US 12,406,890 B2
Method for measuring overlay shift of bonded wafers
Ming-Sung Kuo, Hsinchu (TW); Hsun-Kuo Hsiao, Hsinchu (TW); Chung-Cheng Chen, Miaoli County (TW); and Po-Wei Chen, Hsinchu (TW)
Assigned to Taiwan Semiconductor Manufacturing Company, Ltd., Hsinchu (TW)
Filed by Taiwan Semiconductor Manufacturing Company, Ltd., Hsinchu (TW)
Filed on Jun. 28, 2024, as Appl. No. 18/757,511.
Application 18/757,511 is a continuation of application No. 17/395,426, filed on Aug. 5, 2021, granted, now 12,057,353.
Prior Publication US 2024/0347396 A1, Oct. 17, 2024
This patent is subject to a terminal disclaimer.
Int. Cl. H01L 21/66 (2006.01)
CPC H01L 22/12 (2013.01) [H01L 22/26 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method, comprising:
bonding a top wafer having a top wafer pattern to a bottom wafer having a bottom wafer pattern;
using an optical inspection device for measuring an overlay shift of the top wafer from the bottom wafer along a first axis so that the following measurement conditions are satisfied:

OG Complex Work Unit Math
wherein,
Wx1 is a width of a first portion of the top wafer pattern measured along the first axis;
Wx2 is a width of a first part of the bottom wafer pattern measured along the first axis;
Dx is a target distance between the first portion and the first part when no shifting of the top wafer and the bottom wafer along the first axis exists;
Tx represents a searching distance for finding an end-point of the first portion of the top wafer pattern or an end-point of the first part of the bottom wafer pattern using the optical inspection device; and
Sx represents an actual shifting amount of the first portion of the top wafer pattern along the first axis relative to the target distance Dx.