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676. Cathodic sputtering of tantalum and tungsten at various temperatures
Classified abstracts 672--685 CaF2, p r o v i d e d the t e m p e r a t u r e o f the s u b s t r a t e did n o t fall below 375 °C d u r i n g deposition. C W Chen and S Zeitman, TApp Phy, 36 (2), Feb 1965, 669-670. 30:56
672. Microcircuit Britain)
production:
design
and
economics.
(Great
Russian).
T h i s p a p e r e x a m i n e s t h e effect o f design factors on m a n u f a c t u r i n g costs o f thin-film integrated circuits. T h e a u t h o r first reviews the choice o f sheet resistance, a n d h e n c e of size a n d aspect ratio, for the best l o n g - t e r m stability, lowest t e m p e r a t u r e coefficient, a n d m a x i m u m p r o d u c t i o n yield o f thin-film r e s i s t o r s a n d c o n d u c t o r s . F o u r values r a n g i n g f r o m 10 to 200 o h m s per s q u a r e are s u g g e s t e d as c o n v e n i e n t for resistors, t h o u g h wherever possible a given microcircuit s h o u l d be m a d e f r o m only o n e resistance of film. T h e m a x i m u m resistor v a l u e a t t a i n a b l e t h e n d e p e n d s on t h e area available a n d t h e m i n i m u m attainable t r a c k width. F o r 1 per cent variations d u e to edge definition errors, t h e width s h o u l d n o t be less t h a n 0 . 0 2 i n . with t h e best p h o t o p i t h o g r a p h i c m a s k i n g technique, w h e n 100 k i l o h m requires a n area of 0.064 in. 2. W i t h low-value resistors, the m a i n difficulty is d u e to the resistance of the c o n n e x i o n s a n d especially to their t e m p e r a t u r e coefficient, w h i c h m a y be m u c h worse t h a n t h a t of the resistance alloy. A . c h a r t is given s h o w i n g the sheet resistance w h i c h s h o u l d be c h o s e n for v a r i o u s m a x i m u m a n d m i n i m u m resistance values. F o r m o s t cases, 100 o h m s per s q u a r e is seen to be suitable. T h e p o w e r dissipation per unit area of s u b s t r a t e d e p e n d s o n the fraction covered by the film, a n d o n the stability required. F o r e x a m p l e , 0.5 W / i n . 2 with an a m b i e n t t e m p e r a t u r e o f 7 0 ° C will give better t h a n 0.1 per cent per 1000 hr. F o r m u l a e for calculating t h e area a n d width of t r a c k needed, given t h e permissible film loading, are q u o t e d . F o r capacitors, the starting p o i n t is t h e dielectric t h i c k n e s s n e e d e d to withs t a n d the test voltage. W i t h silicon dioxide, the t h i c k n e s s is selected f r o m a s m a l l r a n g e of values within the r a n g e 2500 to 5 0 0 0 - \ , yielding c a p a c i t a n c e s o f 90,000 to 45,000 p F / i n . 2. T h e m i n i m u m c a p a c i t a n c e w i t h o u t excessive tolerance d u e to p o o r edge definition o f t h e plates is a b o u t 90 p F (at 20-V working). T h e a d d i t i o n o f t r a n s i s t o r s a n d diodes is considered best d o n e by soldering to term i n a l s after a s s e m b l y h a s been lacquered a n d tested. It is p o i n t e d o u t t h a t a c o n s i d e r a b l e e c o n o m y w o u l d be possible if the semic o n d u c t o r dice c o u l d be a t t a c h e d directly to the microcircuit i n s t e a d o f being built into a can. In a d i s c u s s i o n o f the o p t i m u m size o f microcircuit, t h e a u t h o r p o i n t s o u t t h a t r e d u c t i o n in size c h e a p e n s the cost o f deposition, b u t increases the o p e r a t i n g t e m p e r a t u r e a n d hence reduces the reliability. A s s e m b l y costs are also increased if the e l e m e n t s are t o o small. G France, Electronic Equipment News, 6, April 1965, 82 88. 30 : 56 673. A modified representation for thin-film triodes. ( G r e a t Britain) D Abraham and T O Poehler, Proc IEEE, 52, April 1964, p 416. 30 : 33 : 41
