Polymers for High Technology - American Chemical Society

Chapter 10 New Silicon-Containing Electron-Beam Resist Systems

Downloaded by UNIV LAVAL on July 13, 2016 | http://pubs.acs.org Publication Date: August 26, 1987 | doi: 10.1021/bk-1987-0346.ch010

E. Reichmanis, A. E. Novembre, R. G. Tarascon, and A. Shugard AT&T Bell Laboratories, Murray Hill, NJ 07974 The incorporation of silicon into resist systems has been shown to effectively instill oxygen etching resistance while maintaining lighographic utility. Such materials may be used as the imaging layer for two-level processes involving RIE pattern transfer through a planarizing layer of organic polymer. We have used the trimethylsilylmethyl appendage to effect oxygen etching resistance in both positive and negative e-beam resist systems. Compatible silyl novolac/polyolefin sulfone blends afford sensitive, high resolution resists, while the inherently posi tive acting trimethylsilylmethyl methacrylate can be copoloymerized with chlorinated styrenes to yield negative resists capable of submicron resolution. The synthesis and radiation chemistry of these mate rials is discussed, in addition to a brief analysis of their lithographic properties. Multi-layer resist systems have secured an important role in the fabrication of devices with geometries of 1.0 μιη or less ( 1). However, the complexity associated with these processes must be simplified. Since the introduction of tri-layer systems (2,3), an obvious simplification is to combine the properties of both the upper resist imaging layer and the oxygen reactive ion etching (RIE) resistant masking layer (typically S1O2) into one. One mech anism to accomplish this is to incorporate metal atoms into poly meric materials that function as resists (4-7) . Organosilicon species have been shown to provide excellent oxygen RIE resistance and are typically copolymerized with other monomers that effect the radiation sensitivity necessary for imaging (8). Unfortunately, the incorporation of silicon into polymeric resists can alter the desirable materials characteristics. A decrease in the glass transition temperature often accompanies the inclusion of silicon into a resin, and most silicon substituents will drastically change the solubility properties of the parent polymer. For example, polymerization of propylpentamethyldisiloxyl methacrylate affords rubbery, low Tg polymers that are 0097-6156/87/0346-0110$06.00/0 © 1987 American Chemical Society Bowden and Turner; Polymers for High Technology ACS Symposium Series; American Chemical Society: Washington, DC, 1987.


10.

REICHMANIS ET A L .

