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A monolithic channel filter—manufacture with a new technology
WORLD
ABSTRACTS
ON MICROELECTRONICS
circuit calibrator used by G 3 T V U / M for the past two years, and after considering this instrument for some time the authors were finally spurred into action by the availability of numerical indicator tubes and low prices integrated circuit decoder/indicator tube drivers. It is believed that the instrument described may be built for less than £30. A n e w s e E - s c a n n e d p h o t o d i o d e array. R. H. DYCK and G. P. WECKLER. Solid State Technol., July (1971), p. 37. A new self-scanned photodiode array has been developed and is now available as a product. The monolithic integrated circuit consists of a linear array of photodiodes, a matching array of F E T sampling switches and a shift-counter. It is a silicon-gate F E T circuit and consequently it can be operated at higher scanning frequencies than feasible with conventional M O S F E T circuitry. The array operates in the storage mode, thus minimizing the required image intensity for a given application. External driving circuitry and amplifier circuitry are illustrated. Performance of a 128-element array is described. This array is well suited to optical character recognition applications and to facsimile reader applications.
P r o d u c t i o n o f a h y b r i d i n t e g r a t e d c i r c u i t for PICTUREPHONE ¢a) s e r v i c e . J. R. BITLER and A. R. GERHARD. Proc. 21st Electronic Components Conf., Washington DC, USA, 10-12 May (1971), p. 221. Mating of silicon integrated circuit (SIC) technology and tantalum integrated circuit (TIC) technology has been realized in a new generation production hybrid integrated circuit (HIC), the video processor for P I C T U R E P H O N E ¢~> service. On approximately threequarters of a square inch of ceramic are contained tantalum resistors and capacitors, silicon chips, and interconnections which perform five functions on the video signal of the P I C T U R E P H O N E ~R~ station set. A process sequence compatible for fabrication of resistors and capacitors from two tantalum layers on one substrate is the key to this newest hybrid design. This paper describes fabrication of the T I C and tuning, assembly and testing of the combined T I C and SICs required for production of this frequency selective analog hybrid integrated circuit. IC OP a m p s getting it all together. T. P. RIGOLI. EDN, 1 May (1971), p. 23. Ever since the 709 made its debut back in 1965, IC op amps have become quite inexpensive and rather ubiquitous. With the gardenvariety op amps (under $3) satisfying most applications, vendors and users generally agree--the trend will be toward more window dressing and special-purpose devices. A s t u d y o f the c o n t a c t s of a d i f f u s e d resistor. C-Y. TING and C. Y. CHEN. Solid State Electron. 14 (1971), p. 433. The total resistance of a diffused resistor can be expressed in terms of bulk sheet resistance and three correction terms--namely, contact resistance, current crowding resistance in the contact region, and
AND RELIABILITY
21
contact width correction. The latter two terms have been arrived at theoretically. A new test structure has been designed to measure the metal-silicon contact sheet resistivity and the contact resistance of the resistor. The maximum current density in the contact region is also determined experimentally.
M e t a l l u r g i c a l properties a n d e l e c t r i c a l c h a r a c teristics o f p a l l a d i u m s i l i c i d e - - s i l i c o n c o n t a c t s . C. J. KmCHEa. Solid State Electron. 14, p. 507. The fabrication, metallurgical properties and electrical characteristics of palladium silicide (PdzSi) contacts to n-type Si have been investigated. Pd2Si/Si contacts are similar in electrical and metallurgical behavior to PtSi/Si contacts, but can be fabricated at much lower temperatures. Pd was found to react readily with Si at 200°C to form a silicide phase which was identified as PdzSi from X-ray diffraction analysis. The electrical resistivity of the silicide is 40 X 10-e f~ cm as determined from sheet resistivity measurements. The barrier height at the PdzSi/Si interface was determined from differential capacitance measurements to be 0"745 :t: 0'015 V. Current-voltage measurements and activation energy analysis gave barrier heights within this same range. Contact resistance measurements were made on contacts to Si surfaces with phosphorus doping levels of 2 × 102°Jcm3. Resistance values obtained are comparable to both theoretical predictions and measurements reported on PtSi and A1 contacts to Si. MOS/LSI brings c o m p l e x c i r c u i t s w i t h i n r e a c h of a n y d e s i g n e r . S. A. WHITE. Electronics, 5 July (1971), p. 62. Step-by-step layout of a variable-coefficient digital filter and a fast-converging digital square-rooter are