나노급 수소화된 비정질 실리콘층 두께에 따른 저온형성 니켈실리사이드의 물성 연구 (Property of Nickel Silicides with Hydrogenated Amorphous Silicon Thickness Prepared by Low Temperature Process)

서지정보

· 발행기관 : 대한금속·재료학회
· 수록지 정보 : 대한금속·재료학회지 / 46권 / 11호 / 762 ~ 769페이지
· 저자명 : 김종률, 최용윤, 박종성, 송오성

초록

Hydrogenated amorphous silicon(a-Si : H) layers, 120 nm and 50 nm in thickness, were deposited
on 200 nm SiO₂/single-Si substrates by inductively coupled plasma chemical vapor deposition(ICP-CVD).
Subsequently, 30 nm-Ni layers were deposited by E-beam evaporation. Finally, 30 nm-Ni/120 nm a-Si : H/200
nm-SiO₂/single-Si and 30 nm-Ni/50 nm a-Si:H/200 nm-SiO₂/single-Si were prepared. The prepared samples
were annealed by rapid thermal annealing(RTA) from 200oC to 500oC in 50oC increments for 30 minute. A
four-point tester, high resolution X-ray diffraction(HRXRD), field emission scanning electron microscopy (FESEM),
transmission electron microscopy (TEM), and scanning probe microscopy(SPM) were used to examine
the sheet resistance, phase transformation, in-plane microstructure, cross-sectional microstructure, and
surface roughness, respectively. The nickel silicide on the 120 nm a-Si:H substrate showed high sheet
resistance(470 Ω/□ ) at T(temperature) < 450oC and low sheet resistance (70 Ω/□) at T > 450oC. The high
and low resistive regions contained ζ-Ni2Si and NiSi, respectively. In case of microstructure showed mixed
phase of nickel silicide and a-Si:H on the residual a-Si:H layer at T < 450oC but no mixed phase and a residual
a-Si:H layer at T > 450oC. The surface roughness matched the phase transformation according to the
silicidation temperature. The nickel silicide on the 50 nm a-Si:H substrate had high sheet resistance(~1 kΩ/
□) at T < 400oC and low sheet resistance (100 Ω/□) at T > 400oC. This was attributed to the formation of δ-
Ni2Si at T > 400oC regardless of the siliciation temperature. An examination of the microstructure showed a
region of nickel silicide at T < 400oC that consisted of a mixed phase of nickel silicide and a-Si:H without a
residual a-Si:H layer. The region at T > 400oC showed crystalline nickel silicide without a mixed phase. The
surface roughness remained constant regardless of the silicidation temperature. Our results suggest that a
50 nm a-Si:H nickel silicide layer is advantageous of the active layer of a thin film transistor(TFT) when applying
a nano-thick layer with a constant sheet resistance, surface roughness, and δ-Ni2Si temperatures > 400oC.

영어초록

Hydrogenated amorphous silicon(a-Si : H) layers, 120 nm and 50 nm in thickness, were deposited
on 200 nm SiO₂/single-Si substrates by inductively coupled plasma chemical vapor deposition(ICP-CVD).
Subsequently, 30 nm-Ni layers were deposited by E-beam evaporation. Finally, 30 nm-Ni/120 nm a-Si : H/200
nm-SiO₂/single-Si and 30 nm-Ni/50 nm a-Si:H/200 nm-SiO₂/single-Si were prepared. The prepared samples
were annealed by rapid thermal annealing(RTA) from 200oC to 500oC in 50oC increments for 30 minute. A
four-point tester, high resolution X-ray diffraction(HRXRD), field emission scanning electron microscopy (FESEM),
transmission electron microscopy (TEM), and scanning probe microscopy(SPM) were used to examine
the sheet resistance, phase transformation, in-plane microstructure, cross-sectional microstructure, and
surface roughness, respectively. The nickel silicide on the 120 nm a-Si:H substrate showed high sheet
resistance(470 Ω/□ ) at T(temperature) < 450oC and low sheet resistance (70 Ω/□) at T > 450oC. The high
and low resistive regions contained ζ-Ni2Si and NiSi, respectively. In case of microstructure showed mixed
phase of nickel silicide and a-Si:H on the residual a-Si:H layer at T < 450oC but no mixed phase and a residual
a-Si:H layer at T > 450oC. The surface roughness matched the phase transformation according to the
silicidation temperature. The nickel silicide on the 50 nm a-Si:H substrate had high sheet resistance(~1 kΩ/
□) at T < 400oC and low sheet resistance (100 Ω/□) at T > 400oC. This was attributed to the formation of δ-
Ni2Si at T > 400oC regardless of the siliciation temperature. An examination of the microstructure showed a
region of nickel silicide at T < 400oC that consisted of a mixed phase of nickel silicide and a-Si:H without a
residual a-Si:H layer. The region at T > 400oC showed crystalline nickel silicide without a mixed phase. The
surface roughness remained constant regardless of the silicidation temperature. Our results suggest that a
50 nm a-Si:H nickel silicide layer is advantageous of the active layer of a thin film transistor(TFT) when applying
a nano-thick layer with a constant sheet resistance, surface roughness, and δ-Ni2Si temperatures > 400oC.

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