JP2011108950A - Method of manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve throughput by preventing the cracking and chipping of a semiconductor wafer and lengthening a lifetime of a grindstone when continuously performing chamfering processing on end surfaces of a plurality of semiconductor wafers. <P>SOLUTION: In the method of manufacturing a semiconductor device, a semiconductor wafer 1 is adsorbed by a stage 5 with its back surface side facing downward and the stage is rotated about the center of the semiconductor wafer 1 as a center axis of the rotation. Furthermore, an end surface grindstone 10 is rotated about the center of the end surface grindstone 10 as a center axis of the rotation with the center axis being set in a direction substantially perpendicular to the direction of the center axis of the rotation of the semiconductor wafer 1. Then, the end surface grindstone 10 is made to come into contact with an end surface 3 of the semiconductor wafer 1 by moving the end surface grindstone 10 in the longitudinal direction while moving the semiconductor wafer 1 in the transverse direction, so that an oxide film 6 formed on the end surface 3 of the semiconductor wafer 1 is ground. Subsequently, in a similar manner as the end surface grindstone 10, an end surface grindstone 11 is rotated so that the end surface 3 of the semiconductor wafer 1 is ground into a desired end surface shape. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor device for manufacturing a thin semiconductor device having a small device thickness.

  Conventionally, in order to maintain or improve the performance of a semiconductor element, a method of reducing the thickness of a semiconductor wafer serving as a substrate has been proposed. FIG. 18 is a flowchart showing a conventional method for manufacturing a semiconductor device. As shown in FIG. 18, first, a front surface element structure such as an integrated circuit is formed on the front surface of a semiconductor wafer (step S101), and a protective film is formed thereon (step S102). Next, a protective tape is applied to the front surface of the semiconductor wafer (step S103), the back surface of the semiconductor wafer is ground to a predetermined thickness (step S104), and etching or the like is performed on the ground surface (step S105). In this way, the semiconductor wafer is thinned.

  Next, an electrode is formed on the back surface of the semiconductor wafer (step S106), inspections such as characteristic inspection, appearance inspection, and reliability test are performed (step S107), and dicing is performed on individual chips (step S108). In this way, the semiconductor device is completed. Note that step S107 may be performed after step S108.

  FIG. 19 is a cross-sectional view showing the shape of a conventional thinned semiconductor wafer. As shown in FIG. 19, the semiconductor wafer 1 ground and thinned from the back surface side in steps S103 to S105 of FIG. 18 has a sharp knife edge shape on the end surface 31. For this reason, when the semiconductor wafer 1 is stored in the wafer carrier, or when the semiconductor wafer 1 is transported in the apparatus or between the apparatuses, the end surface 31 of the semiconductor wafer 1 comes into contact with a part of the wafer carrier or the apparatus, There is a problem that cracking occurs. In addition, there is a problem that the electrical characteristics of the device are deteriorated because the fragments generated by the chipping and cracking pierce the front surface element structure 2. Furthermore, if a piece pierces the suction table that holds the semiconductor wafer 1, the semiconductor wafer 1 that is held thereafter is also damaged, and the electrical characteristics of the plurality of semiconductor wafers 1 continuously deteriorate. There's a problem.

  As a means for solving such a problem, in the conventional method of manufacturing a semiconductor device shown in FIG. 18, the semiconductor wafer is either simultaneously with, before or after the step of grinding the back surface of the semiconductor wafer (step S104). There has been proposed a method of chamfering the end face of each of them (see, for example, Patent Document 1 and Patent Document 2 below).

  20 or 21 is a cross-sectional view showing the chamfering of the first conventional example or the second conventional example. As shown in FIG. 20, in the first conventional example, the back surface side of the semiconductor wafer 1 with the protective tape 4 affixed to the front surface is held down on the stage 5 and the center of the semiconductor wafer 1 is rotated. For example, the center axis is rotated as indicated by an arrow R3. Further, a grindstone having a groove on the side surface (hereinafter referred to as a groove-type grindstone) 20 that matches the finished shape of the end face 32 of the semiconductor wafer 1 is used as the center axis of rotation. Is rotated in the direction parallel to the central axis of rotation of the semiconductor wafer 1, for example, as indicated by an arrow R4. Then, the end face of the rotated semiconductor wafer 1 is moved as indicated by an arrow D3, for example, until it contacts the side surface of the rotated groove-type grindstone 20 within the front surface of the semiconductor wafer 1, Grinding is performed so that the end face 32 of the semiconductor wafer 1 has a finished shape.

  Further, as shown in FIG. 21, a grindstone having a trapezoidal cross section (hereinafter referred to as a trapezoidal grindstone) 21 is used with the center of the trapezoidal grindstone 21 as a central axis of rotation, and this central axis is used as the rotation of the semiconductor wafer 1. In a direction parallel to the central axis, for example, rotation is performed as indicated by an arrow R6. Then, for example, as indicated by an arrow D4 until the end face 33 of the semiconductor wafer 1 rotated as indicated by an arrow R5 contacts the side surface of the trapezoidal grindstone 21 rotated within the front surface of the semiconductor wafer 1. It grinds so that end face 33 may become an inclined surface.

  Furthermore, a method has been proposed in which a grindstone for grinding from the back side of a semiconductor wafer is used to grind the end surface of the semiconductor wafer in order to reduce the thickness of the semiconductor wafer. In this case, the semiconductor wafer is inclined so that the end surface of the semiconductor wafer is brought into contact with the grindstone, and the end surface is ground so as to be an inclined surface.

  By these methods, it is possible to remove the knife edge shape on the end face of the thinned semiconductor wafer and prevent cracking or chipping of the semiconductor wafer. However, generally, in the step of forming a circuit pattern on a semiconductor wafer, heat treatment, photolithography, etching, or the like is repeatedly performed on the surface of the semiconductor wafer. For this reason, an oxide film is formed on the surface of the semiconductor wafer, or a residue of the treatment film remains.

  When the end face of such a semiconductor wafer is repeatedly ground using the above-described chamfering technique, an oxide film (not shown) formed on the surface of the semiconductor wafer adheres to the surface of the grindstone, and the grindstone is clogged. It becomes easy to do. In addition, the grinding accuracy of the grindstone is lowered, and a desired end face shape cannot be obtained. When the end face of the semiconductor wafer is further ground, an excessive load is applied to the end face of the semiconductor wafer, and the semiconductor wafer is chipped and cracked.

  As a method for solving the above-described problems, the end surface of a semiconductor wafer is ground using a grindstone having a larger abrasive grain diameter (hereinafter referred to as grain size) than a grindstone that causes chipping or cracking in a semiconductor wafer. Methods for doing this are known. By grinding using a grindstone containing a larger grain size, it is possible to reduce the amount of oxide film and other debris (hereinafter referred to as grinding debris) adhering to the grindstone surface during grinding. Clogging can be prevented. However, if the grain size of the abrasive grains is excessively increased, defects (hereinafter referred to as chipping) are generated in the region where the end face of the semiconductor wafer has been chamfered, and the size thereof is increased. If the chipping size of the semiconductor wafer becomes large, the wafer may be chipped or cracked due to chipping of the semiconductor wafer after the semiconductor wafer is thinned and the back surface of the semiconductor wafer is flattened by etching. Arise. Here, the chipping size is the length of chipping generated in the direction parallel to the central axis of the semiconductor wafer in the chipping generated on the end face of the semiconductor wafer.

  To prevent clogging of the grindstone so that the chipping size of the semiconductor wafer does not increase, adjust the amount of abrasive grains exposed on the grindstone surface or remove worn abrasive grains or binding materials. The method of (dressing) is effective. Dressing can remove worn abrasive grains and excess binding material on the surface of the grindstone, and can prevent clogging of the grindstone. Moreover, since the abrasive grains that are not worn on the surface of the grindstone can be exposed, the grinding accuracy of the grindstone can be maintained. Thereby, the stable end surface shape can be obtained and the crack and chipping of the semiconductor wafer can be prevented.

