JP2008275797A - Photoresist pattern forming method - Google Patents

Abstract

A photoresist pattern forming method having excellent dimensional accuracy and productivity is provided.
According to a first aspect of the present invention, there is provided a photoresist pattern forming method comprising: applying a photoresist on a film to be etched formed on a substrate; and pre-baking the substrate coated with the photoresist. Pre-baking in the furnace, cooling the substrate carried out from the pre-baking furnace to a predetermined temperature while measuring the substrate temperature with a temperature sensor in the temperature control unit, and the substrate carried out from the temperature control unit The step of exposing the upper photoresist in an exposure machine and the step of developing the photoresist on the substrate unloaded from the exposure machine are provided.
[Selection] Figure 1

Description

  The present invention relates to a photoresist pattern forming method, and more particularly to a photoresist pattern forming method in manufacturing a display device such as a liquid crystal display device or an organic EL display device.

  In recent years, the importance of display devices such as liquid crystal display devices and organic EL display devices has been increasing along with the full-scale progress of an advanced video and information society and the rapid spread of multimedia systems. Since these display devices have the advantages of low power consumption, thinness, and light weight, they are widely used as display devices for portable terminal devices.

  In the display device, wirings and electrodes made of a metal film or a transparent conductive film are formed on a transparent substrate made of glass or the like. In order to form the electrodes and wiring, first, a metal film or a transparent conductive film is formed on a transparent substrate, and a photoresist is applied on the film. Next, pre-baking is performed to evaporate the solvent of the photoresist. Thereafter, the mask and the transparent substrate are aligned and exposed. Next, the exposed photoresist is developed, and unnecessary photoresist is removed. Then, using the photoresist pattern thus formed as a mask, unnecessary metal films and transparent conductive films are removed by etching to form wirings and electrodes.

  Here, in order to improve the dimensional accuracy of the wiring and the electrode, it is necessary to suppress the variation in the substrate temperature during the photoresist exposure as much as possible. Conventionally, the substrate after pre-baking is insufficiently cooled, causing variations in the substrate temperature during exposure, resulting in a problem that desired dimensional accuracy of wiring and electrodes cannot be obtained. This problem becomes more serious as the substrate becomes larger.

As a technique related to this, Patent Document 1 discloses a method of introducing clean air whose temperature and humidity are controlled in an exposure machine.
JP 2006-253202 A

  However, in the method described in Patent Document 1, since the substrate temperature is not directly controlled, there is a problem that it takes time to control the substrate temperature and the productivity is poor.

  The present invention has been made against the background of the above problems, and an object of the present invention is to provide a photoresist pattern forming method excellent in dimensional accuracy and productivity.

  According to a first aspect of the present invention, there is provided a photoresist pattern forming method comprising: applying a photoresist on an etching target film formed on a substrate; and pre-baking the substrate coated with the photoresist in a pre-baking furnace. A step of cooling the substrate unloaded from the prebaking furnace to a predetermined temperature while measuring the substrate temperature with a temperature sensor in the temperature control unit, and a photoresist on the substrate unloaded from the temperature control unit And a step of developing the photoresist on the substrate unloaded from the exposure machine. Thereby, the photoresist pattern formation method excellent in dimensional accuracy and productivity can be provided.

  The photoresist pattern forming method according to the second aspect of the present invention is the above photoresist pattern forming method, wherein the substrate is placed on a cooling table installed in the temperature control unit to cool the substrate. It is a feature. Thereby, dimensional accuracy can be improved reliably.

  A photoresist pattern forming method according to a third aspect of the present invention is the photoresist pattern forming method, wherein a plurality of the cooling tables are installed in the temperature control unit, and the substrate is disposed on the prebaking furnace side. A cooling table that absorbs rough heat is installed, and a cooling table that precisely cools the substrate to a predetermined temperature is installed on the exposure machine side. Thereby, productivity can be improved reliably.

  A photoresist pattern forming method according to a fourth aspect of the present invention is characterized in that, in the photoresist pattern forming method, the substrate is vacuum-sucked to the cooling table. Thereby, the temperature control of the substrate can be facilitated.

  The photoresist pattern forming method according to the fifth aspect of the present invention is characterized in that, in the above-described photoresist pattern forming method, the predetermined temperature is set to 20 ° C. to 28 ° C. Thereby, dimensional accuracy can be improved more reliably.

