Test slide glass disc device capable of improving wafer back contact and current conduction

Abstract

The invention belongs to but not limited to the technical field of semiconductors, and particularly relates to a test slide glass disc device capable of improving wafer back contact and current conduction, and a plurality of small vacuum suction holes are formed in the front surface of a slide glass disc. And vacuum grooves are distributed in the slide glass disc in a crossed manner and are connected with a plurality of small vacuum suction holes. And an interface connected with a vacuum circuit is arranged at the edge of the slide glass disc. When vacuum is started, the chip can be more firmly sucked on the slide glass disc through the vacuum interface on the side surface of the slide glass disc and the small vacuum suction holes on the front surface of the slide glass disc. Due to the fact that the number of the small vacuum suction holes is large, the consistency of the vacuum suction force of the chip on the chip carrying disc is better achieved. The slide glass disc is made of aluminum alloy, the surface of the slide glass disc is plated with gold (the thickness is about 2 microns), the electrical resistivity of the gold is 2.4 * 10 <-8 > omega.m, the contact resistance during current conduction can be completely ignored due to the ultralow electrical resistivity, and the current transmission capacity is improved.

Description

TECHNICAL FIELD

[0001] The present invention belongs to but not limited to the field of semiconductor technology, and particularly relates to a test wafer disk device capable of improving wafer backside contact and current conduction. BACKGROUND

[0002] During semiconductor wafer manufacturing, the wafer backside is formed with a common electrode layer by evaporating metal, serving as the common electrode of multiple devices. During semiconductor chip testing, the front side is connected with probes and the backside is placed on a test device wafer disk for conduction testing. Therefore, the vacuum suction force of the wafer disk and the current transmission capability of the wafer disk directly determine the test value.

[0003] Some test parameters, such as forward voltage VF, have high requirements for chip testing contact and current transmission capability. Therefore, the material of the wafer disk and the vacuum suction force of the test wafer disk will directly affect the deviation between the test value and the true value.

[0004] A conventional test device wafer disk is provided with an annular groove and a smaller vacuum suction hole. This design mainly solves the problem of ensuring that the chip can be fixed on the tray after the vacuum suction is turned on during actual production. In actual use, only the chip particles at the position of the vacuum suction hole have the best contact, and when testing the forward voltage VF parameter, only the test value in this area is close to the true value. The data in other areas will be scattered and the test value will increase.

[0005] The existing LED wafer testing system includes a wafer disk, a probe disk, a control system, and an integrating sphere acquisition system. The probe disk has a matrix arrangement of control circuits and a matrix arrangement of retractable probes. The control circuits are used to control the extension and retraction of the probes, and at the same time, the probes are arranged according to the test interval and input the set current or voltage. The control system is used to control the matrix arrangement of control circuits, set the test interval of LED wafers, and test the current or voltage.

[0006] Prior Art 1. MicroVac™ vacuum suction wafer disk technology The MicroVac™ technology provides uniform suction for thinned wafers through a large number of micro-holes (about 495, diameter 200 µm) distributed on the front side and a high-flow internal vacuum channel, and the surface is treated with gold plating.

[0007] Technical problem: Although this scheme improves the uniformity of suction and the metal conduction characteristics, it does not optimize the structure of the cross-grid arrangement between the vacuum holes and the channels, and it does not clearly explain how to improve the current conduction consistency of the backside contact through structural design.

[0008] Prior Art 2. Vacuum groove and plating structure of conventional vacuum Chuck Typical vacuum chuck usually uses aluminum or steel as base material, has concentric ring or vacuum hole layout, and selects nickel plating or gold plating as surface treatment method.

[0009] Technical problem: Although a general vacuum adsorption and conductive path is provided, the structure of "cross arrangement of vacuum grooves connected with multiple vacuum small suction holes" is lacking, a vacuum interface uniformly arranged at the edge of the device to connect a vacuum passage is also lacking, and the emphasis on extremely low resistance of the gold plating layer and the systematic conductive path design are not involved. Summary

[0010] In view of the problems existing in the prior art, the present application provides a test wafer disk device capable of improving wafer back contact and improving current conduction.

