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Application of photoresists in semiconductor manufacturing
418
WORLD
ABSTRACTS
ON
MICROELECTRONICS
AND
RELIABILITY
"On the chip" m u l t i l e v e l interconnection. K. D.
Survey
PERKINS. Proc. Tech. Prog. I N T E R / N E P O N 1970, Brighton, 13-15 O c t o b e r (1970), p. V I - 5 6 . T h i s p a p e r discusses s o m e of t h e c o m m o n l y e n c o u n t e r e d p r o b l e m s in t h e fabrication of multilevel interconnections on a silicon integrated circuit chip. T h e s y s t e m to be described is based on a v a c u u m - d e p o s i t e d a l u m i n u m metallization with r.f. s p u t t e r e d silicon dioxide as t h e interlevel dielectric. S o m e reference is m a d e h o w e v e r to o t h e r metallization s y s t e m s (in particular the gold-based systems) a n d t h e relative advantages a n d disadvantages of each discussed.
C. E. JOWETT. Microelectronics 3, No. 10, S p r i n g (1971~, p. 5. T h e n u m b e r of t e c h n i q u e s for clectrically inter-c o n n e c t i n g s e m i c o n d u c t o r devices has proliferated e n o r m o u s l y d u r i n g the last few years. If all the possible p e r t u r b a t i o n s of t e m p e r a t u r e grades, materials and different metallurgical processes are considered, there exists several h u n d r e d variations. T h i s article a t t e m p t s to provide a compilation, s t r u c t u r e and review ~,f those methods.
Plasma-grown AI20 a for COS/MOS integrated circuits. F. B. MICHELETTI, P. E. NORRIS and K. H. ZAININGER. Solid St. Technol., April (1971), p. 27. I n t e g r a t e d circuits have been fabricated u s i n g A1203 as t h e gate insulator. T h e s e circuits, d e m o n s t r a t e a h i g h degree of radiation h a r d n e s s and prove the feasibility of A1203 M O S technology. I n this article, the processing steps are described a n d t h e i m p o r t a n t electrical properties are given.
Design of c u s t o m i s e d microelectronics masks using off-line and on-line computer aids. B. R. KIRK. Proc. Tech. Prog. I N T E R / N E P C O N 1970, Brighton, 13-15 O c t o b e r (1970), p. X - 3 9 . I n t h e early days of microcircuit m a n u f a c t u r e a n e w design was d r a w n out, by engineers, to a large scale on g r a p h paper, t h e various m a s k layers being d r a w n in different colours. T h i s d r a w i n g was t h e n " c o - o r d i n a t e d " , that is t h e X a n d Y co-ordinates on each s h a p e of each layer of the d r a w i n g were noted. T h i s list of co-ordinates for each layer was t h e n u s e d b y an operator to c u t t h e artwork p a t t e r n on " c u t - ' n - s t r i p " material u s i n g a m a n u a l l y controlled co-ordinatograph. T h i s m e t h o d of operation soon b e c a m e impractical because of its susceptibility to h u m a n error a n d low s p e e d of operation. C o m p u t e r aided design, u s i n g OFF-line c o m p u t e r s , was i n t r o d u c e d in an a t t e m p t to reduce h u m a n error a n d speed artwork production. T h e fact that m o s t microcircuits contain g r o u p s of lines, on one or m o r e layers, w h i c h are used repetitively, for example, one stage of a shift register, is p u t to good u s e in m o s t OFF-line artwork p r o g r a m m e s . T h e s y s t e m c u r r e n t l y in u s e is called C A M P ( C o m p u t e r A i d e d M a s k Production). A r e f i n e m e n t of the OFF-line C A M P s y s t e m has been developed utilizing the oN-line facilities of t h e M a r c o n i X-2000 interactive graphics s y s t e m ; this d e v e l o p m e n t was u n d e r t a k e n initially at t h e M a r c o n i R e s e a r c h Laboratories a n d latterly at G E C S e m i c o n d u c t o r s L i m i t e d . A c o m p r e h e n s i v e artwork d e s i g n facility h a s b e e n developed w h i c h incorporates all t h e advantages of the OFF-line a n d oN-line c o m p u t i n g aids; t h e two s y s t e m s are compatible enabling designs to be progressed on w h i c h e v e r s y s t e m is conveniently available. T h e e n d p r o d u c t of t h e c o m p u t e r b a s e d s y s t e m s is a set o f steering tapes w h i c h are u s e d to drive a n u m e r i c a l l y controlled c o - o r d i n a t o g r a p h w h i c h prod u c e s t h e artwork for each m a s k layer on c u t - ' n - s t r i p material.
of
semiconductor
joining
techniques.
