Infrared and Laser Engineering, Volume. 51, Issue 4, 20210942(2022)
Application of terahertz mapping in high throughput measurement of the electrical conductance of Cu alloy thin films (Invited)
Figures & Tables(15)
Fig. 1. Illustration of the high throughput materials chip fabrication method with electron beam deposition. (a) 12×12 mask of 3 patterns; (b) Illustration of the in site discrete mode process; (c) System setup for e-beam source, mask and sample stage; (d) Illustration of the ternary continuous gradient process; (e) Illustration of heat treatment process
Fig. 2. (a) Illustration of the THz mapping detection system in transmission mode; (b) THz time-domain spectra of the periodic temporal signals from multiple internal reflections; (c) Experimental setup of the THz emitter, the sample stage and the photoconductive detector
Fig. 3. (a)-(c) Optical images of the samples; (d)-(f) THz conductance imaging of the corresponding samples; (g) Comparison of metal film conductance obtained by different test methods
Fig. 4. (a) Cu thin film sample photo on high resistivity Si substrate; (b) THz conductance mapping image; (c) THz conductance variations of the sample spots; (d) Anisotropic variations along the horizontal direction of Fig.(a) and (b); (e) Anisotropic variations along the vertical direction of Fig.(a) and (b)
Fig. 5. Cu-Al2O3/Ag/Mg alloy thin film sample fabricated with the continuous gradient mode. (a) Optical image of the sample; (b) THz mapping imaging, scale bar=4 mm; (c) Comparison between the conductance trend of the 15 points marked in Fig.(b) obtained from THz and 4-point probe respectively
Fig. 6. Cu-Al2O3/Ag/Mg alloy thin film sample fabricated with the in site discrete mode. (a) Optical image of the sample; (b) THz mapping imaging; (c) Simulated combination of the thickness and positions of the constituents; (d) Index table of the sample spots; (e) Deposition parameters of multi-layer film
Fig. 7. SEM images of the 12×12 Cu-Al2O3/Ag/Mg Cu alloy thin film samples array, scale bar=100 μm
Fig. 8. (a) Relationship between the THz mapping conductance and that of the weight percentage of the samples constituents from column 164-214; (b) SEM microstructure morphology of representative sample spots with different conductance
Table 1. Conductance value of metal films
View tableView in ArticleTable 1. Conductance value of metal films
Sample constituents Conductance/S RD (THz-4PP)/4PP THz 4PP A Ti 56 nm 0.0214 0.0209 2.39% B Ti 56 nm+Zr 30 nm 0.0192 0.0215 10.7% C Ti 56 nm+Zr 30 nm+Al 24 nm 0.146 0.178 17.8%
Table 2. Constituents of the sample fabricated using the continuous gradient mode
View tableView in ArticleTable 2. Constituents of the sample fabricated using the continuous gradient mode
Layer index Materials Thickness/nm 1 Ti 5 2 Cu 80 3 Ag 0→ 12.7 4 Cu 10 5 Al2O3 0→ 12.7 6 Cu 10 7 Mg 0→ 25.4 8 Cu 10
Table 3. Conductance of the selected 15 points along the thickness gradients of Ag, Mg and Al2O3 using 4-point probe and THz methods respectively
View tableView in ArticleTable 3. Conductance of the selected 15 points along the thickness gradients of Ag, Mg and Al2O3 using 4-point probe and THz methods respectively
1 2 3 4 5 4PP 1.14 1.15 1.32 0.98 0.97 THz 0.76 0.86 0.91 0.59 0.66 RD −0.33% −0.25% −0.31% −0.40% −0.32% 6 7 8 9 10 4PP 1.54 2.15 2.89 1.01 0.88 THz 1.06 1.47 2.24 0.77 0.64 RD −0.31% −0.32% −0.22% −0.24% −0.27% 11 12 13 14 15 4PP 0.65 0.72 0.81 0.9 0.84 THz 0.51 0.53 0.59 0.7 0.6 RD −0.22% −0.26% −0.27% −0.22% −0.29%
Table 4. THz conductance value of the in site discrete 12×12 Cu-Al2O3/Ag/Mg alloy sample library
View tableView in ArticleTable 4. THz conductance value of the in site discrete 12×12 Cu-Al2O3/Ag/Mg alloy sample library