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Electron-Beam

Resist Systems

111

i n a p p r o p r i a t e f o r r e s i s t a p p l i c a t i o n s ( 9 ) . While o t h e r components may be i n c o r p o r a t e d i n t o the system to r a i s e the Tg, the s y n t h e s i s c o u l d become complex i f enhanced r a d i a t i o n s e n s i t i v i t y i s also desired. S i l i c o n s u b s t i t u e n t s are a l s o t y p i c a l l y hydrophobic i n n a t u r e such t h a t i f a base s o l u b l e r e s i n i s d e s i r e d , t h e r e w i l l o f t e n be a d e l i c a t e b a l a n c e between the amount of s i l i c o n t h a t can be i n c o r p o r a t e d i n t o the system t o e f f e c t RIE r e s i s t a n c e and yet a l l o w aqueous base s o l u b i l i t y . We have s u c c e s s f u l l y employed the t r i m e t h y l s i l y l m e t h y l appendage t o e f f e c t oxygen RIE r e s i s t a n c e i n both p o s i t i v e and n e g a t i v e a c t i n g electron-beam r e s i s t systems ( 1 0 , 1 1 ) . The r e l a t i v e l y compact n a t u r e o f t h i s s u b s t i t u e n t a l l o w s the p r e p a r a t i o n of g l a s s y polymers u s e f u l f o r l i t h o g r a p h i c a p p l i c a t i o n s . The p r e p a r a t i o n and c h a r a c t e r i z a t i o n of select t r i m e t h y l s i l y l m e t h y l s u b s t i t u t e d r e s i s t s w i l l be p r e s e n t e d i n a d d i t i o n t o a s t u d y o f t h e i r r a d i a t i o n chemist r y and l i t h o g r a p h i c p r o p e r t i e s . Experimental Materials. T r i m e t h y l s i l y l m e t h y l m e t h a c r y l a t e ( S i ) and chlorom e t h y l s t y r e n e (CMS) (mixed m,p isomers) were o b t a i n e d from P e t r a r c h Systems I n c . and Dow Chemical Co. I n c . , r e s p e c t i v e l y . Both monomers were p u r i f i e d by d i s t i l l a t i o n at reduced p r e s s u r e . Copolymers were prepared by f r e e - r a d i c a l s o l u t i o n p o l y m e r i z a t i o n at 85°C i n t o l u e n e . R e a c t i o n s were i n i t i a t e d u s i n g b e n z o y l p e r o x i d e . T r i m e t h y l s i l y l m e t h y l p h e n o l and o - c r e s o l were o b t a i n e d from P e t r a r c h Systems, I n c . and A l d r i c h Chem. Co. I n c . , r e s p e c t i v e l y . S i l y l a t e d n o v o l a c ( S I - n o v o l a c ) r e s i n s were p r e p a r e d by c o n d e n s a t i o n p o l y m e r i z a t i o n o f p - t r i m e t h y l s i l y l m e t h y l p h e n o l , o - c r e s o l and formaldehyde. P o l y ( 2 - m e t h y l - l - p e n t e n e - s u l f o n e ) (PMPS) was prepared as d e s c r i b e d i n the l i t e r a t u r e ( 1 2 ) . Characterization. P(SI-CMS), p o l y s t y r e n e e q u i v a l e n t m o l e c u l a r weight was determined by h i g h p r e s s u r e s i z e e x c l u s i o n chromatography (HPSEC) u s i n g a Water's Model 510 pump, 401 d i f f e r e n t i a l r e f r a c t o m e t e r , and duPont bimodal s i l a n i z e d columns; SI-novolac number average m o l e c u l a r weight was determined by vapor phase membrane osmometry (Wescan I n s t r u m e n t s , I n c . , Model 232A). Glass t r a n s i t i o n temperatures were determined u s i n g 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 . The temperature h e a t i n g r a t e was 10°C/min w i t h sample masses r a n g i n g from 10 t o 20 mg. R e a c t i v e I o n E t c h i n g . E t c h i n g experiments were c a r r i e d out i n an A p p l i e d M a t e r i a l s Model 8110 Hex r e a c t o r . A l t e r n a t i v e l y , a Cook Vacuum P r o d u c t s I n c . Model C71 RF/DC S p u t t e r i n g Module was employed. F i l m t h i c k n e s s measurements were taken b e f o r e and a f t e r e t c h i n g t o determine e t c h i n g r a t e s , and the r a t e s were t y p i c a l l y compared t o t h a t o f the n o v o l a c - d i a z o q u i n o n e p h o t o r e s i s t , HPR-206, baked at 210°C f o r 1 hour. Measurements were o b t a i n e d on a Dektak Model I I A p r o f i l o m e t e r . P(SI-CMS) r e s i s t f i l m s , 0.5 t o 1.0 um t h i c k , were spun from 10-12 w/v % s o l u t i o n s of the polymers i n 2-methoxyethyl a c e t a t e . S i l y l a t e d novolac-PMPS (SI-NPR) r e s i s t s o l u t i o n s were prepared by d i s s o l v i n g the S I - n o v a l a c (10 wt%) and PMPS (0.9 wt%) i n t o isoamy-

Bowden and Turner; Polymers for High Technology ACS Symposium Series; American Chemical Society: Washington, DC, 1987.