  As an apparatus for performing such dressing, a grindstone pressed against a wafer to be ground, a motor that rotates the grindstone relative to the wafer, an electric quantity detector that detects an electric quantity consumed by the motor, and There has been proposed an apparatus including an instruction unit that instructs execution of dressing on a grindstone when the amount of electricity exceeds a reference value (for example, see Patent Document 3 below).

Japanese Patent Laid-Open No. 08-037169 JP-A-11-333680 JP 2007-331043 A

  However, with the technique of Patent Document 3 described above, the grindstone surface is ground by performing a process for removing clogging of the grindstone such as dressing (hereinafter referred to as dressing). For this reason, compared with the case where dressing is not performed, the reduction of the grindstone is accelerated, and the life of the grindstone is shortened. In addition, the processing capability (hereinafter referred to as throughput) for manufacturing a semiconductor device is reduced by the time for detecting clogging of the grindstone and the time for performing dressing.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor device manufacturing method capable of preventing a semiconductor wafer from being cracked or chipped in order to solve the above-described problems caused by the prior art. It is another object of the present invention to provide a method for manufacturing a semiconductor device that can extend the life of a grindstone. It is another object of the present invention to provide a method for manufacturing a semiconductor device that can improve throughput.

  In order to solve the above-described problems and achieve the object, the semiconductor device manufacturing method according to the first aspect of the present invention has the following characteristics. First, the first oxidation for removing the oxide film formed on the surface of the end surface of the semiconductor wafer by rotating the semiconductor wafer and the first grindstone including coarse abrasive grains that discharge a large amount of ground scraps to contact each other. A film removal process is performed. Next, the semiconductor wafer and a second grindstone containing abrasive grains having a diameter smaller than that of the first grindstone are rotated so that the oxide film is formed by the first oxide film removing step of the semiconductor wafer. A first chamfering process for chamfering the removed end face is performed.

  According to a second aspect of the present invention, there is provided a method for manufacturing a semiconductor device according to the first aspect, wherein the first oxide film removing step rotates the center of the semiconductor wafer as a central axis of rotation. Using the center of the first grindstone as the central axis of rotation, the center axis of rotation of the first grindstone is rotated in a direction substantially perpendicular to the direction of the central axis of rotation of the semiconductor wafer. In the first chamfering step, the direction of the central axis of rotation of the second grindstone is substantially perpendicular to the direction of the central axis of rotation of the semiconductor wafer, with the center of the second grindstone being the central axis of rotation. And rotating.

  According to a third aspect of the present invention, there is provided a method for manufacturing a semiconductor device according to the first or second aspect, wherein the first grindstone is clogged with the oxide film removed in the first oxide film removal step. Abrasive grains that do not occur are included.

  According to a fourth aspect of the present invention, there is provided a method for manufacturing a semiconductor device according to any one of the first to third aspects, wherein the first grindstone has a larger diameter than abrasive grains having a grain size of # 1000. It is a whetstone containing the abrasive grain which has.

  According to a fifth aspect of the present invention, in the semiconductor device manufacturing method according to the first aspect, the first grindstone is a metal bond grindstone, a resin bond grindstone, or a vitrified grindstone. It is characterized by that.

  A semiconductor device manufacturing method according to a sixth aspect of the present invention is the method according to any one of the first to fifth aspects, wherein the second grindstone is the first oxide film removing step of the semiconductor wafer. The end face from which the oxide film has been removed is a grindstone containing fine abrasive grains that do not cause chipping.

  According to a seventh aspect of the present invention, there is provided a method for manufacturing a semiconductor device according to any one of the first to sixth aspects, wherein the second grindstone has a diameter equal to or smaller than that of abrasive grains having a grain size of # 1000. It is a whetstone containing the abrasive grain which has.

  According to an eighth aspect of the present invention, in the semiconductor device manufacturing method according to any one of the first to seventh aspects, the second grindstone is a resin bond grindstone.

  According to a ninth aspect of the present invention, in the semiconductor device manufacturing method according to any one of the first to sixth aspects, the second grindstone has a diameter equal to or less than that of abrasive grains having a grain size of # 2000. It is a whetstone containing the abrasive grain which has.

  According to a tenth aspect of the present invention, there is provided a semiconductor device manufacturing method according to any one of the first to sixth and ninth aspects, wherein the second grindstone is a metal bond grindstone or a vitrified grindstone. Features.

  A method for manufacturing a semiconductor device according to an invention of claim 11 is the invention according to any one of claims 1 to 10, wherein the second grindstone is before the first chamfering process is started. It is made to rotate.

  A semiconductor device manufacturing method according to the invention of claim 12 has the following characteristics. First, a second oxide film removing step is performed in which the semiconductor wafer and the third grindstone including pores are rotated so as to contact each other to remove the oxide film formed on the surface of the end face of the semiconductor wafer. Next, the rotated semiconductor wafer is brought into contact with the rotated third grindstone used in the second oxide film removing step, and the second oxide film removing step of the semiconductor wafer is performed by the second oxide film removing step. A second chamfering process for chamfering the end surface from which the oxide film has been removed is performed. At this time, in the second oxide film removing step, the center of the semiconductor wafer is rotated as a center axis of rotation, and the center of the third grindstone is used as a center axis of rotation. The direction is rotated in a direction substantially perpendicular to the direction of the central axis of rotation of the semiconductor wafer.

  According to a thirteenth aspect of the present invention, there is provided a semiconductor device manufacturing method according to the twelfth aspect of the present invention, wherein the third grindstone is not clogged with the oxide film removed in the second oxide film removal step. It contains the pores in a proportion.

  According to a fourteenth aspect of the present invention, there is provided a semiconductor device manufacturing method according to the twelfth or thirteenth aspect of the present invention, wherein the third grindstone is formed by the second oxide film removing step of the semiconductor wafer. The grindstone includes fine abrasive grains that do not cause chipping on the removed end face.

  According to a fifteenth aspect of the present invention, there is provided a semiconductor device manufacturing method according to any one of the twelfth to fourteenth aspects, wherein the third grindstone has a diameter equal to or smaller than that of abrasive grains having a grain size of # 1500. It is a whetstone containing the abrasive grain which has.

  According to a sixteenth aspect of the present invention, in the semiconductor device manufacturing method according to any one of the twelfth to fifteenth aspects, the third grindstone is a resin bond grindstone.

  According to a seventeenth aspect of the present invention, there is provided a semiconductor device manufacturing method according to any one of the twelfth to fourteenth aspects, wherein the third grindstone has a diameter equal to or smaller than that of abrasive grains having a grain size of # 2000. It is a whetstone containing the abrasive grain which has.

  Further, in the semiconductor device manufacturing method according to the invention of claim 18, in the invention according to any one of claims 12 to 14 and 17, the third grindstone is a metal bond grindstone or a vitrified grindstone. Features.

  According to the invention of each of the above-mentioned claims, after removing the oxide film formed on the end face of the semiconductor wafer by the first oxide film removing step, the end face of the semiconductor wafer is ground to a desired end face shape by the first chamfering step. To do. By using the first grindstone including abrasive grains having a larger diameter (grain diameter) than the abrasive grains having # 1000 grain size, it is possible to prevent the oxide film from being clogged in the first grindstone. For this reason, it is possible to prevent the oxide film from being clogged in the second grindstone also in the first chamfering process performed after the first oxide film removal process. Thereby, even if it continues grinding the end surface of a semiconductor wafer, it can prevent that a load is applied to the end surface of a semiconductor wafer. Therefore, it is possible to prevent the semiconductor wafer from being cracked or chipped. Further, since the clogging of the first grindstone and the second grindstone is prevented, it is not necessary to perform a process for removing clogging of the grindstone such as dressing. Thereby, compared with the case where the process for removing the clogging of a grindstone is performed, the reduction | decrease of a grindstone can be slowed and the lifetime of a 1st grindstone and a 2nd grindstone can be extended. Further, since it is not necessary to perform a process for removing clogging of the grindstone, the processing capability (throughput) for manufacturing the semiconductor device can be improved.

