Electronic tester having a double-helix thermal control passage in a thermal chuck

Abstract

To provide a tester apparatus in which current may be transmitted between an electrical tester and an integrated circuit to test the integrated circuit.SOLUTION: A tester apparatus includes an electrical tester for connection through contacts to a plurality of terminals of at least one substrate that carries at least one integrated circuit and has the terminals connected to the integrated circuit. The tester apparatus includes power supply circuits connected to the contacts, and power is supplied to the tester apparatus through the power supply circuits connected to the contacts. There are a plurality of n+1 power supply circuits connected to one another in parallel such that power is supplied to the integrated circuit by n+1 of the power supply circuits, and even if one of the power supplies fails, power is still supplied to the integrated circuit by n of the circuits. The tester apparatus further includes a current-sharing circuit that detects a reduction in power of one of the (n+1) power supply circuits, and switches off a connection from the one of the (n+1) power supply circuits so that current is shared by the n power supply circuits.SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] The present invention relates to an apparatus used for full wafer test and / or burn-in test and / or burn-in self test.

[0002] Cross-reference to related applications: This application claims priority to U.S. Provisional Patent Application No. 60 / 910,433, filed Apr. 5, 2007, which is hereby incorporated by reference in its entirety.

Background Art

[0003] Microelectronic circuits are typically fabricated within and on a semiconductor wafer. Such wafers are then "singulated" or "diced" into individual dies. Such dies are typically mounted on a support substrate for the purpose of providing robustness and making electronic communication with the die's integrated circuit or microelectronic circuit. Final packaging includes encapsulation of the die and enables the completed package to be shipped to a customer.

[0004] It is necessary to test the die or package before shipping it to a customer. Ideally, the die must be tested at an early stage in order to identify defects that occur during the initial manufacturing stage.

Summary of the Invention

Problems to be Solved by the Invention

[0005] The earliest stage at which a die can be tested is after the manufacture of the microelectronic circuit at the wafer level is complete and before the wafer is singulated. Full wafer testing involves a number of challenges. One challenge in full wafer testing is that there are a large number of contact parts on the wafer, and thus a very large number of power, ground, and signal connections must be made. Another challenge is that while the wafer can be stably maintained at a relatively high temperature, a thermal management system that is simple to operate and relatively inexpensive is required for the burn-in test.

Means for Solving the Problem

[0006] A portable support structure for holding a substrate on which a microelectronic circuit (ultra-small electronic circuit) is mounted and having a plurality of terminals connected to the microelectronic circuit, a plurality of contact portions on the portable support structure that match the terminals for making contact with the terminals, and a first interface on the portable support structure that is connected to a second interface of a fixed structure when the portable support structure is removably held by the fixed structure. A portable pack is provided.

[0007] The portable support structure includes first and second components for holding a substrate therebetween, the contact portions are disposed on the second component, and the components are movable relative to each other to ensure proper contact between the contact portions and the terminals.

[0008] The second component includes a signal distribution board and a contactor, and the CTE ratio of the CTE of the signal distribution board to the CTE of the contactor is not 1. The contactor is heated from a first contactor temperature to a second contactor temperature during testing of the microelectronic circuit, the signal distribution board is heated from a first signal distribution board temperature to a second signal distribution board temperature, and the product of the CTE ratio and the temperature change ratio of the difference between the second signal distribution board temperature and the first signal distribution board temperature and the difference between the second contactor temperature and the first contactor temperature is closer to 1 than the CTE ratio.

[0009] The product of the temperature change ratio and the coefficient of thermal expansion ratio is from 0.8 to 1.2.

[0010] The first component is a substrate chuck having a surface for supporting the substrate.

[0011] The portable pack further includes a pressure - difference cavity seal between the first component and the second component, which forms a pressure - difference cavity surrounded by the surfaces of the first and second components. There is a pressure - reducing passage in the pressure - difference cavity, through which air can be removed from the pressure - difference cavity to relatively move the first and second components towards each other.

[0012] The pressure - difference cavity seal surrounds the contact part and the terminal.

[0013] The pressure - difference cavity seal is fixed to the first component when the first and second components separate.

[0014] The pressure - difference cavity seal is a lip seal.

[0015] A pressure - reducing passage is formed through one of the components. This pressure - reducing passage has an inlet opening to the pressure - difference cavity and an outlet opening outside the pressure - difference cavity. The component with the pressure - reducing passage has a first valve. When this first valve is opened, air can be discharged from the pressure - difference cavity, and when this valve is closed, air can be prevented from entering the pressure - difference cavity.

[0016] The first valve is a check valve. A vacuum - release passage is formed through the component having this check valve. This vacuum - release passage has an inlet opening to the pressure - difference cavity and an outlet opening outside the pressure - difference cavity. The component with the vacuum - release passage is provided with a second vacuum - release valve. When this vacuum - release valve is opened, air can be introduced into the pressure - difference cavity, and when this valve is closed, air can be prevented from escaping from the pressure - difference cavity.

[0017] The portable pack further includes a substrate suction passage in the first component, through which air is pumped to reduce the pressure on the side of the substrate facing the first component, so that the substrate can be held against the first component.

[0018] The contact portion can be pressed elastically by a terminal, and the portable pack further includes a standoff for a second component, the standoff having a surface that limits the pressing of at least one contact portion.

[0019] A plurality of separated standoffs are arranged between the contact portions.

[0020] The portable pack further includes a layer having an adhesive first side attached to the second component and an adhesive second opposite side, and the standoff is attached to the second side.

[0021] The first interface includes a plurality of lands, and the second interface includes a plurality of members having contact surfaces that match those lands and can be pressed elastically by those lands, and is made movable relative to a fixed structure.

[0022] The lands and the terminals are in parallel planes.

[0023] The substrate is a wafer having a plurality of microelectronic circuits.

[0024] The contact portion is a pin, and each pin has a spring that is pressed against its spring force when each contact portion is pressed by its respective terminal.

[0025] Furthermore, the present invention relates to a type of tester device including a portable support structure for holding a substrate on which a microelectronic circuit is mounted and having a plurality of terminals connected to the microelectronic circuit, a plurality of contact portions on the portable support structure that match the terminals for making contact with the terminals, a first interface on the portable support structure that is connected to the contact portions, a fixed structure that the portable support structure can be received by to be held by the fixed structure and can be removed from the fixed structure, a second interface in the fixed structure that is connected to the first interface when the portable support structure is held by the fixed structure and is disconnected from the first interface when the portable support structure is removed from the fixed structure, and an electrical tester connected to the terminals through the second interface, the first interface, and the contact portions, the electrical tester being configured to transmit a signal between the electrical tester and the microelectronic circuit to test the microelectronic circuit.

[0026] The portable support structure includes first and second components for holding the substrate therebetween, the contact portions are disposed on the second component, and the components are movable relative to each other to ensure proper contact between the contact portions and the terminals.

[0027] The second component includes a signal distribution board and a contactor, and the CTE ratio of the CTE of the signal distribution board to the CTE of the contactor is not 1. The contactor is heated from a first contactor temperature to a second contactor temperature during testing of the microelectronic circuit, the signal distribution board is heated from a first signal distribution board temperature to a second signal distribution board temperature, and the product of the CTE ratio and the temperature change ratio of the difference between the second signal distribution board temperature and the first signal distribution board temperature and the difference between the second contactor temperature and the first contactor temperature is closer to 1 than the CTE ratio.

[0028] The product of the coefficient of thermal expansion ratio and the temperature change ratio is from 0.8 to 1.2.

[0029] The first component is a substrate chuck having a surface for supporting a substrate.

[0030] The tester device further includes a pressure difference cavity seal between the first component and the second component, and this pressure difference cavity seal forms a pressure difference cavity surrounded by the surfaces of the first and second components. There is a decompression passage in the pressure difference cavity, and through this, air can be removed from the pressure difference cavity to relatively move the first and second components towards each other.

[0031] The pressure difference cavity seal surrounds the contact part and the terminal.

[0032] The pressure difference cavity seal is fixed to the first component when the first and second components separate.

[0033] The pressure difference cavity seal is a lip seal.

[0034] A decompression passage is formed through one of the components. This decompression passage has an inlet opening to the pressure difference cavity and an outlet opening outside the pressure difference cavity. The component having the decompression passage has a first valve. When this first valve is opened, air can be discharged from the pressure difference cavity, and when this valve is closed, air is prevented from entering the pressure difference cavity.

[0035] The first valve is a check valve, and a vacuum release passage is formed through the component having this check valve. This vacuum release passage has an inlet opening to the pressure difference cavity and an outlet opening outside the pressure difference cavity. The component having the vacuum release passage is provided with a second vacuum release valve. When this vacuum release valve is opened, air can be introduced into the pressure difference cavity, and when this valve is closed, air is prevented from escaping from the pressure difference cavity.

[0036] The tester device further includes a substrate suction passage in the first component, through which air is pumped to reduce the pressure on the side of the substrate facing the first component, enabling the substrate to be held against the first component.

[0037] The contact portion can be elastically pressed by a terminal, and the second component further includes a standoff, which has a surface that limits the pressing of at least one contact portion.

[0038] A plurality of separated standoffs are arranged between the contact portions.

[0039] The tester device further includes a layer having an adhesive first surface attached to the second component and an adhesive opposite second surface, and the standoff is attached to the second surface.

