JPH05166942A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To reduce the amount of drop of a pillar-shaped wiring (a plug) for connecting upper and lower wirings to each other. CONSTITUTION:A conductive layer 3 for connection use is formed in a contact hole 2a and thereafter, an layer insulating layer 20 is etched back by a prescribed amount to bring the layer 3 in a state that its upper end projects more than the surface of the etched-back layer 2 by a trace amount or drops by some amount and thereafter, an upper conductive layer 4 is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device and a method of manufacturing the same, and more particularly to a connection portion of fine wiring formed on a semiconductor substrate and a method of manufacturing the same.

[0002]

2. Description of the Related Art As semiconductor devices become highly integrated, both layers are formed to connect a lower conductive layer made of a lower electrode wiring or an impurity diffusion layer of a semiconductor substrate to an upper conductive layer made of an upper electrode wiring. The columnar holes (contact holes) formed in the insulating layer (interlayer insulating film) that separates the holes are decreasing in diameter and increasing in depth. As a means for solving this, a method of providing a connection conductive layer (generally called a plug) embedded in a columnar connection hole has been conventionally adopted.

Referring to the drawings below, FIG. 2 is a sectional view of a wiring connection portion of a conventional semiconductor device. In the figure,
Reference numeral 1 is a lower conductive layer formed on the underlying insulating layer, 2 is an interlayer insulating layer formed on the lower conductive layer 1, and an upper conductive layer 4 is formed on the insulating layer 3. 1 and the upper conductive layer 4 are electrically connected to each other through a conductive layer 3 for connection such as tungsten filling the contact hole 2a formed in the interlayer insulating layer 2.

Next, the manufacturing method will be described. First, the lower conductive layer 1 is formed on the underlying insulating layer, then the interlayer insulating layer 2 is formed thereon, and then the contact hole 2a reaching the surface of the lower conductive layer 1 is formed at a predetermined position. A conductive layer 3 for connection such as tungsten is formed in the contact hole 2a, and an upper conductive layer 4 is formed thereon. Regarding the method of forming the conductive layer 3 for connection in the above step, the following 2
The method is commonly used.

One is a method of filling the inside of the contact hole with a conductive layer and removing unnecessary portions by etching back using the CVD method or the like. This is as shown in Fig. 3 (a).
First, a conductive film 30 to be the conductive layer 3 for connection is deposited on the entire surface of the interlayer insulating layer 2 having the contact holes 2a by a CVD method or the like, and then, as shown in FIG. 3 (b), selectively by a dry etching method. Conductive film 3 around the contact hole 2a
0 is completely removed from the surface of the insulating film 2, and the conductive film left in the holes is used as the conductive layer 3 for connection.

The other is as shown in FIG. 4 (a), which is shown in FIGS. 4 (b) and 4 (c) by the selective CVD method utilizing the difference in material only on the bottom surface of the contact hole 2a formed in the insulating layer 2. ), A conductive film is sequentially deposited, and this is used as the conductive layer 3 for connection.

[0007]

The conventional semiconductor device and the manufacturing method thereof are configured as described above, and the difference in height between the surface of the interlayer insulating layer and the upper end surface of the conductive layer for connection is dry when the etchback method is used. It is determined by the amount of etching, and in the case of the selective growth method, by the amount of CVD deposition. Usually, the former is an excessive amount of etching considering the underlying step and the film thickness uniformity of the upper conductive layer, and the latter is the surface of the interlayer insulating layer. In general, the amount of deposition is insufficient in order to suppress the deposition on the surface. Therefore, as shown in FIG. 2, the upper end surface of the conductive layer for connection is depressed from the surface of the surrounding interlayer insulating layer, the coverage of the conductive film forming the upper conductive layer is deteriorated, and the reliability of the wiring is deteriorated. There was a problem of inviting.

The present invention has been made to solve the above problems, and a semiconductor device capable of improving the coverage of a conductive film forming an upper conductive layer and improving the reliability of wiring, and a semiconductor device thereof. It is intended to provide a manufacturing method.