  Further, according to the above-described inventions of the ninth to eleventh aspects, grinding oxide such as oxide film is removed by grinding and removing the oxide film formed on the end face of the semiconductor wafer using the third grindstone including pores. It can be taken into the pores of the 3 grindstone and discharged out of the third grindstone by the self-generated action of the 3rd grindstone. For this reason, it is possible to prevent the oxide film from being clogged in the third grindstone. Thereby, even if it continues grinding the end surface of a semiconductor wafer, it can prevent that a load is applied to the end surface of a semiconductor wafer. Therefore, it is possible to prevent the semiconductor wafer from being cracked or chipped.

  According to the method for manufacturing a semiconductor device according to the present invention, it is possible to prevent the semiconductor wafer from being cracked or chipped. Moreover, there exists an effect that the lifetime of a grindstone can be extended. In addition, there is an effect that the throughput can be improved.

1 is a cross-sectional view showing a structure of a semiconductor device according to a first embodiment; FIG. 3 is a diagram showing a method for manufacturing the semiconductor device according to the first embodiment. FIG. 3 is a diagram showing a method for manufacturing the semiconductor device according to the first embodiment. 10 is a flowchart illustrating a method for manufacturing a semiconductor device according to a third embodiment; It is a characteristic view which shows the relationship between the particle size of the grindstone for end surface grinding, and the chipping size of a semiconductor wafer. It is a characteristic view which shows the relationship between the particle size of the grindstone for end face grinding, and the finishing height of a semiconductor wafer. It is a characteristic view which shows the relationship between the particle size of the grindstone for end face grinding, and the finishing height of a semiconductor wafer. It is a characteristic view which shows the relationship between the processing number of a semiconductor wafer, and the finishing height of a semiconductor wafer. It is a characteristic view which shows the relationship between the binding material of the grindstone for end face grinding, and the chipping size of a semiconductor wafer. It is the conceptual diagram which showed the surface of the grindstone for end surface grinding typically (before use). It is the conceptual diagram which showed the surface of the grindstone for end surface grinding typically (before use). It is the conceptual diagram which showed the surface of the grindstone for end surface grinding typically (before use). It is the conceptual diagram which showed the surface of the grindstone for end surface grinding typically (before use). It is the conceptual diagram which showed the surface of the grindstone for end surface grinding typically (after use). It is the conceptual diagram which showed the surface of the grindstone for end surface grinding typically (after use). It is the conceptual diagram which showed the surface of the grindstone for end surface grinding typically (after use). It is the conceptual diagram which showed the surface of the grindstone for end surface grinding typically (after use). It is a flowchart shown about the manufacturing method of the conventional semiconductor device. It is sectional drawing shown about the shape of the conventional semiconductor wafer thinned. It is sectional drawing shown about the chamfering of a 1st prior art example. It is sectional drawing shown about the chamfering of a 2nd prior art example.

  Exemplary embodiments of a method for manufacturing a semiconductor device according to the present invention will be explained below in detail with reference to the accompanying drawings. Note that, in the following description of the embodiments and all the attached drawings, the same reference numerals are given to the same components, and duplicate descriptions are omitted.

(Embodiment 1)
FIG. 1 is a cross-sectional view illustrating the structure of the semiconductor device according to the first embodiment. As shown in FIG. 1, in the semiconductor device according to the first embodiment, the end surface 3 of the thinned semiconductor wafer 1 does not have a knife edge shape. That is, the end surface 3 of the semiconductor wafer 1 has a shape in which a corner is ground at a grinding angle θ from the surface on the back surface side while leaving the height h2 from the front surface side. The surface of the semiconductor wafer 1 (excluding the ground surface) is repeatedly subjected to heat treatment, photolithography, etching and the like for forming the surface element structure 2 on the front surface of the semiconductor wafer 1 many times. By being performed, it is covered with an oxide film or a residue of the treatment film (hereinafter referred to as oxide film 6).

  2 and 3 are diagrams sequentially illustrating the method of manufacturing the semiconductor device according to the first embodiment. 2 is a plan view showing the method of manufacturing the semiconductor device according to the first embodiment, and the lower figure is a sectional view showing a sectional structure taken along the cutting line AA ′ in the upper figure. It is. 2 is the same as the sectional view shown in the lower diagram of FIG. 2, although the sectional structure taken along the cutting line B-B ′ in the upper diagram of FIG. First, as shown in FIG. 2, the front surface element structure 2 is formed on the front surface of the semiconductor wafer 1, and a protective member is attached to the front surface side of the semiconductor wafer 1. The protective member may be a protective tape or a liquid resin applied and cured. Here, the protective tape 4 will be used for explanation.

  Next, the back surface side of the semiconductor wafer 1 is faced down and sucked onto the stage 5, and the center of the semiconductor wafer 1 is rotated with the center axis of rotation as indicated by an arrow R1, for example. Moreover, the grindstone 10 for 1st end surface grinding is rotated in the direction which passes the front surface side and back surface side of the semiconductor wafer 1, for example. That is, for the first end grinding wheel 10, for example, as indicated by an arrow R 2, the center of the first end grinding wheel 10 is the center axis of rotation, and this center axis is substantially the direction of the center axis of rotation of the semiconductor wafer 1. Rotate in a vertical direction (hereinafter referred to as a first rotation process). The first rotation step may be performed after the semiconductor wafer 1 and the first end surface grinding wheel 10 are brought into contact with each other. The first end grinding wheel 10 corresponds to a first grinding wheel.

  Here, the direction of rotation of the first end surface grinding wheel 10 is preferably the direction from the back surface side of the semiconductor wafer 1 toward the front surface side. The reason is that if the direction of rotation of the first end grinding grindstone 10 is the direction from the front side to the back side of the semiconductor wafer 1, the knife edge-shaped tip portion is moved to the inside of the semiconductor wafer 1. A force is applied by the rotation of the first end surface grinding wheel 10 toward the semiconductor wafer 1 and a load is applied to the semiconductor wafer 1. This is because the semiconductor wafer 1 may be broken or chipped.

  Further, the shape of the first end surface grinding wheel 10 may be, for example, a disk shape or a ring shape. As a ring-shaped grindstone, for example, there is one in which a ring-shaped grindstone is fixed to a metal frame. Suitable conditions for the first end grinding wheel 10 will be described later.

  Next, while the semiconductor wafer 1 is moved in the horizontal direction, for example, as indicated by an arrow D1, the first end grinding grindstone 10 is moved in the vertical direction, for example, as indicated by an arrow D2. Then, the end face 3 of the semiconductor wafer 1 is ground by bringing the first end face grinding wheel 10 into contact with the end face 3 of the semiconductor wafer 1. Through this step, the oxide film 6 formed on the surface of the end face 3 of the semiconductor wafer 1 is removed. This step corresponds to the first oxide film removal step.

  In the first oxide film removing step, for example, the central axis of rotation of the first end grinding wheel 10 is set at a position lower than at least the back surface side of the semiconductor wafer 1. Then, by adjusting the distance by which the semiconductor wafer 1 is moved in the lateral direction, from the front surface side of the region of the end surface 3 of the semiconductor wafer 1 that remains without being ground when the end surface 3 of the semiconductor wafer 1 is ground. H1 (hereinafter referred to as the first finishing height) is adjusted. In other words, as the distance moved in the lateral direction of the semiconductor wafer 1 is increased, the region ground by the first end surface grinding wheel 10 from the back surface side of the end surface 3 of the semiconductor wafer 1 is increased. Get smaller.

  In the first oxide film removing step, the grinding angle of the end surface 3 of the semiconductor wafer 1 is adjusted by adjusting the distance by which the first end surface grinding grindstone 10 is moved in the vertical direction. That is, as the distance for moving the first end surface grinding wheel 10 in the vertical direction is increased, the position of the semiconductor wafer 1 in contact with the first end surface grinding wheel 10 becomes the position of the semiconductor wafer 1 of the first end surface grinding wheel 10. Since it approaches the apex in a direction substantially perpendicular to the front surface and the angle of the contact surface becomes gentle, the grinding angle θ becomes gentle.

