JPS63307450A - Method for forming resist pattern - Google Patents

Abstract

PURPOSE:To prevent the thermal flow of a resist by crosslinking previously the resist polymer applied on a substrate, and then, selectively irradiating a radiation energy ray to the obtd. resist thereby decomposing and vaporizing an irradiated part. CONSTITUTION:The resist is formed by applying for example, a solution contg. a methyl polymethacrylate and a crosslinking agent on the substrate, followed by thermally or optically crosslinking the obtd. resist. Next, the above-mentioned resist is selectively irradiated by a light, an electron ray, a X-ray or an ion beam, and the irradiated part is decomposed and vaporized, thereby self- developing said part. As the polymer of the part irradiated the radiation energy ray is hard to liquefy, the thermal flow does not occur, whereby a minute pat tern is formed with a good accuracy.

Description

[Detailed Description of the Invention] [Summary] This is a self-developing method in which the irradiated area is decomposed and vaporized and developed at the same time as exposure. After crosslinking in advance, the resist polymer is selectively exposed to light, electron beams, A pattern is formed by irradiating an ion beam and decomposing and vaporizing the irradiated portion.

This eliminates the heat flow and forms a highly accurate pattern.

[Industrial application field]

The present invention relates to a method for forming a resist pattern by self-development.

As is well known, when manufacturing semiconductor devices such as ICs and LSIs, microfabrication is carried out exclusively by lithography technology. There is a demand for easy processing and low manufacturing costs.

[Conventional technology] Resist is generally a polymeric coating that can be exposed to light or electron beams.

A material whose solubility in a solvent changes when irradiated with radiant energy rays such as X-rays or ion beams, and is used as a protective mask when etching exposed substrates such as semiconductor substrates. It is used as a.

In addition, there are two types of resists: positive type and negative type.Positive type refers to resists in which the irradiated (exposed) areas are easily dissolved in solvents, and negative types are resists in which exposed areas are difficult to dissolve in solvents. However, one typical example is that the molecular weight of the resist changes with exposure to light, and those with smaller molecular weights have the property of being more soluble in solvents. That is, photodegradable polymers (!
! If the unexposed part of the aggregate has a molecular weight of about 10,000, when exposed to light, the exposed part decomposes and becomes, for example, a molecular weight of about 1,000, and therefore the exposed part dissolves in the solvent and becomes positive type. It has a nature. Furthermore, photocrosslinkable polymers have a low molecular weight in unexposed areas, and when exposed, the exposed areas crosslink and increase in molecular weight, thus becoming negative-type.

By the way, conventionally, a resist is applied to a substrate to be exposed, and then the resist surface is selectively irradiated with radiant energy rays such as light through a mask in an exposure device, and then immersed in a solvent such as an organic solvent. The dissolved portion is removed (developed) to form a protective mask for the resist.

However, recently, a method called self-development has been studied, and a schematic diagram of this self-development method is shown in FIG. In the figure, 1 is a vacuum container, 2 is an exhaust port, and 3 is a mask (
4 is a stage containing a heater, and 5 is a substrate to be exposed. In this pattern forming method, the substrate to be exposed 5 is housed in a vacuum container L and heated to about 100°C. , Masks radiant energy rays such as light 3
The resist is selectively irradiated through the light. This is a method of forming a positive resist in which the molecular weight of the resist in the exposed area becomes smaller, the resist in that area is vaporized and evacuated, and patterned.

This self-developing method does not require the conventional development process using a solvent, so the processing process is simplified and the processing cost is low.In addition, since there is no need to immerse the resist pattern in a solvent, the resist pattern does not swell. Therefore, this method has the advantage that it is easy to obtain a highly accurate pattern.

[Problems to be Solved by the Invention] However, in such a pattern forming method using a self-developing method, heat flow occurs during the process in which the resist evaporates from a solid to a gas, making it impossible to form a sufficiently normal pattern. There's a problem. This is illustrated in FIG. 4. During the exposure process of the self-developing method, the portion of the exposed substrate 5 that is irradiated with light undergoes photodecomposition and is converted into a liquid state before being vaporized. It creeps up in the unexposed area, forming the shape shown in the figure, making it impossible to cut the pattern sufficiently.

The object of the present invention is to eliminate this heat flow in the resist and form a highly accurate resist pattern by a self-developing method.

