JPS5815939B2 - Red-crowned night heron - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a solvent-free method for completely removing organic photoresists from a substrate.

Prior to this invention, a method for removing carbon and carbonaceous materials from substrates such as internal combustion engine components was the Bolsoff method described in US Pat. No. 2,443,373.

Bornff has demonstrated the ability to remove carbonaceous materials from various substrates at temperatures of approximately 150 to 260 degrees Celsius in an atmosphere of oxygen and ozone, compared to temperatures of 400 degrees Celsius in an oxygen atmosphere without ozone. It describes what can be done.

In the Bolsoff device, heat is generated by a hot plate located below a perforated substrate support member within the enclosure.

Although Bolsoff's method provides effective removal rates of carbonaceous materials, it is not suitable for continuous operation.

For continuous operation, the carbonaceous substrate must be preheated before entering the oxygen and ozone atmosphere because the hot plate does not provide enough heat to raise the temperature of the substrate quickly enough.

It is believed that the oxygen and ozone atmosphere must also be maintained at a sufficiently high temperature to minimize undue cooling of the substrate.

As a result of overheating of the oxygen-ozone mixture, the ozone decomposes prematurely, which prevents the desired result.

A method that substantially avoids the problem of preheating a substrate to remove carbonaceous material therefrom is described by Wright et al. in US Pat. No. 3,664,899.

Wright et al.'s method is based on the use of ultraviolet light in an oxygen-containing atmosphere.

External heating means, such as the hot plate utilized in Bolsov's method, are not used.

Wright et al.
Using an ultraviolet source capable of emitting ultraviolet light with wavelength A,
Complete removal of the organic polymer coating is achieved.

Lights and other UV sources, such as medium vapor pressure mercury lamps, heat the substrate by absorption of radiant energy and utilize the heat generated during photodepolymerization.

Furthermore, although sufficient heat is generated by the discharge lamp to remove the coating, the radiant energy does not change the temperature of the oxygen-containing gas in the surrounding atmosphere.

However, experience has shown that even with pure oxygen, the removal rate in the Wright et al. process does not substantially exceed several hundred amps per minute.

While this removal rate is adequate for a variety of applications, it is not an adequate removal rate for semiconductor manufacturing equipment where there is an interest in continuously removing negative photoresist from a wafer.

For example, the removal requirement for semiconductor manufacturing equipment is 1000 per minute.
It can be as high as 0X.

The present invention provides that when a UV source, such as a medium vapor pressure mercury lamp, is used in combination with a mixture of ozone and oxygen, as compared to when such a UV source is used with oxygen, as shown in FIG. Based on the finding that a surprising improvement is achieved in the speed of removing photoresist from.

In this specification, the term "ultraviolet discharge lamp" is used below.
A lamp having a clear fused silica envelope with an ultraviolet transmission characteristic of about 1800 to 3500 degrees, containing mercury vapor at a pressure of 0.5 to 20 atmospheres, and operated at a load of 20 to 100 watts/cm. say.

However, other UV sources such as xenon, metal halides, metal arcs, etc., which have radiant energy transmission properties comparable to the mercury vapor lamps just defined, can also be used.

For a more detailed explanation, please refer to the book "High Pressure Steam Discharge" by Ellen Bass, kW, published by North Holland Publishing Company, Amsterdam in 1951.

Figure 1 also shows that the use of UV light in combination with oxygen and ozone significantly improves the photoresist removal rate compared to using a mixture of oxygen and ozone at the same surface temperature without UV light. There is.

The present invention provides a method for completely removing carbonaceous material from a substrate surface in a reaction zone having an oxygen-containing atmosphere with at least 1/4 weight percent ozone at temperatures up to about 260°C. The energy is used to increase the temperature at the interface between the substrate and the oxygen-containing atmosphere by at least about 2
Keep at 00℃.

The radiant energy is at least 100% per square centimeter.
A method is provided in which the ultraviolet radiation is generated by an ultraviolet discharge lamp capable of emitting ultraviolet radiation with a wavelength of 1800 to 3500 A at an intensity of milliwatts.

Among the organic photoresists that can be removed from a variety of substrates by the method of this invention are the following organic materials:

Here, m is 0 or 1, and n is an integer and is at least 10.

