研究生: |
張晏榕 Chang, Yen-Jung |
---|---|
論文名稱: |
鐵磁增強電感耦合電漿放電數值模擬計算分析 Numerical Simulation Study of Ferromagnetic Enhanced Inductively Coupled Plasma Discharges |
指導教授: |
柳克強
Leou, Keh-Chyang |
口試委員: |
寇崇善
潘彥儒 |
學位類別: |
碩士 Master |
系所名稱: |
原子科學院 - 工程與系統科學系 Department of Engineering and System Science |
論文出版年: | 2019 |
畢業學年度: | 107 |
語文別: | 中文 |
論文頁數: | 150 |
中文關鍵詞: | 鐵磁增強電感耦合電漿 、遠距電漿源 、磁極增強電感耦合電漿 、流體模型 |
外文關鍵詞: | Ferromagnetic Enhanced Inductively Coupled Plasma, remote plasma system, magnetic-pole enhanced inductively coupled plasma, fluid model |
相關次數: | 點閱:3 下載:0 |
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鐵磁增強電感耦合電漿,相較於電感耦合電漿,在耦合器中有較低的功率消耗,能量傳輸效率較好,而有比較高的功率因數(power factor)。本研究主旨為探討鐵磁增強電感耦合電漿(ferromagnetic enhance inductively coupled plasma)的放電特性。本研究建立電漿流體模型,結合電磁場與流體熱傳理論來進行模擬計算。主要探討的有兩種鐵磁增強電感耦合電漿源,分別是磁極增強電感耦合電漿(magnetic-pole enhanced inductively coupled plasma , MaPE-ICP)與鐵磁增強電感耦合遠距電漿(ferromagnetic enhanced inductively coupled plasma, FMICP),前者通常操作在較低氣壓,較適合大面積電漿製程之應用,後者常作為遠距電漿源(remote plasma source, RPS)之應用。
在FMICP模擬計算分別以三維與二維模型模擬計算分析。其中三維模型計算流場與電磁場分布,二維模型計算電漿、電磁場與熱傳耦合的結果分佈。在三維模型的結果顯示,得出電磁場分布,氣體流動為螺旋形方向。二維模型分為兩種,分別為平面模型(2D x-y model)與二維柱型(2D r-z model)。前者考慮鋁腔體與陶瓷的效應,後者則沒有考慮其效應。二維平面模型模擬結果顯示,在總功率約5 kW,2 Torr氬氣氣壓下,體平均電子密度約91019 1/m3、體平均氣體溫度約818.86 K、體平均電子溫度為1.2 eV。固定1 Torr氣壓下,體平均電子密度與體平均氣體溫度隨功率增加而上升,從約20 W到5 kW,體平均電子密度從約1.861017 上升至5.11019 1/m3 與體平均氣體溫度從304 K上升至630 K。此外,因DC BREAK的效應在低功率時,吸收功率密度分佈與電子密度分佈集中在DC BREAK附近,電漿特性為電容性,然而功率超過約1.6 kW以上時,電子密度分佈與吸收功率密度分佈均勻分佈整環電漿區域,電漿特性轉為電感性。另一方面,在低功率下,在鋁腔體的電流大小比在電漿中大,如功率約500 W,電漿電流約0.008 A/m,而在鋁腔體電流約36.3 A/m。而在高功率下,在電漿區中的電流會大於在鋁腔體中的電流,功率在約5 kW下電漿電流約3434.8 A/m鋁腔體電流約516.3 A/m。此外,比較總功率、在鋁腔體內的吸收功率與電漿吸收功率隨線圈電流的變化,從結果顯示,大部分的吸收功率都被電漿所吸收。另外固定線圈電流3430.4 A/m下,氣壓上升功率下降是因,在氣壓1 : 2 : 4 Torr下功率的比值為3.67 : 3.32 : 3.01。而且氣壓上升,體平均電子密度與氣體溫度皆上升,從氣壓1 Torr至4 Torr,分別上升至約1020 1/m3 與1100 K。
在FMICP二維柱形模型模擬方面,結果顯示在總功率為100 W,2Torr氬氣氣壓下,其體平均電子密度、電子溫度與氣體溫度分別約為,31018 1/m3 ,1.03 eV與321.3 K。另一方面,在高功率的電漿密度比低功率的軸向電漿密度分佈均勻,原因為在高功率下,磁場在腔體頂端與底端磁場比其他區域大,以至於在此區域中感應電場也較大,故在這兩個區域有較高的吸收功率,所以電子密度在高功率比在低功率時均勻。此外在高功率下電漿腔體中間區域的電場較低功率低,原因在於高功率的電漿電流要低功率來得大,故感應更大的與線圈電流相反方向的磁場。
在MaPE-ICP模型模擬計算方面,其中磁極為錳鋅材料,介電窗是陶瓷材料。模擬參數固定300 W,30 mTorr氣壓下,探討不同鐵芯的形狀與位置對電子密度均勻度的影響。由模擬結果顯示,透過改變不同鐵氧體鐵芯的形狀或位置,使在電漿區域的電場分佈較為均勻,故電漿的均勻度上升。
Ferromagnetic enhanced inductively coupled plasma (FMICP) has lower power loss in the coupler and has better power transfer efficiency than the conventional inductively coupled plasma(ICP) . So FMICP has higher power factor than ICP .
