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Tunnel injection into gate oxide traps
World Abstracts on Microeleetronics and Reliability saturation is well evidenced only at 300 K with the field oriented along the (111) axis. The data are interpreted with theoretical Monte Carlo calculations. The model includes non-parabolicity of the band, and a nonparabolicity parameter a = 0 . 5 eV -1 is suggested by the comparison of theoretical and experimental results.
Low frequency conductance and capacitance measurements on MOS capacitors in weak inversion. N. K. SAKS. Solid State Electron. 18, 737 (1975). The analysis of capacitance and conductance measurements as a function of frequency on MOS capacitors biased in depletion is well understood. However, little information is available on such measurements for capacitors biased in weak inversion. In this work it is shown that approximations to the theory of surface state response lead to a very simple technique for obtaining the density of fast surface states as a function of energy in the weak inversion region. Low frequency conductance and capacitance measurements have been made on a number of MOS samples and analysis of the data yields Ns~ as a function of energy in excellent agreement with results obtained by other techniques. As expected, experimental results show that N~s in weak inversion depends strongly on the annealing treatment given the MOS samples. However, annealing is found to have a much greater effect in reducing N.~ in weak inversion than at midgap. It is also shown that the depletion layer generation current in the majority of samples measured is due to surface state generation rather than bulk generation. Tunnel injection into gate oxide traps. J. MASERJIAN, R. KAW and J. COLLIER. 13th Ann. Proc. Reliability Physics Syrup. Nevada, p. 26, 1975. An experimental method is described for measuring the density of oxide traps in the gate oxide of an MOS transistor as a function of energy and position near the silicon interface. Measurements are obtained from different oxide growth processes and after Co 6° irradiation. The results are related to long-term drift of threshold voltage. 8. T H I C K -
AND
THIN-FILM AND
SOS island edge profiles following oxidation. S. N. LEE and R. A. KJAR. 13th Ann. Proc. Reliability Physics Symp. Nevada, p. 34, 1975. A study of silicon and oxide profiles at the edges of silicon islands etched in silicon-onsapphire (SOS) has shown that, following thermal oxidation of the silicon, a "V"-shaped groove forms "between the silicon dioxide grown on the island edge and the sapphire substrate. This groove can cause etching and metal coverage anomalies at the island edges resulting in poor circuit yield and reliability. Model band structure of reconstructed (111) 2 × 1 surtace of silicon. A. SELLONI and E. TOSATTI. Solid State Cornmun. 17, 387 (1975). We have computed the electronic band structure for a model of the 2× 1-reconstructed (111) surface of Si, based on 2 two-dimensional net of dangling bonds. A pairing of surface atoms is assumed, involving a displacement and a tilting of the dangling bonds towards each other. The energy gap that separates the two bands of surface states obtained increases with the degree of reconstruction, which is taken as a parameter. Experimental data, particularly surface optical absorption, find a satisfactory explanation in terms of this calculation, which indicates in Si (111) 2× 1 a shift of the surface atoms by about 8% of their ideal distance. Surface quantum oscillations in (110) and (111) n-type silicon inversion layers. T. NEUGEBAUER,K. yon KLITZING and G. LANDWEHR. Solid State Commun. 17, 295 (1975). Shubnikov-de Haas oscillations have been studied for (110) and (111) n-type silicon inversion layers. The measured cyclotron masses mc =(0.38±0.03)mo and mc = (0"40±0.03)mo for (110) and (111) planes, respectively, are larger than theoretically predicted values. The experimental valley degeneracy factor g ~ = 2 ± 0 . 2 for both orientations is also at variance with self consistent calculations. The electronic g-factor depends on the surface carrier concentration and is enhanced over its bulk value. There was no evidence for the occupation of other subbands.