[0040] The first interface includes a plurality of lands, and the second interface includes a plurality of members having contact surfaces that match those lands and can be elastically pressed by those lands, and is configured to be movable relative to the fixed structure.

[0041] The lands and the terminals are in parallel planes.

[0042] The fixed structure includes a thermal chuck, and the portable support structure contacts this thermal chuck to enable heat transfer between the portable support structure and the thermal chuck.

[0043] A thermal interface cavity is defined (formed) between the portable support structure and the thermal chuck, and a thermal interface vacuum passage leading from the thermal chuck to the thermal interface vacuum is formed.

[0044] The tester device further includes a thermal interface cavity seal that contacts both the portable support structure and the thermal chuck, and this thermal interface cavity seal defines a thermal interface cavity together with the portable support structure and the thermal chuck.

[0045] The tester device further includes a thermal chuck in a fixed structure, and this thermal chuck has a thermal control passage with an inlet and an outlet, and there is at least one section between the inlet and the outlet to allow fluid to flow from the inlet to the outlet, and heat is transferred between the substrate and the fluid through the thermal chuck in the thermal control passage.

[0046] The thermal control passage has first, second, and third sections in series with each other along the path of the fluid, and the third section is located between the first and second sections in a cross-sectional plan view.

[0047] The thermal control passage has a fourth section in series after the third section along the path of the fluid, and this fourth section is located between the second and third sections.

[0048] The thermal control passage has a fourth section in series after the third section along the path of the fluid, and this fourth section is located between the first and second sections.

[0049] The first, second, and third sections are sections of the first helix.

[0050] The first and second sections are sections of the first helix, and the third section is a section of the second helix located on the first helix.

[0051] The tester device further includes a heater, and heat is transferred to the fluid by this heater when the fluid is outside the thermal control passage.

[0052] The heater is an electric heater.

[0053] Heat is transferred from the substrate to the fluid entering the fluid inlet above 21°C.

[0054] Heat is initially transferred from the fluid to the substrate after the fluid enters the fluid inlet at a temperature above 21°C.

[0055] The temperature of the fluid is higher than 100°C when the fluid enters the fluid inlet.

[0056] The fluid is recirculated.

[0057] The tester device further comprises at least one interface actuator having first and second actuator segments operable relative to each other to move the portable support structure relative to the fixed structure to engage the first interface with the second interface.

[0058] The first and second segments are each a cylinder and a piston, and the piston slides along the inner surface of the cylinder.

[0059] The test performed on the microelectronic circuit by the tester is a burn-in test.

[0060] The substrate is a wafer having a plurality of microelectronic circuits.

[0061] The contact portion is a pin, and each pin has a spring that is pressed against its spring force when each contact portion is pressed by each terminal.

[0062] The present invention also relates to a method for testing a microelectronic circuit held by a substrate, the method comprising the steps of holding the substrate on a portable support structure having contact portions for terminals of the substrate connected to the microelectronic circuit, receiving the portable support structure by a fixed structure such that a first interface of the portable support structure is connected to a second interface of the fixed structure, and transmitting signals between an electrical tester and the microelectronic circuit through the terminals, contact portions, first and second interfaces to test the microelectronic circuit.

[0063] The substrate is held between a first component and a second component of a portable support structure, the contact portion is on the second component, and further includes steps of relatively moving the first and second components toward each other to ensure proper contact between the contact portion and the terminal.

[0064] The portable support structure includes a first and a second element together with the substrate, and the CTE ratio of the CTE of the first element to the CTE of the second element is not equal to 1.

[0065] Preferably, the product of the CTE ratio and the temperature change ratio is between 0.8 and 1.2.

[0066] The first and second elements are a signal distribution board and a contactor on the same side of the substrate.

[0067] One of the elements is the substrate.

[0068] The first component is a substrate chuck having a surface for supporting the substrate.

[0069] The method further includes steps of disposing a pressure differential cavity seal between the first component and the second component to form a cavity surrounded by the surfaces of the first and second components and the pressure differential cavity seal, and reducing the pressure within the cavity of the pressure differential cavity seal to relatively move the first and second components toward each other.

[0070] The pressure differential cavity seal surrounds the contact portion and the terminal.

[0071] The pressure differential cavity seal is fixed to the first component when the first and second components separate.

[0072] The substrate cavity seal is formed of a lip seal.

[0073] A pressure reduction passage is formed through one of the components. This pressure reduction passage has an inlet opening to the pressure difference cavity and an outlet opening outside the pressure difference cavity. The component having the pressure reduction passage is provided with a first valve. Further, the first valve can be opened to discharge air from the pressure difference cavity, and the valve can be closed to prevent air from entering the pressure difference cavity.

[0074] The first valve is a check valve. A vacuum release passage is formed through the component having this check valve. This vacuum release passage has an inlet opening to the pressure difference cavity and an outlet opening outside the pressure difference cavity. The component having the vacuum release passage is provided with a second vacuum release valve. Further, the vacuum release valve can be opened to let air into the pressure difference cavity, and the valve can be closed to prevent air from escaping from the pressure difference cavity.

[0075] The pressure inside the pressure difference cavity is generated before the portable support structure is received by the fixed structure.

[0076] The method further includes pumping air through the substrate suction passage of the first component to reduce the pressure on the side of the substrate facing the first component and holding the substrate against the first component.

[0077] The contact part can be elastically pressed by a terminal, and further includes restricting the pressing of at least one contact part on the stand-off surface of the second component.

[0078] A plurality of separated stand-offs are arranged between the contact parts.

[0079] The method further includes a layer having a first adhesive surface attached to the second component and a second opposite adhesive surface. The stand-off is attached to the second surface.

[0080] The method further includes disposing lands of a first interface of a portable support structure against a plurality of mating members of a second interface of a fixed structure and elastically pressing those members at those lands.

[0081] The method further includes disposing a surface of the portable support structure against a surface of a thermal chuck of the fixed structure and transferring heat through those surfaces.

[0082] The method further includes reducing the air pressure of a thermal interface cavity defined between a surface of the portable support structure and the thermal chuck.

[0083] A thermal interface cavity is defined between the portable support structure and the thermal chuck, and a thermal interface vacuum passage is formed to the thermal interface vacuum through the thermal chuck.

[0084] The method further includes disposing a thermal interface cavity seal between the portable support structure and the thermal chuck and defining the thermal interface cavity with the thermal interface cavity seal, the portable support structure, and the thermal chuck.

[0085] The method further includes passing fluid from a fluid inlet to a fluid outlet through at least one section of a thermal control passage in the thermal chuck on the fixed structure and transferring heat between the fluid in the thermal control passage and the substrate to control the temperature of the substrate.

[0086] The thermal control passage has a first, a second, and a third section in series with one another along the path of the fluid, with the third section positioned between the first section and the second section in a cross-sectional plan view.

[0087] The thermal control passage has a fourth section in series after the third section along the path of the fluid, with this fourth section positioned between the second section and the third section.

[0088] The temperature of the thermal chuck between the second section and the third section is the temperature of the fluid in the second section from the temperature of the fluid in the first section, and the temperature of the thermal chuck between the first section and the fourth section is the temperature of the fluid in the second section from the temperature of the fluid in the first section.

[0089] The temperature difference between the fluid in the first section and the fluid in the fourth section is larger than that between the fluid in the second section and the fluid in the third section.

[0090] The thermal control passage has the fourth section in series after the third section along the fluid passage, and this fourth section is located between the first section and the second section.

[0091] The first, second, and third sections are the sections of the first helix.

[0092] The first and second sections are the sections of the first helix, and the third section is the section of the second helix that is not located on the first helix.

[0093] When the fluid enters the fluid inlet, the temperature of the fluid is higher than 100°C.

[0094] Heat is transferred from the substrate to the fluid entering the fluid inlet above 21°C.

[0095] After the fluid enters the fluid inlet above 100°C, heat is first transferred from the fluid to the substrate.

[0096] The fluid is recirculated.

[0097] The test executed by the microelectronic circuit is a burn-in test.

[0098] The substrate is a wafer having a plurality of microelectronic circuits.

[0099] The contact part is a pin, and each pin has a spring that is pressed against its spring force when each contact part is pressed by each terminal.

[0100] The present invention further provides a thermal chuck having a thermal control passage with an inlet, an outlet, and at least first, second, and third sections arranged in series one behind the other along a fluid path from the fluid inlet to the fluid outlet, and in a cross-sectional plan view, the third section is disposed between the first section and the second section.

[0101] The thermal control passage has, in series along the fluid path, a fourth section after the third section, and this fourth section is positioned between the second section and the third section.

[0102] The thermal control passage has, in series along the fluid path, a fourth section after the third section, and this fourth section is positioned between the first section and the second section.

[0103] The first, second, and third sections are sections of a first helix.

[0104] The first and second sections are sections of a first helix, and the third section is a section of a second helix that is not located on the first helix.

[0105] The present invention further relates to an electrical aspect of a tester device that includes an electrical tester connected through contact portions to a plurality of terminals of at least one substrate having at least one integrated circuit mounted thereon and terminals connected to the integrated circuit, and that conducts a current between the electrical tester and the integrated circuit to test the integrated circuit.

[0106] The tester device further includes a power supply circuit connected to the contact portions, and power is supplied through this power supply circuit connected to the contact portions.

