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Role of chlorine in silicon oxidation (Part 1)
structure and electronic transport properties P Diffusion data and the properties of thep-n junctions obtained are also discussed. Avalanche current distribution and reverse bias electric field spikes have been carefully studied. It is concluded that this material is quite suitable for low-cost solar cell applications.
gradient. When the voltage was increased it caused an abrupt change in the capacitance and isolation resistance. The migration was more pronounced on the surface of bare alumina substrates than on substrates covered with a dielectric layer. Finally, a Du Pont 9137 glass encapsulant was found to be effective in preventing silver migration under THB conditions while an ESL 240 SB encapsulant enhanced the rate of migration.
Temperature dependence of the Hall coefficient of thin films C. R. TELLIER, C. PICHARD and A. J. TOSSER Electrocomp Sci. Technol. 6, 19 (1979). A theoretical expression for the temperature coefficient flint of the Hall coefficient RHF of metallic films is deduced from the FuchsSondheimer conduction model. The general expression takes into account the deviation introduced by the geometrical limitation of the mean free path. This is negligible for relatively thick films (k > 1 for p = 0) and agrees with experiments previously reported by other authors.
Electron trapping in neutron-irradiated very thin films of Ah03. P. C. SRIVASTAVA, A. ROY B A R D H A N and D. L. B H A T F A C H A R Y A Int. J. Electron. 46,(6) 547 (1979). Oxide layers of thicknesses less than 100 A have been prepared by thermal-oxidation of a base metal electrode film of aluminium. These films were then neutron-irradiated from a laboratory Ra-Be source to a fluence o f ~ 1 0 n neutrons cm -2 and the sandwich structure A1-AIaOaAu, was completed by depositing a thin metal film of gold over the irradiated oxide layer. D. C. steady and transient flow through the sandwich structures have been studied. Results obtained in our experiments with irradiated sandwiches have been compared with unirradiated ones to show that traps are introduced because of the damage caused by the incident neutrons. Transient voltage measurement across the junction gives a trap density of ~ 1 0 -Is cm -a. A capture cross-section of the order 10-za cm z is estimated for the traps. It is found that the (identified) traps are uniformly distributed within an energy of 0.099eV below the conduction band edge of aluminium oxide. The physical nature of the traps is discussed by comparing the capture cross-sections of the physically known trapping centres. The possibility of vacancies or F-centres acting as traps (for the identified ones) has been suggested.
Role of chlorine in silicon oxidation (Part I) J MONKOWSKI Solid St. Technol. p. 58 (July 1979). The various roles played by the addition of chlorine-bearing compounds to the oxidation of silicon are discussed. The effects of electrical, chemical, and microstructural changes of the oxide are presented. The paper includes a review of some of the work of others to show the complex role that chlorine, present during oxidation, has on final device structure characteristics. Tunnels in semiconductor epitaxy J. C. M A R I N A C E IBMJ. Res. Dev. 23, (4)459 (July 1979). On (I00) surfaces of III = V or II-VI compounds, tunnels or grooves can be grown over oxide or Mo stripes, the axes of which are in one of the two orthogonal <110> directions on the surface. One <110> direction produces grooves and the other, tunnels. By switching from n- to p-type layers at frequent intervals during growth, the mechanism can be elucidated. An analysis of LPCVD system parameters for polysilicon, silicon nitride and silicon dioxide deposition WILLIAM A. BROWN and T H E O D O R E I. KAMINS SolidSt. Technol. p. 51 (July 1979). The formation by low-pressure CVD of polysilicon, silicon nitride, and silicon dioxide films for integrated circuits is discussed, and the deposition rates are shown to depend critically on the temperature profile, the system pressure, and the partial pressures of the reactant gases. The structure and resistance of polysilicon films are found to depend on the deposition temperature. Proper system operation requires careful attention to particle and reaction byproduct buildup and pump-oil degradation. A maintenance schedule is presented. Silver migration and the reliability of Pd/Ag conductors in thick-film dielectric crossover structures HUSSEIN M. N A G U I B and BLAIR K. MACLAURIN IEEE Trans. Components, Hybrids, Mfg Technol. Chmt-2, (2) 196 (June 1979). The relative performance characteristics of thick-film Pd/Ag conductors (0-34%Pd) for dielectric crossover structures in hybrid microeiectronic circuits are described. The materials were supplied from Du Pont and Engelhard. The experiments involved water-drop (WD) tests and temperature-humidity-bias (THB) tests at 90°C, 90%RH, and a d c bias of 5-50V applied between the conductor electrodes for periods up to 1000h. WD tests showed that the rate of Ag migration decreased by approximately 100 times as the Pd content in the conductor was increased from 10%-19%. However, the results of these tests were considerably scattered for electrodes of high Pd content. In addition, no conclusive results could be reached on the effect of the substrate of various encapsulants on the rate of migration. The rate of migration under THB conditions was considerably lower (10 -4 times) than that under the water-drop tests. Surface migration was found to be the dominant mode of failure in dielectric crossover structures. The rate of migration increased with the increasing voltage
