JPH022604A - Fine-pattern forming method - Google Patents

Abstract

PURPOSE:To enable forming a finer and denser resist pattern than before by applying a novolak resist on a substrate and then exposing the resist with a condensed ion beam. CONSTITUTION:When a fine resist pattern is formed, a novolak resist 11 is applied on a substrate 12 and then the resist 11 is exposed to a condensed ion beam 13. For example, the novolak negative resist 11 is spin-coated by the thickness of 0.5mum as a resist on the substrate 12, and baked at 80 deg.C for 30min. Next, the resist 11 is exposed using a Be condensed ion beam 13 of the acceleration energy 260keV, obtained from an Au-Si-Be alloy ion source. At this time, the exposed quantity of the resist 11 is in a degree of 3X10<12>ions/ cm<2>. After that, a resist pattern is formed by developing it in an alkaline aqueous solution developer for 5min and rinsing it with pure water for one minute.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for forming fine patterns on a substrate in a semiconductor device manufacturing process.

(Prior art and its problems) When compared with resist exposure using an electron beam, which is currently commonly used as a means for forming fine patterns, resist exposure using a focused ion beam is less prone to proximity effects due to forward and backward scattering. Under the influence<<, the sensitivity is 1~
Since it is about 2 high, it is not easily affected by charge-ups. As described above, a focused ion beam has better fine processing properties than an electron beam, and currently, a fine resist pattern with a line width of about 0.1 μm is formed by focused ion beam exposure.

However, resists conventionally used for microfabrication by focused ion beam exposure or electron beam exposure are methacrylate-based resists such as polymethyl methacrylate (PMMA), or chloromethylated polystyrene (CMS). Most of the resists, such as styrene-based resists, use organic solvents in the developer. Resists that use such organic solvent phenomena are
It is known that the resist pattern swells during development due to impregnation with an organic solvent, and therefore, for example, when the line width is 0.1
It was not possible to form a fine and high-density resist pattern of μm/line spacing of 0.1 μm.

Novolac resist uses an alkaline aqueous solution as a developer and is known as a resist that does not cause the pattern to swell during development.However, as mentioned above, the pattern exposure using the conventional electron beam causes the proximity effect, Due to the influence of charge amplifiers, etc., it was not possible to form fine and high-density resist patterns (for example, semiconductor lithography technology: written by Hiro Otori, Sangyo Tosho P, 15-)
.

The purpose of the present invention is to form fine resist patterns.
An object of the present invention is to provide a method for forming a resist pattern that is finer and denser than conventional methods.

(Means for solving the problem) According to the present invention, in forming a fine resist pattern,
This is obtained by a method for forming a fine pattern, which comprises a step of applying a novolak resist to a substrate, and a step of subsequently exposing the resist to light using a focused ion beam.

(Function) FIG. 2 shows the configuration of the focused ion beam device used in the present invention. The ions emitted from the ion source 201 are E
The xB mass separator 204 selects essential ion species, and the objective lens 208 focuses the beam to a beam diameter of 0.1 μm or less.

Furthermore, the ion beam is deflected by a deflector 209 so as to draw an arbitrary pattern on the substrate 210.

As mentioned earlier, focused ion beam exposure is less susceptible to effects such as proximity effect and charge-up compared to electron beam exposure, so the beam diameter is approximately equal to 0.05 to 0.1.
A fine resist pattern with a line width on the order of μm can be formed with high accuracy and reproducibility. In addition, since novolac resists use an alkaline aqueous solution as the developer, there is almost no swelling of the resist due to impregnation with the developer during development, which allows high-density resist patterns with very fine spaces between patterns to be produced with high accuracy and reproducibility. Can be formed well. Therefore, by using a novolac resist and performing exposure with a focused ion beam, it is possible to form a fine and high-density resist pattern that could not be obtained by conventional methods.

(Example) Hereinafter, an example of the present invention will be described using FIG. 1. First, a novola, phosphor-based negative type resist is spin coated on the substrate 12 to a thickness of about 0.5 μm, and heated to 80°C.
Bake for 30 minutes (Figure 1(a)). Then Au-5
Acceleration energy obtained from l-Be alloy ion source2
The resist is exposed using a 60 keV Be focused ion beam (FIG. 1(b)). At this time, the exposure amount of the resist was approximately 3 x xo12ions/cm2. Thereafter, development was carried out for 5 minutes in an aqueous alkaline developer and rinsed for 1 minute with pure water, thereby forming a lensed pattern as shown in FIG. 1(C). in this case.

The line width of the lensed pattern is approximately 0.1 μm, and the distance between each line is <0.1 μm, making it possible to create fine and high-density resist patterns that cannot be obtained with conventional methods without being affected by swelling or proximity effects. was able to form.

As another example, Si with an acceleration energy of 260 keV
Exposure was performed using a focused ion beam. Other conditions were the same as in the case of Be. Line width 0.1 μm Line spacing 0.1
A micrometer-sized pattern was formed.

In this example, a Be focused ion beam obtained from an Au-5l-Be alloy ion source was used in the resist exposure process, but other single metal ion sources such as Li, GalAu, etc.
A focused ion beam of ion species obtained from an alloy ion source such as 11Pt-5b or Pb-N1-B or a gas ion source such as ■e, H2, o□, or F2 may be used.

Further, in this embodiment, a novolac negative type resist (Sibley, Inc., 5AL601-ER7) was used as the resist, but other novolac type resists such as a novolac positive type resist and other novolac type resists that are developed with alkaline aqueous solution may be used. Furthermore, in this example, the acceleration energy is 260 keV,
The exposure amount was 3 x 10I2tons/Cm2,
The acceleration energy and exposure amount may be set to any desired magnitude as long as the resist used undergoes an image-forming reaction and the resist film is not reduced due to ion bombardment.

(Effects of the Invention) As explained above, according to the present invention, in forming a fine resist pattern, the fine pattern is characterized by comprising a step of applying a novolac resist to a substrate and a step of exposing with a focused ion beam. Depending on the formation method,
We were able to form a fine and dense Rennost pattern that could not be obtained using conventional methods.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view of a substrate for explaining one embodiment of the present invention, and FIG. 2 is a schematic diagram of a focused ion beam apparatus for explaining the present invention in detail. In the figure, 11...Novolac negative resist, 1
2...Substrate, 13...Be concentrated east ion beam, 20
1... Ion source, 202... Focusing lens, 203.
207... Alignment deflector, 204... EXB
Mass fraction M device, 205...Ion species selection aperture, 206.
... Astigmatism corrector, 208 ... Objective lens, 209 ...
- Deflector, 210...Substrate, 211...Sample stage.

Claims (1)

[Claims] (1) A method for forming a fine resist pattern, which comprises the steps of applying a novolac resist on a substrate, and then exposing the resist to a focused ion beam.