POLYMERS FOR HIGH T E C H N O L O G Y

112


l a c e t a t e . A l l r e s i s t s o l u t i o n s were c o n s e c u t i v e l y f i l t e r e d through a 0.5 and 0.2 ym T e f l o n f i l t e r s t a c k ( M i l l i p o r e , I n c . ) . Resist s o l u t i o n s were spun onto f o u r i n c h s i l i c o n s u b s t r a t e s t h a t were e i t h e r b a r e , o r precoated w i t h 1.5 pm o f Hunt p h o t o r e s i s t (HPR-206) baked at 210°C f o r 1 hour i n a i r . P r i o r t o e x p o s u r e , the r e s i s t coated s u b s t r a t e s were g i v e n a 30 t o 60 min. prebake at 80 t o 100°C i n a i r . The n e g a t i v e r e s i s t was p o s t - d e v e l o p - b a k e d at 120-150°C. Lithographic Characterization. Electron-beam exposures were conducted on an EBES system o p e r a t i n g at 20 kV, w i t h a beam address and spot s i z e both equal t o 0.25 Mm. E l e c t r o n response parameters were e v a l u a t e d u s i n g l i n e w i d t h c o n t r o l p a t t e r n s . P(SI-CMS) was s p r a y developed a f t e r exposure u s i n g an APT Model 915 r e s i s t p r o c e s s o r i n t o l u e n e - m e t h a n o l (1:1) f o r 30 sec f o l l o w e d by a methanol r i n s e f o r 45 s e c . Aqueous s o l u t i o n s o f tetramethylammonium hydroxi d e (TMAH, 25% i n w a t e r , F l u k a I n c . ) were used f o r the novolac r e s i s t development. Exposed f i l m s were d i p - d e v e l o p e d f o r 20 s e c . i n TMAH-water (1:2.5) s o l u t i o n s . F i l m t h i c k n e s s e s r e m a i n i n g a f t e r exposure and development were measured o p t i c a l l y u s i n g a Nanometrics Nanospec/AFT m i c r o a r e a t h i c k n e s s gauge, and a Dektak I I A p r o f i l o m e t e r . Scanning e l e c t r o n m i c r o g r a p h s (SEM) o f processed p a t t e r n s were taken u s i n g e i t h e r a JEOL IC 35CFS or Cambridge S t e r e o s c a n 100 scanning e l e c t r o n m i c r o scope. R e s u l t s and D i s c u s s i o n M a t e r i a l s S y n t h e s i s and C h a r a c t e r i z a t i o n . I n a d d i t i o n t o the r e q u i r e m e n t s o f e t c h i n g r e s i s t a n c e , s e n s i t i v i t y , s o l u b i l i t y and h i g h g l a s s t r a n s i t i o n temperature ( T g ) , one o f the c r i t e r i a used i n d e s i g n i n g both a n e g a t i v e and p o s i t i v e e l e c t r o n - b e a m r e s i s t system was s y n t h e t i c s i m p l i c i t y . The t r i m e t h y l s i l y l m e t h y l appendage a l l o w s t h e i n c o r p o r a t i o n o f s i l i c o n i n t o p o l y m e r i c resists w i t h o u t adverse s y n t h e t i c c o m p l i c a t i o n s . Standard f r e e r a d i c a l o r c o n d e n s a t i o n p o l y m e r i z a t i o n techniques can be employed w i t h approp r i a t e l y s u b s t i t u t e d monomers that a r e r e a d i l y a v a i l a b l e . While p o l y ( t r i m e t h y l s i l y l m e t h y l m e t h a c r y l a t e ) i s i n h e r e n t l y a p o s i t i v e a c t i n g r e s i s t system ( 1 3 ) , t h e s i l y l a t e d monomer can be r e a d i l y c o p o l y m e r i z e d w i t h such m o i e t i e s as c h l o r o m e t h y l s t y r e n e t o generate c r o s s l i n k a b l e polymers. A s e r i e s o f P(SI-CMS) polymers ( F i g u r e 1) were prepared and t h e r e s u l t i n g m a t e r i a l s p r o p e r t i e s a r e l i s t e d i n Table I . U s i n g the Fineman-Ross treatment ( 1 4 ) , the r e a c t i v i t y r a t i o s f o r SI and CMS were 0.49 and 0.54, r e s p e c t i v e l y . A s l i g h t l y g r e a t e r mole percentage o f CMS was t h e r e f o r e observed i n the copolymer w i t h r e s p e c t t o the monomer feed c o m p o s i t i o n . Due t o t h e compact nature o f the s i l y l a t e d e s t e r group, o n l y a l i m i t e d r e d u c t i o n i n Tg i s observed f o r these systems. The s i l y l a t e d homopolymer e x h i b i t s a Tg o f 68°C and c o p o l y m e r i z a t i o n with c h l o r o m e t h y l s t y r e n e e f f e c t s an i n c r e a s e up t o 78°C f o r t h e polymer c o n t a i n i n g 54 mole% S I . These v a l u e s o f T a r e t y p i c a l o f many n e g a t i v e r e s i s t systems and should not a f f e c t image s t a b i l i t y during l i t h o g r a p h i c processing. The t r i m e t h y l s i l y l m e t h y l u n i t may a l s o be i n c o r p o r a t e d i n t o p h e n o l i c r e s i n s t h a t a r e components o f s o l u t i o n i n h i b i t i o n p o s i t i v e g


10.

