Separation of semiconductor wafer into chips bounded by scribe line

Litant, I.

Scapicchio, A. J.

English

NASA Technical Reports Server

REPLY TO 
ATTN OF: G p  
TO: 
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 
WASHING TON^ 0.C. 20546 
u s ~ / s c i e n t i f  ic & Technical Information Division 
Attentionr Miss Winnfe M. Morgan 
FROM: ~ ~ / 0 f f i c e  of A s s i ~ t a p t  General Counsel f o r  
Patent Matters 
SUBJECT: ~nnouncernent of NASA-Owned U, S. Patents i n  STAR 
In  accordance with the procedures agreed upon by Code G P  
and Code U S I ,  the attached NASA-owned U. S. Patent is being 
forwarded f o r  abstracting and announce'mnt i n  NASA STAR- 
The following in£ ormation is irovidedr m 
U. S, Patent No, 
Government or  
Corporate Employee 
Supplementary Corporate - 
Source (if applicable) - t @ . .'* - 
NASA Patent Case No. 
-.-. b -:, 
NOTE - If ' t h i s  patent covers an invention made by a corporate 
ernplo~ee of a NASA Contractor, the  following is applicable: 
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Pursuant to Section 305(a) of the National Aeronautics and 
Space A c t ,  the  name of the  Administrator of NASA appears on 
the first page of the patent; however, the name of the actual 
inventor (author) appearrr a t  the heading of Column No. 1 of . 
the Specification, following tha -h l ea  *. , . w i t h  zeopect t o  
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Enclosure 
Copy of Patent a i t e d  above 
https://ntrs.nasa.gov/search.jsp?R=19710004879 2020-03-17T02:33:09+00:00Z

F i l e d  May , 1969 
33 
Feb. 3, 1970 I ,  LITANT AL 3,493,155 
95 AND KCTNOO FOR SEPARATING A SPMKCONBUCTOR WAFER 
3 Sheets-Sheet 3 
F16.5. 
- r.: United States Patent 0% . i ; ,  $ u 8 r s t l e b  ce: :. ,,. i ,. _, ,* I, . 
3,493,155 
ABPARAwS AYD ME1 HOD FOR S E Q A R A m G  A 
SEBIICOKDUCTOR WAFER 
Irving i i tanl ,  LexinA(on, and Anthony J. Scapiccbio, 
Melros?, Mas . ,  assignor5 to  the United Slates of 
America :I\  reprerented by tile Administrator of 
the Natjon:~l Aerona11tic5 and Sp:~ce ad mini st ratio^^ 
I'iled May 5, 1969, Ser. No. 821,586 
Int. ('1. B26f .?/Of) 
1J.S. Ci. 225-2 4 C'I:tln~q 
-- 
"$ 
& 
the chip breakrng operation. In the pasi, senil~crriiuctii~ 
wafers have been cut Into chrps rrsing bang saws (1; 
ultrasonic cutters. The use of gang s2v s has proved uri 
econom~cal due to the waqe ol' rnatertai raxrced bv $tie 
sawing and also by the slow speed of oper:rtion. Ultra- 
sonic cutters are more efficrent and rrndiice less waste 
than gang wws but are con\~de!:tbly more expenqive rn 
or iginal co\t. Later, the pi ior 211 t ci~wlo>cs a nunlbcr 
of other ways for sepi~r;~ting the wafer In :mother mcthocl, 
l o  ZI curved niember IS employed lo flex the wafer after i t  h,~s 
been sc~ihed. When the curved member such as a cvlin- 
ABSTIlACT OF THE DISC1,OSILJNE tlrici~l i~nvil or roller is employed, the wafer nmust be flexed first in one direction and then in the other direction, 
The  invention rel:ttc? to a method and apparatus for  and the operator must be t.easonably careful in order to 
separating semiconductor chips who\e boundaries are de- 16 ,minimize damage to and contamination of the chips. 1 3 i s  
fined by scribe lines in a suhstantinlly flat senliconductor operation is not entirely successful due to its slow speed 
water. The wafer will already have heen processed to con- of operation and contamination and darnage m the chips 
fain multiple microcircuits consisting of various diffusion by the flakes that are produced during the breaking oper- 
and dielectric layers as well as the connecting metalized ation. Other methods suggeri tile use of an  adhesive, 
lines. The scribed wafer i n  positioned over a convex hemi- 20 flexible sheet for retaining tho irrdividir,tl chips in place 
sphere, Thereafter, a flexible diaphragm is caused to after the wafer is separated. Another ntethod requires 
engage the scribed wafer and in tiny continuous incre- placing the scribed wafer in a folded sheet of paper and 
merits, force the wafer against the convex hemisphere so pulling it over and down on a curved metal cylinder 
as to  separate the wafer into individual chips with a mini- with the scribed surface up. Other techniques have em- 
mum of flake and dust formation. Also, the individud 25 ployed plastic tapes between which ivrifcrs are pulled 
chips are not permitted to slide about and damage ad- over two curved surfaces. adhesive tapes on which wafers 
jacent chips. are mounted and broken, and steel sheets :vhich are flexed 
with wafers mounted on them. 
