Separation method for preventing edge breakage of wafer

Abstract

The invention discloses a separation method for preventing edge breakage of a wafer, which comprises the following steps of: coating UV (ultraviolet) glue on the front surface of the wafer, manufacturing a mask in an exposure and development manner, adhering the back surface of the wafer to a cutting machine, cutting the wafer with the cutting depth smaller than the thickness of the wafer, and cutting the wafer with the cutting depth smaller than the thickness of the wafer. The method comprises the following steps: carrying out plasma etching on a wafer by adopting a mixture of CF4, CHF3 and O2 so as to separate the wafer for 60-80 minutes, and finally, irradiating the UV glue so as to harden the UV glue, thereby enabling the separated wafer to fall off. The wafer is protected by adopting the UV glue, so that the oscillation force borne by the wafer during cutting is absorbed and relieved by the UV glue, the occurrence of wafer edge breakage is reduced, in addition, the wafer is separated by combining ion etching, the damage to the wafer caused by excessive machining cutting is avoided, the occurrence of wafer edge breakage is reduced, and the production efficiency is improved. Therefore, the defective product rate is reduced.

Description

Technical Field

[0001] The invention relates to the field of semiconductor technology, and in particular to a separation method for preventing wafer edge collapse. Background Art

[0002] At present, semiconductor wafer cutting is generally achieved through mechanical processing. During the cutting process, the blade can easily cause chipping of the semiconductor cross section. The usual solution is to adjust the amplitude of the blade and optimize the blade's cutting shape and speed to reduce the frequency of chipping, but the effect is not good. Summary of the invention

[0003] In view of the deficiencies in the prior art, an embodiment of the present invention provides a separation method for preventing wafer edge collapse, comprising:

[0004] Coat the front side of the wafer with UV glue and make a mask by exposure and development;

[0005] Bond the back side of the wafer to the sawing table;

[0006] Cutting the wafer, wherein the cutting depth of the wafer is less than the thickness of the wafer;

[0007] Plasma etching the wafer using a mixture of CF4, CHF3 and O2 to separate the wafer for 60-80 minutes;

[0008] The UV glue is irradiated.

[0009] As a preferred solution, the cutting of the wafer specifically includes:

[0010] Using a cutting blade to cut into the mask, and allowing the cutting blade to continue to penetrate into the wafer;

[0011] The cutting depth of the wafer is 0.45-0.50 mm, the rotation speed of the cutting spindle is 15000 rpm, the feed rate is 350-450 rpm, the blade width of the cutting blade is 0.3-0.55 mm, and the cutting water temperature is 25-30°C.

[0012] As a preferred solution, during the plasma etching process, the flow rates of CF4, CHF3 and O2 are 1000-1250sccm, the chamber temperature is 25-45 degrees Celsius, the chamber pressure is 50-70mtorr, the source power is 2500-3000W, and the bias power is 100-200W.

[0013] As a preferred solution, the etching depth of the wafer by plasma etching is less than or equal to 0.6 mm.

[0014] As a preferred solution, the thickness of the mask is greater than 1 mm.

[0015] As a preferred solution, the irradiating the UV glue specifically includes:

[0016] The UV glue is irradiated with ultraviolet light.

[0017] As a preferred solution, the coating of UV glue on the front side of the wafer specifically includes:

[0018] Applying a first UV adhesive layer on the front side of the wafer;

[0019] Laying a plurality of buffer fillers on the first UV adhesive layer;

[0020] A second UV adhesive layer is coated on the first UV adhesive layer on which a plurality of fillers are laid.

[0021] As a preferred solution, the buffer filler is a hollow filler or a soft solid filler.

[0022] As a preferred solution, a plurality of buffer fillers are laid on the first UV adhesive layer, specifically including:

[0023] A buffer filler with a particle size of 40-60 μm is laid on the first UV adhesive layer; wherein the ratio between the orthographic projection area of ​​the buffer filler on the first UV adhesive layer and the cross-sectional area of ​​the first UV adhesive layer is 40%-50%.

