Wafer cutting method

Abstract

The invention provides a wafer cutting method, which comprises the following steps of: cutting the front surface of a wafer to remove all laser blocking materials of the wafer at a cutting channel position so as to obtain a cutting channel; releasing to obtain a suspension structure on the front surface of the wafer; and carrying out implicit cutting on the wafer at the cutting channel by using laser. According to the cutting method of the wafer, after front cutting, the back hidden cutting technology is adopted on the wafer, and the problem that laser hidden cutting cannot be achieved due to a laser blocking material at a cutting channel is solved; and front cutting is carried out before release, so that the suspension structure can be effectively prevented from being damaged.

Description

Technical Field

[0001] The present invention belongs to the field of chip manufacturing and cutting, and specifically relates to a wafer cutting method, which is suitable for cutting wafers with laser blocking materials and suspended structures that cannot be exposed to water and squeezed, especially MEMS structure wafers (such as MEMS sound chip wafers). Background Art

[0002] The materials and processes used in wafer manufacturing are numerous and complex. The structures inside the normal wafer cutting lanes are made of pure silicon to facilitate subsequent wafer cutting. The cutting methods are divided into blade cutting, laser surface cutting, laser grooving followed by knife cutting, and laser hidden cutting. Although there are many cutting methods, each has its own limitations.

[0003] Among them, blade cutting, laser surface cutting and laser slotting cutting all need to be washed with water, but wafers such as MEMS structure wafers have suspended structures on the surface that cannot be exposed to water or squeezed, especially MEMS sound chip wafers have suspended structures on the surface that cannot be exposed to water or squeezed, and cannot be touched or washed with water. In addition, laser hidden cutting has high requirements for the silicon material of the cutting path. The existing wafer compounds (i.e. laser blocking materials) will block the laser from penetrating, making it impossible to achieve laser hidden cutting.

[0004] Therefore, it is necessary to design a good cutting method to cut wafers with suspended structures that cannot be exposed to water and extrusion and compounds that block laser penetration. Summary of the invention

[0005] The object of the present invention is to provide a wafer cutting method, which solves the problem that wafers with laser blocking materials cannot be cut using hidden cutting by integrating chip manufacturing and cutting steps.

[0006] In order to achieve the above object, the present invention provides a wafer cutting method, comprising:

[0007] Cutting the front side of the wafer to remove all laser blocking materials at the cutting path position of the wafer to obtain the cutting path;

[0008] The suspended structure on the front side of the wafer is released;

[0009] Laser is used to perform hidden cutting of the wafer at the dicing path.

[0010] The wafer cutting method further comprises manufacturing a semi-finished chip on the wafer according to the required chip size, and the step of manufacturing the semi-finished chip is performed synchronously or asynchronously with the step of cutting the front side of the wafer.

[0011] Semi-finished chips are manufactured on wafers according to the required chip size, specifically including: grinding the back side of the wafer to thin the back side of the wafer to meet the thickness requirement, where the thickness requirement refers to the thickness requirement required for hidden cutting; and / or deep silicon etching is performed on a specified area on the back side of the wafer to obtain a semi-finished chip.

[0012] Semi-finished chips are manufactured on the wafer according to the required chip size, which also includes grinding the back of the wafer and deep silicon etching of the designated area on the back of the wafer; cutting the front of the wafer is performed before or after grinding the back of the wafer, and cutting the front of the wafer is performed before or after deep silicon etching.

[0013] The front side of the wafer is cut by blade cutting, laser cutting or etching.

[0014] When the front side of the wafer is cut by blade cutting or laser surface cutting, after the front side of the wafer is cut, the process also includes: cleaning the wafer.

[0015] When the front side of the wafer is cut by blade cutting or laser surface cutting, the hidden cutting of the wafer is the hidden cutting of the back side of the wafer; when the front side of the wafer is cut by etching, the hidden cutting of the wafer is the hidden cutting of the back side or the front side.

[0016] When the front side of the wafer is cut, the cutting thickness is equal to or greater than the thickness of the laser blocking material.

