DE2321684A1 - METHOD OF GENERATING PATTERNS - Google Patents

Description

WESTERN ELECTRIC COMPANY * ^## "Bowden; * M ^.: JS; 1- ^ 2τ ¹ -

INCORPOATED

New York, N.Y., 10007, USA Method of generating patterns

The invention relates to a method for generating patterns from radiation-sensitive lacquer on a substrate by irradiating a positive lacquer layer sensitive to electron radiation, which is a polymer of an olefin and sulfur dioxide contains, with an electron beam.

In the manufacture of semiconductor circuits, the current trend is towards the highest circuit function density per unit area of the semiconductor. This miniaturization affects the reliability, operating speed and economy of semiconductor circuits cheap. Although the research has continued, there is further miniaturization beyond what is achievable with current technological means because of the photolithographically prescribed Pattern definition limited. In the last 10 years electron beams have been used more and more frequently to paint coatings Manufacture of microelectronic components to irradiate and delivered

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successful fine line patterns, which are created with the means of

conventional photolithography would not have been possible. Various photosensitive compositions with monomeric and crosslinkable polymer compounds and elements are well known. For example, addition polymers of the type described in U.S. Patents 3,418,295 and 3,469,982, respectively, are widely used to create relief images.

Unfortunately, these photosensitive compositions exhibit properties of electron radiation sensitive negative resists, which are not suitable for certain applications. That's why Experts turned their interest to the development of electron radiation sensitive positive resists, which are briefly referred to below as positive electron resists. Despite continued efforts in this direction the electronic lakes were never fully evaluated. The ultimate goal of high sensitivity in the

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The order of magnitude of 10 coulombs / cm has recently only been used at certain negative electron resists. One and only Positive electron resist of any importance which has been reported in the literature so far was polymethyl methacrylate.

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The sensitivity of this material is around 5 χ 10 Coulomb / cm, although some reports that even higher sensitivities can be achieved have been noted. However, the

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Reaching such high sensitivities required processing conditions not been satisfactory.

According to the invention, a method for generating patterns is from radiation-sensitive lacquer on a substrate by irradiating a new positive electron lacquer, which is a Polysulfone contains, described, which is at least one order of magnitude higher sensitivity than any known positive electron resist owns. The paint described is the reaction product of sulfur dioxide and certain hydrocarbon chains, which can be cyclic, unbranched or branched.

A general outline of a process suitable for producing an electron lacquer is given below. Certain operating parameters and ranges are indicated as well as the type of material used.

The described polysulfone electron lacquer is based on one Polymer formed by reacting sulfur dioxide with an olefinic compound. That for this one Purpose chosen olefin can be a cyclic olefin of 5 to 8 Carbon atoms, a compound of the general formula

R.
CH ₂ = C

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in which R consists of hydrogen and alkyl groups with 1 to 3 Carbon atoms is selected and η is an integer from 1 to 6, or a 2-olefin of the general formula

CH. - CH = CII - (CH ₀ ) - H «3 Zn

where η is an integer from 1 to 3.

Olefins particularly suitable for the present purposes are: Propene, butene, pentene, hexene, octene, butene-2, hexene-2, cyclohexene, cyclopentene, 2-methylpentene-1, etc. These materials can be obtained inexpensively from the trade.

Any known conventional method can be used in preparing the desired polymer. In a typical procedure, the reactants are allowed to condense in a suitable reaction vessel at a temperature of about -80 ° C. The reaction vessel is then degassed to a pressure of about 10 millitorr, and then smaller with light having a wavelength of 3600 A at a temperature below the Polymerisationseinsatztemperatur irradiated: After cooling to turn about -80 C, the reaction vessel is opened and allowed to cool ^l to room temperature at which the excess monomer is evaporated. The desired polymer is then in

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CG) PY

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dissolved in a suitable solvent. Particularly useful solvents for this purpose are: Methyläthylkcton, Diojcan, Chloroform, etc. Those skilled in the art know that the choice of a particular solvent will be determined by the solubility of the polysulfone. The dissolved polymer is then applied to a suitable substrate using conventional centrifugal methods. The desired one the final layer thickness is 2000 to 8000 Å. Although the resolving power through the use of a thin layer is improved, the occurrence of pinholes practically prescribes a minimum layer thickness of 2000 Å. At this stage of processing a preliminary heat treatment is expediently carried out in order to remove excess solvent and to make the layer free of tension. A program "suitable for this purpose would include heating to a temperature" above the glass transition temperature, usually between 80 and 100 C for 10 to 300 minutes, enclose »

After that, the layer is made from an electron radiation source, using an acceleration voltage between 3 and 25 KVoIt and one Dosage that depends on the material, but is usually larger

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than 1x10 coulomb / cm, irradiated. The observed voltages and Dosages are determined by the "resolving power and the material properties. The next processing step concerns the development of the irradiated layer. That can

