Hard mask layer and formation method thereof

1 . A method, comprising:

forming a target layer over a substrate;

forming a first hard mask layer over the target layer by a plasma generated using a first radio frequency generator and a second radio frequency generator, the first radio frequency generator and the second radio frequency generator having different powers;

forming a second hard mask layer over the first hard mask layer by a plasma generated using the first radio frequency generator without using the second radio frequency generator;

forming a photoresist layer over the second hard mask layer;

exposing the photoresist layer;

developing the photoresist layer;

patterning the first hard mask layer and the second hard mask layer using the photoresist layer as an etch mask; and

patterning the target layer using the first hard mask layer and the second hard mask layer as an etch mask.

2 . The method of claim 1 , wherein the power of the first radio frequency generator is higher than the power of the second radio frequency generator.

3 . The method of claim 1 , further comprising:

treating the second hard mask layer using an oxygen-containing chemical.

4 . The method of claim 1 , further comprising:

treating the second hard mask layer using ozone gas, hydrogen peroxide (H 2 O 2 ), or H 2 O.

5 . The method of claim 1 , wherein forming the second hard mask layer further comprises:

introducing a hydrocarbon-containing precursor and a hydrogen gas to the first hard mask layer.

6 . The method of claim 5 , wherein the hydrocarbon-containing precursor is C 2 H 2 .

7 . The method of claim 1 , wherein the first hard mask layer is formed at a first temperature, and the second hard mask layer is formed at a second temperature lower than the first temperature.

8 . The method of claim 1 , wherein the second hard mask layer has an amount of terminal CH 3 groups being more than an amount of terminal CH 3 groups of the first hard mask layer.

9 . The method of claim 1 , wherein the second hard mask layer has an amount of terminal carbon-carbon double bonds being less than an amount of terminal carbon-carbon double bonds of the first hard mask layer.

10 . The method of claim 1 , wherein the photoresist layer is in contact with the second hard mask layer.

11 . A method, comprising:

forming a target layer over a substrate;

forming a first carbon-based hard mask layer over the target layer by a plasma generated using a first radio frequency generator and a second radio frequency generator, the first radio frequency generator and the second radio frequency generator having different powers;

forming a second carbon-based hard mask layer over the first carbon-based hard mask layer by a plasma generated using the first radio frequency generator without using the second radio frequency generator;

forming a photoresist layer over the second carbon-based hard mask layer;

exposing the photoresist layer;

developing the photoresist layer;

patterning the first carbon-based hard mask layer and the second carbon-based hard mask layer using the photoresist layer as an etch mask; and

patterning the target layer using the first carbon-based hard mask layer and the second carbon-based hard mask layer as an etch mask.

12 . The method of claim 11 , wherein the photoresist layer is in contact with a top region of the second carbon-based hard mask layer.

13 . The method of claim 11 , further comprising:

treating a top region of the second carbon-based hard mask layer using an oxygen-containing chemical.

14 . The method of claim 13 , wherein the oxygen-containing chemical comprises ozone gas, hydrogen peroxide (H 2 O 2 ), or H 2 O.

15 . The method of claim 11 , wherein the first carbon-based hard mask layer is an amorphous carbon layer.

16 . A method, comprising:

forming a target layer over a substrate;

depositing a first hard mask layer over the target layer by a plasma deposition method using a plasma generated using a first radio frequency generator and a second radio frequency generator, the first radio frequency generator and the second radio frequency generator having different powers;

forming a second hard mask layer over the first hard mask layer by a plasma generated using the first radio frequency generator without using the second radio frequency generator;

forming a photoresist layer over the second hard mask layer;

exposing the photoresist layer;

developing the photoresist layer;

patterning the first hard mask layer and the second hard mask layer using the photoresist layer as an etch mask; and

etching the target layer using the first hard mask layer and the second hard mask layer as an etch mask.

17 . The method of claim 16 , wherein the first hard mask layer is an amorphous carbon layer.

18 . The method of claim 16 , wherein the second hard mask layer is an amorphous carbon layer.

19 . The method of claim 16 , wherein forming the second hard mask layer over the first hard mask layer comprises:

forming the second hard mask layer at a temperature different from a temperature of depositing the first hard mask layer over the target layer.

20 . The method of claim 16 , wherein forming the second hard mask layer over the first hard mask layer comprises:

forming the second hard mask layer at a temperature lower than a temperature of depositing the first hard mask layer over the target layer.