JP2011222779A - Method of manufacturing substrate for thin film element, method of manufacturing thin film element, method for thin film transistor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a substrate for a thin film element, which is superior in surface smoothness and can suppress characteristic deterioration of the thin film element.SOLUTION: In the method of manufacturing the substrate for the thin film element, a deaeration step of deaerating a polyimide resin composition so that the relative dissolved oxygen saturation ratio calculated by a predetermined method becomes 95% or less, and an insulating layer-forming step of forming an insulating layer by coating the polyimide resin composition are provided. The surface roughness Ra of the insulating layer is 30 nm or less.

Description

  The present invention relates to a method for producing a substrate for a thin film element, which is used for a thin film element such as a thin film transistor, a thin film solar cell, and an electroluminescence element, and an insulating layer containing polyimide is formed on a metal substrate.

  Polymer materials are used in various products around us because of their easy processing and light weight. The polyimide developed by DuPont in 1955 in the United States has been under development because it has excellent heat resistance and its application to the aerospace field has been studied. Since then, detailed research has been conducted by many researchers, and it has become clear that performance such as heat resistance, dimensional stability, and insulation properties are among the highest in organic materials. Application to materials was promoted. At present, it is actively used as a chip coating film in a semiconductor element, a base material of a flexible printed wiring board, and the like.

However, the polyimide film has a problem that craters and pinholes are generated due to bubbles. If craters or pinholes are present, the performance will be reduced, making it difficult to use as an insulating layer for electronic components.
There are various causes for the generation of bubbles in the film. One of them is a polyimide resin composition used for forming a polyimide film. When the polyimide resin composition is produced, bubbles are mixed in the polyimide resin composition, and the bubbles remain in the film.

  Polyimide is a polymer synthesized mainly from diamine and acid dianhydride. By reacting diamine and acid dianhydride in a solution, it becomes polyamic acid (polyamic acid) which is a precursor of polyimide, and then becomes a polyimide through a dehydration ring closure reaction. In general, since polyimide has poor solubility in a solvent and is difficult to process, it is often made into a polyimide by making it into a desired shape in a precursor state and then heating. Polyimide precursors are often unstable with respect to heat and water and tend to be inferior in storage stability, such as needing frozen storage. In consideration of this point, polyimide that has been improved so that it can be molded or applied by dissolving it in a solvent after introducing it into a polyimide by introducing a skeleton with excellent solubility in the molecular structure or reducing the molecular weight. Although it has been developed, when it is used, film properties such as heat resistance, chemical resistance, linear thermal expansion coefficient, hygroscopic expansion coefficient and the like tend to be inferior to those using a polyimide precursor. Therefore, a method using a polyimide precursor and a method using a solvent-soluble polyimide are selectively used according to the purpose.

  In order to remove bubbles mixed in the polyimide resin composition, a method of degassing a polyamic acid varnish or a polyimide varnish has been proposed (see, for example, Patent Documents 1 to 3). As degassing methods for polyamic acid varnish and polyimide varnish, for example, Patent Document 1 discloses a vacuum degassing method, a thin film vacuum degassing method, and a centrifugal thin film degassing method. A utilized deaeration method is disclosed, and Patent Documents 1 and 3 disclose a deaeration method of filtering using a filter.

JP-A-8-186343 JP-A-8-176505 JP 2002-348388 A

  In recent years, polyimide has been widely used as an insulating material for electronic components, and various performances have been required. Among these, in particular, a metal group used for thin film elements such as thin film transistors (hereinafter, thin film transistors may be referred to as TFTs), thin film solar cells, and electroluminescence elements (hereinafter, electroluminescence may be referred to as EL). In a thin film element substrate in which a material and an insulating layer containing polyimide are laminated, the thin film element portion formed on the insulating layer is thin, so fine irregularities on the surface of the thin film element substrate deteriorate the characteristics of the thin film element Therefore, it is required to improve the surface smoothness of the thin film element substrate. For example, in the case of TFTs, if there are fine irregularities on the semiconductor layer of the TFT, especially the base of the channel formation region, that is, if there are fine irregularities on the surface of the insulating layer containing polyimide, the mobility of the TFT is significantly reduced or leakage When current flows, it significantly affects the characteristics of the TFT. In addition, the yield decreases depending on the surface state of the insulating layer containing polyimide.

  By degassing the polyimide resin composition, it is possible to suppress the generation of craters and pinholes due to bubbles on the surface of the insulating layer containing polyimide. However, conventionally, as described in Patent Documents 1 and 3, bubbles in the micrometer order have been a problem, and bubbles in the nanometer order have not been studied at all. On the other hand, in the thin film element substrate, since the thin film element portion is thin, bubbles on the order of nanometers that affect the thin film element portion pose a problem. For example, in the TFT, bubbles on the order of nanometers that affect the channel formation region become a problem.

Here, the bubbles in the liquid are in a state where the gas remains in a gaseous state and is mixed in the liquid. This foam is not only mixed from the outside, but is very often generated from the liquid. On the other hand, dissolved gas means a gas dissolved in a liquid, which cannot be seen with eyes like bubbles.
The amount of gas dissolved in the liquid varies depending on the type of liquid, temperature and pressure, and the wetted material, and dissolved gas above the saturation amount appears as bubbles. That is, even if the liquid is free of bubbles, bubbles are generated when the temperature, pressure, or the like changes. On the other hand, even if bubbles are present in the liquid, the bubbles are dissolved in the liquid if the temperature is a predetermined temperature or pressure, or if the dissolved amount of the gas is less than the saturation value. That is, it is not sufficient to simply remove bubbles, and it is important to remove dissolved gas.

If dissolved gas in an amount close to the saturation amount is present in the polyimide resin composition, the gas exceeding the saturation amount appears as bubbles when the temperature or pressure changes with the process such as coating. When the amount of gas that exceeds the saturation amount is small, the bubble size is difficult to grow, so this has not been a big problem from the viewpoint of reducing micrometer-sized bubbles.
However, in order to control the smoothness on the order of nanometers on the surface of the insulating layer, it is necessary to suppress the generation of bubbles of nanometer order size. Therefore, it is necessary to reduce the amount of dissolved gas in order to avoid the presence of dissolved gas above the saturation amount. Therefore, in order to prevent the generation of nanometer-order bubbles that adversely affect the surface smoothness of the insulating layer in the thin film element substrate, the amount of dissolved gas in the polyimide resin composition should be kept lower than the saturation amount. Very important.

  This invention is made | formed in view of the said situation, and it aims at providing the manufacturing method of the board | substrate for thin film elements which is excellent in surface smoothness and can suppress the characteristic deterioration of a thin film element.

In order to achieve the above object, the present invention provides a degassing step of degassing the polyimide resin composition so that the relative dissolved oxygen saturation calculated by the following method is 95% or less, on the metal substrate, An insulating layer forming step of forming an insulating layer by applying the polyimide resin composition, and a method for producing a substrate for a thin film element, wherein the surface roughness Ra of the insulating layer is 30 nm or less To do.
<Calculation method of relative dissolved oxygen saturation>
First, using a dissolved oxygen saturated solvent in which air is bubbled for 30 minutes or more in a solvent contained in the polyimide resin composition, the measured value of the dissolved oxygen amount of the solvent in which no oxygen is dissolved is 0, and the dissolved oxygen saturated solvent The dissolved oxygen meter is calibrated so that the measured value of the dissolved oxygen amount becomes 100. Next, using the calibrated dissolved oxygen meter, the relative value of the dissolved oxygen amount of the reference polyimide resin composition in which the polyimide resin composition was allowed to stand for 1 hour or more in the atmosphere, and the degassing that degassed the polyimide resin composition. The relative value of the dissolved oxygen amount of the gas polyimide resin composition is measured. And the relative value of the dissolved oxygen amount of the said deaeration polyimide resin composition when the relative value of the dissolved oxygen amount of the said reference | standard polyimide resin composition is set to 100% is made into a relative dissolved oxygen saturation rate.

When gas is dissolved in the polyimide resin composition, the dissolved gas may appear as bubbles in the polyimide resin composition due to changes in temperature and pressure. Therefore, in order to reduce bubbles in the insulating layer, it is important to remove dissolved gas in the polyimide resin composition. Most of the gas dissolved in the polyimide resin composition is nitrogen or oxygen, which is difficult to measure because nitrogen is an inert gas, but oxygen can be measured, and the solubility of oxygen and nitrogen in the solvent Since the ratio of is substantially constant, it is possible to estimate the amount of dissolved gas combining nitrogen and oxygen by determining the amount of dissolved oxygen. Furthermore, it is difficult to measure the absolute value of dissolved oxygen in a solvent other than water.
Therefore, in the present invention, relative dissolved oxygen saturation is evaluated based on the dissolved oxygen amount of a dissolved oxygen saturated solvent obtained by bubbling air for 30 minutes or more in the solvent contained in the polyimide resin composition as a reference. The polyimide resin composition is degassed so that the rate is 95% or less. If the relative dissolved oxygen saturation rate is 95% or less, the dissolved oxygen does not immediately exceed the saturation amount due to a change in temperature or pressure, so that the generation of bubbles can be suppressed. As a result, not only micrometer order but also nanometer order bubbles can be suppressed. Therefore, an insulating layer having a surface roughness Ra of 30 nm or less and excellent surface smoothness can be formed, and a thin film element substrate capable of preventing deterioration of characteristics of the thin film element due to fine unevenness can be manufactured. It is.

  In the said invention, it is preferable to perform the said deaeration process just before the said insulating layer formation process. This is because bubbles contained in the insulating layer can be effectively reduced.

  In the present invention, the hygroscopic expansion coefficient of the insulating layer is preferably in the range of 0 ppm /% RH to 15 ppm /% RH. The hygroscopic expansion coefficient is an index of water absorption, and the smaller the hygroscopic expansion coefficient, the smaller the water absorption. Therefore, if the hygroscopic expansion coefficient is in the above range, high reliability can be realized in the presence of moisture. In addition, the smaller the hygroscopic expansion coefficient of the insulating layer, the better the dimensional stability of the insulating layer. Since the hygroscopic expansion coefficient of the metal base material is almost zero, if the hygroscopic expansion coefficient of the insulating layer is too large, the adhesion between the insulating layer and the metal base material may be reduced.

  Furthermore, in this invention, it is preferable that the linear thermal expansion coefficient of the said insulating layer exists in the range of 0 ppm / degrees C-25 ppm / degrees C. When the linear thermal expansion coefficient of the insulating layer is in the above range, the linear thermal expansion coefficients of the insulating layer and the metal base material can be made close, and the warpage of the thin film element substrate can be suppressed and the insulating layer and the metal base material can be suppressed. This is because it is possible to improve the adhesion.

  Moreover, in this invention, it is preferable that the difference of the linear thermal expansion coefficient of the said insulating layer and the linear thermal expansion coefficient of the said metal base material is 15 ppm / degrees C or less. As described above, the closer the linear thermal expansion coefficients of the insulating layer and the metal base material are, the more the warpage of the substrate for the thin film element can be suppressed and the adhesion between the insulating layer and the metal base material becomes higher.

  Moreover, in this invention, it is preferable to have the contact | glue layer formation process which forms the contact | adherence layer containing an inorganic compound on the said insulating layer after the said insulating layer formation process. By forming the adhesion layer, it is possible to obtain a thin film element substrate that has good adhesion to the thin film element part and can prevent peeling and cracking in the thin film element part.

  In the above case, the inorganic compound constituting the adhesion layer is at least one selected from the group consisting of silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride, aluminum oxynitride, chromium oxide and titanium oxide. It is preferable that This is because by using these materials, a film having good adhesion, smoothness, heat resistance, insulation and the like can be obtained.

  In the above case, the adhesion layer is preferably a multilayer film. In this case, the adhesion layer is formed on the insulating layer and is selected from the group consisting of chromium, titanium, aluminum, silicon, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride, aluminum oxynitride, chromium oxide, and titanium oxide. It is preferable to have a first adhesion layer made of at least one selected and a second adhesion layer made of silicon oxide and formed on the first adhesion layer. The adhesion between the insulating layer and the second adhesion layer can be enhanced by the first adhesion layer, and the adhesion between the insulation layer and the thin film element portion can be enhanced by the second adhesion layer. Moreover, by setting it as such a structure, it can be set as the contact | adherence layer excellent in adhesiveness, smoothness, heat resistance, insulation, etc.

The present invention also provides a method for producing a thin film element, comprising a thin film element part forming step for forming a thin film element part on the thin film element substrate produced by the above-described method for producing a thin film element substrate. To do.
According to the present invention, since the above-described thin film element substrate is used, a thin film element having excellent characteristics can be obtained.

Furthermore, the present invention provides a method for producing a TFT, comprising a TFT forming step for forming a TFT on the thin film element substrate produced by the above-described method for producing a thin film element substrate.
According to the present invention, since the thin film element substrate described above is used, it is possible to obtain a TFT with good electrical performance.

  In the above invention, the TFT preferably has an oxide semiconductor layer. Although the electrical characteristics of an oxide semiconductor change due to the influence of water and oxygen, the permeation of water vapor and oxygen can be suppressed by the thin film element substrate, so that deterioration of the characteristics of the semiconductor can be prevented.

  In the present invention, by degassing the polyimide resin composition so that the relative dissolved oxygen saturation calculated by a predetermined method is 95% or less, generation of bubbles not only in the micrometer order but also in the nanometer order is suppressed. It is possible to form an insulating layer having a surface roughness Ra of 30 nm or less and excellent surface smoothness, and it is possible to prevent deterioration of characteristics of the thin film element due to fine unevenness. .

It is a schematic sectional drawing which shows an example of the board | substrate for thin film elements manufactured with the manufacturing method of the board | substrate for thin film elements of this invention. It is a schematic sectional drawing which shows the other example of the board | substrate for thin film elements manufactured by the manufacturing method of the board | substrate for thin film elements of this invention. It is a schematic sectional drawing which shows an example of TFT provided with the board | substrate for thin film elements manufactured by the manufacturing method of the board | substrate for thin film elements of this invention. It is a schematic sectional drawing which shows the other example of TFT provided with the board | substrate for thin film elements manufactured by the manufacturing method of the board | substrate for thin film elements of this invention. It is a schematic sectional drawing which shows the other example of TFT provided with the board | substrate for thin film elements manufactured by the manufacturing method of the board | substrate for thin film elements of this invention. It is a schematic sectional drawing which shows the other example of the board | substrate for thin film elements manufactured by the manufacturing method of the board | substrate for thin film elements of this invention. It is the schematic sectional drawing and top view which show the other example of the board | substrate for thin film elements manufactured by the manufacturing method of the board | substrate for thin film elements of this invention. It is a schematic sectional drawing which shows the other example of the board | substrate for thin film elements manufactured by the manufacturing method of the board | substrate for thin film elements of this invention.

  Hereinafter, the manufacturing method of the thin film element substrate, the manufacturing method of the thin film element, and the manufacturing method of the TFT of the present invention will be described in detail.

A. Method for Manufacturing Thin Film Element Substrate First, a method for manufacturing a thin film element substrate of the present invention will be described.
The method for producing a substrate for a thin film element of the present invention includes a degassing step of degassing the polyimide resin composition so that the relative dissolved oxygen saturation calculated by the following method is 95% or less, on the metal substrate, An insulating layer forming step of forming an insulating layer by applying the polyimide resin composition, and the surface roughness Ra of the insulating layer is 30 nm or less.
<Calculation method of relative dissolved oxygen saturation>
First, using a dissolved oxygen saturated solvent in which air is bubbled for 30 minutes or more in a solvent contained in the polyimide resin composition, the measured value of the dissolved oxygen amount of the solvent in which no oxygen is dissolved is 0, and the dissolved oxygen saturated solvent The dissolved oxygen meter is calibrated so that the measured value of the dissolved oxygen amount becomes 100. Next, using the calibrated dissolved oxygen meter, the relative value of the dissolved oxygen amount of the reference polyimide resin composition in which the polyimide resin composition was allowed to stand for 1 hour or more in the atmosphere, and the degassing that degassed the polyimide resin composition. The relative value of the dissolved oxygen amount of the gas polyimide resin composition is measured. And the relative value of the dissolved oxygen amount of the said deaeration polyimide resin composition when the relative value of the dissolved oxygen amount of the said reference | standard polyimide resin composition is set to 100% is made into a relative dissolved oxygen saturation rate.

