CN101154043B - High Resolution Negative Photoresist - Google Patents

Abstract

The invention relates to a negative photoresist which is a novel photoresist composition. The negative photoresist mainly comprises the following components: polymer Resin, Pigment, Photo initiator, Monomer, Solvent, and Additives, wherein the molecular weight (Mw) of the polymer Resin is preferably lower than 40,000, and the water-soluble Monomer is used for increasing the development contrast, so that after a photoresist image (Pattern) is imaged, the length of a bevel edge (Taper) of the photoresist image can be effectively shortened, the line width (CD) value of the photoresist image is closer to the size of a photomask image, and further a better resolution is obtained.

Description

High Resolution Negative Photoresist

technical field

The present invention relates to a photoresist, especially a high-resolution negative photoresist capable of obtaining high-resolution images.

Background technique

In order to manufacture tiny circuit patterns used in liquid crystal display (LCD) circuits or semiconductor integrated circuits, a photoresist including polymer resin, photosensitive compound and solvent is evenly covered or coated on an insulator layer or conductive metal layer on the substrate The composition, the covered or coated substrate is warm baked to evaporate the solvent, the warm baked substrate is selectively exposed to some type of radiation such as ultraviolet light, electrons or X-rays, the substrate is then developed to produce the desired pattern, the developed The substrate is then etched to remove the insulator layer or the conductive metal layer, and the remaining photoresist layer is removed to complete the micro pattern transfer on the surface of the substrate.

The photoresist that will decompose after exposure (UV light) is called "positive photoresist", on the contrary, the one that will harden and polymerize after exposure is "negative photoresist". One, the biggest difference from general photoresist materials (such as IC photoresist materials) is that the color photoresist adds pigment components, which is also the source of hue, and is also the key material for the colorization of LCD flat-panel displays; Type photoresist lithography process mainly includes: (1) Substrate Clean → (2) Coating → (3) Vacuum Dry → (4) pre-baking ) → (5) exposure (exposure) → (6) development (Developing) → (7) hard baking (Post-baking) and other steps, the difference in color photoresist technology, in addition to the coating characteristics and photoresist and In addition to considering the two aspects of substrate adhesion, it must also be able to meet the needs of the high-resolution field.

In principle, the image resolution of general negative photoresist (including color photoresist) is about 10-20um (line width/line spacing, Line/Space is the same), and high-resolution negative photoresist (including color photoresist) ) image resolution is about 1.0-2.0um (line width/line distance, Line/Space is the same), as shown in Figure 1, after the general photoresist image (Pattern) is imaged, its image hypotenuse (Taper) The length should be short, that is, the angle between the taper and the substrate should be large, so as to meet the main characteristics required by high-resolution negative photoresists; in other words, under the same conditions of the photo mask pattern , the closer the critical dimension (CD) of the photoresist layer image is to the size of the mask image, the better the resolution.

In the existing known technical field, although No. US5847015 patent document, No. US5232634 patent document, US6432614 patent document, and US6348298 patent document have disclosed color light agents (negative photoresists) with different components; The properties of the mixture cannot be easily predicted from the structure of a single component. Therefore, although the above-mentioned known negative photoresists only slightly change their components, they can produce completely different properties, and they all have specific characteristics. Applicable fields; however, the high-resolution image performance effect cannot meet the continuous improvement of resolution (or called pixels, Pixels) usage requirements such as image sensors.

Contents of the invention

In view of this, the present invention aims to provide a high-resolution image that can be applied to a high-resolution negative photoresist that requires high resolution.

In practice, the main components of negative photoresists are: polymer resin (Resin), pigment (Pigment), photoinitiator (Photo initiator), monomer (Monomer), solvent (Solvent), and additives (Additives) ); Among them, the molecular weight (Mw) of the polymer resin (Resin) is preferably lower than 40,000, and the water-soluble monomer is used to increase the development contrast, so that after the photoresist image (Pattern) is imaged, the image skew of the photoresist can be effectively shortened. Taper length makes the line width (CD) value of the photoresist layer image closer to the size of the mask image, thereby obtaining better resolution.