REICHMANIS ET A L .

Silicon-Containing

Electron-Beam

Resist Systems

P(SI-CMS)

CH

I

3

(—CH2—C—)—(—CH2—CH—)-~


I c = ( I

CH CI 2

0

I CH CH,—Si—CH 2

3

I CH

SI -

3

NOVOLAC

OH

CH

I

2

CH —Si—CH 3

3

CH Schematic r e p r e s e n t a t i o n o f P(SI-CMS) and s i l y l a t e d novolac. 3

F i g u r e 1.


113


114

resists. A schematic r e p r e s e n t a t i o n of the r e s i n i s shown i n F i g u r e 1. The methylene spacer between the a r o m a t i c r i n g and s i l y l s p e c i e s i n t r i m e t h y l s i l y l m e t h y l phenol e l i m i n a t e s the problem o f Si-C bond c l e a v a g e observed i n o t h e r systems (15). While c o n d e n s a t i o n polymers o f the s i l y l a t e d phenol and formaldehyde were i n s o l u b l e i n aqueous base because of the h y d r o p h o b i c n a t u r e o f the s i l y l m o i e t y , i n c o r p o r a t i o n of o - c r e s o l a f f o r d e d a l k a l i n e s o l u b l e r e s i n s w i t h up t o ~ 10 wt % s i l i c o n . Polymer m o l e c u l a r parameters f o r t h e s e systems are a l s o g i v e n i n T a b l e I . W h i l e the Tg's are lower than d e s i r e d , no adverse e f f e c t s on l i t h o g r a p h i c imaging were observed.


Table I .

Polymer

P(SI-CMS)

Polymer M o l e c u l a r Parameters

Composition

0.54:0.46 0.66:0.34 0.91:0.09 1.0:0

wt % Si

a

6.7 10.3 14.6 16.3

a a

a

SI-Novolac

0.3:0.7* 0.6:0.4° 0.8:0.2

9.7 5.4 2.5

b

a

G i v e n as t h e r a t i o elemental a n a l y s i s .

M

(χ

w ΙΟ" )

V n M

T

0.85 1.16 1.87 2.17 _

-

g

C O

5

2.3 1.9 2.1 2.2

-

78 76 70 68

broad broad

750 404

26 26

-

-

-

o f SI:CMS i n t h e p o l y m e r , as determined by

k G i v e n as t h e r a t i o o f o - c r e s o l t o t r i m e t h y l s i l y l m e t h y l p h e n o l i n the f e e d . Oxygen RIE B e h a v i o r . Oxygen RIE treatment of the s i l y l a t e d p o l y mers p r e p a r e d above l e a d s t o the g e n e r a t i o n o f a s u r f a c e l a y e r of SiOx> presumed t o be S i 0 . Auger s p u t t e r depth p r o f i l e s ( F i g u r e 2) o f the s i l y l a t e d n o v o l a c r e v e a l s t h a t a 30-50A s u r f a c e l a y e r of o x i d i z e d s i l i c o n i s i n f a c t formed. The t h i c k n e s s o f t h i s l a y e r i s an e s t i m a t e based on the s p u t t e r i n g r a t e of S i 0 (20Â per min) under s i m i l a r c o n d i t i o n s . The c o m p o s i t i o n o f t h a t l a y e r i s p r i m a r i l y s i l i c o n and oxygen, w i t h some carbon a l s o p r e s e n t . Removal o f r e s i s t v i a s p u t t e r i n g , e f f e c t s a d e c r e a s e i n the oxygen and o x i d i z e d s i l i c o n s i g n a l s w i t h a concomitant i n c r e a s e i n carbon i n t e n sity. U n t r e a t e d S I - n o v o l a c e x h i b i t s s i l i c o n s i g n a l s at 84 and 1614 EV; oxygen RIE treatment e f f e c t s a s h i f t t o 77 and 1609 EV. The s i g n a l s at 77 and 1609 EV are t y p i c a l o f o x i d i z e d s i l i c o n ( S I 0 ) . The e t c h i n g p r o p e r t i e s of the m a t e r i a l s d e s c r i b e d e a r l i e r were e v a l u a t e d as a f u n c t i o n o f s i l i c o n c o n t e n t , and the r e s u l t s are 2