Here, the bubbles in the liquid are in a state where the gas remains in a gaseous state and is mixed in the liquid. This foam is not only mixed from the outside, but is very often generated from the liquid. On the other hand, dissolved gas means a gas dissolved in a liquid, which cannot be seen with eyes like bubbles. The present invention removes the “dissolved gas” in the liquid.
The amount of gas dissolved in the liquid varies depending on the type of liquid, temperature and pressure, and the wetted material, and dissolved gas above the saturation amount appears as bubbles. That is, even if the liquid is free of bubbles, bubbles are generated when the temperature, pressure, or the like changes. On the other hand, even if bubbles are present in the liquid, if the temperature is a predetermined temperature or pressure, or if the dissolved amount of the gas is less than the saturation value, the bubbles are not dissolved in the liquid. That is, it is not sufficient to simply remove bubbles, and it is important to remove dissolved gas.

  Therefore, when the polyimide resin composition is in contact with the atmosphere for a sufficient amount of time and the air is constantly dissolved in the polyimide resin composition, a dissolved gas above the saturation amount is generated as a bubble with a slight change in pressure or temperature. It is expected that However, when the dissolved gas amount of the polyimide resin composition in a state where air is constantly dissolved is 100%, when the dissolved gas amount of the polyimide resin composition is about 95%, the pressure and temperature change. Since it does not immediately exceed the saturation amount of the dissolved gas, generation of bubbles can be suppressed.

  With respect to the dissolved gas, in the situation where the polyimide resin composition is in contact with the atmosphere, most of the gas dissolved in the polyimide resin composition is nitrogen or oxygen (the amount in the atmosphere is next to oxygen) Argon is less than 1/20 of oxygen). Nitrogen is an inert gas and is difficult to measure, but oxygen is measurable. In addition, for many solvents, the ratio of the solubility of oxygen and nitrogen in the solvent at the same temperature and pressure is 1.4 to 2.0 (oxygen is easier to dissolve), and the partial pressure of nitrogen in the atmosphere Is about 3.7 times higher than the partial pressure of oxygen. From Henry's law, it is considered that nitrogen is dissolved about 1.9 to 2.7 times that of oxygen when in contact with the atmosphere. This ratio is constant in the state where the pressure is not high as long as the type of the solvent is the same, and even if the type of the solvent is changed, the fluctuation range is not so large as about 1.9 to 2.7 times. By determining the amount, it is possible to estimate the amount of dissolved gas that combines nitrogen and oxygen.

  It is difficult to measure the absolute value of dissolved oxygen in a solvent other than water. Therefore, in the present invention, the relative value (relative dissolved oxygen saturation) is evaluated based on the dissolved oxygen amount of the dissolved oxygen saturated solvent in which air is bubbled for 30 minutes or more in the solvent contained in the polyimide resin composition.

The manufacturing method of the substrate for thin film elements of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic sectional view showing an example of a thin film element substrate manufactured by the method for manufacturing a thin film element substrate of the present invention. In the present invention, after the polyimide resin composition is degassed so that the relative dissolved oxygen saturation calculated by a predetermined method is 95% or less, the polyimide resin composition is applied on the metal substrate, and the imide is obtained by heat treatment. As shown in FIG. 1, the insulating layer 3 is formed on the metal base 2. At this time, the insulating layer 3 having a surface roughness Ra of 30 nm or less is formed. In this way, the thin film element substrate 1 is obtained.

When an insulating layer is formed by applying a polyimide resin composition, a skin layer is formed on the surface of the coating film when the polyimide resin composition is applied and dried, and it is difficult for the solvent and water to evaporate, It may become difficult to detach. Therefore, if bubbles are included in the polyimide resin composition or a gas is dissolved in the polyimide resin composition, an insulating layer that encloses the bubbles is formed.
In contrast, in the present invention, since the polyimide resin composition is deaerated before forming the insulating layer, bubbles in the insulating layer can be reduced. In particular, since the polyimide resin composition is deaerated so that the relative dissolved oxygen saturation calculated by a predetermined method is 95% or less, not only micrometer-order bubbles but also nanometer-order bubbles are reduced in the insulating layer. can do. Thereby, it is possible to form an insulating layer having a surface roughness Ra of 30 nm or less and excellent surface smoothness. Moreover, even when unevenness exists on the surface of the metal base, the unevenness on the surface of the metal base can be flattened by forming an insulating layer on the metal base, and the surface of the thin film element substrate can be smoothed. Can improve sex. Therefore, a thin film element having good characteristics can be obtained by using the thin film element substrate manufactured according to the present invention.

  FIG. 2 is a schematic cross-sectional view showing another example of a thin film element substrate manufactured by the method for manufacturing a thin film element substrate of the present invention. In the present invention, it is preferable to form an adhesion layer 4 containing an inorganic compound on the insulating layer 3 as illustrated in FIG.

  In the present invention, the adhesion layer is formed by vapor-depositing an inorganic compound, and since the film thickness is thin, when the insulating layer is inferior in surface smoothness, the surface smoothness of the adhesion layer formed on the insulating layer However, if the insulating layer is excellent in surface smoothness as described above, the surface smoothness of the adhesion layer formed on the insulating layer is also good. Therefore, even when the adhesion layer is formed on the insulating layer, it is possible to prevent deterioration of characteristics of the thin film element.

  In the present invention, when the adhesion layer is formed on the insulating layer, the adhesion with the thin film element portion can be improved. Therefore, even when moisture or heat is applied during the manufacture of the thin film element portion and the dimensions of the insulating layer change, peeling or cracks may occur in the members constituting the thin film element portion, such as the electrodes and semiconductor layers constituting the TFT It can be prevented from occurring.

In addition, according to the present invention, since the permeation of moisture and oxygen can be reduced by the metal substrate, the deterioration of the thin film element portion due to moisture and oxygen can be suppressed, and the humidity in the element can be maintained and the humidity can be changed. It is possible to suppress the deterioration of characteristics due to.
Furthermore, since a metal base material is generally excellent in thermal conductivity, heat dissipation can be imparted to the thin film element substrate. That is, the thin film element substrate has a high moisture barrier property and can quickly conduct or radiate heat. For example, when a thin film element substrate is used for an organic EL element, adverse effects due to heat generated by the organic EL element during light emission can be suppressed, and the light emission characteristics can be stably maintained over a long period of time. It is possible to achieve uniform light emission without any problems, shorten the lifetime, and reduce element breakdown.
Moreover, since the intensity | strength of the board | substrate for thin film elements can be raised by having a metal base material, durability can be improved.

The substrate for a thin film element manufactured according to the present invention is used, for example, as follows. FIG. 3A to FIG. 5B are schematic cross-sectional views showing an example of a TFT including a thin film element substrate manufactured by the method for manufacturing a thin film element substrate of the present invention.
The TFT 10 illustrated in FIG. 3A includes a TFT having a top gate / bottom contact structure, and includes a source electrode 12S, a drain electrode 12D, and a semiconductor layer 11 formed on the adhesion layer 4 of the thin film element substrate 1. A gate insulating film 14 formed on the source electrode 12S, the drain electrode 12D and the semiconductor layer 11, and a gate electrode 13G formed on the gate insulating film 14.
The TFT 10 illustrated in FIG. 3B includes a TFT having a top gate / top contact structure. The semiconductor layer 11, the source electrode 12 </ b> S, and the drain electrode 12 </ b> D formed on the adhesion layer 4 of the thin film element substrate 1. A gate insulating film 14 formed on the semiconductor layer 11, the source electrode 12S and the drain electrode 12D, and a gate electrode 13G formed on the gate insulating film 14.
The TFT 10 illustrated in FIG. 4A includes a TFT having a bottom gate / bottom contact structure, and covers the gate electrode 13G formed on the adhesion layer 4 of the thin film element substrate 1 and the gate electrode 13G. , The source electrode 12S and the drain electrode 12D and the semiconductor layer 11 formed on the gate insulating film 14, and the protective film formed on the source electrode 12S and the drain electrode 12D and the semiconductor layer 11. 15.
The TFT 10 illustrated in FIG. 4B includes a TFT having a bottom gate / top contact structure, and covers the gate electrode 13G formed on the adhesion layer 4 of the thin film element substrate 1 and the gate electrode 13G. The gate insulating film 14 formed on the gate insulating film 14, the semiconductor layer 11, the source electrode 12S and the drain electrode 12D formed on the gate insulating film 14, and the protective film formed on the semiconductor layer 11, the source electrode 12S and the drain electrode 12D. 15.
A TFT 10 illustrated in FIG. 5A includes a TFT having a coplanar structure, a semiconductor layer 11 formed on the adhesion layer 4 of the thin film element substrate 1, and a source formed on the semiconductor layer 11. It has an electrode 12S and a drain electrode 12D, a gate insulating film 14 formed on the semiconductor layer 11, and a gate electrode 13G formed on the gate insulating film 14.
The TFT 10 illustrated in FIG. 5B also includes a TFT having a coplanar structure, and includes a gate electrode 13G formed on the adhesion layer 4 of the thin film element substrate 1 and a gate formed on the gate electrode 13G. An insulating film 14, a semiconductor layer 11 formed on the gate insulating film 14, a source electrode 12S and a drain electrode 12D formed on the semiconductor layer 11, and a protective film 15 formed on the semiconductor layer 11 are provided. is doing.

  Hereinafter, each process in the manufacturing method of the board | substrate for thin film elements of this invention is demonstrated.

1. Degassing step The degassing step in the present invention is a step of degassing the polyimide resin composition so that the relative dissolved oxygen saturation calculated by the following method is 95% or less.
<Calculation method of relative dissolved oxygen saturation>
First, using a dissolved oxygen saturated solvent in which air is bubbled for 30 minutes or more in a solvent contained in the polyimide resin composition, the measured value of the dissolved oxygen amount of the solvent in which no oxygen is dissolved is 0, and the dissolved oxygen saturated solvent The dissolved oxygen meter is calibrated so that the measured value of the dissolved oxygen amount becomes 100. Next, using the calibrated dissolved oxygen meter, the relative value of the dissolved oxygen amount of the reference polyimide resin composition in which the polyimide resin composition was allowed to stand for 1 hour or more in the atmosphere, and the degassing that degassed the polyimide resin composition. The relative value of the dissolved oxygen amount of the gas polyimide resin composition is measured. And the relative value of the dissolved oxygen amount of the said deaeration polyimide resin composition when the relative value of the dissolved oxygen amount of the said reference | standard polyimide resin composition is set to 100% is made into a relative dissolved oxygen saturation rate.

  Hereinafter, degassing of the polyimide resin composition and the polyimide resin composition will be described.

(1) Polyimide resin composition The polyimide resin composition used for this invention contains a polyimide component and a solvent.
As a polyimide component, any of a polyimide and a polyimide precursor may be sufficient. Specifically, a polyimide having a structure represented by the following formula (1) and a polyimide precursor having a structure represented by the following formulas (2) and (3) are exemplified.

(In the formula (1) ~ (3), R 1 is a tetravalent organic group, R ² is a divalent organic group, ^{R 3} is a hydrogen atom or a monovalent organic group, R ¹ together repeated, R ² and R ³ may be the same or different, and n is a natural number of 1 or more.)

  Moreover, about Formula (3), although it is left-right asymmetric, what differs in the left-right direction may be contained in one polymer molecular chain.

  As a polyimide component in this invention, you may use only the polymer which has only each structure of said Formula (1), Formula (2), and Formula (3), and said Formula (1), Formula (2), and Formula ( A polymer having only each structure of 3) may be used by mixing, and one polymer molecular chain in which the structures of the above formulas (1), (2), and (3) are mixed is used. Also good.

In the above formulas (1) to (3), generally, R ¹ is a structure derived from tetracarboxylic dianhydride, and R ² is a structure derived from diamine.

As a method for producing the polyimide component used in the present invention, a conventionally known method can be applied. For example, as a method for forming a polyimide precursor having the structure represented by (2) above, (i) a method of synthesizing polyamic acid from acid dianhydride and diamine, or (ii) monovalent to acid dianhydride Examples include, but are not limited to, a method in which a diamino compound or a derivative thereof is reacted with a carboxylic acid of an ester acid or an amic acid monomer synthesized by reacting an alcohol, an amino compound, an epoxy compound, or the like.
Moreover, as a formation method of the polyimide precursor which has the structure represented by said (3), or the polyimide represented by said (1), the method of imidating the polyimide precursor represented by said (2) by heating Is mentioned.

Examples of the tetracarboxylic dianhydride applicable to the polyimide component in the present invention include ethylene tetracarboxylic dianhydride, butane tetracarboxylic dianhydride, cyclobutane tetracarboxylic dianhydride, and methylcyclobutane tetracarboxylic acid. Dianhydrides, aliphatic tetracarboxylic dianhydrides such as cyclopentanetetracarboxylic dianhydride; pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 2, 2 ', 3,3'-benzophenone tetracarboxylic dianhydride, 2,3', 3,4'-benzophenone tetracarboxylic dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride, 2,3 ′, 3,4′-biphenyltetracarboxylic dianhydride, , 2 ′, 6,6′-biphenyltetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) Propane dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane Dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1 , 1,1,3,3,3-hexafluoropropane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride 1,3-bis [ (3,4-dicarboxy) benzoyl] benzene dianhydride, 1,4-bis [(3,4-dicarboxy) benzoyl] benzene dianhydride, 2,2-bis {4- [4- (1, 2-dicarboxy) phenoxy] phenyl} propane dianhydride, 2,2-bis {4- [3- (1,2-dicarboxy) phenoxy] phenyl} propane dianhydride, bis {4- [4- ( 1,2-dicarboxy) phenoxy] phenyl} ketone dianhydride, bis {4- [3- (1,2-dicarboxy) phenoxy] phenyl} ketone dianhydride, 4,4′-bis [4- ( 1,2-dicarboxy) phenoxy] biphenyl dianhydride, 4,4′-bis [3- (1,2-dicarboxy) phenoxy] biphenyl dianhydride, bis {4- [4- (1,2- Dicarboxy) phenoxy] phenyl} Ton dianhydride, bis {4- [3- (1,2-dicarboxy) phenoxy] phenyl} ketone dianhydride, bis {4- [4- (1,2-dicarboxy) phenoxy] phenyl} sulfone Anhydride, bis {4- [3- (1,2-dicarboxy) phenoxy] phenyl} sulfone dianhydride, bis {4- [4- (1,2-dicarboxy) phenoxy] phenyl} sulfide dianhydride Bis {4- [3- (1,2-dicarboxy) phenoxy] phenyl} sulfide dianhydride, 2,2-bis {4- [4- (1,2-dicarboxy) phenoxy] phenyl} -1 , 1,1,3,3,3-hexafluoropropane dianhydride, 2,2-bis {4- [3- (1,2-dicarboxy) phenoxy] phenyl} -1,1,1,3 3,3-hexafluoropropane Water, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,1,1,3,3,3-hexafluoro-2,2-bis (2,3- or 3,4-di Carboxyphenyl) propane dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,2,3,4-benzenetetra Carboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, 1,2,7,8-phenanthrenetetracarboxylic Acid dianhydride, pyridinetetracarboxylic dianhydride, sulfonyldiphthalic anhydride, m-terphenyl-3,3 ′, 4,4′-tetracarboxylic dianhydride, p-terphenyl-3,3 ', 4,4'-tetracarboxylic acid Water, 9,9-bis- (trifluoromethyl) xanthenetetracarboxylic dianhydride, 9-phenyl-9- (trifluoromethyl) xanthenetetracarboxylic dianhydride, 12,14-diphenyl-12,14 -Bis (trifluoromethyl) -12H, 14H-5,7-dioxapentacene-2,3,9,10-tetracarboxylic dianhydride, 1,4-bis (3,4-dicarboxytrifluorophenoxy ) Tetrafluorobenzene dianhydride, 1,4-bis (trifluoromethyl) -2,3,5,6-benzenetetracarboxylic dianhydride, 1- (trifluoromethyl) -2,3,5,6 -Benzenetetracarboxylic dianhydride, p-phenylenebistrimellitic acid monoester dianhydride, p-biphenylenebistrimellitic acid monoester dianhydride, etc. Aromatic tetracarboxylic dianhydride, and the like.
These may be used alone or in combination of two or more.

