Method for producing photosensitive resin membrane

Abstract

To make a photosensitive resin membrane made of the same material thicker stably.SOLUTION: A method for producing a photosensitive resin membrane 10 includes: applying a photosensitive resin material 50 to a top layer side of an insulating substrate 20; covering the photosensitive resin material 50 by a first photomask 75; exposing and developing the material via the first photomask 75, and curing it by heating after the development to form a first photosensitive resin membrane 11; applying the photosensitive resin material 50 of the same raw material as that of the first photosensitive resin membrane 11 to the first photosensitive resin membrane 11; coating the photosensitive resin material 50 by a second photomask 76; and exposing and developing the material via the second photomask 76, and curing it by heating after the development to form a second photosensitive resin membrane 12.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The technology described in this specification relates to a method for producing a photosensitive resin film. [Background technology]

[0002] Conventionally, a method for forming a wiring structure by photolithography has been known, and one example of such a method is described in Patent Document 1. In Patent Document 1, a TFT (Thin Film Transistor) or the like is formed as a switching element of a liquid crystal display device, and a drain electrode and a pixel electrode constituting the TFT are connected via a contact hole penetrating an interlayer insulating film.

[0003] Patent Document 1 also discloses that the interlayer insulating film is made of a two-layer photosensitive resin film having different photosensitivity. It discloses that the UV sensitivity of the first interlayer insulating film closer to the substrate and the second interlayer insulating film laminated on the first interlayer insulating film are extremely different, so that the first interlayer insulating film is hardly exposed to UV light that exposes the second interlayer insulating film to form a concave-convex pattern. It is said that this allows the first interlayer insulating film to act as a stop layer during development, thereby regulating the depth of the concave-convex shape of the second interlayer insulating film. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2001-42304 A Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, for example, in order to reduce the parasitic capacitance occurring between the conductive films sandwiching the interlayer insulating film and ensure the withstand voltage of the interlayer insulating film, it is effective to make the interlayer insulating film thicker (for example, about 6 μm or more). However, when the film thickness is increased by forming multiple layers using different photosensitive resin materials as in Patent Document 1, there are problems such as an increase in the number of raw material types and a complicated manufacturing process that makes it impossible to use conventional manufacturing equipment as is. On the other hand, when the photosensitive resin film is made thicker using the same material, the film thickness tends to vary, making it difficult to stably achieve the desired film thickness.

[0006] The technology described in this specification was developed based on the above-mentioned circumstances, and has an object to stably thicken a photosensitive resin film made of the same material. [Means for solving the problem]

[0007] (1) A method for producing a photosensitive resin film related to the technology described in the present specification includes a first coating step of coating a photosensitive resin material on an upper layer side of an insulating substrate, a first exposure and development step of covering the photosensitive resin material coated in the first coating step with a first photomask and exposing and developing it through the first photomask, a first heating step of curing the material by heating to form a first photosensitive resin film after development, a second coating step of coating the photosensitive resin material, which is the same as the raw material of the first photosensitive resin film, on the first photosensitive resin film cured by heating, a second exposure and development step of covering the photosensitive resin material coated in the second coating step with a second photomask and exposing and developing it through the second photomask, and a second heating step of curing the material by heating to form a second photosensitive resin film after development.

[0008] (2) In addition to the above (1), the first photosensitive resin film may have a smaller thickness than the second photosensitive resin film.

[0009] (3) In addition to the above (1) or (2), the first photomask may have a pattern including a first opening, the second photomask may have a pattern including a second opening that overlaps with the first opening in a planar view, and an inner diameter dimension of the second opening may be 1.5 times or more larger than an inner diameter dimension of the first opening.

[0010] (4) In addition to the above (1) or (2), the amount of light irradiation when exposing the photosensitive resin material that is the raw material of the second photosensitive resin film may be more than twice the amount of light irradiation when exposing the photosensitive resin material that is the raw material of the first photosensitive resin film.

[0011] (5) In addition to the above (1) or (2), the photosensitive resin material may be an acrylic resin material.

[0012] (6) In addition to the above (1) or (2), the photosensitive resin material may be applied by a slit coater having a slit serving as a discharge port.

[0013] (7) In addition to the above (1) or (2), the photosensitive resin film may be an interlayer insulating film between a first conductive film and a second conductive film.

