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April, 2003 CMS tracker electronics 1
APV25 Production Testing Status
Mark Raymond, Imperial College
Outline
Yield studies
current status of ongoing investigations into causes of low yield on latest and previousproduction lots
Future production plan
April, 2003 CMS tracker electronics 2
History - 2002Jan 1st two production lots showed low yield
manufacturer found evidence of problems with silicide layer – both lots returned for replacement
March 3rd lot -> much better, 79% yield (few patchy wafers)
May 4th and 5th (replacements for 1 and 2) -> 33% and 44%=> still some processing problem
other HEP designs also experiencing variable yieldcauses unclear but long metal lines common to HEP designs(possible ESD damage during processing due to antenna effect)
Sept Test structures (CERN) included on MPW run to try and prove/disprove theories
Nov MPW run back -> all structures showing high yield no sig. difference between “low expected” and “high expected” yield designs => nothing proven
see http://www.hep.ph.ic.ac.uk/~dmray/pptfiles/CMS_TK_ELEC_July2002.pptand http://www.hep.ph.ic.ac.uk/~dmray/pdffiles/APV_LECC02_HEP.pdf
3210
100806040200% yield
lot 1
3210
100806040200% yield
lot 2
2
1
0
100806040200% yield
lot 3
3210
100806040200% yield
lot 4
43210
100806040200% yield
lot 5
lot 1
lot 2
lot 4
lot 5
lot 3
April, 2003 CMS tracker electronics 3
Up to date - 2003Jan: APV lots 6 and 7 delivered
lot 7 -> average 52%, but lot 6 close to zero
manufacturers notified (via CERN)
Feb: wafers from all 4 lower yield lots sent for failure analysis (FA)
weekly telephone conference set up to monitor progress including participants from:
Manufacturers: FA teams on 2 sites
Imperial and RAL: APV design and test
CERN: coordinating team and Medipix engineers
3210
1009080706050403020100% yield
lot 7lot 7
(Medipix project also experiencing yield problems on several lots – design not very similar to APV but might be common root cause – understood on all sides that FA on APV takes priority)
April, 2003 CMS tracker electronics 4
Date probed:Chips passed:Yield:
Digital failures:Power supply failures:Channel defects (Peds & Cal):Pipeline defects:
01060
01070
01080
01090
01100
01110
01120
01130
020612
02077
02080
02090
02100
02110
02120
02130
03040
03050
03060
03070
03080
03090
03100
03110
03120
03130
03140
031512
040412
04050
040610
04070
04080
04090
04100
04110
04120
04130
04140
041512
050210
05030
050410
05050
05060
05070
05080
05090
05100
05110
05120
05130
05140
05150
051610
051710
060211/12
060312
060410
06050
06060
06070
06080
06090
06100
06110
06120
06137
06140
061512
061611/12
061711/12
070211/12
07030
07040
07050
07060
07070
07080
07090
07100
07110
07120
07130
07140
07150
071612
0717
080211/12
080310
08040
08050
08060
08070
08080
08090
08100
08110
08120
08130
08147
081510
081612
081711/12
090212
09030
09040
09050
09060
09070
09080
09090
09100
09110
09120
09130
09140
09150
091612
091711/12
0918
091912
100212
10030
10040
10050
10060
10070
10080
10090
10100
