JPS6310824B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for processing or modifying a mask pattern of a photomask in an integrated circuit manufacturing process using a mask protective agent (release film).

Photomasks used in the integrated circuit manufacturing process are generally 10.2 cm to 12.7 cm (4 to 5 inches) square in size, but it has been found that pinholes and other scratches occur on the masks during use. It may be necessary to process or modify the pattern due to design changes or design changes.

Conventionally, such pattern processing and modification has been carried out using a photoresist film and a metal such as chromium for forming a mask pattern.

FIG. 1 is a plan view showing part of a mask pattern made on a glass plate. In the figure, a shows the original form of the pattern, b and c show the case where the pattern has a flaw A such as a pinhole, and d shows the case where a new pattern B is added.

Hereinafter, the prior art and the present invention will be explained with reference to the case of adding the mask pattern d. This is because pattern modification is performed in the same manner as addition.

FIG. 2 shows a method of adding a photomask pattern in the prior art in a cross-sectional view. In the same figure, chromium (Cr) is placed on the glass plate 1, which is the mask plate.
It is assumed that a new pattern 3 is added to the pattern 2 made of the film. To do this, first of all,
A photoresist film 4 is applied from above the mask pattern, and partial exposure is performed on the additional pattern using a partial exposure device (indicated by the arrow a in the figure). After that, the mask plate (glass plate) is immersed in an alkaline solution, and the exposed area is exposed. is removed by wet etching.
Next, a chromium film (Cr) 5 is deposited by vapor deposition or sputtering (see figure b), followed by treatment with an alkaline solution or acetone solution to remove unnecessary resist films and chromium films (lift-off). Figure c). It should be noted that the difference in film thickness of the additional mask shown in FIG.

By the way, in the step shown in Fig. 2c, the mask plate is next immersed in an alkaline solution or an acetone solution.
When removing excess resist film and chromium film, it has been confirmed that once dissolved chromium adheres to the mask plate again. This adhered chromium disturbs the mask pattern as shown at 10 in FIG. 3, and has the problem that it cannot be easily removed by washing with water or the like. This chromium, present in the tens to hundreds per plate, requires another etching or ion treatment to remove it, adding additional time and effort to the integrated circuit manufacturing process.

The purpose of the present invention is to solve the above-mentioned problem of chromium re-deposition in the process of processing and correcting mask patterns, and in order to solve this problem, the inventor of the present invention has developed a method that does not use a resist film, and moreover, replaces the chromium film with alkali. We have developed a method for additionally modifying mask patterns that does not require a process of dissolving with a solution. That is, instead of the resist film in the conventional technology, a stripper film (release film as a mask protectant) made of vinyl acetate or the like is applied.
A window is opened in the release film at the position of the pattern to be added, and then a chrome film is applied. Unnecessary chromium film can be easily removed by peeling off the release film.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 4 is a diagram showing the main parts of the mask plate in the implementation step of the method of the present invention. In FIG. 1A, chromium 2 is coated on a mask plate (glass plate) 1 as a mask pattern. Now consider the case where a mask pattern is added to the position shown by 3. First, remove the release film (mask protectant) 11 made of vinyl acetate material by 100 ml.
Apply to a thickness of [μm] (a in the same figure). Next, a window is opened at the pattern addition position by laser irradiation as shown by the arrow in the figure. The laser irradiation energy at this time is sufficient if only the peeling film can be removed, and the laser used is a neodymium argon (Nd-Ar) laser. Next, chromium is applied to a thickness of 800 Å by vapor deposition or sputtering to form a chromium film 5 (FIG. 5b). Thereafter, when the release film is peeled off, a mask pattern with the desired pattern added thereto is completed as shown in FIG.

The release film can be easily removed as follows. That is, in figure b,
The thickness of the applied chromium film 5 becomes thinner at the ends of the mask plate 1. Taking advantage of this fact, the release film can also be removed in one piece by applying adhesive tape or the like to the area and peeling it off. Moreover, since the adhesiveness between chrome and glass is strong, the chrome mask pattern will not be peeled off at the same time when the release film is peeled off. As a result, it becomes possible to add a mask pattern as shown in FIG. Also, when removing the release film, the top surface of the added mask pattern part will be
Although it is disturbed, its function as a mask that blocks light is not affected.

As explained above, according to the method of the present invention,
Unlike conventional methods using wet etching, the chromium that has been dissolved in an alkaline solution during the etching process re-adheres to the mask plate, and there is no need to remove it, making it possible to make additional corrections to the mask pattern. Integrated circuit manufacturing. Process efficiency can be improved.

In the above description, laser irradiation was used to open the release film, but such window opening can also be performed using other energy rays. Furthermore, although a vinyl acetate-based material is used as the mask protective agent, other adhesive materials may also be used. Therefore, the scope of the present invention is not limited to the use of the specific treatments or materials described above, but is also applicable to cases where other treatments or materials are used.

[Brief explanation of the drawing]

Figure 1 is a plan view showing the mask pattern on the mask plate, Figure 2 is a cross-sectional view of the main part of the mask plate during the mask pattern addition correction process in the conventional method, and Figure 3 shows chromium fragments attached to the mask plate. FIG. 4 is a cross-sectional view showing the main part of the mask in the step-by-step process of adding and correcting the mask pattern in the method of the present invention. 1...Mask plate (glass plate), 2...Chromium film, 3...Mask pattern addition position, 3'...
...Additional chromium film, 4...Resist film, 5...Chromium film, 10...Adhered chromium film, 11...Film.

Claims (1)

[Claims] 1. In a method of processing or modifying a mask pattern of a photomask in an integrated circuit manufacturing process, a step of applying a mask protective agent (adhesive) made of vinyl acetate or the like onto a mask plate on which the pattern is formed; A process of opening windows in the area corresponding to the pattern correction position of the protective agent using energy beam processing, a process of applying chromium (Cr) on the protective agent by vapor deposition or sputtering, and then peeling off the mask protective agent from the mask plate surface. A pattern processing method characterized by consisting of the following.