Wafer cutting method

Abstract

The invention discloses a wafer cutting method. The wafer cutting method comprises the steps that a wafer is placed on a scribing machine; the positions of the wafer and the cutter are calibrated, then the surface of the wafer is cut to form a first guide groove, and the depth of the first guide groove is smaller than the thickness of the wafer; the positions of the wafer and the cutter are calibrated, then the surface of the wafer is cut to form a second guide groove perpendicular to and intersecting with the first guide groove, and the depth of the second guide groove is smaller than the thickness of the wafer; the positions of the wafer and the cutter are calibrated, and then the wafer is continuously cut along one of the first guide groove and the second guide groove and penetrates through the wafer; and the positions of the wafer and the cutter are calibrated, and then cutting is continued along the other one of the first guide groove and the second guide groove and the wafer penetrates through the other one of the first guide groove and the second guide groove. According to the method, the guide groove is formed through cutting firstly, then cutting is continued along the guide groove, and compared with one-time cutting and penetrating of the wafer, the generated thermal expansion effect is smaller, so that the size of a notch generated by edge breakage can be effectively reduced, and the performance and the yield of a device are improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of wafer dicing, and particularly relates to a wafer cutting method. BACKGROUND

[0002] Infrared detectors play a crucial role in modern technology and are widely used in military, security, medical, industrial and other fields. With the continuous development of infrared detection technology, the performance requirements of detectors are increasingly improved. The dicing process is a crucial link in the manufacturing process of detectors, directly affecting the performance of detectors and the yield of final products. Dicing is the process of cutting large-size infrared detector wafers into individual chips. In this process, the relative position of the dicing tool and the wafer material must be highly precise to ensure the uniformity of the cutting and the integrity of the chips. Currently, the dicing process is prone to uneven cutting, which can damage the chips and affect the performance and yield of the devices. SUMMARY

[0003] The technical problem to be solved by the present application is that in the existing dicing process, uneven cutting can easily damage the chips. To solve this technical problem, a wafer cutting method for improving cutting uniformity is provided.

[0004] The technical solution provided by the present application is as follows: A wafer cutting method, comprising the steps of: S110, placing a wafer on a dicing machine; S120, calibrating the positions of the wafer and the tool, then cutting a first guide groove on the surface of the wafer, the depth of the first guide groove being less than the thickness of the wafer; S130, calibrating the positions of the wafer and the tool, then cutting a second guide groove perpendicular to and intersecting the first guide groove on the surface of the wafer, the depth of the second guide groove being less than the thickness of the wafer; S140, calibrating the positions of the wafer and the tool, then continuing to cut along one of the first guide groove and the second guide groove and penetrating the wafer; S150, calibrating the positions of the wafer and the tool, then continuing to cut along the other of the first guide groove and the second guide groove and penetrating the wafer.

[0005] The wafer cutting method is used to cut the guiding grooves (the first guiding groove and the second guiding groove) on the surface of the wafer first, and then cut along the guiding grooves and through the wafer, so as to complete the cutting of the wafer. Since the guiding grooves are cut first and then the wafer is cut along the guiding grooves, the heat expansion effect is smaller than that of cutting through the wafer at one time, so that the size of the edge collapse can be effectively reduced, and the performance and yield of the device are improved.

[0006] Further, the depth of the first guiding groove and the second guiding groove is 1 / 4-1 / 2 of the thickness of the wafer.

[0007] Further, the depth of the first guiding groove and the second guiding groove is the same.

[0008] Further, in step S140, the wafer is continuously cut along the first guiding groove and through the wafer.

[0009] Further, in step S120 and step S130, the spindle speed of the dicing machine is 30000-60000 rad / min, and the feed rate is 1-1.5 mm / s.

[0010] Further, in step S140 and step S150, the spindle speed of the dicing machine is 30000-60000 rad / min, and the feed rate is 0.5-1 mm / s.

[0011] Further, step S110 comprises: S111, pasting a UV film on the wafer ring; S112, bonding the UV film to the back surface of the wafer; S113, placing the wafer ring carrying the wafer in the dicing machine.

[0012] Further, it further comprises the steps of: S160, film expanding treatment of the UV film by a film expander; S170, gelatinizing treatment of the UV film by a gelatinizer, and separating the wafer from the UV film.

[0013] Further, step S110 comprises: S111, pasting a dicing film on the wafer ring, and the middle of the dicing film is bonded with a substrate sheet; S112, coating a wax layer on the substrate sheet; S113, bonding the back surface of the wafer to the substrate sheet coated with the wax layer; S114, placing the wafer ring carrying the wafer in the dicing machine.

