Polymers in Electronics - American Chemical Society

ft/min, total exposure time 15 to 30 sec, or under 4RS sunlamps located 10 inches from the sample on a^turntable. RS sunlamp intensity was measured to...
0 downloads 0 Views 871KB Size
21 Photosensitive Polyimide Siloxane GARY C. DAVIS Corporate Research & Development Center, General Electric Company, Schenectady, NY 12301 A photosensitive silicone polyamic acid is described. This material is easily prepared directly from the precursor silicone polyamic acid. Properties and characteristics of this polymer system are discussed including handling, use, and practical photochemistry. Thermal tempering of the photosensitive or crosslinked polymer gives the polyimide siloxane which has been previously shown to be an excellent candidate as an insulating polymer in electronics. The use of such a directly patternable polyimide for dielectric and passivation applications, particularly in micro­ electronics, should become increasingly important as polyimides become more widely accepted in the industry. The insulating properties of polyimides for microelectronics applications are well known (1). However, patterning of polyimides using photoresist technology can be cumbersome since inorganic protective layers are often required to protect poly­ imide films during dry etching. Even the use of wet solution development of polyamic acid films still requires the use of a photoresist to form the initial pattern. A photosensitive poly­ amic acid can simplify processing by acting essentially as its own photoresist. If designed properly, the photosensitive polyamic acid when thermally cured is converted to the parent polyimide with its inherent excellent thermal and electrical properties. Scheme I demonstrates a savings of six steps in device fabrication by the use of a photosensitive polyimide. This paper will report on the preliminary work on the prep­ aration of a photosensitive polyamic acid which has advantages over previously reported materials (2) in the ease of synthesis and in some properties of final Imide film. 0097-6156/ 84/ 0242-0259S06.00/ 0 © 1984 American Chemical Society

POLYMERS IN ELECTRONICS

260

Conventional Dry Etch

Photosensitive

Si Wafer

1.

Apply polyamic acid

2.

Cure to polyimide

1.

•polyimide Si wafer 3.

Protect polyimide •Si0

o

Apply photosensitive . polyimide

///////-

photosensitive "polyimide -Si Wafer

2.

Expose photosensitive polyimide

3.

Develop photosensitive polyimide

4.

Cure to polyimide

Apply photoresist photoresist

5.

Expose Photoresist

6.

Develop Photoresist

7.

Etch S i 0

8.

Strip Photoresist

9.

Etch Polyimide

10.

Remove S i 0

2

Scheme I .

o

Comparison o f P a t t e r n i n g P r o c e s s f o r and P h o t o s e n s i t i v e P o l y i m i d e s .

Conventional

21.

DAVIS

Photosensitive Polyimide

Siloxane

261

Experimental General. I n f r a r e d measurements w e r e p e r f o r m e d u s i n g a N i c o l e t 7199C F T I R on t h i n f i l m s OVLy) c o a t e d on s i l i c o n w a f e r s . T h e s e measurements w e r e u s e d t o f o l l o w t h e UV c u r i n g and t h e r m a l t e m p e r ing of polyamic a c i d f i l m s . B u l k I R s w e r e p e r f o r m e d on a P e r k i n E l m e r 598 I n f r a r e d S p e c t r o p h o t o m e t e r . G l a s s t r a n s i t i o n t e m p e r a t u r e (Tg) m e a s u r e m e n t s w e r e p e r f o r m e d on a P e r k i n E l m e r DSC-2 D i f f e r e n t i a l S c a n n i n g C a l o r i m e t e r . UV e x p o s u r e s w e r e p e r f o r m e d on a PPG M o d e l QC 1202 U l t r a v i o l e t P r o c e s s o r r u n a t 10 t o 20 f t / m i n , t o t a l e x p o s u r e t i m e 15 t o 30 s e c , o r u n d e r 4RS sunlamps l o c a t e d 10 i n c h e s f r o m t h e s a m p l e on a ^ t u r n t a b l e . RS sunlamp i n t e n s i t y was m e a s u r e d t o be 4.3 mW/cm a t 365 nm. Film development was done i n b a t c h f a s h i o n . A l l s o l v e n t s and r e a g e n t s w e r e used as r e c e i v e d . I s o c y a n o t o e t h y l m e t h a c r y l a t e i s an e x p e r i m e n t a l monomer f r o m Dow. N - p h e n y l p h t h a l a m i c a c i d was p r e p a r e d f r o m a p h t h a l i c a n h y d r i d e and a n i l i n e i n m e t h y l e n e c h l o r i d e . f