Turn around t i m e for custom LSI r e d u c e d using reprocessed multilayers. A Cmclrror:1~ a n d ,L }'ort. Proc. Tech. Prog. I N T E R / N E P C O N 1970, t~righton~ 13-15 O c t o b e r (1970), p. V I I I - 3 5 . A new intercom~cction concept is described w h i c h has aIl of the advar)tages of multilayer m e d i a and none of th~ disadxantagcs. A d v a n t a g e s in circuit densities and reliability are retained while disadvantages of long turn-arom~d-tinl~. h i g h tooling costs a n d inflexibility of design changes are eliminated. Utilization of pre-processed multilaycr interconnections provide the basis for this concept, a~ld w h e n partitioned in a m u l t i - t i e r a r r a n g e m e n t , results in a complete L S [ configuration. F o u r preprocessed multilayer a s s e m b l y levels result in a s y s t e m packaginv density w h i c h is comparable to the "ful wafer" approach to L S I . A n y s y s t e m logic configuration can be implem e n t e d w i t h i n two weeks after generation <~f logic equations. T h e c o m m o n feature of all forms ot multi.layer m e d i a described is that all internal conductive layers are standard. E t c h i n g of outer surfaces is all that is required to effect a c u s t o m design. Standardization of t h e i n n e r layers p e r m i t s t h e preprocessing of the multilayers at all levels of assembly. T h e basic building block is a multicellular array of logic elements on a monolithic chip designated M L C ( M a s t e r logic chip). T h e chip contains a s t a n d a r d p r o g r a m m a b l e interconnection network, and therefore can be used to i m p l e m e n t any c u s t o m function. Similarly, a second tier multilaycr ceramic substrate, t h i r d tier multilaycr p r i n t e d circuit board, a n d f o u r t h tier flexible multilayer p r i n t e d circuit backplane all are topologically s t r u c t u r e d s u c h that the3" can be c u s t o m i z e d by a simple one-step process. T h e topology u s e d at all levels is s t r u c t u r e d s u c h that technological advances at t h e wafer level can be incorporated directly into existing designs t h u s affording still higher s y s t e m densities as these advances occur.
Application of photoresists in semiconductor manufacturing. K. G. CLARK. 'llicroelectronics 3, No. 10, S p r i n g (1971), p. 25. T h i s paper p r e s e n t s both a review a n d evaluation of t h e p r e s e n t state of c o m m e r cially available photoresist application s y s t e m s . Application systems, as applied in t h e s e m i c o n d u c t o r i n d u s t r y , call for exacting r e q u i r e m e n t s in t h e preparation of the photoresist. T h e subjects w h i c h have been dealt with are as follows: Preparation of t h e photoresist t%r p a r t i c u l a t e - m a t t e r purification; surface conditions a n d t r e a t m e n t s ; s p i n n e r application of the photoresist; i m a g i n g condition a n d u.v. light sources. D e v e l o p m e n t ,
WORLD baking, etching and techniques.
Metallization
ABSTRACTS
ON MICROELECTRONICS
washing, photoresist removal
systems
for integrated
circuits.
