JP2000005991A - Chamfering method for outer periphery section of wafer and its device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the shape of the chamfer section of a wafer accurately coincident with the shape of the groove of a buff by grinding to the outer periphery section of the wafer with a grinding wheel, then polishing with the buff. SOLUTION: A grinding wheel is called out from a storage magazine 8 by an automatic tool changing means and is fitted to a main spindle 3. The tip of a cutting tool 10 fixed on an X-Y table 7 is ground by the groove of the grinding wheel rotatively held by the main spindle 3. The tool of the main spindle 3 is replaced from the grinding wheel to a buff by the automatic tool changing means. When the buff is set to the main spindle 3, the buff is cut by the cutting tool 10 ground with its tip for the groove machining of the buff. The groove shape of the grinding wheel can be transferred to the buff via the cutting tool 10, thus the groove shape of the grinding wheel is prevented from being made inconsistent with the groove shape of the buff, thereby the outer periphery section of a wafer 2 can be chamfered very accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for chamfering an outer peripheral portion of a wafer and an apparatus for chamfering the outer peripheral portion of the wafer, and more particularly to a case where the outer peripheral portion of a semiconductor silicon wafer is mirror-finished.

[0002]

2. Description of the Related Art Conventionally, for example, in a method of manufacturing a semiconductor silicon mirror surface wafer, as shown in a flow chart of steps in FIG.
A slicing step A for slicing a single crystal rod manufactured by a single crystal manufacturing apparatus to obtain a thin disk-shaped wafer, and a rough chamfering step for grinding and chamfering an outer peripheral edge of the wafer obtained in the slicing step A. B, a lapping step C for lapping the rough-chamfered wafer to flatten it, an etching step D for removing the processing strain remaining on the rough-chamfered and lapped wafer surface, and an outer peripheral portion of the etched wafer. Mirror polishing step E for polishing and polishing the wafer to a mirror finish, mirror polishing step F for polishing the main surface of the mirror-polished wafer to a mirror finish, washing the mirror-polished wafer and polishing agent or foreign matter adhering thereto , A final cleaning step G for removing

As described above, a wafer manufacturing process includes a chamfering process. Of the chamfers, the rough chamfer removes the outer edge of the wafer by grinding.
The outer peripheral portion of the wafer has a predetermined shape and dimensions. The main purpose of rough chamfering is to prevent chips and chips from being generated on the outer peripheral portion of the wafer, thereby preventing a reduction in yield in a wafer manufacturing process or a device manufacturing process. When an epitaxial film is grown on a wafer, it is possible to suppress the occurrence of a so-called crown due to abnormal growth at the outer peripheral portion.

[0004] On the other hand, mirror chamfering is for smoothing the outer peripheral portion of a wafer which has been rough chamfered into a mirror-like shape. The main purpose is to reduce the amount of particles generated (improvement of dust generation) by making it difficult for members in contact with the outer peripheral portion of the wafer, such as a wafer basket and a boat, to be worn in the device manufacturing process, and to reduce the outer peripheral portion of the wafer. This is to facilitate the removal of particles adhering to the substrate in the cleaning process (improvement in cleaning performance), thereby improving the yield in the device manufacturing process.

[0005] The following are typical techniques adopted as such chamfering methods such as rough chamfering and mirror chamfering. First, rough chamfering is performed by grinding using a grindstone as a tool. As a method of this grinding process,
There are two main methods. One is the total pattern method, as shown in FIG.
As shown in the figure, the outer peripheral portion of the wafer is pressed against the groove of the grindstone 20 having the same shape as the desired wafer chamfering shape, and the ridges on the upper surface side and the lower surface side of the wafer 2 held by the holding plate 4 are chamfered at one time. How to do it.

On the other hand, the NC system (numerical control system)
As shown in (B), the relative position between the wafer 2 and the grindstone is numerically controlled, and the grindstone 20 having an inverted trapezoidal groove is used.
Chamfered tip at bottom of groove (outermost periphery of wafer)
And chamfering the upper surface of the wafer on the upper surface of the groove and the lower surface of the wafer on the lower surface of the groove.

As shown in FIG. 6, the mirror chamfering uses a buff 21 made of foamed polyurethane as a tool, supplies an abrasive containing colloidal silica as a working fluid, and inserts a buff into the groove formed in the buff and onto the holding plate 4. By inserting and pressing the outer peripheral portion of the held wafer, the surface roughened by grinding is polished at once. The groove shape of the buff is a general shape, and a shape is adopted such that the polishing pressure when the wafer 2 is pressed is uniform over the entire outer peripheral portion of the wafer so that the mirror surface can be effectively formed.

