KR100278832B1 - Method of forming an anti reflection film in a semiconductor device - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a method for forming an antireflection film of a semiconductor device.

2. Technical problem to be solved by the invention

In the structure in which the silicon oxide film is formed on the conductive film, the existing nitride film or oxynitride film which is deposited to reduce the reflectance due to the increase of reinforcement / cancellation interference is required, but the absorption rate of the nitride film or oxynitride film is about 1.0 or less. Because of the low level of, the thickness must be increased to reduce their reflectivity. However, increasing the thickness not only makes the etching process difficult, but also degrades the performance of the device.

3. Summary of the Solution of the Invention

In the present invention, by forming a partially oxidized amorphous silicon film on the structure where the conductive film and the silicon oxide film are formed to absorb the reflected light during the exposure process to form a photoresist pattern, it is possible to form an ultrafine line width pattern with improved uniformity. have.

Description

Method of forming an anti reflection film in a semiconductor device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device. In particular, a semiconductor having a uniform line width pattern can be formed when a patterning process is performed by forming an amorphous silicon film partially oxidized in a structure in which a silicon oxide film is formed on a conductive film. A method of forming an anti-reflection film of an element.

As the semiconductor device is highly integrated, the line width of the device is smaller, which makes it difficult to pattern. In order to pattern the conductive film with a small line width, the resolution must be good, and the resolution is proportional to the degree of optical diffraction. The optical diffraction phenomenon becomes worse as the line width becomes smaller and the wavelength of light becomes longer, so the resolution at this time is inferior. In order to solve this problem and realize a smaller line width, light of shorter wavelength should be used.

However, when the light wavelength is shortened, the reflectance of the conductive film is increased. Increasing reflectance causes non-uniformity of line width by constructive / destructive interference through photoresist. Therefore, in order to reduce reflectance, a nitride film or an oxynitride film is deposited on the conductive film with a predetermined thickness.

On the other hand, in order to form a pattern of a transistor or a capacitor of ultra-fine structure, a structure in which a silicon oxide film having a predetermined thickness is formed on the conductive film is patterned. In this case, since there is also a reinforcement / destructive interference through the silicon oxide film in addition to the conventional photoresist film, the degree of non-uniformity of the line width is further increased, which is very sensitive to the thickness uniformity of the silicon oxide film. Therefore, the uniformity of the line width is reduced and the finer the line width, the more serious the problem on the device. As a result, it is difficult to form transistors or capacitor structures of uniform size, which lowers yield and reliability.

In the structure in which a silicon oxide film having a predetermined thickness is formed on the conductive film, the existing nitride film or oxynitride film deposited to reduce the reflectivity requires a higher absorption rate or thickness because the reinforcement / cancellation interference is greater. However, since the absorption rate of the nitride film or oxynitride film is about 1.0 or less, it is necessary to increase the thickness in order to reduce the reflectivity, but if the thickness is increased, the etching process becomes difficult and the bottom of the gate oxide film or capacitor structure of the transistor is increased. It causes a large etch loss, which degrades the device's performance.

Accordingly, an object of the present invention is to provide a method for forming an antireflection film of a semiconductor device for forming a pattern having a uniform line width by easily performing a subsequent etching process by obtaining a stable degree of absorption of light during an exposure process.

The present invention for achieving the above object is a step of sequentially forming a conductive film and a silicon oxide film on the semiconductor substrate, the step of forming a partially oxidized amorphous silicon film on the silicon oxide film, the partially oxidized amorphous silicon film, silicon And etching the selected regions of the oxide film and the conductive film to form a pattern.

1 (a) to 1 (c) are cross-sectional views of devices sequentially shown in order to explain a method for forming an antireflection film of a semiconductor device according to the present invention.

2 (a) and 2 (b) are graphs showing the light absorption and light refractive index characteristics according to the light wavelength of the partially oxidized amorphous silicon film used in the present invention.

<Description of the symbols for the main parts of the drawings>

1: semiconductor substrate 2: conductive film

3: silicon oxide film 4: partially oxidized amorphous silicon film

5: photosensitive film 5a: exposure region

5b: non-exposed area

The present invention will be described in detail with reference to the accompanying drawings.

1 (a) to 1 (c) are cross-sectional views of devices sequentially shown in order to explain a method for forming an antireflection film of a semiconductor device according to the present invention.

Referring to FIG. 1A, a conductive film 2 is formed over a semiconductor substrate 1, and a silicon oxide film 3 is formed over the semiconductor substrate 1.

Conducting film (2) is a silicide film such as a polysilicon film as a wiring material highly reflective at a color wavelength of less than 500㎚, tungsten silicide (WSi _x), titanium silicide (TiSi _x), cobalt silicide (CoSi _x), tungsten (W ), Aluminum (Al), titanium nitride (TiN), copper (Cu) and the like.

The silicon oxide film 3 is used as a hard mask for preventing the upper end of the conductive pattern from being etched by the lack of the photosensitive film thickness during etching, or as a sacrificial film for forming a three-dimensional structure. As the silicon oxide film 3, SiO _x , PSG, BSP, BPSG, or the like is used depending on the purpose of use.

