JP2009044025A - Pattern forming method for polyimide resin film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming an appropriate pattern of a polyimide resin film without changing any process condition. <P>SOLUTION: A photoresist 3 is formed on a polyimide resin film. Then, the photoresist 3 is exposed so as to form the pattern having a plurality of windows 32 divided by bridges 31 at a position corresponding to an opening pattern of the polyimide resin film in the photoresist 3. Subsequently, the development of the photoresist 3 and the etching of the polyimide resin film are performed at a time by using the same liquid, and parts of the polyimide resin film to be supreimposed on the bridges 31 in the photoresist 3 are isotropically etched so as to form the opening pattern. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for forming a pattern of a polyimide resin film as a protective film of a semiconductor device, for example.

  Since a polyimide resin film is chemically stable and easy to form, it is generally used as a protective film for semiconductor devices. The polyimide resin includes a photosensitive polyimide resin in which the resin itself has photosensitivity and a non-photosensitive polyimide resin in which the resin itself does not have photosensitivity. Photosensitive polyimide resin is convenient, but it is expensive, and non-photosensitive polyimide resin is often used because of operational demerits such as requiring a special etching solution.

  An example of a forming method when a non-photosensitive polyimide resin is used for the protective film will be described below. First, a polyimide resin film having a desired film thickness is applied and formed on a wafer by a spin coating method, and imidized by performing a heat treatment at about 200 ° C. Next, in order to process into a desired pattern, a photoresist is similarly formed by the spin coating method, and then the photoresist is exposed using a mask and developed with an alkaline solution. At this time, the polyimide resin film is also etched and removed by the alkaline solution simultaneously with the photoresist exposed through the opening of the mask. Thereafter, the unexposed areas of the photoresist that are no longer needed are removed with a solution such as butyl acetate.

  The polyimide resin film is etched at the same time as the development of the photoresist. However, since the polyimide resin film has a very high solubility in an alkaline solution as a developer, the lateral direction of the polyimide resin film is at the opening pattern edge. The etching shift is very large, and the cross-sectional shape of this photoresist becomes a bowl shape as shown in FIG.

  That is, as shown in FIG. 4, the polyimide resin film 2, the photoresist 103, and the mask 104 are sequentially formed on the upper surface of the semiconductor device 1, and the polyimide resin film 2 is larger than the hole 130 a of the photoresist 103. Etching is performed to have an opening pattern.

  As shown in FIGS. 4 and 5, the inner peripheral portion of the hole 130a of the photoresist 103 is formed in a bowl shape. In FIG. 4, the hook-shaped portion indicates a portion surrounded by a solid line frame A, and in FIG. 5, a portion surrounded by a two-dot chain line frame B.

  FIG. 5 shows a plan view of the pattern of the photoresist 103, and the opening pattern of the final polyimide resin film is indicated by a dotted frame C. FIG. A portion between the dotted frame C and the inner peripheral surface of the hole 130a is a portion formed in a bowl shape by etching.

  This wrinkled portion is broken and torn during development, by the water flow during subsequent washing or by centrifugal force during rotary drying, etc. There is a case.

  That is, when a polyimide resin film is used as a protective film of a semiconductor device, the opening pattern of the polyimide resin film is usually a bonding pad portion, so the shape is often a square as shown in FIG. The size is as large as about 100 μm, and the saddle-like portion of the photoresist is in a state of being easily broken.

  In view of this, a method for suppressing the occurrence of the wrinkled portion of the photoresist is proposed in, for example, Japanese Patent Application Laid-Open No. 2002-268236 (Patent Document 1).

The contents are the following three methods.
Method 1. Increase the amount of exposure of the photoresist to create a weakly exposed area around the etched area.
Method 2. The resist sensitivity is increased by reducing the resist thickness to 0.2 μm to 0.6 μm.
Method 3. Increase bake temperature.

