JP2921250B2 - Mirror polishing method and apparatus for wafer chamfer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for mirror-polishing a chamfered portion of a semiconductor wafer (hereinafter abbreviated as "wafer").

[0002]

2. Description of the Related Art A wafer used as a substrate of a semiconductor device is obtained by slicing a single crystal ingot such as silicon at a right angle to the rod axis direction, and chamfering, lapping, It is manufactured by going through processes such as etching, annealing, and polishing.

[0003] By the way, the chamfering conventionally performed in the above-described wafer manufacturing process has a main purpose of preventing chipping at a wafer edge portion. In this chamfering, usually, a wafer is hardened by a hard and rigid grindstone. The method of shaving off the edge part was adopted.

However, in recent years, as the density of semiconductor devices has become higher, measures against dust in the manufacturing process have become more severe, and it has become an important requirement that the wafer, which is the material, is free from dust. Also, the necessity of polishing a wafer chamfered part to the same level as a mirror part of a wafer has been increasing.

[0005] There are various modes of mirror polishing the edge portion of the wafer. One example is shown in FIG.
That is, the mirror polishing method shown in FIG. 6 is a method using a cylindrical full-shaped buff (particularly, an external cylindrical full-shaped buff) 140. The cylindrical full-shaped buff 140 is made of an elastic body, and the outer periphery of the wafer W A processing groove 140a that follows the shape of the outer chamfer W1 is formed over the entire circumference.

In such a method, the cylindrical buff 14 is used.
0 and the wafer W are both driven to rotate in the direction of the arrow shown in the figure, and while supplying a slurry (polishing liquid) (not shown), the outer peripheral chamfered portion W1 of the wafer W is machined by the processing groove 140a of the cylindrical buff 140.
To the outer peripheral chamfer W1 of the wafer W.
Is mirror polished.

[0007]

By the way, in the above-mentioned mirror polishing, the shape of the processing groove 140a of the cylindrical buff 140 and the shape of the outer chamfer W1 of the wafer W match (that is, the shape of the wafer W). Outer chamfer W1 is machined groove 14
It is preferable that the outer peripheral chamfered portion W1 is uniformly mirror-polished over the entire surface (in contact with the entire surface 0a).

However, actually, the cylindrical buff 140
Of the processing groove 140a and the outer chamfer W1 of the wafer W
It is extremely difficult to always make the shape exactly match the shape of the shape, and it is a reality that both shapes are different.

Therefore, the cylindrical buff 140 is made of a soft material, and the entire surface of the outer peripheral chamfer W1 of the wafer W is brought into contact with the processing groove 140a by elastic deformation of the cylindrical buff 140. It is proposed that the outer chamfer W1 be uniformly mirror-polished over the entire surface.

However, if the buff is soft as described above, there is a problem that the buff is severely worn, the life is shortened, and the time required for polishing is prolonged.

[0011] The present invention has been made in view of the above problems, and a purpose thereof is to ensure a long life of a buff,
An object of the present invention is to provide a method and an apparatus for mirror-polishing a wafer outer peripheral chamfer that can uniformly and smoothly mirror the outer peripheral chamfer of the wafer at low cost.

[0012]

In order to achieve the above object, a method of the present invention comprises sequentially pressing a chamfered portion of a rotating wafer into a plurality of processing grooves having different cross-sectional shapes formed in a multistage cylindrical buff. Then, the entire periphery of the chamfered portion of the wafer is mirror-polished.

Further, the present invention provides a cylindrical buff formed by forming a plurality of processing grooves having different cross-sectional shapes in multiple stages, a buff rotating means for rotating and driving the cylindrical buff, and a cylindrical buff. A mirror polishing apparatus including a buff moving means for moving the wafer in the axial direction, a wafer rotating means for holding and rotating the wafer, and a pressing means for pressing the wafer against each processing groove of the cylindrical overall buff. The feature is that it is configured.

[0014]

According to the present invention, since the cross-sectional shapes of a plurality of machining grooves formed in a multi-stage on the cylindrical buff are different from each other, the outer peripheral chamfered portion is formed on the cylindrical buff while rotating the wafer. If the grooves are sequentially pressed, the outer chamfered portion of the wafer is mirror-polished by a plurality of processing grooves having different cross-sectional shapes, leaving no unpolished portion on the outer chamfered portion of the wafer, and the entire outer chamfered portion is uniform. The surface of the wafer is smoothened to improve the quality of the wafer.