On the other hand, a diamine component applicable to the polyimide component can also be used alone or in combination of two or more diamines. The diamine component used is p-phenylenediamine, m-phenylenediamine, o-phenylenediamine, 3,3′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl ether, 3,3′- Diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3, , 3′-diaminobenzophenone, 4,4′-diaminobenzophenone, 3,4′-diaminobenzophenone, 3,3′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane, 3,4′-diaminodiphenylmethane, 2,2 -Di (3-aminophenyl) Propane, 2,2-di (4-aminophenyl) propane, 2- (3-aminophenyl) -2- (4-aminophenyl) propane, 2,2-di (3-aminophenyl) -1,1, 1,3,3,3-hexafluoropropane, 2,2-di (4-aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 2- (3-aminophenyl) -2 -(4-aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 1,1-di (3-aminophenyl) -1-phenylethane, 1,1-di (4-amino) Phenyl) -1-phenylethane, 1- (3-aminophenyl) -1- (4-aminophenyl) -1-phenylethane, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis ( 4-aminophenoxy) benzene, 1, -Bis (3-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminobenzoyl) benzene, 1,3-bis (4-aminobenzoyl) benzene, , 4-bis (3-aminobenzoyl) benzene, 1,4-bis (4-aminobenzoyl) benzene, 1,3-bis (3-amino-α, α-dimethylbenzyl) benzene, 1,3-bis ( 4-amino-α, α-dimethylbenzyl) benzene, 1,4-bis (3-amino-α, α-dimethylbenzyl) benzene, 1,4-bis (4-amino-α, α-dimethylbenzyl) benzene 1,3-bis (3-amino-α, α-ditrifluoromethylbenzyl) benzene, 1,3-bis (4-amino-α, α-ditrifluoromethylbenzyl) benzene, 1,4- Bis (3-amino-α, α-ditrifluoromethylbenzyl) benzene, 1,4-bis (4-amino-α, α-ditrifluoromethylbenzyl) benzene, 2,6-bis (3-aminophenoxy) benzo Nitrile, 2,6-bis (3-aminophenoxy) pyridine, 4,4′-bis (3-aminophenoxy) biphenyl, 4,4′-bis (4-aminophenoxy) biphenyl, bis [4- (3- Aminophenoxy) phenyl] ketone, bis [4- (4-aminophenoxy) phenyl] ketone, bis [4- (3-aminophenoxy) phenyl] sulfide, bis [4- (4-aminophenoxy) phenyl] sulfide, bis [4- (3-Aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ether, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-Aminophenoxy) phenyl] propane, 2,2-bis [3- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 2,2-bis [4 -(4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 1,3-bis [4- (3-aminophenoxy) benzoyl] benzene, 1,3-bis [ 4- (4-aminophenoxy) benzoyl] benzene, 1,4-bis [4- (3-aminophenoxy) benzoyl] benzene, 1,4-bis [4- (4-aminophenoxy) benzo L] benzene, 1,3-bis [4- (3-aminophenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-aminophenoxy) -α, α-dimethylbenzyl] Benzene, 1,4-bis [4- (3-aminophenoxy) -α, α-dimethylbenzyl] benzene, 1,4-bis [4- (4-aminophenoxy) -α, α-dimethylbenzyl] benzene, 4,4′-bis [4- (4-aminophenoxy) benzoyl] diphenyl ether, 4,4′-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] benzophenone, 4,4′-bis [4- (4-Amino-α, α-dimethylbenzyl) phenoxy] diphenylsulfone, 4,4′-bis [4- (4-aminophenoxy) phenoxy] diphenylsulfone, 3,3′-dia Mino-4,4′-diphenoxybenzophenone, 3,3′-diamino-4,4′-dibiphenoxybenzophenone, 3,3′-diamino-4-phenoxybenzophenone, 3,3′-diamino-4-biphenoxy Benzophenone, 6,6′-bis (3-aminophenoxy) -3,3,3 ′, 3′-tetramethyl-1,1′-spirobiindane, 6,6′-bis (4-aminophenoxy) -3, Aromatic amines such as 3,3 ′, 3′-tetramethyl-1,1′-spirobiindane; 1,3-bis (3-aminopropyl) tetramethyldisiloxane, 1,3-bis (4-aminobutyl) ) Tetramethyldisiloxane, α, ω-bis (3-aminopropyl) polydimethylsiloxane, α, ω-bis (3-aminobutyl) polydimethylsiloxane, bis (aminomethyl) A Bis (2-aminoethyl) ether, bis (3-aminopropyl) ether, bis (2-aminomethoxy) ethyl] ether, bis [2- (2-aminoethoxy) ethyl] ether, bis [2- ( 3-aminoprotoxy) ethyl] ether, 1,2-bis (aminomethoxy) ethane, 1,2-bis (2-aminoethoxy) ethane, 1,2-bis [2- (aminomethoxy) ethoxy] ethane, 1,2-bis [2- (2-aminoethoxy) ethoxy] ethane, ethylene glycol bis (3-aminopropyl) ether, diethylene glycol bis (3-aminopropyl) ether, triethylene glycol bis (3-aminopropyl) ether , Ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diamino Of 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane, 1,12-diaminododecane Such aliphatic amines; 1,2-diaminocyclohexane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, 1,2-di (2-aminoethyl) cyclohexane, 1,3-di (2-aminoethyl) ) Cyclohexane, 1,4-di (2-aminoethyl) cyclohexane, bis (4-aminocyclohexyl) methane, 2,6-bis (aminomethyl) bicyclo [2.2.1] heptane, 2,5- And alicyclic diamines such as bis (aminomethyl) bicyclo [2.2.1] heptane. Examples of guanamines include acetoguanamine, benzoguanamine, and the like, and some or all of the hydrogen atoms on the aromatic ring of the diamine are fluoro group, methyl group, methoxy group, trifluoromethyl group, or trifluoromethoxy group. Diamines substituted with substituents selected from the group can also be used.
Furthermore, depending on the purpose, any one or two or more of the ethynyl group, benzocyclobuten-4′-yl group, vinyl group, allyl group, cyano group, isocyanate group, and isopropenyl group serving as a crosslinking point, Even if it introduce | transduces into some or all of the hydrogen atoms on the aromatic ring of diamine as a substituent, it can be used.

In order to improve the heat resistance and insulation of the polyimide resin composition in the present invention, the polyimide component preferably contains an aromatic skeleton. The polyimide resin obtained by heat curing a polyimide component containing an aromatic skeleton is derived from its rigid and highly planar skeleton, and is excellent in heat resistance and insulation in a thin film, and is low outgas. This is because it is preferably used for the insulating layer of the thin film element substrate of the present invention.
Moreover, as for the polyimide component, it is desirable for the part derived from an acid dianhydride to have an aromatic structure, and also the part derived from a diamine to contain an aromatic structure. Therefore, the structure derived from the diamine component is also preferably a structure derived from an aromatic diamine. In particular, it is preferable that all of the part derived from the acid dianhydride and the part derived from the diamine are a wholly aromatic polyimide or a wholly aromatic polyimide precursor containing an aromatic structure.

Here, the wholly aromatic polyimide precursor is a polyimide precursor obtained by copolymerization of an aromatic acid component and an aromatic amine component, or polymerization of an aromatic acid / amino component, and a derivative thereof. The aromatic acid component is a compound in which all four acid groups forming the polyimide skeleton are substituted on the aromatic ring, and the aromatic amine component is the two amino groups forming the polyimide skeleton. Both are compounds substituted on the aromatic ring, and the aromatic acid / amino component is a compound in which both the acid group and amino group forming the polyimide skeleton are substituted on the aromatic ring. However, as is clear from the specific examples of the raw material aromatic dianhydride and aromatic diamine, it is not necessary that all acid groups or amino groups exist on the same aromatic ring.
For the above reasons, the polyimide precursor should have a copolymerization ratio of the aromatic acid component and / or aromatic amine component as large as possible when the final polyimide resin is required to have heat resistance and dimensional stability. preferable. Specifically, the proportion of the aromatic acid component in the acid component constituting the repeating unit of the imide structure is preferably 50 mol% or more, particularly preferably 70 mol% or more, and the amine component constituting the repeating unit of the imide structure The proportion of the aromatic amine component in the total is preferably 40 mol% or more, particularly preferably 60 mol% or more, and is preferably a wholly aromatic polyimide or a wholly aromatic polyimide precursor.

Further, the portion of the ring structure after imidization contained in the above formulas (1) and (3) is more solvent than the portion of the carboxylic acid before imidation contained in the above formulas (2) and (3). Therefore, it is desirable to use a highly soluble polyimide precursor containing a large number of structures before imidization. It is desirable that the acid anhydride-derived carboxyl group (or its ester) is 50% or more of the total, more preferably 75% or more, and all of the polyamic acid (and derivatives thereof) comprising the above formula (2) Preferably there is.
In addition, the polyamic acid (and derivatives thereof) composed of the above formula (2) is particularly preferably a polyamic acid in which R ³ is all hydrogen atoms because of ease of synthesis and high solubility in an alkali developer. preferable.

In the present invention, among them, 33 mol% or more of R ^{1 in} the polyimide component having the structure represented by the above formulas (1) to (3) may be any structure represented by the following formula. preferable. It is because it has the merit that it becomes a polyimide resin which is excellent in heat resistance and shows a low linear thermal expansion coefficient.

(In formula (4), a is a natural number of 0 or 1 or more, A is a single bond (biphenyl structure), an oxygen atom (ether bond), or an ester bond. The linking group is bonded to the 2, 3 or 3, 4 position of the aromatic ring as viewed from the bonding site of the aromatic ring.)

  In the present invention, in particular, when the polyimide component having the structure represented by the above (1) to (3) includes the structure represented by the above formula (4), the polyimide resin exhibits low hygroscopic expansion. Furthermore, there is also an advantage that it is easily available on the market and is low cost.

The polyimide component having the above-described structure can form a polyimide resin exhibiting high heat resistance and a low linear thermal expansion coefficient. Therefore, the content of the structure represented by the above formula is preferably closer to 100 mol% in R ^{1 in} the above formulas (1) to (3), but at least in the above formulas (1) to (3). it may be contained 33% or more of R ^1. Among them, the content of the structure represented by the above formula is preferably 50 mol% or more, more preferably 70 mol% or more, among R ^{1 in} the above formulas (1) to (3).

  In the present invention, examples of the structure of the acid dianhydride that makes the polyimide resin moisture-absorbing include those represented by the following formula (5).

(In the formula (5), a is a natural number of 0 or 1 or more, A is a single bond (biphenyl structure), an oxygen atom (ether bond), or an ester bond. (The acid anhydride skeleton (—CO—O—CO—) is bonded to the 2, 3 or 3, 4 position of the aromatic ring as viewed from the bonding site of the adjacent aromatic ring.)

  In the above formula (5), the acid dianhydride in which A is a single bond (biphenyl structure) or an oxygen atom (ether bond) includes 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2 , 3,3 ′, 4′-biphenyltetracarboxylic dianhydride, 2,3,2 ′, 3′-biphenyltetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, etc. Is mentioned. These are preferable from the viewpoint of reducing the hygroscopic expansion coefficient and from the viewpoint of expanding the selectivity of the diamine.

  In the above formula (5), a phenyl ester acid dianhydride in which A is an ester bond is particularly preferable from the viewpoint of reducing the moisture absorption of the polyimide resin. For example, an acid dianhydride represented by the following formula may be mentioned. Specific examples include p-phenylenebistrimellitic acid monoester dianhydride, p-biphenylenebistrimellitic acid monoester dianhydride, and the like. These are particularly preferable from the viewpoint of reducing the hygroscopic expansion coefficient and from the viewpoint of expanding the selectivity of the diamine.

(Wherein, a is a natural number of 0 or 1 or more. The acid anhydride skeleton (—CO—O—CO—) is a 2, 3-position or 3 of the aromatic ring as viewed from the bonding site of the adjacent aromatic ring. , Binds to position 4.)

  In the case of the tetracarboxylic dianhydride having a small hygroscopic expansion coefficient as described above, a wide variety of diamines to be described later can be selected.

  As the tetracarboxylic dianhydride used in combination, a tetracarboxylic dianhydride having at least one fluorine atom as represented by the following formula can be used. When tetracarboxylic dianhydride into which fluorine is introduced is used, the hygroscopic expansion coefficient of the finally obtained polyimide resin is lowered. The tetracarboxylic dianhydride having at least one fluorine atom preferably has a fluoro group, a trifluoromethyl group, or a trifluoromethoxy group. Specific examples include 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride. However, when the polyimide precursor contained as the polyimide component has a skeleton containing fluorine, the polyimide precursor tends to be difficult to dissolve in a basic aqueous solution, and a resist or the like is used in the state of the polyimide precursor. When patterning is performed, it may be necessary to perform development with a mixed solution of an organic solvent such as alcohol and a basic aqueous solution.

  Here, the selected diamine is preferably an aromatic diamine from the viewpoint of heat resistance, that is, low outgassing, but in a range not exceeding 60 mol%, preferably 40 mol% of the total of the diamine depending on the desired physical properties. A non-aromatic diamine such as an aliphatic diamine or a siloxane diamine may be used.

Moreover, in the said polyimide component, it is preferable that 33 mol% or more among R < ² > in said Formula (1)-(3) is either structure represented by a following formula.

(R ¹¹ is a divalent organic group, an oxygen atom, a sulfur atom, or a sulfone group, and R ¹² and R ¹³ are a monovalent organic group or a halogen atom.)

When the polyimide component contains any structure of the above formula, it is derived from these rigid skeletons and exhibits low linear thermal expansion and low hygroscopic expansion. Furthermore, there is also an advantage that it is easily available on the market and is low cost.
When it has the above structure, the heat resistance of the polyimide resin is improved and the linear thermal expansion coefficient is reduced. Therefore, the closer to 100 mol% of R ^{2 in} the above formulas (1) to (3), the better, but it is preferable that at least 33% or more of R ^{2 in} the above formulas (1) to (3) is contained. Good. Among them, the content of the structure represented by the above formula is preferably 50 mol% or more, more preferably 70 mol% or more, of R ^{2 in} the above formula (1).

  From the viewpoint of making the polyimide resin have a lower hygroscopic expansion, those represented by the following formulas (6-1) to (6-3) and (7) are preferable as the structure of the diamine.

(In formulas (6-2) to (6-3), two amino groups may be bonded to the same aromatic ring.
In Formula (7), a is 0 or a natural number of 1 or more, and the amino group is bonded to the meta position or the para position with respect to the bond between the benzene rings. Further, some or all of the hydrogen atoms on the aromatic ring may be substituted with a substituent selected from a fluoro group, a methyl group, a methoxy group, a trifluoromethyl group, or a trifluoromethoxy group. )

  Specific examples of diamines represented by the above formulas (6-1) to (6-3) include p-phenylenediamine, m-phenylenediamine, 1,4-diaminonaphthalene, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, 2,7-diaminonaphthalene, 1,4-diaminoanthracene and the like can be mentioned.

  Specific examples of the diamine represented by the above formula (7) include 2,2′-dimethyl-4,4′-diaminobiphenyl, 2,2′-ditrifluoromethyl-4,4′-diaminobiphenyl, 3 3,3′-dichloro-4,4′-diaminobiphenyl, 3,3′-dimethoxy-4,4′-diaminobiphenyl, 3,3′-dimethyl-4,4′-diaminobiphenyl, and the like.

  In addition, when fluorine is introduced as a substituent of the aromatic ring, the hygroscopic expansion coefficient of the polyimide resin can be reduced. For example, examples of the structure in which fluorine is introduced in the diamine represented by the above formula (7) include those represented by the following formula. However, polyimide precursors containing fluorine, especially polyamic acid, are difficult to dissolve in a basic aqueous solution. When a low outgas photosensitive polyimide insulating layer is partially formed on a substrate, the insulating layer is processed during the processing. It may be necessary to develop with a mixed solution with an organic solvent such as alcohol.

  When the polyimide resin composition used in the present invention is imparted with photosensitivity and used as a photosensitive polyimide resin composition, the film thickness is 1 μm in order to increase the sensitivity and obtain a pattern shape that accurately reproduces the mask pattern. In this case, it is preferable that the transmittance is at least 5% or more with respect to the exposure wavelength, and it is more preferable that the transmittance is 15% or more.