The lateral etching shift of the photoresist is increased by the above methods 1 and 2, and the lateral etching shift of the polyimide resin film is decreased by the above method 3. In either case, the difference in the lateral etching shift amount between the photoresist and the polyimide resin film is reduced to make it difficult to form a hook-like portion of the photoresist.
JP 2002-268236 A

  However, in the above conventional method, when used as a surface protective film, the polyimide resin film thickness is often set to 3 μm or more in consideration of the level difference of the base, and the resist film thickness cannot be reduced as in the above method 2. . When the photoresist is thick, the weakly exposed region does not reach the entire photoresist even if overexposure is performed as in Method 1 above. Further, when the baking temperature is increased and the etching rate of the polyimide resin film is lowered as in the above method 3, the etching time is significantly increased in the thick polyimide resin film, and the adhesion with the photoresist is reduced and the throughput is reduced. There is concern about the decline.

  Therefore, an object of the present invention is to provide a method for forming an appropriate pattern of a polyimide resin film without changing any process process conditions.

In order to solve the above problems, the polyimide resin film pattern forming method of the present invention is:
Forming a photoresist on the polyimide resin film;
Exposing the photoresist so as to form a pattern having a plurality of windows partitioned by bridges at positions corresponding to the opening pattern of the polyimide resin film in the photoresist;
The development of the photoresist and the etching of the polyimide resin film are performed at the same time using the same liquid, and the portion of the polyimide resin film overlapping the bridge portion of the photoresist is etched isotropically, And a step of forming an opening pattern.

  According to the polyimide resin film pattern forming method of the present invention, a pattern having a plurality of windows partitioned by bridges is formed at a position corresponding to the opening pattern of the polyimide resin film in the photoresist. The photoresist is exposed, the development of the photoresist and the etching of the polyimide resin film are performed at the same time using the same liquid, and the portion of the polyimide resin film that overlaps the bridge portion of the photoresist is also the same. Since the opening pattern is formed by etching, the portion corresponding to the opening pattern of the polyimide resin film in the photoresist is formed into a bowl shape by developing the photoresist and etching the polyimide resin film. Even if left, the photoresist has a pattern having a plurality of windows partitioned by a bridge. Since the formation, and during development, such as by subsequent centrifugal force during water flow and spin drying of washing, the eaves-like portion is not Ika flying broken, thereby preventing a pattern defect of a polyimide resin film.

  Further, the photoresist can be formed by changing only the mask pattern without changing any process process conditions so that the bowl-shaped portion of the photoresist does not break and fly.

  Moreover, since the polyimide resin film under the bridge portion of the photoresist can also be removed by lateral etching, the pattern finish of the polyimide resin film is the same as the conventional one.

  In the polyimide resin film pattern forming method of one embodiment, the width of the bridge portion of the photoresist is not more than twice the thickness of the polyimide resin film.

  According to the pattern forming method of the polyimide resin film of this embodiment, the width of the bridge portion of the photoresist is not more than twice the thickness of the polyimide resin film, so that it is below the bridge portion of the photoresist. The polyimide resin film can be reliably removed by a lateral shift by etching.

  In the polyimide resin film pattern forming method of one embodiment, the photoresist has a plurality of bridge portions, and the plurality of bridge portions are arranged substantially parallel to each other.

  According to the polyimide resin film pattern forming method of this embodiment, there are a plurality of bridge portions of the photoresist, and the plurality of bridge portions are arranged substantially parallel to each other. Can be formed.

  In one embodiment of the polyimide resin film pattern forming method, the photoresist has a plurality of bridge portions, and the plurality of bridge portions are arranged in a substantially lattice shape.

  According to the polyimide resin film pattern forming method of this embodiment, there are a plurality of the bridge portions of the photoresist, and the plurality of bridge portions are arranged in a substantially lattice shape. Can be formed.

  Moreover, in the polyimide resin film pattern forming method of one embodiment, the aspect ratio of the bridge portion of the photoresist is 20 or less.

  According to the pattern forming method of the polyimide resin film of this embodiment, the aspect ratio of the bridge portion of the photoresist is 20 or less. The remaining polyimide resin film under the bridge is prevented.

