Processing method for wafer with semiconductor chip formed therein and processing device using the same

Abstract

To provide a method and a device for highly accurately processing a peripheral edge of a semiconductor wafer into an expected shape by uniformizing a cutting depth or preventing the occurrence of chipping when performing cutting or grinding processing on the peripheral edge of the semiconductor wafer with a semiconductor chip formed therein.SOLUTION: A wafer chamfering device 100 for processing a peripheral edge of a semiconductor wafer W, with which a circuit is formed on a surface, performs cutting or grinding processing on the peripheral edge of the wafer by abutting a processing machine tool 180 rotating at high speed to the semiconductor wafer rotating at low speed. In that case, a predetermined processing position in the vicinity of a position, where the processing machine tool is abutted to the semiconductor wafer rotating at low speed, before processing the semiconductor wafer in a rotation direction is irradiated with a laser beam 230 from a laser source 210 of a laser processing device 200, and a surface at the predetermined processing position is fused and made amorphous.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for processing a wafer having a large number of semiconductor chips formed on its surface and a processing apparatus used therefor, and in particular to a method for processing a wafer having semiconductor chips formed thereon that utilizes laser irradiation and is suitable for wafer thinning or terrace processing, and a processing apparatus used therefor. [Background technology]

[0002] In the case of wafers on which a large number of semiconductor chips are formed, a method is used in which a substrate, such as a silicon wafer, is ground from the back surface to make it thinner, and then it is divided into individual semiconductor chips. In order to prevent cracks or scratches that occur on the edge of the wafer from progressing to the center of the wafer and reducing the yield of semiconductor chips, a terrace process is performed to grind only the edge to a specified thickness, and a process is performed to shape the edge prior to thinning the wafer.

[0003] Conventional techniques for processing the peripheral portion of a wafer are disclosed in Patent Document 1 and Patent Document 2. In Patent Document 1, a dicing device is attached to a chuck table to process the wafer in order to form a small-diameter wafer from a large-diameter wafer without using a dedicated processing device, or to create a wafer with an easy-to-handle shape from a cracked wafer without using a laser processing device. Furthermore, the wafer is cut into an arbitrary curved shape by using not only the rotation of the chuck table but also the movement of the chuck table in the X-axis direction and the movement of the blade in the Y-axis direction to obtain a wafer shape that is easy to handle.

[0004] In addition, in Patent Document 2, in the edge trimming process of a wafer, uneven parts of the wafer with uneven thickness are recognized and reprocessed, and the cutting depth is processed to the desired cutting depth. Specifically, a rotating cutting blade is lowered from above the wafer, and the wafer is rotated while cutting into the outer peripheral edge of the wafer to a predetermined depth. At this time, the cutting marks formed on the outer peripheral edge are imaged, the depth of the cutting marks for each rotation angle of the wafer is stored, and it is determined whether the cutting marks have reached the predetermined depth for each rotation angle, and the parts that have not reached the predetermined depth are cut again.

[0005] Patent Document 3 describes a method of thinning a wafer by grinding the back surface of the wafer on which a semiconductor chip is formed. In the wafer thinning described in this publication, in order to prevent cracks or chips from occurring in the peripheral portion of the semiconductor substrate even in back surface grinding where the thickness is reduced to several tens of μm or less, the chamfered portion of the wafer is cut to a depth slightly deeper than the target thickness for back surface grinding. Then, a semiconductor element protective tape is attached to the flat portion of the front surface, and the tape is cut into a circle with a blade to match the shape of the flat portion, and then the back surface of the wafer is ground with a grindstone for back surface grinding. This prevents cracks and chips in the peripheral portion of the wafer caused by the protective tape being caught in the wafer and by the knife-edge-like chamfered portion remaining. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 11-54461 [Patent Document 2] JP 2013-149822 A [Patent Document 3] JP 2000-173961 A Summary of the Invention [Problem to be solved by the invention]

[0007] In the wafer processing device described in the above Patent Document 1, the peripheral portion of a wafer having chips or the like is cut with a dicing blade to produce a small-diameter wafer. However, the device described in this publication only cuts with a dicing blade, and does not take into consideration the possibility that new cracks may occur during processing due to wear of the dicing blade and progress to the center. In other words, in a wafer in which the processing portion is crystalline, there are many places where the processing orientation and the crystal orientation differ, so if the wafer is mechanically processed with a dicing blade, there is a risk that microcracks such as chipping may occur in unexpected directions.