[0011] The present application is implemented as follows: a test wafer disk device capable of improving wafer back contact and improving current conduction, comprising a wafer disk, a vacuum small suction hole, a vacuum groove and a vacuum interface, the wafer disk is a disc structure, the front surface of the wafer disk is provided with multiple vacuum small suction holes penetrating into the interior of the disc body, the vacuum small suction holes are staggered distributed along the annular array and the radial array, the interior of the wafer disk is provided with a vacuum groove formed by the cross arrangement of a main channel and a branch channel, the vacuum groove is communicated with the multiple vacuum small suction holes, the edge of the wafer disk is provided with a vacuum interface, the vacuum interface is a metal connecting component, the interior of the vacuum interface has a hollow channel and is communicated with the main channel of the vacuum groove, so that under the action of an external vacuum source, the negative pressure is uniformly distributed to each vacuum small suction hole on the front surface of the wafer disk, and the uniform adsorption and fixation of the wafer back surface are realized.

[0012] Further, the vacuum small suction holes are staggered distributed along the annular array and the radial array on the front surface of the wafer disk.

[0013] Further, the main channel of the vacuum groove is arranged along the diameter direction of the disc, the branch channel is arranged along the direction perpendicular to the main channel, and the main channel and the branch channel cross to form a grid-shaped passage.

[0014] The present application also provides a wafer disk conductive structure for testing wafers, the wafer disk is made of aluminum alloy as a whole, and the surface is covered with a gold plating layer, the thickness of the gold plating layer is 2 μm, and the coverage range includes the front surface of the wafer disk, the inner wall of the vacuum small suction hole and the conductive contact surface at the connection of the vacuum interface.

[0015] Further, the gold plating layer is formed by an electroplating process, and the plating layer thickness tolerance does not exceed ±0.2 μm.

[0016] The present application also provides a fixing structure of a wafer disk and a device main body, characterized in that the wafer disk is fixed on the mounting plane of the device main body by four internal hexagonal screws equally distributed along the circumference, and the mounting plane is provided with a counterbore matched with the internal hexagonal screw.

[0017] Further, the bottom edge of the slide disc is provided with a plurality of internal hexagonal screw holes for fixed connection with the analog circuit to form a current conduction path.

[0018] The application also provides a slide disc vacuum interface connection structure, the vacuum interface is a metal threaded joint, the external thread part is fixedly connected with the threaded hole of the outer edge of the slide disc, the internal part of the vacuum interface is provided with a hollow channel and is communicated with the main channel of the vacuum groove, and the external end of the vacuum interface is connected with the external vacuum pipeline.

[0019] Further, the vacuum interface is made of stainless steel and is sealed and matched with the external vacuum pipeline through a sealing ring.

[0020] The application also provides a vacuum adsorption slide disc system for wafer testing, which comprises the slide disc device, a vacuum source connected with the vacuum interface of the slide disc, an external vacuum pipeline and an analog circuit.

[0021] 1. The application effectively reduces the contact resistance of the semiconductor wafer in the actual testing process through the modification of the slide disc, greatly improves the consistency and stability of the forward voltage drop parameter of the semiconductor wafer testing, and 2. The consistency and stability of the data are improved, the misjudgment of the machine testing is greatly reduced, the actual measurement loss is recovered, and the testing quality of the product is ensured.

[0022] The application can directly solve the numerical consistency and accuracy in the forward voltage VF testing through the modification of the structure of the slide disc and the optimization of the gold plating on the surface of the slide disc.

[0023] In the application, the core device is the vacuum small suction hole on the slide disc and the internally cross-arranged vacuum groove, and the two together constitute a stable and uniform vacuum adsorption system. Compared with the existing scheme which depends on a small number of adsorption holes, the application enables the negative pressure to form a full coverage on the back of the wafer through the annular and radial staggered distribution of the suction hole structure, thereby significantly improving the local suspension problem caused by the uneven distribution of the adsorption force of the traditional slide disc. The breakthrough in the structure directly brings the improvement of the contact consistency on the back of the wafer, and provides a reliable guarantee for high-precision electrical testing.

