Wafer cutting method
Through the combined use of laser beam and bevel knife, combined with the Z-axis compensation mechanism, the wafer cut width is accurately controlled, which solves the problems of stress concentration and cutting channel width reduction in the prior art, and improves the efficiency and accuracy of wafer cutting.
Patent Information
- Application Number
- CN202311432671.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-10-26
- Filing Date
- 2023-10-31
- Publication Date
- 2025-04-29
AI Technical Summary
When existing wafer cutting methods use diamond cutting knives, it is easy to cause stress concentration and back fragmentation problems, especially on low dielectric constant wafers, and the cutting path width of the bevel knife is limited, making it difficult to adapt to the reduction of the cutting path width.
The first cutting is used to form a cutting path, and then a second cutting is performed in the inactive area with an oblique angle knife, and the thickness difference is compensated by raising the oblique angle knife, and finally a third cutting is performed on the bottom surface of the cutting path. The Z-axis compensation mechanism is activated using the cut mark width of the second cutting to accurately control the knife width.
By accurately controlling the width of the wafer marks, the width range of the cut path suitable for the beveled knife is expanded, which solves the problem of difficult cut width blocking caused by the reduction of the cutting path width, and overcomes the problem of cut width error.
Smart Images
Figure CN119897610A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a semiconductor cutting technology, and in particular to a wafer cutting method. Background Art
[0002] In modern life with the continuous advancement of science and technology, electronic products play an indispensable role in people's lives. As people's demand for electronic products increases, the demand for chip packages in electronic products also increases. Therefore, how to increase the yield and production efficiency of chip packages has become an urgent problem to be solved.
[0003] Currently, after a wafer has gone through a semiconductor integrated circuit manufacturing process, a wafer cutting step must be performed to cut the wafer into multiple rectangular chips, and then the chips are packaged. The existing wafer cutting method uses a diamond cutter to cut the wafer to separate the chips. However, cutting the wafer with a diamond cutter often causes stress to concentrate on the active surface of the wafer, resulting in back side chipping of the wafer. In particular, the dielectric layer of a low-k wafer is more fragile than the dielectric layer of an existing wafer, and is more difficult to withstand stress. In addition, the corners of existing low-k chips are prone to delamination from the sealing material during packaging.
[0004] Therefore, advanced packaging processes generally use bevel knives to solve the stress problem of chip packages. However, due to the problem of wafer cut width control of bevel knives, the width of the cutting path must be greater than 180 micrometers (μm). As wafer fabs continue to require the width of cutting paths to be reduced in advanced packaging processes, the selection of bevel knives is limited, resulting in the disadvantage of difficult cutting. Summary of the invention
[0005] To solve the above problems, the present invention provides a wafer cutting method, comprising: using a laser beam to perform a first cutting on the wafer to form a cutting path on the wafer; using a bevel knife of a wafer cutting machine to perform a second cutting in an inactive area of the wafer, wherein, before the second cutting, the bevel knife is first raised to a preset height to compensate for the thickness difference between the wafer in the inactive area and the cutting path; obtaining the wafer cut width of the second cutting through feedback from the wafer cutting machine; and using the bevel knife to perform a third cutting on the bottom surface of the cutting path, wherein, during the third cutting, the wafer cut width of the second cutting is used to activate the compensation mechanism of the wafer cutting machine to enable the bevel knife to cut to a predetermined wafer cut width.
[0006] The present invention firstly raises the cutting knife to make a cut on the invalid area of the wafer edge to eliminate the thickness difference between the pre-cutting position and the third cutting position, and then uses the pre-cutting knife mark width to start the Z-axis compensation mechanism of the cutting machine, so that the knife axis can accurately control the knife width when cutting the actual object, and through accurate wafer cut width control, the cutting path width range applicable to the bevel knife is increased to solve the problem that the wafer cut width is difficult to control due to the continuous reduction of the existing cutting path width, and overcome the wafer cut width error problem caused by various variations. BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Figure 1A and Figure 1B They are respectively a top view and a cross-sectional view of the wafer before cutting of the present invention.
[0008] Figure 2A and Figure 2B They are respectively a top view and a cross-sectional view of the first cutting of the wafer cutting method of the present invention.
[0009] Figure 3A and Figure 3B They are respectively a top view and a cross-sectional view of the second cutting of the wafer cutting method of the present invention.