[Means for solving the problem] The purpose is to apply a resist polymer to the substrate to be exposed,
This is achieved by a resist pattern forming method in which the resist polymer is crosslinked in advance, and then the resist polymer is selectively irradiated with radiant energy rays, and the irradiated portions are decomposed and vaporized to self-develop.

[Function] That is, the present invention is a method of patterning by crosslinking the resist polymer in advance, selectively irradiating the resist polymer with radiant energy rays, and decomposing and vaporizing the irradiated portions.

If the resist is crosslinked in advance in this way, the resist will be connected by the crosslinking agent and will be connected to a three-dimensional three-dimensional structure like one molecule on the exposed substrate surface. When it is irradiated with radiant energy, the irradiated part decomposes into circular-shaped molecules, and these circular-shaped molecules are difficult to liquefy, so they sublimate immediately without softening, and no heat flow occurs. . Therefore, a highly accurate pattern is formed. - [Example] Hereinafter, it will be explained in detail using an example.

(2,6-Bis(4'-Azido Benzal
) cyclohexanone) is used.

A substrate to be exposed is coated with it and prebaked at about 150°C. Then, the linear polymer (PMMA) is crosslinked and connected, and the reaction formula is shown in FIG.

Next, the substrate to be exposed is exposed to light using an excimer laser (ArF; wavelength 198n*) while being heated to 100°C. Then, with a laser beam intensity of about 100 mW/ad and irradiation for 3 minutes, a 0.5 μm resist with l]1 Jff can be resolved with good accuracy, and no heat flow will occur. FIG. 2 is a diagram showing the reaction of decomposition of a linear polymer by laser irradiation, and the jagged parts are linear polymers.

This first example is an example in which the material is thermally crosslinked and photodecomposed, and next, a second example in which the material is photocrosslinked and thermally decomposed will be described.

Apply it to the substrate to be exposed, and use a mercury lamp (wavelength 435).
．． Expose the entire surface to 8nI++). Then, the linear polymer (cyclized isoprene) is photocrosslinked and connected.

Next, the substrate to be exposed is exposed to light using an excimer laser (KrF; wavelength 248 nm) while being heated to 100°C. Then, the laser light intensity is approximately IW/cj 1 pulse (Io
The 0.6 μm thick resist is accurately resolved by irradiation (ns/pulse), and no heat flow occurs.

This is a method of irradiating one pulse of strong energy to cause thermal decomposition.

As in these examples, the present invention involves pre-crosslinking elongated linear polymers, connecting them with a crosslinking agent to form a three-dimensional structure, and then irradiating it with radiant energy rays, which decomposes it into round-shaped molecules. Round-shaped molecules are difficult to liquefy and therefore easily sublime, so that a highly accurate pattern can be formed without heat flow.

On the other hand, in conventional self-development methods that do not crosslink in advance, elongated linear polymers are exposed to light and decomposed;
Molecules with this elongated shape are more likely to liquefy and, therefore, more likely to generate heat flow.

[Effects of the Invention] As is clear from the above description, according to the present invention, in the self-development method in which the irradiated area is decomposed and vaporized and developed at the same time as exposure, heat flow is eliminated and 1) fine patterns can be formed with high accuracy. Therefore, it greatly contributes to cost reduction and quality improvement of semiconductor devices.

[Brief explanation of drawings]

FIG. 1 is an example diagram showing the crosslinking reaction formula, FIG. 2 is a diagram showing the decomposition reaction, FIG. 3 is a schematic diagram of the self-developing method, and FIG. 4 is a diagram showing conventional problems. In the figure, 1 is a vacuum container, 2 is an exhaust port, 3 is a mask, 4 is a stage, and 5 is a substrate to be exposed. C→CH2−C→−(PMMA) −O H3 C=O C￥−13 ￥jIhtsu reaction 177 examples Flash Figure 1 Self ■ Men's book / 1 product fist U Figure 3

Claims (1)

[Claims] After applying a resist polymer to a substrate to be exposed and crosslinking it in advance, the resist polymer is selectively exposed to light, electron beams, and X-rays.
A method for forming a resist pattern, which comprises irradiating a resist pattern with a line or an ion beam, decomposing and vaporizing the irradiated portion, and self-developing the resist pattern.