JPH07299732A - Wafer polishing method and polishing apparatus - Google Patents

Abstract

PURPOSE:To provide a wafer polishing method and a device for it, with which the quality of a wafer can be enhanced by performing the polishing operations in accordance with the circuit pattern which the device is embodied in a small construction. CONSTITUTION:The surface of a wafer 3 to be polished is put in pressure contact with the polishing surface 4a of a polishing machine 4 which is revolved horizontally in such a condition that a polish is interposed, and the wafer 3 is moved horizontally with a scope adjusted selectively in excess of the revolutional center C of the polishing surface 4a, and thereby the polishing surface 4a is made smaller in the diameter so that the polishing device 10 is embodied in a small construction, and the opimum sliding direction, speed, etc., of the polishing surface 4a relative to the wafer 3 are selected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing method and a polishing apparatus for polishing the surface of a semiconductor wafer or the like forming an integrated circuit.

[0002]

2. Description of the Related Art In recent years, semiconductor wafers for manufacturing integrated circuits such as LSIs (hereinafter simply referred to as "wafers") have been polished to have a highly accurate and defect-free surface in accordance with miniaturization of devices. Has come to be required. This polishing mechanism is based on a mechano-chemical polishing method that combines a mechanical element such as fine particle silica and an etching element with an alkaline solution. Therefore, since the properties of the polishing agent and the polishing pad are the main factors that determine the surface condition of the wafer, many improvements have been made in the past. However, recent wafer precision,
In particular, the importance of the polishing apparatus is increasing with respect to demands such as improvement of flatness.

FIG. 4 is a diagram showing the structure of a conventional wafer polishing apparatus 1, in which reference numeral 2 is a head for holding a wafer 3.
4 is a platen (polishing plate). The head 2 has a plurality of wafer carriers 5 in its lower part, and holds the wafers 3 vacuum-adsorbed by the respective wafer carriers 5 in a horizontal state with the surfaces to be polished facing downward.

Further, the platen 4 has a disk-shaped polishing surface 4a that can be horizontally swung, and has a radius dimension larger than the diameter dimension of the head 2, as shown in FIG. The polishing cloth 4b attached to the upper surface of the wafer 3 is pressed against the surface 3a to be polished of the wafer 3 supported by the head 2 in a region not including the center of rotation C. Between the wafer 3 and the platen 4, the abrasive S discharged from the supply port 6 arranged above the rotation center C of the platen 4 is caused to flow radially outward by the centrifugal force of the platen 4. Are being supplied.

According to the polishing apparatus 1 thus constructed, the platen 4 is horizontally swiveled and the head 2 is rotated to rotate the platen 4 so that the polishing surface 4a of the platen 4 is pressed against the polishing surface 3a of the wafer 3. Are slid relative to the polishing surface 4a of the platen 4. Then, during the sliding, the wafer 3 is polished by the action of the abrasive S supplied between the wafer 3 and the platen 4.

[0006]

By the way, as the wafer 3 to be polished by the polishing apparatus 1, in addition to the wafer 3 before the circuit pattern is mounted, a circuit pattern of a predetermined form is mounted and silicon is mounted thereon. There is a wafer 3 coated with a coating. In the wafer 3 on which the circuit pattern is mounted as described above, the film quality of the silicon coating is different depending on the circuit pattern. Therefore, the polishing work needs to be appropriately adjusted according to the circuit pattern.

However, the conventional polishing apparatus 1 described above is used.
Then, the head 2 only rotates at a predetermined position of the platen 4, the polishing work is uniform and there is no room for adjustment, and the same polishing work must be performed on all types of circuit patterns. There was the inconvenience of having to do it.

In order to solve this, as shown in FIG. 5, a method of mounting the head 2 on the tip of a revolving arm 7 such as a tone arm of a record player can be considered. However, in this case, since the rotation speed of the polishing cloth 4a becomes zero at the rotation center C of the platen 4, it is difficult to sufficiently secure the relative speed of the platen 4 to the wafer 3 in this region, and the polishing is difficult. The accuracy may decrease. Therefore, the head 2 has a center of rotation C of the platen 4.
Therefore, it is necessary to avoid the above and swing the swing arm 7 in both areas arranged on one side with respect to the swing center C. But,
In this case, in order to secure a considerable polishing area, the diameter of the platen 4 needs to be large, and the device becomes large. As a result, there is a problem that the equipment cost increases with the increase of the installation area.

