第三章 實驗設計與規劃
3.4 結構分析與量測
3.4.5 紅外線熱像儀
微型熱電致冷晶片溫度之檢測，由紅外線熱像儀提供二維的溫度影
首先將熱電漿料利用網版印刷方式成形熱電材料膜於1.8 cm × 1.8 cm 面積 要加熱器(Heater)提供一熱源，將可以同時量測出席貝克電動勢(ΔVSample) 及溫度差(ΔT)，如圖 3.17 為席貝克係數量測設備圖。
V
S T
= Δ
Δ
(3-1)3.5.2 導電率量測方法
四點探針法(Four point probe)是半導體業常被用來量測導電率的量測 方法。主要是以四個非常小的歐姆接點接觸的平板樣品表面，如圖3.18 所
Table 3.1 Experimental facilities.
名稱 型號 製造商 代理商
精密網版印刷機 YCR-001 瑾耀企業有限公司
熱蒸鍍機 SS-600-RA CHA
熱墊板 HP-350 Pentad 汎達科技有限公司
精密天平 AR313 OHAUS 尚偉股份有限公司
水平式管型爐 HTRH
100-300116 GERO 建成科學儀器股份有限公司
光學顯微鏡 STM6 Olympus 元利儀器股份有限公司
紅外線熱像儀 TVS-200 AVIO 景興電腦科技有限公司
掃描式電子顯微鏡 JSM-6360 JEOL 捷東股份有限公司
Table 3.2 Experimental chemical reagent.
名稱 型號 製造商 代理商
光阻 SU-8 2050 Shipley 揚博股份有限公司
顯影液 SU-8 Developer Shipley 揚博股份有限公司
光阻稀釋劑 SU-8 Thinner Shipley 揚博股份有限公司
丙酮 Acetone 日本試藥工業株式會社 昇鋐理化有限公司
異丙醇 Isopropyl Alcohol 日本試藥工業株式會社 昇鋐理化有限公司
α-松油醇 ALPHA
TERPINEOL Showa 景明化工有限公司
乙基纖維素 CPS 200 Showa 景明化工有限公司
三碲化二鉍 Bi2Te3 Admat Midas Inc 昇美達國際開發有限公司 三碲化二銻 Sb2Te3 Admat Midas Inc 昇美達國際開發有限公司
洗版劑 M8850 旭化成ケミカルズ株式会社 台灣平玄科技股份有限公司
(a)
Figure 3.8 Precision screen-printing equipment.
印刷平台 X 軸
Figure 3.9 Thermal evaporator.
Figure 3.10 Precise balance.
Figure 3.11 Hot plate.
Figure 3.12 Horizontal high temperature tube furnace.
Figure 3.13 SEM and EDS system.
Figure 3.14 Surface profiler.
Figure 3.15 X-ray diffraction.
Figure 3.16 Infrared radiometer.
定溫金屬塊
測試試片
(a)
Thermoelectric device
Metal block Metal block
Thermoelectric device
∆V
T
HT
LTemperature distributuion
(b)
Figure 3.17 Schematic diagram of Seebeck coefficient measurement equipment (ITRI).
Figure 3.18 Schematic diagram of electrical conductivity equipment.
第四章 實驗結果與討論
4.1.1 印刷速度對於圖形之影響
實驗採用 4 吋矽晶片作為印刷基材，進行線寬測試印刷。印刷油墨 (Printing ink)選用由貝星貿易股份有限公司提供的 UV 感光型之 UV 9023 油墨，印刷機台所使用之刮刀硬度為 80 度，屬於高硬度型刮刀，而刮刀 角度設定為 50°，由於印刷使用感光型 UV 油墨，不具揮發性與乾燥堵塞 網版之虞，因此實驗中無覆墨手續。
首先針對印刷速度之探討，印刷相關參數如表 4.1 所示，在 case 1 與 case 2、case 3 中，離版距離(Off-contact)皆設定為 0.5 mm，而刮刀施力 (Squeegee force)固定於 2 kgw，變動的參數為 case 1、case 2 與 case 3 之印 刷速度(Printing speed)，其分別為 50 mm/sec、90 mm/sec 與 100 mm/sec，
而在圖 4.1 中，左側與右側分別為線寬 40 μm 與 30 μm 之圖形。由圖 4.1 (a)
4.1.2 離版距離對於圖形之影響
線寬測試網版匹配的最佳刮刀施力。
4.1.5 最佳線寬範圍之印刷測試 mm/sec。GN-52-479 為 UV 感光型油墨，因此印刷後需曝光的程序，使圖 案乾燥固化與定型，給予 1500 mJ/cm2之曝光能量可完成曝光固化程序。
Table 4.1 Process of different printing speed.
