JP7016934B2 - Wafer chamfering equipment - Google Patents

Description

The present invention relates to a method for processing a semiconductor wafer and a wafer, and particularly relates to a wafer chamfering apparatus suitable for chamfering a semiconductor wafer having openness.

Wafers such as silicon, which is a material for semiconductor devices and electronic components, are sliced from the ingot state by a slicing device such as an inner peripheral blade or wire saw, and then placed on the outer peripheral part to prevent cracking or chipping of the peripheral edge. It is chamfered. A plurality of various grindstones such as an outer peripheral grindstone for grinding the outer peripheral portion of the wafer and a notch grindstone for grinding the V-shaped notch portion which is the reference position of the orientation are attached to the chamfering device used for chamfering. Then, the attached grindstone is rotated at high speed by the spindle to perform chamfering. During processing, the wafer was adsorbed and placed on a rotating wafer table, and the wafer and the grindstone were relatively moved by the X-guide, Y-guide, and Z-guide guide axes to form the grindstone. Place the outer periphery of the wafer on the groove for chamfering.

An example of such a wafer processing method is described in Patent Document 1. In the wafer processing method described in this publication, in a wafer on which an orientation flat or an index flat is formed, a single crystal of a compound semiconductor is used in order to improve the processing yield in the steps after the chamfering process. An orientation flat or an index flat is formed at the position of the cleavage plane peculiar to the crystal constituting the wafer obtained by cutting the wafer. Then, the outer peripheral surface, the front surface, the back surface, and the peripheral edge portion of the wafer including these flats are formed in the chamfered portion.

Other processing examples of conventional semiconductor wafers are described in Patent Document 2. In the wafer processing method described in this publication, in the double-sided wrapping operation, the double-sided wrapping step and cleavage are performed in order to prevent chipping defects that occur in the corners where the opening surface of the orientation flat forms a right angle with the front and back surfaces of the wafer. The semiconductor wafer is processed in the order of the scribing process for forming the surface and the chamfering process for the outer peripheral portion of the wafer excluding the cleavage surface portion.

Prior art by the present inventors is described in Patent Document 3 and Patent Document 4. In these publications, in order to reduce the processing time required for chamfering the outer periphery of a wafer, or to perform chamfering with high accuracy regardless of wafer variation, a grindstone for rough grinding and a grindstone for fine grinding are provided, or a wafer grindstone is provided. The positions of the grindstone and the wafer are adjusted based on the relative positions at the machining points of.

Japanese Patent Application Laid-Open No. 2003-86476 Japanese Unexamined Patent Publication No. 2005-32804 Japanese Unexamined Patent Publication No. 2014-226767 Japanese Unexamined Patent Publication No. 2010-162661

In the processing of general semiconductor wafers, an orientation flat (also referred to as an orientation flat) is formed in the middle of processing, including the requirements for determination and alignment of crystal directions and, in the case of laser applications, focusing. That is, when a large number of wafers are manufactured from a semiconductor single crystal or polycrystalline ingot, in many cases, the ingot is first sliced in a direction perpendicular to the axis, and the cleavage is found by using a means such as an electron microscope. A diamond pen is used to scratch and screen the wafer to form an orifura on the surface. As a result, a wafer shape obtained by cutting a part of a circle with a straight line can be obtained. The obtained partially cut disk is a flat plate, and the corners formed by the side surface portion and the upper and lower surface portions are at right angles. Since the material of the semiconductor wafer itself is a material with high hardness such as silicon, the sliced wafer is also high in hardness and brittle. Moreover, the corners between the upper and lower surfaces and the side surfaces form sharp ridges, and cracks and chips due to these corners are likely to occur in the following processing and the like. Therefore, in a wafer having an orientation flat or an index flat, the ridgeline portion between the corner portion of the wafer and the upper and lower surfaces is chamfered to 45 ° or less.

