- Email: [email protected]
Some properties of thin-film SOI MOSFETs
660
World Abstracts on Microelectronics and Reliability
lithic integrated circuit domain into the hybrid level, creating unique mechanical and thermal problems that exceed normal electrical concerns. The largest area consumer used in hybrid circuits is the filter capacitor chip. This chip, used for noise suppression by decoupling from the power supply lines, is usually of a fairly large value and is liberally dispersed throughout the circuit design as a conservative practice. An attempt to reach a higher level of integration would, therefore, require the removal of this surface-mounted component. Obviously, this must be accomplished without electrical compromise. The effect of the physical proximity of the capacitor on the integrated circuit element requiring it is discussed. Two methods of achieving this objective were explored and are described in the case history of a data-retrieval circuit that was constrained to fit in a small-volume hybrid configuration. In the initial phase of the investigation, capacitors were buried within the thick-film multilayer structure by introducing high K-value dielectric materials between large conductor areas serving as counterelectrodes. Connection to the appropriate monolithic integrated circuit wire bond/die pads was provided by standard blind-via techniques. Several dielectric materials were investigated; the experimental plan, processing, and electrical results are discussed as is an overall assessment of the parameters used for selecting the circuit fabrication material. In a subsequent phase of the investigation, a different approach was considered for use as buried capacitors to obtain comparative data and provide an alternative position during production. CAPSTRATE ®,a recently introduced substrate format containing integral capacitor elements, was tested as the base for a conventional thick-film multilayer structure. The initial results of this test are presented. Functional electrical testing of the resulting hybrid microcircuits was carried out to system requirement, and the performance data are presented. The results of a thermal analysis, conducted to ensure reliable operation, are also given. The hybrid packaging scheme that evolved from this effort yielded a component density of almost 100 components per square inch (including analog/linear monolithic integrated circuits and filter capacitors). The electrical characteristics of the data retrieval device were within the required specifications, and junction temperatures were were within reliability limits.
Delamination and fracture of thin films. ERIK KLOKHOLM. I B M J. Res. Dev. 31, 585 (1987). The fracture and delamination of thin films is a relatively common occurrence, and prevention of these mechanical failures is essential for the successful manufacture of thin-film devices. Internal elastic stresses are an inherent part of the thin-film deposition process, and are largely responsible for the mechanical failures of thin films. However, it is not the magnitude of the film stress S which governs film fracture or delamination, but the elastic energy U stored in the film. It is the intent of this presentation to show that the mechanical stability of the film and the substrate requires that U be less than a critical value Uc and that Uc is dependent upon the surface energy ~,. Some properties of thiwfiim SO1 MOSFETs. JEAN-PIERRE COLINGE. IEEE Circuits Devices Mao., 16 (November 1987). This paper describes the properties that can be expected from thin-film SOI-MOS transistors. Simple qualitative modeling shows that improvements of different parameters, such as subthreshold slope, hot-electron effects, and shortchannel effects, can be obtained when thin, fully depleted films are used.
Investigation of thick film technology for microwave applications. M. J. S~,~ms, K. D. STEPHAN,H. CAMPBELL,C. P. SMITHand R. M. ZILBERSTEIN.Microelectron. J. 18(5), 29 (1987). Recently, considerable interest has arisen in the use of thick film technology for microwave circuit applications. The
thick film process can be used to fabricate microwave circuits that perform just as well as thin film counterparts in the lower-frequency region below 1 GHz, but systematic efforts to explore the upper frequency limit of thick-film technology with practical microwave circuits have been lacking. We describe such an effort which involved testing four scaled versions of one microwave circuit design over an 18-toone frequency range. By using the same basic design and scaling the circuit physically to cover a given sub-range, variations in the circuit design were eliminated and any degradation in measured performance can be attributed to intrinsic process limitations. Results are presented for octave-bandwidth Wilkinson power dividers for the frequency ranges 1-2 GHz, 2-4 GHz, 4-8 GHz, and 9-18 GHz. We conclude that satisfactory microwave performance can be obtained routinely from thick-film circuits up to approximately 10GHz, and with special attention designs can be extended to perhaps 12-15 GHz. A simple inexpensive method for thickness measurement of thin films. E. SADER. Vacuum 38, 97 (1988). A simple and inexpensive method for monitoring the thickness of thermally evaporated thin films is reported. The technique relies on a simple oscillating quartz crystal using TTL. The operation of the monitor is illustrated for thin aluminium and copper films. Their thickness is determined, by this method, to an accuracy of a few percent, as the deviations of the mass densities between the bulk material and the films are very small.
