WO2016112822A1 - Koh developing liquid for kmpr photoresist - Google Patents

Abstract

A KOH developing liquid for a KMPR photoresist. The developing liquid comprises a proper amount of KOH and deionized water. Further, K₂HPO₄ is added into the KOH developing liquid to prepare a buffer solution, a hydration reaction of substances in the buffer solution is promoted along with the gradual neutralization of basic groups in the developing liquid, so as to further release basic groups, so that the reduction speed of the developing effect of the developing liquid is reduced, and the slow-release effect of the basic groups is achieved, thereby postponing the adjustment on a developing time during production, and improving the quality and stability of a product. Further, in order to achieve a better developing effect, a surfactant, a defoaming agent and the like can also be added into the developing liquid. The KOH developing liquid for the KMPR photoresist can better develop the KMPR photoresist, without causing environment pollution like an organic solution.

Description

KOH developer for KMPR photoresist Technical field

The present invention relates to a developer for a photoresist, and more particularly to a KOH developer which can develop a KMPR paste.

Background technique

In the front panel of the electrowetting display, the pixel wall surrounds the smallest display unit, which is an important component of the display, and the fabrication of the pixel wall is usually obtained by photolithography using a photolithography process. The photoetching agent is a photosensitive resin composition, which is divided into two types: positive and negative, the exposed area is developed, and the unexposed area cannot be developed as a positive photoresist, and vice versa. Photo etchant. Taking a negative photoresist as an example, first, a photoresist is coated on the substrate, the photoresist is pre-baked, and then exposed to light by a mask, and then washed with a developer. The photoetching agent in the unexposed area covered by the mask can leave a desired photoresist pattern according to the pattern of the mask, specifically a matrix pattern, and each matrix point corresponds to each pixel. Conventionally used development methods include immersion development, shaking development, spray development, and puddle, and the developer includes an organic solvent, an alkaline developer, and the like. In the industrial production, in consideration of problems such as environmental protection and waste liquid treatment, an alkaline developing solution is often used. The commonly used alkaline developing solution is a salt solution of various alkali liquids and alkali metals such as KOH aqueous solution, NaOH aqueous solution, TMAH aqueous solution.

MicroChem's KMPR photoresist is an excellent photoresist material for the preparation of pixel walls. Through the choice of viscosity, we can obtain pixel walls of different heights, and And KMPR photoresist is more hydrophilic than the commonly used SU8 photoresist, and is more suitable for electrowetting display technology and its industrialization. However, the developer of KMPR glue recommended by MicroChem is an organic solvent (such as PGMEA) or 2.38wt% TMAH solution. The organic solvent developer is not suitable for industrial production due to its environmental problems, and the TMAH solution takes a long time to develop KMPR. The development effect is far less than that of its organic solvent developer, so the industrial use of KMPR glue is affected.

Summary of the invention

The technical problem to be solved by the present invention is to provide a KOH developing solution for KMPR glue, which can avoid the environmental protection problem caused by the use of the organic solvent developing solution, and has a short development time and is suitable for industrial production.

The solution to the technical problem of the present invention is: a KOH developer for KMPR photoresist, which consists of KOH and deionized water, wherein the KOH content is from 0.01 to 10% by weight.

Theoretically, the higher the concentration of KOH lye, the higher the content of basic groups, the faster the development speed, but the inventors found through actual experiments: fixed development temperature, taking 22 ° C as an example (as shown in Figure 1), with concentration The KOH developer's apparent point time is gradually decreased. When the KOH concentration reaches 0.8wt%, the peak time appears to be the lowest value of 145s. Then, as the KOH concentration increases, the apparent point time gradually increases slowly when KOH When the concentration reached 3 wt%, the apparent time was increased to 210 s, although the apparent point time was still much less than 0.1 wt% for 330 s.

It is presumed that the reason why the KOH concentration increases when the point time becomes longer is as follows: The development mechanism of the alkaline developing solution is: first, OH ^- enters the macromolecular film void, chemically reacts with the acidic group of the photoresist substance, and then the cation ( K ⁺ ) reaches the reaction interface for charge neutralization. Theoretically, after these steps, a reaction product is carried away from the developer-photoresist film reaction interface into the KOH developer body. For a high concentration of developer (concentration ≥ 0.8 wt%), the initial reaction is rapid due to the high KOH concentration, and the reaction product is too large to be completely removed from the developer-photoresist film reaction interface, thus hindering subsequent OH ^- and K ⁺ to enter, leading to slower late developing, has a concentration of 1wt% KOH solution selected, the time point showing 175S, and 130S in the photoresist is not fully developed, but the visible surface of the substrate Only a thin film of film was stopped, and development was stopped. It was found that if the film was rinsed with 1 wt% of KOH solution immediately after stopping the development, the film on the surface of the substrate could not be washed away for 30 seconds, and if it was rinsed with deionized water, The film was washed off in 3-5s. This also shows that if the developer concentration is too high, the product is not completely removed from the developer-photoresist film reaction interface, but it will hinder the subsequent development, resulting in a prolonged time when the concentration is high.

