JPH0473611B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for forming fine patterns, and in particular to an etching mask made of a styrene polymer film, which has even better plasma resistance than conventional photoresist films, as a plasma etching mask. It is related to the application to

[Prior Art] FIGS. 2a, 2b, and 2c show examples of conventionally used plasma etching-resistant masks. Figure 2a
In this example, a single layer photoresist film pattern 20 is used as an etching mask. To explain the method of forming this mask, first, a photoresist film (not shown) is formed on the film to be etched 1, and a photoresist film pattern 20 is formed on this photoresist film using photolithography. FIG. 2b shows an upper silicon-based photoresist film pattern 22 and a lower layer photoresist film pattern 21.
The two-layer film pattern is used as an etching mask. To explain the method for forming this mask, first, a lower layer photoresist film (not shown) is formed on the film to be etched 1, and an upper layer silicon-based photoresist film (not shown) is formed on this lower layer photoresist film. do. Thereafter, an upper silicon-based photoresist film pattern 22 is formed on this upper-layer silicon-based photoresist film using photolithography, and this upper-layer silicon-based photoresist film pattern 2 is
2 as a mask, the lower photoresist film is plasma etched to form the lower photoresist film pattern 2.
form 1. FIG. 2c shows the inorganic film pattern 23.
A two-layer film pattern consisting of a lower photoresist film pattern 21 and a lower photoresist film pattern 21 is used as an etching mask. To explain the method of forming this mask, first, a lower photoresist film (not shown) is formed on the film to be etched 1, an inorganic film (not shown) is formed on this photoresist film, and this inorganic film is An upper photoresist film (not shown) is formed thereon. Thereafter, the upper layer photoresist film is etched to form an upper layer photoresist film pattern (not shown), and the inorganic film is etched using this upper layer photoresist film pattern as a mask to form an inorganic film pattern 23. Membrane pattern 23
Using the mask as a mask, the lower photoresist film is plasma etched to form the lower photoresist film pattern 21.
form.

[Problems to be Solved by the Invention] Since the conventional plasma-resistant etching mask is formed as described above, in the case of the single-layer pattern mask shown in FIG. At times, the photoresist, which is a mask material, is prone to film thinning, causing many problems when forming fine patterns. In addition, in the case of the mask with the two-layer film pattern shown in FIGS. 2b and 2c, the upper layer silicon-based photoresist film pattern 22 and the inorganic film pattern 23 are
However, there were problems such as poor adhesion with the lower photoresist film pattern 21, resulting in pattern defects during formation of fine patterns.

This invention was made to solve the above-mentioned problems, and it is possible to change the surface of the lower photoresist film from the conventional method of forming an inorganic film pattern or an upper silicon-based photoresist film pattern on the lower photoresist film. By changing the method to a method of forming a polymer film pattern having plasma resistance on the lower photoresist film after activation, a method that can easily form a fine pattern without causing pattern defects is obtained. The purpose is to

[Means for Solving the Problems] The fine pattern forming method according to the present invention is a fine pattern forming method using a two-layer film including a resist film as an etching mask, in which a first resist film is formed on a film to be etched. a step of forming;
A step of forming a polymer film mainly composed of styrene and having plasma resistance on the first resist film, a step of forming a second resist film in a predetermined area on the polymer film, and a step of masking the second resist film. a step of patterning the polymer film by etching the polymer film as a mask; a step of patterning the first resist film by etching the first resist film using the patterned polymer film and the second resist film as a mask; 2, removing the resist film.

[Function] In the fine pattern forming method according to the present invention, the second layer of a polymer film mainly composed of styrene and having plasma resistance allows the first resist film of the first layer to be bonded to the second resist film of the first layer. An etching mask consisting of a two-layer film having good adhesion to the polymer film and excellent plasma etching resistance is formed.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. FIGS. 1A, B, and C are cross-sectional views showing the main process steps of a fine pattern forming method according to an embodiment of the present invention. To explain this method, a lower photoresist film 2 is formed on a film 1 to be etched. Thereafter, this is placed in a vacuum chamber, and the surface of the lower photoresist film 2 is irradiated with inert gas plasma or the like to activate this surface. Thereafter, a polymeric film 3 made of, for example, polystyrene is formed on the lower photoresist film 2, which has plasma resistance when plasma etching the underlying film 1 to be etched. After this, an upper layer photoresist film (not shown) is again formed on the polymeric film 3, and a desired upper layer photoresist film pattern 40 is formed on this upper layer photoresist film using a photolithographic technique [Fig. A]. After this, upper layer photoresist film pattern 4
0 as an etching mask, the underlying polymeric film 3 is wet or dry etched to form a polymeric film pattern 30 [FIG. 1B]. After this, the upper layer photoresist film pattern 40 and the polymer film pattern 30
Using this as an etching mask, the lower photoresist film 2 below the lower photoresist film 2 is etched using a dry etching technique to form a lower photoresist film pattern 21. At this time, the upper photoresist film pattern 40 is removed at the same time as the lower photoresist film 2 is etched [FIG. 1C]. The etching mask consisting of the two-layer film pattern formed in this way has excellent plasma etching resistance and good adhesion between the polymer film pattern 30 and the lower photoresist film pattern 21.
Excellent for forming fine patterns.

In addition, in the above example, the case where the polymer film is made of polystyrene etc. is shown, but the polymer film made of polystyrene etc. contains impurities such as silicon or aluminum in an amount of several to several tens of percent in order to improve plasma resistance. In this case as well, the same effects as in the above embodiment can be achieved.

[Effects of the Invention] As described above, according to the present invention, in a fine pattern forming method using a two-layer film including a resist film as an etching mask, the second layer is made of a polymer containing styrene as a main component and having plasma resistance. By forming a film, an etching mask consisting of a two-layer film with good adhesion between the first resist film as the first layer and the polymer film as the second layer and excellent plasma etching resistance properties can be created. As a result, pattern defects in the etching mask can be effectively prevented from occurring when a film to be etched is plasma-etched using the etching mask, and a fine pattern can be easily formed.

[Brief explanation of the drawing]

FIGS. 1A, B, and C are cross-sectional views showing the main process steps of a fine pattern forming method according to an embodiment of the present invention. Figures 2a, b, and c are examples of conventionally used plasma-resistant etching masks. Figure 2a is an etching mask consisting of a single layer film pattern, and Figures 2b and c are examples of a two-layer etching mask. FIG. 3 is a diagram showing an etching mask consisting of a film pattern. In the figure, 1 is a film to be etched, 2 is a lower photoresist film, 21 is a photoresist film pattern, 3 is a polymer film, 30 is a polymer film pattern, and 40 is an upper photoresist film pattern. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. A fine pattern forming method using a two-layer film including a resist film as an etching mask, comprising: forming a first resist film on a film to be etched; and on the first resist film. forming a polymer film containing styrene as a main component and having plasma resistance; forming a second resist film in a predetermined region on the polymer film; and using the second resist film as a mask to form a polymer film having plasma resistance. patterning the polymer film by etching the patterned polymer film and the second polymer film;
A method for forming a fine pattern, comprising the steps of patterning the first resist film and removing the second resist film by etching the first resist film using the resist film as a mask. 2. The method for forming a fine pattern according to claim 1, wherein the polymer film contains impurities to improve plasma resistance. 3. The fine pattern forming method according to claim 2, wherein the impurity is silicon or aluminum.