JP2001230255A - Method of manufacturing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a semiconductor device which has a multilayered film with an Al/TiN structure wherein an Al film and a TiN film which make an etching shape trapezoidal are laminated. SOLUTION: After patterning is carried out so that the side wall of a photoresist 4 and that of a TiN film 3 are inclined, the A1 film is etched using these side walls as a mask, and an A1 film 2 is processed in a trapezoidal shape.

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 used in a semiconductor integrated circuit or the like,
The present invention relates to a method for forming a metal wiring having a laminated structure of an Al film and an antireflection film.

[0002]

2. Description of the Related Art A metal film is deposited on the entire surface of a wafer by a method such as sputtering, and a predetermined wiring pattern is formed thereon using a photoresist. According to the pattern of the photoresist, a predetermined wiring is obtained by etching away only the portion where the photoresist is opened.
As the metal film used here, Si or Si and C
A two-layered film in which a TiN film is further deposited on an Al film to which a small amount of u is added is often used. Hereinafter, an Al film to which a small amount of Si is added is referred to as an Al-Si film, and an Al film to which a small amount of Si and Cu is added is referred to as an Al-Si-Cu film, and these are collectively referred to as an Al film.

[0003] The role of TiN is that Al has high reflectivity.
A role as an anti-reflection film that reduces reflectivity by being formed on the film and facilitates pattern processing of a photoresist, and a heat treatment (sintering) performed after wiring processing is performed by A.
There is a role as a hillock holder for suppressing hillocks (projections) of Al generated in the l film. 3A to 3C are views showing a conventional method for forming a wiring film having a laminated structure of an Al film and a TiN film. FIGS. FIG.

An insulating film 19 is formed on a substrate 11, an Al film 12 is formed on the insulating film 19, and a Ti film is formed on the Al film 12.
An N film 13 is formed, and a photoresist 1 is formed on the TiN film 13.
Then, the photoresist 14 is patterned so that the side walls become vertical (FIG. 4A). Next,
Using the photoresist 14 as a mask, the TiN film 13 and the Al
The film 12 is anisotropically etched (FIG. 2B). In this case, the side surfaces of the TiN film 13 and the Al film 12 become vertical.

Next, the photoresist 14 is removed (FIG. 1C). In FIG. 2B, the etching is advanced while depositing the side wall protective film 15 on the side surfaces of the Al film 12 and the TiN film 13 which are exposed as the etching progresses, and processing is performed so that the finished shape becomes vertical. Anisotropic etching is performed. Therefore, this method is usually employed because the Al film 12 as a wiring can be processed according to the dimensions of a predetermined photoresist pattern.

FIG. 4 is a view showing another manufacturing method for forming a conventional wiring film having a laminated structure of an Al film and a TiN film. FIGS. It is sectional drawing of a principal part manufacturing process. An insulating film 29 is formed on a substrate 21, an Al film 22 is formed on the insulating film 29, a TiN film 23 is formed on the Al film 22, and a photoresist 24 is coated on the TiN film 23. The resist 24 is patterned so that the side walls become vertical (FIG. 7A).

Next, the TiN film 23 is etched using the photoresist 24 as a mask (FIG. 1B). This TiN film 23 has a trapezoidal shape. Next, the Al film 22 is etched using the photoresist 24 as a mask (FIG. 3C). This Al film 22 has a trapezoidal shape. Next,
The photoresist 24 is removed (FIG. 4D). This manufacturing method is a method for manufacturing an Al wiring used for an element requiring high reliability, and the Al film 22 has a trapezoidal shape.

[0008]

However, in the case of FIG. 3, anisotropic etching (etching in one direction) for etching while depositing the side wall protective film 15 is performed using Al.
The side wall of the film 12 has a vertical processing shape. Therefore, FIG.
As described above, when the passivation film 16 is covered, a weak portion occurs at the side wall. That is, the interlayer film and A
There is a possibility that the film quality of the film deposited at the interface portion with the film (wiring) (the portion within the circle indicated by 17 in the figure) may be weakened (the dotted line portion within the circle indicated by 17 in the diagram: cracks are generated) To do),
If moisture from the outside invades therefrom, it may be a factor of deteriorating reliability such as a decrease in breakdown voltage of the element.