The developing temperature is also an important factor affecting the development speed. The development mechanism of KOH developer is: first, OH ^- enters the macromolecular film void, chemically reacts with the photoresist material, and then the cation (K ⁺ ) reaches the reaction interface for charge neutralization. . Therefore, the development process is actually a chemical reaction process. According to the Arrhenius Uz formula, it is estimated that for every 10 ° C increase in temperature, the chemical reaction rate is increased by 4 to 6 times for the development process, as shown in FIG. 2 . The 0.4 wt% KOH developer exhibited a spot time of 190 s at 22 ° C and a spot time of 45 s at 32 ° C. In the development process of actual scientific research or production, the developing temperature is generally controlled at 22 to 40 ° C. Therefore, in combination with the influence of temperature and concentration on the developing speed, the KOH concentration of the developing solution in the embodiment of the present invention is 0.01 to 10% by weight.

Further, in combination with FIG. 2, it was found that KOH showed a concentration of 0.4 wt% and 0.1 wt%. The liquid solution can reach the display time of <60s between 30-40 °C, and the display time of 30-60s is an ideal time range in actual production or scientific research process, although high concentration can also be realized. The development time is lowered, but the excessive concentration causes excessive KOH consumption, which is disadvantageous to environmental protection. Therefore, the preferred concentration of KOH is in the range of 0.1 to 1% by weight, and in actual use, the temperature adjustment can be combined to shorten the display time.

The above-mentioned development time is taken as a negative gel as an example of the time required for the unexposed dry film to be dissolved from the substrate. In order to make the development more thorough during the actual development process, a development time is generally added on the basis of the display time, which is called the actual development time.

In order to improve the development efficiency, as a further improvement of the above scheme, the developer further includes a buffering agent such as a phosphate, a carbonate, a borate, an amine salt, etc., since the KOH developer is alkaline and has a high pH, The buffer of the invention uses potassium salt K ₂ HPO ₄ , and the amount of K ₂ HPO ₄ added is determined according to the following steps:

1) calculating the pH of the selected KOH developer having a suitable development time according to the formula pH=14+lgC _KOH ; wherein C _KOH is the molar concentration of KOH in the KOH developer;

The pH of the resulting 2) step 1) is calculated, into the equation _{pH = pKa + lg (C KOH} / C K2HPO4), to give ₂ HPO KOH developer ₂ HPO ₄ K ₄ is the relationship between the ratio of the concentration of KOH containing K ; wherein Ka, HPO ₄ ^2- ionization constant; C _KOH, K ₂ HPO4 molar concentration of the developing solution of KOH KOH; C _K2HPO4, containing K KOH ₂ HPO ₄ molar concentration of the developer in a K ₂ HPO _4;

3) Determine the amount of K ₂ HPO ₄ added in combination with the actual process. The combined actual process refers specifically to the ratio of the molar concentration of KOH and K ₂ HPO ₄ in the developing solution obtained in step 2), the concentration of KOH is selected according to the process requirements, and then the amount of K ₂ HPO ₄ is calculated. . The KOH concentration and temperature of the KOH developer in the step 1) are selected according to the development time, and the concentration ranges from 0.1 to 1% by weight, and the temperature ranges from 22 to 40 °C.

Further, in order to solve the problem that the KOH developer wets the surface of the substrate, the developer further includes a surfactant, and the surfactant is a Tween, a Span or a polyoxyethylene ether. Combination of one or more of the agents, or a combination of any one or more of the nonionic surfactants described above and any one or more sulfonate or sulfate anionic surfactants . Among them, nonionic surfactants such as Span20, Span60, Span80, Tween20, Tween40, Tween60, Tween80, AEO3, AEO7, AEO9, etc., the anionic surfactants such as SDS (sodium dodecyl sulfate), dodecane Sodium sulfonate and the like.

Preferably, the surfactant is contained in an amount of from 0.001 to 1% by weight, further, from 0.005 to 0.5% by weight.