The present invention has been made in view of the above-mentioned circumstances, and is capable of improving the quality of the wafer by adjusting the polishing method according to the circuit pattern while reducing the size of the apparatus. It is an object to provide a method and a polishing device.

[0010]

In order to achieve the above object, the present invention is such that the surface to be polished of a wafer is pressed against the polishing surface of a horizontally rotating polishing table with an abrasive agent interposed therebetween, and A wafer polishing method is proposed in which the wafer is horizontally moved beyond the center of rotation of the polishing surface and the horizontal movement range is selectively adjusted.

Further, according to the present invention, a polishing platen for horizontally rotating a disk-shaped polishing surface arranged horizontally, a head arranged near the upper part of the polishing plate for supporting a wafer at a lower end thereof, and a head for lowering the head part are provided. Pressing means for urging the wafer to press the wafer against the polishing surface, moving means for horizontally moving the head within the range of the polishing surface, and polishing agent supplying means for supplying the polishing agent between the wafer and the polishing table. And a non-contact region that does not contact the wafer is provided in the vicinity of the center of rotation of the polishing surface of the polishing plate, and the moving unit moves the head along a locus passing through the center of rotation of the polishing surface. A wafer polishing device is proposed.

Further, in the above polishing apparatus, it is effective that the moving means comprises a moving range selecting means for selectively setting the moving range of the head.

[0013]

According to the method of polishing a wafer according to the present invention, the surface to be polished of the wafer is brought into pressure contact with the polishing surface of the horizontally rotating polishing disk with the polishing agent interposed between the wafer and the polishing surface. The surface of the wafer to be polished is polished by the action of the polishing agent accompanying the mutual movement of the wafers. In this case, since the wafer is horizontally moved beyond the center of rotation of the polishing surface, a sufficiently long moving distance is secured over the entire area of the polishing surface. This makes it possible to reduce the outer diameter of the polishing plate. Further, if the moving range is selectively adjusted, it becomes possible to select the optimum polishing method according to the circuit pattern.

Further, according to the wafer polishing apparatus of the present invention, the wafer supported by the head is brought close to the polishing surface of the horizontally rotating polishing disk, and the pressing means is operated to press the wafer against the polishing surface. At the same time, the polishing means is supplied by the polishing agent supply means while the moving means is operated to move the head horizontally, so that the surface to be polished of the wafer is polished. In this case, since the moving means horizontally moves the head along the locus passing through the center of rotation of the polishing surface, a sufficient movement distance of the wafer can be secured. Moreover,
The non-contact area provided on the polishing surface prevents the wafer from coming into contact with the vicinity of the center position of the polishing surface having a low turning speed.

Further, if the polishing apparatus is provided with a moving range selecting means, it becomes possible to arbitrarily set the moving distance of the wafer by activating the moving range selecting means, and the optimum polishing can be performed according to the circuit pattern. The quality of the wafer will be improved.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a wafer polishing method and a polishing apparatus according to the present invention will be described below with reference to FIGS. In the polishing apparatus of this embodiment, the same reference numerals are given to portions having the same configuration as the conventional polishing apparatus shown in FIGS. 4 and 5, and the description will be simplified.

In the method of polishing the wafer 3 according to this embodiment, the surface 3a to be polished of the wafer 3 is pressed against the polishing surface 4a of the platen 4 (polishing disk) which can be horizontally rotated with the abrasive S interposed. At the same time, the wafer 3 is horizontally moved beyond the turning center C of the polishing surface 4a, and the horizontal movement range is selectively adjusted. This polishing method is specifically realized by the polishing apparatus 10 having the configuration shown in FIGS. 1 to 3.

Wafer 3 polishing apparatus 10 according to the present embodiment
As shown in FIG. 2, a disk-shaped platen 4 having a horizontal polishing surface 4a, a head 11 arranged above the platen 4 for supporting the wafer 3 in a sucked state, and a head 11 capable of horizontally rotating at its tip. The mounting platen 4 is provided with a revolving arm 13 that horizontally swings around a support shaft 12 that is erected on the side.

A polishing cloth 4b is attached to the polishing surface 4a of the platen 4. The polishing cloth 4b has a polishing surface 4a.
Except for the vicinity of the center position of the platen 4 which is the turning center C of
It is adhered over the entire polishing surface 4a. That is,
The vicinity of the rotation center C of the polishing surface 4a is a portion where a sufficient rotation speed cannot be obtained even when rotated, and the sliding speed with respect to the wafer 3 is low. Therefore, the polishing cloth 4b in this portion is removed. As a result, the non-contact area 14 where the wafer 3 is not polished is formed.

