 26 is a cross-sectional view taken along lines 26A-26B in Figure 25. Figure 27 is a cross-sectional view taken along lines 27A-27B in Figure 25.

[0144]

[0178] Figures 28 and 29 are detailed views of the areas marked "C" and "D" in Figures 26 and 27, respectively. Figure 28 shows horizontal transfer device 304, push rod vanes 308, and back plate 74, with back plate 74 having vacuum passage 608 formed therein. Figure 28 also shows gas removal conduit 828 fixed to horizontal transfer device 304. Gas removal conduit 828 has a stationary gas removal connection portion 832. Back plate 74 has a portable gas removal connection portion 836.

[0145]

[0179] In use, the stationary structure gas removal connection portion 832 and the portable structure gas removal connection portion 836 are separated from each other. As described with reference to FIG. 1, the wafer chuck 72 is moved downward into contact with the thermal chuck 34. The stationary structure gas removal connection portion 832 moves downward to engage the portable structure gas removal connection portion 836. A seal seals the stationary structure gas removal connection portion 832 and the portable structure gas removal connection portion 836. Thus, the reduced pressure passage 608 extends from the back plate 74 through the gas removal conduit 828. A vacuum, as shown in FIGS. 24 and 28, can be applied to the reduced pressure passage 608 through the gas removal conduit 828.

[0146]

[0180] FIG. 29 shows horizontal transfer device 304, push rod vanes 308, and back plate 74, with back plate 74 having gas supply passage 852 formed therein. A gas supply conduit 826 is attached to horizontal transfer device 304. Gas supply conduit 826 has a stationary structure gas supply connection portion 842. Back plate 74 has a portable structure gas supply connection portion 846. Stationary structure gas supply connection portion 842 is initially separate from portable structure gas supply connection portion 846. In FIG. 1, as wafer chuck 72 moves downward into contact with thermal chuck 34, portable structure gas supply connection portion 846 moves downward into contact with stationary structure gas supply connection portion 842. A seal seals between portable structure gas supply connection portion 846 and stationary structure gas supply connection portion 842. Gas supply passage 852 then extends through horizontal transfer device 304 and gas supply conduit 826 into and through back plate 74. As described with reference to Figure 24, nitrogen and dielectric pressurized gases are supplied to the area between the contacts through gas supply conduit 826 and backplate 74. After testing is completed, backplate 74 is separated from gas removal conduit 828 shown in Figure 28 and gas supply conduit 826 shown in Figure 29.

[0147]

[0181] Figure 30 shows a gas box that forms part of the slot assembly 18A. Gas box 860 connects couplings 820A, 822A and 824A to gas supply conduit 826 shown in Figure 29 and gas removal conduit 828 shown in Figure 28.

[0148]

[0182] As shown in Figures 31 and 32, the gas box 860 includes a base 862, an intermediate substrate 864, a channeling block 866, a conversion block 868, a mounting plate 870, various regulators including a second nitrogen gas pressure regulator 830, a dielectric gas pressure regulator 834, a vacuum regulator 844, various connectors including a vacuum receiving connector 872, a nitrogen gas receiving connector 874, a dielectric gas receiving connector 876, a vacuum supply connector 880, a gas supply connector 882, a valve control connector 884, a releasable connecting portion 892 and a lid 896.

[0149]

[0183] Vacuum receiving connector 872, nitrogen gas receiving connector 874, and dielectric gas receiving connector 876 are secured to the front of base 862. Base 862 has channels (not shown) formed therein that extend from connectors 872, 874, and 876 to three releasable connections 892. Vacuum supply connector 880 and gas supply connector 882 are secured to the side of base 862. Other channels within base 862 connect connectors 880 and 882 to two other releasable connections 892. Connectors 872, 874, 876, 880, and 882 are generally disposed in the same plane.

[0150]

[0184] The conversion block 868 and the channeling block 866 are mounted on an intermediate substrate 864. The releasable intermediate substrate 864 has three releasable connection portions (not shown), which are spaced apart the same distance as the plurality of releasable connection portions 892 connected to connectors 872, 874, and 876. The channeling block 866 has two releasable connection portions (not shown), which are spaced apart the same distance as the plurality of releasable connection portions 892 connected to connectors 880 and 882. When the intermediate substrate 864 is mounted on the base 862, the releasable connection portions of the intermediate substrate 864 mate with the releasable connection portions 892 of the base 862. A channel is formed through the intermediate substrate 864, the conversion block 868, and the channeling block 866. The conversion block 868 thus connects the connectors 872, 874, and 878 to the channeling block 866. The conversion block 868 also converts the gas flow from horizontally parallel in a first direction 890 to vertically parallel in a second direction 894 that is perpendicular to the first direction.

[0151]

[0185] Regulators 830, 834, and 844 are attached to channeling block 866. Regulators 830, 834, and 844 can individually regulate each gas passing through channeling block 866. When regulators 830 and 834 are removed, channeling block 866 merges multiple passages from regulators 830 and 834 to gas supply connector 882 before passing through one of releasable connections 892 on base 862.

[0152]

[0186] Mounting plate 870 is fixed to the side of intermediate substrate 864. Valve control connector 884 is fixed to mounting plate 870. Valve control connector 884 is electrically connected to electrical terminals on regulators 830, 834 and 844.

[0153]

[0187] Lid 896 is shaped to fit over channeling block 866, conversion block 868, mounting plate 870, and mid-base plate 864. A slot in the side of lid 896 allows valve control connector 884 to protrude outside of lid 896.

[0154]

[0188] In use, gas supply connector 882 is connected to inlet orifice 838 shown in Figure 24, and vacuum supply connector 880 is connected to outlet orifice 840 shown in Figure 24. Valve control connector 884 is connected to heater control board 848 shown in Figure 24. Dielectric gas receiving connector 876, nitrogen gas receiving connector 874, and vacuum receiving connector 872 are also connected to couplings 822A, 820A, and 824A, respectively.

[0155]

[0189] Signals are provided to regulators 830, 834, and 844 via valve control connector 884 to control gas flow and vacuum to gas supply connector 882 and vacuum supply connector 880. For example, to introduce nitrogen gas, vacuum regulator 844 opens, introducing a vacuum through vacuum receiving connector 872 to vacuum supply connector 880, and dielectric gas pressure regulator 830 opens, connecting dielectric gas receiving connector 876 to gas supply connector 882.

[0156]

[0190] Gas box 860 provides a service-friendly form factor for regulators 830, 834, and 844. Mid-board 864 is removable from base 862, allowing base 862 to remain attached to the remainder of slot assembly 18A shown in FIG. 30 while servicing regulators 830, 834, and 844 or valve control connector 884. Releasable connection 892 allows mid-board 864 and base 862 to be connected vertically, where all gas and vacuum lines are linked simultaneously in a single, simple operation. Thus, it is not necessary to disconnect the lines from connectors 872 to 882.

[0157]

[0191] FIG. 33 shows another view of the tester apparatus. Certain components have already been described with reference to previous figures. For example, components of the slot assembly 18A include the thermal chuck 34, the thermal fluid passages 224, the connection board 66, and the first slot assembly interface 40. The previously described components of the first wafer pack 28A include the signal distribution board 500, the stiffener plate 776, the contactor board 502, the wafer contact pins 504, the contactor front contacts 562, the wafer pack interface 78, and the wafer chuck 72. As previously mentioned, the contactor front contacts 562 are located at the tips of the wafer contact pins 504. Some of the contactor front contacts 562 are power contactor front contacts that provide power to select some of the terminals 588 (see FIGS. 8A and 8B) on the wafer 32A. The power contactor front contacts provide power to the wafer 32A during testing. Additionally, some of the contactor front contacts 562 transmit and receive signals to and from the wafer 32A during testing.

[0158]

[0192] Other components of the tester apparatus include a tray 900 , a return terminal pin 902 , a wafer chuck pin 908 and a vacuum conduit 910 .

