Wafer segmentation method

Abstract

A wafer segmentation method comprises the following steps that a wafer with the surface covered with a patterned photoresist layer is provided, and the wafer comprises a cutting area exposed out of the patterned photoresist layer; a non-sticky sheet is placed on a carrying table, a wafer is placed on the non-sticky sheet, the non-sticky sheet and the wafer are fixed to the carrying table in a vacuum adsorption mode, and the patterned photoresist layer is located between the wafer and the non-sticky sheet; cutting the wafer along the cutting area from the surface, deviating from the patterned photoresist layer, of the wafer to obtain a plurality of discrete crystal grains; and separating the crystal grains from the non-adhesive sheet. The patterned photoresist layer on the surface of the crystal grain obtained by the wafer segmentation method is kept intact and is not damaged.

Description

Technical Field

[0001] The present application relates to the field of wafer segmentation, and in particular to a method for segmenting a wafer having a patterned photoresist layer. Background Art

[0002] In the chip manufacturing process, after forming an integrated circuit or a micro-electromechanical system on a wafer, the wafer needs to be cut into multiple discrete chips or crystal grains. However, for a wafer with a patterned photoresist formed on the surface, the patterned photoresist on the surface of the crystal grain is easily damaged when cutting to form multiple crystal grains. Summary of the invention

[0003] An object of the present application is to provide a wafer dividing method that can reduce the risk of damage to a patterned photoresist layer.

[0004] An embodiment of the present application provides a wafer segmentation method, comprising the following steps:

[0005] Providing a wafer having a surface covered with a patterned photoresist layer, the wafer comprising a cutting area exposed outside the patterned photoresist layer;

[0006] A non-adhesive sheet is placed on a carrier, a wafer is placed on the non-adhesive sheet, and the non-adhesive sheet and the wafer are fixed on the carrier by vacuum adsorption, wherein:

[0007] A patterned photoresist layer is located between the wafer and the non-adhesive sheet;

[0008] Cutting the wafer along a cutting region from a surface of the wafer facing away from the patterned photoresist layer to obtain a plurality of discrete crystal grains;

[0009] The die is separated from the non-sticky sheet.

[0010] According to some embodiments of the present application, the non-adhesive sheet is wafer release paper.

[0011] According to some embodiments of the present application, the non-adhesive sheet is an electrostatic adsorption film.

[0012] According to some embodiments of the present application, the wafer is cut by laser cutting, mechanical cutting or plasma etching.

[0013] According to some embodiments of the present application, before the step of cutting the wafer, the wafer dividing method further includes the following step: fixing a transparent film on the surface of the wafer facing away from the patterned photoresist layer.

[0014] According to some embodiments of the present application, before the step of cutting the wafer, the wafer dividing method further includes the following step: fixing the transparent film to a fixing ring.

[0015] According to some embodiments of the present application, after the transparent film is fixed to the fixing ring, the wafer is located in the fixing ring.

[0016] According to some embodiments of the present application, a wafer is cut by laser cutting to obtain a plurality of crystal grains, and the plurality of crystal grains are adhered to a transparent film.

[0017] According to some embodiments of the present application, after the step of cutting the wafer, the wafer cutting method further includes the following step: expanding the transparent film to which the plurality of crystal grains are adhered.

[0018] According to some embodiments of the present application, the fixing ring is made of stainless steel.

[0019] The wafer splitting method provided in the embodiment of the present application fixes the wafer on a carrier by a non-sticky sheet. The non-sticky sheet protects the patterned photoresist layer on the surface of the wafer from being damaged. After the wafer is cut, the patterned photoresist layer on the surface of the wafer will not be damaged by separating the non-sticky sheet. In this way, the patterned photoresist layer on the surface of the grain after separation from the non-sticky sheet remains intact and is not damaged. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0021] Figures 1 to 3 It is a cross-sectional view of a method for dividing a wafer according to an embodiment of the present application.

[0022] Figures 4 to 6 This is a cross-sectional view of a method for dividing a wafer according to another embodiment of the present application.

[0023] Main component symbols

[0024] Wafer 10

[0025] Photoresist layer 20

[0026] Front 10a

[0027] Back 10b

[0028] Cutting area 11

[0029] Non-adhesive sheet 30

[0030] Stage 40

[0031] Adsorption hole 41

[0032] Die 101

[0033] Transparent film 50

[0034] Fixed ring 60 DETAILED DESCRIPTION

[0035] The technical scheme in the embodiment of the present application is described clearly and in detail below. Obviously, the described embodiment is a part of the embodiment of the present application, rather than all the embodiments. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present application. The terms used in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application.