Polyimide Siloxane (SiPI). I n t o a 500 c c 3 n e c k r o u n d bottomed f l a s k e q u i p p e d w i t h a m e c h a n i c a l s t i r r e r and n i t r o g e n b y p a s s i s p l a c e d 54.00 gms (0.17 m o l e s ) o f 3 , 3 , 4 , 4 ' - b e n z o p h e n o n e t e t r a c a r b o x y l i e d i a n h y d r i d e d i s s o l v e d i n 250 c c o f s i e v e d r i e d N - m e t h y l p y r r o l i d o n e ( B & J ) . To t h e s t i r r e d s o l u t i o n i s added 23.22 gms (0.12 m o l e s ) o f m e t h y l e n e d i a n i l i n e f o l l o w e d by 12.6 gms (0.05 moles) o f bis-l,3-gamma a m i n o p r o p y l t e t r a m e t h y l d i s i l o x a n e . The v i s c o u s s o l u t i o n i s a l l o w e d t o s t i r a t room t e m p e r a t u r e f o r 24 hours. 1

Isocyanatoethyl Methacrylate Modified Polyimide Siloxane (PSiPI). I n t o a 100 c c 1 n e c k r o u n d b o t t o m e d f l a s k p r o t e c t e d f r o m l i g h t and e q u i p p e d w i t h a m a g n e t i c s t i r r i n g b a r and a n i t r o g e n b y p a s s , i s p l a c e d 35 gms o f 28% s o l i d s i n N - m e t h y l p y r r o l i d i o n e (NMP) p o l y i m i d e s i l o x a n e ( S i P I ) and 5.5 gms o f i s o c y a n o t o e t h y l methacrylate. The r e a c t i o n m i x t u r e i s s t i r r e d a t room t e m p e r a t u r e f o r 24 h r s . The e v o l u t i o n o f CO- b e g i n s i m m e d i a t e l y , y e t some i s o c y a n a t e r e m a i n s f o r a b o u t 24 n r s . I n some r e a c t i o n s t o l u e n e i s added t o r e d u c e t h e i n i t i a l v i s c o s i t y o f t h e s o l u t i o n . Toluene i s a l s o found t o improve s p i n c o a t i n g c a p a b i l i t i e s of t h e polymer solution. P r i o r t o c o a t i n g , a s e n s i t i z e r package i s added. A t y p i c a l p a c k a g e c o n s i s t s o f 4% M i c h l e r ' s K e t o n e and 4% N - m e t h y l diethanolamine. The f i n a l s o l u t i o n i s s t o r e d c o l d ( ^ ° C ) ; h o w e v e r , i t i s warmed t o room t e m p e r a t u r e p r i o r t o u s e . P S i P I F i l m Préparation. A c l e a n e d ( a c i d washed o r o x y g e n p l a s m a descummed) s i l i c o n w a f e r i s s p i n c o a t e d w i t h P S i P I and d r i e d a t 100°C f o r 1 h o u r . The w a f e r i s t h e n masked and e x p o s e d . Typical t i m e s a r e 30 s e c on t h e PPG U l t r a v i o l e t P r o c e s s o r and 5 m i n u n d e r RS Sunlamps. The u n e x p o s e d a r e a i s t h e n d e v e l o p e d t y p i c a l l y u s i n g 0.5N NaOH. The p a t t e r n e d f i l m i s t h e n t h e r m a l l y tempered a t 200°C f o r 1 h r f o l l o w e d by 300°C f o r 1 h r t o c o n v e r t i t t o t h e i m i d e .