In addition, when exposure is performed using a high-pressure mercury lamp, which is a general exposure light source, a transmittance with respect to an electromagnetic wave having a wavelength of at least 436 nm, 405 nm, and 365 nm is formed on a film having a thickness of 1 μm. Is preferably 5% or more, more preferably 15%, and still more preferably 50% or more.
That the transmittance | permeability of a polyimide component is high with respect to an exposure wavelength means that there is little light loss, and a highly sensitive photosensitive polyimide resin composition can be obtained.

In order to increase the transmittance as the polyimide component, it is desirable to use an acid dianhydride into which fluorine is introduced as an acid dianhydride or an acid dianhydride having an alicyclic skeleton. However, if an acid dianhydride having an alicyclic skeleton is used, the heat resistance may be lowered and the low outgassing property may be impaired.
In the present invention, in order to increase the transmittance, the use of an aromatic acid dianhydride into which fluorine is introduced as the acid dianhydride reduces the hygroscopic expansion while maintaining heat resistance (because it is aromatic). It is further preferable because it can be performed.

As the tetracarboxylic dianhydride having at least one fluorine atom used in the present invention, the above-mentioned tetracarboxylic dianhydride having a fluorine atom can be used, among which a fluoro group, a trifluoromethyl group, Alternatively, it preferably has a trifluoromethoxy group. Specific examples include 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride.
However, a polyimide precursor having a skeleton containing fluorine tends to be difficult to dissolve in a basic aqueous solution, and when patterning using a resist or the like in the state of the polyimide precursor, an organic solvent such as alcohol and the like It may be necessary to perform development with a mixed solution with a basic aqueous solution.

  Also, rigid acid dianhydrides such as pyromellitic acid anhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, etc. If used, the linear thermal expansion coefficient of the finally obtained polyimide resin is reduced, but it tends to hinder the improvement of transparency, so it may be used in combination while paying attention to the copolymerization ratio.

In order to increase the transmittance as the polyimide component, it is desirable to use a diamine introduced with fluorine as a diamine or a diamine having an alicyclic skeleton. However, if a diamine having an alicyclic skeleton is used, the heat resistance may be lowered and the low outgassing property may be impaired.
In order to increase the transmittance, it is more preferable to use an aromatic diamine into which fluorine is introduced as the diamine because it is possible to reduce hygroscopic expansion while maintaining heat resistance (since it is aromatic).

Specific examples of the aromatic diamine into which fluorine has been introduced include those having the above-mentioned structure into which fluorine has been introduced. More specifically, 2,2′-ditrifluoromethyl-4 , 4'-diaminobiphenyl, 2,2-di (3-aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 2,2-di (4-aminophenyl) -1,1 , 1,3,3,3-hexafluoropropane, 2- (3-aminophenyl) -2- (4-aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 1,3 -Bis (3-amino-α, α-ditrifluoromethylbenzyl) benzene, 1,3-bis (4-amino-α, α-ditrifluoromethylbenzyl) benzene, 1,4-bis (3-amino-α , Α-Ditrifluoromethylbenzyl Benzene, 1,4-bis (4-amino-α, α-ditrifluoromethylbenzyl) benzene, 2,2-bis [3- (3-aminophenoxy) phenyl] -1,1,1,3,3 Examples include 3-hexafluoropropane and 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane.
However, polyimide precursors containing fluorine, especially polyamic acid, are difficult to dissolve in a basic aqueous solution. When a low outgas photosensitive polyimide insulating layer is partially formed on a substrate, the insulating layer is processed during the processing. It may be necessary to develop with a mixed solution with an organic solvent such as alcohol.

The parts of the ring structure after imidization contained in the above formulas (1) and (3) are the carboxylic acids before imidation contained in the polyimide precursors represented by the above formulas (3) and (2), respectively. Since the transmittance tends to be lower than that of the portion, it is desirable to use a highly transparent polyimide precursor containing a large number of structures before imidization. It is desirable that the acid anhydride-derived carboxyl group (or ester thereof) is 50% or more of the total, more preferably 75% or more, and all of the polyimide precursor represented by the above formula (2), that is, polyamic An acid (and its derivatives) is preferred.
Moreover, when developing using an alkali developing solution, the solubility with respect to an alkali developing solution can be changed with the residual amount of the carboxylic acid part before imidation contained in said Formula (2) and (3). From the viewpoint of increasing the development speed, it is desirable to use a highly soluble polyimide precursor containing a large number of structures before imidization, and R ³ in the above formulas (2) and (3) are all hydrogen atoms. It is preferable that However, when the developing speed is too high and the solubility of the pattern remaining portion is too high, the one in which imidization has progressed is used, or R ³ in the above formulas (2) and (3) is a monovalent organic group Can be introduced to lower the dissolution rate.

  On the other hand, when a diamine having a siloxane skeleton such as 1,3-bis (3-aminopropyl) tetramethyldisiloxane is used as the diamine, the adhesion to the substrate is improved or the elastic modulus of the polyimide resin is decreased. The glass transition temperature can be lowered.

The weight average molecular weight of the polyimide component used in the present invention is preferably in the range of 3,000 to 1,000,000, and more preferably in the range of 5,000 to 500,000, depending on the use. More preferably, it is in the range of 10,000 to 500,000. When the weight average molecular weight is less than 3,000, it is difficult to obtain sufficient strength when a coating film or film is used. In addition, the strength of the film is reduced when a heat treatment or the like is performed to obtain a polymer such as a polyimide resin. On the other hand, when the weight average molecular weight exceeds 1,000,000, the viscosity increases and the solubility decreases, so that it is difficult to obtain a coating film or film having a smooth surface and a uniform film thickness.
The molecular weight used here refers to a value in terms of polystyrene by gel permeation chromatography (GPC), may be the molecular weight of the polyimide precursor itself, or after chemical imidization treatment with acetic anhydride or the like. Things can be used.

The content of the polyimide component used in the present invention is 50% by weight or more based on the entire solid content of the polyimide resin composition from the viewpoint of film physical properties of the pattern to be obtained, particularly film strength and heat resistance. Among these, 70% by weight or more is preferable.
In addition, solid content of a polyimide resin composition is all components other than a solvent, and a liquid monomer component is also contained in solid content.

  Various general-purpose solvents can be used as a solvent for dissolving, dispersing or diluting the polyimide precursor or polyimide. Moreover, when a polyimide resin composition contains a polyimide precursor, you may use the solution obtained by the synthesis reaction of polyamic acid as it is, and may mix other components there as needed.

  Examples of general-purpose solvents that can be used include ethers such as diethyl ether, tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol dimethyl ether, and propylene glycol diethyl ether; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, Glycol monoethers such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether (so-called cellosolves); ketones such as methyl ethyl ketone, acetone, methyl isobutyl ketone, cyclopentanone, cyclohexanone; acetic acid Ethyl, butyl acetate, vinegar n-propyl, i-propyl acetate, n-butyl acetate, i-butyl acetate, acetate esters of the above glycol monoethers (for example, methyl cellosolve acetate, ethyl cellosolve acetate), methoxypropyl acetate, ethoxypropyl acetate, dimethyl oxalate, Esters such as methyl lactate and ethyl lactate; alcohols such as ethanol, propanol, butanol, hexanol, cyclohexanol, ethylene glycol, diethylene glycol, glycerin; methylene chloride, 1,1-dichloroethane, 1,2-dichloroethylene, 1-chloropropane Halogenated hydrocarbons such as 1-chlorobutane, 1-chloropentane, chlorobenzene, bromobenzene, o-dichlorobenzene, m-dichlorobenzene; Amides such as muamide, N, N-diethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide; Pyrrolidones such as N-methylpyrrolidone; Lactones such as γ-butyrolactone; Sulfoxides such as dimethylsulfoxide And other organic polar solvents, and further include aromatic hydrocarbons such as benzene, toluene and xylene, and other organic nonpolar solvents. These solvents are used alone or in combination.

  Among them, N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylformamide, N, N-diethylacetamide, N, N-dimethylmethoxyacetamide, dimethyl sulfoxide, hexa Polar solvents such as methylphosphoamide, N-acetyl-2-pyrrolidone, pyridine, dimethyl sulfone, tetramethylene sulfone, dimethyltetramethylene sulfone, diethylene glycol dimethyl ether, cyclopentanone, γ-butyrolactone, α-acetyl-γ-butyrolactone It is mentioned as a suitable thing.

  When the polyimide resin composition is degassed under vacuum, the vapor pressure of the solvent at room temperature is preferably 25,000 Pa or less, and more preferably in the range of 10,000 Pa to 1 Pa, particularly 1,000 Pa. It is preferable to be within the range of 10 Pa. This is because if the vapor pressure of the solvent is high, the solvent evaporates during degassing and the concentration and viscosity of the polyimide resin composition may change. Moreover, if the vapor pressure of the solvent is too low, it is difficult to remove the solvent when the polyimide resin composition is dried.

  The polyimide resin composition may be a photosensitive polyimide resin composition. The photosensitive polyimide resin composition can be obtained using a known method. For example, an ethylenic double bond is introduced into the carboxyl group of polyamic acid by an ester bond or an ionic bond, and a photoradical initiator is mixed into the resulting polyimide precursor to form a solvent-developed negative photosensitive polyimide resin composition. Can do. In addition, for example, a naphthoquinone diazide compound is added to polyamic acid or a partially esterified product thereof to obtain an alkali developing positive photosensitive polyimide resin composition, or an nifedipine compound is added to polyamic acid to form an alkali developing negative photosensitive polyimide resin. A photobase generator can be added to polyamic acid, such as a composition, to obtain an alkali developing negative photosensitive polyimide resin composition.

  In these photosensitive polyimide resin compositions, 15% to 35% of a photosensitizing component is added to the weight of the polyimide component. Therefore, even if it heats at 300 to 400 degreeC after pattern formation, the residue derived from a photosensitivity provision component remains in a polyimide. Since these residues cause the linear thermal expansion coefficient and the hygroscopic expansion coefficient to increase, the use of the photosensitive polyimide resin composition compared to the case of using the non-photosensitive polyimide resin composition. Reliability tends to decrease. However, the photosensitive polyimide resin composition obtained by adding a photobase generator to polyamic acid can form a pattern even if the amount of the photobase generator as an additive is 15% or less. Is the most preferable as a photosensitive polyimide resin composition applicable to the present invention because there are few decomposition residues derived from additives, there is little deterioration in properties such as linear thermal expansion coefficient and hygroscopic expansion coefficient, and there is also little outgas.

  It is preferable that the polyimide resin composition be developable with a basic aqueous solution from the viewpoint of ensuring the safety of the working environment and reducing the process cost when the insulating layer is partially formed on the metal substrate. Since the basic aqueous solution can be obtained at a low cost and the waste liquid treatment cost and the facility cost for ensuring work safety are low, production at a lower cost is possible.

  The polyimide resin composition may contain additives such as a leveling agent, a plasticizer, a surfactant, and an antifoaming agent as necessary.

(2) Deaeration of polyimide resin composition The method of degassing the polyimide resin composition is particularly limited as long as the relative dissolved oxygen saturation calculated by a predetermined method can be 95% or less. For example, vacuum degassing, ultrasonic degassing, degassing using a porous film, degassing using a non-porous film, and the like can be given. Vacuum degassing is a method of reducing the solubility of dissolved gas by depressurizing the polyimide resin composition. Ultrasonic degassing is a method of driving out dissolved gas by molecular vibration by applying ultrasonic vibration to the polyimide resin composition. Degassing using a porous membrane or non-porous membrane is a method of removing dissolved gas in the polyimide resin composition by applying gas permeation to the membrane and gas concentration difference and pressure difference in the polyimide resin composition. It is. These degassing methods may be used alone or in combination. Among these, vacuum degassing, combined use of vacuum degassing and ultrasonic degassing, and degassing using an in-line porous film or non-porous film are preferable.

The pressure at the time of vacuum degassing is not particularly limited as long as the dissolved oxygen in the polyimide resin composition can be removed, and may be appropriately set according to the vapor pressure of the solvent used in the polyimide resin composition. preferable. Especially, it is preferable that the pressure in the case of vacuum deaeration is 1.1 times or more of the vapor pressure of the solvent used for a polyimide composition. Specifically, the pressure during vacuum degassing is preferably in the range of 50,000 Pa to 1 Pa, and more preferably in the range of 10,000 Pa to 1 Pa, and particularly in the range of 1,000 Pa to 1 Pa. preferable. This is because if the pressure is high, the effect of deaeration is difficult to obtain, and if the pressure is low, the solvent volatilizes and the concentration and viscosity of the polyimide resin composition change, which adversely affects the formation of the insulating layer.
The time for vacuum degassing is not particularly limited as long as the dissolved oxygen in the polyimide resin composition can be removed, and can be, for example, about 1 to 60 minutes.

  The frequency of ultrasonic waves at the time of ultrasonic degassing is not particularly limited as long as dissolved oxygen in the polyimide resin composition can be removed, but is preferably about 15 kHz to 400 kHz.

The temperature during ultrasonic deaeration is not particularly limited as long as the dissolved oxygen in the polyimide resin composition can be removed, but is preferably in the range of 0 ° C. to 100 ° C., and in particular, 0 The temperature is preferably in the range of 80 ° C to 80 ° C, particularly in the range of 0 ° C to 50 ° C. When the temperature is low, the degassing efficiency is lowered when the viscosity of the polyimide resin composition is high, and when the temperature is high, characteristics such as storage stability of the polyimide resin composition may be changed.
In addition, the time for ultrasonic deaeration is not particularly limited as long as the dissolved oxygen in the polyimide resin composition can be removed, and can be, for example, about 1 to 60 minutes.

  For deaeration using a porous membrane or a non-porous membrane, for example, a deaeration device manufactured by ERC can be used.

  In the present invention, the deaeration process is preferably performed immediately before an insulating layer forming process described later. Here, the reason why bubbles are included in the insulating layer is related to the bubbles contained in the polyimide resin composition as described above, the gas dissolved in the polyimide resin composition, and the water contained in the polyimide resin composition. It is thought to do. If the degassed polyimide resin composition is allowed to stand for an arbitrary time, bubbles may be generated in the polyimide resin composition, gas may be dissolved in the polyimide resin composition, or the polyimide resin composition may absorb moisture. There is. Therefore, in order to effectively reduce the bubbles included in the insulating layer, it is preferable to perform a deaeration process immediately before the insulating layer forming process.

  The term “immediately before” refers to the case where the time from degassing the polyimide resin composition to applying the polyimide resin composition is 60 minutes or less. The above time is preferably 20 minutes or less, more preferably 10 minutes or less.

In this step, the polyimide resin composition is degassed so that the relative dissolved oxygen saturation calculated by the following method is 95% or less.
<Calculation method of relative dissolved oxygen saturation>
First, using a dissolved oxygen saturated solvent in which air is bubbled for 30 minutes or more in a solvent contained in the polyimide resin composition, the measured value of the dissolved oxygen amount of the solvent in which no oxygen is dissolved is 0, and the dissolved oxygen saturated solvent The dissolved oxygen meter is calibrated so that the measured value of the dissolved oxygen amount becomes 100. Next, using the calibrated dissolved oxygen meter, the relative value of the dissolved oxygen amount of the reference polyimide resin composition in which the polyimide resin composition was allowed to stand for 1 hour or more in the atmosphere, and the degassing that degassed the polyimide resin composition. The relative value of the dissolved oxygen amount of the gas polyimide resin composition is measured. And the relative value of the dissolved oxygen amount of the said deaeration polyimide resin composition when the relative value of the dissolved oxygen amount of the said reference | standard polyimide resin composition is set to 100% is made into a relative dissolved oxygen saturation rate.

An oxygen sensor such as “B-506” (manufactured by Iijima Electronics Co., Ltd.) can be used as the dissolved oxygen meter used for the measurement of the dissolved oxygen amount.
The relative dissolved oxygen saturation is 95% or less, preferably 90% or less, and more preferably 85% or less.

2. Insulating layer forming step The insulating layer forming step in the present invention is a step of forming an insulating layer by applying the polyimide resin composition on a metal substrate.
Hereinafter, the method for forming the insulating layer, the insulating layer, and the metal substrate will be described separately.

