本論文主要的目的在研究離子摻雜於積體電路中之元件區的源極/汲極以及介電層薄膜之性質與分析。吾人利用掃描式電子顯微鏡之二次電子激發原理定義離子佈植於源極及汲極的輪廓；除此之外並探討利用高密度電漿化學氣相沉積之金屬導線前介電層及金屬導線間介電層的化學及物理性質。

在本論文的第一部份將討論利用掃描式電子顯微鏡的二次電子影像定義離子佈植的輪廓。掃描式電子顯微鏡的二次電子影像已漸漸地被廣泛用來描繪二維的離子佈植的輪廓。然而摻雜(Doping)所造成的影像對比機制到目前為止還不是很清楚。本研究發現另一個對影像明暗對比有顯著貢獻的因素是來自p或n型金氧半電晶體的源極/汲極上矽化鈷結構所造成的應力應變。實驗結果顯示二次電子影像所呈現的亮區(Bright contrast)輪廓與利用穿透式電子顯微鏡(TEM)暗視野(Dark Field)技術拍攝到的應變輪廓範圍相當。另外，也證實在p型金氧半電晶體元件上的摻雜對比(Dopant Contrast)強度比實驗控片上的摻雜對比高出45%。因此可歸納出，p型或n型電晶體上二次電子訊號強度的增強是來自於矽化鈷結構在摻雜區域形成的應變而造成本區能帶的彎曲，使得二次電子的激發量增加。

本論文的第二部分將探討利用高密度電漿化學氣相沉積(HDP CVD)所成長的磷化矽玻璃(Phosphosilicate glass; PSG)當作金屬連結導線前介電層(Pre-metal dielectric; PMD)之物理與化學性質。磷矽玻璃薄膜是利用含磷的前驅物(PH3)與矽甲烷(SiH4)和氧氣在低於550oC下沉積而成。將初鍍的磷化矽玻璃薄膜在400oC的爐內退火10-30分鐘模擬在積體電路製程中金屬前介電層所經歷的熱循環。除此之外，還利用925oC的快速對退火製程(Rapid Thermal Process; RTP)10-30秒，測試磷矽玻璃在接近玻璃轉換溫度時的化學與物理性質。本實驗中利用各種分析儀器檢測磷矽玻璃薄膜的特性，如傅立葉紅外線吸收光譜儀（FTIR）、X-ray螢光分析儀（XRF）及X光化學分析儀（XPS）等。並測量PSG薄膜在熱循環過程中的應力磁滯現象，用以檢測磷矽玻璃薄膜在元件製程中經歷熱循環過程的熱穩定性。結果顯示有部分殘留的未鍵結的磷和P=O的化合物存在初鍍的PSG薄膜內，但後續的熱處理使得這些自由的磷原子與矽氧基(Si-O)產生再鍵結。除此之外，紅外線吸收光譜所標示的P=O吸收峰的強度經過退火後增強的結果與光化學分析儀所測得的結果一致。

最後一部份吾人將探討在積體電路中作為金屬導線間介電層(Inter-Metal Dielectric; IMD)的氟矽玻璃薄膜(Fluorosilicate Glass; FSG) 的性質。高密度電漿化學氣相沉積所沉積的氟矽玻璃薄膜由於它的低介電常數以及良好的間隙填充能力已經成功的被運用在超大型積體電路中的金屬導線間介電層。然而，在沉積過程中由於濺擊蝕刻所造成的溫度上升已經成為此薄膜性質不穩定的主要因素。因此，本研究利用沉積系統中獨立的氦氣冷卻系統(Independent Helium Cooling; IHC)將氟矽玻璃薄膜的沉積溫度控制在410oC~460oC之間。並檢驗在此溫度區間所沉積的薄膜性質：如氟的濃度及分佈、反射率、介電常數及間隙填充能力(Gap filling)與氦氣冷卻系統的關係。結果顯示，氟濃度隨著沉積時氦氣壓力的上升而增加，並且有較多的未鍵結氟原子存在薄膜中，這些未鍵結的氟原子可能會造成薄膜的缺陷，降低元件的良率; 同時，利用此氦氣冷卻系統，將氦氣壓力控制在9mtorr時得到一介電常數為3.43且擁有良好間隙填充能力的氟矽玻璃薄膜。

The objectives of this study are to investigate characterizes of ions doping in device’s source/drain regions and dielectric films used in integrated circuits (IC). The emission of secondary electron (SE) from scanning electron microscopy (SEM) was used to define the dopant profile of the source/drain region. In addition to, the chemical and physical properties of pre-metal dielectric (PMD) and inter-metal dielectric (IMD) deposited by high-density plasma chemical vapor deposition (HDP CVD) also investigate.

In the first section, secondary electron (SE) imaging with scanning electron microscopy has been used for two-dimensional dopant profiling. However, the mechanism of dopant contrast is still not yet understood. Here we propose another significant contribution from interface strain for the source/drain regions in p- and n-type metal-oxide-semiconductor (MOS) devices. The results show that the width of the dopant profile by SE imaging agrees well with the strain profile by dark-field technique with transmission electron microscopy. We demonstrate that the dopant contrast of the p-MOS device by SE imaging is higher than a test wafer by 45%. The enhanced SE signals for both p-MOS and n-MOS devices are caused by band bending through CoSi2-induced strain.

In the second part, high-density plasma chemical-vapor deposition (HDP CVD) phosphosilicate glass (PSG) films were evaluated for the application of pre-metal dielectric materials. The PSG films were deposited using phosphorous-related precursors reacted with silane and oxygen at a temperature ≦ 550℃. The as-deposited films were subsequently furnace-annealed at 400℃ for 10 to 30 minutes to simulate the effect of thermal budget on pre-metal dielectric layers in the current integrated circuit scheme. In addition, the PSG films were also annealed by rapid thermal processing at 925℃ for 10 to 30 seconds, to examine film stability near glass transformation temperature. Fourier transform infrared spectroscopy (FTIR), stress measurement, X-ray fluorescence analysis, and X-ray photoelectron spectroscopy (XPS) were used to characterize the PSG films. Film stress-measurement was used to examine the stress hysteresis of the PSG films in the thermal-budget process. The results show that residual inactive phosphorous and compounds with P=O bonds are present in the as-deposited PSG films. Some residual phosphorous became active after the thermal annealing. The FTIR results that show an increase in the P=O group upon numerous annealing treatments are in agreement with the XPS analysis.

In the last, the characterizations of fluorosilicate glass used as inter-metal dielectric material in integrated circuit (IC) will be discussed. High-density plasma chemical vapor deposited fluorosilicate glass (FSG) has been successfully used for the inter-metal dielectric material in ultra large semiconductor integration manufacturing due to its low dielectric constant and stable gap-filling capability. However, temperature rise and related effects due to sputter etch from the deposition process have become major concerns for film properties. In this paper, an independent helium cooling system was employed to control a suitable temperature range from 410ºC to 460ºC during FSG deposition. Subsequently, film properties including fluorine concentration, distribution, refractive index, dielectric constant and gap-filling capability were thus examined as a function of He pressure used in the cooling system. The results show that both deposition rate and fluorine concentration increase with increasing helium pressure, however, more fluorine becomes inactive, which might be present as defects. We have shown that a FSG film with a dielectric constant down to 3.43 as well as good gap-filling capability can be achieved when employing this new cooling system with 9 mtorr helium pressure.

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