JPS61216429A - Peeling method of resist film - Google Patents

Abstract

PURPOSE:To peel and remove a resist film completely by heating the resist film in a pre-process, in which ion etching is conducted, and generating a transition to the resist film when peeling the resist film to which ions are implanted. CONSTITUTION:A resist film 12 is applied to the upper section of a substrate 11, and the ions of an element such as boron are implanted as shown in the arrow from the surface of the resist film in order to implant ions to a substrate exposed section 13 in an opening section. The properties of the resist film to which ions are implanted change by ion implanting ions in the surface section of the resist film to which ions are implanted, and a thick section A having the properties of the resist film and a property-change layer B in the surface can be distinguished considerably distinctly, and comply with a rate determination even in a reaction in which a resist is removed through etching. Etching rates remarkably differ even through the same etching process in a section A and a section B, and the etching rate of the property-change section B is reduced. Accordingly, the resist film can be removed completely, thus manufacturing products having high quality.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for removing a resist film, and more particularly to a method for easily and completely removing a resist film in which ions have been implanted.

2. Description of the Related Art Recently, the integration of semiconductor devices has progressed rapidly, and accordingly, it is necessary to form fine and precise patterns of semiconductor elements.

When forming electrodes, etc. on a semiconductor substrate by patterning, a resist film of a predetermined thickness is usually deposited on the substrate, and a mask is used on the resist film to expose the resist film to light projection, electron beams, or X-rays. After exposure, development and etching are performed, and finally the resist film is removed.

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In some cases, a resist film is used to block ion implantation when performing ion implantation. surface is not normal
The molecular structure of the 1-cyst film has changed into a resist film with properties that are quite different.

When removing a resist film that has been ion-implanted in this way, it is difficult to easily peel it off using conventional resist film removal methods, and the resist film must be removed repeatedly. The efficiency of the manufacturing process decreases because the resist film is peeled off.

For these reasons, there is a need for a method for easily and completely peeling off ion-implanted resist strips.

[Conventional technology]

FIG. 3 is a cross-sectional view of a semiconductor substrate for explaining a conventional method of peeling off and removing a resist film into which ions have been implanted by development and etching.

Generally, there are both negative and positive types of resist films, but for example, positive resist materials are
The main components are about 80% Talesol novolac resin and the remaining 20% is a photosensitive material, which is represented by the chemical formula shown below.

Talesol Novolak Resin Photosensitive Material The following examples will be explained using positive resist materials.

1.1μl of positive resist film 1 on silicon substrate 1
For example, in order to make the exposed region 3 of the silicon substrate surface an n-type or p-type conductor, the substrate surface is coated with a thickness of 1 to 1.3 μm and subjected to a predetermined patterning using a mask and exposure. Ion implantation is performed as shown by the arrow, but
For example, boron (B”), arsenic (As) are implanted as molecules.
), phosphorus (p''), and other elements are ion-implanted.

Usually, ion implantation is performed at an energy of about 100 KeV and a concentration of about 3E15.

During this ion implantation, ions are implanted into the region 3 of the silicon substrate where there is no resist, but at the same time the ions are implanted into the surface of the resist film, so the chemical composition of the resist film corresponds to the thickness of the ion implantation. changes and transforms.

Generally, the depth of deterioration is at most 10% of the thickness of the resist film.
Assuming that the thickness of the resist film is 1 μm, the thickness at which the quality deteriorates is approximately 100 μm. However, in a resist film that has been ion-implanted in this way, the azide groups of the photosensitive material are removed from the surface of the resist film. Since the nitrogen component evaporates as NOx, it becomes extremely difficult to peel off and remove the photosensitive portion remaining in the resist film due to energy constraints.

Patterns of deterioration of the resist film can be confirmed with the naked eye,
After the initially yellow resist film undergoes ion implantation, it changes color to green.

As an etching method for peeling off and removing such a resist film, dry etching using a microwave oxygen plasma method is employed, and the etching is performed using a plasma reactor under the following conditions.゛Oxygen: 100cc/min Argon = 100cc/min Power: IKW Pressure: ITorr Frequency: 2.45GH2 Under these conditions, the etching rate of the resist film is, for example, 20 sheets are processed at a rate of 1 μm/15 minutes. It is rare for a resist film that has been ion-implanted to be completely etched in a single etching process, and generally the peripheral portion of a resist film adhered to a substrate is relatively easy to be removed by etching. Often, the etching of the resist film in the central part of the resist film is incomplete and remains on the substrate.

FIG. 4 is a perspective view of the etched resist film formed on the substrate, showing that the resist film has been removed from the peripheral portion E of the substrate and remains in the central portion C. ing.

If the etching is incomplete as described above, the dry etching using microwaves described above must be repeated after the wet treatment described below, which makes the stamen manufacturing process considerably complicated.

Normal wet processing conditions are as follows.

(1) Chemical treatment by heating a mixture of hydrogen peroxide and sulfuric acid to 120°C for 15 minutes (2) Washing the shirt with water for 5 minutes (3) Repeating 5 minutes of water washing twice (4) Drying for 10 minutes (5) Inspection of Resist Residues on Substrate Surfaces For substrates on which a resist film remains on the substrate surface due to this wet etching, the above-mentioned dry etching is repeated again.

Recently, as a method for peeling and removing such a resist film, a dry ashing method has been put into practical use, in which a substrate on which a resist film is coated is peeled and removed using ultraviolet rays in an oxygen atmosphere.

