Device fabrication via pulsed plasma
Systems and methods discussed herein are directed towards processing of substrates, including forming a plurality of features in a target layer on a substrate. The formation of the plurality of features includes a main etch operation that forms the plurality of features to a first depth in the target layer. The main etch operation is followed by a phase shift sync pulsing (PSSP) operation, and these two operations are repeated iteratively to form the features to a predetermined depth. The PSSP operation includes one or more cycles of RF source power and RF bias power, this cycle deposits a protective coating in and on the features and then etches a portion of the protective coating to expose portions of the feature.
1. A method for processing a substrate, comprising:
(a) etching a substrate disposed on a substrate support in a processing chamber by supplying an etching gas composition to the processing chamber to form a plurality of features to a first depth in a target layer disposed on the substrate;
(b) depositing, subsequent to (a), a protective coating on a sidewall of each of the plurality of features, wherein depositing the protective coating comprises:
(1) applying a pulsed RF source power for a first predetermined period of time, and forming, in response to the pulsing, a first layer in between the plurality of features on a top surface of the substrate, on the sidewall of each feature of the plurality of features, and on a bottom of each feature of the plurality of features; and
(2) applying a pulsed RF bias power to an electrode disposed in the substrate support for a second predetermined period of time and removing, in response to the pulsing of the RF bias power, a portion of the first layer; and
(3) repeating (b)(1) and (b)(2) to form the protective coating; and
(c) repeating (a) and (b) until the plurality of features extend to a predetermined depth in the target layer.
2. The method of claim 1 , further comprising:
forming a hardmask layer on the target layer, wherein the hardmask layer is a spin-on-carbon layer.
3. The method of claim 1 , wherein the first predetermined period of time is less than the second predetermined period of time.
4. The method of claim 1 , wherein the first predetermined period is greater than the second predetermined period of time.
5. The method of claim 1 , wherein removing a portion of the first layer comprises:
removing a first portion of the first layer disposed on the sidewall of each feature of the plurality of features; and
removing a second portion of the first layer disposed on the bottom of each feature of the plurality of features.
6. The method of claim 5 , wherein a second portion of the first layer remains on the sidewall subsequent to the removing of the first portion.
7. The method of claim 1 , wherein (b)(2) occurs when the RF source power is off.
8. The method of claim 1 , wherein (b)(1) occurs when the RF bias power is off.
9. The method of claim 1 , wherein a portion of the first predetermined period of time overlaps with the second predetermined period of time.
10. The method of claim 9 , wherein the first predetermined period of time overlaps with up to 10% of the second predetermined period of time.
11. A method for processing a substrate, comprising:
(a) etching a substrate disposed on a substrate support in a processing chamber by supplying an etching gas composition to the processing chamber to form a plurality of features in a target layer disposed on the substrate, wherein;
(b) depositing, subsequent to (a), a protective coating on a sidewall of each of the plurality of features, wherein depositing the protective coating comprises:
(1) applying a pulsed RF source power for a first predetermined period of time, and forming, in response to the pulsing, a first layer in between the plurality of features on a top surface of the substrate, on the sidewall of each feature of the plurality of features, and on a bottom of each feature of the plurality of features; and
(2) applying, while the pulsed RF source is off, a pulsed RF bias power to an electrode disposed in the substrate support for a second predetermined period of time and removing, in response to the pulsing of the RF bias power, a portion of the first layer; and
(3) repeating (b)(1) and (b)(2) to form the protective coating; and
(c) repeating (a) and (b) until the plurality of features extend to a predetermined depth the target layer.
12. The method of claim 1 , wherein a portion of (b) occurs in an AC afterglow.
13. The method of claim 11 , wherein the etching at (a) further comprises forming a plasma from SiCl 4 and O 2 .
14. The method of claim 13 , wherein (b)(2) occurs while F gas is introduced into the processing chamber and a plurality of F ions are directed perpendicularly towards the substrate to remove the portion of the first layer.
15. The method of claim 14 , wherein a ratio of SiCl 4 :O 2 :F is 1:1:1.
16. The method of claim 11 , wherein the first predetermined period of time overlaps with up to 10% of the second predetermined period of time.
17. The method of claim 11 , wherein the sum of the first predetermined period and the second predetermined period is from 0.1 milliseconds (ms) to 1 ms.
18. The method of claim 11 , wherein a hardmask layer is formed on the target layer and comprises a spin-on-carbon layer.
19. A method for processing a substrate, comprising:
(a) etching a substrate disposed on a substrate support in a processing chamber by supplying an etching gas composition to the processing chamber to form a plurality of features in a target layer disposed on the substrate, wherein a hardmask layer comprising spin-on-carbon is formed on the target layer;
(b) depositing, subsequent to (a), a protective coating on a sidewall of each of the plurality of features, wherein depositing the protective coating comprises:
(1) applying a pulsed RF source power for a first predetermined period, and forming, in response to the pulsing, a first layer in between the plurality of features on a top surface of the substrate, on the sidewall of each feature of the plurality of features, and on a bottom of each feature of the plurality of features; and
(2) applying, during a portion of the first predetermined period while the pulsed RF source power is applied, a pulsed RF bias power to an electrode disposed in the substrate support for a second predetermined period and removing, in response to the pulsing of the RF bias power, a portion of the first layer; and
(3) repeating (b)(1) and (b)(2) to form the protective coating; and
(c) repeating (a) and (b) until the plurality of features extend through the target layer.
20. The method of claim 19 , wherein the portion when the RF bias power is applied while the RF source power is applied is up to 10% of the first predetermined period.