Step 20. Nitride removal, pad oxide removal

 

 

 

 

Step

 

Process

Date

Operator

 

20.1

 

 

Etch thin oxide off from top of nitride on product wafers and PCH:

 

Sink6, 10/1 HF dip for 60 sec

 

08/27/04

Horvath

 

20.2

 

 

Etch nitride off from product wafers and PCH:

 

Sink7, hot phosphoric for ~3 hrs @ 160C

 

Measure pad oxide thickness (Nanoduv) to make sure nitride is etched away:

 

Wafer

T

C

F

L

R

W#6

224

208

215

237

221

W#10

223

216

234

212

228

PCH

210

232

220

211

217

 

 

 

20.3

 

 

Etch pad oxide (~230A):

 

Sink6, 10/1 HF dip for 1 min (PCH dewet)

 

 

20.4

 

 

Etch LOCOS from NCH:

 

Sink7, clean 5/1 BHF for 5.5 minutes

 

Rs (NCH) = 730 Ohm/sq