JPS6376349A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To remove an upheaved part of a polishing stopper above a pillar-like protrusion and to make the height of the pillar-like protrusion and a flat part of the polishing stopper uniform in such a way that the polishing stopper is deposited and is then removed by control etching. CONSTITUTION:If a thick PSG film 15 is formed by depositing an insulating film composed of a dielectric material on the whole surface, the PSG film is upheaved on a pillar-like protrusion 13. Then, a polishing stopper material (silicon nitride) is deposited so that a polishing stopper film 16 can be formed. Then, the surface of this film is coated with a resin material, e.g. a resist material, in such a way that the surface becomes flat and that an upheaved part 16b can be hidden, and a resist film 17 is formed. Then, if a control etching process is executed until the upheaved part 16b of the polishing stopper is removed, the PSG material remains over the pillar-like protrusion. Then, the PSG material is polished until the surface of the pillar-like protrusion can be exposed.

Description

Detailed Description of the Invention [Summary] In the formation of a columnar convex portion connecting a first layer wiring and a second layer wiring, a stopper for polishing is provided in the step of flattening an insulating film by polishing, and a stopper on the convex portion is provided. Polishing is performed after removing only the dirt.

[Industrial application field]

The present invention relates to a method for manufacturing a semiconductor device, and more specifically, to an improvement in a method for directly reading first-layer wiring and second-layer wiring.

[Conventional technology]

In manufacturing a semiconductor device, a lower first layer aluminum (i) wiring and an upper second layer Aβ wiring are connected. This technique will be explained with reference to the cross-sectional view of FIG. 2. An insulating film 22 is formed on the first layer wiring 21, a contact hole 23 is opened in this insulating film, and then this contact hole is opened. A buried second layer wiring 24 is formed to connect the first layer wiring 21 and the second layer wiring 24.

[Problem that the invention seeks to solve]

Recently, there has been a demand for higher integration of integrated circuits, and the diameter a of a contact hole tends to be smaller than its depth b.

When the aspect ratio b/a becomes large, for example, when AA is deposited, A7! on the flat part of the insulating film 22! The thickness t2 of A2 on the side wall of the contact hole is tl>t2.

The value of the current flowing through the A1 wiring is set by calculating the cross-sectional area of the A1 wiring, but in the example described above, the cross-sectional area of the wiring 24 on the side wall of the contact hole in the second layer wiring 24 is equal to the cross-sectional area of the wiring 24 on the flat part. The problem is that the cross-sectional area of the contact hole becomes smaller than the cross-sectional area of the contact hole, and the resistance becomes large at the contact hole.

In order to solve this problem, as shown in Figure 3,
A technique has been developed in which a columnar projection 25 is provided on the first J anchor wire 21 and the first layer wiring 21 and the second layer wiring 24 are connected via the columnar projection 25.

FIG. 4 is a cross-sectional view showing a method of forming columnar convex portions 25 on the first layer wiring, in which columnar convex portions 25 (indicated by solid lines) of the same height are provided on the first layer wiring 21 at the same level, and the entire surface is An insulating material (e.g. Eborin Glass -PSG-) is applied to completely cover the columnar protrusions as shown by the dotted line to create an insulating lj odor 22, and this insulating film 22 is mechanically and chemically polished using an abrasive (
polishing) until the surface of the columnar projection 25 is exposed. Note that the illustrated portions are formed on the same wafer.

In such polishing, it is inevitable that there will be a polishing distribution within the wafer, that is, there will be parts of the wafer that are over polished, parts that are just polished, and parts that are still under polished. . In Figure 4,
The columnar protrusion on the left has been polished to just the right level, and the columnar protrusion on the right has been overpolished as shown by the dotted line. In this case, there is a problem that the polishing distribution within the wafer directly affects the height of the columnar convex portions, causing non-uniformity in the level of the second layer wiring.

The present invention was created in view of these points, and an object of the present invention is to provide a method for forming columnar protrusions that connect the first layer wiring and the second layer wiring of a semiconductor device to the same height. do.

[Means for solving problems]

FIG. 1 (al or [1] is a diagram of an embodiment of the present invention, in which 11 is a wafer, 12 is a first layer wiring, 13 is a columnar convex forming member, and 14 is a first layer wiring and a columnar convex). An etching stopper interposed between the part forming members, 15 an insulating film made of a dielectric material, 16 a polishing stopper, and 17 a resin material film (for example, a resist film).

In the present invention, the insulating film 15 (for example, a PSG film) is formed so as to fill the columnar protrusion forming member 13, and the insulating film 15
For example, a silicon nitride film 16 is formed as a polishing stopper thereon, and a resist film 17 having the same etching rate as the polishing stopper is formed so that the entire surface is flat.
The raised part 16b of the polishing stopper on the flat part is removed by controlled etching, and the member 14 is removed.
Place the upper I'SG on the flat part 16a of the polishing stopper.
The surface is polished until the surface is exposed, and then the upper layer wiring is formed.