[0036] In addition, for simplicity and clarity, in the accompanying drawings, the size or thickness of various components, layers may be amplified. Throughout the entire text, the same numerical value refers to the same element. As used herein, the term "and / or", "and / or" includes any and all combinations of one or more related enumerated items. In addition, it should be understood that when element A is referred to as "connecting" element B, element A may be directly connected to element B, or there may be an intermediate element C and element A and element B may be indirectly connected to each other.

[0037] Further, the use of “may” when describing embodiments of the present application means “one or more embodiments of the present application”.

[0038] The technical terms used herein are for the purpose of describing specific embodiments and are not intended to limit the present application. As used herein, the singular form is intended to also include the plural form, unless the context clearly indicates otherwise. It should be further understood that the term "comprising", when used in this specification, refers to the presence of narrated features, values, steps, operations, elements and / or components, but does not exclude the presence or increase of one or more other features, values, steps, operations, elements, components and / or combinations thereof.

[0039] It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts herein, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, the first element, component, region, layer or part discussed below can be referred to as the second element, component, region, layer or part without departing from the teaching of the exemplary embodiment.

[0040] A first embodiment of the present application provides a wafer dividing method, which includes the following steps.

[0041] Step S1, see Figure 1 , a wafer 10 is provided, and a surface of the wafer 10 is covered with a patterned photoresist layer 20 .

[0042] The wafer 10 includes a front side 10a and a back side 10b which are arranged opposite to each other, and the front side 10a is provided with a device (not shown). The patterned photoresist layer 20 covers the area where the device is provided on the front side 10a. The area of ​​the front side 10a of the wafer 10 not covered by the patterned photoresist layer 20 is used as a cutting area 11. The cutting area 11 is exposed outside the patterned photoresist layer 20, and the wafer 10 can be subsequently divided along the cutting area 11 to form a plurality of discrete grains.

[0043] The wafer 10 is a carrier for forming a plurality of chips, and the material of the wafer 10 can be silicon (Si), germanium (Ge), silicon germanium (GeSi), silicon carbide (SiC), gallium arsenide or any other suitable semiconductor wafer material.

[0044] In this embodiment, the wafer 10 is used to form a gene sequencing chip. The material of the wafer 10 is silicon. Step S1 specifically includes the following steps: forming a silicon oxide layer on the front of the silicon wafer; forming a HMD S (Hexamethyldi siloxane) layer on the surface of the silicon oxide layer facing away from the silicon wafer; forming a photoresist layer on the surface of the HMD S layer facing away from the silicon oxide layer, and removing part of the photoresist layer and the corresponding part of the HMD S layer by etching process to form a patterned photoresist layer and a patterned HMD S layer, wherein the patterned photoresist layer covers the patterned HMD S layer, and part of the silicon oxide layer is exposed outside the patterned HMD S layer and the patterned photoresist layer; forming an amino layer on the surface of the exposed silicon oxide layer. Among them, the amino layer is located in the cutting area 11. DNA nanoballs (DNB) can be selectively adsorbed by the amino layer and repelled by the HMD S layer. The silicon oxide layer can be formed by conventional semiconductor process technology, such as low-temperature plasma chemical vapor deposition, plasma enhanced chemical vapor deposition, sputtering, atomic layer deposition, etc. The HMD S layer can be formed by chemical vapor deposition or spin coating. The amination layer can be formed by chemical vapor deposition.

[0045] Step S2, see Figure 2 , place the non-adhesive sheet 30 on the carrier 40, place the back side 10b of the wafer 10 upward on the non-adhesive sheet 30, and fix the non-adhesive sheet 30 and the wafer 10 on the carrier 40 by vacuum adsorption.

[0046] A plurality of through-holes 41 are provided in the carrier 40, and the adsorption holes 41 are used to communicate with a vacuum generator (not shown). When the vacuum generator evacuates the adsorption holes 41, the non-adhesive sheet 30 and the wafer 10 are adsorbed on the carrier 40, so that the relative positions of the wafer 10 and the carrier 40 are fixed. After the vacuum is broken, the wafer 10 can be directly removed to be separated from the carrier 40. Compared with other fixing methods such as gluing, fixing the wafer 10 on the carrier 40 by vacuum adsorption can reduce the risk of damage to the wafer 10 when separating the wafer 10 from the carrier 40.