Further, in order to eliminate bubbles generated by the surfactant in the developer, the developer further includes 0.1 to 1% by weight of an antifoaming agent. The antifoaming agent may be a silicone-based antifoaming agent, a surfactant-based antifoaming agent, or the like, such as a silicone polyether defoaming agent, a non-silicone polyether defoaming agent, or the like.

Preferably, the antifoaming agent is present in an amount of from 0.2 to 0.7% by weight.

The invention has the beneficial effects that the present invention can develop KMPR glue by exploring a suitable concentration of KOH solution, and further, adding K ₂ HPO _{4 to the} KOH developing solution to prepare an alkaline buffer solution, with the alkaline in the developing solution. The group is gradually neutralized, which promotes the hydration reaction of the buffer solution material, thereby releasing the basic group, reducing the speed at which the developer development efficiency is weakened, and the sustained release effect of the basic group is delayed, thereby delaying the production. The adjustment of the development time improves the quality and stability of the product. Further, in order to achieve a better developing effect, a surfactant, an antifoaming agent or the like may be added to the developing solution. The KMPR paste KOH developer of the present invention can better develop KMPR glue without polluting the environment like an organic solution.

DRAWINGS

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly described below. It is apparent that the described drawings are only a part of the embodiments of the present invention, and not all of the embodiments, and those skilled in the art can obtain other designs and drawings according to the drawings without any creative work.

Figure 1 is a development time of different concentrations of KOH developer of the present invention;

Figure 2 is the effect of temperature on the development time of the KOH developer;

3 is a graph showing a development effect of a pixel wall according to an embodiment of the present invention;

Figure 4 is a comparison of the development efficiency of the KOH developer of Example 3 of the present invention with the KOH-K ₂ HPO ₄ buffer developer of Example 7.

detailed description

KMPR photoresist is a photoresist-based material available for the pixel wall of the electrowetting process other than SU8. KMPR series photoresists can achieve pixel wall heights of 2-50μm, meeting the requirements of electrowetting process. For example, KMPR 1005 can coat 4-10μm high pixel walls.

The development effect of the KOH developer of the present invention on the KMPR photoresist will be described below in conjunction with preferred embodiments.

Example 1: Weigh a certain amount of KOH, dissolve it in 100 mL of deionized water, shake it evenly, and obtain a developing solution having a concentration of 0.1% by weight, and add the obtained developing solution to the developing tank. Under the condition of 24 ° C, the 3-inch substrate (side length 7.6 cm) was developed, and the height of the pixel wall formed by the photoresist KMPR on the substrate was 6-7 μm, and the development method was: shaking development.

Example 2: Development at 35 ° C, the same conditions as in Example 1.

Example 3: Weigh a certain amount of KOH, dissolve it in 100 mL of deionized water, shake it evenly, and obtain a developing solution with a concentration of 0.4 wt%. Add the obtained developing solution to the developing tank, and develop 3 inches at 24 ° C. The substrate (side length 7.6 cm), the pixel wall formed by the photoresist KMPR on the substrate has a height of 6-7 μm, and the development method is: shaking development.

Example 4: Development at 26 ° C, the same conditions as in Example 3.

Example 5: Development at 32 ° C, the same conditions as in Example 3.

Example 6: Weigh a certain amount of KOH, dissolve it in 100 mL of deionized water, shake it evenly to obtain a developing solution having a concentration of 2 wt%, add the obtained developing solution to a developing tank, and develop a 3-inch substrate at 24 ° C. (side length 7.6 cm), the pixel wall formed by the photoresist KMPR on the substrate has a height of 6-7 μm, and the development method is: shaking development.

Example 7: Weigh a certain amount of KOH, dissolve it in 100 mL of deionized water, shake it evenly to obtain a KOH solution having a concentration of 0.4 wt%, and further, add K ₂ HPO ₄ to prepare a KOH-K ₂ HPO ₄ buffer developed The amount of K ₂ HPO ₄ added is calculated according to the following steps:

1) The obtained KOH-K ₂ HPO ₄ buffer developing solution was set to have the same pH as the 0.4 wt% KOH developing solution.

The pH of the 0.4 wt% KOH developer was 14 + lgC _KOH = 14 + lg 0.4 / 56.11 = 12.85, that is, the pH of the KOH-K ₂ HPO ₄ buffer developing solution to be configured was 12.28.

2) The calculated pH 12.44 brought KOH-K ₂ HPO ₄ buffer developer to give _{pKa + lg (C KOH / C} K2HPO4) = 12.85, HPO ₄ ^2- known ionization constant Ka = 10 ^{_-12. 38} Calculate C _KOH /C _K2HPO4 =3:1.