[0159]

[0193] The tray 900 includes a substrate 912 made of a dielectric material and a conductive layer 914 formed on the substrate 912. The conductive layer 914 has a conductive portion 916 and a return terminal area 918. The conductive portion 916 and the return terminal area 918 have an exposed top surface 920. The wafer 32A has terminals located on its underside that form part of its internal circuitry. The terminals located on the underside of the wafer 32A contact the exposed top surface 920 of the conductive portion 916. The conductive layer 914 can therefore be used to supply a reference voltage, such as a ground voltage, to the terminals on the underside of the wafer 32A.

[0160]

[0194] Return terminal pins 902 are attached to contactor board 502. Each return terminal pin 902 has a bottom end that forms a contactor return contact 922. The return terminal pins 902 extend past the edge of wafer 32A, resulting in the contactor return contact 922 contacting return terminal area 918. The return terminal pins 902 form electrical conductors that connect conductive layer 914 to signal distribution board 500. The conductors extend through signal distribution board 500, wafer pack interface portion 78, first slot assembly interface portion 40, interface board 66, and to the tester electronics described with reference to the previous figures. Thus, the tester electronics provides a reference voltage, such as ground, to a terminal on the underside of wafer 32A.

[0161]

[0195] Wafer chuck pins 908 are attached to contactor board 502. Each wafer chuck pin 908 has a lower tip that extends below contactor board 502, past wafer 32A and tray 900, and makes contact with wafer chuck 72. A ground reference voltage is therefore provided to wafer chuck 72 through signal distribution board 500 and wafer chuck pins 908. By grounding wafer chuck 72, wafer chuck 72 is maintained at a known voltage, which allows for the control of arcing between various conductive components, such as between terminals on the underside of wafer 32A and wafer chuck 72.

[0162]

[0196] Once testing of wafer 32A is complete, it is removed from tray 900, with tray 900 remaining on wafer chuck 72. Alternatively, tray 900 carrying wafer 32A may be removed from wafer chuck 72 after testing is complete, providing tray 900 with structural rigidity for ultra-thin wafers. In either case, tray 900 and wafer chuck 72 together form wafer holder 924 for wafer 32A during testing of wafer 32A.

[0163]

[0197] A plurality of vacuum openings 926 are formed through tray 900 and partially through wafer chuck 72. A vacuum passage 928 in wafer chuck 72 connects the lower ends of the vacuum openings 926 to one another. Vacuum conduit 910 also defines a vacuum passage and is connected to vacuum passage 928 in wafer chuck 72. Vacuum conduit 910 can connect to vacuum passage 928 using, for example, gas connection 832 and gas connection 836 shown in FIG. 28 .

[0164]

[0198] In use, a vacuum is applied to the vacuum opening 926 through the vacuum conduit 910 and the vacuum passage 928. The vacuum opening 926 is open at the top, exposing the underside of the wafers 32A to the vacuum. The applied vacuum secures the wafers 32A to the tray 900. A vacuum can be applied to secure the wafers 32A to the tray 900 prior to assembling the first wafer pack 28A and inserting the first wafer pack 28A into the slot assembly 18A. This vacuum can be maintained using the same pressure-reducing check valve 600 and vacuum-relief check valve 602 shown in FIG. 11 that are used to maintain the first wafer pack 28A in a closed state. Once the first wafer pack 28A is inserted into the slot assembly 18A, the vacuum is maintained by the connections 832 and 836 shown in FIG. 28 and the vacuum pump 806 shown in FIG. 24.

[0165]

[0199] Figure 34 is an enlarged view of detail "E" in Figure 33. Vacuum opening 926 includes a proximal section 932, a distal section 934, and an enlarged section 936. Proximal section 932 is of a relatively small diameter and extends completely through tray 900. Enlarged section 936 is formed in the top surface of wafer chuck 72 and has a much larger diameter than proximal section 932. Distal section 934 is formed from the base of enlarged section 936 and extends into vacuum opening 926 shown in Figure 33. The diameter of distal section 934 is much smaller than the diameter of enlarged section 936.

[0166]

[0200] By varying the diameter of vacuum opening 926 from its entrance opening 940 to its exit opening 942, the possibility of arcing between conductive layer 914 and wafer chuck 72 is reduced in situations where the voltages on conductive layer 914 and wafer chuck 72 are different. The larger diameter of enlarged section 936 increases the distance an arc must travel through entrance opening 940 and proximal section 932 between conductive layer 914 and the space in enlarged section 936 before reaching the conductive metal material of wafer chuck 72. Additionally, an electrical insulator 944 is formed around entrance opening 940 to further isolate the metal of conductive layer 914 from entrance opening 940.

[0167]

[0201] The vacuum provided through vacuum openings 926 is also used to hold tray 900 against wafer chuck 72. For deburring purposes, a chamfer 948 is formed around the upper periphery of enlarged section 936 to ensure flush contact between the underside of tray 900 and the upper surface of wafer chuck 72. Figures 35 and 36 are perpendicular cross-sectional views of wafer chuck 72 and tray 900. Both figures show the relative position of tray 900 and groove 950 for lip seal 77, which was described in detail with reference to Figure 14.

[0168]

[0202] While certain exemplary embodiments have been described and illustrated in the accompanying drawings, it is to be understood that such embodiments are merely exemplary and not limiting of the invention, and since modifications may occur to those skilled in the art, the invention is not limited to the specific constructions and arrangements shown and described. [Explanation of symbols]

[0169] 10 Testing equipment 18A Slot Assembly 18B Slot Assembly 28A First wafer pack 802 Nitrogen gas tank 804 Dielectric Gas Tank 806 Vacuum Pump 810 First nitrogen gas pressure regulator 830 Second nitrogen gas pressure regulator 834 Dielectric Gas Pressure Regulator 838 Inlet Orifice 840 Exit Orifice 844 Vacuum regulator 848 Heater control panel

Claims

1. 1. A tester apparatus comprising: first and second components for holding a substrate therebetween, said substrate carrying a microelectronic circuit and having a plurality of terminals connected to said microelectronic circuit; a plurality of contacts on the second component that correspond to and contact the terminals; a cavity seal between the first and second components and forming an enclosed cavity with surfaces of the first and second components; a vacuum passage formed through one of the components and having an inlet opening in the enclosed cavity and an outlet opening outside the enclosed cavity; a reduced pressure supply connected to the reduced pressure passage, the opening of which ensures that gas leaves the enclosed cavity and the closing of which prevents gas from entering the enclosed cavity; an electrical tester connected to the microelectronic circuit for testing the microelectronic circuit; a gas supply passage formed through one of the components and having an inlet opening outside the enclosed cavity and an outlet opening within the enclosed cavity; a gas inlet supply connected to said gas supply passage, the opening of which ensures that gas enters said enclosed cavity and the space between said contacts.

2. 10. The tester apparatus of claim 1, further comprising a dielectric gas source connected to the gas supply passage.

3. 10. The tester apparatus of claim 1, wherein the dielectric gas reduces arcing between the contacts compared to air.

4. The tester apparatus of claim 1 further comprising a vacuum pump connected to the reduced pressure supply.

5. 10. The tester apparatus of claim 1, further comprising an orifice connected to the gas supply passage to control the flow of dielectric gas through the gas supply passage.

6. 10. The tester apparatus of claim 1, further comprising an orifice connected to said reduced pressure passage to control the flow of dielectric gas through said reduced pressure passage.

7. a portable support structure including the first and second components; a first electrical connection portion located on the portable support structure and connected to the contact; a stationary structure receivable to hold the portable support structure and from which the portable support structure can be removed; 2. The tester apparatus of claim 1, further comprising: a second electrical connection portion on the stationary structure, the second electrical connection portion being connected to the first electrical connection portion when the portable structure is held by the stationary structure and being disconnected from the first electrical connection portion when the portable support structure is removed from the stationary structure, and an electrical tester being connected to the terminal via the second electrical connection portion, the first electrical connection portion, and the contact.

