JPS58160951A - Positive resist material, manufacture thereof and positive resist for forming surface texture of material made thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermally crosslinkable positive resist material, a method for producing the same, and a positive resist for forming a surface texture on a material made of a mosquito material.

The resist forms a radiation-sensitive film whose solubility varies upon irradiation with high-energy radiation. Depending on whether the solubility of the film layer decreases (% negative resist l) or increases (% positive resist), it is classified into two types of resists. In the first case, after irradiation, the unirradiated areas are removed with a suitable solvent. In the second case, the irradiated parts are removed. These resists are applied in a thin layer to the material and subjected to an irradiation and wash-off process (currently) carried out, for example, by means of a mask original, for example etching or They are used for texturing of material surfaces by electroplating. Among other things, these resists are used in semiconductor technology (ultra-high density integrated circuits).
-ry large 5cal@Integratlo
n) = VL 8 I), electronic components (printed circuits,
integrated circuit) manufacturing and printing technology (screen printing plate)
used in

A series of resists is already known for copying microstructures into semiconductor components, for example for microelectronics. U.S. Patent Nos. 3,535,137 and 3
No. 779,806 describes a polymethacrylic acid ester as a resist, which can be used to copy a predetermined figure onto a paste using an electron beam. DE 2610301 discloses a positive-acting thermally crosslinkable resist containing an alkyl methacrylate-methacrylic acid tetralide copolymer. One drawback of these resists based on polymethacrylate esters or alkyl methacrylate-methacrylic acid chloride copolymers is low sensitivity.

Resists based on halogenated polymethacrylic acid esters are known from West German Patent Application No. 2702427, Japanese Patent Publications No. 55-24088 and No. 53-100774, which are sensitive to high-energy radiation 41. However, it does not have sufficient adhesion to pace.

The object underlying the present invention is therefore to overcome these known drawbacks and to have the desired specific resist properties and, above all, a high sensitivity to radiation as well as sufficient mechanical stability and adhesive strength to the paste. The objective is to obtain a resist that also has the following properties.゛The present invention provides a resist material comprising a thermally crosslinkable methacrylic polymer soluble in an organic solvent, wherein the methacrylic polymer contains 80 to 98 moles of fluoroalkyl methacrylate and <a) methacrylic acid chloride or (b) chloride. The present invention relates to a positive thizoresist material characterized in that it is a copolymer consisting of 20 to 2 moles of alkyl methacrylate.

In the case of 1) (fluoroalkyl methacrylate and methacrylic acid chloride), the copolymer has inter alia the general formula: -represents an alkyl group having -, fll and ns are integers, and 1 degree of polymerization n =
nl tenag is 300-3000 and the molar fraction of methacrylic acid chloride n/n is 0.02-0.20, and 5-50% of the acid chloride groups can be present as carxyl groups]. In the case of b) (fluoroalkyl methacrylates and chloralkyl methacrylates), the copolymer has inter alia the general formula: [where BL is a fully or partially fluorinated, preferably carbon-atom] a3 is preferably an alkyl group having from 2 to 6 carbon atoms and one ω-
Partially chlorinated alkyl group with trichloromethyl group! Expression 1 degree of polymerization n = nt + Kll is 300
~3000 and mole fraction n@/n is 0.02-0.2
0].

The fluorinated alkyl group a or EL"Fi can be fully or partially fluorinated and branched or preferably linear. In particular, it is a hexafluoroalkyl group, and especially 2,2, 3.4.4.4
-hexafluorobutyl.

The partially chlorinated alkyl group a"Fi with an ω-trichloromethyl group in the terminal position can be branched or preferably linear. For example, it can be 2 s 2
s2-) Lichlorethyl.

Copolymers are statistically synthesized from these comonomers.

The resist can be crosslinked during heat treatment with the formation of intermolecular bonds until it becomes insoluble in certain developers. In this case, the degree of crosslinking is determined by the temperature and time of thermal crosslinking and the concentration of crosslinking groups. Generally, a copolymer (1) consisting of fluoroalkyl methacrylate and methacrylic acid chloride is crosslinked at a temperature of 100 to 170°C and a time of 10 to 30 minutes; ) at a temperature of 180-250℃ and a time of 1
It is 0 to 30 minutes.

