This document describes a double-sided CMOS-CNT biosensor array with a padless structure for simple bare-die measurements in a medical environment. The biosensor uses carbon nanotubes coated on electrode arrays to detect target molecules. It aims to provide a disposable, low-cost biosensor chip that can be directly measured without additional equipment by interfacing with a PC or cell phone. The padless chip structure eliminates the need for wire bonding or flip-chip packaging, allowing simple bare-die measurements in test tubes.

1. 16.6: A Double-Side CMOS-CNT Biosensor Array with Padless Structure for Simple Bare-Die Measurements
in a Medical Environment
© 2015 IEEE
International Solid-State Circuits Conference 1 of 28
Jinhong Ahn1, Jeaheung Lim1, Seok-Hyang Kim1, Jun-Yeon Yun1,
Changhyun Kim1, Sang-Hoon Hong2, Myoung-Jin Lee3, Youngjune Park1
Seoul National University1
Kyung Hee University2
Chonnam National University3
A Double-side CMOS-CNT Biosensor Array
with Padless Structure for Simple Bare-die
Measurements in a Medical Environment

2. 16.6: A Double-Side CMOS-CNT Biosensor Array with Padless Structure for Simple Bare-Die Measurements
in a Medical Environment
© 2015 IEEE
International Solid-State Circuits Conference 2 of 28
Outline
 Introduction
 Backside Rectification
 CMOS-CNT Sensor Architecture
 Circuit Implementation
 Measurement Results
 Conclusion

3. 16.6: A Double-Side CMOS-CNT Biosensor Array with Padless Structure for Simple Bare-Die Measurements
in a Medical Environment
© 2015 IEEE
International Solid-State Circuits Conference 3 of 28
Our Goals
 Disposable biosensor for simple medical tests
 Bare die direct measurement
 No microfluidics
 PC or cell-phone based measurement
 Cost-effective process solution
 Standard CMOS process with generic gold bumping
 No TSV(Through Silicon Via) process
 Wafer-level nano-material coating without masking process
 High performance and stability
 Higher data rate than current 1-wire communication case
 Stable operation under high power dissipation

4. 16.6: A Double-Side CMOS-CNT Biosensor Array with Padless Structure for Simple Bare-Die Measurements
in a Medical Environment
© 2015 IEEE
International Solid-State Circuits Conference 4 of 28
Motivation
5
5
20
70
CMOS Biosensor
Cost Structure
CMOS CHIP
POST FABRICATION
MICROFLUIDICS
EQUIPMENT
Microfluidics
Packaging
Functionalization
PEN TYPE
READER
METAL PLATE
SENSOR
CHIP
‘PADLESS’
CMOS Biosensor
Bare-Die Direct
Measurement
Virtually “Zero”.
Conventional
CMOS Biosensor
Padless CMOS Chip
Test Tube
Blood
PC

5. 16.6: A Double-Side CMOS-CNT Biosensor Array with Padless Structure for Simple Bare-Die Measurements
in a Medical Environment
© 2015 IEEE
International Solid-State Circuits Conference 5 of 28
Carbon Nanotube(CNT) Biosensor
Carbon nanotube
Au
TargetProbe with
thiol group
+
+
+
+
Common
Ground Pad Sensor
area
V
Gold Electrode
Island
Electrode
Pad
Island
Electrode
Sensing Mechanism
SEM View (CNT + Au particle) Array type sensor by CNT coating
 CNT solution coating on the electrode array
 Selective coating to protect pads from electrical shorts
+