There are generally two methods for forming grooves in the buff. One method is to attach a buff with a groove outside the machine to the machine, and the other is to attach a cutting tool with the same shape as the buff groove to the machine using another machine,
In this method, a groove is formed in the buff inside the machine using the tool as a tool.

Incidentally, in the wafer manufacturing process, the outer peripheral portion of the wafer is not processed only by the above-mentioned rough chamfering process and mirror surface chamfering process.
Are also processed in the lapping step C and the etching step D. That is, usually lapping holds the wafer in the hole of the steel carrier, sandwiches the wafer between the upper and lower platens, and supplies the free abrasive grains, while rotating the platen in the opposite direction to the main surface of the wafer. Is wrapped. At this time, since the outer peripheral portion of the wafer is also in contact with the inner wall of the hole of the carrier in the presence of the free abrasive grains, it is processed in the same manner as the main surface. Further, the normal etching step D is also performed by immersing the entire wafer in an etching solution, so that the outer peripheral portion of the wafer is also etched.

[0010]

In such a conventional wafer chamfering method, a problem that the chamfered portion is not partially mirror-finished is apt to occur. The fact that the mirror is not partially mirrored means that the polishing is not partially performed, and that the contact between the buff and the outer peripheral portion of the wafer is partially insufficient. This is because the shape of the chamfered portion of the wafer and the shape of the groove of the buff do not partially match.

The reason why the shape of the chamfered portion of the wafer and the shape of the groove of the buff are partially inconsistent is as follows.
There are three main types. One is in the wafer manufacturing process. As described above, the outer peripheral portion of the wafer is rough-chamfered,
After a lapping step and an etching step, a mirror chamfering step is performed. In the lapping step and the etching step, the outer peripheral portion of the wafer is also processed. However, unlike the main surface, the removal amount and the shape of the outer peripheral portion are not controlled, or even if it is performed, it is difficult to control accurately. Therefore, the chamfered shape of the outer peripheral portion of the wafer created in the rough chamfering process is deteriorated in the lapping process and the etching process, and does not match the groove shape of the buff in the mirror chamfering process.

The second cause is that the wafer is held. In other words, since the rough chamfering step and the mirror chamfering step are performed by separate and independent machines, the wafer is also held on separate holding boards. Therefore, there are differences in the centering position of the wafer on the holding plate, the flatness of the holding plate surface, the height of the holding surface, and the like. Therefore, after the rough chamfering, the groove shape of the grindstone is transferred to the outer peripheral portion of the wafer to have a desired shape. However, when the wafer is detached from the holding plate of the rough chamfering machine and held on the holding plate of the mirror chamfering machine, Since there is a difference in the holding state between the two holding plates, the groove shape of the buff does not match the chamfered shape of the wafer.

[0013] The third cause is the consistency of the groove shapes of the grindstone and the buff. That is, the shape of the chamfer of the wafer is
First, since the groove shape of the grindstone is transferred by rough chamfering and then polished by the groove of the buff, it is required that the groove shape of the grindstone and the groove shape of the buff accurately match. However, a method of attaching a buff with a groove outside the machine base to the apparatus, or attaching a tool having a cutting edge formed into the same shape as the buff groove by another machine to the machine base, using the tool as a tool, In the method of forming a groove in the buff, the groove shape of the grindstone and the groove shape of the buff cannot be accurately matched. In addition, both of them are gradually worn by use, but the degree of wear is different, so that the shape consistency is further deteriorated.

SUMMARY OF THE INVENTION The present invention has been made in view of such problems, and an object of the present invention is to provide a chamfer based on the fact that the shape of a chamfered portion of a wafer and the shape of a groove of a buff do not partially match. An object of the present invention is to provide a chamfering method and a chamfering apparatus in which a problem that a part is not partially mirror-finished does not occur.

[0015]

According to a first aspect of the present invention, there is provided a method for chamfering an outer peripheral portion of a wafer, wherein the outer peripheral portion of the wafer is ground using a grindstone. This is followed by polishing using a buff, and chamfering the outer peripheral portion of the wafer.

As described above, if the outer peripheral portion of the wafer is ground by using a grindstone and subsequently polished by using a buff, the roughening process and the mirror-beveling process can be performed. For example, the chamfered shape is deteriorated in the lapping process or the etching process, and the groove shape of the buff and the chamfered shape of the wafer in the mirror chamfering process do not match.