8. 10. The tester apparatus of claim 1, further comprising a vacuum regulator connected to said reduced pressure passage to control the flow of gas through said reduced pressure passage.

9. 9. The tester apparatus of claim 8, further comprising a dielectric gas pressure regulator connected to said gas supply passage to control the flow of dielectric gas into said gas supply passage.

10. 10. The tester apparatus of claim 9, further comprising a nitrogen gas pressure regulator connected to the gas supply passage to control the flow of nitrogen gas into the gas supply passage.

11. 11. The tester apparatus of claim 10, further comprising a channeling block connected to the dielectric gas pressure regulator and the nitrogen gas pressure regulator and connected to the gas supply passage to selectively supply the nitrogen gas or the dielectric gas to the gas supply passage.

12. The tester apparatus of claim 11 , further comprising a gas supply connector connected to the gas supply passage to supply the nitrogen gas or the dielectric gas to the gas supply passage.

13. 13. The tester apparatus of claim 12, further comprising a vacuum supply connector connected to the reduced pressure passageway to supply the vacuum from the vacuum regulator to the reduced pressure passageway.

14. The tester apparatus of claim 13 , wherein the vacuum supply connector is connected to the vacuum regulator through the channeling block.

15. a vacuum receiving connector connectable to a vacuum pump and connecting said vacuum regulator to said vacuum pump; a nitrogen gas receiving connector connectable to a nitrogen gas inlet supply and connecting the nitrogen gas inlet supply to the nitrogen gas pressure regulator; 14. The tester apparatus of claim 13, further comprising: a dielectric gas receiving connector connectable to a dielectric gas inlet supply and connecting said dielectric gas inlet supply to said dielectric gas pressure regulator.

16. 16. The tester apparatus of claim 15, further comprising a base to which the gas supply connector, the vacuum supply connector, the vacuum receiving connector, the nitrogen gas receiving connector, and the dielectric gas receiving connector are mounted.

17. 17. The tester apparatus of claim 16, further comprising an intermediate substrate to which the channeling block is mounted and which is vertically separable from the base, the base and the intermediate substrate having mating connecting portions that releasably connect the gas supply connector, the vacuum supply connector, the vacuum receiving connector, the nitrogen gas receiving connector, and the dielectric gas receiving connector to the channeling block.

18. a mounting plate fixed to the intermediate substrate; 18. The tester apparatus of claim 17, further comprising a valve control connector secured to the mounting plate, the valve control connector transmitting electrical signals to supply the vacuum regulator, the nitrogen gas regulator, and the dielectric gas regulator.

19. 16. The tester apparatus of claim 15, further comprising a transition block for connecting the vacuum receiving connector, the nitrogen gas receiving connector, and the dielectric gas receiving connector to the channeling block, the transition block converting gas flow from horizontally parallel in a first direction to vertically parallel in a second direction perpendicular to the first direction.

20. 11. The tester apparatus of claim 10, further comprising control circuitry for controlling the vacuum regulator, the dielectric gas pressure regulator, and the nitrogen gas pressure regulator.

21. the first component is a wafer chuck in the form of a flat piece having a flat surface movable toward a flat surface of a stationary thermal chuck; a gas supply conduit forming part of said stationary structure; a stationary structure gas supply connection forming part of said stationary structure; 2. The tester apparatus of claim 1, further comprising: a portable structure gas supply connection portion on the portable structure configured to mate with the stationary structure gas supply connection portion when the wafer chuck is moved toward the thermal chuck to connect the inlet opening of the gas supply passage to the gas supply conduit of the stationary structure.

22. The first component has a flat surface that is movable toward the flat surface of the stationary thermal chuck. and a wafer chuck in the form of a flat piece having: a gas removal conduit forming part of said stationary structure; a stationary structure gas removal connection portion forming part of said stationary structure; 2. The tester apparatus of claim 1, further comprising: a portable structure gas removal connection portion on the portable structure, the portable structure gas removal connection portion configured to mate with the stationary structure gas removal connection portion when the wafer chuck moves toward the thermal chuck to connect an outlet opening of the reduced pressure passage to the stationary structure gas removal conduit.

23. 2. The tester apparatus of claim 1, wherein opening the reduced pressure supply to allow gas to exit the enclosed cavity causes the first and second components to move relatively toward one another to ensure proper contact between the contacts and the terminals.

24. 2. The tester apparatus of claim 1, wherein the vacuum passage is formed in the first component.

25. further comprising a latch system, said latch system comprising: a first latch assembly, the first latch assembly comprising: a first part that engages the first component; a second part that engages the second component part; a connecting piece having opposite ends secured to the first and second pieces, respectively, to form a locking mechanism; 2. The tester apparatus of claim 1, further comprising: an engagement mechanism connected to the locking mechanism and operable to move the locking mechanism between a locked position that maintains the first and second components locked in a closed position and an unlocked position that moves the first and second components from the closed relationship to a spaced apart relationship.

26. further comprising a pressure monitoring system, said pressure monitoring system comprising: a pressure sensor positioned to detect pressure within the enclosed cavity; an electrical pressure sensor interface connected to said pressure sensor for transmitting said pressure to an electrical tester.

27. A wafer pack, a portable support structure including first and second components for holding a substrate therebetween, the substrate carrying a microelectronic circuit and having a plurality of terminals connected to the microelectronic circuit; a plurality of contacts on the second component that correspond to and contact the terminals; a cavity seal between the first and second components and forming an enclosed cavity with surfaces of the first and second components; a vacuum passage formed through one of the components and having an inlet opening in the enclosed cavity and an outlet opening outside the enclosed cavity; a reduced pressure supply connected to the reduced pressure passage, the opening of which ensures that gas leaves the enclosed cavity and the closing of which prevents gas from entering the enclosed cavity; a first electrical connection portion on the portable support structure and connected to the contact, the first electrical connection portion being connected to a second electrical connection portion on a stationary structure when the portable support structure is removably held by a stationary structure; a gas supply passage formed through one of the components and having an inlet opening outside the enclosed cavity and an outlet opening within the enclosed cavity; a gas inlet supply connected to the gas supply passage, the opening of which ensures that gas enters the enclosed cavity and the space between the contacts.

28. the first component is a wafer chuck in the form of a flat piece having a flat surface movable toward the flat surface of the stationary thermal chuck, and the wafer pack further comprises:

28. The wafer pack of claim 27, further comprising a portable structural gas supply connection portion shaped to mate with the stationary structural gas supply connection portion when the wafer chuck is moved toward the thermal chuck to connect the inlet opening of the gas supply passage to a gas supply conduit of the stationary structure.

29. The first component is a wafer chuck in the form of a flat piece having a flat surface movable toward a flat surface of a stationary thermal chuck, and the wafer pack further comprises:

28. The wafer pack of claim 27, including a portable structural gas removal connection portion shaped to mate with a stationary structural gas removal connection portion when the wafer chuck moves toward the thermal chuck to connect the outlet opening of the vacuum passage to a gas removal conduit of the stationary structure.

30. 28. The wafer pack of claim 27, wherein opening the reduced pressure supply to allow gas to exit the enclosed cavity causes the first and second components to move relatively toward one another to ensure proper contact between the contacts and the terminals.

31. 28. The wafer pack of claim 27, wherein the vacuum passages are formed in a first component.

32. further comprising a latch system, said latch system comprising: a first latch assembly, the first latch assembly comprising: a first part that engages the first component; a second part that engages the second component part; a connecting piece having opposite ends secured to the first and second pieces, respectively, to form a locking mechanism; 28. The wafer pack of claim 27, further comprising: an engagement mechanism connected to and operable to move the locking mechanism between a locked position that maintains the first and second components locked in a closed position and an unlocked position that moves the first and second components from the closed relationship to a spaced apart relationship.