10110
10120
10130
10147
10150
101610
101712
101811/12
101912
11000
110112
110210
11030
11040
11050
11060
11070
11080
11090
11100
11110
11127
11130
11140
11150
11160
11170
111811/12
111910
12000
120111/12
12020
120310
12040
12050
12060
12070
12080
12090
12100
12110
121212
121310
121410
121510
121610
121710
121811/12
121910
13000
130111/12
130210
13030
13040
13050
13060
13070
13080
13090
13100
13110
13120
13130
13140
13150
13160
131710
13180
13190
140012
140111/12
140212
140310
140410
14050
14060
14070
14080
14090
14100
14110
14120
141310
141410
14150
14160
141710
141811/12
141912
150212
150312
150412
15050
15060
15070
15080
15090
15100
15110
15120
15130
15140
15150
15160
151710
151817/22
151912
160211/12
160312
160412
160510
16060
16070
16080
16090
16100
16110
16120
161310
16140
161520
16165
161712
1618
161912
1702
170311/12
170412
17050
17060
17070
17080
17097
17100
17110
17120
17130
17140
17150
17160
171712
1802
180311/12
180412
180512
180610
18070
18087
18090
18100
18110
18120
181310
181410
18150
181612
181717/22
190211/12
190311/12
190412
19050
19060
19070
19080
19090
19100
19110
19120
19130
19140
19150
191612
191711/12
20020
200311/12
200412
200512
200610
200710
20080
20090
20100
20110
20120
201310
201410
201512
201611/12
201711/12
2104
210512
210612
210710
210810
21090
21100
21110
211210
211310
211412
21150
2204
2205
2206
220711/12
220812
220912
221010
221110
221212
221311/12
221411/12
221511/12
230611/12
230712
230811/12
230912
23100
23110
23120
231311/12
240610
240712
2408
240911/12
241011/12
241111/12
24120
24130
Wafer Map: A7BCG1T
Wed 29 Jan 2003 10/360 3%
220 7123 0
Problem Lots
Date probed:Chips passed:Yield:
Digital failures:Power supply failures:Channel defects (Peds & Cal):Pipeline defects:
01061/2/3/4/5
01071/2/3/4/5
01081/2/3/4/5
01091/2/3/4/5
01101/2/3/4/5
01111/2/3/4/5
01121/2/3/4/5
01131/2/3/4/5
02061/2/5
02072/4/5
02081/2/3/4/5
02091/2/3/4/5
02101/2/3/4/5
02111/2/3/4/5
02121/2/3/4/5
02131/2/4/5
03041/2/3/4/5
03051/2/3/4/5
03061/2/3/4/5
03071/2/3/4/5
03081/2/3/4/5
03091/2/3/4/5
03101/2/3/4/5
03111/2/3/4/5
03121/2/3/4/5
03131/2/3/4/5
03142/4/5
03152/4/5
04041/2/3/4/5
04051/2/3/4/5
04061/2/3/4/5
04071/2/3/4/5
04081/2/3/4/5
04091/2/3/4/5
04101/2/3/4/5
04111/2/3/4/5
04121/2/3/4/5
04131/2/3/4/5
04141/2/3/4/5
0415
05021/2/3/4/5
05031/2/3/4/5
05041/2/3/4/5
05051/2/3/4/5
05061/2/3/4/5
05071/2/3/4/5
05081/2/3/4/5
05091/2/3/4/5
05101/2/3/4/5
05111/2/3/4/5
05121/2/3/4/5
05131/2/3/4/5
05141/2/3/4/5
05151/2/3/4/5
05162/4/5
05171/2/3/4/5
06021/2/3/4/5
06031/2/4/5
06041/2/3/4/5
06051/2/3/4/5
06061/2/3/4/5
06071/2/3/4/5
06081/2/3/4/5
06091/2/3/4/5
06101/2/3/4/5
06111/2/3/4/5
06121/2/3/4/5
06131/2/3/4/5
06141/2/3/4/5
06151/2/4/5
06162/4/5
06172
07021/2/3/4/5
07031/2/3/4/5
07041/2/3/4/5
07051/2/3/4/5
07061/2/3/4/5
07071/2/3/4/5
07081/2/3/4/5
07091/2/3/4/5
07101/2/3/4/5
07111/2/3/4/5
07121/2/3/4/5
07131/2/3/4/5
07141/2/3/4/5
07151/2/3/4/5
07161/2/3/4/5
07172/5
08021/2/3/4/5
08031/2/3/4/5
08041/2/3/4/5
08051/2/3/4/5
08061/2/3/4/5
08071/2/3/4/5
08081/2/3/4/5
08091/2/3/4/5
08101/2/3/4/5