674. Nail-effect studies in deposited CdS thin films. (Great Britain) R S Muller and B G Watkins, Proc IEEE, 52, April 1964, 425-426. 30 : 37
675. Investigation of the rate of evaporation of heat resisting alloys in a vacuum. (USSR) H e a t resisting alloys o f c h r o m i u m - nickel a n d c h r o m i u m - nickel t i t a n i u m were h e a t e d in a v a c u u m of 10 -7 torr a n d their loss o f weight d e t e r m i n e d over t h e t e m p e r a t u r e r a n g e 980 ° to 1185°C. T h e practical limiting t e m p e r a t u r e for t h e s e alloys is 1100°C. At this t e m p e r a t u r e a plate 5 m m thick loses 20 per cent o f its t h i c k n e s s in 4000 h o u r s . A similar loss is experienced in 2350 h o u r s if the t e m p e r a t u r e is raised to 1200°C. F o r s h o r t - t i m e operatives a t e m p e r a t u r e o f 1250°C is r e g a r d e d as j u s t permissible, w h e r e a s 1300 °C leads to a n e x t r e m e l y s h o r t life. Since all t h e alloys e x a m i n e d e v a p o r a t e d to a noticeable extent u n d e r w o r k i n g c o n d i t i o n s , t h e effect o f v a p o u r deposits o n the i n s u l a t i n g m a t e r i a l s u s e d in v a c u u m f u r n a c e s s h o u l d be t a k e n into a c c o u n t . E N M a r m e r et al, Investigation in the field of industrial electro heating, " VNIIETO", 1965, p 249, (in Russian). 30 : 41
676. Cathodic sputtering of tantalum and tungsten at various temperatures. ( USSR) T h e c a t h o d i c s p u t t e r i n g o f t a n t a l u m a n d t u n g s t e n by the alkaline e l e m e n t s w a s s t u d i e d by u s i n g the radioactive m e t h o d for r e c o r d i n g the q u a n t i t y o f m a t e r i a l transferred. p e r a t u r e TK is defined, w h i c h t h e ion target m u s t h a v e a s
384
m u m value to e n s u r e s p u t t e r i n g o f p u r e metal. F o r t u n g s t e n , TK = 1500°K; f o r - t a n t a l u m the figure is 1800°K. If the target t e m p e r a t u r e is below TK, t h e material transferred in c o n t a m i n a t i o n with a b s o r b e d g a s . V A Shustrov, Radio Eng & Electronic, 10 (3), 1965, p 541 (in
ions o f isotope A tema mini-
30 : 41
677. On the durability o f nickel and iron films obtained by condensation in vacuum. ( U S S R ) I r o n a n d nickel films are o f great interest since t h e y (or their alloys) are widely u s e d in micro-electronic circuits, c o m p u t e r s etc. T h e a u t h o r e x a m i n e d b o t h m a x i m u m load stress a n d m i c r o - h a r d n e s s o f s u c h films deposited on s u b s t r a t e s at v a r i o u s t e m p e r a t u r e s , it a p p e a r s t h a t best results f r o m a s t r e n g t h p o i n t o f view are o b t a i n e d if t h e s u b s t r a t e t e m p e r a t u r e does n o t exceed 210 o to 250 ~C. Nickel films, in c o n t r a s t to c o p p e r or silver films, are characterized by r e m a r k a b l e stability o f their s t r e n g t h properties at r o o m t e m p e r a ture. L S P a l a t n i k et al, Fiz Metallov i Metallovedenic, 19 (2), 1965,
.~10, (in Russian). 30:41
678. Epitaxial growth of silver and gold films by sputtering. Britain)
(Great
T h e films were deposited by s p u t t e r i n g in a n a r g o n discharge by u s i n g rock salt at r o o m t e m p e r a t u r e for t h e substrate. T h e films after stripping were e x a m i n e d by electron diffraction a n d t r a n s m i s s i o n electron m i c r o s c o p y . C o n d i t i o n s for epitaxial g r o w t h differ f r o m t h o s e f o u n d to h o l d for e v a p o r a t e d films. F u r t h e r investigation will be required to d e t e r m i n e r e a s o n for this. D S C~.mpbell and D T Shirland, Phil Mag, 9, April 1964, 703-707. 30
679. Application of low energy sputtering for thin film deposition. (USA) T h e deposition of film by low-energy s p u t t e r i n g was e x a m i n e d with special reference to control of deposition rate. It a p p e a r s that the n e w t e c h n i q u e h a s s o m e a d v a n t a g e over n o r m a l s p u t t e r i n g for controlled thin-film deposition. T W Nickerson and R Moseson, Semiconductor Prod Solid State
