System and method for mitigating oxide growth in a gate dielectric
Oxide growth of a gate dielectric layer that occurs between processes used in the fabrication of a gate dielectric structure can be reduced. The reduction in oxide growth can be achieved by maintaining the gate dielectric layer in an ambient effective to mitigate oxide growth of the gate dielectric layer between at least two sequential process steps used in the fabrication the gate dielectric structure. Maintaining the gate dielectric layer in an ambient effective to mitigate oxide growth also improves the uniformity of nitrogen implanted in the gate dielectric.
1. A processing system for use in forming at least part of a gate dielectric structure on a substrate, comprising:
a first process chamber for forming a gate dielectric layer over the substrate, the first process chamber having a first pumping element configured to evacuate gas from the first process chamber;
a second process chamber for introducing nitrogen atoms in the gate dielectric layer, the second process chamber having a second pumping element configured to evacuate gas from the second process chamber;
a transfer chamber connected to the first process chamber via a first vacuum lock door and connected the second process chamber via a second vacuum lock door, the transfer chamber having a gas distribution system and a third, distinct pumping element configured to provide an ambient of uniform, laminar inert gas flow within the transfer chamber during transfer of the substrate between the first process chamber and the second process chamber; and
a load lock distinct from said transfer chamber to allow introduction and removal of the substrate from the processing system.
2. The processing system of claim 1 , wherein the gas distribution system and third distinct pumping element are configured to maintain a pressure substantially below about 760 Torr in the transfer chamber and actively purge the transfer chamber with an inert gas during said transfer.
3. The processing system of claim 2 , wherein the gas distribution system and third distinct pumping element are configured to maintain the atmosphere at a pressure of about 3 Torr to about 200 Torr in the transfer chamber during said transfer.
4. The processing system of claim 3 , wherein the gas distribution system and third distinct pumping element are configured to actively purge the transfer chamber at a flow rate of about 2 liters per minute to about 5 liters per minute during said transfer.
5. The processing system of claim 4 , further comprising a third processing chamber for performing a re-oxidation or densifying process, the third processing chamber connected to the transfer chamber via a third vacuum lock door.
6. The processing system of claim 5 , further comprising a fourth process chamber for forming a conductive layer over the re -oxidized or densified gate dielectric layer, the fourth process chamber connected to the transfer chamber via a fourth vacuum lock door.
7. A processing system for forming a gate stack of a transistor, comprising:
a transfer chamber connected to a first process chamber for forming a gate dielectric layer over a substrate, a second process chamber for introducing nitrogen atoms in the gate dielectric layer, and a load lock, the transfer chamber configured to transfer the substrate from the first process chamber to the second process chamber; and
a gas distribution system in fluid communication with the transfer chamber and one or more pumping elements connected to the transfer chamber, the gas distribution system and one or more pumping elements configured to provide an ambient of uniform, laminar inert gas flow within the transfer chamber during transfer of the substrate between the first process chamber and the second process chamber.
8. The processing system of claim 7 , wherein the gas distribution system and one or more pumping elements are configured to maintain a pressure substantially below about 760 Torr in the transfer chamber and actively purge the transfer chamber with an inert gas during said transfer.
9. The processing system of claim 8 , wherein the gas distribution system and one or more pumping elements are configured to maintain the atmosphere at a pressure of about 3 Torr to about 200 Torr in the transfer chamber during said transfer.
10. The processing system of claim 9 , wherein the gas distribution system and one or more pumping elements are configured to actively purge the transfer chamber at a flow rate of about 2 liters per minute to about 5 liters per minute during said transfer.
11. The processing system of claim 10 , further comprising a third processing chamber for performing a re-oxidation or densifying process, the third processing chamber connected to the transfer chamber.
12. The processing system of claim 11 , further comprising a fourth process chamber for forming a conductive layer over the re -oxidized or densified gate dielectric layer, the fourth process chamber connected to the transfer chamber.