A comparison of the reliability of copper and palladiumsilver thick-film crossovers. ROBERTR. SUTHERLANDand IAN D. E. VIDELO. IEEE Trans. Compon. Hybrids mfff Technol. CHMT-12, 676 (1987). The reliability of palladium-silver crossover systems under 85*C/85-percent relative humidity bias stress has been shown to depend primarily on the porosity of the dielectric. All of the low-porosity dielectrics tested gave consistently good reliability, which met the British Telecom Research Laboratories (BTRL) specification, while all of the high-porosity dielectrics showed considerable variation in reliability and often failed to meet the specification. This variation was only partly explained by constructional features such as the dielectric thickness or the use of an overglaze. The palladium content of the conductors was shown not to influence the reliability of the crossovers. The reliability of all of the copper crossover systems tested was relatively poor, and the best system tested barely met the BTRL specification, many of the remainder failing by a wide margin. Nitrogen-fireable resistors; emerging technology for thickfilm hybrids. PAUL C. DONOHUE, JACOB HORMADALY, CHRISTOPHER R. S. NEEDES, SAMUEL J. HOROWITZ and JOACHIM F. KNAAK. IEEE Trans. Compon. Hybrids mfff Technol. CHMT-12, 537 (1987). A nitrogen-fireable basemetal thick-film resistor system compatible with copper conductors has been developed. A lanthanum hexaboride conductive phase is used to make resistor compositions in the range 10f~/[[]-10kf2/[7, and doped tin oxide is used as the conductive in the 10kg2/[:]-1 Mf~/[:] resistance range. An extensive technology transfer program to move this technology from the research laboratory to full commercial availability is under way. The environmental stability of 44 lots made in pilot, prototype, and manufacturing scale runs have been evaluated and confirm lot-to-lot reproducibility. Lanthanum boride members show good environmental stability under all conditions. Doped tin oxide members are humidity sensitive and require encapsulation. When encapsulated with an organic material, all grades show maximum changes of less than one percent after 1000h of exposure to 85*C/85-percent relative humidity. The kinetics of thin film resistor stabilisation. 1. A.
World Abstracts on Microelectronics and Reliability
lithic integrated circuit domain into the hybrid level, creating unique mechanical and thermal problems that exceed normal electrical concerns. The largest area consumer used in hybrid circuits is the filter capacitor chip. This chip, used for noise suppression by decoupling from the power supply lines, is usually of a fairly large value and is liberally dispersed throughout the circuit design as a conservative practice. An attempt to reach a higher level of integration would, therefore, require the removal of this surface-mounted component. Obviously, this must be accomplished without electrical compromise. The effect of the physical proximity of the capacitor on the integrated circuit element requiring it is discussed. Two methods of achieving this objective were explored and are described in the case history of a data-retrieval circuit that was constrained to fit in a small-volume hybrid configuration. In the initial phase of the investigation, capacitors were buried within the thick-film multilayer structure by introducing high K-value dielectric materials between large conductor areas serving as counterelectrodes. Connection to the appropriate monolithic integrated circuit wire bond/die pads was provided by standard blind-via techniques. Several dielectric materials were investigated; the experimental plan, processing, and electrical results are discussed as is an overall assessment of the parameters used for selecting the circuit fabrication material. In a subsequent phase of the investigation, a different approach was considered for use as buried capacitors to obtain comparative data and provide an alternative position during production. CAPSTRATE ®,a recently introduced substrate format containing integral capacitor elements, was tested as the base for a conventional thick-film multilayer structure. The initial results of this test are presented. Functional electrical testing of the resulting hybrid microcircuits was carried out to system requirement, and the performance data are presented. The results of a thermal analysis, conducted to ensure reliable operation, are also given. The hybrid packaging scheme that evolved from this effort yielded a component density of almost 100 components per square inch (including analog/linear monolithic integrated circuits and filter capacitors). The electrical characteristics of the data retrieval device were within the required specifications, and junction temperatures were were within reliability limits.