[0024] Compared with the prior art, the beneficial effect of the embodiment of the present invention is that: the embodiment of the present invention provides a separation method for preventing wafer edge collapse, first, UV glue is coated on the front of the wafer, and a mask is made by exposure and development, and then the back of the wafer is bonded to the cutting machine, and then the wafer is cut, wherein the cutting depth of the wafer is less than the thickness of the wafer, and then, the wafer is plasma etched by a mixture of CF4, CHF3 and O2 to separate the wafer for 60-80 minutes, and finally, the UV glue is irradiated to harden the UV glue, so that the separated wafer falls off. In the embodiment of the present invention, UV glue is used to protect the wafer, so that the shock force received by the wafer during cutting is absorbed and alleviated by the UV glue, reducing the occurrence of wafer edge collapse. In addition, the wafer is separated by combining ion etching to avoid excessive mechanical processing and cutting to damage the wafer, reducing the occurrence of wafer edge collapse, thereby reducing the defective rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a flow chart of a separation method for preventing wafer edge collapse in an embodiment of the present invention. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] See also Figure 1 As shown, it is a schematic flow chart of a separation method for preventing wafer edge collapse in an embodiment of the present invention.

[0028] The separation method for preventing wafer edge collapse according to an embodiment of the present invention comprises:

[0029] Step S101, coating UV glue on the front side of the wafer, and making a mask by exposure and development;

[0030] Step S102, bonding the back side of the wafer to a cutting machine table;

[0031] Step S103, cutting the wafer, wherein the cutting depth of the wafer is less than the thickness of the wafer;

[0032] Step S104, plasma etching the wafer using a mixture of CF4, CHF3 and O2 to separate the wafer, the time being 60-80 minutes;

[0033] Step S105, irradiating the UV glue.

[0034] In an embodiment of the present invention, first, UV glue is coated on the front of the wafer, and a mask is made by exposure and development, and then the back of the wafer is bonded to a cutting machine, and then the wafer is cut, wherein the cutting depth of the wafer is less than the thickness of the wafer, and then, a mixture of CF4, CHF3 and O2 is used to plasma etch the wafer to separate the wafer for 60-80 minutes, and finally, the UV glue is irradiated to harden the UV glue, so that the separated wafer falls off. In an embodiment of the present invention, UV glue is used to protect the wafer, so that the shock force received by the wafer during cutting is absorbed and alleviated by the UV glue, reducing the occurrence of wafer edge collapse. In addition, the wafer is separated by combining ion etching to avoid excessive mechanical processing and cutting from damaging the wafer, reducing the occurrence of wafer edge collapse, thereby reducing the defective rate.

[0035] In an optional implementation manner, the step S103 of “cutting the wafer” specifically includes:

[0036] Using a cutting blade to cut into the mask, and allowing the cutting blade to continue to penetrate into the wafer;

[0037] Among them, the cutting depth of the wafer is 0.45-0.50mm, for example, it can be 0.45mm, 0.46mm, 0.47mm, 0.48mm, 0.49mm, 0.50mm, etc. Of course, the cutting depth of the wafer can also be set to other values ​​according to actual use requirements, which will not be described in detail here; the speed of the cutting spindle is 15000rpm, and the feed rate is 350-450rpm, for example, it can be 350rpm, 360rpm, 370rpm, 380rpm, 390rpm, 400rpm, 410rpm, 420rpm rpm, 430rpm, 440rpm, 450rpm, etc., of course, the feed rate can also be set to other values ​​according to actual use requirements, which will not be elaborated here; the blade width of the cutting blade is 0.3-0.55mm, for example, it can be 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, 0.55mm, etc., and the cutting water temperature is 25-30℃, for example, it can be 25℃, 26℃, 27℃, 28℃, 29℃, 30℃, etc., of course, the cutting water temperature can also be set to other values ​​according to actual use requirements, which will not be elaborated here.

[0038] In a specific implementation, the wafer is pre-divided by deepening the cutting position of the tool, so that the chips on the wafer are not completely detached, and the remaining part of the cutting position (for example, 0.45-0.5mm) is still connected to the bottom of the wafer. At this time, since the UV glue on the front of the wafer forms a protective mask, the oscillating force of the blade is absorbed and alleviated by the UV glue during the cutting process. After measurement, the rate of wafer edge collapse is 0.2%, while the rate of wafer collapse in the prior art is generally 10%-15%. The embodiment of the present invention effectively reduces the rate of wafer collapse.