just two formerly tough jobs made easy by new multiplier and shift register/adder chips. MOSFET m e m o r y circuits. L. M. TERMAN. Proc. I E E E 59, No. 7, July (1971), p. 1044. Metal-oxidesemiconductor first effect transistors (MOSFETs) are currently being used in a variety of memory applications. The requirements of memory usage and the characteristics of M O S F E T devices and technology have led to a number of unique circuits for these applications. Organization and design considerations of memory systems using M O S F E T devices are reviewed, and examples of specific circuits are presented and analyzed. These include random access cells, shift registers, read only storage and on-chlp support circuits; both complementary and non-complementary circuits are discussed. A monolithic channel filter--manufacture with a n e w t e c h n o l o g y . J. D. JENNINGS and P. R. PERRI. Proc. 21st Electronic Components Conf., Washington DC, USA, 10-12 May (1971), p. 365. Many monolithic crystal voice channel filters at 8 MHz satisfying transmission requirements have been made. The M C F is an eight-pole Chebyshev design with 0-1 dB ripple and a bandwidth of 3"26 KHz. Large rectangular plates can now be economically produced that are parallel to
22
WORLD
ABSTRACTS
ON MICROELECTRONICS
q-6~in, and crystaUographically uniform to within ± 1 min of arc. The mechanical design utilizes a cold welded flat pack enclosure and an internal crystal mounting arrangement employing thermo-compression bonding of the quartz plate. The process and many of the unique, highly mechanized facilities developed to fabricate this device are described.
M a t c h e d - v a r a c t o r c h i p brings e l e c t r o n i c t u n i n g to a - m radios. G. JONKUHN and C. H. LEMBKE. Electronics, 19 July (1971), p. 59. Now it is feasible to build economical varactor tuners for the a-m band by dividing the broadcast range into three frequencies and using
7. S E M I C O N D U C T O R
INTEGRATED
T h e m e a s u r e m e n t o f i n t e r f a c e state c h a r g e in the MOS s y s t e m . J. KOOMEN. Solid State Electron. 14 (1971), p. 571. A simple method of measuring charge in surface states as a function of the surfacepotential in MOS transistors or M O S capacitors is proposed. A constant d.c. current is fed into the gate of an MOS transistor and with the help of an operational amplifier, the gate voltage Vg with respect to the bulk is plotted as a function of gate charge Qg. The gate charge as a function of the surfacepotential o s can be directly read off from the Vg-Qg curve. As the silicon charge Qs(os) is known from the literature the surface state charge can be easily determined as a function of os. The method is illustrated with measurements on n-type and p-type MOS transistors. Finally the accuracy of the charge measuring method is discussed and a comparison with other interface state charge measuring methods is made from which the charge measuring method evolves as a method, attractive for its simplicity. D e v e l o p m e n t s in c o p p e r a l l o y s for s e m i c o n d u c t o r c o n n e c t o r s a n d p a c k a g e s . S. H. BUTT. Proc. 21st Electronic Components Conf., Washington DC, USA, 10-12 May (1971), p. 103. Two groups of newer copper alloys are discussed, a high conductivity group and a high strength-high performance group. Both have application in semiconductor packages and in connectors. High conductivity copper alloys have come into wide use in the semiconductor industry as lead frames for use with plastic encapsulated devices. As compared to nickel, iron-nickel and iron-nickel-cobalt alloys, the copper alloys offer considerable cost savings. The most widely used copper alloy is copper-iron-phosphorus, Alloy 194. A high strength, high conductivity Alloy 0195 (copperiron-cobalt-tin-phosphorus) is now being introduced. Properties of Alloys 194 and 0195 are described and compared to those of other copper alloys as well as nickel and the traditional alloys. T h e s o l u b i l i t y o f c a r b o n in p u l l e d s i l i c o n crystals. A. R. BEAN and R. C. NEWMAN..7. Phys. Chem. Solids 32 (1971), p. 1211. Single crystals of silicon grown by the Czochralski technique have been annealed at various
AND RELIABILITY
individual segments of a triplet on a single chip to tune across each.
F r i n g e field c o r r e c t i o n s for c a p a c i t o r s on thin d i e l e c t r i c layers. C. H. SEQUIN.Solid State Electron. 14 (1971), p. 417. An approximate formula is derived which yields the fringe field correction explicitly in terms of the parameters of the electrode configuration for the frequently encountered case of plane parallel electrodes, of which one is circular and the other infinitely large. Other related cases are also discussed. The error is typically of the order of 1 per cent. The formulae are useful in determining the dielectric constants of crystalline platelets.