ORIGIN OF THE INVENTION None of the foregoing methods are trn!y satisfactory. 
30 Jn these prior art methods, the yieids are low in that The invention described herein was made by employee$ :he ,-hips become damaged by with each other or 
of the U.S. Government and may be manufact1licd and with flakes of semiconductor resllliing as t f l e  
u\ed by or- for the Govet-nnlent of the United Slates of  individual chips are broker, the scribed lines. Anieric:~ for gover-nmenti~l purpoCcs without the P;lYnlcnt invention overcomes the objections of 
o f  any roy:~ltics thcrcon o r  thc~efor .  :I-; a1.t in that the chips ;ire held in yi:ice during the oper- 
13AC K C R O U N D  OF THF INVENTION atrtrn and are not permitted $0 \Irdr c,vct e a ~ h  other o r  
scratch the metalized cond rctirig tincs; semiconductor One o f  the initial steps in the formation of nlicro- 
circuits. is the pr-owing of a cryst;rl, such as germaniunl , fakes  produced during the Lreaking operittion are mini- 
mized and in addition can not touch the circuit pattern; 
o r  silicon, which is subseqt~ently 5liced into thin wafers. 40 and, 
of a skilled The thin wafer\ are then scribed by a scribing device, - .;I o r  ;Ire eliminated. 
the lines so formed by the scribing will determine the SUMMARY OF TPi;E INVESTYON 
boundaries of the individual chips which are later formed 
into miii~ocircuits. As an exanlple, the semiconductor 
uafers may be approximcttely 0.006 inch in thickness and 
the individual chips formed from the wafer may be of a 
dimension. in the case of rectangular chips, 0.040 inch 
by 0.070 inch. Chips of dimensions other than rectangular 
may be scribed on the wafer although the prior art ap- 
paratus for separating the wafer into tbe chips may not 
be capable of separating the chips defined by thesc un- 
usual scribe Iine3. 
The chip wparation techniques have been a n3ajor 
5ource of yield lo\\ which is c;tused principally by break- 
ing of the chip5 and scratching of the chips. As ;in ex- 
ample, scribing and breaking yield\ of 75'4 h;~vc heen 
found by vi\u:il in\pcction o l  prenlo~~nted ch ip .  Cr;~ck.;, 
chips, and scratches, which are incipicnt failures may 
readily pas\ this viwal oh\e~-\ation and al,o i.~tcr test\, 
only to fail in 11%. The dificulty arise5 in the inherent 
production of i n a l l  dicirnond and ~il icon particles. !n 
most of the prewnt pl-ocedurei for forming the chips from 
the ulafcr, there is stifiicient agitation of the breabii~g 
and the all-eady broken wafer into chips, to enable the 
duit particles fornmetl during the breaking operation ;it 
the edge of a chip to scratch rhe surface n~elalization. 