[0024] Secondly, the gold plating layer (thickness 2 microns) covering the surface of the slide disc endows a super-low resistivity conductive interface, and the plating layer not only covers the disc surface but also extends to the conductive contact surface of the inner wall of the vacuum small suction hole and the vacuum interface. Through this design, the contact resistance between the wafer and the disc body is effectively reduced, and the common current conduction bottleneck in the testing process is eliminated. Under the conditions of high current and high frequency testing, the application can realize stable signal transmission, significantly reduce the fluctuation of electrical parameters, and reflect the electrical performance improvement effect superior to the prior art.

[0025] Furthermore, the through-type design of the vacuum interface and the main channel of the vacuum tank in this invention allows the negative pressure of the vacuum source to be quickly transmitted to every small vacuum suction hole on the disk surface, avoiding the problems of vacuum delay and local insufficiency in traditional structures. This improvement not only shortens the response time required for wafer adsorption but also makes the loading and unloading process more efficient, meeting the dual requirements of speed and stability for batch testing in the semiconductor industry. Therefore, this invention achieves significant technological advancements in adsorption uniformity, conductivity, and testing efficiency. Attached Figure Description

[0026] Figure 1 This is a perspective view of the slide disk provided in an embodiment of the present invention; Figure 2 This is a cross-sectional view of the slide disk provided in an embodiment of the present invention; Figure 3 This is a top view of the slide disk provided in an embodiment of the present invention; Figure 4 This is a bottom view of the slide disk provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the tray assembly provided in an embodiment of the present invention; In the diagram: 1. Carrier tray; 2. Vacuum suction hole; 3. Socket head screw hole; 4. Vacuum interface; 5. Vacuum chamber. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0028] In existing semiconductor testing processes, the contact between the wafer carrier 1 and the back side of the wafer directly affects the stability of current conduction. Traditional wafer carriers, lacking a uniform vacuum adsorption structure, often result in minute gaps between localized areas of the wafer back side and the carrier surface, creating additional contact resistance. This non-uniformity causes signal distortion and data fluctuations during high-current or high-frequency electrical parameter testing, becoming a technical bottleneck restricting high-precision wafer-level electrical testing.

[0029] To address the aforementioned issues, this invention incorporates multiple small vacuum suction holes 2 on the front side of the wafer carrier disk 1 and arranges cross-shaped vacuum grooves 5 inside the disk body. This allows the negative pressure from the vacuum interface 4 to be evenly distributed across the entire disk surface through the main channel and branch channels. This gridded vacuum channel design ensures that the vacuum adsorption force is essentially consistent across all the small vacuum suction holes 2, thereby achieving stable and tight bonding of the wafer on the disk surface and preventing localized warping and microscopic suspended contact.

[0030] In terms of current conduction, the substrate 1 is made of aluminum alloy, and the surface is plated with gold to a thickness of 2 μm. The bulk resistivity of gold is only 2.4 × 10⁻⁶. -8 The impedance is Ω·m, which is much lower than that of common metal coatings, thus significantly reducing the additional impedance generated at the contact interface between the wafer and the substrate 1. Through this ultra-low resistance interface, the current can be evenly distributed between the wafer and the substrate 1, eliminating the current bottleneck caused by poor contact and effectively improving the stability and accuracy of electrical signal transmission during testing.

[0031] The vacuum suction orifices 2 are arranged in a combination of interlaced ring and radial arrays. This geometric distribution increases the coverage of adsorption points and, by dispersing the negative pressure center, avoids excessive stress on the wafer due to concentrated adsorption forces at single points. This design not only improves adsorption uniformity but also effectively reduces the risk of wafer cracking, warping, or localized damage during testing, thereby improving the reusability and reliability of the test samples.