[0014] Further comprising the step of: S160, melting the wax layer on the substrate sheet by a wax melting machine. BRIEF DESCRIPTION OF DRAWINGS

[0015] The accompanying drawings are included to provide a further understanding of the present application, and constitute a part of this specification that describes it, together with the embodiments of the present application, to explain the present application, and do not constitute a limitation of the present application.

[0016] Figure 1 A flowchart of a wafer cutting method according to an embodiment of the present application is shown in FIG. 1. Figure 2 A microstructure of a wafer back surface according to the application example 1 is shown in FIG. 2. Figure 3 A microstructure of a wafer back surface according to the application example 2 is shown in FIG. 3. Figure 4 A microstructure of a wafer back surface according to the comparative example is shown in FIG. 4. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0018] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0019] In order to facilitate the understanding of the technical solutions of the present application, the existing dicing process and defects are described as follows: the existing dicing process is usually to adhere the wafer to the dicing film for dicing, and the cutting tool cuts through the wafer at one time during the dicing process. During the cutting process, the cutting is not uniform, which leads to the material being easy to collapse and generate a large notch to damage the chip, affecting the performance and yield of the device.

[0020] Based on this, the application provides a wafer cutting method, which can improve the uniformity in the wafer cutting process, thereby reducing the notch size caused by the edge collapse, and improving the performance and yield of the device.

[0021] As shown in Figure 1 The application provides a wafer cutting method, which comprises the following steps: S110, placing the wafer on a dicer; S120, cutting a first guide groove on the surface of the wafer, the depth of the first guide groove being less than the thickness of the wafer; S130, cutting a second guide groove on the surface of the wafer, the second guide groove being perpendicular to and intersecting with the first guide groove, the depth of the second guide groove being less than the thickness of the wafer; S140, continuing to cut along one of the first guide groove and the second guide groove and penetrating the wafer; and S150, continuing to cut along the other one of the first guide groove and the second guide groove and penetrating the wafer. In steps S120-S150, the wafer and the cutter need to be calibrated before cutting the wafer each time.

[0022] The wafer cutting method has the advantages that the guide groove (the first guide groove and the second guide groove) is first cut on the surface of the wafer, the guide groove does not penetrate the wafer, and then the wafer is cut along the guide groove and penetrated. Since the cutter and the wafer are calibrated once before the guide groove is cut and before the wafer is continuously cut along the guide groove, the accuracy of the relative position of the cutter and the wafer can be ensured, the uniformity of the cutting can be improved, and the quality of the chip can be improved. Meanwhile, the guide groove is first cut, and then the wafer is continuously cut along the guide groove. Compared with cutting the wafer once and penetrating the wafer, the thermal expansion effect caused is smaller, so that the notch size caused by the edge collapse can be effectively reduced, and the performance and yield of the device can be improved.

[0023] It should be explained that a large amount of heat is generated by the cutting friction between the cutter and the wafer during the cutting process. If the cutter cuts the wafer once and penetrates the wafer, the contact area of the cutter and the wafer is larger, the heat is difficult to dissipate, and a large thermal expansion effect is caused, so that the notch caused by the edge collapse is larger. If the guide groove is first cut, and then the wafer is cut along the guide groove, the contact area of the cutter and the wafer can be reduced, the heat can be easily dissipated, the thermal expansion effect can be reduced, and the notch caused by the edge collapse can be effectively reduced.

[0024] In addition, after the guide groove is cut, before the wafer is cut along the guide groove and penetrated, at least a calibration stage is further passed, in which process the heat remaining in the guide groove is also dissipated, and the thermal expansion effect during the subsequent cutting is further reduced. Therefore, it is determined that, in step S140, the wafer is preferably continuously cut along the first guide groove and penetrated, and in step S150, the wafer is continuously cut along the second guide groove and penetrated. In this way, the time interval of the two times of cutting along the second guide groove can be prolonged, and the thermal expansion effect can be further reduced.

[0025] In one embodiment, the first guide groove and the second guide groove each has a depth of 1 / 4-1 / 2 of the thickness of the wafer, so as to facilitate subsequent cutting along the guide grooves while avoiding cutting too deep through the wafer. Preferably, the first guide groove and the second guide groove have the same depth. By way of example, the depth of the guide grooves can be 1 / 4, 1 / 3, 1 / 2, etc. of the thickness of the wafer, without being limited thereto.

[0026] In embodiment 1: Step S110 further includes: S111, pasting a dicing film on the wafer ring, and the middle of the dicing film is attached with a substrate wafer; S112, coating a wax layer on the substrate wafer; S113, attaching the back of the wafer to the substrate wafer coated with the wax layer; S114, placing the wafer ring carrying the wafer on the dicing machine. The dicing film can be a UV film or a blue film, the substrate wafer can be a silicon wafer, and the wax layer can be paraffin, polyethylene wax or other applicable wax.

