JPH11238732A - Wiring structure and formation of bonding pad opening - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiring structure of a stacked wiring of a semiconductor device, which has a bonding pad of good wire bonding characteristic and a high reliability, and to provide a method for forming a bonding pad opening. SOLUTION: A stacked wiring 30 is constituted of a TiN film 13, an Al alloy film 14, an Al2 O3 thin film 31 and a TiN film 15. A plasma SiN film 17, a CVD SiO2 film 16, the TiN film 15 and the Al2 O3 thin film 31 on the stacked wiring 30 are etched by plasma etching, and an bonding pad opening 32 is formed on a bonding pad part 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring structure and a method of forming an opening of a bonding pad, and more particularly, to a wiring structure of a semiconductor device and a method of forming a wire bonding pad opening formed in a bonding pad portion. The present invention relates to a structure and a method of forming an opening of a bonding pad.

[0002]

2. Description of the Related Art In recent years, as semiconductor devices have become more highly integrated, interconnects connecting constituent elements of the semiconductor devices have become increasingly finer.
Wiring widths and the like have become smaller than half microns. When the wiring width becomes narrow in this manner, disconnection due to electromigration or stress migration occurs in an Al film using a conventional Al film containing a small amount of Si or Cu as a wiring material, that is, an Al wiring using an Al alloy film. It has been found that there is a reduction in manufacturing yield and a problem in reliability.
In order to improve the resistance to electromigration and stress migration, TiN layers are formed above and below the Al film.
A laminated wiring provided with a film is used. In addition, when patterning an Al alloy film to form an Al wiring, there is a problem of a decrease in photoresist pattern accuracy due to a high reflectance of the Al alloy film at the time of pattern exposure in a photolithography process. The pattern accuracy is improved by providing on the Al film.

FIG. 2 shows an example of a wiring structure of a laminated wiring of a semiconductor device having a laminated wiring composed of a plurality of conductive films, which is also a wiring of a bonding pad portion, and a method of forming a bonding pad opening. It will be described with reference to FIG.
First, as shown in FIG. 2A, a TiN film 13 and a small amount of Si are formed on a field oxide film 12 on a semiconductor substrate 11.
An Al alloy film 14 which is an Al film containing Ti and a TiN film 15 are successively deposited. Then, the TiN film 15 /
By patterning the Al alloy film 14 / TiN film 13, T
The laminated wiring 2 composed of the iN film 15 / Al alloy film 14 / TiN film 13 is formed.

Next, a CVD SiO ₂ film 16 as a passivation film is deposited by a CVD method, and a plasma SiN film 17 is subsequently formed by a plasma CVD method.

Next, as shown in FIG. 2B, a photoresist 18 is applied, and the photoresist 18 is patterned to form an opening 19 of the photoresist 18 in the bonding pad 1. Thereafter, using the patterned photoresist 18 as a mask, plasma SiN is performed by a plasma etching method using an F-based gas.
The film 17, the CVD SiO ₂ film 16, and the TiN film 15 are etched to form a bonding pad opening 20 in the bonding pad section 1.

Next, as shown in FIG. 2C, the photoresist 18 is removed. During the plasma etching process, the photoresist 18 is hardened, and the photoresist is removed with a normal resist stripper. Since it becomes impossible, the photoresist 18 is first removed by ashing using a photoresist plasma ashing apparatus. After that, the photoresist 18 was formed on the photoresist 18 such as a step portion on the surface of the plasma SiN film 17 and on the surface of the Al alloy film 14 at the bottom of the bonding pad opening 20, which remained without being removed by ashing of the photoresist 18 by the plasma ashing apparatus. The reaction product film and the like are removed by a cleaning treatment with fuming nitric acid. As described above, the bonding pad opening 20 of the bonding pad portion 1 is formed, so that the surface of the Al alloy film 14 of the laminated wiring 2 is exposed at the bottom of the bonding pad opening 20, and the wafer process is started. The manufacture of the semiconductor device is completed.

In the above-described wiring structure of a semiconductor device and the method of forming a bonding pad opening, in the method of forming a laminated wiring 2, a TiN film 15 / Al alloy film 14 / The TiN film 15 and the Al alloy film 1
4, a contact potential difference is generated, and the plasma SiN film 17, CVD SiO ₂ film, and TiN film F
Since the bonding pad opening 20 is formed by plasma etching using a system gas, a large amount of F ions adhere to the surface of the Al alloy film 14 at the bottom of the bonding pad opening 20.

