KR19980031847A - Metal wiring formation method of semiconductor device - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

Metal wiring formation method of a semiconductor device.

2. The technical problem to be solved by the invention

In a method of forming an antireflection film of metal wiring, in particular, in a lithography process using a short wavelength of 248 nm or more for patterning metal wiring as an exposure source, diffuse reflection occurs due to high reflection characteristics of the metal wiring, so that notching phenomenon occurs. To reduce the line width and short-circuit, thereby lowering the semiconductor manufacturing yield device reliability.

3. Summary of Solution to Invention

The purpose of the present invention is to provide a method of forming a multi-layer antireflection film (ARL) on a metal wiring film to improve the absorption coefficient of light energy to reduce reflectivity.

4. Key points of the invention

It is used for a method that can improve the manufacturing yield due to process stability by preventing scum of photoresist.

Description

Metal wiring formation method of a semiconductor device.

In general, as semiconductor devices are increasingly integrated, there are many difficulties in forming fine patterns by lithography.

Currently, polysilicon, silicide, aluminum, and tungsten have a high surface reflectivity, and the image contrast is degraded due to severe interference between incident light and reflected light during fine patterning. ) Uniformity and DOP are severely degraded.

In addition, when the high reflection film on the semiconductor substrate has a step, notching may occur in an unexposed area due to secondary exposure due to diffuse reflection. The notching phenomenon causes a short circuit due to a decrease in the line width, and also lowers semiconductor manufacturing yield and device reliability.

In particular, it is a metal wiring material for semiconductor devices, which has low resistance and excellent conductivity.

Although tungsten and aluminum are commonly used, tungsten has an excellent step coverage characteristic for contact holes with a large aspect ratio, and thus is increasingly used for manufacturing highly integrated devices. Aluminum has a process characteristic opposite to tungsten. In addition, the reflectivity of the substrate is also about 20% to 50% higher than that of tungsten, which is a difficult problem in the lithography process.

Furthermore, the exposure source used in the lithography process is G-ray (436nm), I-ray (365nm), DUV (200-300nm), VUV (100-200nm), etc. as the exposure wavelength is reduced by the light scattering effect As the degree of diffuse reflection is further deepened, it is not easy to suppress the notching phenomenon. Accordingly, an anti-reflective layer (ARL) such as SiON, SiN, TiN, and SiC is additionally formed on the high reflective film to provide a semiconductor substrate. In attempting to reduce the reflection characteristics of the high reflection film, in the aluminum and tungsten of the metal wiring using the shorter light source than the DUV, sufficient anti-reflection film properties cannot be formed only by the inorganic antireflection film (ARL) of a single layer, which lowers the reliability of the semiconductor device. There was a problem that notching phenomenon occurs.

The present invention devised to solve the above problems is a method of forming a metal wiring of a semiconductor device that can prevent the notching phenomenon by reducing the diffuse reflection to the high reflection layer of the metal wiring in the lithography process using a DUV or more light source. To provide that purpose.

1 to 3 are cross-sectional views of a metal wiring process of a semiconductor device according to an embodiment of the present invention.

* Description of Signs of Main Parts of Drawings *

1: silicon substrate 2: lower layer

3: conductive film 4: interlayer insulating film

5: lower titanium nitride film 6: metal film

7: upper titanium nitride film 8: silicon oxynitride film

9: photoresist

In order to achieve the above object, the present invention provides a method for forming a metal wiring of a semiconductor device, the method comprising: forming an interlayer insulating film on the entire structure formed a predetermined conductive layer on a semiconductor substrate; Forming a photoresist pattern on the interlayer insulating layer to make contact with the conductive layer; Forming a contact hole using the photoresist pattern as an etch barrier and removing the photoresist pattern; Sequentially forming a first titanium nitride film and a metal film on the entire structure, and forming a second titanium nitride film and a silicon oxynitride film for an anti-reflection film on the metal film; Forming a photoresist pattern for forming a metal film on the anti-reflection film silicon oxynitride film; Patterning a metal film using the photoresist pattern as an etch barrier; And removing the photoresist pattern.

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

1 to 3 are cross-sectional views illustrating a method of forming an anti-reflection film of a semiconductor device according to an embodiment of the present invention.

As shown in FIG. 1, a predetermined lower layer 2 is formed on the silicon substrate 1, and a predetermined conductive film 3 is formed on the lower layer. Then, the conductive film is patterned to a predetermined size and the overall structure is formed. It is sectional drawing which shows the interlayer insulation film 4 formed in the upper part.