In the case of a) (fluoroalkyl methacrylate and methacrylic acid chloride), the acid chloride groups of a portion of the copolymer and the remaining moieties already present in the organic solvent during contact with this solvent form a polymer. In a similar reaction, thermal crosslinking (pre-heating step) is required under the formation of anhydride groups, which reacts with the formation of carxyl groups. These reactions are schematically illustrated for the formation of calxyl groups (1) and intermolecular anhydride groups (2) from the lower part: If the amount of water present in the organic solvent is insufficient for this, a small amount of water can be added. The copolymer solution containing the resist can be stored until sufficient thermal crosslinking of the resist can be obtained (this may advantageously be carried out under an inert gas atmosphere).
(eg carried out under nitrogen), 5-50 acid chloride groups can be present as carzexyl groups.

In the case of b) (fluoroalkyl methacrylate and chloralkyl methacrylate), Tad (T, Tad
a) Paper by K.T. (Journal of the Electrochemical Society of Japan (J, citation)
roch@m, 8oc, ) Volume 126, Page 1635 (
Since 1979), poly-2,2,2-trichloroethyl methacrylate can be chemically crosslinked by heat treatment, and the mechanical properties are altered by ribbing and the solubility in solvents is degraded. It is clear that they are forced to do so. Complete crosslinking involving all macromolecules results in insolubility and high adhesion of the resist to the paste. Until now, the mechanism of crosslinking has not been elucidated.

According to the invention, the resist solution can be obtained by dissolving the copolymer in an inert organic solvent, in which the inert organic solvent that dissolves the copolymer according to the invention is used as the solvent. Methyl ethyl ketone, methyl isozotyl ketone and/or butyl acetate are preferably used as solvents.

Dissolution is preferably carried out at room temperature or at slightly elevated temperature. The concentration of the copolymer in the solvent is preferably from 5 to 20% by weight.

The resist material according to the invention is advantageously used as a positive resist for texturing of material surfaces, which is another object of the invention.

This material is preferably applied in a thin layer having a thickness of 0.3 to 3.0 μm, which can be done, for example, by centrifugal application (spinning) of the solution, and then this layer is thermally crosslinked and subsequently High-energy radiation, in the case of X-rays, is irradiated using a mask having a predetermined pattern, and the irradiated areas are eluted with a developer. By irradiation with high-energy radiation, the bonds in the main chain and the nine cross-linking positions are also broken down. This makes the resist material at the irradiation position soluble in the developer. Irradiation with TE is carried out using X-rays, electron beams or also ion beams. As developer it is possible to use organic solvents 9, for example solvents or solvent mixtures suitable for the production of resist materials.

According to the invention, zoronozonol-
(2), a mixture of propanol (2) and methyl isobutyl ketone or a mixture of propanol (2) and methyl ethyl ketone is used.
A particular advantage of the present invention is that pure propanol(2) can be used as developer. This makes it possible to avoid solvent mixtures that are often used as developers. The use of solvent mixtures as imaging agents is often problematic. The development time corresponds to that for Regis) KVl. Generally, this time is about 1-2 minutes.

Using the positive resist material according to the invention, resists are obtained which have great sensitivity as well as very good mechanical stability and adhesion.

This makes it superior to previously known methacrylic-based resists. For example, the resist according to the invention has a sensitivity that is a factor of 12 to 20 greater than resists based on polymethyl methacrylate. moreover.

Resists consisting of fluoroalkyl methacrylates and chloroalkyl methacrylates have extremely high storage stability at room temperature.

This resist material Fi is suitable for copying precise structures due to its large contrast coefficient. The resist according to the present invention can be used in a conventional manner in X-ray lithography.
For example, silicon, silicon dioxide, chromium, aluminum, and chiku. It is highly suitable for paste materials such as Ni, GaAl, etc.

EXAMPLES The present invention will be explained in detail below with reference to Examples, but the present invention is not limited by these Examples.

EXAMPLE l Apparatus required for the purification distillation of monomers is carefully freed of water and maintained under a constant stream of nitrogen. In a distillation flask, 1 ton of methacrylic acid loli PI-ott steel powder and ? lll and pressure 6
Distillation is carried out at a temperature of 30 to 33°C through a column using 100% linoleum. The central fraction is collected and fed to the polymerization as a 7-mer.

2.2,3.4.4.4-hexafluorobutyl methacrylate 100. t, 1 in the separation funnel for activation.
Wash with 20 ml of 0'j caustic soda solution and then with water until neutral, and after separating the phases, dry over calcium chloride.

