Abstract A method for etching metal silicide layers 22a, 22b and polysilicon layers 24a, 24b on a substrate 20 with high etching selectivity, and anisotropic etching properties, is described. In the method, the substrate 20 is placed in a plasma zone 55, and process gas comprising chlorine, oxygen and optionally helium gas, is introduced into the plasma zone. A plasma is formed from the process gas to etch the metal silicide layer 22 at high etching selectivity relative to etching of the polysilicon layer 24, while providing substantially anisotropic etching of the metal silicide and polysilicon layers. Preferably, the plasma is formed using combined inductive and capacitive plasma sources. <IMAGE>
A method of selectively etching metal silicide or polysilicon layers supported by a silicon wafer or other substrate, the method comprising the steps of placing the substrate in a process chamber having process electrodes and an inductor coil, introducing process gas comprising chlorine, oxygen, and helium into the process chamber, and forming a plasma from the process gas, characterized in that the process gas is ionized to form plasma ions that energetically impinge on the substrate to selectively etch the layers supported by the substrate, by applying RF current at a source power level of 400 to 3000 Watts to the inductor coil and by applying a RF voltage at a bias power level to the process electrodes, the power ratio P r of the source power level to the bias power level being at least 2:1.
Claim 2
Dependent Claim
18 words
A method according to claim 1 characterized in that the power ratio P r is less than 20:1.
Claim 3
Dependent Claim
18 words
A method according to claim 2 characterized in that the power ratio P r is at least 8:1.
Claim 4
Independent Claim
27 words
A method according to any one of the preceding claims characterized in that the process gas consists essentially of Cl 2 , O 2 , and He.
Claim 5
Independent Claim
59 words
A method according to any one of the preceding claims characterized in that: (1) the process chamber is maintained at a pressure of 0.1 to 100 mTorr; (2) the mass flow ratio of helium to oxygen is from 0.25:1 to 15:1; or (3) the mass flow ratio of chlorine to the oxygen and helium is from 3:1 to 20:1.
Claim 6
Dependent Claim
48 words
A method according to claim 1 characterized in that the plasma is formed by applying a current at a power level of 400 to 3000 Watts to the inductor coil, and by applying a voltage at a power level of 20 to 1000 Watts to the process electrodes.
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