(1) Forming method of insulating layer The method of applying the polyimide resin composition on the metal substrate is not particularly limited as long as it is a method capable of obtaining an insulating layer with good smoothness. It is appropriately selected according to the viscosity of the composition. As a method for applying the polyimide resin composition, for example, a spin coating method, a die coating method, a dip coating method, a bar coating method, a gravure printing method, a screen printing method, or the like can be used.
After application of the polyimide resin composition, the fluidity of the film can be increased and the smoothness can be improved by heating to a temperature higher than the glass transition temperature of the polyimide precursor.

After application of the polyimide resin composition, the solvent is removed by heat treatment. At this time, when the polyimide resin composition contains a polyimide precursor, the polyimide precursor is also imidized by heat treatment.
When imidating a polyimide precursor, the preferable temperature range of heat processing is about 200 degreeC-400 degreeC normally. When the heat treatment temperature is lower than 200 ° C., the progress of imidization does not proceed completely, resulting in insufficient physical properties. On the other hand, the physical properties of the final cured film tend to improve when the heat treatment temperature becomes high. However, when the temperature exceeds 400 ° C., other component members may be adversely affected. It is desirable to determine the imidization temperature in consideration of the above. Further, prior to the heat treatment, preheating may be performed at 50 ° C. to 200 ° C. lower than the heat treatment temperature. Specifically, the heat treatment can be performed at 250 to 350 ° C. for 10 to 120 minutes.
This heat treatment may be any method as long as it is a known method, and specific examples thereof include a circulating oven in an air or nitrogen atmosphere, heating with a hot plate, and the like.

  Moreover, when forming an insulating layer partially on a metal base material, the method of processing directly by the printing method, the photolithographic method, a laser etc. can be used as the formation method. As a photolithography method, for example, after applying a polyimide resin composition, a resist layer is formed on the coating film, a resist pattern is formed by a photolithography method, and then the coating film on the pattern opening is formed using the pattern as a mask. After removing the resist pattern, the resist pattern is removed and the polyamic acid is imidized; the coating film is developed at the same time when the resist pattern is formed, and then the resist pattern is removed and the polyamic acid is imidized; the insulating layer After forming, a resist pattern is formed on the insulating layer, the insulating layer is etched along the pattern by a wet etching method or a dry etching method, and then the resist pattern is removed; a metal substrate, an insulating layer, and a metal substrate Prepared a laminated body, and one metal substrate of the laminated body And a method of removing the metal pattern after etching the insulating layer using the pattern as a mask; and a method of forming the pattern of the insulating layer directly on the metal substrate using the photosensitive polyimide resin composition. . Examples of the printing method include methods using known printing techniques such as gravure printing, flexographic printing, screen printing, and ink jet method.

(2) Insulating layer The surface roughness Ra of the insulating layer is 30 nm or less when measured in an area of 50 μm × 50 μm, and preferably 30 nm or less when measured in an area of 100 μm × 100 μm.
The surface roughness Ra is a value measured using an atomic force microscope (AFM) or a scanning white interferometer. For example, when measuring in an area of 50 μm × 50 μm, Ra can be calculated using an AFM or a scanning white interferometer. Further, when measuring in an area of 100 μm × 100 μm, Ra can be calculated using a scanning white interferometer. Specifically, when measuring using AFM, using Nanoscope V multimode (Veeco), in tapping mode, cantilever: MPP11100, scanning range: 50 μm × 50 μm, scanning speed: 0.5 Hz, surface Ra can be obtained by imaging the shape and calculating the average deviation from the center line of the roughness curve calculated from the obtained image. Further, when measuring using a scanning white interferometer, using New View 5000 (manufactured by Zygo), objective lens: 100 times, zoom lens: 2 times, Scan Length: 15 μm, 50 μm × 50 μm Roughness calculated from the image obtained by imaging the surface shape in the range, or imaging the surface shape in the range of 100 μm × 100 μm with the objective lens: 100 ×, the zoom lens: 1 ×, and the Scan Length: 15 μm Ra can be obtained by calculating an average deviation from the center line of the curve.

  The insulating layer contains polyimide, and preferably contains polyimide as a main component. In general, polyimide has water absorption. Since many semiconductor materials used in TFTs, thin film solar cells, EL devices, etc. are vulnerable to moisture, the insulating layer is water-absorbing in order to reduce moisture inside the device and achieve high reliability in the presence of moisture. It is preferable that the property is relatively small. One index of water absorption is the hygroscopic expansion coefficient. Therefore, the smaller the hygroscopic expansion coefficient of the insulating layer, the better. Specifically, it is preferably in the range of 0 ppm /% RH to 15 ppm /% RH, more preferably 0 ppm /% RH to 12 ppm /% RH. Within the range, more preferably within the range of 0 ppm /% RH to 10 ppm /% RH. The smaller the hygroscopic expansion coefficient, the smaller the water absorption. Moreover, if the hygroscopic expansion coefficient of the insulating layer is within the above range, the water absorption of the insulating layer can be sufficiently reduced, the thin film element substrate can be easily stored, and the manufacturing process of the thin film element is simplified. Furthermore, the smaller the hygroscopic expansion coefficient, the better the dimensional stability. If the hygroscopic expansion coefficient of the insulating layer is large, the thin film element substrate warps as the humidity increases due to the difference in expansion coefficient from the metal base material, which has a hygroscopic expansion coefficient that is almost zero. May decrease. Therefore, it is preferable that the hygroscopic expansion coefficient is small even when a wet process is performed in the manufacturing process of the thin film element.

The hygroscopic expansion coefficient is measured as follows. First, a film having only an insulating layer is produced. The method for producing the insulating layer film is as follows. The insulating layer film is prepared on a heat-resistant film (Upilex S 50S (manufactured by Ube Industries)) or a glass substrate, and then the insulating layer film is peeled off or the insulating layer is formed on the metal substrate. There is a method of obtaining an insulating layer film by etching a metal after producing a film. Next, the obtained insulating layer film is cut into a width of 5 mm and a length of 20 mm to obtain an evaluation sample. The hygroscopic expansion coefficient is measured by a humidity variable mechanical analyzer (Thermo Plus TMA8310 (manufactured by Rigaku Corporation)). For example, the temperature is kept constant at 25 ° C., the humidity is first set to a stable state in an environment of 15% RH, the state is maintained for about 30 minutes to 2 hours, and the humidity of the measurement site is set to 20%. RH and hold for 30 minutes to 2 hours until the sample is stable. Thereafter, the humidity is changed to 50% RH, and the difference between the sample length when the humidity becomes stable and the sample length when the humidity becomes stable at 20% RH is expressed as a change in humidity (in this case, 50-20). 30) and the value divided by the sample length is the hygroscopic expansion coefficient (CHE). At the time of measurement, the tensile weight is set to 1 g / 25000 μm ² so that the weight per cross-sectional area of the evaluation sample becomes the same.

Further, the linear thermal expansion coefficient of the insulating layer is preferably 15 ppm / ° C. or less, more preferably 10 ppm / ° C. or less, more preferably from the viewpoint of dimensional stability. Is 5 ppm / ° C. or less. The closer the linear thermal expansion coefficient between the insulating layer and the metal substrate, the more the warpage of the thin film element substrate is suppressed, and the interface between the insulating layer and the metal substrate when the thermal environment of the thin film element substrate changes. This reduces stress and improves adhesion. Moreover, it is preferable that the substrate for a thin film element does not warp in a temperature environment in the range of 0 ° C. to 100 ° C. for handling, but the insulating layer and the metal base material because the linear thermal expansion coefficient of the insulating layer is large. If the linear thermal expansion coefficients differ greatly, the thin film element substrate warps due to a change in the thermal environment.
The thin film element substrate is not warped when the thin film element substrate is cut into a strip shape having a width of 10 mm and a length of 50 mm, and one short side of the obtained sample is placed on a horizontal and smooth table. When fixed, it means that the flying distance from the surface of the other short side of the sample is 1.0 mm or less.

  Specifically, the linear thermal expansion coefficient of the insulating layer is preferably in the range of 0 ppm / ° C. to 30 ppm / ° C., more preferably in the range of 0 ppm / ° C. to 25 ppm / ° C., from the viewpoint of dimensional stability. More preferably, it is in the range of 0 ppm / ° C to 18 ppm / ° C, particularly preferably in the range of 0 ppm / ° C to 12 ppm / ° C, and most preferably in the range of 0 ppm / ° C to 7 ppm / ° C.

The linear thermal expansion coefficient is measured as follows. First, a film having only an insulating layer is produced. The method for producing the insulating layer film is as described above. Next, the obtained insulating layer is cut into a width of 5 mm and a length of 20 mm to obtain an evaluation sample. The linear thermal expansion coefficient is measured by a thermomechanical analyzer (for example, Thermo Plus TMA8310 (manufactured by Rigaku Corporation)). The measurement conditions were a heating rate of 10 ° C./min, a tensile load of 1 g / 25,000 μm ² so that the weight per cross-sectional area of the evaluation sample was the same, and an average linear thermal expansion within a range of 100 ° C. to 200 ° C. The coefficient is the linear thermal expansion coefficient (CTE).

The hygroscopic expansion coefficient and linear thermal expansion coefficient of the insulating layer can be controlled, for example, by appropriately selecting the structure of the polyimide component.
Generally, the linear thermal expansion coefficient of a metal base material, that is, the linear thermal expansion coefficient of a metal is determined to some extent, so the linear thermal expansion coefficient of the insulating layer is determined according to the linear thermal expansion coefficient of the metal base material to be used, and the polyimide component It is preferable to select the structure as appropriate. Further, the linear thermal expansion coefficient of the metal base material is determined according to the linear thermal expansion coefficient of the thin film element portion, the linear thermal expansion coefficient of the insulating layer is determined according to the linear thermal expansion coefficient of the metal base material, and the polyimide component It is preferable to select the structure as appropriate.

The insulating layer has an insulating property. Specifically, the volume resistance of the insulating layer is preferably 1.0 × 10 ⁹ Ω · m or more, more preferably 1.0 × 10 ¹⁰ Ω · m or more, and 1.0 × 10 ^11. More preferably, it is Ω · m or more.
The volume resistance can be measured by a method based on standards such as JIS K6911, JIS C2318, and ASTM D257.

  The insulating layer may be formed on the entire surface of the metal substrate, or may be partially formed on the metal substrate. That is, the metal substrate exposed region where the insulating layer and the adhesion layer are not present and the metal substrate is exposed may be provided on the surface of the metal substrate where the insulating layer and the adhesion layer are formed. In the case where such a metal base material exposed region is provided, it becomes possible to directly attach the sealing member and the metal base material when the organic EL element is produced using the thin film element substrate. It becomes possible to prevent moisture from entering the element more firmly. In addition, by selectively forming the sealing portion in the exposed area of the metal base material, it becomes possible to divide the organic EL elements in a plane or to seal them in a multi-faceted state with high productivity. There is an advantage that an element can be manufactured. Further, the metal substrate exposed region can also be a through hole for penetrating the insulating layer and the adhesion layer and electrically conducting the metal substrate.

  When the insulating layer is partially formed on the metal substrate, the insulating layer 3 is formed excluding at least the outer edge portion of the metal substrate 2 as illustrated in FIGS. 6 (a) and 6 (b). It may be. 6A is a cross-sectional view taken along line AA in FIG. 6B, and the adhesion layer is omitted in FIG. 6B. When an organic EL element or the like is produced using a thin film element substrate, if the insulating layer is formed on the entire surface of the metal base and the end of the insulating layer is exposed, polyimide generally exhibits hygroscopicity. In addition, moisture may enter the element from the end face of the insulating layer during manufacturing or driving. This moisture deteriorates the device performance or changes the dimensions of the insulating layer. Therefore, an insulating layer is not formed on the outer edge portion of the metal substrate, and it is preferable to reduce as much as possible the portion where the insulating layer containing polyimide is directly exposed to the outside air.

In the present invention, that the insulating layer is partially formed on the metal base means that the insulating layer is not formed on the entire surface of the metal base.
The insulating layer may be formed on the entire surface of the metal substrate except for the outer edge of the metal substrate, or may be further formed in a pattern on the metal substrate except for the outer edge of the metal substrate. Good.

  The thickness of the insulating layer is not particularly limited as long as it can satisfy the above-mentioned characteristics. Specifically, it is preferably in the range of 1 μm to 1000 μm, more preferably in the range of 1 μm to 200 μm. More preferably, it exists in the range of 1 micrometer-100 micrometers. This is because if the thickness of the insulating layer is too thin, the insulation cannot be maintained, or it is difficult to flatten the irregularities on the surface of the metal substrate. In addition, if the insulating layer is too thick, flexibility is reduced, it becomes excessively heavy, drying during film formation becomes difficult, and the amount of material used increases, resulting in an increase in cost. . Furthermore, in the case of providing a heat dissipation function to the thin film element substrate manufactured according to the present invention, if the insulating layer is thick, the thermal conductivity is lowered because polyimide has lower thermal conductivity than metal.

(3) Metal substrate The linear thermal expansion coefficient of the metal substrate is preferably in the range of 0 ppm / ° C to 25 ppm / ° C, more preferably 0 ppm / ° C to 18 ppm / ° C, from the viewpoint of dimensional stability. More preferably, it is in the range of 0 ppm / ° C. to 12 ppm / ° C., particularly preferably in the range of 0 ppm / ° C. to 7 ppm / ° C.
In addition, about the measuring method of the said linear thermal expansion coefficient, it is the same as the measuring method of the linear thermal expansion coefficient of the said insulating layer except cut | disconnecting a metal base material to width 5mm * length 20mm and making it an evaluation sample.

  Moreover, it is preferable that a metal base material has oxidation resistance. This is because a high temperature treatment may be performed during the formation of the thin film element portion. In particular, when the thin film element is a TFT and the TFT has an oxide semiconductor layer, the metal substrate preferably has oxidation resistance because annealing is performed at a high temperature in the presence of oxygen.

  The metal material constituting the metal substrate is not particularly limited as long as it satisfies the above-mentioned characteristics. For example, aluminum, copper, copper alloy, phosphor bronze, stainless steel (SUS), gold, gold alloy Nickel, nickel alloy, silver, silver alloy, tin, tin alloy, titanium, iron, iron alloy, zinc, molybdenum and the like. Among these, SUS is preferable when applied to a large element. SUS is excellent in oxidation resistance and heat resistance, and has a smaller coefficient of linear thermal expansion than copper and has excellent dimensional stability. Further, SUS304 has an advantage that it is particularly easy to obtain, and SUS430 has an advantage that it is easy to obtain and the linear thermal expansion coefficient is smaller than SUS304. On the other hand, considering the linear thermal expansion coefficients of the metal substrate and the thin film element portion, titanium and invar having a lower linear thermal expansion coefficient than SUS430 are preferable from the viewpoint of the linear thermal expansion coefficient. However, it is desirable to select not only the linear thermal expansion coefficient but also taking into consideration the workability of the foil and the cost due to the oxidation resistance, heat resistance, malleability and ductility of the metal substrate.

Moreover, when performing the metal surface treatment process which performs a chemical | medical solution process to a metal base so that it may mention later, it is preferable that a metal base is an alloy type. This is because a variety of characteristics can be imparted depending on the composition as compared with a pure metal. In addition, the alloy-based metal base is usually produced by rolling, and as described later, since organic components such as rolling oil used in the rolling process are attached, chemical treatment is useful. is there. In particular, the metal substrate is preferably composed mainly of iron. This is because a wide variety of compositions have been developed for metal base materials mainly composed of iron, and it is possible to select them according to the characteristics required for the application. Moreover, the metal base material which has iron as a main component has high chemical | medical solution tolerance, and various chemical processing can be applied. Furthermore, the metal base material which has iron as a main component also has an advantage that it is excellent in physical properties such as heat resistance, oxidation resistance and low expansion.
In addition, that a metal base material has iron as a main component means the case where the iron content in a metal base material is 30 mass% or more.
In addition to iron, the metal components contained in the metal substrate include chromium (Cr), nickel (Ni), molybdenum (Mo), manganese (Mn), copper (Cu), titanium (Ti), niobium (Nb), Examples include vanadium (V), tungsten (W), aluminum (Al), cobalt (Co), tin (Sn), and the like. Nonmetallic components contained in the metal substrate include carbon (C), silicon (Si), phosphorus (P) sulfur (S), nitrogen (N), oxygen (O), boron (B) and the like. Can be mentioned.
Specific examples of the metal substrate include carbon steel, nickel chrome steel, nickel chrome molybdenum steel, chrome steel, chrome molybdenum steel, manganese molybdenum steel, SUS, Invar, 42 alloy, and Kovar. Among these, SUS is preferable as described above.

