Chamber cleaning method using F
Elemental fluorine is often manufactured electrochemically from a solution of KF in hydrogen fluoride and contains varying amounts of HF as impurity. The present invention provides a method for chamber cleaning using F 2 which contains more than 0.1% by weight and equal to or less than 10% by weight of HF. Surprisingly, such an F 2 is very well suited for the purpose of chamber cleaning. In a preferred embodiment, the F 2 which contains more than 0.1% by weight and less than 2.5% by weight of HF is electrolytically produced, cleaned, delivered and used on site, without any pressurizing treatment. Omitting cleaning steps and process and using process conditions leaving a relatively high HF content in the F 2 allows at the same time to omit pressurizing steps. The advantage is that less cleaning steps.
1. A method for the cleaning of chambers, the method comprising using F 2 which contains more than 0.01% by weight and less than 0.5% by weight of HF;
wherein the applied F 2 is obtained in a process comprising the following steps (I) and (II):
A step (I) comprising:
A) at least one step of electrolytically producing raw F 2 from HF in the presence of KF
B) at least one step of removing particles entrained in the raw F 2 obtained in step A)
C) at least one step of filtering any remaining particles out of the F 2 leaving step B) by passing the F 2 through a filter
and
D) a step of providing the F 2 to a buffer tank or a storage tank;
and
A step (II) wherein F 2 is withdrawn from the buffer tank or storage tank and delivered to the chamber to perform at least one step of chamber cleaning;
wherein the steps A) to D) are performed on the site of chamber cleaning;
wherein step A) is performed in an electrolyzer, step B) is performed in a static scrubber, step C) is performed using a metallic filter, step D) is performed in a buffer tank or storage tank, and the F 2 leaving step D) is delivered to at least one chamber and used in the chamber in a chamber cleaning step (II), wherein the electrolyzer, the static scrubber, the metallic filter, the buffer tank or storage tank, and the at least one chamber are operably connected; and
wherein the pressure of the F 2 in step B) is lower than the pressure of F 2 in step A), the pressure of the F 2 in step C) is lower than the pressure of F 2 in step B), the pressure of the F 2 in step D) is lower than the pressure of F 2 in step C), and the pressure of the F 2 in step (II) is lower than the pressure of F 2 in step D).
2. The method of claim 1 wherein the chamber is a CVD chamber.
3. The method of claim 1 wherein the chamber is used during the manufacture of a semiconductor, a micro-electromechanical system, TFT (flat panel display) or a solar cell for depositing at least one layer.
4. The method of claim 1 wherein the filter of step C) comprises pores having a diameter between 0.01 and 20 μm.
5. The method of claim 1 wherein the F 2 pressure in step A) is equal to or lower than 1.1 bar (abs).
6. The method of claim 1 wherein the F 2 is delivered to the chamber in step (II) at a pressure from equal to or greater than 0.2 bar (abs) to equal to or lower than 0.55 bar (abs).
7. The method of claim 1 wherein the F 2 is not subjected to a pressurizing treatment.
8. The method of claim 1 wherein the filter used in step C) is cleaned with liquid HF.
9. The method according to claim 8 wherein the liquid HF is recovered and fed to a step of electrolytically producing F 2 .