6. 16.6: A Double-Side CMOS-CNT Biosensor Array with Padless Structure for Simple Bare-Die Measurements
in a Medical Environment
© 2015 IEEE
International Solid-State Circuits Conference 6 of 28
Medical Application Procedure
Antibody
Immobilization
Wafer Level
Carbon Nanotube
Coating
Medical
Application
Step 1 Step 2
52 28 30 33 30 67 50 123 31 123 32 147 200 147 52 200 33 33 33 27 93 48 174 116 77 88 112 88 35 129 48 77 103 46 72 69 43 55 58 21 12 51 55 72 114 157 200 200 146 92 69 200 52 126 123 58 92 146 103 92 58 55 58 103
28 38 30 200 47 107 107 54 65 90 67 33 200 200 174 200 28 30 147 133 30 174 30 50 114 53 28 58 30 107 31 147 200 114 86 71 52 114 146 103 72 92 146 75 200 200 114 200 129 52 75 103 92 52 46 103 58 129 58 200 75 92 200 92
88 38 67 62 54 28 174 25 44 133 50 31 200 200 200 147 89 31 107 35 28 133 67 32 58 28 38 28 200 200 29 48 92 103 103 52 72 92 46 157 52 146 83 92 200 200 200 33 52 55 123 55 75 72 75 12 58 58 58 92 200 114 146 200
174 200 62 52 67 107 174 174 48 115 54 174 200 38 39 200 30 147 30 114 90 67 30 68 25 43 174 129 200 200 147 174 46 52 92 75 52 92 52 52 92 114 86 46 114 46 46 46 58 200 52 58 72 103 200 21 41 200 58 92 157 157 92 129
28 43 114 28 28 28 35 174 174 26 43 129 28 133 31 34 30 33 25 38 174 32 133 54 43 93 25 35 33 38 114 77 129 92 52 92 75 55 21 96 58 200 55 129 126 92 200 92 55 126 58 200 92 200 103 92 55 58 129 92 52 52 129 103
112 32 33 114 28 58 23 13 21 25 30 52 67 35 25 133 28 45 30 93 67 119 31 48 33 35 22 200 103 22 28 53 92 58 129 46 129 72 9.6 12 12 52 52 52 146 92 72 103 58 129 75 75 92 126 75 75 55 157 75 58 200 75 52 92
112 95 30 174 43 32 22 103 26 28 72 114 147 33 29 28 28 28 114 29 107 33 14 13 58 29 29 88 28 26 58 77 92 58 72 49 52 58 114 103 29 52 52 200 92 103 58 58 103 75 123 33 114 46 11 10 92 92 75 52 92 52 52 200
28 28 33 10 45 38 55 147 174 50 93 43 28 26 38 32 28 28 48 58 30 16 10 9.6 25 133 28 114 33 67 43 147 200 46 126 55 52 103 52 34 52 52 52 200 52 129 126 55 146 92 129 62 10 10 9 11 49 146 200 52 146 64 52 83
28 55 107 200 119 28 43 43 30 29 31 116 33 129 33 29 33 26 88 27 10 9.8 9.6 10 35 30 22 30 48 200 48 48 52 114 92 92 52 55 52 72 55 103 72 52 58 58 46 92 52 92 46 12 9.6 8.6 8.1 8.3 17 44 35 43 103 72 126 88
88 114 35 133 103 48 67 52 29 67 115 107 33 119 50 30 30 55 100 39 16 10 10 9.6 23 200 19 107 29 200 49 92 58 58 72 103 72 28 92 200 55 52 92 58 46 58 126 129 146 114 49 23 10 10 8.5 9.3 19 139 22 103 123 58 58 200
88 112 31 43 31 25 49 129 25 50 32 38 29 35 32 28 48 52 45 28 67 200 13 16 22 174 174 139 200 107 54 28 55 129 92 55 123 44 34 200 75 58 55 200 75 55 49 129 146 75 129 52 114 200 11 11 22 114 46 52 92 52 147 48
28 93 48 67 38 32 107 50 28 31 28 32 50 119 174 30 34 32 33 35 107 174 33 133 200 200 107 107 174 200 67 34 200 200 83 92 52 60 69 43 123 129 75 129 129 46 52 146 52 58 49 55 114 103 21 10 69 75 52 58 126 77 129 147
112 147 120 147 32 30 107 133 67 107 115 200 200 174 147 30 174 52 58 200 200 200 74 114 13 18 200 200 67 174 107 28 58 114 32 200 157 103 114 114 200 200 39 27 200 147 200 174 58 46 75 52 147 200 123 36 18 19 129 200 112 46 25 67
55 89 41 107 107 93 26 85 200 174 38 133 174 129 200 200 48 174 200 200 200 200 200 200 21 21 200 200 67 67 67 28 55 28 34 52 114 114 146 35 72 69 46 39 147 200 174 200 200 103 200 49 200 200 92 55 14 19 174 28 25 58 26 67
112 72 54 48 31 48 47 67 112 48 147 174 147 200 114 112 147 116 200 200 200 200 200 91 200 200 200 200 33 200 174 90 55 114 200 200 103 92 146 157 46 43 46 114 56 200 55 157 174 174 72 200 139 114 129 157 103 174 147 38 60 92 48 62
77 33 67 34 48 67 200 174 200 114 200 200 174 200 146 174 200 200 30 200 200 43 200 133 62 200 200 129 174 67 147 38 52 103 92 92 114 200 92 92 200 157 96 96 200 147 200 200 200 147 200 200 92 157 92 114 107 28 26 33 28 38 35 62
114 28 43 133 34 31 200 17 112 52 147 147 147 200 174 133 200 200 200 200 67 46 22 114 53 119 112 174 200 200 50 54 200 200 129 92 68 114 52 22 49 200 157 200 114 157 114 200 139 200 92 52 65 39 39 200 114 26 32 26 25 25 27 48
71 45 114 103 200 29 200 35 200 174 52 62 50 21 29 200 200 200 200 200 38 200 147 133 54 48 174 115 200 200 133 147 46 92 58 92 174 114 52 46 114 157 28 43 92 14 21 92 200 200 83 92 35 147 40 46 48 58 55 25 52 25 25 38
86 68 28 10 25 31 33 58 112 174 107 47 67 23 16 25 200 200 200 147 47 107 29 47 200 31 174 72 200 200 45 30 58 86 58 10 114 157 114 129 114 114 146 92 75 23 13 123 200 92 75 200 35 49 46 46 52 92 35 48 58 39 52 38
77 38 28 28 48 38 133 33 48 200 174 200 107 133 35 107 200 200 174 200 48 107 31 107 133 174 87 45 50 67 67 38 92 52 49 46 146 146 114 146 92 114 114 114 114 103 92 72 92 72 103 69 112 92 92 35 35 67 24 147 45 38 38 147
53 147 29 200 58 48 35 26 93 48 133 67 44 28 34 103 30 174 51 33 50 33 52 47 147 147 133 107 50 67 67 38 126 200 146 52 86 103 114 114 200 200 200 174 146 200 52 80 200 48 96 69 25 26 26 52 26 53 114 72 53 77 53 27
