JPH03182757A - Formation of rugged pattern - Google Patents

Abstract

PURPOSE:To form high-sensitivity rugged patterns by separating a stage for irradiating a film consisting of a high-molecular material with an energy beam and a stage for heating the film so as to avert the abrasion of the high- molecular film. CONSTITUTION:The high-molecular material consisting of particularly halogenated hydrocarbon chains is used in terms of the easy dissociation of chemical bonds by the energy beam and the durability, etc., of the formed rugged patterns. The film 3 consisting of the high-molecular material is irradiated with the energy beam 4 and is heated in an oxidative atmosphere. The energy quantity of this energy beam 4 is then suppressed to the extent of not causing the abrasion of the high-molecular film 3 at the time of irradiating the high-molecular film 3 with the energy beam 4. The reflection of the energy beam on a substrate 1 and the release of secondary electrons are thereby suppressed and the degradation in pattern resolution and the damage of the substrate itself are averted. The rugged patterns of the high sensitivity and high resolution are stably obtd. with good reproducibility.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides an uneven pattern (
The present invention relates to a method for forming a relief pattern (relief pattern), and particularly relates to a method for forming an uneven pattern that does not include a wet development process and can form an uneven pattern on the order of submicrons.

(Prior art and its problems) Conventionally, various inorganic or organic resist materials have been known for forming fine patterns of integrated circuits, etc., but pattern forming methods using these resist materials are as follows: positive type,
Energy beams such as DUV (short wavelength ultraviolet light), EB (electron beam), and X-rays, regardless of negative type,
After irradiating the resist material to form a latent image consisting of a difference in molecular weight in the resist material between the irradiated area and the unirradiated area, an organic solvent is used to utilize the difference in dissolution rate based on the difference in molecular weight. Therefore, it was common to form a concavo-convex pattern.

However, the conventional method uses an organic solvent in the development step, that is, the step of forming the uneven pattern, and therefore has the following problems.

l) It is difficult to select an organic solvent depending on the resist material used.

2) It is difficult to form fine patterns because the organic solvent causes the resist material polymer to swell and the formed pattern to peel off.

In addition, in recent years, polytetrafluoroethylene (PTFE) membranes are irradiated with electron beam pulses and completely self-evaporated (ablated) to form via holes.
A method of forming a concavo-convex pattern is known [J, K
r1shnas wamg et al, SPTE
See Symp, Proc, 1089 (1989, 3)]. The method for forming such a concave-convex pattern is a dry development method that does not use an organic solvent.
However, it does have new problems such as a reduction in pattern resolution and increased damage to the integrated circuit board itself due to the reflection of the energy beam or the emission of secondary electrons at the interface between the PTFE film and the substrate. are doing.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, and to form a concavo-convex pattern that does not require wet development using an organic solvent and can stably obtain a concave-convex pattern with high sensitivity and high resolution with good reproducibility. The purpose is to provide a method.

(Means for solving problems) The above objects are achieved by the present invention as described below.

That is, the present invention has carbon as the main chain, and at least one side chain thereof selected from the group consisting of hydrogen atoms and halogen atoms.
For a film made of a polymeric material containing seed atoms,
A method for forming a concavo-convex pattern, comprising: a) a step of irradiating an energy beam; and b) a step of heating in an oxidizing atmosphere.

(Function) When a specific polymer film is irradiated with an energy beam, the amount of energy of the energy beam is suppressed to the extent that the polymer film is not ablated, thereby preventing reflection of the energy beam on the substrate and secondary Emission of electrons is suppressed, and deterioration of pattern resolution and damage to the substrate itself are avoided.

In the above process, the polymer structure is dissociated (degraded) in the area irradiated with the energy beam, and a latent image corresponding to the irradiated area is formed.

By heating the above layer image in an oxidizing atmosphere,
The polymer in the area irradiated with the energy beam is quickly volatilized and developed, forming a positive uneven pattern. This uneven pattern is created by controlling the energy amount of the energy beam used in the first process within an appropriate range.
Its shape is sharp and the pattern does not deform or shift.

(Preferred Embodiments) Next, the present invention will be described in more detail by citing preferred embodiments.