On the other hand, in order to solve this disadvantage, there is a method of improving the coverage of the passivation film 27 by forming a trapezoidal shape in which the processed shape of the Al film 22 is not vertical but gentle as shown in FIG. The method of FIG. 4 will be further described. In order to obtain a trapezoidal shape of the Al film 22 as shown in FIG. 4, wet etching in which etching progresses isotropically (in all directions) has been used. However, the TiN film 23 and A
In order to process a structure in which dissimilar metals are laminated, such as the laminated structure of the 1 film 22, a plurality of types of etching solutions must be used properly according to the film type, and the etching solution is well suited for wet etching of the Al film 22. The phosphorus nitrate used is TiN
Since the etching rate of the Al film 22 is several tens times or more higher than that of the film 23, after the wet etching of the Al film 22,
When the N film 23 overhangs like the eaves 26 (FIG. 4D) and covers the passivation film 27 thereafter, the adhesion at this portion is poor, and the passivation film is peeled off from this portion or in an extreme case. Causes a problem that a cavity 28 is generated at this location (FIG. 6).

An object of the present invention is to provide a method of manufacturing a semiconductor device having a multilayer film having an Al / TiN structure in which an Al film and a TiN film each having a trapezoidal etching shape are stacked by solving the above-mentioned problems. is there.

[0011]

In order to achieve the above object, an insulating film is formed on a semiconductor substrate, and a metal film for wiring mainly composed of aluminum or aluminum is formed on the insulating film. In a method for manufacturing a semiconductor device, an antireflection film is formed on a metal film, and a side wall of the film formed of the metal film and the antireflection film has a tapered shape extending toward the semiconductor substrate. Forming the metal film thereon; forming an anti-reflection film on the metal film; forming a patterned photoresist film on the anti-reflection film; The film is isotropically etched so that the side wall of the photoresist is tapered to spread toward the antireflection film, and the photoresist is used as a mask to selectively remove the antireflection film. And anisotropic etching, using the photoresist as a mask, etching the antireflection film and the metal film until the insulating film is exposed, and forming a sidewall of the antireflection film and the metal film, Forming a tapered shape extending toward the semiconductor substrate (that is, forming a processed shape of the antireflection film and the metal film into a trapezoidal shape).

An insulating film is formed on a semiconductor substrate, aluminum or a metal film for wiring mainly composed of aluminum is formed on the insulating film, and an antireflection film is formed on the metal film. In a method for manufacturing a semiconductor device in which a side wall of a film formed of an antireflection film has a tapered shape spreading toward the semiconductor substrate, a step of forming the metal film on the insulating film; Forming an anti-reflection film on the anti-reflection film, forming a patterned photoresist film on the anti-reflection film, the first isotropic etching of the photoresist film, the side wall of the photoresist film, Forming a tapered shape extending toward the anti-reflection film, selectively removing the anti-reflection film by a second isotropic etching using the photoresist film as a mask, The photoresist is used as a mask, and the anti-reflection film and the metal film are etched until the insulating film is exposed, and the anti-reflection film and the metal film are tapered to spread toward the semiconductor substrate. (Ie, forming the processed shape of the antireflection film and the metal film into a trapezoidal shape).

The metal film mainly composed of aluminum is
An Al-Si-Cu film or an Al-Si film is preferable. Preferably, the antireflection film is a TiN film. The isotropic etching is performed by using CF ₄ / O ₂ gas or SF ₆ /
Dry etching of O ₂ gas is preferable.

[0014] In the anisotropic etching of the CF ₄ / O ₂ gas, CF ₄ gas flow rate / O ₂ gas flow rate ratio may is to 9.5 / 0.5 7/3. Preferably, the anisotropic etching is dry etching of Cl ₂ / BCl ₃ gas. The O ₂ gas flow rate during the _second isotropic etching is preferably higher than the O ₂ gas flow rate during the first isotropic etching.

The flow rate of the O ₂ gas is preferably 1.5 to 3 times larger. As described above, by adjusting the flow rate of the O ₂ gas flowing when etching the upper TiN film, T
At the same time as the etching of the iN film, the photoresist that should be left is etched under the condition that the photoresist that should be left is actively etched so that the shape of the photoresist becomes trapezoidal. Further, in the step of etching the TiN film in the same chamber and the step of correcting the photoresist shape (to make a trapezoidal shape), the processing may be performed separately by changing the flow rate of the gas used.