In this state, that is, a contact potential difference is generated between the TiN film 15 and the Al alloy film 14, and after the bonding pad opening 20 is formed, T
A contact potential difference exists in the portion where the iN film 15 and the Al alloy film 14 are stacked, and the Al potential at the bottom of the bonding pad opening 20 is reduced.
When a large amount of F ions are attached to the surface of the alloy film 14 and the bonding pad opening 20 is immersed in fuming nitric acid, an electrolytic etching action occurs, and the bonding pad opening 2 is formed.
A deep recess is formed on the surface of the Al alloy film 14 near the side wall of 0, or an insulating film is formed on the surface of the Al alloy film 14.

When the formation of the concave portion or the formation of the insulating film on the surface of the Al alloy film 14 described above occurs, a wire bonding failure occurs in the wire bonding step in the assembly process of the semiconductor device, the resistance of the wire bonding portion increases, and the bonding increases. There is a possibility that a problem such as occurrence of poor reliability of the semiconductor device due to the failure of the pad portion 1 may occur.

[0010]

In the conventional wiring structure and the bonding pad opening forming method described above, since the wiring structure is a laminated wiring in which different kinds of metals are stacked, the bonding structure after the plasma etching step for forming the bonding pad opening is performed. A battery is formed between the TiN film and the Al alloy film of the laminated wiring outside the pad opening, and a large amount of F ions adhere to the surface of the Al alloy film at the bottom of the bonding pad opening after the plasma etching process for forming the bonding pad opening. In the fuming nitric acid treatment process after the photoresist ashing due to the above, an electrolytic etching action of the Al alloy film near the side wall of the bonding pad opening occurs,
A deep concave is formed on the surface of the alloy film, or an insulating film is formed on the surface of the Al alloy film, thereby causing a wire bonding failure in a wire bonding step in an assembling process of a semiconductor device, an increase in resistance of a wire bonding portion,
There is a possibility that a problem such as the occurrence of poor reliability of the semiconductor device due to the failure of the bonding pad portion may occur. The present invention
It was made in consideration of the above circumstances, and the purpose is
An object of the present invention is to provide a wiring structure of a stacked wiring of a semiconductor device having a bonding pad with good wire bonding properties and high reliability, and a method of forming a bonding pad opening.

[0011]

SUMMARY OF THE INVENTION A wiring structure and a bonding pad opening forming method of the present invention are proposed to solve the above-mentioned problems. A first refractory metal compound film; an Al-based conductor film on the refractory metal compound film; It is characterized by comprising an insulating thin film of a predetermined thickness on a system conductor film and a second refractory metal compound film on the insulating thin film of a predetermined thickness.

Further, according to the method of forming a bonding pad opening of the present invention, in the method of forming a bonding pad opening of a semiconductor device having a laminated wiring having the above-mentioned wiring structure, the photoresist applied on the insulating film on the laminated wiring is patterned. Forming a photoresist opening for opening a bonding pad, and using a patterned photoresist as a mask by a plasma etching method using an F-based gas to form a second refractory metal compound film for the insulating film and the laminated wiring. And a step of forming a bonding pad opening by etching the insulating thin film, a plasma ashing step for removing the photoresist, and a cleaning treatment step using an acid-based solution.

Further, according to the present invention, there is provided a method of forming a bonding pad opening for a semiconductor device having a stacked wiring comprising a plurality of conductive films, which is also a wiring of a bonding pad portion. Patterning a photoresist applied on the insulating film on the wiring to form a photoresist opening for opening a bonding pad; and using the patterned photoresist as a mask, at least one of Cl-based gas and Br-based gas. A step of forming a bonding pad opening by etching at least an insulating film by a plasma etching method using a gas containing one of the gases, a plasma ashing step for removing a photoresist, and a cleaning treatment with an acid-based solution And a process.