Negative Hall effect of hot holes in silicon K. KAJITA Solid St. Commun. 31,573 (1979). Hot electron effects of low density holes in silicon were studied in the helium temperature with electric fields up to 5000V cm-L Hall current of electron polarity was observed in high electric fields at low magnetic fields. The phenomenon is ascribed to the re-entrant energy surface of holes in silicon. A high-stability RC circuit using high nitrogen doped tantalum O. J. DUFF, G E R A R D J. KOERCKEL, EDWARD H. MAYER and WALTER WOROBEY. IEEE Trans. Components, Hybrids, Mfg Technol. Chmt-2, (2) 221 (June 1979). A fabrication process and reliability studies for RC hybrid integrated circuits utilising alpha tantalum capacitors and tantalum nitride resistors are described. The alpha tantalum used in this study was reactively sputtered tantalum film containing from I0-20 atomic percent nitrogen and has a body centred cubic structure. The ae and de characterisitics of the alpha tantalum capacitors are in agreement with those shown by Anders and Rottersman. The long-term thermal stability of these capacitors is shown to be at least three times better than for beta tantalum capacitors. Accelerated life tests at various voltages show the alpha tantalum RC circuits to be at least equivalent in reliability to those using standard beta tantalum capacitors. The RC product shows excellent temperature compensation and stability during accelerated parametric aging tests which were done on production RC filter circuits. Electronic dielectric constant of III-V semiconductors J. K. S H A R M A and D. C. KHAN Solid St. Commun. 30, 111 (1979). It is shown that the anion dependence of the derivative of the d-core effect factor D and of the proportionality constant B, used in the Goyal-Sarkar semi-empirical power law relation between electronic dielectric constant and the interionic separation in III-V semiconductors, leads to serious theoretical inconsistencies. On the other hand, a careful use of Philips-Van Vechten formalism gives values of the strain derivatives of the electronic dielectric constants for GaP and G a A s which are in excellent agreement with experimental values, justifying anion-independent proportionality constant and d-core factor derivative. Finally, the values of the strain derivatives of the dielectric constants of a large number of III-V semiconductors are calculated. 39
gradient. When the voltage was increased it caused an abrupt change in the capacitance and isolation resistance. The migration was more pronounced on the surface of bare alumina substrates than on substrates covered with a dielectric layer. Finally, a Du Pont 9137 glass encapsulant was found to be effective in preventing silver migration under THB conditions while an ESL 240 SB encapsulant enhanced the rate of migration.
Temperature dependence of the Hall coefficient of thin films C. R. TELLIER, C. PICHARD and A. J. TOSSER Electrocomp Sci. Technol. 6, 19 (1979). A theoretical expression for the temperature coefficient flint of the Hall coefficient RHF of metallic films is deduced from the FuchsSondheimer conduction model. The general expression takes into account the deviation introduced by the geometrical limitation of the mean free path. This is negligible for relatively thick films (k > 1 for p = 0) and agrees with experiments previously reported by other authors.
Electron trapping in neutron-irradiated very thin films of Ah03. P. C. SRIVASTAVA, A. ROY B A R D H A N and D. L. B H A T F A C H A R Y A Int. J. Electron. 46,(6) 547 (1979). Oxide layers of thicknesses less than 100 A have been prepared by thermal-oxidation of a base metal electrode film of aluminium. These films were then neutron-irradiated from a laboratory Ra-Be source to a fluence o f ~ 1 0 n neutrons cm -2 and the sandwich structure A1-AIaOaAu, was completed by depositing a thin metal film of gold over the irradiated oxide layer. D. C. steady and transient flow through the sandwich structures have been studied. Results obtained in our experiments with irradiated sandwiches have been compared with unirradiated ones to show that traps are introduced because of the damage caused by the incident neutrons. Transient voltage measurement across the junction gives a trap density of ~ 1 0 -Is cm -a. A capture cross-section of the order 10-za cm z is estimated for the traps. It is found that the (identified) traps are uniformly distributed within an energy of 0.099eV below the conduction band edge of aluminium oxide. The physical nature of the traps is discussed by comparing the capture cross-sections of the physically known trapping centres. The possibility of vacancies or F-centres acting as traps (for the identified ones) has been suggested.