In the above Patent Document 1, further, in order to prevent cracking or breakage starting from the corners of both ends of the orientation flat or the index flat, after the index flat is provided at the position of 90 ° or 270 ° with the orientation flat. The entire circumference of the wafer is chamfered to prevent the corners of both flats from directly hitting the surface plate of the lapping machine or the polishing cloth of the polishing machine. However, in Patent Document 1, processing of a wafer during chamfering, specifically, chipping (chips) that may occur when the grinding wheel for chamfering comes into contact with the wafer during chamfering. No consideration is given to the occurrence of defects. That is, when the grindstone is brought close to the wafer for grinding, depending on how the grindstone is brought close to the wafer, the force applied to the wafer from the grindstone which is a processing tool may cause cracking or damage from the cleaved surface or its vicinity. Also, the case where the orifra is a surface different from the cleavage surface is not considered.

In Patent Document 2, based on the experience that chipping occurs from the cleaved surface at a rate of 7% when the wafer is processed by the conventional processing procedure, the double-sided lapping process is preceded by the scribing process and the chamfering process. Is disclosed. However, even in this Patent Document 2, the occurrence of processing defects during chamfering is not taken into consideration. Also, the case where the orifra is a surface different from the cleavage surface is not considered.

Patent Documents 3 and 4 are prior arts by the present inventors, and initially perform high-precision chamfering without being affected by shortening of the chamfering time and the thickness of the wafer and warpage. You have achieved your goal. However, in the subsequent developmental research, a new problem of improving the yield in chamfering was discovered, and these are not sufficiently considered in Patent Documents 3 and 4.

The present invention has been made in view of the above-mentioned defects of the prior art, and an object thereof is to reduce the occurrence of wafer defects due to chamfering in chamfering of a semiconductor wafer having a cleaved surface, and to reduce the occurrence of wafer defects in the chamfering. Is to improve. Another object of the present invention is to reduce processing defects of the wafer and improve the yield in the processing even in the processing after the chamfering process, in addition to the above object.

A feature of the present invention that achieves the above object is a chamfering device for chamfering the outer peripheral portion of a semiconductor wafer formed by slicing from an ingot, and a grindstone for chamfering the outer peripheral portion of the wafer and the grindstone are rotated. A motor and a spindle for driving, a wafer feeder that holds the wafer and moves the wafer in the X, Y, and Z directions, and a storage that stores data on the diameter, thickness, and open surface of the wafer. A means and a control device for controlling the wafer feed device are provided, and the control device rotates the wafer based on the data stored in the storage means when the grindstone first contacts the wafer. By controlling the wafer feeder to rotate the wafer until the wafer opening surface is located on the line connecting the center and the rotation center of the grinding wheel, the wafer opening surface is first on the grinding wheel. It is provided that the wafer is positioned in a direction perpendicular to the tangential direction of the wafer when it comes into contact with the wafer.

In this feature, the wafer feeding device includes an X-axis driving means for driving the wafer in a direction orthogonal to the tangential direction of the grindstone and a Y-axis driving means for driving the wafer in the tangential direction of the grindstone. It is desirable that the control device makes it possible for the Y-axis driving means to bring the wafer closer to the grindstone from the tangential direction of the grindstone and bring it into contact with the grindstone. Further, it is preferable to complete the movement of the wafer in the X-axis direction and the rotation in the θ-axis before the movement in the Y-axis direction is completed.

Further, in the present invention, the control device controls to move the wafer in a direction orthogonal to the tangential direction by using the X-axis driving means before controlling the wafer to be brought into close contact with the grindstone. It is desirable to enable the wafer to approach the grindstone from the tangential direction.

According to the present invention, in the chamfering process of a semiconductor wafer having a cleavage plane, when chamfering is started, the direction in which the grindstone comes into contact with the wafer is brought closer to the direction perpendicular to the cleavage plane, and the force applied from the grindstone to the wafer. Since the components in the direction perpendicular to the cleavage surface are reduced as much as possible, it is possible to reduce the occurrence of wafer processing defects due to chamfering such as chipping and cracking starting from the cleavage surface. Therefore, the entire circumference of the wafer can be chamfered with a high yield, the processing defect of the wafer can be reduced even in the processing after the chamfering, and the yield in the processing of all wafers can be improved.

