Metal oxide preclean for bottom-up gapfill in MEOL and BEOL

1. A method of pre-cleaning in a semiconductor structure, the method comprising:

performing a plasma pre-treatment process to remove impurities from a surface of the semiconductor structure comprising a metal layer and a dielectric layer, wherein the plasma pre-treatment process comprises exposing the surface of the semiconductor structure to a plasma formed from a process gas including hydrogen (H 2 )-containing gas and a plasma formed from a process gas including oxygen (O 2 ) gas in sequence;

performing a selective etch process to remove molybdenum oxide from a surface of the metal layer, the selective etch process comprising soaking the semiconductor structure in a precursor including at least one of molybdenum chloride (MoCl 5 or MoCl 6 ) or tungsten chloride (WCl 5 or WCl 6 ) at a temperature of between 250° C. and 450° C.; and

performing a post-treatment process to remove chlorine residues and by-products of the selective etch process on the surface of the semiconductor structure, wherein the post-treatment process comprises a capacitively coupled plasma (CCP) process, in which the surface of the semiconductor structure is exposed to a plasma formed from a hydrogen (H 2 )-containing gas.

2. The method of claim 1 , wherein an etch selectivity of molybdenum oxide (MoO x ) to molybdenum (Mo) is more than 16.

3. The method of claim 1 , wherein the plasma pre-treatment process comprises an inductively coupled plasma (ICP) process, a capacitively coupled plasma (CCP) process, or a remote plasma assisted process.

4. A method of pre-cleaning in a semiconductor structure, the method comprising:

performing a plasma pre-treatment process to remove impurities from a surface of the semiconductor structure comprising a metal layer and a dielectric layer;

performing a selective etch process to remove molybdenum oxide from a surface of the metal layer, the selective etch process comprising soaking the semiconductor structure in a precursor including at least one of molybdenum chloride (MoCl 5 or MoCl 6 ) or tungsten chloride (WCl 5 or WCl 6 ) at a temperature of between 250° C. and 450° C.; and

performing a post-treatment process to remove chlorine residues and by-products of the selective etch process on the surface of the semiconductor structure,

wherein the post-treatment process comprises a thermal bake process, in which the surface of the semiconductor structure is heated to and maintained at a temperature of between 350° C. and 450° C.

5. The method of claim 4 , wherein an etch selectivity of molybdenum oxide (MoO x ) to molybdenum (Mo) is more than 16.

6. The method of claim 4 , wherein the plasma pre-treatment process comprises exposing the surface of the semiconductor structure to a plasma formed from a process gas including both hydrogen (H 2 )-containing gas and oxygen (O 2 ) gas.

7. The method of claim 5 , wherein the plasma pre-treatment process comprises an inductively coupled plasma (ICP) process or a capacitively coupled plasma (CCP) process performed.

8. The method of claim 4 , wherein the plasma pre-treatment process comprises exposing the surface of the semiconductor structure to a plasma formed from a process gas including hydrogen (H 2 )-containing gas and a plasma formed from a process gas including oxygen (O 2 ) gas in sequence.

9. The method of claim 8 , wherein the plasma pre-treatment process comprises an inductively coupled plasma (ICP) process, a capacitively coupled plasma (CCP) process, or a remote plasma assisted process.

10. A method of pre-cleaning in a semiconductor structure, the method comprising:

performing a plasma pre-treatment process to remove impurities from a surface of the semiconductor structure, wherein the plasma pre-treatment process comprises:

an inductively coupled plasma (ICP) process, a capacitively coupled plasma (CCP) process, or a remote plasma assisted process, in which the surface of the semiconductor structure is exposed to a plasma formed from a process gas including hydrogen (H 2 )-containing gas and a plasma formed from a process gas including oxygen (O 2 ) gas in sequence; and

performing a selective etch process to remove molybdenum oxide from the surface of the semiconductor structure comprising a metal layer and a dielectric layer, the selective etch process comprising:

soaking the semiconductor structure in a precursor including at least one of molybdenum chloride (MoCl 5 or MoCl 6 ), tungsten chloride (WCl 5 or WCl 6 ), tungsten fluoride (WF 6 ), or molybdenum fluoride (MoF 6 ) at a temperature of between 250° C. and 450° C., wherein

the metal layer comprises molybdenum (Mo).

11. The method of claim 10 , wherein an etch selectivity of molybdenum oxide (MoO x ) to molybdenum (Mo) is more than 16.

12. The method of claim 10 , further comprising:

performing a post-treatment process to remove chlorine residues and by-products of the selective etch process on the surface of the semiconductor structure,

wherein the post-treatment process comprises a plasma process in which the surface of the semiconductor structure is exposed to a plasma formed from a hydrogen (H 2 )-containing gas.

13. The method of claim 10 , further comprising:

performing a post-treatment process to remove chlorine residues and by-products of the selective etch process on the surface of the semiconductor structure,

wherein the post-treatment process comprises a thermal bake process in which the surface of the semiconductor structure is heated to and maintained at a temperature of between 350° C. and 450° C.