76 147 200 28 119 58 47 34 30 174 133 133 114 25 45 70 200 107 200 67 28 48 28 200 174 59 174 67 50 90 29 53 58 75 92 92 103 114 103 103 200 200 200 174 92 72 55 46 147 72 35 52 39 25 26 26 28 25 28 40 53 53 53 26
131 62 33 147 93 119 35 139 107 147 200 31 33 31 31 48 67 123 147 133 28 54 200 33 48 107 67 48 67 121 133 200 92 92 114 75 69 92 103 92 200 200 174 114 55 55 92 200 38 77 92 200 28 53 25 38 25 28 26 25 25 46 114 49
85 147 38 33 38 34 44 52 30 67 174 107 139 38 52 34 107 200 200 200 133 200 46 37 67 52 147 48 200 147 47 26 146 52 129 200 83 103 200 92 96 139 200 200 72 58 92 86 200 52 200 147 40 25 30 32 25 25 25 43 52 27 80 58
68 96 40 90 55 28 58 139 48 56 107 119 174 200 174 200 67 200 107 174 107 147 200 200 200 200 174 200 67 133 48 28 52 129 146 200 200 75 200 200 37 92 200 200 146 92 200 147 69 25 25 28 72 39 46 103 49 46 123 46 55 103 83 28
114 93 45 58 48 133 93 48 32 103 30 32 133 174 133 200 48 200 133 200 67 200 25 133 200 200 200 200 35 200 93 96 123 55 146 92 114 37 200 200 37 25 114 114 52 200 200 58 52 25 25 46 103 52 42 26 49 52 75 49 129 38 114 28
147 43 43 88 48 48 93 83 31 67 107 29 62 200 107 54 67 200 30 32 147 67 67 89 200 129 200 31 67 200 29 33 52 200 83 200 114 114 96 200 157 114 200 92 86 55 133 69 26 25 25 22 25 21 58 25 92 114 114 28 174 86 77 58
112 48 58 58 44 31 33 30 139 54 48 67 174 200 107 107 50 200 51 200 48 174 200 200 200 200 200 200 174 67 54 48 103 52 52 72 157 92 103 114 114 200 114 200 52 55 90 200 26 25 25 39 25 25 25 25 28 53 28 25 27 55 48 174
96 53 77 68 33 88 88 52 52 29 30 90 30 34 107 48 107 34 33 47 103 174 200 200 200 200 200 200 107 147 52 103 92 58 126 52 58 114 114 114 114 103 92 103 147 49 72 39 24 25 25 28 25 27 26 28 77 114 114 114 103 103 52 53
52 77 96 53 112 88 100 200 30 26 147 107 116 89 89 200 32 35 67 58 200 200 147 200 200 200 200 129 29 103 93 28 103 52 52 55 52 114 55 103 157 114 75 157 133 49 77 45 24 25 75 107 38 28 28 100 96 77 96 77 114 52 114 28
49 58 114 52 77 53 28 72 29 47 200 43 50 29 107 28 200 22 111 174 200 107 31 129 114 200 114 48 90 67 58 131 103 146 75 200 52 129 146 157 92 103 55 146 67 26 60 46 26 25 25 62 77 40 40 200 51 28 77 67 28 77 114 47
52 45 114 96 114 96 86 112 88 28 72 33 28 58 114 28 43 28 43 43 50 50 48 33 47 107 47 200 48 45 33 58 103 174 103 114 92 200 58 200 52 200 103 92 93 58 25 48 67 58 72 48 107 200 200 114 67 52 38 147 32 67 67 200
평균 = 평균 =47.1 57
52 28 30 33 30 67 50 123 31 123 32 147 200 147 52 200 33 33 33 27 93 48 174 116 77 88 112 88 35 129 48 77 103 46 72 69 43 55 58 21 12 51 55 72 114 157 200 200 146 92 69 200 52 126 123 58 92 146 103 92 58 55 58 103
28 38 30 200 47 107 107 54 65 90 67 33 200 200 174 200 28 30 147 133 30 174 30 50 114 53 28 58 30 107 31 147 200 114 86 71 52 114 146 103 72 92 146 75 200 200 114 200 129 52 75 103 92 52 46 103 58 129 58 200 75 92 200 92
88 38 67 62 54 28 174 25 44 133 50 31 200 200 200 147 89 31 107 35 28 133 67 32 58 28 38 28 200 200 29 48 92 103 103 52 72 92 46 157 52 146 83 92 200 200 200 33 52 55 123 55 75 72 75 12 58 58 58 92 200 114 146 200
174 200 62 52 67 107 174 174 48 115 54 174 200 38 39 200 30 147 30 114 90 67 30 68 25 43 174 129 200 200 147 174 46 52 92 75 52 92 52 52 92 114 86 46 114 46 46 46 58 200 52 58 72 103 200 21 41 200 58 92 157 157 92 129
28 43 114 28 28 28 35 174 174 26 43 129 28 133 31 34 30 33 25 38 174 32 133 54 43 93 25 35 33 38 114 77 129 92 52 92 75 55 21 96 58 200 55 129 126 92 200 92 55 126 58 200 92 200 103 92 55 58 129 92 52 52 129 103
112 32 33 114 28 58 23 13 21 25 30 52 67 35 25 133 28 45 30 93 67 119 31 48 33 35 22 200 103 22 28 53 92 58 129 46 129 72 9.6 12 12 52 52 52 146 92 72 103 58 129 75 75 92 126 75 75 55 157 75 58 200 75 52 92
112 95 30 174 43 32 22 103 26 28 72 114 147 33 29 28 28 28 114 29 107 33 14 13 58 29 29 88 28 26 58 77 92 58 72 49 52 58 114 103 29 52 52 200 92 103 58 58 103 75 123 33 114 46 11 10 92 92 75 52 92 52 52 200
28 28 33 10 45 38 55 147 174 50 93 43 28 26 38 32 28 28 48 58 30 16 10 9.6 25 133 28 114 33 67 43 147 200 46 126 55 52 103 52 34 52 52 52 200 52 129 126 55 146 92 129 62 10 10 9 11 49 146 200 52 146 64 52 83
28 55 107 200 119 28 43 43 30 29 31 116 33 129 33 29 33 26 88 27 10 9.8 9.6 10 35 30 22 30 48 200 48 48 52 114 92 92 52 55 52 72 55 103 72 52 58 58 46 92 52 92 46 12 9.6 8.6 8.1 8.3 17 44 35 43 103 72 126 88
88 114 35 133 103 48 67 52 29 67 115 107 33 119 50 30 30 55 100 39 16 10 10 9.6 23 200 19 107 29 200 49 92 58 58 72 103 72 28 92 200 55 52 92 58 46 58 126 129 146 114 49 23 10 10 8.5 9.3 19 139 22 103 123 58 58 200
88 112 31 43 31 25 49 129 25 50 32 38 29 35 32 28 48 52 45 28 67 200 13 16 22 174 174 139 200 107 54 28 55 129 92 55 123 44 34 200 75 58 55 200 75 55 49 129 146 75 129 52 114 200 11 11 22 114 46 52 92 52 147 48
