碳化硅基外延金刚石薄膜及其性质研究
发布时间：2019-04-22 18:50
【摘要】：金刚石薄膜的生长分为形核和生长两个阶段,衬底温度、沉积压强、碳氢气体的流量以及衬底偏压等工艺参数直接影响着金刚石薄膜的形核阶段,从而对金刚石薄膜的表面结构以及晶体晶向产生影响,因此将金刚石薄膜生长的工艺参数作为薄膜制备的重要研究对象。本文采用热丝化学气相沉积(HFCVD)的方法在单面为碳面的碳化硅衬底成功制备了金刚石薄膜。研究了各种工艺参数对金刚石薄膜的影响,讨论了它们作用的机理,优化了工艺参数,得出结论如下:1.衬底的预处理能够极大的改善碳化硅衬底表面的微结构,从而对金刚石薄膜的连续性生长产生影响。在机械研磨以及化学清洗的预处理方法下,碳化硅表面生长的金刚石颗粒少、薄膜连续性差且有薄膜脱落的现象;在超声清洗预处理方法下,金刚石颗粒尺寸大小不一,薄膜均匀性较差;在研磨加超声清洗的预处理方法下,金刚石薄膜致密度高、薄膜连续性最好。2.氢气流量的大小与金刚石薄膜的表面形貌和晶体晶向有着密切的关系。当氢气流量较低的时候150 mL/min,氢气的不充足会造成碳氢活性基团不充足,造成生长金刚石薄膜反应过慢,从而导致金刚石薄膜难以形成。当氢气的流量较高的时候200 mL/min,较低的氢气流量有利于(111)面的生长。除此之外,由于氢气流量较低,氢气对石墨的刻蚀不足,从而导致样品出现石墨,造成金刚石薄膜不纯。在氢气流量为250 mL/min情况下,氢气充足有利于(100)面的生长。3.衬底温度以及沉积气压影响金刚石薄膜的形核速率。随着温度(或沉积气压)的提高,金刚石薄膜的形成速率是提升的。衬底温度过高或沉积气压过大都会造成金刚石二次形核出现,破坏金刚石薄膜表面完整性;衬底温度过低或沉积气压过小,碳氢基团反应速率慢,金刚石薄膜生长速率慢。4.衬底偏压提高碳氢离子活性,加快碳氢基团活性反应速率。气压影响真空室内活性基团的碰撞速率,从而对金刚石薄膜生长速率产生影响。随着衬底偏压的增大,金刚石薄膜生长速率更快。但是过压对金刚石薄膜设备负荷较大,并且对金刚石薄膜的生长速率提升不明显,因此将700 V作为金刚石薄膜生长的偏压。
[Abstract]:The growth of diamond films is divided into two stages: nucleation and growth. The process parameters, such as substrate temperature, deposition pressure, flow rate of hydrocarbon gas and substrate bias, directly affect the nucleation stage of diamond films. As a result, the surface structure and crystal orientation of diamond film are affected. Therefore, the technological parameters of diamond film growth are regarded as an important research object in the preparation of diamond thin film. Diamond thin films were successfully deposited on sic substrate with carbon surface by hot filament chemical vapor deposition (HFCVD). The effects of various process parameters on diamond films were studied, the mechanism of their action was discussed, and the process parameters were optimized. The conclusions are as follows: 1. The pretreatment of the substrate can greatly improve the microstructure of the silicon carbide substrate surface, thus affecting the continuous growth of diamond films. Under the pre-treatment of mechanical grinding and chemical cleaning, the diamond particles grown on the surface of silicon carbide are few, the continuity of the film is poor, and there is a phenomenon of film shedding. Under the pretreatment method of ultrasonic cleaning, the size of diamond particles is different and the film uniformity is poor, and under the pretreatment method of grinding and ultrasonic cleaning, the density of diamond film is high and the continuity of the film is the best. The hydrogen flow rate is closely related to the surface morphology and crystal orientation of diamond films. When the flow rate of hydrogen is low, the insufficient hydrogen of 150 mL/min, will lead to insufficient active groups of carbon and hydrogen, which will cause the reaction of diamond film to be too slow, so that it is difficult to form diamond film. When the flow rate of hydrogen is higher, the lower flow rate of hydrogen at 200 mL/min, is beneficial to the growth of (111) surface. In addition, due to the low flow rate of hydrogen, the etching of graphite by hydrogen is insufficient, which leads to the appearance of graphite and impure diamond film. At a hydrogen flow rate of 250 mL/min, sufficient hydrogen is conducive to the growth of (100) surfaces. 3. The nucleation rate of diamond films is influenced by substrate temperature and deposition pressure. With the increase of temperature (or deposition pressure), the formation rate of diamond films is increased. If the substrate temperature is too high or the deposition pressure is too high, the secondary nucleation of diamond will occur, and the surface integrity of diamond film will be destroyed, the substrate temperature is too low or the deposition pressure is too small, the reaction rate of carbon and hydrogen groups is slow, and the growth rate of diamond film is slow. Substrate bias increases the activity of hydrocarbon ions and accelerates the reaction rate of hydrocarbon groups. Air pressure affects the collision rate of active groups in vacuum chamber, thus affects the growth rate of diamond films. With the increase of substrate bias, the growth rate of diamond films is faster. However, the overvoltage has a large load on the diamond film equipment, and the growth rate of the diamond film is not significantly increased, so 700 V is used as the bias voltage for the growth of diamond film.
