To accurately find a film thickness of an electron injection layer having, for example, 10 nm or less of extremely thin film thickness.
The electron injection layer 52 is formed by vapor-depositing an electron injection material such as Ca on an organic EL layer formed in a recess 62, and the electron injection material is vapor-deposited on two conductive parts 60 formed in a peripheral area 120 on an element substrate 1b. A vapor deposition film 53 is formed thereby to connect electrically the two conductive parts 60 each other. A measuring terminal 61 connected electrically to a measuring instrument 62 is brought into contact respectively with the two conductive parts 60 to measure an electric resistance value of the vapor deposition film 53 i.e. a film resistance of the vapor deposition film 53 along a substrate face of the element substrate 1b, using a biterminal method. A correlation between the electric resistance value of the vapor deposition film 53 and the film thickness of the vapor deposition film 53 is found preliminarily to calculate the film thickness of the vapor deposition film 53 with one-to-one correspondence, by measuring the electric resistance value of the vapor deposition film 53. The film thickness of the vapor deposition film 53 is brought into the film thickness of the electron injection layer 52 to find indirectly and accurately the film thickness of the electron injection layer 52.
Fujitsuna Hideyoshi
Osamu Suzawa