APERTURE MASK FOR CHARGED BEAM RESTRICTION

• Main Author: NINOMIYA MASAHARU
• Format: Patent
• Language: English
• Published: 08.04.1987
• Subjects: BASIC ELECTRIC ELEMENTS; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; SEMICONDUCTOR DEVICES

PURPOSE:To improve the machining accuracy of an aperture by a method wherein two openings differing in diameter are used for aperture to make the thickness of a mask substrate sufficient thickness for heat conduction, and the depth of the opening is made thin to the degree where required machining accuracy can be obtained so as to prevent the thermal deformation of the aper ture and melting losses with favorable heat conduction. CONSTITUTION:The trancated corn-shaped second opening 12 is formed until it reaches from the back of the mask substrate 10 to the surface. Then, the first opening section 11 whose diameter is smaller than the largest diameter of the second opening section 12 and is larger than the smallest diameter of the second one is formed from the surface of the substrate 10 parallel to it. For forming the first opening section 11, it is convenient to use the substrate with higher machining accuracy such as panching. When the first opening section 11 is formed, the depth h of the first opening section 11 is sufficiently shallower than the thickness of the substrate 10. Moreover, it is possible to change the depth h beforehand in accordance with conditions such as the size of the second opening 12 and its taper angle suitably and also possible to sufficiently make it thin until the required machining accuraly is obtained.