[0027] Further, in steps S120 and S130, the spindle speed of the dicing machine is 30000-60000 rad / min, and the feed speed is 1-1.5 mm / s; in steps S140 and S150, the spindle speed of the dicing machine is 30000-60000 rad / min, and the feed speed is 0.5-1 mm / s. By setting the parameters of the dicing machine, the notch generated by the chipping is further reduced. In addition, it should be noted that in steps S140 and S150, the cutter will cut into and scratch the substrate wafer when it penetrates the wafer (will not penetrate the substrate wafer), so as to ensure that the wafer is penetrated.

[0028] Further, the wafer cutting method further includes: S160, melting the wax layer on the substrate wafer by a wax melting machine, so as to facilitate taking out the wafer after cutting. The temperature of the wax melting machine for melting the wax layer of the substrate wafer is 70-90℃, for example, 70℃, 71℃, 72℃, 73℃, 74℃, 75℃, 76℃, 77℃, 78℃, 79℃, 80℃, 81℃, 82℃, 83℃, 84℃, 85℃, 86℃, 87℃, 88℃, 89℃, 90℃.

[0029] In embodiment 2: Step S110 further includes: S111, pasting a UV film on the wafer ring; S112, attaching the UV film to the back of the wafer; S113, placing the wafer ring carrying the wafer on the dicing machine. It should be noted that the attachment of the UV film to the back of the wafer is a prior art, which will not be described here.

[0030] Further, the wafer cutting method further comprises: S160, performing film expansion treatment on the UV film by a film expander; and S170, performing adhesive removal treatment on the UV film by an adhesive remover, and separating the wafer from the UV film. Similarly, the film expansion treatment by the film expander and the adhesive removal treatment by the adhesive remover are prior art, and thus are not described herein.

[0031] It should be noted that the difference between the embodiment 1 and the embodiment 2 is the connection and separation mode of the wafer and the ring. In the embodiment 1, the wafer is connected to the ring by bonding the dicing film on the ring, bonding the substrate sheet on the dicing film, coating the wax layer on the substrate sheet, and fixing the wafer by the wax layer. Subsequently, the wafer and the substrate sheet can be separated by melting the wax layer by the wax melting machine. In the embodiment 2, the wafer and the ring are directly bonded by the UV film. The wafer is directly bonded on the UV film. Therefore, the film expansion and adhesive removal steps are required. Since the UV film needs to be expanded in the embodiment 2, if the wafer is made of a brittle material, the wafer is prone to edge collapse and large notches during the film expansion process, which affects the performance and yield of the device. In the embodiment 1, the wafer and the substrate sheet can be separated by only melting the wax layer. Therefore, the wafer edge collapse probability is further reduced, the large notches caused by the film expansion are avoided, and the performance and yield of the device are improved.

[0032] In addition, it should be further noted that before the wafer is connected to the UV film or the substrate sheet in the embodiment 1 and the embodiment 2, the back surface of the wafer needs to be treated, for example, scraped by a scalpel or wiped by anhydrous ethanol, to ensure the flatness of the contact.

[0033] In order to reflect the advantages of the present application compared with the prior art, application examples and comparative examples are provided for illustration: It should be noted that in the following application examples and comparative examples, the type of the dicing machine is the same, the type of the cutter is a hard cutter, the length of the cutting edge is 0.83 mm, the width of the cutting groove is 0.032 mm, the particle size is 3000 (mesh), and the concentration is 50. The thickness of the UV film is 0.088 mm (if a blue film is used, the thickness of the blue film is 0.07 mm). The size of the wafer is 2 inches, and the material is GaSb.

[0034] Application Example 1 A dicing film is attached to a wafer ring, with a substrate attached to the center of the dicing film. Next, a wax layer is applied to the substrate to secure the wafer. The wafer ring carrying the wafer is then placed in a dicing machine. A first guide groove is cut into the wafer surface, with a depth of 1 / 3 of the wafer thickness. The wafer is then rotated 90°, and a second guide groove is cut into the wafer surface, also with a depth of 1 / 3 of the wafer thickness. The wafer is then rotated another 90°, and cutting continues along the first guide groove, penetrating the wafer. After this, the wafer is rotated another 90°, and cutting continues along the second guide groove, penetrating the wafer. Throughout this process, the dicing machine spindle speed is consistently 40,000 rad / min. The feed rate is 1 mm / s when cutting the guide groove and 0.5 mm / s when cutting through the wafer along the guide groove. After the wafer is diced, the wafer ring carrying the wafer is placed in a wax melting machine to melt the wax (melting temperature is 80℃), and then the diced wafer is removed.