POLYMERS IN ELECTRONICS

262 R e s u l t s and

Discussion

The p h o t o s e n s i t i v e p o l y a m i c a c i d d i s c u s s e d h e r e i s made d i r e c t l y f r o m t h e p r e c u r s o r p o l y a m i c a c i d . Of t h e few o t h e r p h o t o s e n s i t i v e polyamic a c i d s reported i n the l i t e r a t u r e ( 2 ) , the workers i n i t i a l l y p h o t o - f u n c t i o n a l i z e t h e monomers. T h i s l a t t e r a p p r o a c h r e q u i r e s more s t e p s and r e q u i r e s more c a r e a s t h e p h o t o s e n s i t i v e m o i e t y i s i s o l a t e d and c a r r i e d t h r o u g h t h e e n t i r e s y n t h e s i s process. A c o m p a r i s o n o f t h e two p r o c e s s e s i s shown i n Scheme I I . Our p o l y m e r r e q u i r e s a r e a c t i o n b e t w e e n a c a r b o x y l i c a c i d o r a m i d e and a m o l e c u l e c o n t a i n i n g a p h o t o l a b i l e g r o u p . Candidates considered f o r that molecule included g l y c i d y l methacrylate 1, a c r y l o y l c h l o r i d e 2, and i s o c y a n o t o e t h y l m e t h a c r y l a t e (IEM) 3.

1

2

3

Model system s t u d i e s w i t h t h e s e m a t e r i a l s u s i n g N-phenylp h t h a l a m i c a c i d 4, i n d i c a t e d t h a t 3 was t h e most p r o m i s i n g c a n d i date. As i n t y p i c a l r e a c t i o n s o f e p o x i d e s w i t h c a r b o x y l i c a c i d s (3), r e a c t i o n of 4 w i t h 1 r e q u i r e d temperatures i n excess of 100°C. E x t e n d e d t i m e a t 100°C, h o w e v e r , c a u s e s u n d e s i r e d i m i d ization. R e a c t i o n o f 4 w i t h 2 was shown t o be f e a s i b l e , b u t was n o t f u r t h e r p u r s u e d . The a n h y d r i d e l i n k a g e f o r m e d w o u l d l i k e l y

be t o o h y d r o l y t i c a l l y u n s t a b l e and p r o n e t o p r e i m i d i z a t i o n d u r i n g film drying. R e a c t i o n o f 4 w i t h 3^ was f o u n d t o be s l o w a t room t e m p e r a t u r e but l i k e r e p o r t e d r e a c t i o n s between c a r b o x y l i c a c i d s and i s o c y a n a t e s c o u l d be a c c e l e r a t e d by a m i n e s and t i n compounds (4). S i m i l a r r a t e i n c r e a s e s were found i n t h e c a t a l y z e d r e a c t i o n o f IEM w i t h t h e a c i d a m i d e p o l y m e r . The u s e o f a c a t a l y s t i s n o t n e c e s s a r y t o p r e p a r e P S I P I ; however, t h e n o n - c a t a l y z e d r e a c t i o n r e q u i r e s 24 h o u r s compared t o l e s s t h a n 1 h o u r f o r a c a t a l y z e d reaction. I n t h e model system s t u d y , even a f t e r an e q u i v a l e n t o f 3 has r e a c t e d w i t h 4, ^-H and C nmr a s w e l l a s F T I R a n a l y s i s o f t h e p r o d u c t i n d i c a t e s t h a t some c a r b o x y l i c a c i d r e m a i n s . I t i s c o n c e i v a b l e t h a t some o f t h e 3^ i s o c y a n a t e r e a c t s w i t h t h e a m i d e g r o u p o f 4 ( 5 ) . However, e v e n i f t h i s r e a c t i o n o c c u r s , t h e 1 3

21.

DAVIS

Photosensitive

Polyimide

Siloxane

263

Monomer Approach

Scheme I I .

A Comparison o f Processes f o r P r e p a r i n g sensitive Polyimides.