33. further comprising a pressure monitoring system, said pressure monitoring system comprising: a pressure sensor positioned to detect pressure within the enclosed cavity; 28. The wafer pack of claim 27, including an electrical pressure sensor interface connected to the pressure sensor for transmitting the pressure to an electrical tester.

34. 1. A method for testing a microelectronic circuit carried by a substrate, comprising: holding the substrate between the first and second components, the second component having contacts that contact terminals of the substrate connected to the microelectronic circuit; disposing a cavity seal between the first and second components to form a cavity bounded by surfaces of the first and second components and the cavity seal; transmitting signals between the electrical tester and the microelectronic circuit to test the microelectronic circuit; and filling said enclosed cavity and the space between said contacts with a dielectric gas.

35. a vacuum passageway formed through one of the components, the vacuum passageway having an inlet opening in the enclosed cavity and an outlet opening outside the enclosed cavity, the method further comprising:

35. The method of claim 34, including the step of opening a gas inlet supply to admit a conductive gas through a gas supply passage formed through one of the components into the enclosed cavity and into the space between the contacts.

36. 35. The method of claim 34, wherein the dielectric gas reduces the arcing between the contacts compared to air.

37. 35. The method of claim 34, further comprising controlling the flow of the dielectric gas through the gas supply passage by passing the dielectric gas through an orifice.

38. 35. The method of claim 34, further comprising controlling the flow of the dielectric gas through the gas decompression passage by passing the dielectric gas through an orifice.

39. The first and second components form part of a portable support structure, and the method further comprises:

35. The method of claim 34, further comprising the step of housing the portable support structure with a stationary structure with a first electrical connection portion on the portable support structure connected to a second electrical connection portion on the stationary structure, wherein the signals are transmitted between the electrical tester and the microelectronic circuit via the terminals, the contacts, and the first and second electrical connection portions to test the microelectronic circuit.

40. 35. The method of claim 34, further comprising controlling the flow of gas through the reduced pressure passage using a vacuum regulator connected to the reduced pressure passage.

41. 41. The method of claim 40, further comprising controlling the flow of dielectric gas into the gas supply passage using a dielectric gas pressure regulator connected to the gas supply passage.

42. 42. The method of claim 41, further comprising a nitrogen gas pressure regulator connected to the gas supply passage to control the flow of nitrogen gas into the gas supply passage.

43. 43. The method of claim 42, further comprising controlling the vacuum regulator, the dielectric gas pressure regulator, and the nitrogen gas pressure regulator using control circuitry.

44. The first component is a wafer chuck in the form of a flat piece having a flat surface, and the method further comprises:

40. The method of claim 39, further comprising: moving the flat surface of the wafer chuck toward the flat surface of the thermal chuck of the stationary structure to further mate a portable structure gas supply connection portion with a stationary structure gas supply connection portion to connect the inlet opening of the gas supply passage to a gas supply conduit of the stationary structure.

45. The first component is a wafer chuck in the form of a flat piece having a flat surface, and the method further comprises:

35. The method of claim 34, further comprising the step of further pairing a portable structure gas removal connection portion with a stationary structure gas removal connection portion by moving the flat surface of the wafer chuck toward a flat surface of a stationary structure thermal chuck to connect the outlet opening of the reduced pressure passage to a gas removal conduit of the stationary structure.

46. 35. The method of claim 34, wherein opening the reduced pressure supply to allow gas to escape from the enclosed cavity causes the first and second components to move relatively toward one another to ensure proper contact between the contacts and the terminals.

47. 35. The method of claim 34, wherein the vacuum passage is formed in the first component.

48. The method further includes operating an engagement mechanism to move a locking device between a locked position where the locking device maintains the first and second components locked in a closed position and an unlocked position where the locking device moves the first and second components from the closed relationship to a spaced apart relationship, the locking mechanism comprising: a first part that engages the first component; a second part that engages the second component part; a connecting piece having opposite ends secured to the first and second pieces, respectively.

49. sensing a pressure within the enclosed cavity; 35. The method of claim 34, further comprising: transmitting the pressure to the electrical tester.

50. A gas box, a vacuum regulator connectable to the reduced pressure passage for controlling the flow of gas through the reduced pressure passage; a dielectric gas pressure regulator connectable to the gas supply passage and configured to control the flow of dielectric gas into the gas supply passage; a nitrogen gas pressure regulator for controlling the flow of nitrogen gas into the gas supply passage; a channeling block connected to the dielectric gas pressure regulator and the nitrogen gas pressure regulator and connectable to a gas supply passage, for selectively supplying the nitrogen gas or the dielectric gas to the gas supply passage.

51. 51. The gas box of claim 50, further comprising a gas supply connector connected to the gas supply passage to supply the nitrogen gas or the dielectric gas to the gas supply passage.

52. 52. The gas box of claim 51, further comprising a vacuum supply connector connected to said reduced pressure passageway to supply said vacuum from said vacuum regulator to said reduced pressure passageway.

53. 53. The gas box of claim 52, wherein the vacuum supply connector is connected to the vacuum regulator through the channeling block.

54. a vacuum receiving connector connectable to a vacuum pump for connecting said vacuum regulator to said vacuum pump; a nitrogen gas receiving connector connectable to a nitrogen gas inlet supply and capable of connecting the nitrogen gas inlet supply to the nitrogen gas pressure regulator; 53. The gas box of claim 52, further comprising: a dielectric gas receiving connector connectable to a dielectric gas inlet supply, connecting said dielectric gas inlet supply to said dielectric gas pressure regulator.

55. 55. The gas box of claim 54, further comprising a base to which the gas supply connector, the vacuum supply connector, the vacuum receiving connector, the nitrogen gas receiving and dielectric gas receiving connectors are mounted.

56. 56. The gas box of claim 55, further comprising an intermediate substrate to which said channeling block is mounted and vertically separable from said base, said base and said intermediate substrate having mating connecting portions that releasably connect said gas supply connector, said vacuum supply connector, said vacuum receiving connector, said nitrogen gas receiving and dielectric gas receiving connectors to said channeling block.

57. a mounting plate fixed to the intermediate substrate; 57. The gas box of claim 56, further comprising a valve control connector secured to the mounting plate, the valve control connector through which electrical signals are transmitted to supply the vacuum regulator, the nitrogen gas regulator, and the dielectric gas regulator.

58. 55. The gas box of claim 54, further comprising a transition block for connecting the vacuum receiving connector, the nitrogen gas receiving connector, and the dielectric gas receiving connector to the channeling block, the transition block converting gas flow from horizontally parallel in a first direction to vertically parallel in a second direction perpendicular to the first direction.

59. 1. A tester apparatus comprising: a portable support structure including first and second components for holding a substrate therebetween, the substrate carrying a microelectronic circuit and having a plurality of terminals connected to the microelectronic circuit, the first component being a wafer chuck in the form of a flat piece having a flat surface; a plurality of contacts on the second component and aligned with the terminals for contacting the terminals; a cavity seal between the first and second components and forming an enclosed cavity with surfaces of the first and second components; a vacuum passage formed through one of the components and having an inlet opening in the enclosed cavity and an outlet opening outside the enclosed cavity; a reduced pressure supply connected to the reduced pressure passage, the opening of which ensures gas exits the enclosed cavity and the closing of which prevents gas from entering the enclosed cavity; a first electrical connection portion located on the portable support structure and connected to the contact; a gas removal connection on the portable structure; a stationary structure receivable to hold the portable support structure and from which the portable support structure can be removed; a second electrical connection portion on the stationary structure, the second electrical connection portion being connected to the first electrical connection portion when the portable structure is held by the stationary structure and being disconnected from the first electrical connection portion when the portable support structure is removed from the stationary structure; an electrical tester is connected to the terminal via the second electrical connection portion, the first electrical connection portion, and the contact; a thermal chuck in the stationary structure, the planar surface of the thermal chuck being movable toward the planar surface of the wafer chuck; a stationary structure gas removal connection portion forming part of the stationary structure, the stationary structure gas removal connection portion configured to mate with the portable structure gas removal connection portion when the wafer chuck moves toward the thermal chuck to connect the outlet opening of the vacuum passage to the gas removal conduit of the stationary structure; an electrical tester connected to said microelectronic circuit for testing said microelectronic circuit.

