JP2001351899A - Method of manufacturing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing semiconductor device by which a thin silicon film containing a large amount of metal can be worked in a good shape without generating etch residues. SOLUTION: When a silicon area 6B containing a large amount of metal is etched by performing plasma etching using a mixed gas of HBr gas and Cl2 gas, superior anisotropy is secured, because reaction products, etc., deposit and form side-wall protective films 8 on the side walls of a resist mask and the thin silicon film 10. In addition, the protective films 8 maintain the shape of the film 10 at the time of removing etching residues 9 by performing plasma etching using a mixed gas of CF4 gas and O2 gas after the silicon area 6B is etched.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a semiconductor device used for fine processing of a silicon-based material layer.

[0002]

2. Description of the Related Art In recent years, as the design rules of semiconductor devices have become highly miniaturized, as seen in highly integrated devices such as VLSI and ULSI, high selectivity and high anisotropy are also required in the field of plasma etching. There is a strong demand for simultaneously achieving various requirements such as performance, practical etching rate, low contamination, and low damage at the highest possible level. However, since these various requirements are mutually selected, in the actual process, etching is performed while appropriately adjusting them to a range acceptable in a practical level.

Conventionally, as a method for manufacturing a semiconductor device,
A fluorine-based gas is widely used for etching a silicon-based material layer (Japanese Patent Laid-Open No. 5-291197). In this method of manufacturing a semiconductor device, a substance to be etched in which silicon nitride and amorphous silicon are sequentially provided in layers on a substrate is placed in an etching chamber, and an etching gas introduced into the etching chamber is excited. Then, the amorphous silicon as the etching target material is etched. The etching gas at this time is a mixed gas of a fluorine-based gas in which carbon tetrafluoride and oxygen are mixed at a partial pressure ratio of 3: 1 and a chlorine-based gas, and the fluorine-based gas is a chlorine-based gas. The gas is mixed at a partial pressure ratio of about 15 to 67% with respect to the gas. According to this method of manufacturing a semiconductor device, the etching rate for amorphous silicon can be increased by changing the flow rate of the etching gas.

However, in the above-described method of manufacturing a semiconductor device, the etching shift is large, and the dimension of the pattern to be formed does not correspond to the width of the pattern forming mask.
Since the processing width cannot keep up with pattern miniaturization, there is a problem that required fine processing cannot be performed. In addition, this method of manufacturing a semiconductor device has a problem that when the base is a silicon oxide film, the base selectivity cannot be obtained and the base silicon oxide film is etched.

As a method of manufacturing a semiconductor device which solves such a problem, there is a method using a halogen-based chemical species (a chlorinated gas or a bromine-based gas) other than a fluorine-based chemical species as a main etching species (Japanese Patent Application Laid-Open No. HEI 9-163572). No. 7-335634). In this method of manufacturing a semiconductor device, F ^* (fluorine radical), which easily causes a spontaneous chemical reaction to a silicon-based material layer, is eliminated, and instead, an anisotropic mechanism such as Cl ⁺ , Br ⁺ is used. It is intended to secure a proper shape and to secure a high selectivity with respect to a gate insulating film (SiOx) which is a base material particularly when a gate electrode is processed.

In recent years, there has been proposed a method of manufacturing a semiconductor device in which etching is carried out in the presence of oxygen-based chemical species in addition to the Cl-based and Br-based etching species, and a SiOx-based reaction product is used for sidewall protection. (The 39th Symposium on Applied Physics (Spring Annual Meeting, 1992), Proceedings of the Lectures, p.50
4, Abstract No. 28p-NC-4). In this method of manufacturing a semiconductor device, in the Si etching using the HBr / O ₂ mixed gas, the resist mask is covered with the SiO ₂ -based material, thereby preventing the resist mask from retreating and achieving an anisotropic shape. ing.

