JP3040500B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device having a multilayer wiring.

[0002]

2. Description of the Related Art Conventionally, Al (aluminum) alloy is generally used as a wiring material in a wiring forming process of a semiconductor device which is miniaturized. Such an Al alloy has a high light reflectance. Therefore, when a multilayer wiring is formed using an Al alloy layer, a resist pattern used for a photolithography method is disconnected due to light reflected from the wiring layer due to a step in a base, and a desired wiring pattern cannot be formed. There was a problem.

As a method for solving such a problem, an antireflection film such as a TiN film and a TiON film is formed on an Al alloy layer serving as a wiring layer, and the antireflection film prevents reflected light from the wiring layer. There is a way.

[0004]

However, as described above,
There is a problem that the antireflection film formed on the wiring layer cannot be easily removed by etching. That is, in the multilayer wiring, when electrically connecting the lower wiring layer and the upper wiring layer, an interlayer insulating film is formed on the lower wiring layer, and a through hole is formed in the interlayer insulating film. Electrically connects the lower wiring layer and the upper wiring layer. Here, when a wiring in which an antireflection film such as a TiN film or a TiON film is formed on the above-described Al alloy layer is used as a lower wiring layer, a CF-based film is usually formed to form a through hole in the interlayer insulating film. Although an etching gas is used, a TiN film or a TiON film serving as an anti-reflection film cannot be removed by etching satisfactorily, and there is a problem that the anti-reflection film remains in a lower wiring layer. As a result, there is a problem that the contact resistance between the lower wiring layer and the upper wiring layer increases and the contact resistance varies.

Further, a TiN film or a T
The iON film can be satisfactorily removed by etching using a mixed solution of hydrogen fluoride (HF) and water. However, in this case, there is a problem that the Al alloy layer as a lower wiring layer is also etched. Was. SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a semiconductor device having a multilayer wiring structure capable of obtaining a wiring layer having a precise wiring pattern shape and preventing an increase in contact resistance and a variation in contact resistance between wiring layers. Is to provide a method of manufacturing the same.

[0006]

A method of manufacturing a semiconductor device according to the first aspect is as follows. A silicon nitride film is formed on the first wiring layer, and an anti-reflection film is formed on the silicon nitride film. Then, after forming the first wiring layer in a wiring pattern shape, the antireflection film is etched away using the silicon nitride film as an etching stopper.
After forming an interlayer insulating film on the surface, the interlayer insulating film and the silicon nitride film are selectively removed to form a through hole. A second wiring layer electrically connected to the first wiring layer through the through hole is formed.

According to a second aspect of the present invention, there is provided a method of manufacturing a semiconductor device.
Do the following: A silicon nitride film is formed on the first wiring layer, and an anti-reflection film is formed on the silicon nitride film.
Then, after forming a first wiring layer in a wiring pattern shape, an interlayer insulating film is formed on the surface. Then, the interlayer insulating film and the antireflection film are selectively etched and removed using the silicon nitride film as an etching stopper. And
After the exposed silicon nitride film is selectively removed to form a through hole, a second wiring layer electrically connected to the first wiring layer through the through hole is formed.

[0008]

According to the structure of the present invention, a silicon nitride film is formed on a lower first wiring layer, and an antireflection film is formed on the silicon nitride film. After the first wiring layer is formed in a wiring pattern shape, the silicon nitride film is used as an etching stopper when etching the antireflection film. Therefore, the anti-reflection film can be easily and completely removed without etching the first wiring layer. Further, the silicon nitride film formed on the first wiring layer can be easily removed by etching. Therefore, the first wiring layer can be completely exposed in the through hole.

[0009]

1A to 1F are cross-sectional views in the order of steps showing a method for manufacturing a semiconductor device according to a first embodiment of the present invention. FIG.
1A, a first wiring layer 3 made of an Al alloy layer, a silicon nitride film 4, and a TiN film 5 serving as an anti-reflection film are formed in this order on a silicon substrate 1 with an insulating film 2 interposed therebetween. I do. The thickness of the TiN film 5 is about 100 to 500 °.

