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Light ion mass spectrometer for the space-plasma investigations
Classified
abstracts
5513-5523
mate in cumulative ozone that increases almost linearly with pressure and
is only weakly dependent on the solar zenith angle. For most practical operating conditions, however, the error in cumulative ozone arising from the scattered flux is of the order of 1% or less. R W L Thomas et al, Appl Optics, 21 (13), 1982, 2436-2441. 34 5513. Light Ion Mea Spectrometer for space-plasma ioveatigatioos. (USA)
Recent studies of the low-energy plasma population in the Earth’s space environment have revealed that this plasma population is much more complex than previously supposed and that a simple model of ionospheric evaporation cannot explain the distributions. There was a need to develop an advanced instrument to study this plasma in detail, and this paper describes the scientific background, design, development and in-flight characteristics of such an instrument, the Light Ion Mass Spectrometer (LIMS). This instrument combines a magnetic mass spectrometer, a planar-grid retarding potential analyser and multidirectional sensor heads to measure the mass composition, density, temperature and flow velocity of low-energy (E < 100 eV) plasma. The studies which were conducted leading to the final design will be discussed in detail and will illustrate certain effects which arose in the combining ofenergyand mass analysis into a single sensor. The instrument was flown on a high-altitude satellite in February 1979 and selected flight data will be presented to demonstrate the instrument performance. David L Reasoner et al, Reu Sci Instrum, 53 (4), 1982, 441-448. 35. PROCESSING
OF MATERIALS
35 5514. Annealing of implnatatioa damage in iategratedcircnit devices using an incoherent light source. (USA) A stationary large-diameter incoherent light beam has been used to anneal ion-implantation damage (‘WAS:185 keV, 1 x lOI cme2) in an array of n+-p junction diodes fabricated on 3 in. Si (100) wafers. The best diodes produced in this way had device characteristics comparable to those of furnace-annealed diodes (-0.5; 1 nA cm-* leakage current at 5 V reverse bias). The variation of reverse leakage current across a 3 in. wafer (-0.5-20 nA cm-*) was much greater than for furnace-annealed diodes and may be caused by nonuniformities in the incoherent light beam. Tests on MOS capacitors showed that when incoherent light annealing was performed with the sample in moderate vacuum (5 lo-* torr), damage introduced at the SiSiOZ interface was negligible. R A Powell et PI, J Vuc Sci Technol, 28 (l), 1982, 33-36. 35 5515. Uniqw semiconductor materials and strwtores produced by laser nod electron beams. (USA)
High intensity laser and electron beams can be used to melt thin semiconductor surface layers and produce unique materials and structures. In the pulsed beam regime, materials with supersaturated substitutional and electrically active impurity concentrations are commonly produced in thin layers below the surface. In using a scanned continuouswave beam, thin film crystalline material has been grown on noncrystalline substrates. W L Brown, J Vat Sci Technol, 28 (3). 1982, 734-737. 35 5516. Atomic mixing in the depth-dependent diffusion approximation (USA)
The atomic mixing of a layer of implant atoms in a solid by subsequent irradiation has been discussed in a number of recent theoretical papers. The most general formalism is that resulting in an integro-differential equation for the implant concentration n(x, 4) at depth x after irradiation of total ion flux I#J.The general solution of this equation presents severe difficulties and various approximations have been adopted. One of the most useful has been the diffusion approximation’ in which a form of diffusion equation for n is obtained. In this equation the net implant displacement rate is represented by a (depth-dependent) drift velocity v, while the broadening of the implant profile is represented by a (depthdependent) diffusion coefficient D. Contributions to both o and D arise from both ion-implant recoils and matrix-implant cascade collisions. Although there isgeneral agreement on the method ofcalculation ofboth I! and D, different forms of the diffusion equation have resulted from differing approximations. The purpose of the present note is to show that the particular form suggested by one of the present authors on the basis of an indirect argument is in fact the closest diffusion approximation to the integrodifferential equation of the more general location theory. R Collins and J J Jimenez-Rodriguez, Rad Eficfs Lerrers. 68, 1982.19-23. 352
