使用低壓化學氣相沉積法成長氧化鉭薄膜

Abstract

本論文是以tert-butylimdotris (diethylamido)tantalum為前驅物在通水氣 (0~1.2 mg/min)及氧氣 (200 sccm)下分別以673-873 K以及573-873 K下成長氧化鉭薄膜.並在大氣壓力下通氧氣以1123 K做事後的回火處理. 並使用了SEM, AFM, AES, ESCA, XRD, RGA,GC/MS鑑定薄膜的組成及型態. 在回火前通水氣可得到顆粒狀的薄膜, 而通氧氣沉積的薄膜則為柱狀. 回火後薄膜有收縮現象, 且顆粒皆變大. 在不通水氣下有26-40A/min的成長速率, 通水氣的成長速率則在4-8.4 A/min, 通氧氣的成長速率略高於通水氣下的成長速率. 由AFM亦發現回火後粗糙度增加. 由AES對回火前的薄膜做縱深分布發現氧鉭在膜內分佈均勻且碳並未深入裡層. 結晶性方面回火前皆沒有結晶性. 回火後可得到 b-Ta2O5的X-ray繞射圖.即使是不通水氣的狀況下所成長的薄膜在經回火後也呈現相同的情形. 由RGA分析反應可發現到Me2C=CH2, CH3CN, Et2NH, 以及H2. 而由GC/MS也發現HONEt2. 為了更進一步了解所沉積的薄膜的電性, 也測量了在873 K下通氧氣沉積的薄膜不經回火及分別經過30, 60分鐘回火的C-V及I-V圖. 可發現漏電流在回火後被抑制在2x10-8 A/cm2.在回火30分鐘時其崩潰電壓3.0 MV/cm, 介電常數則為22. 回火60分鐘後的介電常數則有35.-

A procedure is studied to produce tantalum oxide thin films. The deposition uses tert-butylimidotris (diethylamido)tantalum in the presence of water vapor (0-1.64 mg/min) and oxygen gas (200 sccm) under the temperature 673-873 K and 573-873 K, respectively. Post annealing is employed under atmosphere oxygen at 1123 K. SEM, AFM, AES, ESCA, XRD, RGA, GC/MS are used to characterize the thinfilms. Grain size ranging from 30-60 nm are observedwhen deposited with H2O. Columnar grains are found when deposited with oxygen.Films are shrunk and rougher after annealing. Growth rates of the films grownwithout water vapor are 26-40 A/min* while the growth rate of films grown withH2O and O2 are 4-8.4 A/minand 10 A/min, respectively. Distribution of tantalumand oxygen is uniform in the film as indicated by AES. Films are amorphous before annealing and crystallized into b-Ta2O5 after annealing. With RGA andGC/MS,H2C=CMe2, CH3CN, Et2NH, H2 and HONEt2 are found in the deposition. Electrical properties of the films grown with oxygen are also measured. Leakagecurrent are suppressed to 2x10-8 A/cm2 after annealed for 30 min. Breakdownvoltage is 3 MV/cm. Dielectric constant of anneal 30 min and 60 min are 22 and 35, respectively