28 93 48 67 38 32 107 50 28 31 28 32 50 119 174 30 34 32 33 35 107 174 33 133 200 200 107 107 174 200 67 34 200 200 83 92 52 60 69 43 123 129 75 129 129 46 52 146 52 58 49 55 114 103 21 10 69 75 52 58 126 77 129 147
112 147 120 147 32 30 107 133 67 107 115 200 200 174 147 30 174 52 58 200 200 200 74 114 13 18 200 200 67 174 107 28 58 114 32 200 157 103 114 114 200 200 39 27 200 147 200 174 58 46 75 52 147 200 123 36 18 19 129 200 112 46 25 67
55 89 41 107 107 93 26 85 200 174 38 133 174 129 200 200 48 174 200 200 200 200 200 200 21 21 200 200 67 67 67 28 55 28 34 52 114 114 146 35 72 69 46 39 147 200 174 200 200 103 200 49 200 200 92 55 14 19 174 28 25 58 26 67
112 72 54 48 31 48 47 67 112 48 147 174 147 200 114 112 147 116 200 200 200 200 200 91 200 200 200 200 33 200 174 90 55 114 200 200 103 92 146 157 46 43 46 114 56 200 55 157 174 174 72 200 139 114 129 157 103 174 147 38 60 92 48 62
77 33 67 34 48 67 200 174 200 114 200 200 174 200 146 174 200 200 30 200 200 43 200 133 62 200 200 129 174 67 147 38 52 103 92 92 114 200 92 92 200 157 96 96 200 147 200 200 200 147 200 200 92 157 92 114 107 28 26 33 28 38 35 62
114 28 43 133 34 31 200 17 112 52 147 147 147 200 174 133 200 200 200 200 67 46 22 114 53 119 112 174 200 200 50 54 200 200 129 92 68 114 52 22 49 200 157 200 114 157 114 200 139 200 92 52 65 39 39 200 114 26 32 26 25 25 27 48
71 45 114 103 200 29 200 35 200 174 52 62 50 21 29 200 200 200 200 200 38 200 147 133 54 48 174 115 200 200 133 147 46 92 58 92 174 114 52 46 114 157 28 43 92 14 21 92 200 200 83 92 35 147 40 46 48 58 55 25 52 25 25 38
86 68 28 10 25 31 33 58 112 174 107 47 67 23 16 25 200 200 200 147 47 107 29 47 200 31 174 72 200 200 45 30 58 86 58 10 114 157 114 129 114 114 146 92 75 23 13 123 200 92 75 200 35 49 46 46 52 92 35 48 58 39 52 38
77 38 28 28 48 38 133 33 48 200 174 200 107 133 35 107 200 200 174 200 48 107 31 107 133 174 87 45 50 67 67 38 92 52 49 46 146 146 114 146 92 114 114 114 114 103 92 72 92 72 103 69 112 92 92 35 35 67 24 147 45 38 38 147
53 147 29 200 58 48 35 26 93 48 133 67 44 28 34 103 30 174 51 33 50 33 52 47 147 147 133 107 50 67 67 38 126 200 146 52 86 103 114 114 200 200 200 174 146 200 52 80 200 48 96 69 25 26 26 52 26 53 114 72 53 77 53 27
76 147 200 28 119 58 47 34 30 174 133 133 114 25 45 70 200 107 200 67 28 48 28 200 174 59 174 67 50 90 29 53 58 75 92 92 103 114 103 103 200 200 200 174 92 72 55 46 147 72 35 52 39 25 26 26 28 25 28 40 53 53 53 26
131 62 33 147 93 119 35 139 107 147 200 31 33 31 31 48 67 123 147 133 28 54 200 33 48 107 67 48 67 121 133 200 92 92 114 75 69 92 103 92 200 200 174 114 55 55 92 200 38 77 92 200 28 53 25 38 25 28 26 25 25 46 114 49
85 147 38 33 38 34 44 52 30 67 174 107 139 38 52 34 107 200 200 200 133 200 46 37 67 52 147 48 200 147 47 26 146 52 129 200 83 103 200 92 96 139 200 200 72 58 92 86 200 52 200 147 40 25 30 32 25 25 25 43 52 27 80 58
68 96 40 90 55 28 58 139 48 56 107 119 174 200 174 200 67 200 107 174 107 147 200 200 200 200 174 200 67 133 48 28 52 129 146 200 200 75 200 200 37 92 200 200 146 92 200 147 69 25 25 28 72 39 46 103 49 46 123 46 55 103 83 28
114 93 45 58 48 133 93 48 32 103 30 32 133 174 133 200 48 200 133 200 67 200 25 133 200 200 200 200 35 200 93 96 123 55 146 92 114 37 200 200 37 25 114 114 52 200 200 58 52 25 25 46 103 52 42 26 49 52 75 49 129 38 114 28
147 43 43 88 48 48 93 83 31 67 107 29 62 200 107 54 67 200 30 32 147 67 67 89 200 129 200 31 67 200 29 33 52 200 83 200 114 114 96 200 157 114 200 92 86 55 133 69 26 25 25 22 25 21 58 25 92 114 114 28 174 86 77 58
112 48 58 58 44 31 33 30 139 54 48 67 174 200 107 107 50 200 51 200 48 174 200 200 200 200 200 200 174 67 54 48 103 52 52 72 157 92 103 114 114 200 114 200 52 55 90 200 26 25 25 39 25 25 25 25 28 53 28 25 27 55 48 174
96 53 77 68 33 88 88 52 52 29 30 90 30 34 107 48 107 34 33 47 103 174 200 200 200 200 200 200 107 147 52 103 92 58 126 52 58 114 114 114 114 103 92 103 147 49 72 39 24 25 25 28 25 27 26 28 77 114 114 114 103 103 52 53
52 77 96 53 112 88 100 200 30 26 147 107 116 89 89 200 32 35 67 58 200 200 147 200 200 200 200 129 29 103 93 28 103 52 52 55 52 114 55 103 157 114 75 157 133 49 77 45 24 25 75 107 38 28 28 100 96 77 96 77 114 52 114 28
49 58 114 52 77 53 28 72 29 47 200 43 50 29 107 28 200 22 111 174 200 107 31 129 114 200 114 48 90 67 58 131 103 146 75 200 52 129 146 157 92 103 55 146 67 26 60 46 26 25 25 62 77 40 40 200 51 28 77 67 28 77 114 47
52 45 114 96 114 96 86 112 88 28 72 33 28 58 114 28 43 28 43 43 50 50 48 33 47 107 47 200 48 45 33 58 103 174 103 114 92 200 58 200 52 200 103 92 93 58 25 48 67 58 72 48 107 200 200 114 67 52 38 147 32 67 67 200
평균 = 평균 =47.1 57
Resistance Color Map
@ Step 1
Resistance Color Map
@ Step 2
Statistical Analysis
‘PADLESS’
CMOS Wafer
Antibody
Serum
Resistance(KΩ)
CumulativeProbability

