The University of Zurich (UZH) offers international PhD candidates the following possibilities:

Doctoral Study at UZH
Academic Guests
Joint-University PhD
Information on Exchange Programs and Financial Aid

Doctoral Study at UZH

Students interested in doctoral study at UZH should ask for information about the PhD in general and the various ways of earning a PhD at the Admissions Office and the Graduate Campus.

Academic Guests

Researchers who work at UZH, but are neither registered as students nor employed by the University are academic guests. The University offers various services to its academic guests. more (in German)

Joint-University PhD

The Cotutelle de Thèse allows PhD candidates to be registered simultaneously at two universities as PhD candidates and to receive supervision at both institutions. more

Information on Exchange Programs and Financial Aid

Please ask your home university whether it has an exchange agreement with the University of Zurich. You can find more information about Swiss government scholarships (Bundesstipendium) at The Swiss Federal Commission for Scholarships for Foreign Students (CFBE)  

Information about other sources of financial aid is available at Euraxess Switzerland.
Finally, information about entering Switzerland and visa requirements can be found here (in German).