JPH07111256A - Semiconductor manufacturing apparatus - Google Patents

Abstract

PURPOSE:To prevent polishing wastes from re-adhering, keep a polishing rate constant and improve the uniformity of a film on a wafer surface by a method wherein abrasive is changed uniformly and the polishing wastes and reaction products produced by a polishing process are prevented from mixing with the abrasive. CONSTITUTION:An endless polishing belt 1 which moves in its longitudinal direction at a constant speed and has a belt-shaped polishing surface whose width is smaller than a wafer diameter, a wafer supporting mechanism 17 which attracts a wafer 16 to be polished and is moved reciprocally in a direction perpendicular to the direction of the belt 11, a washing mechanism 21 which cleans the polishing surface of the belt 11 and is provided on the part of a polishing belt track not in contact with the wafer surface and an abrasive supplying mechanism 22 which supplies the abrasive onto the part of the wafer surface not in contact with the polishing surface of the polishing belt 11 to change the abrasive and, at the same time, clean the wafer surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor manufacturing apparatus, and more particularly, it is used as a polishing apparatus for flattening an element during a wafer process, for example, flattening an interlayer insulating film of a multilayer wiring structure.

[0002]

2. Description of the Related Art FIG. 5 is a sectional view showing the outline of the configuration of a conventional polishing apparatus used for flattening the unevenness of a film on the main surface of a semiconductor wafer in a wafer process. The wafer 2 to be polished is suction-fixed to the suction plate 3 and rotates with the suction plate. Reference numeral 4 is a template that functions as a stopper. A surface plate 6 having a polishing surface 5 containing an abrasive (for example, an alkaline suspension of an abrasive such as silica) is provided eccentrically opposite to the suction plate 3.

At the time of polishing, the wafer 2 is pressed against a surface plate 6 having a polishing surface 5, and at the same time, the wafer 2 itself also rotates, and polishing is performed while eccentric to the rotating surface plate 6. To replace the abrasive, a new abrasive is supplied by spraying the abrasive on a region other than the area where the wafer is pressed and rotating the surface plate 6 itself.

In such a conventional polishing apparatus,
At the time of polishing, the area of contact between the wafer surface and the polishing surface fixed to the surface plate via the polishing material substantially coincides with the wafer surface.

Therefore, at the time of polishing, the exchange of the polishing material between the wafer and the polishing surface is not sufficient, and the tendency is remarkable especially in the central portion of the wafer. Therefore, as the polishing progresses, shavings, reaction products and the like are mixed in the abrasive.

Due to the presence of these shavings and reaction products,
In addition to increasing the non-uniformity of the polishing rate within the wafer surface, post-treatment by shavings and redeposition of reaction products on the wafer surface after completion of polishing is required.

[0007]

As described above, in the conventional polishing apparatus, during polishing, the entire surface of the wafer is polished while being brought into pressure contact with the polishing surface of the surface plate. Therefore, it is very difficult to constantly renew the polishing material between the polishing surface and the entire surface of the wafer.
Since polishing is performed by so-called chemical mechanical polishing, the polishing rate (polishing rate or polishing rate) is different between the polishing surface containing fresh abrasive and the polishing surface containing abrasive mixed with shavings and reaction products. Are very different. For this reason, if the polishing material is not uniformly replaced, the flatness of the film on the surface of the wafer after polishing becomes uneven. Further, there is a problem that shavings and reactive organisms mixed in the polishing material are reattached to the wafer.

An object of the present invention is to uniformly renew the polishing material and to suppress the mixture of the shavings and the reaction products due to the polishing into the polishing material, so that the shavings and the reaction products are regenerated on the wafer. It is an object of the present invention to provide a semiconductor manufacturing apparatus capable of preventing adherence, maintaining a constant polish rate, and improving the uniformity of a film on a wafer surface after polishing.

[0009]

A semiconductor manufacturing apparatus of the present invention is a polishing apparatus for polishing a film formed on a wafer surface by using an abrasive, and (a) forms an endless track at a constant speed in a longitudinal direction. A polishing belt having a strip-shaped polishing surface having a width narrower than the moving wafer diameter, and polishing a film formed on the wafer surface by the polishing surface; and (b) adsorbing a wafer to be polished, rotating and rotating the polishing belt. A wafer supporting mechanism that reciprocates orthogonally to the moving direction; and (c) a mechanism that is provided on a polishing belt track other than a portion of the wafer surface that contacts the surface to be polished and that cleans the polishing surface of the polishing belt. ) A polishing material supply mechanism for discharging the polishing material to the wafer surface not in contact with the polishing surface of the polishing belt to renew the polishing material and clean the wafer surface.