60. a gas supply passage formed through one of the components and having an inlet opening outside the enclosed cavity and an outlet opening within the enclosed cavity; 60. The tester apparatus of claim 59, further comprising a gas inlet supply connected to the gas supply passage, the opening of which ensures gas enters the enclosed cavity and spaces between the contacts.

61. 61. The tester apparatus of claim 60, further comprising a dielectric gas source connected to the gas supply passage.

62. 62. The tester apparatus of claim 61, wherein the dielectric gas reduces arcing between the contacts compared to air.

63. 61. The tester apparatus of claim 60, further comprising a vacuum pump connected to the reduced pressure supply.

64. 61. The tester apparatus of claim 60, further comprising an orifice connected to the gas supply passage for controlling the flow of the dielectric gas through the gas supply passage.

65. 61. The tester apparatus of claim 60, further comprising an orifice connected to the reduced pressure passage to control the flow of the dielectric gas through the reduced pressure passage.

66. 61. The tester apparatus of claim 60, further comprising a vacuum regulator connected to the reduced pressure passage to control the flow of gas through the reduced pressure passage.

67. 67. The tester apparatus of claim 66, further comprising a dielectric gas pressure regulator connected to the gas supply passage to control the flow of dielectric gas into the gas supply passage.

68. 68. The tester apparatus of claim 67, further comprising a nitrogen gas pressure regulator connected to the gas supply passage to control the flow of nitrogen gas into the gas supply passage.

69. 69. The tester apparatus of claim 68, further comprising a channeling block connected to the dielectric gas pressure regulator and the nitrogen gas pressure regulator and connected to the gas supply passage to selectively supply the nitrogen gas or the dielectric gas to the gas supply passage.

70. 70. The tester apparatus of claim 69, further comprising a gas supply connector connected to the gas supply passage to supply the nitrogen gas or the dielectric gas to the gas supply passage.

71. 71. The tester apparatus of claim 70, further comprising a vacuum supply connector connected to the reduced pressure passageway to supply the vacuum from the vacuum regulator to the reduced pressure passageway.

72. 72. The tester apparatus of claim 71, wherein the vacuum supply connector is connected to the vacuum regulator through the channeling block.

73. a vacuum receiving connector connectable to a vacuum pump for connecting said vacuum regulator to said vacuum pump; a nitrogen gas receiving connector connectable to a nitrogen gas inlet supply, connecting said nitrogen gas inlet supply to said nitrogen gas pressure regulator; 72. The tester apparatus of claim 71, further comprising: a dielectric gas receiving connector connectable to a dielectric gas inlet supply, connecting said dielectric gas inlet supply to said dielectric gas pressure regulator.

74. 74. The tester apparatus of claim 73, further comprising a base to which the gas supply connector, the vacuum supply connector, the vacuum receiving connector, the nitrogen gas receiving and dielectric gas receiving connectors are mounted.

75. 75. The tester apparatus of claim 74, further comprising an intermediate substrate to which the channeling block is mounted and which is vertically separable from the base, the base and the intermediate substrate having mating connecting portions that releasably connect the gas supply connector, the vacuum supply connector, the vacuum receiving connector, the nitrogen gas receiving and dielectric gas receiving connectors to the channeling block.

76. 76. The tester apparatus of claim 75, further comprising: a mounting plate secured to the intermediate substrate; and a valve control connector secured to the mounting plate, the valve control connector transmitting electrical signals to supply the vacuum regulator, the nitrogen gas regulator, and the dielectric gas regulator.

77. 74. The tester apparatus of claim 73, further comprising a transition block for connecting the vacuum receiving connector, the nitrogen gas receiving connector, and the dielectric gas receiving connector to the channeling block, the transition block converting gas flow from horizontally parallel in a first direction to vertically parallel in a second direction perpendicular to the first direction.

78. 69. The tester apparatus of claim 68, further comprising control circuitry for controlling the vacuum regulator, the dielectric gas pressure regulator, and the nitrogen gas pressure regulator.

79. The first component is a wafer chuck in the form of a flat piece having a flat portion movable toward a flat surface of a stationary thermal chuck, and the tester device further comprises: a gas supply conduit forming part of said stationary structure; a stationary structure gas supply connection forming part of said stationary structure; 60. The tester apparatus of claim 59, further comprising: a portable structure gas supply connection portion on the portable structure, the portable structure gas supply connection portion shaped to mate with the stationary structure gas supply connection portion when the wafer chuck is moved toward the thermal chuck to connect the inlet opening of the gas supply passage to the gas supply conduit of the stationary structure.

80. 60. The tester apparatus of claim 59, wherein opening the reduced pressure supply to vent gas from the enclosed cavity causes the first and second components to move relatively toward one another to ensure proper contact between the contacts and the terminals.

81. 60. The tester apparatus of claim 59, wherein the vacuum passage is formed in the first component.

82. Further comprising a latch system, the latch system comprising: a first latch assembly, said first latch assembly comprising: a first part that engages the first component; a second part that engages the second component part; a connecting piece having opposite ends fixed to the first piece and the second piece, respectively; 60. The tester apparatus of claim 59, including an engagement mechanism connected to and operable to move the locking mechanism between a locked position that maintains the first and second components locked in a closed position and an unlocked position that moves the first and second components from the closed relationship to a spaced apart relationship.

83. further comprising a pressure monitoring system, said pressure monitoring system comprising: a pressure sensor positioned to detect pressure within the enclosed cavity; an electrical pressure sensor interface connected to the pressure sensor for transmitting said pressure to an electrical tester.

84. A wafer pack, a portable support structure including first and second components for holding a substrate therebetween, the substrate carrying a microelectronic circuit and having a plurality of terminals connected to the microelectronic circuit, the first component being a wafer chuck in the form of a flat piece having a flat surface movable toward a flat surface of a stationary thermal chuck; a plurality of contacts on the second component and aligned with the terminals for contacting the terminals; a cavity seal between the first and second components and forming an enclosed cavity with surfaces of the first and second components; a vacuum passage formed through one of said components and having an inlet opening in said enclosed cavity and an outlet opening outside said enclosed cavity; a reduced pressure supply connected to the reduced pressure passage, the opening of which ensures that gas leaves the enclosed cavity and the closing of which prevents gas from entering the enclosed cavity; a first electrical connection portion on the portable support structure and connected to the contact, the first electrical connection portion for connecting to a second electrical connection portion on a stationary structure when the portable support structure is removably held by the stationary structure; a portable structural gas removal connection portion shaped to mate with the stationary structural gas removal connection portion when the wafer chuck moves toward the thermal chuck to connect the outlet opening of the vacuum passage to a gas removal conduit of the stationary structure.

85. a gas supply passage formed through one of the components and having an inlet opening outside the enclosed cavity and an outlet opening within the enclosed cavity; 85. The wafer pack of claim 84, further comprising: a gas inlet supply connected to the gas supply passage, the opening of which ensures that gas enters the enclosed cavity and into the spaces between the contacts.

86. The first component is a wafer chuck in the form of a flat piece having a flat surface movable toward a flat surface of a stationary thermal chuck, and the wafer pack further comprises:

86. The wafer pack of claim 85, including a portable structure gas supply connection portion shaped to mate with a stationary structure gas supply connection portion when the wafer chuck is moved toward the thermal chuck to connect the inlet opening of the gas supply passage to a gas supply conduit of the stationary structure.

87. 85. The wafer pack of claim 84, wherein opening the reduced pressure supply to vent gas from the enclosed cavity causes the first and second components to move relatively toward one another to ensure proper contact between the contacts and the terminals.

88. 85. The wafer pack of claim 84, wherein the vacuum passages are formed in the first component.

