JPH11176807A - Manufacture of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce conversion difference in pattern etching. SOLUTION: In a method for manufacturing a semiconductor device including a process of patterning a material layer containing silicon includes a process, wherein a hard mask material layer 6 is adhered onto the material layer containing silicon, a hard mask formation process in which the hard mask material layer 6 is patterned into a hard mask 16 of a specified pattern, and a hydrofluoric acid assisted process with a deposit on part of the surface of the material layer containing silicon exposed to the outside by the patterning of the hard mask material layer is removed are executed. After these process, a pattern etching process in which the material layer containing silicon is dry- etched with the hard mask 16 as an etching mask is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device such as a semiconductor integrated circuit, and more particularly, to a method of using a hard mask for a material layer containing silicon such as refractory metal silicide, polycrystalline silicon and single crystal silicon. And a method of manufacturing a semiconductor device having a patterning step of performing dry etching.

[0002]

2. Description of the Related Art As the density of a semiconductor device such as a semiconductor integrated circuit device increases, the technology of forming an electrode or a wiring is increased.
Higher precision miniaturization is increasingly required. This electrode or wiring processing technology occupies an important position in a semiconductor device manufacturing process.

In a semiconductor device, for example, a semiconductor integrated circuit device such as an SRAM (static random access memory), when forming a gate electrode or a wiring, silicon such as a refractory metal silicide layer or a polycrystalline silicon layer is used. For patterning of the material layer including the material layer, a so-called hard mask such as SiO ₂ or Si ₃ N ₄ is formed on this material layer, and using this as an etching mask, patterning by dry etching is performed to obtain a desired electrode or wiring. Is formed.

A method of manufacturing the conventional semiconductor device will be described with reference to FIG.
In this case, first, as shown in FIG. 2A, at least a gate forming portion of the surface of the semiconductor substrate 1, for example, a silicon (Si) substrate, has SiO ₂ having a required thickness by thermal oxidation.
A gate insulating layer 2 of a film is formed. A polycrystalline silicon layer 3 doped with impurities and having a low resistivity, and a refractory metal silicide layer 4 such as tungsten silicide (WSi) are successively formed thereon as a conductive layer for forming a gate electrode or a wiring. Layers are sequentially formed. Then, an anti-reflection film 5 for preventing reflection of exposure light at the time of pattern exposure on a photoresist layer to be described later is formed on the refractory metal silicide layer 4, and SiO ₂ , Si ₃ N ₄ or the like is formed thereon. The hard mask material layer 6 constituting the hard mask is deposited. Then, pattern etching by photolithography is performed on the hard mask material layer 6 and the antireflection film 5. For this purpose, first, a photoresist layer 7 having a pattern corresponding to a target electrode or wiring pattern is formed on the hard mask material layer 6 by deposition. This photoresist layer 7
Can be formed by so-called lithography in which a photoresist is applied, a required pattern is exposed, and a developing process is performed.

[0005] As shown in FIG.
Is used as a mask, dry etching is performed on the hard mask material layer 6 and the antireflection film 5 to form a hard mask 16 having a required pattern, and then the photoresist layer 7 is removed by so-called ashing.

Then, as shown in FIG. 2C, using the hard mask 16 as an etching mask, the refractory metal silicide layer 4 and the polycrystalline silicon layer 5 are patterned by dry etching to form the refractory metal silicide layer 4. For example, a gate electrode or a wiring 15 is formed by lamination with the polycrystalline silicon layer 3.

[0007]

However, in the case of the above-mentioned method, the etching of the layer to be etched is not performed satisfactorily. For example, as shown in FIG.
As a result, there is a case where the patterning faithful to the pattern of the photoresist layer 7 in FIG. 2A is not performed, and a so-called pattern conversion difference becomes large.

As a result of extensive studies, studies and considerations, the present inventors have found that the cause cannot be completely removed by ashing on a silicon-containing material layer, for example, a refractory metal silicide layer 4 as shown in FIG. 2B. Polymer 9 or a deposit 9 of a silicon oxide film as a by-product of the reactive gas at the time of ashing remains.
It has been found that when dry etching is performed using the mask 6 as a mask, the etching is also inhibited in portions other than the hard mask 16.