[0014] (8) In addition to the above (7), the first photomask may have a pattern including a first opening, the second photomask may have a pattern including a second opening overlapping the first opening in a planar view, a first through hole conforming to the first opening is formed in the first interlayer insulating film, a second through hole conforming to the second opening is formed in the second interlayer insulating film, and the first through hole and the second through hole may be contact holes for electrically connecting the first conductive film and the second conductive film. Effect of the Invention

[0015] According to the technology described in this specification, a photosensitive resin film made of the same material can be stably made thick. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a cross-sectional view showing a photosensitive resin film according to an embodiment of the present invention. [Diagram 2] FIG. 11 is a cross-sectional view showing a photosensitive resin film according to another embodiment. [Diagram 3] 1 is a cross-sectional view showing a process for producing a photosensitive resin film. [Figure 4] Perspective view of the coating device [Diagram 5] A cross-sectional view showing a process subsequent to FIG. [Figure 6] A cross-sectional view showing a process subsequent to FIG. 5. [Figure 7] A cross-sectional view showing a process subsequent to FIG. [Figure 8] A cross-sectional view showing a process subsequent to FIG. 7. [Figure 9] A plan view showing the openings in the photomask. [Figure 10] Cross-sectional micrograph of the photosensitive resin film in evaluation experiment 1 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] <Embodiment 1> A method for producing a photosensitive resin film 10 according to the first embodiment will be described with reference to Fig. 1 to Fig. 10. Note that some of the drawings show an X-axis, a Y-axis, and a Z-axis, and each axis direction is drawn so as to be a common direction in each drawing. In addition, in the Z-axis direction, the upper side of the drawing is the upper layer side, and the lower side is the lower layer side.

[0018] As shown in Fig. 1, the photosensitive resin film 10 has a first photosensitive resin film 11 laminated on the upper layer side of a glass substrate 20 (an example of an insulating substrate), and a second photosensitive resin film 12 laminated on the first photosensitive resin film 11. As shown in Fig. 2 as an example, the photosensitive resin film 10 may be formed not on the glass substrate 20 but on another film on the upper layer side of the glass substrate 20 (on the first conductive film 30 in Fig. 2). In the following, a method of forming the photosensitive resin film 10 on the glass substrate 20 as shown in Fig. 1 will be described, but the basic manufacturing method is the same even when the photosensitive resin film 10 is formed on another layer.

[0019] First, as shown in FIG. 3, a photosensitive resin material 50, which is a raw material of the first photosensitive resin film 11, is applied onto a glass substrate 20 (first application step S1). The photosensitive resin material 50 is, for example, an acrylic resin material. The acrylic resin material is versatile and can be used for photosensitive resin films of various products. The application is performed, for example, by using a slit coater 70 (an example of an application device) shown in FIG. 4. The slit coater 70 includes a discharge section 71 from which the photosensitive resin material 50 is discharged, and a slit 71A serving as a discharge port is formed in the discharge section 71. A plate-shaped spacer (shim plate) can be inserted into the slit 71A, and the size of the discharge port (slit width) can be adjusted by the spacer.

[0020] The applied photosensitive resin material 50 is covered with a first photomask 75 and exposed to light through the first photomask 75 (FIG. 3). The first photomask 75 has a first opening 75A. The photosensitive resin material 50 is patterned by exposure and development (FIG. 5, first exposure and development step S2). After development, the patterned photosensitive resin material 50 is heated (sintered) and cured to form a first photosensitive resin film 11 (FIG. 6, first heating step S3). The first photosensitive resin film 11 has a first through hole 11S that conforms to the first opening 75A. The film thickness of the first photosensitive resin film 11 after heating and curing is indicated by the symbol T11.

[0021] Next, the photosensitive resin material 50 is applied again onto the first photosensitive resin film 11 (FIG. 7, second application step S4). The photosensitive resin material 50 is the same as the raw material of the first photosensitive resin film 11, including the composition and the content of the photosensitive component, and is applied by the same slit coater 70. The slit width of the slit coater 70 does not need to be changed and remains the same as in the first application step S1. The applied photosensitive resin material 50 is covered with a second photomask 76 and exposed by light irradiation through the second photomask 76. The second photomask 76 has a second opening 76A that overlaps with the first opening 75A of the first photomask 75 in a plan view. The photosensitive resin material 50 is exposed and developed to be patterned (FIG. 8, second exposure and development step S5).

[0022] As shown in FIG. 9, the inner diameter of the second opening 76A of the second photomask 76 is larger than that of the first opening 75A, and the inner diameter dimension of the second opening 76A is preferably 1.5 times or more larger than that of the first opening 75A. In this way, light can be irradiated over a wide range in the second exposure and development process S5. More specifically, in the second application process S4 (FIG. 7), the photosensitive resin material 50 flows into the first through hole 11S of the first photosensitive resin film 11 on the lower layer side, but by making the second opening 76A larger, light can be irradiated sufficiently to the photosensitive resin material 50 in the first through hole 11S. As a result, it is possible to suppress the situation in which film remains in the first through hole 11S.

