JP3022418B2 - Resist material and resist pattern forming method using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resist material used in a fine processing step of a semiconductor device and the like, a resist pattern forming method using the same, and a fine processing method.

[0002]

2. Description of the Related Art Conventionally, in the production of semiconductor integrated circuits,
To perform microfabrication, apply a resist material to the substrate, selectively irradiate it with high-energy rays or ultraviolet rays to form a latent image, obtain the desired pattern by development, and process this as a resist. It was customary to do so. As the resist material, a polymer or a composition obtained by adding a reactive material to the polymer has been widely used.
For example, as a negative resist for electron beams, SAL
(Chemically amplified resist, Shipley) and polymers of CMS (chloromethylstyrene) are known.

[0003]

However, in the fine processing in the submicron region required in the manufacture of semiconductor devices, etc., it is difficult to sufficiently meet the demand by the conventional processing technology using a polymer resist material. there were. For example, as a negative resist for the above-mentioned electron beam, SAL or CMS has several micro C / cm ² for electron beam sensitivity.
Although the sensitivity is as high as about 10 nm, it was difficult to form an ultrafine pattern of about 10 nm.

Accordingly, there has been a strong demand for a resist material which can be easily processed and can be processed on the order of submicrons, similarly to the conventionally used polymer resist.

[0005]

In order to solve the above problems, the present inventors have found that it is extremely effective to use a resist material containing an α-methylstyrene oligomer. That is, the weight average molecular weight is 300 or more and 2000 or less.
A negative resist material for high energy radiation is provided, which comprises the following α-methylstyrene oligomer as a binder component.

[0006] According to the present invention, after a negative resist material is applied on the substrate to be processed, forming a negative les <br/> resist film is pre-baked, high energy the negative resist film negatives and forming a latent image of a desired pattern selectively exposing to the line, and a step of developing the latent image
In the method of forming a resist pattern, the negative resist material may have an α having a weight average molecular weight of 300 or more and 2000 or less.
-A method for forming a negative resist pattern, comprising a methylstyrene oligomer as a binder component.

Further, according to the present invention, a negative electrode is formed on a substrate to be processed.
Type resist material is applied, selectively forming a negative resist film, the negative resist film to a high energy radiation
Forming a latent image of a desired pattern by exposing
Forming a microstructure by dry etching after developing the latent image ,
The negative resist material has a weight average molecular weight of 300 or more and 200
There is provided a microfabrication method characterized by containing an α-methylstyrene oligomer of 0 or less as a binder component.

One of the reasons that the conventional resist material has a certain limit in the fine workability is that the size of the polymer used for forming the pattern itself is the resolution, more specifically, the roughness when forming the pattern. Is to cause problems. This problem is pointed out by Yoshimura et al. In Applied Physics Letters 63, p734 (1993). On the other hand, since the resist material of the present invention uses an oligomer, there is no such a problem, and excellent fine workability can be realized.

Various conditions must be satisfied in order to put an organic material into practical use as a resist. Specifically, solubility in a solvent, film forming ability, amorphous or very hardly crystallizable properties, heat resistance, sensitivity, etching resistance, etc.
The resist material containing the α-methylstyrene oligomer according to the present invention satisfies these conditions and
It is possible to form an ultrafine pattern of about m.
In addition, when comparing the sensitivity of the resist containing the α-methylstyrene oligomer with other organic resists, it is slightly inferior when trying to expose a large area, but when forming an ultrafine pattern for the purpose of the present invention, Equivalent or higher. For example, in electron beam writing, the exposure sensitivity of SAL when attempting to expose a large area is 30 μC / cm ² . This value is 500 times more sensitive than 15 mC / cm ² of α-methylstyrene. However, this SAL
When a dot having a diameter of about nm is formed by one-point irradiation using a resist, the sensitivity is required to be 30 fC / dot per dot (point irradiation). Similarly, for α-methylstyrene, about 100 fC / dot per dot
There is no significant difference between the value degree and the SAL point irradiation sensitivity. Conversely, S
In the case of a high-sensitivity resist such as AL, the minimum diameter of a dot pattern that can be formed is a limit, whereas in the case of an α-methylstyrene oligomer, minute dots having a diameter of about 10 nm can be easily formed.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The resist composition of the present invention contains an α-methylstyrene oligomer as a binder component. Its molecular weight is preferably 300 or more and 20000 or less, and more preferably 500 or more and 2000 or less.
By setting the content in such a range, a resist material having excellent fine workability and good workability is provided.