[0017] By completely removing the sacrificial layer on the front side of the wafer, a suspended structure is formed on the front side of the wafer.

[0018] After the wafer is cut at the cutting path by laser, the method further includes: splitting and / or expanding the wafer to obtain crystal grains.

[0019] The wafer cutting method of the present invention uses a back hidden cutting technology on the wafer after front cutting, thereby solving the problem that laser hidden cutting cannot be performed due to the laser blocking material at the cutting path; and the front cutting is performed before release, thereby effectively avoiding damage to the suspended structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The present invention is a flowchart of a wafer cutting method according to an embodiment of the present invention.

[0021] Figure 2-Figure 7 It is a schematic diagram of the structure of a wafer at different stages of the wafer cutting method of the present invention. DETAILED DESCRIPTION

[0022] The invention is further described below in conjunction with specific examples. It should be understood that the following examples are only used to illustrate the invention and are not used to limit the scope of the invention.

[0023] like Figure 1 A wafer cutting method according to an embodiment of the present invention is shown, which is used to cut a wafer with a laser blocking material and a suspension structure that cannot be exposed to water and cannot be squeezed, comprising:

[0024] Step S100: Figure 2 As shown, the back side 20 of the wafer is ground to thin the back side 20 of the wafer to meet the thickness requirement;

[0025] The thickness requirement refers to the thickness requirement required for hidden cutting. The material of the wafer back side 20 is low-resistance silicon.

[0026] Step S200: Figure 3 As shown, the front side 10 of the wafer is cut to remove all the laser blocking materials 11 of the wafer at the cutting path position to obtain the cutting path;

[0027] Therefore, by removing all the laser blocking materials 11 of the wafer at the cutting path position, subsequent hidden cutting is facilitated, while the problem of subsequent batch production difficulties caused by full cutting is avoided.

[0028] In this embodiment, the front side 10 of the wafer is cut (i.e., step S200) after the back side 20 of the wafer is ground (i.e., step S100). However, in other embodiments, the front side 10 of the wafer can also be cut before the back side 20 of the wafer is ground.

[0029] In step S200, the wafer front side 10 may be cut by blade cutting, laser cutting or etching. In this embodiment, the wafer front side 10 is cut by blade cutting.

[0030] In step S200, when cutting the wafer front side 10, the cutting thickness is equal to or greater than the thickness of the laser blocking material 11. Preferably, the cutting thickness is equal to the thickness of the laser blocking material 11, so that the cutting path is shallower, which is more conducive to avoiding subsequent processing debris.

[0031] Based on the fact that the wafer front side 10 is cut by blade cutting or laser cutting in step S200, after step S200, step S201 may be further included: Figure 4 As shown, the wafer is cleaned to remove contaminants 30 such as silicon scraps remaining after blade dicing (using a dicing blade 40) or laser surface dicing.

[0032] Step S300: Figure 5As shown, deep silicon etching is performed on a designated area on the back side 20 of the wafer to obtain a semi-finished chip.

[0033] That is, in this embodiment, the wafer front side 10 is cut (ie, step S200) before deep silicon etching (ie, step S300). However, in other embodiments, the wafer front side 10 is cut after deep silicon etching.

[0034] That is, the wafer cutting method of the present invention includes the step of making a semi-finished chip on the wafer according to the size of the required chip (including grinding the back side 20 of the wafer and deep silicon etching), and this step can be performed synchronously or asynchronously with the step of cutting the front side 10 of the wafer. Making a semi-finished chip on the wafer according to the size of the required chip specifically includes: grinding the back side 20 of the wafer to thin the back side 20 of the wafer to meet the thickness requirement; and / or deep silicon etching a specified area of ​​the back side 20 of the wafer to obtain a semi-finished chip.

[0035] In this embodiment, since the wafer is a MEMS structure wafer, the designated area on the back side 20 of the wafer refers to the pixel area.

[0036] Step S400: Figure 6 As shown, the suspended structure of the wafer front side 10 is released;

[0037] In this embodiment, the sacrificial layer on the front side of the wafer 10 is completely removed, so that the front side of the wafer 10 forms a suspended structure. The sacrificial layer is made of silicon oxide (SiO 2 ).