3) The concentration of K ₂ HPO ₄ in the buffer developing solution was calculated to be 0.42 wt%, and the mass of K ₂ HPO _{4 was} further obtained.

The prepared KOH-K ₂ HPO ₄ buffer developing solution was added to the developing cell, and the 3 inch substrate (side length 7.6 cm) was developed at 24 ° C, and the pixel wall height of the photoresist KMPR on the substrate was 6-7 μm. , development method: shaking and developing.

Example 8: Development at 26 ° C, the same conditions as in Example 7.

Example 9: 0.012% by weight of Tween 20 was added to the developing solution, and the remaining conditions were the same as in Example 4.

Example 10: 0.012% by weight of Span 80 was added to the developing solution, and the other conditions were the same as in Example 4.

Example 11: 0.006 wt% of Span 80 and 0.006 wt% of Tween 20 were added to the developer, the same conditions as in Example 4.

Example 12: 0.006 wt% of Span 80 and 0.006 wt% of SDS (sodium dodecyl sulfate) were added to the developer, and the same conditions were the same as those in Example 4.

Example 13: 0.012 wt% of Span 80 was added to the developer, and the rest of the conditions were the same as in Example 8.

The developing solution commonly used for KMPR adhesives includes the organic solvent PGMEA developer and TMAH developer, so the two developers are selected for comparison with the KOH developer of the present invention.

Comparative Example 1: 100 mL of PGMEA organic solvent developer was added to a developing cell at Under the condition of 24 ° C, the 3 inch substrate (side length 7.6 cm) was developed, and the height of the pixel wall formed by the photoresist KMPR on the substrate was 6-7 μm, and the development method was: shaking development.

Comparative Example 2: 100 mL of a 2.38 wt% TMAH developer was added to a developing cell, and a 3 inch substrate (side length 7.6 cm) was developed at 24 ° C. The pixel wall height of the photoresist KMPR on the substrate was 6 -7 μm, development method: shaking development.

The development time of the developer in the above Examples 1-13 and Comparative Example 1-2 was measured, and the preferred embodiment was used to fix the actual development time, and the measurement was performed using a step meter to plot the development curve of the pixel wall. The test results are shown in the table. 1.

Table 1 list of embodiments

Combined with Table 1 and Figure 3, it can be seen from the comparison that under the same conditions, the organic solvent PGMEA develops the fastest (the display time is 30 s); while the TMAH developer develops the slowest, and the pixel wall height is displayed at 600 s. Only half of the actual height proves that the TMAH developer shows a point time of more than 600s, which is not suitable for production or scientific research. The development speed of KOH solution is moderate, and the development curve of the obtained pixel wall is basically the same as that of the organic solvent PGMEA, which is suitable for industrial production, and can be adjusted according to the influence of temperature and concentration on the display time. control.

The comparison between Example 3 and Example 7 shows that there is no difference in the time for developing the first substrate under the same conditions for both the KOH developer and the KOH-K ₂ HPO ₄ buffer developer, but further development is carried out by testing different numbers of sheets. The conductivity of the liquid, as shown in Figure 4, shows that the conductivity of the KOH developer is slower than that of the KOH-K ₂ HPO ₄ buffer developer under the condition that the initial developer pH and the developer volume are the same, that is, The addition of K ₂ HPO ₄ serves as a buffering effect, and the developing efficiency of the developing solution is lowered, so that the number of developing portions of the developing solution can be increased.

In the seventh embodiment, for convenience of comparison, the concentration of KOH in the selected KOH-K ₂ HPO ₄ buffer developing solution is the same as the concentration of KOH in the corresponding KOH developing solution, but in practical application, those skilled in the art can, as needed, Different KOH concentrations were selected, and the concentration of K ₂ HPO _{4 was} calculated according to the formula provided, and the amount of addition was determined.

Examples 9-13 show preferred embodiments of a developer having a surfactant. By comparison with the developer having no surfactant in Example 4 and Example 8, it was found that the addition of the surfactant under the same conditions. The development time of the developer is not significant influences. However, by measuring the contact angle of the photoresist surface of the unexposed area, the exposed area, and the unexposed-exposed area of the substrate (as shown in Table 2), the addition of the surfactant is advantageous for improving the surface of the photoresist. Wettability. It is indicated that the addition of the surfactant is mainly to improve the wettability of the surface of the photoresist, and there is no significant improvement in the time of the display.