  In one embodiment of the polyimide resin film pattern forming method, the photoresist has a plurality of bridge portions, and the interval between the adjacent bridge portions is 20 μm or less.

  According to the pattern forming method of the polyimide resin film of this embodiment, since the interval between the adjacent bridge portions is 20 μm or less, the hook-shaped portion located between the adjacent bridge portions is broken and flies. Can be prevented.

  In the polyimide resin film pattern forming method of one embodiment, the end portion of the bridge portion of the photoresist is thicker than the central portion.

  According to the pattern forming method of the polyimide resin film of this embodiment, since the end portion of the bridge portion of the photoresist is thicker than the central portion, the strength of the bridge portion can be improved.

  According to the polyimide resin film pattern forming method of the present invention, a pattern having a plurality of windows partitioned by bridges is formed at a position corresponding to the opening pattern of the polyimide resin film in the photoresist. The photoresist is exposed, the development of the photoresist and the etching of the polyimide resin film are performed at the same time using the same liquid, and the portion of the polyimide resin film that overlaps the bridge portion of the photoresist is also the same. Since the opening pattern is formed by isotropic etching, an appropriate pattern of the polyimide resin film can be formed without changing any process process conditions.

  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

(First embodiment)
FIG. 1 is a plan view showing a first embodiment of a photoresist used in a method for forming a pattern of a polyimide resin film according to the present invention. In the polyimide resin film pattern forming method of the present invention, a polyimide resin film 2, a photoresist and a mask are sequentially formed on the upper surface of the semiconductor device 1 as in the description of FIG. Etching is performed so as to have an opening pattern larger than the hole portion of the resist.

  That is, in the polyimide resin film pattern forming method of the present invention, the photoresist 3 is formed on the polyimide resin film 2 as shown in FIGS. 1 and 4, and then the photoresist 3 is formed. The photoresist 3 is exposed so as to form a pattern having a plurality of window portions 32 partitioned by bridge portions 31 at positions corresponding to the opening pattern of the polyimide resin film 2 in FIG. Thereafter, the development of the photoresist 3 and the etching of the polyimide resin film 2 are performed at once using the same liquid, and the portion of the polyimide resin film 2 that overlaps the bridge portion 31 of the photoresist 3 is also isotropic. Etching is performed to form the opening pattern.

  That is, the photoresist 3 is a portion overlapping the region where the polyimide resin film 2 is removed during pattern formation in which the development of the photoresist 3 and the etching of the polyimide resin film 2 are performed at once using the same liquid. The photosensitive portion has a hole 30a provided in the photoresist main body 30, and a plurality of the bridge portions 31 provided on the inner peripheral surface of the hole 30a.

  The hole 30a is formed in a square shape in plan view. The plurality of bridge portions 31 are arranged substantially parallel to each other. The bridge portion 31 is formed in a linear shape and is arranged so as to be inclined at 45 degrees with respect to one side of the inner peripheral surface of the hole portion 30a. The bridge portion 31 connects adjacent sides of the inner peripheral surface of the hole portion 30a.

  In FIG. 1, the opening pattern of the final polyimide resin film 2 is indicated by a dotted frame Z. A portion between the dotted frame Z and the inner peripheral surface of the hole 30a is a portion formed in a bowl shape by etching. The space portion of the photoresist 3 is a region where the polyimide resin film 2 is etched by development with an alkaline solution.

  The width X of the bridge portion 31 of the photoresist 3 is not more than twice the thickness of the polyimide resin film 2. The aspect ratio of the bridge portion 31 of the photoresist 3 is 20 or less. Here, the aspect ratio of the bridge portion 31 is the ratio of the length to the width X of the bridge portion 31. The interval Y between the adjacent bridge portions 31 is 20 μm or less.