FIGS. 4 (a) to 4 (c) are cross-sectional views showing steps for explaining a method of manufacturing a semiconductor device using the above HBr / O ₂ mixed gas.

First, as shown in FIG. 4A, a wafer in which a gate insulating film 43, a polysilicon film 44, a silicide film 45, and an antireflection film 46 are sequentially formed on a silicon substrate 42 is subjected to a predetermined process. A patterned resist mask 47 is formed.

Then, using the resist mask 47 as a mask, for example, an HBr / O ₂ mixed gas is discharged and dissociated, reactive ion etching (RIE) is performed, and the antireflection film 46 and the polycide film 45 are etched. The above RI
When E is performed, as shown in FIG. 4B, while the side wall of the resist mask 47 is covered with the side wall protective film 48, a region not masked by the resist mask 47 is removed.

Here, the sidewall protective film 48 contributes to achieving an anisotropic shape by preventing the resist mask 47 from receding. Note that this side wall protective film 4
8 is the direct oxidation of Si atoms released from the polycide film 45 by etching (or the etching reaction product Si).
(Oxidation of Brx) is mainly composed of SiOx-based products.
It also contains carbon-based reaction products and the like generated by sputtering. When plasma treatment using an oxygen-based gas is performed after plasma etching of the silicon-based material layer, the sidewall protective film is modified to have a composition close to SiO _2. What is necessary is just to dissolve and remove by solution processing (FIG. 4 (c)).

By using the method for manufacturing a semiconductor device, plasma etching having excellent anisotropy and ensuring high selectivity can be performed.

[0012]

By the way, the above Cl system,
In a method of manufacturing a semiconductor device using a Br-based etching species, fine processing of silicide or polysilicon is possible. However, when a silicon thin film containing a large amount of a metal element is etched, the metal element contained in the silicon thin film is removed. Cannot be etched, a residue is generated, and the silicon thin film cannot be etched into a good shape.

An object of the present invention is to provide a method of manufacturing a semiconductor device capable of processing a silicon thin film containing a large amount of metal into a good shape without generating an etching residue (residue).

[0014]

In order to achieve the above object, a method of manufacturing a semiconductor device according to the present invention is directed to a method of manufacturing a semiconductor device in which a silicon thin film containing metal is etched by plasma etching. Etching the silicon thin film by plasma etching using at least the bromine-based gas of the system gases; and etching the silicon thin film, and then performing metal etching by plasma etching using a mixed gas of a fluorocarbon-based gas and an oxygen gas. And removing the residue.

According to the method of manufacturing a semiconductor device having the above-described structure, when a silicon thin film is etched by plasma etching using a bromine-based gas, the etching is performed by a Br ⁺ ion assist mechanism and the reaction product S
By oxidation of iBrx, SiOx-based products and the like are deposited on the side walls of the resist mask and the silicon thin film to form a side wall protective film, and excellent anisotropy is secured. Further, in plasma etching using a bromine-based gas and a chlorine-based gas, excellent anisotropy is obtained and the etching rate is improved. In this case, a reaction product of the etching gas and the metal is present on the substrate as it is, and silicon is left using the metal element as a mask to generate a residue. Next, when plasma etching is performed using a fluorocarbon-based gas such as CF ₄ and an O ₂ gas as an etching gas, a metal element, C (carbon) and O (oxygen) are obtained.
Is bonded to form a compound, and the compound with CO has a lower boiling point than a compound of chlorine, bromine, fluorine and a metal element generally used for etching of polysilicon, so that the compound is externally provided from the etching apparatus. Easily discharged.
For example, comparing the melting point and boiling point of the reaction product between nickel and each etching gas, NiBr ₂ [melting point: 963 ° C.]
Compared to iCl ₂ [melting point: 1001 ° C.] NiF [sublimation at 1000 ° C. or more], nickel, C (carbon) and O
(Oxygen) bonded to tetracarbonyl nickel Ni (C
O) ₄ has a boiling point of 42.5 ° C. When this method of manufacturing a semiconductor device is used, the metal element is contained in the silicon thin film before etching at 1 × 10 ¹⁴ atoms / cm ^{3 to} 5 × 1.
Etching is possible even if it contains about 0 ¹⁸ atoms / cm ³ . At this time, silicon as a residue is also removed, but the shape of the silicon thin film can be maintained by the sidewall protective film.

