Hoerni left Amelco to work directly for Union Carbide as a consulting engineer and asked Hall to join him there. From 1962 to 1967 Hall was Union Carbide’s director of IC development. Hall’s first patent, filed in 1966 while working for Jean Hoerni at Union Carbide as the company’s Director of Integrated Circuit Development, involved the invention of a sputtering process to create gold contacts in a molybdenum-based semiconductor. Over the course of his career, Hall received at least 21 patents covering advanced semiconductor processes and designs. Hall was a protégé of Dr. Jean Hoerni, one of the “Traitorous Eight” who left Shockley Semiconductor Laboratory and co-founded rival Fairchild Semiconductor. In turn, many of Hall's former employees such as David Fullagar went on to become major Silicon Valley contributors.