JPH09285957A - Abrasive material and polishing method and device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely prevent the scratching of a semiconductor wafer caused by the intrusion of foreign objects in chemical machine polishing. SOLUTION: In addition to abrasive particles 9 as main components for an abrasive material KZ, resin particles 10 such as a polyurethane resin are mixed into the abrasive material KZ used for chemical machine polishing. When the intrusion of a foreign object 11 occurs during polishing, the foreign object 11 is moved into a gap produced by the resin particles 10 and prevented from being brought into contact with the main surface of a semiconductor wafer W, and thus scratching is prevented. Since the abrasive particles 9 are smaller than the resin particles 10 and the foreign object 11 and light in weight, the abrasive particles 9 are moved to the upper side of the resin particles 10 and compressed by the resin particles 10 and the semiconductor wafer W and thereby polishing is performed. Also, since the resin particles 10 are accumulated on a polishing pad 3 during polishing and the pad 3 contacted with the semiconductor wafer W is always kept to be an activated surface, sharpening is made unnecessary.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abrasive, a polishing method and an apparatus using the same, and more particularly to a technique effectively applied to prevent scratches in chemical mechanical polishing.

[0002]

2. Description of the Related Art Chemical mechanical polishing (CM) is one of planarization techniques for realizing highly reliable multilayer wiring of semiconductor devices.
P: Chemical Mechanical Pol
Ishing).

According to a study made by the present inventor, a polishing apparatus for performing chemical mechanical polishing presses a polishing pad, which is supplied to a surface to be polished by a chemical polishing material, against a semiconductor wafer and mechanically scrapes it. The wiring interlayer insulating film is flattened.

Further, the polishing apparatus is provided with a dresser, and so-called dressing is performed to remove the surface of the polishing pad damaged by the polishing of the semiconductor wafer by the dresser. A new pad is being replaced when it has worn out to the specified thickness.

As an example in which this type of polishing apparatus is described in detail, December 4, 1995, published by Kogyo Kenkyukai Co., Ltd., Masashi Oshima (ed.), December issue of electronic materials, "Super LSI Manufacturing. Test apparatus guidebook <1996 edition> ”P19 to P22, and this document describes the current state and trends of the chemical mechanical polishing apparatus.

[0006]

However, the present inventor has found that the polishing technique using the above-described polishing apparatus has the following problems.

That is, if a foreign substance larger than the particles of the abrasive is mixed between the polishing pad and the semiconductor wafer, scratches are generated on the surface of the semiconductor wafer and the flatness is impaired. is there.

There is also a problem that the operating rate of the polishing apparatus is not improved because it takes time to dress and replace the polishing pad.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an abrasive material capable of reliably preventing a semiconductor wafer from being scratched due to the inclusion of foreign matter in chemical mechanical polishing, and a polishing method and apparatus using the same.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0011]

SUMMARY OF THE INVENTION Among the inventions disclosed in the present application, the outline of a representative one will be briefly described.
It is as follows.

That is, the abrasive of the present invention is an anti-scratch particle having a diameter larger than the particle of the abrasive used for chemical mechanical polishing of semiconductor wafers to prevent scratches caused by rubbing of foreign matter. Is mixed.

As a result, foreign matter can be prevented from entering the gap created by the scratch-preventing particles and scratching the semiconductor wafer during polishing.

Further, in the polishing material of the present invention, the scratch preventing particles are made of the same material as the polishing pad for polishing the semiconductor wafer.

As a result, it is not necessary to sharpen the polishing pad, the apparatus can be simplified, and the polishing pad can be prevented from being damaged, so that the polishing pad replacement cycle can be extended.

Further, in the abrasive of the present invention, the scratch-preventing particles are made of a resin softer than that of the semiconductor wafer.

As a result, it is not necessary to sharpen the polishing pad, the apparatus can be simplified, and the polishing pad can be prevented from being damaged, so that the polishing pad replacement cycle can be extended.

Further, in the abrasive of the present invention, the scratch preventing particles are made of polyurethane resin.

This also eliminates the need for sharpening the polishing pad, simplifies the apparatus, and suppresses damage to the polishing pad by the polishing material, so that the polishing pad replacement cycle can be prolonged and foreign matter can be prevented. It is possible to prevent scratches on the semiconductor wafer due to.