[0032] The vacuum interface 4, located at the edge of the wafer tray 1, is connected to the main channel of the internal vacuum chamber 5, enabling the external vacuum pump to quickly transfer negative pressure to all the small vacuum suction holes 2 on the tray surface when turned on. This fast-response vacuum conduction mechanism solves the common problems of vacuum delay and local vacuum insufficiency in existing devices, ensuring operational efficiency during wafer placement and fixation. It is especially suitable for testing scenarios requiring high-frequency wafer loading and unloading, meeting the semiconductor industry's demand for batch testing.

[0033] This invention achieves a dual improvement in wafer backside contact consistency and current conduction efficiency by integrating a vacuum suction hole 2, a vacuum groove 5, and a vacuum interface 4 on the surface and inside of the wafer carrier disk 1, combined with the low impedance characteristics of surface gold plating. Its working principle relies on a vacuum adsorption structure to ensure uniform mechanical adhesion and a noble metal conductive interface to guarantee low current transmission impedance, thereby significantly improving the reliability and applicability of traditional test wafer carrier disks in precision electrical testing processes.

[0034] The present invention opens several small vacuum suction holes 2 on the front side of the slide disk 1 (such as... Figure 1 (As shown). Inside the slide tray 1, vacuum grooves 5 are arranged in a crisscross pattern, connected to multiple small vacuum suction holes 2 (as shown). Figure 2 As shown). On the edge of slide tray 1, there is an interface for connecting to the vacuum circuit (as shown). Figure 3When vacuum is activated, the chips can be more firmly adhered to the wafer tray 1 via the vacuum interface 4 on its side and the small vacuum suction holes 2 on its front. The numerous small vacuum suction holes 2 further improve the consistency of vacuum suction on the wafer tray 1. The wafer tray 1 is made of aluminum alloy, with its surface plated with gold (approximately 2µm thick). The resistivity of gold is 2.4 × 10⁻⁶. -8 With an ultra-low resistivity of Ω·m, the contact resistance during current conduction can be completely ignored, thus improving the current transmission capability.

[0035] like Figure 5 As shown, the substrate tray 1 of this invention is connected to the main body of the device via four hexagonal screws, and is connected to the analog circuit via hexagonal screws on the bottom edge of the substrate tray 1. This allows it to communicate normally with the machine tool during operation.

[0036] In summary, by modifying the structure of the substrate disk 1 and optimizing the gold plating on its surface, the consistency and accuracy of the positive voltage VF test can be directly solved.

[0037] like Figure 3 , Figure 4 As shown, the slide tray 1 is an integral circular structure with a plurality of small vacuum suction holes 2 evenly distributed on its front side. The small vacuum suction holes 2 are arranged in an alternating ring and radial array, covering the main working area of ​​the slide tray 1. The slide tray 1 has cross-shaped vacuum grooves 5 inside, the layout of which corresponds to the small vacuum suction holes 2, ensuring that each small suction hole is connected to the internal vacuum passage. A vacuum interface 4 is located on one side of the outer edge of the slide tray 1, the center of which is directly connected to the main channel of the vacuum groove 5.

[0038] The vacuum suction port 2 is connected to the internal vacuum tank 5 through a vertical drilled hole. The end of the vacuum tank 5 merges into the inlet cavity of the vacuum interface 4. The vacuum interface 4 is a metal threaded connector. The external threaded part is fixed to the threaded hole on the outer edge of the tray 1, and the internal hollow structure is connected to the vacuum tank 5. The outer end of the vacuum interface 4 is connected to the external vacuum pipeline, forming a continuous gas path from the external vacuum source to the vacuum suction port 2.

[0039] The tray 1 is fixed to the mounting surface of the device body by four hexagon socket screws distributed around its circumference. The screw holes are evenly distributed and equidistant along the circumference of the tray. The mounting surface has corresponding countersunk holes to accommodate the screw heads and ensure a tight fit between the tray and the device surface. The bottom edge of the tray 1 also has several hexagon socket screw holes 3 for fixing and mounting when connected to analog circuits.

