JP2004335774A - Method for forming resist pattern, and method for forming wiring pattern - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming a high precision micro resist pattern coping with the high performance of an electronic component, and to provide a method for forming a wiring pattern. <P>SOLUTION: At least one resist layer is formed on a substrate 1. A mold having a reverse tapered sidewall at a protrusion corresponding to a pattern being formed is pressed against the resist layer to form a resist pattern 4 where the sidewall corresponding to the protrusion has a reverse tapered recess. A wiring pattern is formed by a lift-off method using the resist pattern 4 thus formed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for forming a fine pattern, in particular, a method for forming a resist pattern and a method for forming a wiring pattern formed on a ceramic substrate or a semiconductor substrate by using an imprint method.
[0002]
[Prior art]
2. Description of the Related Art In recent years, with the development of mobile phones and mobile communication, a surface acoustic wave element having a desired metal film pattern formed on a piezoelectric substrate has been actively used as a surface acoustic wave filter or a surface acoustic wave resonator. In order to cope with higher frequencies in the surface acoustic wave element, it is necessary to make the metal film thinner and to make the metal film pattern finer.
[0003]
As a method for forming this fine metal film pattern, a pattern forming method using a photolithography technique is generally developed.
[0004]
On the other hand, the photosensitive resist applied to the substrate is exposed through a predetermined photomask and developed to form a fine resist pattern, and then a metal film is formed on the substrate and the formed fine resist pattern. There is a method of forming a fine metal film pattern called a lift-off method of removing an unnecessary metal film by forming and then removing the photosensitive resist with a solvent or the like.
[0005]
However, these techniques using the photolithography technique have a problem that expensive equipment is required from the process.
[0006]
Therefore, as a method of forming a fine pattern, a mold having an uneven pattern formed thereon is pressed on a resist film formed on a substrate, and the uneven pattern of the formed resist is irradiated with ultraviolet rays. A manufacturing method for forming a resist pattern by selectively forming a modified portion and a non-modified portion has been proposed (for example, see Patent Document 1).
[0007]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2002-158192
[Problems to be solved by the invention]
However, the above-described conventional technique for forming a fine pattern has the following problems.
[0009]
In Patent Document 1, as shown in FIG. 5, a resist layer 12 that is modified by irradiation with ultraviolet light is formed on a substrate 11. Next, a resist layer 13 that is easy to mold is formed on the resist layer 12 by pressing. Next, a concave portion corresponding to the convex portion is formed in the resist layer 13 by pressing a mold having the convex portion.
[0010]
Next, by irradiating the formed pattern having the concave portion with ultraviolet light, the ultraviolet ray is transmitted through the concave portion 14 of the resist layer 13, and the denatured portion 15 is generated in the lower resist layer 12. On the other hand, the lower layer of the resist layer 13 other than the concave portion 14 becomes the non-denatured portion 17 without reaching the ultraviolet rays.
[0011]
Then, after the resist layer 13 is removed by wet etching, the denatured portion 15 of the resist layer 12 is removed by wet etching.
[0012]
As described above, the non-denatured portion 17 remains on the substrate 11, and a resist pattern is formed.
[0013]
However, the formation of the non-denatured portion by this UV irradiation has the problem that the shape of the non-denatured portion formed is not stable due to the influence of the unevenness of the shape of the previously formed uneven resist pattern and the influence of the UV irradiation. Have.
[0014]
This has a problem that the shape of the resist pattern formed after the unnecessary resist is removed by wet etching is not stable.
[0015]
In forming a metal film pattern by the lift-off method, stability of the shape of the resist pattern is important, and as a result, there is a problem that it is difficult to form a stable metal film pattern.
[0016]
[Means for Solving the Problems]
In order to solve the above problem, a method for forming a resist pattern according to the present invention includes a step of preparing a substrate, a step of forming at least one resist layer on the substrate, and a convex portion corresponding to the pattern to be formed on a mold surface. Pressing the mold against the resist layer to form the resist layer so as to include a concave portion corresponding to the convex portion.
[0017]
Furthermore, the side wall of the concave portion formed in the resist layer has an inverse tapered shape by forming the side wall of the convex portion of the mold into an inversely tapered shape.
