JPH01264227A - Removal of resist - Google Patents

Abstract

PURPOSE:To enhance the capacity to remove a resist by a method wherein a side face of a pattern of a film to be treated is etched slightly by an isotropic etching operation before or during a wet resist removal operation and an undenatured part hidden by a denatured layer of a resist pattern surface layer is exposed. CONSTITUTION:A resist-exfoliating solvent 5 cannot penetrate into the inside from a resist denatured layer 1; it penetrates into the inside from a part of an undenatured part 2 of a resist exposed by an isotropic etching operation of a side face of a pattern 3a of a film to be treated before or during a resist removal operation; it swells and dissolves the resist; a resist pattern is removed. When the film to be treated is a metal film such as Al, Al-Si or the like, this film can be etched by using an acid or an alkali. When, however, a strong acid such as sulfuric acid or the like is used, its dissolving power is higher to a metal than to the resist itself; accordingly, this acid is not suitable. As a resist-exfoliating liquid, an organic acid containing phenol or the like can be used in addition to an inorganic acid. Normally, this organic exfoliating solvent hardly displays corrosiveness to the metal; when a little water is added, this solvent displays the corrosiveness and simultaneously increases the exfoliating performance to the resist.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application J] This invention relates to a method for removing resist from a substrate.

[Conventional technology J] Conventional resist removal methods include dry processing using oxygen oxidation agents, etc., wet processing using inorganic or organic solvents, and a combination of dry processing and wet processing. Specifically, the resist, which is an organic substance, is ashed and turned into carbon dioxide and water, so the removal ability is high, but since the substrate is exposed to the defuma, the film to be processed is damaged by heat and attack by active species. Furthermore, this damage becomes more apparent and becomes a problem as the degree of integration of devices increases. In addition, since active species of oxygen attack the substrate, the exposed surface of the substrate is oxidized. On the other hand, wet processing does not cause physical damage to the substrate like dry processing, but its removal performance is inferior. With the shift to Icm, UV curing is being added to resist pattern formation, and defuma processing, especially reactive ion etching (hereinafter referred to as RIE), is being frequently used to remove errors. During these treatments, the resist is exposed to high-energy ultraviolet rays, heat, and active species attack, forming a degraded layer on the surface. The size of this altered layer varies depending on the processing conditions, but it is usually about several hundred times thicker. In this way,
The altered layer on the resist surface generated by UV curing treatment, R/E treatment, etc. is difficult to swell and dissolve in a resist stripping solvent, and the solvent does not penetrate into the resist pattern, making it difficult to remove the resist using a wet method.

[Problems to be Solved by the Invention] As described above, conventional resist removal methods do not remove the resist after UV curing or RI Efi treatment, which tends to be frequently used as the elements in the substrate become smaller. It was difficult to remove it without damaging the substrate.

This invention was made to solve the above problems, and aims to improve the removal ability of the conventional wet resist removal process by adding a simple pretreatment before the l/cyst removal process. do.

[Means to solve the problem]

In this invention, before or during the wet resist removal process,
By slightly etching the pattern side surface of the processed film that is in close contact with the resist pattern using an isotropic etching process, and by infiltrating the unaltered portion inside the resist pattern with a resist removal solvent during the wet resist removal process, The resist pattern whose surface layer has been altered and hardened is removed.

[Operation J] The purpose of etching the pattern side surface of the processed film that is in close contact with the resist pattern of this invention is to allow the resist removal solvent to penetrate and come into contact with the unaltered portion inside the resist pattern. The amount of etching must be at least equal to the thickness of the altered layer on the surface of the resist pattern. However, the thickness of the deteriorated layer is only a few thousandths of an inch, which is not a problem even when compared with the minimum pattern size of advanced devices.

The mechanism for improving the resist removal ability in this invention is that after selective etching by HIE, the pattern side surface of the film to be processed is slightly etched by isotropic etching, and then
The resist stripping solvent shown in Figure (b) cannot penetrate into the inside of the resist deteriorated layer by dipping it in a resist stripping solvent to remove the deteriorated layer on the resist surface that has occurred due to the previous process of UV curing treatment, R-E treatment, etc. First, it penetrates into the interior of the unaltered portion of the resist exposed by isotropic etching of the side surface of the film pattern to be processed, causing swelling and dissolution of the resist, leading to removal of the resist pattern.