CIRCUITS, DEVICES AND MATERIALS temperatures in the range 600-1350°C. IR measurements have been made of the strength of the absorption bands due to carbon (16'5 ~tm) and oxygen (9 Izm). From the measurements, heats of solution of the two impurities of 53 ± 6 and 38 ± 4 kcal/mole have been deduced respectively. When carbon precipitates broad absorption is produced in the region of 12 ~tm which is attributed to silicon carbide particles. The strength of this absorption is found to be consistent with the estimated loss of carbon from solution. Precipitation of silicon carbide was not observed in oxygen-free crystals.
T y p i c a l c u r r e n t vs. v o l t a g e c u r v e o f s o d i u m s i l i c o n N contact. H e i g h t o f p o t e n t i a l barrier. N. SZYDLO. Rev. Tech. Thomson-CSF 3, No. 2, June (1971), p. 205. (In French.) Having shown that the classical Richardson-Dushmann relationship for the thermoionic current of an Au-Si N Schottky diode does not always permit a good agreement between theory and experiment unless corrective terms are introduced, the author reviews the various theories for metal-semiconductor contact. He makes a special study of the correlation established by A. M. Cowley and S. M. Sze between the height of the potential barrier and the work function of the metal. Though unsatisfactory in the case of metals with high work function, this correlation is not verified by experimental results in the case of metals with low output work like the alkalis, as shown by the results obtained with sodium-silicon N contacts in which the height of the potential barrier is 0.43 × 0.03 eV. C h a r a c t e r i z a t i o n o f SiO u s i n g fine f e a t u r e s o f X-ray K e m i s s i o n spectra. W. L. BAUN,J. S. SOLOMON. Vacuum 21, No. 5 (1971), p. 165. The fine features of silicon and oxygen K X-ray emission spectra may be used to characterize thin-film and bulk SiO. The Si K s satellites K~3 and K~4, Si K~ and KW, and the O K band are all very sensitive to chemical combination. The X-ray spectral features indicate that SiO in the condensed state is an intimate mixture of Si and SiO~. The K % and K~4 satellite lines are especially valuable for quantitative analysis of the two components of SiO films.
ABSTRACTS
ON MICROELECTRONICS
circuit calibrator used by G 3 T V U / M for the past two years, and after considering this instrument for some time the authors were finally spurred into action by the availability of numerical indicator tubes and low prices integrated circuit decoder/indicator tube drivers. It is believed that the instrument described may be built for less than £30. A n e w s e E - s c a n n e d p h o t o d i o d e array. R. H. DYCK and G. P. WECKLER. Solid State Technol., July (1971), p. 37. A new self-scanned photodiode array has been developed and is now available as a product. The monolithic integrated circuit consists of a linear array of photodiodes, a matching array of F E T sampling switches and a shift-counter. It is a silicon-gate F E T circuit and consequently it can be operated at higher scanning frequencies than feasible with conventional M O S F E T circuitry. The array operates in the storage mode, thus minimizing the required image intensity for a given application. External driving circuitry and amplifier circuitry are illustrated. Performance of a 128-element array is described. This array is well suited to optical character recognition applications and to facsimile reader applications.
P r o d u c t i o n o f a h y b r i d i n t e g r a t e d c i r c u i t for PICTUREPHONE ¢a) s e r v i c e . J. R. BITLER and A. R. GERHARD. Proc. 21st Electronic Components Conf., Washington DC, USA, 10-12 May (1971), p. 221. Mating of silicon integrated circuit (SIC) technology and tantalum integrated circuit (TIC) technology has been realized in a new generation production hybrid integrated circuit (HIC), the video processor for P I C T U R E P H O N E ¢~> service. On approximately threequarters of a square inch of ceramic are contained tantalum resistors and capacitors, silicon chips, and interconnections which perform five functions on the video signal of the P I C T U R E P H O N E ~R~ station set. A process sequence compatible for fabrication of resistors and capacitors from two tantalum layers on one substrate is the key to this newest hybrid design. This paper describes fabrication of the T I C and tuning, assembly and testing of the combined T I C and SICs required for production of this frequency selective analog hybrid integrated circuit. IC OP a m p s getting it all together. T. P. RIGOLI. EDN, 1 May (1971), p. 23. Ever since the 709 made its debut back in 1965, IC op amps have become quite inexpensive and rather ubiquitous. With the gardenvariety op amps (under $3) satisfying most applications, vendors and users generally agree--the trend will be toward more window dressing and special-purpose devices. A s t u d y o f the c o n t a c t s of a d i f f u s e d resistor. C-Y. TING and C. Y. CHEN. Solid State Electron. 14 (1971), p. 433. The total resistance of a diffused resistor can be expressed in terms of bulk sheet resistance and three correction terms--namely, contact resistance, current crowding resistance in the contact region, and
AND RELIABILITY
21
contact width correction. The latter two terms have been arrived at theoretically. A new test structure has been designed to measure the metal-silicon contact sheet resistivity and the contact resistance of the resistor. The maximum current density in the contact region is also determined experimentally.
