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Monemolecular resists: a new class of high resolution resists for electron beam microlithography
World Abstracts on Microelectronics and Reliability beam mask-making systems in the light of future technologies such as optical wafer-stepping exposure, deep UV exposure, x-ray, and direct electron-beam exposure.
Monemolecular resists: a new class of high resolution resists for electron beam micmlithography. A. BARRAUD,C. ROSILIO and A. RUAUDEL-TEIXIER.Solid St. Technol. p. 120 (August 1979). A new class of ulthrathin (30 to 1000 A) electron-resists based on monomolecular layers is described. These negative resists make it possible, with a proper choice of the accelerating voltage, to achieve a very high resolution, even on thick substrates. The thickness-voltage combination is shown to be the main parameter, contrast being second order. These properties are illustrated by the example of c~-tricosenoic acid, which provides a resolution of 600 A when 450/~ thick, despite a contrast value of 0.7.
Response of diazoquinone resists to optical and electronbeam exposure. MICHAEL KAPLAN and DIETRICH MEYERHOFER. R C A Rev. 40, 166 (June 1979). The responses of diazoquinone/novolak resist systems to optical and electron-beam radiation are compared. The "intrinsic" sensitivity to radiation is determined by measuring the rate of destruction of the diazoquinone sensitizer with radiation. Under optical exposure, a quantum efficiency of 0.30 + 0.03 is measured for two different sensitizers and various resist formulations. This quantity is constant over the wavelength region of 350-450nm where only the photoactive site absorbs. Under electron irradiation, we measure G-values (number of molecules destroyed per 100eV of energy absorbed) of 7 8 for undiluted sensitizer films. The optical quantum efficiency and th'~"G-value can be compared in terms of the energy required to destroy one sensitizer site. This energy is 12.5eV for electron beam exposure and 10.5 for optical exposure. In resist films, the result depends on how the absorbed energy is partitioned between the sensitizer and the resin. If it is assumed that the energy is absorbed equally in both parts, then the G-value can be as much as a factor of 2 higher in the resist than in the sensitizer. These resist systems are positive-working for both optical exposure and electron irradiation at low doses. The solubility of the films changes more rapidly with energy absorbed for electron irradiation than for optical irradiation, if only the energy absorbed by the sensitizer is taken into account. The reverse is true if all the energy is included. Practical exposure values required for lithographic applications are 3-4 mJ/cm 2 optical dose and 7-20pC/cm 2 electron dose at 10kV.
Annealing of ion implanted layers by laser beam. JANUSZ KRYNICKI. Electron Technol. 12, (1) 77. The paper discusses the applicability of laser beam for annealing of implanted layers and presents the results of electrical, optical and backscattering investigations of laser-annealed implanted layers. The effects of impurity-profile broadening during laser action are reviewed. The results of laser and thermal annealing are compared.
Ar-ion implant damage gettering of generation impurities in silicon employing voltage ramping and nitrogen backscattering. B. GOLJA and A. G. NASSIBIAN. Solid-St. electron Devices 3, (5) 127 (September 1979). The effects of At-ion implant gettering has been investigated using the linear voltage ramp applied to m.o.s, capacitors. A comparison is made with control (not implanted) samples and N+-ion Rutherford backscattering is used to examine the precipitation of generation impurities by the damaged layers.
391
The gettering anneals were carried out over the temperature range 950°C-1100°C and for various times from 15 min to 120 min. It is shown that long gettering anneal times and high anneal temperatures both have a detrimental effect on minority-carrier lifetime.
Some annealing properties of low-energy-antimony-implanted silicon resistors. S. M. K u and W. K. CHU. Solid-St. Electron. 22, 719 (1979). Shallow-implanted antimony in silicon can be used in fabricating n-type silicon resistors with very low temperature coefficient of resistance (TCR), controllably and reproducibly. This paper reports a study of the sheet resistance of silicon resistors implanted with 1z ~Sb at 10keV, for various doses and annealing conditions. The methods used in fabricating samples and taking measurements were described in an earlier paper. For high doses, ~ 1015 Sb/cm 2, we found that two-stage annealing preannealing at 550°C followed by annealing at 1000°C improves the electrical conductivity. For low doses, 10t2Sb/cm 2, the final annealing determines the conductivity. For medium doses, ~ 1013 1014 Sb/cm 2, the interplay of damage-annealing and activation of Sb in Si introduces complications, giving a crossover of sheet resistance vs implant dose for various annealing temperatures. For doses around 3 × I013cm -2, the resistances are very insensitive to the details of annealing sequence and temperature; also the TCR is very low, about 50ppm/°C. The effect of annealing conditions for various doses, resistivities and TCR values are discussed.