[0047] After the back side 10b of the wafer 10 is placed on the non-adhesive sheet 30 with the back side 10b facing upward, the patterned photoresist layer 20 disposed on the front side 10a is located between the non-adhesive sheet 30 and the wafer 10 and contacts the non-adhesive sheet 30. The size of the non-adhesive sheet 30 is greater than or equal to the size of the wafer 10, and the non-adhesive sheet 30 covers the entire wafer 10 to isolate the patterned photoresist layer 20 and the carrier 40, thereby protecting the patterned photoresist layer 20 from damage and reducing the risk of damage to the patterned photoresist layer 20 caused by contact between the carrier 40 and the patterned photoresist layer 20.

[0048] The non-adhesive sheet 30 is not sticky. When the non-adhesive sheet 30 and the wafer 10 are separated, the patterned photoresist layer 20 will not be taken away by the non-adhesive sheet 30, thereby reducing the risk of damaging the patterned photoresist layer 20. In this embodiment, the non-adhesive sheet 30 is a wafer isolation paper, which is air permeable. When the vacuum generator evacuates the adsorption hole 41, the wafer isolation paper and the wafer 10 are simultaneously vacuum-adsorbed on the carrier 40, thereby fixing the relative positions of the wafer 10 and the carrier 40.

[0049] In other embodiments, the non-adhesive sheet 30 is an electrostatic adsorption film. The electrostatic adsorption film is electrostatically adsorbed on the wafer 10 to pre-fix the wafer 10; when the vacuum generator evacuates the adsorption hole 41, the electrostatic adsorption film is vacuum adsorbed on the carrier 40 to fix the relative position of the wafer 10 and the carrier 40.

[0050] Step S3, see Figure 3 , the back side 10 b of the wafer 10 is cut along the cutting area 11 to obtain a plurality of discrete crystal grains 101 .

[0051] In this embodiment, laser cutting is used to cut the wafer 10. Specifically, the laser device emits a laser beam to the cutting area 11 for cutting until it penetrates the wafer 10. In other embodiments, mechanical cutting, plasma etching, or a combination of mechanical cutting and laser cutting may be used to cut the wafer 10, which is not limited in this application.

[0052] Step S4, separating the die 101 from the non-adhesive sheet 30 .

[0053] Since the non-adhesive sheet 30 is not sticky, the die 101 and the non-adhesive sheet 30 can be easily separated, so the die 101 can be separated by directly taking it out from the non-adhesive sheet 30 , and the separation of the non-adhesive sheet 30 will not damage the patterned photoresist layer 20 of the die 101 .

[0054] A second embodiment of the present application provides a wafer dividing method, which includes the following steps.

[0055] Step S10, see Figure 4 , a transparent film 50 is attached to the back surface 10 b of the wafer 10 .

[0056] The transparent film 50 can be attached to the back side 10b of the wafer 10 by a film attaching machine, and is used to stick the split multiple grains 101 during the subsequent cutting process to prevent the split grains 101 from being scattered. In other embodiments, the transparent film 50 can also be directly attached to the back side 10b by an adhesive, or the transparent film 50 can also be a transparent tape. The size of the transparent film 50 is larger than the size of the wafer 10, and the transparent film 50 covers the entire back side 10b.

[0057] The transparent film 50 has high laser transparency, so that in the subsequent cutting process, the laser beam can penetrate into the wafer 10 with necessary energy.

[0058] Step S20, see Figure 4 , the transparent film 50 is fixed to the fixing ring 60 .

[0059] The transparent film 50 can be fixed to the fixing ring 60 by gluing or other methods. By fixing the transparent film 50 on the fixing ring 60, the risk of wrinkling of the transparent film 50, collision between the dies 101 after cutting, edge collapse of the dies 101, and reduction in the yield rate of the dies can be reduced.

[0060] The fixing ring 60 is an annular element, and the wafer 10 is located inside the fixing ring 60. The fixing ring 60 provides protection for the wafer 10, reducing the risk of scratching or rubbing the wafer 10. For example, in the process of moving the wafer 10, it is only necessary to clamp the fixing ring 60, reducing the risk of damaging the surface of the wafer 10. In some embodiments, the wafer 10 and the fixing ring 60 are cocentric, so that in the cutting process, the position of the wafer 10 is more accurate and the damage to the wafer 10 is less.