[0018]
In forming a resist layer on a substrate, at least the substrate side first resist layer is formed of a material having a relatively high etching rate, and the surface layer side second resist layer is formed of a material having a relatively low etching rate. And a step of forming a resist layer having an inversely tapered side wall of the concave portion by etching so that the side wall of the concave portion has an overhang shape.
[0019]
Further, the first resist layer is made of a polyimide resin, and the second resist layer is made of a phenol resin.
[0020]
The method for forming a wiring pattern according to the present invention includes a step of forming a wiring pattern on a substrate by a lift-off method using the resist pattern formed by the above-described method for forming a resist pattern. This is a method of forming a wiring pattern.
[0021]
According to the manufacturing method of the present invention, it is possible to form a highly precise fine resist pattern and a wiring pattern corresponding to high performance of an electronic device without significantly increasing the manufacturing cost.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0023]
FIG. 1 shows a schematic process flow of one embodiment of the method for forming a resist pattern according to the present invention.
[0024]
First, as shown in FIG. 1A, a resist layer 2, for example, a layer made of polymethylglutarimide which is a polyimide-based thermoplastic resin is formed on a substrate 1. The resist layer 2 is formed by applying polymethylglutarimide to the substrate 1 using a spin coater or the like so that the film thickness becomes 0.4 μm. It is formed by heating for 60 seconds on a hot plate heated to ℃ and drying.
[0025]
Next, as shown in FIG. 1B, while the substrate 1 on which the resist layer 2 is formed is heated on a hot plate, a mold 3 having a convex portion corresponding to a pattern to be formed is placed on the resist layer 2 side. Press from. As the pressing conditions at this time, it is preferable to set the heating temperature to 130 ° C., the pressing pressure to 100 MPa, and the pressing time to 5 minutes. Here, the convex shape of the mold 3 is such that the side wall is formed in an inversely tapered shape.
[0026]
In addition, the shape of the protrusion is set to a shape in which the tip of the protrusion reaches the substrate 1 in consideration of the resist film thickness. Further, at the time of pressing, the pressing is performed in a state where the substrate 1 is not damaged.
[0027]
Next, after cooling to room temperature, the mold 3 is peeled from the resist layer 2. As shown in FIG. 1 (c), the resist layer 2 pressed by the mold 3 was formed so that the side wall of the concave portion followed the convex portion having the side wall of the reverse taper shape of the mold 3 so as to have a reverse taper shape. A resist pattern 4 is formed.
[0028]
Next, FIG. 2 shows a schematic process flow of another embodiment of the method for forming a resist pattern of the present invention.
[0029]
First, as shown in FIG. 2A, a resist layer 5 which is a first resist layer having a relatively high etching rate on a substrate 1 is made of, for example, polymethylglutarimide which is a polyimide-based thermoplastic resin. Form a layer. The resist layer 5 is formed by applying polymethylglutarimide to the substrate 1 using a spin coater or the like so that the film thickness becomes 0.2 μm. It is formed by heating for 60 seconds on a hot plate heated to ℃ and drying.
[0030]
Next, after cooling to room temperature, a resist layer 6 which is a second resist layer having a relatively low etching rate on the resist layer 5, for example, a phenolic resin having an etching resistance of Fi-SP2 (Fuji Film Arch) Is formed. The resist layer 6 is formed by applying Fi-SP2 onto the resist layer 5 using a spin coater or the like so that the film thickness becomes 0.2 μm. It is formed by heating for 60 seconds on a hot plate heated to ℃ and drying. Thus, a resist layer 7 having a two-layer structure is formed on the substrate 1.
[0031]
Next, as shown in FIG. 2B, in a state where the substrate 1 on which the resist layer 7 is formed is heated on a hot plate, the mold 3 having a convex portion corresponding to the pattern to be formed is placed on the resist layer 7 side. Press from. As the pressing conditions at this time, it is preferable to set the heating temperature to 130 ° C., the pressing pressure to 100 MPa, and the pressing time to 5 minutes. Here, the convex portion of the mold 3 is formed in a reverse tapered shape. The shape of the convex portion of the mold 3 is set to a shape in which the tip of the convex portion reaches the substrate 1 in consideration of the resist film thickness.