According to the present invention, the laminated wiring is composed of the first refractory metal compound film, the Al-based conductor film, the insulating thin film and the second refractory metal compound film, By interposing an insulating thin film between the film and the Al-based conductor film, electron transfer between these metal films is suppressed, so that a contact potential difference is not generated. Therefore, a bonding pad opening is formed by a plasma etching method using an F-based gas. After this, in the cleaning treatment step using an acid-based solution, the electrolytic etching action on the surface of the Al-based conductor film and the formation of an insulating film on the surface of the Al-based conductor film can be suppressed. In the method of forming a bonding pad opening of the present invention, a bonding pad opening is formed in a bonding pad portion using a conventional laminated wiring by a plasma etching method using a Cl-based gas or a Br-based gas other than the F-based gas. Therefore, in the cleaning process using an acid-based solution after forming the bonding pad openings,
l The electrolytic etching effect on the surface of the conductor film is suppressed, and
l The formation of an insulating film on the surface of the conductor film is suppressed. Accordingly, it is possible to suppress the occurrence of wire bonding failure and reliability failure in the wire bonding process of the semiconductor device assembly process.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings. The same components as those in FIG. 2 referred to in the description of the prior art are denoted by the same reference numerals.

Embodiment 1 In this embodiment, a wiring structure of a laminated wiring of a semiconductor device having a laminated wiring composed of a plurality of conductive films, which is also a wiring of a bonding pad portion, and a bonding pad opening are formed. This is an example in which the present invention is applied to a forming method, which will be described with reference to FIG. First, as shown in FIG. 1A, a first refractory metal is formed on a field oxide film 12 on a semiconductor substrate 11 as a laminated film for forming a wiring structure of a laminated wiring which is a feature of the present invention. A compound film, for example, a TiN film 13 which is a refractory metal nitride film is deposited by, for example, a sputtering method to a thickness of about 100 nm, and then,
Al-based conductor film, for example, Al film containing 1% Si
An alloy film 14 is deposited to a thickness of about 400 nm by, for example, a sputtering method, and then an insulating thin film, for example, A
An l ₂ O ₃ thin film 31 is deposited to a thickness of about 5 nm by, for example, a sputtering method, and then a second refractory metal compound film, for example, a TiN film 15 which is a refractory metal nitride film is deposited by, for example, a sputtering method. Deposit about 100 nm.

[0017] The thickness d of the Al ₂ O ₃ thin film 31 described above, the potential of about contact potential difference due to the work function difference between the Al alloy film 14 and the TiN film 15, Al alloy film 14 and the TiN due to a tunnel current or the like 2 nm ≦ d ≦ 10 nm, which is not less than a thickness that does not cause electron transfer between the films 15 and that does not significantly reduce the effect of improving the resistance to electromigration and stress migration by the TiN film 15 above the Al alloy film 14. It is desirable that

Next, the above-described TiN film 15 / Al alloy film 14 / Al ₂ O ₃ thin film 31 / TiN film 13 are patterned to obtain a T
iN film 15 / Al alloy film 14 / Al ₂ O ₃ thin film 31 / T
A laminated wiring 30 made of the iN film 13 is formed. afterwards,
A CVD SiO ₂ film 16 as a passivation film is deposited to a thickness of about 300 nm on the above-described laminated film by a CVD method, and then a plasma S
An iN film 17 is deposited to a thickness of about 600 nm.

Next, as shown in FIG. 1B, a photoresist 18 is applied, and the photoresist 18 is patterned to form an opening 19 of the photoresist 18 in the bonding pad portion 1. Thereafter, using the patterned photoresist 18 as a mask, plasma SiN is performed by a plasma etching method using an F-based gas.
The film 17, the CVD SiO ₂ film 16, the TiN film 15 and the Al ₂ O ₃ thin film 31 are etched to form a bonding pad opening 32 in the bonding pad section 1.

