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近几年,国外发展了一种热壁低压化学蒸汽淀积(简称LPCVD)薄膜技术。由于在低压下,气体分子的输运过程加快,炉内硅片可以高密度直立装片,每炉装片量可达100～200片。提高了劳动效率,降低了成本,薄膜均匀性也很好(厚度偏差<±5％)。但该工艺有一个较为严重的缺点,所用的石英管内壁会出现裂纹,甚至断裂,这种现象是由于淀积在管内壁的硅和石英本身两者膨胀系数相差太大而引起的。这一工艺中所用的石英支架,也有类似的断裂现象。在石英管有裂纹漏气而未断裂时,对生产危害最大,往往会使得成批产品报废或质量下降。 为了解决石英管的破裂问题,美国应用材料公司制造的LPCVD多晶硅专用设备中,采用HCl气体在炉内及时腐蚀去除管壁上的多晶硅层,以防止石英管的破裂。而日本国际电气
In recent years, a thermal wall low pressure chemical vapor deposition (LPCVD) thin film technology has been developed abroad. Due to the acceleration of transport of gas molecules under low pressure, the silicon wafer in the furnace can be mounted vertically in high density, with the loading capacity of up to 100-200 pieces per furnace. Improve labor efficiency, reduce costs, film uniformity is also good (thickness deviation of <± 5%). However, there is a serious disadvantage of the process. The inner wall of the quartz tube used therein may be cracked or even cracked. This phenomenon is caused by the large difference in the expansion coefficients between the silicon and the quartz deposited on the inner wall of the tube. Quartz stents used in this process also have similar fracture phenomena. Cracked leaks in the quartz tube without rupture, the most harmful to the production, often make the bulk product scrapped or the quality of decline. In order to solve the rupture of quartz tube, LPCVD polysilicon special equipment manufactured by Applied Materials Company uses HCl gas to promptly remove the polysilicon layer on the tube wall in the furnace to prevent the rupture of the quartz tube. The Japan International Electric