After the upper TiN film is etched and the photoresist shape is corrected, the lower Al film is anisotropically etched. In this anisotropic etching of the Al film, the etching rate of the photoresist serving as a mask is about one time lower than the etching rate of the Al film serving as the etching target film.
Utilizing the relatively high speed of / 2, the etching of the Al film is advanced in such a manner that the photoresist that should be left behind is retreated, and processing is performed so that the finish becomes trapezoidal.

To explain further, first, the anisotropic etching of the Al film proceeds immediately below the photoresist, and
The protective film is formed on the side surface of the l film (FIG. 1)
(C)). However, at the same time, the photoresist is also etched and scraped, so that the portion where the photoresist film thickness is reduced due to the angle, the photoresist disappears, the surface of the Al film appears, and the etching of the Al film further proceeds. Goes on. By such a mechanism, the Al film has a trapezoidal shape.

[0018]

1A to 1E show a method of manufacturing a semiconductor device according to an embodiment of the present invention. FIGS. 1A to 1E are cross-sectional views of a main part manufacturing process shown in the order of processes. FIG.
Al—Si—Cu film 2 in which Si and Cu are added to Al
Is deposited on an insulating film 9 on a semiconductor substrate (hereinafter, simply referred to as a substrate 1) by a sputtering method to a thickness of 1 μm.
A TiN film 3 serving as an anti-reflection film is deposited on the i-Cu film 2 to a thickness of 30 nm, a photoresist 4 is coated on the TiN film 3, and a predetermined pattern is formed on the photoresist 4 by photolithography. . At this stage, the processed shape of the photoresist 4 is substantially vertical (FIG. 7A). Of course, the Al-Si-Cu film 2 may be an Al-Si film.

Next, CF ₄ / O ₂ = 70/30 scc is set in a plasma etching apparatus having parallel plate electrodes.
The isotropic etching was performed on the photoresist 4 and the TiN film 3 under the conditions of m, pressure 0.2 × 133 Pa, and RF power 200 W for about 2 minutes. At this stage, the shape of the photoresist 4 becomes trapezoidal, and the so-called side etching, in which the etching of the TiN film 3 proceeds to the lower part of the photoresist 4, is performed (FIG. 2B).

Incidentally, in the anisotropic etching of CF ₄ / O ₂ gas, in order to secure an appropriate etching rate, CF ₄ = 70 to 140 sccm and O ₂ = 10 to 60 sccm.
In the sccm range, the ratio of CF ₄ gas flow rate / O ₂ gas flow rate may be 7/3 to 9.5 / 0.5. Further, pressure = 0.2 to 1.0 × 133 Pa, RF power = 150 to
A range of 400W is good.

Further, CF_FourSF instead of gas₆Gas
May be used. This SF₆The conditions for using gas are:
SF₆/ O_Two= 50-60 sccm, O_Two= 10-20
sccm, pressure = 0.2-0.5 x 133 Pa, RF
W = 150 to 400 W is good. Also anti-reflective
Etching of the TiN film 3 as a film, and photoresist 4
Of shape correction (trapezoidal shape) etching
Etching for correcting the shape of the photoresist 4
In the case of (1), the O.sub.2
_TwoIncrease the gas flow by 10 to 40 sccm. this is,
First, the TiN film 3 is etched, and then the photo
This is effective when etching for correcting the shape of the resist 4.
You.

Next, the lower Al-Si-Cu film 2 was subjected to anisotropic etching in an atmosphere of Cl ₂ / BCl ₃ . The condition at this time is as follows: Cl ₂ = 25 to 100 scc
m, BCl ₃ = 5-30 sccm, pressure 2-5 × 133
mPa, power = 1000 to 2100 W. Due to this anisotropic etching, the Al—Si—Cu film 2 becomes
Is etched in a trapezoidal shape (the side wall is tapered toward the substrate) (FIG. 3C).

Further, this etching is performed to expose the insulating film 9 on the substrate 1 (FIG. 2D). At this stage, A
The l-Si-Cu film 2 has a trapezoidal shape. Next, the photoresist 4 and the side wall protective film 5 are removed (FIG. 4E). Trapezoidal Al-Si processed as described above
As shown in FIG. 2, a passivation film 6 was deposited on the substrate 1 on which the Cu film 2 was formed, and the coverage was observed. Streaks entering toward the Al film interface (1 in FIG. 5)
7 (dotted line in the circle) is not observed and the passivation film 6
It was confirmed that this trapezoidal shape contributed to the improvement of the coatability of the.