08111/2/3/4/5
08121/2/3/4/5
08131/2/3/4/5
08141/2/3/4/5
08151/2/3/4/5
08161/2/3/4/5
08172
09021/2/3/4/5
09031/2/3/4/5
09041/2/3/4/5
09051/2/3/4/5
09061/2/3/4/5
09071/2/3/4/5
09081/2/3/4/5
09091/2/3/4/5
09101/2/3/4/5
09111/2/3/4/5
09121/2/3/4/5
09131/2/3/4/5
09141/2/3/4/5
09151/2/3/4/5
09161/2/3/4/5
09172/3/4/5
0918
09191/2/3/4/5
10021/2/3/4/5
10031/2/3/4/5
10041/2/3/4/5
10051/2/3/4/5
10061/2/3/4/5
10071/2/3/4/5
10081/2/3/4/5
10091/2/3/4/5
10101/2/3/4/5
10111/2/3/4/5
10121/2/3/4/5
10131/2/3/4/5
10141/2/3/4/5
10151/2/3/4/5
10161/2/3/4/5
10171/2/3/4/5
1018
10191/2/3/4/5
11001/2/3/4/5
11011/2/3/4/5
11021/2/3/4/5
11031/2/3/4/5
11041/2/3/4/5
11051/2/3/4/5
11061/2/3/4/5
11071/2/3/4/5
11081/2/3/4/5
11091/2/3/4/5
11101/2/3/4/5
11111/2/3/4/5
11121/2/3/4/5
11131/2/3/4/5
11141/2/3/4/5
11151/2/3/4/5
11161/2/3/4/5
11171/2/3/4/5
11182/3/4/5
11192/3/5
12001/2/3/4/5
12011/2/3/4/5
12021/2/3/4/5
12031/2/3/4/5
12041/2/3/4/5
12051/2/3/4/5
12061/2/3/4/5
12071/2/3/4/5
12081/2/3/4/5
12092/3/4/5
12101/2/3/4/5
12111/2/3/4/5
12121/2/3/4/5
12131/2/3/4/5
12141/2/3/4/5
12151/2/3/4/5
12161/2/3/4/5
12171/2/3/4/5
12182/5
12191/2/3/4/5
13001/2/3/4/5
13011/2/3/4/5
13021/2/3/4/5
13031/2/3/4/5
13041/2/3/4/5
13051/2/3/4/5
13061/2/3/4/5
13071/2/3/4/5
13081/2/3/4/5
13091/2/3/4/5
13101/2/3/4/5
13111/2/3/4/5
13121/2/3/4/5
13131/2/3/4/5
13141/2/3/4/5
13151/2/3/4/5
13161/2/3/4/5
13171/2/3/4/5
13181/2/3/4/5
13191/2/3/4/5
14001/2/3/4/5
14011/2/3/4/5
14021/2/3/4/5
14031/2/3/4/5
14041/2/3/4/5
14051/2/3/4/5
14061/2/3/4/5
14071/2/3/4/5
14081/2/3/4/5
14091/2/3/4/5
14101/2/3/4/5
14111/2/3/4/5
14121/2/3/4/5
14131/2/3/4/5
14141/2/3/4/5
14151/2/3/4/5
14161/2/3/4/5
14171/2/3/4/5
14181/2/3/4/5
14191/2/3/4/5
15021/2/3/4/5
15031/2/3/4/5
15041/2/3/4/5
15051/2/3/4/5
15061/2/3/4/5
15071/2/3/4/5
15081/2/3/4/5
15091/2/3/4/5
15101/2/3/4/5
15111/2/3/4/5
15121/2/3/4/5
15131/2/3/4/5
15141/2/3/4/5
15151/2/3/4/5
15161/2/3/4/5
15171/2/3/4/5
15181/2/3/4/5
15191/2/3/4/5
16021/2/3/4/5
16031/2/3/4/5
16041/2/3/4/5
16051/2/3/4/5
16061/2/3/4/5
16071/2/3/4/5
16081/2/3/4/5
16091/2/3/4/5
16101/2/3/4/5
16111/2/3/4/5
16121/2/3/4/5
16131/2/3/4/5
16141/2/3/4/5
16151/2/3/4/5
16161/2/3/4/5
16171/2/4/5
16181/2/3/4/5
16191/2/3/4/5
17021/2/3/4/5
17031/2/3/4/5
17041/2/3/4/5
17051/2/3/4/5
17061/2/3/4/5
17071/2/3/4/5
17081/2/3/4/5
17091/2/3/4/5
17101/2/3/4/5
17111/2/3/4/5
17121/2/3/4/5
17131/2/3/4/5
17141/2/3/4/5
17151/2/3/4/5
17161/2/3/4/5
17171/2/3/4/5
18021/2/3/4/5
18031/2/4/5
18041/2/3/4/5
18051/2/3/4/5
18061/2/3/4/5
18071/2/3/4/5
18081/2/3/4/5
18091/2/3/4/5
18101/2/3/4/5
18111/2/3/4/5
18121/2/3/4/5
18131/2/3/4/5
18141/2/3/4/5
18151/2/3/4/5
18161/2/3/4/5
18172/4/5
19021/2/3/4/5
19031/2/4/5
19041/2/3/4/5
19051/2/3/4/5
19061/2/3/4/5
19071/2/3/4/5
19081/2/3/4/5
19091/2/3/4/5
19101/2/3/4/5
19111/2/3/4/5
19121/2/3/4/5
19131/2/3/4/5
19141/2/3/4/5
19151/2/3/4/5
19161/2/3/4/5
19171/2/3/4/5
20021/2/3/4/5
20031/2/3/4/5
20042/5
20051/2/4/5
20061/2/3/4/5
20071/2/3/4/5
20081/2/3/4/5
20091/2/3/4/5
20101/2/3/4/5
20111/2/3/4/5
20121/2/3/4/5
20131/2/3/4/5
20141/2/3/4/5
20151/2/3/4/5