Case No. Printing ink Off-contact Squeegee
force Printing speed
1 UV 9023 0.5 mm 2 kgw 50 mm/sec
2 UV 9023 0.5 mm 2 kgw 90 mm/sec
3 UV 9023 0.5 mm 2 kgw 100 mm/sec
40 μm 30 μm
(a) case 1: 50 mm/sec
40 μm 30 μm
(b) case 2: 90 mm/sec
40 μm 30 μm
(c) case 3: 100 mm/sec
Figure 4.1 The test pattern of different printing speed.
Table 4.2 Process of different off-contact.
Case No. Printing ink Off-contact Squeegee
force Printing speed
4 UV 9023 0.3 mm 2 kgw 90 mm/sec
40 μm 30 μm
Figure 4.2 The test pattern of 0.3 mm off-contact.
Table 4.3 Process of different Squeegee force.
Case No. Printing ink Off-contact Squeegee
force Printing speed
5 UV 9023 0.5 mm 2.0 kgw 90 mm/sec
6 UV 9023 0.5 mm 1.5 kgw 90 mm/sec
40 μm
(a) case 5: 2.0 kgw
40 μm
(b) case 6: 1.5 kgw
Figure 4.3 The test pattern of different squeegee pressure.
Table 4.4 Process of different printing ink.
Case No. Printing ink
(viscosity) Off-contact Squeegee
force Printing speed
7 GN 479
(11 Pa⋅s) 0.5 mm 1.5 kgw 90 mm/sec
8 UV 9023-H-1
(50 Pa⋅s) 0.5 mm 1.5 kgw 90 mm/sec
9 UV 9023-H-1
(50 Pa⋅s) 0.6 mm 1.5 kgw 90 mm/sec
40 μm
(a) case 7: GN 479 (11 Pa⋅s)
40 μm
(b) case 8: UV 9023-H-1 (50 Pa⋅s)
40 μm
(c) case 9: UV 9023-H-1 (50 Pa⋅s)
Figure 4.4 The test pattern of different printing ink.
Table 4.5 Process of minimum critical dimension.
Case No. Printing ink
(viscosity) Off-contact Squeegee
force Printing speed
10 GN -52-479
(50 Pa⋅s) 0.5 mm 1.5 kgw 90 mm/sec
50 μm
Figure 4.5 The screen pattern of different angle.
50 μm
Figure 4.6 The test pattern of different angle.
(a) 30-100 μm
(b) 30-100 μm
(c) 50 μm
(d) 100 μm
Figure 4.7 SSccrreeeenn--pprriinntteedd pattern on a silicon for resolution test.
4.2 印刷成形熱電材料膜之結果討論
可進一步達到膜厚增加的目的。
以 Sb2Te3之熔點 90%的溫度，也就是約 585 °C 的溫度進行燒結，有更佳 的結合性。熱電膜有良好的結合性是必要的，因為材料顆粒的結合，可提 高材料與基板的附著性，也提升熱電膜結構緻密性，使得熱電膜之熱電性 質有較穩定與良好的表現。
4.2.4 熱電膜之特性量測
經過前兩節針對熱電膜之品質改善後，使得熱電膜去除氧成份，以降 低電阻值達到正常範圍；以及提升熱電膜之結合性，使熱電特性有較穩定 的表現。之後進行熱電特性的量測，表 4.10 顯示 Bi2Te3與 Sb2Te3熱電膜之 席貝克係數與電阻值。Bi2Te3與 Sb2Te3 席貝克係數、電阻值，分別為-57.06 μV/K、4.40×10-5 Ωm 與 64.70 μV/K、7.33×10-5 Ωm，與粉末擠壓燒結法文 獻【49】中，n-type 與 p-type 材料為 -103μV/K、7.86×10-2 Ω⋅m 與 222 μV/K、
22.17×10-2 Ω⋅m 相比較，熱電膜的電阻值明顯低於文獻的數值，而席貝克 係數並無出色表現。推測熱電膜的均勻性與緻密性必須設法提升，才有機 會改善席貝克係數。解決方式有：(1) 增加燒結時間促使熱電膜結合性提 升，且熔融反應的時間增加有助於均勻性的提升；(2) 提高燒結溫度促使 熱電膜的流動性提升，加快熔融反應促使熱電膜更均勻、緻密以及提升結 合性。
Table 4.6 Concentration of the binder and printing ink.