The ester is then distilled off via a column at a pressure of 23 t and a temperature of 60 DEG to 63 DEG C.

The middle fraction is used for polymerization.

Example 2 Copolymerization of 2.2,3,4.4.4-hexafluorobutyl methacrylate and methacrylic acid chloride. 2.2, 3, 4, 4.
4-hexafluorobutyl methacrylate aop, methacrylic acid loli PO, 376fk and peroxide pencil k
o, 072f and melt with exclusion of moisture. Polymerization is allowed to proceed within 24 hours at a temperature of 80°C. The polymer is dissolved in dry methyl ethyl ketone, precipitated with dry benzene (boiling range 50 DEG -75 DEG C.) and separated from the solvent in vacuo. The yield is approximately 90-. Molecular weight measurement by gel permeability chromatography was performed using MW
-640000 and a value of M, 7μm-7.5 were obtained. This molecular weight measurement is calibrated using a 2% constant 4-trimethyl methacrylate fraction. The relatively broad molecular weight distribution before crosslinking does not impair the coating properties, since the resist is in a crosslinked state (very high molecular weight) after the preheating step.

The glass transition temperature was determined to be 58° C. with a differential scanning calorimetry needle.

Example 3 Conversion of acid chloride groups into carxyl groups The free acid chloride groups of one part already react with some residual moisture of the organic solvent during the dissolution and precipitation steps with the formation of carmexyl groups, which form carmexyl groups. is the preheating process (110℃
, 15 min) required for dehydration crosslinking. If the reaction of the grains with water is still insufficient, the copolymer solution is stored with a small amount of water in a nitrogen atmosphere in the open, in which crosslinking of the lacquer can be obtained in the preheating step. For subsequent use, it is advantageous to dry the resist material and store it in cool, dark conditions.

Example 4 Application Example To prepare a resist solution, the copolymer 15yt-methylisobutylketone asf prepared according to the previous example was dissolved. This m1lt.

Apply to the paste by centrifugation at 2000 rpm. Film thickness 0.
9 μm is obtained. In order to crosslink this resist) t-1
After preheating at 10° C. for 5 minutes, this film has very good mechanical stability and adhesion.

The sensitivity of this resist was measured using synchrotron radiation as well as electron beam (20 KV) t. As a source of synchronized radiation, a storage ring (Hamburg) with an electron energy of 1.5 G@V was used. The wavelength of maximum energy of the synchrotron radiation behind the Kapton filter was x=0.8.

Sensitivity tests were conducted with a film thickness of 0.5 μm. The current pay time was 90 seconds. The current drug used was propanol (2). Herring chrotron radiation with the following sensitivity
1lD5 = 45 m J/j electron beam (20K V
) DB = O-4μo/ai.

Compared to polymethyl methacrylate, the resist according to the invention exhibits a factor of 12 greater sensitivity.

Example 5 2.2. Preparation by azeotropic esterification of 2-trichloroethyl methacrylate Unactivated methacrylic acid methyl ester 100F (1 mol), trichloroethanol 224f (1 mol), concentrated sulfuric acid 5f, Penzol 300F and hydroquinone 5f
f mixed. This mixture 1- is kept boiling for 24 hours in an azeotropic distillation apparatus. The methanol produced in this case is distilled off.

After the reaction has ended, the solvent (penzol) and the unreacted residues of methacrylic acid methyl ester and 2.2.2-trichloroethanol are separated from the reaction mixture by distillation. The product is fractionated by vacuum distillation. The central fraxin carbonate (boiling point 74-76°C, tStS Paryl) is used for copolymerization.

Example 6 Copolymerization of 2.2.3.4,4.4-hexafluorobutyl methacrylate and 2.2.2-trichloroethyl methacrylate. According to example 1, nHL, 2, 2.3, 4.4.4
-hextefluorobutyl methacrylate) 4.76 f
, 2, 2, 2-) lychloroethyl methacrylate (Example 5 λ 0.22 f and benzoyl peroxide 12
Fill 11ft and melt.

Polymerization is carried out at a temperature of 80° C. within 23 hours.

The polymer is dissolved in methyl ethyl ketone, precipitated with pendine and dried in vacuo. Yield is about 45s.