[0040] The substrate tray 1 is made of aluminum alloy and machined as a single piece. The surface of the tray is covered with a 2μm thick gold plating layer, the thickness of which is controlled within tolerance through an electroplating process. The gold plating layer covers the front of the substrate tray 1, the walls of the vacuum suction holes 2, and the conductive contact surfaces at the vacuum interface 4 connection, ensuring a continuous current conduction path. The low resistivity of gold makes the contact resistance in the conductive path negligible, thus ensuring the overall conductivity uniformity of the substrate tray 1.

[0041] When the external vacuum source is activated, vacuum enters the main vacuum groove 5 inside the disk body through the vacuum interface 4, and then the negative pressure is evenly transmitted to each vacuum suction hole 2 by the cross-distributed branch vacuum grooves 5. When the chip is placed on the front of the carrier disk 1, the suction force generated by the vacuum suction holes 2 acts on the bottom surface of the chip through the evenly distributed aperture, thereby maintaining the chip's stable adhesion to the carrier disk 1.

[0042] During testing, the wafer carrier 1 is connected to the analog circuit via an internal hex screw at the bottom. The analog circuit provides the required test current to the wafer carrier 1. The current is rapidly conducted to the chip contact points via the gold-plated surface, achieving a low-impedance current transmission path. The structure and plating design of the wafer carrier 1 ensure extremely low current loss during transmission, which is beneficial to the stability and consistency of test data. Example

[0043] In this embodiment, the wafer carrier disk 1 adopts an aluminum alloy disc structure with a diameter of 200 mm. 240 vacuum suction holes 2 are machined on the front side, which are distributed alternately along two concentric annular arrays and six radial arrays, covering the entire wafer placement area. The wafer carrier disk 1 has vacuum grooves 5 that are 3 mm wide and 2 mm deep. The main channel is arranged along the diameter of the disk, and branch channels intersect perpendicularly to form a grid-like pathway, ensuring that all vacuum suction holes 2 are connected to the main channel.

[0044] The vacuum tank 5 is connected to an external vacuum source via a metal vacuum interface 4 located at the edge of the disk. The vacuum interface 4 is a brass threaded connector, with its external thread engaging with the threaded hole on the outer edge of the disk for fixation. The hollow channel in the interface is directly connected to the main vacuum tank 5. A sealing ring is used at the outer end of the interface to engage with the vacuum pipeline to prevent air leakage. Example

[0045] In this embodiment, the substrate tray 1 is made of 6061 aluminum alloy. After precision machining, it is polished and covered with a 2 µm thick gold plating layer. The gold plating layer is formed by electroplating, with a thickness tolerance controlled within ±0.2 µm. The coverage area includes all exposed metal parts of the front of the tray, the inner wall of the vacuum suction hole 2, and the connection surface of the vacuum interface 4.

[0046] The gold plating is pre-treated with nickel to enhance the adhesion between the plating and the substrate. Due to the low resistivity of gold, the continuous coverage of the plating ensures a stable impedance path for current conduction from the edge of the disk to the center, facilitating high-precision transmission of electrical signals during wafer testing. Example

[0047] In this embodiment, the tray 1 is fixed to the mounting surface of the device body by four M6 hex socket screws. The screws are evenly distributed along the circumference of the outer edge of the tray, spaced at 90° intervals. The mounting surface of the device body is machined with countersunk holes to mate with the screws, ensuring that the screw heads do not protrude above the mounting surface, allowing the tray 1 to fit tightly against the mounting surface.

[0048] Six additional M4 hex socket screw holes are provided at the bottom edge of the disk for fixing it to the analog circuit board. These screw holes correspond to the conductive terminals of the circuit board, and after tightening, they form a stable mechanical connection and a low-impedance electrical connection path. Example

[0049] In this embodiment, the vacuum interface 4 is made of stainless steel with an external thread, the thread specification being M8×1.25. The external thread portion is fixed in place with the threaded hole on the edge of the disc. The interface has a hollow channel with a diameter of 4 mm inside, which is directly connected to the main channel of the vacuum tank 5 to ensure smooth airflow.

