JP2002009027A - Flattening method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent increase in cost by reducing abrasive grains which are discarded without directly contributing to finishing. SOLUTION: The content of abrasive grains contained in a fixed abrasive board is distributed in such a way that the abrasive grains are uniformly dispersed and distributed in conventional way in a region mainly contributing to the finishing and on the other hand, the inside and outside of the fixed abrasive board which do not contribute to the finishing have the constitution containing no abrasive grain. By distributing the density of abrasive grains in this way, the efficiency of utilization of the abrasive grains is improved and the cost can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flattening technique for a substrate or wafer surface pattern by polishing used in a manufacturing process of a semiconductor integrated circuit or the like. And a flattening apparatus for the same.

[0002]

2. Description of the Related Art A semiconductor device manufacturing process includes a number of process steps. As an example of a process to which the present invention is mainly applied, a wiring process will be described with reference to FIG.

FIG. 5A is a cross-sectional view of a wafer on which a first-layer wiring is formed. An insulating film 16 is formed on the surface of the wafer substrate 15 on which the transistors are formed, and a wiring layer 17 of aluminum or the like is provided thereon. A hole is formed in the insulating film 16 to form a junction between the transistor portion and the wiring, and a portion 1
7 'is slightly dented.

In a second-layer wiring process shown in FIG.
An insulating film 18 and a metal aluminum layer 19 are formed on the first layer.
Is formed, and a photoresist layer 20 for exposure is attached to form a wiring pattern on the aluminum layer. Next, as shown in FIG. 3C, the circuit pattern is exposed and transferred onto the photoresist 20 using a stepper 21. In this case, it is impossible to focus simultaneously on the convex portion and the concave portion 22 on the surface of the photoresist layer 20, which is a serious obstacle of resolution blur.

[0005] In order to solve the above-mentioned problem, a flattening process of the substrate surface as described below is performed. That is, after the processing step of FIG. 5A, as shown in FIG. 5D, after the insulating layer 18 is formed, the insulating layer 18 is polished by a method described later so as to be flat to the level 23 in FIG. (E)
Get the state of. Thereafter, a metal aluminum layer 19 and a photoresist layer 20 are formed, and are exposed by a stepper as shown in FIG. In this state, since the resist surface is flat, the problem of the resolution blur does not occur.

[0006] US Pat.
No. 944836 or Japanese Patent Publication No. 5-30052 discloses Chemical Mechanical Polishing (CMP).
A flattening method by polishing called g) is described.

As another wafer flattening processing technique, there is a flattening technique using a fixed abrasive disk made of cerium oxide or the like. The basic configuration of the apparatus is the same as that of the CMP technique, but a fixed abrasive disk is mounted on a rotating platen instead of a polishing pad. In addition, processing can be performed only by supplying water containing no abrasive grains instead of fumed silica or the like as a polishing liquid. The flattening technology using a fixed abrasive disc during the manufacturing process of a semiconductor device includes a patent application PC.
There is T / JP95 / 01814.

[0008]

The cost of conventional chemical mechanical polishing using free abrasive grains and the flattening processing using the above-mentioned fixed abrasive disc largely depend on the amount of abrasive grains consumed per wafer substrate. I do. Even in the case of a fixed abrasive disc, although the efficiency is improved as compared with the free abrasive grain method, there is a problem that some abrasive grains are discarded without directly contributing to the processing, thereby increasing the cost. The reason why the abrasive grains that do not contribute to the direct processing are generated is due to the structure of the head that supports the wafer substrate and applies a polishing load.

The head is usually provided with a retainer ring for supporting the wafer substrate so that the wafer substrate does not come off the head due to frictional force during processing. This retainer ring is inevitably larger than the outer diameter of the wafer substrate, and the surface of the fixed abrasive disc must be formed wide enough to cover the retainer ring. For this reason, since a fixed abrasive disc containing abrasive grains is used over a region where the wafer substrate surface does not pass during processing, there has been a serious problem that wasteful abrasive grains are consumed and cost increases.

[0010]

In order to solve the above-mentioned problems, in the present invention, the content of the abrasive grains contained in the fixed abrasive disc is distributed, and the area which mainly contributes to the processing is uniformly polished as before. Although the grains are dispersed and distributed, the inside and outside of the fixed abrasive disc that does not contribute to the processing have a structure substantially free of abrasive grains. By distributing the abrasive grain concentration in this manner, there is an effect that the abrasive grain utilization efficiency is improved and the cost can be reduced.

[0011]

(Embodiment 1) FIG. 1 shows a basic configuration of a flattening apparatus according to one embodiment of the present invention. In this embodiment, a processing method and apparatus using a normal flattening processing apparatus will be described. The apparatus according to the present embodiment includes a platen 9 that performs polishing, and a rotation driving unit 1 that rotates the platen 9.
0, a polishing tool 6 containing no abrasive grains, a polishing tool 7 containing abrasive grains, a polishing tool 8 containing no abrasive grains, a wafer 1 and a wafer holder 4 for holding the same, a retainer ring 5, A liquid supply unit 2 for supplying a working liquid 3 such as water or slurry, and a conditioner (dresser) 1 for conditioning the surfaces of the polishing tools 6, 7, 8
Consists of one.

At the time of polishing, the fixed-size dresser 11 is driven to cut the surface of the fixed abrasive disc by 1 to 10 μm to perform dressing to expose fresh abrasive grains. Polishing is performed by simultaneously rotating the wafer holder 4 and the platen 9 while pressing the held wafer 1 against the polishing tool 7 containing abrasive grains.