20161/2/3/4/5
20171/2/3/4/5
21042/4/5
21052/4/5
21061/2/3/4/5
21071/2/3/4/5
21081/2/3/4/5
21091/2/3/4/5
21101/2/3/4/5
21111/2/3/4/5
21121/2/3/4/5
21131/2/3/4/5
21141/2/3/4/5
21151/2/3/4/5
22041/2/3/4/5
22051/2/4/5
22062/4/5
22072/4/5
22081/2/3/4/5
22091/2/3/4/5
22101/2/3/4/5
22111/2/3/4/5
22121/2/3/4/5
22131/2/3/4/5
22141/2/3/4/5
22151/2/3/4/5
23061/2/3/4/5
23071/2/3/4/5
23081/2/3/4/5
23091/2/3/4/5
23101/2/3/4/5
23111/2/3/4/5
23121/2/3/4/5
23131/2/3/4/5
24061/2/3/4/5
24071/2/3/4/5
24081/2/3/4/5
24091/2/3/4/5
24101/2/3/4/5
24111/2/3/4/5
24121/2/3/4/5
24131/2/3/4/5
Wafer Map: WG8P4CT
Wed 26 Feb 2003 3/360 1%
351 1 4 1
Date probed:Chips passed:Yield:
Digital failures:Power supply failures:Channel defects (Peds & Cal):Pipeline defects:
01062/5
0107
0108
0109
01102/3/5
01112/5
0112
0113
02062
0207
0208
0209
0210
0211
0212
0213
03041/2
0305
03062/5
03072
0308
0309
0310
03112
0312
0313
0314
0315
0404
04052
04062
0407
04085
0409
0410
04112/5
0412
0413
0414
0415
0502
0503
0504
0505
0506
05072
0508
0509
05102
0511
0512
0513
0514
0515
0516
0517
0602
06032/5
0604
0605
0606
06072
0608
06092
0610
0611
0612
0613
0614
0615
0616
0617
0702
07032/5
0704
0705
07062/4/5
07071/2/3/4/5
07081/2/4/5
07092/3/4/5
07102/4/5
07112/4/5
0712
07132
0714
0715
0716
0717
0802
0803
0804
08052/5
08062/5
08072
08082/4/5
08091/2/3/4/5
08102/4/5
08112
08122
08132
08142/5
08152
0816
0817
09022/5
0903
09042/5
09052/5
09062/4/5
09071/2/3/4/5
09081/2/3/4/5
09091/2/3/4/5
09101/2/4/5
09112/3/4/5
09122/3/4/5
09132
09142
0915
0916
0917
0918
0919
1002
10032
10042
10052/5
10062/3/4/5
10071/2/3/4/5
10081/2/3/4/5
10091/2/3/4/5
10102/3/4/5
10112/4/5
10122/3/4/5
10132
1014
1015
1016
1017
1018
1019
1100
1101
1102
11032/5
11042/5
11052/3/4/5
11061/2/3/4/5
11071/2/3/4/5
11081/2/3/4/5
11091/2/3/4/5
11101/2/4/5
11111/2/3/4/5
11121/2/3/4/5
11132/4/5
1114
1115
1116
1117
1118
1119
1200
1201
1202
12032
12042
12052/4/5
12061/2/3/4/5
12071/2/3/4/5
12081/2/3/4/5
12092/3/4/5
12102/5
12111/2/3/4/5
12121/2/3/4/5
12132/4/5
12142
12152
1216
1217
1218
1219
1300
1301
1302
1303
13042/5
13052/4/5
13062/3/4/5
13071/2/3/4/5
13081/2/3/4/5
13091/2/3/4/5
13101/2/3/4/5
13111/2/3/4/5
13121/2/3/4/5
13131/2/3/4/5
13142
13152
1316
1317
1318
1319
14002/3/5
1401
1402
14032
14042
14052/5
14062/4/5
14071/2/3/4/5
14081/2/3/4/5
14091/2/3/4/5
14101/2/3/4/5
14111/2/3/4/5
14121/2/3/4/5
14131/2/3/4/5
14142
14152/5
1416
1417
1418
1419
1502
15032/5
15042
15052/4/5
15061/2/4/5
15071/2/3/4/5
15081/2/3/4/5
15091/2/3/4/5
15101/2/3/4/5
15111/2/3/4/5
15121/2/3/4/5
15131/2/3/4/5
15142
1515
1516
1517
1518
1519
1602
1603
16042/5
16052
16062/4/5
16072/4/5
16081/2/3/4/5
16091/2/3/4/5
16101/2/3/4/5
16111/2/3/4/5
16121/2/3/4/5
16132/3/4/5
16142
16152
1616
1617
1618
1619
1702
1703
17042/5
17052/5
17062/5
17072/4/5
17081/2/4/5
17091/2/3/4/5
17101/2/3/4/5
17111/2/3/4/5
17121/2/4/5
17131/2/3/4/5
17142
1715
1716
1717
1802
18032/5
1804
1805
18062
18072/5
18082/5
18092/4/5
18102
18111/2/4/5
18122
18132
18142
1815
1816
1817
19022/5
19032/5
1904
19055
19062
19072
19082
19092/5
19102/5
19112/5