[0032]
Next, after cooling to room temperature, the mold 3 is peeled off from the resist layer 7. As shown in FIG. 2 (c), the resist layer 7 pressed by the mold 3 had a concave side wall shaped like an inverse taper following the convex part having an inversely tapered side wall of the mold 3. A resist pattern 8 is formed.
[0033]
Next, as shown in FIG. 3, the formed resist pattern 8 may be subjected to an etching process to form a resist pattern 9 in which the side wall of the concave portion has an overhang shape.
[0034]
The resist pattern 9 can be formed by, for example, performing RIE processing on the resist pattern 8 formed on the substrate 1 shown in FIG.
[0035]
The details of the RIE processing conditions will be described below (not shown). For the contents, reference numerals shown in FIGS. 2 and 3 are used.
[0036]
The substrate 1 on which the resist pattern 8 has been formed is set in a vacuum device having a desired function. Next, 90 sccm of O ₂ is introduced as an ashing gas into the vacuum apparatus, and the back pressure is controlled to 300 mtorr. The input power is set to 100 W, and the RIE process is performed for about 180 seconds. In the resist pattern 8, the first resist layer 5 is made of a polyimide resin, and the second resist layer 6 is made of a phenol resin. Thereby, the first resist layer 5 shows a larger etching rate as compared with the second resist layer 6. As a result, as shown in FIG. 3, the resist pattern 8 subjected to the RIE process has a resist pattern 9 in which the side wall of the concave portion in which the resist layer 5 on the substrate side is further etched has an overhang shape.
[0037]
As described above, the resist pattern 9 in which the side wall of the concave portion has an overhang shape is formed on the substrate 1.
[0038]
Another example of a method for forming a resist pattern in which the side wall of the concave portion has an overhang shape will be described below (not shown). For the contents, reference numerals shown in FIGS. 2 and 3 are used.
[0039]
By subjecting the resist pattern 8 formed on the substrate 1 to wet etching, it is possible to form a resist pattern 9 in which the side wall of the concave portion has an overhang shape.
[0040]
First, the substrate 1 provided with the resist pattern 8 is immersed in an alkaline solution and rocked. At this time, it is preferable to use a 2.38 wt% teolamethylammonium hydroxide solution as the alkaline solution, and set the immersion time to 120 seconds. The resist pattern 8 includes a polyimide resin for the first resist layer 5 and a phenolic resin for the second resist layer 6. Thereby, the first resist layer 5 shows a larger etching rate as compared with the second resist layer 6. As a result, in the resist pattern 8 that has been subjected to the wet etching, a resist pattern 9 is formed in which the side walls of the concave portions are overhanging as shown in FIG.
[0041]
At this time, it is preferable to select a solution that causes less damage to the substrate 1 as the alkaline solution to be used.
[0042]
As described above, the resist pattern 9 in which the side wall of the concave portion has an overhang shape is formed on the substrate 1.
[0043]
In addition, it is possible to correct variations in the shape and dimensions of the resist in the concave portion of the reverse taper formed by pressing, by this etching process. Even if the resist layer remains under the concave portion of the resist layer, the removal can be performed by the above-described etching process.
[0044]
Further, the formation of the overhang shape on the side wall of the concave portion of the resist pattern 9 can be performed by combining the above-described embodiments. After the unnecessary resist is removed by the RIE process, an overhang shape can be formed by a wet etching process. For these, appropriate etching processing conditions are set according to the state of the resist pattern 8 pressed by the mold 3.
[0045]
Further, the resist pattern 9 may be composed of three or more resist layers. At this time, a resist layer is formed in which the side wall of the concave portion has an overhang shape based on the resist layer on the substrate side.
[0046]
Next, FIG. 4 shows a schematic process flow of one embodiment of the wiring pattern forming method of the present invention.
[0047]
First, FIG. 4A shows a substrate 1 provided with a resist pattern 8 having an inversely tapered side wall on the substrate 1. At this time, if the surface of the substrate 1 is contaminated, cleaning may be performed at this stage.