89. further comprising a latch system, said latch system comprising: a first latch assembly, the first latch assembly comprising: a first part that engages the first component; a second part that engages the second component part; a connecting piece having opposite ends secured to the first and second pieces to form a locking mechanism; 85. The wafer pack of claim 84, including an engagement mechanism connected to and operable to move the locking mechanism, the engagement mechanism moving the locking mechanism between a locked position that maintains the first and second components locked in a closed position and an unlocked position that moves the first and second components from the closed relationship to a spaced apart relationship.

90. further comprising a pressure monitoring system, said pressure monitoring system comprising: a pressure sensor positioned to detect pressure within the enclosed cavity; an electrical pressure sensor interface connected to said pressure sensor for transmitting said pressure to an electrical tester.

91. 1. A method for testing a microelectronic circuit carried by a substrate, comprising: for holding the substrate between the first and second components, the second component having contacts for contacting terminals of the substrate connected to the microelectronic circuit, and the first component being a wafer chuck in the form of a flat piece having a flat surface; disposing a cavity seal between the first and second components to form a cavity bounded by surfaces of the first and second components and the cavity seal; receiving the portable support structure with a stationary structure with a first electrical connection portion on the portable support structure connected to a second electrical connection portion on the stationary structure; further mating a portable structure gas removal connection portion with a stationary structure gas removal connection portion by moving the planar surface of the wafer chuck toward a planar surface of a stationary structure thermal chuck to connect the outlet opening of the vacuum passage to a gas removal conduit of the stationary structure; transmitting signals between an electrical tester and the microelectronic circuit to test the microelectronic circuit, the signals being transmitted between the electrical tester and the microelectronic circuit via the terminals, the contacts, and the first and second electrical connection portions to test the microelectronic circuit.

92. 92. The method of claim 91, further comprising disposing a dielectric gas within the enclosed cavity and within the spaces between the contacts.

93. a vacuum passageway formed through one of the components, the vacuum passageway having an inlet opening in the enclosed cavity and an outlet opening outside the enclosed cavity, the method further comprising:

93. The method of claim 92, including opening a gas inlet supply to admit conductive gas into the enclosed cavity and into the space between the contacts through a gas supply passage formed through one of the components.

94. 92. The method of claim 91, wherein the dielectric gas reduces arcing between the contacts compared to air.

95. 94. The method of claim 93, further comprising controlling the flow of the dielectric gas through the gas supply passage by passing the dielectric gas through an orifice.

96. 94. The method of claim 93, further comprising controlling the flow of the dielectric gas through the reduced pressure passage by passing the dielectric gas through an orifice.

97. The first and second components form part of a portable support structure, and the method further comprises:

94. The method of claim 93, comprising housing the portable support structure with a stationary structure with a first electrical connection portion of the portable support structure connected to a second electrical connection portion of the stationary structure, and the signals being transmitted between the electrical tester and the microelectronic circuit via the terminals, the contacts, and the first and second electrical connection portions to test the microelectronic circuit.

98. 94. The method of claim 93, further comprising controlling the flow of gas through the reduced pressure passage using a vacuum regulator connected to the reduced pressure passage.

99. 94. The method of claim 93, further comprising controlling the flow of dielectric gas into the gas supply passage using a dielectric gas pressure regulator connected to the gas supply passage.

100. 94. The method of claim 93, further comprising a nitrogen gas pressure regulator connected to the gas supply passage to control the flow of nitrogen gas into the gas supply passage.

101. 101. The method of claim 100, further comprising controlling the vacuum regulator, the dielectric gas pressure regulator, and the nitrogen gas pressure regulator using control circuitry.

102. The first component is a wafer chuck in the form of a flat piece having a flat surface, and the method further comprises:

98. The method of claim 97, further comprising: moving the flat surface of the wafer chuck toward the flat surface of a thermal chuck of a stationary structure to further pair a portable structure gas supply connection portion with a stationary structure gas supply connection portion to connect the inlet opening of the gas supply passage to a gas supply conduit of the stationary structure.

103. 92. The method of claim 91, wherein opening the reduced pressure supply to vent gas from the enclosed cavity causes the first and second components to move relatively toward one another to ensure proper contact between the contacts and the terminals.

104. 92. The method of claim 91, wherein the vacuum passage is formed in the first component.

105. and operating an engagement mechanism to move the locking mechanism between a locked position that maintains the first and second components in a closed position and an unlocked position that allows the first and second components to move from a closed relationship to a spaced apart relationship, the locking mechanism comprising: a first part that engages the first component; a second part that engages the second component part; a connecting piece having opposite ends secured to the first and second pieces, respectively.

106. sensing a pressure within the enclosed cavity; 92. The method of claim 91, further comprising: transmitting the pressure to the electrical tester.

107. 1. A tester apparatus comprising: a tray for releasably holding a wafer, the tray having at least a portion that is electrically conductive and has an exposed surface that contacts a backside wafer terminal on the backside of the wafer; a contactor panel; contactor front contacts mounted on the contactor board, each contactor front contact having a surface positioned to contact a respective front wafer terminal on the front side of the wafer; an electrical tester connected to the contactor front contacts, such that, in use, electricity flows between the wafer and the circuitry of the wafer via the front wafer contacts and the contactor front contacts to test the circuitry; and a tester apparatus comprising: an electrical conductor connected to the conductive portion, such that, in use, the circuit is connected to the electrical tester via the back wafer contact, the exposed surface of the conductive portion, and the electrical path.

108. 108. The tester apparatus of claim 107, further comprising a thermal chuck to which the tray is thermally connected and which transfers heat to and from the wafer in use.

109. 109. The tester apparatus of claim 108, wherein the thermal chuck has a thermal passageway such that, in use, a fluid flows through the thermal passageway to transfer heat between the fluid and the thermal chuck.

110. 108. The tester apparatus of claim 107, further comprising a wafer chuck on which the tray is disposed and having a vacuum passage therethrough, the tray having a plurality of vacuum openings therethrough, each vacuum opening connecting the backside of the wafer to a vacuum passage in the wafer chuck, such that when a vacuum is applied to the vacuum passage, the vacuum secures the backside of the wafer to the tray.

111. 111. The tester apparatus of claim 110, wherein the tray includes an electrical insulator around the entrance opening of each vacuum opening.

112. 111. The tester apparatus of claim 110, further comprising at least one wafer chuck pin having a ground contact attached to the contactor board and contacting the wafer chuck.

113. 113. The tester apparatus of claim 112, wherein the wafer chuck pins extend beyond the edge of the tray.

114. 113. The tester apparatus of claim 112, further comprising a plurality of wafer chuck pins.

115. The tray includes a return terminal area electrically connected to an exposed surface thereof, the contactor face contact mounted on the contactor board is a power contactor face contact, and the electrical return conductor is 108. The tester apparatus of claim 107, including a contactor return contact mounted on the contactor board and having a surface positioned to contact a return terminal area on the tray.

116. a plurality of wafer contact pins attached to the contactor board and on which the power contactor front contacts are disposed; 116. The tester apparatus of claim 115, further comprising: at least one return terminal pin attached to the contactor board and on which the contactor return terminal is disposed.

117. 117. The tester apparatus of claim 116, wherein the return terminal pin extends beyond the edge of the wafer.

118. 117. The tester apparatus of claim 116, further comprising a plurality of return terminal pins.

119. Further comprising a signal distribution board, the signal distribution board comprising: a signal distribution board; a signal distribution board contact on the signal distribution board substrate; a signal distribution board terminal on the signal distribution board; 116. The tester apparatus of claim 115, further comprising: signal distribution board conductors connecting the signal distribution board contacts to the signal distribution board terminals.

120. 120. The tester apparatus of claim 119, further comprising a stiffener plate positioned to support the signal distribution board substrate.