35 5517. ImpIaot profile eompntation with depthdependent diffnsion. (USA) In a recent communication, a derivation was given of the diffusion equation which gives the closest approximation to the more general relocation theory used by Sigmund Gras-Marti, Jimenez-Rodriguez and others. In the present note we give the results of some numerical computations, based on the foregoing theory. We calculate successive implantation profiles of an initially thin uniform layer of platinum in a silicon matrix, when subjected to subsequent irradiation by 300 keV Xe ions. The effects of sputtering are subsumed into a constant surface recession velocity. (GB) T Marsh et al, Rad E’cts Letters, 68, 1982, 1-5. 35 SSlI3. RITA, a promising Monte Carlo code for recoil implantation. (USA) A computer code previously set up to simulate ion penetration in amorphous solids has been extended to handle with recoil phenomena. Preliminary results are. compared with existing experimental data (Italy) A Deaalvo and R Rosa, Rad Effects Letters, 67 (4), 1982, 119-123. 35 5519.100 bombardment-induced s&surface composition modifications in alloys at elevated temperatures (USA) Modifications of subsurface ahoy composition during high-temperature sputtering were studied using a comprehensive kinetic model that includes Gibbsian adsorption, preferential sputtering, displacement mixing, radiation-enhanced diffusion and radiation-induced segregation. Numerical solutions were obtained for a Cu-40 atm% Ni alloy under 5-keV Ar+ ion bombardment as functions of time and temperature. The model predictions are in good qualitative agreement with recent experimental measurements. NghI Q Lam and H Wiiersich, Rod E@cts Letters, 67 (4). 1982,107-l 12. 35 SSU). Pulsed eleetroa beam for silicon antwaling. (GB) The characteristics of an electron beam generator are given. It produces pulses up to 50 kV, currents up to 20 kA, with a pulse length of about 50 ns. It was designed and built for annealing of thin metal layers deposited on single crystal silicon wafers. (Italy) G Leggieri et al, Vacuum, 32 (1) 1982,9-10. 35 5521. Electron beam induced reactions in metal/Si systems. (GB) Thin Pt. Pd, PtzSi. PtSi, Pd,Si, Ni, MO, W, Nb, Ti, V films deposited on Si single crystal were treated by using electron beam pulses of 60 ns duration in the 0.4-4 J cm-’ energy density range. Irradiation of these structures products at the same time many phases. Post-thermal annealing of the reacted layer induces the formation of a stable phase, the same obtained by only thermal treatment in a conventional furnace. A linear relationship between the energy density range and the lowest eutectic temperature of the compounds formed has been found. Further SEM observations seem to identify a liquid layer from which the phases are forming by subsequent fast cooling. (Italy) G Majni et al, Vacuum, 32 (1). 1982, 11-18. 35 5522. Effect of pressore, ageing and in situ annealing on the electrical properties of thin samarium films. (GB) We report on the e&t of pressure, ageing and in situ annealing on the electrical resistivity and temperature coefficient of resistance in thin samarium films over the thickness range 100800 A. On annealing at 180°C for 2 h, film resistivity increases for lower thicknesses but remains constant for higher thicknesses. For films grown at higher pressures the resistivity decreases at lower thicknesses (< 500 A). (India) P V Asbrit and M A Angadi, Vacuum, 32 (2), 1982,99-101. 35 5523. Polysilicon etcbiog and profile control in a CCI,-0, plasma. (USA) The etch selectivity in a CCI,GZ discharge of undoped polysilicon over Si02 is found to increase as a function of oxygen concentration in the CCI,-G2 gas feed. Selectivities of 4: 1, 15: 1 and 24: 1 are found at 0, concentrations of 0,25 and 50%, respectively. Correlation of these results with observed trends in the intensities of emission bands at 465.5 nm (Cl:), 288.3 nm (CO;) and 278.8 nm (Ccl) reflect on the differences between polysihcon and SiO, etching in fluorine and chlorine based discharges. A model for profiling an etched polysilicon line based upon the controlled erosion of photoresist is presented and shows the resultant profile to be a function of the initial photoresist profile and the polysiliconto-photoresist etch selectivity. This selectivity is shown to be variable over the range from 2: 1 to 1: 10. C S Korman, J Vat Sci Technol. 20 (3). 1982, 476479.
