- 學位論文
鍺/矽化學氣相沉積磊晶異質成長與參雜
Heteroepitaxy Ge/Si and Dopant Incorporation by Chemical Vapor Deposition
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摘要
為因應尺寸不斷的縮小的互補式金氧半電晶體元件，鍺製程除了有與當前矽製程兼容的優勢外，鍺通道更具有比III-V族高的電洞遷移率。此外藉由成長矽鍺的汲極和源極使通道產生應變可用以提高鍺通道的電子和電洞遷移率，使鍺同時具有高電子以及電洞遷移率，故藉由產業界所使用的化學氣相沉積系統，來成長高品質的矽鍺及鍺材料在未來的互補式金氧半電晶體元件是必要的。 於本論文的第一部份，藉由鍺原子從被覆蓋的矽鍺量子點外擴散的現象來形成矽鍺量子環的生長機制將被再次討論，研究發現在不同的載流氣體環境之下會影響此種矽鍺量子環的生長。當氫原子較少覆蓋矽鍺量子點導致較多的矽成長覆蓋在量子點上，此覆蓋會阻礙鍺原子經由外擴散形成矽鍺量子環結構。除此之外，為了想在鍺基板型成此奈米微結構，我們討論了在鍺基板上成長矽的生長機制。一個與一般在矽基板上生長鍺狀況不同，從三維生長回歸到二維生長的機制，被第一次在鍺基板上成長矽的情形中發現。首先，矽量子點會先出現在鍺基板表面。在持續的矽沉積後，整個矽表面將會變平，會由原先的三維生長回歸到二維生長當中。我們發現由於在矽量子點的濕層的表面鍺濃度較高處會有較快的成長速率，而矽量子點的頂端表面鍺濃度較低有較慢的成長速率，最後導致原先三維生長形成的量子點最後變平回歸的二維生長的模式當中。 由於之前我們發現載流氣體以及鍺濃度會影響矽鍺生長模式，故本論文的第二部份會探討利用矽甲烷或二氯矽烷加鍺甲烷，在不同載流氣體以及不同鍺濃度之下，來研究影響矽鍺薄膜或甚至鍺薄膜成長速率以及光激發光特性的因素。研究結果發現:第一、提高矽鍺薄膜中鍺濃度確實會提高其成長速率。第二、在氮氣的環境中，鍺薄膜的成長速率以及利用矽甲烷和鍺甲烷形成的矽鍺薄膜成長速率增加，但若利用二氯甲矽烷及鍺甲烷形程矽鍺薄膜的成長速率卻會降低。成長速率增加原因在於較高的鍺濃度以及在充滿氮氣的環境中會使得薄膜表面氫氣較少，有利於矽或鍺原子的吸附來提高成長速率。但對於利用二氯矽烷形程矽鍺薄膜時，由於二氯矽烷不易脫附阻礙矽或鍺原子的吸附使得成長速率降低。 為了應用在汲極和源極對通道產生應變的技術或成長高濃度的無接面電晶體元件通道，在此外本論文最後研究有關鍺參雜的技術，藉由形成一高硼參雜或磷參雜的固態層，其參雜藉由擴散在鍺內形成淺接面。此技術避免因離子佈值型成的缺陷而造成的暫態擴散提升效應，此部分一開始會利用固態參雜擴散技術來形成接面，此技術為形成一高硼或磷濃度的固態層做為形成鍺參雜的來源，證實由於沒有因離子佈值型成的缺陷，此技術所製成的二極體具有較低的漏電流。但由參雜在鍺的固態溶解度很低，加上在活化時會因快速擴散而降低濃度，不利於型成鍺的淺接面，所以本研究利用在氣相沉積鍺薄膜時的直接參雜的技術來形成高濃度的參雜鍺，並利用不同的後續熱製成來活化，研究結果得到利用氣相沉積直接參雜加直接加熱技術可以得到3x1020 cm-3的p型參雜鍺，利用氣相沉積直接參雜加雷射活化技術所可以得到2x1020 cm-3的n型參雜鍺。
並列摘要
To scale down the CMOS devices in the future, Ge not only the compatible with current Si industry, but also the higher carrier mobility than Si channel. For hole mobility, Ge has the highest hole mobility even compared with group III-V materials. Using the SiGe stressor at source and drain, which is called strain technology, the Ge channel can have both higher electron and hole mobility. Base on its wide use of future CMOS device in the future industry, it is needed to grow high quality SiGe or even Ge material using chemical vapor deposition (CVD) system. In the first part of this thesis, the SiGe nanoring formation mechanism by Ge out-diffusion from the capped SiGe dot in the ultra-high vacuum CVD (UHV/CVD) is discussed. It is found that the formation of SiGe nanoring can be affected in different carrier gas environment. Less H passivation on the SiGe dot can result more Si cover on the top of dot and retard the Ge out-diffusion to form the nanoring. To grow the nanoring structures on the Ge substrate, the growth mechanism of the Si on Ge growth is studied. The transition from 3-dimensional (3D) to 2-dimensional (2D) growth for Si on Ge, which is different from the Ge on Si case, was observed for the first time. The Si quantum dots can be observed in the initial Si growth on Ge. With the increasing Si deposition, the surface can be flatten without any nanostructures above. At the wetting layer of SiGe dot, more Ge coverage on the surface leads to higher growth rate than the peak of the dot. This different Si growth rate at the SiGe dots region leads to the growth transition from 3D to 2D of Si growth on Ge. Base on the study on carrier gas and Ge content can affect the SiGe growth mechanism, the second part of this thesis will study the growth rate the photoluminescence characteristics of SiGe and Ge film using silane (SiH4), dichlorosilane (SiCl2H2) and germane (GeH4) in the rapid thermal CVD (RTCVD). It is found that: 1. the SiGe growth rate can be enhanced by Ge content. 2. the SiGe and Ge growth rate using SiH4 and GeH4 can be enhanced in N2 environment. however, the the SiGe growth rate using SiCl2H2and GeH4 can be reduced. Harder desorption of gas phase SiCl2 to retard the coming Si or Ge adsorption can be the reason for reduced growth rate. For the application of source/drain stressor or the channel of junction less device, the doping technology of Ge is studied in the third part in this thesis. The first technology is the solid phase doping for shallow junction. The solid layers, which have high boron or phosphorous dopants, can diffusion to Ge for shallow junctions. Due to the ion implantation damage free, the diodes doped by solid phase doping have low leakage. However, the dopant solid solubility in Ge is low and diffusion is high during the following activation. So the in situ doping by CVD with different post activation is used to grow high doped Ge. The 3x1020 cm-3 p-type Ge can be reach directly by in situ doping and in situ H2 anneal. Due to the fast phosphorous diffusion, the rapid thermal anneal (RTA) and laser anneal are used to activate n-type dopant. The 2x1020 cm-3 n-type Ge can be reach directly by in situ doping and laser anneal.
參考文獻
Chapter 1
[4] M. Lundstrom, International Electron Devices Meeting (IEDM), Technical Digest, 789 (2003).
[5] C. Jungemann and B. Meinerzhagen, International Electron Devices Meeting (IEDM), Technical Digest, 191 (2003).
[6] A. G. O’neill and A. D. Antoniadis, IEEE Trans. Electron Devices, 43, 911 (1996).
[7] B. S. Meyerson, IBM J. Res. Develop., 44, 132 (2000)