KR20030042879A - A forming method of pattern using ArF photolithography - Google Patents

Abstract

PURPOSE: A method for forming a pattern using ArF exposing source is provided to be capable of minimizing the deformation of pattern by using a mask layer. CONSTITUTION: An etch object layer(11) is formed on a substrate(10). A photoresist pattern(12) for ArF is formed on the etch object layer(11). A mask layer(13) is formed on the resultant structure including an opened etch object layer(11a). The mask layer(13) is polished to expose the photoresist pattern(12). After removing the photoresist pattern(12), the etch object layer(11) is selectively etched by using the mask layer as a mask. Then, the mask layer is removed. At the time, the mask layer(13) contains SiLK(Silica Low-K).

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.

As is well known, the photolithography process includes a process of forming a photoresist pattern and a process of etching a layer to be etched through an etching process using the photoresist pattern as an etch mask to form a pattern having a desired shape such as a contact hole. Wherein the photoresist pattern includes a process of applying a photoresist on the etched layer, a process of exposing the photoresist using a prepared exposure mask, and a portion of the photoresist exposed or not exposed with a predetermined chemical solution; Through the development process.

On the other hand, the critical dimension of the pattern that can be implemented by the photolithography process (hereinafter referred to as CD) depends on the wavelength of the light source used in the above exposure process. This is because the CD of the actual pattern is determined by the width of the photoresist pattern that can be realized through the exposure process.

The wavelength of the light source used in the initial stepper adopting the “step and repeat” exposure method is from 436 nm (g-line) to 365 nm (i-line) and is now 248 nm (KrF Excimer Laser) wavelength. It mainly uses stepper or scanner type exposure equipment using DUV (Deep Ultra-violet). The 248nm DUV photolithography technology initially developed a product with a 0.18µm design with many 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.

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 has to be used to improve sensitivity, and problems related to the reaction mechanism include PED (Post Exposure Delay) stability and substrate dependence. Development of a photoresist for ArF. ArF is a chemically amplified type such as KrF, but the material needs to be fundamentally improved. ArF photoresist material development is difficult because 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 poor 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 in the world have announced their research results, but the commercially available polymers of COMO (CycloOlefin-Maleic Anhydride) or Acrylate system, or a mixture of these photoresists are It has a benzene structure as described above, so that a stripe pattern deformation or a SAC occurs during a process such as landing plug contact (LPC) through photolithography using an ArF exposure source. PR lumps or cluster plastic deformation during etching and PR resistance is weak due to weak SAC etching.

The most preferred method for ArF dry etching is to define a pattern at once using a recipe in which no photoresist deformation occurs. However, it is very difficult to develop a recipe in which the pattern deformation does not occur while satisfying all the various requirements of the process.

For example, an etching recipe currently used to form a bitline may include an etching step for removing an organic anti-refrective coating and an etching process for etching an insulating film between the bit line and the plug. Is composed of steps. At this time, in the case of the conventional anti-reflective layer etching recipe of CO / Ar / O ₂ series, the anti-reflective layer is etched with little etching of the insulating film, and then SAC of C ₄ F ₈ / CH ₂ F ₂ series The reason for using (Self Align Contact) is to minimize the loss of the gate hard mask exposed during the etching of the oxide-based insulating layer.

However, if the concept of this concept is used as it is for contact patterning using ArF photoresist, a problem occurs. When etching the anti-reflection layer, the upper portion of the photoresist is opened and the size of the contact is increased. The photoresist is severely deformed and polygonalized. As a result, this type of photoresist pattern is transferred to the lower portion as it is, the shape of the contact remains irregular.

Therefore, the weak durability of the ArF resistor and the weak physical properties of the fluorine-based gas, or the development of process technology is an urgent problem.

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 forming method using an argon fluoride exposure source that can minimize the deformation of the photoresist pattern for ArF.

1A to 1F are cross-sectional views showing a pattern forming process using an ArF exposure source according to the present invention.

* Explanation of symbols for the main parts of the drawings

10: substrate

11: etching target layer

11a: Etched layer on which pattern

12: photoresist pattern

13: mask layer

The present invention to solve the above problems, the step of applying a photoresist for argon fluoride on the etching layer; Forming a photoresist pattern by an exposure and development process using a predetermined mask so that an upper portion of the etched layer region where a predetermined pattern is to be formed is opened; Forming a mask layer on the entire structure including the open etching layer; Planarizing until the photoresist pattern is exposed; Removing the photoresist pattern; Selectively etching the etched layer using the mask layer as an etch mask; And it provides a pattern forming method using an argon fluoride exposure source comprising the step of removing the mask layer.

Preferably, the mask layer of the present invention can be deposited at a low temperature so that the photoresist is not damaged, is not damaged at all when removing the photoresist, and satisfies a condition that does not affect the etched layer when removing the mask layer. Characterized in that it comprises a substance,

The argon fluoride photoresist is characterized in that it comprises COMA (CycloOlefin-Maleic Anhydride) or Acrylate (Acrylate).