Further, the invention described in claim 2 of the present invention is characterized in that the grinding and the subsequent polishing are performed continuously while holding the wafer. And chamfering the outer peripheral portion of the wafer.

As described above, if the grinding process and the subsequent polishing process are performed continuously while holding the wafer, the rough chamfering process and the mirror chamfering process can be performed by separate and independent machines. As described above, it is possible to completely solve the problem that the groove shape of the buff and the chamfered shape of the wafer do not match based on the difference in the holding state of the wafer.

Further, according to a third aspect of the present invention, in the method for chamfering the outer peripheral portion of the wafer according to the first or second aspect, first, the tip of the cutting tool is ground with a grindstone for performing a grinding process. Then, using the ground tool, a groove for polishing is performed on the surface of the buff, and then a grinding process is performed on the outer peripheral portion of the wafer using the grindstone. This is a method for chamfering an outer peripheral portion of a wafer, wherein the outer peripheral portion of the wafer is polished using a buff that has been grooved with a cutting tool.

As described above, if the tool is ground with a grindstone for grinding the outer periphery of the wafer and the buff is grooved using the tool, the shape of the grindstone is accurately transferred to the buff via the tool. The consistency between the groove shape of the grindstone and the groove shape of the buff is accurately maintained. In addition, even if an inconsistency occurs due to wear, it can be easily repaired by performing the same operation.

In this case, when the tip of the cutting tool is ground with a grindstone for performing the grinding, the shape of the tip of the cutting tool is ground to the same shape as the chamfered shape of the wafer. Is preferred. In the case where a groove for polishing is formed on the surface of the buff by using the ground cutting tool, the groove shape of the buff is processed into the same shape as the shape of the grindstone. be able to.

With this arrangement, the chamfered shape of the outer peripheral portion of the wafer and the groove shape of the buff exactly match, or the groove shape of the grindstone and the groove shape of the buff match, so that the chamfered portion is partially mirror-finished. The problem of not being performed is eliminated.

In the present invention, a grinding wheel for the grinding and a buff for the polishing may be integrated with each other. With this configuration, not only the wafer as the workpiece is held, but also the grinding wheel and the buff as the tool are also held coaxially, so that the relative position, height, etc. of the tool are simply changed. Processing can be performed only by using. Therefore, the wafer chamfered shape and the buff groove shape can be matched with extremely high accuracy,
Processing time can also be reduced.

The chamfering method according to the present invention is extremely useful as a method for chamfering the outer peripheral portion of a semiconductor silicon wafer which requires increasingly higher quality.

Therefore, if the chamfering method of the present invention is adopted as one step in a method for producing a wafer, particularly a method for producing a semiconductor silicon wafer, a high-quality wafer having a mirror-polished outer peripheral portion can be reliably obtained. (Claims 8 and 9).

On the other hand, the invention according to claim 10 of the present invention holds at least a whetstone for grinding the outer peripheral portion of the wafer or a buff for subsequently polishing the outer peripheral portion of the wafer. A chamfering device for an outer peripheral portion of a wafer, comprising: a main shaft for rotating the wafer; and a holding plate for holding and rotating the wafer. With such an apparatus, roughing and mirror chamfering can be performed with one apparatus,
Grinding and polishing can be performed successively while holding the wafer.

In this case, as described in claim 11,
It is preferable to have an automatic tool changing means capable of automatically removing and replacing a grindstone or a buff held on the main spindle. As described above, if the automatic tool changing means is provided, the tool changing time can be extremely shortened, and the tool can be accurately set on the spindle.

Further, as set forth in claim 12, the grindstone and the buff held on the main shaft can be integrated. In this way, if the whetstone and buff are integrated, without changing tools during grinding and polishing,
Since the outer peripheral portion of the wafer can be chamfered, the time can be further reduced, and errors due to tool setting can be eliminated.

According to a thirteenth aspect of the present invention, the spindle is disposed on a Z table, the holding plate is disposed on an XY table, and the Z table, the holding plate, and the XY table are It can be controlled numerically. Thereby, the chamfering of the outer peripheral portion of the wafer can be performed very accurately.

According to a fourteenth aspect of the present invention, the X-
A tool is arranged on the Y table, the tool is ground by the grindstone held on the spindle, and the buff held on the spindle can be processed by the ground tool. With this configuration, the groove shape of the grindstone can be accurately transferred to the buff via the cutting tool, and the groove shape of the grindstone and the groove shape of the buff do not become inconsistent.