[0039] In an optional embodiment, during the plasma etching process, the flow rates of CF4, CHF3 and O2 are 1000-1250 sccm, the chamber temperature is 25-45 degrees Celsius, the chamber pressure is 50-70 mtorr, the source power is 2500-3000 W, and the bias power is 100-200 W. The etching depth of the wafer by plasma etching is less than or equal to 0.6 mm.

[0040] In the specific implementation, in step S103, a portion of the thickness of the wafer cutting position is cut by mechanical cutting, and the remaining portion of the cutting position after the tool cutting (the thickness of the remaining portion is, for example, less than or equal to 0.6 mm) can be cut by ion etching, so that the wafer is separated into multiple independent chips. Most importantly, the sidewalls can also be etched at the same time. Since most of the brittle pieces of the wafer are concentrated on the sidewalls, ion etching will cause these fragments to fall off from the semiconductor substrate, and at the same time, the traces of their falling off are corrected to make them disappear or become smooth. In addition, the direction of ion etching is mainly the depth direction of the wafer, so the etching depth of the sidewalls will naturally be less than 0.6 mm, and this depth will not affect the performance of the chip itself.

[0041] In an optional embodiment, the thickness of the mask is greater than 1 mm. In the specific implementation, UV glue is firstly pasted to the front side of the wafer, and a mask with a thickness of greater than 1 mm is made by exposure and development to provide protection and avoid confusion of the chips when the wafer is subsequently separated into multiple chips.

[0042] In an optional implementation, the step S105 of “irradiating the UV glue” specifically includes:

[0043] The UV glue is irradiated with ultraviolet light. In a specific implementation, the UV glue is irradiated with ultraviolet light to harden the UV glue and lose its stickiness, so that the chip falls off in an orderly manner.

[0044] In an optional implementation manner, coating the front side of the wafer with UV glue specifically includes:

[0045] Applying a first UV adhesive layer on the front side of the wafer;

[0046] Laying a plurality of buffer fillers on the first UV adhesive layer;

[0047] A second UV adhesive layer is coated on the first UV adhesive layer on which a plurality of fillers are laid.

[0048] Exemplarily, the buffer filler is a hollow filler or a soft solid filler, for example, it can be a hollow filler such as silica balls or a soft solid filler such as polyethylene (PP) and polypropylene (PE). Of course, the buffer filler can also be selected from other fillers according to actual use requirements, which will not be elaborated here.

[0049] In this embodiment, a plurality of buffer fillers are arranged between the first UV glue layer and the second UV glue layer to form a sandwich structure. When the wafer is cut or ion-etched, the oscillating force on the wafer can be buffered in the first UV glue layer, the second UV glue layer and the buffer filler. Among them, the buffer filler can further provide a space for extrusion deformation, so that the sandwich structure can withstand a greater extrusion force, so that the oscillating force on the wafer can be fully absorbed and alleviated. In addition, by setting the first UV glue layer to ensure that the sandwich structure can be firmly connected to the wafer, and by setting the second UV glue layer to ensure that the subsequent exposure and development methods can be smoothly used to make the mask, the buffer filler is avoided. The impact of the mask making. Therefore, the entire sandwich structure can improve the buffering capacity of the UV glue, thereby further protecting the wafer, so that the oscillating force on the wafer during cutting or ion etching is absorbed and alleviated by the UV glue and the buffer filler, further reducing the occurrence of wafer edge collapse.

[0050] In an optional implementation, laying a plurality of buffer fillers on the first UV adhesive layer specifically includes:

[0051] A buffer filler with a particle size of 40-60 μm is laid on the first UV adhesive layer; wherein the ratio between the orthographic projection area of ​​the buffer filler on the first UV adhesive layer and the cross-sectional area of ​​the first UV adhesive layer is 40%-50%.

