A method and device for detecting wafer through-type defects

Abstract

The present invention provides a method and device for detecting through-type defects in a wafer, and specifically relates to the field of semiconductor defect detection. The detection method of the present invention comprises the following steps: providing a wafer containing device; placing a wafer to be detected coated with a first solution and a second solution in the wafer containing device; evacuating the wafer containing device containing the wafer to be detected and keeping it in a vacuum state for a period of time; taking out the wafer to be detected and observing the color change on its surface. The location of the through-type defect in the wafer is determined by the color change of the solution on both sides of the wafer. The method is simple and easy to operate, and can improve the detection efficiency of the wafer. The present invention also provides a device for detecting through-type defects in a wafer, which has a simple structure and is easy to operate.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor defect detection, and in particular to a method and device for detecting wafer through-type defects. Background Art

[0002] As a third-generation semiconductor material, silicon carbide (SiC) has great application potential in high temperature, high frequency, high power, optoelectronics and radiation resistance due to its wide bandgap, high critical avalanche breakdown electric field strength, high thermal conductivity, and high electron saturation drift velocity. It is the preferred material for manufacturing new devices such as high-performance power electronic devices, high-power solid microwave devices and solid sensors, as well as high-temperature resistant integrated circuits, and is widely used in petroleum, chemical, automotive, aviation, aerospace, communications, weapons and other industries.

[0003] SiC ingots and wafers contain a variety of defects. For example, defects in 4H-SiC crystals or substrates usually include screw dislocations (TSD), edge dislocations (TED), basal plane dislocations (BPD) and micropipe defects. Among them, basal plane dislocations are a common one-dimensional crystallization defect located in the basal plane of 4H-SiC crystals, which mainly affects the stability of bipolar devices, such as the occurrence of bipolar decay. TSD, TED and micropipes are through-type defects. TSD dislocations in the seed crystal will penetrate into the crystal, and TSD in the 4H-SiC substrate will also penetrate into the epitaxial layer, causing the reverse leakage current of the device to increase; TSD may also cause the epitaxial layer to form morphological defects such as triangle defects and carrot defects that are harmful to device performance; TED dislocation density is usually 10 4 cm -2 TED dislocations have the smallest impact on the performance of bipolar power devices and will not cause VF drift. TED dislocations in 4H-SiC epitaxial layers mainly come from the penetration of substrate TED dislocations into the epitaxial layer during the epitaxial growth process. Micropipes are a type of threading screw dislocation with a large Burgers vector, which penetrates from the substrate to the epitaxial layer and is the most harmful defect in 4H-SiC power devices. Micropipes can cause reverse bias failure of the device until it breaks down.

[0004] Through-type defects have serious adverse effects on the preparation of semiconductor devices in the later stage. Seed crystals are needed in the process of crystal growth. The presence of through-type defects in seed crystals will cause glue leakage during bonding, which will seriously affect crystal growth. There will also be glue leakage and leakage during the device preparation process. Therefore, the detection of through-type defects in wafers is particularly important. For large through-type defects, they can be identified by irradiation with a strong light. For small through-type defects, they are difficult to identify with the naked eye and need to be assisted by other equipment. The detection process is cumbersome and the operation is inconvenient. Summary of the invention

[0005] In view of the above shortcomings of the prior art, the present invention provides a method and device for detecting through-type defects in a wafer, so as to improve the problem of inconvenience in detecting through-type defects in a wafer.

[0006] To achieve the above object and other related objects, the present invention provides a method for detecting wafer through-type defects, comprising the following steps:

[0007] Providing a wafer receiving device;

[0008] A wafer to be inspected is placed in the wafer receiving chamber device, wherein one side of the wafer to be inspected is coated with a first solution, and the other side is coated with a second solution, and a color change reaction occurs when the first solution meets the second solution;

[0009] A wafer receiving device containing the wafer to be inspected is evacuated and maintained in a vacuum state for a period of time;

[0010] The wafer to be inspected is taken out and the color change on its surface is observed.

[0011] In an example of the present invention, the wafer containing device containing the wafer to be inspected is evacuated to a pressure below 5000 Pa and maintained in this state for 5 to 30 minutes.

[0012] In an example of the present invention, the first solution is an acid or alkaline solution, and the second solution is an acid-base indicator corresponding to the first solution.

[0013] In an example of the present invention, the first solution is a weak acid solution or a weak base solution, the weak acid solution is one or more of acetic acid, hypochlorous acid, chlorous acid, and sodium bisulfate solution, and the weak base solution is ammonia water or sodium carbonate solution.

[0014] In an example of the present invention, the acid-base indicator is one of methyl orange, phenolphthalein, bromocresol green and methyl red.