  According to the pattern forming method of the polyimide resin film having the above configuration, the plurality of window portions 32 partitioned by the bridge portion 31 are provided at positions corresponding to the opening pattern of the polyimide resin film 2 in the photoresist 3. The photoresist 3 is exposed so as to form a pattern, and the development of the photoresist 3 and the etching of the polyimide resin film 2 are performed at once using the same liquid, so that the bridge portion of the photoresist 3 is formed. The portion of the polyimide resin film 2 that overlaps 31 is isotropically etched to form the opening pattern. Therefore, the development of the photoresist 3 and the etching of the polyimide resin film 2 allow the Even if the portion corresponding to the opening pattern of the polyimide resin film 2 (the inner peripheral portion of the hole 30a) remains in a bowl shape. Since the photoresist 3 forms a pattern having a plurality of window portions 32 partitioned by the bridge portion 31, during development, the water flow at the time of subsequent washing, the centrifugal force at the time of rotary drying, etc. The saddle-shaped portion does not fold and fly, and pattern defects of the polyimide resin film 2 can be prevented.

  In addition, the photoresist 3 can be formed by changing only the mask pattern without changing any process process conditions so that the saddle-like portion of the photoresist 3 does not break off.

  Moreover, since the polyimide resin film 2 below the bridge portion 31 of the photoresist 3 can also be removed by lateral etching, the finish of the pattern of the polyimide resin film 2 is the same as the conventional one.

  Further, there are a plurality of bridge portions 31 of the photoresist 3, and the plurality of bridge portions 31 are arranged substantially parallel to each other, so that the photoresist 3 can be easily formed.

  Further, since the width X of the bridge portion 31 of the photoresist 3 is less than twice the thickness of the polyimide resin film 2, the polyimide resin film 2 under the bridge portion 31 of the photoresist 3 is etched. Can be reliably removed with a lateral shift.

  That is, the width X of the photoresist 3 needs to be set to a thickness that can be sufficiently etched by the lateral etching of the polyimide resin film 2. Usually, when the polyimide resin film 2 is etched with an alkaline solution, it is etched isotropically, so that the etching amount in the lateral direction is substantially equal to the thickness of the polyimide resin film 2. Therefore, the width X of the photoresist 3 needs to be not more than twice the thickness of the polyimide resin film 2.

  In addition, since the aspect ratio of the bridge portion 31 of the photoresist 3 is 20 or less, the bridge portion 31 of the photoresist 3 is prevented from sagging during etching, and is formed below the bridge portion 31 of the photoresist 3. The remaining generation of a certain polyimide resin film 2 is prevented.

  That is, when the strength of the bridge portion 31 of the photoresist 3 is taken into consideration, if the length is too long with respect to the width X of the bridge portion 31, the photoresist 3 may hang down during etching. In this case, the remainder of the polyimide resin film 2 on the lower side of the photoresist 3 may occur. Therefore, it is necessary to limit the length (aspect ratio) with respect to the width X of the photoresist 3. For example, when the size of the opening of the polyimide resin film 2 as the bonding pad portion is 100 μm and the thickness of the polyimide resin film 2 is about 3 μm, the width X of the photoresist 3 needs to be about 5 μm. In this case, the aspect ratio is about 16. Therefore, the aspect ratio is desirably 20 or less.

  Moreover, since the space | interval Y of the said adjacent bridge part 31 is 20 micrometers or less, it can prevent that the bowl-shaped part located between the said adjacent bridge parts 31 breaks and flies.

  In other words, if the gap Y between the adjacent bridge portions 31 is too large, the hole 30a of the photoresist 3 between the adjacent bridge portions 31 is the same as in a state where the bridges 31 are not connected, and it is broken and flies as before. . Therefore, in order to prevent the photoresist 3 between the adjacent bridge portions 31 from being broken and flying, it is desirable that the interval Y is set to about 20 μm or less.

(Second Embodiment)
FIG. 2 is a plan view showing a second embodiment of a photoresist used in the method for forming a polyimide resin film pattern of the present invention. The difference from the first embodiment will be described. In the second embodiment, the plurality of bridge portions 51 of the photoresist 5 are arranged in a substantially lattice shape. The bridge portion 51 defines a window portion 52.