[0008] The wafer processing method described in Patent Document 2 describes cutting the same location multiple times with a cutting blade according to changes in the wafer thickness. However, even in the method described in this publication, the wafer is only mechanically processed with a cutting blade, so there is a risk of microscopic cracks such as chipping occurring in unexpected directions due to differences between the crystal orientation and the processing direction, etc.

[0009] Patent Document 3 also describes a method of grinding the backside of a wafer, in which a protective tape is applied and then the peripheral portion is cut with a blade. The method described in this publication also merely cuts a wafer with a crystal orientation with a cutting tool, so if the processing direction differs from the crystal orientation of the wafer and the tool is worn away, the wafer may chip in an unexpected direction or microcracks may occur.

[0010] The present invention has been made in consideration of the above-mentioned deficiencies in the conventional technology, and has as its object to process the peripheral portion of a wafer having semiconductor chips formed thereon into a desired shape with high precision by making the cutting depth uniform or preventing chipping, even when wear of tools such as grinding wheels and cutting tools is expected to occur when cutting or grinding the peripheral portion of the wafer on which semiconductor chips are formed. [Means for solving the problem]

[0011] A feature of the present invention for achieving the above-mentioned object is that, in a processing method for processing a peripheral portion of a semiconductor wafer having a circuit formed on a surface thereof, the method includes the steps of bringing a high-speed rotating processing tool into contact with the semiconductor wafer rotating at a low speed to cut or grind the peripheral portion of the semiconductor wafer, and irradiating a laser beam to a planned processing position before processing the semiconductor wafer, which is in the vicinity of the position where the processing tool contacts the semiconductor wafer rotating at a low speed, to melt and amorphize the surface of the planned processing position, the planned processing position being behind the position where the processing tool is disposed in the rotation direction of the semiconductor wafer and having a surface that has not yet been contacted by the processing tool, and a control device controls so that only the planned processing position that has undergone the laser beam irradiation step is cut or ground.

[0012] In this feature, instead of the planned processing position being behind the position where the processing tool is arranged in the rotation direction of the semiconductor wafer, the planned processing position is a position which is ahead of the rotation direction of the semiconductor wafer after processing the semiconductor wafer, and where the frictional heat generated in the processing is not substantially completely dissipated, and in a pass in which the planned processing position is first cut or ground, it is preferable to irradiate the planned processing position with laser light in advance.

[0013] Furthermore, when the semiconductor wafer is composed of at least one of a Si substrate, a sapphire substrate, a GaN substrate, a SiC substrate, a lithium tantalate substrate, and a lithium niobate substrate, it is preferable that the laser light be a pulsed laser light having a long wavelength of 532 nm or more, and when the semiconductor wafer is composed of a gallium oxide substrate, it is preferable that the laser light be an ultraviolet excimer laser light.

[0014] Another feature of the present invention for achieving the above-mentioned object is that a processing apparatus for processing a semiconductor wafer having a number of semiconductor chips formed on its surface includes a processing tool that rotates at high speed and cuts or grinds the peripheral portion of the semiconductor wafer, a rotating bed that rotates the semiconductor wafer at a low speed, and a control device that controls the rotation of the processing tool and the rotation of the semiconductor wafer, and a laser light irradiation device is provided that, when the peripheral portion of the wafer is processed with the processing tool, irradiates with laser light that melts and amorphizes the processed surface of the wafer near a position where the processing tool contacts the semiconductor wafer and at a position before the processing tool performs cutting or grinding, and the control device controls the laser light to be irradiated in advance to a processing position where the processing tool will perform cutting or grinding.