When m is 0, the acetylenic polymer is jetynyl alkane (alkadiyne), jetynyl haloarene, or hasiethynyl haloarene.

That is, R is alkylene and arylene including alkyl-substituted haloarylene.

Alkylene diacetylene monomers are easily produced by the reaction of sodium acetylide and alkylene civalide.

Arylene and haloarylene type siat tyrene monomers include the corresponding divinylarenes, such as divinylbenzene, divinyltoluene, divinylnaphthalene, etc., or diacetylarenes, such as diacetylbenzene, divinyltoluene, diacetylxylylene, diacetylnaphthalene, etc. , diacetylanthracene, etc., followed by dehydrohalogenation.

Photosensitizers that can be used in combination with the aforementioned polystyrene include various dyes, carbonyl compounds, e.g. ketones, aldehydes, anhydrides,
Quinones, such as ■, 4-jethynylbenzene, etc., can absorb the actinic radiation to which they are exposed, and use the energy thus absorbed to promote cross-linking in polymers incorporating them. Any material that can be used.

In addition to the acetylenic polymers mentioned above, organic polymers substituted with unsaturated imide groups can also be used in the practice of this invention.

Among these unsaturated imide-substituted organic polymers are polyarylene oxides, polycarbonates, polyesters, polyamides, polystyrenes, and the like.

Other photopolymers that can be used are those described in U.S. Pat. No. 2,948,610 for azide polymers, those described in U.S. Pat. No. 2,725,372 for unsaturated esters of polyvinyl alcohol, Eastman Kodak These include photoresists KPR and KMER from Co., Ltd., and cinnamoyl-polystyrene resin.

Other photosensitive materials are described in Jaromir Kozar's book Photosensitive Systems, Chapter 4, pages 137-155, published by John Wiley & Sons, New York, 1965. .

For example, polyvinyl cinnamate, cinnamide of styrene maleic anhydride, copolymers of N-(cinnamoylphenyl) urethane derivatives, partially hydrolyzed cellulose acetate containing 3- or 4-(α-cyanocinnamide) phthalic anhydride. , soluble polyamide, photosensitive cinnamylidene aryl vinyl acetophenone, etc., U.S. Patent No. 2
These include the polymer described in No. 908667, a chalcone type compound such as benzalacetophenone, and the like.

In addition to the above-mentioned reforming organic polymers, which can be applied to various substrates in the form of organic solvent solutions or melts by spraying, dip coating, spinning, etc., for example butadiene, 1. 5-hexadiene 2. Dienes such as 4-hexadiene, hexachlorobutadiene, tetrafluoroethylene, ethylene, methyl methacrylate, N-phenylmaleimide, phenol, pyromellitic dianhydride, acrylyl), etc. and U.S. Pat. No. 3,522,226
Organic polymer coatings made by surface photopolymerization of various organic monomers that can be photopolymerized in the vapor phase, such as the other materials described in this issue, can also be removed within the scope of the method of this invention. .

Substrates that can be used in the practice of this invention include any material that can be etched, such as metals, metalloids or their oxides, such as gold and silver, aluminum, tin, copper, silicon oxide, and the like.

In the method of the present invention, complete removal of organic photoresist from a substrate, such as a silicon wafer, can be accomplished in an oxygen-osine atmosphere using radiant energy comprising ultraviolet radiation at wavelengths from about 1800 to 3500X.

Because of the toxicity of ozone in the oxygen-osine atmosphere, it is preferred to use a closed system or a system that is capable of continuous or intermittent operation and is shielded from the operator.

One type of device is shown, for example, in FIG. 2 of US Pat. No. 3,664,899.

To achieve effective results using the parameters of the method of this invention, the
It has been found desirable to be able to obtain coating removal rates of up to or greater than X.

It has been found that under certain circumstances, removal rates as high as greater than 10,000 A per minute, such as 15,000 A per minute, can be achieved depending on the temperature of the substrate or surface of the photoresist that is directly exposed to ultraviolet radiation. It was found that various factors influence the

For example, the concentration of ozone in an oxygen atmosphere, the temperature of the surface of an organic photoresist, the intensity of radiant energy, the wavelength of ultraviolet light,
These include the properties of the organic photoresist to be removed.