The method of measuring line width (CD) value is generally the most common optical method. Using a microscope with image sensing components, control system and measurement analysis software, you can read the photoresist line width image and measure its line The wide value is on the computer. A scanning electron microscope (SEM) can also be used as a measurement tool, but it is more time-consuming and inconvenient than the optical method.

Description of drawings

Figure 1 is a schematic diagram of the state of the photoresist layer image and the substrate of a general negative photoresist;

FIG. 2 is a schematic diagram of the state of the photoresist layer image and the substrate of the negative photoresist of the present invention.

Detailed ways

In order to make your examiner understand the main technical content and implementation mode of the present invention, the description is as follows with the help of drawings:

The high-resolution negative photoresist of the present invention mainly consists of polymer resin (Resin), pigment (Pigment), photoinitiator (Photo initiator), monomer (Monomer), solvent (Solvent), and additives (Additives) The composition is a high-resolution image that can be applied to high-resolution negative photoresists with high-resolution requirements; wherein:

The function of the polymer resin (Resin) lies in adhesion, development, pigment dispersion, fluidity, heat resistance, chemical resistance, and resolution; the function of the pigment (Pigment) lies in coloring and colorization; the photosensitive initiator ( The function of photo initiator lies in photosensitive characteristics and resolution; the function of monomer lies in adhesion, development and resolution; the function of solvent lies in viscosity and coating properties; the function of additives lies in Spreadability, leveling and foaming properties.

The polymer resin (Resin) can be a polymer or copolymer containing carboxylic acid groups (COOH), such as acrylic (Acrylic) resin, acrylic-epoxy (Epoxy) resin, acrylic-melamine ( Melamine) resin, acrylic-styrene (Styrene) resin, phenol-phenolic (PhenolicAldehyde) resin and other resins, or any mixture of the above resins, but not limited thereto. The weight percent of the resin in the photoresist may range from 6% to 50%.

Pigment can be optionally CI pigment yellow (1, 3, 11, 12, 13, 14, 15, 16, 17, 20, 24, 31, 53, 55, 60, 61, 65, 71, 73 , 74, 81, 83, 93, 95, 97, 98, 99, 100, 101, 104, 106, 108, 109, 110, 113, 114, 116, 117, 119, 120, 126, 127, 129, 138 , 139, 150, 151, 152, 153, 154, 155, 156, 166, 167, 168, 175), CI Pigment Orange (1, 5, 13, 14, 16, 17, 24, 34, 36, 38, 40, 43, 46, 49, 51, 61, 63, 64, 71, 73), CI pigment red (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14 , 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 40, 41, 42, 48:1, 48:2, 48:3, 48:4, 49 :1, 49:2, 50:1, 52:1, 53:1, 57, 57:1, 57:2, 58:2, 58:4, 60:1, 63:1, 63:2, 64 :1, 81: 1, 83, 88, 90: 1, 97, 101, 102, 104, 105, 106, 108, 112, 113, 114, 122, 123, 144, 146, 149, 150, 151, 155 , 166, 168, 170, 171, 172, 174, 175, 176, 177, 178, 179, 180, 185, 187, 188, 190, 193, 194, 202, 206, 207, 208, 209, 215, 216 , 220, 224, 226, 242, 243, 245, 254, 264, 265), CI Pigment Violet (1, 19, 23, 29, 32, 36, 38, 39), CI Pigment Blue (1, 2, 15, 15 :3, 15:4, 15:6, 16, 22, 60, 66), CI pigment green (7, 36, 37), CI pigment brown (23, 25, 28), CI pigment black (1, 7) Inorganic pigments (metal oxides or metal complexes) or organic pigments, or any mixture of the above pigments, but not limited thereto. The weight percent of the pigment in the photoresist can range from 2% to 15%.