[0024]

According to the present invention, an antireflection film is formed on an Al film, a photoresist is coated thereon, and etching for patterning the antireflection film and correction of the photoresist to a trapezoidal shape are performed. After the etching is performed by isotropic etching, the Al film can be formed into a trapezoidal shape by anisotropically etching the Al film using these as a mask.

[Brief description of the drawings]

FIGS. 1A to 1E show a method of manufacturing a semiconductor device according to an embodiment of the present invention, wherein FIGS.

FIG. 2 is a diagram in which a substrate on which a trapezoidal Al film is formed is covered with a passivation film.

FIGS. 3A to 3C are cross-sectional views illustrating a conventional method of forming a wiring film having a laminated structure of an Al film and a TiN film, in which (a) to (c) are illustrated in the order of steps;

4A to 4D are diagrams showing another manufacturing method for forming a wiring film having a conventional laminated structure of an Al film and a TiN film, wherein FIGS.
Is a cross-sectional view of a main part manufacturing process shown in a process order.

FIG. 5 shows a substrate on which an Al film and a TiN film of FIG. 3 are formed;
Figure covered with passivation film

FIG. 6 shows a substrate on which an Al film and a TiN film of FIG. 4 are formed;
Figure covered with passivation film

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Al-Si-Cu film 3 TiN film 4 Photoresist 5 Side wall protective film 6 Passivation film 9 Insulating film

Claims (9)

[Claims] An insulating film is formed on a semiconductor substrate, a metal film for wiring mainly composed of aluminum or aluminum is formed on the insulating film, and an antireflection film is formed on the metal film. A method of manufacturing a semiconductor device in which a side wall of a film formed of a film and an anti-reflection film has a tapered shape spreading toward the semiconductor substrate, forming the metal film on the insulating film; Forming an anti-reflection film on the film; forming a patterned photoresist film on the anti-reflection film; and isotropically etching the photoresist and the anti-reflection film to form a sidewall of the photoresist. A tapered shape spreading toward the anti-reflection film, and selectively removing the anti-reflection film using the photoresist as a mask. Etching the anti-reflection film and the metal film until the insulating film is exposed using the mask as a mask, and forming sidewalls of the anti-reflection film and the metal film in a tapered shape extending toward the semiconductor substrate. And a method of manufacturing a semiconductor device. 2. An insulating film is formed on a semiconductor substrate, aluminum or a metal film for wiring mainly composed of aluminum is formed on the insulating film, and an antireflection film is formed on the metal film. A method of manufacturing a semiconductor device in which a side wall of a film formed of a film and an anti-reflection film has a tapered shape spreading toward the semiconductor substrate, forming the metal film on the insulating film; Forming an anti-reflection film on the film, forming a patterned photoresist film on the anti-reflection film, and removing the side wall of the photoresist film by first isotropic etching. Forming a tapered shape extending toward the anti-reflection film; selectively removing the anti-reflection film by a second isotropic etching using the photoresist film as a mask; Etching, using the photoresist as a mask, and etching the antireflection film and the metal film until the insulating film is exposed, and the side walls of the antireflection film and the metal film facing the semiconductor substrate. Forming a widened taper. 3. The metal film mainly composed of aluminum,
3. The method for manufacturing a semiconductor device according to claim 1, wherein the method is an Al-Si-Cu film or an Al-Si film. 4. The method according to claim 1, wherein the antireflection film is a TiN film. 5. The method according to claim 1, wherein the isotropic etching is dry etching of CF ₄ / O ₂ gas or SF ₆ / O ₂ gas. 6. The CF ₄ / O ₂ gas anisotropic etching, wherein a CF ₄ gas flow rate / O ₂ gas flow rate ratio is 7/3 to 9.5 / 0.5. 6. The method for manufacturing a semiconductor device according to item 5. 7. The method according to claim 1, wherein said anisotropic etching is performed using Cl ₂ / BCl.
_{3. The} method for manufacturing a semiconductor device according to claim 1, wherein dry etching is performed using _three gases. O ₂ gas flow rate when the 8. second isotropic etching, according to claim 2 or 5, characterized in that more than O ₂ gas flow rate when the first isotropic etching A method for manufacturing a semiconductor device. 9. The method according to claim 8, wherein the flow rate of the O ₂ gas is 1.5 to 3 times larger.