0.175 6 0.101 8 0.175 6 0.179 8 0.180 1 0.178 1 0.159 1 0.173 4 0.151 0 0.127 0 0.172 1 0.195 6 0.082 5 0.060 6 0.188 0 0.203 7 0.202 1 0.188 0 0.172 0 0.193 3 0.183 8 0.151 9 0.195 7 0.211 3 0.192 1 0.180 7 0.194 9 0.210 0 0.203 3 0.204 8 0.153 7 0.167 7 0.190 4 0.171 9 0.176 1 0.209 0 0.212 5 0.207 9 0.223 0 0.271 7 0.216 5 0.215 5 0.173 4 0.197 7 0.214 8 0.218 4 0.243 9 0.248 5 0.078 9 0.076 9 0.185 2 0.223 4 0.223 9 0.231 5 0.178 1 0.194 4 0.215 4 0.222 9 0.256 1 0.220 7 0.079 2 0.077 7 0.184 0 0.210 7 0.225 7 0.218 7 0.172 2 0.200 9 0.240 6 0.222 1 0.234 2 0.223 9 0.198 5 0.203 5 0.168 5 0.216 8 0.231 4 0.223 0 0.190 2 0.194 4 0.276 3 0.264 5 0.262 1 0.266 8 0.188 6 0.186 7 0.154 3 0.206 5 0.191 7 0.197 8 0.189 1 0.201 3 0.238 9 0.238 7 0.250 1 0.268 3 0.033 8 0.040 6 0.101 5 0.181 3 0.072 5 0.077 6 0.177 3 0.193 6 0.165 3 0.162 8 0.251 2 0.268 7 0.030 5 0.042 4 0.111 4 0.175 8 0.083 2 0.097 4 0.179 6 0.189 6 0.177 3 0.148 5 0.237 7 0.246 1 0.161 6 0.159 5 0.141 7 0.213 6 0.179 1 0.183 2 0.165 4 0.179 8 0.244 8 0.222 8 0.248 9 0.258 8 0.173 6 0.168 9 0.144 9 0.224 3 0.181 8 0.187 6 0.155 9 0.175 1 0.226 5 0.216 7 0.242 6 0.250 5
Table 5. Comparison of THz conductance and the weight percentage of oxygen of representative sample spots
View tableView in ArticleTable 5. Comparison of THz conductance and the weight percentage of oxygen of representative sample spots
Sample index THz conductance/S O/wt% 263 0.2763 5.05 264 0.2645 6.76 143 0.1904 7.36 233 0.1773 8.03 234 0.1485 16.24 333 0.1114 11.46 336 0.0974 25.1
Table 6. THz conductance and weight percentages of the constituents of sample spots in column #164-#214
View tableView in ArticleTable 6. THz conductance and weight percentages of the constituents of sample spots in column #164-#214
Sample index THz conductance/S O/wt% Al/wt% Ag/wt% Mg/wt% 164 0.127 8.73 7.79 5.83 5.58 154 0.151 9 4.94 8.19 4.99 6.51 144 0.171 9 7.19 5.75 5.38 2.13 134 0.218 4 6.27 7.47 10.15 3.79 124 0.222 9 6.65 4.65 10.38 5.11 114 0.222 1 8.05 6.93 9.76 4.27 264 0.264 5 6.76 6.39 6.21 3.65 254 0.238 7 7.87 5.98 5.46 3.56 244 0.162 8 12.91 9.6 7.74 4.26 234 0.148 5 16.24 11.85 10.77 4.61 224 0.222 8 5.88 6.55 11.12 4.23 214 0.216 7 6.7 6.03 10.25 2.8
Table 7. Advantages of THz scanning method vs. 4-point probe
View tableView in ArticleTable 7. Advantages of THz scanning method vs. 4-point probe
Measurement of electrical conductance/conductivity Terahertz mapping Four point probe Detection mode Contactless Contact with sample Applications[ 12 -14 ]Suitable for large samples or micro sampling（<2 mm）, uniform or non-uniform Sample area ≥10 mm2, uniform Conductivity mapping of graphene and carbon nanotubes, measurements of semiconductors, metallic thin films, superconductors, and metal oxides, etc. High throughput mapping of Conductance of Cu alloy thin films in the present study Bulk or thin plates of conducting metals or semiconductors Efficiency of measurement High throughput 144 samples/compositions per chip/batch in the present study Low throughput Information extracted Discrete value and mapping of conductivity, complex conductivity, charge/carrier mobility; electron scattering, etc. Discrete value of DC conductivity Detection resolution Three dimensional Two dimensional Overall results Comparison of multiple samples with various compositions prepared in one batch under same conditions in the present study One singular sample prepared each time
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Yu Zhu, Shihan Yan, Ziyi Zang, Shengxing Song, Jie Wang, Zhanqiang Ru, Hongliang Cui, Helun Song. Application of terahertz mapping in high throughput measurement of the electrical conductance of Cu alloy thin films (Invited)[J]. Infrared and Laser Engineering, 2022, 51(4): 20210942
Paper Information
Category: Invited paper
Received: Dec. 9, 2021
Accepted: Mar. 10, 2022
Published Online: May. 18, 2022
The Author Email: Shihan Yan (yanshihan@cigit.ac.cn), Helun Song (hlsong2008@sinano.ac.cn)
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