19122
19132
1914
1915
1916
1917
2002
20032/5
2004
2005
2006
2007
20082
20092/5
20102
20112
20122
20132
2014
2015
20162
2017
2104
2105
2106
21072/5
2108
21092/5
2110
21112/5
2112
2113
21142/5
2115
22042/3/5
22052/4/5
22062
22072/5
22085
2209
2210
2211
22122
2213
2214
2215
2306
2307
2308
23095
2310
23112/3/5
23122/5
2313
24062/3/4/5
2407
2408
24092
24105
24112/5
2412
2413
Wafer Map: W28P77T
Thu 27 Feb 2003170/36047%
111 1 77 1
Date probed:Chips passed:Yield:
Digital failures:Power supply failures:Channel defects (Peds & Cal):Pipeline defects:
01062
01072
0108
01092
0110
01112
01122
01132/5
02062
0207
02082/5
0209
0210
02112
0212
0213
0304
0305
0306
0307
0308
0309
0310
0311
0312
0313
0314
03152
0404
0405
0406
04071/2/4/5
0408
0409
0410
0411
0412
04132
04145
0415
05022
0503
0504
0505
0506
05072
05082
05092
05102/4/5
05112
05122
0513
0514
0515
0516
05172
0602
0603
06042
0605
06061/2/4/5
06072
06082
06092
06102
06112
06122
0613
0614
0615
0616
0617
0702
0703
0704
07052
07062
07072/4/5
07082/4/5
07092/4/5
07102/4/5
07112
07122/4/5
07132
0714
0715
0716
0717
0802
08032
0804
08052
08062
08072/4/5
08082
08092/4/5
08102
08112
08122
08132/5
08142
0815
0816
0817
0902
09032
09042
09052
09062/4/5
09071/2/3/4/5
09081/2/3/4/5
09091/2/4/5
09102
09112/5
09122/4/5
09132/4/5
09142
09152
0916
0917
0918
09191/2/5
10022
10032
10042
10052
10062
10072/4/5
10082/3/4/5
10092/4/5
10102
10112
10122
10132/5
10142/4/5
10152
10162
1017
1018
10192
11002/3/4/5
1101
1102
11032
11042/4/5
11052/4/5
11062/4/5
11072/4/5
11081/2/4/5
11092/4/5
11102
11112/4/5
11122/4/5
11132/4/5
11142/3/4/5
11152/5
11162
1117
1118
1119
12002/3/5
1201
1202
12032
12042
12052/4/5
12062/4/5
12072/4/5
12082
1209
1210
12112
12122
12132/5
12142
12152
12162
1217
1218
1219
13001/2/3/4/5
1301
13022
13032
13042
13052/4/5
13061/2/3/4/5
13071/2/3/4/5
13082/3/4/5
13092/4/5
13102/4/5
13112/4/5
13122/4/5
13132/4/5
13142/3/4/5
13152/5
1316
1317
13182
13192
14001/2/3/4/5
1401
1402
14032
14042
14052/5
14062/5
14072/4/5
14082/3
14091/2/3/4/5
14102
14112/4/5
14122/4/5
14132/4/5
14142/5
14152
14162
1417
1418
1419
15022
15032
15042
15052
15062
15072/4/5
15082/4/5
15092/4/5
15102/4/5
15111/2/3/4/5
15121/2/3/4/5
15132/3/4/5
15142/4/5
15152/4/5
1516
1517
1518
15192/4/5
1602
1603
16042
16052
16062
16072
16082
16092
16102
16112/4
16122/4/5
16132/5
16142
16152
1616
1617
1618
16191/2/3/4/5
1702
17032
1704
17052
17062
17072
17082
17092/4/5
17102/5
17112/5
17122/5
17132
17142
17152
1716
1717
18022
1803
1804
1805
1806
18072
18082
18092
18102
18112
18122
18132
18142
18152
1816
1817
1902
1903
1904
19052/3/4/5
1906
19072
19082
19092
19102
19112
1912
1913
1914
1915
1916
1917
20021/2/3/4/5
2003
2004
2005
2006
2007
2008
20092
20102
2011
2012
2013
2014
2015
2016
20172/4/5
21045
21052/3/5
2106
2107
2108
2109
21103/5
2111
2112
2113
2114
2115
22042/3/5
22052
2206
22072
2208
2209
2210
2211
2212
2213
2214
22152
2306
2307
2308
2309
2310
2311
2312
2313
24062/4/5
24072
2408
2409
24101/2
24112
2412
2413
Wafer Map: KKM3K2T
Tue 18 Feb 2003150/36042%
77 2127 4
