iron oxide films for &# 34 ; see - through &# 34 ; photomasks are deposited upon heated substrates by chemical vapor deposition from iron pentacarbonyl in the presence of oxygen . the solubility of the iron oxide film is found to be higher , the lower the temperature of the substrate during deposition . at temperatures below 160 degrees c ., films are obtained which can be patterned at reasonable rates by photolithographic procedures using conventional mild etchants .