High Speed Infrared Probe for Doped Layers Characterization: Experiment and Ray Tracing Study

Measurement of infrared (IR) reflectance and transmittance are proven methods for rapid inline process monitoring of doped layers formation. This work presents two experiments where multiple layer properties can be simultaneously determined using appropriate IR measurements: 1) separation of the sheet resistances of front and rear diffused layers, derived from IR front incident reflectance and transmittance data, and; 2) resolution of the sheet conductance and thickness of front and rear ITO layers, derived from IR front incident reflectance, transmittance and rear incident reflectance data. Both of these scenarios are further articulated using ray tracing modelling combined with sensitivity analysis. Finally, this type of simulation is also used to predict the ability of the IR interactions to resolve phosphorus diffused layer surface concentration independently of the sheet resistance. The simulation shows that reliable resolution is achievable, as long as the surface active dopant concentration exceeds 2 x10
¹⁹
cm
^-3
.