Table 1: Manufacturing Process of a Compliant Switch

Step No. General step Input Detailed step Material Temp./ºC Time Pressure OtherData/Comments Result/Output
1 Piranha Etch plain wafer 500 µm etch bath H2O2:H2SO4
(1:1)		 120 10 min     cleaned wafer
2 rinse H2O   ~15 min    
3 dry N2        
4 Lithography I: Circuits cleaned wafer adhesion promoter HMDS   30 s   3500 rpm wafer w/ patterned PR for transmission lines
5 wait     10 s    
6 negative PR AZ 5214   30 s   3500 rpm
thickness: ~1.5 µm
7 softbake   105 1 min   softbake on hotplate
8 mask alignment         mask: standard 4" chromium mask
9 exposure     4.5 s    
10 hardbake   130 1 min   hardbake on hotplate
11 flood expose     90 s   expose w/o mask 
12 development MF 327   20-40 s    
13 rinse H2O        
14 dry N2        
15 descum plasma etcher w/ O2   1 min 250 mT power: 100 W
16 Installation of Transmission Lines wafer w/ patterned PR for transmissionlines evaporation Ti 500 Å
Au 8000 Å		     < 1*10-6 Torr   wafer w/ transmission lines
17 liftoff PRS 2000 (hot) 30-60 min    
18 rinse H2O        
19 dry N2        
20 Deposition of Si3N4 as Passivation Layer wafer w/ transmission lines PECVD deposition of Si3N4 SiH4 - 100 sccm
He - 990 sccm
NH3 - 10 sccm
N2 - 900 sccm		 400 ~6.5 min   thickness: 1000 Å
power: 100 W
rate: ~150 Å/min		 wafer w/ transmission lines partially covered with Si3N4
21 adhesion promoter HMDS   30 s   3500 rpm
22 wait     10 s    
23 negative PR AZ 5214   30 s   3500 rpm
thickness: ~1.5 µm
24 softbake   105 1 min   softbake on hotplate
25 mask alignment         mask: standard 4" chromium mask
26 exposure     4.5 s    
27 hardbake   130 1 min   hardbake on hotplate
28 flood expose     90 s   expose w/o mask
29 development MF 327   20-40 s    
30 rinse H2O        
31 dry N2        
32 descum plasma etcher w/ O2   1 min 250 mT power: 100 W
33 Si3N4 etch plasma etcher w/ CF4 - 25 sccm
O2 - 0.5 sccm		   5 min 250 mT power: 100 W
34 removal of PR ACE
IPA		   30 s
 s		    
35 dry N2        
36 descum plasma etcher w/ O2   1 min 250 mT power: 100 W
37 1st Sacrificial Layer wafer w/ transmission lines partially covered with Si3N4 adhesion promoter VM 651   30 s   3000 rpm wafer covered w/ 1st sacrificial layer
38 wait     20 s    
39 apply polyimide PF 2545        
40 wait     (until PF is spread)    
41 spin PF 2545   30 s   2000 rpm
thickness: 3-4 µm
42 bake   150 30 min   bake in oven
43 evaporation Ti 500 Å     <1*10-6 Torr  
44 Lithography II: Beam Anchor wafer covered w/ 1st sacrificial layer adhesion promoter HMDS   30 s   3500 rpm wafer w/ patterned PR for beam anchors
45 wait     10 s    
46 positive PR 1813   30 s   3500 rpm
thickness: ~1.5 µm
47 softbake   105 1 min   softbake on hotplate
48 mask alignment          
49 exposure     6 s    
50 development MP 351:DI H2O (1:5)   17 s    
51 rinse H2O        
52 dry N2        
53 hardbake   130 1 min   hardbake on hotplate
54 Definition of Anchorpoints wafer w/ patterned PR for beam anchors etch Ti HF:DI H2O (1:10)   5 s     wafer w/ prepared anchorpoints for beam
55 rinse H2O        
56 dry N2        
57 etch polyimide MF 351:DI H2O (1:5)   5 min    
58 rinse H2O        
59 dry N2        
60 remove PR ACE
IPA		   30 s
30 s		    
61 dry N2        
62 descum plasma etcher w/ O2   1 min 250 mT power: 100 W
63 remove Ti HF:DI H2O (1:10)   8 s    
64 rinse H2O        
65 dry N2        
66 evaporation Ti 250 Å
Ni 750 Å		     <1*10-6 Torr  
67 Lithography III: Beam wafer w/ prepared anchorpoints for beam adhesion promoter HMDS   30 s   3500 rpm wafer w/ patterned PR for beam
68 wait     10 s    
69 positive PR 1827   30 s   3500 rpm
thickness: ~3 µm
70 softbake   105 1 min   softbake on hotplate
71 mask alignment          
72 exposure     15 s    
73 development MP 351:DI H2O (1:5)   25 s    
74 rinse H2O        
75 dry N2        
76 hardbake   130 1 min   hardbake on hotplate
77 descum plasma etcher w/ O2   1 min 250 mT power: 100 W
78 Plating of Ni wafer w/ patterned PR for beam electroplating Ni 50 20 min   current: 1.5 mA
thickness: 2 µm
area: ~0.6 cm2
spin bar: 100 rpm		 wafer w/ beam
79 rinse H2O        
80 dry N2        
81 remove PR ACE
IPA		   30 s
30 s		    
82 dry N2        
83 descum plasma etcher w/ O2   1 min 250 mT power: 100 W