abstracts
5513-5523
mate in cumulative ozone that increases almost linearly with pressure and
is only weakly dependent on the solar zenith angle. For most practical operating conditions, however, the error in cumulative ozone arising from the scattered flux is of the order of 1% or less. R W L Thomas et al, Appl Optics, 21 (13), 1982, 2436-2441. 34 5513. Light Ion Mea Spectrometer for space-plasma ioveatigatioos. (USA)
Recent studies of the low-energy plasma population in the Earth’s space environment have revealed that this plasma population is much more complex than previously supposed and that a simple model of ionospheric evaporation cannot explain the distributions. There was a need to develop an advanced instrument to study this plasma in detail, and this paper describes the scientific background, design, development and in-flight characteristics of such an instrument, the Light Ion Mass Spectrometer (LIMS). This instrument combines a magnetic mass spectrometer, a planar-grid retarding potential analyser and multidirectional sensor heads to measure the mass composition, density, temperature and flow velocity of low-energy (E < 100 eV) plasma. The studies which were conducted leading to the final design will be discussed in detail and will illustrate certain effects which arose in the combining ofenergyand mass analysis into a single sensor. The instrument was flown on a high-altitude satellite in February 1979 and selected flight data will be presented to demonstrate the instrument performance. David L Reasoner et al, Reu Sci Instrum, 53 (4), 1982, 441-448. 35. PROCESSING
OF MATERIALS
35 5514. Annealing of implnatatioa damage in iategratedcircnit devices using an incoherent light source. (USA) A stationary large-diameter incoherent light beam has been used to anneal ion-implantation damage (‘WAS:185 keV, 1 x lOI cme2) in an array of n+-p junction diodes fabricated on 3 in. Si (100) wafers. The best diodes produced in this way had device characteristics comparable to those of furnace-annealed diodes (-0.5; 1 nA cm-* leakage current at 5 V reverse bias). The variation of reverse leakage current across a 3 in. wafer (-0.5-20 nA cm-*) was much greater than for furnace-annealed diodes and may be caused by nonuniformities in the incoherent light beam. Tests on MOS capacitors showed that when incoherent light annealing was performed with the sample in moderate vacuum (5 lo-* torr), damage introduced at the SiSiOZ interface was negligible. R A Powell et PI, J Vuc Sci Technol, 28 (l), 1982, 33-36. 35 5515. Uniqw semiconductor materials and strwtores produced by laser nod electron beams. (USA)
High intensity laser and electron beams can be used to melt thin semiconductor surface layers and produce unique materials and structures. In the pulsed beam regime, materials with supersaturated substitutional and electrically active impurity concentrations are commonly produced in thin layers below the surface. In using a scanned continuouswave beam, thin film crystalline material has been grown on noncrystalline substrates. W L Brown, J Vat Sci Technol, 28 (3). 1982, 734-737. 35 5516. Atomic mixing in the depth-dependent diffusion approximation (USA)
The atomic mixing of a layer of implant atoms in a solid by subsequent irradiation has been discussed in a number of recent theoretical papers. The most general formalism is that resulting in an integro-differential equation for the implant concentration n(x, 4) at depth x after irradiation of total ion flux I#J.The general solution of this equation presents severe difficulties and various approximations have been adopted. One of the most useful has been the diffusion approximation’ in which a form of diffusion equation for n is obtained. In this equation the net implant displacement rate is represented by a (depth-dependent) drift velocity v, while the broadening of the implant profile is represented by a (depthdependent) diffusion coefficient D. Contributions to both o and D arise from both ion-implant recoils and matrix-implant cascade collisions. Although there isgeneral agreement on the method ofcalculation ofboth I! and D, different forms of the diffusion equation have resulted from differing approximations. The purpose of the present note is to show that the particular form suggested by one of the present authors on the basis of an indirect argument is in fact the closest diffusion approximation to the integrodifferential equation of the more general location theory. R Collins and J J Jimenez-Rodriguez, Rad Eficfs Lerrers. 68, 1982.19-23. 352
