Patent ID: 7933015
Filing Date: 2011-04-26
Classification: G03B

Abstract:
1. An exposure method, comprising the steps of: providing a first mask having a first mark pattern, the first mark pattern comprising a first pattern and a second pattern, the first pattern comprising a plurality of rectangular regions arranged in a first direction, a sideline in a second direction being longer than a sideline in the first direction for each rectangular region of the first pattern, the first direction being perpendicular to the second direction, the second pattern being disposed on both sides of the first pattern in the second direction and comprising a plurality of rectangular regions arranged in the second direction, and a sideline in the first direction is longer than a sideline in the second direction for each rectangular region of the second pattern; and forming a first exposed pattern corresponding to the first mark pattern on a wafer via the first mask, and performing a semiconductor process; forming a photoresist layer on the wafer; providing a second mask having a second mark pattern, the second mark pattern comprising a third pattern and a fourth pattern, the third pattern comprising two rectangular regions disposed on locations corresponding to both sides of the first pattern in the first direction, and the fourth pattern comprising two rectangular regions disposed on locations corresponding to both sides of the second pattern in the second direction; determining a position of the second mask relative to the wafer based on the first exposed pattern; forming a second exposed pattern corresponding to the second mark pattern on the photoresist layer via the second mask; and measuring a relative distance between the first exposed pattern and the second exposed pattern for determining an overlay error, wherein the part of the second exposed pattern corresponding to the third pattern is used together with the part of the first exposed pattern corresponding to the first pattern for determining the overlay error in the first direction, and the part of the second exposed pattern corresponding to the fourth pattern is used together with the part of the first exposed pattern corresponding to the second pattern for determining the overlay error in the second direction.