KR100533967B1 - A forming method of pattern using ArF photolithography - Google Patents

Abstract

The present invention relates to a method for manufacturing a semiconductor device, and in particular, to provide a pattern forming method using an exposure source for argon fluoride, which can minimize the deformation of the pattern and enable narrow pattern formation. Forming an oxide film and an antireflective layer on the photoresist, performing a photolithography process using an argon fluoride exposure source to form an argon fluoride photoresist pattern on the antireflective layer, and etching the argon fluoride photoresist pattern Selectively etching the antireflection layer in a chlorine plasma atmosphere containing an O ₂ or N ₂ plasma to expose the oxide film surface, and using the remaining antireflection layer as a mask, and using the fluorine-based gas to form the oxide film. Argon Fluoride Exposure Source Including Optional Etching It provides a pattern forming method using the same.

Description

A forming method of pattern using ArF photolithography

TECHNICAL FIELD This invention relates to a semiconductor technology. Specifically, It is related with the pattern formation method using the argon fluoride (ArF) exposure source.

The microfabrication technology that has supported the progress of semiconductor devices is a photolithography technology, and it is no exaggeration to say that the improvement in resolution of this technology is directly connected to the future of high integration of semiconductor devices.

In general, the photolithography technique may be divided into an exposure process and a development process as a process of forming a pattern, but in recent years, the meaning of photolithography generally refers only to an exposure process.

Photolithography in the semiconductor process is applied to a substrate, such as a substrate for the purpose of forming a circuit board on a variety of materials on the substrate, a photoresist, that is, a mask (i.e. It is a technology that forms a photoresist pattern by transmitting light through the photoresist to develop a photoresist and then developing the photoresist. The substrate is etched using the photoresist pattern as an etch barrier to finally implement a desired pattern.

Since the beginning of mass production of semiconductor products based on DRAM (Dynamic Random Access Memory), the development of the photolithography technology has been rapid.

The resolution in the optical photolithography technique is inversely proportional to the wavelength of the exposure source. The wavelength of the light source used in the initial stepper adopting the "step and repeat" exposure method ranges from 436 nm (g-line) to 365 nm (i-). Nowadays, stepper or scanner type exposure equipment using deep ultra-violet (UV) of 248nm (KrF Excimer Laser) is mainly used.

Photolithography technology has been used to develop materials such as CAR (Chemically Amplified Resist) type photoresist, as well as the development of exposure equipment such as high aperture lens and hardware of 0.6 mm or more, namely aperture, mars, etc. In terms of process, TLR (Tri Layer Resist), BLR (Bi-Layer Resist), TSI (Top Surface Imaging), ARC (Anti Reflective Coating), and PSM (Phase Shift Mask) and OPC (Optical Proximity Correction) Many technological developments have been made.

The 248 nm DUV photolithography initially produced a number of problems, such as time delay effects and substrate dependence. However, in order to develop a product having a design of 0.15 μm or less, it is necessary to develop a technology with a new DUV photolithography technique having a wavelength of 193 nm (ArF Excimer Laser). However, even if a combination of various techniques for enhancing the resolution in the DUV photolithography technique is impossible to pattern less than 0.1㎛, the development of a photolithography technique having a new light source is actively progressing.

Currently, the closest technology is developing exposure equipment using electron beams and X-rays as light sources, and EUV (Extreme Ultraviolet) technology using weak X-rays as S-light sources is being developed.

The initial exposure equipment was a contact printer, in which a mask was placed directly on a substrate, and after exposure with eyes. This technology has been further developed to increase the resolution by reducing the gap between the mask and the substrate, which is then exposed to proximity printers such as soft contact and hard contact (10 μm or less).

Subsequently, through the steady development, in recent years, the development of exposure equipment using a KrF laser (λ = 248 nm) as a light source, the development of photoresist, and the improvement of other auxiliary technologies have enabled the pattern of 0.15 μm or less.

At present, an ArF (argon fluoride) laser (λ = 193 nm) is being developed to target a pattern up to 0.11 mu m. DUV photolithography is superior in terms of performance and resolution compared to i-rays, but process control is not easy. These problems can be divided into optical causes due to short wavelengths and chemical causes due to the use of chemically amplified photoresists. If the wavelength is shortened, the CD shake phenomenon due to the stationary wave effect and the reflection of reflected light due to the substrate phase become worse. CD shaking refers to a phenomenon in which the line thickness changes periodically as the degree of interference between incident light and reflected light changes depending on the slight thickness difference of the photoresist or the thickness difference of the substrate film. In the DUV process, a chemically amplified photoresist must be used to improve the sensitivity, and problems related to the reaction mechanism include PED (Post Exposure Delay) stability and substrate dependence.

