Wafer clamp of silicon carbide epitaxial wafer carrier concentration test board

Abstract

The utility model discloses a silicon carbide epitaxial wafer carrier concentration testboard wafer clamp, comprising a testboard, the testboard is provided with an outer ring, the outer ring is internally provided with an inner ring, both the outer ring and the inner ring are provided with positioning edges, and the edge of the outer ring is provided with a fixed flange. The structure is simple, operation steps are simplified, and test point position precision is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of semiconductors. Specifically, the utility model relates to a wafer clamp for measuring the carrier concentration of a silicon carbide epitaxial wafer. Background Art

[0002] As a representative of the third-generation semiconductor materials, silicon carbide (SiC) has the characteristics of large bandgap, high breakdown electric field, high thermal conductivity, high electron saturation velocity, strong radiation resistance, etc. In working scenarios such as high voltage and high temperature, it has obvious advantages such as easy heat dissipation, small volume, low energy consumption, and high power. The end products of silicon carbide materials are mainly used in new energy vehicles, photovoltaic power generation, smart grids, etc. Epitaxy refers to growing a layer of higher-quality single crystal material on the surface of a silicon carbide substrate.

[0003] At present, the silicon carbide industry obtains silicon carbide epitaxial wafers by growing silicon carbide epitaxial layers on substrates, and manufactures power devices such as Schottky diodes (SBDs) and metal-oxide-semiconductor field-effect transistors (MOSFETs) on the epitaxial layers. Therefore, the quality of epitaxy has a very great influence on the performance of devices and plays a very crucial role in the development of the industry. The quality of silicon carbide epitaxial wafers is generally monitored through tests of items such as carrier concentration, epitaxial film thickness, surface defects, and roughness.

[0004] At the present stage, silicon carbide epitaxy has entered the mass production stage, and production capacity is the main competitive factor, and improving production efficiency is the key. Regarding the detection section in epitaxial production, detection equipment for epitaxial wafer film thickness, defects, etc. can all achieve multi-piece full-automatic testing, thus greatly improving production efficiency.

[0005] However, currently, the mainstream mercury probe carrier concentration testing equipment on the market is basically single-piece testing. The test bench of the mercury probe carrier concentration testing equipment is a wafer stage with a flat belt and a four-six-inch vacuum adsorption guide rail. When testing and placing silicon carbide epitaxial wafers, manual operation is required, including two actions of placing the wafer and adjusting the position of the positioning edge. During this process, the manual adjustment of the positioning edge position requires a relatively high level of personnel operation skills and needs to be finely adjusted to the marked position, resulting in low production efficiency. At the same time, manual operation cannot avoid differences, resulting in deviations in the accuracy of the test points.

[0006] The utility model patent with the publication number CN211478547U was published on September 11, 2020, with the name of a wafer test fixture, which includes a chip test base. It is characterized in that: a positioning cylinder is fixedly installed at the top of the chip test base. There are substantially four positioning cylinders in total, and the four positioning cylinders are distributed in a rectangular array at the top of the chip test base. A piston rod is slidably connected inside the positioning cylinder, and a guide rod mounting plate is fixedly connected to the end of the piston rod. A test head guide slide bar is fixedly connected to one side of the guide rod mounting plate. A chip suction nozzle plate is placed on the top of the chip test base, and positioning grooves corresponding to the test head guide slide bars are provided around the chip suction nozzle plate. This wafer test fixture has a complex structure and is not very convenient to operate. Summary of the utility model

[0007] The purpose of the present utility model is to provide a wafer fixture for a carrier concentration test bench of a silicon carbide epitaxial wafer, which has a simple structure, simplifies the operation steps, and improves the test point accuracy, aiming at the deficiencies of the existing technology.