  Next, the second end grinding wheel 11 is rotated, for example, in the same manner as the first end grinding wheel 10. That is, for the second end grinding wheel 11, for example, as indicated by an arrow R 3, the center of the second end grinding wheel 11 is set as the central axis of rotation, and this central axis is substantially the direction of the central axis of rotation of the semiconductor wafer 1. Rotate in a vertical direction (hereinafter referred to as a second rotation process). The order of starting the second rotation process is not limited to this, and may be performed until the process of grinding the semiconductor wafer 1 using the second end face grinding wheel 11 described later is started. In addition, the second rotation process may be performed after the semiconductor wafer 1 and the second end surface grinding grindstone 11 are brought into contact with each other. The second end grinding wheel 11 corresponds to a second grinding wheel.

  Here, the direction of rotation of the second end grinding wheel 11 is the same as that of the first end grinding wheel 10. The reason is the same as that of the first end grinding wheel 10. The shape of the second end grinding wheel 11 is the same as that of the first end grinding wheel 10. Suitable conditions for the second end grinding wheel 11 will be described later.

  Next, while the semiconductor wafer 1 is moved in the lateral direction as shown by an arrow D1, for example, the second end grinding wheel 11 is omitted as shown by an arrow D2 like the first end grinding wheel 10 although not shown. Move vertically. Then, the end face 3 of the semiconductor wafer 1 is ground by bringing the second end face grinding wheel 11 into contact with the end face 3 of the semiconductor wafer 1. By this step, the end surface 3 of the semiconductor wafer 1 from which the oxide film 6 has been removed by the first oxide film removing step is ground until a desired end surface shape is obtained. This process corresponds to a first chamfering process.

  In the first chamfering process, for example, the center axis of rotation of the second end grinding wheel 11 is set to a position lower than at least the position of the upper end of the region ground by the first oxide film removal process. Then, by adjusting the distance by which the semiconductor wafer 1 is moved in the lateral direction, the end surface of the semiconductor wafer 1 from the front surface side of the region that remains without being ground when the end surface 3 of the semiconductor wafer 1 is ground. The height h2 (hereinafter referred to as the second finishing height) is adjusted. That is, as in the first oxide film removing step, as the distance moved in the lateral direction of the semiconductor wafer 1 is increased, the region ground by the second end surface grinding wheel 11 from the back surface side of the end surface 3 of the semiconductor wafer 1 is increased. As a result, the second finishing height h2 decreases.

  In the first chamfering process, the grinding angle of the end face 3 of the semiconductor wafer 1 is adjusted by adjusting the distance by which the second end face grinding grindstone 11 is moved in the vertical direction. That is, as the distance for moving the second end surface grinding wheel 11 in the vertical direction is increased, the position of the semiconductor wafer 1 in contact with the second end surface grinding wheel 11 of the semiconductor wafer 1 of the second end surface grinding wheel 11 is increased. Since it approaches the apex in a direction substantially perpendicular to the front surface and the angle of the contact surface becomes gentle, the grinding angle θ becomes gentle. The grinding angle of the end face 3 of the semiconductor wafer 1 when grinding with the second end face grinding wheel 11 may be the same as the grinding angle of the end face 3 of the semiconductor wafer 1 when grinding with the first end face grinding grindstone 10, May be different.

  The first end face grinding wheel 10 is preferably a grindstone including abrasive grains (coarse abrasive grains) having a diameter (hereinafter referred to as grain size) larger than that of # 1000 grain size. The reason is that it is possible to prevent clogging of scraps such as the ground oxide film 6 in the first end face grinding wheel 10. Here, the particle size corresponding to the particle size of the abrasive grains is, for example, a range described in a table of abrasive particle size (bonded abrasive grain sizes) defined in JIS (Japanese Industrial Standard) R6001: 1998. (Hereinafter, the same applies to other abrasive grains).

  Moreover, it is desirable that the first end face grinding wheel 10 further satisfies the following conditions. When the grain size of the first end face grinding grindstone 10 is too large (the grain is too coarse), the chipping size of the semiconductor wafer becomes large when contacting the end face 3 of the semiconductor wafer 1. In this case, as described above, after the back surface of the semiconductor wafer 1 is flattened by etching, there is a possibility that wafer chipping or cracking due to chipping of the semiconductor wafer occurs. Therefore, the first end face grinding wheel 10 is a grindstone containing abrasive grains that are coarse enough to suppress the chipping size of the semiconductor wafer so that the wafer chipping and cracking due to chipping do not occur in the semiconductor wafer 1. Is desirable.

  Moreover, the 1st end surface grinding grindstone 10 is good in any of a metal bond grindstone, a resin bond grindstone, and a vitrified grindstone, for example. Desirably, the 1st end surface grinding stone 10 is a resin bond grindstone. The reason is that when a resin bond grindstone is used as the first end face grinding grindstone 10, the surface of the semiconductor wafer 1 can be ground more flatly than a metal bond grindstone or vitrified grindstone having the same grain size. Because. The resin bond grindstone makes more contact with the grinding surface than the metal bond grindstone or vitrified grindstone due to the elastic deformation of the resin bond as a binder during grinding. For this reason, the resin bond grindstone has a weaker force for cutting the ground surface than the metal bond grindstone or the vitrified grindstone. Thereby, the resin bond grindstone can grind the grinding surface more flatly than the metal bond grindstone or the vitrified grindstone. Therefore, when a metal bond grindstone or a vitrified grindstone is used as the first end face grinding grindstone 10, the particle size of the metal bond grindstone or vitrified grindstone should be several tens of percent smaller than that of the resin bond grindstone. Good.

  Moreover, the content rate (concentration) of the abrasive grains contained in the first end surface grinding wheel 10 may be set to, for example, a concentration degree 125 in which more abrasive grains are included than the concentration degree 100, for example. The degree of concentration of 100 means that the volume ratio of the abrasive grains contained in the grindstone is 25% with respect to the grindstone. By setting the first end face grinding wheel 10 to a high concentration level, the life of the first end face grinding wheel 10 can be extended. On the other hand, the grinding accuracy of the first end surface grinding wheel 10 can be improved by setting the first end surface grinding wheel 10 to a low concentration level.

  The second end surface grinding wheel 11 includes abrasive grains having a particle size smaller than that of the first end surface grinding wheel 10. Thereby, the end surface 3 of the semiconductor wafer 1 ground in the first oxide film removing step can be ground more flatly. The second end face grinding wheel 11 is preferably a grindstone including abrasive grains (fine abrasive grains) having a grain size of # 1000 or less. This is because the chipping size of the semiconductor wafer can be reduced.

  Further, it is desirable that the second end surface grinding wheel 11 further satisfies the following conditions. When the grain size of the second end face grinding grindstone 11 is too small (it is an abrasive grain that is too fine), it takes time to obtain a desired end face shape, and thus the processing capability (throughput) for manufacturing a semiconductor device is high. It will decline. Therefore, it is desirable that the second end surface grinding stone 11 is a grindstone containing fine abrasive grains to such an extent that the throughput does not decrease. Further, the second end surface grinding wheel 11 is, for example, any one of a metal bond grindstone, a resin bond grindstone, and a vitrified grindstone. The effect of using these grindstones is the same as that of the first end face grinding grindstone 10. Further, when a metal bond grindstone or a vitrified grindstone is used as the second end face grinding grindstone 11, the second end face grindstone 11 is an abrasive grain having a grain size equal to or smaller than # 2000 grain size (fine grinding). It is desirable that the grindstone includes a grain). The reason is that the metal bond grindstone and the vitrified grindstone have less elastic deformation of the binding material than the resin bond grindstone, so that the grinding surface becomes rougher and the chipping size becomes larger than the resin bond grindstone.

  It is desirable that the first end surface grinding wheel 10 and the second end surface grinding wheel 11 are always installed. The reason is that the time for alternately replacing the first end surface grinding wheel 10 and the second end surface grinding wheel 11 can be shortened when performing the first rotation step and the second rotation step. Thereby, throughput can be improved. Moreover, by always installing the 1st end surface grinding grindstone 10 and the 2nd end surface grinding grindstone 11, the 2nd rotation process can be performed before the 1st chamfering process process is started. As a result, the first chamfering process can be smoothly started simultaneously with the completion of the first oxide film removing process, and the throughput can be further improved.