84 remove Ni (750 Å) HCL:DI H2O (1:1)   ~5 min    
85 rinse H2O        
86 dry N2        
87 remove Ti (250 Å) HF:DI H2O (1:10)   5 s    
88 rinse H2O        
89 dry N2        
90 Deposition of Si3N4 as Passivation Layer wafer w/ beam sputtering Si3N4 Ar - 30 sccm     7 mT source: RF 
700 W rot. -> 50 Å/min
300 W static -> 170 Å/min
thickness: 2000 Å		 wafer w/ beam partially covered w/ passivation layer
91 adhesion promoter HMDS   30 s   3500 rpm
92 wait     10 s    
93 negative PR AZ 5214   30 s   3500 rpm
thickness: ~1.5 µm
94 softbake   105 1 min   softbake on hotplate
95 mask alignment         mask: standard 4" chromium mask
96 exposure     4.5 s    
97 hardbake   130 1 min   hardbake on hotplate
98 flood expose     90 s   expose w/o mask
99 development MF 327   20-40 s    
100 rinse H2O        
101 dry N2        
102 descum plasma etcher w/ O2   1 min 250 mT power: 100 W
103 Si3N4 etch plasma etcher w/ CF4 - 25 sccm
O2 - 0.5 sccm		   5 min 250 mT power: 100 W
104 rinse H2O        
105 dry N2        
106 removal of PR ACE
IPA		   30 s
30 s		    
107 dry N2        
108 descum plasma etcher w/ O2   1 min 250 mT power: 100 W
109 2nd Sacrificial Layer wafer w/ beam partially covered w/ passivation layer apply polyimide PF 2545         wafer covered w/ 2nd sacrificial layer
110 spin PF 2545   30 s   6000 rpm
thickness: ~1 µm
111 softbake   150 30 min   bake in oven
112 evaporation Ti 500 Å     <1*10-6 Torr  
113 Lithography IV: Electrode Anchor wafer covered w/ 2nd sacrificial layer adhesion promoter HMDS   30 s   3500 rpm wafer w/ patterned PR for electrode anchors
114 wait     10 s    
115 positive PR 1813   30 s   3500 rpm
thickness: ~1.5 µm
116 softbake   105 1 min   softbake on hotplate
117 mask alignment          
118 exposure     6 s    
119 development MP 351:DI H2O (1:5)   17 s    
120 rinse H2O        
121 dry N2        
122 hardbake   130 1 min   hardbake on hotplate
123 Definition of Anchorpoints wafer w/ patterned PR for electrode anchors etch Ti HF:DI H2O (1:10)   5 s     wafer w/ prepared anchorpoints for electrode
124 rinse H2O        
125 dry N2        
126 etch polyimide MF 351:DI H2O (1:5)   5 min    
127 rinse H2O        
128 dry N2        
129 remove PR ACE
IPA		   30 s
30 s		    
130 dry N2        
131 descum plasma etcher w/ O2   1 min 250 mT power: 100 W
132 remove Ti HF:DI H2O (1:10)   8 s    
133 rinse H2O        
134 dry N2        
135 evaporation Ti 250 Å
Ni 750 Å		     <1*10-6 Torr  
136 Lithography V: Electrode wafer w/ prepared anchorpoints for electrode adhesion promoter HMDS   30 s   3500 rpm wafer w/ patterned PR for electrode
137 wait     10 s    
138 positive PR 1827   30 s   3500 rpm
thickness: ~3 µm
139 softbake   105 1 min   softbake on hotplate
140 mask alignment          
141 exposure     15 s    
142 development MP 351:DI H2O (1:5)   25 s    
143 rinse H2O        
144 dry N2        
145 hardbake   130 1 min   hardbake on hotplate
146 descum plasma etcher w/ O2   1 min 250 mT power: 100 W
147 Plating of Ni wafer w/ patterned PR for electrode electroplating Ni 50 20min   current: 1.5 mA
thickness: 2 µm
area: ~0.6 cm2
spin bar: 100 rpm		 wafer w/ top electrode
148 rinse H2O        
149 dry N2        
150 remove PR ACE
IPA		   30 s
30 s		    
151 dry N2        
152 descum plasma etcher w/ O2   1 min 250 mT power: 100 W
153 remove Ni (750 Å) HCL:DI H2O (1:1)   ~5 min    
154 rinse H2O        
155 dry N2        
156 remove Ti (250 Å) HF:DI H2O (1:10)   5 s    
157 rinse H2O        
158 dry N2        
159 Removal of Sacrificial Layers wafer w/ top electrode etch of polyimide PRS2000 (hot) 2-4 hrs (preferrably overnight)     wafer w/ freed structures (wet)
160 rinse H2O     sample should not dry!  
161 Supercritical CO2 Release wafer w/ freed structures (wet) immerse sample IPA   5 min     wafer w/ compliant switch (final)
162 immerse sample Ethanol 1   3 min    
163 immerse sample Ethanol 2   3 min    
164 place sample covered w/ ethanol in chamber          
165 cool chamber   <-12 (-30)      
166 fill chamber CO2 (liquid)        
167 purge ethanol          
168 raise chamber temp   32-36   >1200 psi  
169 wait     5 min   keep in supercritical region
170 release CO2 in gaseous form     until press. is 1 atm    
171 release sample