[0010]

In the present invention, instead of the conventional flat polishing surface, a polishing belt having a strip-shaped polishing surface having a width narrower than the wafer diameter (for example, a width of several% of the wafer diameter) is used. Therefore, the area of the wafer surface covered by the polishing belt,
That is, the surface to be polished of the wafer pressed by the polishing surface is strip-shaped and narrow, and the rotation and the reciprocating motion are repeated. On the other hand, a new polishing material is discharged from the polishing material supply mechanism onto the wafer surface not covered with the polishing belt. As a result, the polishing material interposed between the polishing surface of the polishing belt and the surface to be polished of the wafer is constantly and uniformly updated.

Further, since the strip-shaped polishing surface is used instead of the conventional flat polishing surface, a more uniform pressure can be applied to the wafer surface as compared with the conventional case.

Further, the polishing belt passes through a cleaning mechanism provided in the middle of the polishing belt orbit, by which shavings and reaction products adhering to the polishing surface are removed, and a clean polishing surface is always kept on the wafer. Transferred to the surface to be polished.

Further, as described above, since the polishing belt only partially covers the wafer, a sufficient amount of the polishing material is discharged from the polishing material supply mechanism to the surface of the wafer not covered by the polishing belt, and the polishing material is removed. And the shavings and reaction products remaining on the wafer surface are washed away.

As described above, in the polishing apparatus of the present invention, shavings and reaction products accompanying polishing are mixed into the polishing material through the polishing surface of the polishing belt and the surface to be polished of the wafer, or are reattached to the wafer. Is prevented.

Due to the above-mentioned actions, the uniformity of the film on the wafer surface after polishing can be greatly improved.

..

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the polishing apparatus of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing an example of the structure of the polishing apparatus of the present invention. In FIG. 1, reference numeral 11
Is a belt-shaped polishing belt (also referred to as a polishing pad) having a width narrower than the diameter of the wafer to be polished (6 inches in this example) (for example, 3 to 6 cm in this example), and is made of soft artificial leather. There is. The polishing belt 11 moves (that is, rotates) in the longitudinal direction of the belt (indicated by the arrow 13) at a constant speed (eg, 1.0 cm / sec) by the driving means 12 to form an endless track. The outer surface of the polishing belt forms a strip-shaped polishing surface 14, and as shown in FIG. 1, the track portion below the polishing belt 14 presses the wafer 16 to be polished by the roller pressing means 15 by hydraulic pressure.

The wafer support mechanism 17 mounts a suction plate 18 for holding the wafer 16 by a vacuum chuck so that the wafer 16 does not warp, a means 19 for rotating the suction plate 18, a suction plate 18 and a rotating means 19. The polishing belt 11 is composed of a means 20 which reciprocates in a direction orthogonal to the moving direction (arrow line 13) of the polishing surface 14 (in FIG. 1, a direction perpendicular to the paper surface).

The mechanism 21 for cleaning the polishing surface 14 of the polishing belt 11 is provided on the polishing belt track other than the portion of the wafer surface that contacts the surface to be polished. In this embodiment, as shown in FIG. 1, the polishing surface after cleaning is provided at a position where it is not contaminated by the driving means 12 or the like in the upper track. The polishing belt after wafer polishing passes through the mechanism 21 at the constant speed,
While passing through the polishing surface 14, a cleaning liquid (for example, pure water)
To be washed.

The abrasive supply mechanism 22 includes an abrasive discharge port 23.
The polishing material is discharged from the discharge port 23 onto the wafer surface which is not in contact with the polishing surface 14 of the polishing belt.
In this embodiment, a known CMP (chemical mechanical polishing) abrasive is used as the abrasive.

Next, an outline of a method for polishing a semiconductor wafer using the polishing apparatus shown in FIG. 1 will be described.

The film to be polished formed on the surface of the wafer 16 is an element (not shown) having a multi-layer wiring structure, and an underlying oxide film (contact holes and the like are formed) on the main surface of the wafer having a diameter of 6 inches. When the wiring pattern of the layer and the interlayer insulating film covering the wiring pattern are stacked in this order, this interlayer insulating film (CVDSiO ₂ film) is taken as a film to be polished.