It is a schematic top view of an Example of the wafer chamfering apparatus which concerns on this invention. It is a front view of the processing apparatus included in the wafer chamfering apparatus shown in FIG. It is a schematic top view for demonstrating the movement of a wafer at the start of chamfering. It is a schematic top view which shows the state at the time of the start of chamfering of a wafer by this invention. It is a schematic top view which shows the state at the time of the start of chamfering of the wafer of the comparative example. It is a figure explaining the relationship between a wafer diameter error and chamfering. It is a flowchart explaining the chamfering procedure of a wafer by this invention.

Hereinafter, an embodiment of the wafer chamfering apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic top view of an embodiment of the wafer chamfering device 10, and FIG. 2 is a front view of a processing portion 16A (16B) which is a main part of the wafer chamfering device 10 shown in FIG.

The wafer chamfering device 10 includes a supply / recovery unit 12, a prealignment unit 14, two processing units 16A and 16B, an orientation flat (hereinafter referred to as an orientation flat) polishing unit 18, a cleaning unit 20, a post-measurement unit 22, and a transport unit. It has 24, an operation panel 17, and a control device 15. The supply / recovery unit 12 supplies the chamfered wafer W from the wafer cassette 30 to the processing side 19, and collects the chamfered wafer W from the processing side 19 to the wafer cassette 30. The supply / recovery unit 12 of this embodiment includes four cassette tables 32 and one supply / recovery robot 34.

The supply / recovery robot 34 takes out one wafer W from each wafer cassette 30 set on the cassette table 32 and supplies it to the prealignment unit 14. At the same time, the chamfered wafer W is stored in the wafer cassette 30 from the post-measurement unit 22. The supply / recovery robot 34 is provided with a 3-axis rotary type transfer arm 36, and holds the wafer W by vacuum suctioning the back surface of the wafer W with a suction pad. The transfer arm 36 of the supply / recovery robot 34 is provided on a slide block 40 that can move along the guide rail 38. As the slide block 40 moves in the front-rear direction (Y-axis direction), the transfer arm 36 moves.

The pre-alignment unit 14 measures the thickness of the wafer W to be chamfered and performs pre-alignment. The prealignment unit 14 includes a measurement table 50, a thickness sensor 52, and an orientation flat detection sensor 54. The measuring table 50 rotates the wafer W around its central axis. The thickness sensor 52 is a capacitance sensor and measures the distance from the front surface to the back surface of the wafer W. The measurement result of the capacitance sensor is output to an arithmetic unit (not shown), and the thickness of the wafer W is obtained. The tilter detection sensor 54 is a laser sensor and detects the position of the tilter of the wafer W.

The two processing portions 16A and 16B are arranged in parallel with the front portion of the wafer chamfering device 10, and each of them executes all processing of the outer peripheral chamfering of the wafer W, that is, from rough processing to finishing processing. The processed portions 16A and 16B have the same configuration as each other, and include a wafer feeding device 60 and an outer peripheral grinding device 62.

The ori-fla polishing unit 18 finishes the ori-fla portion of the wafer W. The ori-fla polishing unit 18 has a wafer feeding device 70 and an ori-fla polishing unit 72. The wafer feeder 70 sucks and holds the wafer W in the front-rear direction (Y-axis direction), the left-right direction (X-axis direction), the vertical direction (Z-axis direction), and the rotation direction around the central axis (θ-axis). It has a movable chuck table 74. The ori-fla polishing unit 72 includes an ori-fla polishing head 76 for finishing (finish polishing) the ori-fla portion.

The cleaning unit 20 cleans the wafer W after chamfering, and while rotating the wafer W held by the cleaning table 82, the cleaning liquid is sprayed onto the surface of the wafer W to cause stains adhering to the surface of the wafer W. The spin cleaning device 80 is provided for peeling and removing the wafer. The post-measurement unit 22 measures the diameter of the chamfered wafer W, and has a diameter measuring device 84 for measuring the diameter of the wafer W and a measuring table 86 for holding the wafer W and rotating and moving it up and down.

The transfer unit 24 transfers the wafer W to each portion of the wafer chamfering device 10, and includes a grinding transfer unit 100, an Orifra Seiken transfer unit 102, a cleaning transfer unit 104, and a storage transfer unit 106. The grinding transfer unit 100 includes a transfer arm 114 provided on the slide blocks 112 and 112 that slide and move along the horizontal guides 110 and 110. A suction pad 116 is attached to the tip of the transfer arm 114. The transfer arm 114 can move horizontally and vertically while holding the wafer W.

