High pressure chemical vapor trapping method
A high pressure trapping system is provided to collect chemical vapor by-products in successive stages through chemical reasons conducted at progressively colder temperatures. A hot trap receives chemical vapor exhaust and collects a first waste, typically a solid, as a result of the high temperature completing a chemical reason in the vapor. Surviving gaseous by-products continue to the next process. The following chamber is colder, and collects waste as a solid or a liquid as a result of a chemical process dependent on the cold temperature. Sometimes a third chamber is used for even a colder chemical reaction to collect waste products. As a solid, these waste products are easier to collect, remove, and even reuse.
1. A method to separate and collect elements of a chemical vapor exhaust at a high pressure, the method comprising:
(a) passing sequentially the exhaust from a processing chamber to a vacuum pump and to a hot trap, and then to a first cold trap, wherein a non-gaseous chemical waste is collected in the hot trap and in the first cold trap, and a gaseous exhaust is thereafter vented;
(b) collecting any additional non-gaseous waste in a second cold trap before the gaseous exhaust is vented, the second cold trap operatively connected with and positioned downstream of the first cold trap.
2. A method as in claim 1 wherein the chemical vapor exhaust is a MOCVD precursor exhaust, in which the passing of the exhaust through the hot trap collects a solid metal waste from the MOCVD precursor exhaust.
3. A method as in claim 1 further comprising biasing the hot trap with a voltage before passing the exhaust through the hot trap, whereby charged metal from the MOCVD precursor is attracted to and deposited in the hot trap.
4. A method as in claim 1 further comprising bypassing the hot trap to allow the disconnection of the hot trap without exposing the exhaust to the hot trap.
5. A method as in claim 1 further comprising bypassing the first cold trap to allow the disconnection of the first cold trap without exposing the exhaust to the first cold trap.
6. A method as in claim 1 further comprising bypassing the second cold trap to allow the disconnection of the second cold trap without exposing the exhaust to the second cold trap.
7. A method as in claim 1 further comprising heating the hot trap to a hot trap temperature before passing the exhaust through the hot trap.
8. A method as in claim 1 further comprising cooling the first cold trap to a first cold trap temperature before passing the exhaust through the first cold trap.
9. A method as in claim 1 further comprising cooling the second cold trap to a second cold trap temperature before passing the exhaust through the second cold trap.