2

X



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shown i n F i g u r e 3. The r e l a t i o n i s n o n - l i n e a r f o r both r e s i s t systems and becomes a s y m p t o t i c at h i g h p e r c e n t a g e s o f s i l i c o n . E x a m i n a t i o n o f t h e p l o t s o f e t c h i n g r a t e r a t i o s v s . wt. % s i l i c o n i n d i c a t e s that small incremental increases i n s i l i c o n content, i n t h e range o f 10-16%, w i l l e f f e c t l a r g e i n c r e a s e s i n e t c h i n g r a t i o s between a s i l i c o n r e s i s t and p l a n a r i z i n g l a y e r . Note t h e i n c r e a s e i n s e l e c t i v i t y from 12 t o 20 f o r t h e P(SI-CMS) copolymer c o n t a i n i n g 14.6 wt % S i and s i l y l m e t h a c r y l a t e homopolymer t h a t c o n t a i n s 16.3 wt% S i , r e s p e c t i v e l y . E t c h i n g r a t i o s f o r s i l y l a t e d polymers a r e t y p i c a l l y h i g h l y dependent on t h e e t c h i n g c o n d i t i o n s employed. Changes i n oxygen p r e s s u r e , RF power, and DC b i a s w i l l e f f e c t changes i n both e t c h i n g r a t e r a t i o s between r e s i s t and p l a n a r i z i n g l a y e r , and e t c h i n g anisotropy. F o r example, a d e c r e a s e i n b i a s v o l t a g e from -550V t o -200V l e a d s t o an improvement i n s e l e c t i v i t y from 4.5 t o 17 f o r a P(SI-CMS) polymer c o n t a i n i n g 10 wt % s i l i c o n . However at -200V, t h e e t c h i n g p r o c e s s c o n t a i n s a s i g n i f i c a n t i s o t r o p i c component and an u n a c c e p t a b l e l i n e w i d t h l o s s w i l l be o b s e r v e d . W h i l e e t c h i n g a t -350V w i l l a f f o r d h i g h l y a n i s o t r o p i c - p r o f i l e s , t h e s e l e c t i v i t y o f 6.5 observed f o r t h e 10 wt % S i polymer i s inadequate f o r subm i c r o n p a t t e r n t r a n s f e r , and t h e h i g h e r s i l i c o n content m a t e r i a l must be employed. I t i s i n t e r e s t i n g t o note t h a t t h e wt. % s i l i c o n i n a polymer i s not t h e o n l y f a c t o r i n d e t e r m i n i n g oxygen RIE selectivities. The n o v o l a c r e s i n c o n t a i n i n g o n l y 10 wt% s i l i c o n e t c h e s at a p p r o x i m a t e l y t h e same r a t e as t h e 14% S i P(SI-CMS) p o l y mer. C l e a r l y , such f a c t o r s as polymer s t r u c t u r e and c o m p o s i t i o n p l a y an added r o l e i n d e t e r m i n i n g RIE c h e m i s t r y ( 1 6 ) . Oxygen e t c h i n g r a t e s as a f u n c t i o n o f b i a s v o l t a g e f o r two PTsi-CMS) polymers and t h e s i l y l n o v o l a c c o n t a i n i n g 10 wt% S i a r e g i v e n i n T a b l e I I .

Table I I .

Resist

HPR-206 P(SI-CMS) P(SI-CMS) SI-Novolac

Oxygen RIE s e l e c t i v i t y as a f u n c t i o n o f b i a s

wt % S i

0 10.3 14.6 9.7

voltage

E t c h i n g Il a t e R a t i o (HI>R:Resin) -350V -200V -500V

1 6.5 12 11

1 4.5 11 3.5

1 17 17 >11

Lithographic Characteristics. The exposure response c u r v e s f o r Ρ(SI-CMS) and S I - n o v o l a c c o n t a i n i n g PMPS (SI-NPR) a r e shown i n F i g u r e 4, and t h e i r l i t h o g r a p h i c c h a r a c t e r i s t i c s a r e summarized i n -0.5 2 T a b l e I I I . The s e n s i t i v i t i e s a r e 2 pC/cm (D ) and 8 yC/cm f o r P(SI-CMS) and SI-NPR, r e s p e c t i v e l y . I n t h e case o f SI-NPR, PMPS a f f o r d s r a d i a t i o n s e n s i t i v i t y v i a spontaneous u n z i p p i n g a f t e r expo sure ( 1 7 ) . The mechanism i s e q u i v a l e n t t o t h a t o f NPR and t h e l i t h o g r a p h i c c h a r a c t e r i s t i c s are quite s i m i l a r . No e v i d e n c e o f i n c o m p a t i b i l i t y was o b s e r v e d . z




Figure

3.

