The harm of the shape of the graphite boat to the surface layer of the surface layer will use the new graphite boat and the use of the old graphite boat for more than three years to saturate the coating on the surface layer of the PECVD surface. The flat surface of the new graphite boat is good, and the graphite boat has the same conductivity. The plastic membrane molecular formula can be uniformly accumulated on the surface of the single crystal silicon wafer, and the uniformity between the pieces is higher.

After the new graphite boat is saturated, there are still some plasma accumulated on the graphite boat when the accumulation is accumulated. When the number of running times is less than thirty times, as the number of running times increases, the plasma accumulated on the graphite boat decreases. Essence After the number of running times exceeds thirty times, as the number of uses increases, the inner wall of the graphite tape and the single crystal silicon tablets touch the plastic film on the edge of the edge. The section of the level of the level of the edge of the tablet has caused several reductions between the tablets several times.