Table 2 Effect of surfactant on the surface wetting properties of photoresist

As shown in Table 2, a certain concentration of nonionic surfactant (Tween 20 or Span 80), or a combination of nonionic surfactants (Tween 20 and Span 80), or nonionic surface active was added to a 0.4 wt% KOH developer. The combination of the agent and the anionic surfactant (Span80 and SDS), the contact angle of the developer with the surface of the KMPR gel is reduced, including the unexposed area, the exposed area, and the mixed area of the two, that is, the surfactant The addition increases the wettability of the KOH developer on the surface of the KMPR gel. Among them, the preferred embodiment is a KOH developing solution in which 0.012% by weight of Span 80 is added, and the contact angle of water droplets in the unexposed area, the exposed area, and the mixed area of the two is lowered by 10°, 19°, and 15°, respectively. That is, the addition of the surfactant in the KOH developer improves the wettability of the surface of the KMPR gel, which facilitates uniform development. Also, as shown in Example 2 and Example 13 of Table 2, for the buffer developing solution of KOH-K ₂ HPO ₄ , the addition of the surfactant causes the contact angle of the buffer developing solution on the surface of the KMPR gel to be lowered, and the surface wettability is enhanced. .

Further, in order to eliminate bubbles generated by the surfactant in the developer, the developer of the present invention may further comprise 0.1 to 1% by weight of an antifoaming agent. The antifoaming agent may be a silicone-based antifoaming agent, a surfactant-based antifoaming agent, or the like, such as a silicone polyether defoaming agent, a non-silicone polyether defoaming agent, or the like. Preferably, the content of the antifoaming agent is 0.2-0.7 wt%, and the amount and type of defoaming agent added are selected by those skilled in the art as needed, and will not be described herein.

In the above embodiment, the composition and effect of the developer of the present invention have been described by taking shaking development as an example, but the developer of the present invention is not only suitable for the development method, but also suitable for various other development methods, including spray development, Let stand for development and the like.

The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the embodiments, and various equivalent modifications or substitutions can be made by those skilled in the art without departing from the spirit of the invention. These equivalent variations or alternatives are intended to be included within the scope of the claims.

Claims (9)

1. A KOH developer for KMPR photoresist, characterized in that the developer is composed of KOH and deionized water, wherein the content of KOH is 0.01 to 10% by weight.
2. The KOH developer for KMPR photoresist according to claim 1, wherein the KOH content is from 0.1 to 1% by weight.
3. The KOH developer for KMPR photoresist according to claim 1, wherein the developer further comprises K ₂ HPO ₄ , and the amount of K ₂ HPO ₄ added is determined according to the following steps:

   1) calculating the pH of the selected KOH developer having a suitable development time according to the formula pH=14+lgC _KOH ; wherein C _KOH is the molar concentration of KOH in the KOH developer;

   The pH of the resulting 2) step 1) is calculated, into the equation _{pH = pKa + lg (C KOH} / C K2HPO4), to give ₂ HPO KOH developer ₂ HPO ₄ K ₄ is the relationship between the ratio of the concentration of KOH containing K Wherein the ionization constant of Ka, HPO ₄ ^2- ; C _KOH , the molar concentration of KOH in the KOH developer containing K ₂ HPO ₄ ; C _K2HPO4 , the molar concentration of K ₂ HPO ₄ in the KOH developer containing K ₂ HPO ₄ ;

   3) Determine the amount of K ₂ HPO ₄ added in combination with the actual process.
4. The KOH developer for KMPR photoresist according to any one of claims 1 to 3, wherein the developer further comprises 0.001 to 1% by weight of a surfactant.
5. The KOH developer for KMPR photoresist according to claim 4, wherein the surfactant is one or more of a Tween type, a Span type or a polyoxyethylene ether type nonionic surfactant. Compound, or any one or more of the nonionic surfactants described above and any one or more of the sulfonates or sulfates Compounding of ionic surfactants.
6. The KOH developer for KMPR photoresist according to claim 5, wherein the surfactant is contained in an amount of from 0.005 to 0.5% by weight.
7. The KOH developer for KMPR photoresist according to claim 4, wherein the developer further comprises 0.1 to 1% by weight of an antifoaming agent.
8. The KOH developer for KMPR photoresist according to claim 7, wherein the antifoaming agent is contained in an amount of from 0.2 to 0.7% by weight.
9. Use of a KOH developer for KMPR photoresist according to any one of claims 1-8, characterized in that the developer is developed at 22-40 °C.

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