[0038] Therefore, the front cutting is performed before release, which can effectively avoid damage to the suspended structure.

[0039] Step S500: Figure 7 As shown, laser is used to perform hidden cutting of the wafer at the cutting path;

[0040] When the front side 10 of the wafer is cut by blade cutting or laser surface cutting, the surface of the cut path is rough after the front side 10 of the wafer is cut, and it is impossible to realize the front laser cutting of low-resistance silicon. Therefore, when the front side 10 of the wafer is cut by blade cutting or laser surface cutting, the hidden cutting of the wafer is the back side hidden cutting of the wafer; when the front side 10 of the wafer is cut by etching, the hidden cutting of the wafer is the back side hidden cutting or the front side hidden cutting of the wafer.

[0041] Since it uses an invisible cutting foundation, there is no need to clean the wafer.

[0042] Step S600: splitting and / or expanding the wafer to obtain crystal grains.

[0043] Thus, the wafer is divided into multiple separate dies, each of which is the desired chip.

[0044] The wafer cutting method of the present invention uses a back hidden cutting technology on the wafer after front cutting, which solves the problem that laser hidden cutting cannot be performed due to the laser blocking material 11 at the cutting path; and the front cutting is performed before release, which can effectively avoid damage to the suspended structure.

[0045] The above is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. The above embodiment of the present invention can also be modified in various ways. That is, all simple, equivalent changes and modifications made according to the claims and the description of the present invention fall within the scope of protection of the claims of the present invention. The contents not described in detail in the present invention are all conventional technical contents.

Claims

1. A wafer cutting method, characterized in that: include: Cutting the front side of the wafer to remove all laser blocking materials at the cutting path position of the wafer to obtain the cutting path; The suspended structure on the front side of the wafer is released; Laser is used to perform hidden cutting of the wafer at the dicing path.

2. A wafer cutting method according to claim 1, characterized in that: The method also includes manufacturing a semi-finished chip on a wafer according to the required chip size, wherein the step of manufacturing the semi-finished chip is performed synchronously or asynchronously with the step of cutting the front side of the wafer.

3. A wafer cutting method according to claim 2, characterized in that: Semi-finished chips are manufactured on the wafer according to the required chip size, including: Grinding the back side of the wafer to thin the back side of the wafer to meet the thickness requirement, wherein the thickness requirement refers to the thickness requirement required for hidden cutting; and / or The designated area on the back of the wafer is deep silicon etched to obtain a semi-finished chip.

4. A wafer cutting method according to claim 3, characterized in that: A semi-finished chip is manufactured on the wafer according to the required chip size, and the back of the wafer is polished and a designated area on the back of the wafer is deep-etched; Cutting the front side of the wafer is performed before or after grinding the back side of the wafer, and cutting the front side of the wafer is performed before or after deep silicon etching.

5. The wafer cutting method according to claim 1, characterized in that: The front side of the wafer is cut by blade cutting, laser cutting or etching.

6. A wafer cutting method according to claim 5, characterized in that: When the front side of the wafer is cut by blade cutting or laser surface cutting, after the front side of the wafer is cut, the process also includes: cleaning the wafer.

7. The wafer cutting method according to claim 5, characterized in that: When the front side of the wafer is cut by blade cutting or laser surface cutting, the hidden cutting of the wafer is the hidden cutting of the back side of the wafer; when the front side of the wafer is cut by etching, the hidden cutting of the wafer is the hidden cutting of the back side or the front side.

8. The wafer cutting method according to claim 1, characterized in that: When the front side of the wafer is cut, the cutting thickness is equal to or greater than the thickness of the laser blocking material.

9. The wafer cutting method according to claim 1, characterized in that: By completely removing the sacrificial layer on the front side of the wafer, a suspended structure is formed on the front side of the wafer.

10. The wafer cutting method according to claim 1, characterized in that: After the wafer is cut at the cutting path by laser, the method further includes: splitting and / or expanding the wafer to obtain crystal grains.

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