This study investigates discharge characteristic of FMICP. In this study building fluid plasma model , combines electromagnetic field and heat transfer theory to compute numerical simulation . There are two different types of FMICP to investigate in this study respectively , magnetic-pole enhanced inductively coupled plasma (MaPE-ICP) ,which is used to do big area plasma process , and the FMICP with closed ferrite core , which is used to be remote plasma system(RPS) to clean the process chamber .
Use three dimension and two dimension model to do numerical simulation analysis .In three dimension model, simulate the distribution of flow and electromagnetic field . The two dimension model is planar and column type model respectively . In three dimension model, the simulation result reveal that the electric field direction is azimuthal direction in plasma region and the direction of flow is helical , For the planar type model, at 5 kW total power and 2 Torr gas pressure, the volume averaged electron density is roughly 91019 1/m3 , volume averaged gas temperature is roughly 818.86 K and the volume averaged electron temperature is roughly 1.2 eV . Fixing 1 Torr gas pressure, volume average electron density and gas temperature respectively increase to 51019 1/m3 and 630 K . And at low power, the current in Al chamber is higher than the current in plasma region . In addition to, the effect of DC BREAK causes the uniform electron and power density distribution that the characteristic of plasma is capacitive at low power . And at high power , the electron density distribution is uniform around the plasma chamber and thus resulting in the inductive plasma characteristic . However at high power , the current in plasma region is higher than the current in Al chamber . For instance, at 5 kW total power the plasma current is roughly 3434.8 A/m and current in Al chamber is roughly 516.3 A/m . And at low power, the current in plasma region is lower than the current in Al chamber . For instance, at 500 W total power the plasma current is roughly 0.008 A/m and current in Al chamber is roughly 36.3 A/m . The most of power density absorb in plasma comparing to which is in plasma and Al chamber . In addition , fixing coil current 3430.4 A/m, total power decrease with gas pressure due to power ratio 3.67 : 3.32 : 3.01 at 1, 2, and 4 Torr . And volume average electron density and gas temperature increase with gas pressure , which are respectively increase to 1020 1/m3 and 1100 K .
For column type model, at 100 W total power and 2 Torr gas pressure , the volume averaged electron density, electron temperature and gas temperature is roughly 3.331018 1/m3 ,1.03 eV and 321.3 K respectively . On the other hand, the electron density is more uniform at high power than it is at low power . Because magnetic flux density is higher than the other position at the top and bottom of plasma chamber so that the inductive electric field is high in these region . So the power density is more uniform at high power than it is at low power . In addition , the electric field in the middle of plasma region at high power is lower than which is at low power . The reason is that plasma current at high power is higher than which is at low power, so the magnetic flux density induced back higher magnetic flux density .
For MaPE-ICP model , the ferrite core is Mn-Zn ,and the dielectric window is ceramic . At 300 W total power and 30 mTorr gas pressure, investigate different position and geometry of ferrite core affect of the uniform of plasma density . In this model , the simulation result reveal that different geometry and position makes the electric field is uniform in plasma region , and thus the plasma uniformity increase .
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