JPH03184319A - Irregular pattern forming method - Google Patents

Abstract

PURPOSE:To stably obtain an irregular pattern having high sensibility and high resolution with excellent reproducibility without requiring wet developing treatment by an organic solvent by irradiating a film composed of a specific high molecular material with energy beams and heating the film. CONSTITUTION:A film 3 consisting of a high molecular material having carbon as a main chain and at least one kind of an atom selected from a group made up of a hydrogen atom and a halogen atom as the side chain of the main chain is irradiated with energy beams 4, and heated. The polychlorotrifluoroethylene plasma film 3 in thickness of 1mum is formed onto a silicon wafer 1, on which an SiO2 film 2 is formed, through a plasma CVD method while using chlorotrifluoroethylene as a raw material. An electron-beam pumping fixed target system is used as an X-ray source in a vacuum, and a desired image is adhesively exposed for one hundred and eighty min. When a latent image pattern acquired is heated at 150 deg.C in an air atmosphere, an exposed section is removed, and a positive type irregular pattern, in which an unexposed section is left, is obtained.

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,
Regardless of negative type, DUV (short wavelength ultraviolet light), EB (
After irradiating the resist material with an energy beam such as electron beam (electron beam) or It has been common to form an uneven pattern by utilizing the difference in dissolution rate based on the difference in .

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.

1) 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
Symp, Proc, 1089 (1989, 3) The method for forming the concavo-convex pattern that requires 1° is a dry development process that does not use an organic solvent, so the above-mentioned 1) and 2).
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. Therefore, it is an object of the present invention to solve the problems of the prior art described above, and to provide a concavo-convex pattern that does not require wet development using an organic solvent and that can stably obtain a concave-convex pattern with high sensitivity and high resolution with good reproducibility. The object of the present invention is to provide a method for forming the same.

(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.

(Function) When a specific polymer film is irradiated with an energy beam, the amount of energy of the energy beam is reduced so that ablation of the polymer film does not occur and the energy beam passes through the polymer film and reaches the substrate surface. By suppressing the
Reflection of the energy beam on the substrate and emission of secondary electrons are suppressed, thereby avoiding a decrease in pattern resolution and damage to the substrate itself.

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 heat-treating the latent image, the polymer in the area irradiated with the energy beam is volatilized and developed, forming a positive uneven pattern. This uneven pattern has a sharp shape because the energy amount of the energy beam used in the first step is controlled within an appropriate range, and no deformation or shift of the pattern occurs.

(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, (meth)acrylonitrile, (meth)
Homopolymers such as acrylamide and two of these monomers
There are various types of copolymers, such as copolymers consisting of more than one species, but their chemical bonds are easily dissociated by the energy beam (that is, it is easy to form a latent image), and the durability of the formed uneven pattern, chemical and physical What is preferable in terms of properties is
consisting of halogenated hydrocarbon chains, e.g. P
TFE, polytetrachlorethylene, polytrifluoroethylene, polytrichloroethylene, polydifluoroethylene, polydichloroethylene, polyfluoroethylene, polychloroethylene, polychlorotrifluoroethylene, polypromotrifluoroethylene, or coexistence of monomers constituting these Examples include polymers.

A polymer film made of the above polymer material can be 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. Preferably, if the film thickness is less than the above range, it is unsatisfactory in that pinholes are likely to occur, making it difficult to form a fine pattern, etc. On the other hand, if the film thickness exceeds the above range, high aspect ratio may occur. This is not preferable because it becomes difficult to obtain a ratio pattern.

The polymer film may be formed by any conventionally known method, but from the viewpoint 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 amount of energy beam irradiation varies depending on the type of polymer material used, its film thickness, the desired uneven pattern shape, and the type of energy beam used, and cannot be unconditionally determined. 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
When the halogen bonds dissociate, a latent image consisting of the dissociated region (irradiated region) and the undissociated region (unirradiated region) is formed (see Figure 1).Also, the unevenness formed by the irradiation amount of the energy beam Control of the depth of the shape is also possible.

Next, the heating step b) 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. The temperature used for heat treatment is
It 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 determined unconditionally, but it is generally between 50 and 55.
The heating time is generally about 0.5 seconds to 1 hour, preferably about 1 second to 30 minutes at a temperature of 0°C, preferably 80 to 500°C.

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 apparatuses, or may be performed continuously.

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

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

Then in vacuum (2X l O-” Torr),
An electron beam excitation fixed target (Rh: wavelength =
4.6) method, a desired image was exposed in close contact for 180 minutes under the conditions of accelerating voltage = 20 kV and accelerating current = 48 mA. Note that this exposure condition is 80 mJ/on the film surface.
It was crrd.

When the obtained latent image pattern was heated at 150° C. in an air atmosphere, 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 air atmosphere, 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 air atmosphere 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 positive uneven 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 was set to 80 μC/c rd and 70 μC/c to each region.
rrr, 60ILC/crrr and 50uC/crd
The images of each were drawn as follows.

When the obtained latent image pattern was heated at 120° C. in an air atmosphere, a positive uneven pattern with a thickness corresponding to the exposure time was formed.6 The line width of the above pattern was 0.2.
The lines and spaces were 5 to 1 μm, 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 5 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,
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, it was heated to 130° C. in an air atmosphere to obtain a positive uneven pattern.

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 with a thickness of 1 μm was formed using promotrifluoroethylene as a raw material in the same manner as in Example 1, and then irradiated with an exposure energy of 40 mJ using a DUV irradiation device. The latent image pattern obtained was heated at 125° C. in an air atmosphere to obtain a positive uneven pattern.

The line width of the above 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 positive uneven 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, H4) gas as raw materials in the same manner as in Example 1, and then using an EB lithography system. Using acceleration voltage = 2
The latent image pattern obtained by drawing at 0 kV is
A positive uneven pattern was obtained by heating at 50°C.

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 uC/C, 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 I obtained by the same plasma CVD method used in Example 3
A PTFE plasma polymerized membrane of LLm was prepared.

Next, using the same EB drawing apparatus as in Example 3, drawing was performed at an acceleration voltage of 15 kV and an exposure amount of 10 μC/cd, 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. 1: Silicon wafer 2: 5iOi 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. (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 an uneven pattern according to claim 1, wherein the energy beam is irradiated with an amount that does not melt the polymer material.