JPS5877230A - Pattern formation - Google Patents

Abstract

PURPOSE:To obtain a very fine pattern with high accuracy by a method wherein hydrogen ion beams are selectively implanted in the required parts of a positive- type photoresist film including a diazocompound as sensitive groups and then ultraviolet rays are aimed at the whole face including the required parts of the positive-type photoresist film and next, only the parts irradiated by the ultraviolet rays are developed and eliminated. CONSTITUTION:A positive-type photoresist film 2 including a diazo compound as sensitive groups is applied on an Si wafer 1 with a thickness of about 1mum and prebaking is done at 90 deg.C for about 20min. Next, after irradiating H<+> ions 3 at the required parts 4 of the film 2, the whole face including the required parts is exposed by using ultraviolet rays 5. In this way, sensitive groups at the parts 4 irradiated by the H<+> irons are destructed and the film 2 is changed to the state not exposed by the ultraviolet rays and only the places except the parts 4 are maintained under the condition permitting exposure and development by the ultraviolet rays. After that, the places except the parts 4 are developed and removed and a desired pattern by the parts 4 is left on a substrate 1.

Description

[Detailed description of the invention] The invention relates to a pattern forming method vc.

By using ion beam irradiation and ultraviolet 111 irradiation in combination, extremely fine patterns can be produced. It can be formed in # degrees. This invention relates to a pattern forming method.

As is well known, the fine turns of various semiconductor devices are usually formed by a technique called photolithography.

This technique uses ultraviolet rays, #L
After irradiating with a sub-ray or X4ii11, develop it,
By performing etching using the obtained resist pattern as a mask, the back area A is formed.

The accuracy of the obtained resist pattern is significantly reduced because it is scattered in the resist film or reflected from the substrate or film to be processed.

Conventionally, in order to form a resist pattern, it was necessary to reduce the thickness of the resist film to reduce the effects of scattering and reflection.

However, if the film thickness of the resist pattern is thin, it becomes difficult to perform etching using the resist pattern as a mask.Especially when performing dry etching, it is extremely difficult to use a resist that has sufficient resistance to dry etching. Therefore, if the thickness of the resist film is made thin, processing by dry etching becomes impossible.

ultraviolet! −? When a resist film is irradiated with an ion beam (instead of an electron beam), the scattering and reflection described above are much less than when using ultraviolet rays or a single beam. It is not necessary to widen the area, and it is extremely advantageous for forming fine patterns.

For example, when a PMMA (polymethyl methacrylate) film with a thickness of 125 μm is irradiated with an ion beam, the width becomes 0.57 μm.
Nine reports have shown that micrometer patterns were formed (R, L,
Seliger, Ike, Journal of Vacuum Science and Technology Vol. 6, p. 1610, l5HIO
), it is possible to expose thick resist films with high aspect ratios.

4 like this! The i length is extremely important for forming semiconductor devices with high integration density, but in order to advance the lithography technology using ion beams, the characteristics of the resist are extremely important.

However, in order to form an 11-it thin pattern, it is necessary to use dry etching, which allows A-oriented etching, without using an etching liquid, instead of wet etching using an etching liquid.

A nosist material with sufficient resistance to dry etching has not been found, resulting in less scattering and reflection, and 4ILI
The advantage of ion beams, which are suitable for forming a-hatterns, has not yet been fully utilized.

For example, a method for dry etching an Irui nicum film using upper grade CPMMA as a resist film. BCj.

was used as the reaction gas, the pressure was 0.2) -l, the output was 60
When performing etch blowfish under standard conditions of 0W. PM
The MA changes in quality and the shape of the resist pattern is distorted.In particular, in the case of the thank you note butter formed on the resist film, the pattern is completely crushed. It was confirmed that 11 was not used at all.

4: The purpose of the invention is to solve the above conventional problem 1t4, irradiate the ion beam tV cyst flag, and #. Thin I (ter/woto).

It is possible to provide a pattern forming method that can be formed with high degree of accuracy using a light-etched blowfish.

To achieve the queen's objective, the present invention uses a combination of selective irradiation with an ion beam and full-surface irradiation with ultraviolet rays to transform a positive resist into a negative resist with apparently high dry etching resistance. ! It is used to form a pattern.

Hereinafter, this invention will be explained in detail using examples.

AZ1350J (DA & NAME, manufactured by Shipley) with positive resist
A cyst film was formed by coating Ueno 1 to a thickness of 1 μm.