Next, as shown in FIG. 1B, a resist pattern (not shown) is formed by a photolithography method, and the first wiring layer 3 is formed by using the resist pattern.
By etching the silicon nitride film 4 and the TiN film 5, the first wiring layer 3 is formed in a wiring pattern shape. At this time, the TiN film 4 serving as an antireflection film prevents light reflected by the first wiring layer 3. Thereby, disconnection of the resist pattern due to reflected light can be prevented.
Therefore, the first wiring layer 3 can be precisely formed in a wiring pattern shape.

Next, as shown in FIG. 1C, the TiN film 5 is removed by wet etching using a mixed solution of hydrogen fluoride (HF) and water. On this occasion,
The TiN film 5 serving as an anti-reflection film can be favorably etched, and the silicon nitride film 4 serves as an etching stopper, so that the first wiring layer 3 is not etched.

Next, as shown in FIG.
An interlayer insulating film 6 made of O ₂ or the like is formed, and a photoresist layer 7 is formed on the interlayer insulating film 6. An opening for forming a through hole is patterned in the photoresist layer 7. Next, as shown in FIG. 1E, through holes 8 are formed by selectively removing the interlayer insulating film 6 and the silicon nitride film 4 using the photoresist layer 7 as a mask. At this time, the interlayer insulating film 6 and the silicon nitride film 4 can be easily removed by dry etching using a CF-based gas.

Then, as shown in FIG. 1 (f), a second wiring layer 9 is formed on the first wiring layer 3, and the first wiring layer 3 and the second wiring layer 9 are formed through holes. Through the electrical connection. According to the first embodiment, T as an anti-reflection film
By using the silicon nitride film 4 as an etching stopper when removing the iN film 5 by etching,
Etching of the first wiring layer 3 made of an alloy can be eliminated. Also, a TiN film 5 serving as an anti-reflection film
Is removed by etching before forming the through hole 8, so that the etching can be performed well, and the etching residue of the TiN film 5 does not occur on the silicon nitride film 4. Further, the silicon nitride film 4 used as an etching stopper can be easily removed by dry etching. Therefore, the first wiring layer 3 can be completely exposed in the through hole 8. As a result, the first
A semiconductor device having a multilayer wiring structure having good contact characteristics with low contact resistance between the wiring layer 3 and the second wiring layer 9 and small variation in contact resistance can be obtained.

FIGS. 2A to 2G are cross-sectional views in the order of steps showing a method for manufacturing a semiconductor device according to a second embodiment of the present invention. As shown in FIG. 2A, a first wiring layer 3 made of an Al alloy layer, a silicon nitride film 4, and a TiN film 5 serving as an anti-reflection film are formed on a silicon substrate 1 via an insulating film 2 from below. Form in order.

Next, as shown in FIG. 2B, a resist pattern (not shown) is formed by photolithography, and the first wiring layer 3 and
By etching the silicon nitride film 4 and the TiN film 5, the first wiring layer 3 is formed in a wiring pattern shape. At this time, the TiN film 5 serving as an anti-reflection film prevents reflected light. Thereby, disconnection of the resist pattern due to reflected light can be prevented. Therefore, the first wiring layer 3 can be precisely formed in a wiring pattern shape.

Next, as shown in FIG.
An interlayer insulating film 6 made of O ₂ or the like is formed, and a photoresist layer 7 is formed on the interlayer insulating film 6. An opening for forming a through hole is patterned in the photoresist layer 7. Next, as shown in FIG. 2D, using the photoresist layer 7 as a mask, the interlayer insulating film 6 and the TiN film 5 are selectively etched and removed. At this time, the etching residue 10 of the TiN film 5 may be left on the silicon nitride film 4 in some cases.

Next, as shown in FIG. 2E, the remaining etching of the TiN film 5 remaining on the silicon nitride film 4 is performed by wet etching using a mixed solution of hydrogen fluoride (HF) and water. Is completely removed by etching. At this time, the TiN film 5 serving as an anti-reflection film can be favorably etched, and the silicon nitride film 4 serves as an etching stopper, so that the first wiring layer 3 is not etched.

Next, as shown in FIG. 2F, through holes 8 are formed by removing the silicon nitride film 4 by dry etching using the photoresist layer 7 as a mask. Then, as shown in FIG. 2G, a second wiring layer 9 is formed on the first wiring layer 3, and the first wiring layer 3 and the second wiring layer 9 are electrically connected through the through holes 8. Connection.