Delamination and fracture of thin films. ERIK KLOKHOLM. I B M J. Res. Dev. 31, 585 (1987). The fracture and delamination of thin films is a relatively common occurrence, and prevention of these mechanical failures is essential for the successful manufacture of thin-film devices. Internal elastic stresses are an inherent part of the thin-film deposition process, and are largely responsible for the mechanical failures of thin films. However, it is not the magnitude of the film stress S which governs film fracture or delamination, but the elastic energy U stored in the film. It is the intent of this presentation to show that the mechanical stability of the film and the substrate requires that U be less than a critical value Uc and that Uc is dependent upon the surface energy ~,. Some properties of thiwfiim SO1 MOSFETs. JEAN-PIERRE COLINGE. IEEE Circuits Devices Mao., 16 (November 1987). This paper describes the properties that can be expected from thin-film SOI-MOS transistors. Simple qualitative modeling shows that improvements of different parameters, such as subthreshold slope, hot-electron effects, and shortchannel effects, can be obtained when thin, fully depleted films are used.
Investigation of thick film technology for microwave applications. M. J. S~,~ms, K. D. STEPHAN,H. CAMPBELL,C. P. SMITHand R. M. ZILBERSTEIN.Microelectron. J. 18(5), 29 (1987). Recently, considerable interest has arisen in the use of thick film technology for microwave circuit applications. The
thick film process can be used to fabricate microwave circuits that perform just as well as thin film counterparts in the lower-frequency region below 1 GHz, but systematic efforts to explore the upper frequency limit of thick-film technology with practical microwave circuits have been lacking. We describe such an effort which involved testing four scaled versions of one microwave circuit design over an 18-toone frequency range. By using the same basic design and scaling the circuit physically to cover a given sub-range, variations in the circuit design were eliminated and any degradation in measured performance can be attributed to intrinsic process limitations. Results are presented for octave-bandwidth Wilkinson power dividers for the frequency ranges 1-2 GHz, 2-4 GHz, 4-8 GHz, and 9-18 GHz. We conclude that satisfactory microwave performance can be obtained routinely from thick-film circuits up to approximately 10GHz, and with special attention designs can be extended to perhaps 12-15 GHz. A simple inexpensive method for thickness measurement of thin films. E. SADER. Vacuum 38, 97 (1988). A simple and inexpensive method for monitoring the thickness of thermally evaporated thin films is reported. The technique relies on a simple oscillating quartz crystal using TTL. The operation of the monitor is illustrated for thin aluminium and copper films. Their thickness is determined, by this method, to an accuracy of a few percent, as the deviations of the mass densities between the bulk material and the films are very small.
A comparison of the reliability of copper and palladiumsilver thick-film crossovers. ROBERTR. SUTHERLANDand IAN D. E. VIDELO. IEEE Trans. Compon. Hybrids mfff Technol. CHMT-12, 676 (1987). The reliability of palladium-silver crossover systems under 85*C/85-percent relative humidity bias stress has been shown to depend primarily on the porosity of the dielectric. All of the low-porosity dielectrics tested gave consistently good reliability, which met the British Telecom Research Laboratories (BTRL) specification, while all of the high-porosity dielectrics showed considerable variation in reliability and often failed to meet the specification. This variation was only partly explained by constructional features such as the dielectric thickness or the use of an overglaze. The palladium content of the conductors was shown not to influence the reliability of the crossovers. The reliability of all of the copper crossover systems tested was relatively poor, and the best system tested barely met the BTRL specification, many of the remainder failing by a wide margin. Nitrogen-fireable resistors; emerging technology for thickfilm hybrids. PAUL C. DONOHUE, JACOB HORMADALY, CHRISTOPHER R. S. NEEDES, SAMUEL J. HOROWITZ and JOACHIM F. KNAAK. IEEE Trans. Compon. Hybrids mfff Technol. CHMT-12, 537 (1987). A nitrogen-fireable basemetal thick-film resistor system compatible with copper conductors has been developed. A lanthanum hexaboride conductive phase is used to make resistor compositions in the range 10f~/[[]-10kf2/[7, and doped tin oxide is used as the conductive in the 10kg2/[:]-1 Mf~/[:] resistance range. An extensive technology transfer program to move this technology from the research laboratory to full commercial availability is under way. The environmental stability of 44 lots made in pilot, prototype, and manufacturing scale runs have been evaluated and confirm lot-to-lot reproducibility. Lanthanum boride members show good environmental stability under all conditions. Doped tin oxide members are humidity sensitive and require encapsulation. When encapsulated with an organic material, all grades show maximum changes of less than one percent after 1000h of exposure to 85*C/85-percent relative humidity. The kinetics of thin film resistor stabilisation. 1. A.