7. 16.6: A Double-Side CMOS-CNT Biosensor Array with Padless Structure for Simple Bare-Die Measurements
in a Medical Environment
© 2015 IEEE
International Solid-State Circuits Conference 7 of 28
Padless Sensor Chip
 2 terminal device with double sided metal contacts
- A wide ring structure around the sensor area (VF)
- A plate structure for both power and single I/O line (VB)
 Diode rectifier and voltage regulator from backside
_
+ Vint_ref
_
+
DOUT
DIN
CMOS
Circuits
I/O Buffer
VSS
VSS
Vref
VDD
VB
VFBackside Terminal (VB)
Front side Terminal (VF)
Sensor Surface

8. 16.6: A Double-Side CMOS-CNT Biosensor Array with Padless Structure for Simple Bare-Die Measurements
in a Medical Environment
© 2015 IEEE
International Solid-State Circuits Conference 8 of 28
Outline
 Introduction
 Backside Rectification
 CMOS-CNT Sensor Architecture
 Circuit Implementation
 Measurement Results
 Conclusion

9. 16.6: A Double-Side CMOS-CNT Biosensor Array with Padless Structure for Simple Bare-Die Measurements
in a Medical Environment
© 2015 IEEE
International Solid-State Circuits Conference 9 of 28
Backside Rectification Structure
 Diode rectifier using P-substrate to Deep N-Well PN junction
- All active devices are enclosed by Deep N-Well
- On-chip capacitance between VDD and VSS(VF)
 Backside metal connection to I/O buffer through P-substrate
Backside Metal Plate
Front side Metal
Back side Metal (VB)
Front side Metal (VF)
VDD
P-substrate
Deep N-well
P-WellN-Well P-Well
VSS I/O
n+
p+
P_gate
p+ n+
p+
N_gate

