Plasma etching chemistries of high aspect ratio features in dielectrics
A method for etching features in a stack below a patterned mask in an etch chamber is provided. The stack is cooled with a coolant with a coolant temperature below −20° C. An etch gas is flowed into the etch chamber. A plasma is generated from the etch gas. Features are selectively etched into the stack with respect to the patterned mask.
1 . An etching method, comprising:
a) supporting a substrate on a chuck in a chamber of a plasma treatment system, the chuck having a lower electrode, wherein the substrate comprises a stack comprising at least two different silicon containing layers comprising at least one silicon oxide layer and at least one silicon nitride layer;
b) cooling the substrate to a temperature below −20° C.;
c) providing an etch gas comprising a halogen containing gas;
d) generating a plasma from the etch gas, wherein the plasma modifies the at least two different silicon containing layers of the stack providing modified layers;
e) activating the modified layers of the stack; and
f) etching features in the at least one silicon oxide layer and the at least one silicon nitride layer forming the stack.
2 . The etching method, as recited in claim 1 , further comprising after step e providing a bias.
3 . The etching method, as recited in claim 1 , wherein the generating the plasma from the etch gas comprises providing RF power.
4 . The etching method, as recited in claim 1 , wherein the etch gas further comprises a phosphorous containing gas.
5 . The etching method, as recited in claim 4 , wherein the phosphorous containing gas comprises phosphorus pentafluoride (PF 5 ).
6 . The etching method, as recited in claim 4 , wherein the plasma deposits a sidewall passivation on sidewalls of the features.
7 . The etching method, as recited in claim 1 , wherein the halogen containing gas comprises a free fluorine providing component.
8 . The etching method, as recited in claim 1 , further comprising providing one or more of a hydrogen containing component, a hydrocarbon containing component, a fluorocarbon containing component, and an iodine containing component.
9 . The etching method, as recited in claim 1 , wherein the stack comprises a plurality of silicon oxide and silicon nitride layers forming an ONON stack.
10 . The etching method, as recited in claim 1 , further comprising after step e providing a bias with a magnitude of at least 400 volts.
11 . An etching method, comprising:
a) supporting a substrate on a chuck in a chamber of a plasma treatment system, the chuck having a lower electrode, wherein the substrate comprises a stack comprising at least two different silicon containing layers comprising at least one silicon oxide layer and at least one silicon nitride layer;
b) providing an etch gas comprising a halogen containing gas;
c) generating a plasma from the etch gas, wherein the plasma modifies the at least two different silicon containing layers of the stack providing modified layers;
d) activating the modified layers of the stack; and
e) etching features in the at least one silicon oxide layer and the at least one silicon nitride layer forming the stack.
12 . The etching method, as recited in claim 11 , further comprising after step d providing a bias.
13 . The etching method, as recited in claim 11 , wherein the generating the plasma from the etch gas comprises providing RF power.
14 . The etching method, as recited in claim 11 , wherein the etch gas further comprises a phosphorous containing gas.
15 . The etching method, as recited in claim 14 , wherein the phosphorous containing gas comprises phosphorus pentafluoride (PF 5 ).
16 . The etching method, as recited in claim 14 , wherein the plasma deposits a sidewall passivation on sidewalls of the features.
17 . The etching method, as recited in claim 11 , wherein the halogen containing gas comprises a free fluorine providing component.
18 . The etching method, as recited in claim 11 , further comprising providing one or more of a hydrogen containing component, a hydrocarbon containing component, a fluorocarbon containing component, and an iodine containing component.
19 . The etching method, as recited in claim 11 , wherein the stack comprises a plurality of silicon oxide and silicon nitride layers forming an ONON stack.
20 . The etching method, as recited in claim 11 , further comprising after step d providing a bias with a magnitude of at least 400 volts.