As an example of the formation of the bonding pad opening 32 of the bonding pad section 1 described above, the plasma SiN film 17 is etched by a plasma etching method using a patterned photoresist as a mask, for example, using a microwave etching apparatus. For example, by a plasma etching method using a parallel plate type RIE apparatus, the CVD SiO ₂ film 16, the TiN film 15, and the Al ₂ O ₃
The thin film 31 and the bonding pad opening 3 are etched.
Form 2

The conditions for etching the various films using the above-described etching apparatuses are, for example, as follows. [Etching conditions for plasma SiN film 17] CF ₄ gas flow rate: 50 sccm O ₂ gas flow rate: 12 sccm Pressure: 50 Pa RF: 700 W [Etching conditions for CVD SiO ₂ film 16] CHF ₃ gas flow rate: 35 sccm CF ₄ gas Flow rate: 50 sccm Ar gas flow rate: 400 sccm N ₂ gas flow rate: 20 sccm Pressure: 160 Pa RF: 1400 W [Etching conditions for TiN film 15 and Al ₂ O ₃ thin film 31] SF ₆ gas flow rate: 40 sccm Pressure: 30 Pa RF: 450 W

Next, as shown in FIG. 1 (c), the photoresist is removed in the same manner as in the conventional example. However, the photoresist hardens during the plasma etching step. Then, the photoresist cannot be removed, so using a plasma ashing device,
The photoresist is removed by ashing. Thereafter, a reaction formed on the photoresist such as a step portion on the surface of the plasma SiN film 17 and on the surface of the Al alloy film 14 at the bottom of the bonding pad opening 32, which remained without being removed even by ashing of the photoresist by the plasma ashing apparatus. The film and the like are removed by a washing treatment with an acid-based solution, for example, fuming nitric acid. As described above, by forming the bonding pad openings 32 on the laminated wiring 30 of the bonding pad section 1, the manufacture of the semiconductor device in the wafer process is completed.

According to the wiring structure of the laminated wiring of the semiconductor device and the method of forming the opening of the bonding pad, which is also the wiring of the bonding pad portion, the plasma S which remains without being removed even by ashing of the photoresist is removed.
At the time of cleaning treatment with fuming nitric acid for removing photoresist such as a step portion on the surface of the iN film 17 and a reaction product film formed on the surface of the Al alloy film 14 at the bottom of the bonding pad opening 32, the Al alloy film 14 and TiN are removed. Al ₂ O between the film 15
₃ Due to the presence of the thin film 31, the Al alloy film 14 and the TiN film 1
5, the Al alloy film 14 and the TiN
There is no transfer of electrons between the films 15, so that A
Since there is no contact potential difference between the 1 alloy film 14 and the TiN film 15, no electrolytic etching action occurs. Since there is no occurrence of a contact potential difference between the Al alloy film 14 and the TiN film 15, the bonding pad opening 32 is formed by plasma etching using an F-based gas while maintaining good conventional workability. Can be cleaned with fuming nitric acid without being affected by F ions attached to the surface of the Al alloy film 14 at the bottom of the bonding pad opening 32.
Etching on the surface of the 1 alloy film 14 and formation of an insulating film on the surface of the Al alloy film 14 can be suppressed. Accordingly, it is possible to suppress the occurrence of wire bonding failure and reliability failure in the wire bonding process of the semiconductor device assembly process.

Embodiment 2 This embodiment is directed to a stacked wiring of the uppermost layer of a semiconductor device.
This is an example in which the present invention is applied to a method of forming a bonding pad opening in a wiring which also serves as a wiring of a bonding pad portion, which will be described with reference to FIG. First, as shown in FIG. 2A, for example, a TiN film 13 and an Al containing a small amount of Si
It is composed of an Al alloy film 14 and a TiN film 15 which are films. A CVD SiO ₂ film 16 as a passivation film and a plasma SiN film 17 are formed on the stacked wiring 2.

Next, as shown in FIG. 2B, a photoresist is applied and the photoresist is patterned to form a photoresist opening 19 for the bonding pad opening of the bonding pad portion 1. Next, using the patterned photoresist as a mask, etching by a plasma etching method using a Cl-based gas or a Br-based gas other than the F-based gas, which is a feature of the present invention, for example, a Cl-based gas using an ECR device, The plasma SiN film 17, the CVD SiO ₂ film 16, and the TiN are etched by plasma etching using a Br-based gas.
The film 13 is etched to form a bonding pad opening 20.
To form