[0015] In this feature, it is preferable that the laser light irradiation device emits a pulsed laser light, and when the semiconductor wafer is composed of a gallium oxide substrate, it is preferable that the laser light irradiation device is an ultraviolet excimer laser, and when the semiconductor wafer is composed of at least any one of a Si substrate, a sapphire substrate, a GaN substrate, a SiC substrate, a lithium tantalate substrate, and a lithium niobate substrate, it is preferable that the laser light irradiation device is capable of emitting a pulsed laser light with a long wavelength of 532 nm or more. Effect of the Invention

[0016] According to the present invention, when cutting or grinding the peripheral portion of a wafer on which semiconductor chips are formed, the intended cutting or grinding position is amorphized and modified by laser irradiation before processing, so that the cutting or grinding can be performed at the intended processing position, the cutting depth can be made uniform, and chipping can be prevented. This allows the peripheral portion of the wafer to be processed into the intended shape with high precision. [Brief description of the drawings]

[0017] [Figure 1] 1 is a front view of an embodiment of a processing apparatus for a wafer on which semiconductor chips are formed according to the present invention; [Diagram 2]2 is a top view of the laser processing apparatus for explaining the arrangement of the laser processing apparatus shown in FIG. 1. FIG. [Diagram 3] 1A to 1C are diagrams illustrating a procedure of one embodiment of wafer processing according to the present invention. [Figure 4] 11 is a front view of another embodiment of the apparatus for processing a wafer on which semiconductor chips are formed according to the present invention; FIG. [Diagram 5] 5 is a top view of the laser processing apparatus for explaining the arrangement of the laser processing apparatus shown in FIG. 4. [Figure 6] 10A to 10C are diagrams illustrating the procedure of another embodiment of wafer processing according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, the processing device and processing method of a wafer on which a semiconductor chip is formed according to the present invention will be described with reference to the drawings. FIG. 1 is a front view of an embodiment of a wafer processing device 300 including a wafer chamfering device 100 used for terrace processing of a wafer W on which a semiconductor chip is formed. The wafer chamfering device 100 is a device for processing the peripheral portion of a wafer W or various brittle plate-like bodies, and can process, for example, Si wafers and compound semiconductors such as sapphire, SiC, GaN, and LT. In the following description of this embodiment, a silicon wafer W will be taken as an example of a workpiece to be processed by the wafer chamfering device 100, but wafers, plate-like bodies, and bonded wafers made of other materials can also be processed in the same manner.

[0019] The wafer chamfering apparatus 100 includes a wafer feed unit 102 and a grinding unit 104. The wafer feed unit 102 includes a horizontally disposed base plate 106, on which a pair of Y-axis guide rails 108 are disposed in parallel with a gap therebetween, and a Y-axis linear guide 110 is disposed on each Y-axis guide rail. A Y-axis table 112 is placed on the Y-axis linear guide 110. The Y-axis table 112 moves linearly in the Y direction along the Y-axis guide rails 108 by a Y-axis ball screw 116 driven by a Y-axis motor 114.

[0020] A pair of X-axis guide rails 120 are disposed parallel to each other at a distance from each other on the Y-axis table 112, perpendicular to the Y-axis guide rail 108, and an X-axis linear guide 122 is disposed on each X-axis guide rail 120. An X-axis table 124 is placed on the X-axis linear guide 122. The X-axis table 124 is moved linearly in the X direction along the X-axis guide rails 120 by an X-axis ball screw 128 driven by an X-axis motor 126.

[0021] A Z-axis base 130 is provided on the X-axis table 124 perpendicular to the X-axis table 124, and a Z-axis guide rail 132 is disposed on the Z-axis base 130. A Z-axis linear guide 134 is attached to the Z-axis guide rail 132, and a Z-axis table 136 is disposed on the side of the Z-axis linear guide 134 opposite the Z-axis guide rail surface so as to be movable up and down. The Z-axis table 136 is movable up and down by a Z-axis ball screw 140 driven by a Z-axis motor 138. That is, when the Z-axis motor 138 is driven, the Z-axis ball screw 140 rotates, and the Z-axis table 136 moves up and down along the Z-axis guide rail 132.