  The first finishing height h1 is such that the oxide film 6 that remains without being ground on the end surface 3 of the semiconductor wafer 1 after the first oxide film removing step does not clog the second end grinding wheel 11 used in the first chamfering step. It is preferable that the height remains in the extent. In addition, the second finishing height h2 is a value smaller than the thickness remaining without being ground when the entire back surface side of the semiconductor wafer 1 is ground.

  Here, when the protective tape 4 is affixed to the entire front surface of the semiconductor wafer 1, the second finishing height h2 is set so that the second end grinding grindstone 11 does not contact the protective tape 4. And adjust the grinding angle. In addition, when the protective tape 4 is affixed inside the outer end on the front surface side of the semiconductor wafer 1, both the front surface and the back surface of the semiconductor wafer 1 can be ground into an arbitrary shape.

  By performing such a process, as shown in FIG. 3, the height from the front surface side of the region remaining on the end surface 3 of the semiconductor wafer 1 without being ground is the second finishing height h2, and grinding is performed. A semiconductor wafer 1 having an angle θ is formed. Then, by grinding the entire back surface of the semiconductor wafer 1 to a desired thickness and thinning the semiconductor wafer 1, the semiconductor device shown in FIG. 1 is completed.

  As described above, according to the first embodiment, after the oxide film 6 formed on the end surface 3 of the semiconductor wafer 1 is removed by the first oxide film removing process, the semiconductor wafer 1 is processed by the first chamfering process. The end face 3 is ground into a desired end face shape. At this time, the first end surface grinding wheel 10 used in the first oxide film removal step is a grindstone that satisfies the above-described conditions, thereby preventing the oxide film 6 from being clogged in the first end surface grinding wheel 10. Can do. For this reason, also in the 1st chamfering process performed after the 1st oxide film removal process, it can prevent clogging with the oxide film 6 in the grindstone 11 for 2nd end surface grinding. Thereby, even if it continues grinding the end surface 3 of the semiconductor wafer 1, it can prevent that a load is applied to the end surface 3 of the semiconductor wafer 1. FIG. Therefore, cracking and chipping of the semiconductor wafer 1 can be prevented. In addition, since the clogging of the first end surface grinding wheel 10 and the second end surface grinding wheel 11 is prevented, it is not necessary to perform a process for removing clogging of the grinding stone such as dressing. Thereby, compared with the case where dressing etc. are performed, the reduction | decrease of a grindstone can be slowed and the lifetime of the grindstone 10 for 1st end surface grinding and the grindstone 11 for 2nd end surface grinding can be extended. In addition, since it is not necessary to perform dressing or the like, the processing capability (throughput) for manufacturing the semiconductor device can be improved.

(Embodiment 2)
In the method of manufacturing a semiconductor device according to the first embodiment (see FIG. 2), a semiconductor using only a third end grinding grindstone including pores instead of the first end grinding grindstone and the second end grinding grindstone The end face of the wafer may be ground. The third end grinding wheel corresponds to the third grinding wheel. Other semiconductor device manufacturing methods are the same as those in the first embodiment.

  In the method of manufacturing a semiconductor device according to the second embodiment, as in the first embodiment, the semiconductor wafer having the front surface element structure is attracted to the stage with the back surface side facing down (see FIG. 2). . The rotation direction of the semiconductor wafer is the same as in the first embodiment. The structure of the semiconductor device is the same as that in Embodiment 1 (see FIG. 1).

  Next, the third end surface grinding wheel is rotated in the same manner as the first end surface grinding wheel of the first embodiment. That is, the third end surface grinding wheel is rotated with the center of the third end surface grinding wheel as the central axis of rotation and the central axis in a direction substantially perpendicular to the direction of the central axis of rotation of the semiconductor wafer (hereinafter, This is the third rotation step). The direction of rotation of the third end surface grinding wheel is the same as that of the first end surface grinding wheel of the first embodiment. The shape of the third end surface grinding wheel is the same as that of the first end surface grinding wheel of the first embodiment. Suitable conditions for the third end grinding wheel will be described later.

  Next, as in the first embodiment, the third end grinding grindstone is moved in the vertical direction while moving the semiconductor wafer in the horizontal direction. Then, the end face of the semiconductor wafer is ground by bringing a third end face grinding grindstone into contact with the end face of the semiconductor wafer. By this step, the oxide film formed on the surface of the end face of the semiconductor wafer is removed. This step corresponds to a second oxide film removal step. Subsequently, using the same third end grinding grindstone that is still rotated, the third end grinding grindstone is brought into contact with the end face of the semiconductor wafer in the same manner as in the second oxide film removing step. To grind. By this step, the end surface of the semiconductor wafer from which the oxide film has been removed by the second oxide film removing step is ground until the end surface has a desired shape. This process corresponds to a second chamfering process.

  The grinding angle of the end face of the semiconductor wafer is adjusted by adjusting the distance by which the third end face grinding grindstone is moved in the vertical direction, similarly to the first end face grinding grindstone of the first embodiment. Further, for example, the central axis of rotation of the third end face grinding wheel is set at a position lower than at least the back surface side of the semiconductor wafer. Then, the second finishing height is adjusted by adjusting the distance by which the semiconductor wafer is moved in the lateral direction (see FIG. 3).

  The third end face grinding grindstone may be a grindstone including pores at a porosity of 50%, for example. In addition, the third end face grinding wheel is desirably a grindstone including abrasive grains (fine abrasive grains) having a grain size equal to or smaller than # 2000. This is because it is possible to prevent clogging of scraps such as the ground oxide film in the third end surface grinding wheel. In addition, when the grain size of the third end face grinding grindstone is too small (it is an abrasive grain that is too fine), it takes time until a desired end face shape is obtained, resulting in a decrease in throughput. Therefore, it is desirable that the third end face grinding wheel is a grindstone containing fine abrasive grains to such an extent that the throughput does not decrease. Moreover, it is desirable that the third end surface grinding wheel is a grindstone containing fine abrasive grains to such an extent that chipping does not occur on the semiconductor wafer. The third end surface grinding wheel is, for example, one of a metal bond grindstone, a resin bond grindstone, and a vitrified grindstone. The effect of using these grindstones is the same as that of the first end face grinding grindstone. When a metal bond grindstone or a vitrified grindstone is used as the third end face grinding grindstone, the third end face grindstone is a grindstone containing abrasive grains having a grain size equal to or smaller than # 2000 grain size. Is desirable. The reason is the same as that of the second end grinding wheel.

  As described above, according to the second embodiment, the same effect as in the first embodiment can be obtained. In the second embodiment, the oxide film formed on the end surface of the semiconductor wafer is ground and removed using the third end surface grinding wheel including pores, so that the grinding waste such as the oxide film is removed for the third end surface grinding. It can be taken into the pores of the grindstone and discharged outside the third end face grinding grindstone by the self-generated action of the third end face grindstone. Thereby, it is possible to prevent the oxide film from being clogged in the third end face grinding wheel. Therefore, it is possible to prevent the semiconductor wafer from being cracked or chipped.

(Embodiment 3)
FIG. 4 is a flowchart illustrating the method for manufacturing the semiconductor device according to the third embodiment. FIG. 4 shows a method of chamfering the end face of the semiconductor wafer performed before or after the entire surface of the semiconductor wafer is thinned. In the third embodiment, when continuously chamfering a plurality of semiconductor wafers, the shape of the end face of the semiconductor wafer subjected to the chamfering process and the shape of the grindstone for end face grinding are measured, and the next semiconductor wafer is measured. This is a method in which chamfering is performed by feeding back the deviation between the measured value and the reference dimension when chamfering the end face.

  As shown in FIG. 4, first, the semiconductor wafer is put into a chamfering apparatus (step S1). Next, the shape of the semiconductor wafer is measured (step S2). In step S2, the thickness and diameter of the semiconductor wafer are measured. Next, the center of the semiconductor wafer is detected (step S3). Then, the semiconductor wafer is mounted on the stage by a transfer mechanism such as a transfer arm (step S4).