The present invention seeks to reduce the conversion difference in such pattern etching.

[0010]

That is, in the present invention, for example, refractory metal silicide, polycrystalline silicon,
In a method for manufacturing a semiconductor device having a patterning step of performing dry etching using a hard mask on a material layer containing silicon such as single crystal silicon, the patterning step is performed by forming a hard mask material layer on a material layer containing silicon. A silicon mask exposed to the outside by removing the hard mask material layer, and forming a hard mask of a required pattern by patterning the hard mask material layer to form a hard mask having a required pattern; A hydrofluoric acid treatment step for removing deposits on the surface of the material layer is followed by an etching step for performing dry etching on the material layer containing silicon using the hard mask as an etching mask.

According to the method of the present invention, the conversion difference can be effectively reduced, and the intended patterning can be reliably performed.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for manufacturing a semiconductor device according to the present invention will be described. In the present invention, as described above, for example, a method of manufacturing a semiconductor device having a patterning step of performing dry etching using a hard mask on a material layer containing silicon such as refractory metal silicide, polycrystalline silicon, single crystal silicon, etc. In the patterning step, a hard mask material layer is formed on a material layer containing silicon, and a hard mask is formed by patterning the hard mask material layer to form a hard mask having a required pattern. And a hydrofluoric acid treatment step of removing deposits on the surface of the material layer containing silicon exposed to the outside by removing the hard mask material layer, and then using the hard mask as an etching mask to contain silicon. And an etching step of performing dry etching on the material layer.

Here, the hydrofluoric acid treatment is performed in an amount of 1 in terms of an oxide film.
It is desirable to set the condition to obtain an exclusion effect of nm or more. That is, this hydrofluoric acid treatment is performed by using a separately prepared S
A hydrofluoric acid treatment is performed on the iO ₂ layer, and this treatment
The conditions are selected so that the iO ₂ layer can exclude 1 nm or more.

Referring to FIG. 1, a method of manufacturing a semiconductor device according to the present invention, in particular, forming a gate electrode or wiring by a so-called polycide layer in which a high melting point metal silicide, for example, a tungsten silicide layer is laminated on a polycrystalline silicon layer. An example of a method for manufacturing a semiconductor device having a step of performing will be described.

Also in this case, first, as shown in FIG. 1A, at least a gate forming portion of the surface of the semiconductor substrate 1, for example, a silicon (Si) substrate, is made of a SiO ₂ film having a required thickness by thermal oxidation. An insulating layer 2 is formed. Then, an n ⁺ -type polycrystalline silicon layer 3 doped with impurities and having a low resistivity as a conductive layer for sequentially forming a gate electrode or a wiring thereon and a refractory metal silicide such as tungsten silicide ( W
Si _x ) layer 4 is sequentially formed. Then, an anti-reflection film 5 for preventing reflection of exposure light when pattern exposure is performed on the photoresist layer described later is formed on the high-melting metal silicide layer 4, and a Si film is further formed thereon.
A hard mask material layer 6 constituting a hard mask of O ₂ , Si ₃ N ₄ or the like is deposited. Then, a photoresist layer 7 is formed in a pattern corresponding to a target electrode or wiring pattern for performing pattern etching by photolithography on the hard mask material layer 6.

The above-described gate insulating layer 2 is formed to a thickness of, for example, 10 nm by thermally oxidizing the Si semiconductor substrate 1 in, for example, a batch type thermal diffusion furnace. The polycrystalline silicon layer 3, refractory metal silicide layer 4 (tungsten silicide layer in this example), antireflection film 5, hard mask material layer 6, and photoresist layer 7 are formed by the following apparatus and conditions. it can.

The polycrystalline silicon layer 3 and the refractory metal silicide layer 4 are each formed to a thickness of about 100 nm.

Film forming apparatus and conditions for n ⁺ -type polycrystalline silicon layer 3: Equipment: low-pressure CVD (Chemical Vapor Deposition) equipment Raw material gas and supply flow rate: SiH ₄ gas 400 sccm PH ₃ gas (SiH ₄ base 0.5% ) 100 sccm Pressure: 40 Pa Film forming temperature: 550 ° C.