The adherence of chromium and titanium films deposited on alumina, quartz, and glass--testing and improvement of electron-beam-deposition techniques. MARTIN CAULXON, WILLIAM L. SKED and FRANCIS S. WOZN1AK. RCA Rev. 40, ll5 (June 1979). The adherence of standard electron-beam (EB) evaporated chromium-copper metallization on alumina substrates was found to be marginal, especially when the metallization patterns are both narrow ( < 10 mils) and thick ( > 7/lm). The adherences of chromium and titanium films were therefore measured under different evaporation conditions on alumina, quartz, and glass. In the tests the seed metal is plated with 2 or more mils of copper, and the force per unit width necessary to pull the chromium-metal film off the substrate is measured. It was found that although titanium, resistance-filament chromium, and sputtered chromium-rich films had a good adherence, it is necessary for EB evaporated chromium on alumina and quartz to add oxygen in a definite pressure range to produce a superior adhesion. The details of the testing technique and the peel strengths of chromium on alumina, quartz and glass under different deposition conditions are described. The addition of oxygen during the initial EB chromium evaporation produces an adhesion that is as strong as the materials used.
Application of the ZBA-IO electron-beam exposure system in the production of precision photomasks with pattern element dimensions in the submicron range. S. A. INOZEMTSEV,A. S. KORABL1N, V. M. SUTYRIN and P. HAHMANN. Jena Rev. 2/1979, 62. For the first time the principle of a shaped beam (rectangularly-shaped intensity distribution of the electron probe) with electron-optical variation possibilities has been implemented. Within the scope of tests, essential performance parameters which are of importance to the designer and refer to the shaped-beam principle, were experimentally determined, partly with the aid of suitable test patterns.
Monemolecular resists: a new class of high resolution resists for electron beam micmlithography. A. BARRAUD,C. ROSILIO and A. RUAUDEL-TEIXIER.Solid St. Technol. p. 120 (August 1979). A new class of ulthrathin (30 to 1000 A) electron-resists based on monomolecular layers is described. These negative resists make it possible, with a proper choice of the accelerating voltage, to achieve a very high resolution, even on thick substrates. The thickness-voltage combination is shown to be the main parameter, contrast being second order. These properties are illustrated by the example of c~-tricosenoic acid, which provides a resolution of 600 A when 450/~ thick, despite a contrast value of 0.7.
Response of diazoquinone resists to optical and electronbeam exposure. MICHAEL KAPLAN and DIETRICH MEYERHOFER. R C A Rev. 40, 166 (June 1979). The responses of diazoquinone/novolak resist systems to optical and electron-beam radiation are compared. The "intrinsic" sensitivity to radiation is determined by measuring the rate of destruction of the diazoquinone sensitizer with radiation. Under optical exposure, a quantum efficiency of 0.30 + 0.03 is measured for two different sensitizers and various resist formulations. This quantity is constant over the wavelength region of 350-450nm where only the photoactive site absorbs. Under electron irradiation, we measure G-values (number of molecules destroyed per 100eV of energy absorbed) of 7 8 for undiluted sensitizer films. The optical quantum efficiency and th'~"G-value can be compared in terms of the energy required to destroy one sensitizer site. This energy is 12.5eV for electron beam exposure and 10.5 for optical exposure. In resist films, the result depends on how the absorbed energy is partitioned between the sensitizer and the resin. If it is assumed that the energy is absorbed equally in both parts, then the G-value can be as much as a factor of 2 higher in the resist than in the sensitizer. These resist systems are positive-working for both optical exposure and electron irradiation at low doses. The solubility of the films changes more rapidly with energy absorbed for electron irradiation than for optical irradiation, if only the energy absorbed by the sensitizer is taken into account. The reverse is true if all the energy is included. Practical exposure values required for lithographic applications are 3-4 mJ/cm 2 optical dose and 7-20pC/cm 2 electron dose at 10kV.