Technol, 7 (12), Dec 1964, 33-36. 30 : 22
680. Efficient low pressure sputtering in a large inverted magnetron suitable for film synthesis. (USA) T h e s p u t t e r i n g characteristics of a 10 c m d i a m e t e r inverted m a g n e t r o n were investigated in the transitive region f r o m positive to negative space-charge m o d e s . T h e f o r m e r resulted in the m o s t efficient t r a n s p o r t of s p u t t e r e d material f r o m c a t h o d e to anode. T h e deposition profile at the a n o d e s h o w e d that sputtering was u n i f o r m over the effective c a t h o d e area. It a p p e a r s that satisfactory o p e r a t i o n in the 10 5 torr r a n g e c a n be expected for a 4 0 c m d i a m e t e r configuration. W D Gill and E Kay, Rev Sci Instrum, 36 (3), March 1965, 27~282. 30:41 681. Exploding metal films. (USA) V a c u u m e v a p o r a t e d films of AI, Sn, Cu, Ni a n d Fe on glass a n d plexiglass were electrically e x p l o d e d at energy levels in the r a n g e 1 to 10 J. C u r r e n t a n d voltage m e a s u r e m e n t , as well as high-speed c i n e m a p h o t o g r a p h s of the process, are presented. Ca J Woffinden, Exploding Wires, Volume 3, New York, Plenum
Press, 1964, pp 193-210. 30:41
682. Field emission microscopy of silver nucleation and epitaxial growth on tungsten. (USA) T h e t e c h n i q u e u s e d for o b t a i n i n g clean silver surfaces by epitaxial g r o w t h on t u n g s t e n f r o m the v a p o u r is described. T h e article is well illustrated a n d epitaxial relationships are discussed in detail. A F Melmed and R F M c C a r t h y , J Chem Phys, 42 (4), Jan 1965,
1466-1468. 30 : 16 : 33
683. Diffusion of impurities during epitaxy. (Great Britain) W Rice, Proc IEEE, 52, March 1964, 284-295. 30 : 41
684= Large vacuum metallising plant. (Great Britain) Anon, Engineer, 219 (5692), Feb 1965, 401. 30 : 41 6 8 5 . Vacuum metallising plant. (Great Britain) A n o n , Engineer, 219 (5697), April 1965, 613.
672. Microcircuit Britain)
production:
design
and
economics.
(Great
Russian).
T h i s p a p e r e x a m i n e s t h e effect o f design factors on m a n u f a c t u r i n g costs o f thin-film integrated circuits. T h e a u t h o r first reviews the choice o f sheet resistance, a n d h e n c e of size a n d aspect ratio, for the best l o n g - t e r m stability, lowest t e m p e r a t u r e coefficient, a n d m a x i m u m p r o d u c t i o n yield o f thin-film r e s i s t o r s a n d c o n d u c t o r s . F o u r values r a n g i n g f r o m 10 to 200 o h m s per s q u a r e are s u g g e s t e d as c o n v e n i e n t for resistors, t h o u g h wherever possible a given microcircuit s h o u l d be m a d e f r o m only o n e resistance of film. T h e m a x i m u m resistor v a l u e a t t a i n a b l e t h e n d e p e n d s on t h e area available a n d t h e m i n i m u m attainable t r a c k width. F o r 1 per cent variations d u e to edge definition errors, t h e width s h o u l d n o t be less t h a n 0 . 0 2 i n . with t h e best p h o t o p i t h o g r a p h i c m a s k i n g technique, w h e n 100 k i l o h m requires a n area of 0.064 in. 2. W i t h low-value resistors, the m a i n difficulty is d u e to the resistance of the c o n n e x i o n s a n d especially to their t e m p e r a t u r e coefficient, w h i c h m a y be m u c h worse t h a n t h a t of the resistance alloy. A . c h a r t is given s h o w i n g the sheet resistance w h i c h s h o u l d be c h o s e n for v a r i o u s m a x i m u m a n d m i n i m u m resistance values. F o r m o s t cases, 100 o h m s per s q u a r e is seen to be suitable. T h e p o w e r dissipation per unit area of s u b s t r a t e d e p e n d s o n the fraction covered by the film, a n d o n the stability required. F o r e x a m p l e , 0.5 W / i n . 