JPH08148454A - Substrate polishing method - Google Patents

Abstract

PURPOSE: To provide a polishing method with which a polishing liquid can be spread to the center part of the surface to be polished when a substrate is polished using a polishing liquid, and the whole surface of the substrate can be polished excellently and uniformly. CONSTITUTION: When the surface 2 to be polished of the substrate 1 (semiconductor wafer, etc.) is polished using a polishing liquid, grooves 3, to be used for feeding of the polishing liquid to reach the center part of the surface 2 to be polished of the substrate, are formed on the surface 2 to be polished, on scribe lines, for example, and a polishing operation is conducted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for polishing a substrate. INDUSTRIAL APPLICABILITY The present invention can be used in polishing various substrates having a step of polishing a substrate with a polishing liquid.

[0002]

2. Description of the Related Art Conventionally, when a substrate (for example, a semiconductor substrate) is polished, a polishing liquid is supplied to the surface to be polished and the polishing is performed using this. For example, when forming a bonded SOI substrate, it is used for polishing from one bonded substrate.

In the conventional polishing method, for example, in the conventional polishing method using a flat semiconductor wafer and a flat polishing pad (cross), the polishing liquid cannot be sufficiently supplied to the center of the wafer, and the polishing amount becomes uneven. There is a problem. That is, as shown in FIG. 4, when the wafer 10 held by the wafer holder 5 is polished by the polishing pad 6, even if an attempt is made to supply the polishing liquid 4 between the wafer 10 and the polishing pad 6, the wafer 10 is not always removed. The polishing liquid cannot be sufficiently supplied to the center of the. This becomes particularly remarkable when the wafer 10 has a large diameter.

It is possible to solve the above problem by forming a groove for guiding a polishing liquid to a polishing pad (cloth), but in this case, the processing strain of the pad at the time of forming the groove causes the polishing uniformity and the polishing surface roughness. There is a problem that it worsens.

Further, if the polishing pad has a groove, there is a problem that the edge of a wafer or the like as a substrate to be polished is caught in the groove and the wafer is cracked or broken.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and when polishing a substrate with a polishing liquid, the polishing liquid can be sufficiently spread to the center of the surface to be polished of the substrate. Therefore, it is an object of the present invention to provide a method for polishing a substrate that can realize uniform and excellent polishing over the entire surface.

[0007]

According to the invention of claim 1 of the present application, in a method of polishing a substrate for polishing a substrate with a polishing liquid, the polishing liquid of the substrate is polished on the surface to be polished of the substrate. A method for polishing a substrate is characterized in that a groove for supplying a polishing liquid that leads to the central portion is formed and polishing is performed, thereby achieving the above object.

The invention according to claim 2 of the present application is the method for polishing a substrate according to claim 1, characterized in that the substrate is a semiconductor wafer for forming a semiconductor substrate. It is a thing.

The invention of claim 3 of the present application is the method for polishing a substrate according to claim 1, characterized in that the substrate is a substrate for forming a bonded SOI substrate. To achieve.

The invention according to claim 4 of the present application is characterized in that a groove for supplying a polishing liquid is formed at a position which becomes a scribe line at the time of manufacturing a semiconductor device. A method for achieving the above object.

The structure of the present invention will be described below with reference to the example of FIG. 1 showing an embodiment of the present invention which will be described later in detail.

FIG. 1 is a plan view of a surface to be polished 2 of a substrate to be polished 1 (semiconductor wafer in the illustrated example). The present invention
When polishing the substrate 1 with the polishing liquid, a groove for supplying the polishing liquid to the surface 2 to be polished of the substrate 1 (the surface visible in FIG. 1) that guides the polishing liquid to the central portion of the surface 2 to be polished of the substrate. Form 3
It is configured to perform polishing.

In the illustrated example, the groove 3 is formed on the surface of the substrate 1 (the surface 2 to be polished) so as to divide the whole vertically and horizontally into a large number of squares.

In the examples described later, specific examples of applying the present invention to polishing for SOI substrate formation, interlayer flattening polishing, and bare Si mirror polishing are shown, but the present invention is not limited to these, and various substrates can be used. Needless to say, it can be used for polishing.