The Orifra Seiken transfer unit 102, the cleaning transfer unit 104, and the storage transfer unit 106 have the same configuration as the grinding transfer unit 100, and each have a horizontal guide 110, a slide block 112, a transfer arm 114, and a suction pad 116, respectively.

Next, the configurations of the processed portions 16A and 16B, which are characteristic portions of the present invention, will be described with reference to FIG. Since the configurations of the processed portions 16A and 16B are the same, only the processed portions 16A will be described, but the same applies to the processed portions 16B.

As described above, the processing unit 16A includes a wafer feed device 60 and an outer peripheral grinding device 62. The wafer feeder 60 includes an X-axis base 121 mounted on the main body base 141, two X-axis guide rails 122, four X-axis linear guides 123, an X-axis drive composed of a ball screw and a servomotor. It has an X table 124 that is moved in the X direction of FIG. 2 by means 125. The X table 124 is moved in the Y direction in FIG. 2 by a Y-axis drive means composed of two Y-axis guide rails 126, four Y-axis linear guides 127, a ball screw (not shown) and a servomotor. The Y table 128 is incorporated.

The upper part of the Y table 128 is guided by two Z-axis guide rails 129 and four Z-axis linear guides (not shown), and is moved in the Z direction in the figure by a Z-axis drive means 130 including a ball screw and a stepping motor. Z table 131 is incorporated. A θ-axis motor 132 and a θ-spindle 133 are incorporated in the Z table 131. A wafer table 134 on which the wafer W is adsorbed and placed is attached to the θ-spindle 133.

The wafer table 134 rotates about the rotation axis CW of the wafer table in the θ direction of FIG. The transfer arm 114 shown in FIG. 1 is arranged on the upper surface of the wafer table 134, and the suction pad 116 is attached downward to the tip of the transfer arm. The suction pad 116 communicates with a vacuum source, and a wafer W to be chamfered or a trueuing grindstone (hereinafter referred to as a truer) for growing a grindstone to be chamfered is placed and fixed by suction. The wafer feeder 60 rotates the wafer W and the tourer in the θ direction of FIG. 2 and moves in the X, Y, and Z directions.

In the outer peripheral grinding device 62, an outer peripheral grindstone 152 having a plurality of grooves for outer peripheral rough grinding is attached, and the outer peripheral grindstone spindle 151 and the outer peripheral grindstone 152 are rotationally driven around the axis CH by an outer peripheral grindstone motor (not shown). It has an outer peripheral grinding wheel 154 and an outer peripheral grinding wheel 156 mounted above. An outer peripheral fine grinding wheel 155, which is a chamfering grindstone for finishing and grinding the outer periphery of the wafer W, is attached to the outer peripheral fine grinding spindle 154. The outer peripheral fine grinding wheel 155 moves to the machining position by rotating the rotary 163. The outer peripheral fine grinding wheel 155 is trounged by a tool (not shown) placed on the upper surface of the wafer table 134 or a tool (not shown) attached to the lower part of the wafer table to form an outer peripheral fine grinding groove.

The wafer W used in this embodiment is a compound semiconductor wafer sliced from an ingot of lithium tantalate (hereinafter referred to as LT) or lithium niobate (hereinafter referred to as LN), and has a thin disk shape having a diameter of about φ50 to 300 mm. I am doing. Then, the cleavage plane 211 is detected in advance by using X-ray diffraction or an optical image method. It is formed so as to have an angle with respect to the detected cleavage plane 211 so that the orientation flat 210, which is a positioning reference for the wafer W, cuts out a part of the circle. Further, the diameter D of the wafer W is accurately determined by the diameter measuring instrument 84 shown in FIG. 1 or another method. Further, the thickness t of the wafer W is also accurately obtained in advance by the thickness sensor 52 of the prealignment unit 14. Measurement and detection data such as the diameter D and thickness t of the wafer W, the relationship between the orientation flat 210 and the cleavage plane 211, etc. are stored in a storage means (not shown) provided in the control device 15 for each wafer W until the chamfering process of the wafer W is started. It is remembered in.