R. W. WILSON and L. E. TERRY. Proc. Teeh. Prog. I N T E R / N E P O N 1970, Brighton, 13-15 October (1970), p. VIII-1. A metallization system must satisfy certain conditions if it is to be used in the fabrication of semiconductor devices. These conditions or constraints are as follows : A. The material should have a high conductivity (0 < 1 0 ~ n/era). B. It should have good adhesion to both the semiconductor material and to thermally grown or deposited dielectric films. C. The metal or metals should be free from degrading
ington D.C., U.S.A., 10-12 May (1971), p. 408. The Meteorological Data Sounding System measures the meteorological characteristics of the atmosphere. The $254 is the transmitter that was designed for this system to transmit the temperature and relative humidity data to the ground station from a balloon-borne payload during the ascent and descent. The transmitter consists of three major sections : the modulator/voltage regulator, the oscillator and antenna. The described transmitter delivers a minimum of 50 m W over the --70 ° to +70°C temperature range while the input voltage is varied between 30 and 20V. The transfer characteristic (resistance as a function of frequency) of the modulator is accurate enough to permit the determination of atmospheric temperature to within one-half a degree.
Microprogramming m a d e e a s y - - w i t h a 4,096-bit bipolar ROM. S. SIRKIN. Electronics, 15 March (1971), p. 64. Complex digital systems need complex, expensive control systems; but the latest bipolar processing techniques have produced a fast ROM that's large enough for the job and can save about $100 per device used.
The effects of in-process heating on K1200 monolithic multilayer capacitors. R. F. TINDALL. Proc. Tech. Prog. I N T E R / N E P C O N 1970, Brighton, 13-15 October (1970), p. VI-46. It is well known that while ceramic capacitors are among the most reliable components available, the high K types do exhibit considerable capacitance variations with temperature and time. The result of these variations is that it is difficult for the user to predict the capacitance value of a K1200 capacitor after a temperature change has occurred, either during processing of the circuit or during the life of the capacitor, to any precision better than, say ~ 1 0 per cent. This paper describes a series of exploratory experiments in which an attempt has been made to evaluate the changes in capacitance experienced by K1200 chip capacitors as a result of heating, and the
419
intermetallie compounds not only between metal films, but between the metal and the semiconductor. D. Should make a good low ohmic contact to both p and n type siiicon. E. Amenable to practical production methods of deposition and delineation. F. Resistant to current-induced electro-migration. G. Resistant to electro-chemical corrosion. H. The deposition of the metal or metals must not introduce surface instabilities in the semiconductor material. I.
6. M I C R O E L E C T R O N I C S - - C O M P O N E N T S , A hybrid thin-film radiosonde transmitter. R. E. ASKEW. Proc. 21st Electronic Components Conf., Wash-
AND RELIABILITY
The metallization system must be compatible with LSI arrays involving multilayer interconnection processing.
SYSTEMS AND EQUIPMENTS
subsequent recovery from heating. It is hoped that these results will enable the user to predict with a fair degree of certainty, the behaviour of these capacitors.
Capacitors in m i c r o w a v e integrated circuits. H. KATOH. Trans. Inst. Elec. Comm. Engrs Japan 54-B, No. 3, March (1971), p. 95. (In Japanese.) An expression for the complex impedance of thin film capacitors whose electrodes come in from opposite sides has been derived, including the distributed resistive and inductive effect of the electrode. The result indicates that at microwave frequencies the resistance and reactance of capacitors are due mainly to that of the electrodes. Furthermore, the loss factor of such capacitors as Tantalum thin film capacitors, SiO thin film capacitors and ceramic chip capacitors was confirmed experimentally by measuring the change in Q of a strip-line resonant system with the addition of them.
The use of passive chip components in hybrid integrated circuits. D. W. HAMER. Pro& 21st Electronic Components Conf., Washington D.C., U.S.A., 10-12 May (1971), p. 27. This paper looks at the various reasons a hybrid integrated circuit manufacturer would have for using passive chip components in his designs, rather than using thick or thin integrated circuit technology for fabrication of these elements. Emphasis in this analysis is placed on resistors and capacitors (rather than all types of discrete components) and on chips (rather than on minicomponents and other leaded devices).
MOSFETS rejuvenate old design for CATV broadband amplifiers. D. V. LEE. Electronics, 15 March (1971), p. 72. The large dynamic range and low crossmodulation distortion of low-cost ~[OSFETs, plus a distributed-amplifier configuration, can provide a highlevel output suitable for v.h.f, coverage.
The m e a s u r e m e n t of linear circuits with a computer-operated system. G. MILLER. Proc. Tech.
