JPH02143253A - Precise pattern forming method - Google Patents

Abstract

PURPOSE:To exactly reproduce mask patterns by providing a thin layer of a specific org. compd. on an org. resist layer. CONSTITUTION:The org. resist 3 is applied on a film 2 to be etched and the thin layer 4 of the org. compd. elected from a group consisting of an org. metal compd. and org. metal complex is formed and thereafter, a mask 5 is applied thereon and the resist is exposed or after the mask is applied thereon, the resist is exposed and thereafter, the thin layer 4 of the org. compd. is formed. Developing and etching are then executed. The timing for the formation of the org. compd. layer and the exposing necessitates the earlier execution of the exposing if the org. compd. layer is colored or UV absorptivity is high. The mask patterns are exactly reproduced in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method of forming fine patterns for electronic components and the like using an organic resist.

[Prior art]

In conventional photolithography technology, Fresnel diffraction in the optical system (when the wavelength λ of the incident light and the distance from the mask surface to the sample surface is g, the amount of pattern blur from the edge of the mask ds)
is approximately expressed as ds=v'2λg).

A stepped pattern occurs.

Additionally, a light interference effect (standing wave effect) occurs between the resist film thickness and the sample surface (especially when the reflectance is high such as A and Q), and diffused light enters the mask pattern, causing damage to the mask pattern. It makes the accuracy worse.

The pattern accuracy becomes thicker in the case of a negative resist and thinner in the case of a positive resist. Furthermore, if the resist film thickness is uneven, the reflectance of the sample surface is partially different, or there is uneven exposure, the standing wave effect will partially change, causing sensitivity unevenness in the resist thickness direction. , wrinkles appear on the resist after development, and the edges of the pattern become jagged.
Resist bridges occur between patterns, resulting in pattern defects.

Even if the above-mentioned phenomenon occurs when the pattern accuracy is about 5 to 10 .mu.m, it is possible to process these defects by suppressing the error to .±.2 .mu.m or less by optimizing the conditions. However, when the processing accuracy is set to ±0.2 to 1 μm or less for a pattern of 5 μm or less, it has been impossible to expect the reproducibility of the mask pattern using the conventional methods.

〔the purpose〕

The object of the invention is to overcome the drawbacks of the prior art.

The present invention relates to a precision pattern forming method for accurately reproducing mask pattern hair.

〔composition〕

The present invention has discovered that the above objects can be achieved at once by providing an atom of a specific organic compound on the organic resist layer. In other words, one aspect of the present invention is to (1) apply an organic resist on a film to be etched, (2) form a thin layer of an organic compound selected from the group consisting of (a) organometallic compounds and organometallic complexes, and then apply a mask. or (b) forming a thin layer of the organic compound after exposure by applying a mask.

(3) The present invention relates to a method for forming a precision pattern, which is characterized in that development and etching are then performed.

Specific examples of the organometallic compound include the general formula % formula %) (wherein R is alkyl, aryl, alkylaryl,
M is Si, Ti, Zn.

Ba, B, W, Mo, Cr, Sn, Ni.

Element selected from the group consisting of Pb, AQ, Ta, In, Ce, Mgl Fe, n is 1 to 4, preferably 1
~3. ) or alcoholal silicate or 2M■Et2゜M■E
t, , M(:DB ut, , M■BLIt+
BuM■(OB u)z.

M■Et4. M■Ph, etc. can be mentioned.

Here, M■=Mg, Zn, MO=B, AQ+In
.

Fe, Ta, Ce, Sn, Ni, M = Si, Ti,
Et=C,H,, BuL=(isobutane) C4Hs
.

OR=alkoxy group, such as for example butoxy group (one type forming an alcoholade), Bu=butane C,H.

The organometallic complex has an organic chelating agent and a functional group of M
g, Zn, Ba, Ti, Si, AQ.

Ta, In, Ce, Fe, Ti, B, W, Mo, Cr.

It is a complex of Sn, Nil, Pb, etc., and is used by dissolving it in an organic solvent. Organic chelating agents include EDTA (ethylenediaminetetraacetic acid), propylmalonic acid, phthalic acid, N,N-dimethylethylenediamine, propylenediamine, phenanthroline, glycylglycinemethionine, phonylalanine, aniline diacetic acid, salicylaldehyde, and 0-aminophenol. etc. can be given.