Further, since the present invention employs a general buffing method in which the structure of the apparatus is simplified, mirror polishing can be performed at low cost.

Further, in the present invention, a relatively hard elastic material such as a hard polyurethane resin or a synthetic leather made of the same resin, a polyester resin, a fluororesin, or the like is used as a material of the cylindrical overall buff so that the cylindrical overall buff can be used. The life of the shape buff can be extended by keeping the wear of the shape buff small.

[0017]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a longitudinal sectional view of a mirror polishing apparatus according to the present invention, FIG. 2 is a longitudinal sectional view of a buff drive unit of the apparatus, FIG. 3 is a sectional view taken along line AA of FIG. 1, and FIG. It is sectional drawing of an outer peripheral chamfer.

In the mirror polishing apparatus 1 shown in FIG. 1, reference numeral 2 denotes a base, on which a buff head 3 is installed so as to be horizontally movable. A screw shaft 4 rotatably supported on the base 2 is screwed into the projecting stay 3a, and the screw shaft 4 is turned by a handle 5 attached to an end of the screw shaft 4. Thus, the buff head 3 can be moved in the direction of the arrow shown in the figure (the left-right direction in FIG. 1).

A U-shaped frame 6 is provided on the buff shaft 3 so as to be horizontally movable. The frame 6 is moved by a cylinder 7 mounted on the buff shaft 3. It is moved in the direction of the arrow shown in the figure (the left-right direction in FIG. 1). That is,
The frame 6 is connected to a rod 7a extending from the cylinder 7. By driving the cylinder 7 to move the rod 7a forward and backward, the frame 6 is moved on the buff shaft 3 in the direction of the arrow shown in the figure.

A master support 8 is mounted below the frame 6 so as to be horizontally movable.
In the figure, a disk-shaped master 9 is supported by a shaft 10 so as to be freely rotatable horizontally. A screw shaft 11 rotatably supported by the frame 6 is screwed to the master support 8, and by turning the screw shaft 11 with the handle 12, the master support 8 is placed on the frame 6. It can be moved in the direction of the arrow shown in FIG.

On the other hand, a buff driving device 20 is mounted on the upper part of the frame 6, and a rotary shaft 21 extending vertically downward from the buff driving device 20 is connected with an external cylinder buff 40. ing. As shown in detail in FIG. 2, the outer cylinder buff 40 has four processing grooves 40 having different cross-sectional shapes on its outer periphery.
a, 40b, 40c, and 40d are formed in multiple stages, and in this embodiment, each of the processing grooves 40a, 40b, 40c, and 4 is formed.
The included angles θ1, θ2, θ3, θ4 of 0d are respectively 20 °,
The angles are set to 40 °, 60 °, and 180 ° (straight). The outer cylinder buff 40 has characteristics such as having appropriate elasticity, retaining abrasive particles in the slurry, and being chemically and mechanically resistant to the working pressure and the used slurry. It is required to have, but as the material thereof, a relatively hard elastic material such as a hard polyurethane resin or a synthetic leather made of the same resin, a polyester resin, a fluororesin or the like is used.

Here, the configuration of the buff drive device 20 will be described in detail with reference to FIG.

In the buff drive device 20 shown in FIG. 2, the rotary shaft 21 penetrates the casing 22 so as to be vertically movable, and an intermediate portion thereof is held by a slider 24 via a bearing 23.

On the other hand, two motors 25 and 26 are provided in the upper part of the casing 22 so that one motor 2
The slider 24 is threadably engaged with a screw portion 27a formed on an output shaft 27 extending vertically downward from the vertical direction. A pulley 29 is connected to the lower end of an output shaft 28 extending vertically downward from the other motor 26. The pulley 29 and a spline 21a formed on the upper portion of the output shaft 21 can be freely moved up and down. A V-belt 31 is wound between the pulley 30 and the V-belt 31.

The motor 25, the output shaft 27, the slider 24, and the like are formed by moving the outer cylinder buff 40 in the axial direction (vertical direction).
Buffing means for moving the motor 2
6, the pulleys 29 and 30, the V-belt 31 and the like constitute buff rotating means for rotating and driving the external cylinder buff 40.