Next, with reference to FIGS. 2 and 3 and the following, the states up to the start of chamfering and immediately after the start of chamfering of the wafer W according to the embodiment of the present invention will be described. FIG. 3 is a diagram illustrating the movement of the wafer W after the wafer W is transferred to the wafer feeder 60 by using the grinding transfer unit 100. First, as shown in FIG. 3A, the wafer W is placed on the wafer table 134 of the wafer feeder 60 while being sucked by the suction pad 116 (see FIG. 2).

The control device 15 drives the Z axis of the wafer feed device 60 based on the diameter D of the wafer W stored in the control device 15, the positions of the cleavage planes 211 and the orientation flat 210 of the wafer W, and the thickness t of the wafer W. Drives the Z-axis drive means. Then, the peripheral portion, which is the grinding position of the wafer W, is aligned with the processing height position of the outer peripheral processing grindstone 152 or the outer peripheral fine grinding grindstone 155, and the height position of the wafer W is locked. Since the processing position heights of the wafer W are matched, when the open surface 211 of the wafer W first abuts on the outer peripheral processing grindstone 152 or the outer peripheral fine grinding grindstone 155, the relative positional relationship thereof is shown in FIG. 3 (d) described later. State, that is, the wafer W is connected to the θ-axis motor 132 until the opening surface is located on the line connecting the rotation center CW of the wafer W and the rotation center (CH) of the outer peripheral processing grindstone 152 or the rotation center of the outer peripheral fine grinding wheel 155. Rotate using (Op ₁ ). In other words, the cleavage surface 211 of the wafer W is positioned so that it is positioned perpendicular to the tangential direction of these grindstones 152 and 155 when it first abuts on the outer peripheral machining grindstone 152 or the outer peripheral fine grinding grindstone 155. FIG. 3 (b)].

After determining the circumferential position of the wafer W in this way, the rotation of the θ-axis motor 132 is locked, and the wafer W is moved in the X-axis direction by using the X-axis driving means 125 (Op ₂ ). At that time, the control device 15 accurately controls the moving distance of the wafer W in the X direction by using the diameter D of the wafer W and the outer diameter d of the outer peripheral processing grindstone 152 or the outer peripheral fine grinding grindstone 155. Therefore, it is desirable that the outer peripheral processing grindstone 152 and the outer peripheral fine grinding grindstone 155 be provided with a detection device capable of constantly detecting their outer diameter d. Alternatively, the outer diameters d of the grindstones 152 and 155 are periodically detected. When the movement in the X direction reaches a predetermined distance, the X-axis driving means 125 is locked to prevent further movement of the wafer W in the X direction [FIG. 3 (c)].

Since the approach of the wafer W to the machining position could be made in the tangential direction of the outer peripheral machining grindstone 152 or the outer peripheral fine grinding grindstone 155, the control device 15 uses a Y-axis drive means (not shown) to perform outer peripheral machining of the wafer W. It is brought close to the grindstone 152 or the outer peripheral fine grinding grindstone 155 (Op ₃ ). At this time, using the diameter D of the wafer W and the outer diameter d of the grindstones stored in the control device 15, the control device 15 opens the wafer W at the position where the wafer W first abuts on the grindstones 152 and 155. It is confirmed that the surface 211 is in a direction orthogonal to the tangential direction of the grindstones 152 and 155. Since the grindstones 152 and 155 rotate at high speed, the approach speed is reduced immediately before the wafer W abuts on the grindstones 152 and 155 to alleviate the impact of the abutment.

When the wafer W comes into contact with the outer peripheral grinding wheel 152 or the outer peripheral grinding wheel 155 [FIG. 3 (d)], the lock of the X-axis driving means 125 is released, and then chamfering along the outer peripheral shape of the wafer W is performed. Be able to do it. Further, the rotation of the locked θ-axis motor 132 is restarted. The rotation of the θ-axis motor 132 may be locked or restarted by directly turning the motor on / off or via a clutch or the like. The rotation of the θ-axis motor 132 is decelerated, and the rotation of the wafer W is orders of magnitude slower than the rotation of the grindstones 152 and 155, preventing the wafer W from being damaged starting from the cleavage surface 211. When the wafer W comes into contact with the grindstones 152 and 155, the outer peripheral chamfering process is started with predetermined grinding specifications.