[0010] Figure 4A and Figure 4B They are respectively a top view and a cross-sectional view of the third cutting of the wafer cutting method of the present invention.
[0011] Figure 5A and Figure 5B They are respectively a top view and a cross-sectional view of the fourth cutting of the wafer cutting method of the present invention.
[0012] Main component symbols
[0013] 20 Wafer
[0014] 21 Wafer body
[0015] 22 Passivation layer
[0016] 23 Cutting Road
[0017] 231 Bottom
[0018] 24,25 position
[0019] 241,251Wafer cut width
[0020] 26 No effect area
[0021] 30 Bearing
[0022] 31 Laser device
[0023] 32 Laser Beam
[0024] 33 Electronic components
[0025] 34 Bevel Knife
[0026] 35 right angle knife
[0027] H1,H2 height. DETAILED DESCRIPTION
[0028] The following describes the implementation of the present invention through specific embodiments. Those having ordinary knowledge in the technical field can easily understand other advantages and technical effects of the present invention from the contents disclosed in this specification.
[0029] Figure 1A and Figure 1B They are respectively a top view and a cross-sectional view of a wafer 20 before cutting according to an embodiment of the present invention. Figure 2A , Figure 3A , Figure 4A and Figure 5A is a top view of the wafer 20 when it is cut. Figure 2B , Figure 3B , Figure 4B and Figure 5B FIG. 2 is a cross-sectional view of the wafer 20 when being cut. The wafer cutting method of the present invention will be described below with reference to the above drawings.
[0030] First, if Figure 1A and Figure 1B As shown, a wafer 20 is provided. The wafer 20 is placed on a carrier 30, for example, the carrier 30 can be a dicing tape. A plurality of electronic components 33 are formed in the wafer 20. Each electronic component 33 can include an active component and / or a passive component, and the active component can be, for example, a semiconductor circuit or a semiconductor device, and the passive component can be, for example, a resistor, a capacitor, or an inductor. In addition, the wafer 20 includes a wafer body 21 and a passivation layer 22 formed on the wafer body 21.
[0031] like Figure 2A and Figure 2B As shown, the laser beam 32 emitted by the laser device 31 is used to perform the first cutting on the wafer 20 to form a cutting street 23. The cutting street 23 has a bottom surface 231. The first cutting can prevent the wafer 20 from breaking due to stress concentration when the wafer 20 is finally cut off.
[0032] like Figure 3A and Figure 3BAs shown, the wafer 20 is cut for the second time using the bevel knife 34 of the wafer cutting machine at the position 24 in the inactive area 26 at the edge of the wafer 20. Before the second cutting, the bevel knife 34 is first raised by a height of H1+H2 to compensate for the thickness difference between the position 24 in the inactive area 26 and the position 25 in the cutting path 23 of the wafer 20, wherein H1 is the thickness of the passivation layer 22, and H2 is the cutting depth of the laser beam 32, that is, the depth of the cutting path 23. For example, H1 can be 6 microns, and H2 can be 14 microns. After the second cutting, the wafer cut width 241 of the second cutting on the wafer 20 can be confirmed through the feedback of the wafer cutting machine. In detail, the wafer cut width 241 is the width of the cut formed by the bevel knife 34 at the position 24 on the surface of the passivation layer 22.
[0033] like Figure 4A and Figure 4B As shown, the wafer 20 is cut for the third time using the bevel knife 34 of the sawing machine at position 25 on the bottom surface 231 of the cutting path 23. This third cutting can also avoid the wafer 20 from breaking due to stress concentration when the wafer 20 is finally cut. During the third cutting, the wafer cut width 241 of the second cutting is used to activate the Z-axis compensation mechanism of the sawing machine, so that the bevel knife 34 can accurately cut to a predetermined wafer cut width 251, wherein the wafer cut width 251 is the width of the cut formed by the bevel knife 34 at position 25 on the bottom surface 231 of the cutting path 23. The aforementioned Z axis is parallel to Figure 1B , Figure 2B , Figure 3B , Figure 4B and Figure 5B The up-down direction in the Figure 1A , Figure 2A , Figure 3A , Figure 4A and Figure 5A The surface of the wafer 20 in the embodiment of the present invention.
[0034] In one embodiment, the wafer kerf width 251 of the third dicing is equal to the wafer kerf width 241 of the second dicing.