Here, the fixed abrasive discs 6, 7, 8 will be described in more detail. Fixed abrasive discs have an average grain size of 0.3
It is a porous solid consisting of abrasive particles of about μm, a resin for fixing them, and pores. Since the abrasive grains are fixed after being dispersed uniformly, the abrasive grains are usually included on the entire surface.

As shown in FIG. 1, it is understood that the actual contact of the wafer on the surface of the fixed abrasive disk is limited to the vicinity of the center. This is because the wafer holder 4 holding the wafer 1
This is because a retainer ring 5 for supporting the side surface of the wafer 1 is provided so that the wafer does not come off during processing, and a surface for receiving the retainer ring is required for the fixed abrasive disc. Therefore, if dressing is performed on the entire surface of the fixed abrasive discs 6, 7, 8 before processing, abrasive grains that do not contribute to the processing at all in the conventional apparatus are removed, and waste occurs.

In order to solve the above-mentioned problems, in this embodiment, the abrasive grains are contained only in the area 7 of the fixed abrasive disc which actually contacts the wafer surface, and the other areas 6 and 8 are contained in the other areas 6 and 8. The configuration was such that no abrasive grains were included. As a specific structure,
As shown in FIG. 3, a method of arranging the polishing tool 6 containing no abrasive grains (on the platen 9), the polishing tool 7 containing the abrasive grains, and the polishing tool 8 containing no abrasive grains in a segment shape, or A tool formed in a hollow ring shape as shown in FIG. 4 may be arranged. Although not shown, it goes without saying that the same effect can be obtained even if the abrasive grain content is distributed to one tool.

Here, when the compressive elastic moduli of the polishing tools 7 and 8 containing abrasive grains are substantially equal to those of the polishing tools 6 and 8 not containing the abrasive grains, the height of the polishing tool is maintained uniformly during the processing, and the good flattening is achieved. Processing will be performed, which is preferable.

(Embodiment 2) In Embodiment 1, the flattening apparatus of the circular platen type has been described. In this embodiment, an example using a belt-type flattening apparatus will be described.

FIG. 2 shows a schematic configuration diagram of a belt type flattening apparatus. In this method, a belt-type polishing tool 12 is driven by two pulleys 13, and the wafer 1 is pressed against the surface of the belt 12 that linearly moves on the pressure receiving plate 14 to polish the wafer. The present invention can be applied to this belt system basically as described in the first embodiment.
That is, a tool containing abrasive grains may be arranged only in the central portion of the belt 12 facing the wafer 1, and a pad containing no abrasive grains may be arranged in other areas.

[0019]

According to the present invention, the amount of abrasive grains that have been wasted and consumed in the prior art can be reduced with respect to the technology for flattening a surface pattern by polishing a semiconductor wafer, so that the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a side view of a flattening apparatus according to one embodiment of the present invention.

FIG. 2 is a side view of a flattening apparatus according to another embodiment of the present invention.

FIG. 3 is a plan view of a polishing tool according to one embodiment of the present invention.

FIG. 4 is a plan view of a polishing tool according to one embodiment of the present invention.

FIG. 5 is a cross-sectional view illustrating a step of forming a wiring in a semiconductor device using a planarization method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Wafer board, 2 ... Processing liquid supply means, 3 ... Processing liquid, 4
... wafer holder, 5 ... retainer ring, 6 ... abrasive tool without abrasive grains, 7 ... abrasive tool with abrasive grains, 8 ... abrasive tool without abrasive grains, 9 ... rotary platen, 11 ... fixed dresser, 15 ... working fluid, 16 ... Pressing means, 17 ... Valve, 18 ... Insulating layer, 1
9 ... metal aluminum layer, 20 ... photoresist layer, 21
... Stepper, 22...

Claims (6)

[Claims] 1. A method for flattening a surface of a workpiece using a fixed abrasive disk in which abrasive grains are fixed with a binder, wherein the ratio of the abrasive grains contained in the fixed abrasive disk is determined by the fixed abrasive A flattening method characterized by being distributed according to the position of a polishing surface of a grain disk. 2. A method of flattening the surface of a workpiece using a fixed abrasive disk in which abrasive grains are fixed by a binder, wherein only a region where the workpiece contacts the fixed abrasive disk during processing. A flattening method, characterized by including abrasive grains in the surface. 3. The flattening method according to claim 1, wherein
The fixed abrasive disc is composed of divided small tools, and the small tool that forms the polished surface on the workpiece contains the required amount of abrasive grains, and the small tool that forms the other polished surface Is a method for flattening a semiconductor wafer, wherein the amount of abrasive grains is less than or not greater than the required content. 4. The flattening method according to claim 1, wherein
The fixed abrasive disc is formed in a disk shape, and the inner and outer peripheral portions thereof are substantially free of abrasive grains, and only the central portion sandwiched between the inner and outer peripheral portions contains abrasive grains, and is polished. A flattening method characterized by performing processing. 5. The flattening method according to claim 1, wherein
A flattening method characterized by processing by controlling a position so that an outer peripheral region of a workpiece covers a region having a low abrasive content. 6. An apparatus for flattening the surface of a workpiece using a fixed abrasive disc in which abrasive grains are fixed with a binder, wherein the ratio of the abrasive grains contained in the fixed abrasive disc is fixed to the fixed abrasive disc. A flattening apparatus comprising a fixed abrasive disk distributed according to the position of an abrasive disk surface.