[Effect]

According to the above-mentioned method, by depositing a polishing stopper and performing controlled etching, the raised portion 1 of the polishing stopper on the upper part of the columnar convex portion forming member is formed.
6b is removed and then polished,
Over-polishing due to polishing distribution is prevented by the flat portion 16a of the polishing stopper, and the heights of the columnar convex portions can be made uniform.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First, referring to the perspective view of FIG. 1 (al), a semiconductor substrate (
On the wafer 11, an 8β film for forming a first layer wiring, an etching stopper film, and a columnar projection forming member film are formed in this order, and patterned as shown in the figure. The etching stopper is different from the polishing stopper described below, and serves as a stopper when forming a columnar projection by etching the columnar projection forming member. The first layer wiring film is formed to have a thickness of 0.8 μm, the etching stopper film to a thickness of 0.1 μm, and the columnar convex portion forming member film to a thickness of 0.8 μm.

Next, referring to FIG. 1(b) (this figure is a cross-sectional view of the patterned first layer wiring 12 of FIG. 1(a) viewed in the longitudinal direction), a dielectric insulator is coated on the entire surface. (For example, P.S.
G) 15 is deposited to form a PSG film 15 with a thickness of 1.5 μm, the PSG film rises above the columnar convex portion forming member 13. Next, a polishing stopper material (silicon nitride) is deposited to a thickness of 0.2 μm to form a polishing stopper film 16. The polishing stopper film consists of a flat part 16a and a raised part 16b corresponding to the above-mentioned raised shape of the PSG film 15.

Subsequently, a resist film 17 is formed by applying a resin material, for example, a resist, to the extent that the surface is flat and the raised portions 16b are hidden.
form. This resist may be made of other resin materials, but a material whose etching rate is approximately the same as that of the polishing stopper is selected.

Next, control etching using a Ch-based etchant gas is performed until the raised portion 16b of the polishing stopper disappears as shown in FIG. 1(C), and PSG remains above the columnar convex portion forming member.

Instead of such controlled etching, resist film 1
7 may be patterned to expose the raised portion 16b, and then the raised portion 16b may be etched.

Next, as shown in FIG. - The stopper works to prevent over-polishing. Therefore, polishing is performed while preventing over-polishing as described with reference to FIG. 4 until the surfaces of all columnar convex portion forming members are exposed.

The structure of FIG. 1(d) after the polishing described above is shown in FIG. 1(e) and FIG. 1(d) when viewed in the lateral direction of FIG. 1(d).
This is shown in FIG. 1(f) as seen from above.

Thereafter, the columnar protrusion forming member is etched to form the columnar protrusion shown in FIG. 3, and then the second layer wiring is formed.

〔Effect of the invention〕

As described above, according to the present invention, the polishing stopper is partially removed by controlled etching, that is, only the raised part 16b at the top of the columnar convex part forming member is removed, leaving the flat part 16a and polishing the PSG. In this polishing, the flat portion 16a acts as a stopper to prevent over-polishing, making it possible to form columnar convex portions of the same height.

[Brief explanation of the drawing]

Figures 1 (a) to f) are diagrams of the embodiment of the present invention, Figure 2 is a sectional view showing the problems of the conventional example, and Figure 3 is a cross-sectional view of the first layer and the second layer.
FIG. 4 is a cross-sectional view showing the problems of the conventional example. In FIG. 1, 11 is a wafer, 12 is first layer wiring, 13 is a columnar convex forming member, and 14 is Etching stopper film 15 is a PSG film, 16 is a polishing stopper film, and 17 is a resist film. Agent, Patent Attorney: Hajime Kuki, Agent, Patent Attorney, Yoshio Osuga, Nomotoki, I'm on Hujitong's side! -～-+1! q! Self-conspiracy 12Z゛V+77'
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Claims (1)

[Claims] In a method for connecting a first layer wiring (12) provided on a semiconductor substrate (11) and a second layer wiring formed on the first layer wiring via an insulating film (15) , A columnar protrusion forming member (13) used for connecting the first layer wiring (12) and the second layer wiring is placed on the semiconductor substrate (11) with an etching stopper (13) for etching said member.
4) step of forming a dielectric material (15
), a step of depositing a polishing stopper film (16) serving as a stopper in polishing the film (15) and a resin film (17) having the same etching rate as the polishing stopper; )
A method for manufacturing a semiconductor device, comprising the steps of: removing a protrusion (16b); and exposing a surface of a columnar protrusion forming member (13) by polishing.