Therefore, when etching a silicon thin film containing a large amount of metal (for example, a silicon thin film using a metal element which promotes crystallization to form a silicon thin film having high crystallinity), the etching residue of the metal element is reduced. High anisotropy processing can be performed without generation, and a silicon thin film containing a large amount of metal can be processed into a good shape.

Further, according to the method of manufacturing a semiconductor device of the present invention, in the method of manufacturing a semiconductor device in which a silicon thin film containing a metal is etched by plasma etching, at least the bromine-based gas and the chlorine-based gas are combined with each other. The method includes a step of etching the silicon thin film by plasma etching using a mixed gas of a fluorocarbon-based gas and an oxygen gas.

According to the method of manufacturing a semiconductor device described above, when a silicon thin film is etched by plasma etching using a bromine-based gas, anisotropic etching is performed by a Br ⁺ ion assist mechanism, and a reaction product Si is formed.
By oxidation of Brx, SiOx-based products and the like are deposited on the side walls of the resist mask and the silicon thin film to form a sidewall protective film,
Excellent anisotropy is ensured. Further, in plasma etching using a bromine-based gas and a chlorine-based gas, excellent anisotropy is obtained and the etching rate is improved. At this time, the metal contained in the silicon thin film is combined with a metal element, C (carbon) and O (oxygen) by a fluorocarbon-based gas such as CF ₄ and an O ₂ gas. Since the compound with CO has a lower boiling point than the compound of chlorine, bromine, fluorine and a metal element, it is easily discharged from the etching apparatus to the outside.

Therefore, when a silicon thin film containing a large amount of metal is etched, highly anisotropic processing can be performed without generating etching residue of a metal element. It can be processed into various shapes.

In one embodiment of the present invention, the fluorocarbon-based gas is CF ₄ , CHF ₃ , CH
Any one of ₂ F ₂ , C ₂ F ₆ , or C ₄ F ₈ , or one of the above CF ₄ , CHF ₃ , CH ₂ F ₂ , C ₂ F ₆ , or C ₄ F ₈ Characterized in that it is a mixed gas of at least two types.

According to the method of manufacturing a semiconductor device of the above embodiment, general CF ₄ , CH _{4 is} used as a fluorocarbon-based gas.
By using at least one gas of F ₃ , CH ₂ F ₂ , C ₂ F ₆ or C ₄ F ₈ , residues can be effectively removed.

Further, according to the method of manufacturing a semiconductor device of the present invention, in the method of manufacturing a semiconductor device in which a silicon thin film containing a metal is etched by plasma etching, at least a bromine-based gas out of a bromine-based gas and a chlorine-based gas, Etching the silicon thin film by plasma etching using a gas mixture with at least one of carbon monoxide and carbon dioxide.

According to the method of manufacturing a semiconductor device described above, when a silicon thin film is etched by plasma etching using a bromine-based gas, anisotropic etching is performed by a Br ⁺ ion assist mechanism, and a reaction product Si is formed.
By oxidation of Brx, SiOx-based products and the like are deposited on the side walls of the resist mask and the silicon thin film to form a sidewall protective film,
Excellent anisotropy is ensured. Further, in plasma etching using a bromine-based gas and a chlorine-based gas, excellent anisotropy is obtained and the etching rate is improved. At this time, in the metal contained in the silicon thin film, the metal element, C (carbon), and O (oxygen) are bonded by at least one of CO and CO ₂ . This compound with CO is
Since the boiling point is lower than that of a compound of chlorine, bromine, fluorine and a metal element, it is easily discharged from the etching apparatus to the outside.