The next exposure technique after KrF is ArF exposure technique. One of the key challenges of ArF exposure technology is the development of photoresist for ArF. ArF is a chemically amplified type such as KrF, but it is necessary to fundamentally improve the material. The difficulty in developing a photoresist material for ArF is that benzene rings cannot be used. Benzene rings have been used in photoresists for i-rays and KrF to ensure dry etching resistance. However, when the benzene ring is introduced into the ArF photoresist, since the absorbance is large at 193 nm, which is the wavelength region of the ArF laser, the transparency is low and the exposure to the lower portion of the photoresist is impossible. For this reason, the research of the material which can ensure dry etching resistance, does not have a benzene ring, and has good adhesive force and can develop in 2.38% TMAH is progressing. To date, many companies and research institutes around the world have published their research results. However, currently commercially available photoresist in the form of a polymer of COMA (CycloOlefin-Maleic Anhydride) or Acrylate system, or a mixture thereof has a benzene structure as described above.

Accordingly, as shown in FIG. 1A, a stripe pattern deformation occurs during a process such as landing plug contact (LPC) through photolithography using an ArF exposure source, or FIG. As shown in FIG. 1B, PR aggregates or plastic deformation during SAC etching and PR resistance is weak due to weak resistance of SF during SAC etching, resulting in weak durability of ArF photoresist. It is an urgent task to compensate for the weak physical properties of and fluorine-based gases.

The present invention proposed to solve the problems of the prior art as described above, an object of the present invention to provide a pattern formation method using an argon fluoride exposure source that can minimize the deformation of the pattern and enable the formation of a narrow pattern.

In order to solve the above problems, the present invention, by sequentially forming an oxide film and the antireflection layer on the substrate, by performing a photolithography process using an argon fluoride exposure source to form a photoresist pattern for argon fluoride on the antireflection layer Selectively etching the antireflection layer in a chlorine-based plasma atmosphere containing an O ₂ or N ₂ plasma using the argon fluoride photoresist pattern as an etching mask, and exposing the remaining surface of the oxide layer. Using a argon fluoride exposure source comprising the step of using a mask as a mask, and selectively etching the oxide film using a fluorine-based gas.

The present invention, when forming a pattern using a photoresist pattern for ArF, such as COMA or acrylate, after forming an organic antireflection layer having a certain etching resistance to the fluorine series to a predetermined thickness thereunder After etching the anti-reflection layer through plasma of chlorine-based plasma, the anti-reflection layer is used as an etch mask again, and selectively etching the lower etched layer using fluorine-based etching gas to minimize pattern deformation and form a narrow pattern. It characterized in that to enable.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can more easily implement the present invention.

2A to 2D are cross-sectional views illustrating a pattern forming process using an ArF exposure source according to an embodiment of the present invention, which will be described in detail with reference to the drawings.

First, as illustrated in FIG. 2A, a plurality of gate electrodes 11, for example, word lines or bit lines, in which silicides such as polysilicon and tungsten silicide are stacked on a substrate 10 on which various elements for forming a semiconductor device are formed. And so forth.

That is, a gate oxide film (not shown) is formed at the contact interface between the substrate 10 and the gate electrode 11, and the gate electrode is lost on the gate electrode 11 by subsequent self align contact or the like. A hard mask 12, such as a nitride film, is formed to prevent this.

Subsequently, an insulating film for a spacer such as a nitride film is deposited on the entire surface of the substrate including the gate electrode 11, and then a spacer 13 is formed on the sidewall of the gate electrode 11 through an entire surface etching process. (Advanced Planarization Layer) An etched layer 14 made of an oxide film, such as an oxide film, Boro Phospho Silicate Glass (BPSG), Spin On Glass (SOG), or High Density Plasma (HDP) oxide film, is formed.

Subsequently, a thick organic anti-refrective coating 15 was formed on the etched layer 14 to a thickness of 500 kPa to 3000 kPa, and then a photoresist for ArF was coated on the antireflective layer 15. Next, the photoresist pattern 16 is formed through a photolithography process using an ArF exposure source.

Specifically, the ArF photoresist, such as COMA or acrylate, is coated on the antireflection layer 25 to have a thickness of 1000 GPa to 5000 GPa, and at this time, to enhance the resistance of the photoresist pattern 16 according to etching. As an additional process, electron beam irradiation or Ar ion implantation may be performed alone or in combination, and then a test etching process using an exposure source for argon fluoride (not shown), that is, an exposure, development, and etching process may be performed. Through the photoresist pattern 16 is formed.

Next, as shown in FIG. 2B, the surface of the etched layer 14 is exposed by selectively etching the antireflection layer 15 while appropriately adjusting the temperature of the substrate 10.

Specifically, the antireflection layer 15 is selectively etched in a chlorine-based plasma atmosphere in which the substrate 10 is kept at a low temperature and Cl ₂ , SiCl _4, or HCl is alone or mixed, thereby forming a COMA forming the photoresist pattern 16. Etc., since the etching resistance to chlorine-based gas is stronger than that of fluorine-based gas, the anti-reflection layer 15 is etched using the photoresist pattern 16 as a mask through chlorine-based gas, thereby minimizing damage to the photoresist pattern 16 do.

At this time, N ₂ or O ₂ may be further included in the chlorine-based plasma.

Subsequently, as shown in FIG. 2C, the anti-reflection layer 15 is etched, and then, as shown in FIG. 2D, the remaining anti-reflection layer 15 is used as a mask, and the etched layer 14 is formed using fluorine-based gas. Etch selectively.

