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Charge neutrality in semiconductors with implanted impurity profiles
424
WORLD
ABSTRACTS
ON
MICROELECTRONICS
Computer controlled batch process manufacture o f thin f i l m resistor n e t w o r k s on c e r a m i c substrates. C. H. BOYD. Proc. 21st Electronic Components Conf., W a s h i n g t o n D . C . , U . S . A . , 10-12 M a y (1971), p. 91. A c o m p u t e r controlled b a t c h process for t h e m a n u f a c t u r e of h i g h reliability t h i n film resistor net-
AND
RELIABILITY
works on ceramic substrates has been developed a n d placed in p r o d u c t i o n at t h e W e s t e r n Electric m a n u f a c t u r i n g facility in V f i n s t o n - S a l e m , N.C. T h i s facility was developed to p r o d u c e h i g h reliability thin tihn networks on ceramic s u b s t r a t e s for use in Military Appli.cations.
9. ELECTRON, ION AND LASER BEAMS L a s e r r e s i s t a n c e t r i m m i n g f r o m the m e a s u r e m e n t point o f v i e w . A. G. ALBIN and E. J. SWENSON. Proc. 21st Electronic Components Conf., W a s h i n g t o n D.C., U . S . A . 10-12 M a y (1971), p. 38. T h e laser, as a resistor t r i m m i n g tool h a s exciting n e w speed capabilities. T h e s e greater capabilities d e m a n d , in turn, c o r r e s p o n d i n g i m p r o v e m e n t in the speed a n d accuracy of the controlling m e a s u r e m e n t system, a basic s y s t e m h a s been developed for laser t r i m m i n g of b o t h thick a n d t h i n fihn resistors. T h i s s y s t e m c o m b i n e s a laser, resistance scanner, prog r a m m a b l e laser optics a n d a m i n i c o m p u t e r to form a complete t r i m m i n g system. T h i s s y s t e m t r i m s t h e complete range of c o m p o n e n t s f r o m low accuracy thick films to very h i g h precision t h i n film networks. However, t h e speed vs. accuracy limitations require s t u d y a n d optimization of t h e complete s y s t e m . Particular care is required in t h e following m e a s u r e m e n t areas: (1) l,ead a n d contact resistance. (2) Leakage resistance. (3) l a n e f r e q u e n c y pickup. (4) Stray d.c. signals s u c h as t h e r m a l e.m.f.'s a n d zero offsets. (5) T r a n s i e n t effects while the laser is t r i m m i n g . M e t h o d s to a c c o m p l i s h optimization include three- a n d f o u r - t e r m i n a l t e c h n i q u e s to reduce errors of lead, contact a n d leakage resistance; dual-slope integration to s u p p r e s s line f r e q u e n c y pickup, a u t o m a t i c zero-setting to m i n i m i z e effects of stray d.c. signals a n d L s h a p e cuts based on deviation. I n lower-accuracy applications, a c o n t i n u o u s track m o d e of m e a s u r e m e n t d u r i n g t h e t r i m m i n g operation can be used. At h i g h e r accuracies, t r a n s i e n t effects require a longer m e a s u r e m e n t cycle a n d a m e a s u r e - p r e d i c t - t r i m m o d e of operation.
C h a r g e n e u t r a l i t y in s e m i c o n d u c t o r s w i t h i m p l a n t e d i m p u r i t y profiles. J. A. GRIMSHAW a n d D. N. OSBORNE. Solid St. Electron. 14 (1971), p. 603. T h e c i r c u m s t a n c e s for w h i c h failure of t h e condition of charge neutrality is likely to be a feature of s e m i c o n d u c t o r s i m p l a n t e d with d o p a n t ions is discussed. Calculations are m a d e of i m p l a n t a t i o n doses as a f u n c tion of energy for five d o p a n t ion species in silicon w h e n the condition will fail over t h e whole or part of t h e profile, a s s u m e d G a u s s i a n , a n d also w h e n it will hold over that part of t h e profile w i t h i n one s t a n d a r d deviation of t h e G a u s s i a n peak. T h e extent of p e n e t r a t i o n of a j u n c t i o n field into a G a u s s i a n profile is considered, a n d a lower limit to i m p l a n t a t i o n doses calculated to enable s u c h a profile to be conveniently investigated b y differential capacitance-with-bias m e a s u r e m e n t s . T h e dose limits for the different criteria are c o m p a r e d , a n d t h e cases w h e n profiles d e d u c e d f r o m t h e capacitance m e a s u r e m e n t s will n e e d correction are pointed out.