[0015] On the other hand, the present invention provides a detection device for a method for detecting through-type defects in chips, comprising a chip accommodating device and a vacuum pumping device, wherein the chip accommodating device comprises a first cover body and a second cover body, wherein the first cover body is provided with an exhaust port, the second cover body is correspondingly connected to the first cover body, and the second cover body and the first cover body are buckled together to form a chip accommodating cavity; the vacuum pumping device is connected to the exhaust port of the first cover body.

[0016] In an example of the detection device of the present invention, a sealing device is provided at the connection between the first cover body and the second cover body.

[0017] In an example of the detection device of the present invention, a first support rib is provided in the first cover body, a second support rib corresponding to the first support rib is provided on the second cover body, and the wafer to be detected is placed between the first support rib and the second support rib.

[0018] In an example of the detection device of the present invention, the wafer receiving cavities on both sides of the wafer to be detected are filled with porous materials.

[0019] In an example of the detection device of the present invention, the porous material is porous graphite.

[0020] The present invention provides a method for detecting through-type defects on a wafer. A wafer to be detected is placed in a vacuum state, and the color change of the solution on both sides of the wafer is used to determine the through-type defects on the wafer. When there is a through-type defect on the wafer to be detected, the solutions on both sides of the wafer will penetrate each other under the action of the pressure difference, and the solutions on both sides will change color after meeting; when there is no through-type defect on the wafer to be detected, the solutions on both sides of the wafer cannot meet, that is, the wafer will not change color. The present invention uses color change to identify whether there is a through-type defect on the wafer and the location of the through-type defect. The detection method is easy to operate and has good feasibility. The present invention also provides a detection device for wafer through-type defects. The device utilizes a vacuum pumping device to vacuum a wafer containing cavity formed by a first cover body and a second cover body. The operation is convenient, and the vacuum pumping device can detect the vacuum degree inside the wafer containing cavity in real time to prevent damage to the wafer to be detected due to excessive vacuum. A sealing device is utilized to seal the connection between the first cover body and the second cover body to improve the sealing of the wafer containing cavity and prevent air leakage during the observation process, thereby preventing the defects in the wafer from being accurately detected. A porous material is filled in the wafer containing cavity. The porous material can effectively prevent damage to the wafer due to the pressure difference during the vacuuming and inflation stages, thereby protecting the wafer to be detected. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 It is a flow chart of the method for detecting wafer through-type defects of the present invention;

[0023] Figure 2 It is a schematic structural diagram of a wafer through-type defect detection device in one embodiment of the present invention;

[0024] Figure 3is a schematic top view of a wafer through-type defect detection device according to an embodiment of the present invention;

[0025] Figure 4 FIG. 4 is a schematic structural diagram of a wafer through-type defect detection device in another embodiment of the present invention.

[0026] Component number description

[0027] 100, first cover; 101, air outlet; 102, first supporting rib; 200, second cover; 201, second supporting rib; 202, sealing ring; 203, sealing buckle; 204, porous graphite; 3, wafer to be tested. DETAILED DESCRIPTION

[0028] The following is an explanation of the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the features in the following embodiments and the embodiments can be combined with each other without conflict. It should also be understood that the terms used in the embodiments of the present invention are intended to describe specific embodiments, rather than to limit the scope of protection of the present invention. The test methods for which specific conditions are not specified in the following examples are usually carried out under conventional conditions or according to the conditions recommended by the manufacturers.

[0029] It should be noted that the terms such as "upper", "lower", "left", "right", "middle" and "one" etc. used in this specification are only for the convenience of description and are not intended to limit the scope of implementation of the present invention. Changes or adjustments to their relative relationships, without substantially changing the technical content, should also be regarded as the scope of implementation of the present invention.

[0030] See also Figures 1 to 4 The present invention provides a method and device for detecting through-type defects of a wafer, so as to improve the problem of inconvenience in detecting through-type defects in the prior art.

[0031] See also Figure 1 and Figure 2 The present invention provides a method for detecting wafer through-type defects, comprising the following steps:

[0032] S1. Provide a wafer receiving device;

[0033] S2, placing a wafer 3 to be inspected in a wafer containing device, wherein one side of the wafer 3 to be inspected is coated with a first solution, and the other side is coated with a second solution, and a color change reaction occurs when the first solution meets the second solution;

[0034] S3, evacuating the wafer receiving device containing the wafer to be tested and keeping it in a vacuum state for a period of time;

[0035] S4, take out the wafer 3 to be tested, and observe the color change on its surface.