[0009]

In a semiconductor device and a method of manufacturing the same according to the present invention, after filling a contact hole with a buried conductive layer, an upper end surface of the buried conductive layer and a surface of the interlayer insulating film are separated from each other. The interlayer insulating film is selectively removed by a predetermined amount so as to be substantially flush.

[0010]

In the present invention, after filling the contact hole with the buried conductive layer, the interlayer insulating film is selectively removed by a predetermined amount to form the upper end surface of the buried conductive layer and the surface of the interlayer insulating film. Are almost flush with each other, the height difference between the surface of the interlayer insulating film and the upper surface of the embedded conductive layer is made small, or the upper surface of the embedded conductive layer is slightly protruded to form the upper conductive layer. The coverage with the embedded conductive layer is improved, and the reliability of the wiring is improved.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of manufacturing a semiconductor device according to an embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, FIG.
The same reference numerals denote the same or corresponding portions, and 2a denotes an interlayer insulating layer whose thickness is reduced by etching.

Next, the manufacturing method will be described. First, a lower conductive layer 1 of polysilicon is formed on a base insulating layer, an interlayer insulating layer 2 of silicon dioxide is formed on the underlying insulating layer, and a contact hole 2a is formed in the lower conductive layer 1 by using the same method as in the conventional example. As shown in FIG. 1A, a conductive layer 3 for connection is formed in the contact hole 2a by using etch back or selective growth.

Then, as shown in FIG. 1B, with the surface of the insulating layer 2 and the upper end surface of the conductive layer 3 for connection exposed, C
By a dry etching method using a reactive gas such as HF ₃ or CF ₄ , only a desired amount of silicon dioxide forming the insulating layer 2 is removed, and the connection conductive layer 3 is processed so that the tungsten is hardly removed. At this time, the upper end surface of the conductive layer 3 for connection is slightly protruded from the surface of the interlayer insulating layer 20 whose thickness has been reduced by etching. In this state, after depositing the aluminum alloy by the sputtering deposition method, the aluminum alloy is deposited by the photolithography method and the dry etching method.
As shown in FIG. 1 (c), the upper conductive layer 4 is processed into a desired wiring pattern.

As described above, according to this embodiment, after the connection conductive layer 3 is formed in the contact hole 2a, the interlayer insulating layer 2 is etched back by a predetermined amount to insulate the upper end surface of the connection conductive layer 3 with the interlayer insulation. Since the upper conductive layer 4 is formed so as to project from the surface of the layer 20, the contact area between the conductive layer 3 for connection and the upper conductive layer 4 is increased, and a multi-layer wiring with good connection can be obtained. You can Moreover, the contact area between the upper conductive layer 4 and the exposed surface of the conductive layer 3 for connection is increased, the connection resistance of the wiring can be reduced, and the performance of the wiring can be improved.

In the above-mentioned embodiment, the interlayer insulating layer is receded until the connecting conductive layer protrudes beyond the interlayer insulating layer. However, the connecting conductive layer does not necessarily have to protrude, and the amount of depression of the connecting conductive layer can be reduced. It may be processed so that the receding of the insulating layer is stopped at a minute position.

In the above embodiment, the case where the lower and upper conductive layers are used as wirings has been described, but these conductive layers may be other conductive layers such as an impurity diffusion layer.

[0017]

As described above, according to the present invention, after the contact hole is filled with the buried conductive layer, the interlayer insulating film is selectively removed by a predetermined amount, and the upper surface of the buried conductive layer is removed. Since the end face and the surface of the interlayer insulating film are made to be substantially flush with each other, the height difference between the surface of the interlayer insulating film and the upper end surface of the embedded conductive layer becomes small, or the upper end surface of the embedded conductive layer slightly protrudes. The contact area between the upper conductive layer and the conductive layer for connection is increased, the coverage of the upper conductive layer and the buried conductive layer is improved, and the upper conductive layer and the conductive layer for connection are connected with low resistance. It is possible,
There is an effect that it is possible to obtain a highly reliable semiconductor device even under long-term use or severe use conditions.