Photo-

264

POLYMERS IN ELECTRONICS

o r i g i n a l g o a l o f a c i d a m i d e f u n c t i o n a l i z a t i o n has b e e n accom­ p l i s h e d t o g i v e a p h o t o s e n s i t i v e m a t e r i a l w h i c h would u l t i m a t e l y y i e l d an i m i d e on t h e r m a l t r e a t m e n t . The r e a c t i o n p r o d u c t o f 3 w i t h 4 was n o t f u r t h e r c h a r a c t e r i z e d . The r e s t o f t h i s p a p e r d e a l s e x c l u s i v e l y w i t h t h e IEM m o d i f i e d S i P I . The amount o f IEM r e q u i r e d t o g i v e a p o l y m e r w h i c h c o u l d be s u c c e s s f u l l y p h o t o c r o s s l i n k e d i s i m p o r t a n t ( T a b l e I ) . As e x p e c t e d , t h e more p o l y m e r g r o u p s f u n c t i o n a l i z e d , t h e more p h o t o r e a c t i v e t h e p o l y m e r , y e t i t i s i m p o r t a n t n o t t o add t o o much IEM a s t h i s l e a d s t o g e l l f o r m a t i o n p r i o r t o UV e x p o s u r e . A 1:1 r a t i o o f IEM t o p o l y m e r i c c a r b o x y l i c a c i d g r o u p was f o u n d t o be o p t i m a l .

Table I .

D e t e r m i n a t i o n o f Optimum R a t i o o f IEM t o C a r b o x y l i c A c i d f o r S i P I Polymer M o d i f i c a t i o n Equivalent Solution After E x p o s u r e and IEM/COOH R e a c t i o n (24 h r s ) Development R e s u l t s 0 No g e l l No P a t t e r n , F i l m D i s s o l v e d °·2 No g e l l P a t t e r n , F i l m Thinned °· No g e l l P a t t e r n , Some T h i n n i n g !·° No g e l l Pattern, Minimal Thinning · No g e l l Pattern, Minimal Thinning 1.5 Gell a

b

5

1

2

R e a c t i o n r u n a t room t e m p e r a t u r e u s i n g 4 0 % Ί . 8 μ f i l m s ( d r i e d 60°C/20 min) P r o c e s s o r ) and 1 m i n d e v e l o p e r

SiPI solution in

NMP

p r i o r t o 30 s e c e x p o s u r e (PPG (0.5N NaOH)

UV

S h e l f - l i f e of p h o t o s e n s i t i v e polyamic a c i d s i s important. We have found t h a t t h e P S i P I polymer s o l u t i o n s ( c o n t a i n i n g s e n s i ­ t i z e r s ) b e g i n t o g e l l a f t e r a b o u t 1 month a t room t e m p e r a t u r e . They r e m a i n p h o t o a c t i v e d u r i n g t h e e n t i r e p e r i o d p r i o r t o g e l l formation. I f t h e p o l y m e r s o l u t i o n s a r e k e p t a t 4°C, t h e y a r e s t a b l e up t o a t l e a s t 6 m o n t h s . We h a v e f o u n d t h a t i n h i b i t o r s such as hydroquinone a r e not e f f e c t i v e i n i n c r e a s i n g polymer solution stability. U n l i k e the precursor S i P I polyamic a c i d , the p h o t o s e n s i t i v e a n a l o g u e c a n be p r e c i p i t a t e d i n t o m e t h a n o l t o g i v e a s o l i d w h i c h has shown i n c r e a s e d p h o t o p o l y m e r s h e l f s t a b i l i t y . S e n s i t i z e r s w e r e f o u n d t o be n e c e s s a r y t o e f f e c t a p h o t o c u r e o f t h e P S i P I . S e n s i t i z e r e f f e c t i v e n e s s was m e a s u r e d by c o m p a r i n g f i n a l p o l y m e r f i l m t h i c k n e s s e s a f t e r e x p o s u r e and d e v e l o p m e n t . M i c h l e r ' s k e t o n e was f o u n d t o be most e f f e c t i v e ( T a b l e I I ) . Films prepared u s i n g the M i c h l e r ' s ketone/N-methyldiethanola m i n e s e n s i t i z e r s y s t e m a t 4% l e v e l showed i d e n t i c a l d e v e l o p m e n t b e h a v i o r when e x p o s e d i n e i t h e r a i r o r n i t r o g e n d e m o n s t r a t i n g t h e o x y g e n i n s e n s i t i v i t y o f t h i s s e n s i t i z e r p a c k a g e . Two m i c r o n f i l m s ( a f t e r e q u i v a l e n t e x p o s u r e t i m e s u n d e r RS s u n l a m p s ) m a i n ­ t a i n e d 71% of t h e i r o r i g i n a l t h i c k n e s s a f t e r 6 minutes of d e v e l o p ­ i n g i n 0.5N NaOH. I n s e p a r a t e e x p e r i m e n t s t h e optimum amount o f M i c h l e r ' s k e t o n e f o r a 5 m i n RS sunlamp e x p o s u r e was d e t e r m i n e d t o be a b o u t 4 t o 6% t o p o l y m e r w e i g h t ( T a b l e I I I ) .