Dry ashing using ultraviolet rays is an extremely promising method.The substrate on which the resist film is attached is placed in an oxygen atmosphere, and the surface of the resist film is directly irradiated with ultraviolet rays with a wavelength of λ=1B49A. The film is peeled off by ashing. Although this method is quite effective in removing the resist film, it currently requires an extremely high-intensity ultraviolet light emitter and the atmosphere in which the substrate is placed. The amount of oxygen is large at 10 to 201/min, and the diameter is 1 μm.
Problems remain in terms of efficiency in the manufacturing process, such as the fact that it takes approximately one hour to ash a resist film with a thickness of .

On the other hand, when performing ultraviolet ashing, a method has also been proposed in which the substrate on which the resist film is coated is heated, and it has also been proposed that this can significantly improve the efficiency of ashing time. In addition to the drawbacks, there are still many practical difficulties in removing a large amount of resist film, and for these reasons, we have developed a resist film that can easily and reliably peel off ion-implanted resist films. A peeling method is required.

[Problem that the invention seeks to solve]

Regarding the above-mentioned method of peeling off and removing a resist film that has been ion-implanted, in the conventional dry etching method, the resist film is often not peeled off completely and the work is often repeated, and it is also difficult to remove the resist film by irradiating it with ultraviolet rays. However, the method of peeling and removing the resist film by ashing in an oxygen atmosphere has problems in that it consumes a large amount of oxygen, uses a strong ultraviolet light source, and requires a long working process, making it unsuitable for mass production.

[Means to solve the problem]

The present invention provides a method for stripping and removing a resist film that has undergone ion implantation, which solves the above-mentioned problems. In the previous process, the resist film was
This can be achieved by a resist film stripping method that includes a heating step of heating at a temperature of 00° C. to 260° C. to cause a transition in the resist film.

[Effect]

The present invention provides a method for extremely easily and completely peeling off a resist film that has been ion-implanted. Before etching, the substrate coated with the resist film is heated at 200°C to 250°C in the atmosphere.
By heating to ℃, the resist film heated at this temperature undergoes transition, and the ion-implanted layer of the resist film undergoes severe hardening and shrinkage, resulting in numerous cracks on the resist film surface. The surface of the resist film that has not been ion-implanted is exposed from the crack surface, and as a result, the conventional dry etching method performed in the next process works extremely effectively on the resist film, completely removing the resist film. This design allows for easy peeling and removal.

〔Example〕

FIGS. 1 and 2 are schematic cross-sectional views of essential parts showing a resist film peeling method according to the present invention.

In FIG. 1, there is a substrate 11, and a resist film 1 is placed on top of the substrate 11.
It is assumed that boron (B), for example, is ion-implanted from the surface of the resist film in the direction indicated by the arrow in order to implant ions into the exposed substrate portion 13 of the opening.

The surface portion of the resist film into which such ions have been implanted is altered by the ion-implanted molecules, resulting in a thickness A that has the properties of the original resist film and a surface altered layer B.
There is a very clear distinction between the two parts, and it also follows the rate-limiting reaction in the reaction of resist removal by etching. The etching speed of B becomes slower.

The difference in the molecular structure between layer A and layer B is whether or not boron ions (B+) are coordinately bonded to the side chains of the photosensitizer. When a B+ ion coordinates to the benzene ring of the compound, its expansion coefficient usually becomes smaller than that before alteration.

When heating according to the present invention takes advantage of such chemical changes in the resist film, cresol novolac resin (
When heat of 200°C to 260°C, which is the temperature at which the benzene rings of a positive resist film begin to decompose (transition), is uniformly applied to parts A and B of the resist film, the difference in expansion coefficient causes Stress will be generated at the interface between the parts.

In addition, since the surface of part B of the resist film is in contact with the atmosphere due to the influence of ion implantation and ultraviolet rays, crosslinking is completed in this part, so when the resist film is heated, the surface of the resist film Cracks occur and portion A of the resist film is exposed. - FIG. 2 is a cross-sectional view showing a state in which cracks have occurred on the surface of the resist film due to heating of the resist film according to the present invention.

It can be seen that a large number of cranks D are generated in the B portion of the resist film, and the cranks have reached the A portion of the resist film.

As an example of the present invention, resist removal is performed in the following procedure.

(1) Ion implantation into the substrate.

(2) After ion implantation, the substrate was exposed to air for 200 minutes.
Heating at a temperature of 1 minute diameter from ℃ to 260℃. (The resist film transfers and generates cranks) (3) Microwave oxygen plasma etching (dry etching method) (4) Wet etching.

In this way, the resist film in which part B is cracked and part A is exposed is removed by a dry etching process performed after heating the substrate, but even though the dry etching is isotropic etching, the resist film is If there is a crank on the surface, the etching effect will appear on the boundary between parts A and B through the crank part, and the entire resist film will be etched, including parts A and B. The resist film can be removed by etching extremely easily.

〔Effect of the invention〕

As explained above in detail, the method of etching and stripping a resist film that has been ion-implanted according to the present invention can completely remove the resist film by adding an extremely simple step. This method has an extremely large effect in that high-quality products can be manufactured and defects occurring in the manufacturing process can be reduced.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of the main part for explaining the peeling and removal of the resist film according to the present invention, FIG. 2 is a perspective view of the main part for explaining the crank of the resist film of the present invention, and FIG. , ion-implanted resist in conventional method)
3151 is a cross-sectional view of a main part for explaining a method of etching and removing 3151. FIG. 4 is a plan view showing a state in which an ion-implanted resist film is etched in a conventional method. Resist film, 13
indicates the exposed part of the board, and indicates the exposed part of the board, respectively. Figure 2

Claims (1)

[Claims] When peeling off a resist film that has been ion-implanted, the resist film is heated to 200°C in the pre-ion etching process.
A method for peeling off a resist film, comprising a heating step of heating at a temperature of 260° C. to 260° C. to cause a transition in the resist film.