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--- delayer:decoration [2012/02/21 01:55] – created mcmaster
+++ delayer:decoration [2013/04/07 04:06] (current) – removed mcmaster
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-Decoration as called by Fredrick Beck is the process of making parts stand out better.
-====== Copper sulphate ======
-Copper sulphate will bring out n-diffusion areas of pn junctions when illuminated (FIXME: how strong?). Chemistry is something like:
-Cu+2 + 2 e-  ======> Cu
-Si + 4 HF + 2 CuSO4  ======> SiF4 + 2 Cu + 2 H2SO4
-At higher temperatures, HF etch takes over, so it needs to be done cold. In particular, do not use a hot light source such as a bare halogen lamp. If it goes through a microscope it should be fine as the thermal part should be heavily attenuated / distorted by the time it reaches the sample.
-====== Periodic Acid Etchant ======
-Good at showing where doping changes. Strong etch rate dependence on illumination. Room temp: mostly etches highly doped areas, especially p+ with max conc 10**18 atoms / cm**3 Increased illumination favors weaker doping.
-  * 20-50 seconds
-  * 50 mL H2O
-  * 5 g H5IO6 (periodic acid)
-  * 5 mg KI
-  * 2 mL 48 % HF
-  * Must be added in given order
-====== Permanganate Etchant ======
-mL KMnO4
-mL 48 % HF
-.5 um / min on <111> @ 23C
-====== Bichromate Etchant ======
-Brings out n doped areas. Use 1:10 diluted Secco etchant. : H2O
-====== Silicon etchant p ======
-  * 20 mL acetic acid
-  * 1 mL 40% HF
-  * 3 mL 65% HNO3
-  * 1-3 seconds
-====== Staining etchant ======
-  * 12 mL 65 % HNO3 (works without nitric if just exposed to air?)
-  * 200 mL 48% HF
-  * 5-10 seconds