| 摘要 |
Controlling compound semiconductor growth in situ using reflectometry measurements and a multi-layer stack model. The method comprises: i. illuminating a semiconductor wafer 40 having one or more layers of different semiconductor materials in a state of growth within a reaction chamber 42 with a source of laser light 44, said growth having at least one controllable process variable such as temperature, pressure or flow rate, ii. detecting light 48 normally reflected from the surface of the semiconductor wafer, and from each underlying interface to generate a plurality of sets of reflectance data over discrete time periods, and iii. using the reflectance data sets in a matching procedure to determine one or more characteristics of the illuminated wafer 40. The matching procedure involves the processing of data in matrix form, wherein the matrices are of the order of the number of layers in the compound semiconductor wafer. A priori data (such as layer refractive indices or desired thicknesses) provide a measure of variation which is used via a feedback control signal to control the process variable. The wafer may rotate at a predetermined frequency and the data collected at a frequency dependent on the rotation frequency. |