[0107] A plurality of n + 1 power supply circuits are connected in parallel with each other, and power is supplied to the integrated circuit by these n + 1 power supply circuits. Even if one of the power supplies fails, power is still supplied to the integrated circuit by the n circuits.

[0108] The tester device further comprises a current sharing circuit, which (i) at least detects a decrease in power of one of the n + 1 power circuits, and (ii) switches off the connection from one of the n + 1 power circuits to remove the current from one of the n + 1 power circuits and share the current among the n power circuits.

[0109] The current sharing circuit comprises a plurality of defect detection circuits that respectively detect the power loss from each of the power circuits.

[0110] The tester device further comprises a power control circuit energized from at least one of the plurality of power circuits, and this power control circuit switches the power circuit between a test mode in which power is supplied by a first number of the plurality of power circuits and a power saving mode in which power is supplied by a second number of power circuits smaller than the first number.

[0111] The tester device further comprises a current configuration circuit configured to switch the current between a first configuration in which individual currents of different magnitudes are supplied to individual channels and a second configuration in which the currents to the individual channels follow a common reference.

[0112] This current configuration circuit comprises a plurality of current amplifiers each having an output current following an individual reference when it is in the first configuration.

[0113] The tester device further comprises a current amplifier that amplifies the current to the individual channels.

[0114] The tester device further comprises a signal electronic device that gives a signal to the integrated circuit.

[0115] The tester device further comprises a support structure for holding at least one substrate and a plurality of contact portions that match the terminals for contacting the terminals. The electrical tester is connected to the terminals through the contact portions, and a current is conducted between the electrical tester and the integrated circuit to test the integrated circuit.

[0116] Moreover, the present invention also relates to an electrical aspect of a method for testing at least one circuit held by at least one substrate, the method including arranging contact portions with respect to the terminals of the substrate connected to the integrated circuit and conducting a current between the electrical tester and the integrated circuit through these terminals and the contact portions to test the integrated circuit.

[0117] Power is supplied through a power supply circuit connected to the contact portion.

[0118] A plurality of n + 1 power supply circuits are connected in parallel with each other, and power is supplied to the integrated circuit of at least one substrate by these n + 1 power supply circuits. Even if one of the power supply circuits fails, power is still supplied to the integrated circuit by the n circuits.

[0119] The method further includes at least detecting a decrease in power of one of the n + 1 power supply circuits and switching off the connection from one of the n + 1 power supply circuits to remove the current from one of the n + 1 power supply circuits and share the current by the n power supply circuits.

[0120] The method further includes detecting the power loss from each of the power supply circuits with an individual defect detection circuit.

[0121] The method further includes supplying power from at least one of the plurality of power supply circuits to a power control circuit and using the power control circuit to switch between a test mode in which power is supplied by a first number of the plurality of power supply circuits and a power saving mode in which power is supplied by a second number of power supply circuits smaller than the first number.

[0122] The method further includes switching between a first configuration in which individual currents of different magnitudes are supplied to individual channels and a second configuration in which the currents to the individual channels follow a common reference.

[0123] The current configuration circuit includes a plurality of current amplifiers each having an output current following an individual reference when it is in the first configuration.

[0124] The method further includes amplifying the current to the individual channels.

[0125] The method further includes supplying a signal to an integrated circuit.

[0126] The present invention will be described in detail below by way of example with reference to the accompanying drawings.

Brief Description of the Drawings

[0127]

Figure 1

Figure 2

Figure 3

Figure 4

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Figure 8

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Figure 10

Figure 11

Figure 12

Figure 13A

Figure 13B

Figure 13C

Figure 14

Figure 15

DETAILED DESCRIPTION OF THE INVENTION

[0128] FIG. 1 of the accompanying drawings is a perspective view of a wafer chuck assembly 10, and FIG. 2 is a cross-sectional side view of a part of the wafer chuck assembly 10. The wafer chuck assembly 10 includes a wafer chuck component 12, a pressure differential substrate cavity seal 14, an offset ring 16, and a substrate suction passage valve 18.

[0129] The wafer chuck component 12 is made of aluminum or another metal having a relatively high thermal conductivity and has a predetermined relatively low coefficient of thermal expansion. The wafer chuck component 12 has a circular outer surface 20, and upper and lower surfaces 22, 24. The diameter of the outer surface 20 is typically from 350 to 450 mm, and more typically about 400 mm. The upper surface 22 has a number of grooves formed therein and extending to the outer surface 20. Also, the lower surface 24 is formed in a single plane extending to the outer surface 20. The planes of the upper surface 22 and the lower surface 24 are parallel to each other. The lower surface 24 has the same surface area as the upper surface 22.

[0130] The offset ring 16 has an upper surface 26 and a lower surface 28. The lower surface 28 of the offset ring 16 is positioned on the upper surface 22 of the wafer chuck component 12, and the offset ring 16 is fixed to the wafer chuck component 12 by a fixture 30. Accordingly, the upper surface 26 of the offset ring 16 is in a plane vertically spaced from the plane of the upper surface 22 of the wafer chuck component 12.

[0131] Also, the offset ring 16 also has an inner surface 32 and an outer surface 34. The inner surface 32, together with the central portion of the upper surface 22 of the wafer chuck component 12, defines a circular recess 36 for receiving a wafer having a circular outer edge. In the example shown here, the wafer has a diameter of about 200 mm. Larger wafers can be received by removing the offset ring 16.

[0132] The substrate cavity seal 14 is formed into a closed circular loop that completely surrounds the offset ring 16 and the recess 36 for the wafer. The substrate cavity seal 14 is a lip seal having a lower anchor portion 40 and an upper lip 42. The lower anchor portion 40 is fixed in a groove formed in an outer region of the upper surface 22 of the wafer chuck component 12. The lower anchor portion 40 is fixed in the groove due to the thermoelastic characteristics of the substrate cavity seal 14. The lip 42 has an upper surface 46 in a plane vertically spaced from the plane of the upper surface 26 of the offset ring 16. The upper surface 46 of the lip 42 can be elastically pressed in a direction toward the wafer chuck component 12. The pressure applied to the upper surface 46 bends the lip 42 so that the upper surface 46 moves downward, and when the pressure is removed, the upper surface 46 moves upward due to the elasticity of the lip 42.

[0133] A substrate suction passage 50 is formed in the wafer chuck component 12. This substrate suction passage 50 includes first, second, and third portions 52, 54, and 56. The first portion 52 is drilled from the outer surface toward the center of the wafer chuck component 12. The second portion 54 has a length that is approximately one-third of the diameter of the outer surface 20 of the wafer chuck component 12. The first portion 52 is drilled from the upper surface 22 of the wafer chuck component 12, and the first portion 52 forms an air inlet opening 60 in the upper surface 22 of the wafer chuck component 12. The third portion 56 is drilled from the lower surface 24 of the wafer chuck component 12 to the second portion 54 near the periphery of the lower surface 24. The third portion 56 forms an air outlet opening 62 in the lower surface 24.

[0134] Three circular grooves 64, 66, and 68 and a slot 70 are formed in the upper surface 22 of the wafer chuck component 12. The circular grooves 64, 66, and 68 are concentric with a center point that coincides with the center point of the outer surface 20 of the wafer chuck component 12. The slot 70 is formed to the same depth as the circular grooves 64, 66, and 68 and connects the circular grooves 64, 66, and 68 to each other. The air inlet opening 60 is disposed in the slot 70 between the circular grooves 66 and 68.

[0135] The substrate suction passage valve 18 is a shuttle valve inserted from the outer surface 20 of the wafer chuck component 12 to the second portion 54 of the substrate suction passage 50, and the second portion 54 of the substrate suction passage is then closed by a plug 72. The substrate suction passage valve 18 has a seat portion 74 and a ball valve component 76. When the pressure at the air outlet opening 62 is lower than the pressure at the air inlet opening 60, the ball valve component 76 is lifted from the seat portion 74 to allow air to flow from the air inlet opening 60 to the air outlet opening 62. The ball valve component 76 is placed on the seat portion 74 when the pressure at the air inlet opening 60 is lower than that at the air outlet opening 62, thereby preventing air from flowing from the air outlet opening 62 to the air inlet opening 60.

[0136] The pressure relief opening 80 is formed in the lower surface 24 of the wafer chuck component 12 and is connected to the second portion 54 of the substrate suction passage 50 on the side of the substrate suction passage valve 18 opposite to the air inlet opening 60. In a situation where the pressure at the air inlet opening 60 is lower than that at the air outlet opening 62 and the ball valve component 76 is placed on the seat portion 74, the pressure at the relief opening 80 can be made lower than the tip pressure at the air inlet opening 60 to lift the ball valve component 76 from the seat portion 74. When the ball valve component 76 is lifted from the seat portion 74, air flows from the air inlet opening 60 through the ball valve component 76 to the air outlet opening 62.