The etching conditions for the above-mentioned various films using the above-described etching apparatuses are, for example, as follows. [Etching conditions for plasma SiN film 17] Cl ₂ gas flow rate: 100 sccm Pressure: 0.67 Pa RF: 80 W [Etching conditions for CVD SiO ₂ film 16] HBr gas flow rate: 80 sccm Cl ₂ gas flow rate: 20 sccm pressure: 1.33 Pa RF: 100 W [Etching conditions of TiN film 13] Cl ₂ gas flow rate: 100 sccm Pressure: 0.67 Pa RF: 100 W

Next, as shown in FIG. 2C, the photoresist is removed by ashing using a plasma ashing apparatus in the same manner as in the conventional example. Thereafter, a photoresist such as a step portion on the surface of the plasma SiN film 17 and a reaction product film formed on the surface of the Al alloy film 14 at the bottom of the bonding pad opening 20 remain without being removed even by ashing of the photoresist by the plasma ashing device. And the like are removed by a washing treatment with an acid-based solution, for example, fuming nitric acid. As described above, by forming the bonding pad openings 20 on the laminated wiring 2 of the bonding pad section 1, the fabrication of the semiconductor device in the wafer process is completed.

According to the bonding pad opening forming method of the bonding pad portion in the above-described conventional wiring structure, when the bonding pad opening 20 is formed, plasma using Cl-based gas or Br-based gas other than F-based gas is used. Since the etching is performed by the etching method, F ions do not adhere to the surface of the Al alloy film 14 at the bottom of the bonding pad opening 20, and the Al alloy film 14 and the TiN are removed in the cleaning process using fuming nitric acid after the photoresist ashing process.
Even if a contact potential difference occurs between the films 15, the electrolytic etching action on the surface of the Al alloy film 14 is suppressed, and the formation of an insulating film on the surface of the Al alloy film 14 is also suppressed. Accordingly, it is possible to suppress the occurrence of wire bonding failure and reliability failure in the wire bonding process of the semiconductor device assembly process.

Although the present invention has been described with reference to the two embodiments, the present invention is not limited to these embodiments. For example, Embodiment 1 of the present invention
In the above description, both the first and second refractory metal compound films of the laminated wiring are described as TiN films, but the first and second refractory metal compound films are made of a refractory metal such as W, Ti, Co, Ni, or the like. , A so-called refractory metal silicide film, a nitride film of a refractory metal such as W, Mo, Co, Ni, etc., a so-called refractory metal nitride film, or a first refractory metal compound film. A different refractory metal compound film may be used for the second refractory metal compound film. Further, in the first embodiment of the present invention, the insulating thin film of the laminated wiring is described as an Al ₂ O ₃ thin film, but may be an insulating thin film such as a SiO ₂ thin film and a SiN thin film. In addition, within the scope of the technical concept of the present invention, the process apparatus and process conditions can be appropriately changed.

[0030]

As is apparent from the above description, the wiring structure and the method for forming the bonding pad opening of the present invention are as follows.
The laminated wiring is composed of a first refractory metal compound film, an Al-based conductor film, an insulating thin film, and a second refractory metal compound film, and between the second refractory metal compound film and the Al-based conductor film. By interposing an insulating thin film, electron transfer between these metal films is suppressed, so that a contact potential difference is not generated. Therefore, cleaning with an acid-based solution after forming a bonding pad opening by a plasma etching method using an F-based gas. In the processing step, the electrolytic etching action on the Al conductor film surface and the formation of an insulating film on the Al conductor film surface can be suppressed. In the method of forming a bonding pad opening of the present invention, a bonding pad opening is formed in a bonding pad portion using a conventional laminated wiring by a plasma etching method using a Cl-based gas or a Br-based gas other than the F-based gas. Therefore, in the cleaning process using an acid-based solution after forming the bonding pad openings, the electrolytic etching action on the Al conductor film surface is suppressed, and the formation of an insulating film on the Al conductor film surface is suppressed. Accordingly, it is possible to suppress the occurrence of wire bonding failure and reliability failure in the wire bonding process of the semiconductor device assembly process.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a bonding pad portion of a semiconductor device for explaining steps of a first embodiment to which the present invention is applied in the order of steps.
A state in which an O ₂ film and a plasma SiN film are formed, (b)
Uses the patterned photoresist as a mask,
Plasma SiN film, CVD SiO ₂ film, TiN film, and Al ₂ O ₃ thin film are plasma etched to form bonding pad openings, and (c) is a state in which the photoresist has been removed and a cleaning process using fuming nitric acid has been performed. .