lot 4 – ave. yld. 33% lot 5 – ave. yld. 44% lot 6 – ave. yld. ~ 0% lot 7 – ave.yld. 52%
sample wafers from each of 4 problem lots sent to manufacturers failure analysis team
Lot 4 wafer extreme example but hopefully indicative of failure mode of other wafers in same lotother wafers from this lot already with hybrid company
to assist failure analysis wafers re-probed with modified test protocol – trying to extract as much info as possible from failing sites
April, 2003 CMS tracker electronics 5
Analog
Pipeline
Memory
Pipeline Control Logic
Pre
am
plifi
er
Filt
er
Pip
elin
eR
ea
do
ut
12
8:1
An
alo
gM
ux
Bias generator
and bias registers
FIFO Standard
Cell Logic
Modified wafer test protocol
test continues to end even if gross defect found early onto provide as much info as possible to FA team
sort failures into 5 categories:powerchannel (pedestal or response to CAL)bias register (stuck bits)pipeline logic (digital header incorrect)other digital
try to associate failure with particular functional area on chip
high power failure can be useful in localising faults
chips can (and often do) fail on more than one (sometimes all) categories
April, 2003 CMS tracker electronics 6
Failure Analysis (FA) techniquesliquid crystal
wafer coated with temperature sensitive layerprobes used to apply power to a particular chipcoating changes colour over any hot spots – allows localization of fault
delayering (top down) cross sectiongradual removal of layers, looking for cut through wafer in suspect locationproblems along the way
April, 2003 CMS tracker electronics 7
Metallization X section
MZ
M2
M1
via
via
via
via
M2
Q2 thin dielectriclayer
APV uses 3 metal layers (up to 6 possible)
floating capacitors implemented by Q2/M2 structure – only used in analogue parts of chip
production process divided into 2 distinct phases
Front end of line – transistors defined
Back end of line – metal layers and interconnecting vias added
substrate
ILD (inter-level dielectric)
ILD (inter-level dielectric)
April, 2003 CMS tracker electronics 8
Fault Diagnosis – Lot 6
severity of problem with this lotallowed fairly rapid diagnosis
X-section through metal trackingshows shorts between tracks, andQ2 (capacitor top-plate metal) whereit shouldn’t be
Q2 should have been stripped off (inareas where it is not supposed to be)prior to patterning of underlying M2
problem thought to be incomplete removal of photo-resist layer used to pattern Q2=> Q2 layer not removed properly (in areas where it should be)=> subsequent M2 etch had to go through Q2 first and so didn’t get all the way through
example coordinatesX=2422, Y=872 um
cross section
April, 2003 CMS tracker electronics 9
Fault Diagnosis – lot 4this wafer showed high power consumption failures – liquid crystal technique showed hotspots in pipeline control logic area
non-contacting vias => transistors which should be off can float to on condition => high power consumption
reasons for via underetch not clear, but separation between metal layers close to maximum allowed=> points to possible problem with Inter-Level Dielectric (ILD) layer thickness control (etch time is fixed)
