PECVD apparatus for in-situ deposition of film stacks
An apparatus for depositing film stacks in-situ (i.e., without a vacuum break or air exposure) are described. In one example, a plasma-enhanced chemical vapor deposition apparatus configured to deposit a plurality of film layers on a substrate without exposing the substrate to a vacuum break between film deposition phases, is provided. The apparatus includes a process chamber, a plasma source and a controller configured to control the plasma source to generate reactant radicals using a particular reactant gas mixture during the particular deposition phase, and sustain the plasma during a transition from the particular reactant gas mixture supplied during the particular deposition phase to a different reactant gas mixture supplied during a different deposition phase.
1. A plasma-enhanced chemical vapor deposition apparatus configured to deposit a plurality of film layers on a substrate without exposing the substrate to a vacuum break between film deposition phases, the apparatus comprising:
(a) a process station;
(b) one or more reactant feeds fluidly coupled to the process station, the one or more reactant feeds configured to supply to the process station a first reactant gas mixture during a first film deposition phase, a purging gas during purging of the process station, and a second reactant gas mixture during a second film deposition phase;
(c) a plasma source configured to generate a plasma for the process station, wherein the plasma source comprises a low-frequency plasma source and a high-frequency plasma source; and
(d) a controller having program instructions on a non-transitory computer machine-readable medium for:
(i) causing a generation of reactant radicals using the first reactant gas mixture and causing a deposition of a first material during the first film deposition phase, while causing a generation of the plasma using the low-frequency plasma source and the high-frequency plasma source,
(ii) causing the purging of the process station with the purging gas after the first film deposition phase,
(iii) causing the plasma to be sustained during the purging included in a transition from the first reactant gas mixture supplied during the first film deposition phase to the second qualitatively different reactant gas mixture supplied during the second film deposition phase, wherein the second film deposition phase deposits a second material onto the first material, the second material having a different set of chemical elements than the first material, wherein the first reactant gas mixture supplies chemical elements for the first material, and the second qualitatively different reactant gas mixture supplies chemical elements for the second material deposited in the second film deposition phase; and
(iv) causing a low-frequency plasma source power to decrease from a higher power used during the first film deposition phase to a lower power or to zero power used during the transition.
2. The apparatus of claim 1 , wherein the program instructions further comprise instructions to cause the plasma to be sustained by controlling one or more of a process station pressure, a reactant gas concentration, an inert gas concentration, a plasma source power, a plasma source frequency, and a plasma power pulse timing.
3. The apparatus of claim 1 , wherein the program instructions further comprise instructions for causing a high-frequency plasma source power to decrease from a higher power used during the first film deposition phase to a lower power used during the transition.
4. The apparatus of claim 1 , further comprising a showerhead, and a plurality of reactant feeds, wherein the showerhead includes a plurality of segregated gas plenums, each gas plenum being coupled to a respective reactant feed of the plurality of reactant feeds so that two or more incompatible process gases are segregated from one another in the showerhead.
5. The apparatus of claim 1 , wherein the process station is one of a plurality of process stations included within the apparatus, each process station fluidly coupled to a shared mixing volume via the one or more reactant feeds, the shared mixing volume configured to generate the particular reactant gas mixture from a plurality of reactant gas sources.
6. The apparatus of claim 1 , further comprising another process station fluidly coupled to another reactant feed, wherein the reactant feeds are fluidly isolated from each other, wherein each process station is fluidly coupled to a separate mixing volume via the respective reactant feeds, each mixing volume fluidly connected to one or more reactant gas sources, the one or more reactant gas sources of each mixing volume being separated from one another.
7. A system comprising the apparatus of claim 1 and a stepper tool.
8. The apparatus of claim 1 , wherein the program instructions comprise instructions for causing a low-frequency plasma source power to decrease from a higher power used during the first film deposition phase to a lower power or to zero power used during the transition, such that the low-frequency plasma source power is decreased by a proportionally greater amount than a decrease in high-frequency plasma source power from the first film deposition phase to the transition.
9. The apparatus of claim 1 , wherein the program instructions comprise instructions for causing the low-frequency plasma source power to be turned off during the transition.