WORLD
ABSTRACTS
ON
MICROELECTRONICS
AND
RELIABILITY
"On the chip" m u l t i l e v e l interconnection. K. D.
Survey
PERKINS. Proc. Tech. Prog. I N T E R / N E P O N 1970, Brighton, 13-15 O c t o b e r (1970), p. V I - 5 6 . T h i s p a p e r discusses s o m e of t h e c o m m o n l y e n c o u n t e r e d p r o b l e m s in t h e fabrication of multilevel interconnections on a silicon integrated circuit chip. T h e s y s t e m to be described is based on a v a c u u m - d e p o s i t e d a l u m i n u m metallization with r.f. s p u t t e r e d silicon dioxide as t h e interlevel dielectric. S o m e reference is m a d e h o w e v e r to o t h e r metallization s y s t e m s (in particular the gold-based systems) a n d t h e relative advantages a n d disadvantages of each discussed.
C. E. JOWETT. Microelectronics 3, No. 10, S p r i n g (1971~, p. 5. T h e n u m b e r of t e c h n i q u e s for clectrically inter-c o n n e c t i n g s e m i c o n d u c t o r devices has proliferated e n o r m o u s l y d u r i n g the last few years. If all the possible p e r t u r b a t i o n s of t e m p e r a t u r e grades, materials and different metallurgical processes are considered, there exists several h u n d r e d variations. T h i s article a t t e m p t s to provide a compilation, s t r u c t u r e and review ~,f those methods.
Plasma-grown AI20 a for COS/MOS integrated circuits. F. B. MICHELETTI, P. E. NORRIS and K. H. ZAININGER. Solid St. Technol., April (1971), p. 27. I n t e g r a t e d circuits have been fabricated u s i n g A1203 as t h e gate insulator. T h e s e circuits, d e m o n s t r a t e a h i g h degree of radiation h a r d n e s s and prove the feasibility of A1203 M O S technology. I n this article, the processing steps are described a n d t h e i m p o r t a n t electrical properties are given.
Design of c u s t o m i s e d microelectronics masks using off-line and on-line computer aids. B. R. KIRK. Proc. Tech. Prog. I N T E R / N E P C O N 1970, Brighton, 13-15 O c t o b e r (1970), p. X - 3 9 . I n t h e early days of microcircuit m a n u f a c t u r e a n e w design was d r a w n out, by engineers, to a large scale on g r a p h paper, t h e various m a s k layers being d r a w n in different colours. T h i s d r a w i n g was t h e n " c o - o r d i n a t e d " , that is t h e X a n d Y co-ordinates on each s h a p e of each layer of the d r a w i n g were noted. T h i s list of co-ordinates for each layer was t h e n u s e d b y an operator to c u t t h e artwork p a t t e r n on " c u t - ' n - s t r i p " material u s i n g a m a n u a l l y controlled co-ordinatograph. T h i s m e t h o d of operation soon b e c a m e impractical because of its susceptibility to h u m a n error a n d low s p e e d of operation. C o m p u t e r aided design, u s i n g OFF-line c o m p u t e r s , was i n t r o d u c e d in an a t t e m p t to reduce h u m a n error a n d speed artwork production. T h e fact that m o s t microcircuits contain g r o u p s of lines, on one or m o r e layers, w h i c h are used repetitively, for example, one stage of a shift register, is p u t to good u s e in m o s t OFF-line artwork p r o g r a m m e s . T h e s y s t e m c u r r e n t l y in u s e is called C A M P ( C o m p u t e r A i d e d M a s k Production). A r e f i n e m e n t of the OFF-line C A M P s y s t e m has been developed utilizing the oN-line facilities of t h e M a r c o n i X-2000 interactive graphics s y s t e m ; this d e v e l o p m e n t was u n d e r t a k e n initially at t h e M a r c o n i R e s e a r c h Laboratories a n d latterly at G E C S e m i c o n d u c t o r s L i m i t e d . A c o m p r e h e n s i v e artwork d e s i g n facility h a s b e e n developed w h i c h incorporates all t h e advantages of the OFF-line a n d oN-line c o m p u t i n g aids; t h e two s y s t e m s are compatible enabling designs to be progressed on w h i c h e v e r s y s t e m is conveniently available. T h e e n d p r o d u c t of t h e c o m p u t e r b a s e d s y s t e m s is a set o f steering tapes w h i c h are u s e d to drive a n u m e r i c a l l y controlled c o - o r d i n a t o g r a p h w h i c h prod u c e s t h e artwork for each m a s k layer on c u t - ' n - s t r i p material.
of
semiconductor
joining
techniques.