The average molecular weight was determined to be MW = 2.0X10'; MW
/Mn=2.6° Example 7 Application example Coating of the paste surface In order to coat the paste surface, the copolymer prepared according to Example 6 was dissolved in a suitable solvent and this solution was preferably applied by spin coating. After application, the solvent was evaporated. A film with a layer thickness of 1 μm is prepared, for example, in a solution of copolymerization in methyl isobutyl ketone (100 y/l#) 't200
Stones obtained when centrifugally applied to the pace at 0 rpm. Continue.

The film was heated under nitrogen for 30 minutes at 180-24°C.
Heated to a temperature of 0°C. In the case of the irradiation test below, 2.0
A film heated to 0°C was used.

To examine the radiation sensitivity and contrast sensitivity and contrast coefficient, the film was exposed to synchrotron radiation.

chrontro sietrarunta, berlin chrontro
nstrahrung, Berlin) f+ was used. The maximum energy wavelength of synchrotron radiation after 7.5 μm Kapton filter and 9 μm silicon is λml
X ” O-8.1m corresponded to To9.1-55aV.

Development was carried out in Zoronorol-(2) at 23°C. Development time was 90 seconds. In the irradiation test, the initial layer thickness d
. Wo, sensitivity D9=25± when using 8μm film
5 mJ/gJ was obtained, ie the copolymer had a sensitivity 20 times greater than that of polymethyl methacrylate (PMMA). The contrast coefficient is r m 4.5. In the case of PMMA, it is r-2.9.

Figure 1 shows the irradiation dose of a copolymer consisting of 2,2,3,4,4,4-hexafluorobutyl methacrylate and 2,2°2-trichloroethyl methacrylate (5,3 mol). Figure 2 shows the relative reduction rate of layer thickness as a function (gradation curve).

Initial layer thickness d. =0.8 μm, dp: layer thickness remaining on irradiated and current fireflies, current agent: ProA-Nol-(2).

Development time = 90 seconds.

Adhesion The adhesion test was carried out using the cross-cut test method according to the German industrial standard DIN 53151.
Cross-cut test device 29 manufactured by Erlchsea)
The experiment was carried out using a lugisto film of %l#m thickness using type 5. A glass object carrier was used as a pace. Poly-2,2°3.4.4.4-hexafluorobutyl methacrylate (:1 monomer)2.2.
2-) Lichlorethyl methacrylate (95:!S Mol IIG).

Poly-2,2,3,4,4,4-hexafluorodithyl methacrylate (FBMIIO, manufactured by Daikin Industries, Ltd.) and polymethyl methacrylate (ES-KEM (GS))
The results obtained from these films are summarized in Table 1.

In the case of the homopolymer FB110, the %Gt-0-B value is 0%, that is, all the positive shapes obtained by cross-cutting are severely damaged, and the Gt-0-B value in the case of the copolymer MFOI is 0%. The B value is 985 g, ie only a very small portion of the squares show significant edge damage.

Compared to PMMA, the homopolymer FBM110 has a lower preheating temperature (prebaking) than is actually commonly used for this material [1
At 40° C., it was found to have poorer adhesion than PMMA.

A PBMIIO film preheated to 200°C is similar in adhesion to a PMMA film preheated to 140°C.

Table 1 Adhesion of the resist film to glass Measurements by the cross-cutting method according to German Industrial Standard D I N 53151 a) When cross-cutting, a given number of squares with dimensions 1×1- are obtained. The amount of squares remaining undamaged (o
* o B) e or.

The volumes of squares whose faces have been removed by peeling by up to 5 mm (Gt-1-B) and between 5 and 15 mm (Gt-2-B) are examined.

b) Polymethyl methacrylate, preheating: 150°C,
30 minutes.

C poly-2,2,3,4,4,4 dihexafluorobutyl methacrylate, preheating = (mm) 140″C, 3
0 minutes, CB) 200°C, 30 minutes.

d) Poly-2,2,3,4,4,4-hexafluorobutyl methacrylate (comonomer) 2.2.2-)lichloroethyl methacrylate) (95:5), preheating: 2
00tl:, 30 minutes.

