SPECIFY THE GRID

Title of keyword block used to specify the number of grid points used in the finite difference scheme. The axial grid is defined by separating the reactor into three sections defined as the entrance region, wafer load, and exit region as shown in Figure 3.1: Schematic of the LPCVD reactor and some of the input parameters . The keywords in the SPECIFY THE GRID block control the number of grid points used in each region as well as the number of radial grid points distributed across the wafers. A uniform grid spacing is used for each region and across wafers. None of the keywords in the block have defaults; all are required inputs. Requires END statement to close keyword block.

NUMBER OF WAFERS =

Provides the number of wafers in the reactor, which is used as the number of axial grid points in the wafer load region. The axial spacing between wafers is determined by dividing the difference between the location of the first and last wafers in the load by the number of wafers minus one. The positions of the first and last wafers are specified as inputs in the SPECIFY THE REACTOR keyword block. Part of the SPECIFY THE GRID keyword block.

Example:NUMBER OF WAFERS = 61

Units:None

NUMBER OF RADIAL POINTS ACROSS WAFERS =

Provides the number of radial grid points used across each wafer. In addition to radial grid points across the wafers, at each wafer’s axial location a radial grid point is placed within each of the quartz walls, the heater elements, and the thermal insulation to determine distinct but radially uniform temperatures for each of these components. Hence, the model gives the axial variation of separate temperatures for the quartz walls, heaters, and external insulation. Part of the SPECIFY THE GRID keyword block.

Example:NUMBER OF RADIAL POINTS ACROSS WAFERS = 3

Units: None, but must be given as an integer.

NUMBER OF POINTS IN THE ENTRANCE REGION =

Provides the number of axial grid points used in the entrance region. Part of the SPECIFY THE GRID keyword block.

Example: NUMBER OF POINTS IN THE ENTRANCE REGION = 5

Units: None, but must be given as an integer

NUMBER OF POINTS IN THE EXIT REGION =

Provides the number of axial grid points used in the exit region. Part of the SPECIFY THE GRID keyword block.

Example: NUMBER OF POINTS IN THE EXIT REGION = 5

Units: None, but must be given as an integer.