【学位授予单位】：河北工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.2;TQ163
本文编号：2463104
[Abstract]:The growth of diamond films is divided into two stages: nucleation and growth. The process parameters, such as substrate temperature, deposition pressure, flow rate of hydrocarbon gas and substrate bias, directly affect the nucleation stage of diamond films. As a result, the surface structure and crystal orientation of diamond film are affected. Therefore, the technological parameters of diamond film growth are regarded as an important research object in the preparation of diamond thin film. Diamond thin films were successfully deposited on sic substrate with carbon surface by hot filament chemical vapor deposition (HFCVD). The effects of various process parameters on diamond films were studied, the mechanism of their action was discussed, and the process parameters were optimized. The conclusions are as follows: 1. The pretreatment of the substrate can greatly improve the microstructure of the silicon carbide substrate surface, thus affecting the continuous growth of diamond films. Under the pre-treatment of mechanical grinding and chemical cleaning, the diamond particles grown on the surface of silicon carbide are few, the continuity of the film is poor, and there is a phenomenon of film shedding. Under the pretreatment method of ultrasonic cleaning, the size of diamond particles is different and the film uniformity is poor, and under the pretreatment method of grinding and ultrasonic cleaning, the density of diamond film is high and the continuity of the film is the best. The hydrogen flow rate is closely related to the surface morphology and crystal orientation of diamond films. When the flow rate of hydrogen is low, the insufficient hydrogen of 150 mL/min, will lead to insufficient active groups of carbon and hydrogen, which will cause the reaction of diamond film to be too slow, so that it is difficult to form diamond film. When the flow rate of hydrogen is higher, the lower flow rate of hydrogen at 200 mL/min, is beneficial to the growth of (111) surface. In addition, due to the low flow rate of hydrogen, the etching of graphite by hydrogen is insufficient, which leads to the appearance of graphite and impure diamond film. At a hydrogen flow rate of 250 mL/min, sufficient hydrogen is conducive to the growth of (100) surfaces. 3. The nucleation rate of diamond films is influenced by substrate temperature and deposition pressure. With the increase of temperature (or deposition pressure), the formation rate of diamond films is increased. If the substrate temperature is too high or the deposition pressure is too high, the secondary nucleation of diamond will occur, and the surface integrity of diamond film will be destroyed, the substrate temperature is too low or the deposition pressure is too small, the reaction rate of carbon and hydrogen groups is slow, and the growth rate of diamond film is slow. Substrate bias increases the activity of hydrocarbon ions and accelerates the reaction rate of hydrocarbon groups. Air pressure affects the collision rate of active groups in vacuum chamber, thus affects the growth rate of diamond films. With the increase of substrate bias, the growth rate of diamond films is faster. However, the overvoltage has a large load on the diamond film equipment, and the growth rate of the diamond film is not significantly increased, so 700 V is used as the bias voltage for the growth of diamond film.
【学位授予单位】：河北工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.2;TQ163
【参考文献】
相关期刊论文 前1条
1 左伟;沈彬;孙方宏;陈明;;热丝化学气相法生长单晶金刚石颗粒的衬底温度场仿真及实验研究(英文)[J];人工晶体学报;2007年05期
，本文编号：2463104
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