US-12628621-B2 - Semiconductor structure and method of overlay measurement of semiconductor structure

US12628621B2US 12628621 B2US12628621 B2US 12628621B2US-12628621-B2

Abstract

A method of overlay measurement of a semiconductor structure includes a number of operations. A semiconductor structure with a pre-layer and a current layer over the pre-layer is provided, wherein the pre-layer includes a first overlay mark with a first grating group and a second grating group, and the current layer includes a second overlay mark. A semiconductor process is performed on the semiconductor structure. A detection beam is irradiated to the first overlay mark. A first intensity distribution of the first grating group and a second intensity distribution of the second grating group with respect to the reference point of the first overlay mark are received.

Inventors

Chan Hen YANG
Yun Chen WU

Assignees

NANYA TECHNOLOGY CORPORATION

Dates

Publication Date: 20260512
Application Date: 20230206

Claims (9)

1 . A method of overlay measurement of a semiconductor structure, comprising: providing a semiconductor structure with a pre-layer and a current layer over the pre-layer, wherein the pre-layer comprises a first overlay mark with a first grating group and a second grating group, and the current layer comprises a second overlay mark; performing a semiconductor process on the semiconductor structure; setting a reference point of the second overlay mark after the semiconductor process is performed; irradiating a detection beam to the first overlay mark; receiving a first intensity distribution of the first grating group and a second intensity distribution of the second grating group with respect to the reference point of the first overlay mark; obtaining a first offset of the first grating group with respect to the reference point based on the first intensity distribution; obtaining a second offset of the second grating group with respect to the reference point based on the second intensity distribution; and determining a position difference between the first overlay mark and the second overlay mark based on the first offset and the second offset.
2 . The method of claim 1 , wherein obtaining the first offset comprises selecting a first center region of the first intensity distribution and determining a first center point of the first center region based on an average intensity near the first center point, and the first offset is a distance between the reference point and the first center point.
3 . The method of claim 2 , wherein the first center point is a position corresponding to an extreme point of the first intensity distribution.
4 . The method of claim 1 , wherein each of the first grating group and the second grating group comprises a plurality of gratings extended in a first direction and arranged in a second direction perpendicular to the first direction, and a number of the gratings of the first grating group is different from a number of the gratings of the second grating group.
5 . The method of claim 4 , wherein the first grating group and the second grating group are arranged in the first direction, a first density of the gratings of the first grating group is less than a second density of the gratings of the second grating group in the second direction, and a first average intensity of the first intensity distribution is greater than a second average intensity of the second intensity distribution.
6 . The method of claim 1 , wherein the first overlay mark further comprises a third grating group, the method further comprises: receiving a third intensity distribution of the third grating group with respect to the reference point.
7 . The method of claim 6 , wherein each of the first grating group, the second grating group and the third grating group comprises a plurality of gratings extended in a first direction and arranged in a second direction perpendicular to the first direction, and a number of the gratings of the first grating group, a number of the gratings of the second grating group and a number of the gratings of the third grating group are different from each other.
8 . The method of claim 7 , wherein a first density of the gratings of the first grating group is less than a second density of the gratings of the second grating group in the second direction, the second density is less than a third density of the gratings of the third grating group, and the first grating group, the second grating group and the third grating group are arranged along the first direction in order.
9 . The method of claim 1 , wherein performing the semiconductor process on the semiconductor structure comprises performing a planarization process, a polishing process or an etching process on the pre-layer or the current layer.

Description

BACKGROUND Field of Invention The present disclosure relates to a semiconductor structure and a method of overlay measurement of semiconductor structure. Description of Related Art An important issue to confirm the overlay alignment relationship between semiconductor layers forming a structure. For example, two overlay marks can be formed on two different semiconductor layers, and an alignment between the two semiconductor layers can be confirmed through an alignment relationship of the two overlay marks. However, once any of the two overlay marks is damaged, the overlay alignment measurement for the two semiconductor layers would fail, and it is difficult to determine whether any of the two overlay marks is damaged after the semiconductor structure is formed. SUMMARY An aspect of the present disclosure is related to a method of overlay measurement of a semiconductor structure. According to one or more embodiments of the present disclosure, a method of overlay measurement of a semiconductor structure includes a number of operations. A semiconductor structure with a pre-layer and a current layer over the pre-layer is provided, wherein the pre-layer includes a first overlay mark with a first grating group and a second grating group, and the current layer includes a second overlay mark. A semiconductor process is performed on the semiconductor structure. A detection beam is irradiated to the first overlay mark. A first intensity distribution of the first grating group and a second intensity distribution of the second grating group with respect to the reference point of the first overlay mark are received. In one or more embodiments of the present disclosure, the method of overlay measurement of a semiconductor structure includes a number of operations. A first offset of the first grating group with respect to the reference point is obtained based on the first intensity distribution. A second offset of the second grating group with respect to the reference point is obtained based on the second intensity distribution. A position difference between the first overlay mark and the second overlay mark is determined based on the first offset and the second offset. In some embodiments, obtaining the first offset includes selecting a first center region of the first intensity distribution and determining a first center point of the first center region based on an average intensity near the first center point. The first offset is a distance between the reference point and the first center point. In some embodiments of the present disclosure, the first center point is a position corresponding to an extreme point of the first intensity distribution. In one or more embodiments of the present disclosure, each of the first grating group and the second grating group includes a plurality of gratings extended in a first direction and arranged in a second direction perpendicular to the first direction. A number of the gratings of the first grating group is different from a number of the gratings of the second grating group. In some embodiments, the first grating group and the second grating group are arranged in the first direction. A first density of the gratings of the first grating group is less than a second density of the gratings of the second grating group in the second direction. A first average intensity of the first intensity distribution is greater than a second average intensity of the second intensity distribution. In one or more embodiments of the present disclosure, the first overlay mark further includes a third grating group. The method of overlay measurement of a semiconductor structure includes following operation. A third intensity distribution of the third grating group with respect to the reference point is received. In some embodiments, each of the first grating group, the second grating group and the third grating group includes a plurality of gratings extended in a first direction and arranged in a second direction perpendicular to the first direction. A number of the gratings of the first grating group, a number of the gratings of the second grating group and a number of the gratings of the third grating group are different from each other. In some embodiments, a first density of the gratings of the first grating group is less than a second density of the gratings of the second grating group in the second direction. The second density is less than a third density of the gratings of the third grating group. The first grating group, the second grating group and the third grating group are arranged along the first direction in order. In one or more embodiments of the present disclosure, performing the semiconductor process on the semiconductor structure includes performing a planarization process, a polishing process or an etching process on the pre-layer or the current layer. An aspect of the present disclosure is related to a semiconductor structure. According to one or more embodiments of the present di