PURPOSE: To completely avoid the charge up of an upper silicon sheet further providing the mask substrate in high productivity having an affixing structure in relation to the improvement of the title charged beam exposure transmission mask substrate having the affixing structure of upper and lower silicon sheets.

CONSTITUTION: The title mask substrate is composed of an intermediate layer comprising silicon oxide film layer regions 2 passing through both surfaces of the layers and a conductive layer region 5 as well as two silicon sheets 1, 6 affixed to each other through the intermediary of said intermediate layer while in one silicon sheet 1, the parts adjacent to the silicon oxide film layer region 2 are removed. On the other hand, the manufacturing step of mask substrate is composed of the following three steps i.e., the first step wherein the silicon oxide films 2 formed in the lower silicon sheet 1 are removed by pattern etching step, the second step wherein the conductive film 5 is buried in the removed oxide film regions and the third step wherein the upper silicon sheet 6 and the lower silicon sheet 1 are affixed to each other through the intermediary of the oxide films 2 and the conductive film 5.