By the way, as shown in FIG.
A non-contact type position sensor 32 for detecting the height position (axial movement) of the outer cylinder buff 40 is provided on the upper side, and the position sensor 32 is provided to a controller 50 as control means. It is electrically connected. And
The controller 50 is electrically connected to the motor 25, which receives an input signal from the position sensor 32 and transmits a corresponding control signal to the motor 25.

On the other hand, a vertical rotating shaft 51 is rotatably supported on the base 2 via upper and lower bearings 52. A pulley 53 is connected to the lower end of the rotating shaft 51. ing. A motor 54 is provided on the side of the rotating shaft 51 of the base 2, and a pulley 56 is connected to a lower end of an output shaft 55 extending vertically downward from the motor 54. A belt 57 is wound between 56 and the pulley 53. The motor 54, the pulleys 53 and 56, the belt 57, the rotating shaft 51 and the like constitute a wafer rotating means.

A dish-shaped flange 58 is integrally formed at the upper end of the rotary shaft 51.
8, a disc-shaped suction plate 59 is held by a ball bearing 60 so as to be horizontally movable in an arbitrary direction. The suction plate 59 is provided between the flange plate 58 and this in a plan view. The center of the rotary shaft 5 is formed by a hexagonal plate spring 61.
1 is biased to coincide with the center. A pin 62 for transmitting torque is projected from the lower surface of the suction plate 59, and the pin 62 is engaged with a long hole 58 a formed in the flange portion 58 of the rotating shaft 51. Also, the suction plate 59
A circular suction groove 59a is opened on the upper surface of the central part of
The suction groove 59a is connected via a vacuum path 63 to a vacuum source (not shown) such as a vacuum pump. Further, a ring-shaped model 64 is attached to the lower surface of the suction plate 59.

A wafer pressing means 70 is provided on the base 2, and the wafer pressing means 70
Reference numeral 1 denotes a cylinder, and 72 denotes a pusher slidably held by a linear guide 73 in a direction indicated by an arrow (in the horizontal direction in FIG. 1). One end of the pusher 72 is in contact with a rod 71a of the cylinder 71. I have. FIG.
As shown in FIG.
4 is pivotally connected at its intermediate portion so as to be freely rotatable. And
One end of each arm 74 is connected to a pusher 72 via a spring 75, and a roller 76 is rotatably supported at the other end of the arm 74. The roller 76 contacts the outer peripheral portion of the suction plate 59. In contact.

Next, the operation of the mirror polishing apparatus 1 will be described.

First, the screw shaft 4 is turned by the handle 5, and the master support 8 is moved in the direction of the arrow on the frame 6 so that the center of rotation of the master 9 coincides with the center of rotation of the outer cylinder buff 40. Next, the cylinder 7 is driven to move the entire frame body 6 on the buff shaft stand 3 to bring the master 9 into contact with the outer periphery of the model 64.
Is positioned above.

On the other hand, when a wafer W is placed on the suction plate 59 and a vacuum source (not shown) is driven, a negative pressure is generated in the suction groove 59a opened in the suction plate 59. The wafer W is vacuum-sucked on the suction plate 59.
At this time, the cylinder 71 of the wafer pressing means 70
Is in a non-operation state, and the wafer W is a circular outer cylinder buff 40
Away from

Next, when the motor 26 is driven, the rotation thereof is transmitted to the rotating shaft 21 via the output shaft 28, the pulley 29, the V-belt 31, and the pulley 30, so that the rotating shaft 21 and the cylindrical buff 40 are fixed. Are integrally rotated at the speed of. Similarly, if the motor 54 is driven, the rotation of the output shaft 55, the pulley 56, the belt 57 and the pulley 5
The rotation of the rotation shaft 51 is further transmitted to the suction plate 59 via the pin 62, and the rotation of the rotation shaft 51 is further transmitted to the suction plate 59 via the pin 62.
And the wafer W is rotationally driven at a predetermined speed.