The contact angle with respect to the solvent contained in the polyimide resin composition on the surface of the metal substrate is preferably 30 ° or less, more preferably 20 ° or less, and still more preferably 10 ° or less.
Here, when an insulating layer is formed by applying a polyimide resin composition on a metal substrate, uniform application is difficult when the polyimide resin composition is applied. In some cases, the uniformity of the film decreases, and pinholes and craters may be formed in the film. In particular, when unevenness is present on the surface of the metal substrate, there is a risk that a decrease in the uniformity of the film becomes significant.
On the other hand, when the contact angle with respect to the solvent contained in the polyimide resin composition on the surface of the metal substrate is a predetermined range and is small, the wettability of the polyimide resin composition with respect to the metal substrate is good, and the metal substrate When the polyimide resin composition is applied on top, it can be applied uniformly, and the occurrence of repellency and foaming can be suppressed. Therefore, the uniformity of the coating film is improved, and further, pinholes and craters are reduced, and an insulating layer having excellent surface smoothness can be formed.

The contact angle is a measurement of the contact angle with the solvent contained in the polyimide resin composition using a contact angle measuring device (DM500 model, manufactured by Kyowa Interface Science Co., Ltd.). 2 seconds after dropping).
Since the surface treatment method in which the metal substrate surface has a predetermined contact angle will be described later, description thereof is omitted here.

In addition, the ratio of the amount of carbon (C) to the total amount of elements detected by X-ray photoelectron spectroscopy (XPS) on the surface of the metal substrate is preferably 0.25 or less, and preferably 0.20 or less. Is more preferable. When the ratio of the amount of carbon (C) to the total detected elements is within the above range, the contact angle with respect to the solvent contained in the polyimide resin composition on the surface of the metal substrate is reduced, and the polyimide resin composition on the metal substrate is reduced. This is because the applicability of can be improved. The carbon component is considered to be derived from organic components such as rolling oil used in the production of the metal substrate and organic components contained in the atmosphere, and a large amount of carbon component remains on the surface of the metal substrate. And it is thought that it has a bad influence on the contact angle with respect to the solvent contained in the polyimide resin composition on the surface of a metal base material, and the applicability | paintability of the polyimide resin composition on a metal base material.
In the measurement of X-ray photoelectron spectroscopy (XPS), for example, using Quantum2000 (manufactured by ULVAC-PHI), the X-ray conditions are Al mono 200 μmφ × 30 W 15 kV, the photoelectron uptake angle is 45 °, and charge neutralization is performed. By using Ion / Electron 20 μA, the measured values of each element can be obtained.

The surface roughness Ra of the metal substrate is usually larger than the surface roughness Ra of the insulating layer and adhesion layer described later, and is, for example, about 50 nm to 200 nm.
The method for measuring the surface roughness is the same as the method for measuring the surface roughness of the insulating layer.

  The thickness of the metal substrate is not particularly limited as long as it can satisfy the above-described characteristics, and is appropriately selected depending on the application. The thinner the metal substrate, the more flexible it becomes. On the other hand, the thicker the metal substrate, the better the gas barrier properties against oxygen and water vapor and the thermal diffusion in the surface direction. Specifically, the thickness of the metal substrate is preferably in the range of 1 μm to 1000 μm, more preferably in the range of 1 μm to 200 μm, and still more preferably in the range of 1 μm to 100 μm. If the thickness of the metal base is too thin, the gas barrier property against oxygen or water vapor may be reduced, the heat dissipation function may not be sufficiently exhibited, or the strength of the thin film element substrate may be reduced. Moreover, when the thickness of a metal base material is too thick, flexibility will fall, it will become heavy, and cost will become high.

The shape of the metal substrate is not particularly limited, and may be, for example, a foil shape or a plate shape. As illustrated in FIG. 7, the shape of the metal substrate 2 is uneven on the contact surface with air. The shape which has this may be sufficient.
When the metal substrate has irregularities on the contact surface with air, the thermal diffusion becomes good and the heat dissipation can be improved. As a method for forming irregularities, for example, a method of directly embossing, etching, sandblasting, frosting, stamping, etc. on the surface of a metal substrate, a method of forming an irregularity pattern using a photoresist or the like, Examples thereof include a plating method and a method of bonding a metal layer having a foil shape or a plate shape and a metal layer having irregularities on the surface. In the case of embossing, for example, a rolling roll having irregularities on the surface may be used. In the case of an etching process, a chemical | medical agent is selected according to the kind of metal base material. In the case of a method of laminating a metal layer such as a foil or plate and a metal layer having irregularities on the surface, for example, the metal layers are joined together by brazing, welding, soldering, or an adhesive such as an epoxy resin The metal layers can be bonded to each other via. In this case, the metal layer having a foil shape or a plate shape and the metal layer having irregularities on the surface may be made of the same metal material or different metal materials. Of these, embossing and etching are preferably used from the viewpoint of cost.
The size and shape of the unevenness are not particularly limited as long as the surface area of the contact surface of the metal substrate with the air can be increased. The width, height, pitch, and the like of the unevenness are appropriately selected according to the type of metal base material, the use of the substrate for the thin film element, and the like, and a range suitable for heat conduction can be obtained by simulation, for example.

  As a method for producing the metal substrate, a general method can be used, which is appropriately selected according to the type of the metal material, the thickness of the metal substrate, and the like. When the metal substrate is a metal foil, the metal foil may be a rolled foil or an electrolytic foil, but a rolled foil is preferred because of its good gas barrier properties.

3. Metal substrate surface treatment process In this invention, it is preferable to have a metal substrate surface treatment process which performs a chemical | medical solution process to the said metal base material before the said insulating layer formation process. In a metal base material that has not been subjected to any treatment, an organic component contained in the atmosphere may adhere to the surface of the metal base material after the metal base material is manufactured and used. Metal substrates include rolled foil and electrolytic foil. In the case of rolled foil, organic components such as rolling oil used in the manufacturing process of the rolled foil, particularly the rolling process of the metal, adhere to the surface of the metal substrate. Sometimes. Thus, when many organic substance components have adhered to the metal base material surface, there exists a possibility that the wettability of the polyimide resin composition with respect to a metal base material may fall. On the other hand, by performing the metal substrate surface treatment step, the organic component remaining on the metal substrate surface can be removed, the wettability of the polyimide resin composition to the metal substrate is improved, and the metal substrate When the polyimide resin composition is applied on the top, it can be applied uniformly, and further, the occurrence of repelling and foaming can be suppressed.

The method for the chemical treatment of the metal substrate is not particularly limited as long as the contact angle with respect to the solvent contained in the polyimide resin composition on the surface of the metal substrate can be within a predetermined range. , Alkaline cleaning, electric field degreasing, pickling and the like.
Alkali cleaning is a method in which the surface of a metal substrate is eluted and washed by soaking in an alkaline chemical solution or by applying a paste-like alkaline cleaner. Gloss does not come out, but can be used for cheap and large products. Since the glossy portion will become frosted, alkali cleaning can be applied if the appearance is not a problem, such as to remove darkening due to welding burn.
Electrolytic degreasing is a method of making a smooth and glossy surface by eluting convex portions (micron level) on the surface of a metal substrate by conducting electricity (electrolysis) in a chemical solution. Since the dirt and impurities attached to the surface of the metal substrate are removed and the film is strengthened, the corrosion resistance can be improved. This is presumably because iron on the surface of the metal base material is first dissolved by electrolysis, so that metal components (for example, chromium) other than iron are relatively thick and the passive film becomes strong.
Pickling is a method in which the surface of a metal substrate is eluted and washed by soaking it in a strongly acidic chemical solution or by applying a paste-like acid detergent. Gloss does not come out, but can be used for cheap and large products. Pickling can be applied if the appearance is not a problem, for example, to remove darkening due to welding burns, because the glossy part will be frosted.

In this invention, it is preferable to perform a chemical | medical solution process so that the contact angle with respect to the solvent contained in the polyimide resin composition of the metal base material surface may fall. Specifically, it is preferable to perform a chemical treatment so that the contact angle with respect to the solvent contained in the polyimide resin composition on the surface of the metal substrate is 30 ° or less.
In addition, the contact angle with respect to the solvent contained in the polyimide resin composition on the surface of the metal substrate is as described above.

4). Adhesion layer formation process In this invention, you may have the adhesion layer formation process of forming the adhesion layer containing an inorganic compound on an insulating layer after the said insulating layer formation process.

  The inorganic compound constituting the adhesion layer is not particularly limited as long as it satisfies the above-described characteristics. For example, silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride, aluminum oxynitride, oxidation Examples thereof include chromium and titanium oxide. These may be used alone or in combination of two or more.

The adhesion layer may be a single layer or a multilayer.
When the adhesion layer is a multilayer film, a plurality of layers made of the above-described inorganic compound may be laminated, or a layer made of the above-mentioned inorganic compound and a layer made of metal may be laminated. The metal used in this case is not particularly limited as long as an adhesion layer satisfying the characteristics described below can be formed, and examples thereof include chromium, titanium, aluminum, and silicon.
When the adhesion layer is a multilayer film, the outermost layer of the adhesion layer is preferably a silicon oxide film. That is, it is preferable to form a thin film element portion on the silicon oxide film. This is because the silicon oxide film sufficiently satisfies the characteristics described later. The silicon oxide in this case is preferably SiO _x (X is in the range of 1.5 to 2.0).

  Among them, the adhesion layer 4 is formed on the insulating layer 3 as illustrated in FIG. 8 and is made of chromium, titanium, aluminum, silicon, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride, aluminum oxynitride, chromium oxide. It is preferable to have a first adhesion layer 4a made of at least one selected from the group consisting of titanium oxide and a second adhesion layer 4b made of silicon oxide and formed on the first adhesion layer 4a. This is because the adhesion between the insulating layer and the second adhesion layer can be enhanced by the first adhesion layer, and the adhesion between the insulation layer and the thin film element portion can be enhanced by the second adhesion layer. Moreover, it is because the 2nd contact | adherence layer which consists of silicon oxides fully satisfy | fills the below-mentioned characteristic.

  The method for forming the adhesion layer is not particularly limited as long as it is a method capable of forming a layer made of the above-described inorganic compound or a layer made of the above-mentioned metal. For example, DC (direct current) sputtering, RF (High frequency) magnetron sputtering method, plasma CVD (chemical vapor deposition) method, etc. can be mentioned. In particular, when a layer made of the above-described inorganic compound is formed and a layer containing aluminum or silicon is formed, it is preferable to use a reactive sputtering method. This is because a film having excellent adhesion to the insulating layer can be obtained.

The adhesion layer preferably has smoothness. The surface roughness Ra of the adhesion layer only needs to be smaller than the surface roughness Ra of the metal substrate, and is specifically preferably 25 nm or less, more preferably 10 nm or less. This is because if the surface roughness Ra of the adhesion layer is too large, characteristics of the thin film element may be deteriorated when the thin film element portion is produced on the thin film element substrate manufactured according to the present invention.
The method for measuring the surface roughness is the same as the method for measuring the surface roughness of the insulating layer.

The adhesion layer preferably has heat resistance. This is because a high temperature treatment may be performed during the formation of the thin film element portion. As the heat resistance of the adhesive layer, the 5% weight reduction temperature of the adhesive layer is preferably 300 ° C. or higher.
In addition, about the measurement of 5% weight reduction | decrease temperature, using a thermal analyzer (DTG-60 (made by Shimadzu Corp.)), atmosphere: nitrogen atmosphere, temperature range: 30 degreeC-600 degreeC, temperature increase rate: Thermogravimetric / differential heat (TG-DTA) measurement was performed at 10 ° C./min, and the temperature at which the weight of the sample decreased by 5% was defined as a 5% weight reduction temperature (° C.).

  The adhesion layer usually has an insulating property. This is because the thin film element substrate is required to have insulating properties.

  In the case where the thin film element is a TFT, the adhesion layer preferably prevents the impurity ions contained in the insulating layer from diffusing into the semiconductor layer of the TFT. Specifically, as the ion permeability of the adhesion layer, the iron (Fe) ion concentration is preferably 0.1 ppm or less, or the sodium (Na) ion concentration is preferably 50 ppb or less. In addition, as a measuring method of the density | concentration of Fe ion and Na ion, after sampling and extracting the layer formed on the contact | adherence layer, the method of analyzing by an ion chromatography method is used.

  The thickness of the adhesion layer is not particularly limited as long as it can satisfy the above-described characteristics, but specifically, it is preferably in the range of 1 nm to 500 nm. In particular, when the adhesion layer has the first adhesion layer and the second adhesion layer as described above, the second adhesion layer is thicker than the first adhesion layer, the first adhesion layer is relatively thin, and the second adhesion layer. Is preferably relatively thick. In this case, the thickness of the first adhesion layer is preferably in the range of 0.1 nm to 50 nm, more preferably in the range of 0.5 nm to 20 nm, and still more preferably in the range of 1 nm to 10 nm. The thickness of the second adhesion layer is preferably in the range of 10 nm to 500 nm, more preferably in the range of 50 nm to 300 nm, and still more preferably in the range of 80 nm to 120 nm. This is because if the thickness is too thin, sufficient adhesion may not be obtained, and if the thickness is too thick, cracks may occur in the adhesion layer.

  The adhesion layer may be formed on the entire surface of the metal substrate, or may be partially formed on the metal substrate. In particular, when the insulating layer is partially formed on the metal substrate, the adhesion layer 4 is also partially formed on the metal substrate 2 in the same manner as the insulating layer 3 as illustrated in FIG. It is preferable to do. This is because if an adhesion layer containing an inorganic compound is formed directly on the metal substrate, cracks or the like may occur in the adhesion layer. That is, it is preferable that the adhesion layer and the insulating layer have the same shape.

B. Next, a method for manufacturing a thin film element of the present invention will be described.
The thin film element manufacturing method of the present invention includes a thin film element portion forming step of forming a thin film element portion on the thin film element substrate manufactured by the above-described thin film element substrate manufacturing method. is there.

In the present invention, since the thin film element portion is formed on the thin film element substrate having excellent surface smoothness, a thin film element having excellent characteristics can be obtained.
In addition, since the thin film element substrate has a gas barrier property against oxygen and water vapor, it can suppress deterioration of the element performance due to moisture and oxygen, and also keeps the humidity in the element constant and suppresses deterioration of characteristics due to humidity change. be able to. Furthermore, since the substrate for a thin film element has not only a gas barrier property but also a heat dissipation property, for example, when an organic EL element is manufactured as a thin film element portion, the light emission characteristics can be stably maintained over a long period of time, and light emission can be achieved. It is possible to achieve uniform light emission with no unevenness, shorten the lifetime, and reduce element destruction.
In addition, when the adhesion layer is formed on the insulating layer in the thin film element substrate, the thin film element portion can be formed on the thin film element substrate with good adhesion, and moisture or heat is generated during the manufacture of the thin film element. In addition, even when the dimension of the insulating layer containing polyimide is changed, it is possible to prevent peeling or cracking from occurring in the member constituting the thin film element portion.

The “thin film element” refers to an electronic element having a functional layer with a thickness of 150 nm or less. That is, the “thin film element portion” refers to an electronic element portion having a functional layer having a thickness of 150 nm or less. The thickness of the functional layer is preferably 100 nm or less.
Examples of the functional layer include an insulating layer, an electrode layer, a semiconductor layer, a dielectric layer, an adhesion layer, and a seed layer. Among them, the functional layer is preferably an insulating layer, an electrode layer, a semiconductor layer, or a dielectric layer. This is because it is particularly preferable that these layers have high flatness because irregularities on the order of nanometers cause problems that seriously affect the operation of the device, such as disconnection, short circuit, and defects.
The functional layer may be formed directly on the thin film element substrate, or may be formed on the thin film element substrate via an intermediate layer. The intermediate layer is not particularly limited as long as it does not significantly change the surface roughness of the thin film element substrate.