In this case, as described in claim 15,
The holding plate is configured to be slidable on an XY table so that a contact load can be kept constant during polishing of an outer peripheral portion of the wafer held by the holding plate. With this configuration, the problem that the wafer outer peripheral portion is not partially polished can be completely solved.

Therefore, as described in claim 16, the chamfering apparatus for the outer peripheral portion of the wafer according to the present invention is particularly useful when chamfering a semiconductor silicon wafer.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings, mainly with respect to chamfering the outer peripheral portion of a silicon wafer, but the present invention is not limited to these. Absent. The present inventor, when chamfering the outer peripheral portion of the wafer, has conducted intensive studies to solve the problem that the chamfered portion is not partially mirror-finished, and as a result, the shape of the chamfered portion of the wafer and the shape of the groove of the buff are partially changed. The present invention has been completed by paying attention to the fact that it does not coincide with the above.

That is, in the present invention, first, the grinding process performed on the outer peripheral portion of the wafer using a grindstone and the polishing process performed using a buff are successively performed. In this method, the mirror chamfering process is performed immediately after the rough chamfering process, so that the wafer can be subjected to the mirror chamfering process with the chamfered shape created in the rough chamfering process. Therefore, after the conventional rough chamfering step, for example, when a lapping step or an etching step is performed, the chamfered shape formed by the rough chamfering is deteriorated, and the groove shape of the buff and the chamfered shape of the wafer in the mirror chamfering step match. It never goes away.

In the present invention, it is preferable that the grinding and the subsequent polishing are continuously performed while holding the wafer. As described above, if the grinding and the subsequent polishing are performed continuously while holding the wafer on the same holding plate, the holding states of the wafers are completely the same, so that they are independent and independent. Buffing based on differences in wafer holding conditions, such as differences in centering position of wafer on holding plate, flatness of holding plate surface, height of holding surface, etc. This eliminates the possibility that the groove shape and the chamfered shape of the wafer do not match.

Further, in the present invention, first, the tip of the cutting tool is ground with a grindstone for performing a grinding process, and then the groove for polishing is formed on the surface of the buff using the ground tool. It is preferable that the outer peripheral portion of the wafer is later subjected to grinding using a grindstone, and subsequently, the outer peripheral portion of the wafer is subjected to polishing using a buff grooved with a cutting tool. That is, the shape of the cutting edge of, for example, a cutting tool fixed to a machine base is created using a grindstone used for roughening of a wafer, and the groove of the buff is processed using the cutting tool as a tool.

In this case, for example, a metal bond diamond is generally used as a material of the grinding stone, and a foamed polyurethane resin is generally used as a material of the buff. Should be adopted. Thereby, the cutting tool can be subjected to the grinding by the grindstone and the buff can be subjected to the cutting.

As described above, if a tool is ground with a grindstone for grinding the outer peripheral portion of a wafer and the buff is grooved using the tool, the shape of the grindstone or the desired chamfered shape can be accurately formed through the tool. Therefore, the groove shape of the grindstone and the groove shape of the buff do not become inconsistent.

In mirror chamfering, it is necessary that the relative heights of the buff groove and the chamfered portion on the outer peripheral portion of the wafer match each other. In the method of mounting on a table, errors in groove processing and mounting errors occur, and the relative heights of the grooves of the buff and the outer peripheral portion of the wafer do not always match. Also, in a method in which a cutting tool with a cutting edge shape is mounted on the machine base outside the machine base and the buff is grooved with this machine tool, a machining error of the tool and a mounting error of the tool occur, and the same problem as described above occurs. .

On the other hand, if the processing of the cutting edge of the cutting tool for buff grooves is performed in the machine base as in the present invention, the groove processing error of the buff, the mounting error of the buff, the processing error of the cutting tool, Installation error etc. can be completely eliminated,
The relative height between the buff groove and the wafer chamfer can be matched. In addition, when attaching the byte to the machine,
Although there should be an installation error, in the present invention, since the cutting edge of the cutting tool is machined in the machine base, when the cutting edge of the cutting tool is machined, it is processed at an appropriate position. You can do the same as it does not.

Further, the grindstone and the buff wear due to use, and the groove shape gradually deteriorates. In addition, since the method of wear is different between the grindstone and the buff, the groove shapes gradually do not match during use. In such a case, in the past, the only option was to replace it with a new one. On the other hand, in the present invention, even when mismatching occurs due to wear, since the groove shape of the grindstone can be transferred to the buff via the cutting tool, the influence of the shape change due to wear is substantially eliminated, The outer peripheral portion of the wafer can be reliably mirror-finished.