Thereafter, when the motor 26 is driven, the output shaft 27 rotates in a predetermined direction, and the slider 24 screwed into the screw portion 27a of the output shaft 27 descends.
The rotating shaft 21 held by the slider 24 also descends together with the outer cylinder buff 40. At this time, the height position of the outer cylinder buff 40 is detected by the position sensor 32, and a detection signal of the position sensor 32 is sent to the controller 50, and the controller 50 receives this detection signal and When the uppermost processing groove 40a formed on the outer periphery of the shape buff 40 coincides with the height position of the wafer W,
A control signal is sent to the motor 25 to stop driving the motor 25. Then, the cylindrical full-shaped buff 40 is driven to rotate in a state where the uppermost processing groove 40a coincides with the height position of the wafer W. Even if the rotating shaft 21 is lowered as described above, since the pulley 30 is spline-fitted to the rotating shaft 21, the height position of the pulley 30 is unchanged, and the rotation of the motor 26 is It is transmitted to the rotating shaft 21 through the V-belt 31 and the pulley 30 without any problem.

When the cylinder 71 of the wafer pressing means 70 is driven to extend the rod 71a from the above state, the pusher 72 is pushed by the rod 71a and the suction plate 5 is pushed.
In order to move in nine directions, the arm 74 held by the pusher 72 presses the suction plate 59 and the wafer W in the direction of the outer cylinder buff 40 via a roller 76 attached to the tip of the arm 74, and the suction plate 59 and the wafer W are moved in the direction of the outer cylinder buff 40 and the outer peripheral chamfered portion W1 of the wafer W is pressed by the uppermost processing groove 40a, and the outer peripheral chamfered portion W1 is slid relative to the processing groove 40a. Mirror polished. Although not shown, the outer peripheral chamfered portion W1 of the wafer W during the polishing process.
Is supplied with a slurry.

As described above, since the included angle θ1 of the uppermost processing groove 40a is set to 20 °, as shown in FIG.
As shown in FIG.
A portion in contact with the straight line a at 1 = 20 ° is first mirror-polished by the uppermost processing groove 40a.

When the mirror polishing by the uppermost processing groove 40a is completed as described above, the driving of the cylinder 71 of the wafer pressing means 70 is released. Then, the suction plate 59 and the wafer W are moved to a position where the centers thereof coincide with the center of the rotary shaft 51 by the centering action of the leaf spring 61, and the wafer W is separated from the outer cylinder overall buff 40.

Next, the controller 50 controls the motor 25
To drive the motor 25 to lower the rotary shaft 21 and the outer cylinder buff 40 by the same operation as described above. At this time, the amount of descent (the amount of movement in the axial direction) of the outer cylinder buff 40 is detected by the position sensor 32, and the detection signal is transmitted to the controller 50. The controller 50 calculates the descending amount of the outer cylinder buff 40 based on the detection signal from the position sensor 32, and reaches a predetermined value (pitch P1 between the uppermost processing groove 40a and the second processing groove 40b). That is, that is, the second stage processing groove 40b
At the time when the position of the motor 2 coincides with the height position of the wafer W,
The control signal is sent to the control unit 5 to stop the driving of the motor 25 to stop the outer cylinder buff 40 at that position. When the wafer pressing means 70 is driven again in this state, the outer peripheral chamfered portion W1 of the wafer W is pressed by the second-stage processing groove 40b, and is mirror-polished by the processing groove 40b.

Since the included angle θ2 of the second processing groove 40b is set to 40 ° as described above,
As shown in FIG.
2 = 40 ° straight line b is the second step machining groove 4
0b is mirror-polished.

Thereafter, the outer chamfered portion W of the wafer W is similarly set.
1 is sequentially pressed into the third processing groove 40c and the lowest straight processing groove 40d, the outer peripheral chamfered portion W1 is sequentially mirror-polished by the third processing groove 40c and the lowest processing groove 40d. As shown in FIG. 4, a portion of the outer peripheral chamfered portion W1 of the wafer W which contacts the straight line c having the included angle θ3 = 60 °,
The portions (outer peripheral edges) that contact the straight line d at θ4 = 180 ° are sequentially mirror-polished by the processing grooves 40c and 40d.

As described above, according to this embodiment, the outer peripheral chamfered portion W1 of the wafer W is mirror-polished sequentially by the plurality of processing grooves 40a, 40b, 40c, 40d having different cross-sectional shapes. No unpolished portion remains on the outer peripheral chamfered portion W1, and the entire surface of the outer peripheral chamfered portion W1 is uniformly and smoothly mirror-polished, thereby improving the quality of the wafer W.

Further, in this embodiment, since the mirror-type polishing employs a general buffing method in which the structure of the apparatus is simplified, the mirror-polishing can be performed at low cost.

