| 摘要 |
A circuit board having a plurality of first holes formed in a semiconductor substrate to extend therethrough; insulating layers formed on a back surface of the semiconductor substrate in the plurality of first holes, the insulating layers between the back surface and the first holes being differed in thickness; second holes formed in the insulating layers to communicate with the first holes; and an electro-conductive layer formed inside of the first holes and the second holes to extend through the semiconductor substrate.
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