Device models built from the device targets and simulation before fitted silicon data exists, so the alpha kit can be used to start symbols, PCells, libraries, IP and flow work.
Model Work product in the Process design kit (PDK) development lifecycle
It allows layout, library and IP development to start before silicon is available, so the beta kit arrives with usable content. Early teams otherwise wait for silicon or, worse, use informal models whose basis nobody knows.
The full lifecycle detail, with its charts, flows, tables and every section, is for registered members. Registration is free and takes a minute. You come back to this page afterwards.