Further, according to the polishing method of the present invention, particles larger than the polishing particles for polishing the semiconductor wafer and softer than the semiconductor wafer or particles made of the same material as the polishing pad are provided on the polishing pad for polishing the semiconductor wafer. The semiconductor wafer is polished on the polishing pad while supplying the mixed abrasive.

As a result, foreign matter can be prevented from entering the gap created by the scratch-preventing particles and scratching the semiconductor wafer during polishing.

Further, the polishing method of the present invention is made of the same material as a polishing platen to which a polishing pad for polishing a semiconductor wafer is attached, and a polishing plate having dimples or grooves formed on its main surface The semiconductor wafer is polished on the polishing plate while supplying an abrasive containing particles larger than the abrasive particles to be polished and softer than the semiconductor wafer or particles made of the same material as the polishing pad.

As a result, a polishing pad for polishing a semiconductor wafer is not required, and the cost of the device can be reduced.

Further, in the polishing apparatus of the present invention, a polishing plate made of the same material as the polishing plate and having dimples or grooves is provided on the polishing plate on which a polishing pad for polishing a semiconductor wafer is attached. A semiconductor wafer is chemically mechanically polished by a polishing plate.

As a result, since the polishing is performed on a hard polishing plate, the flatness of polishing can be greatly improved, and a polishing pad for polishing a semiconductor wafer is not required, so that the cost of the apparatus can be reduced. it can.

As described above, the operating rate of the polishing apparatus can be increased, and the product quality and productivity can be improved.

[0027]

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

(Embodiment 1) FIG. 1 is a structural explanatory view of a chemical mechanical polishing apparatus according to Embodiment 1 of the present invention, and FIG.
FIG. 3 is a schematic explanatory view showing an enlarged main part at the time of polishing a semiconductor wafer using an abrasive material mixed with resin particles according to Embodiment 1 of the present invention. FIG. 3 shows a chemical mechanical polishing apparatus studied by the present inventor. FIG. 4 is a schematic explanatory comparison diagram showing an enlarged main part of a semiconductor wafer during polishing, and FIG. 4 shows deposition of resin particles mixed in a polishing material mixed with resin particles on a polishing pad according to Embodiment 1 of the present invention. It is a schematic explanatory view.

In the first embodiment, a chemical mechanical polishing device (polishing device) 1 for flattening a wiring interlayer insulating film and the like.
Is provided with a disk-shaped surface plate 2 made of ceramic or the like in the central portion, and the upper surface of the surface plate 2 is for polishing the semiconductor wafer W and is also like a disk-shaped polishing pad made of polyurethane, for example. 3 is provided.

Further, a cylindrical support portion 4 connected to a drive portion such as a motor is provided at the center of the surface plate 2, and the polishing pad 3 is rotated in a predetermined direction by driving this drive portion. Is supposed to do.

Next, a chemical mechanical polishing device (hereinafter referred to as CMP
1), a polishing material supply nozzle 5 for supplying the polishing material KZ is provided above the center of the polishing pad 3, and the polishing material supply nozzle 5 stores the polishing material KZ. The abrasive material KZ is connected to the abrasive material storage tank, and the abrasive material KZ is supplied from the tank to the abrasive material supply nozzle 5 by a pump or the like.

Further, in the CMP apparatus 1, a polishing head portion 6 for polishing while fixing the semiconductor wafer W is provided at a predetermined position above the polishing pad 4.

Further, the CMP apparatus 1 includes a polishing pad 4
The cleaning head portion 7 for cleaning the
The cleaning head portion 7 is disposed above the cleaning head portion 6 and is symmetrical to the polishing head portion 6.

Next, the polishing head portion 6 is provided with a circular back pad 6a having a diameter similar to that of the semiconductor wafer W to be fixed, and the back pad 6a is, for example, a vacuum chuck of the semiconductor wafer W. A chuck mechanism for holding by such means is provided.

A ring-shaped guide ring 6b for guiding the semiconductor wafer W during polishing is provided on the circumference of the back pad 6a.

Further, the back pad 6a and the guide ring 6b are the same as the disk-shaped wafer carrier 6c.
Attached to. Then, the wafer carrier 6c
Has a lower part made of ceramic and an upper part made of stainless steel, and has a back pad 6a and a guide ring 6
The part to which b is attached is made of ceramic.

