第三章 實驗步驟
3.4 濺鍍系統簡介
(a) 濺鍍系統
本系統為交流式濺鍍系統，濺鍍過程通入氧氣與氬氣。為了避 免氧氣還沒反應時就直接被真空幫浦抽出，所以本系統利用一個圓 環型的玻璃管將氧氣引入濺鍍腔的上方，使得游離的氧分子存在於
第三章 實驗步驟
真空濺鍍腔內的機率增大。濺鍍系統如圖 Figure 3.2，其中真空腔 體為一玻璃中空圓柱環，而整個濺鍍腔體是石英玻璃中空圓柱與不 銹鋼罩所構成。加熱基板則位於真空腔體的中央位置。濺鍍槍為 Reactive Magnetron RF System，作用在藉由所產生出來的電磁場 而能將游離態的氧氣與氬氣侷限在基板和靶材的中間，此時在適當 的電磁場作用下，在靶材附近就會有電漿形成。本系統是由 RF Rnerator 所產生，最大輸出功率為 550 瓦、工作頻率 13.56Mhz，
靶材距離基板 5 公分，並且藉由匹配系統使得 RF 的反射功率維持 0 瓦。濺鍍靶材：銥 (Ir) 金屬，純度 99.95%，直徑 1 inch，厚度 1/8 inches；五氧化二鉭 (Ta2O5)，純度 99.99%，直徑 2 inch，厚 度 1/8 inches，密度 6.91g/cc。
第四章 結果與討論
第四章 結果與討論 的指標。其中有ㄧ點我們可以發現到此實驗數據比液態 Severinghaus 的二氧化碳感測器所預期的靈敏度來的少。這是因為與離子所處的環境
現象相當合理，因為氧化銥的表面積與體積的比值較大，可在小範圍內
第四章 結果與討論
(iii) 注射含有 0.05ml CO2氣體 + 0.05ml H2 氫氣
我們可以由圖 Figure 4.10 中看出被(i)(ii)(iii)三種不同組合的 氣體注射後，所得到峰值電位差都相同，因此我們可以推論在氧化 銥薄膜上面再多濺鍍一層五氧化二鉭薄膜的確對抵抗氧氣的干擾 有顯著效果。所以在此感測器裡面注射氧氣或氫氣都不會對感測器 的峰值電壓差有所改變。
4.5 無通水氣時對元件感測性質的影響實驗
圖 Figure 4.11 是無水狀態下的對感測器對氣體感測響應圖，從圖 中我很可以看到在無水狀態下的感測器不僅對二氧化碳反應的即時性 差，而且大大拉長反應平衡的時間。但是對於氧氣與氫氣仍無反應，這 也顯示多鍍上ㄧ層五氧化二鉭來當作阻擋層，即使在無水狀態下也不會 造成它對二氧化碳發生感測上的影響。我們可由反應式來發現此無水狀 態對固態電解質是不利的。無水反應式如下所示
CO2 + H2O ÍÎ H2CO3 ÍÎ H+ + HCO3- ÍÎ 2H+ +CO32-
所以對於此固態型二氧化碳感測器最重要的機制就是要水來參與反 應。若是無水加入反應，此感測器根本是不可能動作的。但是為了得到 無水狀態時感測器會發生怎樣變化，所以我們是採用先通含水氮氣進去 感測元件的動作區讓固態電解質薄膜能殘留部分水份，之後再關掉含水 的氣泡產生器，以此來完成此實驗步驟。
第五章 結論
成功的把會受氧氣干擾的因素解決，這對此二氧化碳感測器有很大的 助益。由於本感測器目前還處於實驗室使用階段上，因為此電位式二 氧化碳感測器在感測氣體時需要有水氣通過才能發揮感測能力。對於 此研究方面仍有很大發展性，像是我們可以在固態電解質裡面添加適 當保濕的材料進去，讓水氣分子可以保留在固態電解質薄膜內，而不 會影響到對二氧化碳感測，這樣就可以解決需要通水氣的問題。
本感測元件經過改良不僅不影響本身感測能力而且對於氧氣又 能有抵抗干擾的能力。再加上本感測器又是電位式訊號，如此搭配上 數位電子電路的設計便可將感測訊號即時顯現在顯示面板上，將之製 成輕、薄、短、小、價格低廉的數位型電位式二氧化碳感測器。日後 若運用在商業販售上，便會取代目前以紅外線為主的二氧化碳感測 器，而成為新主流的二氧化碳感測器。
---參考文獻---
參 考 文 獻
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731-741
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Figure 2.2 氣體感測機制說明圖
Si Substrate
---圖表---
0.6 mm
(b) (a)
Figure 3.1 (a) microelectrode array pattern . (b) stainless mask .