[0022] A θ-axis motor 150 is disposed on the Z-axis table 136, which rotates and drives a suction table 160 serving as a rotating bed that is a holding platform used to rotate the workpiece. The θ-axis motor 150 is connected to a θ-axis shaft 152, and the suction table 160 is horizontally connected to the upper end of the θ-axis shaft 152. The suction table 160 is a so-called vacuum chuck, on which a wafer W, which is a workpiece, is vacuum-sucked and placed, and in this state, the wafer W is terraced. Here, the θ-axis is a rotation axis that is parallel to the Z-axis and faces in the vertical direction.

[0023] In the wafer feed unit 102 configured in this manner, the control device 252 drives and controls the Y-axis motor 114, thereby moving the suction table 160 in the Y direction, which is the left-right direction in Fig. 1, and similarly, the control device 252 drives and controls the X-axis motor 126, thereby moving the suction table 160 in the X direction, which is the front-to-back direction of the paper in Fig. 1. In addition, the control device 252 drives the θ-axis motor 150, thereby rotating the suction table 160 at a relatively low speed around the θ-axis parallel to the Z-axis.

[0024] On the other hand, in the grinding unit 104 to which the grinding wheel 180 is attached, a stand 174 is disposed on the base plate 106. An outer peripheral motor 176 is provided on the stand 174, and the outer peripheral motor 176 is connected to a spindle 178. A central axis CH of the spindle 178 is parallel to the Z-axis. The grinding wheel 180 is detachably attached to the lower end of the spindle 178. The spindle 178 is rotated at a relatively high speed by the outer peripheral motor 176. A nozzle 192 that ejects coolant 190 is disposed near the grinding wheel 180, and sprays the coolant 190 to the grinding position where the grinding wheel 180 abuts against the workpiece.

[0025] The terrace processing apparatus configured as above adopts the same configuration as the conventional wafer chamfering apparatus 100, but the present invention is characterized in that, in addition to the conventional mechanical grinding process described above, laser processing is used in combination with the grinding process. For this reason, a laser processing device 200 is added to the wafer chamfering apparatus 100. The wafer chamfering apparatus 100 equipped with this laser processing device 200 will be referred to as the wafer processing apparatus 300 below.

[0026] In the wafer processing apparatus 300, the laser processing apparatus 200 is disposed near the wafer chamfering apparatus 100. This state will be described with reference to Fig. 2. Fig. 2 is a top view of the wafer processing apparatus 300 including the main parts of the laser processing apparatus 200. In Fig. 1, the laser processing apparatus 200 is disposed on the opposite side of the grinding unit 104 across the wafer feed unit 102 for ease of understanding, but as shown in Fig. 2, the laser processing apparatus 200 is disposed so that the irradiation position is located near the position where the grinding wheel 180 abuts against the wafer W.

[0027] The laser processing apparatus 200 includes a laser light source 210 and a beam splitter 212 that splits the light emitted from the laser light source 210 into two beams. One of the beams split by the beam splitter 212, a first beam 220, is adjusted in position in the Z-axis direction via a galvanometer mirror 222 and an f-θ lens 224 to be an irradiation position P I The other light, the second split light 230, is similarly adjusted in position in the radial direction via a galvanometer mirror 232 and an f-θ lens 234 to reach an irradiation position P I The wafer W is irradiated at an irradiation position P I In the present embodiment, these two beams irradiate the respective surfaces 242, 244 to heat the wafer W before grinding.

[0028] Depending on the form of the terrace processing, the end surface 242 that spreads in the vertical direction and is formed by the terrace processing becomes a conical surface instead of a cylindrical surface. In that case, the first split light 220 is incident on the end surface 242 at an angle. In addition, when the frictional heat generated during the grinding process is used in combination to further improve the next grinding surface, the laser light irradiation position P I The position before the cooling effect of the coolant 190 progresses, that is, the position immediately after the grinding process (since the wafer is rotating to the right in the figure, the grinding position P g It is also possible to set it to the right of

[0029] Each of the optical components 212, 222, 224, 232, 234 of the laser processing apparatus 200 is disposed in a housing or holder 254, which in this embodiment is disposed on the upper surface of the control device 252 of the wafer chamfering apparatus 100. In other words, the control device 252 also functions as a stand, and aims to make effective use of the processing space. The control device 250 of the laser processing apparatus 200 is incorporated on the upper part of the control device 252 of the wafer chamfering apparatus 100, and controls the emission of the laser light from the laser light source 210, the irradiation position and rotation of the galvanometer mirrors 222, 232, etc.