This organic compound is usually applied on the organic resist layer with a concentration of 200 to 1
Formed in a thin layer of 000 people.

Regarding the timing of forming the organic compound layer and exposing it to light, if the organic compound layer is colored or has a high ultraviolet absorption rate, it is necessary to perform the exposure first.

Any organic resist can be used as long as the polymer chain is decomposed by exposure to ultraviolet rays and becomes soluble in a solution. , "New Photosensitive Resin" by Takahiro Tsunoda, No. 78
Those described on pages 1 to 105 can be used.

As the organic resist, a novolac resin orthoquinone diazo compound is usually used. This compound system has a main chain consisting of a condensation compound with phenol or cresol.

The diazo group in the exposed portion absorbs this ultraviolet light, decomposes, and leaves as nitrogen gas as shown in the formula below. The decomposed area undergoes hydrolysis to form carboxylic acid groups,
Soluble in alkaline solution. That is, the exposed portion becomes alkali-soluble and elutes, but the unexposed portion remains the naphthoquinone diazo compound and is therefore insoluble in alkali and remains on the surface.

The organic resist usually has a thickness of about 0.5 to 5 μm, especially about 0.8 to 5 μm.
A thin layer of about 1.2 μm is preferable.

Since the alkaline developer has a thin organic compound layer,
It passes through this layer to dissolve and develop the exposed portions of the organic resist layer. It is desirable to consider the exposure conditions so that this development is limited to the surface layer of the organic resist as much as possible.

Next, etching will be explained.

Preferably, wet etching is performed as the first step and dry etching is performed as the second step.

Wet etching involves etching and developing the upper organometallic compound or complex and a part of the photosensitive portion of the organic resist layer, and in the second step, the remaining organic resist layer and the film to be etched are etched.

A known etching solution can be used as the etching solution for the organic resist in the first stage.

The second stage of etching is performed by performing anisotropic etching (dry etching) using oxygen by RIE (reactive ion etching) or ECR (etching using electron microtron resonance), so that the resist pattern is perpendicular to the film to be etched. It can be patterned into

This is because the oxygen ions generated during dry etching (RrE, ECR) directly react with the organosilicon compound, and the organosilicon compound is decomposed on the spot and S is deposited on its surface.
In, is formed and etching does not proceed, but in the areas where there is no organosilicon compound due to wet development, the organic resist quickly becomes an oxide (H2O, CO2) and is etched, and due to ionic etching, the etching becomes anisotropic. The pattern is etched vertically.

The film to be etched includes A(1, a metal film such as Cu,
Any film can be targeted, such as semi-dedicated films such as PoQysi and a-3i, but it is especially suitable for electronic equipment, O
It targets films to be etched that are applied to various devices used in A equipment.

Next, etching of the film to be etched will be explained.

As an etching agent, if the film to be etched is a metal film such as 80 or Cr, a mixed gas of CCQ4 and 0□ can be used as the etching gas, and Po12y
In the case of Si or a-3i, a mixed gas of CF4 and 02 can be used. Of course, any known etching material can be used.

〔Example〕

Example 1 Will! on a glass substrate A resist film (positive) with a thickness of 0.8 μm is further formed on top of the resist film 2. (Figure 1A) As shown in Figure 1B, a film of an organosilicon compound is formed on the resist film to a thickness of about 300 mm using any method such as spinner method, sputtering method, vacuum evaporation method, etc. Pre-cure.

As shown in FIG. 1C, two masks are applied and exposed to ultraviolet rays.The exposure is less than )OOmj/aJ, and only the surface of the positive resist is decomposed as much as possible.

Since the organosilicon compound layer is extremely thin, only the portion where the resist is dissolved is removed. This is to minimize the occurrence of Fresnel interference and standing wave effects, and to minimize resist decomposition in the depth direction of the resist film thickness.

This is developed by wet development, and only the very surface of the exposed and decomposed portion is patterned as shown in the first diagram. The dimensional accuracy of this pattern was good.