Turn around t i m e for custom LSI r e d u c e d using reprocessed multilayers. A Cmclrror:1~ a n d ,L }'ort. Proc. Tech. Prog. I N T E R / N E P C O N 1970, t~righton~ 13-15 O c t o b e r (1970), p. V I I I - 3 5 . A new intercom~cction concept is described w h i c h has aIl of the advar)tages of multilayer m e d i a and none of th~ disadxantagcs. A d v a n t a g e s in circuit densities and reliability are retained while disadvantages of long turn-arom~d-tinl~. h i g h tooling costs a n d inflexibility of design changes are eliminated. Utilization of pre-processed multilaycr interconnections provide the basis for this concept, a~ld w h e n partitioned in a m u l t i - t i e r a r r a n g e m e n t , results in a complete L S [ configuration. F o u r preprocessed multilayer a s s e m b l y levels result in a s y s t e m packaginv density w h i c h is comparable to the "ful wafer" approach to L S I . A n y s y s t e m logic configuration can be implem e n t e d w i t h i n two weeks after generation <~f logic equations. T h e c o m m o n feature of all forms ot multi.layer m e d i a described is that all internal conductive layers are standard. E t c h i n g of outer surfaces is all that is required to effect a c u s t o m design. Standardization of t h e i n n e r layers p e r m i t s t h e preprocessing of the multilayers at all levels of assembly. T h e basic building block is a multicellular array of logic elements on a monolithic chip designated M L C ( M a s t e r logic chip). T h e chip contains a s t a n d a r d p r o g r a m m a b l e interconnection network, and therefore can be used to i m p l e m e n t any c u s t o m function. Similarly, a second tier multilaycr ceramic substrate, t h i r d tier multilaycr p r i n t e d circuit board, a n d f o u r t h tier flexible multilayer p r i n t e d circuit backplane all are topologically s t r u c t u r e d s u c h that the3" can be c u s t o m i z e d by a simple one-step process. T h e topology u s e d at all levels is s t r u c t u r e d s u c h that technological advances at t h e wafer level can be incorporated directly into existing designs t h u s affording still higher s y s t e m densities as these advances occur.
Application of photoresists in semiconductor manufacturing. K. G. CLARK. 'llicroelectronics 3, No. 10, S p r i n g (1971), p. 25. T h i s paper p r e s e n t s both a review a n d evaluation of t h e p r e s e n t state of c o m m e r cially available photoresist application s y s t e m s . Application systems, as applied in t h e s e m i c o n d u c t o r i n d u s t r y , call for exacting r e q u i r e m e n t s in t h e preparation of the photoresist. T h e subjects w h i c h have been dealt with are as follows: Preparation of t h e photoresist t%r p a r t i c u l a t e - m a t t e r purification; surface conditions a n d t r e a t m e n t s ; s p i n n e r application of the photoresist; i m a g i n g condition a n d u.v. light sources. D e v e l o p m e n t ,
WORLD baking, etching and techniques.
Metallization
ABSTRACTS
ON MICROELECTRONICS
washing, photoresist removal
systems
for integrated
circuits.