[0023] The amount of light applied in the second exposure and development process S5 is preferably at least twice as much as the amount of light applied in the first exposure and development process S2. This also allows the photosensitive resin material 50 in the first through-hole 11S of the first photosensitive resin film 11 to be sufficiently irradiated with light, and reduces the amount of film remaining in the first through-hole 11S.

[0024] Furthermore, by making the second opening 76A larger, even if the second opening 76A is misaligned with the first opening 75A, it is possible to prevent the planar size of the overlapping portion between the first through hole 11S of the first photosensitive resin film 11 and the second through hole 12S of the second photosensitive resin film 12 from being significantly smaller than the first through hole 11S.

[0025] After development, the patterned photosensitive resin material 50 is heated (sintered) and cured to form a second photosensitive resin film 12, and then the photosensitive resin film 10 is formed (FIG. 1, second heating step S6). The second photosensitive resin film 12 has a second through hole 12S that conforms to the second opening 76A. The film thickness of the second photosensitive resin film 12 after heat curing is indicated by the symbol T12. Note that the first photosensitive resin film 11 also undergoes slight thermal shrinkage due to the second heating step S6, and therefore the film thickness T11 also decreases slightly due to the second heating step S6.

[0026] 1, it is preferable that the thickness T11 of the first photosensitive resin film 11 is smaller than the thickness T12 of the second photosensitive resin film 12. In this way, the amount of the photosensitive resin material 50 applied in the second application step S4 (FIG. 7) flowing into the first through-holes 11S of the lower first photosensitive resin film 11 can be reduced, making it easier to reduce liquid pools that hinder uniform application.

[0027] Incidentally, the coating thickness of the photosensitive resin material 50 varies not only with the size of the discharge port (slit width) of the slit coater 70, but also with the discharge pressure, coating speed, viscosity of the photosensitive resin material 50, and the like. For this reason, in the coating process of the photosensitive resin material 50 described above, in order to suppress variations in the film thickness and coat the coating thickness stably, it is necessary to optimize the set values ​​of these elements. Since this optimal value differs depending on the desired coating film thickness, when a common slit coater 70 is used for many types of products with different coating film thicknesses, it is necessary to determine the optimal value according to the coating film thickness in advance and then change the setting of the optimal value.

[0028] In this respect, in the manufacturing method of the photosensitive resin film 10 according to the present embodiment, as described above, the coating process of the same photosensitive resin material 50, the exposure and development process, and the heating process are repeated twice in sequence, and the second photosensitive resin film 12 is laminated on the first photosensitive resin film 11. The film thicknesses of the first photosensitive resin film 11 and the second photosensitive resin film 12 can be the same as in the past, and there is no need to thicken each of them. Therefore, in the coating process, it is not necessary to determine the optimal value of each element according to the film thickness or to change the settings to each optimal value. For example, when the photosensitive resin film 10 is thickened from the conventional thickness of about 3 μm to about 6 μm, the thicknesses of the first photosensitive resin film 11 and the second photosensitive resin film 12 can remain at about 3 μm. As a result, the photosensitive resin film 10 made of the same material can be thickened stably.

[0029] The photosensitive resin film 10 thickened in this way is used as an interlayer insulating film between the first conductive film 30 and the second conductive film 40, for example, as shown in FIG. 2. Such an interlayer insulating film is widely used as an organic insulating film (so-called JAS film) in, for example, a liquid crystal panel. By thickening the interlayer insulating film between the conductive films 30 and 40 using this technology, the parasitic capacitance can be reduced and the withstand voltage can be ensured so that the interlayer insulating film does not break down. As a result, the display quality of the liquid crystal panel can be improved. Even if the photosensitive resin film 10 is thickened, the contact hole 10S for electrically connecting the first conductive film 30 and the second conductive film 40 can be easily formed by forming the first through hole 11S of the first photosensitive resin film 11 and the second through hole 12S of the second photosensitive resin film 12 as described above.

[0030] <Evaluation experiment 1> In order to verify the above-mentioned action and effect, evaluation experiment 1 was carried out. In evaluation experiment 1, a photosensitive resin film 10 having a large thickness of 6 μm was formed under the following conditions, and its cross section was photographed with a scanning electron microscope (FIG. 10). The evaluation sample was assumed to be an application example to a general liquid crystal panel (a gate metal film, a gate insulating film, a semiconductor film, a source metal film, an interlayer insulating film (photosensitive resin film) 10, and a transparent electrode film are laminated in this order on a glass substrate 20 by a lithography method). FIG. 10 is a cross-sectional photograph at a stage after the interlayer insulating film 10 is formed and before the transparent electrode film is formed. The cross-sectional photograph was used to evaluate the state of the interface between the first photosensitive resin film 11 and the second photosensitive resin film 12, and the finished state of the through holes 11S and 12S. In addition, a peel test was carried out to evaluate film peeling at the interface between the first photosensitive resin film 11 and the second photosensitive resin film 12.