M e t a l l u r g i c a l properties a n d e l e c t r i c a l c h a r a c teristics o f p a l l a d i u m s i l i c i d e - - s i l i c o n c o n t a c t s . C. J. KmCHEa. Solid State Electron. 14, p. 507. The fabrication, metallurgical properties and electrical characteristics of palladium silicide (PdzSi) contacts to n-type Si have been investigated. Pd2Si/Si contacts are similar in electrical and metallurgical behavior to PtSi/Si contacts, but can be fabricated at much lower temperatures. Pd was found to react readily with Si at 200°C to form a silicide phase which was identified as PdzSi from X-ray diffraction analysis. The electrical resistivity of the silicide is 40 X 10-e f~ cm as determined from sheet resistivity measurements. The barrier height at the PdzSi/Si interface was determined from differential capacitance measurements to be 0"745 :t: 0'015 V. Current-voltage measurements and activation energy analysis gave barrier heights within this same range. Contact resistance measurements were made on contacts to Si surfaces with phosphorus doping levels of 2 × 102°Jcm3. Resistance values obtained are comparable to both theoretical predictions and measurements reported on PtSi and A1 contacts to Si. MOS/LSI brings c o m p l e x c i r c u i t s w i t h i n r e a c h of a n y d e s i g n e r . S. A. WHITE. Electronics, 5 July (1971), p. 62. Step-by-step layout of a variable-coefficient digital filter and a fast-converging digital square-rooter are just two formerly tough jobs made easy by new multiplier and shift register/adder chips. MOSFET m e m o r y circuits. L. M. TERMAN. Proc. I E E E 59, No. 7, July (1971), p. 1044. Metal-oxidesemiconductor first effect transistors (MOSFETs) are currently being used in a variety of memory applications. The requirements of memory usage and the characteristics of M O S F E T devices and technology have led to a number of unique circuits for these applications. Organization and design considerations of memory systems using M O S F E T devices are reviewed, and examples of specific circuits are presented and analyzed. These include random access cells, shift registers, read only storage and on-chlp support circuits; both complementary and non-complementary circuits are discussed. A monolithic channel filter--manufacture with a n e w t e c h n o l o g y . J. D. JENNINGS and P. R. PERRI. Proc. 21st Electronic Components Conf., Washington DC, USA, 10-12 May (1971), p. 365. Many monolithic crystal voice channel filters at 8 MHz satisfying transmission requirements have been made. The M C F is an eight-pole Chebyshev design with 0-1 dB ripple and a bandwidth of 3"26 KHz. Large rectangular plates can now be economically produced that are parallel to
22
WORLD
ABSTRACTS
ON MICROELECTRONICS
q-6~in, and crystaUographically uniform to within ± 1 min of arc. The mechanical design utilizes a cold welded flat pack enclosure and an internal crystal mounting arrangement employing thermo-compression bonding of the quartz plate. The process and many of the unique, highly mechanized facilities developed to fabricate this device are described.