[0137] FIG. 2 also shows the wafer substrate 82 before being inserted into the wafer chuck assembly 10. The vertical dimension of the wafer substrate 82 is enlarged for purposes of illustration. The wafer substrate 82 has an upper surface 84, a parallel lower surface 86, and a circular edge 88. Also, in the wafer substrate 82, a plurality of integrated microelectronic circuits 90 are formed under the upper surface 84 and spaced apart from the lower surface 86. Each integrated microelectronic circuit 90 includes a plurality of electronic components such as capacitors, diodes and / or transistors, which are interconnected to each other using metal lines, plugs and vias. Also, the wafer substrate 82 also has a plurality of metal terminals 92 on the upper surface 84. In the embodiment shown herein, the upper surface of the terminal 92 forms a plane slightly above the upper surface 84. Therefore, in the embodiment shown herein, the total thickness of the wafer substrate 82 is measured from the lower surface 86 to the upper surface of one terminal 92. A plurality of terminals 92 are connected to each of the integrated microelectronic circuits 90.

[0138] In use, the air inlet opening 60 and the release opening 80 are maintained at ambient pressure. Then, the wafer substrate 82 is placed within the recess 36. The lower surface 86 of the wafer substrate 82 is positioned over the upper surface 22 of the wafer chuck component 12. The edge 88 of the wafer substrate 82 is fitted within the inner surface 32 of the offset ring 16.

[0139] A small surrounding space is defined between the slot 70 and the lower surface 86. Referring to FIGS. 1 and 2, the surrounding space extends to the circular grooves 64, 66 and 68, which are closed from above by the lower surface 86 of the wafer substrate 82. A pump is connected to the air outlet opening 62 and is used to lower the pressure of the air outlet opening 62 below the ambient pressure. Therefore, the pressure of the air outlet opening 62 is lower than the pressure of the air inlet opening 60, and thus the ball valve component 76 is lifted from the seat 74. A small amount of air is pumped from the surrounding cavity defined by the circular grooves 64, 66, 68 and the slot 70, through the substrate suction passage 50, through the substrate suction passage valve 18, and out of the air outlet opening 62. Therefore, the surrounding opening defined by the circular grooves 64, 66, 68 and the slot 70 is lower than the ambient pressure. The upper surface 84 of the wafer substrate 82 is at the ambient pressure. The pressure of the lower surface 86, which is lower than the upper surface 84 of the wafer substrate 82, holds the lower surface 86 of the wafer substrate 82 against the upper surface 22 of the wafer chuck component 12. The alignment of the wafer substrate 82 with respect to the wafer chuck assembly 10, particularly the alignment of the terminals 92, is maintained by holding the wafer substrate 82 against the upper surface 22 of the wafer chuck component 12.

[0140] Next, the air outlet opening 62 can be brought back to the ambient pressure again. Since the air inlet opening 60 is still lower than the ambient pressure, the ball valve component 76 remains seated in the seat 74 even after the air outlet opening 62 has returned to the ambient pressure. Whenever it is necessary to remove the wafer substrate 82 from the wafer chuck assembly 10, the release opening 80 can be brought to a pressure lower than the pressure of the air inlet opening 60. Therefore, the air inlet opening 60 has a higher pressure than the release opening 80, and the ball valve component 76 is lifted from the seat 74. Then, the air inlet opening 60 is connected to the air outlet opening, and a small amount of air flows from the air outlet opening into the air inlet opening 60 and into the circular grooves 64, 66, 68 and the slot 70. Thereby, the lower surface 86 of the wafer substrate 82 is brought to the ambient pressure and thus to the same pressure as the upper surface 84 of the wafer substrate 82. Now, the wafer substrate 82 can be removed from the wafer chuck assembly 10.

[0141] Figures 3 and 4 show a portable pack 108 for holding a wafer substrate 82, the portable pack 108 including a wafer chuck assembly 10 and a distribution board assembly 110. Figures 3 and 4 do not show in detail the contact portions, interfaces, and electrical paths including vias of the distribution board assembly 110. Accordingly, only the structural parts of the distribution board assembly 110 are shown. The structural parts include a metal backing plate 114, a signal distribution board 116, and a backing member 118 for a contact.

[0142] The metal backing plate 114 is substantially square. A circular opening 120 is formed in the metal backing plate 114. Two opposite edges 122 of the metal backing plate 114 are processed such that the remaining portion of the metal backing plate 114 is slightly thicker than the opposite edges 122, and each opposite edge defines each flange.

[0143] The signal distribution board 116 includes a substantially square substrate 124 that is slightly smaller than the metal backing plate 114. The signal distribution board 116 is positioned between the flanges defined by the opposite edges 122, and a fixture 126 is used to fix the substrate 124 to the metal backing plate 114.

[0144] The backing member 118 for the contact is circular and is positioned at the center of the substrate 124 opposite to the signal distribution board 116. A clamping ring 128 is positioned on the edge of the backing member 118. A fixture 130 is used to fix the clamping ring to the substrate 124 of the signal distribution board 116. The clamping ring 128 has an outer edge larger than the backing member 118 for the contact and an inner edge slightly smaller than the backing member 118 for the contact. Due to the dimensions of the clamping ring 128, the clamping ring 128 fixes the backing member 118 for the contact to the substrate 124 of the signal distribution board 116. The outer diameter of the clamping ring 128 is slightly smaller than the diameter of the inner surface 32 of the offset ring 16 of the wafer chuck assembly 10.

[0145] The signal distribution board 116 further has a gold metal seat portion 134 on the substrate 124. The inner diameter and outer diameter of this gold metal seat portion 134 are in the form of a ring that is slightly smaller and slightly larger than the diameter of the upper surface 46 of the substrate cavity seal 14, respectively.

[0146] All components of the distribution board assembly 110 have relatively high and similar coefficients of thermal expansion.

[0147] FIG. 5 shows the portable pack 108 after the distribution board assembly 110 is positioned on the wafer chuck assembly 10. The gold metal seat portion 134 is disposed at the bottom of the distribution board assembly 110 and is positioned on the substrate cavity seal 14 on the wafer chuck assembly 10.

[0148] Referring to FIG. 6, the substrate cavity seal 14 is disposed between the lower wafer chuck component 12 and the substrate 124 of the upper signal distribution board 116. The wafer chuck component 12, the substrate cavity seal 14, and the substrate 124 of the signal distribution board 116 together define an enclosed pressure differential cavity 140. This pressure differential cavity 140 extends into the space between the wafer substrate 82 and the contact backing member 118. Before the lip 42 of the substrate cavity seal 14 is deflected, the pressure differential cavity 140 extends into the space between the offset ring 16 of the wafer chuck assembly 10 and the substrate 124 of the signal distribution board 116. Also, the pressure differential cavity 140 extends into a circular groove 142 formed in the upper surface 22 of the wafer chuck component 12, and the raised portion of the clamp ring 128 is positioned within the groove 142. A small space is provided between the lower surface of the clamp ring 128 and the upper surface of the groove 142 to allow communication between the inner and outer volume portions of the pressure differential cavity 140 inside and outside the clamp ring 128.

[0149] A vacuum passage 144 is formed within the wafer chuck component 12, and a vacuum passage check valve 146 is disposed within the vacuum passage 144. The vacuum passage 144 includes first, second, and third portions 148, 150, and 152. The first portion 148 is drilled from the upper surface 22 of the wafer chuck component 12 to form an inlet opening 154 in the upper surface 22. The third portion 152 is drilled from the lower surface 24 of the wafer chuck component 12 to form an outlet opening 156 in the lower surface 24. The second portion 150 is drilled from the outer surface 20 of the wafer chuck component 12 to connect the first and second portions 148 and 150 to each other. The vacuum passage check valve 146 is inserted into the second portion 150 from the outer surface 20 of the wafer chuck component 12 and uses a plug 158 to close the inlet of the second portion 150 at the outer surface 20.

[0150] The vacuum passage check valve has a valve component 162 and a seat 164. The valve component 162 lifts off the seat 164 when air flows from the inlet opening 154 to the outlet opening 156. The valve component 162 being seated on the seat 164 prevents air from flowing from the outlet opening 156 to the inlet opening 154.

[0151] The offset ring 16 has a plurality of slots 168 formed in its lower surface. One of the slots 168 is shown in cross-section in FIG. 6 and connects the inlet opening 154 of the vacuum passage 144 to the pressure differential cavity 140. Yet another slot 168 extends radially toward the center of the offset ring 16 and is connected to the inlet opening 154 of the vacuum passage 144 together with a circular groove 142 in the lower surface of the offset ring 16.

[0152] In use, the pressure differential cavity 140 is initially at ambient pressure and the outlet opening 156 is connected to a pump such that it is lower than ambient pressure. Thus, a pressure differential is created between the air inlet opening 154 and the outlet opening 156, and air is pumped from the pressure differential cavity 140 through the pressure relief passage check valve 146 of the pressure relief passage 144. The pressure within the pressure differential cavity 140 drops below ambient pressure. The pressure outside the portable pack 108 is maintained at ambient pressure, and thus a pressure differential is created, with the pressure within the pressure differential cavity 140 being lower than the pressure above the substrate 124 of the signal distribution board 116 and below the lower surface 24 of the wafer chuck component 12. Due to this pressure differential, the lip 42 of the substrate cavity seal 14 deflects and the vertical height of the pressure differential cavity 140 decreases.

[0153] The vertical height of the pressure differential cavity 140 continues to decrease until the lower surface of the substrate 124 of the signal distribution board 116 comes into contact with the upper surface of the offset ring 16. Thus, the offset ring 16 restricts the relative movement of the substrate 124 of the signal distribution board 116 and the wafer chuck component 12 towards each other.