[0035] In one embodiment, the bevel angle of the blade of the bevel knife 34 is 63°.
[0036] like Figure 2B , Figure 3B and Figure 4B As shown, the first cut, the second cut, and the third cut only partially penetrate the thickness of the wafer 20. In other words, the first cut, the second cut, and the third cut do not cut through the wafer 20.
[0037] like Figure 5A and Figure 5BAs shown, the wafer 20 is cut for the fourth time at the position 25 of the third cutting using the right-angle knife 35 of the sawing machine to cut off the wafer 20 .
[0038] like Figure 2A , Figure 3A , Figure 4A and Figure 5A As shown, the first to fourth cutting steps can be performed on the wafer 20 and between the electronic components 33 to separate a plurality of electronic components 33 from the wafer 20 , and then a packaging process for each of the electronic components 33 can be performed.
[0039] Since the wafer kerf width control of the bevel knife limits the laser beam cutting path to a width greater than 180 microns, and the wafer kerf width control falls within 100±20 microns. If the bevel knife is to be used in a smaller 120-micron cutting path, the wafer kerf width control specification must be more rigorous. According to the simulation results, the wafer kerf width must be controlled at 90±10 microns to maintain the stress release effect. However, the bevel knife is greatly affected by the wafer thickness and the cutting path depth of the laser cutting (laser grooving).
[0040] Correspondingly, the present invention first raises the cutting knife to make a cut on the invalid area of the wafer edge to eliminate the thickness difference between the pre-cutting position and the third cutting position, and then uses the pre-cutting knife mark width to start the Z-axis compensation mechanism of the cutting machine, so that the knife axis can accurately control the knife width when cutting the actual object. Through precise wafer cut width control, the bevel knife can be used in cutting lanes that are only greater than 120 microns, and the cutting lane width range applicable to the bevel knife is increased, so as to solve the problem that the wafer cut width is difficult to control due to the continuous reduction of the existing cutting lane width, and overcome the wafer cut width error problem caused by various variations.
[0041] The above embodiments are merely illustrative of the principles and technical effects of the present invention, and are not intended to limit the present invention. Anyone with ordinary knowledge in the technical field may modify and change the above embodiments without violating the spirit and inventive concept of the present invention. Therefore, the scope of protection of the present invention shall be as set forth in the claims.
Claims
1. A wafer cutting method, comprising: Performing a first dicing on the wafer using a laser beam to form dicing streets on the wafer; Using a bevel knife of a wafer cutting machine to perform a second cut in the inactive area of the wafer, wherein before the second cut, the bevel knife is first raised to a preset height to compensate for a thickness difference between the wafer in the inactive area and the cutting street; Obtaining the wafer kerf width of the second cut through feedback from the wafer cutting machine; and The bevel knife is used to perform a third cut on the bottom surface of the cutting path, wherein during the third cut, the wafer cut width of the second cut is used to activate the compensation mechanism of the wafer cutter so that the bevel knife cuts to a predetermined wafer cut width.
2. The wafer cutting method according to claim 1, wherein: The wafer includes a wafer body and a passivation layer formed on the wafer body.
3. The wafer cutting method according to claim 1, wherein: The bevel angle of the blade of this bevel knife is 63°.
4. The wafer cutting method according to claim 1, wherein: The inactive area is located at the edge of the wafer.
5. The wafer cutting method according to claim 1, wherein: The preset height is equal to the thickness of the passivation layer of the wafer plus the depth of the scribe line.
6. The wafer cutting method according to claim 1, wherein: The wafer scribe width of the third cutting is equal to the wafer scribe width of the second cutting.
7. The wafer cutting method according to claim 1, wherein: The first cutting, the second cutting and the third cutting do not cut the wafer.
8. The wafer cutting method according to claim 1, wherein: The method further includes: The fourth cutting is performed at the position of the third cutting using the right-angle knife of the wafer cutting machine to cut off the wafer.
9. The wafer cutting method according to claim 8, wherein: The wafer has a plurality of electronic components formed therein, and the wafer cutting method further comprises: The first cutting, the second cutting, the third cutting and the fourth cutting are performed between the plurality of electronic components to separate the plurality of electronic components from the wafer.
10. The wafer cutting method according to claim 9, wherein: Each of the electronic components includes an active component and / or a passive component.