JP2005115171A - Method for manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To uniformly align a polymer by using interfacial alignment of a surfactant by incorporating a surfactant into a resist and to reduce line edge roughness of a pattern obtained after development in a single layer resist process for forming lines by exposure to electron beams or light. <P>SOLUTION: A resist 11 is applied on an undercoat layer 10 and patterned by a conventional exposure method 16 (with electron beams or light). The resist 11 used is prepared by adding a surfactant 13 to a polymer. The surfactant 13 comprises a hydrophobic group 15 and a hydrophilic group 14. By applying the resist containing the surfactant on the undercoat layer 10, the hydrophilic group 14 is aligned inward the resist on the interface of the resist 11 and air. As the pattern 11a obtained by exposure and development has a uniform microscopic structure of the polymer depending on the alignment of the surfactant, the line edge roughness can be reduced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a semiconductor device using an improved resist material, and more particularly to a method for manufacturing a semiconductor device using a chemically amplified resist.

  In recent years, semiconductor devices have been increasingly integrated, and the pattern miniaturization has been rapidly progressing. Along with this, the required CD control range tends to become narrower, and as one of the CD controls, disturbance of the resist pattern end, so-called line edge roughness (LER), is required to be miniaturized, and the control is performed. The situation is extremely difficult. Since this LER affects the line width variation in the etching process after resist patterning, a value of several nm level is required for 3σ which is a manufacturing management method.

  The polymer currently used for the resist is a polymer having a molecular weight of about 100, and the size of one polymer corresponds to several nm. Furthermore, since this polymer is agglomerated and clustered by several polymer molecules, the pattern patterned using this resist has a factor of increasing LER. Thus, in the current resist, since LER depends on the polymer type, LER cannot always be improved even if the polymer is optimized.

  A pattern forming method using a conventional resist will be described with reference to FIG. 3 which is a schematic sectional view showing the process. First. As shown in FIG. 3A, a resist 31 is applied to the base 30. Next, as shown in FIG. 3B, the resist 31 is exposed using a mask (not shown). By this exposure, a non-photosensitive area 31a and a photosensitive area 31b are formed. Next, as shown in FIG. 3C, when this is developed, a pattern 31a is formed. As shown in FIG. 4, the obtained pattern 31a has irregularities on the pattern side wall and the upper surface. FIG. 4 is an enlarged schematic view of the pattern portion 38 of FIG.

The resist constituting the pattern is formed by agglomerating clusters of resist polymer microcrystals or polymer molecules (hereinafter referred to as “polymer microstructures”). The polymer microstructures are randomly formed in the resist. Is located.
In FIG. 4, the polymer microstructure 32 of the polymer, which is a material constituting the resist that occupies a large part of the resist, is randomly and discretely dispersed in the resist 4, and thus the polymer microstructure When the body is dispersed in the resist pattern, the patterned resist interface portion is uneven, corresponding to the polymer microstructure.

In order to prevent this line edge roughness, it is known that PEB is first performed at a high temperature (see Patent Document 1). However, according to this method, when a resist having poor heat resistance is used, a thermal history remains in the resist, which may adversely affect its characteristics.

JP 2003-68602 A

The present invention improves the occurrence of unevenness at the edge of a resist pattern in lithography using a conventional resist. By improving the resist microstructure, the unevenness (line) of the resist interface after patterning is improved. The object is to reduce edge roughness (LER).

  The present invention has been made paying attention to the fact that a polymer microstructure in a resist can be oriented by adding a surfactant to the resist.

The present invention comprises a step of applying a resist material containing a surfactant to the surface of the underlayer and drying to form a resist layer;
Irradiating the resist layer with light, X-rays or electron beam to expose the resist layer;
Heat treating the exposed resist layer;
A method of manufacturing a semiconductor device, comprising: at least a step of alkali-developing the heat-treated resist layer to form a pattern without unevenness at an end portion.

In the present invention, the resist material is preferably a chemically amplified resist material. The surfactant is preferably a surfactant that is not decomposed by the exposure light and does not volatilize by the heat treatment.