The resist material of the present invention may contain, in addition to the α-methylstyrene oligomer, other resins usually used as a resist material. In this case, the content of the α-methylstyrene oligomer is appropriately adjusted depending on the type of other resin, pattern forming conditions, fine processing conditions, and the like. Sex is achieved.

In addition to the α-methylstyrene oligomer, phenolic resin, calixarene, chloromethylstyrene and the like can be appropriately added to the resist composition of the present invention.

The α-methylstyrene oligomer is diluted with a solvent and applied by spin coating or the like. As the solvent, for example, xylene, monochlorobenzene, toluene or the like is used.

The concentration of the α-methylstyrene oligomer is not particularly limited, but is usually adjusted appropriately in the range of 1% to 20%. Further, the film thickness when the solvent is dried after coating is preferably 20 nm or more and 1000 nm or less, more preferably 30 nm or more and 100 nm or less.

The high energy beam in the method of forming a resist pattern according to the present invention is used to draw a pattern by irradiating a resist material, and an electron beam, X-ray, ion beam or the like can be used.

[0016]

The present invention will be described in more detail with reference to the following examples. First, α-methylstyrene oligomer was synthesized from α-methylstyrene as a raw material by anionic polymerization. After replacing a 100 ml eggplant-shaped two-necked flask equipped with a condenser and a three-way cock with nitrogen, sodium (0.43
g, 18.7 mmol), naphthalate (2.47 g,
19.3 mmol) and THF (25 ml) were added and reacted at room temperature for 3 hours to prepare a catalyst. The reaction solution was brought to 62 ° C., and α-methylstyrene (1.9 g, 1
6.1 mmol) and stirred for 30 minutes. Reaction solution is 0
After cooling at −78 ° C. for 5 minutes and at −78 ° C. for 30 minutes, α-methylstyrene (1.61 g, 13.6 mm
ol) was added. After reacting at −78 ° C. for 12 hours,
The reaction was quenched by the dropwise addition of methanol. After distilling off the solvent under reduced pressure, n-hexane was added and redissolved. Sodium methoxide precipitated at this time was removed by filtration. After distilling off the solvent, the polymer was dissolved in THF (10 ml). ). The precipitate was collected by filtration and dried under reduced pressure at 40 ° C. to obtain 1.2 g of a polymer. As a result of molecular weight measurement by GPC measurement, the thus obtained α-methylstyrene oligomer had a weight average molecular weight Mw of 652 and a number average molecular weight M
n is a low molecular weight of 598, and the dispersion Mw / Mn is 1.09.
Met.

The α-methylstyrene oligomer synthesized as described above was dissolved in chlorobenzene at 1.5% by weight and filtered through a 0.2 μm filter to prepare a resist solution. Using a coater on a clean silicon substrate, 4
Spin coating was performed at 000 rpm to obtain a uniform coating film having a thickness of 35 nm. Using an electron beam exposure apparatus (Hitachi S5000), pattern drawing was performed at various exposure doses using an electron beam of 25 kV. The substrate was immersed in xylene for 30 seconds for development and dried to obtain a resist pattern. The film thickness of this pattern was measured and the sensitivity was determined as a function of the exposure (FIG. 2). As is apparent from the figure, the surface sensitivity of the α-methylstyrene oligomer is 15 mC / 25 kV electron beam.
cm ² . Using this α-methylstyrene oligomer, a dot array having a diameter of 15 nm as shown in FIG. 3 and a line pattern having a line width of 12 nm as shown in FIG. 4 can be easily obtained.

X as a high energy beam for resist exposure
Lines, ion beams and the like can also be used. For example, even when SR (synchrotron radiation) light having a wavelength of 1 nm was used, a fine pattern similar to the case of an electron beam could be obtained. A 100 KeV FIB (Focused IonBe) using Ga ¹⁺ ions as an ion beam.
am) Even when the apparatus was used, a fine pattern of α-methylstyrene oligomer could be obtained.

The thus obtained negative pattern of the α-methylstyrene oligomer has a sufficient etching resistance to dry etching, and the Si or GaAs
s, and also has a sufficient etching resistance to aluminum or Ge metal. For example, when CF ₄ plasma is used, α-methylstyrene oligo to Ge
Is the etching selectivity γGe of the polymer (γ = the etching amount of Ge / the etching amount of α-methylstyrene oligomer)
About 4 was obtained, and γSi = 1 was obtained for Si. Actually, using an α-methylstyrene oligomer, G
An extremely fine line having a line width of about 7 nm could be formed as the quantum thin line of e.