COMPONENTS, MATERIALS
Packages and film resistors for hybrid microcircuits. C. H. LANE. 13th Ann. Proc. Reliability Physics Syrup. Nevada, p. 230, 1975. A review of resistor systems, and the processes used to deposit and delineate them, is given. Effects of mechanical, thermal, chemical and electrical stresses are discussed as they relate to accuracy and stability. Failure mecyanisms are reviewed. Trimming techniques are explored and design limits for the various systems discussed. Parameters of interest such as frequency response, temperature coefficient, voltage coefficient and noise are compared for the various systems. Finally, quality control and screening techniques are discussed as they relate failure mechanisms and package quality and reliability control. Hybrid technology loose particles and coating materials. C. MURPHY. 13th Ann. Proc. Reliability Physics Syrup. Nevada, p. 248, 1975. Any discussion concerning particles in hybrids usually comes soon to the question of whether or not particles are really a problem. Conversations with a wide spectrum of hybrid users has led to the conclusion that problems associated with particles are a function of the sensitivity each user perceives to exist for his particular application and program requirements. It is interesting to note however, that almost all users state that even limited tests indicate that a percentage of all hybrids seems to exhibit the presence of particles. Previous studies of particle behavior clearly indicate that if
413
HYBRID
CIRCUITS
particles occur, they can easily become mobile within the enclosure of microelectronic packages? The question that each hybrid user must answer for his particular application and environment is, "Am I really concerned that there will be particles in some of my hybrids?" If the answer is "no," the designer may happily concern himself with other quality aspects of his system; if the answer is "yes," the designer finds himself in the growing ranks of persons trying to do something about particles.
Hybrid packages by the direct bonded copper process. J. F. BURGESS, C. A. NEUGEBAUER, G. FLANAGAN and R. E. MOORE. Solid State Techn. May 1975, p. 42. The direct bonding of metals to ceramics is possible utilizing a gas phase eutectic. The mechanism of direct bonding of copper foil to ceramics such as AI203 in a slightly oxidising atmosphere is presented. It involves the formation of a eutectic melt, involving copper and oxygen, at a temperature slightly below the melting point of copper, which serves to bring the foil into intimate contact with the substrate. Properties of the bond, application to other metal-gas systems, and the types of ceramics are discussed. The use of the direct bonding process in a number of electronic applications such as hybrid packages and power device heat sinks is reviewed. Materials control for the manulacture of thin-film hybrid circuits. W. CLASS and G. T. MURRAY. Solid State Techn.
Low frequency conductance and capacitance measurements on MOS capacitors in weak inversion. N. K. SAKS. Solid State Electron. 18, 737 (1975). The analysis of capacitance and conductance measurements as a function of frequency on MOS capacitors biased in depletion is well understood. However, little information is available on such measurements for capacitors biased in weak inversion. In this work it is shown that approximations to the theory of surface state response lead to a very simple technique for obtaining the density of fast surface states as a function of energy in the weak inversion region. Low frequency conductance and capacitance measurements have been made on a number of MOS samples and analysis of the data yields Ns~ as a function of energy in excellent agreement with results obtained by other techniques. As expected, experimental results show that N~s in weak inversion depends strongly on the annealing treatment given the MOS samples. However, annealing is found to have a much greater effect in reducing N.~ in weak inversion than at midgap. It is also shown that the depletion layer generation current in the majority of samples measured is due to surface state generation rather than bulk generation. Tunnel injection into gate oxide traps. J. MASERJIAN, R. KAW and J. COLLIER. 13th Ann. Proc. Reliability Physics Syrup. Nevada, p. 26, 1975. An experimental method is described for measuring the density of oxide traps in the gate oxide of an MOS transistor as a function of energy and position near the silicon interface. Measurements are obtained from different oxide growth processes and after Co 6° irradiation. The results are related to long-term drift of threshold voltage. 8. T H I C K -
AND
THIN-FILM AND