As described above, the line edge roughness of the resist pattern can be effectively reduced by adding a surfactant to the conventional resist. In addition, since the present invention does not go through a special process, it is possible to obtain a good pattern without reducing the throughput.

  The resist material used in the present invention contains at least a polymer that is solubilized or cross-linked by an acid, a photoacid generator, a surfactant, and an organic solvent.

  In the present embodiment, the resist is preferably a chemically amplified resist that enables lithographic fine patterns with high resolution.

  The chemically amplified resist according to the present embodiment is composed of a polymer as a resist body, a photoacid generator (PAG), a surfactant, and an organic solvent for dissolving them.

As the polymer constituting the resist, a polymer that is solubilized or cross-linked by the action of an acid is used. Specifically, polyhydroxystyrene (PHS), or a mixed material of PHS and a methacrylate copolymer (ESCAP). Known polymer materials such as acrylic polymers and fluorine-containing polymers can be used.
These polymers have polar groups (hydrophilic groups) such as hydroxy groups (—OH) and carboxyl groups (—COO ⁻ ) in the side chains, and the main chain is composed of carbon and hydrogen. It consists of a non-polar group (hydrophobic group) alkyl chain.

  Photoacid generators include bissulfoniudiazomethanes, nitrobenzyl derivatives, polyhydroxy compounds and aliphatic or aromatic sulfonic acid esters, onium salts, sulfonylcarbonylalkanes, sulfonylcarbonyldiazomethanes, halogen-containing triazine compounds. , Oxime sulfonate compounds, and phenylsulfonyloxyphthalimides can be used.

  The surfactant used in the present embodiment has a highly polar group (hydrophilic group) and a less polar group (hydrophobic group) in the molecule.

As the surfactant, any of an anionic surfactant, a cationic surfactant, a nonionic surfactant, and a zwitterionic surfactant can be used.
Examples of the anionic surfactant include fatty acid sodium salts, alpha sulfo fatty acid esters, alkyl benzene sulfonates, alkyl sulfates, alkyl ether sulfate esters, and alkyl sulfate triethanolamine. Examples of the cationic surfactant include alkyltrimethylammonium salt, dialkyldimethylammonium chloride, alkylpyridinium chloride and the like. Nonionic surfactants include fatty acid diethanolamine, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, and the like. Examples of the zwitterionic surfactant include alkyl carboxybetaines.

The surfactant used in the present embodiment must not be decomposed by exposure light in the resist exposure process, and must not be volatilized in the heat treatment process. It is. Examples of the surfactant having such requirements include surfactants having a molecular weight of 230 or more.
These surfactants are preferably materials that do not contain a metal impurity element so as not to contaminate the semiconductor device.

  The amount of the surfactant to be blended in the resist is preferably about 1 to 10% by weight. When the amount is less than the above range, the effect of adding the surfactant is not exhibited. On the other hand, when the amount exceeds the above range, the mechanical strength of the pattern is lowered, which is not preferable.

Hereinafter, the principle of pattern formation when the resist material is used will be described. A chemical amplification resist, which is a mixed material, is generally formed from a polymer, an acid generator (PAG), and an organic solvent that dissolves them, and a component called a quencher (basic substance) may be added. In the present invention, as described above, a surfactant having a hydrophilic group and a hydrophobic group in the molecule is further blended.
Pattern formation using a resist having such a composition will be described with reference to FIG. 1 which is a schematic cross-sectional view of the process and FIG. As shown in FIG. 1A, in the resist 11 applied on the base 10, a surfactant 13 having a high potential energy is arranged at the interface between the resist and air. Also in the pattern 11a obtained by exposing and developing the resist 11 as shown in FIGS. 1B and 1C, the surfactant is oriented, and accordingly, the polymer microstructure constituting the resist. As a result, the line edge roughness of the resist pattern is also improved. That is, as shown in FIG. 2 which is an enlarged view of the pattern, the polymer microstructure 12 is oriented with the interface arrangement of the surfactant 13. Due to the orientation of the polymer constituting the resist, the polymer positions at the resist pattern interface are aligned. As a result, the unevenness (line edge roughness: LER) at the interface can be reduced.