Prior to separating the wafer- into chips, the icni i -  
conductor wafer is first scribed so ;is to form a gi id-!ike 
pattern o f  lines or grooves. Thereafter, the scrihcd ua fc r  
is flexed in such a rn;inrter \o :is to separate the \v;ifcr 
into 3 plurality of chips :I\ dctesniined by the sc~ibecl 
lines o r  marks. V;irious methods have been emmployed in 
In  the present invention, ark open end ~ylil-idrical cham- 
ber has positioned therein a convex hr~?iisphere upon 
which a scribed semicr~nd~rctor wni'er is r:lcctii. A flexible 
diaphragm is posifioned over the wafer  2nd convex hemi- 
sphere and a second chamber is positioned over the flex- 
ible diaphragm. Fluid pressure is introduced into the up- 
per chamber so as to  force the PIe:cible dkphmgm down- 
ward and into engagement with the scrihed wafer. As the 
presstire is progressively increased, the flexible diaphragm 
"walks" across the surface of the scribed wafer. the wafer 
being forced into engagement with the convex hemisphere. 
The pressure is increa\etl rrntii the entire wafei. is brol,cn 
and when the fluid pressure is fcrniin~itcd arid the upper 
chaniher and Oexihie diaphragm removed, t h e  remains 
a completely bl-okcn semicond~tctor witfcr now in the fort11 
of nl:iny chips. I)nring the ope:;rtion, rile chips were not 
permitted to  touch each other and thus cause damage. Irt 
addition, the separation o f  thc wafer ;at the scrihed lines 
was clean, ciear-cut, and ordel-iy st; th;ii. :lij!c if any 3;ij:cs 
o r  dust were fornmed. In actual practice, very high yields 
have been achieved. 
Accordiiigly, it is {fie principal object (;I lire preserit 
inventioii :o improve the prcces-eq, n~cthnrts, a-tntl appa- 
ratllc for separ;iting elements whose boundaries are defined 
by scribe lines. 
It is a further object of the present invention 10 inz- 
prove the methods and apparatus for  separakiilg semi- 
conductor chips whose boundaries zre defined by scribe 
lines in a substantially flat semiconductor wafer. 
- 
It is a further object of the present invention to increase 
the yield o f  sernicondrrctsr chips formed from breaking 
. . a scrl"ued sen~lco;ldiictur \%,iifer by eliminiifing or nti:i:- 
mizing semiconductor flakes and dust resulting from the 
breaking operation and by not permitting the chips to 
slide over each other so as  to scratch o r  mar other chips " 
so formed. 
It is a further object of the present invention to  permit 
the breaking of chips from a wafer into any geometrical 
pattern determined hy the scrihed lines, the breaking be-- ],, 
ing attended hy n high yield and hy the services of an in- 
experiencetl operatclr. 
Hlillii;' DESCli11'7'10N OF THE DRAWINGS 
7s 
produced by the applicaiiiar? of pressure tlirouph the con- 
ciuib 48. 
As the pressure "via the conduit 40 j ; ,  jntt:,c;~-eii, tile flex- 
ible diaghragril 28' ~orlfiliilcs lo "s'aik'' aciiisi ",I; sdriace 
of the scribed wafer 24' and orie of rhe irrterii~etIiaie pcsi-. 
rions is shown in the FlciURE 3. 111 rlre FIGURE 3, it 
will he noted that ihe central portion of rhe scribed wafer 
24" and an area surrounding the central portion has been 
parted at  the scribe lines by engagement of thc flexible 
diaphragm now indicated as 28". 
'The application of fluid pressure continues ihmugh the 
conduit 40 until a final position is reached which is illus- 
trztted in the FIGURE 4. In this figure, the flexible dia- 
phragm now indicated as 28"' has "waiketi" conipleteiy 
Thc invention, both :IS to i t s  organi7ation and met]lo,l 1 5  :~C'-OSS IIhe enfire surface of the scribed wafer now desig- 
of operation, together with further objects and  nated 24"'. Tlre entire wafer 24"'h:is been brokcn and 
thereof, will best he ~lndersrootl by reference to the fol- the flexible diaphragm 28"' has conginuect on dawrrward 
lowing specifications laken in conjunction with the accom. "floss a lower portion of the convex hemisphere 18. As 
panying drawings in which: the pressure was increased in the upper chamber 30 to 
FIGURE 1 is an exploded view, with portions removed, 20 force the  flexible diaphriigm 28 downwardly, any  pressure 
of the apparatus for  accomplishing the breaking opera- built UP In the lower chamber 12 v,as tclieved through the 
tion; bleed holes 20. 
