Numerical analysis of the use of multiple inlet plates to improve the thickness uniformity of silicon epitaxial layers during atmospheric pressure chemical vapor deposition

• Design a multi-inlet plate structure for an APCVD reactor for growing Si epi-layers on silicon wafers with a radius of 150 mm. • Find the ideal deposition rate distribution to obtain perfect epi-layer flatness on the Si wafer after wafer rotation. • Numerical simulation for optimization of plate position and gas velocity to obtain high Si epi-layer flatness. • The degree of flatness is improved by increasing the number of inlet plates. • The present method may also be applied in horizontal MOCVD or other types of horizontal CVD reactors. The further reduction of semiconductor nanometer line width has led to increasingly higher silicon epitaxial film surface flatness requirement. This study conducts a series of numerical simulations to examine the use of multiple inlet plates in an atmospheric pressure chemical vapor deposition (APCVD) chamber to achieve this requirement. The aim is to apply uneven gas velocities at the inlet to achieve better thickness uniformity of the silicon epitaxial layer on the silicon wafer. The results show that in a reactor without an inlet plate, the rapid growth of the trichlorosilane (TCS) reaction boundary layer from the leading edge to the trailing edge of the wafer results in a rapid decay of the deposition rate on the wafer surface. In addition, the rotation of the susceptor causes tilting of the deposition rate pattern on the wafer due to the viscous force. These factors lead to non-uniform deposition thickness on the wafer with wafer rotation. However, the uniformity can be improved by using a multi-inlet reactor design, choosing the appropriate inlet plate positions and selecting the appropriate gas velocity for each inlet. The deposition rate on the wafer surface at the same coordinate position perpendicular to the direction of the flow should be maintained at close to the same value, thereby improving the uniformity of the deposition thickness. Furthermore, using higher gas velocities at the appropriate inlet channels can reduce the degree of nonlinearity in the deposition rate starting from the front edge of the wafer, thereby reducing the film non-uniformity.