Long-term sputtering method

摘要: There are provided techniques of forming a back reflecting layer with constant characteristics throughout long-term film formation and metal oxide so as to be able maintain current bottom cell thereby keep short-circuit Jsc solar over long period time. A sputtering method is stack film, comprising the step 1 on substrate, 2 bringing surface into contact active oxygen, 3 thereon after 2, wherein in an amount oxygen at first substrate position different from that second position.