FIGURE 2 is a diagrammatic side elevational view of In the FIGURE 5 ,  nh,: B~uih' : :  i;i::phr:?:it> 18, the 
the apparatus and illustrating the first step of the method upper chamber 38. ar,d the top pialc L2 ;:.I I?  been re- 
wherein the flexible diaphragm is just touching the wafer 26 moved so as to expose the b r o k ~ n  wafer 14"" and the 
positioned on the convex hemisphere; individual chips 42 which have bzrn formed as a re- 
FIGURE 3 is a diazrammatic side elevational view sult of the f'ore~oing proces .  P i l tko~~gh not readily 
similar to the FIGURE 2 and showing the flexible dia- evident in the FlGIJRE 5 ,  the chips 42 hive i~een formed 
phragm in a more advanced position in separating the with little, if any, flaking o r  dust being iornlzd and each 
wafer; 30 chip 42 is prefectly fornitd ;nd nut ctijpped o r  marred 
FIGURE 4 is a diagrammatic side elevational view in any manner. The foregoing operation can be accom- 
similar to the FIGURES 2 and 3 but illustrating the final pli',hed by an unskilled operator and repeaieci tilne and 
position of the flexible diaphragm at the termination o f  again reaching yields that approach 10(i%. 
the separating process; and, Thu.;, a highly efficient, 5imple. and reli;lhle method 
FIGURE 5 is a pictorial view of the lower chamber 36 and apparatus has been disclosed for separating serni- 
with a portion removed, and showing the individual chips conductor wafers o r  wafel.s ui otliei material, which 
after separation of the wafer. have been previously scribed accortiing to a desired 
DESCRIPTION OF 'TWF PREFERRED p'tttern. The yield\ from quch oycr,irion art: extremely 
I klRODlMFYT high In that I~ttle, ~f airy flrrLinp b- ,i *, fc,irneci dui- 4r' In- the or~crairon. \ L ~ I < ~ I  ilaA~t, r \  I!v t lelete~~or~.;  
~h~ is 5hown in a n  exploded view i n  the F ~ G -  10 the chips. I ;u~.the~-:~iorc,  the indivii!k!ai chip, have 
URE 1. A base member 10 of flat construction has posi- h e n  held in poyition and h:rvc not b x n  permitted to 
tioned thereon a lower 12. - ~ h ~  lower chamber move al7011t \o as to damage fhcni\clvch o r  adjacent 
12 is secured to the base member 10 by a plurality chips. The process can be rcpealetl iinre and :asair? by an 
bolts, not shown, which are insel-ted in a group of q j  inexperienced operator which :ii!evi:ites ti?,: ri::e:f for 
tures 14  in the lower chamber 12 and apertures 16 (only advanced training in the practice of the proxss.  
one of which is shown) in the base member 10. Positioned In an actual prom\\ ivhich has been pi-actice4, the 
within the lower chamber 12 and resting upon the base wafer diameten were 1-23 inches. 'Ti-  r i i i i , i ,  of ctirva- 
member 10 is a con\.rex hemisphere 18, ~h~ hemisphere illre of the hemisphere w;:\ S.Cf  <.!it. -1 .'ic ~ l i i c X l i ~ ~ ~ . ;  of the 
1 8  is provided a plurality of bleed holes 20 which Pevible diaphr:t,~n~ wak 0.018 inch. T h c  pressure :~ppliet! 