[0008] In order to achieve the above purpose, the technical solution adopted by the present utility model is as follows:

[0009] This wafer fixture for a carrier concentration test bench of a silicon carbide epitaxial wafer includes a test bench. An outer ring is provided on the test bench, and an inner ring is provided inside the outer ring. Positioning edges are provided on both the outer ring and the inner ring, and a fixed flange is provided at the edge of the outer ring.

[0010] An adsorption groove is provided on the test bench. The adsorption groove includes an annular adsorption groove and a radial adsorption groove, and the radial adsorption grooves are evenly distributed on the annular adsorption groove.

[0011] The inner diameter of the outer ring is equal to the outer diameter of the inner ring. The inner ring is snap-fitted on the outer ring, and the fixed flange is snap-fitted with the end of the test bench.

[0012] The outer ring and the inner ring have the same thickness.

[0013] A wafer picking column is provided in the middle of the test bench.

[0014] Grooves are provided at both ends of the positioning edge, and the grooves are semicircular.

[0015] The thickness of the outer ring is less than the length of the wafer picking column.

[0016] The technical effects of the present utility model are as follows: By using the wafer fixture of the carrier concentration test bench for silicon carbide epitaxial wafers of the present utility model, an outer ring and an inner ring structure are provided. During the process of placing the wafer for testing, the operation process of manually adjusting the position of the positioning edge is reduced, avoiding damage to the integrity of the wafer by directly adjusting the position of the wafer, enabling accurate and efficient wafer placement operation. Determining the positioning edge makes the placement position of the wafer more accurate and fixed, making the test point position more precise, reducing the test difference between each wafer, while also reducing the skill requirements for testers and saving labor costs; The adsorption grooves on the test bench are reasonably arranged, with high adsorption stability for the wafer; A fixed flange is provided, which can be directly installed on the test bench, simple and efficient, and can also accommodate the placement of wafers of various sizes, with convenient and quick switching. The overall structure is simple, and the material processing and manufacturing cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] This specification includes the following drawings, and the shown contents are respectively:

[0018] Figure 1 is the front view of the wafer fixture of the carrier concentration test bench for silicon carbide epitaxial wafers of the present utility model;

[0019] Figure 2 is the installation schematic diagram of the fixture of the present utility model;

[0020] Figure 3 is the front view of the test bench of the present utility model.

[0021] The markings in the figure are: 1, test bench; 2, outer ring; 3, inner ring; 4, fixed flange; 5, positioning edge; 6, groove; 7, adsorption groove; 8, annular adsorption groove; 9, radial adsorption groove; 10, wafer picking column. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The following is a further detailed description of the specific embodiments of the present utility model by referring to the drawings and describing the embodiments, aiming to help those skilled in the art have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention, and contribute to its implementation.

[0023] As Figures 1 to 3 shown, the wafer fixture of the carrier concentration test bench for silicon carbide epitaxial wafers includes a test bench 1, an outer ring 2 is provided on the test bench 1, an inner ring 3 is provided inside the outer ring 2, positioning edges 5 are provided on both the outer ring 2 and the inner ring 3, and a fixed flange 4 is provided at the edge of the outer ring 2.

[0024] This fixture is a jig installed on the test bench 1 for fixing the placement of the wafer. The fixture adopts an annular structure, which not only forms a hole position for placing the wafer, avoiding the sliding of the wafer and affecting the accuracy of the test points, but also realizes the function of placing wafers of different sizes. By aligning the positioning edge 5 of the fixture with the marking line, the process of manually adjusting the position of the positioning edge of the wafer and aligning it with the marking line can be omitted, eliminating the differences caused by non-standard manual operations, thus ensuring the accuracy of the test points. Placing the wafer on the hole position of the fixture can also ensure stability and avoid the risk of damaging the wafer during the process of adjusting the position of the wafer.