Experience has shown that organic photoresists are exposed to UV light in the presence of an oxygen atmosphere containing, for example, 1/4 to 2% ozone, preferably 1/2 to 2% ozone, based on the weight of the oxygen-ozone mixture. It turned out that the best results could be obtained.

For example, by passing oxygen gas through an ozonizer, such as an electric discharge type, such as the Wellsbach Ozonizer T816,
Ozone can be introduced into the oxygen mixture.

If desired, liquid ozone can be used as a source, but for safety reasons it is preferred to generate the ozone in situ in the presence of oxygen.

The pressure at which the oxygen-ozone mixture can be used is preferably 740 to 780 torr, although effective results can be obtained at pressures as low as 700 torr or as high as 800 torr.

The temperature at which the most effective rate is achieved is about 200 to 26
It is 0°C.

Effective results can be obtained at higher as well as lower temperatures, depending on the forces with which the substrate can withstand the change in properties.

The temperature is satisfactorily controlled by using ultraviolet light generated by a medium vapor pressure mercury lamp as previously described at various distances to achieve at least 100 milliwatts per square centimeter on the surface of the photoresist. I can do it.

Surface temperature can be measured by thermocouples placed on the surface within the radiant flux.

To maximize the removal rate, ultraviolet light having a wavelength within the range of 1800 to 3500 A, preferably 1849 to 3000 A, can be used.

Those skilled in the art will appreciate that the term "radiant energy" includes infrared and visible light that contributes to the effectiveness of this invention and is naturally generated by the ultraviolet discharge lamps described above.

The intensity of the radiant flux can be easily changed depending on the rating of the lamp used, the distance from the surface of the organic polymer coating to the lamp used, etc.

Measurement of radiant intensity is described in Applied Optics Magazine No. 4.
Volume No. 2 (December 1965), page 1547, R, G,
This can be done using a thermopile as described by Johnston and R.P. Matsden.

The method of this invention can effectively remove organic polymer coatings having thicknesses up to about 1 mil or more.

The removal of organic polymer coatings according to this invention
Journal of Applied Physics Vol. 39 No. 141
9 (1968) [can refer to a carbon-free surface as determined by the Auger emission analysis method described by L.A. Harris.

The following examples are provided to enable those skilled in the art to practice the invention.

This does not limit the invention.

All parts are parts by weight. Example 1 A wafer of silicon having a diameter of approximately 1-inch and having a uniform silicon oxide coating of approximately 1 micron is photoresist.
It was placed in a spinner and treated with a hexagonal solution of polyacetylene in a mixed solvent of toluene and xylene.

A silicon wafer was spun at about 200 rpm to produce a resist with a thickness of about 150 OA.

The polyacetylene used in the polymer solution was essentially about 97
It was a copolymer composed of 2,2-bis(41-propargyloxyphenylpropane) in molar proportion and 1,4-jethynylbenzene in about 3 molar proportion.

The treated silicon webbers were dried in air at room temperature for about 30 minutes using a flow of nitrogen to aid in evaporation of the solvent.

A silicon-weber composite was obtained consisting of a silicon base, a silicon oxide coating approximately 1 micron thick, and an upper polyacetylene layer approximately 1500 nm thick.

A silicone Weber composite was placed over the exposed area, contacted with the polyacetylene coating, and the contact mask was tightened.

Figure 2a shows polyacetylene coating - silicone wafer.
A mask complex is shown at 20.

In this figure, 10 is a silicon substrate, 11 is a silicon oxide coating, 12 is a polyacetylene resist, and 13 is a mask.

The polyayathylene coating is then exposed to an ultraviolet light source in the form of a GEAE4 lamp rated at about 100 watts for about 10 to 15 seconds, as shown in Figure 2. It's a public exposure.

The exposed polyacetylene coating was developed as shown in FIG. 2C by stirring the silicone wafer in toluene for about 4 minutes.

Next, dry the silicone wafer at about 60°C for 1 hour.
The solvent was removed from the complex.

Figure 2d shows the exposed silicon oxide on the composite being etched with a hydrogen fluoride etching solution containing ammonium fluoride buffer.

