Specific Process Knowledge/Thin film deposition/Deposition of Gold: Difference between revisions
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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. You can also use polymer or organosilane adhesion layers as exemplified by the work in the next section. | 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. You can also use polymer or organosilane adhesion layers as exemplified by the work in the next section. | ||
For Cr and Ti adhesion layers, a 5 nm to 10 nm thick layer 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 | For Cr and Ti adhesion layers, a 5 nm to 10 nm thick layer 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 up to get some Au-Si diffusion which improves the adhesion. | ||
*[[/Adhesion layers|Read more about Ti and Cr adhesion layers]]. | *[[/Adhesion layers|Read more about Ti and Cr adhesion layers]]. | ||