[0052] In the specific implementation, the buffer filler is roughly evenly laid on the first UV adhesive layer. In this embodiment, a buffer filler with a particle size of 40-60 μm is used, and the laying area accounts for 40%-50% of the first UV adhesive layer to ensure that the sandwich structure composed of sufficient buffer fillers plays a better buffering role, thereby helping to reduce the occurrence of wafer edge collapse, and at the same time ensuring that sufficient UV glue firmly connects the sandwich structure to the wafer.

[0053] The separation method for preventing wafer edge collapse provided by the embodiment of the present invention can effectively reduce the defective rate of chips, and the defective rate of chips reaches 0.001-0.002%, and there are almost no defective chips.

[0054] Compared with the prior art, the beneficial effect of the embodiment of the present invention is that: the embodiment of the present invention provides a separation method for preventing wafer edge collapse, first, UV glue is coated on the front of the wafer, and a mask is made by exposure and development, and then the back of the wafer is bonded to the cutting machine, and then the wafer is cut, wherein the cutting depth of the wafer is less than the thickness of the wafer, and then, the wafer is plasma etched by a mixture of CF4, CHF3 and O2 to separate the wafer for 60-80 minutes, and finally, the UV glue is irradiated to harden the UV glue, so that the separated wafer falls off. In the embodiment of the present invention, UV glue is used to protect the wafer, so that the shock force received by the wafer during cutting is absorbed and alleviated by the UV glue, reducing the occurrence of wafer edge collapse. In addition, the wafer is separated by combining ion etching to avoid excessive mechanical processing and cutting to damage the wafer, reducing the occurrence of wafer edge collapse, thereby reducing the defective rate.

[0055] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A separation method for preventing wafer edge collapse, characterized in that: include: Coat the front side of the wafer with UV glue and make a mask by exposure and development; Bond the back side of the wafer to the cutting machine table; Cutting the wafer, wherein the cutting depth of the wafer is less than the thickness of the wafer; Plasma etching the wafer using a mixture of CF4, CHF3 and O2 to separate the wafer for 60-80 minutes; The UV glue is irradiated.

2. The separation method for preventing wafer edge collapse according to claim 1, characterized in that: The cutting of the wafer specifically includes: Using a cutting blade to cut into the mask, and allowing the cutting blade to continue to penetrate into the wafer; The cutting depth of the wafer is 0.45-0.50 mm, the rotation speed of the cutting spindle is 15000 rpm, the feed rate is 350-450 rpm, the blade width of the cutting blade is 0.3-0.55 mm, and the cutting water temperature is 25-30°C.

3. The separation method for preventing wafer edge collapse according to claim 1, characterized in that: During the plasma etching process, the flow rates of CF4, CHF3 and O2 are 1000-1250sccm, the chamber temperature is 25-45 degrees Celsius, the chamber pressure is 50-70mtorr, the source power is 2500-3000W, and the bias power is 100-200W.

4. The separation method for preventing wafer edge collapse according to claim 1, characterized in that: The etching depth of the wafer by plasma etching is less than or equal to 0.6 mm.

5. The separation method for preventing wafer edge collapse according to claim 1, characterized in that: The thickness of the mask is greater than 1 mm.

6. The separation method for preventing wafer edge collapse according to claim 1, characterized in that: The irradiating the UV glue specifically includes: The UV glue is irradiated with ultraviolet light.

7. The separation method for preventing wafer edge collapse according to claim 1, characterized in that: The step of coating the front side of the wafer with UV glue specifically includes: Applying a first UV adhesive layer on the front side of the wafer; Laying a plurality of buffer fillers on the first UV adhesive layer; A second UV adhesive layer is coated on the first UV adhesive layer on which a plurality of fillers are laid.

8. The separation method for preventing wafer edge collapse according to claim 7, characterized in that: The buffer filler is a hollow filler or a soft solid filler.

9. The separation method for preventing wafer edge collapse according to claim 7 or 8, characterized in that: The step of laying a plurality of buffer fillers on the first UV adhesive layer specifically includes: A buffer filler with a particle size of 40-60 μm is laid on the first UV adhesive layer; wherein the ratio between the orthographic projection area of ​​the buffer filler on the first UV adhesive layer and the cross-sectional area of ​​the first UV adhesive layer is 40%-50%.

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