Therefore, it is not necessary to replace the grindstone with a new one while the change in the groove shape of the grindstone due to the wear is within the allowable range. Also, when the cutting edge of the cutting tool is worn, it can be regenerated by grinding with a grindstone.
This can also significantly reduce the frequency of replacement with new ones.

In this case, in the present invention, when the tip of the cutting tool is ground with a grindstone for grinding, it is desirable that the shape of the tip of the cutting tool be ground to the same shape as the chamfered shape of the wafer. Then, using this ground tool, a groove for polishing is formed on the surface of the buff, and the groove shape of the buff is processed into the same shape as the shape of the grindstone or the same shape as the desired wafer chamfering shape. To do.

In this way, the chamfered shape of the outer peripheral portion of the wafer and the groove shape of the buff exactly match, or the groove shape of the grindstone and the groove shape of the buff match, so that the chamfered portion is partially mirror-finished. The problem of not being performed is eliminated.

However, in the practice of the present invention, if the positions of the grindstone, the buff, the cutting tool and the wafer are controlled by numerical control which can be freely and precisely controlled, the groove shape of the grinding stone, the groove shape of the buff and the cutting edge shape of the cutting tool can be freely adjusted. It is possible to select, and it is not always necessary to limit the shape as described above. However, it is more preferable to limit each shape as described above from the practical viewpoints such as ease of numerical control program and machining time.

FIG. 1 shows the relationship between the shape of the groove of the grindstone, the cutting edge of the cutting tool, the groove of the buff, and the outer peripheral portion of the wafer of the present invention. In the case of FIG. 1A, the rough chamfering is performed by the die forming method. First, the cutting edge of the cutting tool is processed with a grinding stone, and the groove shape of the grinding stone is transferred to the cutting edge of the cutting tool. Next, a buff groove is machined with this tool, and the cutting edge shape of the tool is transferred to the buff groove.
As described above, in the die forming method, the shape of the groove of the grindstone, the cutting edge of the cutting tool, the groove of the buff, and the shape of the outer peripheral portion of the wafer have the same shape. Therefore, there is no problem that the mirror is not partially mirrored.

FIG. 1B shows a case where rough chamfering is performed by the NC method. First, the cutting edge of a cutting tool is machined with a grindstone, and the cutting edge of the cutting tool is formed into a chamfered shape of a wafer. Next, the groove of the buff is processed with the cutting tool, and the groove shape of the grindstone is transferred to the buff groove. As described above, in the NC method, the grooves of the grindstone and the grooves of the buff, the cutting edge of the cutting tool, and the chamfered shape of the outer peripheral portion of the wafer have the same shape. Never.

FIG. 1C shows a case where rough chamfering is performed by the NC method. First, the cutting edge of the cutting tool is machined with a grindstone, and the cutting edge of the cutting tool is formed into a chamfered shape of the wafer. Next, the groove of the buff is machined with the cutting tool, and the groove shape of the buff is changed to the chamfered shape of the wafer. In this case, the chamfered shape of the cutting edge of the cutting tool and the outer peripheral portion of the wafer and the groove shape of the buff have the same shape, and there is no problem that the chamfered portion of the wafer is not partially mirror-finished during the mirror-chamfering.

The present invention is not limited to such a case, and the present invention can be practiced even if the shapes of the grovestone groove, the cutting edge of the cutting tool, the buff groove, and the chamfered portion of the wafer are different from each other. The effect is achieved.

As described above, according to the present invention, the groove shape of the grindstone and the groove shape of the buff can be perfectly matched, so that the entire area of the wafer chamfered portion comes into contact with the buff. However, the polishing does not proceed because the contact pressure does not occur between the wafer and the buff just by contacting. Therefore, it is necessary to cause the contact pressure to be generated by relatively moving the wafer and the buff to advance the polishing. For this purpose, it is preferable to use numerical control that can ensure a uniform polishing pressure.

Further, in carrying out the present invention, when a whetstone for grinding and a buff for polishing are used as an integral type, the wafer to be processed is reduced. In addition to being processed while being held, the grinding wheel and the buff as tools are also held coaxially, so that chamfering can be performed simply by changing the relative position and height of the tool. Therefore, the wafer chamfered shape and the buff groove shape are matched with extremely high precision,
A highly mirror-finished wafer can be obtained, and the processing time can be reduced.