[0050] The interface has a slot at its outer end for installing a silicone sealing ring. The sealing ring fits tightly against the inner wall of the external vacuum hose to prevent vacuum leakage. The interface can be easily installed and removed by screwing, facilitating cleaning and reconnection of the tray 1 during maintenance or replacement. Example

[0051] The vacuum adsorption slide plate system of this embodiment includes the slide plate device described in Embodiments 1 to 4, a vacuum pump with a rated vacuum of −90 kPa, a high-temperature resistant silicone vacuum pipeline, and a set of analog circuit test modules. The vacuum pump is connected to the vacuum interface 4 of the slide plate through the vacuum pipeline to form a closed negative pressure system.

[0052] The analog circuit test module is fixed to the wafer tray by the internal hex screws on the bottom of the tray, forming electrical contact with the gold-plated surface. After the wafer is placed on the front of the tray, the vacuum system is activated, and the negative pressure generated by the small suction hole fixes the wafer. At the same time, the test current is transmitted to the wafer through the gold-plated surface, realizing simultaneous mechanical fixation and electrical testing.

[0053] In the description of this invention, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0054] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A test wafer carrier device that improves back-side contact and current conduction of a wafer, characterized in that, The wafer carrier includes a wafer tray, vacuum suction holes, a vacuum groove, and a vacuum interface. The wafer tray has a disc-shaped structure with multiple vacuum suction holes penetrating into the interior of the tray on its front side. These vacuum suction holes are distributed alternately in a ring array and a radial array. The interior of the wafer tray has a vacuum groove formed by a cross arrangement of main channels and branch channels. The vacuum groove communicates with the multiple vacuum suction holes. The edge of the wafer tray has a vacuum interface, which is a metal connecting component. The vacuum interface has a hollow channel inside and communicates with the main channel of the vacuum groove. Thus, under the action of an external vacuum source, the negative pressure is evenly distributed to each vacuum suction hole on the front side of the wafer tray, achieving uniform adsorption and fixation of the back side of the wafer.

2. The test slide disk device according to claim 1, characterized in that, The vacuum suction holes are distributed alternately along the annular and radial arrays on the front side of the slide disk.

3. The test slide disk device according to claim 1, characterized in that, The main channel of the vacuum tank is arranged along the diameter of the disk, and the branch channels are arranged in a direction perpendicular to the main channel. The main channel and the branch channels intersect to form a grid-like passage.

4. A conductive structure for a wafer carrier disk used for testing, characterized in that, The substrate tray is made of aluminum alloy and covered with a gold plating layer with a thickness of 2 μm. The gold plating layer covers the front of the substrate tray, the inner wall of the vacuum suction hole, and the conductive contact surface at the vacuum interface connection.

5. The conductive structure of the substrate disk according to claim 4, characterized in that, The gold plating layer is formed by an electroplating process, and the thickness tolerance of the plating layer does not exceed ±0.2 μm.

6. A fixing structure for a slide tray and a device body, characterized in that, The tray is fixed to the mounting surface of the device body by four hex socket screws that are equidistant from each other along the circumference. The mounting surface is provided with countersunk holes that mate with the hex socket screws.

7. The fixing structure between the slide tray and the device body according to claim 6, characterized in that, The bottom edge of the substrate tray has several hexagonal screw holes for fixing it to the analog circuit to form a current conduction path.

8. A vacuum interface connection structure for a wafer disk, characterized in that, The vacuum interface is a metal threaded connector. The external threaded part is fixed to the threaded hole on the outer edge of the tray. The vacuum interface has a hollow channel inside and is connected to the main channel of the vacuum tank. The outer end of the vacuum interface is connected to an external vacuum pipeline.

9. The vacuum interface connection structure for the wafer disk according to claim 8, characterized in that, The vacuum interface is made of stainless steel and is sealed to the external vacuum pipeline through a sealing ring.

10. A vacuum adsorption wafer carrier system for wafer testing, characterized in that, The device includes a substrate tray as described in any one of claims 1 to 9, and a vacuum source, an external vacuum pipeline, and an analog circuit connected thereto. The vacuum source is connected to the vacuum interface of the substrate tray, and the analog circuit is fixedly connected to the internal hexagon screws on the bottom edge of the substrate tray to form a current conduction path.

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