[0015]

As described above, in the present invention, the surface 3 to be polished of the substrate 1 is provided with the groove 3 for supplying the polishing liquid for guiding the polishing liquid to the central portion of the surface 2 to be polished of the substrate 1. At this time, as shown in FIG. 2, even when the polishing pad 6 is used to polish the substrate 1 supported by the holder 5 using the polishing liquid 4, it is difficult to supply the polishing liquid in the prior art. The polishing liquid 4 can be sufficiently supplied to the center of 2. Therefore, polishing uniformity is improved, and good polishing can be achieved.

[0016]

EXAMPLES Examples of the present invention will be described in detail below. However, as a matter of course, the present invention is not limited to the following examples.

Example 1 In this example, the present invention is applied to a selective polishing step in a manufacturing process of a bonded SOI substrate.

In general, a bonded SOI substrate is manufactured by
Wafer bonding, grinding (rough polishing), and selective polishing (precision polishing) are performed, but in this embodiment, after completion of the grinding in this series of steps, a polishing liquid is provided on the scribe line as shown in FIG. The groove 3 for supply is formed.

The formation of the SOI substrate by the conventional bonding / polishing technique will be described below. As shown in FIG. 5A, the silicon substrate 11
(In general, a high flatness silicon wafer is used. This is referred to as a substrate A). One side of the gutter is patterned by using a photolithography technique and an etching technique to form a concave step. Further, Si is formed on the surface having the stepped portion of the recess.
The insulating portion 12 is formed by forming an O ₂ film or the like (FIG. 5B). Further, a polysilicon film is formed as the bonding film 13 on the insulating portion 12 (FIG. 5C).

Next, the bonding film 13 made of a polysilicon film.
The surface of is polished and flattened to a highly smooth surface (Fig. 5).
(D)).

On the polished surface of the bonding film 13, another substrate 14 is attached.
(This is the substrate B) is brought into close contact. Both surfaces are joined by the tight compression bonding, and as a result, a bonded joint structure as shown in FIG. 6A is obtained.

Next, after chamfering the side peripheral portion, the surface of the substrate 1 is ground until the insulating portion 12 is exposed (FIG. 6).
(B)).

6B is upside down from FIG. 6A, but this is because the substrate 11 is turned upside down for the purpose of chamfering and grinding, and the substrate 11 is placed on the upper side.

Next, selective polishing is performed. Here, precise finishing polishing is performed until the insulating portion 12 is just exposed. As a result, as shown in FIG. 6C, a structure is obtained in which the silicon portion 10 ′ (which serves as an element forming portion) is surrounded by the insulating portion 12 having irregularities and is present on the insulating portion 12.

In this embodiment, in the SOI substrate manufacturing technique by the above-mentioned laminating and polishing method, the selective polishing,
That is, the present invention is embodied when the structure of FIG. 6 (b) is polished to obtain the structure of FIG. 6 (c).

In this embodiment, as shown in FIG. 3, the Si substrate 11 is roughly ground and then joined to form an integral Si substrate 11, an insulating film 12 (SiO ₂ ), and a bonding film 1.
3 (Poly-Si), the entire substrate 14 to be the base is used as the substrate 1 to be polished, and the Si substrate 11 side is used as the surface 2 to be polished.
Is formed in the portion that will be the scribe line.

In this embodiment, as shown in the plan view of FIG. 1, a polishing liquid is applied to a surface to be polished 2 of a semiconductor wafer for forming an SOI substrate, which is a substrate to be polished 1, at a central portion of the surface to be polished 2 of the substrate. A groove 3 for supplying a polishing liquid for leading to is formed to perform polishing.

The groove 3 for supplying the polishing liquid is formed on the surface of the substrate 1 (the surface to be polished 2) so as to divide the whole vertically and horizontally into a large number of squares, which serve as scribe lines for device formation. This is because the groove 3 is formed in the portion to be formed so as to suppress the influence on each device chip.

Here, the method of forming the groove 3 for supplying the polishing liquid can be performed, for example, in the steps of mask formation by photoresist patterning and dry etching.

Alternatively, the method of forming the groove 3 is not limited to this, and other appropriate means can be adopted, for example, it may be formed by wet etching after photoresist patterning.

By polishing the substrate 1 to be polished (wafer to be polished), as shown in FIG. 2, when a wafer, which is the substrate 1 to be polished, held by a holder 5 is polished by a polishing pad 6, a conventional method is used. Then, the polishing liquid 4 can be sufficiently supplied to the center of the wafer, which was difficult to supply, and the polishing uniformity is improved.