Annealing of ion implanted layers by laser beam. JANUSZ KRYNICKI. Electron Technol. 12, (1) 77. The paper discusses the applicability of laser beam for annealing of implanted layers and presents the results of electrical, optical and backscattering investigations of laser-annealed implanted layers. The effects of impurity-profile broadening during laser action are reviewed. The results of laser and thermal annealing are compared.
Ar-ion implant damage gettering of generation impurities in silicon employing voltage ramping and nitrogen backscattering. B. GOLJA and A. G. NASSIBIAN. Solid-St. electron Devices 3, (5) 127 (September 1979). The effects of At-ion implant gettering has been investigated using the linear voltage ramp applied to m.o.s, capacitors. A comparison is made with control (not implanted) samples and N+-ion Rutherford backscattering is used to examine the precipitation of generation impurities by the damaged layers.
391
The gettering anneals were carried out over the temperature range 950°C-1100°C and for various times from 15 min to 120 min. It is shown that long gettering anneal times and high anneal temperatures both have a detrimental effect on minority-carrier lifetime.
Some annealing properties of low-energy-antimony-implanted silicon resistors. S. M. K u and W. K. CHU. Solid-St. Electron. 22, 719 (1979). Shallow-implanted antimony in silicon can be used in fabricating n-type silicon resistors with very low temperature coefficient of resistance (TCR), controllably and reproducibly. This paper reports a study of the sheet resistance of silicon resistors implanted with 1z ~Sb at 10keV, for various doses and annealing conditions. The methods used in fabricating samples and taking measurements were described in an earlier paper. For high doses, ~ 1015 Sb/cm 2, we found that two-stage annealing preannealing at 550°C followed by annealing at 1000°C improves the electrical conductivity. For low doses, 10t2Sb/cm 2, the final annealing determines the conductivity. For medium doses, ~ 1013 1014 Sb/cm 2, the interplay of damage-annealing and activation of Sb in Si introduces complications, giving a crossover of sheet resistance vs implant dose for various annealing temperatures. For doses around 3 × I013cm -2, the resistances are very insensitive to the details of annealing sequence and temperature; also the TCR is very low, about 50ppm/°C. The effect of annealing conditions for various doses, resistivities and TCR values are discussed.
The adherence of chromium and titanium films deposited on alumina, quartz, and glass--testing and improvement of electron-beam-deposition techniques. MARTIN CAULXON, WILLIAM L. SKED and FRANCIS S. WOZN1AK. RCA Rev. 40, ll5 (June 1979). The adherence of standard electron-beam (EB) evaporated chromium-copper metallization on alumina substrates was found to be marginal, especially when the metallization patterns are both narrow ( < 10 mils) and thick ( > 7/lm). The adherences of chromium and titanium films were therefore measured under different evaporation conditions on alumina, quartz, and glass. In the tests the seed metal is plated with 2 or more mils of copper, and the force per unit width necessary to pull the chromium-metal film off the substrate is measured. It was found that although titanium, resistance-filament chromium, and sputtered chromium-rich films had a good adherence, it is necessary for EB evaporated chromium on alumina and quartz to add oxygen in a definite pressure range to produce a superior adhesion. The details of the testing technique and the peel strengths of chromium on alumina, quartz and glass under different deposition conditions are described. The addition of oxygen during the initial EB chromium evaporation produces an adhesion that is as strong as the materials used.
Application of the ZBA-IO electron-beam exposure system in the production of precision photomasks with pattern element dimensions in the submicron range. S. A. INOZEMTSEV,A. S. KORABL1N, V. M. SUTYRIN and P. HAHMANN. Jena Rev. 2/1979, 62. For the first time the principle of a shaped beam (rectangularly-shaped intensity distribution of the electron probe) with electron-optical variation possibilities has been implemented. Within the scope of tests, essential performance parameters which are of importance to the designer and refer to the shaped-beam principle, were experimentally determined, partly with the aid of suitable test patterns.