Therefore, when a silicon thin film containing a large amount of metal is etched, highly anisotropic processing can be performed without generating etching residue of a metal element. It can be processed into various shapes.

Further, the method of manufacturing a semiconductor device according to one embodiment is characterized in that after the plasma etching, a residue is removed by wet etching using an etchant of an aqueous solution containing hydrofluoric acid.

According to the method of manufacturing the semiconductor device according to the above-described embodiment, after the plasma etching is completed, wet etching is performed using an etchant of an aqueous solution containing hydrofluoric acid, thereby easily removing the sidewall protective film as a residue. it can.

In one embodiment of the present invention, in the method of manufacturing a semiconductor device, the metal contained in the silicon thin film includes iron (Fe), nickel (Ni), cobalt (Co), ruthenium (Ru), rhodium (Rh), It is characterized by being at least one of palladium (Pd), osmium (Os), iridium (Ir), platinum (Pt), copper (Cu) and gold (Au).

According to the method of manufacturing a semiconductor device of the above embodiment, the metal element (Fe,
Ni, Co, Ru, Rh, Pd, Os, Ir, Pt, Cu and Au) have a high crystallinity.
Although it contains a large amount of metal, good anisotropic processing can be performed even for such etching of a silicon thin film.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for manufacturing a semiconductor device according to the present invention will be described in detail with reference to the illustrated embodiments.

(First Embodiment) FIGS. 1A to 1E and FIG.
3A to 3D are process cross-sectional views illustrating a method for manufacturing a semiconductor device according to a first embodiment of the present invention.
A method for manufacturing a semiconductor device using a metal element that promotes crystallization in forming a silicon thin film having high crystallinity will be described.

First, an amorphous silicon film is formed by plasma CV.
It is formed on an appropriate solid surface by a method D, a low pressure thermal CVD method, or another appropriate method. When the semiconductor device is configured, an amorphous silicon film 2 is formed on a substrate 1 (FIG. a)).

The substrate is not particularly limited, and a ceramic substrate or another substrate is used in addition to a glass substrate or a quartz substrate.

Next, nickel Ni is introduced into the surface of the formed amorphous silicon film 2 as a metal element for promoting crystallization of silicon (FIG. 1B).

In the first embodiment, nickel Ni is used as an element to be introduced. However, iron Fe, cobalt Co, ruthenium Ru, rhodium Rh, palladium Pd, Osmium Os,
One or more metal elements selected from iridium Ir, platinum Pt, copper Cu, and gold Au may be used. The silicon thin film containing these metal elements can also be etched by the method for manufacturing a semiconductor device of the present invention.

Thereafter, the silicon is crystallized by performing an annealing step at a heating temperature of 520 to 580 ° C. for several hours in an atmosphere of an inert gas such as nitrogen.

Next, an NSG (non-doped silicate glass) film 4 is formed on the silicon thin film 6 by a normal pressure CVD method to a thickness of about 200 nm, and a region where the concentration of the catalytic element is desired to be reduced (a gettering region) is formed by a resist. Then, using the resist (not shown) as a mask, the NSG film 4 is etched with buffered hydrofluoric acid or the like, and then the resist is removed.

As a result, the gettering region is NSG
This means that the film 4 is covered. Next, using the patterned NSG film 4 as a mask, a P element doping step is performed (FIG. 1C).

By this process, a region containing P element at a high concentration (gettering region) and a region to be gettered are formed (FIG. 1D).

Then, a heat treatment for gettering is performed, and nickel (Ni), which is a catalytic element present in the gettering region, is moved to the gettering region.
This gettering region has a higher concentration than nickel (Ni) initially introduced as a catalyst. At this time, the concentration of nickel (Ni) is about 3 × 10 ¹⁸ atoms / cm ³ (FIG. 1E).