[0025] Among them, the fixed flange 4 has a diameter of 226 mm, a width of 3 mm, and a height of 1 mm, which is used to clamp the outer ring 2 on the test bench 1 to fix the entire fixture. The design of the positioning edge 5 can place the wafer on the test bench 1 more efficiently and accurately, reducing the manual operation of adjusting the position of the positioning edge during testing, thus improving production efficiency and being beneficial to improving the test efficiency and point accuracy of carrier concentration. The fixture can be composed of two parts: a 6-inch outer ring 2 and a 4-inch inner ring 3, which are respectively adapted to the sizes of 6-inch and 4-inch wafers, and will not affect the test point difference due to the excessive size and the sliding of the wafer. And both are made of anti-static Peek material, thus being applicable to a Class 100 clean workshop. The inner ring 3 can be directly taken and placed for switching, which is convenient and efficient, and also saves material costs. The diameter of the 6-inch wafer is 150 mm, and the positioning edge is 47.5 mm; the diameter of the 4-inch wafer is 100 mm, and the positioning edge is 32.5 mm. The inner diameter of the outer ring 2 is 150.5 mm, the length of the lower wafer positioning edge 5 is 47.7 mm, slightly larger than the size of the standard 6-inch wafer, and the inner ring 3 is partially embedded in the inner circle of the 6-inch outer ring 2, with an inner diameter of 100.5 mm, and the length of the lower wafer positioning edge 5 is 32.7 mm, slightly larger than the size of the standard 4-inch wafer.

[0026] As Figure 3 shown, an adsorption groove 7 is provided on the test bench 1. The adsorption groove 7 includes an annular adsorption groove 8 and a radial adsorption groove 9, and the radial adsorption grooves 9 are evenly distributed on the annular adsorption groove 8. The adsorption holes are connected to an adsorption device to achieve the adsorption effect of the adsorption groove 7. After the wafer is placed, the wafer to be tested is stably fixed on the test bench 1 through the uniform adsorption effect of the adsorption groove 7. The annular adsorption grooves 8 are distributed in concentric circles on the test bench 1, and the end of each annular adsorption groove 8 is connected to the adsorption hole in the middle of the test bench 1. The setting of the radial adsorption groove 9 expands the adsorption range and improves the uniformity of the adsorption force, providing a uniform adsorption and fixing effect for the wafer.

[0027] As Figure 1 shown, the inner diameter of the outer ring 2 is equal to the outer diameter of the inner ring 3, and the inner ring 3 is clamped on the outer ring 2, and the fixed flange 4 is clamped with the end of the test bench 1. The outer ring 2 is clamped on the test bench 1, and the inner ring 3 can be completely clamped on the outer ring 2 to improve stability.

[0028] like Figure 2 As shown, the outer ring 2 and the inner ring 3 have the same thickness. The uniform thickness of the two makes it easy to observe whether the surfaces of the two are flat after installation, so as to judge and adjust the two parts to form a snap-fit contact and improve the stability of the inner ring 3 on the outer ring 2.

[0029] like Figure 2 and Figure 3 As shown, a wafer removal column 10 is provided in the middle of the test table 1. The wafer removal column 10 on the test table 1 is connected to a lifting mechanism, which can eject the wafer from the test table 1 and the fixture after the test is completed, making it easier to remove the wafer and unload it. Setting multiple wafer removal columns 10 to operate simultaneously can avoid damage to the wafer caused by local force.

[0030] like Figure 1 As shown, semicircular grooves 6 are provided at both ends of the positioning edge 5. The aforementioned structure, with grooves cut into the ends of the positioning edge 5 on the outer surface and inner ring 3, provides space for placement of the wafer or the positioning edge of the inner ring 3, avoiding space interference and preventing placement. After the wafer is placed, the two positioning edges will not contact and generate force, thus preventing damage to the positioning edge of the wafer.