In this state, when the photosensitive film is deposited and then subjected to an exposure process, light (ultraviolet) passes through the silicon oxide film 3 and is reflected by the conductive film 2. At this time, the reflected light and the incident light pass through the silicon oxide film 3 to cause reinforcement / cancellation interference and enter the photosensitive film in an amplified and reduced state. This lowers the line width uniformity of the photosensitive film pattern. Since the degree of constructive / destructive interference is sensitive to the thickness of the silicon oxide film 3, the worse the uniformity of the thickness, the worse the uniformity of the line width.

As a method for solving such a problem, in the present invention, a partially oxidized amorphous silicon film 4 is formed on the silicon oxide film 3 to a thickness of about 50 to 500 Å.

The partially oxidized amorphous silicon film 4 is oxidized to about 0 to 40% of silicon. The absorption rate is large and the absorption rate can be easily adjusted according to the degree of oxidation. Deposit. At this time, the gas injected for deposition adds N ₂ O and H ₂ to SiH ₄ , Si ₂ H ₆ or SiH ₂ Cl ₂ gas, and the temperature is about 300 to 500 ° C. for PECVD and about 500 to 650 ° C. for LPCVD. The pressure is 0.1-10 Torr. At this time, the degree of partial oxidation is determined according to the injection amount of N ₂ 0, it is injected in a ratio of 2: 1 or more with SiH ₄ , Si ₂ H ₆ or SiH ₂ Cl ₂ gas.

Referring to FIG. 1B, an exposure process is performed after the photosensitive film 5 is coated on the partially oxidized amorphous silicon film 4. When the exposure step is performed, light passes through the silicon oxide film 3 under the exposure region 5a of the photosensitive film and is reflected by the conductive film 3. Reflected light passes through the silicon oxide film 3 again and is complemented / offset, but the absorbed and canceled light is absorbed by the partially oxidized polycrystalline silicon film 4 and is blocked from being incident on the photosensitive film 5. When the photoresist layer is formed, a photosensitive film pattern having a uniform line width CD is formed.

Referring to FIG. 1C, an etching process is performed using the photoresist pattern as a mask to sequentially remove the partially oxidized amorphous silicon film 4, the silicon oxide film 3, and the conductive film 2 to form a pattern. Remove the pattern.

2 (a) and 2 (b) are graphs showing the light absorption and light refractive index characteristics according to the light wavelength of the partially oxidized amorphous silicon film used in the present invention, wherein the partially used amorphous silicon film used in the present invention is It shows that it shows superior properties than the oxynitride film.

As described above, according to the present invention, by depositing a partially oxidized amorphous silicon film on the structure on which the conductive film and the silicon oxide film are formed, a photoresist pattern is formed, thereby obtaining a sufficient degree of absorption with a low thickness antireflection film. Therefore, a uniform ultrafine pattern can be obtained, and as a result, a transistor or a capacitor of uniform size can be formed. A transistor or capacitor structure of uniform size can ensure stable performance, and can solve problems such as short circuits between adjacent transistors and capacitors, thereby improving device reliability and yield. In addition, since a finer pattern can be implemented using the present invention, it is easy to develop a semiconductor device having a higher degree of integration.

Claims (7)

Sequentially forming a conductive film and a silicon oxide film on the semiconductor substrate; Forming a partially oxidized amorphous silicon film on the silicon oxide film; And etching the selected regions of the partially oxidized amorphous silicon film, the silicon oxide film, and the conductive film to form a pattern. The method of claim 1, The conductive film is a polycrystalline silicon film, a silicide film, tungsten, aluminum, titanium nitride and copper, characterized in that any one of the anti-reflection film forming method of the semiconductor device. The method of claim 1, The silicon oxide film is SiO _x , PSG, BSP and BPSG any one of the anti-reflection film forming method of the semiconductor device. The method of claim 1, The anti-oxidation film forming method of a semiconductor device according to claim 1, wherein the partially oxidized amorphous silicon film has a degree of oxidation of silicon of 1 to 40% and a thickness of 50 to 500 GPa. The method of claim 1, In the partially oxidized amorphous silicon film, N ₂ O and H ₂ gas are added to any one of SiH ₄ , Si ₂ H ₆ and SiH ₂ Cl ₂ gas, and plasma chemical vapor deposition and low pressure are applied at a pressure of 0.1 to 10 Torr. A method for forming an anti-reflection film for a semiconductor device, characterized in that the deposition by any one of the chemical vapor deposition method. The method of claim 5, The plasma chemical vapor deposition method is carried out in a temperature atmosphere of 300 to 500 ℃, low pressure chemical vapor deposition method is carried out in a temperature atmosphere of 500 to 650 ℃, the anti-reflection film forming method of a semiconductor device. The method of claim 1, And determining the degree of partial oxidation according to the first dose of the partially oxidized amorphous silicon film N ₂ 0 gas, SiH _4, the injection ratio of the Si ₂ H _6, and SiH ₂ Cl ₂ gas any one of the gas and the N ₂ 0 gas of which is It is 2: 1 or more, The anti-reflective film formation method of the semiconductor element characterized by the above-mentioned.

Images