Hardmask materials
Hardmask films having high hardness and low stress are provided. In some embodiments a film has a stress of between about −600 MPa and 600 MPa and hardness of at least about 12 GPa. In some embodiments, a hardmask film is prepared by depositing multiple sub-layers of doped or undoped silicon carbide using multiple densifying plasma post-treatments in a PECVD process chamber. In some embodiments, a hardmask film includes a high-hardness boron-containing film selected from the group consisting of Si x B y C z , Si x B y N z , Si x B y C z N w , B x C y , and B x N y . In some embodiments, a hardmask film includes a germanium-rich GeN x material comprising at least about 60 atomic % of germanium. These hardmasks can be used in a number of back-end and front-end processing schemes in integrated circuit fabrication.
1. A method of forming a hardmask film on a semiconductor substrate, the method comprising:
receiving the semiconductor substrate in a plasma-enhanced chemical vapor deposition (PECVD) process chamber; and
forming a high-hardness Si x B y C z hardmask film having a hardness of greater than about 12 GPa, and a stress of between about −600 MPa and 600 MPa by PECVD on the semiconductor substrate, wherein the PECVD hardmask deposition process comprises:
(i) flowing a process gas comprising a boron-containing precursor, a silicon-containing precursor and a carrier gas into the PECVD process chamber; and
(ii) forming a dual frequency plasma, wherein LF/HF power ratio is at least about 1.5, to deposit the high-hardness Si x B y C z hardmask film on the semiconductor substrate, wherein the formed high-hardness Si x B y C z hardmask film has a ratio of IR peak areas for BC/[BC+SiC] of at least about 0.35.
2. The method of claim 1 , wherein the high-hardness Si x B y C z hardmask film has a stress of between about −300 MPa and 300 MPa.
3. The method of claim 1 , wherein the high-hardness Si x B y C z hardmask film has a stress of between about 0 MPa and 600 MPa.
4. The method of claim 1 , wherein the high-hardness Si x B y C z hardmask film has a hardness of at least about 16 GPa.
5. The method of claim 1 , wherein the formed high-hardness Si x B y C z hardmask film is deposited over a layer of dielectric having a dielectric constant of less than about 2.8, and wherein the formed h-hardness Si x B y C z hardmask film has an etch selectivity of at least about 8:1 versus the dielectric in a dry plasma etch.
6. The method of claim 1 , wherein the formed high-hardness Si x B y C z hardmask film is deposited over a layer of polysilicon.
7. The method of claim 1 , wherein the high-hardness Si x B y C z hardmask film is formed at a temperature of less than about 400° C.