2A and 2B are schematic cross-sectional views of a bonding pad portion of a semiconductor device, illustrating a conventional method of forming a stacked wiring and a bonding pad opening in the order of steps, and explaining the steps of Embodiment 2 in the order of steps; After forming the laminated wiring,
A state in which a SiO ₂ film and a plasma SiN film are formed,
(B), using a patterned photoresist as a mask, a plasma SiN film, a CVD SiO ₂ film and Ti
A state in which a bonding pad opening is formed by plasma etching the N film, (c) after removing the photoresist,
This is a state in which a cleaning process using fuming nitric acid has been performed.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Bonding pad part, 2, 30 ... Laminated wiring, 11
... Semiconductor substrate, 12 ... Field oxide film, 13,15 ...
TiN film, 14 ... Al alloy film, 16 ... CVDSiO
₂ film, 17 ... plasma SiN film, 18 ... photoresist, 19 ... opening, 20, 32 ... bonding pad opening, 31 ... Al ₂ O ₃ thin film

Claims (10)

[Claims] 1. A wiring structure of a laminated wiring of a semiconductor device having a laminated wiring composed of a plurality of conductor films, which also serves as a wiring of a bonding pad portion, wherein: a first refractory metal compound film; An Al-based conductor film on a metal compound film, an insulating thin film of a predetermined thickness on the Al-based conductor film, and a second refractory metal compound film on the insulating thin film of the predetermined thickness A wiring structure of a stacked wiring of a semiconductor device. 2. The method according to claim 1, wherein the first refractory metal compound film and the second refractory metal compound film are one of a refractory metal nitride film and a refractory metal silicide film. The wiring structure of the stacked wiring of the semiconductor device according to claim 1. 3. The wiring structure of a stacked wiring of a semiconductor device according to claim 1, wherein said first refractory metal compound film and said second refractory metal compound film are TiN films. . 4. The insulating thin film is an Al ₂ O ₃ thin film, Si
O ₂ thin film and of the SiN film, characterized in that it is a one of a thin film, the laminated wiring of the semiconductor device according to claim 1 wiring structure. 5. The predetermined thickness d of the insulating thin film is 2n
2. The wiring structure of a laminated wiring of a semiconductor device according to claim 1, wherein m ≦ d ≦ 10 nm. 6. The method for forming a bonding pad opening of a semiconductor device having a laminated wiring having a wiring structure according to claim 1, wherein a photoresist applied on an insulating film on the laminated wiring is patterned. Forming an opening in the photoresist for the, using the patterned photoresist as a mask,
Forming a bonding pad opening by etching the insulating film and the second refractory metal compound film and the insulating thin film of the laminated wiring by a plasma etching method using an F-based gas; and removing the photoresist. A method for forming a bonding pad opening of a semiconductor device, comprising: a plasma ashing step for performing a cleaning process using an acid-based solution. 7. The F-based gas used for plasma etching when forming the bonding pad opening is S
7. The method for forming a bonding pad opening of a semiconductor device according to claim 6, wherein at least one of F ₆ gas, CF ₄ gas and CHF ₃ gas is included. 8. A method of forming a bonding pad opening of a semiconductor device having a laminated wiring composed of a plurality of conductive films, which is also a wiring of a bonding pad portion, wherein a photo-coated layer is formed on an insulating film on the laminated wiring. Patterning the resist to form a photoresist opening for bonding pad opening, and using the patterned photoresist as a mask,
A step of etching at least the insulating film to form a bonding pad opening by a plasma etching method using at least one of a Cl-based gas and a Br-based gas; and a plasma for removing the photoresist A method for forming a bonding pad opening of a semiconductor device, comprising: an ashing step; and a cleaning step using an acid-based solution. 9. A Cl-based gas used for plasma etching when forming the bonding pad opening is Cl-based gas.
9. The method for forming a bonding pad opening of a semiconductor device according to claim 8, wherein the gas contains one of the _two gases and the BCl ₃ gas. 10. A Br-based gas used for plasma etching when forming the bonding pad opening is H gas.
9. The method for forming a bonding pad opening in a semiconductor device according to claim 8, wherein the gas is Br gas.