[0048]
Next, as shown in FIG. 4B, a metal film 10 is formed on the substrate 1 including the resist pattern 8 by vapor deposition from the resist pattern 8 side.
[0049]
The formation of the metal film 10 is performed, for example, by setting the substrate 1 on which the resist pattern 8 is formed in a vacuum evaporation apparatus having a crucible for multi-source.
[0050]
Next, the inside of the vacuum deposition apparatus is brought into a vacuum state by a vacuum pump. At this time, it is preferable to evacuate the inside of the vacuum evaporation apparatus to a pressure of the order of 10 ⁻⁵ Pa using a high vacuum pump.
[0051]
Next, a metal film 10 is formed on the substrate 1 including the resist pattern 8 by an electron beam evaporation method. At this time, it is preferable that the substrate 1 revolves at a speed of 5 rpm so as to obtain a uniform film thickness distribution. A shutter is provided above the crucible, and is controlled by opening and closing so as to have a predetermined film thickness.
[0052]
Next, as shown in FIG. 4C, the resist pattern 8 and the unnecessary metal film 10 formed on the resist pattern 8 are peeled off. The resist pattern 8 and the unnecessary metal film 10 are removed by removing the resist pattern 8 by immersing and swinging in an organic solvent and removing the unnecessary metal film 10. At this time, since the resist pattern 8 has an inversely tapered side wall, the metal film 10 on the substrate 1 and the unnecessary metal film 10 on the resist pattern 8 are discontinuously formed. Therefore, the metal film 10 serving as a wiring pattern having a good quality state is formed on the substrate 1 without being affected by the removal of the resist pattern 8. Further, since the resist layer 5 on the substrate side of the resist pattern 8 is made of a polyimide-based thermoplastic resin, it can be easily peeled off.
[0053]
As described above, a method for forming a fine resist pattern can be provided by the method for forming a resist pattern by combining the imprint method and the etching treatment of the present invention. Further, it is possible to provide a method for forming a high-precision wiring pattern corresponding to higher performance of an electronic device using the resist pattern.
[0054]
【The invention's effect】
According to the method for forming a resist pattern and a wiring pattern of the present invention as described above, a high-precision fine resist pattern and a wiring pattern corresponding to high performance of an electronic device can be formed without significantly increasing the manufacturing cost. be able to.
[Brief description of the drawings]
FIG. 1 is a schematic process flow chart showing one embodiment of a method for forming a resist pattern according to the present invention.
FIG. 2 is a schematic process flow chart showing another embodiment of the method for forming a resist pattern according to the present invention.
FIG. 3 is a schematic sectional view of a substrate showing one embodiment of the forming of the method for forming a resist pattern according to the present invention.
FIG. 4 is a schematic process flow chart showing one embodiment of a method for forming a wiring pattern according to the present invention.
FIG. 5 is a schematic sectional view of a resist pattern formed by a conventional technique.
Reference numerals 1, 11, substrate 2, 5, 6, 7, 11, 12, 13 resist layer 3, mold 4, 8, 9 resist pattern 10, metal film 14, concave portion 15, modified portion 16, convex portion 17, non-conductive Denature part

Claims (4)

Preparing a substrate;
Forming at least one resist layer on the substrate,
Pressing a mold having a convex portion corresponding to the pattern to be formed on the mold surface on the resist layer, and forming the resist layer to include a concave portion corresponding to the convex portion,
A method of forming a resist pattern, wherein a side wall of a concave portion formed in the resist layer has an inversely tapered shape by forming a side wall of a convex portion of the mold into an inversely tapered shape. In forming a resist layer on the substrate, at least the substrate side first resist layer is formed of a material having a relatively high etching rate, and the surface layer side second resist layer is formed of a material having a relatively low etching rate. Process and
Forming the resist layer having an inversely tapered side wall by etching so that the side wall of the concave portion has an overhang shape by an etching process. . The method according to claim 2, wherein the first resist layer is made of a polyimide resin, and the second resist layer is made of a phenol resin. 4. A method for forming a wiring pattern, comprising: using a resist pattern formed by the method for forming a resist pattern according to claim 1, forming a wiring pattern on the substrate by a lift-off method.

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