After 11 minutes, the silicone Weber composite was washed and rinsed with water and air dried at room temperature.

A silicon base and silicon oxide wafer composite etched in the form of and protected by a photoresist was obtained.

A silicon wafer was placed at the bottom of the horizontally arranged cylinder, just below the quartz window in the cylinder wall.

The cylinder was then flushed with nitrogen and a thermocouple was placed on the surface of the weber.

Next, a mixture of oxygen and ozone with about 1/2 to 2 parts by weight ozone made by a silent discharge ozonator, such as a Wellsbach ozonator, was introduced.

A GEHT37 ultraviolet lamp was turned on to apply ultraviolet light to the surface of the weber through the quartz window while an ozone-containing oxygen stream was passed over the surface of the weber at atmospheric pressure.

The lamp distance is approximately 2 inches from the surface of the weber, which results in a ballast of at least 1 inch per square centimeter on the surface of the weber, resulting in a 900 watt ballast.
This is sufficient to provide 0.00 mW of ultraviolet radiation.

The 0.15 micron photoresist present on the surface of the silicon wafer disappeared in 10 to 15 seconds, as shown in FIG. 2C.

This corresponds to a speed of approximately 1000of/min.

From the temperature at the surface of the weber based on thermocouple readings according to the method of R.C. Joston and R.P. Madden previously described, it was determined that the average temperature of the surface was 210° C. during the removal of the photoresist. understood.

The surface of the resist was then examined by Auger emission spectroscopy and was found to be completely free of carbonaceous residue.

Example 2 The procedure of Example 1 was repeated except that a photoresist with an average thickness of about 1000 OA was introduced continuously into the reaction zone.

A horizontal cylinder 6 inches in diameter and 8 inches in length was used as the reaction chamber.

A quartz window 4 inches wide by 11/2 feet long was placed in the center of the top of the steel cylinder.

The carrying chain is a 4 inch wide braided metal steel belt.

Said cylinder has a discharge orifice at the top near one side of the window and a duct introducing the oxygen and ozone mixture at the bottom opposite the quartz window.

The cylinder was shielded from the nitrogen atmosphere at each end on both sides.

Four GEHT type 37 lamps were used, and the distance from the Weber to the quartz window was approximately 1 inch.

The lamps were each operated at approximately 900 watts and the oxygen and ozone mixtures were within the concentrations given in Example 1.

Several semiconductor wafers with photoresist on their surfaces as described in Example 1 were successively passed under a quartz window in an ozone and oxygen atmosphere.

By using a thermocouple on one weber passing through the reaction zone, the surface temperature of the weber was found to be approximately 250°C.

The Weber passed through the reaction zone in about 1 minute, resulting in an average removal rate of about 1000 OA.

Depending on the thickness of the photoresist on the surface of the weber, the speed of the conveying chain is varied so that the weber is completely free of photoresist, as determined by the auger discharge method according to the method previously described.

Although the examples described above are limited to only a few of the many variables that can be used in the practice of this invention, the present invention can be used to statically or continuously remove various carbonaceous materials from various substrates. It goes without saying that this invention can be used.

This invention can take the following embodiments in relation to the claims.

(a) The oxygen-containing atmosphere contains 1/2 to 2 parts ozone.

(b) The substrate is a semiconductor wafer.

(c) The substrate is a silicon wafer.

b) the substrate is continuously conveyed through the reaction zone.

[Brief explanation of the drawing]

FIG. 1 is a graph showing a comparison of removal rates between the present invention and a conventional method. FIG. 2 is a process diagram showing a method of making and removing photoresist. Explanation of main symbols: 10: Substrate, 12: Photoresist.

Claims (1)

[Claims] 1. A method for completely removing organic photoresist from the surface of a substrate at temperatures up to about 260° C. in a reaction zone having an oxygen-containing atmosphere with at least one-quarter weight ozone. a reaction between the organic photoresist and the oxygen-containing atmosphere at the interface between the organic photoresist and the oxygen-containing atmosphere, and the radiant energy is ultraviolet radiation capable of emitting ultraviolet radiation with a wavelength of 1800 to 3500 A at an intensity of at least 100 milliwatts per square centimeter of the substrate surface. A method characterized in that the generation is performed using a discharge lamp.