If the wafer chamfering method of the present invention is adopted as one step in a method for manufacturing a wafer, particularly in a method for manufacturing a semiconductor silicon wafer, a high quality wafer whose outer peripheral portion is mirror-finished can be surely obtained. Obtainable. In this case, if the chamfering step of the present invention is performed in the first half of the wafer manufacturing step, the mirrored chamfered portion may be roughened in a later step. Therefore,
The chamfering step of the present invention is preferably performed as late as possible in the wafer manufacturing step. For example, after the slicing step, the wafer can be manufactured in the order of the double-side grinding step, the chamfering step according to the present invention, and the double-side polishing step.

Next, the chamfering device of the present invention will be described, but the present invention is not limited to these. FIG.
1 is a schematic configuration example diagram of a chamfering device of the present invention. The chamfering device 1 of the present invention holds at least a grindstone for grinding the outer peripheral portion of the wafer 2 or a buff for polishing, and a spindle 3 for rotating the same, and holds and rotates the wafer 2. And a holding plate 4 for causing the holding plate 4. A vacuum line 5 is connected to the holding board 4 so that the wafer 2 can be suction-held. The holding plate 4 is connected to an XY table 7 via a rotary table 6.
It is installed above. A wafer centering device (not shown) is arranged around the holding plate 4. The cutting tool 10 used for buffing is fixed on the XY table 7.

A tool such as a grindstone or a buff held by the spindle 3 can be stored in the storage magazine 8, and can be called out to the spindle as required, and can be automatically attached and detached to change tools. Means. And
The spindle 3 is arranged on a Z table 9 and the holding plate 4 is XY
The Z table 9, the holding plate 4,
The position of the XY table 7 can be precisely and freely controlled by numerical control. A supply line 11 for a grinding fluid and a polishing fluid is connected near a tool such as a grindstone or a buff held on the main shaft 3.

In the chamfering of the present invention with the above-described apparatus configuration, first, a grinding wheel is called from the storage magazine 8 by the automatic tool changing means and attached to the main shaft 3. Next, the cutting edge of the cutting tool 10 fixed on the XY table 7 is ground by a groove of a grindstone that is rotated and held by the main shaft. Next, the tool of the spindle 3 is changed from the grindstone to the buff by the automatic tool changing means. When the buff is set on the main shaft 3, the buff is grooved by cutting with a cutting tool 10 having the above-mentioned cutting edge. Next, the buff of the spindle 3 is replaced with a grindstone stored in the magazine 8 again by the automatic tool changing means. Then, using the grindstone, the outer peripheral portion of, for example, the silicon wafer 2 sucked and held by the holding board 4 is ground and rough chamfered. When the rough chamfering is completed, the whetstone is replaced with a buff by automatic tool changing means. When the buff is set on the main shaft, the outer periphery of the silicon wafer is polished using the buff.

As described above, in the apparatus of the present invention, roughing and mirror-chamfering can be performed by one apparatus, so that grinding and polishing can be performed successively while holding the wafer. In addition, since it has automatic tool change means, the tool change time is extremely reduced,
It can be accurately set on the spindle. Further, since the groove shape of the grindstone can be accurately transferred to the buff via the cutting tool, the groove shape of the grindstone does not become inconsistent with the groove shape of the buff. Therefore, the apparatus of the present invention enables extremely accurate chamfering of the outer peripheral portion of the wafer.

In this case, according to the present invention, as shown in FIG. 3, the grindstone 20 and the buff 21 held on the main shaft 3 can be integrated. Thus, the whetstone 20 and the buff 2
If 1 is an integrated type, the automatic tool changing means can be used to change tools one by one in advance, such as grinding of a cutting tool, cutting of a buff with a cutting tool, grinding of the outer peripheral portion of a wafer, and polishing of the outer peripheral portion of the wafer. Instead, the machining can be performed simply by raising and lowering the spindle held on the Z-axis. Therefore,
The processing time can be further reduced. Further, not only the wafer 2 as the workpiece is held but also the grindstone 20 and the buff 21 as the tools are also held coaxially, so that errors based on the setting of the tool can be completely eliminated. The wafer chamfer can be mirror-finished with extremely high precision.

In the present invention, as shown in FIG.
The holding plate 4 is placed on the XY table 7 by, for example, a guide 12,
13, the guide is pulled toward the main shaft side using a weight 14 or the like at one end of the guide, so that the contact load during polishing of the outer peripheral portion of the wafer 2 held on the holding plate 4 is reduced. You may make it fixed. The guide is composed of an upper guide 12 and a lower guide 13 and is slidable in the X-axis direction, and can be fixed by a stopper 15.