121. 1. A method for testing a wafer, comprising: holding the wafer on a tray, said tray having at least a portion that is electrically conductive and has an exposed surface for contacting a backside wafer terminal on the backside of said wafer; moving the contactor board and the tray relatively toward one another so that surfaces of contactor contacts mounted on the contactor board contact respective front wafer contacts on the front side of the wafer; conducting current between an electrical tester and circuitry on the wafer through the front-side wafer contacts and the contactor contacts to test the circuitry; the circuit is connected to an electrical tester via the back wafer terminal, the exposed surface of the conductive portion, and the electrical path; and removing the wafer from the tray.

122. thermally connecting the tray to the thermal chuck; 122. The method of claim 121, further comprising: transferring heat between the thermal chuck and the wafer.

123. 123. The method of claim 122, wherein a fluid flows through the thermal passages of the thermal chuck to transfer heat between the fluid and the thermal chuck.

124. The tray is placed on the wafer chuck, the wafer chuck having a vacuum passage therethrough, the tray having a plurality of vacuum openings therethrough, each vacuum opening connecting the backside of the wafer to the vacuum passage in the wafer chuck, so that the method further comprises:

122. The method of claim 121, comprising applying a vacuum to the vacuum passage, the vacuum securing the backside of the wafer to the tray.

125. 125. The method of claim 124, wherein the tray includes electrical insulation around the entrance opening of each vacuum opening.

126. 125. The method of claim 124, further comprising contacting the wafer chuck with a ground contact of at least one wafer chuck pin mounted on the contactor board.

127. 127. The method of claim 126, wherein the wafer chuck pins extend beyond the edge of the tray.

128. 127. The method of claim 126, further comprising contacting the wafer chuck with a plurality of wafer chuck pins attached to the contactor board.

129. The tray includes a return terminal area electrically connected to an exposed surface thereof, the contactor face contact mounted on the contactor board is a power contactor face contact, and the electrical return conductor is 122. The method of claim 121, including a contactor return contact attached to the contactor board and having a surface positioned to contact the return terminal area on the tray.

130. a plurality of wafer contact pins mounted on the contactor board, the power contactor surface contacts being disposed on the wafer contact pins; 130. The method of claim 129, wherein the contactor board has at least one return terminal pin attached thereto, and the contactor return contact is on the return terminal pin.

131. 131. The method of claim 130, wherein the return terminal pin extends beyond the edge of the wafer.

132. 131. The method of claim 130, wherein the contactor board has a plurality of return terminal pins attached thereto.

133. The method further includes attaching the contactor board to a signal distribution board, the signal distribution board comprising: a signal distribution board; a signal distribution board contact on the signal distribution board substrate; a signal distribution board terminal on the signal distribution board; 130. The method of claim 129, further comprising: a signal distribution board conductor connecting said signal distribution board contact to said signal distribution board terminal.

134. 134. The method of claim 133, further comprising the step of positioning a stiffener plate to support the signal distribution board substrate.

135. 1. A tester apparatus comprising: a wafer chuck; a tray that releasably holds a wafer and is releasably disposed on the wafer chuck; the wafer chuck having a vacuum passage therethrough and the tray having a plurality of vacuum openings therethrough, each vacuum opening connecting the backside of the wafer to a vacuum passage in the wafer chuck such that when a vacuum is applied to the vacuum passage, the vacuum secures the backside of the wafer to the tray; a contactor panel; contactor contacts mounted on the contactor board, each contactor contact having a surface positioned to contact a respective front wafer terminal on the front side of the wafer; an electrical tester connected to the contactor contacts such that, in use, current is conducted to and from circuitry on the wafer through the front-side wafer contacts and the contactor contacts to test the circuitry.

136. 136. The tester apparatus of claim 135, further comprising a thermal chuck to which the tray is thermally connected and which transfers heat to and from the wafer in use.

137. 137. The tester apparatus of claim 136, wherein the thermal chuck has a thermal passageway such that, in use, a fluid flows through the thermal passageway to transfer heat between the fluid and the thermal chuck.

138. the tray has at least a conductive portion and an exposed surface for contacting a backside wafer terminal on the backside of the wafer, and the tester device further comprises 136. The tester apparatus of claim 135, comprising an electrical conductor connected to the conductive portion such that, in use, the circuit is connected to the electrical tester via the back wafer terminal, the exposed surface of the conductive portion, and the electrical path.

139. 139. The tester apparatus of claim 138, wherein the tray includes an electrical insulator around the entrance opening of each vacuum opening.

140. 139. The tester apparatus of claim 138, further comprising at least one wafer chuck pin having a ground contact attached to the contactor board and contacting the wafer chuck.

141. 141. The tester apparatus of claim 140, wherein the wafer chuck pins extend beyond the edge of the tray.

142. 141. The tester apparatus of claim 140, further comprising a plurality of wafer chuck pins.

143. The tray includes a return terminal area electrically connected to an exposed surface thereof, the contactor face contact mounted on the contactor board is a power contactor face contact, and the electrical return conductor is 139. The tester apparatus of claim 138, including a contactor return contact attached to the contactor board and having a surface positioned to contact the return terminal area on the tray.

144. a plurality of wafer contact pins attached to the contactor board and on which the power contactor front contacts are disposed; 136. The tester apparatus of claim 135, further comprising: at least one return terminal pin attached to the contactor board and carrying the contactor return contact.

145. 145. The tester apparatus of claim 144, wherein the return terminal pin extends beyond the edge of the wafer.

146. 145. The tester apparatus of claim 144, further comprising a plurality of return terminal pins.

147. Further comprising a signal distribution board, the signal distribution board comprising: a signal distribution board; a signal distribution board contact on the signal distribution board substrate; a signal distribution board terminal on the signal distribution board; and signal distribution board conductors connecting the signal distribution board contacts to the signal distribution board terminals.

148. 148. The tester apparatus of claim 147, further comprising a stiffener plate positioned to support the signal distribution board substrate.

149. 1. A method for testing a wafer, comprising: holding the wafers in a tray; placing the tray on a wafer chuck; applying a vacuum to a vacuum passage through the wafer chuck, the tray having a plurality of vacuum openings therethrough, each vacuum opening connecting the backside of the wafer to a vacuum passage in the wafer chuck, such that the vacuum secures the backside of the wafer to the tray; moving the contactor board and the tray relatively toward one another so that surfaces of contactor contacts mounted on the contactor board contact respective front wafer contacts on the front side of the wafer; conducting current between an electrical tester and circuitry on the wafer through the front-side wafer contacts and the contactor contacts to test the circuitry; and removing the wafer from the tray.

150. thermally connecting the tray to the thermal chuck; 150. The method of claim 149, further comprising: transferring heat between the thermal chuck and the wafer.

151. 151. The method of claim 150, wherein a fluid flows through the thermal passage of the thermal chuck, transferring heat between the fluid and the thermal chuck.

152. the tray has at least a portion that is electrically conductive and has an exposed surface for contacting a backside wafer terminal on the backside of the wafer; 150. The method of claim 149, wherein the circuit is connected to the electrical tester via the back wafer terminal, the exposed surface of the conductive portion, and the electrical path.

153. 153. The method of claim 152, wherein the tray includes electrical insulation around the entrance opening of each vacuum opening.

154. 153. The method of claim 152, further comprising contacting the wafer chuck with a ground contact of at least one wafer chuck pin mounted on the contactor board.

155. 155. The method of claim 154, wherein the wafer chuck pins extend beyond the edge of the tray.

156. 155. The method of claim 154, further comprising contacting the wafer chuck with a plurality of wafer chuck pins attached to the contactor board.

157. The tray includes a return terminal area electrically connected to an exposed surface thereof, the contactor face contact mounted on the contactor board is a power contactor face contact, and the electrical return conductor is 150. The method of claim 149, comprising a contactor return contact attached to the contactor board and having a surface positioned to contact a return terminal area on the tray.

