JPH024267A - Method for enhancing etching resistance of resist - Google Patents

Abstract

PURPOSE:To enhance etching resistance of a resist and to simplify process by using convergent ion beams and irradiating the resist with ions. CONSTITUTION:The resist 31 applied to a base plate 32 is exposed to the convergent ion beams 33 to cause chemical reaction for forming a latent image in addition to cross-linking reaction of the resist constituent molecules with a high energy of the ion beams, and the region except the pattern region is not irradiated and the base plate is neither damaged nor contaminated. Development is carried out in a developing solution, thus permitting the obtained pattern to be enhanced in etching resistance more than in the case of not using such convergent ion beams, both of the patterning process and the ion irradiation process for enhancing the etching resistance to be executed at the same time, accordingly, the processes to be simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for improving the etch resistance of a resist used as an etching mask in a semiconductor device manufacturing process.

(Conventional technology and its problems) In the semiconductor device manufacturing process, a method of irradiating resist with ions is generally known as a method of improving the etch resistance of resist, which is a mask material when etching a substrate. . This is because by irradiating the resist with ions, the high ion energy excites the easily excited parts of the main chain or side chain of the resist constituent molecules, causing a crosslinking reaction. This prevents the constituent molecules of the resist from being easily excited, cut, and scattered by chemical ions.

FIG. 1 is an example of a conventional technique. Novolac positive type photoresist 1 spin-coated on Si substrate 12
1 (FIG. 1(a)) is exposed to ultraviolet light 13 through a photomask 14 (FIG. 1(b)). Thereafter, development is performed in an alkaline developing solution to form a resist pattern that will become an etching mask (Figure 1 (C)).
. Next, H ions are applied to the entire surface of the substrate at I x 1013 ions.
By irradiating the resist at about /am2, the crosslinking reaction of the resist proceeds and the etch resistance improves (FIG. 1(d)).

However, in this conventional method, ions are irradiated onto the entire surface of the substrate, so ions are implanted into the substrate surface other than the resist.
This causes damage to the substrate and causes the implanted ions to become impurities, deteriorating device characteristics.

Furthermore, since the ion irradiation process is performed after the resist development process, there is also a drawback that the process is more complicated than a normal resist pattern forming process. (For example, Proceedings of the 47th Japan Society of Applied Physics Academic Conference P, 333.3OA-ZF-9
, Hashimoto et al.).

An object of the present invention is to provide a method for improving the etch resistance of a resist by ion irradiation, which does not cause damage or impurities to parts other than the resist pattern due to ion irradiation, and has a simplified process compared to conventional methods. Our goal is to provide the following.

(Means for Solving the Problem) According to the present invention, a method for improving resist etch resistance by ion irradiation is characterized by comprising an ion irradiation step 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 necessary ion species, and the objective lens 208 focuses the beam to a beam diameter of 0.1 pm or less. Furthermore, the ion beam is deflected by a deflector 209 so as to draw an arbitrary pattern on the substrate 210.

Further, FIG. 3 is a sectional view of the substrate for explaining the present invention in detail. That is, the resist 31 coated on the substrate 32
Exposure is performed using a focused ion beam 33 (FIG. 3(a)) (FIG. 3(b)). At this time, due to the exposure with the focused ion beam, in addition to the chemical reaction that is inherent in the resist for image formation, the high energy of the irradiated ions promotes cross-linking reactions in the resist constituent molecules, forming a latent image. . Therefore, ions are not irradiated to areas other than the pattern area, and the substrate is not damaged or impurities are introduced. By subsequently developing the resist in a developer, a pattern with improved etch resistance than the original resist is formed, and because the pattern drawing process and the ion irradiation process to improve etch resistance are performed simultaneously, it is better than the conventional method. The process is simplified.

(Example) Hereinafter, an example of the present invention will be described and explained using FIG. 4. First, as a resist on the substrate 42, 5AL601-ER7 manufactured by Sibley Co., Ltd. is used as a novolac negative type resist.
was spin-coated to a thickness of about 0.5 pm and baked for 80°030 minutes (Figure 4(a)). Next, the acceleration energy of 260 keV obtained from the Au-8i-Be alloy ion source
The resist is exposed using a Be focused ion beam (FIG. 4(b)). Normally, the appropriate exposure amount for patterning novolac negative resist is 3 x 1012i.
ons/cm2, but in this case, in order to advance the crosslinking reaction of the resist, the exposure amount is about 3 times I
013 ions/cm2. Thereafter, development was carried out for 5 minutes in an alkaline developer and rinsed for 1 minute with pure water, thereby forming a resist pattern with improved etch resistance as shown in FIG. 4(e). In this case, the Be ions used in the resist exposure step and the ion irradiation step are implanted only into the formed resist pattern portion, so that other substrate surfaces are not damaged or impurities are caused by ion irradiation. In addition, since the resist pattern exposure process using a Be focused ion beam and the ion irradiation process to improve etch resistance are performed simultaneously, the process simplification was achieved.

In this example, a Be focused ion beam obtained from an Au-8i-Be alloy ion source was used in the resist exposure process and the ion irradiation process to improve etch resistance.
i, Ga, Au, etc. elemental metal ion source, Au-8i.

A focused ion beam of ion species obtained from an alloy ion source such as Pt-8b, Pb-N1-B, or a gas ion source such as He, H2°02, F2, etc. may also be used. In addition, in this example, a novolak-based negative resist (Sibley, 5AL601-ER7) was used as the resist.
Other resists such as a novolac resist such as a novolac positive resist, a methacrylate resist such as polymethyl methacrylate, or a polystyrene resist such as chloromethylated polystyrene may be used. Further, in this example, the acceleration energy was 260 keV and the exposure amount was 1 x 1011013 ions1, but these may vary as long as they cause image formation and crosslinking reactions in the resist used and do not reduce the resist film due to ion bombardment. It may also be the acceleration energy and exposure amount of the magnitude.

(Effects of the Invention) As described above, according to the present invention, in a method for improving resist etch resistance by ion irradiation, a method for improving resist etch resistance characterized by comprising an ion irradiation step using a focused ion beam, Compared to the method described above, the etch resistance of the resist can be improved without causing damage or impurities to the substrate surface other than the resist pattern due to ion irradiation, and the process can be simplified.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view of a substrate for explaining the prior art;
FIG. 2 is a schematic diagram of a focused ion beam device for explaining the present invention in detail, FIG. 3 is a partial sectional view of a substrate for explaining the present invention in detail, and FIG. 4 is an embodiment of the present invention. FIG. In the figure, 11... Novolac positive photoresist, 12... Si substrate, 13... Ultraviolet light, 14
...Photomask, 15...H ion, 16...
damage, 201... ion source, 202... focusing lens, 203.207... alignment deflector, 204...
... EXB mass separator, 205 ... ion species selection aperture, 206 ... astigmatism corrector, 208 ... objective lens,
209... Deflector, 210... Substrate, 211...
sample stage, 31... resist, 32... substrate,
33...Focused ion beam, 41...Novolac negative resist, 42...Substrate, 43...Be focused dion beam.

Claims (1)

[Claims] A method for improving resist etch resistance by ion irradiation, the method comprising performing ion irradiation on the resist using a focused ion beam.