2 with an a m b i e n t t e m p e r a t u r e o f 7 0 ° C will give better t h a n 0.1 per cent per 1000 hr. F o r m u l a e for calculating t h e area a n d width of t r a c k needed, given t h e permissible film loading, are q u o t e d . F o r capacitors, the starting p o i n t is t h e dielectric t h i c k n e s s n e e d e d to withs t a n d the test voltage. W i t h silicon dioxide, the t h i c k n e s s is selected f r o m a s m a l l r a n g e of values within the r a n g e 2500 to 5 0 0 0 - \ , yielding c a p a c i t a n c e s o f 90,000 to 45,000 p F / i n . 2. T h e m i n i m u m c a p a c i t a n c e w i t h o u t excessive tolerance d u e to p o o r edge definition o f t h e plates is a b o u t 90 p F (at 20-V working). T h e a d d i t i o n o f t r a n s i s t o r s a n d diodes is considered best d o n e by soldering to term i n a l s after a s s e m b l y h a s been lacquered a n d tested. It is p o i n t e d o u t t h a t a c o n s i d e r a b l e e c o n o m y w o u l d be possible if the semic o n d u c t o r dice c o u l d be a t t a c h e d directly to the microcircuit i n s t e a d o f being built into a can. In a d i s c u s s i o n o f the o p t i m u m size o f microcircuit, t h e a u t h o r p o i n t s o u t t h a t r e d u c t i o n in size c h e a p e n s the cost o f deposition, b u t increases the o p e r a t i n g t e m p e r a t u r e a n d hence reduces the reliability. A s s e m b l y costs are also increased if the e l e m e n t s are t o o small. G France, Electronic Equipment News, 6, April 1965, 82 88. 30 : 56 673. A modified representation for thin-film triodes. ( G r e a t Britain) D Abraham and T O Poehler, Proc IEEE, 52, April 1964, p 416. 30 : 33 : 41
674. Nail-effect studies in deposited CdS thin films. (Great Britain) R S Muller and B G Watkins, Proc IEEE, 52, April 1964, 425-426. 30 : 37
675. Investigation of the rate of evaporation of heat resisting alloys in a vacuum. (USSR) H e a t resisting alloys o f c h r o m i u m - nickel a n d c h r o m i u m - nickel t i t a n i u m were h e a t e d in a v a c u u m of 10 -7 torr a n d their loss o f weight d e t e r m i n e d over t h e t e m p e r a t u r e r a n g e 980 ° to 1185°C. T h e practical limiting t e m p e r a t u r e for t h e s e alloys is 1100°C. At this t e m p e r a t u r e a plate 5 m m thick loses 20 per cent o f its t h i c k n e s s in 4000 h o u r s . A similar loss is experienced in 2350 h o u r s if the t e m p e r a t u r e is raised to 1200°C. F o r s h o r t - t i m e operatives a t e m p e r a t u r e o f 1250°C is r e g a r d e d as j u s t permissible, w h e r e a s 1300 °C leads to a n e x t r e m e l y s h o r t life. Since all t h e alloys e x a m i n e d e v a p o r a t e d to a noticeable extent u n d e r w o r k i n g c o n d i t i o n s , t h e effect o f v a p o u r deposits o n the i n s u l a t i n g m a t e r i a l s u s e d in v a c u u m f u r n a c e s s h o u l d be t a k e n into a c c o u n t . E N M a r m e r et al, Investigation in the field of industrial electro heating, " VNIIETO", 1965, p 249, (in Russian). 30 : 41
676. Cathodic sputtering of tantalum and tungsten at various temperatures. ( USSR) T h e c a t h o d i c s p u t t e r i n g o f t a n t a l u m a n d t u n g s t e n by the alkaline e l e m e n t s w a s s t u d i e d by u s i n g the radioactive m e t h o d for r e c o r d i n g the q u a n t i t y o f m a t e r i a l transferred. p e r a t u r e TK is defined, w h i c h t h e ion target m u s t h a v e a s
384
m u m value to e n s u r e s p u t t e r i n g o f p u r e metal. F o r t u n g s t e n , TK = 1500°K; f o r - t a n t a l u m the figure is 1800°K. If the target t e m p e r a t u r e is below TK, t h e material transferred in c o n t a m i n a t i o n with a b s o r b e d g a s . V A Shustrov, Radio Eng & Electronic, 10 (3), 1965, p 541 (in
ions o f isotope A tema mini-
30 : 41
