- Email: [email protected]
Tantalum nitride thin film resistors with low TCR
256
WORLD
ABSTRACTS
ON
MICROELECTRONICS
to 4 × 1019atoms/cmS a n d was f o u n d to d e p e n d linearly on the T e a t o m fraction in t h e liquid phase. F o r a linear dependence, a distribution coefficient of 0.35 m a y be assigned to T e at 1000°C. F o r extrinsic c o n ditions a n d dilute liquid solutions, p r e s e n t m o d e l s for t h e incorporation of fully ionized impurities, w h i c h do n o t include surface b a n d bending, lead to a s q u a r e - r o o t d e p e n d e n c e of t h e i m p u r i t y concentration in the solid on t h e i m p u r i t y concentration in the liquid phase. T r e a t m e n t
8. T H I C K -
AND
THIN-FILM (See
AND
RELIABILITY
of the liquid-solid interface as a m e t a l - s e m i c o n d u c t o r Schottky barrier gives a n electron concentration at t h e s e m i c o n d u c t o r surface w h i c h is i n d e p e n d e n t of the i m p u r i t y concentration in t h e solid, a n d results in a linear relationship b e t w e e n t h e concentration in t h e solid a n d liquid phase. Existing results for o t h e r impurities in G a A s a n d G a P s u g g e s t that it is necessary to consider surface b a n d b e n d i n g in t h e interpretation of other i m p u r i t y I I I - V s e m i c o n d u c t o r s y s t e m s .
CIRCUITS
AND
MATERIALS
also Components)
Characteristics and applications of bias sputtering. O. CHRISTENSEN. Solid State Technol., D e c e m b e r (1970), p. 39. T h e properties of s p u t t e r e d t h i n films can be favourably influenced by applying a negative bias to t h e growing films. T h e effects of r e - s p u t t e r i n g resulting f r o m t h e applied bias are discussed. Single metals, alloys a n d c o m p o u n d s , b o t h directly a n d reactively sputtered, are included. S o m e m e t h o d s of obtaining r e - s p u t t e r i n g are given, i n c l u d i n g a s y m m e t r i c a.c. sputtering, d.c. a n d r.f. bias sputtering. References are m a d e to diode a n d triode sputtering.
Tantalum nitride thin film resistors with l o w T C R . Av:io SATA,Y. ODA a n d Y. HISHINUMA. Proc. 1970 20th Electronic Components Conf., W a s h i n g t o n , 13-15 M a y (1970), p. 58. T a n t a l u m nitride thin film resistors with low T C R (temperature coefficient of resistance) were obtained by heat t r e a t m e n t in v a c u u m . T h e favorable characteristics of resistors w h i c h were deposited in the so called "plateau r e g i o n " were m a i n t a i n e d after this process. T h e change in the T C R value was saturated by over 2 h r of heat t r e a t m e n t a n d d e p e n d e d on only the t r e a t m e n t temperature. T h e effect of heat t r e a t m e n t in v a c u u m appeared apparently over 450°C a n d t a n t a l u m nitride film resistors with zero p p m / ° C were obtained at 520°C. "['he deviation of ± 1 0 p p , / ° C of the T C R value was achieved b y controlling the t e m p e r a t u r e within ~ 5 ° C f r o m pre-set one. T h e stability of v a c u u m annealed films was comparable to c o m m o n t a n t a l u m nitride thin film resistors in accelerated aging in air of 125°C. A c c o r d i n g to this m e t h o d , films could be deposited u n d e r the condition desirable to each s p u t t e r ing a p p a r a t u s a n d t h e n h e a t treated in v a c u u m ; so this m e t h o d is especially suitable for the s p u t t e r i n g a p p a r a t u s s u c h as a c o n t i n u o u s s p u t t e r i n g m a c h i n e in w h i c h s p u t t e r i n g conditions were restricted in a relatively n a r r o w range. F i l m s showed no special change of crystal s t r u c t u r e s after heat t r e a t m e n t in v a c u u m u n d e r X - r a y a n d electron diffraction analysis.
Glaze resistor paste preparation. L. F. MILLER. Proc. 1970 20th Electronic Components Conf., W a s h i n g ton, 13-15 M a y (1970), p. 92. T h e electrical properties of thick film resistors are k n o w n to be controlled by m a n y aspects of materials a n d processing. D i s c u s s e d
in this p a p e r are two aspects of t h e preparation of t h e resistor pastes themselves w h i c h are also p e r t i n e n t to their u n d e r s t a n d i n g . A l t h o u g h these two a s p e c t s - - t h e vehicle w h i c h carries the conductive particles, a n d t h e milling process w h i c h disperses t h e particles into t h e v e h i c l e - - a r e really t h e d o m a i n of t h e paste supplier, an appreciation of these factors can also help t h e user b o t h to c o m m u n i c a t e a n d to u n d e r s t a n d his processes. E x a m p l e s will be provided to s h o w h o w t h e p r o p e r choice of vehicle can indeed influence a n d optimize certain characteristics of glaze resistor performance, a n d h o w the electrical properties themselves can be b r o u g h t into narrower specifications b y intelligent use of the paste milling process.