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by using a developer, which usually consists of a mixture of ketones and alcohols. Developing can practically by soaking or spraying the irradiated layer with a suitable one for 5 to 60 seconds Developer done. After development, a final heat treatment between 50 and 150 C for 5 to 120 minutes can be made to evaporate the developer and improve the adhesive properties. These operating parameters are determined by the property of the chosen polysulfone. ,

Alternatively, the described electron resist can be developed without any solvent or wet developer. Because im Development process does not use a solvent, it is necessary that the degraded residues of the irradiated polymer depolymerize at the irradiation temperature. Process-wise this is practically done by irradiating the electron lacquer at a Appropriate dosage and temperature reached, which are determined by the material properties. Below is an example of the present invention will be described in detail. These examples are only given in order to better understand the invention should do. Those skilled in the art can make changes without departing from the spirit and scope of the invention.

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example 1

. Approximately equimolar proportions of butene-1 and sulfur dioxide (14 g of butene-1 and 7 g of sulfur dioxide) were in one, at -80 C held Pyrex glass tube condensed. The pipe was then on

—3 passed a vacuum line and reduced the contents to about 10 mt degassed. The tube would then be irradiated with ultraviolet light from a medium pressure mercury source at 0 C and rotated during irradiation to prevent polymer deposition on the pipe walls. Then the content the reaction tube cooled again to -80 C, the tube opened and its contents allowed to cool to room temperature, at which the superfluous monomer is evaporated. The resulting poty (butene-1 sulfon) was dissolved in acetone, in methanol precipitated and dried at 40 C in a vacuum. Then it was dissolved in methyl ethyl ketone. Then a silicon dioxide / Silicon-containing substrate selected and a 2% poly (butene-l Sulfone) solution at 4000 revolutions / minute about 3500 Å thick in methyl ethyl ketone. The shift was 10 minutes subjected to a preheating treatment at 80 C for a long time and then with a programmed electron beam of a dose of approximately

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3x10 Cculomb / cm at an accelerating voltage of 5 kV irradiated. Then the irradiated layer became through 15 seconds Spraying with a solution of 55% methyl ethyl ketone and 45%

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2-propanol developed.

"The sensitivity of the resulting electron resist became too

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found about 3x10 coulombs / cm. The structure described was then etched in buffered hydrogen fluoride. That included determined resolving power was at least 4000 Å.

Example 2

The procedure outlined in Example 1 was repeated, with the exception that a tungsten substrate was used. The sensitivity of the resulting electronic enamel was determined to be approximately 3 × 10 ^T coulombs / cm. The tungsten was etched with a potassium hydroxide-potassium ferride cyanide solution and the remaining electron lacquer was removed with methyl ethyl ketone. The resolving power determined was at least 4000 Å.

Example 3

The procedure outlined in Example 1 was repeated using a

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Radiation dosage of 4x10 coulombs / cm at ambient temperature was used. Under these conditions, the electron resist is patterned without any solvent or wet development and developed. Investigations of the resolving power revealed no changes, although the edge sharpness of the etching

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lines were improved compared to the lines etched by wet developed masks. The root mean square value of the marginal deviation was + 300 A, a significant advantage over electro-optical components.

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Claims (5)

P ATENT CLAIMS 1. Method for generating patterns from radiation-sensitive Lacquer on a substrate by selective irradiation of a positive lacquer layer that is sensitive to electron radiation - 7th with an electron radiation dose greater than 1 χ 10 coulomb / cm, -6 2 preferably of the order of 1 χ 10 coulomb / cm, characterized, that the positive resist layer consists of intermediate reaction products of sulfur dioxide and of at least one of the following olefinic Connections is selected: (a) cyclic olefins having 5 to 8 carbon atoms, (b) Compounds of the general formula CH = C- (CH V H / δ η in which R is selected from the group consisting of hydrogen and alkyl groups having 1 to 3 carbon atoms and η is an integer from 1 to 6,
(c) compounds of the general formula CH. - CH = CH- (CH.) H, u dt H in which η is an integer from ί to 3. 30 9846/09 0 5 2. The method according to claim 1, characterized in that the reaction product is generated by reacting of sulfur dioxide with at least one of the olefinic compounds and by irradiating the resulting product with light having a wavelength less than 3600 Å at a Temperature below the polymerisation start temperature. 3. The method according to "claim 1 or 2, characterized in that the Otöinische connection under at least the following Compounds is selected: propene, butene, pentene, hexene, octene, butene-2, hexene-2, cyclohexene, cyclopentene, 2-methylpentene-1. 4. The method according to claim 3, characterized in that that butene-1 is used as an olefinic compound. 5. According to one of claims 1 to 4 produced on a substrate paint pattern. 309846/0905