  Hereinafter, the semiconductor manufacturing method of the present embodiment will be described in the order of steps with reference to FIG. 1 which is a schematic sectional view showing the process of the present invention.

  First, as shown in FIG. 1A, a resist 11 is applied to a thickness of 200 to 300 nm on an underlayer 10 on which various thin films are formed on a silicon wafer semiconductor substrate. The present embodiment is characterized in that a surfactant is added to this resist material.

  In this step, after the resist 11 is applied and until the resist 11 is dried, the surfactant 13 moves in the resist 11 and, as shown in FIG. Arrange at the interface. As described above, there is a hydrophilic group in the polymer side chain of the resist 11, and the surfactant 13 is disposed so that this hydrophilic group and the hydrophilic group 14 of the surfactant 13 are close to each other. Will be oriented.

  Next, after drying the resist and performing a pre-bake treatment at a temperature of 100 ° C. or less for about 15 minutes, as shown in FIG. 1B, exposure is performed with light, X-rays or electron beams using a mask not shown To do.

Next, as shown in FIG. 1 (c), after the heat treatment after exposure, development is performed with an alkali developer such as tetramethylammonium hydroxide to obtain a pattern.
The heat treatment in this process is “post-exposure squeezing” called PEB, which reduces the unevenness of the pattern edge due to the influence of standing waves during exposure, or the acid action by the catalytic action of a chemically amplified resist. It is carried out to accelerate the generation of the above, and a conventionally used condition can be adopted.

FIG. 2 shows an enlarged view of the pattern portion 18 in FIG.
When the pattern is formed through the alkali development process, the surfactant 13 moves not only on the resist 11 but also on the pattern side wall and is arranged on the interface. It is considered that the surfactant 13 having a low molecular weight and high polarity has a high molecular energy, so that it easily moves through the resist 11 and is easily arranged on the interface. By arranging the surfactant 13 on the pattern interface, the polar portion (hydrophilic group) 14 of the surfactant 13 is directed to the inside of the resist 11 and interacts with the polarity of the polymer microstructure, thereby causing a microcrystalline structure of the polymer. Its own orientation occurs.

By the above process, the polymer exists uniformly at the pattern interface, and the line edge roughness can be reduced by optimizing the microstructure of the resist polymer. Thus, when a pattern with reduced line edge roughness is applied to various processing of the underlayer, a semiconductor device with a fine pattern can be manufactured with a high manufacturing yield.

The schematic sectional drawing which shows the pattern formation method at the time of using the resist of this invention in order of a process. The enlarged schematic diagram of the pattern for demonstrating the principle of this invention. The schematic sectional drawing which shows the pattern formation method by the conventional resist in order of a process. The figure which shows the factor of the phenomenon which this invention overcomes (pattern sectional drawing).

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 30: Underlayer 11, 31: Application | coating resist 11a, 31a: Non-exposed area | region of resist 11b, 31b: Exposed area | region of resist 12, 32: Microstructure of polymer 13: Surfactant 14: Hydrophilic group 15: Hydrophobic groups 16, 36: Arrows indicating energy irradiation portions in exposure 18, 38: Pattern portions

Claims (4)

Applying a resist material containing a surfactant to the surface of the underlayer and drying to form a resist layer;
Irradiating the resist layer with light, X-rays or electron beam to expose the resist layer;
Heat treating the exposed resist layer;
A method of manufacturing a semiconductor device, comprising at least a step of alkali-developing the heat-treated resist layer to form a pattern without unevenness at an end portion.   The method for manufacturing a semiconductor device according to claim 1, wherein the resist material is a chemically amplified resist material.   The method for manufacturing a semiconductor device according to claim 1, wherein the surfactant is a surfactant that is not decomposed by the exposure light. 4. The method of manufacturing a semiconductor device according to claim 1, wherein the surfactant is a surfactant that is not volatilized by the heat treatment.

Images