T h i n film l a s e r m a c h i n i n g . M. V~. llor)x'am Proc. 21st Electronic Components Conf., \ V a s h i n g t o n I ) . C , i..S.A., 10-12 M a y (1971), p. 74. F o r the past several ",ears, the A l l e n t o w n W o r k s of t h e W e s t e r n Electric C o m p a n y has been u s i n g a n e o d y m i u m doped y t t r i u m a l u m i n u m garnet ( N d : Y A G ) laser m a c h i n i n g s y s t e m to assist m the m a n u f a c t u r e of thin fihn inteeratcd circuits. T h i s e q u i p m e n t has served primarily as :~ tool for repairing improperly m a d e circuits a n d circuits that ha\'c been d a m a g e d d u r i n g processing. Recently, the use of t h ( m a c h i n i n g s y s t e m has been extended for d e v e l o p m e n t m o d e l s to generation of c o m p l e x gold c o n d u c t o r networks w h i c h interconnect large numl)ers of silicon integrated circuits. I n addition to discussing both of the above applications, this p a p e r describes the }asci m a c h i n i n g s y s t e m a n d a few of the safety features tha~ have been designed into t h e m a c h i n e
S c a n n i n g e l e c t r o n m i c r o s c o p y s t u d i e s on s w i t c h i n g lateral transistors in i n t e g r a t e d circuits. J. I ) LAST and D. W. LucAs. Solid St. Electron. 14 (1!)71), p. 481. A s w i t c h i n g p h e n o m e n o n has bccn ohservcd m certain lateral g e o m e t r y transistors il, silicon inte~,,rated circuits and reported. T h e s e devices switch b~:twecn c o n d u c t i n g and n o n - c o n d u c t i n g statc.~ and a hypothesis has been p r o p o s e d to explain the mechanisnl. It has been s u g g e s t e d that t h e extension of the collector depletion region within t h e epitaxial layer increases the resistance of run' c a u s i n g this effect. T h i s paper dcacribes the use ,,f a s c a n n i n g electron miscroscope in the charge collection m o d e to m a p t h e positions of the depletion layers at different bias voltages. Detailed examination <,f the m i c r o g r a p h s has confirmed t h e proposed the~:.' and has revealed u n e x p e c t e d information ahout the '.
Electron b e a m s s h i n e on IC layouts. 1~ t:t:J~Ra,\-
Electronics, 21 J u n e (1971), p. 83~ S e m i c o n d u c t o r designers look to s c a n n i n g electron miscroscopes tied t,, c o m p u t e r for resolution a n d colltlTol n c c d e d for ¢]enser a n d h i g h e r - f r e q u e n c y devices. T e s t i n g i n t e g r a t e d c i r c u i t s w i t h a laser b e a m . R. E. McMAHON. Proc. 21st Electronic Components Con/., W a s h i n g t o n D . C . , U . S . A . , 10-12 M a y (1971), p. 412. A laser s c a n n e r s y s t e m is described w h i c h h a s been developed for integrated circuit testing. T h e s y s t e m has been u s e d for structural fault detection and electrical evaluation of internal devices as well. I n m o s t cases electrical contact to t h e chip is required only on the p o w e r a n d g r o u n d pads.
WORLD
ABSTRACTS
ON
MICROELECTRONICS
Computer controlled batch process manufacture o f thin f i l m resistor n e t w o r k s on c e r a m i c substrates. C. H. BOYD. Proc. 21st Electronic Components Conf., W a s h i n g t o n D . C . , U . S . A . , 10-12 M a y (1971), p. 91. A c o m p u t e r controlled b a t c h process for t h e m a n u f a c t u r e of h i g h reliability t h i n film resistor net-
AND
RELIABILITY
works on ceramic substrates has been developed a n d placed in p r o d u c t i o n at t h e W e s t e r n Electric m a n u f a c t u r i n g facility in V f i n s t o n - S a l e m , N.C. T h i s facility was developed to p r o d u c e h i g h reliability thin tihn networks on ceramic s u b s t r a t e s for use in Military Appli.cations.
9. ELECTRON, ION AND LASER BEAMS L a s e r r e s i s t a n c e t r i m m i n g f r o m the m e a s u r e m e n t point o f v i e w . A. G. ALBIN and E. J. SWENSON. Proc. 21st Electronic Components Conf., W a s h i n g t o n D.C., U . S . A . 10-12 M a y (1971), p. 38. T h e laser, as a resistor t r i m m i n g tool h a s exciting n e w speed capabilities. T h e s e greater capabilities d e m a n d , in turn, c o r r e s p o n d i n g i m p r o v e m e n t in the speed a n d accuracy of the controlling m e a s u r e m e n t system, a basic s y s t e m h a s been developed for laser t r i m m i n g of b o t h thick a n d t h i n fihn resistors. T h i s s y s t e m c o m b i n e s a laser, resistance scanner, prog r a m m a b l e laser optics a n d a m i n i c o m p u t e r to form a complete t r i m m i n g system. T h i s s y s t e m t r i m s t h e complete range of c o m p o n e n t s f r o m low accuracy thick films to very h i g h precision t h i n film networks. However, t h e speed vs. accuracy limitations require s t u d y a n d optimization of t h e complete s y s t e m . Particular care is required in t h e following m e a s u r e m e n t areas: (1) l,ead a n d contact resistance. (2) Leakage resistance. (3) l a n e f r e q u e n c y pickup. (4) Stray d.c. signals s u c h as t h e r m a l e.m.f.'s a n d zero offsets. (5) T r a n s i e n t effects while the laser is t r i m m i n g . M e t h o d s to a c c o m p l i s h optimization include three- a n d f o u r - t e r m i n a l t e c h n i q u e s to reduce errors of lead, contact a n d leakage resistance; dual-slope integration to s u p p r e s s line f r e q u e n c y pickup, a u t o m a t i c zero-setting to m i n i m i z e effects of stray d.c. signals a n d L s h a p e cuts based on deviation. I n lower-accuracy applications, a c o n t i n u o u s track m o d e of m e a s u r e m e n t d u r i n g t h e t r i m m i n g operation can be used. At h i g h e r accuracies, t r a n s i e n t effects require a longer m e a s u r e m e n t cycle a n d a m e a s u r e - p r e d i c t - t r i m m o d e of operation.