[0154] Next, the outlet opening 156 is returned to ambient pressure and can be disconnected from the pump. The valve component 162 is seated on the seat 164 to prevent air from entering the pressure differential cavity 140 through the pressure relief passage 144. Thereby, the pressure differential cavity 140 maintains its reduced size and the substrate 124 of the signal distribution board 116 contacts the offset ring. The portable pack 108 can then be removed from the device used to connect the pump to the outlet opening 156 to lower the pressure within the pressure differential cavity 140 and transported to a subsystem tester.

[0155] As shown in FIG. 7, the backing member 118 forms a portion of the contactor 170, which further includes a plurality of pins 172, standoffs 174, and an adhesive 176.

[0156] Each of the pins 172 has first and second components 178 and 179 and respective springs 182. The first component 178 has a cavity, and within this cavity the spring 182 is disposed. A portion of the second component 179 is also disposed within the cavity that holds the spring 182. The first and second components 178 and 179 are attached to each other and are movable relative to each other. When the terminals of the second component 179 move relatively towards the terminals of the first component 178, the spring 182 is compressed. Thus, in order for the terminals of the first and second components 178 and 179 to move towards each other, a force is required that overcomes the spring force of the spring 182. This force ensures proper contact between the pin 172 and the terminal 92 of the wafer substrate 82. When this force is removed, the terminals of the first and second components 178 and 179 move away from each other under the spring force of the spring 182. In another embodiment, a spring force can be generated by a component such as another spring or a membrane that is not a coil spring.

[0157] The backing member 118 is formed of two half - parts, each half - part having each set of openings formed therein. One terminal of one pin 172 is inserted through one opening in one half - part of the backing member 118, and the other terminal of the pin 172 is inserted through one opening in the other half - part of the backing member 118. The terminals of each pin 172 are inserted through each pair of openings in the two half - parts of the backing member 118. The pin 172 is held within the backing member 118 when the half - parts of the backing member 118 are fixed to each other. The terminals of the pin 172 form each array of contact portions 184 at the bottom of the contactor 170 and the corresponding array of contact portions 186 at the top of the contactor 170.

[0158] The signal distribution board 116 includes, in addition to the substrate 124, a plurality of contact portions 188, a plurality of lands 193, and a plurality of metal wires 191. The contact portions 188 and the lands 193 are arranged on the same surface of the substrate 124. The contact portions 188 are within the substrate cavity seal 14 shown in FIG. 4, and the lands 193 are outside the substrate cavity seal 14. Each of the metal wires 191 connects each of the contact portions 188 to each of the lands 193. Accordingly, each conductor is formed by each contact portion 188, each metal wire 191, and each land 193 of the signal distribution board 116. When the backing member 118 of the contactor 170 is fixed to the substrate 124 of the signal distribution board 116, each of the contact portions 186 of the contactor 170 contacts each of the contact portions 188 of the signal distribution board 116.

[0159] The standoff 174 is a thin layer of material attached to the lower surface of the backing member 118 of the contactor 170. The adhesive 176 is a layer having upper and lower adhesive surfaces. The lower adhesive surface of the adhesive 176 is attached to the upper surface of one standoff 174. The upper adhesive surface of the adhesive 176 is attached to the lower surface of the backing member 118 of the contactor 170, thereby attaching the standoff 174 to the backing member 118 of the contactor 170.

[0160] When the pressure in the pressure difference cavity 140 of FIG. 6 is reduced, the standoff 174 moves closer to the wafer substrate 82. Such movement of the standoff 174 toward the wafer substrate 82 elastically presses the contact portion 184 of the contactor 170 by the terminal 92 of the wafer substrate 82. Subsequently, the lower surface of the standoff 174 comes into contact with the upper surface 84 of the wafer substrate 82. Thereby, the lower surface of the standoff 174 limits the pressing of the contact portion 184 against the backing member 118 of the contactor 170. A plurality of separated standoffs 174 are arranged between the contact portions 184.

[0161] A plurality of conductive paths are formed. Each conductive path includes one of each terminal 92 of the wafer substrate 82, each pin 172 of the contactor 170, each contact portion 188, metal wire 191, and land 193 of the signal distribution board 116. The lands 193 and contact portions 188 of the signal distribution board 116 are in a plane parallel to the plane of the terminals 92 of the wafer substrate 82. Referring again to FIG. 1, a portable support structure is provided by the cooperation of the wafer chuck component 12 at the bottom and the structural components of the distribution board assembly 110 at the top, and the wafer substrate 82 is disposed between the wafer chuck component 12 and the structural components of the distribution board assembly 110. Referring again to FIG. 7, electrical contact to the terminals 92 of the wafer substrate 82 is provided by the contact portions 184 of the contactor 170, and the distribution board assembly 110 has an interface formed by the lands 193 for connection to another device. The portable pack 108 shown in FIGS. 4 to 7 is here conveyed to a test system that makes contact with the interface formed by the lands 193 and supplies test signals, power, and ground to the wafer substrate 82. The contact portions 184 of the contactor 170 and the terminals 92 of the wafer substrate 82 are completely surrounded by the substrate cavity seal 14, and thus are kept free of contaminants and moisture.

[0162] As shown in FIG. 8, the portable pack 108 is received by a fixed structure 180. The fixed structure 180 has a frame 181 located at a fixed position (not shown) of the system. The components of the fixed structure 180 can move relative to each other. In addition to the frame 181, the fixed structure 180 includes a holding structure 185 for receiving the portable pack 108, four actuators 187 (only one is shown), an interface assembly 189, a thermal chuck 190, and a mounting structure 192 for the thermal chuck 190. The actuator 187 includes a cylinder 194, a piston 196 within the cylinder 194, and a connection piece 198 connected to the piston 196. The piston 196 can slide vertically up and down within the cylinder 194, and the pressure can be increased and decreased behind and in front of the piston 196 to move the piston vertically upward and downward. The lower end of the connection piece 198 is attached to the piston 196, and the upper end thereof is attached to the holding structure 185. Accordingly, the holding structure 185 moves up and down together with the piston 196.

[0163] The interface assembly 189 has an interface assembly substrate 200 and a plurality of pins 202. The pins 202 are held within the interface assembly substrate 202. The interface assembly substrate 200 is fixed to the upper surface of the frame 181. The interface assembly substrate 200 and the frame 181 define a circular opening 204 that is slightly larger than the diameter of the outer surface 20 of the wafer chuck component 12.

[0164] A horizontal slot 205 is formed inside the holding structure 185. Similar slots (not shown) are formed in another part of the holding structure 185. The flange of the edge 122 of the metal backing plate 114 of the distribution board assembly 110 is inserted into the slot 205 in the direction towards the paper plane. The opposite edge (see FIG. 3) is also inserted into the other slot of the holding structure 185 simultaneously. The portable pack 108 is then suspended by the opposite part of the holding structure 185. The slot 205 holds the flange formed on the edge 122 and prevents the vertical movement of the portable pack 108 above or below the holding structure 185. When the piston 196 moves downward inside the cylinder 194, the holding structure 185 also moves downward, and the portable pack 108 moves downward to contact the interface assembly 189 of the fixed structure 180.

[0165] Referring again to FIG. 7, the components of the fixed structure 180 of FIG. 8 including the interface assembly 189 and the signal and power board 206 are shown. Each of the pistons 202 includes the first and second components 208 and 210 and a spring 212. A part of the second component 210 is disposed inside a part of the first component 208. The spring 212 is also disposed inside a part of the first component 208. The pin 202 has two opposing contact portions on the first and second components 208 and 210 respectively. To move the contact portions towards each other, a force is required to compress the spring 212 against the spring force of the spring 212. The contact portions move away from each other when the force compressing the spring 212 is removed.

[0166] The interface assembly substrate 200 has two half - parts, and a plurality of openings are formed in each half - part. The pin portions of the first component 208 and the second component 210 are inserted into the opposing openings of the two half - parts. Thus, each pin 202 has a contact portion at the top and a contact portion at the bottom of the interface assembly 189.

[0167] The signal and power board 206 has a substrate 214, a plurality of contact portions 216, and a plurality of metal leads 218 in the form of traces, wires, and / or vias. The contact portions 216 are formed on the upper surface of the substrate 214. The metal leads 218 are connected to the contact portions 216.

[0168] The interface assembly substrate 200 is mounted on the substrate 214 of the signal and power board 206. The contact portions of each first component 208 of each pin 202 are brought into contact with the respective contact portions 216 of the signal and power board 206. The interface assembly 189 shown in FIG. 7 is mounted to the frame 181 shown in FIG. 8 through the signal and power board 206. When the portable pack 108 moves downward so as to contact the interface assembly 189, each of the lands 193 of the signal distribution board 116 comes into contact with the contact portions at each second component 210 of each pin 202 of the interface assembly 189. The lands 193 press the contact portions at the top of the pins 202 when the portable pack 108 moves further downward. The force generated by the actuator 187 in FIG. 8 ensures proper contact between the lands 193 and the pins 202.

[0169] Next, the terminals of the wafer substrate 82 are connected to the contact portions 216 and the metal leads 218 of the signal and power board 206 via the pins 172 of the contactor 170, the contact portions 188, the wires 191, and the lands 193 of the signal distribution board 116, and the pins 202 of the interface assembly 189.