Film forming apparatus and conditions of tungsten silicide layer 4: Equipment: low pressure CVD apparatus Raw material gas and supply flow rate: SiH ₄ gas 1000 sccm WF ₆ gas 10 sccm Pressure: 26.6 Pa Film forming temperature: 360 ° C.

The anti-reflection film 5 is formed by forming a 33 nm thick SiO _x N _y film by the following film forming method.

Apparatus: Plasma CVD apparatus Source gas and supply flow rate: SiH ₄ gas 50 sccm N ₂ O gas 50 sccm Pressure: 330 Pa Film formation temperature: 380 ° C. RF (high frequency) power: 190W (13.56MHz)

Film forming apparatus and conditions for hard mask material layer 6: Equipment: room temperature CVD apparatus Source gas and supply flow rate: SiH ₄ (100%) 50 sccm Pressure: normal pressure Film forming temperature: 430 ° C.

As the photoresist layer 7, a positive type photoresist is used. For example, a novolak-based photoresist is applied to a thickness of 1.2 μm, and an i-line (365 n
m) by pattern exposure and development.

Using the photoresist layer 7 thus formed as a mask, the hard mask material layer 6 and the antireflection film 5 are patterned by dry etching to form a hard mask 16 as shown in FIG. 1B. This etching can be performed by the following method.

Etching apparatus and conditions for hard mask material layer 7 and antireflection film 5: Apparatus: magnetron plasma apparatus Etching gas and its flow rate: CF ₄ gas 20 sccm CHF ₃ gas 20 sccm Ar gas 200 sccm Gas pressure: 33 Pa Upper RF power: 800 W Stage temperature: 30 ° C

Thus, the hard mask 16 in which the hard mask material layer 6 is patterned is formed. Thereafter, the photoresist layer 7 is removed by ashing. This ashing can be performed by the following apparatus and conditions. Ashing device and conditions for photoresist layer 7: Device: counter electrode type ashing device Ashing gas and its supply flow rate: O ₂ gas 12000 sccm C ₂ F _{6 60} sccm Gas pressure: 2666 Pa RF power: 700 W Stage temperature: 250 ° C.

As described above, O ₂ containing C ₂ F ₆ gas
Ashing with plasma removes residues due to resist shrinkage.

Further, the resist and the polymer residue that could not be removed by the ashing are removed by a post-treatment by washing with sulfuric acid and hydrogen peroxide. The following apparatus and method can be used for the sulfuric acid-hydrogen peroxide treatment. Sulfuric acid peroxide treatment apparatus and method; Apparatus: Dip (liquid tank) type cleaning apparatus Treatment method: The following procedures (1) to (4) were performed. (1) Sulfuric acid aqueous solution (H ₂ SO ₄ : H ₂ O ₂ = 5: 1)
(110 ° C) for 300 seconds. (2) Rinse with deionized water (ultra pure water) for 300 seconds. (3) Final finish deionized water (ultra pure water) rinse 300
Seconds. (4) Spin drying 360 seconds.

In this manner, the photoresist layer 7 is removed. At this time, the refractory metal silicide layer 4, that is, the material layer containing Si, is exposed except for the portion where the hard mask 16 is applied. As a result, a deposit 9 of Si oxide, such as SiO _x, for example, SiO _2, is generated by the ashing post-treatment described above.

In the method of the present invention, the deposit 9 is removed. This removal is performed by a hydrofluoric acid treatment. This processing can be performed by the following apparatus and method. Hydrofluoric acid treatment apparatus and method: Apparatus: Dip (liquid tank) type cleaning apparatus Treatment method: The following procedures (1) to (4) were performed. (1) Immersion in 0.25% HF aqueous solution (25 ° C) for 190 seconds. (2) Rinse with deionized water (ultra pure water) for 300 seconds. (3) Rinse 300 definitive deionized water (ultra pure water)
Seconds. (4) Spin drying 360 seconds This treatment corresponds to 1 nm or more in terms of the oxide film described above. At this time, as shown in FIG. 1C, the deposit 9 shown in FIG. The surface of the silicide layer 4, in this example the WSi layer, is cleaned.