Monomers can be divided into water-insoluble and water-soluble monomers, among which, water-insoluble monomers (water-insoluble Monomer) can be PENTAERYTHRITOLTRIACRYLATE (penterythritol triacrylate), TRIMETHYLOLPROPANETRIACRYLATE (trimethyl ether propane triacrylate) , TRIMETHYLOLPROPANE TRIMETHACRYLATE (trimethyl ether propane trimethacrylate), TRIS (2-HYDROXY ETHYL) ISOCYANURATE TRIACRYLATE) (three, di-ethanol isocyanate triacrylate), (DI-TRIMETHYLOLPROPANE TETRAACRYLATE (two, three methylol propane tetraacrylic acid ester) ester), DIPENTAERYTHRITOL PENTAACRYLATE (dipentaerythritol pentaacrylate), PENTAACRYLATE ESTER (pentaacrylate), PENTAERYTHRITOL TETRAACRYLATE) (pentaerythritol tetraacetate); Diisopentylthritol hexaacetate), or Muti-function Monomer (multifunctional monomer), Dendritic/Hyper-branchedacrylate oligomers (dendritic/multi-branched acrylate oligomers), Hyper-branched polyesteracrylates (multi-branched polyether Acrylates), Urethane acrylates (urethane).

Water-soluble monomer (water-soluble monomer) can be Ethoxylated (polyoxyethylene) (referred to as EO) base and Propoxylated (polyoxypropylene) (referred to as PO) monomer (monomer); for example: 2 (2-ETHOXYETHOXY ) ETHYL ACRYLATE (two-(two-oxyethylene oxyethylene) vinyl acrylate, ETHOXYLATED (15) TRIMETHYLOL PROPANE TRIACRYLATE (fifteen polyoxyethylene trimethylol propane triacrylate), ETHOXYLATED (30) BISPHENOL A DIACRYLATE (thirty Ethylene oxide two, two-bis-p-phenol methane diacrylate), ETHOXYLATED (30) BISPHENOL A DIMETHACRYLATE (thirty oxyethylene two, two-bis-p-phenol methane dimethacrylate), ETHOXYLATED (20) TRIMETHYLOL PROPANETRIACRYLATE (two Ten oxyethylene trimethylol propane triacrylate), METHOXYPOLYETHYLENE GLYCOL (350) MONOMETHACRYLATE (fifteen oxyethylene trimethylol propane triacrylate), METHOXY POLYETHYLENEGLYCOL (550) MONOMETHACRYLATE (methyloxy five hundred and fifty oxyethylene mono Methacrylate), POLYETHYLENEGLYCOL (200) DIACRYLATE (two hundred oxyethylene diacrylate), POLYETHYLENEGLYCOL (400) DIACRYLATE (four hundred oxyethylene diacrylate), POLYETHYLENE GLYCOL (400) DIMETHACRYLATE (four hundred oxyethylene Dimethacrylate), POLYETHYLENEGLYCOL (600) DIACRYLATE (600 oxyethylene diacrylate), POLYETHYLENEGLYCOL (600) DIMETHACRYLATE (600 oxyethylene dimethacrylate), POLYPROPYLENE GLYCOL MONOMETHACRYLATE (polyoxypropylene monomethacrylate Acrylic acid ester), its molecular general formula is as follows:

或

or

The values of x, y, and z can range from 0 to 600 or above, and x+y+z≠0.

Of course, two or more monomers can also be added to form a co-monomer. The weight percent of the monomer or comonomer in the photoresist may range from 2% to 10%.

Photo initiator, which can be selected from acetophenone, benzophenone or bis-imidazole, or any combination of the above photo initiators , but not limited to this. The weight percent of the photoinitiator in the photoresist may range from 1% to 10%.

The solvent (Solvent) can be ethylene glycol monopropylether, di-ethylene glycol dimethyl ether, tetrahydrofuran, ethylene glycol monomethyl ether, ethylene glycol ether (ethylene glycol monoethyl ether), di-ethylene glycol mono-methyl ether, di-ethylene glycol mono-ethyl ether, di-ethylene glycol mono -butyl ether), propylene glycol mono-methyl ether acetate, propylene glycol mono-ethyl ether acetate, propylene glycol mono-propyl ether acetate, 3 - Ethoxy ethyl propionate (ethyl3-ethoxy propionate), etc., or any mixture of the above solvents, but not limited thereto. The weight percent of the solvent in the photoresist may range from 42% to 88%.