[0170] Referring again to FIG. 8, the mounting assembly 192 includes a plurality of mounting pieces 220 (only one is shown) and a spring assembly 224. The thermal chuck 190 is mounted to the frame 181 through each of the mounting pieces 220 and each spring assembly 224. When the portable pack 108 moves downward, the lower surface 24 of the wafer chuck component 12 is brought into contact with the upper surface of the thermal chuck 190. Some difference in flatness between the lower surface 24 of the wafer chuck component 12 and the upper surface of the thermal chuck 190 is absorbed by the spring assembly 224.

[0171] Figure 9 shows the thermal chuck 190, the mounting fragment 220, the thermal interface cavity seal 226, and the two adapters 228, 230.

[0172] The thermal interface cavity seal 222 is an O-ring seal formed in a circular groove 242 on the upper surface 232 of the thermal chuck 190. The thermal interface cavity seal 226 forms a closed loop around the center point of the thermal chuck 190. Approximately two-thirds of the thermal interface cavity seal 226 is inserted into the groove on the upper surface 232 of the thermal chuck 190, and approximately one-third of the thermal interface cavity seal 226 remains above the upper surface 232. The groove for the thermal interface cavity seal 226 has a substantially rectangular cross-section and can receive the entire thermal interface cavity seal 226. When one-third of the thermal interface cavity seal 226 above the upper surface 232 is compressed into the groove, the upper surface of the thermal interface cavity seal 226 becomes flush with the upper surface 232.

[0173] A thermal interface vacuum passage 234 is formed from the upper surface 232 to the lower surface 236 of the thermal chuck 190. A plurality of vacuum grooves 240 are formed in the upper surface 232 of the thermal chuck 190 in the area within the thermal interface cavity seal 226. The thermal interface vacuum passage 234 has an inlet opening in one of the vacuum grooves 240. One of the vacuum grooves 240 is a slot extending radially from the center point of the upper surface 232 of the thermal chuck 190. Four vacuum grooves 240 are concentric rings having a center point at the center point of the upper surface 232 of the thermal chuck 190. The vacuum grooves 240 are connected to each other, thus forming a single interconnected cavity under the upper surface of the thermal chuck 190.

[0174] A vacuum port 242 is formed from the upper surface 232 to the lower surface 236 in the area of the upper surface 232 outside the thermal interface cavity seal 226. A vacuum port seal 244 is formed in the groove surrounding this vacuum port 242. The vacuum port 242 is aligned and connected to the outlet opening 156 of the decompression passage 144 in the wafer chuck component 12 shown in FIG. 6.

[0175] In use, the lower surface 24 of the wafer chuck component 12 of FIG. 6 contacts the thermal interface cavity seal 226 and the vacuum port seal 244 shown in FIG. 9. The thermal interface cavity is defined at its bottom by the upper surface 232 of the thermal chuck 190, at its top by the lower surface 24 of the wafer chuck component 12, and at its sides by the thermal interface cavity seal 226 that connects the upper surface 232 of the thermal chuck 190 to the lower surface 24 of the wafer chuck component 12. The thermal interface vacuum passage 234 is permanently connected to a pump through a valve (not shown), and air is pumped from the thermal interface cavity through the thermal interface vacuum passage, thereby reducing the pressure within the thermal interface cavity. Accordingly, the pressure within the thermal interface cavity is lower than the ambient pressure above the portable pack 108 and the ambient pressure below the thermal chuck 190. The thermal interface cavity decreases in size until the lower surface 24 of the wafer chuck component 12 contacts the upper surface 232 of the thermal chuck 190 and the thermal interface cavity seal 226 is compressed into its groove. Accordingly, the only remaining portion of the thermal interface cavity is defined by the vacuum groove 240, and the pressure that has dropped within the vacuum groove 240 is maintained, holding the surfaces 24 and 232 together. Since the surfaces 24 and 232 are held together, heat can be transferred in both directions between the thermal chuck 190 and the wafer chuck component 12.

[0176] The vacuum port seal 244 seals with the lower surface 24 of the wafer chuck component 12 around the outlet opening 156 of the decompression passage 144. The pump maintains the vacuum port 242 at a low pressure, and thus maintains the outlet opening 156 at a low pressure in the event of a leak in the decompression passage check valve 146.

[0177] The thermal chuck 190 is made of an upper fragment 252 and a lower fragment 254 that are brazed to each other. A thermal control passage 256 is machined on the lower surface of the upper fragment 252. As particularly shown in FIG. 9, the thermal control passage 256 has an inlet 258 and an outlet 260 formed through the lower fragment 254. Fluid flows out from the outlet 260 through successive sections of the thermal control passage from the inlet 258. The first half portion of the thermal control passage 256 forms a first helix 268 that proceeds clockwise towards the center of the thermal chuck 190 in a plan view. The second half of the thermal control passage 256 forms a second helix 270 that moves counterclockwise away from the center of the thermal chuck 190. Two sections of the first helix 268 have one section of the second helix 270 therebetween. Two sections of the second helix 270 have one section of the first helix 268 therebetween. Thus, the thermal control passage 256 has, for example, first, second, and third sections in series with each other front to back, and in a cross-sectional plan view, the third section is disposed between the first section and the second section. Also, the thermal control passage 256 has a fourth section in series after the third section. Depending on where the fourth section is selected, the fourth section may be either between the second section and the third section, or between the first section and the second section. In any case, the first and second sections are sections of the first helix, and the third section is a section of the second helix that is not disposed in the first helix.

[0178] For example, there is a temperature difference of 10°C between the fluid flowing through the inlet 258 and the fluid flowing out of the outlet 260. Therefore, the adjacent sections of the thermal control passage 256 in the outer region of the thermal chuck 190 have a temperature difference of 10°C. However, the temperature between the two sections in the outer region of the thermal chuck 190 is the average value of the temperatures of the inlet 258 and the outlet 260, that is, 5°C above and below the temperatures of the inlet 258 and the outlet 260. Since heat is conducted from the fluid when the fluid flows towards the center of the thermal chuck 190, the temperature of the fluid between the adjacent sections of the thermal control passage 256 near the center of the thermal chuck 190 may be only 4°C. However, the temperature difference between the adjacent sections of the thermal control passage 256 near the center of the thermal chuck 190 is still the same as the average value of the inlet 258 and the outlet 260. Therefore, the thermal chuck 190 is the same in the outer region and near its center.

[0179] The adapters 228 and 230 are attached to the thermal chuck 190 and connected to the inlet 258 and the outlet 260.

[0180] FIG. 10 shows a tester device 300 including a plurality of components shown in FIG. 8, namely a plurality of portable packs 108, a plurality of thermal chucks 190, and a plurality of interface assemblies 189. Each portable pack 108 is connected to each thermal chuck 190, and each portable pack 108 has each interface of the lands that contact each interface of the pins regardless of the interface assembly 189. The tester device 300 further includes a plurality of electrical testers 302 and a thermal control system 304.

[0181] One or two electrical testers 302 are connected to each portable pack 108. Each electrical tester 302 is configured to perform a burn-in test based on a pre-programmed set of instructions. These instructions are used to exchange electrical signals through each interface assembly 189 between the microelectronic circuits of a wafer substrate (not shown) held in the portable pack 108. The thermal control system includes inlet and outlet pipes 306 and 308, inlet and outlet manifolds 310 and 312, a cooling heat exchanger 314, a recirculation pump 316, and a heater assembly 318. Each inlet pipe 306 is disconnected from each adapter such as adapter 228 of FIG. 9, and each outlet pipe 308 is connected to each adapter such as adapter 230 of FIG. 9. A closed-loop valve is formed by the thermal control passage 256 in one thermal chuck 190, one outlet pipe 308, the outlet manifold 312, the path through the heat exchanger 314, the pump 316, the path through the heater assembly 318, the inlet manifold 310, and one inlet pipe 306. The thermal control passage 256 of the thermal chuck 190 is connected in parallel to the manifolds 310 and 312.

[0182] The heat exchanger 314 also has a path connected to a water source and a drain. Water at room temperature can be flowed through the heat exchanger 314 to conduct heat to the water.

[0183] The heater assembly 318 has an electric coil connected to a power source. This electric coil generates heat when the power source is switched on. Heat can be transferred from the heating coil when an electric current flows.

[0184] In use, the components that define the recirculation path are first filled with oil. The pump 316 is switched on and the oil is recirculated through the heater assembly 318, the inlet manifold 310, the inlet pipe 306, the thermal chuck 190, the outlet pipe 308, the outlet manifold 312, and back to the pump 316 through the heat exchanger 314. When the power is switched on, the electric coil of the heater assembly 318 generates heat and the heat is transferred from the electric coil to the oil. The oil is heated from a room temperature of 21 °C to a temperature of about 100 °C, typically about 170 °C. The 170 °C oil enters the thermal chuck 190 and gradually heats the thermal chuck 190. Since heat is transferred to the thermal chuck 190, the oil exiting the thermal chuck 190 through the outlet pipe 308 is, for example, at a lower temperature of 150 °C. When the thermal chuck 190 is heated to a sufficiently high temperature to test the integrated microelectronic circuit 90 of FIG. 2, the electrical tester tests the integrated microelectronic circuit 90. The burn-in test is typically performed on the integrated microelectronic circuit 90.