FIG. 4 schematically shows a state in which grinding resistance is generated when the wafer W comes into contact with the grindstone 152 (155). It is assumed that the grindstone 152 (155) is rotating clockwise at high speed. The wafer W is rotating at a low speed ( _R0 ) in the same right direction as the rotation direction of the grindstone 152 (155). Friction force or grinding resistance F is generated at the point of the wafer W, which is both a contact point and a machining point, including a point on the cleavage plane 211. What is important here is that the grinding resistance F is a force in the direction perpendicular to the cleavage plane 211 and does not have a component parallel to the cleavage plane 211. This will be described in more detail with reference to FIG.

FIG. 5 shows, as a comparative example, a case where the wafer W abuts on the grindstone 152 (155) in a state where the cleavage surface 211 of the wafer W is inclined with respect to the direction approaching the grindstone 152 (155). It is a figure corresponding to FIG. At the contact position between the wafer W and the grindstone 152 (155), the grinding resistance F is generated in the tangential direction of the grindstone 152 (155) as in the example of FIG. As a result, at the contact portion, the grinding resistance _F generates a component force _FP in the cleavage plane 211 direction and a component force FT perpendicular to the cleavage surface 211.

By the way, although it becomes remarkable in a single crystal, even if it is a polycrystal, the cleavage plane is a plane in which the crystal is easily split along the plane, and when a force is applied in the cleavage plane direction, the crystal is easily broken. That is, the existence of the component force _FT in the cleavage plane 211 direction means that in the case of a single crystal, cleavage that extends almost straight from the plane direction to the entire surface of the wafer W starts. This causes the formation of the damaged region 215 as schematically shown in FIG. 5, and reduces the yield in the chamfering of the wafer W.

As described above, it is known that the relationship between the position of the cleavage surface 211 of the wafer W and the grindstone 152 (155) is important for improving the yield in the chamfering of the wafer W, but the fluctuation and thickness of the diameter D of the wafer W are known. It is also feared that the fluctuation of t has a greater effect on the chamfering process than the effect of the cleavage surface 211. Therefore, the influence of the diameter of the wafer W on the chamfering process will be described below with reference to FIG.

FIG. 6A is a case where the diameter D of the wafer W is a specified size, and FIG. 6B is a case where the diameter D of the wafer W is increased to (D + δ). The left side of each figure is a top sectional view of the contact portion between the wafer W and the grindstone 152 (155), and the right side is a cross-sectional view thereof. If the size of the wafer W is a specified size, the chamfered surfaces 231 and 232 of the grindstone 152 (155) make the upper and lower sides of the wafer W chamfered 221 and 222 with almost the same amount and the same shape in the thickness direction. The middle part is r-processed.

On the other hand, when the diameter of the wafer W is increased by δ, the relative height positions of the wafer W and the grindstone 152 (155) are changed to maintain the circumferential contact relationship of the wafer W. Can be chamfered. Specifically, if a wafer W having an increased diameter is machined using the chamfered surfaces 231 and 232 and the r machined surface shape of the same grindstone 152 (155), the upper side surface chamfering amount 233 and the lower side surface chamfering amount 234 and theirs are processed. Although the shapes are not almost the same, the cleavage plane 211 can be maintained in a direction perpendicular to the tangential direction of the grindstone rotation. If the specified wafer is machined in the same state as the specified wafer without considering the amount of change in diameter, for example, if there is a diameter error of δ = 0.1 mm on a wafer with D = 50 mm, the grinding resistance in the cleavage plane direction The component force _FP of is generated by about 3% of the grinding resistance F. Even at this level, the chamfering process may cause damage from the cleavage surface 211 and reduce the yield of the chamfering process. Further, even if the thickness t changes, it can be dealt with in the same manner.