In order to remove this gettering region, N
Etching is performed using the SG film as a mask. In the first embodiment, an NSG mask is used in the process, but a mask with a photoresist in particular may be used for processing.

The gettering region is a silicon thin film (silicon region 6B) containing a large amount of metal as referred to in this embodiment.

A method of etching the silicon region 6B containing a large amount of metal formed by the above procedure will be described below (FIG. 2A).

For example, using a magnetic field RIE (reactive ion etching) apparatus, in the first step, etching gas: HBr: Cl ₂ = 50: 50 sccm gas pressure: 100 mTorr RF power: 300 W magnetic field: 40 gauss (= 40 × 10 Etching is performed under the condition of ^-4 T). At this time, the silicon thin film 1
The sidewall protective film 8 is formed on the sidewall of the 0, NSG film 4, and a silicon thin film having a good shape is processed. However, at this point, nickel and nickel products are present on the substrate 1, and using these as a mask, a portion where the silicon thin film is not etched, that is, a residue 9 is present (FIG. 2B).

Subsequently, in the second step, etching is performed under the following conditions: etching gas: CF ₄ : O ₂ = 100: 25 sccm gas pressure: 100 mTorr RF power: 250 W magnetic field: 40 gauss (= 40 × 10 ⁻⁴ T). , Ni (CO) ₄ are generated and exhausted to the outside of the etching apparatus. At this time, the shape of the silicon thin film 10 is maintained due to the effect of the sidewall protective film 8 (FIG. 2C).

Under the etching conditions at this time, CF
The gas flow ratio of O _{2 to 4} is desirably 25% to 50%. However, when the NSG film is etched, oxygen or an oxygen compound is generated and contributes as an etchant. is there.

After the etching is completed, the resist is removed using oxygen plasma and the sidewall protective film 8 is oxidized, and then a dilute hydrofluoric acid solution treatment is performed to deposit the silicon thin film 10 on the sidewall (the sidewall protective film 8). 2), a silicon thin film 10 having a good shape can be obtained (FIG. 2 (d)).

The ICP (Inductively Coupled) of the substrate processed by the method for manufacturing a semiconductor device of the first embodiment is used.
Plasma: Inductively coupled high frequency plasma-MS (Mass Specto)
ram: mass spectrum) analysis revealed that the concentration of nickel detected from the substrate was about 4 × 10 ¹³ atoms / cm
It was confirmed that it was reduced to ³ . In other words, it can be seen that the silicon thin film containing a large amount of nickel could be etched without leaving nickel on the substrate.

In the first embodiment, a mixed gas of CF ₄ and O ₂ was used, but CHF ₃ , CH ₂ F ₂ , C ₂ F ₆ , or C ₂
A mixed gas of another fluorocarbon-based gas such as ₄ F ₈ and O ₂ may be used, or two kinds of CF ₄ , CHF ₃ , CH ₂ F ₂ , C ₂ F ₆ , or C ₄ F ₈ A mixed gas of the above gases and O ₂ may be used.

(Second Embodiment) FIGS. 3A to 3D are process cross-sectional views illustrating a method for manufacturing a semiconductor device according to a second embodiment of the present invention. A method of etching a silicon thin film containing a large amount of metal when CO is used as an additive gas for a substrate similarly manufactured by the steps shown in FIGS. 1A to 1E of the embodiment will be described.

First, the gettered silicon region 36A and the silicon region 3 containing a large amount of metal are formed on the substrate 31.
6B, and a BSG film 34 is provided on the silicon region 36A (FIG. 3A).

Next, the gettered silicon region 3
6A is a region which is masked by the NSG film 34 and is to be etched (a silicon region 36B containing a large amount of metal).
Is about 3 × 10 ¹⁸ atoms / cm ³ (FIG. 3B).

This silicon region 36B is subjected to a magnetic field RIE.
Using a (reactive ion etching) apparatus, etching gas: HBr: Cl ₂ : CO = 50: 50: 10 sccm Gas pressure: 100 mTorr RF power: 300 W Magnetic field: 40 gauss (= 40 × 10 ⁻⁴ T) Etching is performed.