[0185] As the integrated microelectronic circuits are tested, they are gradually heated and it becomes necessary to cool them to maintain a temperature suitable for the burn-in test. The current to the electric coil of the heater assembly 318 is switched off. Water from a water source is switched on. Heat is transferred from the oil to the water of the water source to cool the oil. The oil entering the thermal chuck 190 is now, for example, at 160 °C and the oil exiting the thermal chuck 190 is at 170 °C. The heat exchanger 314 cools the oil from 170 °C to 160 °C. Note that it is typically not necessary to cool the oil below 150 °C. Tests have shown that it is not necessary to lower the temperature of the oil, for example, below 100 °C or to room temperature. Rather, to prevent the thermal chuck 190 from overheating and to maintain a temperature of 170 °C, a high flow rate, typically 3 to 5 liters per minute of oil, is sufficient.

[0186] In the tester device 300, local heating is used. In contrast, a conventional burn-in tester has a burn-in oven and a burn-in port on which an integrated microelectronic circuit package inserted into this burn-in oven is placed. Heat is converted from the air in the burn-in oven to the integrated microelectronic circuit package and the burn-in board. Thus, in a general heating configuration, the heated air surrounds the burn-in board on which the integrated microelectronic circuit package is placed. In the local heating configuration of the tester device of FIG. 10, the air surrounding the portable pack 108 is typically at a substantially room temperature of 21° C., and the local area of the portable pack 108 is heated (or cooled) by the thermal chuck 190.

[0187] Local heating has its own unique set of challenges. Referring again to FIGS. 3 and 4, the signal distribution board assembly 116 is not heated as high above room temperature as the backing member 118 of the contact 170, and the backing member 118 of the contact 170 is not heated as high above room temperature as the wafer substrate 82. The backing member 118 of the contact 170 is heated, for example, from 21° C. to 171° C., and the signal distribution board assembly 116 is simultaneously heated from 21° C. to 121° C. The coefficients of thermal expansion of the backing member 118 of the contact 170 and the signal distribution board assembly 116 are designed such that the backing member 118 of the contact 170 and the signal distribution board assembly 116 expand and contract at similar rates. In a given embodiment, the coefficient of thermal expansion (CTE) of the signal distribution board assembly 116 is 10 parts per million (ppm), and the CTE of the backing member 118 of the contact 170 is 4.5, while the CTE of the wafer substrate 82 is 3.2. In another embodiment, the CTE of the signal distribution board assembly 116 is 5 to 6, or may be lower than the CTE of the backing member 118 of the contact 170 under a different set of thermal conditions.

[0188] In a given embodiment, the CTE ratio between the CTE of the signal distribution board assembly 116 and the CTE of the backing member 118 of the contactor 170 is 2.22. The CTE ratio can be defined as follows. TIFF0007689999000001.tif1253

[0189] The signal distribution board 116 is heated from a low signal distribution board temperature to a high signal distribution board temperature, and the backing member 118 of the contactor 170 is heated from a low contactor temperature to a high contactor temperature and temperature ratio. The temperature increase ratio can be defined as follows. TIFF0007689999000002.tif12106

[0190] The multiplication of the CTE ratio and the temperature increase ratio is defined as follows. CTE ratio X temperature increase ratio = χ

[0191] Ideally, χ should be as close to 1 as possible. In a preferred embodiment, χ should be closer to 1 than the CTE ratio. The CTE ratio is typically between 0.2 and 5, more preferably between 0.9 and 1.1, and χ is preferably between 0.8 and 1.2.

[0192] Referring to FIG. 8 again. When the burn-in test of the integrated microelectronic circuit 90 is completed, the holding structure 185 is lifted, thereby disconnecting the land interface of the portable pack 108 from the interface assembly 189. Then, the portable pack 108 is removed from the holding structure 185 by sliding the portable pack 108 in a direction out of the plane of the paper.

[0193] Referring again to FIG. 6, a vacuum release passage 272 is formed through the wafer chuck component 12, and a vacuum release valve 274 is disposed within the vacuum release passage 272. The vacuum release passage 272 has first, second, and third portions 276, 278, and 280. The first and second portions 276 and 278 are each drilled from the lower surface 24 and upper surface 22 of the wafer chuck component 12, respectively. The second portion 336 is drilled from the outer surface 20 and connects the first and second portions 276 and 278 to each other. The first portion 276 has an air inlet opening 282, and the second portion 336 has an air outlet opening 284 within the pressure differential cavity 140.

[0194] The vacuum release valve is a shuttle valve, and a release valve opening 286 is formed in the lower surface 24 of the wafer chuck component 12 on the side of the vacuum release valve 274 opposite the air outlet opening 284 of the vacuum release passage 272. The air inlet opening 282 is normally maintained at ambient pressure. The low pressure within the pressure differential cavity 140 holds the ball valve component 288 of the vacuum release valve 274 in its seat 290. To open the portable pack 108, the pressure at the release valve opening 286 is lowered below the pressure within the pressure differential cavity 140. The pressure differential between the pressure differential cavity 140 and the release valve opening 286 causes the ball valve component 288 to move away from the seat 290. The air inlet opening 282 is then placed in communication with the air outlet opening 284, and air flows through the vacuum release passage 272 into the pressure differential cavity 140. The pressure differential cavity 140 returns to ambient pressure. Since the pressure differential cavity 140 is at the same pressure as the air outside the portable pack 108, the distribution board assembly 110 can be lifted from the wafer substrate 82 and the wafer chuck assembly 10. The wafer substrate 82 can then be removed from the wafer chuck assembly 10.

[0195] FIG. 11 shows where two of the substrates 214 shown in FIGS. 7 and 8 form a single interface, and also shows one of the electrical testers 302 of FIG. 10.

[0196] The electrical tester 302 includes a backplane 322, a configurable power board (CPB) 324, a pin electronic board (PEB) 326, a test electronic board (TEB) 328, a die power board (DPB) 330, and a plurality of power buses 333. The configurable power board 324 and the pin electronic board 326 are structurally connected to the die power board 330 through the backplane 322. Also, the configurable power board 324 and the pin electronic board 326 are electrically connected to each of the power buses 333. The test electronic board 328 is mounted on top of the pin electronic board 326 and is electrically connected thereto.

[0197] The electrical tester 302 is thermally and mechanically disconnected from the substrate 214. A plurality of flexible attachments (not shown) are used to connect the die power board 330 to the substrate 214. A plurality of connectors 332 are disposed on the substrate 214 and are connected through the conductors 218 to the contacts 216 of FIG. 7. Another set of connectors 334 are disposed on the die power board 330. Each flexible attachment has two connectors at both ends. One of the connectors of the flexible attachment is connected to one of the connectors 332, and the opposite connector of the flexible attachment is connected to one of the connectors 334.

[0198] Power, signals, and ground can be supplied to the integrated circuit 92 of FIG. 2 through the configurable power board 324, the pin and test electronic boards 326 and 328, and the connectors 335 in the backplane 322, the die power board 330, and the flexible attachments. Each of the boards 324, 326, 328, and 330 has each substrate and each circuit (one or more) on each substrate, through which power, ground, or signals can be supplied to or from the circuit 92.

[0199] As shown in FIG. 12, the configurable power board 324 includes four power circuits 340 (IBC 48V to 12V @ 500W). The power circuits 340 are connected in parallel with each other. Even if one of the power circuits 340 fails, power is still supplied by the remaining power circuits 340. Therefore, the four power circuits 340 are n + 1, where n is 3. Even if one of the power circuits 340 fails, power is still supplied by n power circuits 340.

[0200] The current sharing circuit connects the power circuits 340 to the power bus 341. The current sharing circuit detects when the power from one of the power circuits 340 decreases below zero. When a power loss in one of the n + 1 power circuits 340 is detected, the current sharing circuit switches off the connection from the failed one of the n + 1 power circuits 340 and removes the current from the failed one of the n + 1 power circuits 340. Then, the current is shared by the n power circuits 340 that did not fail.

[0201] FIG. 13A shows that each of the power circuits 340 is connected to each defect detection circuit 342. The defect detection circuits 342 together make up the current sharing circuit of FIG. 12. Each of the defect detection circuits 342 detects the power loss from each of the power circuits 340 and disconnects each power circuit 340 from the power bus 341. In the defect detection circuit 342, in order to connect the power circuit 340 to the power bus 341, the voltage in (VIN) must be more positive than the voltage out (VOUT). If VIN is not more positive than VOUT, the GATE is de-energized and a defect signal is given to the defect line (IBCFAULTIN). In FIG. 12, the defect signal is given to the power control circuit 344 connected to the control line (IBC_INHIBIT_N). The power control circuit 344 can be used to switch on or off the power supplied by the power circuit 340. All the power circuits 340 are under the control of the power control circuit 344.

[0202] Also, the power control circuit 344 is energized by the power supply circuit 340 through the power bus 341. The power control circuit 344 is programmed to control which of the power supply circuits 340 to switch on and which to switch off. One of the power supply circuits 340 is always on and constantly supplies power to the power control circuit 344. Therefore, power loss to the power control circuit 344 is avoided and there is no need for restart or reprogramming. Thus, the power control circuit 344 is used to switch between a test mode in which power is supplied by all four power supply circuits 340 and a power saving mode in which power is supplied by only one power supply circuit 340. The current sharing circuit detects that power is lost by all but one of the power supply circuits 340 and disconnects all power supply circuits 340 except one from the power bus 341.