[0020]

According to the present invention, an electron beam negative resist having a high resolution on the order of nm can be obtained, and fine processing in a submicron region becomes possible. This enables application to next-generation ultra-high integration Si-LSI and various sensors.

[Brief description of the drawings]

FIG. 1 is a view showing a chemical structural formula of an α-methylstyrene oligomer.

FIG. 2 is a diagram showing electron beam exposure sensitivity of α-methylstyrene oligomer.

FIG. 3 is a drawing-substitute photograph showing an example of a dot pattern obtained by using an α-methylstyrene oligomer.

FIG. 4 is a photograph as a drawing substitute showing an example of a line pattern obtained by using an α-methylstyrene oligomer.

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Shoko Mako 5-7-1 Shiba, Minato-ku, Tokyo Within NEC Corporation (56) References JP-A-3-200968 (JP, A) JP-A Sho53 JP-A-92-57444 (JP, A) JP-A-54-41719 (JP, A) JP-A-63-137227 (JP, A) JP-A-58-122531 (JP, A) JP-A-1-163738 (JP, A) JP-A-62-191850 (JP, A) JP-A-60-257445 (JP, A) JP-A-4-281455 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) G03F 7/038 C09D 4/00 C09D 125/16 H01L 21/027

Claims (17)

(57) [Claims] 1. A weight average molecular weight of 300 or more and 2000 or less.
A negative resist material for high energy rays , characterized by containing the α-methylstyrene oligomer of (1) as a binder component. 2. The weight average molecular weight is 500 or more and 200 or more.
2. High energy according to claim 1, wherein the energy is 0 or less.
Negative resist material for gauze wires. 3. The high energy beam is an electron beam.
The negative resist material according to claim 1, wherein:
Fees. 4. The method according to claim 1, wherein the high energy ray is an X-ray.
The negative resist material according to claim 1 or 2, 5. The high energy beam is an ion beam.
The negative resist according to claim 1 or 2, wherein
Material. 6. After the negative resist material is applied on the substrate to be processed, forming a negative resist film is pre-baked, desired the negative resist film selectively exposed to the high energy beam forming a latent image of the pattern, the negative resist pattern forming method comprising the step of developing the latent image, the negative resist material is the weight average
Ne to a molecular weight of 300 to 2,000 of α- methyl styrene oligomer comprising as a binder component
A method of forming a resist pattern. 7. The weight average molecular weight is 500 or more and 200 or more.
7. The negative type laser according to claim 6, wherein the value is 0 or less.
Gist pattern forming method. 8. The film thickness of the negative resist film is 20 nm.
7. The semiconductor device according to claim 6, wherein
Is a method for forming a negative resist pattern according to item 7. 9. The negative resist pattern forming method according to claim 6, wherein said high energy beam is an electron beam. 10. The negative resist pattern forming method according to claim 6, wherein said high energy rays are X-rays. Wherein said high energy beam according to any one of claims 6 to 8, characterized in that an ion beam
Negative resist pattern forming method. 12. A coated negative resist composition on a substrate to be processed, forming a negative resist film, the negative
The resist film is selectively exposed to high energy rays to
Forming a latent image of the pattern, and developing the latent image
After, the fine processing method comprising the steps of forming a fine structure by dry etching, finely the negative resist material is characterized in that it comprises a weight-average molecular weight of 300 to 2,000 of α- methyl styrene oligomer as a binder component Processing method. 13. The weight average molecular weight is 500 or more and 20 or more.
13. The fine particle according to claim 12, wherein the particle diameter is not more than 00.
Processing method. 14. The film thickness of the negative resist film is 20 n.
2. The structure according to claim 1, wherein the thickness is not less than m and not more than 100 nm.
14. The microfabrication method according to 2 or 13. 15. The high energy beam is an electron beam.
15. The fine structure according to claim 12, wherein
Fine processing method. 16. The high energy ray is an X-ray
The fine particle according to any one of claims 12 to 14, wherein
Processing method. 17. The high energy beam is an ion beam.
The method according to any one of claims 12 to 14, wherein
Micro-processing method.