10. 16.6: A Double-Side CMOS-CNT Biosensor Array with Padless Structure for Simple Bare-Die Measurements
in a Medical Environment
© 2015 IEEE
International Solid-State Circuits Conference 10 of 28
 Backside rectification shows no latch-up up to -20V
- Reverse p-n-p structure has small current gain due to the
low emitter efficiency and small emitter-collector area ratio
Merits of Backside Rectification(1)
- Latch-up immunity -
P-substrate
p+
P-Well
VF
VB
DNW
20
40
60
80
100
-20
I(mA)
-5-10-15-20 50
VF-VB(V)
64x64 Array Chip
32x32 Array Chip
A
V
+
-
VF
VB
Operation Range
(0V to -4.0V)
P-
N
P+
VB
VF

11. 16.6: A Double-Side CMOS-CNT Biosensor Array with Padless Structure for Simple Bare-Die Measurements
in a Medical Environment
© 2015 IEEE
International Solid-State Circuits Conference 11 of 28
Merits of Backside Rectification(2)
 Rs produces ground bounce for front side rectification only
p+
N-Well
P-substrate
n+ p+
P-Well
VDDVF VSS
VB
RS
N-Well
P-substrate
n+ p+
P-Well
VDD VF(=VSS)
VB
RS
Deep N-well
(Front side Rectification) (Backside Rectification)
- Ground Bounce Noise -

12. 16.6: A Double-Side CMOS-CNT Biosensor Array with Padless Structure for Simple Bare-Die Measurements
in a Medical Environment
© 2015 IEEE
International Solid-State Circuits Conference 12 of 28
Outline
 Introduction
 Backside Rectification
 CMOS-CNT Sensor Architecture
 Circuit Implementation
 Measurement Results
 Conclusion

13. 16.6: A Double-Side CMOS-CNT Biosensor Array with Padless Structure for Simple Bare-Die Measurements
in a Medical Environment
© 2015 IEEE
International Solid-State Circuits Conference 13 of 28
Padless Sensor Chip Architecture
V Program (/8)
Sensor SW (/16)
RW
R/W
Din Counter
256 Sensor Group Decoder
Output CircuitInput Circuit OSC.
Voltage Generators
In Out
VB (Backside)
VF (Front Side)
Selected
Electrodes
4K Padless Sensor Chip Layout
A to D

14. 16.6: A Double-Side CMOS-CNT Biosensor Array with Padless Structure for Simple Bare-Die Measurements
in a Medical Environment
© 2015 IEEE
International Solid-State Circuits Conference 14 of 28
Flexible Sensor Electrode Structure
 When 1 of 16 electrodes is selected by a data input signal,
the remaining 15 electrodes are automatically configured
to VSS, forming a surrounding CNT resistance sensor
: Unselected Electrodes (VSS)
: Selected Electrodes
S
Surrounding
CNT Resistance of
Selected Electrode
CNT
Coated
Array
1 Operational Amplifier +
16 programmable Switches
Measurement unit :