At this time, the SiB generated by the effect of HBr
rx is the silicon thin film 20 (silicon region 36A) and B
A sidewall protection film 38 is formed on the sidewall of the SG film 34.

When nickel deposits in the etching region, tetracarbonylnickel Ni (CO) ₄ is generated by the combination of nickel and CO, and is exhausted out of the etching apparatus. In this manner, the silicon thin film 20 processed into a good shape with no residue of the metal element is obtained.
(FIG. 3 (c)).

After the etching is completed, the resist is removed using oxygen plasma and the sidewall protection film 38 is oxidized, and then a dilute hydrofluoric acid solution process is performed to deposit the silicon thin film 20 and the NSG film 34 on the sidewalls (sidewall protection). By removing the film 38), a silicon thin film having a good shape can be obtained (FIG. 3).
(d)).

As a result of performing ICP-MS analysis on the substrate processed by the method for manufacturing a semiconductor device according to the second embodiment, the concentration of nickel detected from the substrate was about 4 × 10 ^13.
It was confirmed that the concentration was reduced to atoms / cm ³ . In other words, it can be seen that the silicon thin film containing a large amount of nickel could be etched without leaving nickel on the substrate.

In the second embodiment, HBr, Cl ₂ and C
Although the etching was performed using the mixed gas with O, the etching may be performed using a mixed gas of at least a bromine-based gas and a chlorine-based gas and CO ₂ , or a mixture of a bromine-based gas and a chlorine-based gas. The etching may be performed using at least a bromine-based gas of the system gas and a mixed gas of CO and CO ₂ .

Further, the silicon thin film may be etched by plasma etching using a mixed gas of at least a bromine-based gas, a fluorocarbon-based gas, and an oxygen gas among the bromine-based gas and the chlorine-based gas. In this case, excellent anisotropy is obtained and the metal contained in the silicon thin film is converted into a metal element, C (carbon) and O (oxygen) by a fluorocarbon-based gas such as CF ₄ and a gas of O _2. Combine with each other to form a compound.This compound has a lower boiling point than that of a compound of chlorine, bromine, fluorine and a metal element, so that the compound is easily discharged from the etching apparatus to the outside, and an etching residue of the metal element is generated. Thus, a silicon thin film containing a large amount of metal can be processed into a good shape. In addition, the residue can be removed simultaneously with the etching in one step, and the step can be simplified.

[0059]

As is apparent from the above, according to the method of manufacturing a semiconductor device of the present invention, a bromine-based gas and a chlorine-based gas are used in a method of manufacturing a semiconductor device in which a silicon thin film containing a metal is etched by plasma etching. After etching the silicon thin film by plasma etching using at least a bromine-based gas, a large amount of metal is removed by removing metal residues by plasma etching using a mixed gas of a fluorocarbon-based gas and an oxygen gas. Includes silicon thin film including metal etching residue
It is possible to process into a good shape without generating (residue).

According to the method of manufacturing a semiconductor device of the present invention, in the method of manufacturing a semiconductor device in which a silicon thin film containing a metal is etched by plasma etching, at least a bromine-based gas of a bromine-based gas and a chlorine-based gas is used. When a silicon thin film containing a large amount of metal is etched by etching the silicon thin film by plasma etching using a mixed gas of a fluorocarbon-based gas and an oxygen gas, the metal element has a high difference without etching residue. Anisotropic processing can be performed, and a silicon thin film containing a large amount of metal can be processed into a good shape.

Further, by using at least one gas of general CF ₄ , CHF ₃ , CH ₂ F ₂ , C ₂ F ₆ , or C ₄ F ₈ as the fluorocarbon-based gas, residue can be reduced. It can be effectively removed.

