鎢,鈦與氮化鈦金屬化學氣相沉積在積體電路上的應用與研究

Abstract

本論文的研究分為兩大主題:第一個主題是將低介電常數材料(摻氟的二氧 化矽)與金屬化學氣相沉積(鎢，鈦及氮化鈦)相結合以降低電阻電容，達 到減少RC的延遲時間。但摻氟的二氧化矽(SiOF)的最大缺點是易吸水，而 造成介電常數的上升，且使鋁管洞電阻(via resistance)上升。用氨電漿 對摻氟的二氧化矽做後處理，可提升其抗吸水性。選擇性金屬化學氣相鎢 沉積之前，鋁管洞的前置清洗非常重要。我們發現用一羥胺加介面活應性 劑((NH2OH)2H2SO4+surfactant)的溶液可有效地清除氧化鋁。我們將此處 理方法運用在鎢塞的製作，並且探討Al/W/Al結構的接觸電阻。相同地， 在化學氣相鈦及氮化鈦沉積之前，我們也嘗試用多種不同的前置處理來去 除鋁表面的氧化鋁。發現乾式前置處理的效果最好。第二個主題探討化學 氣相沉積氮化鈦的特性中，用低壓化學氣相沉積可長出高均覆性的氮化鈦 ，且成功地填入點零五微米大的矽管洞而不會產生空洞(void)。再者四氯 化鈦的流量與氮化鈦沉積速率相關，在反應速率限制區域成長的氮化鈦具 有高均覆性且均勻的特質。最後，用氨電漿對氮化鈦做後處理，可降低其 電阻係數，為鋁與銅的應用提供絕佳的阻障(barrier)特性。 In this thesis, two major topics are studied:The first topic is the reduction of RC delay time with combining low dielectric constant materials such as fluorine-doped SiO2 (SiOF) and metal chemical vapor deposition (tungsten and titanium/titanium nitride). Silicon dioxide doped with fluorine (SiOF) may be used as an intermetal dielectric in multilevel metallizations due to its lower dielectric constant as compared to SiO2. But SiOF absorbs moisture easily which results in an increase of the dielectric constant and the via resistance. NH3 plasma post- treatment can improve the moisture resistance of SiOF film.For the aluminum substrate, pre-clean of aluminum via is critical to the selective CVD-W process. Various pre-clean solutions are tried to clean the aluminum surface. (NH2OH)2H2SO4+surfactant is found to be effective in removing the native metal oxide (Al2 O3) prior to tungsten depesition.Before CVD Ti/TiN deposition, various pretreatments are also used to remove Al2O3. We have found that dry-etching has the best capability to remove Al2O3. The second topic is the characterization of CVD-TiN film. Conformal TiN films have been deposited by low pressure chemical vapor deposition (LPCVD) in a rotating disk reactor, using TiCl4 and NH3 with N2 as dilute. TiN plugs with 500* contact size have been firstly demonstrated. No void formation is observed in the TiN plug. This result indicates that the LPCVD-TiN has high ability for filling very fine contact holes. In addition, deposition rates as a function of TiCl4 flow rates are measured. Surfac