A cylindrical support portion 6d is provided at the center of the upper surface of the upper surface of the wafer carrier 6c made of stainless steel.
Is connected to one end thereof, and the other end of the support portion 6d is connected to a drive unit including a motor and a gear.

Then, by driving a driving unit connected to the other end of the supporting unit 6d, the supporting unit 6d
Can be rotationally driven in the vertical direction, the radial direction, and a predetermined direction.

Next, the cleaning head portion 7 includes the polishing pad 3
The polishing pad brush 7a, which is a nylon brush, for example, is provided in the lower portion. Also,
One end of a cylindrical support 7b is connected to the center of the upper surface of the polishing pad brush 7a, and the other end of the support 7b is also driven by a motor and a gear. Parts are connected.

Then, the driving portion connected to the other end of the supporting portion 7b is driven to move the supporting portion 7b in the vertical direction.
Rotational drive can be performed in the radial direction as well as in a predetermined direction.

Further, the CMP apparatus 1 is provided with a housing 8 provided so as to cover the polishing pad 3 in order to prevent the polishing material KZ from scattering.

Next, the operation of this embodiment will be described.

First, the semiconductor wafer W is located above the polishing pad 3 by a predetermined transfer system.
Is conveyed to and is clamped by the back pad 6a.

Then, the polishing pad 3 is rotated in a predetermined direction by the above-mentioned drive unit provided at the bottom of the surface plate 2.

Further, the polishing material supply nozzle 5 located at the center of the polishing pad 3 constantly discharges the polishing material KZ to the rotating polishing pad 3 by the above-mentioned pump,
It is uniformly supplied to the surface of the polishing pad 3.

After that, the supporting portion 6 in the polishing head portion 6
The driving unit provided in d is driven to lower the semiconductor wafer W fixed to the back pad to start polishing.

During polishing, the semiconductor wafer W is oscillated while being pressed in the predetermined direction by the drive unit provided in the supporting portion 6d and being pressed against the polishing pad 3 with a predetermined pressure.

Further, the hardness of the polishing pad 3 can be prevented from scratching the semiconductor wafer by the polishing material KZ which will be described later. Therefore, a harder pad than usual is used to improve the flatness by polishing. There is.

Here, the polishing material KZ for polishing the semiconductor wafer W will be described.

As shown in FIG. 2, this abrasive KZ contains resin particles (scratch) for preventing scratches in addition to abrasive particles 9 such as colloidal silica and alumina, which are the main components of ordinary abrasives KZ. The prevention particles) 10 are mixed.

Further, the resin particles 10 are particles equivalent to or softer than the semiconductor wafer W to be polished, and particles having a diameter larger than the diameter of the foreign matter 11 which is estimated to enter suddenly, such as polyurethane resin. To use.

Here, FIG. 3 shows a comparative example in polishing the semiconductor wafer W of the chemical mechanical polishing apparatus examined by the present inventor.

First, when the semiconductor wafer W is polished by using the abrasive KZ1 in which the resin particles 10 (FIG. 2) are not mixed, if the foreign matter 11 gets into the abrasive KZ1, for example, the abrasive If the foreign matter 11 is larger than the abrasive particles 9 such as colloidal silica or alumina, which is the main component of KZ1, the foreign matter 11 comes into contact with the main surface of the semiconductor wafer W, which causes scratches.

However, when polishing the semiconductor wafer W, the foreign matter 1
1 has entered and remains on the polishing pad 3,
As shown in FIG. 2, when the resin particles 10 are mixed in the abrasive KZ, the foreign particles 11 are smaller than the resin particles 10, so that the foreign particles 11 enter the space created by the resin particles 10 and the main surface of the semiconductor wafer W This prevents contact with the scratches and prevents scratches.

Further, since the abrasive particles 9 are smaller than the resin particles 10 and the foreign matters 11 and are light in weight, the abrasive particles 9 constantly move above the resin particles 10 to cause the resin particles 1 to move.
0 and the semiconductor wafer W are compressed and the semiconductor wafer W is polished.