  According to the present invention, a photoresist pattern forming method excellent in dimensional accuracy and productivity can be provided.

  Embodiments of the present invention will be described below. However, the present invention is not limited to the following embodiment. In addition, for clarity of explanation, the following description and drawings are simplified as appropriate.

BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to FIG. FIG. 1 shows a flowchart of an electrode / wiring forming process on a substrate using the photoresist pattern forming method according to the present embodiment. As an example, a process of forming an electrode / wiring made of a transparent conductive film on a glass substrate used for a liquid crystal display device or an organic EL display device will be described. As shown in FIG. 1, this flow includes 8 steps from ST101 to ST108.

  First, a transparent conductive film for forming a transparent electrode / wiring is formed on a cleaned glass substrate by a sputtering method, a vacuum deposition method, or the like (ST101). A typical transparent electrode film for display devices is ITO (Indium Tin Oxide).

  Next, a photoresist, which is an ultraviolet photosensitive resin material, is applied to the entire surface of the transparent conductive film formed on the transparent substrate with a uniform thickness (ST102). In order to uniformly apply the photoresist, the type and amount of the solvent are appropriately selected. There are two types of photoresists: a negative type photoresist in which a light-irradiated part is crosslinked and cured and remains after development, and a positive type photoresist in which a light-irradiated part is decomposed and solubilized and removed by development. The present invention is applicable when any photoresist is used.

  Next, in order to evaporate the solvent of the photoresist, the transparent substrate coated with the photoresist is pre-baked (ST103). Specifically, for example, a transparent substrate coated with a photoresist is carried into a pre-baking furnace, placed on a hot plate installed in the furnace, and heated to about 90 ° C. Further, after the pre-baking is completed, the transparent substrate is placed on a cooling table in the pre-baking furnace and cooled. However, conventionally, it has been difficult to keep the temperature of the transparent substrate after cooling constant.

  Next, the transparent substrate carried out from the pre-baking furnace is carried into the temperature control unit, and in this temperature control unit, the temperature of the transparent substrate is measured by a temperature sensor and cooled to a predetermined temperature (ST104). Specifically, for example, a transparent substrate coated with a photoresist is placed on a table cooled by cooling water (hereinafter referred to as a cooling table). The transparent substrate is measured by a temperature sensor such as a thermocouple or a radiation thermometer, and cooled so that the temperature of the transparent substrate falls within a temperature range of 20 ° C to 28 ° C. By providing the temperature control unit between the pre-baking furnace and the exposure machine, it is possible to reduce variations in the temperature of the transparent substrate during exposure, and to provide a photoresist pattern forming method with excellent dimensional accuracy.

  Here, the structure of the temperature control unit will be described in detail with reference to FIG. As shown in FIG. 2, the temperature control unit 100 includes a clean room 101, a first cooling table 102, a second cooling table 103, a cooling water unit 104, a cooling water pipe 105, and a clean air unit 106.

  The first cooling table 102 and the second cooling table 103 installed inside the clean room 101 are cooled by the cooling water supplied to each from the cooling water unit 103 installed outside the clean room 101. Here, the first cooling table 102 and the second cooling table 103 have a vacuum suction mechanism, and the transparent substrate 110 can be brought into close contact with the table. Thereby, the transparent substrate 110 can be cooled effectively.

  Further, the first cooling table 102 and the second cooling table 103 are connected in parallel by a cooling water pipe 105. That is, the cooling water that has cooled the first cooling table 102 and the second cooling table 103 returns to the cooling water unit 104.

  Furthermore, throughput can be improved by installing a plurality of cooling tables connected in parallel. In the case of the present embodiment, the first cooling table 102 installed on the prebaking furnace side absorbs the rough heat of the transparent substrate 110 transferred by a substrate transfer means (not shown). Then, the temperature of the transparent substrate 110 conveyed from the first cooling table 102 is precisely cooled to a predetermined temperature by the substrate conveying means (not shown) in the second cooling table 103 installed on the exposure machine side. That is, the transparent substrate 110 is cooled stepwise by a plurality of cooling tables installed from the pre-baking furnace side to the exposure machine side. The number of cooling tables may be appropriately selected according to the throughput of the exposure apparatus.

  As indicated by the arrows in FIG. 2, the cooling water circulates through the path of the cooling water pipe 105, the water temperature is adjusted in the cooling water unit 104, and the first cooling table 102 and the second cooling table 103 again. To be supplied. The clean air unit 106 supplies clean air into the temperature control unit.