According to the method of manufacturing a semiconductor device of the present invention, in the method of manufacturing a semiconductor device in which a silicon thin film containing a metal is etched by plasma etching, at least a bromine-based gas of a bromine-based gas and a chlorine-based gas is used. By etching the silicon thin film by plasma etching using a mixed gas of at least one of carbon monoxide and carbon dioxide, when etching a silicon thin film containing a large amount of metal, the etching residue of the metal element is reduced. High anisotropy processing can be performed without generation, and a silicon thin film containing a large amount of metal can be processed into a good shape.

After the plasma etching is completed, residues are removed by wet etching using an etchant of an aqueous solution containing hydrofluoric acid.
Residual sidewall protective films can be easily removed.

Further, metal elements (Fe, Ni, Co, Ru, Rh, Pd, Os, Ir, Pt, Cu) which promote crystallization of the silicon thin film.
Good anisotropic processing can be performed even when etching a silicon thin film containing a large amount of Au and Au.

[Brief description of the drawings]

FIGS. 1A to 1E are process cross-sectional views illustrating a method for manufacturing a semiconductor device according to a first embodiment of the present invention.

FIGS. 2A to 2D are process cross-sectional views illustrating a method of manufacturing the semiconductor device following FIG. 1E.

FIGS. 3A to 3D are process cross-sectional views illustrating a method for manufacturing a semiconductor device according to a second embodiment of the present invention.

4 (a) to 4 (c) are process cross-sectional views illustrating a conventional method for manufacturing a semiconductor device.

[Explanation of symbols]

 1, 31: substrate, 2, 32: amorphous silicon film, 3: Ni (metal element), 4, 34: NSG film, 6, 36: silicon thin film, 6A, 36A: gettered silicon region, 6B , 36B: silicon region containing a large amount of metal; 8, 38: side wall protective film; 9: residue; 10, 20: silicon thin film.

Claims (6)

[Claims] 1. A method of manufacturing a semiconductor device for etching a silicon thin film containing a metal by plasma etching, wherein the silicon thin film is etched by plasma etching using at least the bromine gas of a bromine gas and a chlorine gas. And etching the silicon thin film, and then removing a metal residue by plasma etching using a mixed gas of a fluorocarbon-based gas and an oxygen gas. 2. A method for manufacturing a semiconductor device for etching a silicon thin film containing a metal by plasma etching, wherein at least one of a bromine-based gas and a chlorine-based gas is mixed with a mixed gas of a bromine-based gas, a fluorocarbon-based gas and an oxygen gas. A method of manufacturing a semiconductor device, comprising a step of etching the silicon thin film by using plasma etching. 3. The method for manufacturing a semiconductor device according to claim 1, wherein the fluorocarbon-based gas is CF ₄ , CHF ₃ , CH
Any one of ₂ F ₂ , C ₂ F ₆ , or C ₄ F ₈ , or one of the above CF ₄ , CHF ₃ , CH ₂ F ₂ , C ₂ F ₆ , or C ₄ F ₈ A method of manufacturing a semiconductor device, comprising a mixed gas of at least two kinds of the above. 4. A method of manufacturing a semiconductor device for etching a metal-containing silicon thin film by plasma etching, comprising: at least one of a bromine-based gas and a chlorine-based gas; and at least one of carbon monoxide and carbon dioxide. A step of etching the silicon thin film by plasma etching using a mixed gas of the above. 5. The method for manufacturing a semiconductor device according to claim 1, wherein after the plasma etching, residues are removed by wet etching using an etchant of an aqueous solution containing hydrofluoric acid. And a method for manufacturing a semiconductor device. 6. The method for manufacturing a semiconductor device according to claim 1, wherein the metal contained in the silicon thin film is iron (Fe), nickel (Ni), cobalt (Co), ruthenium. (Ru), rhodium
(Rh), palladium (Pd), osmium (Os), iridium (Ir), platinum (Pt), copper (Cu), and gold (Au). Method.