In the present invention, the photoresist pattern is used as an etch mask to form a photoresist pattern in the form of a negative value without etching the lower layer, and then the etching layer is etched by substituting a separate material with a mask layer, thereby weakly etching resistance of the photoresist for ArF. By minimizing the pattern deformation by complementing the technical feature.

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.

1A to 1F 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 shown in FIG. 1A, an Advanced Planarization Layer (APL) oxide film, Boro Phospho Silicate Glass (BPSG), Spin On Glass (SOG), or HDP (Panel) is formed on a substrate 10 having various elements for forming a semiconductor device. High Density Plasma) An etched layer 11 including an insulating film such as an oxide film or a conductive film such as polysilicon or tungsten is formed.

Subsequently, an ArF photoresist is applied onto the etched layer 11, and then the photoresist pattern 12 is formed through a photolithography process using an ArF exposure source. At this time, the photoresist pattern 12 is formed in an intaglio manner so that the upper portion of the etched layer region 11a on which the pattern is to be formed is opened.

Specifically, an ArF photoresist such as COMA or acrylate may be coated on the etched layer 11 to a predetermined thickness, and then an argon fluoride exposure source (not shown) and a predetermined reticle (not shown) are used. To selectively expose a predetermined portion of the photoresist, and to leave the exposed or unexposed portions through the developing process through the developing process, and then remove the etch residues through the post-cleaning process to remove the photoresist pattern 12. To form.

At this time, although not shown in the drawing, it is preferable to separately form an antireflection layer at an interface between the photoresist pattern 12 and the etched layer 11 in order to suppress diffuse reflection or the like during exposure.

Next, as shown in FIG. 1B, a mask layer 13 is deposited on the entire structure including the open etched layer 11a to cover the photoresist pattern 12, and as shown in FIG. 1C. Similarly, an etching back or chemical mechanical polishing process is performed. The polishing target or the etching target is exposed to the point where the upper portion of the photoresist pattern 12 is exposed. The mask layer 13 is made substantially the same height.

Here, the mask layer 13 may be deposited at a low temperature so that the photoresist pattern 12 may not be damaged, and the mask layer 13 may be made of a different material so as not to be damaged at all when the photoresist pattern 12 is removed. When it is removed to include the material that satisfies the condition that does not affect the etching layer (11).

Since the mask layer 13 is used as an alternative layer for overcoming the weak etching resistance of the photoresist pattern 12, the above-described characteristics must be provided, and the material may also vary depending on the underlying etching layer 11 and the like.

For example, SiLK (Silica Low-K), which is one of the low dielectric constant materials, can be deposited at a low temperature by spin coating, and can be removed without damaging the SiLK in the photoresist stripper when the photoresist pattern 12 is removed. The organic polymer is itself an organic polymer, which is a wet chemical for removing the O ₂ plasma or the polymer, and thus can be removed without damaging the etching layer 11 or the like.

Next, as shown in FIG. 1D, the photoresist strip process is performed using a photoresist stripper or the like to remove the photoresist pattern 12. In this case, loss of the mask layer 13 occurs as described above. Process conditions and material choices are appropriate.

Next, as shown in FIG. 1E, the etching target layer 11 is selectively etched using the mask layer 13 as an etching mask so that the etching target layer 11a on which the pattern is to be formed remains, as described above. The material of the etching layer 11 and the mask layer 13 should be different.

Next, as shown in FIG. 1F, the mask layer 13 is removed, and then, the desired pattern 11b forming process is completed by performing the cleaning process.

Therefore, a separate device for electron beam curing, which is used to prevent deformation during etching of the photoresist pattern, is also unnecessary.

As described above, the present invention provides a photoresist according to an etching process by forming a photoresist pattern at a negative angle when forming a photoresist pattern using an ArF exposure source and introducing a mask layer as an alternative material for improving the etching resistance of the photoresist for ArF. The embodiment has been found to minimize the deformation of the resist pattern and to form a fine pattern.

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 apparent to those of ordinary knowledge.

The present invention described above, by preventing the deformation and loss of the photoresist pattern according to the ArF photo-etching process, it can be expected to have an excellent effect that can ultimately improve the yield of the semiconductor device.

Claims (4)

Applying a photoresist for argon fluoride on the etched layer; Forming a photoresist pattern by an exposure and development process using a predetermined mask so that an upper portion of the etched layer region where a predetermined pattern is to be formed is opened; Forming a mask layer on the entire structure including the open etching layer; Planarizing until the photoresist pattern is exposed; Removing the photoresist pattern; Selectively etching the etched layer using the mask layer as an etch mask; And Removing the mask layer Pattern formation method using an argon fluoride exposure source comprising a. The method of claim 1, The mask layer, Argon fluoride comprising a material capable of low temperature deposition so as not to damage the photoresist, a material that is not damaged at all when removing the photoresist, and satisfies a condition that does not affect the etched layer when removing the mask layer Pattern formation method using an exposure source. The method of claim 1, The mask layer comprises a SiLK (Silica Low-K) pattern forming method using an argon fluoride exposure source. The method of claim 1, 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).