[0030] The processing method of the present invention for terrace processing of a wafer W using the wafer processing apparatus 300 configured as described above will be described with reference to Figs. 1 to 3. Here, Fig. 3 is a diagram showing the state of terrace processing of a wafer W in a partial front view of the wafer. Fig. 3(a) shows the state before terrace processing, Fig. 3(b) shows the laser processing state before grinding processing, and Fig. 3(c) shows the state during grinding processing. Fig. 3(d) shows the state after the terrace processing is completed. In the terrace processing using the wafer chamfering apparatus 100, the wafer W is first placed on the suction table 160 and vacuum-sucked. At the same time, the Z-axis motor 138 is driven to adjust the height of the suction table 160 to match the height of the wafer W to the processing position of the grinding wheel 180, and the X-axis motor 126 is driven to match the θ-axis, which is the rotation axis of the wafer W, with the X-axis position of the center axis CH of the grinding wheel 180. At this time, the Y-axis motor 114 is not driven, or if the wafer W is too close to the grinding wheel 180, it is driven so as to retreat to a retreat position.

[0031] Next, the control device 252 controls the rotation of the peripheral motor 176 at a high speed and the θ-axis motor 150 at a low speed so that they move in the same direction. For example, the motors 176, 150 are controlled so that the rotation speed of the grinding wheel 180 attached to the spindle 178 connected to the peripheral motor 176 is 3000 rpm and the peripheral speed of the wafer W is 5 mm / s.

[0032] In this state, the control device 252 drives the Y-axis motor 114 to move the wafer W closer to the grinding wheel 180 in the Y-axis direction (see FIG. 3(a)). Then, when the wafer W approaches close to the point where it contacts the grinding wheel 180, the rotation speed of the Y-axis motor 114 is reduced to decelerate the feed speed of the wafer W in the Y-axis direction, and the grinding wheel 180 is brought into contact with the wafer W. Thereafter, the feed amount of the wafer W in the Y-axis direction is determined so as to be the radial grinding width per grinding, and grinding is started over the entire circumference of the wafer W at the determined feed amount (see FIG. 3(c)). Once grinding is started, a coolant 190 is sprayed from a nozzle (coolant supplying means) 192 toward the grinding position to remove grinding chips and wear powder of the grinding wheel generated by grinding from the grinding position and to cool the grinding location.

[0033] The radius grinding width possible in one grinding (per pass) is the desired terrace processing area P T If the width of the desired terrace processing portion P is reached, the Y-axis motor 114 is driven to move the wafer W away from the grinding position when grinding is completed over the entire circumference. T If the width is smaller than the width of the wafer W, the above is repeated multiple times (multiple passes). Generally, when performing terrace processing on a wafer, multiple grinding operations are required in the thickness direction of the wafer, i.e., in the Z direction, so the Z-axis motor is driven to move the wafer W in the Z direction by a predetermined Z-axis feed amount to change the grinding height position. Since the height position of the wafer W has changed downward, the Y-axis motor 114 is driven again to abut the wafer W, and grinding is performed for a predetermined radial width at a predetermined Y-axis feed amount. This is repeated until the wafer W has been terraced to a predetermined thickness (see FIG. 3(d)), and the processing of the next wafer W is started. Note that FIG. 3(b) is a diagram showing a laser processing state described in detail below, and the circumferential position of the wafer feed unit 102 is shown differently from the other diagrams (FIGS. 3(a), (b), and (d)). In the above-mentioned terrace processing, the control device 252 controls the grinding speed of the grinding wheel 180, the rotation speed of the wafer W, and the positions of the grinding wheel 180 and the wafer W.

