Processes to form a metallic film stack
View Patent ↗The present invention relates to an electrically conductive film stack for semiconductors and methods and apparatus for providing same. A film stack comprising a first layer of a platinum-rhodium alloy deposited by metal organic chemical vapor deposition (MOCVD) in the presence of a reducer, such as hydrogen (H 2 ) gas, and a second layer of the platinum-rhodium alloy deposited in the presence of an oxidizing gas, such as ozone (O 3 ), provides an electrical conductor that is also a relatively good barrier to oxygen. The platinum-rhodium film stack can be used as an electrode or capacitor plate for a capacitor with a high-k dielectric material. The electrode formed with alternating reducing and oxidizing agents produces a rough surface texture, which enhances the memory cell capacitance.
1. A process of depositing a metallic film stack on a substrate in accordance with a metal organic chemical vapor deposition (MOCVD) process, the process comprising:
depositing a first film of a metal composition, wherein the metal composition comprises an alloy of platinum and rhodium, in the presence of a reducer; and
depositing a second film of the metal composition in the presence of an oxidizer, the second film directly contacting the first film.
2. The process as defined in claim 1 , wherein the reducer is selected from hydrogen (H 2 ) and ammonia (NH 3 ).
3. The process as defined in claim 1 , wherein the oxidizer is selected from oxygen (O 2 ), ozone (O 3 ), nitrous oxide (N 2 O), hydrogen peroxide (H 2 O 2 ), steam (H 2 O), and nitric oxide (NO).
4. The process as defined in claim 1 , wherein depositing the film stack is conducted in one recipe.
5. The process as defined in claim 1 , further comprising depositing a third film of the metal composition in the presence of the oxidizer before depositing the first film.
6. The process as defined in claim 1 , wherein a thickness of the film stack is from about 50 Angstroms (Å) to about 2000 Å.
7. The process as defined in claim 1 , wherein a thickness of the film stack is from about 100 Å to about 1000 Å.
8. The process as defined in claim 1 , wherein a thickness of the first film is about 20 Å to about 500 Å.
9. The process as defined in claim 1 , wherein a thickness of the second film is about 20 Å to about 500 Å.
10. A method of depositing a metallic film stack on a substrate in accordance with a metal organic chemical vapor deposition (MOCVD) process, the method comprising:
depositing a plurality of layers of a metallic composition on the substrate to form a rough metallic layer having a grain size of about 100 to 500 angstrom (Å) by alternating between:
depositing a layer with a metal source gas using a reducing agent; and
depositing a layer with the same metal source gas using an oxidizing agent.
11. The method as defined in claim 10 , wherein depositing the plurality of layers forms a total thickness of the film stack between about 100 Å and about 1000 Å.
12. The method as defined in claim 10 , wherein depositing using the reducing agent forms a layer thickness between about 20 Å and about 500 Å thick.
13. The method as defined in claim 10 , wherein depositing using the oxidizing agent forms a layer thickness between about 20 Å and about 500 Å thick.
14. A process of depositing a metallic film stack on a semiconductor wafer with a metal organic chemical vapor deposition (MOCVD) process, the process comprising:
in a deposition chamber, depositing a first platinum-rhodium alloy in the presence of a first gas, the first platinum-rhodium alloy being deposited at a first deposition rate to form a first platinum-rhodium layer; and
while the wafer remains in the deposition chamber, depositing a second platinum-rhodium alloy on the first platinum-rhodium layer in the presence of a second gas, the second platinum-rhodium alloy being deposited at a second deposition rate to form a second platinum-rhodium layer, wherein the second deposition rate is greater than the first deposition rate.
15. The process of claim 14 , wherein the first gas is a reducer gas.
16. The process of claim 14 , wherein the second gas is an oxidizer gas.