  That is, the plurality of bridge portions 51 connect opposite sides of the inner peripheral surface of the hole portion 50a of the photoresist main body 50. In the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  Accordingly, since the plurality of bridge portions 51 are arranged in a substantially lattice shape, the photoresist 5 can be formed firmly.

(Third embodiment)
FIG. 3 is a plan view showing a third embodiment of a photoresist used in the polyimide resin film pattern forming method of the present invention. The difference from the second embodiment will be described. In the third embodiment, the end portion 61b of the bridge portion 61 of the photoresist 6 is thicker than the central portion 61a. The bridge portion 61 defines a window portion 62.

  That is, the end portion 61b is a portion connected to the inner peripheral surface of the hole 60a of the photoresist main body 60, and is wider than the central portion 61a located between the both end portions 61b. Since other structures are the same as those of the second embodiment, description thereof is omitted.

  Therefore, since the end 61b is thicker than the central portion 61a, the bridge 61 can be firmly connected to the inner peripheral surface of the hole 60a, and the strength of the bridge 61 is improved. it can.

  In addition, this invention is not limited to the above-mentioned embodiment. For example, at least one bridge part is sufficient. Further, at least two points on the inner peripheral surface of the hole portion of the photoresist may be connected by a bridge portion. Further, when the hole portion of the photoresist is a polygon, at least two sides of the polygon may be connected by a bridge portion. Further, the opening pattern of the polyimide resin film and the hole of the photoresist may be a polygon such as a rectangle, a hexagon or an octagon, or a circle other than a square.

It is a top view which shows 1st Embodiment of the photoresist used for the pattern formation method of the polyimide resin film of this invention. It is a top view which shows 2nd Embodiment of the photoresist used for the pattern formation method of the polyimide resin film of this invention. It is a top view which shows 3rd Embodiment of the photoresist used for the pattern formation method of the polyimide resin film of this invention. It is sectional drawing which shows the state after the etching of the polyimide resin film as a protective film of a semiconductor device. It is a top view which shows the conventional photoresist.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor device 2 Polyimide resin film 3, 5, 6 Photoresist 30, 50, 60 Photoresist main body 30a, 50a, 60a Hole 31, 51, 61 Bridge part 61a Center part 61b End part 32, 52, 62 Window part 103 Photoresist 130a Hole 104 Mask

Claims (7)

Forming a photoresist on the polyimide resin film;
Exposing the photoresist so as to form a pattern having a plurality of windows partitioned by bridges at positions corresponding to the opening pattern of the polyimide resin film in the photoresist;
The development of the photoresist and the etching of the polyimide resin film are performed at the same time using the same liquid, and the portion of the polyimide resin film overlapping the bridge portion of the photoresist is etched isotropically, And a step of forming an opening pattern. A method for forming a pattern of a polyimide resin film. The polyimide resin film pattern forming method according to claim 1,
The polyimide resin film pattern forming method, wherein the width of the bridge portion of the photoresist is not more than twice the thickness of the polyimide resin film. In the polyimide resin film pattern formation method according to claim 1 or 2,
A method for forming a pattern of a polyimide resin film, wherein the photoresist has a plurality of bridge portions, and the plurality of bridge portions are arranged substantially parallel to each other. In the polyimide resin film pattern formation method according to claim 1 or 2,
There is a plurality of bridge portions of the photoresist, and the plurality of bridge portions are arranged in a substantially lattice shape. In the polyimide resin film pattern formation method according to any one of claims 1 to 4,
A method for forming a pattern of a polyimide resin film, wherein an aspect ratio of a bridge portion of the photoresist is 20 or less. In the polyimide resin film pattern forming method according to any one of claims 1 to 5,
A method for forming a pattern of a polyimide resin film, wherein the photoresist has a plurality of bridge portions, and an interval between the adjacent bridge portions is 20 μm or less. In the polyimide resin film pattern formation method according to any one of claims 1 to 6,
The polyimide resin film pattern forming method, wherein an end portion of the bridge portion of the photoresist is thicker than the central portion.

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