Further, an abrasive material K containing resin particles 10 mixed therein.
By polishing with Z, as shown in FIG.
The resin particles 10 are deposited on the polishing pad 3 during polishing, and the polishing pad 3 with which the semiconductor wafer W is in contact always has an activated surface, and the polishing particles 9 are efficiently held, so that dressing by a dresser is unnecessary. Becomes

When the polishing of the semiconductor wafer W is completed, the polishing head portion 6 moves to a predetermined position, and the semiconductor wafer W clamped by the back pad 6a is transferred by the above-mentioned transfer system and stored in the predetermined position. It

After that, the drive unit provided on the support unit 7b of the cleaning head unit 7 is driven while being rotated in a predetermined direction by the drive unit provided on the bottom of the surface plate 2 to polish the polishing pad brush 7a. To lower.

Then, the drive unit provided on the support portion 7b causes the polishing pad brush 7a to be pressed against the polishing pad 3 with a predetermined pressure and to swing in a predetermined direction to perform a swinging motion to clean the polishing pad 3. To start.

Therefore, in the first embodiment,
By mixing the resin particles 10 into the abrasive KZ,
Even if foreign matter enters during polishing, it is possible to prevent scratches from occurring on the main surface of the semiconductor wafer W due to the foreign matter.

Further, since scratches can be prevented, a harder polishing pad 3 can be used, and the flatness of the semiconductor wafer W can be improved.

Further, since the resin particles 10 activate the surface of the polishing pad 3, dressing by a dresser is unnecessary, the cost can be reduced, and the operating rate of the apparatus can be increased.

(Embodiment 2) FIG. 5 is an enlarged schematic explanatory view of a main part when a semiconductor wafer is polished using an abrasive material mixed with resin particles according to Embodiment 2 of the present invention.

In the second embodiment, the CMP device 1
For example, hemispherical dimples 12 are formed on the entire main surface of a disk-shaped surface plate (polishing plate) 2a made of ceramic or the like provided in (FIG. 1).

Although the dimples 12 are formed on the main surface of the surface plate 2a in this case, a disk-shaped disc (polishing disk) made of the same material as the surface plate 2a is attached to the main surface of the surface plate 2a. Hemispherical dimples may be formed on the main surface of the disk.

At the time of polishing the semiconductor wafer W, the semiconductor wafer W is polished using the polishing material KZ mixed with the resin particles 10 such as polyurethane resin as in the first embodiment.

The depth of the dimples 12 formed on the entire main surface of the surface plate 2a is about the radius of the resin particles 10, and the size of the dimples 12 is slightly larger than the diameter of the resin particles 10. The formation is performed so that one particle enters one dimple 12.

Therefore, when the resin particles 10 mixed in the abrasive KZ enter the dimples 12 during polishing, the surface of the surface plate 2a becomes rough, that is, the surface becomes the same as the state of sharpening, and the dimples 12 are formed. The abrasive particles 9 in the abrasive KZ are held by the resin particles 10 that have entered, and the semiconductor wafer W can be satisfactorily abraded.

As a result, in the second embodiment, by using the surface plate 2a having the dimples 12 formed thereon, a polishing pad and a dresser for setting up the polishing pad can be dispensed with, and the cost of the apparatus can be greatly reduced. You can

Further, since it is not necessary to replace the dresser and the polishing pad, the operating rate of the apparatus can be greatly improved.

Although the invention made by the present inventor has been specifically described based on the embodiments of the present invention, the present invention is not limited to the above embodiments, and various modifications are possible without departing from the scope of the invention. It goes without saying that it can be changed.

For example, in the first and second embodiments, the polyurethane resin is used as the resin particles mixed with the abrasive.
A semiconductor wafer can be satisfactorily polished as long as it is made of particles having a diameter equal to or softer than that of the semiconductor wafer to be polished and larger than the diameter of a foreign substance which is estimated to enter suddenly.

Further, in the second embodiment, the surface of the surface plate is made to be the same as the state where the surface of the surface plate is sharpened by forming the dimples on the surface plate, but the surface shape of the surface plate is such that the dimples are the surface of the surface plate. It may have any shape as long as it enters and is fixed. For example, a groove may be formed in the surface plate, and resin particles may be allowed to enter the groove to make the dressing the same.

At this time, the depth of the groove formed on the surface plate is about the radius of the resin particles, and the width of the groove is formed so as to be slightly larger than the diameter of the resin particles. It is possible to efficiently make the surface of the surface plate the same as when the resin particles enter and the surface of the surface plate is sharpened.