This means that the position is controlled by an XY table,
If the wafer is pressed against the buff, the amount of pressing can be controlled correctly. However, due to the viscoelastic properties of the buff, the contact load between the buff and the wafer is not always constant. In polishing, it is more important to make the contact load constant rather than the pressing amount. Therefore, the above configuration is more preferable.

In this case, the chamfering of the wafer is performed as follows. The guides 12 and 13 are fixed by the stopper 15, and rough chamfering is performed. Next, the fixing of the upper and lower guides is released, and mirror chamfering is performed. At this time, the buff 21 and the wafer 2 come into contact with a constant load by the weight 14, and the outer peripheral portion of the wafer is uniformly polished.

[0061]

EXAMPLE An 8-inch diameter silicon single crystal wafer was chamfered by the method of chamfering the outer peripheral portion of the wafer of the present invention. As the wafer used, a silicon single crystal rod grown by the Czochralski method was cut with a wire saw to obtain a slice wafer having a diameter of 201 mm, and both sliced wafers were ground. The wafer is subjected to rough chamfering and mirror-chamfering according to the present invention to obtain a wafer having a diameter of 200 mm.
mm silicon single crystal wafer was obtained.

An apparatus as shown in FIG. 2 was used as the chamfering apparatus. As the grindstone for rough chamfering, a metal bond diamond grindstone with a grain size of 800 having an inverted trapezoidal groove was used, and industrial water was used as a working fluid. A cylindrical buff made of foamed polyurethane in which zirconium oxide abrasive grains were dispersed was used as a buff for mirror chamfering, and an abrasive containing colloidal silica was used as a working fluid. A 1.2 mm thick plate made of high speed steel (high speed tool steel) was used as the cutting tool.

As a processing procedure, first, using a grindstone as a tool, grinding was performed such that the shape of the tip portion serving as the cutting edge of the cutting tool was the same as the shape of the chamfered portion of the wafer. Next, using this cutting tool, cutting was performed so that the groove shape of the buff was the same as the groove shape of the grindstone. Next, the silicon wafer having a diameter of 201 mm to be chamfered was centered on a holding plate, and then held by vacuum suction. Using the above-mentioned grindstone and buff, rough chamfering and mirror chamfering were continuously performed while holding the wafer on the holding plate. In addition, at the time of mirror chamfering, in order to generate a contact pressure for polishing between the wafer and the buff, the interference between the buff and the wafer should be 50 μm in the vertical direction of the bottom surface and the side surface of the groove of the buff. And the relative position of the buff and the wafer was numerically controlled.

The outer periphery of the wafer after chamfering was observed with a video microscope. For comparison, a sample which was chamfered by a conventional chamfering method and in which the chamfered portion was not partially mirror-finished was similarly observed. As a result, in the conventional wafer, a linear streak peculiar to the grinding process by rough chamfering was partially observed, but in the wafer subjected to the chamfering according to the present invention, all the streaks disappeared and the entire outer peripheral portion was removed. Was mirrored.

The present invention is not limited to the above embodiment. The above embodiment is an exemplification, and has substantially the same configuration as the technical idea described in the scope of the claims of the present invention. It is included in the technical scope of the invention.

For example, in the above embodiment, the case where the wafer to be planarized is semiconductor silicon has been described as an example. However, the present invention is not limited to this, and other semiconductor materials, such as germanium or GaAs, may be used. , Ga
The present invention can be similarly applied to a wafer such as a compound semiconductor single crystal such as P or InP or an oxide single crystal.

In the above embodiment, the diameter 20
The case of manufacturing a silicon semiconductor single crystal wafer of 0 mm has been described by way of example, but the present invention is not limited to this. Similar effects can be obtained by chamfering a silicon wafer having a large diameter of 300 mm or more or 400 mm or more. Of course, it can be applied.
Needless to say, the present invention is effective even when applied to a wafer having a diameter of m or less.

[0068]

As described above, in the present invention, since the grinding and polishing are performed successively while holding the wafer, the shape of the chamfered portion of the wafer and the shape of the groove of the buff can be accurately determined. Matches. Therefore, the problem that the chamfered portion of the wafer is not partially mirror-finished, which has conventionally been a problem, does not occur. In addition, since the processing time can be shortened and the life of the grindstone and the buff can be improved, the wafer manufacturing cost and productivity can be improved.

[Brief description of the drawings]

FIG. 1 is a view showing the relationship among the shape of a groove of a grindstone, a cutting edge of a cutting tool, a groove of a buff, and an outer peripheral portion of a wafer in the chamfering method of the present invention. (A) When the whole shape is the same, (B) When the bite and the wafer, and when the grindstone and the buff have the same shape, (C) When the bite, the buff and the wafer shape are the same.