[0036] See also Figure 2 The present invention also provides a detection device for a detection method of wafer through-type defects, the device includes a wafer accommodating device and a vacuum device connected thereto (not shown in the figure), wherein the wafer accommodating device includes a first cover 100 and a second cover 200, the first cover 100 is provided with a vacuum port 101 to be connected to the vacuum device, the second cover 200 is correspondingly connected to the first cover 100, and the two are buckled to form a accommodating cavity for installing the wafer. The vacuum device is connected to the vacuum port 101, and the vacuum device can be, for example, a vacuum pump, which is connected to the vacuum port 101 through a vacuum pipeline.

[0037] See also Figure 2 and Figure 3 In one example, the first cover 100 is provided with a first support rib 101, and the second cover 200 is provided with a second support rib 201. During detection, the wafer 3 to be detected is placed between the first support rib 101 and the second support rib 201. In order to prevent air leakage at the connection between the first cover 100 and the second cover 200, the first cover 100 and the second cover 200 are connected in a sealed manner, and the sealing manner may be, for example, soft packing sealing, dry gas sealing, labyrinth sealing (smooth labyrinth sealing, zigzag labyrinth sealing, stepped labyrinth sealing, honeycomb sealing), spiral sealing, sealing ring sealing, etc. Preferably, a sealing ring 202 is used for sealing, that is, a sealing ring 202 is provided at the connection between the first cover 100 and the second cover 200.

[0038] See also Figure 2 and Figure 3 In one example, sealing buckles 203 are provided on both sides of the second cover body 202, and locking holes corresponding to the sealing buckles 203 are provided on the first cover body 100. The first cover body 100 and the second cover body 200 are locked by the cooperation of the sealing buckles 203 and the locking holes.

[0039] See also Figure 3 and Figure 4In one embodiment, the first cover body 100 and the second cover body 200 are cylindrical shell structures, and grooves are correspondingly arranged inside them. After the two are buckled, the grooves arranged opposite to each other form a wafer accommodating chamber. Preferably, the grooves of the first cover body 100 and the second cover body 200 are filled with porous materials, such as porous graphite 204, porous ceramics, etc. The porous material can serve as both a support and an adsorbent. When the porous material serves as a support, it can carry the wafer, and the wafer can be clamped by the porous materials on both sides. The porous material can effectively prevent the pressure difference from damaging the wafer during the vacuum and inflation stages, and protect the wafer 3 to be detected. When the porous material serves as an adsorbent, the first solution and the second solution can be added to the porous material, and the adsorption properties of the porous material can be used to allow the first solution and the second solution to enter the wafer to be detected.

[0040] See also Figure 1 and Figure 2 When detecting through-type defects of a wafer, the detection device provided by the present invention is used. The wafer containing device in step S1 is a wafer containing device composed of a first cover body 100 and a second cover body 200 in the detection device. The internal structure thereof is as described above and will not be described again here.

[0041] See also Figure 1 and Figure 2 In step S2, the first solution and the second solution are respectively coated on both sides of the wafer 3 to be detected. They can be directly coated on both sides of the wafer 3 to be detected, or coated on the inner walls of the first cover 100 and the second cover 200, and the first solution and the second solution are separated by the wafer 3 to be detected. A color change reaction will occur when the first solution and the second solution meet. For example, the first solution is an acid or alkaline solution, and the second solution is an acid-base indicator. Preferably, the first solution is a weak acid solution or a weak alkaline solution. The weak acid solution can be one or more of acetic acid, hypochlorous acid, chlorous acid, and sodium bisulfate solution, and the weak alkaline solution can be ammonia water or sodium carbonate solution; the second solution is one of methyl orange, phenolphthalein, bromocresol green and methyl red. When selecting the first solution and the second solution, the pH value of the first solution and the color change range of the acid-base indicator are used to make the color change reaction of the first solution and the second solution more obvious and easy to observe. Table 1 lists the common color change ranges of different acid-base indicators. In some embodiments, the first solution and the second solution can also be other solutions that can produce color development reactions.

[0042] Table 1: Color change range of different acid-base indicators

[0043]

[0044]

[0045] In order to prevent acidic or alkaline solutions from corroding the chip holding device, the inner side of the chip holding device is made of acid-resistant and alkali-resistant materials, such as polytetrafluoroethylene (PTFE), PA46 material, PA6T material, LCP material, peek material, and carbon fiber material. Preferably, one or more of polytetrafluoroethylene (PTFE), carbon fiber material, and peek material are selected.