[0075]

Advantageous effects obtained by typical ones of the inventions disclosed by the present application will be briefly described as follows.
It is as follows.

(1) According to the present invention, it is possible to prevent the semiconductor wafer from being scratched at the time of polishing, and to suppress the damage to the polishing pad.

(2) Further, in the present invention, by mixing the scratch-preventing particles into the abrasive, it is not necessary to sharpen the polishing pad, and the cost of the apparatus and the operating rate of the apparatus can be increased.

(3) Further, in the present invention, since polishing is performed on a hard polishing plate, the flatness of polishing can be greatly improved, and a polishing pad for polishing a semiconductor wafer is not required, so that the cost of the apparatus can be reduced. It can be performed.

(4) According to the present invention, the above (1)
Through (3), the quality and productivity of products such as semiconductor devices can be improved.

[Brief description of drawings]

FIG. 1 is a structural explanatory view of a chemical mechanical polishing apparatus according to a first embodiment of the present invention.

FIG. 2 is an enlarged schematic explanatory view of a main part when polishing a semiconductor wafer using a polishing material mixed with resin particles according to the first embodiment of the present invention.

FIG. 3 is a schematic explanatory comparison view in which an essential part of a chemical mechanical polishing apparatus examined by the present inventors during semiconductor wafer polishing is enlarged.

FIG. 4 is a schematic explanatory view showing deposition of resin particles mixed in a polishing material mixed with resin particles according to Embodiment 1 of the present invention on a polishing pad.

FIG. 5 is an enlarged schematic explanatory view of a main part when polishing a semiconductor wafer using a polishing material mixed with resin particles according to a second embodiment of the present invention.

[Explanation of symbols]

 1 chemical mechanical polishing device (polishing device) 2 surface plate 2a surface plate (polishing plate) 3 polishing pad 4 support part 5 abrasive material supply nozzle 6 polishing head part 6a back pad 6b guide ring 6c wafer carrier 6d support part 7 for cleaning Head part 7a Polishing pad brush 7b Support part 8 Housing 9 Abrasive particles 10 Resin particles (scratch prevention particles) 11 Foreign matter 12 Dimples KZ Abrasives W Semiconductor wafer KZ1 Abrasives

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinichiro Mitani 2326 Imai, Ome-shi, Tokyo Hitachi, Ltd. Device Development Center

Claims (7)

[Claims] 1. An abrasive used for chemical mechanical polishing of a semiconductor wafer, comprising scratch-preventing particles having a diameter larger than that of the abrasive particles for preventing scratches caused by rubbing foreign substances on the semiconductor wafer. Abrasive material characterized by being mixed. 2. The polishing material according to claim 1, wherein the scratch-preventing particles are made of the same material as a polishing pad for polishing the semiconductor wafer. 3. The abrasive according to claim 1, wherein the scratch prevention particles are made of a resin softer than the semiconductor wafer. 4. The abrasive according to claim 3, wherein the scratch prevention particles are made of polyurethane resin. 5. A polishing method for chemically mechanically polishing a semiconductor wafer, comprising particles larger than polishing particles for polishing the semiconductor wafer and softer than the semiconductor wafer on a polishing pad for polishing the semiconductor wafer. Alternatively, the polishing method is characterized in that the semiconductor wafer is polished on the polishing pad while supplying a polishing material in which particles made of the same material as the polishing pad are mixed. 6. A polishing method for chemically mechanically polishing a semiconductor wafer, which is made of the same material as a polishing platen to which a polishing pad for polishing the semiconductor wafer is attached, and has dimples or grooves formed on its main surface. On the polishing plate, while supplying to the polishing plate a polishing material in which particles larger than the polishing particles for polishing the semiconductor wafer and softer than the semiconductor wafer or particles made of the same material as the polishing pad are mixed. A polishing method comprising polishing the semiconductor wafer. 7. A polishing apparatus for chemically mechanically polishing a semiconductor wafer, comprising a polishing platen to which a polishing pad for polishing the semiconductor wafer is attached, the plate being made of the same material as the polishing platen, and having dimples or grooves. A polishing apparatus having a polishing plate formed with the above, and polishing the semiconductor wafer by the polishing plate.