[0034] However, when the grinding wheel 180 is brought into contact with the wafer W, friction occurs due to the difference in rotational speed between them, and high-hardness abrasive grains such as diamonds scrape off the surface of the wafer W. Therefore, a large frictional force is instantaneously applied to the surface of the wafer W, and if the abrasive grains are not stably held by the grinding wheel 180, that is, if the grinding wheel 180 is worn down, the wafer W may be damaged unexpectedly, and undesirable defects may occur.

[0035] Therefore, the location (planned processing position) P T is destroyed in advance by the laser beam to reduce the grinding load caused by the abrasive grains or to serve as a guide for grinding. In other words, by microscopically determining in advance the location of the wafer W to be removed by the abrasive grains with the laser beam, when the abrasive grains pass that portion, the wafer is peeled off only from the portion that has been microscopically destroyed and made amorphous by the laser beam, preventing unintended peeling. This destruction by the laser beam is microscopic, unlike destruction by the abrasive grains, and the wafer W is temporarily melted and made amorphous in a liquid phase or a state close to it, so that the shear stress caused by the abrasive grains is significantly reduced.

[0036] The state of the pre-modification of the wafer W by such a laser beam is shown in FIG. 3(b). Since this is pre-modification of the wafer W, it is carried out before the grinding process. Therefore, the grinding position P g The position behind the rotation direction of the wafer W (since the wafer W rotates clockwise in the figure, the grinding position P g The laser beam irradiation position P I As described above, if the wafer W is to be further ground at a different position in the thickness direction after the current grinding process, the laser irradiation position P for pre-modification is set to the position after the grinding process is completed, that is, the front position in the rotation direction of the wafer W. I In this case, the laser irradiation position P can be set to a position immediately after the end of the grinding process, where the frictional heat generated by the grinding process can be utilized. I By setting the above, the surface of the wafer W can be pre-modified and made amorphous, including by absorbing the frictional heat generated during grinding, before the frictional heat is dissipated by the coolant 190, and the wafer can be pre-modified effectively.

[0037] Laser processing using the laser processing apparatus 200 shown in this embodiment will be further described below. The laser light is a pulsed laser light, and it is preferable that the wavelength is changed according to the material of the workpiece, the wafer W. When the workpiece is a wafer or substrate made of Si (silicon), sapphire (gallium nitride), GaN (silicon carbide), LiTaO3 (lithium tantalate), LiNbO3 (lithium niobate), or the like, it is preferable to use a nanosecond pulsed laser with a relatively long wavelength of 532 nm or more in terms of heat absorption of the terrace processing surface.

[0038] In this case, in the case of a GaN or SiC substrate or wafer, a fluid material with high laser absorption may be applied to the surface of the wafer or substrate and then irradiated with the laser light. In this case, a high proportion of the laser light is absorbed by the fluid material before reaching the inside of the wafer W, so that the heat generated by the laser light is concentrated on the interface of the wafer W, i.e., the terraced surfaces 242, 244, and the wafer W can be melted more effectively, and the terraced surfaces 242, 244 can be flattened. On the other hand, in the case of Ga2O3 (gallium oxide), the wafer W can be pre-modified by using an ultraviolet excimer laser with a short wavelength, for example, a wavelength of 250 to 260 nm.

[0039] According to this embodiment, the control device 252 controls the wafer W immediately before grinding to be irradiated with laser light in accordance with a previously stored program, melting and modifying the processed surface, and then terrace-processing the wafer W, so that it is possible to determine in advance the area where the abrasive grains of the grinding wheel 180 peel off from the wafer W. This makes it possible to prevent unintended parts of the wafer W from being peeled off by the abrasive grains, and to prevent defects, cracks, chipping, and other problems from occurring on the processed surface. This makes it possible to prevent cracks caused by the terrace portion from progressing to the chip portion formed on the semiconductor wafer, and improves the yield of semiconductor manufacturing.

[0040] Next, another embodiment of the processing of a wafer on which semiconductor chips are formed according to the present invention will be described with reference to Figs. 4 to 6. The processing in this embodiment is a trimming process for cutting the peripheral portion of a wafer W on which semiconductor chips are formed. The tool used in the trimming process is a disk-shaped dicing blade 182. Fig. 4 is a front view of a wafer processing device 301 corresponding to Fig. 1, and Fig. 5 is a top view of the laser processing device 201 portion showing the arrangement of the laser processing device 201. Fig. 6 is a diagram for explaining the trimming process, showing the relative relationship between the wafer, the dicing blade 182, and the laser processing device 201.