21.

Photosensitive Polyimide

DAVIS

Table I I .

Sensitizer None 2,2-Dimethoxy2-phenylacetophenone Benzophenone Michler's Ketone 2-Chlorothioxanthone

Siloxane

265

S e n s i t i z e r E f f e c t i v e n e s s on P S i P I C u r i n g

% Sensitizer in Polymer a

Developer T i m e (min) 0.1 0

d

e

0.5 1.5

32 24

1.5

80

2

60

An e q u a l p e r c e n t a g e o f N - m e t h y l d i e t h a n o l a m i n e each sample b

% Of I n i t i a l Film Thickness After Exposure 0

added t o

0 . 5 N NaOH

"Development t i m e was d e t e r m i n e d by t h e t i m e i t t o o k t o open the pattern. I n i t i a l films dried f i l m (100°C/2 h r ) . Exposed

100°C/1 h r e x c e p t 2 - c h l o r o t h i o x a n t h o n e

5 m i n u t e s 10 i n c h e s u n d e r 4 RS

Table I I I .

sunlamps.

Effect of Sensitizer Concentration on P h o t o c u r e o f P S i P I

% M i c h l e r ' s Ketone 2 4 6 8 10

D e v e l o p e r ^ Time° (min) 2 2 2 3 3

% of I n i t i a l Film Thickness A f t e r Exposure And D e v e l o p m e n t 63 85 91 92 92

Same a s T a b l e I I b

Same a s T a b l e I I

"Same a s T a b l e I I initial

films dried

100°C/lhr

Unlike other photosensitivepolyimides (2), the use of N-phenylmaleimide (10% t o polymer weight) as c r o s s l i n k i n g agent d i d n o t improve t h e p h o t o p o l y m e r i z a t i o n o f P S i P I .

POLYMERS IN ELECTRONICS

266

As e x p e c t e d , t h e more i n t e n s e t h e l i g h t s o u r c e , t h e f a s t e r t h e p h o t o c u r e . C u r e s i n a s s h o r t a s 30 s e c o n d s h a v e b e e n o b t a i n e d on a PPG U l t r a v i o l e t P r o c e s s o r . However, w i t h t h i s p o l y m e r s y s t e m , UV r a d i a t i o n a l o n e i s n o t s u f f i c i e n t f o r f a s t c u r e r a t e s . B o t h h e a t and l i g h t a r e r e q u i r e d . T h i s i s demonstrated i n Table IV.

T a b l e I V . E f f e c t o f Heat a n d L i g h t On P h o t o c u r e o f P S i P I

a

P S i P I Sample Exposure 4 RS sunlamps 5 min/80°C 4 RS sunlamps 5 min/10°C Heat lamp 5 min/90°C a

% o f I n i t i a l F i l m Remaining A f t e r Exposure Development 84 36 0 fe

F i l m d r i e d 100°C/1 h r and c o n t a i n 8% M i c h l e r ' s k e t o n e a n d 8% N - m e t h y l d i e t h a n o l a m i n e .

