The application discloses a
semiconductor device and a preparation method thereof. The method comprises the following steps: providing an intermediate body, forming a blocking structure above an interlayer
dielectric layer corresponding to a spacing region between adjacent gate stacks,
etching the interlayer
dielectric layer according to the blocking structure to form a contact opening exposing the
gate stack and remove the blocking structure, and filling a material in the contact opening to form a contact unit. The existence of the blocking structure can avoid the connection of two adjacent contact units. Further, the blocking structure is formed by
etching a
mask layer, and the lateral size of the forming process can be flexibly adjusted. The opening size of the upper photoetching layer can be close to the width of the adjacent gate and the spacing region in the direction. Compared with the prior art, the opening size of the photoetching layer can be enlarged, the photoetching difficulty can be reduced, and the contact opening formed above the
gate stack can be accurately positioned by the protection of the blocking structure, so that the load area of the contact unit and the
gate stack is improved.