Precursor Ethyl-cellulose Alpha-terpineol Bi2Te3 or Sb2Te3
powder
Binder 4 wt.% 96 wt.% -
Printing ink 20 wt.% 80 wt.%
Table 4.7 Process of thermoelectric material film.
Printing ink Off-contact Squeegee force
Flood bar
speed Printing speed
Bi2Te3 80 wt.%
Sb2Te3 80 wt.% 0.5 mm 1.5 kgw 50 mm/sec 65 mm/sec
Table 4.8 Sintering process of different gas.
Atomic Temperature Time Pressure Gas
Bi : 10.02 %
10.1×10-1 bar Atmosphere
Bi : 29.11 %
Figure 4.8 SEM images of thermoelectric material before sintering.
Table 4.9 Sintering process of different temperature.
Atomic Temperature Time Pressure Gas
Bi : 40.18 %
(a) 480 °C
(b) 560 °C
Figure 4.9 SEM images of Bi2Te3after sintering under different temperature.
(a) 480 °C
(b) 560 °C
(c) 585 °C
Figure 4.10 SEM images of Sb2Te3after sintering under different temperature.
Table 4.10 Thermoelectric properties of Bi2Te3 and Sb2Te3 film after sintering.
Atomic Sintering data Printing ink Seebeck coefficient
Electrical resistivity
Bi : 39.97 %
Te : 60.03 % 560 °C-240 min Bi2Te3 80 wt.% -57.06 μV/K 4.40×10-5 Ωm
Sb : 39.64 %
Te : 60.36 % 585 °C-240 min Sb2Te3 80 wt.% 64.70 μV/K 7.33×10-5 Ωm
4.3 熱電元件之製程的初步測試與探討
4.3.1 底電極之製程測試
首先使用第三章所提出的元件製程之第一道網版，選用 DuPont Materials Solamet™ PV502 Photovoltaic Composition 銀漿，並以成長上 1 μm 氧化矽的四吋矽晶圓為基材，進行底電極結構印刷測試。表 4.11 顯示
4.3.2 熱電結構之製程測試
已達到 20 μm 以上的厚度，但表面形貌不夠平整且高度參差不齊，對於後 續堆疊製程可能造成問題。若底電極改為物理或化學沉積方式製作，使電 極表面平整，將可減少上述的問題產生。
Table 4.11 Process of bottom electrode pad.
Printing ink
(viscosity) Off-contact Squeegee force Printing speed
PV 502
(50 Pa⋅s) 0.25 mm 1.5 kgw 30 mm/sec
(a) 50 μm
(b) 75 μm
(c) 100 μm
Figure 4.11 Defined patterns of bottom electrode pad.
Table 4.12 Sintering data of bottom electrode pad.
Temperature RT-400 °C 400-700 °C 700 °C
Time 1 hr 1 hr 2 hr
Table 4.13 Process of thermoelectric structure.
Printing ink
(Concentration) Off-contact Squeegee force
Flood bar
speed Printing speed
Bi2Te3
(80 wt.%) 0.15 mm 1.5 kgw 50 mm/sec 65 mm/sec
(a) 50 μm
(b) 75 μm
(c) 100 μm
Figure 4.12 Defined patterns of thermoelectric structure.
(a) 50 μm
(b) 75 μm
(c) 100 μm
Figure 4.13. Thermoelectric structure stacked on bottom electrode pad.
(a) 50 μm
(b) 75 μm
(c) 100 μm
Figure 4.14. Thickness of thermoelectric structure stacked on bottom electrode pad.
第五章 結論與未來展望
僅降低離版距離為 0.25 mm，以求得更精確的圖案表現，而結果顯示
4. 日後將進一步針對燒結的溫度與時間變數，影響熱電膜特性的研究與 比較，整理出一系列的特性分析，如燒結溫度與席貝克係數的關係圖、
燒結時間與電阻值的關係圖、XRD 分析圖…等。
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