15. 16.6: A Double-Side CMOS-CNT Biosensor Array with Padless Structure for Simple Bare-Die Measurements
in a Medical Environment
© 2015 IEEE
International Solid-State Circuits Conference 15 of 28
Gold Plated Sensor Electrodes
 Front side metal and dummy electrodes are the same
sensor ground (VSS) as unselected electrodes
 Wafer-level carbon nanotube dip coating is possible
Front side metal (VSS)
Gold Plated Area
CNTDipCoating
Measurement
Unit
Dummy
Electrodes
(VSS)
35μm
15μm

16. 16.6: A Double-Side CMOS-CNT Biosensor Array with Padless Structure for Simple Bare-Die Measurements
in a Medical Environment
© 2015 IEEE
International Solid-State Circuits Conference 16 of 28
Die Micrographs
16 CNT Resistance Sensors.
Front side Metal
64x64 Sensor Array
3.9mm
3.7 mm
1.9 mm
2.3mm
32x32 Sensor Array
Front side Metal
(Gold plated 64x64 and 32x32 sensor chips)
(Controller chip)

17. 16.6: A Double-Side CMOS-CNT Biosensor Array with Padless Structure for Simple Bare-Die Measurements
in a Medical Environment
© 2015 IEEE
International Solid-State Circuits Conference 17 of 28
Outline
 Introduction
 Backside Rectification
 CMOS-CNT Sensor Architecture
 Circuit Implementation
 Measurement Results
 Conclusion

18. 16.6: A Double-Side CMOS-CNT Biosensor Array with Padless Structure for Simple Bare-Die Measurements
in a Medical Environment
© 2015 IEEE
International Solid-State Circuits Conference 18 of 28
Data Write Control Circuit
 Short and Vref limited pulses are made at Tx transitions
 Toggle Flip-Flop recovers the original Tx signals
_
+
IOref
I/O
M1
I/O voltage
Regulator
Tx
_
+
Vref
Data
Input
I/O
Vref
Comparator
Long Pulse generator
+
_
VDD
D Q
QB
Data
Input
WRITE
Toggle F/F
Input
Comparator
I/O Line
I/O
Tx
Vref
C
VDD
Pulse
Generator
5V
0V
IOref
5V
VDD
Controller Padless Sensor Chip
VB
VF

19. 16.6: A Double-Side CMOS-CNT Biosensor Array with Padless Structure for Simple Bare-Die Measurements
in a Medical Environment
© 2015 IEEE
International Solid-State Circuits Conference 19 of 28
CDNW
CMOS + CDNW
x VPULSE
~ 0.16 VPULSE
Deep N-Well
MOS Capacitor
12.8 x 80pF(DNW) = 1.02nF
3.2 x 1700pF(MOS) = 5.44nF
MOS
Capacitance
DNW
Capacitance
I/O
VDD
VDD Droop by I/O Signal Coupling
 DNW Capacitance is less than 1/20 of MOS Capacitance
 VDD Drooping is managed to <1/5VDD using MOS capacitor
Area(mm2) Capacitance/mm2
Tx
VDD
Drooping
I/O
Recovered
Tx at Sensor
1
2
3
4
Voltage(V)
0
0.5μs
Time

20. 16.6: A Double-Side CMOS-CNT Biosensor Array with Padless Structure for Simple Bare-Die Measurements
in a Medical Environment
© 2015 IEEE
International Solid-State Circuits Conference 20 of 28
Data Read Control Circuit
 Tri-state I/O control by detecting I/O voltage level (Vref)
- CPG signal makes the I/O line to float (by turning off M2)
and receives the data outputs from the sensor chip
 Double-sampling amplifier to sense the data output.
SW1
SW2
CPG
Rclk
I/O Vref
“L” “H”
SW1
SW2
+
_ Dout
_
+
Vref
CPG
Circuit
I/O
R
Rclk
SW2
_
+
IOref
I/O
Latch
M1
M2
Double sampling
difference amplifier
I/O voltage
Regulator
Comparator
Minimum
Delay
S Q
R
Constant
Delay
+
_
Vref
Output
Data
READ
C
VDD
DQ
Output
Buffer
Constant Pulse
Generator (CPG)
I/O Switch
Input
Comparator
I/O Line
CPG
I/O Vref
“L
”
“H
”
Output
Data
Sensor
Output
Last Stage
of FIFO
Controller Padless Sensor Chip
CPG
Circuit
VB
VF