SOS island edge profiles following oxidation. S. N. LEE and R. A. KJAR. 13th Ann. Proc. Reliability Physics Symp. Nevada, p. 34, 1975. A study of silicon and oxide profiles at the edges of silicon islands etched in silicon-onsapphire (SOS) has shown that, following thermal oxidation of the silicon, a "V"-shaped groove forms "between the silicon dioxide grown on the island edge and the sapphire substrate. This groove can cause etching and metal coverage anomalies at the island edges resulting in poor circuit yield and reliability. Model band structure of reconstructed (111) 2 × 1 surtace of silicon. A. SELLONI and E. TOSATTI. Solid State Cornmun. 17, 387 (1975). We have computed the electronic band structure for a model of the 2× 1-reconstructed (111) surface of Si, based on 2 two-dimensional net of dangling bonds. A pairing of surface atoms is assumed, involving a displacement and a tilting of the dangling bonds towards each other. The energy gap that separates the two bands of surface states obtained increases with the degree of reconstruction, which is taken as a parameter. Experimental data, particularly surface optical absorption, find a satisfactory explanation in terms of this calculation, which indicates in Si (111) 2× 1 a shift of the surface atoms by about 8% of their ideal distance. Surface quantum oscillations in (110) and (111) n-type silicon inversion layers. T. NEUGEBAUER,K. yon KLITZING and G. LANDWEHR. Solid State Commun. 17, 295 (1975). Shubnikov-de Haas oscillations have been studied for (110) and (111) n-type silicon inversion layers. The measured cyclotron masses mc =(0.38±0.03)mo and mc = (0"40±0.03)mo for (110) and (111) planes, respectively, are larger than theoretically predicted values. The experimental valley degeneracy factor g ~ = 2 ± 0 . 2 for both orientations is also at variance with self consistent calculations. The electronic g-factor depends on the surface carrier concentration and is enhanced over its bulk value. There was no evidence for the occupation of other subbands.
COMPONENTS, MATERIALS
Packages and film resistors for hybrid microcircuits. C. H. LANE. 13th Ann. Proc. Reliability Physics Syrup. Nevada, p. 230, 1975. A review of resistor systems, and the processes used to deposit and delineate them, is given. Effects of mechanical, thermal, chemical and electrical stresses are discussed as they relate to accuracy and stability. Failure mecyanisms are reviewed. Trimming techniques are explored and design limits for the various systems discussed. Parameters of interest such as frequency response, temperature coefficient, voltage coefficient and noise are compared for the various systems. Finally, quality control and screening techniques are discussed as they relate failure mechanisms and package quality and reliability control. Hybrid technology loose particles and coating materials. C. MURPHY. 13th Ann. Proc. Reliability Physics Syrup. Nevada, p. 248, 1975. Any discussion concerning particles in hybrids usually comes soon to the question of whether or not particles are really a problem. Conversations with a wide spectrum of hybrid users has led to the conclusion that problems associated with particles are a function of the sensitivity each user perceives to exist for his particular application and program requirements. It is interesting to note however, that almost all users state that even limited tests indicate that a percentage of all hybrids seems to exhibit the presence of particles. Previous studies of particle behavior clearly indicate that if
413
HYBRID
CIRCUITS
particles occur, they can easily become mobile within the enclosure of microelectronic packages? The question that each hybrid user must answer for his particular application and environment is, "Am I really concerned that there will be particles in some of my hybrids?" If the answer is "no," the designer may happily concern himself with other quality aspects of his system; if the answer is "yes," the designer finds himself in the growing ranks of persons trying to do something about particles.
Hybrid packages by the direct bonded copper process. J. F. BURGESS, C. A. NEUGEBAUER, G. FLANAGAN and R. E. MOORE. Solid State Techn. May 1975, p. 42. The direct bonding of metals to ceramics is possible utilizing a gas phase eutectic. The mechanism of direct bonding of copper foil to ceramics such as AI203 in a slightly oxidising atmosphere is presented. It involves the formation of a eutectic melt, involving copper and oxygen, at a temperature slightly below the melting point of copper, which serves to bring the foil into intimate contact with the substrate. Properties of the bond, application to other metal-gas systems, and the types of ceramics are discussed. The use of the direct bonding process in a number of electronic applications such as hybrid packages and power device heat sinks is reviewed. Materials control for the manulacture of thin-film hybrid circuits. W. CLASS and G. T. MURRAY. Solid State Techn.