Improvement of Uniformity and Reliability of Scaled-Down Cu Interconnects with Carbon-Rich Low-kFilms

Low-k SiCxNyFilms Prepared by Plasma-Enhanced Chemical Vapor Deposition Using 1,3,5-trimethyl-1,3,5-trivinylcyclotrisilazane Precursor

“…It is proposed that the use of a single source precursor and low plasma power density can alleviate or eliminate the resist poisoning, which required further experimental validation. Moreover, high etch selectivity can be achieved for our SiC x N y films deposited at 100-300 • C (C/Si = 0.72-0.81), and even higher for SiC x N y film deposited at 400 • C (C/Si = 0.29) if a low-k ILD with a high carbon content (C/Si ratio = 2.7) in Kume et al's study 35 is assumed.…”

“…For the copper/low-k backend interconnects, a via-first patterning scheme has been widely used in a dual damascene integration pro- cess flow. 34,35 In the via etch process, highly selective etching of the low-k ILD against the underlying etch-stop layer, such as SiC x N y in our case, is required. This is to ensure sufficient thickness of SiC x N y film to protect the underlying copper layer from plasma induced damage and oxidation due to diffusion of oxygen.…”

“…The etch selectivity requirement becomes more challenging as the low-k ILD is reduced to k < 2.6, which is achieved by incorporating high carbon content. Recently Kume et al 35 reported that a high etch selectivity (∼10) can be achieved for a low-k ILD with high carbon content (C/Si = 2.7 for k = 2.55) against a SiC x N y etch-stop layer with C/Si = 0.9 using N 2 -Ar-CF x etching gas chemistry. In our study, as shown in Table II, a wide range of C/Si ratio from 0.29 to 1.82 was obtained with decreasing deposition temperature from 400 • C to 25 • C. We can infer that high etch selectivity can be achieved for our SiC x N y films deposited at 100-300 • C (C/Si = 0.72-0.81), and even higher for SiC x N y film deposited at 400 • C (C/Si = 0.29) if a low-k ILD with a high carbon content (C/Si ratio = 2.7) in Kume et al's study 35 is assumed.…”

“…Recently Kume et al 35 reported that a high etch selectivity (∼10) can be achieved for a low-k ILD with high carbon content (C/Si = 2.7 for k = 2.55) against a SiC x N y etch-stop layer with C/Si = 0.9 using N 2 -Ar-CF x etching gas chemistry. In our study, as shown in Table II, a wide range of C/Si ratio from 0.29 to 1.82 was obtained with decreasing deposition temperature from 400 • C to 25 • C. We can infer that high etch selectivity can be achieved for our SiC x N y films deposited at 100-300 • C (C/Si = 0.72-0.81), and even higher for SiC x N y film deposited at 400 • C (C/Si = 0.29) if a low-k ILD with a high carbon content (C/Si ratio = 2.7) in Kume et al's study 35 is assumed. Even for SiC x N y film deposited at room temperature (C/Si ratio = 1.82), a high selectivity is still possible by designing the etching gas chemistry to enhance their difference in etch rates of ILD and etch-stop layer with specific carbon contents.…”

Review of methods for the mitigation of plasma‐induced damage to low‐dielectric‐constant interlayer dielectrics used for semiconductor logic device interconnects

“…In the integration scheme, the low‐k films face etch gas chemistry containing fluorine. Hayashi et al applied etching plasma from an Ar/N 2 /CF 4 /O 2 gas mixture to a stack of oxygen‐rich SiOC (k = 2.7) and porous SiOCH (k = 2.5). The large hydrocarbons attached to hexagonal silica backbones in molecular‐pore‐stacked SiOCH prevent the oxidation of Si‐CH 3 during the O 2 plasma ash process, reducing the C‐depleted damage area at the sidewalls of via holes and trench lines.…”