The material forming the polymer film used in the present invention is a polymer material that has carbon as its main chain and at least one type of atom selected from the group consisting of hydrogen atoms and halogen atoms in its side chains. As far as possible, any conventionally known polymeric materials can be used.

Examples of such polymeric materials include ethylene, propylene, butene, butadiene, isoprene, chlorobrene, styrene, vinyl chloride, vinyl acetate, vinylidene chloride, vinyl fluoride, vinylidene fluoride, (meth)acrylic acid, esters thereof, There are various examples including homopolymers such as (meth)acrylonitrile and (meth)acrylamide, and copolymers consisting of two or more of these monomers.
It is preferable that chemical bonds are easily dissociated by the energy beam (that is, it is easy to form a latent image) and that the formed uneven pattern is made of halogenated hydrocarbon chains in terms of durability, chemical and physical properties. things, e.g. PT
FE, polytetrachlorethylene, polytrifluoroethylene, polytrichlorethylene, polydifluoroethylene, polydichloroethylene, polyfluoroethylene,
Examples include polychloroethylene, polychlorotrifluoroethylene, polypromotrifluoroethylene, and copolymers of monomers constituting these.

The polymer film made of the above polymer material is preferably formed as a thin film, generally 0.05 to 5 μm thick, preferably 0.2 to 1.2 μm thick, on any substrate such as a silicon wafer. If the film thickness is less than the above range, pinholes are likely to occur, making it difficult to form a fine pattern, which is unsatisfactory.On the other hand, if the film thickness exceeds the above range, it may result in a high aspect ratio. This is undesirable in that it becomes difficult to obtain a pattern.

The above-mentioned polymer film may be formed by any conventionally known method; however, from the point of view of thin film uniformity, CVD method (
chemical vapor deposition method), plasma CVD method, photoCVD method,
Sputtering method, reactive sputtering method,
Ion blating method and electron beam evaporation method are suitable.

In step a), the energy beam irradiated onto the polymer film may be any energy beam that can dissociate the chemical bonds in the polymer film, but the resolution of the resulting concavo-convex pattern, etc. Considering DUV, VUV (vacuum ultraviolet light), EB, X-ray, IB
(ion beam) etc. are preferred.

The energy beam irradiation method is a method of selectively irradiating the polymer film, and may be, for example, a conventionally known irradiation method using a drawing method, a light shielding mask, or the like.

Regarding the amount of energy to be irradiated, one of the essential conditions is that no ablation of the polymer film occurs, and more preferably, that no ablation of the polymer film occurs, and that the energy beam passes through the polymer film and reaches the substrate surface. It is preferable that the irradiation amount does not reach .

The irradiation amount of such an energy beam varies depending on the type of polymer material used, its film thickness, the desired uneven pattern shape, the type of energy beam used, etc., and cannot be further specified. As illustrated, it can be easily determined by those skilled in the art through several experiments depending on the type of polymer material, film thickness, substrate type, energy beam type, etc. selected.

By irradiating the energy beam as described above, carbon-hydrogen bonds or carbon-hydrogen bonds in the polymer material constituting the polymer film are
The halogen bonds are dissociated, and a latent image consisting of such dissociated sites (irradiated sites) and undissociated sites (unirradiated sites) is formed (see Figure 1).

In addition, the depth of the uneven shape formed by the energy beam irradiation changes, and when the energy beam reaches near the substrate surface, the entire polymer film is volatilized as shown in the figure, while the irradiation amount changes. As the number decreases, the depth of the recess decreases.

Next, the heating step b) in an oxidizing atmosphere for developing the latent image will be explained.

Such a heating step may be performed after the step of irradiating the energy beam, or may be performed simultaneously with the irradiation of the energy beam.

An oxidizing atmosphere means an atmosphere that is more oxidizing than air (atmosphere). For example, if an oxidizing gas atmosphere such as oxygen or ozone is applied to a system in which a heating process is performed, 60% of the entire system is heated.
% or more, more preferably 80% or more. Here, it is preferable that the proportion of the oxidizing gas in the entire system be 60% or more, since this further reduces the development processing time and further sharpens pattern formation. Moreover, the pressure may be under reduced pressure or increased pressure and is not particularly limited.