R. W. WILSON and L. E. TERRY. Proc. Teeh. Prog. I N T E R / N E P O N 1970, Brighton, 13-15 October (1970), p. VIII-1. A metallization system must satisfy certain conditions if it is to be used in the fabrication of semiconductor devices. These conditions or constraints are as follows : A. The material should have a high conductivity (0 < 1 0 ~ n/era). B. It should have good adhesion to both the semiconductor material and to thermally grown or deposited dielectric films. C. The metal or metals should be free from degrading
ington D.C., U.S.A., 10-12 May (1971), p. 408. The Meteorological Data Sounding System measures the meteorological characteristics of the atmosphere. The $254 is the transmitter that was designed for this system to transmit the temperature and relative humidity data to the ground station from a balloon-borne payload during the ascent and descent. The transmitter consists of three major sections : the modulator/voltage regulator, the oscillator and antenna. The described transmitter delivers a minimum of 50 m W over the --70 ° to +70°C temperature range while the input voltage is varied between 30 and 20V. The transfer characteristic (resistance as a function of frequency) of the modulator is accurate enough to permit the determination of atmospheric temperature to within one-half a degree.
Microprogramming m a d e e a s y - - w i t h a 4,096-bit bipolar ROM. S. SIRKIN. Electronics, 15 March (1971), p. 64. Complex digital systems need complex, expensive control systems; but the latest bipolar processing techniques have produced a fast ROM that's large enough for the job and can save about $100 per device used.
The effects of in-process heating on K1200 monolithic multilayer capacitors. R. F. TINDALL. Proc. Tech. Prog. I N T E R / N E P C O N 1970, Brighton, 13-15 October (1970), p. VI-46. It is well known that while ceramic capacitors are among the most reliable components available, the high K types do exhibit considerable capacitance variations with temperature and time. The result of these variations is that it is difficult for the user to predict the capacitance value of a K1200 capacitor after a temperature change has occurred, either during processing of the circuit or during the life of the capacitor, to any precision better than, say ~ 1 0 per cent. This paper describes a series of exploratory experiments in which an attempt has been made to evaluate the changes in capacitance experienced by K1200 chip capacitors as a result of heating, and the
419
intermetallie compounds not only between metal films, but between the metal and the semiconductor. D. Should make a good low ohmic contact to both p and n type siiicon. E. Amenable to practical production methods of deposition and delineation. F. Resistant to current-induced electro-migration. G. Resistant to electro-chemical corrosion. H. The deposition of the metal or metals must not introduce surface instabilities in the semiconductor material. I.
6. M I C R O E L E C T R O N I C S - - C O M P O N E N T S , A hybrid thin-film radiosonde transmitter. R. E. ASKEW. Proc. 21st Electronic Components Conf., Wash-
AND RELIABILITY
The metallization system must be compatible with LSI arrays involving multilayer interconnection processing.
SYSTEMS AND EQUIPMENTS
subsequent recovery from heating. It is hoped that these results will enable the user to predict with a fair degree of certainty, the behaviour of these capacitors.
Capacitors in m i c r o w a v e integrated circuits. H. KATOH. Trans. Inst. Elec. Comm. Engrs Japan 54-B, No. 3, March (1971), p. 95. (In Japanese.) An expression for the complex impedance of thin film capacitors whose electrodes come in from opposite sides has been derived, including the distributed resistive and inductive effect of the electrode. The result indicates that at microwave frequencies the resistance and reactance of capacitors are due mainly to that of the electrodes. Furthermore, the loss factor of such capacitors as Tantalum thin film capacitors, SiO thin film capacitors and ceramic chip capacitors was confirmed experimentally by measuring the change in Q of a strip-line resonant system with the addition of them.
The use of passive chip components in hybrid integrated circuits. D. W. HAMER. Pro& 21st Electronic Components Conf., Washington D.C., U.S.A., 10-12 May (1971), p. 27. This paper looks at the various reasons a hybrid integrated circuit manufacturer would have for using passive chip components in his designs, rather than using thick or thin integrated circuit technology for fabrication of these elements. Emphasis in this analysis is placed on resistors and capacitors (rather than all types of discrete components) and on chips (rather than on minicomponents and other leaded devices).
MOSFETS rejuvenate old design for CATV broadband amplifiers. D. V. LEE. Electronics, 15 March (1971), p. 72. The large dynamic range and low crossmodulation distortion of low-cost ~[OSFETs, plus a distributed-amplifier configuration, can provide a highlevel output suitable for v.h.f, coverage.
The m e a s u r e m e n t of linear circuits with a computer-operated system. G. MILLER. Proc. Tech.