As shown in FIG. 3, the head 11 has a wafer carrier 15 in its lower part, and the wafer 3 is vacuum-adsorbed by the wafer carrier 15 so that the surface to be polished 3a to be polished faces downward. It is designed to be held horizontally. On the other hand, above the wafer carrier 15,
A pressing means 37 for displacing the wafer carrier 15 downward is provided by supplying a minute air pressure to the pressure chamber 36 from a pressure air source (not shown), and the wafer 3 is pressed against the platen 4 by the operation of the pressing means 37. It has become.

Further, this head 11 is
A head rotating mechanism 16 is provided for horizontally rotating itself about its axis 11a. This head rotation mechanism 16
The motor 17 for horizontally rotating the platen 4 includes a pulley 18, a belt 19, a drive shaft 20, and a pulley 2.
1, the pin 23 on the upper part of the head 11 through the belt 22.
It is configured by connecting the shaft bodies 24 joined by.

An air cylinder 25 is installed at the tip of the revolving arm 13, and when the air cylinder 25 is linked to the shaft 24 of the head 11, the head 11 can be slightly moved in the vertical direction by the operation of the air cylinder 25. It is like this. A drive motor 28 is connected to the swivel arm 13 via a pulley 26 and a belt 27, and the support shaft 12
It can be swung around in a horizontal plane. The drive motor 28 is provided with a control device 29 (moving range selecting means) that arbitrarily sets the swing angle of the swing arm 13 and the swing position with respect to the platen 4. The operator can set the movement range of the revolving arm 13 to an optimum state by the control device 29 according to the circuit pattern mounted on the wafer 3.

As a result, as shown in FIG.
1 is moved with its turning center 11a arranged in a cylindrical surface including the turning center C of the platen 4. That is, the head 11 moves along the arc-shaped miracle passing through the turning center C of the platen 4 along the turning center C of the platen 4.
It can be moved horizontally beyond.

In each of FIGS. 1 to 3, reference numeral 30 is a roller for laterally supporting the head 11, 31 is a nozzle for supplying a slurry-like polishing agent S between the polishing surface 4 a and the wafer 3. , 32 are the roller 30 and the nozzle 31
A support beam for supporting the wafer carrier 33, a diaphragm for moving the wafer carrier 15 up and down, a hole 34 provided in the wafer carrier 15 for vacuum suction of the wafer 3, a retainer 35 for suppressing horizontal movement of the wafer 3, 36 Is a pressure chamber for displacing the diaphragm 33, and 38 is a weight for suppressing the flying of the head.

Wafer polishing apparatus 10 thus configured
In order to polish the wafer 3 by using, the head 11 having the wafer 3 attached thereto is placed on the polishing surface 4 a of the platen 4 by horizontally turning the turning arm 13. Then, while the platen 4 and the head 11 are horizontally swirled, and the polishing agent S is ejected from the nozzle 31, high pressure air is supplied from a pressure air source to lower the wafer carrier 15 and the surface to be polished of the wafer 3. 3a is brought into pressure contact with the polishing surface 4a.

As a result, the platen 4 and the head 11
However, as shown in FIG. 1, the turning arm 13 that supports the head 11 is rotated clockwise, and
It can be rotated about 2. Then, while the head 11, the platen 4, and the swivel arm 13 perform such mutual movement, the wafer 3 is rubbed against the polishing surface 4a of the platen 4 via the abrasive S, and the surface 3a to be polished is polished. Will be done.

In this case, in the polishing apparatus 10 of this embodiment,
Since the head 11 is horizontally moved by the turning arm 13 beyond the turning center C of the polishing surface 4a, the polishing surface 4a
It becomes possible to carry out polishing by effectively utilizing the entire surface of, and it is possible to secure a sufficient movement distance. Conversely, since the diameter of the polishing surface 4a for ensuring a desired moving distance is small, the polishing apparatus 10 itself can be downsized. Here, since the non-contact area 14 is provided in the vicinity of the rotation center C position of the polishing surface 4a that cannot secure a sufficient sliding speed with respect to the wafer 3, the wafer 3
It is possible to maintain the quality of the wafer 3 even if is moved horizontally over the polishing surface 4a beyond the turning center C.