C h a r g e n e u t r a l i t y in s e m i c o n d u c t o r s w i t h i m p l a n t e d i m p u r i t y profiles. J. A. GRIMSHAW a n d D. N. OSBORNE. Solid St. Electron. 14 (1971), p. 603. T h e c i r c u m s t a n c e s for w h i c h failure of t h e condition of charge neutrality is likely to be a feature of s e m i c o n d u c t o r s i m p l a n t e d with d o p a n t ions is discussed. Calculations are m a d e of i m p l a n t a t i o n doses as a f u n c tion of energy for five d o p a n t ion species in silicon w h e n the condition will fail over t h e whole or part of t h e profile, a s s u m e d G a u s s i a n , a n d also w h e n it will hold over that part of t h e profile w i t h i n one s t a n d a r d deviation of t h e G a u s s i a n peak. T h e extent of p e n e t r a t i o n of a j u n c t i o n field into a G a u s s i a n profile is considered, a n d a lower limit to i m p l a n t a t i o n doses calculated to enable s u c h a profile to be conveniently investigated b y differential capacitance-with-bias m e a s u r e m e n t s . T h e dose limits for the different criteria are c o m p a r e d , a n d t h e cases w h e n profiles d e d u c e d f r o m t h e capacitance m e a s u r e m e n t s will n e e d correction are pointed out.
T h i n film l a s e r m a c h i n i n g . M. V~. llor)x'am Proc. 21st Electronic Components Conf., \ V a s h i n g t o n I ) . C , i..S.A., 10-12 M a y (1971), p. 74. F o r the past several ",ears, the A l l e n t o w n W o r k s of t h e W e s t e r n Electric C o m p a n y has been u s i n g a n e o d y m i u m doped y t t r i u m a l u m i n u m garnet ( N d : Y A G ) laser m a c h i n i n g s y s t e m to assist m the m a n u f a c t u r e of thin fihn inteeratcd circuits. T h i s e q u i p m e n t has served primarily as :~ tool for repairing improperly m a d e circuits a n d circuits that ha\'c been d a m a g e d d u r i n g processing. Recently, the use of t h ( m a c h i n i n g s y s t e m has been extended for d e v e l o p m e n t m o d e l s to generation of c o m p l e x gold c o n d u c t o r networks w h i c h interconnect large numl)ers of silicon integrated circuits. I n addition to discussing both of the above applications, this p a p e r describes the }asci m a c h i n i n g s y s t e m a n d a few of the safety features tha~ have been designed into t h e m a c h i n e
S c a n n i n g e l e c t r o n m i c r o s c o p y s t u d i e s on s w i t c h i n g lateral transistors in i n t e g r a t e d circuits. J. I ) LAST and D. W. LucAs. Solid St. Electron. 14 (1!)71), p. 481. A s w i t c h i n g p h e n o m e n o n has bccn ohservcd m certain lateral g e o m e t r y transistors il, silicon inte~,,rated circuits and reported. T h e s e devices switch b~:twecn c o n d u c t i n g and n o n - c o n d u c t i n g statc.~ and a hypothesis has been p r o p o s e d to explain the mechanisnl. It has been s u g g e s t e d that t h e extension of the collector depletion region within t h e epitaxial layer increases the resistance of run' c a u s i n g this effect. T h i s paper dcacribes the use ,,f a s c a n n i n g electron miscroscope in the charge collection m o d e to m a p t h e positions of the depletion layers at different bias voltages. Detailed examination <,f the m i c r o g r a p h s has confirmed t h e proposed the~:.' and has revealed u n e x p e c t e d information ahout the '.
Electron b e a m s s h i n e on IC layouts. 1~ t:t:J~Ra,\-
Electronics, 21 J u n e (1971), p. 83~ S e m i c o n d u c t o r designers look to s c a n n i n g electron miscroscopes tied t,, c o m p u t e r for resolution a n d colltlTol n c c d e d for ¢]enser a n d h i g h e r - f r e q u e n c y devices. T e s t i n g i n t e g r a t e d c i r c u i t s w i t h a laser b e a m . R. E. McMAHON. Proc. 21st Electronic Components Con/., W a s h i n g t o n D . C . , U . S . A . , 10-12 M a y (1971), p. 412. A laser s c a n n e r s y s t e m is described w h i c h h a s been developed for integrated circuit testing. T h e s y s t e m has been u s e d for structural fault detection and electrical evaluation of internal devices as well. I n m o s t cases electrical contact to t h e chip is required only on the p o w e r a n d g r o u n d pads.