FIG. 2 is a schematic configuration example diagram of a chamfering device of the present invention.

FIG. 3 is an explanatory diagram of a case where a grindstone and a buff are integrated with each other in the present invention.

FIG. 4 is a configuration example diagram in a case where the holding plate is configured to be slidable in the present invention.

FIG. 5 is an explanatory view of a conventional rough chamfering method. (A) Total type system, (B) NC system.

FIG. 6 is an explanatory diagram of a conventional mirror surface chamfering method.

FIG. 7 is a flowchart showing a conventional silicon mirror wafer manufacturing process.

[Explanation of symbols]

1: Chamfering device, 2: Wafer, 3: Spindle, 4:
Holding board, 5 ... vacuum line, 6 ... rotary table, 7 ...
XY table, 8: storage magazine, 9: Z table, 10: byte, 11: supply line, 12: upper guide, 13: lower guide, 14: weight, 15: stopper, 20: grinding stone, 21: buff. A: slicing process, B: rough chamfering process, C: lapping process,
D: Etching process, E: Mirror chamfering process, F
… Mirror polishing step, G… final cleaning step.

Claims (16)

[Claims] 1. A method of chamfering an outer peripheral portion of a wafer, wherein the outer peripheral portion of the wafer is first subjected to grinding using a grindstone, and subsequently to a polishing process using a buff. How to chamfer a part. 2. The method for chamfering an outer peripheral portion of a wafer according to claim 1, wherein the grinding process and the subsequent polishing process are continuously performed while holding the wafer. 3. The method for chamfering an outer peripheral portion of a wafer according to claim 1 or 2, wherein the tip of the cutting tool is first ground with a grindstone for performing a grinding process. The surface of the buff is used to perform groove processing for polishing processing, and thereafter the outer peripheral portion of the wafer is subjected to grinding processing using the grinding stone, and subsequently, the wafer is processed using the buff grooved with the cutting tool. A method of chamfering an outer peripheral portion of a wafer, wherein the outer peripheral portion is polished. 4. The grinding machine according to claim 3, wherein when the tip of the cutting tool is ground with a grindstone for performing the grinding process, the shape of the tip of the cutting tool is ground to the same shape as the chamfered shape of the wafer. A method for chamfering the outer periphery of the described wafer. 5. A groove for polishing the surface of a buff using the ground cutting tool, wherein the groove of the buff is processed to have the same shape as a grindstone. The method for chamfering an outer peripheral portion of a wafer according to claim 3 or 4. 6. The apparatus according to claim 3, wherein a whetstone for said grinding and a buff for said polishing are integrated. Method of chamfering the outer periphery of a processed wafer. 7. A method for chamfering an outer peripheral portion of a semiconductor silicon wafer by the method according to any one of claims 1 to 6. 8. A method for manufacturing a wafer, wherein at least the chamfering method according to any one of claims 1 to 6 is performed in one step. 9. A method for manufacturing a semiconductor silicon wafer, wherein at least the chamfering method according to any one of claims 1 to 6 is performed in one step. 10. A grinding wheel for grinding the outer peripheral portion of the wafer or a buff for subsequently polishing the outer peripheral portion of the wafer and a main shaft for rotating the same, and a wafer for holding the wafer. A chamfering device for an outer peripheral portion of a wafer, comprising a holding plate for rotating the wafer. 11. A wafer chamfering apparatus according to claim 10, further comprising an automatic tool changing means capable of automatically removing and replacing a whetstone or a buff held on said spindle. 12. The wafer chamfering apparatus according to claim 10, wherein the grindstone and the buff held on the spindle are integrated. 13. The spindle is disposed on a Z table,
The said holding board is arrange | positioned on an XY table, The said Z table, a holding board, and an XY table are numerically controlled, The Claim 1 characterized by the above-mentioned. Chamfering device for wafer periphery. 14. A tool is arranged on the XY table so that the tool can be ground by a grindstone held by the spindle and the buff held by the spindle can be processed by the ground tool. 14. The apparatus for chamfering an outer peripheral portion of a wafer according to claim 10, wherein: 15. The holding plate is configured to be slidable on an XY table so that a contact load becomes constant during polishing of an outer peripheral portion of a wafer held by the holding plate. The apparatus for chamfering an outer peripheral portion of a wafer according to any one of claims 10 to 14, wherein: 16. An apparatus for chamfering an outer peripheral portion of a wafer according to claim 10, wherein the wafer to be chamfered is a semiconductor silicon wafer.