The chamfering method of the present embodiment is collectively shown in FIG. 7 by a flowchart of processing. After slicing the wafer from the ingot to make it, chamfering is started. First, the cleavage plane 211 is detected and stored for each of the LT and LN wafers W by using X-ray diffraction or an optical image method. Further, the thickness t and the diameter D of each wafer W are measured (step S710). The thickness t and diameter D of the wafer W are separately executed by the wafer chamfering device 10 having the pre-alignment unit 14 provided with the thickness sensor 52 and the rear measuring unit 22 provided with the diameter measuring device 84 together with the outer peripheral grinding device 62. You may.

Based on the detected cleavage plane 211, the olifra 210 is machined on the wafer W by an olifra processing machine (not shown) (step S720). At that time, for the above reason, the orientation flat 210 is preferably different from the plane parallel to the cleavage plane 211. More preferably, as shown in FIG. 4, the processing of the orientation flat 210 is started from the vicinity of the position where the cleavage plane 211 coincides with the radial direction of the wafer W. If the relationship between the position of the tilter and the cleavage plane is memorized, the cleavage plane 211 cannot be seen, but the subsequent processing can be visually confirmed.

Each wafer W is stored in the wafer cassette 30 of the wafer chamfering device 10, and then attached to the wafer chamfering device 10. Then, after pretreatment in the wafer chamfering apparatus, the wafer W is transferred to the chamfering processing section 16A (16B) using the grinding transfer section 100 (step S730).

Operations Op ₁ to Op ₃ for bringing the wafer W into contact with the grindstone 152 (155) are executed by operating each part of the wafer feed device 60 and the outer peripheral grinding device 62 (steps S740 to S760). That is, at the contact position between the wafer W and the grindstone 152 (155), which is the machining position, the wafer W is rotated about the θ axis so that the wafer is in contact with the grindstone 152 (step S740). At that time, the wafer W is rotated to a position where the cleavage surface 211 coincides with the line connecting the wafer W and the center of the grindstone 152 (155) at the time of contact (Op ₁ ).

Next, the wafer W is moved in the X direction by using the X-axis driving means 125 of the wafer feeding device 60 (step S750). At that time, the wafer W is moved to the contact position between the wafer W and the grindstone 152 (155), which is the processing position, by the distance in the X direction (Op ₂ ). The order of operations Op ₁ and Op ₂ in steps S740 and S750 may be reversed or simultaneous, but must be completed before the next operation Op ₃ .

The wafer W is moved in the Y direction by using the Y-axis driving means of the wafer feeding device 60 (step S760). That is, the wafer is moved so as to approach the position where the wafer W abuts on the grindstone 152 (155) from the tangential direction (Op ₃ ). At the time of this operation _Op3 , the positions of the wafer W and the grindstone 152 (155) are already controlled based on the measured values of the diameter D of the wafer W, the thickness t, and the diameter d of the grindstone 152 (155). Since the measure 15 is controlled, it is prevented that the chamfering amount of the outer peripheral surface of the wafer W becomes excessive.

Since the chamfering start position of the wafer W has been determined, chamfering is started. At the time of chamfering, the wafer W is also rotated (step S770). When the chamfering of the wafer W is continued and the position of the orifra 210 is reached, the wafer W is moved in the X direction based on the detected contact force of the wafer W with the grindstone 152 (155) (step S780). Instead of detecting the contact force, the shape of the wafer W stored in the control means 15 in advance may be used to determine the amount of movement in the X direction. Grinding is completed when the wafer W goes around.

As described above, according to the present invention, when chamfering a semiconductor wafer, the wafer is approached from the tangential direction of the rotating grindstone, and at that time, the circumference of the wafer is oriented so that the cleavage plane of the wafer is perpendicular to the approaching direction. Since the directional position is fixed, it is possible to prevent the wafer from approaching the grindstone from a direction inclined with respect to the cleavage plane, and it is possible to prevent the wafer from being damaged due to the grinding resistance component in the direction perpendicular to the cleavage plane. This makes it possible to improve the yield of the wafer during grinding. Further, even if the diameter and thickness of the wafer vary, it is only necessary to adjust the processing position height of the wafer and the grindstone according to the amount measured in advance, and chamfering of the difficult-to-cut material LT and LN wafers. However, it is possible to prevent the wafer from being damaged from the cleavage plane.