Next, as shown in FIG. 1E, the resist pattern is etched by anisotropic etching using 02 (oxygen) by RIE (reactive ion etching) or ECR (electron cyclotron resonance etching). Pattern vertically up to. Next, AQm up to the film to be etched is etched with a mixed gas of cc p 4 and 02 to obtain the image shown in FIG. 1F. Finally, the surface (7) 5
The in2 layer and the organic resist layer were removed to obtain the object shown in FIG. 1G.

Example 2 A photomask was applied to the laminate (FIG. 2A) consisting of the substrate, film to be etched, and organic resist (positive type) used in Example 1 and exposed (FIG. 2B), with an exposure dose of 100 mj/
Co? Control so that it is as follows.

Next, an organosilicon compound was applied to this surface. This organosilicon compound has a higher ultraviolet absorption rate than the organosilicon compound of Example 1. Next, Example 1
A pattern-formed body shown in the first diagram is obtained by developing in the same manner as above. Through this development treatment, only the organosilicon compound layer present on the top of the resist that dissolves in the alkaline developer is peeled off.

The subsequent steps are the same as in the first embodiment.

Example 3 What happens when exposure unevenness occurs when a large area surface of a laminate (see FIG. 3A) consisting of a substrate, a film to be etched, an organic resist, and an organic silicon compound (see FIG. 3A) similar to that in Example 1 is exposed to ultraviolet light. An example is illustrated. The amount of exposure is overexposure. Therefore, there is a portion 7 where standing wave effects and Fresnel diffraction effects occur (see FIG. 3B).

However, as a result of suppressing the wet development process to 15 seconds or less, it was possible to reproduce a sufficiently precise pattern without developing a latent abnormal pattern even when standing wave effects and Fresnel diffraction effects occurred.

On the glass substrate of Comparative Example 37740, a film of about 1 μm of a-5i is formed (FIG. 4A), and then an organic positive resist (trade name: 0FPR-800-50c, p) is coated with a thickness of 1 μm using a spinner method. (Figure 4B). 80℃
After curing for 30 molecules at room temperature, exposure is performed by applying a mask, the exposure conditions are 18+llW/cA,
'AO seconds/405 nm. For development, use the product name NMD-
3 for 30 seconds (Figure 4C).

When the edge of the pattern is observed under a microscope, as seen in the fourth diagram, the pattern width has increased due to the Fresnel diffraction effect (8).

Furthermore, if there is a metal layer with a high reflectance, such as Afll, on the substrate, the resist layer will become thinner (9) in the film thickness direction due to the standing wave effect, as shown in FIG.

If etching is performed in this state, the width will be larger than the mask pattern in the case of FIG. 4, and the width will be narrower than the mask pattern in the case of FIG. 5.

〔effect〕

■ A pattern of 5μ or less can be patterned with an accuracy of 0.5 to 1μ or less.

■ Fresnel diffraction effects are ignored even when the coherency is high in single-spectrum exposure such as I-line (365 nm) or H-line (405 nm).9 ■ After dry etching the resist pattern, change the gas type to Since patterning and resist ashing can be carried out in its entirety, it is possible to improve efficiency and shorten the process.

(2) This method is extremely useful in pattern processing of ICs, LSIs, thermal sensors, etc.

[Brief explanation of the drawing]

Figures 1 to 3 are for explaining the method of the present invention according to Examples 1 to 3 of the present invention in the order of steps, and Figure 4 is for explaining the conventional method. This is for explaining the Fresnel diffraction effect, and FIG. 5 is for explaining the standing wave effect. 1...Substrate 2...Film to be etched 3...Organic resist layer 4...Organic metal shop 5...Mask pattern 6...Exposed portion 7...Overexposed due to standing wave effect Megumi Kutabe 4 to 8...“1 thick part where Fresnel diffraction effect occurs”

Claims (1)

[Claims] 1. (1) After applying an organic resist on the film to be etched, and (2) (a) forming a thin layer of an organic compound selected from the group consisting of organometallic compounds and organometallic complexes. , applying a mask and exposing to light, or (b) applying a mask and exposing to light, forming a thin layer of the organic compound, (3) then developing and etching. Method.