【作者】 姜志刚；

【导师】 金曾孙；

【作者基本信息】 吉林大学 ， 凝聚态物理， 2004， 博士

【摘要】 高气压、大电流直流辉光等离子体化学气相沉积方法能够快速沉积高品质金刚石膜。然而，高气压下直流辉光放电和以往的低气压直流辉光放电相比，具有很大的区别。本论文研究了高气压下的直流辉光放电特性，建立了稳定的高气压直流辉光放电的工艺。研究了金刚石膜的生长特性，完善了高导热、高磨耗比的金刚石膜制备工艺和金刚石膜工具的制备技术。论文主要内容如下： 一、放电特性研究： 研究了高气压直流辉光放电的特点，放电区间从低气压的多区域演变成四个主要区域：阴极辉光层、法拉第暗区、辉光等离子体球和阳极辉光层。研究了各放电区域的变化情况：阴极辉光层中通过 热 电 子 发 射 和 γ 过 程 产 生 的 初 级 电 子 在 强 电 场 中 与 气 体 碰 撞 使气体电离，提供大量的电子。随着气压的减小或放电电流的增加阴极辉光层所覆盖阴极的面积增加；法拉第暗区中的电子能量较低，电子和粒子的碰撞以弹性碰撞为主，在向阳极运动的过程中其能量逐渐增加，暗区厚度主要与放电气体的种类有关而与其它放电参数的关系不大；辉光等离子体球是粒子激发和离化的主要区域，其颜色、尺寸和形状依赖于气体的种类、气体的浓度、气体的压强、放电电流、电极尺寸比例、电极间距等。研究了各放电参量的相互关系：放电电压随着气压的增加而增加，也随电极间距的增加而增加。随电流的增加电压存在“饱和”值。电极间的阻值随放电电流的增加而减小，说明随着电流的增加电离出的带电粒子数增加。 研 究 了 影 响 高 气 压 直 流 辉 光 放 电 稳 定 性 的 主 要 因 素 ， 包 括 阴极、电源等，采用电容-电感变换器原理，研制了适合于高气压直流辉光放电的电源，可满足在高气压和大电流条件下稳定的直流辉光放电要求。 二、金刚石膜的生长特性研究 研究了各种沉积条件对金刚石膜的生长速率、表面形貌、晶界、 124<WP=131>品质、均匀性等方面的影响，以及金刚石膜的微裂纹和爆裂等问题。 对金刚石膜生长速率影响较大的工艺参数是气体流量和放电电流。采用甲烷、乙醇、丙酮、甲烷和甲醇的混合气体等研究了金刚石膜的生长速率，金刚石膜的生长速率随碳源气体流量的增加而增加。当碳源气体增加到一定值后，由于金刚石膜表面沉积了较多的石墨相而抑制了金刚石相的沉积，同时，石墨容易被刻蚀，结果使金刚石膜的生长速率降低，导致随着流量的增加生长速率存在极大值。不同的碳源气体生长速率的极大值不同。适当地加入含氧的碳源气体会使生长速率的极大值增加，当反应气氛中的含氧量较高时，金刚石膜的表面由于受到“刻蚀”而使生长速率明显下降。金刚石膜的生长速率随放电电流的增加也存在一个极大值，这个极大值随着含碳气体流量的增加而增加。金刚石膜的生长速率随气体压强的增加而增加，达到极大值后开始降低，其极大值随电流的增加而增加，并向高气压方向推进。基片温度对生长速率有明显影响，1000℃左右有利于金刚石膜的高速生长。 甲烷+乙醇作为碳源气体研究了金刚石膜表面形貌。随着气体流量的增加，逐渐从（111）和（110）混合面到（110）面再到（100）面变化；使用甲烷+甲醇作为碳源气体，金刚石膜主要显露（111）和（110）面，甲醇流量较大时，金刚石膜表面的晶粒棱角明显被“刻蚀”；基片温度较低时，容易出现（100）面，随着温度的升高，逐渐出现（111）面和（110）面，当温度升高到 1100℃时，晶型很不完整。 研究了金刚石膜的晶界。采用氢的微波等离子体刻蚀抛光的金刚石膜截面，清晰地看到了金刚石膜的晶界。低碳源气体流量制备的高品质金刚石膜的晶粒又长又大，二次成核少，晶粒的纵向尺寸大。随着含碳气体流量的增加，出现二次成核，在生长方向上晶界密度明显增加。当含碳气体流量较大时，金刚石膜的质量明显下降，表现为晶粒尺寸小，晶界密度高，晶界被刻蚀的又深又粗，说明晶界中含有较多非金刚石碳相。而且，抛光的晶粒面上有被刻蚀的坑 125<WP=132>点，说明晶粒中也含有缺陷和杂质。 显微拉曼光谱研究结果表明：随着碳源气体流量的增加，金刚石膜的品质下降。随着放电电流的增加，金刚石膜的品质提高。金刚石膜的品质分布一般表现为在径向上逐渐降低，其主要原因是辉光放电在径向上的不均匀性。 金刚石膜厚度的均匀性可分为四种情况，均匀形、凹形、中心平整形和山形。影响金刚石膜厚度均匀性的主要因素是阴极和阳极的尺寸比例、电极间距离、碳源气体流量和放电电流等。电极尺寸比例和电极间距对金刚石膜的厚度分布影响是：大基片远间距容易出现山形，小基片近间距容易使金刚石膜向均匀形转变。随着电流的增加金刚石膜从山形向均匀形转变，随着碳源气体流量的增加金刚石膜从凹形向均匀形转变，即大电流和大流量有利于制备均匀的金刚石膜。气体流量大而放电电流小容易出现山形；气体流量小而放电电流大容易出现均匀形。金刚石膜品质的均匀性表现为在径向上逐渐降低。产生金刚石膜厚度分布差异的原因归结为等离子体球的体积、更多还原