At this time, the temperature of the substrate 10 is maintained at 20 ° C. to 80 ° C., and the fluorine-based gas is selected from the group consisting of CH ₂ F ₂ , CF ₄ , C ₂ F ₆ , C ₄ F _6, and C ₄ F ₈ . Using at least one selected, it may further include argon gas or helium gas alone or in combination.

Here, when etching a portion of the etched layer 14, the etching target selection is determined in consideration of the thickness of the etched layer 14 formed on the gate electrode 11, here the hard mask 12, In an embodiment, a contact hole 17 is formed to selectively etch the etched layer 14 to expose the surface of the substrate 10 between the gate electrodes 11.

Subsequently, the polymer is removed as a by-product generated in the SAC process through the cleaning process, and then the pattern forming process is completed by removing the antireflection layer 15.

Accordingly, after application of the pattern forming process through the ArF photolithography process of the present invention shown in FIGS. 3 (a), 3 (b) and 3 (c), the center of the pattern as shown in the photographs in the plane and the cross section, respectively. It can be seen that pattern deformation is minimized at both the edge and the edge.

On the other hand, the pattern in one embodiment of the present invention described above may include all of the I-type isolated pattern or hole-shaped pattern.

In the present invention as described above, when forming a pattern through a photolithography process using an ArF exposure source, by forming an organic-based antireflection layer below the photoresist for ArF, by selectively etching the antireflection layer through chlorine-based plasma By minimizing the pattern deformation, the etched layer is etched using fluorine-based gas, thereby preventing the deformation of the PR pattern by the ArF photolithography process, and it is known through the examples that the narrower pattern can be formed. saw.

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.

The present invention described above, by making it possible to prevent the deformation and loss of the PR pattern according to the ArF photolithography process, it can be expected to have an excellent effect of improving the integration and process margin of the device.

 Figure 1a is a photograph showing the deformation of the pattern of the stripe shape when forming the landing plug contact using the ArF photolithography process,

1B is a photograph showing a phenomenon in which PR aggregates or mold deformation during SAC etching and a phenomenon in which the resistance of PR is weak due to weakness during SAC etching;

2A to 2D are cross-sectional views illustrating a pattern forming process using an ArF exposure source according to an embodiment of the present invention;

Figure 3 (a), 3 (b), 3 (c) is a photograph showing the pattern in the plane and cross-section after the application of the pattern forming process through the ArF photolithography process of the present invention.

* Explanation of symbols for the main parts of the drawings

10: substrate

11: gate electrode

12: hard mask insulating film

13: spacer

14: etching layer

17 contact hole

Claims (12)

delete delete Sequentially forming an oxide film and an antireflection layer on the substrate; Performing a photolithography process using an argon fluoride exposure source to form a photoresist pattern for argon fluoride on the antireflection layer; Selectively etching the antireflection layer in an chlorine-based plasma atmosphere containing an O ₂ or N ₂ plasma using the argon fluoride photoresist pattern as an etching mask to expose the oxide film surface; And Selectively etching the oxide layer using the remaining antireflection layer as a mask and using a fluorine-based gas Pattern formation method using an argon fluoride exposure source comprising a. The method of claim 3, wherein The chlorine-based plasma pattern forming method using an argon fluoride exposure source, characterized in that containing at least one of Cl ₂ , SiCl ₄ or HCl. The method of claim 3, wherein The argon fluoride photoresist pattern is a pattern forming method using an argon fluoride exposure source, characterized in that the thickness of 1000 ~ 5000Å. The method of claim 3, wherein The anti-reflection layer is a pattern forming method using an argon fluoride exposure source, characterized in that the thickness of 500 ~ 3000Å. The method of claim 3, wherein Forming the photoresist pattern for argon fluoride, Applying a photoresist for argon fluoride on the antireflection layer; Performing electron beam irradiation or argon ion implantation alone or in combination to improve the etching resistance of the argon fluoride photoresist; Forming a photoresist pattern by performing a photolithography process using an argon fluoride exposure source; Pattern formation method using an argon fluoride exposure source comprising a. The method of claim 3, wherein The argon fluoride photoresist is a pattern forming method using an argon fluoride exposure source, characterized in that it comprises a (CycloOlefin-Maleic Anhydride) or Acrylate (Acrylate). The method of claim 3, wherein The method of forming a pattern using an argon fluoride exposure source, characterized in that for maintaining the temperature of the substrate at 20 ℃ to 80 ℃ in etching the oxide film. The method of claim 3, wherein The fluorine-based gas pattern forming method using an argon fluoride exposure source, characterized in that at least one selected from the group consisting of CH ₂ F ₂ , CF ₄ , C ₂ F ₆ , C ₄ F ₆ and C ₄ F ₈ . The method of claim 10, And argon gas or helium gas in the fluorine-based gas alone or in combination. The method of claim 3, wherein After etching the anti-reflection layer, a pattern formation method using an argon fluoride exposure source, characterized in that it further comprises a strip.