9 (1'. 1 row of 10 minute bake, 180Ke
V&CM accelerated hydrogen iot, 3. 2 x 10'
After irradiating the entire surface with V C/cm" and then irradiating the entire surface with V C. ultraviolet light, it was developed with a 1-alkaline developer to form a negative V cyst pattern. The Z1350J has an excellent resolution of 0.1 μm or less. By narrowing the ion flow,
It is also possible to form a turn 1 (with a width of 0.1 μm or less), and by using the above processing conditions, a fine JIL/distortion (turn 1) with a line space of C1 width of 0.5 μm can be formed.

Formed with high precision.

In this way, Vζ. If a variety of so-called Z-type resists such as AZ1350J manufactured by 7P V Co., Ltd. are irradiated with a 1-on-kilometre beam and then developed, fine resist film turns can be formed with high precision.

As is well known, AZ series V cysts of Shipley A, such as AZ1350J, are positive resists, but in the present invention, they apparently exhibit characteristics as negative resists.

That is, when a resist film formed by applying AZ-based V cyst is irradiated with an ion beam such as hydrogen ions, the photosensitive groups of the resist are destroyed.

It becomes insensitive to ultraviolet light and becomes insoluble in alkaline fA1 liquid.

Although the I-site bond of orthoquinone azide, which is necessary for the photosensitizer of AZ-based photoresists, is destroyed, since the formation of carboxylic acid does not occur, it becomes insensitive to ultraviolet rays and is not sensitive to alkaline m-concentrated solutions. Becomes insoluble.

On the other hand, ion? The portions that were not irradiated with ultraviolet rays are exposed to ultraviolet rays to produce carboxylic acid, so that they become soluble in alkaline development.

Therefore, after selectively irradiating desired portions of the resist film with ion beams, the entire surface is irradiated with ultraviolet light.

If you develop with an alkaline developer, only the areas irradiated with the ion beam will remain! Then, the portion d is removed to form a negative resist pattern 4.

When an ion beam is used for irradiation to form a resist pattern, the number of resists is small, so microfabrication becomes OT.
It is Noh. It has advantages such as being able to use a thick I-regis 14, and in addition, when using Naruko dAt, the sensitivity is about an order of magnitude [higher, so the running speed Rf: can be faster, which is a great feature in practical terms. I'm also doing M.

Furthermore, since the resulting resist pattern has an unstable portion of the resist removed by ion embroidery irradiation, its resistance to plasma and other radiation is significantly improved. Moreover, as mentioned above.

Since it is possible to use a thick resist film, the resist pattern described above can be used as an excellent mask in dry etching.

Ninth, the formation of extremely fine resist patterns and increase in proof stress during dry etching are 11 important issues that could not be solved using conventional methods.

The present invention makes it possible to solve both problems at the same time.

Formation of fine patterns by dry etching has become extremely easy.

Implementation In the present invention, the amount of hydrogen ion irradiation can be selected from a wide range.

Figure 41 shows AZ135 with a thickness of 1 μm formed on a substrate.
The relationship between the amount of hydrogen ion irradiation and the remaining film thickness after development is shown when the entire surface was irradiated with ultraviolet light at 0 Jg at 180 KeV4C/10 speed and developed.

As is clear from Figure 741, the irradiation amount is
When it exceeds 0-"C/cWI", ijL * Button photoresist remains), is 3.2XIO-・0
When 7 cm'' IK- was applied, a photoresist film with approximately the same thickness as the coated photoresist film remained, but the same was true even if the initial thickness of the photoresist film was different.

In this example, a clear photoresist pattern could be obtained with a radiation dose of 1.6 x 10 cm or more, and similar results were obtained even if the initial film thickness was different.

Example 2! s2 diagram is g thickness IAmohzlssoamot-tr
Irradiate the ion beam for am minutes and 1 irradiation ji13L2X1G-
@C%cm勺.

The relationship between the thickness of the permanent photoresist group 〇 film remaining when the entire surface is irradiated with ultraviolet light and developed and the amount of ion irradiation is shown.

As is clear from Figure 2, the ion energy is approximately 5
At 0 KeV or more, the photoresist remains in the image, but if the photoresist film is irradiated with an acceleration energy of 70 KeV or more, no decrease in film thickness is observed, and the applied n*photoresist film is It remains as it is.

The ion energy required to prevent film thickness reduction due to development is approximately proportional to the coating film thickness before ion beam irradiation.

For example, when the coating film thickness before ion irradiation is 1 μm,
As mentioned above, the ion energy required to maintain the g thickness without reducing it is approximately 70 KeV or more, but when the coating film thickness is approximately 2 μm.

An ion beam of approximately 140 K@V or more is applied to the photoresist.
By irradiating the film, it is possible to prevent the film thickness from decreasing due to development.