[0046] See also Figure 1 and Figure 2 , step S3, after placing the wafer 3 to be tested in the wafer containing device, the wafer containing chamber needs to be evacuated to below 5000Pa and maintained in a vacuum state for 5 to 30 minutes, so as to provide sufficient time for the penetration of the first solution and the second solution. For example, the wafer containing chamber is evacuated by a vacuum pump to a vacuum degree of 100Pa, 500Pa, 1000Pa, 2000Pa, 3000Pa, etc., and maintained in a vacuum state for 5min, 10min, 20min, 30min, etc.

[0047] See also Figure 1 and Figure 2 , step S4, after the inspection is completed, slowly inflate the wafer containing device to atmospheric pressure, open the wafer containing device, observe the color change on the surface of the wafer 3 to be inspected, and determine whether there is a through-type defect in the wafer 3 to be inspected and the location of the defect based on the color change.

[0048] The present invention coats the first solution and the second solution that can generate color reaction on both sides of the wafer to be tested. Under vacuum environment, if there are through-type defects (TSD, microtubes, hexagonal voids) in the silicon carbide wafer, the solutions on both sides will penetrate under the pressure difference, and then change color. By observing whether there is color change and the location of color change, the defect position in the silicon carbide wafer can be determined. The method uses simple equipment, is easy to operate, and can save detection costs.

[0049] The present invention is further described below through several embodiments. The chemical reagents used in the following embodiments can be obtained through commercial means. The detection device used to detect wafer through-type defects is the detection device provided by the present invention, wherein the first cover body 100 and the second cover body 200 are both made of acid- and alkali-resistant polytetrafluoroethylene material.

[0050] Example 1

[0051] See also Figures 1 to 3 , the wafer receiving cavity of the detection device of this embodiment is not filled with porous materials.

[0052] The detection process is as follows: 0.7 mol / L acetic acid solution is configured as the first solution, and the pH value of the first solution is <4.4, and it is applied to one side of the wafer 3 to be detected; methyl orange is selected as the second solution, and it is applied to the other side of the wafer 3 to be detected to avoid contact between the solutions on the two sides; the processed wafer 3 to be detected is placed on the second support rib 201 of the second cover 200, and the first cover 100 is covered, and the wafer 3 to be detected is clamped and fixed by the first support rib 102 and the second support rib 201, and the sealing buckle 203 is buckled; the vacuum pump is connected to the exhaust port 101 of the first cover 100, and the wafer accommodating chamber is evacuated to 1000 Pa, and maintained at this vacuum for 20 minutes; then the wafer accommodating chamber is slowly inflated for 30 minutes to atmospheric pressure, the sealing buckle 203 is opened, the wafer 3 is taken out and the color change of the wafer surface is observed. If the color changes to orange or red, it indicates that there is a through-type defect in the wafer, and the position of the color change can also reflect the position where the defect exists.

[0053] Example 2

[0054] See also Figure 1 , Figure 3 and Figure 4 Compared with Example 1, the detection device for wafer through-type defects used in this embodiment adds porous graphite 204. The porous graphite 204 is filled in the grooves in the first cover body 100 and the second cover body 200, and can be used as a support to effectively prevent damage to the wafer caused by pressure difference during vacuuming or inflation, thereby protecting the wafer. The porous graphite 204 can also be used as an adsorbent. The first solution and the second solution are added dropwise to the porous graphite, and the adsorption property of the porous graphite 204 is used to adsorb the first solution and the second solution to the surface of the wafer to be detected.

[0055] The detection process is as follows: prepare 0.1 mol / L ammonia water as the first solution, apply it to one side of the wafer 3 to be detected, select phenolphthalein as the second solution, and apply it to the other side of the wafer 3 to be detected; place the processed wafer 3 to be detected between the first cover 100 and the second cover 200, fasten the sealing buckle 203, use a vacuum pump to evacuate the wafer accommodating chamber to 500 Pa, and keep it at this vacuum for 25 minutes; then inflate the wafer accommodating chamber to atmospheric pressure for 60 minutes, open the sealing buckle 203, take out the wafer and observe the color change on its surface; if red appears on the wafer, it indicates that there is a through-type defect in the wafer, and the position of the color change can also reflect the position of the defect.

[0056] Example 3

[0057] See also Figure 1 , Figure 3 and Figure 4 The wafer through-type defect detection device used in this embodiment is the same as that in Embodiment 2.

[0058] The detection process is as follows: prepare 0.3 mol / L sodium bisulfate solution as the first solution, and add it dropwise into the porous graphite 204 in the first cover body 100; select bromocresol green methyl red solution as the second solution, and add it dropwise into the porous graphite 204 in the second cover body 200; place the wafer 3 to be detected between the porous graphite 204 in the first cover body 100 and the second cover body 200, and use the wafer 3 to be detected to separate the first solution and the second solution; fasten the sealing buckle 203, use a vacuum pump to evacuate the wafer containing chamber to 600 Pa, and keep it at this vacuum for 15 minutes; inflate the wafer containing chamber to atmospheric pressure for 30 minutes, open the sealing buckle 203, take out the wafer and observe the color change on its surface. If the color of the wafer surface turns red, it indicates that there is a through-type defect in the wafer, and the position of the color change can also reflect the position where the defect exists.