0.4 mm 0.6 mm 0.4 mm 0.3
mm 0.6 mm 0.4
mm
0.4 mm
0.4 mm
Figure 3.2 The sputtering equipment setup.
Quartz cylinder shield Magnetron Sputter source
In line regulator RotaMeters Glass cylinder
(ψ=21cm)
Substrate Holder
Cooling water in
out Matching
Box RF generator
Vacuum Gauge Mechanical Pump
Ar Gas ring
Viton L-gasket
ThermoCouple Gauge
Heater power Supply
O2
Figure 3.3 真空換氣系統裝置圖 集氣瓶
抽氣幫浦 氣瓶
氣瓶閥
發泡器
閥門開關 開關閥
開關閥
矽油 氣壓計
Oxide Pt /Cr
SiO2 Si3N4
N type Silicon
Figure 3.4 Schematic side viewof the summarized process flow for the lift-off processes.
Positive Photoresist Coating
Exposure ＆ Development
Remove Photoresist Sputtering
Deposition Oxide
---圖表---
Silicon/SiO2/Si3N4
Pt /Cr flag
IrO2 thin film
(a)
(b)
(c)
(d)
PVA‧KHCO3
Ag epoxy Epoxy IrO2 thin film
Figure 3.5 Schematic side view and top view of the summarized process flow for the fabrication of a sensor.
(+) (-)
O-ring seal Plastics
Syringe needle inlet Syringe needle outlet
Epoxy
Ag epoxy Epoxy
PVA•KHCO3 Si Subtrate
IrO2
(e)
(f)
Epoxy
Figure 3.6 感測小流量二氧化碳實驗裝置圖
Syringe pump
N2
Flowmeter
DI water
Bubbler Electrometer
Keithley 617
Strip chat recorder
Gas-tight syringe
(-) (+)Vdrop
CO2
N2 carrier gas Switch valve
Figure 3.7 微量二氧化碳快速注射裝置圖
N2 carrier gas N2
Flowmeter
DI water
Bubbler Electrometer
Keithley 617
Strip chat recorder
(-) (+) Vdrop
CO2 Switch valve
---圖表---Two terminal method Potential steps
Potential uphill and downhill by gradually increasing and decreasing the percentage of CO2 in N2 gas at 1 atm ,298K and H2O saturation. The total flow rate is kept at 14 ml/min.
Figure 4.1 多濃度表現階梯電位圖
500 1000 1500 2000 2500 3000
0
Potential difference (mV)
Time(sec)
Two terminal method Potential steps
Potential uphill and downhill by gradually increasing and decreasing the percentage of CO2 in N2 gas at 1 atm , 298K and H2O saturation. The total flow rate is kept at 14 ml/min.
Figure 4.2 大面積多濃度表現階梯電位圖
0 500 1000 1500 2000 2500 3000
10
Potential difference (mV)
Time(sec)
---圖表---Two terminal method Characteristic
Potential vs. logarithmic concentration of CO2 . The average slope 14 mV/dec.
Figure 4.3 電位差 vs. 二氧化碳注射濃度對數圖
100 101
35 40 45 50 55 60 65 70 75
Potential difference (mV)
log [ % of CO2]
Minc = 33.46 mV/Dec increasing
Two terminal method Characteristic
Potential vs. logarithmic concentration of CO2 . The average slope 14 mV/dec.
Figure 4.4 大面積氧化銥的電位差 vs.二氧化碳注射濃度對數圖
100 101
35 40 45 50 55 60 65 70 75
Potential difference (mV)
log [ % of CO2]
Minc = 28.15 mV/Dec increasing
---圖表---Two terminal method
Potential variation with respect to reference electrode vs. time under repeated injections of 0.1ml CO2 under a constant flow of N2 and saturated with H2O. The Plot shows the device is rapidly response.