Josephson
effects in thin film " W e a k - L i n k s " CERDONIO, T . DI LEO a n d G. LUCANO. Alta Frequenza X X X I X , No. 6 (1970), p. 5 4 1 - 544. W e have developed a t e c h n i q u e for fabricating " w e a k - l i n k s " b e t w e e n s u p e r c o n d u c t o r s : a constriction of 1 + 4Exm in w i d t h is created in a t h i n a l u m i n i u m film by p h o t o etching techniques. W e have s h o w n in detail that these " w e a k - l i n k s " s h o w up all the d.c. a n d a.c. J o s e p h s o n effects. T h e m a i n feature of these s t r u c t u r e s is an h i g h degree of reproducibility of their characteristics over m a n y t h e r m a l cicles between r o o m a n d liquid h e l i u m t e m p e r a t u r e , so that t h e y can be u s e d in device applications. M.
Compatibility between thin and thick film techniques. E. CAPPELLETTI,A. CATTANEO,F. FORLANI a n d A. PUZONE. Alta Frequenza, Vol. X X X l X , No. 6 (1970), p. 537-540. T h e i m p l e m e n t a t i o n of L S H I (large scale h y b r i d integrated) circuits, i.e. h y b r i d circuits u s i n g m o n o l i t h i c L S I chips, poses t h e p r o b l e m to get a technological approach suitable to obtain interconnection networks characterized by h i g h densities of low resistivity conductive lines in multilayer structures with as m u c h low as possible parasitic capacitance at t h e crossovers. T h i n film a n d thick film t e c h n i q u e s are comparatively analyzed a n d it is s h o w n h o w their proper hybridization can provide an o u t s t a n d i n g approach. S o m e results are presented. So far they are encouraging, f u r t h e r developm e n t being u n d e r w a y .
WORLD
ABSTRACTS
ON
MICROELECTRONICS
to 4 × 1019atoms/cmS a n d was f o u n d to d e p e n d linearly on the T e a t o m fraction in t h e liquid phase. F o r a linear dependence, a distribution coefficient of 0.35 m a y be assigned to T e at 1000°C. F o r extrinsic c o n ditions a n d dilute liquid solutions, p r e s e n t m o d e l s for t h e incorporation of fully ionized impurities, w h i c h do n o t include surface b a n d bending, lead to a s q u a r e - r o o t d e p e n d e n c e of t h e i m p u r i t y concentration in the solid on t h e i m p u r i t y concentration in the liquid phase. T r e a t m e n t
8. T H I C K -
AND
THIN-FILM (See
AND
RELIABILITY
of the liquid-solid interface as a m e t a l - s e m i c o n d u c t o r Schottky barrier gives a n electron concentration at t h e s e m i c o n d u c t o r surface w h i c h is i n d e p e n d e n t of the i m p u r i t y concentration in t h e solid, a n d results in a linear relationship b e t w e e n t h e concentration in t h e solid a n d liquid phase. Existing results for o t h e r impurities in G a A s a n d G a P s u g g e s t that it is necessary to consider surface b a n d b e n d i n g in t h e interpretation of other i m p u r i t y I I I - V s e m i c o n d u c t o r s y s t e m s .
CIRCUITS
AND
MATERIALS
also Components)
Characteristics and applications of bias sputtering. O. CHRISTENSEN. Solid State Technol., D e c e m b e r (1970), p. 39. T h e properties of s p u t t e r e d t h i n films can be favourably influenced by applying a negative bias to t h e growing films. T h e effects of r e - s p u t t e r i n g resulting f r o m t h e applied bias are discussed. Single metals, alloys a n d c o m p o u n d s , b o t h directly a n d reactively sputtered, are included. S o m e m e t h o d s of obtaining r e - s p u t t e r i n g are given, i n c l u d i n g a s y m m e t r i c a.c. sputtering, d.c. a n d r.f. bias sputtering. References are m a d e to diode a n d triode sputtering.