The additive is generally a pigment dispersant, which is a necessary component for photoresists containing pigments. It is generally a non-ionic surfactant, for example: Solsperse39000, Solsperse21000. The weight percentage range of this dispersant in the photoresist can be 1 % to 14%.

In particular, it is better to mix water-soluble monomers with water-insoluble monomers for the monomers used. The ratio range: water-insoluble monomers/water-soluble monomers = 95:5 to 5:95, which will increase the development Contrast; As for, polymer resin (Resin) is mainly a kind of polymer substance, can be weight average molecular weight (Mw) below 40,000, better below 20,000, because low molecular weight contributes to image hypotenuse (Taper) length The reduction, and can get the line width value (Critical dimension, CD) closer to the size of the mask image; In addition, the molecular weight distribution range of the resin can be expressed by the polymer dispersion index (PDI), PDI=Mw/Mn , Mn is the number average molecular weight, the smaller the PDI value, the more helpful it is to improve the resolution. Generally, the PDI value is required to be about 4.0, and the better PDI value is below 3.5, and the acid value of the polymer resin (Resin) (Acid value) =40～250mgKOH/g.

Specific examples are described below, however, the present invention is not limited thereto.

Photoresist composition Composition ratio (%) Resin (1) ~ Resin (6) 20 Pigment RED CI254, Ciba. 5 Additive: pigment dispersant (nonionic surfactant, Solsperse39000) 3 Monomer (acrylic system: DI-TRIMETHYLOLPROPANETETRAACRYLATE) 10 Photo-initiator (Photo-initiator), Irgacure907, Ciba. 2 Solvent (propylene glycol monomethyl ether acetate, PGMEA), DOW Chemical. 60 total total 100

Resin (1)-resin (4) represent acrylic resins composed of four different molecular weights of methylmethacrylate (MethylMethacrylate), methacrylic acid (Methacrylic acid) and a small amount of other monomer components, please refer to Table I. Resin (5)-resin (6) represent acrylic resins composed of two different molecular weights of methyl methacrylate (Methyl Methacrylate), methacrylic acid (Methacrylic acid) and a small amount of other monomer components, please refer to Table II. The weight percentages of the monomer compositions of the resins (1)-(6) are: MethylMethacrylate=60%, Methacrylic acid=30%, and other monomer compositions=10%.

Table 1: Effects of different resin molecular weights on photoresist linewidth values

Resin number Resin molecular weight (Mw) Photoresist line width value after exposure and development (um) Mask line width value (um) (1) 10,000 53.73 50 (2) 16,087 59.59 50 (3) 21,554 60.17 50 (4) 28,141 67.40 50 Comparative example-1 Greater than 40,000 greater than 70 50

Table 2: Effects of different PDI values of resins on photoresist linewidth values

Resin number Resin PDI value Photoresist line width value after exposure and development (um) Mask line width value (um) (5) 1.8～2.5 56～58 50 (6) 3.5～4.0 60～63 50 Comparative example-2 greater than 4.0 greater than 65 50

Using the negative photoresist composed of the above components, I-line photo initiator (I-line photo initiator), benzophenone (benzo-phenone) or water-soluble monomer can be added selectively, after passing through (1) substrate Substrate Clean→(2)Coating→(3)Vacuum Dry→(4)Pre-baking→(5)Exposure→(6)Development (Developing) → (7) Post-baking and other processing steps (Pattern) imaging, as shown in Table 1 represents the influence of different resin molecular weights on the photoresist line width value, different molecular weight acrylic resin, according to The molecular weight (Mw) decreases from 28,141 of resin (4) to 10,000 of resin (1), and the line width value decreases from 67.40 to 53.73, and the closer to the mask line width value of 50, that is, the closer to the mask The size of the image, of course, the better the resolution. As shown in FIG. 2 , the line width value CD2 of the photoresist layer image is significantly shortened, which is closer to the size of the mask image, and of course the resolution is also better. If a resin with a molecular weight (Mw) greater than 40,000 is used, it often cannot be resolved between 40-50um equidistant adjacent line widths and line spacings, that is, adjacent photoresist lines will be connected together. If it is less than 30um, it cannot be resolved at all. Under the development conditions allowed by the general process, the mask is 50um, and the photoresist line width is about 70um.