According to the second embodiment, the interlayer insulating film 6
When the TiN film 5 serving as an anti-reflection film is selectively removed by etching, even if an etching residue 10 of the TiN film 5 occurs, the etching residue of the TiN film 5 is further reduced by using the silicon nitride film 4 as an etching stopper. Is etched. Thus, the TiN film 5 can be completely removed, and the first wiring layer 3 can be prevented from being etched. In addition, the silicon nitride film 4 used as an etching stopper can be easily removed by dry etching. Therefore, the first wiring layer 3 can be completely exposed in the through hole 8. As a result, it is possible to obtain a semiconductor device having a multi-layer wiring structure having low contact resistance between the first wiring layer 3 and the second wiring layer 9 and small variation in contact resistance and having good contact characteristics.

According to the second embodiment, the TiN film 5 exists on the uppermost portion of the first wiring layer 3 in a region other than the region electrically connected to the second wiring layer 9. It is known that a wiring having a structure in which a TiN film exists at the uppermost portion on a wiring layer has excellent stress migration resistance. Therefore, a highly reliable wiring with improved stress migration resistance can be obtained.

In the first and second embodiments,
Although the wiring structure is a two-layer structure including the first wiring layer 3 and the second wiring layer 9, the present invention is not limited to this. For a semiconductor device having a multilayer wiring structure of three or more layers with an interlayer insulating film between each layer. Can also be applied. Further, the first and second wiring layers 3 and 9 include A
Although it is composed of a single layer of 1 alloy, it is not limited to this, and it may be a multilayer structure such as a Ti / TiN / Al alloy from below.

In the first and second embodiments,
The TiN film 5 serving as an antireflection film formed on the silicon nitride film 4 was selectively removed by wet etching using a mixed solution of hydrogen fluoride (HF) and water, but not limited to this. Any etching method may be used as long as the selection ratio between the film 4 and the TiN film 5 can be obtained.

In the first and second embodiments,
Although the TiN film 5 was used as the antireflection film, the present invention is not limited to this, and a TiON film may be used.

[0024]

According to the method of manufacturing a semiconductor device of the present invention, a silicon nitride film is formed on a first wiring layer, and an antireflection film is formed on the silicon nitride film. And the first
When the antireflection film is etched after forming the wiring layer in the wiring pattern shape, the silicon nitride film is used as an etching stopper. Therefore, the first wiring layer is not etched, and the antireflection film can be easily and completely removed. Further, the silicon nitride film formed on the first wiring layer can be easily removed by etching. Therefore, the first wiring layer can be completely exposed in the through hole.

As a result, a precise first wiring layer can be formed in the wiring pattern, and the contact resistance between the first wiring layer and the second wiring layer is low, and the variation in the contact resistance is small. A semiconductor device having a multilayer wiring structure having excellent contact characteristics can be obtained.

[Brief description of the drawings]

FIGS. 1A to 1F are cross-sectional views in the order of steps showing a method for manufacturing a semiconductor device according to a first embodiment of the present invention.

FIGS. 2A to 2G are cross-sectional views in the order of steps showing a method for manufacturing a semiconductor device according to a second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 silicon substrate 2 insulating film 3 first wiring layer 4 silicon nitride film 5 TiN film (anti-reflection film) 6 interlayer insulating film 8 through hole 9 second wiring layer 10 TiN film remaining after etching

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) H01L 21/3205 H01L 21/321 H01L 21/3213 H01L 21/768

Claims (2)

(57) [Claims] A step of forming a silicon nitride film on the first wiring layer; a step of forming an anti-reflection film on the silicon nitride film; and a step of forming the first wiring layer in a wiring pattern shape. Etching the antireflection film using the silicon nitride film as an etching stopper, removing the antireflection film, forming an interlayer insulating film on the surface, and selectively removing the interlayer insulating film and the silicon nitride film. Forming a through hole, and forming a second wiring layer electrically connected to the first wiring layer through the through hole. 2. A step of forming a silicon nitride film on a first wiring layer, a step of forming an antireflection film on the silicon nitride film, and a step of forming the first wiring layer in a wiring pattern shape. Forming an interlayer insulating film on the surface, selectively etching and removing the interlayer insulating film and the antireflection film using the silicon nitride film as an etching stopper, and removing the exposed silicon nitride film. Forming a through hole by selectively removing the second wiring layer; and forming a second hole electrically connected to the first wiring layer through the through hole.
Forming a wiring layer of the semiconductor device.