[Example J An embodiment of the present invention will be described below with reference to the drawings.

Figure (a) is a cross-sectional view of the pattern after blowing selected errors by RIE, and Figure (b) is a state in which the pattern side surface of the processed film is slightly etched by isotropic etching and then immersed in a resist stripping solvent. FIG. In the figure, 1 is an altered layer on the resist surface caused by the previous UV curing treatment, RIE treatment, etc., 2 is the unaltered portion inside the resist pattern, 3a is the processed film pattern before isotropic etching treatment, 3b shows the pattern of the film to be processed after isotropic etching, 4 shows the substrate or underlayer, and 5 shows the movement of resist stripping solvent molecules.

→ As shown at 5 in Figure (b), the resist stripping solvent cannot penetrate into the interior of the resist deteriorated layer 1, and the resist stripping solvent cannot penetrate into the inside of the undegraded portion 2 of the resist exposed by isotropic etching of the side surface of the temporarily processed film pattern 3a. It penetrates into the interior, causes the resist to swell and dissolve, and leads to the removal of the resist pattern.

3a is the conventional state of the Al-8i pattern diagram (a), and when the resist is removed, the resist pattern swells slightly;
When the Al-8i pattern is slightly isotropically etched, the resist pattern is completely removed.

In the above embodiment, the side surface of the pattern of the film to be processed is subjected to isotropic etching treatment before the resist removal process, but there is no problem in performing this etching process during the resist removal process. When the film to be processed is a metal film such as A1 or Al-8i, etching is also possible with acid or alkali. However, the use of a strong acid such as sulfuric acid is unsuitable because its ability to dissolve metals is higher than that of the resist itself.

As the resist stripping solution, in addition to inorganic acids, there are organic acids containing the above-mentioned cyphenol, etc., and amine-based organic alkalis. These organic stripping solvents usually exhibit little corrosivity to metals, but by adding a small amount of water, they exhibit corrosivity and at the same time increase their stripping performance against resists.

Therefore, by performing resist removal processing using an organic acid or alkaline resist stripping solvent with a slight amount of water added, etching processing is performed on the pattern side surface of the metal film to be processed during the resist removal processing. The resist removal ability can be improved as in the embodiment.

[Effects of the Invention J As described above, according to the present invention, before or during the wet resist removal process, the side surface of the pattern of the processed film is slightly etched by isotropic etching process, thereby reducing the deterioration of the surface layer of the resist pattern. By exposing the unaltered portions hidden in the layer, the resist stripping solvent can smoothly penetrate into the resist. As a result, the surface layer is altered by UV curing or RIE treatment, and the resist, which was conventionally difficult to remove, can be easily removed without damaging the substrate or underlying layer.

[Brief explanation of the drawing]

The figure shows an embodiment of the resist removal method of the present invention, in which figure (a) is a cross-sectional view of the pattern after removing selective errors by RIE, and figure (b) is a pattern side surface of the film to be processed is etched by isotropic etching. FIG. 3 is a schematic cross-sectional view showing a state in which the resist stripping material is immersed in a resist stripping solvent after being slightly etched. In the figure, 1 is a degraded layer on the resist surface caused by UV curing in the previous process, R/E treatment, etc., 2 is an unaltered portion inside the resist pattern, and 3a is the processed film before isotropic etching. 3b shows the pattern of the film to be processed after isotropic etching, 4 shows the substrate or underlayer, and 5 shows the movement of resist stripping solvent molecules. In addition, in the figures, the same reference numerals indicate the same parts.

Claims (1)

[Claims] (1) In a resist removal method in which a resist is patterned on a substrate to be processed and the film to be processed is selectively etched by plasma treatment, the resist is removed. A resist removal method characterized in that the pattern side surface of a film to be processed is slightly etched by an isotropic etching process to facilitate removal during a wet resist removal process.