Next, the polishing conditions are as follows:
5, the pressure of the polishing belt 11 is 7.0 PSI, the suction plate 18
Rotation speed of 50 rpm, rotation speed of polishing belt 11 is 1.0 cm
/ Sec. 2 and 3 show the polishing belt 11
3A and 3B are a perspective view and a plan view, respectively, showing the movement direction of the suction plate 18 by arrows. The arrow line 13 indicates the moving direction of the polishing belt, the arrow line 24 indicates the rotation direction of the suction plate 18, and the arrow line 25 indicates the reciprocating direction of the suction plate.

Abrasive discharge port 23 of abrasive supply mechanism 22
Is provided at a fixed position on the top of the wafer (relative to the polishing belt), and the polishing material is used at any time (continuous or intermittent).
Supplied.

The uniformity (flatness) of the residual film after polishing in the present embodiment was improved to ± 2 to 3%.
Also, the number of dusts after polishing could be reduced to about 30% of the conventional one on the oxide film.

The following is given as an explanation for obtaining the above effect.

As shown in FIG. 3, since the polishing belt 11 only partially covers the surface of the wafer 16, in the portion not covered by the polishing belt, shavings and reaction products accompanying the polishing progress. Are flushed and renewed with new abrasive. Since the wafer 16 moves due to the rotation and reciprocating motion of the suction plate 18, the polishing material interposed between the surface to be polished of the wafer 16 and the polishing surface of the polishing belt 11 is sequentially replaced with a fresh one.

Further, since the polishing surface is changed from the conventional flat surface to the strip shape, uniform pressure is eventually applied to the wafer surface, and the flatness of the film is improved.

The polishing belt 11 is sequentially rotated while polishing is in progress, and the polishing surface cleaning mechanism 21 is passed during the rotation, so that the polishing belt is sequentially cleaned in a clean state after cleaning.

As a method of pressing the polishing belt 11,
Other than the roller pressing method shown in FIG. 1, other methods such as the method using the leaf spring 26 shown in FIG. 4 may be used.

Further, the width of the strip-shaped contact surface, which is polished by the polishing surface 14 of the polishing belt 11 while pressing the wafer surface, may be a width that is linear or larger and does not exceed the wafer diameter.

Further, the polishing conditions are not limited to those of the above-mentioned embodiment as long as effective polishing can be performed.

[0033]

As described in detail above, according to the present invention, the polishing material is uniformly renewed, and the polishing residue and the reaction products are prevented from being mixed into the polishing material due to the polishing. It was possible to provide a semiconductor manufacturing apparatus capable of preventing the re-adhesion of the reaction product and the reaction product on the wafer, keeping the polish rate constant, and improving the uniformity (flatness) of the film on the wafer surface after polishing. .

[Brief description of drawings]

FIG. 1 is a semiconductor manufacturing apparatus (polishing apparatus) of the present invention.
3 is a front view showing an example of the configuration of FIG.

FIG. 2 is a perspective view illustrating directions of rotation and reciprocation of a polishing belt and a wafer support mechanism of the polishing apparatus shown in FIG.

FIG. 3 is a plan view illustrating rotation and reciprocating directions of a polishing belt and a wafer support mechanism of the polishing apparatus shown in FIG.

FIG. 4 is a front view showing another embodiment of the configuration of the polishing apparatus of the present invention.

FIG. 5 is a front view showing an example of the configuration of a conventional polishing apparatus.

[Explanation of symbols]

 Reference Signs List 11 polishing belt 12 driving means for polishing belt 14 belt-shaped polishing surface 15 pressure roller 16 wafer to be polished 17 wafer support mechanism 18 suction plate 19 rotating means 20 reciprocating means 21 polishing surface cleaning mechanism 22 abrasive material supply mechanism 23 abrasive material discharge port 26 leaf spring

Claims (1)

[Claims] 1. A polishing apparatus for polishing a film formed on a wafer surface using an abrasive, which has a strip-shaped polishing surface having a width narrower than a wafer diameter which forms an endless track in a longitudinal direction and moves. A polishing belt for polishing a film formed on the wafer surface by a surface, a wafer supporting mechanism for adsorbing a wafer to be polished, and performing reciprocating motion orthogonal to the moving direction of the polishing belt, and a surface to be polished on the wafer surface. A mechanism for cleaning the polishing surface of the polishing belt provided on the polishing belt track other than the contacting portion, and discharging the polishing material to the wafer surface not in contact with the polishing surface of the polishing belt to renew the polishing material and the wafer. A semiconductor manufacturing apparatus, comprising: a polishing material supply mechanism for cleaning the surface.