communicate with a central aperture 22. ~h~ purpose of "as 120 p.s.i. The wafer thicknesses r:ingtii from 0.006 
the bleed holes 20 is to prevent a rise in pressure above inch to 0.010 inch. Whcn the wafers wrre properly 
the hemisphere 18 during the bj-eaking operation. ~t is over scribed, es~entially 100% breakage w.i\ n*~hiived along 
the convex hemisphere 1 8  (hat the wafer is sub- the scribe lines. Ill adtiition lo th,: !lsii,ti reclilngtllar 
sequently broken. One such wafer is shown at  24. The 53  chips, other w.tfei-s were \~cccs\fii!iy set~;ri,iiec! such as 
wafer 24 has scribed thereon a plurality of scribed lines those into symmetrical triangle? by scribincl: at the ap- 
26 which are scribed in accordance with the geometrical ~ 1 - o ~ r i a t e  angles. The rectangular scribing produced chip 
pattern desired of the chips. sizes in the ranges o f  0.040 by 0.070 to (1.070 by 0.070 
A flexible diaphragm 28 is illustrated in the FIGURE inch. Sm;lller chip sizes woll1d reqllire ;I hcrni\plhcr.e hav- 
] above the scribed wafer 24 and below a cylindrical np- 60 in!! a smalier raditl.: of ctirvature, the ra:iikfs elf crtr-Vairrrc 
per chamber 38. Above the llnper chamber 30 is a fop  being e;l\ily !iclectcd hy cine \kiii?tl i i i  ;he a r i .  
plate 32 and the top plate 32,  the upper chamber 30, and Thus, thc present invention nt;iy i-): embodieii in o:her 
the flexible diaphragm 28 have formed therein, r e s p c -  specific form.; without c!ep;lt-ling fi-onr th:: spirit anti 
tively, a plurality of apertllres 34, 36, and 38 whicf, align ti': es$enti;~l ch;~r:~ctci~i\rrc~, of tile iiiveniic?n 
with the aperture.; 14 and 16 in the lower chamher I f  f i j  Vdh:it i 5  clairncif i 5 :  
and the haie member I@. The bolts, not &own, sect~rely 1 .  A n~ethoil for \cp:lg-:ttit~? :I \ + , t i t a ! .  ~ I l o ~ t *  l - ! b ~ ~ t - ~ ~ ! L ~ t , i ~ \  
position the entire <fcvice as a inlid tJni?, A sorjrce of' f l t r i t i  itre ( l ~ f i l 2 ~ d  by  %:lit'W !ititx% ~ . t ) i l \ ~ ? l ~ i \ i ! ~ ~  th,. \t~*{i., * ~ * f  ]-t,~,i- 
pre\:ijr.e, \hoiv:), i,, in(i.utjiiciitj i i l l o  IIprEr chamher  l i m i r : ~ :  rho i:/;ifci. otat:r :i ccii:vi. I;',~i;i\lil:c,c, i , : . t ; imti:  ., 
30 via a condtlit 40. The pre\\tire to tile ripper charnhei- ie\ilient tfii1~3hrit~rn t ) V t l  1112 ! a r ~ l l ~ r ~  < > I C : ~ I I C  f i > , .  tii'ti>i11'1~111 
m:ty be controlled in any <riit:ihle rnzinner. 70  :tg:~intt the w,~fcr \o ; I \  l o  cnjz;igr !fie t c - ~ r t i - : ~ i  :rrc;i of 
The methoti i \  best i!lirslr;tted in the FIGIJRES 2, 3 .  I h -  ( J i :~phr~ t~ r i>  & i t 1 1  1111: centi-;~! itre { ) f  !!-st: ts,,,ft%~. : t f ! , !  c ( , I ~ .  
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illg engagemenl with t!le scliheti w:tfcr iiitlicitleti a1 26'. :~\>umcs llle contotll. oi' the ccifivey \ l i r f ; l c . c  10 i?ierehy 
'l'hc cli~plni.erncnl ut' the Itexihic cliaph~.,ign~ 28' 11.1s bcc11 i s  ~.epiir-ate the v,.~fcr a[ i t \  \ c r - i i ~ t  l i l l c \ ,  
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Apparatus and method for separating a semiconductor wafer Patent

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