[0035] Application Example 2 A UV film is attached to a wafer ring, and the wafer is then bonded to the center of the UV film. Next, the wafer ring carrying the wafer is placed in a dicing machine. First, a first guide groove is cut into the wafer surface, with a depth of 1 / 3 of the wafer thickness. Then, the wafer is rotated 90°, and a second guide groove is cut into the wafer surface, also with a depth of 1 / 3 of the wafer thickness. The wafer is then rotated another 90°, and cutting continues along the first guide groove, penetrating the wafer. After this, the wafer is rotated another 90°, and cutting continues along the second guide groove, penetrating the wafer. Throughout this process, the dicing machine spindle speed is consistently 55,000 rad / min. The feed rate is 1.35 mm / s when cutting the guide groove and 0.65 mm / s when cutting through the wafer along the guide groove. After wafer dicing, the UV film is first expanded using a film expander, then desorbed using a desizing machine. Finally, the diced wafer is separated from the UV film.

[0036] Comparative Examples A UV film is attached to the wafer ring, and the wafer is then bonded to the center of the UV film. Next, the wafer ring carrying the wafer is placed in a dicing machine, where the cutter cuts through the wafer in one pass. During the dicing process, the dicing machine spindle speed is 55,000 rad / min, and the feed rate is 0.65 mm / s. After wafer dicing, the UV film is first expanded using a film expander, then desorbed using a desizing machine, and finally the diced wafer is separated from the UV film.

[0037] like Figures 2 to 4 As shown, Figure 2 This is a schematic diagram of the back side of the wafer after dicing in Application Example 1. Figure 3Figure 6 is a schematic diagram of the back surface structure of a wafer after cutting is completed in the comparative example, wherein the size of the notch is marked. Figure 4 Figure 6 is a schematic diagram of the back surface structure of a wafer after cutting is completed in the comparative example, wherein the size of the notch is marked. Therefore, the wafer cutting method provided in the present application can effectively improve the uniformity of cutting, reduce the notch caused by the edge collapse, and improve the performance and yield of the device.

[0038] Although the embodiments of the present application have been shown and described, it should be understood by those ordinary skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A wafer cutting method characterized by, The method comprises the steps of: S110, placing the wafer on a dicing machine; S120, calibrating the wafer and the tool position, and then cutting a first guide groove on the surface of the wafer, the depth of the first guide groove being less than the thickness of the wafer; S130, calibrating the wafer and the tool position, and then cutting a second guide groove on the surface of the wafer, the second guide groove being perpendicular to and intersecting the first guide groove, the depth of the second guide groove being less than the thickness of the wafer; S140, calibrating the wafer and the tool position, and then continuing to cut along one of the first guide groove and the second guide groove and penetrating the wafer; S150, calibrating the wafer and the tool position, and then continuing to cut along the other of the first guide groove and the second guide groove and penetrating the wafer.

2. The wafer cutting method according to claim 1, wherein The depth of the first guide groove and the second guide groove is 1 / 4-1 / 2 of the thickness of the wafer.

3. The wafer cutting method according to claim 2, wherein The depth of the first guide groove and the second guide groove is the same.

4. The wafer cutting method according to claim 1, wherein In step S140, the wafer is cut along the first guide groove and penetrates the wafer.

5. The wafer cutting method according to claim 1, wherein In steps S120 and S130, the spindle speed of the dicing machine is 30000-60000 rad / min, and the feed rate is 1-1.5 mm / s.

6. The wafer cutting method according to claim 1, wherein In steps S140 and S150, the spindle speed of the dicing machine is 30000-60000 rad / min, and the feed rate is 0.5-1 mm / s.

7. The wafer cutting method according to claim 1, wherein Step S110 comprises: S111, pasting a UV film on the wafer ring; S112, bonding the UV film to the back of the wafer; S113, placing the wafer ring carrying the wafer on the dicing machine.

8. The wafer cutting method according to claim 7, wherein Further comprising the steps of: S160, expanding the UV film by an expanding machine; S170, separating the wafer from the UV film by a debonding machine.

9. The wafer cutting method according to claim 1, wherein Step S110 comprises: S111, pasting a dicing film on the wafer ring, and the middle of the dicing film is bonded with a substrate sheet; S112, coating a wax layer on the substrate sheet; S113, bonding the back of the wafer to the substrate sheet coated with the wax layer; S114, placing the wafer ring carrying the wafer on the dicing machine.

10. The wafer cutting method according to claim 9, wherein Further comprising the steps of: S160, melting the wax layer on the substrate sheet by a wax melting machine.

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