> For the complete documentation index, see [llms.txt](https://docs.hackerfabiitb.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.hackerfabiitb.org/fab-basics/liftoff-and-undercut-in-deposition.md). # Liftoff and Undercut in Deposition TODO Liftoff is the simplest way to create a pattern using deposition and lithography (sputtered metal in our case). Patterned and developed photoresist blocks certain areas of the substrate and leaves the rest exposed to deposition. However, sputtering is conformal: it coats all surfaces with a non-zero film thickness, independent of deposition. Thus there would be no way to develop the photoresist as the metal deposition blocks the developer. Undercut means creating a laterally larger hole in liftoff-resist underneath the photoresist layer. If the LOR layer is thicker than the deposition, it leaves place for the developer to attack the resists. The developer removes the resists and the metal layer above lifts and floats away, hence the term **liftoff.** --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation by asking a question. Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters: ``` GET https://docs.hackerfabiitb.org/fab-basics/liftoff-and-undercut-in-deposition.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.