  The thin film element substrate has been described in detail in the above section “A. Manufacturing Method of Thin Film Element Substrate”, and therefore the description thereof is omitted here. Hereafter, the thin film element part formation process in the manufacturing method of the thin film element of this invention is demonstrated.

  The thin film element portion forming step in the present invention is a step of forming the thin film element portion on the thin film element substrate manufactured by the above-described method for manufacturing a thin film element substrate.

The thin film element portion is not particularly limited as long as it is an electronic element portion having the functional layer, and examples thereof include TFTs, thin film solar cells, EL elements, RFID (Radio Frequency IDentification: IC tags), memories, and the like. It is done.
Since the TFT is described in the section “C. TFT manufacturing method” described later, a description thereof is omitted here.
Examples of the thin film solar cell include CIGS (Cu (copper), In (indium), Ga (gallium), Se (selenium)) solar cells, organic thin film solar cells, and the like.
The EL element may be either an organic EL element or an inorganic EL element.
A method for forming the thin film element portion is appropriately selected according to the type of the thin film element portion, and a general method can be adopted.

C. Next, a method for manufacturing the TFT of the present invention will be described.
The TFT manufacturing method of the present invention is characterized by having a TFT forming step of forming a TFT on the thin film element substrate manufactured by the above-described thin film element substrate manufacturing method.

  FIG. 3A to FIG. 5B are schematic cross-sectional views showing examples of the TFT of the present invention. The TFT 10 illustrated in FIG. 3A includes a TFT having a top gate / bottom contact structure, and the TFT 10 illustrated in FIG. 3B includes a TFT having a top gate / top contact structure. The TFT 10 illustrated in FIG. 4A includes a TFT having a bottom gate / bottom contact structure, and the TFT 10 illustrated in FIG. 4B includes a TFT having a bottom gate / top contact structure. The TFT 10 illustrated in FIGS. 5A and 5B includes a TFT having a coplanar structure. Note that each configuration of the TFT shown in FIGS. 3A to 5B has been described in the above section “A. Method for Manufacturing Substrate for Thin Film Element”, and therefore description thereof is omitted here.

In the present invention, since the TFT is formed on the thin film element substrate having excellent surface smoothness, a TFT having good electrical performance can be obtained.
In addition, since the substrate for a thin film element has a gas barrier property against oxygen or water vapor, when an organic EL display device is manufactured using a TFT, deterioration of element performance due to moisture or oxygen can be suppressed. When electronic paper is manufactured, the humidity in the element can be kept constant and deterioration of display characteristics due to a change in humidity can be suppressed. Furthermore, since the substrate for a thin film element has not only a gas barrier property but also a heat dissipation property, when an organic EL display device is manufactured using TFTs, the light emission characteristics can be stably maintained over a long period of time, and light emission can be achieved. It is possible to achieve uniform light emission with no unevenness, shorten the lifetime, and reduce element destruction.
In addition, when an adhesion layer is formed on an insulating layer in a thin film element substrate, a TFT can be formed on the thin film element substrate with good adhesion, and moisture and heat are added during the manufacture of the TFT to form polyimide. Even when the dimensions of the insulating layer containing s are changed, it is possible to prevent the electrodes and the semiconductor layer from being separated or cracked.

  The thin film element substrate has been described in detail in the above section “A. Manufacturing Method of Thin Film Element Substrate”, and therefore the description thereof is omitted here. Hereinafter, the TFT formation process in the TFT manufacturing method of the present invention will be described.

1. TFT formation process The TFT formation process in this invention is a process of forming TFT on the board | substrate for thin film elements manufactured by the manufacturing method of the board | substrate for thin film elements mentioned above.

  Examples of the TFT structure include a top gate structure (forward stagger type), a bottom gate structure (reverse stagger type), and a coplanar type structure. In the case of the top gate structure (forward stagger type) and the bottom gate structure (reverse stagger type), a top contact structure and a bottom contact structure can be further exemplified. These structures are appropriately selected according to the type of semiconductor layer constituting the TFT.

  The semiconductor layer constituting the TFT is not particularly limited as long as it can be formed on the thin film element substrate. For example, silicon, an oxide semiconductor, or an organic semiconductor is used.

As the silicon, polysilicon or amorphous silicon can be used.
Examples of the oxide semiconductor include zinc oxide (ZnO), titanium oxide (TiO), magnesium zinc oxide (Mg _x Zn _1-x O), cadmium zinc oxide (Cd _x Zn _1-x O), and cadmium oxide (CdO). ), Indium oxide (In ₂ O ₃ ), gallium oxide (Ga ₂ O ₃ ), tin oxide (SnO ₂ ), magnesium oxide (MgO), tungsten oxide (WO), InGaZnO-based, InGaSnO-based, InGaZnMgO-based, InAlZnO-based InFeZnO, InGaO, ZnGaO, and InZnO can be used.
Examples of organic semiconductors include π-electron conjugated aromatic compounds, chain compounds, organic pigments, and organosilicon compounds. More specifically, pentacene, tetracene, thiophen oligomer derivatives, phenylene derivatives, phthalocyanine compounds, polyacetylene derivatives, polythiophene derivatives, cyanine dyes and the like can be mentioned.

Especially, it is preferable that a semiconductor layer is an oxide semiconductor layer which consists of the above-mentioned oxide semiconductor. Although the electrical characteristics of an oxide semiconductor change due to the influence of water and oxygen, the substrate for a thin film element has a gas barrier property against water vapor as described above, so that deterioration of the characteristics of the semiconductor can be suppressed. When TFT is used in an organic EL display device, the organic EL display device is inferior in resistance to water and oxygen, but the metal base material can suppress the permeation of oxygen and water vapor. Can be suppressed.
The method for forming the semiconductor layer and the thickness thereof can be the same as those in general.

The gate electrode, source electrode, and drain electrode constituting the TFT are not particularly limited as long as they have desired conductivity, and a conductive material generally used for TFTs can be used. Examples of such materials include Ta, Ti, Al, Zr, Cr, Nb, Hf, Mo, Au, Ag, Pt, Mo-Ta alloys, W-Mo alloys, ITO, IZO and other inorganic materials, and And organic materials having conductivity such as PEDOT / PSS.
The formation method and thickness of the gate electrode, the source electrode, and the drain electrode can be the same as those in general.

As the gate insulating film constituting the TFT, the same gate insulating film as that in a general TFT can be used. For example, silicon oxide, silicon nitride, aluminum oxide, tantalum oxide, barium strontium titanate (BST), Insulating inorganic materials such as lead zirconate titanate (PZT), acrylic resins, phenolic resins, fluorine resins, epoxy resins, cardo resins, vinyl resins, imide resins, novolac resins, etc. An insulating organic material such as an insulating organic material can be used.
The formation method and thickness of the gate insulating film can be the same as a general one.

A protective film may be formed on the TFT. The protective film is provided to protect the TFT. For example, the semiconductor layer can be prevented from being exposed to moisture or the like contained in the air. By forming the protective film, deterioration of the TFT performance with time can be reduced. For example, silicon oxide or silicon nitride is used as such a protective film.
The method for forming the protective film and the thickness thereof can be the same as those in general.
When the semiconductor layer is an oxide semiconductor layer, if a protective film is formed over the oxide semiconductor layer by a sputtering method or the like, oxygen may be lost in the oxide semiconductor, but in the presence of oxygen after the protective film is formed, By performing the annealing treatment, oxygen defects can be compensated. Since this annealing process is performed at a high temperature of several hundred degrees, there is a concern about the dimensional change of the insulating layer containing polyimide. Even in such a case, the adhesion between the insulating layer and the TFT can be maintained, and peeling and cracking of the TFT can be suppressed.

2. Applications TFTs produced according to the present invention can be used for, for example, organic EL display devices, electronic paper, reflective liquid crystal display devices, circuits such as RFID, sensors, and the like. Among these, organic EL display devices and electronic paper are preferable.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

Hereinafter, the present invention will be specifically described using examples and comparative examples.
[Production example]
1. Preparation of polyimide precursor solution (polyimide resin composition) (Production Example 1)
4.0 g (20 mmol) of 4,4′-diaminodiphenyl ether (ODA) and 8.65 g (80 mmol) of paraphenylenediamine (PPD) were put into a 500 ml separable flask, and 200 g of dehydrated N-methyl-2 was added. -It dissolved in pyrrolidone (NMP), and it stirred, heating and monitoring with a thermocouple so that liquid temperature might be 50 degreeC with an oil bath under nitrogen stream. After confirming that they were completely dissolved, 29.1 g (99 mmol) of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) was added thereto gradually over 30 minutes. After the addition, the mixture was stirred at 50 ° C. for 5 hours. Then, it cooled to room temperature and obtained the polyimide precursor solution 1.

(Production Example 2)
The polyimide precursor solution 2 was prepared in the same manner as in Production Example 1, except that the amount of NMP was adjusted so that the reaction temperature and the solution concentration were 17% by weight to 19% by weight, with the compounding ratio shown in Table 1 below. -15 and polyimide precursor solution Z (comparative example) were synthesized.
Acid dianhydrides include 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA), pyromellitic dianhydride (PMDA), p-phenylenebistrimellitic acid monoester dianhydride (TAHQ), p-biphenylenebistrimellitic acid monoester dianhydride (BPTME) was used. Diamines include 4,4'-diaminodiphenyl ether (ODA), paraphenylenediamine (PPD), 1,4-Bis (4-aminophenoxy) benzene (4APB), 2,2'-Dimethyl-4,4'-diaminobiphenyl. One or two of (TBHG) and 2,2′-Bis (trifluoromethyl) -4,4′-diaminobiphenyl (TFMB) were used.

(Production Example 3)
To make photosensitive polyimide, add {[(4,5-dimethoxy-2-nitrobenzyl) oxy] carbonyl} 2,6-dimethyl piperidine (DNCDP) to the polyimide precursor solution 1 at 15% by weight of the solid content of the solution. It added and it was set as the photosensitive polyimide precursor solution 1.

(Production Example 4)
In order to obtain a photosensitive polyimide, an amide compound (HMCP) synthesized from 2-hydroxy-5-methoxy-cinnamic acid and piperidine was added to the polyimide precursor solution 1 at 10% by weight of the solid content of the solution. A polyimide precursor solution 2 was obtained.

(Evaluation of linear thermal expansion coefficient and hygroscopic expansion coefficient)
The polyimide precursor solutions 1 to 15 and the polyimide precursor solution Z are applied to a heat-resistant film (Upilex S 50S: manufactured by Ube Industries, Ltd.) pasted on glass, and dried on a hot plate at 80 ° C. for 10 minutes. Then, the film was peeled from the heat resistant film to obtain a film having a film thickness of 15 μm to 20 μm. Then, the film was fixed to a metal frame, and heat-treated at 350 ° C. for 1 hour under a nitrogen atmosphere (temperature increase rate: 10 ° C./min, natural cooling), and polyimides 1 to 15 and polyimides having a film thickness of 9 μm to 15 μm A film of Z was obtained.
Moreover, the said photosensitive polyimide precursor solutions 1 and 2 were apply | coated to the heat-resistant film (Upilex S50S: Ube Industries, Ltd. product) affixed on the glass, and it was made to dry for 10 minutes on a 100 degreeC hotplate. Thereafter, after exposure to 2000 mJ / cm ^{2 in} terms of illuminance at a wavelength of 365 nm with a high-pressure mercury lamp, the film was heated on a hot plate at 170 ° C. for 10 minutes, and then peeled off from the heat-resistant film to obtain a film having a thickness of 10 μm. Thereafter, the film is fixed to a metal frame, and heat-treated in a nitrogen atmosphere at 350 ° C. for 1 hour (temperature increase rate: 10 ° C./min, natural cooling), and photosensitive polyimide 1 and photosensitive polyimide having a film thickness of 6 μm. A film of 2 was obtained.

<Linear thermal expansion coefficient>
The film produced by the above method was cut into a width of 5 mm and a length of 20 mm and used as an evaluation sample. The linear thermal expansion coefficient was measured by a thermomechanical analyzer Thermo Plus TMA8310 (manufactured by Rigaku Corporation). The measurement conditions are as follows: the observation length of the evaluation sample is 15 mm, the heating rate is 10 ° C./min, the tensile load is 1 g / 25000 μm ² so that the weight per cross-sectional area of the evaluation sample is the same, and 100 ° C. to 200 ° C. The average linear thermal expansion coefficient in the range was defined as the linear thermal expansion coefficient (CTE).

<Humidity expansion coefficient>
The film produced by the above method was cut into a width of 5 mm and a length of 20 mm and used as an evaluation sample. The humidity expansion coefficient was measured by a humidity variable mechanical analyzer Thermo Plus TMA8310 (manufactured by Rigaku Corporation). The temperature is kept constant at 25 ° C., and the sample is first stabilized in a humidity of 15% RH. After maintaining this state for approximately 30 minutes to 2 hours, the humidity of the measurement site is set to 20% RH. Further, this state was maintained for 30 minutes to 2 hours until the sample became stable. Thereafter, the humidity is changed to 50% RH, and the difference between the sample length when the humidity becomes stable and the sample length when the humidity becomes stable at 20% RH is expressed as a change in humidity (in this case, 50-20). 30), and the value divided by the sample length was defined as the humidity expansion coefficient (CHE). At this time, the tensile load was set to 1 g / 25000 μm ² so that the weight per cross-sectional area of the evaluation sample was the same.

(Substrate warpage evaluation)
Using the above polyimide precursor solutions 1 to 15 and Z and photosensitive polyimide precursor solutions 1 and 2 on a SUS304-HTA foil (manufactured by Toyo Seiki Co., Ltd.) having a thickness of 18 μm, the film thickness after imidization is 10 μm. Polyimide films of polyimides 1 to 15 and Z and photosensitive polyimides 1 and 2 and polyimide films of photosensitive polyimides 1 and 2 were formed under the same process conditions as in the preparation of samples for evaluating the linear thermal expansion coefficient so as to be ± 1 μm. Then, the laminated body of SUS304 foil and a polyimide film was cut | disconnected to width 10mm x length 50mm, and it was set as the sample for board | substrate curvature evaluation.

This sample was fixed to the SUS plate surface with only one of the short sides of the sample with Kapton tape, heated in an oven at 100 ° C. for 1 hour, and then in the oven heated to 100 ° C., the short side on the opposite side of the sample The distance from the SUS plate was measured. At that time, a sample having a distance of 0 mm or more and 0.5 mm or less was evaluated as “◯”, a sample of more than 0.5 mm and 1.0 mm or less was evaluated as Δ, and a sample of 1.0 mm or more was determined as “X”.
Similarly, when this sample is fixed to the surface of the SUS plate with only one of the short sides of the sample with Kapton tape and left in a constant temperature and humidity chamber at 23 ° C. and 85% Rh for 1 hour, The distance from the short side SUS plate was measured. At that time, a sample having a distance of 0 mm or more and 0.5 mm or less was evaluated as “◯”, a sample of more than 0.5 mm and 1.0 mm or less was evaluated as Δ, and a sample of 1.0 mm or more was determined as “X”.
The evaluation results are shown below.

Since the linear thermal expansion coefficient of SUS304 foil was 17 ppm / ° C., it was confirmed that the warpage of the laminate was large when the difference in linear thermal expansion coefficient between the polyimide film and the metal foil was large.
Table 2 shows that the smaller the hygroscopic expansion coefficient of the polyimide film, the smaller the warp of the laminate in a high humidity environment.

2. Deaeration of Polyimide Precursor Solution (Polyimide Resin Composition) After diluting the polyimide precursor solution 1 with an NMP solvent so as to have a solid content of 10%, 50 mL each was dispensed into a glass sample tube.
(Deaeration method)
(1) Ultrasonic treatment of the sample collected using an ultrasonic cleaner UT-106 (manufactured by Sharp Manufacturing System Co., Ltd.) at 100 W and 37 kHz at room temperature for 10 minutes with the sample tube closed. Did.
(2) Vacuum The sample collected was opened in a sample tube, placed in a specimen dryer, and decompressed using a vacuum pump, and subjected to a decompression treatment for 15 minutes after the pressure reached less than 300 Pa. At this time, the final ultimate pressure was 230 Pa.