[0059] Example 4

[0060] See also Figure 1 , Figure 3 and Figure 4 The wafer through-type defect detection device used in this embodiment is the same as that in Embodiment 2.

[0061] The detection process is as follows: a 2% (0.65 mol / L) hydrogen peroxide solution (H2O2) is prepared as the first solution, and it is dripped into the porous graphite 204 in the first cover body 100; a 5% (0.35 mol / L) potassium permanganate solution (KMnO4) is selected as the second solution, and it is dripped into the porous graphite 204 in the second cover body 200; the wafer 3 to be detected is placed between the porous graphite in the first cover body 100 and the second cover body 200, and the first solution and the second solution are separated by the wafer 3 to be detected; the sealing buckle 203 is fastened, and the wafer containing chamber is evacuated to 400 Pa by a vacuum pump, and maintained at this vacuum for 15 minutes; the wafer containing chamber is inflated to atmospheric pressure for 30 minutes, the sealing buckle 203 is opened, the wafer is taken out and the color change of its surface is observed. If the color of the wafer surface changes from purple to transparent, it indicates that there is a through-type defect in the wafer, and the position of the color change can also reflect the position of the defect.

[0062] In summary, the present invention provides a method for detecting through-type defects in a wafer. Different solutions are coated on both sides of the wafer to be detected and placed in a vacuum state. If there is a through-type defect in the wafer, the solutions on both sides will penetrate and meet and a color change will occur. The position of the defect in the wafer can be determined by observing the position of the color change. The detection method of the present invention is simple and easy to operate. The present invention also provides a detection device for the detection method. The device has a simple structure and is easy to operate, which improves the detection efficiency of the wafer and saves the detection cost. Therefore, the present invention effectively overcomes some practical problems in the prior art and has a high utilization value and use significance.

[0063] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for detecting wafer through-type defects, characterized in that: The following steps are involved: Providing a wafer receiving device; Placing a wafer to be inspected in the wafer containing device, wherein one side of the wafer to be inspected is coated with a first solution, and the other side is coated with a second solution, and a color change reaction occurs when the first solution meets the second solution; Evacuating a wafer receiving device containing the wafer to be inspected and maintaining the device in a vacuum state for a period of time; Taking out the wafer to be tested and observing the color change on its surface; The wafer receiving device containing the wafer to be tested is evacuated to a vacuum pressure below 5000 Pa and maintained in this state for 5 to 30 minutes; The chip accommodating device includes a first cover body and a second cover body, the first cover body is provided with an exhaust port, the second cover body is correspondingly connected to the first cover body, and the second cover body and the first cover body are buckled to form a chip accommodating cavity; the exhaust port is connected to a vacuum pumping device; the chip accommodating cavities on both sides of the chip to be tested are filled with porous material, and the porous material is porous graphite.

2. The detection method according to claim 1, characterized in that: The first solution is an acid or alkaline solution, and the second solution is an acid-base indicator corresponding to the first solution.

3. The detection method according to claim 2, characterized in that: The first solution is a weak acid solution or a weak base solution, the weak acid solution is one or more of acetic acid, hypochlorous acid, chlorous acid, and sodium bisulfate solution, and the weak base solution is ammonia water or sodium carbonate solution.

4. The detection method according to claim 2, characterized in that: The acid-base indicator is one of methyl orange, phenolphthalein, bromocresol green and methyl red.

5. A detection device for use in the method for detecting wafer through-type defects according to any one of claims 1 to 4, characterized in that: include: A wafer accommodating device comprises a first cover body and a second cover body, wherein the first cover body is provided with an air extraction port, the second cover body is correspondingly connected to the first cover body, and the second cover body and the first cover body are buckled to form a wafer accommodating cavity; and A vacuum pumping device connected to the air extraction port; The wafer accommodating cavities on both sides of the wafer to be inspected are filled with porous material, and the porous material is porous graphite.

6. The detection device according to claim 5, characterized in that: A sealing device is provided at the connection between the first cover body and the second cover body.

7. The detection device according to claim 5, characterized in that: A first supporting rib is disposed in the first cover body, a second supporting rib corresponding to the first supporting rib is disposed in the second cover body, and the wafer to be inspected is placed between the first supporting rib and the second supporting rib.

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