Table 2 represents the influence of different PDI values of the resin on the photoresist linewidth value. The molecular weight (Mw) of the resin is 15,000, and the range of PDI values varies from 3.5 to 4.0 in resin (6) to 1.8 to 1.8 in resin (5). 2.5, the line width value ranges from 60 to 63 to 56 to 58, the closer to the mask line width value of 50, that is to say, the closer to the size of the mask image, the better the resolution of course. If a resin with a PDI value greater than 4.0 is used, the line width of the photoresist will be greater than 65um when the mask is 50um, and the resolution will drop a lot.

The idea of the present invention is to create a high-resolution image, which can be applied to a new type of negative photoresist that requires high resolution. In the entire process of creating ideas, it is not easy to use a single component The structure of the compound must have the properties it should have, but must be indirectly evaluated in the tedious manufacturing process (process, preparation process) of the mixture. By constantly changing the structure of the ingredients with similar properties, we can explore the structure that may have the required properties. , and then determine whether the properties of each component can enable the final negative photoresist to successfully match the ever-increasing resolution (Pixels) of the image detector.

As mentioned above, the present invention provides a high-resolution image that can be applied to a high-resolution negative photoresist that requires high resolution, so an application for a patent for the invention is submitted according to law; however, the above implementation The description and drawings are preferred embodiments of the present invention, and are not intended to limit the present invention. Therefore, all similar and similar structures, devices, and features of the present invention should belong to the creation purpose and purpose of the present invention. within the scope of the patent application.

Claims (8)

1. high-resolution negative-type photoresist comprises at least:

Macromolecule resin, 6% to 50% percentage by weight;

Pigment, 2% to 15% percentage by weight;

The sensitization initiator, 1% to 10% percentage by weight;

Monomer, 2% to 10% percentage by weight;

Solvent, 42% to 88% percentage by weight;

Adjuvant, 1% to 14% percentage by weight;

Wherein, this macromolecule resin is that weight average molecular weight is lower than 40,000; And the range of molecular weight distributions of this macromolecule resin is less than 3.5; And

Wherein, described macromolecule resin is that methyl methacrylate, methacrylic acid are acryl resin main and that other small amounts of monomer constituent is formed.

2. photoresist as claimed in claim 1, wherein the weight average molecular weight of this macromolecule resin is lower than 20,000.

3. photoresist as claimed in claim 1, this pigment is any of the inorganic pigment of CI pigment yellow, CI pigment orange, CI paratonere, CI pigment violet, CI alizarol saphirol, CI naphthol green, CI pigment brown, CI pigment black or organic pigment, or with any mixing of paint.

4. photoresist as claimed in claim 1, this sensitization initiator be I linear light initiator, acetophenone based compound, benzophenone based compound or diimidazole based compound any or with any mixing of glazing initiator.

5. photoresist as claimed in claim 1, this solvent are that any or above solvent of glycol propyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, ethylene glycol monomethyl ether, ethylene glycol ethyl ether, diethylene glycol monomethyl ether, carbitol, butylcarbitol, 1-Methoxy-2-propyl acetate, propylene-glycol ethyl ether acetate, propylene glycol propyl ether acetate, 3-ethoxyl ethyl propionate mixes arbitrarily.

6. photoresist as claimed in claim 1, this adjuvant are pigment dispersing agent.

7. photoresist as claimed in claim 1, this adjuvant are non-ionic interfacial agent.

8. photoresist as claimed in claim 1, wherein the acid value of this macromolecule resin is between 40～250mgKOH/g.

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