35 5517. ImpIaot profile eompntation with depthdependent diffnsion. (USA) In a recent communication, a derivation was given of the diffusion equation which gives the closest approximation to the more general relocation theory used by Sigmund Gras-Marti, Jimenez-Rodriguez and others. In the present note we give the results of some numerical computations, based on the foregoing theory. We calculate successive implantation profiles of an initially thin uniform layer of platinum in a silicon matrix, when subjected to subsequent irradiation by 300 keV Xe ions. The effects of sputtering are subsumed into a constant surface recession velocity. (GB) T Marsh et al, Rad E’cts Letters, 68, 1982, 1-5. 35 SSlI3. RITA, a promising Monte Carlo code for recoil implantation. (USA) A computer code previously set up to simulate ion penetration in amorphous solids has been extended to handle with recoil phenomena. Preliminary results are. compared with existing experimental data (Italy) A Deaalvo and R Rosa, Rad Effects Letters, 67 (4), 1982, 119-123. 35 5519.100 bombardment-induced s&surface composition modifications in alloys at elevated temperatures (USA) Modifications of subsurface ahoy composition during high-temperature sputtering were studied using a comprehensive kinetic model that includes Gibbsian adsorption, preferential sputtering, displacement mixing, radiation-enhanced diffusion and radiation-induced segregation. Numerical solutions were obtained for a Cu-40 atm% Ni alloy under 5-keV Ar+ ion bombardment as functions of time and temperature. The model predictions are in good qualitative agreement with recent experimental measurements. NghI Q Lam and H Wiiersich, Rod E@cts Letters, 67 (4). 1982,107-l 12. 35 SSU). Pulsed eleetroa beam for silicon antwaling. (GB) The characteristics of an electron beam generator are given. It produces pulses up to 50 kV, currents up to 20 kA, with a pulse length of about 50 ns. It was designed and built for annealing of thin metal layers deposited on single crystal silicon wafers. (Italy) G Leggieri et al, Vacuum, 32 (1) 1982,9-10. 35 5521. Electron beam induced reactions in metal/Si systems. (GB) Thin Pt. Pd, PtzSi. PtSi, Pd,Si, Ni, MO, W, Nb, Ti, V films deposited on Si single crystal were treated by using electron beam pulses of 60 ns duration in the 0.4-4 J cm-’ energy density range. Irradiation of these structures products at the same time many phases. Post-thermal annealing of the reacted layer induces the formation of a stable phase, the same obtained by only thermal treatment in a conventional furnace. A linear relationship between the energy density range and the lowest eutectic temperature of the compounds formed has been found. Further SEM observations seem to identify a liquid layer from which the phases are forming by subsequent fast cooling. (Italy) G Majni et al, Vacuum, 32 (1). 1982, 11-18. 35 5522. Effect of pressore, ageing and in situ annealing on the electrical properties of thin samarium films. (GB) We report on the e&t of pressure, ageing and in situ annealing on the electrical resistivity and temperature coefficient of resistance in thin samarium films over the thickness range 100800 A. On annealing at 180°C for 2 h, film resistivity increases for lower thicknesses but remains constant for higher thicknesses. For films grown at higher pressures the resistivity decreases at lower thicknesses (< 500 A). (India) P V Asbrit and M A Angadi, Vacuum, 32 (2), 1982,99-101. 35 5523. Polysilicon etcbiog and profile control in a CCI,-0, plasma. (USA) The etch selectivity in a CCI,GZ discharge of undoped polysilicon over Si02 is found to increase as a function of oxygen concentration in the CCI,-G2 gas feed. Selectivities of 4: 1, 15: 1 and 24: 1 are found at 0, concentrations of 0,25 and 50%, respectively. Correlation of these results with observed trends in the intensities of emission bands at 465.5 nm (Cl:), 288.3 nm (CO;) and 278.8 nm (Ccl) reflect on the differences between polysihcon and SiO, etching in fluorine and chlorine based discharges. A model for profiling an etched polysilicon line based upon the controlled erosion of photoresist is presented and shows the resultant profile to be a function of the initial photoresist profile and the polysiliconto-photoresist etch selectivity. This selectivity is shown to be variable over the range from 2: 1 to 1: 10. C S Korman, J Vat Sci Technol. 20 (3). 1982, 476479.