Method for forming semiconductor device

A method for forming a semiconductor device, comprising:

• forming a seal ring structure and a first alignment mark at least partially overlapping the seal ring structure in a top die;
• forming a second alignment mark in a bottom wafer;
• attaching the top die to the bottom wafer;
• and
• aligning the top die with the bottom wafer using the first alignment mark and the second alignment mark,
• wherein in a top view, the first alignment mark and the second alignment mark both comprise four patterns.

A method for forming a semiconductor device, comprising:

• forming a first alignment mark in a top die;
• forming a second alignment mark and a third alignment mark in a bottom wafer;
• attaching the top die to the bottom wafer;
• and
• aligning the top die with the bottom wafer using the first alignment mark, the second alignment mark, and the third alignment mark by calculating a first-direction deviation and a second-direction deviation,
• wherein the first-direction deviation is calculated based on a positional relationship between the first alignment mark and the second alignment mark, and the second-direction deviation is calculated based on a positional relationship between the first alignment mark and the third alignment mark.