Specific Process Knowledge/Wafer cleaning/RCA

RCA cleaning

The RCA clean is used for cleaning the wafers before taking them into the furnaces and a few other equipments (check the cross contamination sheet). It consists of two solutions: RCA1 and RCA2 plus diluted HF. A crucial part of the RCA clean is the oxidation by H$_{2}$O$_{2}$. Therefore the life time of the RCA solutions are limited by the presence of the H$_{2}$O$_{2}$ which is highly volatile at 70 $^{o}$C.

• The RCA1 contains: H$_{2}$O, NH$_{4}$OH and H$_{2}$O$_{2}$ (5:1:1). It is used for removal of light organics, particles and metal.
  
• The RCA2 contains: H$_{2}$O, HCl and H$_{2}$O$_{2}$ (5:1:1). It is used for removal of heavy metals, alkalies and metal hydroxides.

RCA procedure

• RCA1: 10 min
• DI water rinsing (dumping three times)
• HF: 30 sec (avoid it if you have oxide as the top layer)
• DI water rinsing (dumping three times)
• RCA2: 10 min
• DI water rinsing (dumping three times)
• Optional: HF: 30 sec (avoid it if you have oxide as the top layer)
• DI water rinsing (dumping three times)

For procedure details please look in the user manual positioned in LabManager.

Overview of RCA process data

	RCA1	RCA2	HF
General description	It is used for removal of light organics, particles and metal.	It is used for removal of heavy metals, alkalies and metal hydroxides.	It is used for removal of oxide generated in RCA1 and RCA2
Chemical solution	H$_{2}$O, NH$_{4}$OH(29%) and H$_{2}$O$_{2}$(30%) (5:1:1)	H$_{2}$O, HCl(37%) and H$_{2}$O$_{2}$(30%) (5:1:1)	5% HF
Process temperature	70-80 oC	70-80 oC	Room temperature
Process time	10 min.	10 min.	30 sec.
Life time of the chemical solutions	Can only be heated one time. When hot: it lasts for ~1h	Can only be heated one time. When hot: it lasts for ~1h	~2 months
Allowed materials	Silicon Silicon oxide Silicon nitride Quartz wafers/fused silica	Silicon Silicon oxide Silicon nitride Quartz wafers/fused silica	Silicon Silicon oxide Silicon nitride
Batch size	1-25 2",4" or 6" wafers at a time	1-25 2",4" or 6" wafers at a time	1-25 2",4" or 6" wafers at a time
Size of substrate	2"-4"-6" wafers	2"-4"-6" wafers	2"-4"-6" wafers