Tantalum nitride thin film resistors with l o w T C R . Av:io SATA,Y. ODA a n d Y. HISHINUMA. Proc. 1970 20th Electronic Components Conf., W a s h i n g t o n , 13-15 M a y (1970), p. 58. T a n t a l u m nitride thin film resistors with low T C R (temperature coefficient of resistance) were obtained by heat t r e a t m e n t in v a c u u m . T h e favorable characteristics of resistors w h i c h were deposited in the so called "plateau r e g i o n " were m a i n t a i n e d after this process. T h e change in the T C R value was saturated by over 2 h r of heat t r e a t m e n t a n d d e p e n d e d on only the t r e a t m e n t temperature. T h e effect of heat t r e a t m e n t in v a c u u m appeared apparently over 450°C a n d t a n t a l u m nitride film resistors with zero p p m / ° C were obtained at 520°C. "['he deviation of ± 1 0 p p , / ° C of the T C R value was achieved b y controlling the t e m p e r a t u r e within ~ 5 ° C f r o m pre-set one. T h e stability of v a c u u m annealed films was comparable to c o m m o n t a n t a l u m nitride thin film resistors in accelerated aging in air of 125°C. A c c o r d i n g to this m e t h o d , films could be deposited u n d e r the condition desirable to each s p u t t e r ing a p p a r a t u s a n d t h e n h e a t treated in v a c u u m ; so this m e t h o d is especially suitable for the s p u t t e r i n g a p p a r a t u s s u c h as a c o n t i n u o u s s p u t t e r i n g m a c h i n e in w h i c h s p u t t e r i n g conditions were restricted in a relatively n a r r o w range. F i l m s showed no special change of crystal s t r u c t u r e s after heat t r e a t m e n t in v a c u u m u n d e r X - r a y a n d electron diffraction analysis.
Glaze resistor paste preparation. L. F. MILLER. Proc. 1970 20th Electronic Components Conf., W a s h i n g ton, 13-15 M a y (1970), p. 92. T h e electrical properties of thick film resistors are k n o w n to be controlled by m a n y aspects of materials a n d processing. D i s c u s s e d
in this p a p e r are two aspects of t h e preparation of t h e resistor pastes themselves w h i c h are also p e r t i n e n t to their u n d e r s t a n d i n g . A l t h o u g h these two a s p e c t s - - t h e vehicle w h i c h carries the conductive particles, a n d t h e milling process w h i c h disperses t h e particles into t h e v e h i c l e - - a r e really t h e d o m a i n of t h e paste supplier, an appreciation of these factors can also help t h e user b o t h to c o m m u n i c a t e a n d to u n d e r s t a n d his processes. E x a m p l e s will be provided to s h o w h o w t h e p r o p e r choice of vehicle can indeed influence a n d optimize certain characteristics of glaze resistor performance, a n d h o w the electrical properties themselves can be b r o u g h t into narrower specifications b y intelligent use of the paste milling process.
Josephson
effects in thin film " W e a k - L i n k s " CERDONIO, T . DI LEO a n d G. LUCANO. Alta Frequenza X X X I X , No. 6 (1970), p. 5 4 1 - 544. W e have developed a t e c h n i q u e for fabricating " w e a k - l i n k s " b e t w e e n s u p e r c o n d u c t o r s : a constriction of 1 + 4Exm in w i d t h is created in a t h i n a l u m i n i u m film by p h o t o etching techniques. W e have s h o w n in detail that these " w e a k - l i n k s " s h o w up all the d.c. a n d a.c. J o s e p h s o n effects. T h e m a i n feature of these s t r u c t u r e s is an h i g h degree of reproducibility of their characteristics over m a n y t h e r m a l cicles between r o o m a n d liquid h e l i u m t e m p e r a t u r e , so that t h e y can be u s e d in device applications. M.
Compatibility between thin and thick film techniques. E. CAPPELLETTI,A. CATTANEO,F. FORLANI a n d A. PUZONE. Alta Frequenza, Vol. X X X l X , No. 6 (1970), p. 537-540. T h e i m p l e m e n t a t i o n of L S H I (large scale h y b r i d integrated) circuits, i.e. h y b r i d circuits u s i n g m o n o l i t h i c L S I chips, poses t h e p r o b l e m to get a technological approach suitable to obtain interconnection networks characterized by h i g h densities of low resistivity conductive lines in multilayer structures with as m u c h low as possible parasitic capacitance at t h e crossovers. T h i n film a n d thick film t e c h n i q u e s are comparatively analyzed a n d it is s h o w n h o w their proper hybridization can provide an o u t s t a n d i n g approach. S o m e results are presented. So far they are encouraging, f u r t h e r developm e n t being u n d e r w a y .