According to experiments, the applied e)L/resist film thickness tr
Regarding the relationship between @m and the hydrogen ion acceleration energy E and lI required to prevent film thickness reduction due to development.

E @MW (KeyJ medium 14 t eta (nm
) (1) It was found that there is a relationship n
Ta.

However, the photoresist film thickness is 0.7μm (7QQnm
), the irradiation energy is approximately 50 KeV.

When the irradiated ion beam contains something other than hydrogen ions, the proportional relationship holds true just by changing the coefficient of equation (υ), so the 4I relationship can also be easily determined by experiment. I can do it.

Also, the appropriate irradiation dose varies depending on the ionization process, but in both cases it can be easily determined through experimentation, as the relationship is similar to that of the water-based platform shown in Figure 1.

Example 3 First, as shown in Figure 3, P! ! 110Ω・sub(1
A photoresist film 2 of AZ135UJJt with a thickness of 1#miC* is formed on a silicon wafer l having a surface (00) by ordinary spin coating, and prebaked at 90C for 20 minutes.

Next, as shown in Figure 3 ■, apply the above photoresist g4.
At the desired portion 4 of 2, hydrogen ions (3.2
"(2X10"cIn-") was irradiated. ・", ・As shown in FIG. 3 (Q), the entire surface of the photoresist film 2 is irradiated with ultraviolet rays 5. In No. 4, the photosensitive groups are destroyed by irradiation with aqueous ions, so the solubility does not increase by UV irradiation, but the part that is not irradiated with hydrogen ions is exposed to #external radiation and can be converted into the current 1 solution. It becomes molten.

The amount of ultraviolet irradiation in this step is approximately 80 to 300 J/crs, as long as the portions not irradiated with hydrogen ions are completely removed by development. 100 mJ/cIN''.

After irradiating with water-based ion beam and ultraviolet rays, 130C13
After 0 minutes of post-exposure baking, ME312 (trade name,
When performing ij4 imaging using rice 1 ship V isha shogi) as a present, as shown in Fig. 3 0, what is the tip part I that is irradiated with ultraviolet light? ! ! Only the portion 4 irradiated with hydrogen ions remained on Ueno S1.

In the above embodiment, both A and A are used as resists.
However, the photoresist that can be used in the present invention is not that of Z1350J but, for example, A
Many photoresists can be used, such as AZ-based photoresist such as Z1450 manufactured by Kutsuprey Co., Ltd. and 0FPR800 (trade name, manufactured by Kyoi Kakogyo Co., Ltd., 1iIL).

That is, 1) the present invention is to destroy the photosensitive groups of the photoresist by ion beam irradiation so that it is not sensitive to external radiation, thereby using a positive photoresist to look like a negative photoresist (e) L/cyst. Because it is,
For example, a Tanizashi positive photoresist having a photosensitive group that can be destroyed by irradiation with an ion beam, such as a diazo compound, can be used.

In addition, the ions to be irradiated were not only 9H0 used in the above-mentioned example, but also H; Alternatively, Ll,' can be used. If a more refined ion is used, the energy required for irradiation will increase (for example, B9
It takes about 200
For example, B. B * 't' C * , N
It is also possible to irradiate with ions that are slightly different from the above ions, such as * and O* ions.

According to the present invention, as is clear from the above explanation.

Because irradiation with ion beams with low reflection and low reflection is used in conjunction with irradiation with ultraviolet rays, it is possible to form fine photoresist patterns with a thick film thickness, which is difficult to achieve with conventional methods.
Moreover, the resulting photoresist material has extremely high dry etching resistance.

Using this, a desired fine pattern can be formed with high precision by performing 54 times of dry etching.

[Brief explanation of the drawing]

Figures 1 and 2 are curve diagrams showing the relationship between the hydrogen ion irradiation amount 2 and ion energy and the thickness of the photoresist film remaining after development, respectively, and Figure 3 is a diagram showing an embodiment of the present invention. Ruru. 1...Crycon wafer, 2...Photoresist film,
3...Hydrogen ion-14...Part irradiated with hydrogen ion beam, 5...Ultraviolet light, 6...Ivy irradiated only with ultraviolet light 1. 1) %, 3 Figure (A Anzono 3 Figure (B) 1~3 5g <cノ+i↓++i++ to 5

Claims (1)

[Claims] 1. A pattern forming method including the following steps: (1) A step of selectively irradiating a desired portion of a positive photoresist film with an irradiation line. (2) A step of irradiating the entire surface of the photoresist film with ultraviolet rays. (3) A step of developing the photoresist film and removing the portion irradiated only with the ultraviolet rays. The pattern forming method according to claim 1 or 2.