The amount of oxygen is a factor that determines the aspect ratio of the resulting uneven pattern. By employing such an oxidizing atmosphere, development processing can be performed at a lower temperature, and deformation of the uneven pattern due to heat can be better prevented.

The temperature used for the heat treatment varies depending on the type of polymer used, its film thickness, the desired unevenness pattern, the type of energy beam used, etc., and cannot be further specified, but it is generally between 50 and 550. The heating time is generally about 0.5 seconds to 1 hour, preferably about 1 second to 30 minutes.

Further, various heating methods can be used, such as heating with an oven, heating with a hot plate, and flash annealing using a lamp or the like.

In the above step b), the bond/dissociation site (the energy beam irradiation site) of the latent image formed in the above step a) is volatilized to form a desired uneven pattern (see FIG. 2C).

As mentioned above, the method for forming a concavo-convex pattern of the present invention is as described in a) above.
These steps may be performed sequentially in the same or different equipment, consecutively, or simultaneously. It goes without saying that a film forming step and a post-processing step for forming the uneven pattern may be added.

(Example) Next, the present invention will be explained in more detail by giving examples and comparative examples.

Example 1 Silicon wafer A provided with SiO□ film 2 as shown in the first figure
-1, a polychlorotrifluoroethylene film 3 having a thickness of 1 μm was formed by plasma CVD using chlorotrifluoroethylene as a raw material.

Next, in a helium atmosphere, using an electron beam excitation fixed target (Rh dual wavelength = 4.6) type X-ray source, a desired image was closely focused for 180 minutes under the conditions of accelerating voltage = 20 kV and accelerating current = 48 mA. exposed. Note that this exposure condition was 100 mJ/crtr on the film surface.

When the obtained latent image pattern was heated at 150° C. in an atmosphere of oxygen/nitrogen=5:l, a positive uneven pattern in which exposed areas were removed and unexposed areas remained was obtained.

Even when the line width of the above-mentioned pattern was 0.35 and 0.5 μm, no deformation of the pattern or shift of pattern dimensions was observed, and a positive uneven pattern with high sensitivity and high resolution was obtained.

Example 2 In Example 1, the exposure area was divided into four, and the exposure time was set to 45 minutes, 90 minutes, 135 minutes, and 180 minutes, respectively.
Thereafter, a desired image was subjected to contact exposure in the same manner as in Example 1.

When the obtained latent image pattern was heated at 120° C. in an atmosphere of oxygen/nitrogen=5:1, a positive uneven pattern having a thickness corresponding to the exposure time was formed.

The line width of the above pattern was line and space of 0.35 to 1 μm, and no deformation of the pattern line width or shift of pattern dimensions was observed, and a positive uneven pattern with high sensitivity and high resolution was obtained. .

Example 3 A PTFE plasma polymerized film with a thickness of 1 μm was formed using tetrafluoroethylene as a raw material in the same manner as in Example 1, and then a latent image pattern was obtained by drawing using an EB drawing device at an accelerating voltage of 15 kV. was heated at 120°C in an oxidizing atmosphere of oxygen/nitrogen = 4.5:1 to obtain a positive uneven pattern.

The line width of the above pattern is 0.25 to ILtm.
and spaces, and no deformation of the pattern line width or shift of the pattern dimensions was observed, and a positive type concavo-convex pattern with high sensitivity and high resolution was obtained.

Example 4 In Example 3, the exposure area was divided into four, and the exposure amount for each area was 80 μC/cnf and 7° uC/an! ,
Each image was drawn as 60uC/crd and 50uC/crrf.

When the obtained latent image pattern was heated at 120'C in an oxidizing atmosphere of oxygen/nitrogen=4.4:l, a positive uneven pattern having a thickness corresponding to the exposure time was formed.

The line width of the above pattern was line and space of 0.25 to 1 μm, and no deformation of the pattern line width or shift of pattern dimensions was observed, and a positive uneven pattern with high sensitivity and high resolution was obtained. .