^Film completely l o s t i n spots. F u r t h e r w o r k i s b e i n g done i n t h i s a r e a t o u n d e r s t a n d t h i s phenomenon. Since PSiPI i sa negative acting m a t e r i a l , d i s s o l u t i o n of t h e unexposed a r e a s i s r e q u i r e d f o r p a t t e r n i n g . U n l i k e some p h o t o acting polyimides which r e q u i r e organic solvents t o d i s s o l v e t h e unexposed a r e a ( 2 ) , P S i P I i s d e v e l o p e d i n d i l u t e h y d r o x i d e s o l u ­ t i o n w h i c h makes i t c o m p a t i b l e w i t h p o s i t i v e S h i p l e y d e v e l o p m e n t equipment a n d s h o u l d m i n i m i z e p o l y m e r s w e l l i n g p r o b l e m s a s s o c i ­ a t e d w i t h o r g a n i c d e v e l o p e r s . 0.5N NaOH h a s b e e n f o u n d t o be a c o n v e n i e n t s o l v e n t f o r unexposed P S i P I . Some f i l m t h i c k n e s s l o s s i n exposed a r e a s i s observed d u r i n g development. We h a v e p r e v i o u s l y shown t h a t a 1 h r 100°C d r i e d S i P I f i l m c o n t a i n s a b o u t 22% NMP ( 6 ) . The f i l m t h i c k n e s s l o s s u p o n d e v e l o p m e n t may p a r t i a l l y r e f l e c t t h e l e a c h i n g o f t h e NMP f r o m t h e f i l m . Once t h e P S i P I h a s b e e n p a t t e r n e d , t h e r m a l t e m p e r i n g c o n v e r t s t h e c r o s s l i n k e d m o d i f i e d p o l y a m i c a c i d t o t h e S i P I i m i d e . The c r o s s l i n k s a r e expelled during thermal r i n g closure. The r e s u l t ­ i n g S i P I f i l m h a s b e e n shown t o b e more t h a n a d e q u a t e f o r e l e c t r o n i c a p p l i c a t i o n s and h a s some p r o p e r t i e s , p a r t i c u l a r l y adhesion, which a r e b e t t e r than commercial p o l y i m i d e s ( 6 ) . F i g u r e 1 shows a s e t o f I R s p e c t r a d e m o n s t r a t i n g v a r i o u s s t a g e s o f PSiPI f i l m l i f e . I R spectrum A i s t h e u n c u r e d , untempered f i l m . N o t e t h e m e t h a c r y l a t e d o u b l e bond a t 1640 c m ~ l . I R s p e c t r u m Β shows t h e same f i l m a f t e r UV i r r a d i a t i o n ; t h e a b s e n c e o f t h e c a r b o n c a r b o n d o u b l e bond i s a p p a r e n t . I R s p e c t r u m C shows t h e P S i P I f i l m a f t e r t h e r m a l t e m p e r i n g a t 300°C w h i c h c o n v e r t s i t t o S i P I i m i d e . F o r c o m p a r i s o n , a pure sample o f i m i d i z e d S i P I i s shown i n I R s p e c t r u m D. A l s o , when a s a m p l e o f P S i P I was r i n g c l o s e d a t 300°C, t h e Tg o f t h e r e s u l t a n t p o l y m e r was 190°C w h i c h i s t h e Tg o f u n m o d i f i e d f u l l y i m i d i z e d p o l y i m i d e s i l o x a n e . During t h e f i n a l t h e r m a l tempering o f P S i P I , about 40% weight l o s s o f t h e p o l y m e r i s e x p e c t e d and t h i s i s o b s e r v e d i n a 4 0 % r e d u c t i o n o f t h e ζ ( t h i c k n e s s ) dimension o f t h e polymer. Other

21.