As shown in FIG. 2, a photoresist pattern for contact etching is applied to form a conductive line between the metal wiring and the conductive film, and a contact hole is formed using the photoresist pattern as an etch barrier. A lower titanium nitride (TiN) film is formed to reduce the contact resistance of coverage, and then a metal film 6 is deposited, followed by an upper titanium nitride (TiN) film. In this case, the upper titanium nitride (TiN) film may not sufficiently exhibit the characteristics of the anti-reflection film in an exposure process having a short wavelength such as far ultraviolet (DUV). Therefore, by forming a silicon oxynitride film (SiOxNy) 8 formed at a predetermined composition ratio on the upper titanium nitride (TiN; 7) film, the antireflection film is improved in efficiency for an exposure source having a wavelength greater than far ultraviolet (DUV). Next, it is sectional drawing which shows the photoresist 9 pattern formed in order to pattern the said metal film. At this time, the metal film 6 is made of tungsten and aluminum, the lower titanium nitride (TiN; 5) film is formed to a thickness of about 200 ~ 800Å, the silicon oxynitride (SiOxNy; 7) is about 200 ~ 400Å The upper TiN; 8) is formed to a thickness of about 200 kPa-800 kPa.

In addition, the conditions for the composition of the silicon oxynitride film (SiOxNy; 7) are used in the plasma chemical vapor deposition (PECVD) method and the SiH ₄ : N ₂ O: N ₂ gas 40 ~ 200sccm: 40 ~ 100sccm: 1000 ~ 3000sccm The RF power is adjusted to about 350 w, the pressure in the reaction chamber is about 3 (Torr), and the wafer temperature is about 200 to 500 ° C.

As shown in FIG. 3, after the lithography process using deep ultra violet (DUV) is performed to etch the photoresist 9 pattern with an etch barrier to pattern the metal film 6, the photoresist is patterned. It is sectional drawing which shows that the resist was removed. In this case, the DUV uses a wavelength of 248 nm.

On the other hand, the reflective property (R) for the antireflection layer is as follows.

R = n-ik

Where n, the real part of the reflectivity equation, is the refractive index of the antireflection film, and the imaginary part of the equation is the light energy absorption coefficient of the antireflection film. In this case, the reflectivity (R) is affected by the type, composition ratio and composition method of the material.

For example, since n is a refractive index of the antireflection film, there is a difference depending on the physical properties of the material. However, k is an optical energy absorption coefficient of the antireflection film, so the composition ratio and composition method of the antireflection film are affected. If the composition ratio and composition method are executed differently to maximize the absorption coefficient k, the refractive index of the antireflection film naturally decreases and the reflectance R also decreases.

Therefore, the present invention forms a conventional titanium nitride (TiN) film as an anti-reflection film (ARL) when forming a fine pattern using far ultraviolet rays of 248 nm or more on metal wires having high reflectivity such as tungsten and aluminum, The energy absorption coefficient (k) is increased, and thus the optical reflection characteristic R = 1.5-i0.13 shows low reflection characteristics.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes are possible in the art without departing from the technical spirit of the present invention. It will be clear to those of ordinary knowledge.

Accordingly, the present invention provides a sufficient low reflection layer (ARL) effect in the lithography process using a short wavelength of 248 nm or more as an exposure source by constructing a multilayer having two or more layers of thin films having different compositions and optical properties. It is effective in improving physical stress and improving electrical reliability of wiring materials.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming metal wiring in a semiconductor device, and more particularly, to a method of forming an anti-reflective layer (ARL), which serves to prevent diffuse reflection in a highly reflective metal wiring in which there are steps in a lithography process. It is about.

Claims (5)

In the metal wiring forming method of a semiconductor device, Forming an interlayer insulating film over the entire structure in which a predetermined conductive layer is formed on the semiconductor substrate; Forming a photoresist pattern on the interlayer insulating layer to make contact with the conductive layer; Forming a contact hole using the photoresist pattern as an etch barrier and removing the photoresist pattern; Sequentially forming a first titanium nitride film and a metal film on the entire structure, and forming a second titanium nitride film and a silicon oxynitride film for an anti-reflection film on the metal film; Forming a photoresist pattern for forming a metal film on the anti-reflection film silicon oxynitride film; Patterning a metal film using the photoresist pattern as an etch barrier; And And removing the photoresist pattern. The method of claim 1 Wherein the first titanium nitride film is formed to a thickness of about 200 kW to about 800 kW. The method according to claim 1 or 2, Wherein the silicon oxynitride film is formed to a thickness of about 200 kPa-400 kPa. The method of claim 3, wherein And the second titanium nitride film is formed to a thickness of about 200 kW to about 800 kW. The method of claim 3, wherein The silicon oxynitride film is formed by using a gas in which SiH ₄ : N ₂ O: N ₂ is mixed in a ratio of 40 to 200 sccm: 40 to 100 sccm: 1000 to 3000 sccm.