[Brief description of drawings]

FIG. 1 is a diagram showing a method for manufacturing a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional structure diagram showing a conventional semiconductor device.

FIG. 3 is a sectional structural view showing a part of the conventional manufacturing process of a semiconductor device.

FIG. 4 is a sectional structural view showing a part of a manufacturing process of a semiconductor device by another conventional method.

[Explanation of symbols]

 1 Lower Conductive Layer 2 Interlayer Insulating Layer 2a Contact Hole 20 Interlayer Insulating Layer with Reduced Layer 3 Connection Conductive Layer 4 Upper Conductive Layer

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] June 17, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0003

[Correction method] Change

[Correction content]

Referring to the drawings below, FIG. 2 is a sectional view of a wiring connection portion of a conventional semiconductor device. In the figure,
Reference numeral 1 is a lower conductive layer formed on the underlying insulating layer, 2 is an interlayer insulating layer formed on the lower conductive layer 1, and an upper conductive layer 4 is formed on the interlayer insulating layer 2. The lower conductive layer 1 and the upper conductive layer 4 are electrically connected to each other through a conductive layer 3 for connection such as tungsten filling the contact hole 2a formed in the interlayer insulating layer 2.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

The other is to cover only the bottom surface of the contact hole 2a formed in the insulating layer 2 as shown in FIG. 4 (a).
By the selective CVD method utilizing the difference in the material of the deposition surface, FIG.
As shown in (b) and (c), conductive films are successively deposited to form the conductive layer 3 for connection.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

[0010]

In the present invention, after filling the contact hole with the buried conductive layer, the interlayer insulating film is selectively removed by a predetermined amount to form the upper end surface of the buried conductive layer and the surface of the interlayer insulating film. The upper and lower conductive layers have a shape in which the height difference between the surface of the interlayer insulating film and the upper surface of the buried conductive layer is made small, or the upper surface of the buried conductive layer protrudes slightly.
Improved coverage in the buried conductive layer of, reliability of the wiring is improved.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of manufacturing a semiconductor device according to an embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, FIG.
The same reference numerals denote the same or corresponding portions, and reference numeral 20 denotes an interlayer insulating layer whose thickness is reduced by etching.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction content]

[0017]

As described above, according to the present invention, after the contact hole is filled with the buried conductive layer, the interlayer insulating film is selectively removed by a predetermined amount, and the upper surface of the buried conductive layer is removed. Since the end face and the surface of the interlayer insulating film are made to be substantially flush with each other, the height difference between the surface of the interlayer insulating film and the upper end surface of the embedded conductive layer becomes small, or the upper end surface of the embedded conductive layer slightly protrudes. The contact area between the upper conductive layer and the conductive layer for connection is increased , the coverage of the upper conductive layer on the embedded conductive layer is improved, and the upper conductive layer and the conductive layer for connection are connected with low resistance. Therefore, there is an effect that a semiconductor device having excellent reliability can be obtained even under long-term use or severe use conditions.

Claims (2)

[Claims] 1. An upper conductive layer formed on the lower conductive layer via an interlayer insulating film and a contact hole formed in the interlayer insulating film are filled to electrically connect the lower conductive layer and the upper conductive layer. A semiconductor device including a buried conductive layer connected to the semiconductor device, wherein the upper end surface of the buried conductive layer projects beyond the surface of the interlayer insulating film. 2. A semiconductor having a step of forming a contact hole in an interlayer insulating film formed on a lower conductive layer, filling the contact hole with a buried conductive layer, and then forming an upper conductive layer on the interlayer insulating film. In the method of manufacturing a device, the step of filling the contact hole formed in the interlayer insulating film with a buried conductive layer, and the upper end surface of the buried conductive layer and the surface of the interlayer insulating film are substantially flush with each other. And a step of selectively removing the interlayer insulating film by a predetermined amount.