Example 5 A PTFE plasma polymerized film with a thickness of Ium was formed using tetrafluoroethylene as a raw material in the same manner as in Example 1,
Argon (
A desired latent image was formed by irradiation with an ion beam (Ar"). The argon acceleration voltage at that time was 20 kV. Thereafter, the positive image was heated to 130°C in an oxidizing atmosphere of oxygen/nitrogen = 5:1. A mold uneven pattern was obtained.

This pattern is 2 to 10 μm faithful to the mask pattern.
A positive uneven pattern with high sensitivity and high resolution was obtained.

Example 6 A plasma polymerized film of polypromotrifluoroethylene having a thickness of 1 μm was formed using promotrifluoroethylene as a raw material in the same manner as in Example 1, and then using a DUV irradiation device under the condition of exposure energy of 4 mmJ. The latent image pattern obtained by irradiation was heated to 125° C. in an oxidizing atmosphere of oxygen/nitrogen=5.5:1 to obtain a positive uneven pattern.

The line width of the above-mentioned positive concavo-convex pattern was line and space of 0.45 to 1 μm, and no deformation of the pattern line width or shift of pattern dimensions was observed, and a pattern with high sensitivity and high resolution was obtained. .

Example 7 A plasma polymerized film of a copolymer of tetrafluoroethylene and ethylene with a thickness of 1 μm was formed using tetrafluoroethylene and ethylene (C, H,) gas as raw materials in the same manner as in Example 1, and then EB drawing was performed. Accelerating voltage using the device = 20
The latent image pattern obtained by drawing at kV is oxygen/nitrogen = 5.5
:Heating was performed in an atmosphere of 1 to obtain a positive uneven pattern.

The line width of the above pattern was line and space of 0.25 to 1 μm, and no deformation of the pattern line width or shift of pattern dimensions was observed, and a pattern with high sensitivity and high resolution was obtained.

Comparative Example 1 Thickness 1 obtained by the same plasma CVD method used in Example 3
A μm PTFE plasma polymerized membrane was prepared.

Next, after drawing was performed using the same EB drawing apparatus as in Example 3 at an acceleration voltage of 15 kV and an exposure amount of 100 gC/cd, heating was performed under the same conditions as in Example 3.
Although a positive concave-convex pattern was obtained, the positive concave pattern was narrower than the target line width, and the line width was deformed.

Note that under these conditions, something like a pattern was already observed under a microscope at the latent image stage.

Comparative Example 2 Thickness 1 obtained by the same plasma CVD method used in Example 3
A μm PTFE plasma polymerized membrane was prepared.

Next, using the same EB lithography apparatus as in Example 3, lithography was performed at an acceleration voltage of 15 kV and an exposure dose of 10 μC/crtr, and then heated under the same conditions as in Example 3, but at a level that could be determined by microscopic observation. No positive concave pattern was formed.

(Effects of the Invention) As explained above, according to the pattern forming method of the present invention, by separating the concavo-convex pattern forming process into the energy beam irradiation process and the heating process, it is possible to ablate the polymer film or to remove the substrate. without causing any damage,
It became possible to form an uneven pattern.

Furthermore, the method of the present invention is applicable to the submicron region and can be incorporated into a vacuum-through process.

The method of the present invention as described above is useful for forming fine patterns such as integrated circuits, and is also useful for manufacturing various printing plates using conventional resist materials.

[Brief explanation of drawings]

FIG. 1 is a diagram schematically explaining the steps of the pattern forming method of the present invention. A indicates the polymer film formation process, b indicates the energy beam irradiation process, and C indicates the formed uneven pattern. l: Silicon wafer 2: 5i (h film 3: polymer film 4: energy beam diagram (C)

Claims (4)

[Claims] (1) A film made of a polymeric material having carbon as its main chain and at least one type of atom selected from the group consisting of hydrogen atoms and halogen atoms in its side chains is a) irradiated with an energy beam. and b) heating in an oxidizing atmosphere. (2) The method for forming an uneven pattern according to claim 1, wherein the polymeric material comprises a halogenated hydrocarbon chain. (3) The method for forming an uneven pattern according to claim 1, wherein the irradiation amount of the energy beam is such that the beam does not reach the substrate. (4) The method for forming a concavo-convex pattern according to claim 1, wherein the energy beam is irradiated with an amount that dissociates chemical bonds in the polymeric material but does not melt the polymeric material.