Thereafter, as shown in FIG. 1D, using the hard mask 16 as an etching mask, the refractory metal silicide layer 4 and the polycrystalline silicon layer 3 are etched, and the patterned refractory metal silicide layer 4 and the A gate electrode or wiring 15 is formed by lamination with the crystalline silicon layer 5.

The etching of the refractory metal silicide layer 4 and the polycrystalline silicon layer 5 by WSi can be performed by an etching method according to the following apparatus and conditions.

Etching apparatus and conditions: Apparatus: Magnetic field microwave plasma etching apparatus Etching gas and its supply flow rate: Cl ₂ gas 74 sccm O ₂ gas 6 sccm Gas pressure: 0.67 Pa Microwave power: 800 W (2.45 GHz) RF bias : 100W (2MHz) Stage temperature: 20 ° C

Further, in order to secure a selectivity with respect to the gate insulating layer 2, the RF bias was lowered, and overetching corresponding to a polycrystalline silicon thickness of 100 nm was performed. This etching can be performed by the following apparatus and conditions.

Over-etching apparatus and conditions Apparatus: Microwave plasma etching apparatus with magnetic field Etching gas and supply flow rate: Cl ₂ gas 74 sccm O ₂ gas 6 sccm Gas pressure: 0.67 Pa Microwave power: 800 W (2.45 GHz) RF bias: 70W (2MHz) Stage temperature: 20 ° C

The gate electrode or wiring layer 15 formed of the refractory metal silicide layer 4 and the polycrystalline silicon layer 5 formed as described above is removed by removing the deposit 9 of the silicon oxide film by the above-described hydrofluoric acid treatment. 9 is avoided, and is formed as a pattern accurately corresponding to the pattern of the photoresist layer 7, that is, a pattern having a small conversion difference.

[0037] Incidentally, the refractory metal silicide layer 4 is not limited to tungsten silicide WSi _X described above can be configured by Mo silicide, various high melting point metal silicide layer such as Ti silicide.

Further, the manufacturing method of the present invention is not limited to a method of manufacturing a semiconductor device having a step of forming a gate electrode or a wiring, but is applicable to a method of manufacturing a semiconductor device having pattern etching of various silicon-containing material layers. Can be applied.

[0039]

As described above, according to the method of the present invention,
Applied when performing dry etching using a hard mask for a material layer containing silicon such as a refractory metal silicide layer and a polycrystalline silicon layer, and reliably corresponds to the pattern of the photoresist layer used in forming the hard mask. Since pattern etching can be performed, pattern etching as intended, that is, pattern etching with a small conversion difference can be performed. Therefore, for example, a semiconductor device having excellent uniform characteristics can be manufactured by being applied to the formation of a gate electrode or a wiring such as an SRAM.

[Brief description of the drawings]

FIGS. 1A to 1D are schematic cross-sectional views of respective steps of an example of a method for manufacturing a semiconductor device according to the present invention.

2A to 2C are schematic cross-sectional views of respective steps of an example of a conventional method for manufacturing a semiconductor device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Semiconductor base, 2 ... Gate insulating layer, 3 ...
Polycrystalline silicon layer, 4 ... high melting point metal silicon layer, 5
... Anti-reflection film, 6 ... Hard mask material layer, 7 photoresist layer, 15 ... Electrode or wiring, 16 ...
・ Hard mask

Claims (2)

[Claims] 1. A method of manufacturing a semiconductor device having a patterning step for a material layer containing silicon, wherein the patterning step comprises: forming a hard mask material layer on the silicon-containing material layer; Patterning the mask material layer to form a hard mask having a required pattern, and removing the silicon-containing material layer surface exposed to the outside by removing the hard mask material layer A hydrofluoric acid treatment step, and thereafter, an etching step of performing dry etching on the material layer containing silicon using the hard mask as an etching mask. 2. The hydrofluoric acid treatment condition is 1 in terms of an oxide film.
2. The method for manufacturing a semiconductor device according to claim 1, wherein processing conditions are set to obtain an exclusion effect of at least nm.