Abstract
The fabrication of a highly reflective multi-layer film is an urgent need in the next-generation extreme ultraviolet (EUV) lithography to print ever-smaller circuit patterns onto semiconductor wafers by using extremely short wavelength (13.5 nm) light. For this purpose, we have synthesized the Mo/Si multi-layer films by employing the two-cathode superconducting bulk magnet magnetron sputtering apparatus. The films were made by repeatedly depositing a pair of 4.5 nm thick Si and then 2.5 nm thick Mo layer up to 40 or 50 pairs on the Si wafer with its root-mean square (rms) surface roughness of 0.1 nm. The resulting rms surface roughness of the Mo/Si multi-layer film turned out to be 0.12 nm. The transmission electron microscope (TEM) studies revealed the inter-diffusion layer thicknesses of Si-on-Mo and Mo-on-Si layers to be 0.5 and 1.5 nm, respectively. The EUV-reflectivity was theoretically calculated to reach the value of 70%, when these structural data are inserted into the reflectivity formula. However, the highest EUV-reflectivity so far observed was 67% in the normal incident condition. The 2-3% shortage of the reflectivity is attributed to the presence of residual Xe gas atoms incorporated into the film during deposition in the reduced Xe gas atmosphere.
| Original language | English |
|---|---|
| Pages (from-to) | 1456-1460 |
| Number of pages | 5 |
| Journal | Physica C: Superconductivity and its Applications |
| Volume | 468 |
| Issue number | 15-20 |
| DOIs | |
| Publication status | Published - 2008 Sep 15 |
| Externally published | Yes |
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Keywords
- EUV lithography
- Magnetron sputtering
- Mo/Si multilayer
- Superconducting bulk magnet
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering
Cite this
Fabrication of Mo/Si multilayer mirrors for extreme ultraviolet lithography by means of superconducting bulk magnet magnetron sputtering. / Mizutani, U.; Yamaguchi, T.; Ikuta, H.; Tomofuji, T.; Yanagi, Y.; Itoh, Y.; Oka, Tetsuo.
In: Physica C: Superconductivity and its Applications, Vol. 468, No. 15-20, 15.09.2008, p. 1456-1460.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Fabrication of Mo/Si multilayer mirrors for extreme ultraviolet lithography by means of superconducting bulk magnet magnetron sputtering
AU - Mizutani, U.
AU - Yamaguchi, T.
AU - Ikuta, H.
AU - Tomofuji, T.
AU - Yanagi, Y.
AU - Itoh, Y.
AU - Oka, Tetsuo
PY - 2008/9/15
Y1 - 2008/9/15
N2 - The fabrication of a highly reflective multi-layer film is an urgent need in the next-generation extreme ultraviolet (EUV) lithography to print ever-smaller circuit patterns onto semiconductor wafers by using extremely short wavelength (13.5 nm) light. For this purpose, we have synthesized the Mo/Si multi-layer films by employing the two-cathode superconducting bulk magnet magnetron sputtering apparatus. The films were made by repeatedly depositing a pair of 4.5 nm thick Si and then 2.5 nm thick Mo layer up to 40 or 50 pairs on the Si wafer with its root-mean square (rms) surface roughness of 0.1 nm. The resulting rms surface roughness of the Mo/Si multi-layer film turned out to be 0.12 nm. The transmission electron microscope (TEM) studies revealed the inter-diffusion layer thicknesses of Si-on-Mo and Mo-on-Si layers to be 0.5 and 1.5 nm, respectively. The EUV-reflectivity was theoretically calculated to reach the value of 70%, when these structural data are inserted into the reflectivity formula. However, the highest EUV-reflectivity so far observed was 67% in the normal incident condition. The 2-3% shortage of the reflectivity is attributed to the presence of residual Xe gas atoms incorporated into the film during deposition in the reduced Xe gas atmosphere.
AB - The fabrication of a highly reflective multi-layer film is an urgent need in the next-generation extreme ultraviolet (EUV) lithography to print ever-smaller circuit patterns onto semiconductor wafers by using extremely short wavelength (13.5 nm) light. For this purpose, we have synthesized the Mo/Si multi-layer films by employing the two-cathode superconducting bulk magnet magnetron sputtering apparatus. The films were made by repeatedly depositing a pair of 4.5 nm thick Si and then 2.5 nm thick Mo layer up to 40 or 50 pairs on the Si wafer with its root-mean square (rms) surface roughness of 0.1 nm. The resulting rms surface roughness of the Mo/Si multi-layer film turned out to be 0.12 nm. The transmission electron microscope (TEM) studies revealed the inter-diffusion layer thicknesses of Si-on-Mo and Mo-on-Si layers to be 0.5 and 1.5 nm, respectively. The EUV-reflectivity was theoretically calculated to reach the value of 70%, when these structural data are inserted into the reflectivity formula. However, the highest EUV-reflectivity so far observed was 67% in the normal incident condition. The 2-3% shortage of the reflectivity is attributed to the presence of residual Xe gas atoms incorporated into the film during deposition in the reduced Xe gas atmosphere.
KW - EUV lithography
KW - Magnetron sputtering
KW - Mo/Si multilayer
KW - Superconducting bulk magnet
UR - http://www.scopus.com/inward/record.url?scp=50349083407&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=50349083407&partnerID=8YFLogxK
U2 - 10.1016/j.physc.2008.05.239
DO - 10.1016/j.physc.2008.05.239
M3 - Article
AN - SCOPUS:50349083407
VL - 468
SP - 1456
EP - 1460
JO - Physica C: Superconductivity and its Applications
JF - Physica C: Superconductivity and its Applications
SN - 0921-4534
IS - 15-20
ER -