In this embodiment, the depth and width of the groove 3 for supplying the polishing liquid is such that the polishing liquid 4 can be supplied and the polishing liquid 4 can be removed by cleaning, and the shallower the wafer High strength is desirable, and sufficiently narrow is desirable because the yield of chips is high.

That is, in this embodiment, in order to avoid a decrease in the chip yield per wafer, the groove width is set to the minimum necessary.

Further, various films deposited at the time of making the device are formed so that the formed groove 3 is not deeply filled and the groove is wide enough to prevent such filling.

In this embodiment, conventional polishing means may be used as they are as the polishing apparatus, polishing conditions and the like.

However, the region where the groove 3 is formed is not limited to the scribe line and may be any region that can supply the polishing liquid to the center of the wafer.

According to this embodiment, the polishing liquid can be sufficiently supplied to the central portion of the surface to be polished 2 of the wafer to be polished 1 and the polishing uniformity is improved. Further, the flatness of the polishing pad 6 (cloth) can be maintained, and the uniformity and surface roughness are not deteriorated. Moreover, it does not induce cracking or chipping of the wafer to be polished 1. This embodiment can be applied with a conventional polishing apparatus and polishing conditions. Further, even if the diameter of the wafer is increased, there is a great advantage that polishing uniformity is not deteriorated.

Example 2 In Example 1, the present invention was applied to polishing a bonded SOI substrate, but in this Example, the present invention was applied to interlayer planarization CMP (chemical mechanical polishing).

In this embodiment, a SiO ₂ film is formed as a flattening film on a silicon wafer having an underlying step, and this is CMP using, for example, an alkaline chemical polishing liquid,
At the time of flattening, a groove for supplying a polishing liquid was formed and polishing was performed in the same manner as in Example 1.

Also in this embodiment, sufficient supply of the polishing liquid to the surface to be polished was achieved, and uniform polishing was realized.

Example 3 This example is an example in which the present invention is applied to mirror polishing a bare Si wafer.

In this example, a groove for supplying a polishing liquid was formed on the surface to be polished of a bare Si wafer, and polishing was carried out in the same manner as in each of the above examples.

Also in this embodiment, sufficient supply of the polishing liquid to the surface to be polished was achieved, and uniform mirror polishing was realized.

[0044]

As described above, according to the present invention, when the substrate is polished with the polishing liquid, the polishing liquid can be sufficiently spread to the central portion of the surface to be polished of the substrate, so that the entire surface can be covered. It was possible to provide a method for polishing a substrate capable of achieving uniform and excellent polishing over a range.

[Brief description of drawings]

FIG. 1 is a plan view of Example 1, showing formation of grooves on a surface to be polished of a substrate.

FIG. 2 is an explanatory view of the operation of the first embodiment.

FIG. 3 is an enlarged cross-sectional view of a main part of a substrate to be polished (SOI substrate) of Example 1.

FIG. 4 is a diagram showing a conventional technique and its problems.

FIG. 5 is a diagram showing a background art and a diagram showing a general manufacturing process of an SOI substrate (1).

FIG. 6 is a diagram showing a background art and a diagram showing a general manufacturing process of an SOI substrate (2).

[Explanation of symbols]

1 Substrate 11 Si Substrate Forming Si Substrate 12 SOI Substrate Forming Insulating Film (SiO ₂ ) 13 SOI Substrate Forming Bonding Film (Poly-Si) 14 Support Substrate (Si Wafer) 2 Polished Surface 3 Polishing Liquid Supply Groove 4 Polishing liquid 5 (Wafer) holder 6 Polishing pad

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location H01L 21/301 27/12 B

Claims (4)

[Claims] 1. A method for polishing a substrate, which comprises polishing a substrate with a polishing liquid, wherein a groove for supplying a polishing liquid is formed on the surface to be polished of the substrate for guiding the polishing liquid to the center of the surface to be polished of the substrate. And a method for polishing a substrate, which comprises performing polishing. 2. The method for polishing a substrate according to claim 1, wherein the substrate is a semiconductor wafer for forming a semiconductor substrate. 3. The method for polishing a substrate according to claim 1, wherein the substrate is a substrate for forming a bonded SOI substrate. 4. The method for polishing a substrate according to claim 2 or 3, wherein a groove for supplying a polishing liquid is formed at a position which becomes a scribe line at the time of manufacturing a semiconductor device.