[0203] The circuit shown in FIG. 13A supplies 12V power to the power bus 341. FIG. 12 shows the voltage master DACS and MUXES circuit 346 also shown in FIG. 13B. The circuit of FIG. 13B establishes four master voltage levels (from HIC_VMASTER0 to HIC_VMASTER4). The master voltage is adjusted by individual digital / analog converters (12BIT DACs). Thus, the circuit of FIG. 13B can provide four different voltages, each of which is one of five different levels switched by a multiplexer (DG408). The circuit of FIG. 13B is under the control of the power control circuit 344 of FIG. 12.

[0204] Referring back to FIG. 12, the voltage master DACS and MUXES circuit 346 is connected to high current slaves 348, high voltage slaves 350, and additional slaves 352. Each high current slave 348 is arranged in a "primary" group of six high current modules. Eight "primary" groups of high current slaves 348 are arranged in a "super" group of 48 high current modules. Four high voltage slaves 350 are arranged in a "primary" group of high voltage slaves 350, and four "primary" groups of high voltage slaves 350 are arranged in one "super" group of 16 high voltage modules. Four voltages provided by the voltage master DACS and MUXES circuit 346 are supplied to each "primary" group of high current slaves 348 and each "primary" group of high voltage slaves 350 via four separate lines.

[0205] FIG. 13C shows one of the "primary" groups of the high current slaves 348 of FIG. 12. Six current amplifiers 356 are provided. The voltage adjustment lines (VADJ) of the current amplifiers 356 are connected to a common line 358. Line 358 is connected to the four voltage lines (VMASTER) on the right side of the circuit of FIG. 13B via a switch 360, two amplifiers 362 and 364, and a voltage selector 366. The voltage selector 366 is used to select each of the four voltages applied to the current amplifiers 356.

[0206] FIG. 14 shows one of the current amplifiers 356 of FIG. 13C. The current amplifier 356 has a current amplification module 370, an amplifier 372, a switch 374, and first and second input lines 376 and 378 to the amplifier 372.

[0207] The current amplification module 370 has a voltage reference (V0ADJ) and is connected to a 12V power supply via the power bus 341 of FIG. 13A to supply current to the output (VOUT).

[0208] The voltage reference line (V0ADJ) is connected to the common line 358 of FIG. 13C via the amplifier 372 and the first input line 376. The current amplification module 370 drives the output (VOUT) to the same voltage as the voltage reference line (V0ADJ). When the switch 374 is in the first configuration and the second input line 378 is disconnected from the sense line (VSENSE), the voltage of the second input line 378 follows VOUT, thereby keeping VOUT locally locked to VADJ.

[0209] When the switch 374 is in the second configuration and the sense line (VSENSE) is connected to the second input line 378 of the amplifier 372, the reference (V0AJD) of the amplification module 370 follows the remote voltage of the sense line (VSENSE). The voltage of the output (VOUT) is under the control of the sense line (VSENSE). It should be understood that both the output (VOUT) and the input (VSENSE) are ultimately connected to the terminal 92 of the substrate 82 in FIG. 2.

[0210] Referring back to FIG. 13C, each of the current amplifiers 356 has an individual output (VOUT) and an individual sense line (VSENSE). An individual voltage can be sensed on each sense line, and when the current configuration circuits shown in FIGS. 13C and 14 are in the second configuration, the currents to each output line will be different.

[0211] In the second configuration, the switch 360 connects the common line 358 to the amplifier 362. In the first configuration, the switch 360 connects the common line 358 to the output of the amplifier 384. The amplifier 384 has first and second input lines 386 and 388. The first input line 386 is connected to the output from the amplifier 362. The second output line 388 is connected to the sense line (VSENSE0) of only one of the current amplifiers 356. Thus, the voltage of the common line 358 follows the voltage of the sense line (VSENSE0) when the current configuration circuits of FIGS. 13C and 14 are in the first configuration.

[0212] Referring again to FIG. 12, each “primary” group of the high-voltage slaves 350 includes a circuit that is the same as the current configuration circuit of FIG. 13C, except that each of the current amplifiers 356 is used as a current and voltage amplifier. Each of the current and voltage amplifiers has each circuit shown in FIG. 15. The voltage and current amplifiers of FIG. 15 are the same as the current amplifiers of FIG. 14, except that four voltage-dividing resistors R1, R2, R3, and R4 are provided, and the current amplification module 370 of FIG. 14 acts as a current and voltage amplification module. The sense line (HIV_VSENSE) is connected to the switch 374 through the resistor R1. Also, the sense line (HIV_VSENSE) is also connected to the resistors R1 and R2 to ground. Accordingly, the resistors R1 and R2 act as a voltage divider for the voltage of the sense line (HIV_VSENSE) to the switch 374.

[0213] Similarly, the switch 374 is connected to the voltage sense line (VSENSE) through the resistor R4, connected to the output (VOUT) of the voltage and current amplification module 370, and the same terminal of the switch 374 is also grounded through the resistor R3. The voltage and current amplification module 370 amplifies the voltage based on the voltage of the VTRIM line.

[0214] Accordingly, referring particularly to FIGS. 13 and 14, it will be apparent that the operator can switch between the first configuration and the second configuration. In the first configuration, for example, a current of 60 A can be provided and shared among the six slave module outputs. In the second configuration, approximately 10 A can be provided by each of the six different module outputs, and the currents can be floated independently of each other.

[0215] Although several embodiments have been illustrated and described, they are merely illustrative and do not limit the present invention, and it should be understood that the present invention is not limited to the specific structures and configurations illustrated and described, since various modifications will be apparent to those skilled in the art.

Description of Symbols

[0216] 10: Wafer chuck assembly 12: Wafer chuck component 14: Pressure difference substrate cavity seal 16: Offset ring 18: Substrate absorption passage valve 36: Circular recess 40: Lower anchor portion 50: Substrate suction passage 52: First part 54: Second part 56: Third part 62: Air outlet opening 64, 66, 68: Circular groove 70: Slot 74: Seat portion 76: Ball valve component 80: Pressure relief opening 82: Wafer substrate 92: Metal terminal 108: Portable pack 114: Backing plate 116: Signal distribution board 118: Backing member 120: Opening 122: Edge 124: Substrate 128: Clamping ring 134: Metal seat portion 140: Pressure difference cavity 142: Groove 144: Vacuum passage 154: Inlet opening 168: Slot 170: Contact 172: Pin 174: Stand-off 176: Adhesive 178: First component 179: Second component 180: Fixing structure 181: Frame 182: Spring 185: Holding structure 187: Actuator 188: Contact part 189: Interface assembly 190: Thermal chuck 191: Metal wire 192: Mounting structure 193: Land 194: Cylinder 196: Piston 198: Connection fragment 200: Substrate 202: Piston 206: Signal and power board 208: First component 210: Second component 212: Spring 214: Substrate 216: Contact part 218: Metal wire 220: Mounting fragment 226: Thermal interface cavity seal 230: Adapter 240: Vacuum groove 242: Vacuum port 244: Vacuum port seal 268: First helix 270: Second helix 302: Electrical tester

Claims

1. An electrical tester that is mounted on at least one substrate having at least one integrated circuit and is connected to a plurality of terminals of the at least one substrate through contact portions, and a current is conducted between the electrical tester and the integrated circuit to test the integrated circuit. Further, the electrical tester includes a power supply circuit connected to the contact portion, and power is supplied through the power supply circuit connected to the contact portion. The power supply circuit includes a plurality of sense lines, and a current configuration circuit configured to perform current switching between a first configuration in which currents to individual channels follow a common reference and a second configuration in which different magnitude individual currents are supplied to individual channels and the individual currents follow each reference of each of the plurality of sense lines. A tester device.

2. The tester device according to claim 1, wherein the current configuration circuit includes a plurality of current amplifiers each having an output current following each reference when the current configuration circuit is in the first configuration.

3. The tester device according to claim 1, further comprising a current amplifier for amplifying the current to an individual channel.

4. The tester device according to claim 1, further comprising a signal electronic device for applying a signal to the integrated circuit.

5. A support structure for holding at least one substrate, and a plurality of contact portions matching the terminals for contacting the terminals. The electrical tester is connected to the terminals through the contact portions, and a current is conducted between the electrical tester and the integrated circuit to test the integrated circuit. The tester device according to claim 1.

6. In a method of testing at least one integrated circuit held by at least one substrate, placing a contact portion against a terminal of the substrate connected to the integrated circuit; conducting a current between the electrical tester and the integrated circuit through the terminal and the contact portion to test the integrated circuit; supplying power to the electrical tester through a power supply circuit connected to the contact portion. A step of switching between a first configuration in which the current to an individual channel follows a common reference, and a second configuration in which individual currents of different magnitudes are supplied to individual channels and the individual currents follow each reference of each of a plurality of sense lines, comprising, the power supply circuit having the plurality of sense lines and a current configuration circuit configurable to perform the switching step, method. **Claim 7**: The method according to claim 6, wherein the current configuration circuit includes a plurality of current amplifiers each having an output current following each reference when the current configuration circuit is in the first configuration. **Claim 8** The method according to claim 6, further comprising a step of amplifying the current to the individual channel. **Claim 9** The method according to claim 6, further comprising a step of applying a signal to the integrated circuit.

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