[0031] The thickness of the outer ring 2 is less than the length of the wafer removal column 10. The thickness of the clamp is 3mm, and the height of the wafer removal column 10 is 6mm, that is, the thickness of the clamp is less than the height of the wafer removal column 10, thereby ensuring that the movement of the wafer removal column 10 can completely lift the wafer and separate it from the clamp, that is, the clamp will not be stuck due to being too thick, avoiding affecting the wafer removal operation, and avoiding the wafer being stuck on the carrier due to being too thick during placement, affecting the placement efficiency.

[0032] Embodiment: Install the fixture on the test table 1, clamp the outer ring 2 on the test table 1 by fixing the flange 4, align the positioning edge 5 of the outer ring 2 with the marking line on the test table 1, then place the wafer in the middle of the outer ring 2, keep the positioning edge 5 aligned, start the adsorption device to adsorb and fix the wafer, that is, accurately place it at the test point, then remove the outer ring 2 to perform the test operation, after the test is completed, start the wafer removal column 10 to lift the wafer to remove the wafer for unloading; if you need to replace the test four-inch wafer, just install the inner ring 3 on the outer ring 2, and the operation method is the same as the above steps. After comparative testing, compared with the manual operation of the prior art, testing 25 wafers saves about 20 minutes.

[0033] The wafer fixture of the carrier concentration test bench for the silicon carbide epitaxial wafer is provided with the outer ring 2 and the inner ring 3 structures. During the test wafer loading process, it reduces the manual operation process of adjusting the position of the positioning edge, enables accurate and efficient wafer loading operation, determines the positioning edge to make the placement position of the wafer more accurate and fixed, makes the test point position more precise, reduces the test difference between each wafer, and at the same time reduces the skill requirements for the test personnel and saves labor costs; the adsorption grooves 7 on the test bench 1 are reasonably arranged, and the adsorption stability of the wafer is high; the fixed flanging 4 is provided, which can be directly installed on the test bench 1, simple and efficient, and can also be compatible with the placement of wafers of various sizes, and the switching is convenient and fast. The overall structure is simple, and the material processing and manufacturing cost is low.

[0034] The above has made an exemplary description of the present invention in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited by the above methods. As long as various non-substantive improvements are made by adopting the method concept and technical solution of the present invention; or without improvement, the above concept and technical solution of the present invention are directly applied to other occasions, they are all within the protection scope of the present invention.

Claims

1. A wafer fixture for a silicon carbide epitaxial wafer carrier concentration test station, characterized by: The invention comprises a test bench (1), wherein the test bench (1) is provided with an outer ring (2), an inner ring (3) is provided inside the outer ring (2), both the outer ring (2) and the inner ring (3) are provided with positioning edges (5), and the edge of the outer ring (2) is provided with a fixed flange (4); the inner diameter of the outer ring (2) is equal to the outer diameter of the inner ring (3), the inner ring (3) is clamped on the outer ring (2), and the fixed flange (4) is clamped with the end of the test bench (1).

2. The wafer fixture for a carrier concentration test bench for silicon carbide epitaxial wafers according to claim 1, characterized in that: The test bench (1) is provided with an adsorption groove (7), the adsorption groove (7) comprising an annular adsorption groove (8) and radial adsorption grooves (9), and the radial adsorption grooves (9) are evenly distributed on the annular adsorption groove (8).

3. The wafer fixture for testing carrier concentration of silicon carbide epitaxial wafers according to claim 2, characterized in that: The outer ring (2) and the inner ring (3) have the same thickness.

4. The wafer fixture for a carrier concentration test bench for silicon carbide epitaxial wafers according to claim 3, characterized in that: A film taking column (10) is provided in the middle of the test bench (1).

5. The wafer fixture for a carrier concentration test bench for silicon carbide epitaxial wafers according to any one of claims 1 to 4, characterized in that: Grooves (6) are provided at both ends of the positioning edge (5), and the grooves (6) are semicircular.

6. The wafer fixture for testing carrier concentration of silicon carbide epitaxial wafers according to claim 4, characterized in that: The thickness of the outer ring (2) is smaller than the length of the film-taking column (10).

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