10 ... Wafer chamfering device, 12 ... Supply and recovery section, 14 ... Prealignment section, 15 ... Control device, 16A, 16B ... Machining section, 17 ... Operation panel, 19 ... Machining side, 18 ... Orifura polishing section, 20 ... Cleaning section , 22 ... rear measurement unit, 24 ... transfer unit, 30 ... wafer cassette, 32 ... cassette table, 34 ... supply and recovery robot, 36 ... transfer arm, 38 ... guide rail, 40 ... slide block, 50 ... measurement table, 52 ... Thickness sensor, 54 ... Orifura detection sensor, 60 ... Wafer feeding device, 62 ... Outer circumference grinding device, 70 ... Wafer feeding device, 72 ... Orifura polishing unit, 74 ... Chuck table, 76 ... Orifura polishing head, 80 ... Spin cleaning device , 82 ... Washing table, 84 ... Diameter measuring instrument, 86 ... Measuring table, 100 ... Grinding transfer section, 102 ... Orifura Seiken transfer section, 104 ... Cleaning transfer section, 106 ... Storage transfer section, 110 ... Horizontal guide, 112 ... Slide block, 114 ... Transfer arm, 116 ... Suction pad, 121 ... X-axis base, 122 ... X-axis guide rail, 123 ... X-axis linear guide, 124 ... X table, 125 ... X-axis drive means, 126 ... Y-axis guide Rail, 127 ... Y-axis linear guide, 128 ... Y table, 129 ... Z-axis guide rail, 130 ... Z-axis drive means, 131 ... Z table, 132 ... θ-axis motor, 133 ... θ spindle, 134 ... Wafer table, 141 ... Main body base, 151 ... Outer peripheral grind spindle, 152 ... Outer peripheral processing grind, 154 ... Outer peripheral fine grinding spindle, 155 ... Outer peripheral fine grinding grind, 156 ... Outer peripheral fine grinding motor, 163 ... Rotary, 210 ... Orifura, 211 ... Open chamfer, 215 ... Damaged area, 221 ... Upper side chamfer (amount), 222 ... Lower side chamfer (amount), 231 ... Upper side chamfer, 232 ... Lower side chamfer, 233 ... Upper side chamfer, 234 ... Lower Chamfer amount, CH ... axis, CW ... wafer table rotation axis, _D ... wafer diameter, d ... grindstone diameter, _F ... force, FT ... tangential component force, FP ... component force parallel to the open surface, Op ₁ to Op ₃ ... Operation, r ... Chamfering part, R ... Rotation, t ... Wafer thickness, W ... Wafer, δ ... Diameter error

Claims (2)

A chamfering device that chamfers the outer peripheral portion of a semiconductor wafer formed by slicing from an ingot.
A grindstone for chamfering the outer peripheral portion of the wafer,
A motor and a spindle for driving the grindstone to rotate,
A wafer feeder that holds the wafer and moves the wafer in the X, Y, and Z directions.
A storage means for storing data on the diameter, thickness and cleavage plane of the wafer, and
A control device that controls the wafer feeder and
Equipped with
When the grindstone comes into contact with the wafer for the first time, the control device opens the wafer on a line connecting the rotation center of the wafer and the rotation center of the grindstone based on the data stored in the storage means. By controlling the wafer feed device to rotate the wafer until the surface is located, the cleaved surface of the wafer is positioned perpendicular to the tangential direction of the grindstone when it first abuts on the grindstone. Be ,
The wafer feeding device includes an X-axis driving means for driving the wafer in a direction orthogonal to the tangential direction of the grindstone and a Y-axis driving means for driving the wafer in the tangential direction of the grindstone.
The control device is a wafer chamfering device, characterized in that the wafer is brought into close contact with the grindstone from the tangential direction of the rotating grindstone by the Y-axis driving means . The control device controls the wafer to be moved in a direction orthogonal to the tangential direction by using the X-axis driving means before controlling the wafer to be brought into close contact with the grindstone. The wafer chamfering device according to claim 1 , wherein the wafer approaches the grindstone from a tangential direction.

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