158. a plurality of wafer contact pins mounted on the contactor board and the power contactor surface contacts disposed on the wafer contact pins; 158. The method of claim 157, wherein the contactor board has at least one return terminal pin attached thereto and the contactor return contact is on the return terminal pin.

159. 159. The method of claim 158, wherein the return terminal pin extends beyond the edge of the wafer.

160. 159. The method of claim 158, wherein a plurality of return terminal pins are attached to the contactor board.

161. The method further includes attaching the contactor board to a signal distribution board, the signal distribution board comprising: a signal distribution board; a signal distribution board contact on the signal distribution board substrate; a signal distribution board terminal on the signal distribution board; and a signal distribution board conductor connecting said signal distribution board contact to said signal distribution board terminal.

162. 162. The method of claim 161, further comprising the step of positioning a stiffener plate to support the signal distribution board substrate.

163. 1. A tester apparatus comprising: a vacuum conduit defining a vacuum passage; a wafer holder that releasably holds a wafer and has a plurality of vacuum openings therethrough, each vacuum opening connecting a backside of the wafer to a vacuum passage such that when a vacuum is applied to the vacuum passage, the vacuum secures the backside of the wafer; each vacuum opening includes an entrance opening at the wafer, an exit opening away from the wafer, and an enlarged section between the entrance opening and the exit opening to reduce arcing between the openings; a contactor panel; contactor contacts mounted on the contactor board and each having a surface positioned to contact a respective front wafer terminal on the front side of the wafer; an electrical tester connected to the contactor contacts such that, in use, current is conducted to and from circuitry on the wafer through the front-side wafer contacts and the contactor contacts to test the circuitry.

164. 164. The tester apparatus of claim 163, further comprising a thermal chuck to which, in use, the wafer holder is thermally connected and in thermal communication with the wafer.

165. 165. The tester apparatus of claim 164, wherein the thermal chuck has a thermal passage such that, in use, a fluid flows through the thermal passage to transfer heat between the fluid and the thermal chuck.

166. the wafer holder has at least a portion that is electrically conductive and has an exposed surface for contacting a backside wafer terminal on the backside of the wafer; 164. The tester apparatus of claim 163, further comprising: an electrical conductor connected to the conductive portion, such that, in use, the circuit is connected to the electrical tester via the back wafer contact, the exposed surface of the conductive portion, and the electrical path.

167. The wafer holder is a wafer chuck; a tray that releasably holds a wafer and is releasably disposed on the wafer chuck; 164. The tester apparatus of claim 163, comprising: the wafer chuck having a vacuum passage therethrough; and the tray having a plurality of vacuum openings therethrough, each vacuum opening connecting the backside of the wafer to a vacuum passage in the wafer chuck, such that when a vacuum is applied to the vacuum passage, the vacuum secures the backside of the wafer to the tray.

168. 168. The tester apparatus of claim 167, wherein the tray includes electrical insulation around the entrance opening of each vacuum opening.

169. the tray has at least a portion that is conductive and has an exposed surface that contacts a backside wafer terminal on the backside of the wafer; 168. The tester apparatus of claim 167, further comprising: a conductor connected to the conductive portion, such that, in use, the circuit is connected to the electrical tester via the back wafer contact, the exposed surface of the conductive portion, and the electrical path.

170. 170. The tester apparatus of claim 169, further comprising at least one wafer chuck pin having a ground contact attached to the contactor board and contacting the wafer chuck.

171. 171. The tester apparatus of claim 170, wherein the wafer chuck pins extend beyond the edge of the tray.

172. 171. The tester apparatus of claim 170, further comprising a plurality of wafer chuck pins.

173. The tray includes a return terminal area electrically connected to an exposed surface thereof, the contactor face contact mounted on the contactor board is a power contactor face contact, and the electrical return conductor is 170. The tester apparatus of claim 169, including a contactor return contact attached to the contactor board and having a surface positioned to contact the return terminal area on the tray.

174. a plurality of wafer contact pins attached to the contactor board and on which the power contactor front contacts are disposed; 164. The tester apparatus of claim 163, further comprising: at least one return terminal pin attached to the contactor substrate and on which the contactor return terminal is disposed.

175. 175. The tester apparatus of claim 174, wherein the return terminal pin extends beyond the edge of the wafer.

176. 175. The tester apparatus of claim 174, further comprising a plurality of return terminal pins.

177. Further comprising a signal distribution board, the signal distribution board comprising: a signal distribution board; a signal distribution board contact on the signal distribution board substrate; a signal distribution board terminal on the signal distribution board; and signal distribution board conductors connecting the signal distribution board contacts to the signal distribution board terminals.

178. 178. The tester apparatus of claim 177, further comprising a stiffener plate positioned to support the signal distribution board.

179. 1. A method for testing a wafer, comprising: releasably holding a wafer in a wafer holder having a plurality of vacuum openings therethrough, each vacuum opening connecting the backside of the wafer to the vacuum passage; applying a vacuum to the vacuum passage, the vacuum securing the backside of the wafer to the wafer holder; moving the contactor board and the tray relatively toward one another so that surfaces of contactor contacts mounted on the contactor board contact respective front wafer contacts on the front side of the wafer; conducting electrical current between an electrical tester and circuitry on a front side wafer through the front side wafer contacts and the contactor contacts to test the circuitry, wherein each vacuum opening has an entrance opening at the wafer, an exit opening away from the wafer, and an enlarged portion between the entrance and exit openings to reduce arcing between the openings.

180. thermally connecting the tray to the thermal chuck; 180. The method of claim 179, further comprising: transferring heat between the thermal chuck and the wafer.

181. 181. The method of claim 180, wherein a fluid flows through the thermal passages of the thermal chuck, transferring heat between the fluid and the thermal chuck.

182. 180. The method of claim 179, wherein the tray has at least a portion that is conductive and has an exposed surface for contacting a back wafer terminal on the back side of the wafer, and the circuit is connected to the electrical tester via the back wafer terminal, the exposed surface of the conductive portion, and the electrical path.

183. The wafer holder is a wafer chuck; a tray releasably positioned on the wafer chuck for releasably holding a wafer; 180. The method of claim 179, wherein the wafer chuck has a vacuum passage therethrough and the tray has a plurality of vacuum openings therethrough, each vacuum opening connecting the backside of the wafer to a vacuum passage in the wafer chuck, such that when a vacuum is applied to the vacuum passage, the vacuum secures the backside of the wafer to the tray.

184. 183. The method of claim 182, wherein the tray includes electrical insulation around the inlet opening of each vacuum opening.

185. 183. The method of claim 182, further comprising contacting the wafer chuck with a ground contact of at least one wafer chuck pin mounted on the contactor board.

186. 186. The method of claim 185, wherein the wafer chuck pins extend beyond the edge of the tray.

187. 187. The method of claim 186, further comprising contacting the wafer chuck with a plurality of wafer chuck pins mounted on the contactor board.

188. The tray includes a return terminal area electrically connected to an exposed surface thereof, the contactor face contacts mounted on the contactor board are power contactor face contacts, and the electrical return conductor is 180. The method of claim 179, including a contactor return contact attached to the contactor board and having a surface positioned to contact the return terminal area on the tray.

189. a plurality of wafer contact pins are attached to the contactor board, and the power contactor surface contacts are disposed on the wafer contact pins; 189. The method of claim 188, wherein at least one return terminal pin is attached to the contactor board, and the contactor return contact is located on the return terminal pin.

190. 190. The method of claim 189, wherein the return terminal pin extends beyond the edge of the wafer.

191. 190. The method of claim 189, wherein a plurality of return terminal pins are attached to the contactor board.

192. The method further includes attaching the contactor board to a signal distribution board, the signal distribution board comprising: a signal distribution board; a signal distribution board contact on the signal distribution board substrate; a signal distribution board terminal on the signal distribution board; and a signal distribution board conductor connecting said signal distribution board contact to said signal distribution board terminal.

193. 193. The method of claim 192, further comprising the step of positioning a stiffener plate to support the signal distribution board.

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