Mosaic拼接法高质量大尺寸单晶金刚石生长研究

发布时间：2018-03-10 02:34

本文选题：单晶金刚石　切入点：CVD法　出处：《哈尔滨工业大学》2016年硕士论文　论文类型：学位论文

【摘要】：金刚石具有极高硬度、热导率、优异的光学及电学性质,在多个应用领域都可能成为不可替代的最佳材料。针对单晶金刚石的CVD的生长和尺寸增大严重受到籽晶衬底尺寸的限制的问题,本文对Mosaic拼接法高质量大尺寸单晶金刚石生长进行了较为详实的理论分析和实验研究,通过对几块HPHT籽晶拼接放置,在其上同时进行生长,使得CVD生长层连接成为一个整体,突破单块籽晶生长因边界的多晶生成而限制了外延生长层尺寸的难题,以获得大尺寸CVD单晶金刚石层。首先对单晶金刚石生长的化学本质和沉积过程中初期的生长模式进行了总结分析与实验论证。研究了CVD生长的化学本质及生长过程中几种重要组分如原子[H],CH*等及其相关反应方程式的程度对反应速率的而影响。通过实验和理论分析讨论了同质外延初期生长模式为岛状生长向层状台阶流动模式的转变现象。附着物会随着生长过程镶嵌于CVD生长层中,造成晶格畸变和内应力;而大刻蚀坑所揭露的深层位错或包裹体也会由于晶格错配和位错扩展,使得其上的CVD生长层具有较高的缺陷密度,这都会严重影响CVD外延生长层的质量。对单晶金刚石生长进行了较为系统的分析,并对影响其生长质量和速率的各种因素分别进行了实验研究。通过PL谱、X射线摇摆曲线和等离子体刻蚀处理,表征籽晶的质量和缺陷密度,总结出高质量HPHT籽晶所必须具备的指标。此外,籽晶侧面是否抛光、温度、微波功率、碳源浓度和杂质元素对籽晶生长的速率和质量都有着极大的影响。侧面抛光的籽晶可以使得侧边生长的多晶相推迟出现,进而提升使CVD外延生长层面积增大的可能性,且温度越高、碳源浓度越高,CVD层生长速率越快,但质量也相对越低。所以采用了较为折中的生长工艺320mbar,4600W,850℃进行生长,实现了高品质和高速率协同的CVD单晶金刚石生长。对Mosaic拼接法进行了实验研究和探索,以实现CVD单晶金刚石面积的突破性增大。对双籽晶拼接中的界面处进行了研究,探究了影响界面处生长质量的籽晶因素。进而对生长后样品的界面处进行了晶体质量,缺陷和掺杂浓度等表征。同时,对双籽晶拼接生长进行了激光切割和抛光,并对横截面的拼接界面处进行了Raman mapping测试,发现随着CVD生长层的增厚,界面处由于存在应力和晶格错配以及一定的缺陷,导致界面应力区的宽度逐渐增加,Raman半高宽也随之逐渐增大,表明应力区的晶体质量有所降低,缺陷密度增加。且最大应力点始终与Raman峰半高宽最大值位置相对应,表明了拼接界面的所在位置。此外,对三籽晶和四籽晶的拼接生长进行了研究,探究拼接方式对界面处形貌的影响和N原子掺杂浓度信息,获得了大尺寸的单晶金刚石。
[Abstract]:Diamond has extremely high hardness, thermal conductivity, excellent optical and electrical properties, The growth and size increase of CVD for single crystal diamond is seriously limited by the size of seed substrate. In this paper, the growth of high quality and large size monocrystalline diamond by Mosaic splicing method is analyzed and experimentally studied in detail. By placing several HPHT seeds together and growing on them at the same time, the CVD growth layer is connected as a whole. Breaking through the problem of monolithic seed growth limiting the size of epitaxial growth layer due to the formation of polycrystals at the boundary, In order to obtain large size CVD monocrystalline diamond layer, the chemical nature of monocrystalline diamond growth and the initial growth pattern during the deposition process were summarized, analyzed and experimentally demonstrated. The chemical nature and growth history of CVD growth were studied. Several important components in the process, such as atom [H] Ch * and the degree of reaction equation, affect the reaction rate. The initial growth mode of homogeneous epitaxy is discussed by experiment and theoretical analysis. The initial growth mode of homoepitaxy is island growth to stratified step flow mode. The attachment is embedded in the CVD growth layer as it grows. The deep dislocations or inclusions exposed by the large etching pits also have high defect density due to lattice mismatch and dislocation propagation. This will seriously affect the quality of CVD epitaxial growth layer. The growth of single crystal diamond is analyzed systematically. The effects of various factors on the growth quality and growth rate were studied experimentally. The mass and defect density of seed crystal were characterized by PL spectrum X-ray rocking curve and plasma etching treatment. In addition, whether the side side of the seed is polished, temperature, microwave power, The concentration of carbon source and impurity elements have great influence on the growth rate and quality of seed crystal. The side-polished seed crystal can delay the appearance of polycrystalline phase on the side side, and then increase the possibility of increasing the area of epitaxial growth layer of CVD. The higher the temperature, the faster the growth rate and the lower the mass of CVD layer, the higher the concentration of carbon source. The growth of CVD single crystal diamond with high quality and high speed has been realized. The Mosaic splicing method has been studied experimentally and explored in order to realize the breakthrough increase of the area of CVD single crystal diamond. The interface of double seed crystal splicing has been studied. The factors affecting the growth quality at the interface were investigated. The crystal quality, defects and doping concentration were characterized at the interface of the grown samples. At the same time, the laser cutting and polishing of the double seed splicing growth were carried out. The results of Raman mapping test show that with the thickening of the CVD growth layer, there are some defects in the interface due to the stress and lattice mismatch. As a result, the width of the interfacial stress region increases gradually and the width of the Raman half maximum increases, which indicates that the crystal quality of the stress region decreases and the defect density increases, and the maximum stress point always corresponds to the maximum position of the half width of the Raman peak. In addition, the splicing growth of tri-seed and tetra-seed was studied. The influence of splicing mode on the morphology of interface and the information of N atom doping concentration were investigated, and large size single crystal diamond was obtained.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TQ163

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