  Next, it is determined whether or not there is a correction value when using the same first end face grinding wheel last time. Further, it is determined whether or not there is a correction value when using the same second end surface grinding wheel (step S5). When there is no correction value in step S5 (step S5: No), the reference dimension is set as the setting condition (step S6). The reference dimension is a finished dimension of the end face of the semiconductor wafer, and is information on the finished height and the grinding angle. In Step S5, when there is no correction value, the end grinding wheel is not worn, for example, when a new first end grinding grindstone or second end grinding grindstone is used. On the other hand, when there is a correction value in step S5 (step S5: Yes), a value obtained by adding the correction value to the reference dimension is set as a setting condition (step S7). Next, the oxide film formed on the surface of the end face of the semiconductor wafer is removed based on the setting conditions of the first end face grinding wheel (step S8). Further, based on the setting condition of the second end face grinding wheel, the end face of the semiconductor wafer is ground until a desired end face shape is obtained (step S9).

  Next, it is determined whether or not grinding of the end face of the semiconductor wafer has been completed (step S10). In step S10, when the grinding is not completed (step S10: No), the process returns to step S8 and the grinding is continued. When the grinding is completed (step S10: Yes), the shape of the end face of the ground semiconductor wafer and the wear amounts of the first end face grinding wheel and the second end face grinding wheel used for grinding are measured (step). S11). In step S11, for example, the finished height and the grinding angle of the end face of the semiconductor wafer are measured by a displacement sensor, projection, image processing, a linear gauge, or the like. Further, for example, the amount of wear of the end surface grinding wheel is measured by a displacement sensor or a linear gauge, or by moving the end surface grinding wheel so as to be brought into contact with a housing, a pedestal, or the like.

  Next, the measurement value measured in step S11 is compared with the reference dimension (step S12), and a correction value is calculated (step S13). Next, the correction value calculated in step S13 is recorded in the recording unit provided in the chamfering apparatus (step S14) to be used for the chamfering process of the end face of the next semiconductor wafer, and the series of processes is completed.

  In the flowchart of FIG. 4, it is determined whether or not grinding is completed in step S <b> 10, but is not limited thereto. For example, before the grinding in step S8 or step S9 ends, the process may proceed to step S11 and the subsequent processing may be performed. In this case, the grinding of the end face is finished when the setting condition for making the end face of the semiconductor wafer into a desired end face shape is satisfied.

  Further, in the flowchart of FIG. 4, the end face of the semiconductor wafer is ground using the first end face grinding grindstone and the second end face grinding grindstone (see FIG. 2), but the present invention is not limited to this. For example, it is good also as a structure which grinds the end surface of a semiconductor wafer only using the grindstone for 3rd end surface grinding (refer Embodiment 2). In this case, the processes in step S8 and step S9 are performed using only the third end face grinding wheel.

  In the flowchart of FIG. 4, the process proceeds to step S11 every time grinding of one semiconductor wafer is completed in step S10. However, the present invention is not limited to this. For example, it is possible to wait until a predetermined number of semiconductor wafers are ground, and then proceed to step S11 after the grinding of the predetermined number of semiconductor wafers is completed. In this case, since it is not necessary to calculate a correction value for each semiconductor wafer, throughput is improved.

  As described above, according to the third embodiment, the same effects as those of the first and second embodiments can be obtained. Further, when continuously chamfering the end faces of a plurality of semiconductor wafers using the same first end grinding grindstone and the same second end grinding grindstone, the shape of the end face of each semiconductor wafer is a reference dimension. Can be. For this reason, since the shape of each semiconductor wafer becomes substantially the same, it can prevent that the shape and diameter of an end surface vary for every semiconductor wafer. Also, when grinding the end face of the semiconductor wafer based on the set condition, for example, it is not necessary to change the set condition between the start and end of the grinding of the end face of one semiconductor wafer. It becomes easy to control. This eliminates the need for a device or a program for performing complex control, thereby reducing costs.

Example 1
FIG. 5 is a characteristic diagram showing the relationship between the grain size of the edge grinding wheel and the chipping size of the semiconductor wafer. In accordance with the first embodiment described above, a semiconductor wafer having a front surface element structure was prepared. The thickness of the semiconductor wafer was 500 μm. Moreover, as the first end face grinding wheel, a grindstone containing abrasive grains having particle sizes of # 600, # 800, # 1000 and # 1500 was prepared (hereinafter referred to as a first sample to a fourth sample). Moreover, the 1st sample-the 4th sample were used as the resin bond grindstone.

  Next, according to the method for manufacturing the semiconductor device according to the first embodiment, the end surface of the semiconductor wafer was ground using the first to fourth samples, and the chipping size of the semiconductor wafer after the first oxide film removal step was measured. . In the first oxide film removing step, grinding was performed so that the first finishing height was 150 μm. The grinding angle θ was 30 °. In FIG. 5, the chipping sizes of a plurality of semiconductor wafers are measured, and the average value is calculated.

  From the results shown in FIG. 5, it was found that the chipping size of the semiconductor wafer can be reduced as the grain size of the abrasive grains is increased. Further, it has been found that when the first sample is used, the chipping size of the semiconductor wafer may be 100 μm or more. For this reason, it has been found that the chipping size of the semiconductor wafer becomes large when the grain size of the first end face grinding grindstone is too large. For example, when the standard setting of the chipping size of the semiconductor wafer is 50 μm or less, it is preferable that the first end face grinding wheel is a grindstone including abrasive grains having a grain size smaller than that of # 600 grain size. all right. On the other hand, it was found that the chipping size of the semiconductor wafer can be made smaller than about 25 μm when the third sample and the fourth sample are used. Further, as a result of examination by the inventors, it has been found that the chipping size of the semiconductor wafer can be removed by etching when it is smaller than about 25 μm. For this reason, chipping is removed by etching for flattening the back surface of the semiconductor wafer by making the second end face grinding wheel a grindstone having a grain size equal to or smaller than # 1000 grain size. Can do. In other words, by using a grindstone containing abrasive grains having a grain size of # 1000 or less as the second end face grinding grindstone, to the extent that wafer chipping and cracking due to chipping do not occur in the semiconductor wafer, It was found that the chipping size of the semiconductor wafer can be suppressed.

(Example 2)
FIG. 6 is a characteristic diagram showing the relationship between the grain size of the end grinding grindstone and the finished height of the semiconductor wafer. A semiconductor wafer was prepared in the same manner as in Example 1. Further, a semiconductor wafer whose surface is not covered with an oxide film (hereinafter referred to as a reference wafer) was prepared. As in Example 1, second to fourth samples were prepared as first end grinding wheels. A resin bond grindstone containing abrasive grains having a grain size of # 1500 was prepared as a second end face grinding grindstone.

  Next, according to the method for manufacturing the semiconductor device according to the first embodiment, the end face of the semiconductor wafer is used within the reference work time (hereinafter referred to as the total reference work time) using the same second to fourth samples. Each was ground. Thereafter, the end face of the semiconductor wafer was ground using a second end face grinding grindstone. And the difference (henceforth a finishing height difference) between the actual height of the end surface of the semiconductor wafer after grinding and the target value of the 2nd finishing height was measured. In the first chamfering process, the target value of the second finishing height was set to 100 μm. The target value of the first finishing height is the same as that in the first embodiment. That is, when a series of steps of the manufacturing method of the semiconductor device according to the first embodiment is performed and the grinding time reaches the first reference work time, or when the first finishing height of the semiconductor wafer reaches 150 μm, The first oxide film removal process is terminated, and the process proceeds to the first chamfering process. Then, when the grinding time reached the second reference work time, or when the second finished height of the end face of the semiconductor wafer reached 100 μm, the grinding of the end face of the semiconductor wafer was finished. As the first reference work time, the time required for grinding until the first finished height of the reference wafer reached 150 μm was measured. As the second reference work time, the time required for grinding until the second finished height of the reference wafer reached 100 μm was measured. The time obtained by adding the first reference work time and the second reference work time was defined as the total reference work time. In FIG. 6, the finishing height difference (0 μm) of the reference wafer is used as a reference, and the finishing height difference is indicated by minus. That is, the actual height of the end face of the semiconductor wafer after grinding is equal to the target value (100 μm) of the second finishing height, which is a positive value on the vertical axis in FIG. 6, and the finishing height, which is a negative value in FIG. This is a numerical value obtained by adding the absolute values of the differences. The number of processed semiconductor wafers (hereinafter referred to as the number of processed wafers) is three for each of the second to fourth samples. Other manufacturing methods are the same as those in the first embodiment.

