鍺離子佈植技術應用於淺接面製作產生的晶體缺陷之退火行為及其消除方法和低壓化學沉積矽薄膜磊晶之研究

Abstract

當離子佈植技術應用於製作淺接面時，鍺離子佈植預非晶質化常被用來抑止氟化硼離子佈值的穿隧效應。本論文探討經由不同佈值條件的鍺離子預非晶質化與氟化硼離子佈值於矽中所產生的晶體缺陷之演化和消除方法。這些EOR缺陷(End-of-Range Defects)的形成與演變與離子佈植條件及後續的退火條件有關。本研究利用穿透式電子顯微鏡觀察晶體缺陷之演變和消除缺陷的方法與機制。 離子佈植所產生的晶體缺陷對於淺接面的電氣特性具有害。本研究利用微波電漿處理在表面形成氮化矽的薄膜，實驗結果顯示其可有效地縮小EOR差排環的大小；加上偏壓的微波電漿處理可以進一步縮小EOR差排環的大小；同時，我們利用碳離子佈植來消除鍺預非晶質化所產生EOR缺陷，我們發現，移除EOR缺陷的能力與鍺離子佈植的條件，碳離子佈植的Rp(Projected Range)位置，和接續的退火條件有關。在900°C，30分鐘，碳離子佈植的Rp越接近鍺離子佈植所造成的晶層與非晶層界面時，碳原子與間隙矽原子結合而形成碳化矽複合物以降低EOR缺陷的濃度能力越佳。經由穿透式電子顯微鏡的觀察，也顯示高能量╱高劑量鍺離子佈植的試片中，退火處理後有髮夾狀差排出現；在碳離子佈值的試片，在差排附近析出的碳化矽化合物則阻止了髮夾差排的滑移運動而使其無法以退火熱處理消除。 本研究探討低壓化學氣相沈積法所產生的非晶矽薄膜經離子佈植後之固相磊晶成長行為，鍺和矽離子佈植首先被用來將低壓化學氣相沈積法所產生的矽薄膜完全非晶質化，離子佈植並可打散原晶層與非晶層界面的氧化層，在後續的退火過程中，非晶質化的矽以固相磊晶的機制而成長，而得到品質優良的矽磊晶薄膜。感應式耦合電漿(Inductive Couple Plasma)亦被用進行試片表面處理。當使用氮氣進行表面處理時，氮化試片表面可提供空孔來增益原子的擴散速率，固相磊晶的速度得以增加。

For the fabrication of the shallow p+/n junctions, Ge+ peramorphization was employed to eliminate the channeling effect of BF2+ implantation. This thesis studied the extended defects in Si subjected to various Ge+-preamorphization and BF2+ implantation. The formation and evolution of extended defects depend on the implantation and subsequent annealing conditions. Transmission electron microscopy (TEM) has been employed to study the residual defects and their evolution as well as the methods and mechanisms to eliminate the extended defects are discussed. The extended defects are detrimental to the electrical properties of shallow p+/n junctions. Microwave plasma surface treatment was carried out to form a nitride layer on specimen surface. Such a surface nitridation was found to be effective to reduce the size of end-of-range (EOR) loops. The defect size reduction was more pronounced when the bias voltage was added to the plasma process. Carbon implantation was also employed to annihilate the EOR defects in Ge+-preamorphized Si. It was found that the efficiency of EOR defect removal depends on the Ge+-preamorphized conditions, the location of projected range (Rp) of carbon implantation, and subsequent annealing conditions. Carbon can capture the excess Si interstitials to form SiC complex and reduce the concentration of EOR defects. However, TEM observation revealed the emergence of hairpin dislocations when the dose and accelerating voltage of Ge+ implantation were high. For carbon-implanted specimens, the glide motion of hairpin dislocations would be inhibited by the SiC complexes formed in the vicinity of dislocations. The thesis also discussed the solid phase epitaxy (SPE) of Si thin film prepared by low pressure chemical vapor deposition (LPCVD). In the present work, Ge+ and Si+ ion implantations were utilized to amorphize the LPCVD Si film and mixed the interfacial oxide layer. Ge+ implantation with sufficiently high accelerating voltage and dose amount could break up the oxide layer and the regrowth of amorphous Si could proceed layer by layer during subsequent annealing. An epitaxial layer with superior quality could be obtained. The surface of specimen was also modified by inductive couple plasma (ICP) process. The ICP modification using nitrogen gas was able to accelerate the SPE process.