DAVIS

Photosensitive

Polyimide

Ί 1 1 T" T Spectrum B. IEM Modified SiPI After 3 0 sec. UV Exposure.

Spectrum A. IEM Modified SiPI Before UV Exposure.

J 1900

I

267

Siloxane

L

1700

1500

1700 WAVENUMBERS

WAVENUMBERS

"Ί 1 1 1 Spectrum D. Fully Cured Unmodified SiPI Film.

Spectrum C. IEM Modified SiPI After 3 0 0 ° C / 1 hr. Tempering.

Γ

0 80

0 00

J

I

1 900

I 1 700

L

J

F i g u r e 1.

IR Spectra of S i P I

I

1900

1 500

WAVENUMBERS





1700

1500

WAVENUMBERS

After

Various

Treatments

POLYMERS IN ELECTRONICS

268

p a t t e r n dimensions a r e not e f f e c t e d . Figure 2 demonstrates t h i s phenomenon. A s i m i l a r e f f e c t h a s been p r e v i o u s l y o b s e r v e d ( 7 ) . P S i P I f i l m s a s t h i c k a s 12y h a v e been p a t t e r n e d and r e s o l u ­ t i o n s o f 40y h a v e been a c c o m p l i s h e d . Work i s c o n t i n u i n g t o i m p r o v e t h e r e s o l u t i o n , s e n s i t i v i t y , and speed c a p a b i l i t i e s o f PSiPI.

A - Exposed and developed polymer film before tempering (11.6 ).

Β - Same film after 300 °C/2h bake (8.1 ).

Figure 2. Photographs of PSiPI.

Summary A p h o t o s e n s i t i v e s i l i c o n e p o l y a m i c a c i d has been d e s c r i b e d . This m a t e r i a l i s e a s i l y prepared d i r e c t l y from t h e p r e c u r s o r s i l i c o n e p o l y a m i c a c i d . P r o p e r t i e s and c h a r a c t e r i s t i c s o f t h i s p o l y m e r s y s t e m h a v e b e e n d i s c u s s e d i n c l u d i n g h a n d l i n g , u s e , and p r a c t i c a l photochemistry. Thermal tempering o f t h e p h o t o s e n s i t i v e o r c r o s s l i n k e d polymer g i v e s t h e p o l y i m i d e s i l o x a n e w h i c h has been p r e v i o u s l y shown t o be a n e x c e l l e n t c a n d i d a t e a s a n i n s u l a t i n g p o l y m e r i n electronics. The u s e o f s u c h a d i r e c t l y p a t t e r n a b l e p o l y i m i d e f o r d i e l e c t r i c and p a s s i v a t i o n a p p l i c a t i o n s , p a r t i c u l a r l y i n m i c r o ­ e l e c t r o n i c s , s h o u l d become i n c r e a s i n g l y i m p o r t a n t a s p o l y i m i d e s become more w i d e l y a c c e p t e d i n t h e i n d u s t r y .

21. DAVIS

Photosensitive Polyimide Siloxane

269

Ac kno wl ed gmen t s The author wishes to thank Carol Fasoldt for her excellent technical support and Dr. Stephen Valenty for obtaining FTIR data. Literature Cited 1. 2. 3. 4.

Wilson, Α. Μ., Thin Solid Films, 1981, 83, 145. Rubner, R., Siemens Forsch.-u. Entwickl.-Ber., 1976, 5, 235. Sherter, L.; Wynstra, J., Ind. Eng. Chem., 1956, 48 (1), 86. Ozaki, S.; Hashino, T., Nippon Kagaku Nasshi, 1959, 80, 434; Chem. Abstracts, 1961, 55, 4396i. 5. The author is indebted to the referee for pointing out this possibility. 6. Davis, G. C.; Heath, Β. Α.; Gildenblat, G., Proceedings of the First Technical Conference on Polyimides, in press. 7. Rubner, R.; Ahne, Α.; Kühn, E.; Kololodziej, G., Photogr. Sci. Eng., 1979, 23, 303. RECEIVED September 2,

1983