[Brief explanation of the drawing]

FIG. 1 #i1 is a chart showing a gradation curve of a resist according to the present invention. F:'J, 1%xp 1rnJ/c#2) Continued from page 1 Priority claim @ December 17, 1982 ■West Germany (
DE) ■3246825.3 0 Inventor Wolfram Schnabel Berlin 38 Krodnauler Strasse 1, Federal Republic of Germany

Claims (1)

[Scope of Claims] L A resist material comprising a thermally crosslinkable methacrylic polymer soluble in an organic solvent, wherein the methacrylic polymer is fluoroalkyl I? A? A positive resist material characterized in that it is a copolymer consisting of 80 to 98 moles of methacrylate and 20 to 2 moles of methacrylic acid chloride or chloroalkyl methacrylate. 2 The copolymer is fluoroalkyl methacrylate 80
Positive V-cyst material according to claim 1, characterized in that it is a copolymer consisting of ~98 moles of methacrylic acid chloride and 20 to 2 moles of methacrylic acid chloride. The copolymer has the general formula: % formula % [wherein a is completely or partially fluorinated]. b represents an alkyl radical preferably having 1 to 9 carbon atoms;
1 and nl are integers, the degree of polymerization m is 300 to 3000, and the molar fraction of methacrylic acid tetralide is ns/a kaO, (1 to 0.20"t'aC, kat). 5~
501$12) It is characterized in that it has an acidic acid (1) in which the lido group is present as a carzexyl group. A positive resist material according to any one of claims 1 and 112. This Kyoden combination is fluoroalkyl methacrylate 8
0-98 molti and chloralkyl methacrylate-12
The positive resist material according to claim 1, characterized in that it is a composite. & copolymers having the general formula: [wherein Bl represents a fully or partially fluorinated alkyl group, preferably having 2 to 6 carbon atoms, Bl is one partially chlorinated 9-1 preferably represents an alkyl group having 2 to 6 carbon atoms and one ω-trichloromethyl group, with a degree of polymerization n = nl + n
5. A positive resist material according to claim 1, characterized in that the positive resist material has a richness of 300 to 3000 and a molar fraction fil /It of 0.02 to 0.20. & The positive resist material according to any one of claims 1 to 5 of the patent scope, wherein the fluorinated alkyl group is a hexafluoroalkyl group. 7. Fluorinated alkyl group is 2,2,3,4. The positive resist material according to claim 411, characterized in that it is 4,4-hext-fluorobutyl. & chlorinated alkyl Go is 2.2.2-}lichloroethyl, Claim 1, $4
and the positive resist material according to any one of Item 5. The organic solvent is methyl ethyl ketone, methyl isobutyl ketone and/or butyl acetate.1
*The positive resist material according to any one of claims 1 to 8, which is mold. 1α The methacrylic polymer is a copolymer consisting of 80 to 98 moles of fluoroalkyl methacrylate and 2.0 to 2 moles of methacrylic acid tetralide or chloralkyl methacrylate, a thermoplastic soluble in organic solvents. 1. A method for producing a positive resist material, which comprises dissolving the copolymer in an organic solvent. 11. The method for producing a positive resist material according to claim 10, characterized in that the copolymer is dissolved in methyl ethyl ketone, methyl isobutyl ketone and /t or butyl acetate. 12. The methacrylic polymer is a copolymer consisting of 80 to 98 moles of fluoroalkyl methacrylate and 20 to 2 moles of methacrylic acid chloride, soluble in organic solvents and thermally crosslinkable. 1. A positive resist for forming a material surface structure comprising a dithizoresist material comprising a methacrylic polymer. 13. A resist material is applied in a thin layer to the paste, cross-linked by heat, irradiated with high-energy radiation in the desired pattern, and the irradiated portion is eluted with a developer to form t% mold. A positive resist for forming a material surface structure, comprising the positive resist material according to item 12. 14. A resist material consisting of a copolymer of fluoroalkyl methacrylate and methacrylic acid chloride is crosslinked at a temperature of 100 to 170°C for 10 to 30 minutes before irradiation. A positive resist for forming a material surface structure, comprising the positive resist material according to item 13. 15,7 Resist material comprising fluoroalkyl methacrylate and chloralkyl methacrylate t% crosslinked at a temperature of 180 to 250°C for 30 to 90 minutes before irradiation, according to claim 13. Positive resist for material surface structure formation made of positive resist materials. 16. Irradiation with X-rays, electron beams or ion beams 1*Mold, Claims 13-Jll
The positive cash register according to any of Item I115. A positive resist for forming a material surface structure made of a transparent material. 17 Pronoarm Nol-(2), Pronoarm Nol-(
2) and methyl isobutyl ketone, or a mixture of zorononol-(2) and methyl ethyl ketone. A positive resist for forming a material surface structure made of a positive resist material.