677. On the durability o f nickel and iron films obtained by condensation in vacuum. ( U S S R ) I r o n a n d nickel films are o f great interest since t h e y (or their alloys) are widely u s e d in micro-electronic circuits, c o m p u t e r s etc. T h e a u t h o r e x a m i n e d b o t h m a x i m u m load stress a n d m i c r o - h a r d n e s s o f s u c h films deposited on s u b s t r a t e s at v a r i o u s t e m p e r a t u r e s , it a p p e a r s t h a t best results f r o m a s t r e n g t h p o i n t o f view are o b t a i n e d if t h e s u b s t r a t e t e m p e r a t u r e does n o t exceed 210 o to 250 ~C. Nickel films, in c o n t r a s t to c o p p e r or silver films, are characterized by r e m a r k a b l e stability o f their s t r e n g t h properties at r o o m t e m p e r a ture. L S P a l a t n i k et al, Fiz Metallov i Metallovedenic, 19 (2), 1965,
.~10, (in Russian). 30:41
678. Epitaxial growth of silver and gold films by sputtering. Britain)
(Great
T h e films were deposited by s p u t t e r i n g in a n a r g o n discharge by u s i n g rock salt at r o o m t e m p e r a t u r e for t h e substrate. T h e films after stripping were e x a m i n e d by electron diffraction a n d t r a n s m i s s i o n electron m i c r o s c o p y . C o n d i t i o n s for epitaxial g r o w t h differ f r o m t h o s e f o u n d to h o l d for e v a p o r a t e d films. F u r t h e r investigation will be required to d e t e r m i n e r e a s o n for this. D S C~.mpbell and D T Shirland, Phil Mag, 9, April 1964, 703-707. 30
679. Application of low energy sputtering for thin film deposition. (USA) T h e deposition of film by low-energy s p u t t e r i n g was e x a m i n e d with special reference to control of deposition rate. It a p p e a r s that the n e w t e c h n i q u e h a s s o m e a d v a n t a g e over n o r m a l s p u t t e r i n g for controlled thin-film deposition. T W Nickerson and R Moseson, Semiconductor Prod Solid State
Technol, 7 (12), Dec 1964, 33-36. 30 : 22
680. Efficient low pressure sputtering in a large inverted magnetron suitable for film synthesis. (USA) T h e s p u t t e r i n g characteristics of a 10 c m d i a m e t e r inverted m a g n e t r o n were investigated in the transitive region f r o m positive to negative space-charge m o d e s . T h e f o r m e r resulted in the m o s t efficient t r a n s p o r t of s p u t t e r e d material f r o m c a t h o d e to anode. T h e deposition profile at the a n o d e s h o w e d that sputtering was u n i f o r m over the effective c a t h o d e area. It a p p e a r s that satisfactory o p e r a t i o n in the 10 5 torr r a n g e c a n be expected for a 4 0 c m d i a m e t e r configuration. W D Gill and E Kay, Rev Sci Instrum, 36 (3), March 1965, 27~282. 30:41 681. Exploding metal films. (USA) V a c u u m e v a p o r a t e d films of AI, Sn, Cu, Ni a n d Fe on glass a n d plexiglass were electrically e x p l o d e d at energy levels in the r a n g e 1 to 10 J. C u r r e n t a n d voltage m e a s u r e m e n t , as well as high-speed c i n e m a p h o t o g r a p h s of the process, are presented. Ca J Woffinden, Exploding Wires, Volume 3, New York, Plenum
Press, 1964, pp 193-210. 30:41
682. Field emission microscopy of silver nucleation and epitaxial growth on tungsten. (USA) T h e t e c h n i q u e u s e d for o b t a i n i n g clean silver surfaces by epitaxial g r o w t h on t u n g s t e n f r o m the v a p o u r is described. T h e article is well illustrated a n d epitaxial relationships are discussed in detail. A F Melmed and R F M c C a r t h y , J Chem Phys, 42 (4), Jan 1965,
1466-1468. 30 : 16 : 33
683. Diffusion of impurities during epitaxy. (Great Britain) W Rice, Proc IEEE, 52, March 1964, 284-295. 30 : 41
684= Large vacuum metallising plant. (Great Britain) Anon, Engineer, 219 (5692), Feb 1965, 401. 30 : 41 6 8 5 . Vacuum metallising plant. (Great Britain) A n o n , Engineer, 219 (5697), April 1965, 613.