1. Acknowledgement before cleaning
1) When the PECVD graphite boat/carrier is used more than 100 to 150 times, the operator needs to check the coating condition in time. If there is an abnormal coating, it needs to be cleaned and confirmed. The normal coating color of the silicon wafer in the graphite boat/carrier is blue. If the wafer has non-blue, multiple colors, or the color difference between the wafers is large, it is an abnormal coating, and the cause of the abnormality needs to be confirmed in time.
2) After the process personnel analyze the coating condition of the PECVD graphite boat/carrier, they will determine whether the graphite boat needs to be cleaned and whether the card point needs to be replaced, and the graphite boat/carrier that needs to be cleaned will be handed over to the equipment personnel for cleaning.
3) After the graphite boat/carrier is damaged, the production personnel will take out all the silicon wafers in the graphite boat and use CDA (compressed air) to sort out the fragments in the graphite boat. After completion, the equipment personnel will lift it into the acid tank that has been prepared with a certain proportion of HF solution for cleaning.
2. Cleaning of graphite boat
It is recommended to use a 15-25% hydrofluoric acid solution for three rounds of cleaning, each for 4-5 hours, and periodically bubbling nitrogen during the soaking and cleaning process, adding about half an hour of cleaning; note: it is not recommended to use air directly as the gas source for bubbling. After pickling, rinse with pure water for about 10 hours, and confirm that the boat has been thoroughly cleaned. After cleaning, please check the surface of the boat, the graphite card point and the boat sheet joint, and other parts to see if there is any silicon nitride residue. Then dry according to the requirements.
3. Cleaning precautions
A) Since HF acid is a highly corrosive substance and has a certain volatility, it is dangerous to operators. Therefore, operators at the cleaning post must take safety precautions and be managed by a dedicated person.
B) It is recommended to disassemble the boat and only clean the graphite part during cleaning, so that each contact part can be cleaned more thoroughly. At present, many domestic manufacturers use overall cleaning, which is convenient, but because HF acid is corrosive to ceramic parts, overall cleaning will shorten the service life of the corresponding parts.
Post time: Dec-23-2024