  Next, the transparent substrate automatically carried out from the temperature control unit is automatically carried into the exposure machine, and the photoresist is exposed (ST105). Specifically, after aligning a transparent substrate coated with a photoresist and a photomask, exposure is performed by irradiating ultraviolet rays. In this embodiment, a batch exposure method using a mirror projection type exposure machine and one large mask is adopted. As a matter of course, a step-and-repeat exposure method using a lens projection type exposure machine and a plurality of small masks may be adopted.

  In the exposure apparatus according to this embodiment, a high-output light source is used to improve the throughput of the exposure apparatus. On the other hand, this may increase the temperature in the exposure apparatus, but in the present invention, the temperature of the transparent substrate carried into the exposure apparatus can be appropriately adjusted by the temperature control unit. Specifically, when the temperature in the exposure apparatus rises, the temperature of the transparent substrate during exposure can be made constant by lowering the temperature of the transparent substrate that is carried in.

  Normally, the stage on which the transparent substrate is placed in the exposure machine is cooled by cooling water. However, if the temperature of the cooling water is lower than the dew point temperature, there is a problem that condensation occurs on the parts of the precision exposure machine. For example, when the exposure apparatus has a temperature of 25 ° C. and a humidity of 60% RH, the dew point temperature is 19.5 ° C., and condensation occurs when the stage is cooled to a temperature lower than this. In particular, when dew condensation occurs on the stage of the exposure machine, the operation of the alignment jig deteriorates, and the alignment accuracy of the transparent substrate deteriorates. In addition, due to the generation of rust due to condensation, foreign matter adheres to the transparent substrate, causing a defect in the formation of the photoresist pattern. For the above reasons, it is not preferable to cool the transparent substrate in the exposure machine. In other words, if the temperature control unit according to the present invention is used, it is not necessary to cool the stage in the exposure machine to a temperature lower than the dew point temperature, and condensation on the stage can be prevented.

  Next, the transparent substrate carried out from the exposure machine is carried into the developing machine, and the photoresist is developed (ST106). Specifically, the photoresist on the transparent substrate is developed with an organic alkali developer. After the development, pure water washing is performed to remove the developer. By this step, unnecessary photoresist is removed, and a photoresist pattern is formed on the transparent substrate.

  Next, the ITO film is etched using the photoresist pattern as a mask (ST107). Specifically, the ITO film is wet etched with an acidic etchant such as an iron chloride / hydrochloric acid aqueous solution. Thereby, an unnecessary ITO film is removed, and a wiring / electrode pattern made of the ITO film is formed. Etching includes wet etching and dry etching, which are appropriately selected depending on the film to be etched.

  Finally, the photoresist pattern is removed (ST108). Specifically, the photoresist is removed by wet peeling with strong alkali or ashing using plasma.

It is a flowchart of the electrode and wiring formation process on a board | substrate using the photoresist pattern formation method which concerns on embodiment. It is a schematic diagram which shows the structure of a temperature control unit.

Explanation of symbols

100 Temperature Control Unit 101 Clean Room 102 First Cooling Table 103 Second Cooling Table 104 Cooling Water Unit 105 Cooling Water Pipe 106 Clean Air Unit 110 Transparent Substrate

Claims (5)

Applying a photoresist on the film to be etched formed on the substrate;
Pre-baking the substrate coated with the photoresist in a pre-baking furnace;
Cooling the substrate unloaded from the pre-baking furnace to a predetermined temperature while measuring the substrate temperature with a temperature sensor in the temperature control unit;
Exposing the photoresist on the substrate unloaded from the temperature control unit in an exposure machine;
Developing a photoresist on the substrate unloaded from the exposure machine.   The method of forming a photoresist pattern according to claim 1, wherein the substrate is cooled by placing the substrate on a cooling table installed in the temperature control unit.   A plurality of cooling tables are installed in the temperature control unit, a cooling table that absorbs the rough heat of the substrate is installed on the pre-baking furnace side, and the substrate is precisely cooled to a predetermined temperature on the exposure machine side. The method of forming a photoresist pattern according to claim 2, wherein a cooling table is installed.   4. The method for forming a photoresist pattern according to claim 2, wherein the substrate is vacuum-sucked on the cooling table.   The photoresist pattern forming method according to claim 1, wherein the predetermined temperature is 20 ° C. to 28 ° C.

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