(Measurement of dissolved oxygen)
About the deaerated sample, the dissolved oxygen amount was measured immediately using oxygen sensors “B-506”, “MA-300G”, and “WA-BRP” (manufactured by Iijima Electronics Co., Ltd.).
First, as a reference, the dissolved oxygen saturated solvent (dissolved oxygen saturated NMP) obtained by bubbling air over N-methylpyrrolidone (NMP) for 30 minutes or more was measured using an oxygen sensor, and oxygen was completely dissolved. The oxygen sensor was calibrated so that the measured value of the dissolved oxygen amount of NMP was 0 and the measured value of the dissolved oxygen amount of dissolved oxygen saturated NMP was 100. Next, with a calibrated oxygen sensor, the relative value of the dissolved oxygen amount of the reference polyimide precursor solution that was allowed to stand for 1 hour in the atmosphere and the relative value of the dissolved oxygen amount of the degassed sample were measured. Subsequently, for the degassed sample, the relative value of the dissolved oxygen amount of the degassed sample (relative dissolved oxygen saturation) when the relative value of the dissolved oxygen amount of the reference polyimide precursor solution was 100% was calculated. .

  It became clear that the degassing effect was small with only ultrasonic waves compared with vacuum. In addition, it became clear that the effect of deaeration is not so different even if only vacuum or ultrasonic and vacuum are combined.

(Change over time after deaeration)
About the sample deaerated by the ultrasonic wave (10 minutes) and the vacuum (15 minutes), it left still in air | atmosphere, and the time-dependent change of the amount of dissolved oxygen was observed. It was found that the amount of dissolved oxygen was maintained until 10 minutes later, but the effect of degassing decreased due to absorption from the atmosphere after a longer time, and it completely returned to before degassing after 120 minutes.

3. Surface treatment of SUS foil A 20 μm thick SUS304-HTA foil (manufactured by Toyo Seiki Co., Ltd.) was cut into a 15 cm square and subjected to a surface treatment with the chemicals and treatment conditions shown in Table 5 below.
About the contact angle with respect to NMP which is the solvent of a polyimide resin composition on the surface of SUS foil before surface treatment and each SUS foil after surface treatment, it measured using a contact angle measuring device (DM500 type | mold by Kyowa Interface Chemical Co., Ltd.). (After 2 seconds of dropping 1.5 μL of the droplet from the microsyringe). The contact angle was measured from 5 points on the same sample and calculated from the average value.
In addition, using X-ray photoelectron spectroscopy (XPS), the abundance ratio of the total number of detected elements and the number of carbon atoms on the SUS foil before the surface treatment and the surface of each SUS foil after the surface treatment was calculated.
Furthermore, with respect to the SUS foil before the surface treatment and each SUS foil after the surface treatment, the polyimide precursor solution 1 is coated with a die coater and dried in the atmosphere at 80 ° C. for 60 minutes to confirm the coating property. did. As a result, pinholes occasionally occurred in the sample before the surface treatment. Moreover, about the process example 4, the coating nonuniformity occasionally occurred. For the samples of Processing Examples 1, 2, 3, 5, and 6, no pinholes or coating unevenness occurred, and the coating properties were good.

4). Flatness of insulating layer (Formation of insulating layer 1)
First, the polyimide precursor solution 1 was degassed by the degassing method 3 in Table 3 above. Next, a 90 mm square 20 μm thick SUS304-HTA foil (manufactured by Toyo Seiki Co., Ltd.) affixed to the glass so that the polyimide precursor solution 1 after deaeration is 7 μm ± 1 μm after imidization. The insulating layer 1 was formed by coating with a spin coater, drying on a hot plate at 100 ° C. for 15 minutes, and then heat-treating in a nitrogen atmosphere at 350 ° C. for 1 hour (temperature increase rate: 10 ° C./min, natural cooling).
(Formation of insulating layer 2)
First, a 20 μm-thick SUS304-HTA foil (manufactured by Toyo Seiki Co., Ltd.) was cut into a 15 cm square and surface-treated with 10% sulfuric acid at room temperature for 1 minute. Next, the polyimide precursor solution 1 was degassed by the degassing method 3 in Table 3 above. Subsequently, a sample obtained by cutting the surface-treated SUS foil into 90 mm squares was attached to glass, and the polyimide precursor solution 1 after deaeration was coated with a spin coater so that the film thickness after imidization was 7 μm ± 1 μm. Then, after drying on a hot plate at 100 ° C. for 15 minutes, heat treatment was performed at 350 ° C. for 1 hour in a nitrogen atmosphere (temperature increase rate: 10 ° C./min, natural cooling), whereby insulating layer 2 was formed.
(Formation of insulating layer 3)
A 90 mm square 20 μm thick SUS304-HTA foil (manufactured by Toyo Seiki Co., Ltd.) affixed to glass is coated with a spin coater so that the film thickness after imidization is 7 μm ± 1 μm. After drying on a hot plate at 100 ° C. for 15 minutes, heat treatment was performed in a nitrogen atmosphere at 350 ° C. for 1 hour (temperature increase rate: 10 ° C./min, natural cooling) to form the insulating layer 3.

(Measurement of surface roughness Ra)
Using New View 5000 (manufactured by Zygo), (1) Objective lens: 10x, Zoom lens: 1x, Scan Length: 15µm, 1000µm x 1000µm range, (2) Objective lens: 50x, zoom Lens: 1 ×, Scan Length: 15 μm, 200 μm × 200 μm, (3) Objective lens: 100 ×, Zoom Lens: 1 ×, Scan Length: 15 μm, 100 μm × 100 μm, (4) Objective With a lens of 100 times, a zoom lens of 2 times, and a scan length of 15 μm, each surface shape in the range of 50 μm × 50 μm was imaged, and the average deviation from the center line of the roughness curve calculated from the obtained image By calculating, the surface roughness Ra (unit: nm) of each insulating layer was obtained.

  It became clear that the flatness of the insulating layer surface was improved by deaeration. In addition, it has also been clarified that the effect is further improved by the combined use of the surface treatment.

5. Flatness of adhesion layer (formation of adhesion layer)
For a sample obtained by dispensing 50 mL of the polyimide precursor solution 1 in a glass sample tube, 100 W 37 kHz using an ultrasonic cleaner UT-106 (manufactured by Sharp Manufacturing System Co., Ltd.) with the sample tube lid closed. And sonicated at room temperature for 10 minutes. Thereafter, the lid of the sample tube was opened, put into a specimen dryer, and the pressure was reduced using a vacuum pump. After the pressure reached less than 300 Pa, a pressure reduction treatment was performed for 20 minutes.
The film thickness after imidization was determined using the polyimide precursor solution 1 that had been deaerated on a 100 μm thick SUS304-HTA substrate (manufactured by Koyama Steel Co., Ltd.) immersed in 10% sulfuric acid for 1 minute. After coating with a spin coater to 7 μm ± 1 μm, drying in an oven at 100 ° C. for 60 minutes in the air, heat treatment was performed in a nitrogen atmosphere at 350 ° C. for 1 hour (temperature increase rate 10 ° C./minute, natural Cooling), an insulating layer was formed.
Next, an aluminum film as a first adhesion layer was formed on the insulating layer with a thickness of 5 nm by a DC sputtering method (film formation pressure 0.2 Pa (argon), input power 1 kW, film formation time 10 seconds). Next, a silicon oxide film as a second adhesion layer was formed with a thickness of 100 nm by RF magnetron sputtering (deposition pressure 0.3 Pa (argon: oxygen = 3: 1), input power 2 kW, deposition time 30 minutes). . This obtained the board | substrate for thin film elements.

(Measurement of surface roughness Ra)
For the insulating layer, the surface roughness Ra at 50 μm × 50 μm measured using New View 5000 (manufactured by Zygo) was 13.2 nm.
About the adhesion layer, the surface roughness Ra at 50 μm × 50 μm measured using New View 5000 (manufactured by Zygo) was 23.5 nm. Moreover, the surface roughness Ra in 50 micrometers x 50 micrometers measured using Nanoscope Vmultimode (made by Veeco) was 15.9 nm.

[Example]
First, the polyimide precursor solution 1 was degassed by the degassing method 3 in Table 3 above. Next, on a SUS304-HTA base material (manufactured by Koyama Steel Co., Ltd.) having a thickness of 100 μm, the polyimide precursor solution 1 after deaeration is coated with a spin coater so that the film thickness after imidization becomes 7 μm ± 1 μm. After drying in an oven at 100 ° C. for 60 minutes in the air, heat treatment was performed in a nitrogen atmosphere at 350 ° C. for 1 hour (temperature increase rate: 10 ° C./min, natural cooling) to form an insulating layer.
Next, an aluminum film as a first adhesion layer was formed on the insulating layer with a thickness of 5 nm by a DC sputtering method (film formation pressure 0.2 Pa (argon), input power 1 kW, film formation time 10 seconds). Next, a silicon oxide film as a second adhesion layer was formed with a thickness of 100 nm by RF magnetron sputtering (deposition pressure 0.3 Pa (argon: oxygen = 3: 1), input power 2 kW, deposition time 30 minutes). . This obtained the board | substrate for thin film elements.

A TFT having a bottom gate / bottom contact structure was fabricated on the thin film element substrate. First, an aluminum film having a thickness of 100 nm was formed as a gate electrode film, a resist pattern was formed by photolithography, and then wet etching was performed with a phosphoric acid solution, and the aluminum film was patterned into a predetermined pattern to form a gate electrode. Next, silicon oxide having a thickness of 300 nm was formed as a gate insulating film on the entire surface so as to cover the gate electrode. This gate insulating film uses an RF magnetron sputtering apparatus and is applied to a 6-inch SiO ₂ target with a power of 1.0 kW (= 3 W / cm ² ), a pressure of 1.0 Pa, and a gas of argon + O ₂ (50%). It formed on film-forming conditions. Thereafter, a resist pattern was formed by photolithography and then dry etching was performed to form a contact hole. Next, a 100 nm thick titanium film, aluminum film, and IZO film are deposited on the entire surface of the gate insulating film to form a source electrode and a drain electrode, and then a resist pattern is formed by a photolithography method, and then a hydrogen peroxide solution is formed. Then, wet etching was continuously performed with a phosphoric acid solution, and the titanium film was patterned into a predetermined pattern to form a source electrode and a drain electrode. At this time, the source electrode and the drain electrode were formed on the gate insulating film so as to have a pattern apart from a portion other than directly above the central portion of the gate electrode.

Next, an InGaZnO amorphous oxide thin film (InGaZnO ₄ ) with an In: Ga: Zn ratio of 1: 1: 1 was formed on the entire surface so as to cover the source electrode and the drain electrode so as to have a thickness of 25 nm. The amorphous oxide thin film is 4 inches of InGaZnO (In: Ga: Zn = 1: 1: 1) using an RF magnetron sputtering apparatus under conditions of room temperature (25 ° C.) and Ar: O ₂ of 30:50. It was formed using a target. Then, after forming a resist pattern on the amorphous oxide thin film by photolithography, wet etching was performed with an oxalic acid solution, and the amorphous oxide thin film was patterned to form an amorphous oxide thin film having a predetermined pattern. The amorphous oxide thin film thus obtained was formed on the gate insulating film so as to contact the source electrode and the drain electrode on both sides and straddle the source electrode and the drain electrode. Subsequently, 100 nm thick silicon oxide was formed as a protective film by RF magnetron sputtering so as to cover the whole, and then a resist pattern was formed by photolithography, followed by dry etching. Thereafter, annealing was performed in the atmosphere at 300 ° C. for 1 hour to produce a TFT.

[Comparative example]
A thin film element substrate and a TFT were produced in the same manner as in the example except that an insulating layer was formed as shown below.
On a SUS304-HTA base material (manufactured by Koyama Steel Co., Ltd.) having a thickness of 100 μm, the polyimide precursor solution 1 is coated with a spin coater so that the film thickness after imidation becomes 7 μm ± 1 μm, and then in an oven at 100 ° C. After drying in the air for 60 minutes, heat treatment was performed at 350 ° C. for 1 hour in a nitrogen atmosphere (temperature increase rate: 10 ° C./min, natural cooling) to form an insulating layer.

[Evaluation]
When the electrical characteristics of a TFT (Comparative Example) fabricated using a polyimide precursor solution 1 that was not degassed were evaluated, a TFT fabricated using a polyimide precursor solution 1 that had been deaerated (Example) In comparison with, a decrease in field effect mobility was observed. In addition, a short circuit was observed between the gate electrode and the source or drain electrode in a part of the TFT of the comparative example. These are considered due to the low surface flatness of the insulating layer formed on the SUS substrate. Note that such a short circuit between electrodes can occur not only in the TFT but also in the wiring of the display or the like. For this reason, it is necessary to flatten the insulating layer formed on the SUS substrate.

DESCRIPTION OF SYMBOLS 1 ... Substrate for thin film elements 2 ... Metal base material 3 ... Insulating layer 4 ... Adhesion layer 10 ... TFT

Claims (12)

A degassing step of degassing the polyimide resin composition so that the relative dissolved oxygen saturation calculated by the following method is 95% or less;
An insulating layer forming step of forming an insulating layer by applying the polyimide resin composition on a metal substrate, and the surface roughness Ra of the insulating layer is 30 nm or less. A method for manufacturing a substrate.
<Calculation method of relative dissolved oxygen saturation>
First, using a dissolved oxygen saturated solvent in which air is bubbled for 30 minutes or more in the solvent contained in the polyimide resin composition, the measured value of the dissolved oxygen amount of the solvent in which no oxygen is dissolved is 0, and the dissolved oxygen saturated solvent The dissolved oxygen meter is calibrated so that the measured value of the dissolved oxygen amount becomes 100. Next, with the calibrated dissolved oxygen meter, the relative value of the dissolved oxygen amount of the reference polyimide resin composition in which the polyimide resin composition was allowed to stand for 1 hour or more in the atmosphere, and the degassing that degassed the polyimide resin composition. The relative value of the dissolved oxygen amount of the gas polyimide resin composition is measured. And let the relative value of the dissolved oxygen amount of the said deaeration polyimide resin composition be the relative dissolved oxygen saturation rate when the relative value of the dissolved oxygen amount of the said reference | standard polyimide resin composition is set to 100%.   The method for manufacturing a thin film element substrate according to claim 1, wherein the degassing step is performed immediately before the insulating layer forming step.   3. The method for manufacturing a substrate for a thin film element according to claim 1, wherein the hygroscopic expansion coefficient of the insulating layer is in a range of 0 ppm /% RH to 15 ppm /% RH.   The method for manufacturing a substrate for a thin film element according to any one of claims 1 to 3, wherein a linear thermal expansion coefficient of the insulating layer is in a range of 0 ppm / ° C to 25 ppm / ° C.   5. The thin film element according to claim 1, wherein a difference between a linear thermal expansion coefficient of the insulating layer and a linear thermal expansion coefficient of the metal substrate is 15 ppm / ° C. or less. A method for manufacturing a substrate.   6. The thin film element according to claim 1, further comprising an adhesion layer forming step of forming an adhesion layer containing an inorganic compound on the insulating layer after the insulating layer formation step. A method for manufacturing a substrate.   The inorganic compound constituting the adhesion layer is at least one selected from the group consisting of silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride, aluminum oxynitride, chromium oxide and titanium oxide. The manufacturing method of the board | substrate for thin film elements of Claim 6 characterized by the above-mentioned.   The method for producing a substrate for a thin film element according to claim 6 or 7, wherein the adhesion layer is a multilayer film.   The adhesion layer is formed on the insulating layer and selected from the group consisting of chromium, titanium, aluminum, silicon, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride, aluminum oxynitride, chromium oxide, and titanium oxide. The method for producing a substrate for a thin film element according to claim 8, comprising: a first adhesion layer composed of at least one kind; and a second adhesion layer formed on the first adhesion layer and composed of silicon oxide. .   It has the thin film element part formation process which forms a thin film element part on the board | substrate for thin film elements manufactured by the manufacturing method of the board | substrate for thin film elements in any one of Claim 1-9. Manufacturing method of thin film element.   A method for producing a thin film transistor, comprising: a thin film transistor forming step of forming a thin film transistor on the thin film element substrate produced by the method for producing a thin film element substrate according to claim 1. .   The method of manufacturing a thin film transistor according to claim 11, wherein the thin film transistor includes an oxide semiconductor layer.

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