21. 16.6: A Double-Side CMOS-CNT Biosensor Array with Padless Structure for Simple Bare-Die Measurements
in a Medical Environment
© 2015 IEEE
International Solid-State Circuits Conference 21 of 28
Flippable Bare-Die Probing
 Reverse I/O biasing from controller with exchanged
sensor terminals gives identical sensor operation
 Mode selection of flipped(Mode-1) or nonflipped(Mode-2)
I/O
CPG
_
+ IOref1
I/O
IOref2
I/O
Mode2
Mode1
Mode1
Mode2
_
+
Vref1
_+ Vref2
Rclk
I/O
_
+
VCC
VG1
VG2
IOref2
IOref1
Mode1 Mode2
Vref1
Vref2
Difference
Amplifier
Mode-1
VB
VFController
VCC
VB
VF
Single
Contact
Probe
Mode-2
I/O VCC
VB
VB
VF
Controller
VCC
I/O
VF
Single
Contact
Probe
VCC

22. 16.6: A Double-Side CMOS-CNT Biosensor Array with Padless Structure for Simple Bare-Die Measurements
in a Medical Environment
© 2015 IEEE
International Solid-State Circuits Conference 22 of 28
Common Line UART Operation
 Read command code is used for a sensor activation
 Interleaved sense and I/O operations for low noise
Din
Dout
VDD
Din
Dout
VDD
Rx
Tx
Rclk
Auto-
Write Mode
Return
º º º
º º º
Data Write for
Sensor Configuration
Read Command Code + Sensor ID
Sensor Data Read (256 cycles)
Tx
W/R
Rclk
Write to Read
Transition
Sensing and ADC Operation
Default Write Mode

23. 16.6: A Double-Side CMOS-CNT Biosensor Array with Padless Structure for Simple Bare-Die Measurements
in a Medical Environment
© 2015 IEEE
International Solid-State Circuits Conference 23 of 28
Outline
 Introduction
 Backside Rectification
 CMOS-CNT Sensor Architecture
 Circuit Implementation
 Measurement Results
 Conclusion

24. 16.6: A Double-Side CMOS-CNT Biosensor Array with Padless Structure for Simple Bare-Die Measurements
in a Medical Environment
© 2015 IEEE
International Solid-State Circuits Conference 24 of 28
Measurement Setup
 Silicon chip is thinned down to 300μm to reduce Rs
 Reliable backside metallization (V/Ni/AuGeSb/Au)
 LED package is used for stable biosensor measurement
 USB/UART converter for PC interface
Test Board Structure
(2 test chips on a board.)
USB/UART Converter
Controller
Socket
Epoxy
Electrode 2
(Backside)
Single
Wire
Bonding
Plastic
Well
Packaging using LED leadframe
Electrode 1
(Front side)

25. 16.6: A Double-Side CMOS-CNT Biosensor Array with Padless Structure for Simple Bare-Die Measurements
in a Medical Environment
© 2015 IEEE
International Solid-State Circuits Conference 25 of 28
Measurement Results
Tx
Tx
I/O
I/O
Rx
I/O
Rx
I/O
0.1 μs
0.1 μs
0.2 μs0.2 μs
0.2 μs0.2 μs
Mode-1 Write signal
Mode-2 Write signal
Mode-1 Read signal
Mode-2 Read signal

26. 16.6: A Double-Side CMOS-CNT Biosensor Array with Padless Structure for Simple Bare-Die Measurements
in a Medical Environment
© 2015 IEEE
International Solid-State Circuits Conference 26 of 28
Resistance Color Map
 4-times repeated CNT resistance measurement
results for 2 chips
0 Ω 100KΩ

27. 16.6: A Double-Side CMOS-CNT Biosensor Array with Padless Structure for Simple Bare-Die Measurements
in a Medical Environment
© 2015 IEEE
International Solid-State Circuits Conference 27 of 28
Performance Summary
Process Technology 0.35μm CMOS process
(MagnaChip)
Controller Voltage 5.0 V
I/O Line Voltage 4.0 V
Sensor Chip Voltage 3.3 V, 2.5V(internal)
Maximum Data Rate 2.0 Mbps
Resistance Range 5KΩ(min.), 100KΩ(max.)
ADC 2.5V, 8 bit SAR
VDD Latch-up Voltage > 20V
Power consumption range 5 mW(min.), 150 mW(max.)
Chip Area 1.9 x 2.3 mm2 (1K Sensor)
3.7 x 3.9 mm2 (4K Sensor)
1.9 x 2.3 mm2 (Controller)

28. 16.6: A Double-Side CMOS-CNT Biosensor Array with Padless Structure for Simple Bare-Die Measurements
in a Medical Environment
© 2015 IEEE
International Solid-State Circuits Conference 28 of 28
Conclusions
 Developed a double-side CMOS-CNT sensor array
based on a 0.35-μm standard CMOS process
 Can take advantage of backside rectifying diode with a
high latch-up resistance and low ground bounce noise
 A new single wire communication scheme for UART
communication is developed
 A stable operation under 150mW sensing power at
2MHz data rate can be achieved