M a t c h e d - v a r a c t o r c h i p brings e l e c t r o n i c t u n i n g to a - m radios. G. JONKUHN and C. H. LEMBKE. Electronics, 19 July (1971), p. 59. Now it is feasible to build economical varactor tuners for the a-m band by dividing the broadcast range into three frequencies and using
7. S E M I C O N D U C T O R
INTEGRATED
T h e m e a s u r e m e n t o f i n t e r f a c e state c h a r g e in the MOS s y s t e m . J. KOOMEN. Solid State Electron. 14 (1971), p. 571. A simple method of measuring charge in surface states as a function of the surfacepotential in MOS transistors or M O S capacitors is proposed. A constant d.c. current is fed into the gate of an MOS transistor and with the help of an operational amplifier, the gate voltage Vg with respect to the bulk is plotted as a function of gate charge Qg. The gate charge as a function of the surfacepotential o s can be directly read off from the Vg-Qg curve. As the silicon charge Qs(os) is known from the literature the surface state charge can be easily determined as a function of os. The method is illustrated with measurements on n-type and p-type MOS transistors. Finally the accuracy of the charge measuring method is discussed and a comparison with other interface state charge measuring methods is made from which the charge measuring method evolves as a method, attractive for its simplicity. D e v e l o p m e n t s in c o p p e r a l l o y s for s e m i c o n d u c t o r c o n n e c t o r s a n d p a c k a g e s . S. H. BUTT. Proc. 21st Electronic Components Conf., Washington DC, USA, 10-12 May (1971), p. 103. Two groups of newer copper alloys are discussed, a high conductivity group and a high strength-high performance group. Both have application in semiconductor packages and in connectors. High conductivity copper alloys have come into wide use in the semiconductor industry as lead frames for use with plastic encapsulated devices. As compared to nickel, iron-nickel and iron-nickel-cobalt alloys, the copper alloys offer considerable cost savings. The most widely used copper alloy is copper-iron-phosphorus, Alloy 194. A high strength, high conductivity Alloy 0195 (copperiron-cobalt-tin-phosphorus) is now being introduced. Properties of Alloys 194 and 0195 are described and compared to those of other copper alloys as well as nickel and the traditional alloys. T h e s o l u b i l i t y o f c a r b o n in p u l l e d s i l i c o n crystals. A. R. BEAN and R. C. NEWMAN..7. Phys. Chem. Solids 32 (1971), p. 1211. Single crystals of silicon grown by the Czochralski technique have been annealed at various
AND RELIABILITY
individual segments of a triplet on a single chip to tune across each.
F r i n g e field c o r r e c t i o n s for c a p a c i t o r s on thin d i e l e c t r i c layers. C. H. SEQUIN.Solid State Electron. 14 (1971), p. 417. An approximate formula is derived which yields the fringe field correction explicitly in terms of the parameters of the electrode configuration for the frequently encountered case of plane parallel electrodes, of which one is circular and the other infinitely large. Other related cases are also discussed. The error is typically of the order of 1 per cent. The formulae are useful in determining the dielectric constants of crystalline platelets.
CIRCUITS, DEVICES AND MATERIALS temperatures in the range 600-1350°C. IR measurements have been made of the strength of the absorption bands due to carbon (16'5 ~tm) and oxygen (9 Izm). From the measurements, heats of solution of the two impurities of 53 ± 6 and 38 ± 4 kcal/mole have been deduced respectively. When carbon precipitates broad absorption is produced in the region of 12 ~tm which is attributed to silicon carbide particles. The strength of this absorption is found to be consistent with the estimated loss of carbon from solution. Precipitation of silicon carbide was not observed in oxygen-free crystals.
T y p i c a l c u r r e n t vs. v o l t a g e c u r v e o f s o d i u m s i l i c o n N contact. H e i g h t o f p o t e n t i a l barrier. N. SZYDLO. Rev. Tech. Thomson-CSF 3, No. 2, June (1971), p. 205. (In French.) Having shown that the classical Richardson-Dushmann relationship for the thermoionic current of an Au-Si N Schottky diode does not always permit a good agreement between theory and experiment unless corrective terms are introduced, the author reviews the various theories for metal-semiconductor contact. He makes a special study of the correlation established by A. M. Cowley and S. M. Sze between the height of the potential barrier and the work function of the metal. Though unsatisfactory in the case of metals with high work function, this correlation is not verified by experimental results in the case of metals with low output work like the alkalis, as shown by the results obtained with sodium-silicon N contacts in which the height of the potential barrier is 0.43 × 0.03 eV. C h a r a c t e r i z a t i o n o f SiO u s i n g fine f e a t u r e s o f X-ray K e m i s s i o n spectra. W. L. BAUN,J. S. SOLOMON. Vacuum 21, No. 5 (1971), p. 165. The fine features of silicon and oxygen K X-ray emission spectra may be used to characterize thin-film and bulk SiO. The Si K s satellites K~3 and K~4, Si K~ and KW, and the O K band are all very sensitive to chemical combination. The X-ray spectral features indicate that SiO in the condensed state is an intimate mixture of Si and SiO~. The K % and K~4 satellite lines are especially valuable for quantitative analysis of the two components of SiO films.