Plade RCA

Preliminary and fundamental remarks:

  • TO OPERATE ON CMi WETBENCHES, PLEASE READ THE MANUAL Wet Benches Safety.
  • Any intervention in the wet bench is done only by CMI staff
  • This tool is a MICRO-ELECTRONIC compatible tool :
    • No organic layers (Photoresist, Kapton, polyimide etc …)
    • No Metallic layers (Gold, Copper Titane ….etc)

RESERVATIONS RULES AND BILLING POLICY :

  1. Booking : No restriction
  2. Reservation names must be correspond to operators
  3. Billing (service mode) : Flat rate 20 min operator / 30 min machine for one batch*
  4. Billing (user mode) : Processing time
  5. No penalty fees in case of user’s no show

* Batch : 25 wafers or samples with the same size and for the same cleaning 

Contents:

I. Equipement description

II. RCA baths at CMi

III. Modus operandi

IV. Links

I. Equipment description

The Plade RCA wet bench is dedicated to the cleaning of wafers and samples before processing in the Centrotherm furnaces (high  temperature processes) according the procedure developped by W. Kern et al in 1970.  

The baths are compatible with 4 or 6 inches wafers but also samples larger than 1.0 x 1.0 cm2. The default configuration is 4 inches, for 6 inches wafers, please contact CMi staff to change the carrier of the dryer.  The handling is done with 4 or 6 inches baskets. The baskets are in teflon and labelled “RCA”.

II. RCA baths at CMi

A “service RCA” is organized by CMi staff every Wednesday. To participate to the service, you have to have wafers free of photoresist. The service request has to done online according to this procedure:

CMI service RCA request

The RCA cleaning sequence is the following one :

  1. RCA 1 for the elimination of the organic elements. The processing temperature is 75°C and the processing time 15 min.
  2. Rinse 1 min
  3. HF (Can be optional) for the removal of the silicon oxide generated during the RCA 1 step. The removed thickness is 70A for 15 s on thermal oxide. This step can be skiped for blanket silicon wafers with oxide on it. 
  4. Rinse 1 min
  5. RCA 2 for the elimination of the metallic elements. The processing temperature is 75°C and the processing time 15 min.
  6. Full rinse 15 min with the Fast Fill Rinse bath (FFR) and the Trickle Tank (TT) bath .
  7. Drying of the wafers with the Spin Rinse & Dry (SRD) system.

The main informations regarding the 3 RCA baths are summarized in the table below :

RCA 1

(organic residus removal)

HF 

(thin oxide removal)

RCA 2

(metallic species removal)

H2O : NH4OH : H2O2

5 : 1 : 1

HF : H2O

1 : 10

H2O : HCl : H2O2

6 : 1 : 1

Temperature : 75°C

Duration : 5 to 15 min

Temperature : 20°C

Duration : 15 s

Temperature : 75°C

Duration : 5 to 15 min

HF : Fluorhydric acide 49% 

NH4OH : Ammonia 28% 

H2O2 : Peroxide 30% 

HCl : Chlorhydrique acid 37% 

III. Modus operandi

  1. Login on the Plade RCA using zone 3 computer
  2. Load the wafers in one of the dedicated Teflon carrier and put the handle on
  3. Full protection is now required (apron, face shield, chemical gloves) before going further
  4. Open the lid of the RCA 1 bath and gently plunge the carrier into it. Switch ON the RCA 1 timer.
  5. Rinse the gloves and gently clean the bath’s surroundings with a moist paper (several cleanings/rinsings are necessary)
  6. After 15 min, switch OFF the RCA 1 timer and open the FFR lid and gently transfer the Teflon carrier from the RCA 1 bath to FFR bath
  7. Activate the FFR button
  8. After 1 min, switch OFF the FFR, open the lid of the HF bath, gently transfer the Teflon carrier from the FFR bath to HF bath and switch ON the HF timer
  9. After 15 s, switch OFF the HF timer, open the lid of the FFR bath and gently transfer the Teflon carrier from the HF bath to FFR bath
  10. Activate the FFR button
  11. After 1 min, switch OFF the FFR, open the lid of the RCA 2 bath, gently transfer the Teflon carrier from the FFR bath to RCA 2 bath, switch ON the RCA 2 timer
  12. After 15 min, switch OFF the RCA 2 timer, open the FFR bath and gently transfer the Teflon carrier from the RCA 2 bath to FFR bath switch ON the FFR timer
  13. Activate the FFR button and wait for a full rinse cycle of 15 min
  14. Once resistivity is reached (~12 Mohm.cm), put the carrier in the SRD system (the carrier’s handle must be removed)
  15. A recipe is already selected. Just press STOP and the START
  16. When the SRD is finished, get the wafers back and put the carrier where it belongs
  17. Carefully check the cleanliness of the wetbench before taking off the chemical protection (apron, face shield, chemical gloves)
  18. Perform wetbench logout on zone 3 computer

Any droplets of any kind MUST be removed from the wetbench before leaving it. Suspicious droplets must be cleared using a moist paper (2 to 3 cleanings/rinsings are necessary) and remaining water droplets must be removed with absorbent paper.

IV. Links