[0041] 4, the wafer chamfering apparatus 100 in FIG. 1 is provided with the grinding unit 104, but the wafer processing apparatus 301 in this embodiment is provided with a dicing apparatus 101 having a cutting unit 105 instead. The cutting unit 105 of the dicing apparatus 101 has a configuration almost similar to that of the grinding unit 104 in FIG. 1, but differs from the grinding unit 104 in FIG. 1 in that a spindle 178 is formed on a horizontal axis and a dicing blade 182, which is a disk-shaped cutter, is attached to the tip of the spindle 178. In the cutting unit 105, the dicing blade 182 is lowered while rotating at high speed, and is brought into contact with the wafer W placed on the suction table 160 to cut the peripheral portion of the wafer into a predetermined shape.

[0042] 1, the direction of the emitted light 216 from the laser light source 210 is changed by the galvanometer mirror 232 and enters the f-θ lens 234. The position is adjusted by the galvanometer mirror 232 and the f-θ lens 234, and the edge trimming portion or the trimming processing portion P of the wafer W is TR (See FIG. 6(a)).

[0043] As shown in FIG. 5, in this embodiment as well, the laser processing apparatus 201 has a dicing section (trimming section) P TRIn other words, since the wafer W rotates clockwise, the trimming processing portion P TR The irradiation position P of the laser processing device 201 is on the left side of I is set.

[0044] The control device 252, according to a program stored in advance, controls the laser processing device 201 to focus the laser beam on the trimming processing portion P, which is a processing target position, before the dicing processing of the wafer W. TR The wafer W is controlled to melt and become amorphous. Therefore, the wafer W is microscopically broken, and dicing proceeds from the broken part. This makes it possible to prevent unintended peeling or cracks from progressing to the center of the wafer W.

[0045] In Fig. 5, the laser irradiation position P I and trimming processing part P TR Since a nozzle 192 for the coolant 190 is disposed between the laser irradiation position P and the wafer W, the wafer W is cooled after the laser irradiation and before the dicing process. I If the laser beam is transmitted to the laser processing device 201, the efficiency of the laser irradiation decreases. I Trimming processing part P TR It is also possible to place it behind, i.e., on the right side in FIG.

[0046] In this case, there is an advantage that frictional heat during dicing that has not yet been sufficiently dissipated by the coolant 190 can be utilized together with the heat generated by the laser light. However, this method is only effective when dicing is performed multiple times (multiple passes) in the thickness direction of the wafer W, and even in this case, the benefit of pre-modification of the wafer W by laser irradiation cannot be obtained in the initial (first processing pass) dicing. To avoid this, in the first pass, the controller 252 controls the wafer W to rotate while only irradiating it with laser light without dicing, and from the next time (next pass), the wafer W is diced as usual before laser processing is performed.

[0047] Even in this case, the frictional heat generated during the dicing process cannot be utilized in the initial wafer modification using the laser light, so the laser light irradiation position P I When setting, the trimming line L on the wafer W is set for the first pass only. TR It is desirable to emit a laser beam with a higher output along the optical axis.

[0048] 6 shows a dicing method using a wafer processing device 301 equipped with a dicing device 101 and a laser processing device 201. The dicing blade 182 is rotated at a high speed of, for example, 500 rpm in the R direction (see FIG. 5), and the wafer W is rotated at a low speed of a peripheral speed of 5 mm / s. The laser is irradiated on the wafer W at a position P I (Figure 6(a)). Irradiation position P I indicates a trimming line L along which the wafer W is trimmed using a dicing blade 182. TR The irradiation position P I is set at a position behind the dicing position 196 at which the dicing blade 182 contacts the wafer W in the rotation direction of the wafer W.