P l o t o f e t c h i n g r a t e r a t i o s as a f u n c t i o n o f s i l i c o n c o n t e n t f o r P ( S I - C M S ) and s i l y l a t e d n o v o l a c (-350V, 4mtorr 0 ). 2


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Resist Systems

Table I I I . Summary o f L i t h o g r a p h i c C h a r a c t e r i s t i c s

Resist

Ύ

Resolution

Ρ(SI-CMS)

, 2 2 yC/cm

1.8

0.75

SI-NPR

2 8 yC/cm

1.1

0.5

l


Sensitivity

3

ym ym

Minimum demonstrated coded l i n e / s p a c e r e s o l u t i o n .

As the dose requirements for c r o s s l i n k i n g chloromethylated p o l y s t y r e n e s are s i g n i f i c a n t l y below those f o r m e t h a c r y l a t e c h a i n s c i s s i o n , P(SI-CMS) polymers are s e n s i t i v e , n e g a t i v e a c t i n g r e sists. L e d w i t h , et a l . have shown t h a t o n l y s m a l l amounts of CMS a r e r e q u i r e d t o e f f e c t over an o r d e r of magnitude enhancement i n p o l y ( m e t h y l s t y r e n e ) s e n s i t i v i t y ( 1 8 ) , and the s e n s i t i v i t y observed f o r our copolymer i s i n the range of t h a t observed f o r the m e t h y l styrene-CMS copolymers of e q u i v a l e n t m o l e c u l a r w e i g h t . An a p p r o x i m a t i o n of the r a d i a t i o n c h e m i c a l y i e l d s f o r P(SI-CMS) were d e t e r mined as per the method d e s c r i b e d by Novembre and Bowmer (19) . The c a l c u l a t e d v a l u e s of G(x) and G(s) are 1.26 and 0.5, r e s p e c t i v e l y , and the C h a r l e s b y - P i n n e r (20) p l o t used t o determine those v a l u e s i s shown i n F i g u r e 5. The r e l a t i v e l y h i g h v a l u e of G(s) i s c l e a r l y a t t r i b u t a b l e t o the presence of an a l k y l m e t h a c r y l a t e . The e f f i c i e n c y of C-Cl bond c l e a v a g e l e a d i n g t o c r o s s l i n k i n g of the polymer network i s evidenced by the h i g h v a l u e o f G ( x ) . Submicron p a t t e r n s have been generated i n both r e s i s t s and e f f e c t i v e l y p a t t e r n t r a n s f e r r e d through t h i c k p l a n a r i z i n g photo r e s i s t with l i t t l e linewidth loss. F i g u r e 6 d e p i c t s coded 1.0, 0.75 and 0.5 ym l i n e - s p a c e p a t t e r n s p r i n t e d i n SI-NPR p r i o r t o oxygen RIE t r e a t m e n t . S i m i l a r p a t t e r n s have been o b t a i n e d w i t h P(SI-CMS) and F i g u r e 7 shows the r e s u l t s of oxygen RIE p a t t e r n t r a n s f e r of coded 1.0 and 0.75 ym images o b t a i n e d w i t h the n e g a t i v e resist. Conclusion Both n e g a t i v e and p o s i t i v e a c t i n g , oxygen RIE r e s i s t n t e-beam r e s i s t systems have been prepared through the i n c o r p o r a t i o n of the t r i m e t h y l s i l y l m e t h y l f u n c t i o n a l i t y i n t o standard r e s i s t chemistry. R e s i n s c o n t a i n i n g >10 wt% s i l i c o n d i s p l a y an RIE r e s i s t a n c e more t h a n 10 times g r e a t e r than c o n v e n t i o n a l p h o t o r e s i s t s and a l l o w submicron p a t t e r n t r a n s f e r w i t h minimum l i n e w i d t h l o s s .



118


EXPOSURE DOSE (/iC/Cm*)

EXPOSURE DOSE (/xC/Cm ) 2

Figure 4.

