Specific Process Knowledge/Thin film deposition/Deposition of Gold: Difference between revisions

The adhesion of gold on Silicon or Silicon with native oxide is not very good. The Si substrate is often deposited an adhesion layer before the gold deposition. A few nm of Chromium or Titanium works well and they react with the Oxygen of Silicon oxide and present a metallic bond with gold. 5 nm to 10 nm thick of Cr or Ti is commonly used and it is important to deposit Cr or Ti and then immediately Au. If the vacuum chamber is opened in between, the surface of Cr or Ti will get oxidized and that will give a poor adhesion. If a gold layer needs to be deposited directly on Silicon, then native oxide has to be removed by deep in diluted HF and immediately load the evaporation chamber. And after the deposition, the wafer has to be heated op to get some Au-Si diffusion which improves the adhesion.