[0061] In some embodiments, the fixing ring 60 is made of stainless steel.

[0062] Step S30, see Figure 5, place the non-adhesive sheet 30 on the stage 40 , place the back side 10 b of the wafer 10 upward on the non-adhesive sheet 30 , and fix the non-adhesive sheet 30 and the wafer 10 on the stage 40 by adsorption.

[0063] In step S30, the fixing ring 60 may also be fixed to the stage 40, so as to further fix the wafer 10 on the stage 40 through the transparent film 50. In some embodiments, the fixing ring 60 is sandwiched between the transparent film 50 and the stage 40.

[0064] Step S40, see Figure 6 The wafer 10 is cut from the back side 10 b of the wafer 10 along the cutting area 11 by laser cutting to obtain a plurality of discrete crystal grains 101 . After cutting, the plurality of discrete crystal grains 101 adhere to the transparent film 50 .

[0065] Step S50 , separating the die 101 and the non-adhesive sheet 30 , and expanding the transparent film 50 to which the plurality of die 101 are attached.

[0066] The transparent film 50 is fixed on the stage of the film expander for film expansion to increase the gap between adjacent grains 101. After the wafer 10 is cut, the spacing between multiple grains 101 is very small. When the grain 101 is taken out, it is easy to collide with the adjacent grain 101 to cause defects such as edge collapse and scratches. In order to improve the yield rate of the grain 101, the present application uses a film expansion process to expand the spacing between the grains 101, which is convenient for taking out the grain 101, reducing the damage to the grain 101, and improving the yield rate of the grain 101.

[0067] The wafer splitting method provided in the embodiment of the present application fixes the wafer 10 on the carrier 40 by means of a non-adhesive sheet 30. The non-adhesive sheet 30 protects the patterned photoresist layer 20 on the surface of the wafer 10 from being damaged. After cutting the wafer 10, the patterned photoresist layer 20 on the surface of the wafer 10 will not be damaged by separating the non-adhesive sheet 30. In this way, the patterned photoresist layer 20 on the surface of the grain 101 after being separated from the non-adhesive sheet 30 remains intact and is not damaged.

[0068] The above disclosure is only a preferred implementation mode of the present application, and certainly cannot be used to limit the present application. Therefore, equivalent changes made according to the present application are still within the scope covered by the present application.

Claims

1. A wafer dividing method, characterized in that: The following steps are involved: Providing a wafer having a surface covered with a patterned photoresist layer, the wafer comprising a cutting area exposed outside the patterned photoresist layer; Placing a non-adhesive sheet on a stage, placing the wafer on the non-adhesive sheet, and fixing the non-adhesive sheet and the wafer on the stage by vacuum adsorption, wherein the patterned photoresist layer is located between the wafer and the non-adhesive sheet; Cutting the wafer along the cutting region from the surface of the wafer facing away from the patterned photoresist layer to obtain a plurality of discrete crystal grains; The die is separated from the non-adhesive sheet.

2. The wafer dividing method according to claim 1, wherein: The non-adhesive sheet material is wafer release paper.

3. The wafer dividing method according to claim 1, wherein: The non-adhesive sheet is an electrostatic adsorption film.

4. The wafer dividing method according to claim 1, wherein: The wafer is cut by laser cutting, mechanical cutting or plasma etching.

5. The wafer dividing method according to claim 1, wherein: Before the step of cutting the wafer, the wafer dividing method further comprises the following step: fixing a transparent film on the surface of the wafer away from the patterned photoresist layer.

6. The wafer dividing method according to claim 5, characterized in that: Before the step of cutting the wafer, the wafer dividing method further comprises the following step: fixing the transparent film to a fixing ring.

7. The wafer dividing method according to claim 6, wherein: After the transparent film is fixed to the fixing ring, the wafer is located in the fixing ring.

8. The wafer dividing method according to claim 5, characterized in that: The wafer is cut by laser cutting to obtain the plurality of crystal grains, and the plurality of crystal grains are adhered to the transparent film.

9. The wafer dividing method according to claim 8, characterized in that: After the step of cutting the wafer, the wafer cutting method further comprises the step of expanding the transparent film to which the plurality of dies are adhered.

10. The wafer dividing method according to claim 6, wherein: The material of the fixing ring is stainless steel.

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