this problem now confirmed on chips in centre and at edge of wafer
April, 2003 CMS tracker electronics 10
Fault Diagnosis – lots 5 & 7lot 7 wafer FA just started - this lot showed average 52% yield, so not such severe problem
no definite problem found so far (but ILD thickness also large)
physical coordinates of stuck bit locations in biasregisters provided for both these lots – may be helpful
0,0
6454,6395
Bit 8 Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1
Flip-FlopRegister ISSF<8>
Bias Generator Area
APV25 Complete Chip
X =
1307
X =
1307
X =
1349
X =
1349
X =
1482
X =
1524
X =
1599
X =
1641
X =
1686
X =
1728
X =
1758
X =
1800
X =
1830
X =
1872
X =
1902
X =
1944
X =
1974
X =
2016
ISPARE Y = 105
ICAL Y = 131
CSEL Y = 157
CDRV Y = 183
IPRE Y = 209
IPCASC Y = 235
VFP Y = 261
IPSF Y = 287
IMUXIN Y = 313
VPSP Y = 339
IPSP Y = 365
ISHA Y = 391
VFS Y = 417
ISSF Y = 443
ISSF Y = 443
Notes:
This diagram shows the location of the storage flip-flops in the bias generator area relative to a co-ordinate system defined by pad openings.
The origin is at the bottom right corner of the left columns of pads. The lower left corner of the pad at the right end of the top side is at x=6454, y=6395 microns.
The detail of the bias generator area show rows specific to each register (see labels on the right) where the Y co-ordinate desribes the center line. Within each row there are 8 flip flops with analogue mirrors in between. The horizontal edges are defined in microns along the lower side.
Note that the registers: Mode, Latency and Muxgain are not listed, they are in a separate region of the chip.
Registers CDRV and CSEL appear different from the others: in these cases there are no analogue mirrors, the digital states are output instead.
M J French 21/March/2003
April, 2003 CMS tracker electronics 11
APV Production Plan
(March)(48)Feb.48
Jan 0448Nov.48Oct.48Sept.48July24
June 0324
latest delivery date
no. of wafers
288 (336)
wafer volume will cover our needs assuming 60% yield~ 62,000 (72,500) chips
~ 40 wafers/monthhigh but manageable, 2 wafers/day
2003
2004
April, 2003 CMS tracker electronics 12
SummaryProgress in understanding causes for low yields
2002 lotsLot 4 (33%): V2 underetch (non-contacting vias), ILD thickness close to maximumLot 5 (44%): not yet begun
2003 lotsLot 6 (~0%): M2 layer shorts and extraneous Q2 metal layerLot 5 (52%): FA started, no problem found so far, but ILD thickness also large
Manufacturer’s efforts have been substantial, still ongoing
All problems identified so far associated with “back-end-of-line” production phase
2 free production lots offered and now in fabrication (delivery in ~ few weeks time)foundry proposes to vary ILD thickness (5 steps between process extremes) on one lot with additional measurements after each ILD stage
=> lower overall yield for this lot but valuable information for further production
hope that results of these studies will lead to reduction of low-yield lots
