Modular system and process for continuous deposition of a thin film layer on a substrate
A system and associated process for vapor deposition of a thin film layer on a photovoltaic (PV) module substrate is includes establishing a vacuum chamber and introducing the substrates individually into the vacuum chamber. A conveyor system is operably disposed within the vacuum chamber and is configured for conveying the substrates in a serial arrangement through a vapor deposition apparatus within the vacuum chamber at a controlled constant linear speed. A post-heat section is disposed within the vacuum chamber immediately downstream of the vapor deposition apparatus in the conveyance direction of the substrates. The post-heat section is configured to maintain the substrates conveyed from the vapor deposition apparatus in a desired heated temperature profile until the entire substrate has exited the vapor deposition apparatus.
1. A process for vapor deposition of a thin film layer on a photovoltaic (PV) module substrate, comprising:
conveying substrates in serial arrangement through a vapor deposition apparatus in a vacuum chamber wherein a thin film of a sublimed source material is deposited onto an upper surface of the substrates, the substrates being conveyed through the vapor deposition apparatus at a controlled constant linear speed such that leading and trailing sections of the substrates in a conveyance direction are exposed to the same vapor deposition conditions within the vapor deposition apparatus;
post-heating the substrates as the substrates are conveyed out of the vapor deposition apparatus such that a substantially uniform temperature is maintained along the length of the substrates until the entire substrate is conveyed out of the vapor deposition apparatus, wherein the substrates are conveyed from the vapor deposition apparatus into a post-heat module for the post-heating step while maintaining a substantially constant temperature profile throughout the longitudinal length of the post-heat module; and,
cooling the substrates subsequent to the post-heating step;
wherein the substrates are conveyed through the vapor deposition apparatus and into the post-heat module at a first conveyance rate, and conveyed from the post-heat module into a downstream cool-down section at a substantially greater second conveyance rate effective to prevent a thermal gradient from being established along the length of the substrates.
2. The process as in claim 1 , wherein the first conveyance rate is from about 10 mm/sec to about 40 mm/sec, and the second conveyance rate is from about 200 mm/sec to about 600 mm/sec.
3. The process as in claim 1 , wherein the substrates are conveyed through the cool-down section at about the first conveyance rate.
4. The process as in claim 1 , further comprising pre-heating the substrates prior to conveying the substrates through the vapor deposition apparatus.
5. A process for vapor deposition of a thin film layer on a photovoltaic (PV) module substrate, comprising:
conveying substrates in serial arrangement through a vapor deposition apparatus in a vacuum chamber wherein a thin film of a sublimed source material is deposited onto an upper surface of the substrates, the substrates being conveyed through the vapor deposition apparatus at a controlled constant linear speed such that leading and trailing sections of the substrates in a conveyance direction are exposed to the same vapor deposition conditions within the vapor deposition apparatus;
post-heating the substrates as the substrates are conveyed out of the vapor deposition apparatus in a manner such that a controlled gradually decreasing temperature gradient is established along the length of the substrates until the entire substrate is conveyed out of the vapor deposition apparatus; and,
cooling the substrates subsequent to the post-heating step.
6. The process as in claim 5 , wherein the substrates are conveyed from the vapor deposition apparatus into a post-heat module for the post-heating step, and into a cool-down section for the cooling step.
7. The process as in claim 6 , further comprising maintaining a decreasing temperature profile along the longitudinal length of the post-heat module.
8. The process as in claim 7 , wherein the temperature profile has a temperature of from about 400 degrees C. to about 600 degrees C. at an inlet thereof and about 200 degrees C. to about 500 degrees C. at an outlet thereof.
9. The process as in claim 5 , wherein the substrates are conveyed through the vapor deposition apparatus, into and through the post-heat module, and into and through the cool-down section at substantially the same constant liner speed.
10. The process as in 5 , further comprising pre-heating the substrates prior to conveying the substrates through the vapor deposition apparatus.