鈦矽氧類嵌附減光式相移圖罩之研製與模擬

Abstract

嵌附減光式相移圖罩可增加光學微影製程的解像度與聚焦深度，且易製造、修補、檢測，故近年來深受半導體界重視。目前已商業化的此式圖罩有導電性較差和對可見光之透光率較大等缺點。 本論文發展TiSixOy作為248奈米和365奈米嵌附減光武相移圖罩之嵌附層材質。研究結果發現： 1.TiSixOy薄膜可藉由改變濺鍍薄膜的條件而得到符合嵌附層的需求。此薄膜對於i-線365奈米的折射率為2.508，吸光係數為0.521，符合相移角度180度的厚度為121奈米，此時透光率為8.5％；此薄膜對248奈米入射光的折射率為2.419，吸光係數為0.644，符合相移角度180度的薄膜厚度為87奈米，此時透光率為4.5％。 2.TiSixOy薄膜對可見光波長範圍的透光率低(<40％)，比電阻小(<103Ω-cm)，且具抗酸鹼能力。此薄膜經長時間深紫外光（254奈米寬帶）照射後，其透光率有些許上升，反光率則略微下降。 3.本論文結合了斜率法和反光率—透光率法，在n-k平面上選擇適當的計算範圍，篩選出一組最有可能的解，不但解決了原本R-T法可能有多組解的困擾，而且也大幅縮短了計算時間。 4.以Cl2/NF3為蝕刻氣體進行活性離子蝕刻(RIE)，利用田口法來規劃蝕刻實驗，並以二步驟蝕刻法完成蝕刻，可大幅提昇TiSixOy薄膜對SiO2薄膜的蝕刻選擇比，並且降低了蝕刻後薄膜的粗糙度。 本論文初步改善了國外報導使用其他材質應用於嵌附減光式相移圖罩嵌附層材質之缺點。本論文相關題目值得繼續深入研究。

Resolution and depth of focus in photolithography can be improved by an embedded attenuated phase shift mask (EAPSM), the fabrication, repair and defect inspection of the EAPSM are easy, therefore, EAPSM gained much attention from semiconductor industry. Currently, the disadvantages of EAPSM are the low conductance and high transmittance to visible light, etc. In this thesis, study on the materials of TiSixOy as embedded layer in EAPSM for 248 and 365 nm is emphasized. The results are reported as follows: 1.By changing the conditions of sputtering, qualified embedded layer could be obtained. For 365 nm, TiSixOy with thickness 121 nm has a degree of phase shift 180 , its transmittance at this thickness is 8.5%, refractive index is 2.508, extinction coefficient is 0.521. For 248 nm, TiSixOy with thickness 87 nm has a degree of phase shift 180, its transmittance at this thickness is 4.5%, refractive index is 2.419, extinction coefficient is 0.644. 2.TiSixOy has a low transmittance (<40%) to visible light, small specific resistance (<103Ω-cm), and good resistance to acid and base. The irradiation of this film by deep ultraviolet light (254 nm broad band) for a long time, transmittance increased and reflection decreased slightly. 3.This thesis combined the slope method and the reflection-transmission method, selected suitable calculation range in the n-k plane, chose the most possible domain, solve the problem of multiple domains of reflection-transmission method, and reduced the calculation time. 4.Using Cl2/NF3 gas as RIE etchant, Taguchi method to design the etching experiments, and two step to complete the etching, the selectivity of TiSixOy to SiO2 increased largely and the roughness of thin film after etching was also reduced. This study indicated a preliminary improvement of embedded material's properties for EAPSM compared with reported materials. This topic is worthy to study further.