Further, in this embodiment, as the material of the outer cylinder buff 40, a relatively hard elastic material such as a hard polyurethane resin or a synthetic leather made of the same resin, a polyester resin, or a fluororesin is used. Therefore, the wear of the outer cylinder buff 40 can be reduced to extend the life thereof.

By the way, in the above embodiment, the outer cylinder contact type polishing method using the outer cylinder overall buff 40 having a plurality of processing grooves 40a to 40d formed on the outer periphery is employed. A plurality of processing grooves 40a ', 40
If the inner cylinder contact type polishing method using the inner cylinder total buff 40 'formed by forming b', 40c ', and 40d' is adopted, the processing grooves 40a 'to 40d' of the outer peripheral chamfered portion W1 of the wafer W are provided.
Since the contact width with respect to the contact area increases and the polishing rate theoretically increases, the effect of shortening the processing time and increasing the productivity is also obtained.

[0046]

As is apparent from the above description, according to the present invention, the outer peripheral chamfered portion of the wafer is mirror-polished by a plurality of processing grooves having different cross-sectional shapes. The polished portion does not remain, and the entire surface of the outer peripheral chamfered portion is evenly mirror-finished, so that the quality of the wafer is improved.

Further, since the present invention employs a general buffing method in which the structure of the apparatus is simplified, mirror polishing can be performed at low cost.

Further, in the present invention, a relatively hard elastic material such as a hard polyurethane resin or a synthetic leather made of the same resin, a polyester resin, or a fluororesin can be used as the material of the cylindrical buff. The wear of the cylindrical buff can be kept small and the life thereof can be extended.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of a mirror polishing apparatus according to the present invention.

FIG. 2 is a vertical sectional view of a buff drive device of the mirror polishing device according to the present invention.

FIG. 3 is a sectional view taken along line AA of FIG. 1;

FIG. 4 is a sectional view of an outer peripheral chamfered portion of the wafer.

FIG. 5 is a vertical cross-sectional view of an inner cylinder buff according to a modified embodiment of the present invention.

FIG. 6 is a perspective view showing a conventional outer cylinder contact type polishing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mirror polishing apparatus 25 Motor (buff moving means) 26 Motor (buff rotating means) 40 Outer cylinder buff (cylindrical buff) 40 'Inner cylinder buff (cylindrical buff) 40a-40d Machining groove 54 Motor (Wafer rotating means) 70 Wafer pressing means W Wafer W1 Wafer outer peripheral chamfer

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hiroshi Kono 150 Odakura Osaikura, Nishigo-mura, Nishishirakawa-gun, Fukushima Prefecture Examiner Tsutomu Iwamoto, Semiconductor Shirakawa Research Institute, Shin-Etsu Semiconductor Co., Ltd. (56) References JP-A-64-20958 (JP, A) JP-A-3-26459 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 21/304 B24B 9/00

Claims (5)

(57) [Claims] 1. A method in which a chamfered portion of a rotating wafer is sequentially pressed into a plurality of processing grooves having different cross-sectional shapes formed in a multistage cylindrical buff in a multi-stage manner, and the entire chamfered portion of the wafer is mirror-polished. Characteristic mirror polishing method for wafer chamfer. 2. A cylindrical buff formed by forming a plurality of processing grooves having different cross-sectional shapes in multiple stages, a buff rotating means for rotating and driving the cylindrical buff, and the cylindrical buff in the axial direction. Buff moving means, wafer rotating means for holding and rotating the wafer, and wafer pressing means for pressing the wafer against each processing groove of the cylindrical general shape buff. Polishing machine for wafer chamfering. 3. The mirror polishing of a wafer chamfered part according to claim 2, wherein said cylindrical buff is an outer cylinder buff formed by forming said plurality of processing grooves on an outer peripheral portion thereof. apparatus. 4. The mirror surface of a wafer chamfered part according to claim 2, wherein said cylindrical overall shape buff is an inner cylinder overall shape buff formed by forming said plurality of processing grooves on an inner peripheral portion thereof. Polishing equipment. 5. The apparatus according to claim 2, further comprising a position sensor for detecting an axial movement of said cylindrical buff, and a control means for controlling said buff moving means based on a value detected by said position sensor. 5. The mirror polishing device for a wafer chamfer according to claim 3, 3 or 4.