Figure 4.5 快速注射小量二氧化碳即時反應實驗圖 ( IrO2-Ta2O5)
0 200 400 600 800 1000 1200 1400 20
40 60 80 100 120
Potential difference (mV)
Time (sec) 0.1ml
Injection of CO2
Two terminal method
Potential variation of IrO2-Ta2O5 sensing electrode with respect to the refernce electrode vs. time under a series of fast , small quantities CO2
injections under a constant flow of N2 stream. The concentration of PVA·
KHCO3 used on sensing electrode section and reference electrode section were 2mM. The line in the insect figure has a slope of 2788.05 [mV * sec /log ( % CO2 in N2)].The N2 flow rate is kept at 28ml/min,1 atm , 298K , and H2O saturation.
Figure 4.6 多濃度低流量快速注射實驗 ( IrO2-Ta2O5 )
0 150 300 450 600 750 900 1050 1200 1350 0
20 40 60 80 100
Potential difference (mV)
Time (sec) Injection of CO2
0.2ml
0.010ml 0.025ml
0.05ml 0.06ml 0.08ml 0.1ml
Two terminal method
Potential curve shade area vs. logarithmic injected CO2 quantity under constant 14 ml/min N2 flow with H2O saturated at 1 atm, 298K. The slop is 2788.05 mV*sec/Dec.
Figure 4.7 積分面積 vs 快速注射二氧化碳氣體濃度對數圖
10-2 10-1
1500 2000 2500 3000 3500 4000 4500 5000 5500
intergrate area ( 60 mV*sec)
[ injected CO2 quantity (ml) ] Y = 7787.38 + 2788.05 X
Two terminal method
Potential variation with respect to the reference electrode vs. time under 0.1ml O2 injection with N2 flow at 1atm,298K,and H2O saturation. The N2 flow rate is kept at 14 ml/min.
Figure 4.8 氧化銥感測元件對氧氣干擾實驗圖 0.1ml
Injection of O2
-200 0 200 400 600 800 1000 1200
14 15 16 17 18 19 20 21 22 23 24 25
Time (sec)
Potential difference (mV)
---圖表---Two terminal method
Potential variation with respect to the reference electrode vs.
time under 0.1ml O2 injection with N2 flow at 1atm,298K,and H2O saturation. The N2 flow rate is kept at 14 ml/min.
Figure 4.9 氧化銥-五氧化二鉭感測元件對氧氣干擾實驗圖
0 150 300 450 600 750
39 42 45
Potential difference (mV)
Time (sec) Injection of 0.1ml O2 gas
Two terminal method
Potential variation with respect to the reference electrode vs.
time under 0.05 ml CO2 , 0.05 ml CO2 + 0.05 ml O2, and 0.05 ml CO2 + 0.05 ml H2 injection with N2 flow at 1atm, 298K,and H2O saturation. The N2 flow rate is kept at 14 ml/min.
Figure 4.10 檢測氧氣對元件干擾的混合氣體實驗圖
0 200 400 600 800 1000 1200
60 70 80 90 100 110 120 130
Potential differece (mV)
Time (sec) injection
0.05 ml CO2
0.05 ml CO2 + 0.05 ml O2
0.05 ml CO2 + 0.05ml H2
---圖表---The terminal method
Potential variation with respect to the reference electrode vs.
time under 0.05 ml CO2 , 0.05 ml CO2 + 0.05 ml O2, and 0.05 ml CO2 + 0.05 ml H2 injection with N2 flow at 1atm, 298K,and without H2O saturation. The N2 flow rate is kept at 14 ml/min.
Figure 4.11 檢測氧氣干擾混合氣體與無水氣條件下實驗
-100 0 100 200 300 400 500 600 700 800 900 1000 20
30 40 50 60 70
Potential difference (mV)
Time ( sec )
0.05 ml CO2 0.05 ml CO2 + 0.05 ml O2 0.05 ml CO2 + 0.05ml H2
Injection
Ι. IrO
2( iridium oxide ) properties :
1.結構 : rutile structure
2.分子量( Formula weight ) : 224.216 ( g/mol ) 3.物理特性( Physical properties ) :
․顏色( Colour ) : black or brown
․外觀( Appearance ) : crystalline solid
․熔點( Melting point ) : 1070 ( °C ) ( decomposes )
․密度( Density ) :11700 ( kg /m3 )
․電阻( resistivity ) : 3 ~ 6×10-5 ( Ωcm ) (室溫)
4.組成分析與氧化數( Element analysis and oxidation numbers ) : 成 分 百 分 比 氧 化 態 電 子 組 態
Ir 85.73 4 [Xe].4f14.5d5 O 14.27 -2 [He].2s2.2p6
Ir O
---附錄---