Cylinder surface treated container for monochlorosilane
View Patent ↗The present invention is a container and a processing for passivating the internal surface of the container to store monochlorosilane in a stable manner without degradation of the monochlorosilane. Various container surface modifications have been identified to reduce surface reactions to acceptable levels. Some of the described surface modifications result in significant reduction in monochlorosilane instability.
1. A container containing a volume of monochlorosilane having an internal surface, wherein the internal surface comprises either carbon steel or stainless steel and has been modified by mechanical polishing followed by exposure to either a silicon hydride or a chlorosilane prior to storage of the monochlorosilane, wherein the container is capable of stably storing monochlorosilane such that the rate of decomposition of monochlorosilane is less than 0.1% per month at ambient temperature.
2. The container of claim 1 wherein the mechanical polishing was performed by a process selected from the group consisting of shot blasting, glass bead blasting, and abrasive slurry polishing.
3. The container of claim 2 wherein the mechanical polishing was performed by an abrasive slurry.
4. The container of claim 3 wherein the abrasive slurry comprises stainless steel or ceramic spheres.
5. The container of claim 3 wherein the abrasive slurry comprises a corrosion inhibitor.
6. The container of claim 2 wherein the mechanical polishing was accomplished by shot blasting the surface three times followed by abrasive slurry polishing with ceramic pellets followed by abrasive slurry polishing with stainless steel shaped pellets.
7. The container of claim 2 wherein the mechanical polishing provides approximately a 1 micron R a surface finish.
8. The container of claim 1 wherein the silicon hydride is MCS or DCS.
9. The container of claim 1 wherein the container is a 44 liter container.
10. The container of claim 1 wherein the container, once filled with the monochlorosilane, is maintained at a temperature of below 20° C. during storage.
11. The container of claim 10 herein the container, once filled with the monochlorosilane, is maintained at a temperature of 0° C.
12. The container of claim 1 wherein the monochlorosilane has a purity of greater that 99.5%.
13. The container of claim 1 wherein the de-activation of surface hydroxyl groups by exposure to either a silicon hydride or chlorosilane occurs at an elevated temperature.
14. The container of claim 13 wherein the elevated temperature is 55° C.
15. The container of claim 1 wherein the exposure to either a silicon hydride or a chlorosilane prior to storage of the monochlorosilane de-activates surface hydroxyl groups.