Guidance on substrate resistivity and radial uniformity specifications. - Specify substrates with a tight radial resistivity uniformity, not just a nominal resistivity value. - Choose higher quality crystal grown with good thermal and rotational control; for the most demanding cases, magnetically controlled Czochralski (MCZ) material has reduced striations. - For applications that need precise oxide thickness, select prime, tightly specified substrates rather than test or low-grade material. - Remember that the cause is in the wafer, not the furnace, so adjusting the oxidation recipe will not remove striations that are built into the crystal. - Work with your foundry to set an incoming material specification that matches the device requirement. Rogue Valley Microdevices provides thermal oxidation along with wafer services and substrate sourcing. We can help determine whether a ring pattern reflects the incoming substrate or the process. For applications that depend on oxide thickness uniformity or substrate resistivity uniformity, the team can advise on substrate selection and specifications so the starting material is better aligned with the performance needs of your device. - Guidance on substrate resistivity and radial uniformity specifications.