Exposure response SI-NPR.

c u r v e s f o r a) P(SI-CMS) and b)

P(SI-CMS) G =1.26 x

G = 0.50 $

0.0

0.10

0.20 DOSE"

F i g u r e 5.

0.30 1

0.40

_i

(Mrod )

Charlesby-Pinner plot of

P(SI-CMS).


Silicon-Containing

Electron-Beam

Resist Systems


REICHMANIS ET A L .

Figure

6.

SEM m i c r o g r a p h s d e p i c t i n g c o d e d ( a ) 1 . 0 , ( b ) 0.75 a n d ( c ) 0 . 5 μιη l i n e - s p a c e p a t t e r n s p r i n t e d i n S I NPR.




120

F i g u r e 7. SEM m i c r o g r a p h s d e p i c t i n g coded 1.0 (a) and 0.75 (b) μιη l i n e - s p a c e p a t t e r n s p r i n t e d i n Ρ (SI-CMS) f o l l o w e d by oxygen RIE p a t t e r n t r a n s f e r .


10. REICHMANIS ET AL.

Silicon-Containing Electron-Beam Resist Systems

Acknowledgments The authors wish to thank T. G. Melone and C. Lochstampfor for ebeam irradiations, A. Kornblit for sample oxygen RIE determina tions, and H. Luftman for Auger analyses.


Literature Cited 1. Lin, B. J. In "Intro. to Microlithography," Thompson, L. F.; Willson, C. G.; Bowden, M. J., eds.; ACS Symposium Series, 219, (1983). 2. Havas, J. Electrochem Soc. Extended Abstracts 1976, 76(2), 74344. 3. Moran, J. M.; Maydan D. J. Vac. Sci. Technol., 1979, 16, 1620. 4. Hatzakis, M.; Paraszczak, J.; Shaw, J. In "Microcircuit Engineering 81," Oosenbrug, Α., ed., Swiss Fed. Inst. of Technol., Lausanne, pp 386-96. 5. Ohnishi, Y.; Suzuki, M.; Saigo, K.; Saotome, Y.; Gokan, H. Proc. SPIE 1985, 539, 62. 6. MacDonald, S. Α.; Steinmann, A. S.; Ito, H.; Hatzakis, M.; Lee, W.; Hiraoka, H.; Willson, C. G. "Int'l. Symp. Electron, Ion, Photon Beams," Los Angeles, CA, May 31-June 3, 1983. 7. Taylor, G. N.; Wolf, T. M. Polym. Engrg. Sci. 1980, 20, 1087. 8„ Reichmanis, E.; Smolinsky, G.; Wilkins, C. W., Jr. Solid State Technol. Aug. 1985, 130. 9. Reichmanis, E.; Smolinsky, G. Proc. SPIE 1984, 469, 38. 10. Novembre, A. E.; Reichmanis, E.; Davis, M. Proc. SPIE 1986, 631, 14. 11. Tarascon, R. G.; Shugard, Α.; Reichmanis, E. Proc. SPIE, 1986, 631, 40. 12. Bowden M. J.; Thompson, L. F. J. Appl. Polym. Sci. 1973, 17, 3211. 13. Reichmanis, E.; Smolinsky, G. J. Electrochem. Soc. 1985, 132(5), 1178. 14. Fineman, M.; Ross, S. D. J. Polym. Sci., 1950, 5, 259. 15. Wilkins, C. W., Jr.; Reichmanis, E.; Wolf, T. M.; Smith, B. C. J. Vac. Sci. Technol. 1984, B3, 306. 16. Ohnishi, Y.; Watanabe, F. J. Vac. Sci. Technol. 1986, B4, 422. 17. Bowden, M. J . ; Thompson, L. F.; Fahrenholtz, S. R.; Doerries, E. M. J. Electrochem. Soc. 1981, 128 (6), 1304. 18. Ledwith, Α.; Mills, M.; Hendy, P.; Brown, Α.; Clements, S.; Moody, R. J. Vac. Sci. Technol. 1985, B3, 339. 19. Novembre, A. E.; Bowmer, T. N. In "Materials for Microlithography," Thompson, L. F.; Willson, C. G.; Frechet, J. M. J.; eds.; ACS symposium Series, 266, 1984, 241. 20. Charlesby, A. "Atomic Radiation and Polymers," Permagon Press, New York, 1960. RECEIVED April 8, 1987


Polymers for High Technology - American Chemical Society

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