[0049] Irradiation position P of the same wafer W I At the dicing processing position 196, which is a rear position in the rotation direction of the wafer W, the irradiation position P I The wafer W that has been irradiated with the laser light and modified is then cut using a dicing blade 182 (FIG. 6(b)). The steps of FIG. 6(a) and FIG. 6(b) are repeated the desired number of processing passes. Finally, the peripheral portion of the wafer W is cut into the desired shape, and the trimming process is completed (FIG. 6(c)).

[0050] In this embodiment, the wafer is irradiated with laser light immediately before dicing, and the processed surface is melted and reformed to be amorphous, so that it is possible to microscopically distinguish in advance the areas to be cut by the dicing blade from the areas not to be cut. Therefore, it is possible to prevent unintended parts of the wafer W from being cut microscopically, and to prevent defects, cracks, chipping, and other problems on the processed surface. This prevents cracks caused by the edge trimming portion from progressing to the chip portion formed on the semiconductor wafer, and improves the yield of semiconductor manufacturing.

[0051] In addition, if the laser processing described in each of the above embodiments is performed at least before the final step or before the finishing step in the terrace processing or trimming processing, a wafer can be provided in a flattened state without cracks or chipping for the next step such as a thinning step. Therefore, laser processing can be omitted when it is desired to eliminate the complexity of processing or when there is little risk of cracks or chipping occurring in the intermediate processing. However, since it is difficult to predict the timing of wear occurrence in the grinding wheel or dicing blade, it is desirable to use the laser processing shown in each of the above embodiments in combination before each grinding or cutting pass. [Explanation of symbols]

[0052] 100...wafer chamfering device, 101...dicing device, 102...wafer feed unit, 104...grinding unit, 105...cutting unit, 106...base plate, 108...Y-axis guide rail, 110...Y-axis linear guide, 112...Y-axis table, 114...Y-axis motor, 116...Y-axis ball screw, 120...X-axis guide rail, 122...X-axis linear guide, 124...X-axis table, 126...X-axis motor, 128...X-axis ball screw, 130...Z-axis base, 132...Z-axis guide rail, 134...Z-axis linear guide, 136...Z-axis table, 138...Z-axis motor, 140...Z-axis ball screw, 150...θ-axis motor, 152...θ-axis shaft, 160...suction table (rotating bed), 174...frame, 176...periphery motor, 178...spindle, 180...grinding wheel (machining tool), 182...dicing blade (machining tool), 190...coolant, 192...coolant supply means (nozzle), 196...dicing processing position, 200, 201...laser processing device, 210...laser light source, 212...beam splitter, 216...emitted light, 220...(first) splitting, 222...galvanometer mirror, 224...f-θ lens, 230...(second) splitting, 232...galvanometer mirror, 234...f-θ lens, 242...(terrace processing) end surface, 244...terrace processing surface, 250...(laser processing device) control device, 252...control device, 254...holding tool (housing), 300, 301...wafer processing device, CH...center axis, L TR …Trimming line, P I …(laser) irradiation position, P g … grinding position, P T … Terrace processing area (planned processing position), P TR …Trimming processing area (dicing processing area, planned processing position), R…Rotation direction, W…Wafer

Claims

1. A method for processing a semiconductor wafer, comprising rotating a semiconductor wafer having a circuit formed on a surface thereof and contacting a rotating processing tool with a peripheral portion of the semiconductor wafer to process the peripheral portion, A method for processing a semiconductor wafer, comprising: irradiating the semiconductor wafer with laser light having a wavelength according to the material thereof at a position in a rotational direction preceding the processing position by the processing tool, thereby amorphizing the semiconductor wafer.

2. 2. The semiconductor wafer processing method according to claim 1, wherein the laser light is irradiated to a position where the processing tool is scheduled to come into contact next, the position being a position ahead in a rotation direction corresponding to the processing position, where frictional heat generated in the processing is not substantially completely dissipated.

3. A semiconductor wafer processing device that rotates a semiconductor wafer having a circuit formed on a surface thereof and processes the peripheral portion by bringing a rotating processing tool into contact with the peripheral portion, A semiconductor wafer processing device comprising a laser irradiation device that irradiates laser light having a wavelength corresponding to the material of the semiconductor wafer to amorphize the material at a position in a rotational direction corresponding to a processing position by the processing tool.

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