[0031] <Condition> Photosensitive resin material 50: Acrylic resin material Inner diameter dimension of the first opening 75A of the first photomask 75: 8.0 μm × 5.0 μm Inner diameter dimension of the second opening 76A of the second photomask 76: 12.0 μm×8.0 μm Exposure amount in the first exposure and development step S2: 250 mJ / cm 2 Exposure amount in the second exposure and development step S5: 500 mJ / cm 2 Heating temperature in the first heating step S3: 210°C Heating temperature in the second heating step S6: 210°C Thickness T11 of the first photosensitive resin film 11 after the first heating step S3: 3.2 μm Thickness T12 of second photosensitive resin film 12 after second heating step S6: 3.6 μm

[0032] <Evaluation Results> As shown in Fig. 10, a scanning electron microscope confirmed that no boundary line was observed at the interface between the first photosensitive resin film 11 and the second photosensitive resin film 12, and that the films were continuously formed. Although a step between the first photosensitive resin film 11 and the second photosensitive resin film 12 was visible at the opening edge of the first through hole 11S of the first photosensitive resin film 11 and the second through hole 12S of the second photosensitive resin film 12, it was confirmed that there were no defects such as remaining film or residue. Also, in a peel test, it was confirmed that no film peeling occurred (JIS standard level 0 judgment).

[0033] <Other embodiments> The technology described in this specification is not limited to the embodiments described above with reference to the drawings, and for example, the following embodiments are also included within the technical scope of the present invention.

[0034] (1) The technology described in this specification is applicable not only to liquid crystal panels but also to all devices in which a photosensitive resin film is used. [Explanation of symbols]

[0035] Reference Signs List 10...photosensitive resin film, 10S...contact hole, 11...first photosensitive resin film, 11S...first through hole, 12...second photosensitive resin film, 12S...second through hole, 20...glass substrate (insulating substrate), 30...first conductive film, 40...second conductive film, 50...photosensitive resin material, 70...slit coater (coating device), 75...first photomask, 75A...first opening, 76...second photomask, 76A...second opening

Claims

1. A first coating step of coating a photosensitive resin material on an upper layer side of an insulating substrate; a first exposure and development step of covering the photosensitive resin material applied in the first application step with a first photomask and exposing and developing the material through the first photomask; a first heating step of curing the developed resin by heating to form a first photosensitive resin film; a second coating step of coating the photosensitive resin material, which is the same as the raw material of the first photosensitive resin film, on the heat-cured first photosensitive resin film; a second exposure and development step of covering the photosensitive resin material applied in the second application step with a second photomask and exposing and developing the material through the second photomask; and a second heating step of, after the development, curing the developed resin by heating to form a second photosensitive resin film.

2. 2. The method for producing a photosensitive resin film according to claim 1, wherein the thickness of the first photosensitive resin film is smaller than the thickness of the second photosensitive resin film.

3. the first photomask has a pattern including a first opening; the second photomask has a pattern including a second opening overlapping the first opening in a plan view; 3. The method for producing a photosensitive resin film according to claim 1, wherein an inner diameter of the second opening is 1.5 times or more larger than an inner diameter of the first opening.

4. 3. The method for manufacturing a photosensitive resin film according to claim 1, wherein the amount of light irradiation when exposing the photosensitive resin material that is the raw material for the second photosensitive resin film is at least twice the amount of light irradiation when exposing the photosensitive resin material that is the raw material for the first photosensitive resin film.

5. 3. The method for producing a photosensitive resin film according to claim 1, wherein the photosensitive resin material is an acrylic resin material.

6. 3. The method for producing a photosensitive resin film according to claim 1, wherein the photosensitive resin material is applied by using a coating device having a slit serving as a discharge port.

7. 3. The method for producing a photosensitive resin film according to claim 1, wherein the photosensitive resin film is an interlayer insulating film between a first conductive film and a second conductive film.

8. the first photomask has a pattern including a first opening; the second photomask has a pattern including a second opening overlapping the first opening in a plan view; a first through hole conforming to the first opening is formed in the first interlayer insulating film; a second through hole conforming to the second opening is formed in the second interlayer insulating film; The method for manufacturing a photosensitive resin film according to claim 7 , wherein the first through hole and the second through hole may be contact holes for electrically connecting the first conductive film and the second conductive film.

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