  From the results shown in FIG. 6, in the grinding using the second sample, the average of the finishing height difference was 2.6 μm / sheet. In the grinding using the third sample, the average of the finished height difference was 8.5 μm / sheet. In the grinding using the fourth sample, the average of the finishing height difference was 27 μm / sheet. Thereby, in grinding using the 2nd sample and the 3rd sample, it turned out that a finishing height difference is small and the grinding accuracy of a grindstone is maintained. The reason can be assumed that the oxide film is not easily clogged in the second sample or the third sample. Thereby, in the 2nd sample and the 3rd sample, it turned out that the life of a grindstone can be extended. On the other hand, in the grinding using the fourth sample, it was found that the finishing height difference was large and the grinding accuracy of the grindstone was lowered. The reason can be assumed that the oxide film is clogged in the fourth sample. Thereby, in the 4th sample, it turned out that the life of a grindstone has fallen. Therefore, by using a grindstone containing a grain (coarse abrasive grain) having a grain size larger than that of # 1000 grain as the first end face grinding grindstone, the oxide film is clogged in the first end face grinding grindstone. It was found that it can be prevented.

(Example 3)
FIG. 7 is a characteristic diagram showing the relationship between the grain size of the grindstone for end face grinding and the finished height of the semiconductor wafer. FIG. 8 is a characteristic diagram showing the relationship between the number of processed semiconductor wafers and the finished height of the semiconductor wafer. In accordance with the second embodiment described above, a semiconductor wafer having a front surface element structure was prepared. Further, as in Example 2, a reference wafer was prepared. As the third end face grinding wheel, a grindstone containing pores and abrasive grains having a grain size of # 2000 was prepared (hereinafter referred to as a fifth sample). The fifth sample was a vitrified grindstone. For comparison, a fourth sample was prepared in the same manner as in Example 1. The fourth sample is a grindstone including abrasive grains having a larger grain size than that of the fifth sample.

  Next, according to the method for manufacturing the semiconductor device according to the second embodiment, a plurality of semiconductor wafers were ground for the total reference work time using the same fifth sample. Then, the difference (finishing height difference) between the actual height of the end face of the semiconductor wafer after grinding and the target value of the second finishing height was measured. Here, the target value of the second finishing height was set to 100 μm. That is, when a series of steps of the semiconductor device manufacturing method according to the second embodiment is performed and the grinding time reaches the total reference work time or the second finishing height of the semiconductor wafer reaches 100 μm, the semiconductor The grinding of the wafer end face was completed. The total reference work time is the same as that in the second embodiment. Other manufacturing methods are the same as those in the first embodiment.

  From the results shown in FIG. 7, in the grinding using the fifth sample, the average of the finishing height difference was 2.3 μm / sheet. In the grinding using the fourth sample, as shown in Example 1, the average of the finishing height difference was 27 μm / sheet. Further, from the results shown in FIG. 8, it was found that in the grinding using the fifth sample, the difference in the finishing height of the semiconductor wafer 1 does not substantially change even when the number of processing of the semiconductor wafer is further increased. Thus, it has been found that by using a grindstone including pores, it is possible to prevent the grinding accuracy of the grindstone from being lowered even if the grain size of the grindstone of the grindstone is set to # 2000. The reason is that by using a grindstone containing pores, the oxide film generated when grinding a semiconductor wafer is discharged together with the self-generated action of the grindstone, and the oxide film is less likely to clog the grindstone. Can do. Moreover, the chipping size of the semiconductor wafer can be reduced because the grain size of the abrasive grains of the grindstone can be set to # 2000. Further, it was found that the vitrified grindstone has a higher self-generating effect of the grindstone than the resin bond grindstone.

Example 4
FIG. 9 is a characteristic diagram showing the relationship between the bonding material of the grindstone for end face grinding and the chipping size of the semiconductor wafer. Similarly to Example 1, a semiconductor wafer 1 having a front surface element structure was prepared. Further, as end grinding wheels, grindstones containing abrasive grains having a grain size of # 600 and # 800 were prepared (hereinafter referred to as a sixth sample and a seventh sample). Two grindstones containing # 1000 abrasive grains with different concentrations were prepared (hereinafter referred to as the eighth sample and the ninth sample). The concentrations of the eighth sample and the ninth sample were 125 and 150, respectively. A grindstone containing abrasive grains having a grain size of # 1500 was prepared (hereinafter referred to as a tenth sample). Three grindstones containing abrasive grains of # 2000 grain size were prepared (hereinafter referred to as the 11th to 13th samples). Here, the 6th sample-the 11th sample were used as the resin bond grindstone. The twelfth sample and the thirteenth sample were vitrified grinding wheels. The twelfth sample and the thirteenth sample are grindstones of the same conditions from different manufacturers.

  From the results shown in FIG. 9, it was found that in the resin bond grindstone (sixth sample to eleventh sample), the chipping size was smaller as the diameter of the abrasive grains was smaller. In the eleventh sample, no chipping was confirmed on the end face of the semiconductor wafer. In addition, the vitrified grinding wheels (12th and 13th samples) containing abrasive grains of # 2000 grain size have a chipping size larger than the resin bond grinding stones (8th and 9th samples) containing abrasive grains of # 1000 grain size. It turned out that it can be made small. Moreover, it turned out that it can be set as the chipping size comparable as the resin bond grindstone (10th sample) containing the abrasive grain of # 1500. In other words, when the grinding accuracy is finer or comparable to the resin bond grindstone having a particle size of # 1000, the vitrified grindstone is a grindstone including an abrasive having a diameter equal to or smaller than that of an abrasive having a # 2000 particle size I found it necessary. Further, it is presumed that the metal bond grindstone needs to be a grindstone including abrasive grains having a diameter equal to or smaller than the abrasive grains having a grain size of # 2000, similarly to the vitrified grindstone.

(Example 5)
FIGS. 10-13 is the conceptual diagram which showed typically the surface of the grindstone for end surface grinding before use. Moreover, FIGS. 14-17 is the conceptual diagram which showed typically the surface of the grindstone for end surface grinding after use. Similarly to Example 1, a semiconductor wafer 1 having a front surface element structure was prepared. In the same manner as in Example 1, a grindstone containing abrasive grains having a grain size of # 800 was prepared as the first end face grinding grindstone (second sample). In addition, a grindstone containing abrasive grains having a grain size of # 1500 was prepared as the second end face grinding grindstone (hereinafter referred to as the 14th sample). In the same manner as in Example 3, a grindstone containing pores and abrasive grains having a particle size of # 2000 was prepared as a third end face grinding grindstone (fifth sample). For comparison, a fourth sample was prepared in the same manner as in Example 1.

  Next, in the same manner as in Example 1, a series of steps of the semiconductor device manufacturing method according to the first embodiment was performed on a plurality of semiconductor wafers using the same second sample and fourteenth sample. Similarly to Example 3, a series of steps of the method for manufacturing a semiconductor device according to the second embodiment were performed on a plurality of semiconductor wafers using the same fifth sample. As a comparison, as in Example 3, a series of steps of the method for manufacturing a semiconductor device according to the second embodiment were performed on a plurality of semiconductor wafers using the same fourth sample. The number of semiconductor wafers processed is 50 each. The grindstones shown in FIGS. 10 to 13 are a second sample, a fourteenth sample, a fifth sample, and a fourth sample that have not been used yet. The grindstones shown in FIGS. 14 to 17 are the second sample, the fourteenth sample, the fifth sample, and the fourth sample after grinding the semiconductor wafer.