Role of chlorine in silicon oxidation (Part I) J MONKOWSKI Solid St. Technol. p. 58 (July 1979). The various roles played by the addition of chlorine-bearing compounds to the oxidation of silicon are discussed. The effects of electrical, chemical, and microstructural changes of the oxide are presented. The paper includes a review of some of the work of others to show the complex role that chlorine, present during oxidation, has on final device structure characteristics. Tunnels in semiconductor epitaxy J. C. M A R I N A C E IBMJ. Res. Dev. 23, (4)459 (July 1979). On (I00) surfaces of III = V or II-VI compounds, tunnels or grooves can be grown over oxide or Mo stripes, the axes of which are in one of the two orthogonal <110> directions on the surface. One <110> direction produces grooves and the other, tunnels. By switching from n- to p-type layers at frequent intervals during growth, the mechanism can be elucidated. An analysis of LPCVD system parameters for polysilicon, silicon nitride and silicon dioxide deposition WILLIAM A. BROWN and T H E O D O R E I. KAMINS SolidSt. Technol. p. 51 (July 1979). The formation by low-pressure CVD of polysilicon, silicon nitride, and silicon dioxide films for integrated circuits is discussed, and the deposition rates are shown to depend critically on the temperature profile, the system pressure, and the partial pressures of the reactant gases. The structure and resistance of polysilicon films are found to depend on the deposition temperature. Proper system operation requires careful attention to particle and reaction byproduct buildup and pump-oil degradation. A maintenance schedule is presented. Silver migration and the reliability of Pd/Ag conductors in thick-film dielectric crossover structures HUSSEIN M. N A G U I B and BLAIR K. MACLAURIN IEEE Trans. Components, Hybrids, Mfg Technol. Chmt-2, (2) 196 (June 1979). The relative performance characteristics of thick-film Pd/Ag conductors (0-34%Pd) for dielectric crossover structures in hybrid microeiectronic circuits are described. The materials were supplied from Du Pont and Engelhard. The experiments involved water-drop (WD) tests and temperature-humidity-bias (THB) tests at 90°C, 90%RH, and a d c bias of 5-50V applied between the conductor electrodes for periods up to 1000h. WD tests showed that the rate of Ag migration decreased by approximately 100 times as the Pd content in the conductor was increased from 10%-19%. However, the results of these tests were considerably scattered for electrodes of high Pd content. In addition, no conclusive results could be reached on the effect of the substrate of various encapsulants on the rate of migration. The rate of migration under THB conditions was considerably lower (10 -4 times) than that under the water-drop tests. Surface migration was found to be the dominant mode of failure in dielectric crossover structures. The rate of migration increased with the increasing voltage
Negative Hall effect of hot holes in silicon K. KAJITA Solid St. Commun. 31,573 (1979). Hot electron effects of low density holes in silicon were studied in the helium temperature with electric fields up to 5000V cm-L Hall current of electron polarity was observed in high electric fields at low magnetic fields. The phenomenon is ascribed to the re-entrant energy surface of holes in silicon. A high-stability RC circuit using high nitrogen doped tantalum O. J. DUFF, G E R A R D J. KOERCKEL, EDWARD H. MAYER and WALTER WOROBEY. IEEE Trans. Components, Hybrids, Mfg Technol. Chmt-2, (2) 221 (June 1979). A fabrication process and reliability studies for RC hybrid integrated circuits utilising alpha tantalum capacitors and tantalum nitride resistors are described. The alpha tantalum used in this study was reactively sputtered tantalum film containing from I0-20 atomic percent nitrogen and has a body centred cubic structure. The ae and de characterisitics of the alpha tantalum capacitors are in agreement with those shown by Anders and Rottersman. The long-term thermal stability of these capacitors is shown to be at least three times better than for beta tantalum capacitors. Accelerated life tests at various voltages show the alpha tantalum RC circuits to be at least equivalent in reliability to those using standard beta tantalum capacitors. The RC product shows excellent temperature compensation and stability during accelerated parametric aging tests which were done on production RC filter circuits. Electronic dielectric constant of III-V semiconductors J. K. S H A R M A and D. C. KHAN Solid St. Commun. 30, 111 (1979). It is shown that the anion dependence of the derivative of the d-core effect factor D and of the proportionality constant B, used in the Goyal-Sarkar semi-empirical power law relation between electronic dielectric constant and the interionic separation in III-V semiconductors, leads to serious theoretical inconsistencies. On the other hand, a careful use of Philips-Van Vechten formalism gives values of the strain derivatives of the electronic dielectric constants for GaP and G a A s which are in excellent agreement with experimental values, justifying anion-independent proportionality constant and d-core factor derivative. Finally, the values of the strain derivatives of the dielectric constants of a large number of III-V semiconductors are calculated. 39