【Abstract】 Diamond films with high quality were synthesized by high gas pressure andhigh electric current DC glow discharge plasma chemical vapor deposition.Diamond films with this method have high growth rate. There are great differencesbetween DC glow discharge at high gas pressure and at low gas pressure. Thecharacteristics of DC glow discharge at high pressure were researched in this thesis.The technics of DC glow discharge at high pressure were optimized. Growthcharacteristics of diamond films and technology of making diamond film tools werestudied. Growth techniques of diamond films with high thermal conductivity andhigh abrasiveness ratio were set up. The followings are the main contents of thisthese: 1. Characteristics of discharge Characteristics of DC glow discharge at high gas pressure were researched.There are four parts in the region of discharge: cathode-glow, Faraday dull area,sphere of plasma and anode-glow. The situation of different discharge parts wasstudied: original electrons come from thermal electron emission and γ process. A lotof electrons appear when original electrons and gas particles collide, and at thesame time gas was ionized. Cathode-glow covers cathode, and its area increaseswith discharge current increasing or gas pressure decreasing. Energy of electrons inthe Faraday dull area is low. Most collisions between electrons and other particlesare elastic, and energy of electrons increases gradually in the course of moving tothe anode. Thickness of Faraday dull area is correlative with the category ofdischarge gas. Sphere of plasma is main region of gas excitation and ionization. Itscolor, size and shape depend on gas category, gas density, gas pressure anddischarge current, size proportion and space between cathode and anode. We haveacquired the relations of various discharge parameters that discharge voltageincreases with gas pressure increasing as well as space between cathode and anode.Voltage saturation appears in the course of electric current increasing. Resistancebetween two electrodes decreases with the current increasing. It indicates that thenumber of the electrification particles increases as current increases. The factors, which can predominate the stability of high gas pressure DC glowdischarge such as cathode and power supply, were investigated in this paper.According to the principle of capacitance- inductance transformer, we developedpower supply which is suited for high pressure DC glow discharge. The powersupply can accord with the requirement of high gas pressure DC glow discharge. 128<WP=135>2. The growth characteristics of thick diamond films Growth rate of diamond films, surface figure, crystal boundary, quality,distribution of thickness, micro-crack and split have been researched in this paper. Discharge current and gas flux have a great impact on growth rate of diamondfilms. Diamond films were deposited by employing methane, acetone, ethanol aswell as the compounds of methane and methanol, and growth rate of diamond filmswas studied. The growth rate of diamond films increases when carbon-source gasincreases. Diamond phase is restrained because of graphite phase being depositedheavily on the diamond surface when carbon-source gas reached to a curtainamount. Meanwhile, graphite is etched rapidly, leading to the decreasing of thegrowth rate of diamond films. And growth rate maximum, which depends on thecategories of carbon-source gas, appears with flow rate increasing. The maximumof growth rate will increase if we have appended oxygenous carbon-source gasproperly, but the growth rate will decrease obviously when oxygen flow rate excess.The maximum of growth rate appears with discharge current increasing as well ascarbonaceous gas flow rate increasing. The growth rate will increase with gaspressure increasing. Substrate temperature influences the growth rate evidently. It isbeneficial to increase the growth rate of di更多还原