  From the results shown in FIG. 10 and FIG. 14, no oxide film was observed on the surface of the second sample even after grinding a plurality of semiconductor wafers. Thereby, it turns out that it can prevent that an oxide film is clogged in the grindstone for 1st end surface grinding in the grinding using the grindstone for 1st end surface grinding. It can also be seen that the surface condition of the second sample does not change before use and after grinding. Thereby, it turned out that the grinding wheel for the 1st end face grinding can prevent that the grinding accuracy of a grinding stone falls even after grinding a plurality of semiconductor wafers.

  Further, from the results shown in FIGS. 11 and 15, no adhesion of an oxide film was observed on the surface of the fourteenth sample even after grinding a plurality of semiconductor wafers. As a result, the oxide film formed on the end face of the semiconductor wafer is removed by grinding using the first end face grinding grindstone, and thereafter contains finer abrasive grains than the first end face grinding grindstone. It has been found that even if the second end grinding wheel is used, it is possible to prevent the oxide film from being clogged in the second end grinding wheel. Further, it was found that the surface state of the 14th sample did not change before use and after grinding. Thereby, it turned out that the grinding wheel for the 2nd end face grinding can prevent that the grinding accuracy of a grindstone falls even after grinding a plurality of semiconductor wafers.

  Further, from the results shown in FIGS. 12 and 16, no adhesion of an oxide film was observed on the surface of the fifth sample even after grinding a plurality of semiconductor wafers. Thereby, it turns out that it can prevent clogging with an oxide film in the grinding wheel for 3rd end face grinding in grinding using the grinding wheel for 3rd end face grinding. It was also found that the surface condition of the fifth sample did not change before use and after grinding. Thereby, it turns out that the grinding wheel for 3rd end face grinding can prevent that the grinding accuracy of a grindstone falls even after grinding a plurality of semiconductor wafers.

  On the other hand, from the results shown in FIGS. 13 and 17, in the fourth sample, after a plurality of semiconductor wafers were ground, adhesion of an oxide film was observed on the surface thereof. For this reason, from the results shown in FIGS. 10 to 17, when grinding a semiconductor wafer with a grindstone that does not contain pores and contains too fine abrasive grains having a grain size equal to or smaller than the grain size of # 1500, In addition, it was found that the oxide film was clogged.

  In each of the above embodiments, the movement (adjustment) in the horizontal direction is performed by moving the semiconductor wafer, and the movement (adjustment) in the vertical direction is performed by moving the grindstone. However, the present invention is not limited to this. For example, contrary to the above, the movement (adjustment) in the horizontal direction may be performed by moving the grindstone, and the movement (adjustment) in the vertical direction may be performed by moving the semiconductor wafer. Alternatively, one of the semiconductor wafer and the grindstone may be rotated at a fixed position, that is, only the other of the wafer or the grindstone may be moved in the vertical and horizontal directions with the rotation axis as the fixed position.

  Moreover, the grinding of the end face of the semiconductor wafer may be performed before the grinding process of the back face of the semiconductor wafer. Here, the grinding process of the back surface of the semiconductor wafer may be moved back and forth according to other processes of the semiconductor manufacturing process. In the above-described grinding of the end face of the semiconductor wafer, an end face grinding grindstone is used. However, the present invention is not limited to this, and a grindstone for grinding the back face of the semiconductor wafer may be used for grinding the end face.

  As described above, the method for manufacturing a semiconductor device according to the present invention is useful for manufacturing a semiconductor device having a thin device thickness, and is particularly suitable for manufacturing a power semiconductor device used for a power conversion device or the like. ing.

DESCRIPTION OF SYMBOLS 1 Semiconductor wafer 2 Front surface element structure 3 End surface 4 Protection tape 5 Stage 10 Grinding wheel for end surface grinding (1st)
11 Grinding wheel for end face grinding (2nd)

Claims (18)

First oxide film removal for removing the oxide film formed on the surface of the end face of the semiconductor wafer by rotating the semiconductor wafer and the first grindstone including coarse abrasive grains that discharge a large amount of ground waste. Process,
The semiconductor wafer and the second grindstone containing abrasive grains having a smaller diameter than the first grindstone are rotated so as to contact each other, and the oxide film is removed by the first oxide film removal step of the semiconductor wafer. A first chamfering process for chamfering the finished end face;
A method for manufacturing a semiconductor device, comprising: In the first oxide film removing step, the center of the semiconductor wafer is rotated as a center axis of rotation, and the center of the first grindstone is used as a center axis of rotation. Rotate the wafer in a direction substantially perpendicular to the direction of the central axis of rotation of the semiconductor wafer,
In the first chamfering step, the center of the second grindstone is the central axis of rotation, and the direction of the central axis of rotation of the second grindstone is substantially perpendicular to the direction of the central axis of rotation of the semiconductor wafer. The method of manufacturing a semiconductor device according to claim 1, wherein the semiconductor device is rotated.   3. The method of manufacturing a semiconductor device according to claim 1, wherein the first grindstone includes abrasive grains having a roughness that does not cause clogging of the oxide film removed in the first oxide film removing step. 4. .   4. The method of manufacturing a semiconductor device according to claim 1, wherein the first grindstone is a grindstone including abrasive grains having a larger diameter than abrasive grains having a grain size of # 1000.   The method of manufacturing a semiconductor device according to claim 1, wherein the first grindstone is a metal bond grindstone, a resin bond grindstone, or a vitrified grindstone.   The said 2nd grindstone is a grindstone containing the abrasive grain of the fineness which does not produce a chipping in the end surface from which the said oxide film was removed by the said 1st oxide film removal process of the said semiconductor wafer. The manufacturing method of the semiconductor device as described in any one of 1-5.   The method for manufacturing a semiconductor device according to claim 1, wherein the second grindstone is a grindstone including abrasive grains having a diameter equal to or smaller than that of abrasive grains having a grain size of # 1000.   The method of manufacturing a semiconductor device according to claim 1, wherein the second grindstone is a resin bond grindstone.   The method for manufacturing a semiconductor device according to claim 1, wherein the second grindstone is a grindstone including abrasive grains having a diameter equal to or less than that of abrasive grains having a grain size of # 2000.   The method for manufacturing a semiconductor device according to claim 1, wherein the second grindstone is a metal bond grindstone or a vitrified grindstone.   The method of manufacturing a semiconductor device according to claim 1, wherein the second grindstone is rotated until the first chamfering process is started. A second oxide film removing step of removing the oxide film formed on the surface of the end face of the semiconductor wafer by rotating the semiconductor wafer and the third grindstone including pores in contact with each other;
The rotated semiconductor wafer is brought into contact with the rotated third grindstone used in the second oxide film removing step, and the oxide film is removed by the second oxide film removing step of the semiconductor wafer. A second chamfering process for chamfering the end face from which
Including
In the second oxide film removing step, the center of the semiconductor wafer is rotated as a center axis of rotation, the center of the third grindstone is used as a center axis of rotation, and the direction of the center axis of rotation of the third grindstone is A method of manufacturing a semiconductor device, comprising: rotating a semiconductor wafer in a direction substantially perpendicular to a direction of a central axis of rotation of the semiconductor wafer.   13. The method of manufacturing a semiconductor device according to claim 12, wherein the third grindstone includes the pores at a rate at which clogging of the oxide film removed in the second oxide film removing step does not occur.   The said 3rd grindstone is a grindstone containing the fine grain which does not produce a chipping in the end surface from which the said oxide film was removed by the said 2nd oxide film removal process of the said semiconductor wafer. 14. A method for manufacturing a semiconductor device according to 12 or 13.   15. The method of manufacturing a semiconductor device according to claim 12, wherein the third grindstone is a grindstone including abrasive grains having a diameter equal to or smaller than abrasive grains having a grain size of # 1500.   The method for manufacturing a semiconductor device according to claim 12, wherein the third grindstone is a resin bond grindstone.   The method for manufacturing a semiconductor device according to claim 12, wherein the third grindstone is a grindstone including abrasive grains having a diameter equal to or smaller than that of abrasive grains having a grain size of # 2000.   The method of manufacturing a semiconductor device according to claim 12, wherein the third grindstone is a metal bond grindstone or a vitrified grindstone.

Images