Further, in the polishing apparatus 10 of this embodiment, the turning arm 13 is operated by operating the control device 29.
The rocking angle and rocking position of can be arbitrarily selected.
Thereby, the sliding speed of the polishing surface 4a with respect to the wafer 3,
The sliding direction can be changed to a desired one. As a result, the polishing method that should be set according to various circuit patterns and the like can be set to the optimum one, and the quality of the product can be improved.

In the polishing apparatus 10 of this embodiment, the head 11 is moved horizontally beyond the turning center C of the polishing surface 4a. As a result, the direction of the frictional force acting on the head 11 from the polishing surface 4a is constant. Will not do. However, in the polishing apparatus 10 of this embodiment, the head 11 is the roller 3
Since the head 11 is supported by 0, the head 11 is held so as not to tilt, and the flatness of the polished surface 3a of the wafer 3 can be maintained.

Further, since the head 11 passes through the turning center C of the polishing surface 4a, the supply position of the abrasive S cannot be set above the turning center C as in the conventional case, but in the polishing apparatus 10 of this embodiment. Since the nozzle 31 is provided on the support beam 32 that is swung together with the turning arm 13, the polishing agent S can be reliably supplied between the polishing surface 4 a and the wafer 3.

[0031]

As described above in detail, in the method for polishing a wafer according to the present invention, the surface to be polished of the wafer is pressed against the polishing surface of the horizontally rotating polishing plate with the polishing agent interposed therebetween. Since the wafer is horizontally moved within the range that is selectively adjusted beyond the center of rotation of the polishing surface, it is possible to select the most suitable polishing method according to the circuit pattern etc. mounted on the wafer. There is an effect that the quality of can be improved.

The wafer polishing apparatus according to the present invention is
A polishing table for horizontally rotating the polishing surface, a head for supporting the wafer above it, a pressing means for pressing the wafer against the polishing surface, a moving means for moving the head horizontally, and a polishing table between the wafer and the polishing disk. A polishing agent supply means for supplying a polishing agent, and a non-contact region that does not contact the wafer is provided in the vicinity of the rotation center position of the polishing surface, and the moving means moves the head along the trajectory passing through the rotation center of the polishing surface. Since it is moved, a sufficient movement distance can be secured even if the outer diameter of the polishing surface is reduced. As a result, there is an effect that the device can be downsized and the facility cost can be reduced.

Further, in the above polishing apparatus, if the moving means is provided with moving range selecting means for selectively setting the moving range of the head, in addition to the above effects, sliding of the polishing surface on the wafer is achieved. Since the speed, the sliding direction, and the like can be set to the optimum state, there is an effect that the quality of the wafer can be improved.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of a wafer polishing apparatus according to the present invention.

FIG. 2 is a front view showing the polishing apparatus of FIG.

3 is a vertical cross-sectional view showing the structure near the head of the polishing apparatus of FIG.

FIG. 4 is a vertical sectional view showing a conventional example of a polishing apparatus.

FIG. 5 is a plan view showing another conventional example of the polishing apparatus.

[Explanation of reference numerals] 3 wafer 3a surface to be polished 4 platen (polishing plate) 4a polishing surface 10 polishing device 11 head 13 turning arm (moving means) 14 non-contact area 29 control means (moving range selecting means) 31 nozzle (polishing agent) Supplying means) 37 Pressing means C Swiveling center S Abrasive

Claims (3)

[Claims] 1. A surface to be polished of a wafer is pressed against a polishing surface of a polishing table which can be horizontally rotated while an abrasive is interposed, and the wafer is horizontally moved beyond a center of rotation of the polishing surface, A method of polishing a wafer, characterized in that the horizontal movement range is selectively adjusted. 2. A polishing platen for horizontally rotating a disk-shaped polishing surface arranged horizontally, a head for supporting a wafer at a lower end portion which is arranged close to the polishing platen, and urges the head downward. And pressing means for pressing the wafer against the polishing surface, moving means for moving the head horizontally within the range of the polishing surface, and polishing agent supplying means for supplying the polishing agent between the wafer and the polishing plate. A non-contact region that does not contact the wafer is provided in the vicinity of the center of rotation of the polishing surface of the polishing plate, and the moving unit moves the head along a trajectory passing through the center of rotation of the polishing surface. Wafer polishing device. 3. The wafer polishing apparatus according to claim 2, wherein the moving means is provided with a moving range selecting means for selectively setting a moving range of the head.