Abstract: A semiconductor structure includes a first transistor having a first source/drain (S/D) feature and a first gate; a second transistor having a second S/D feature and a second gate; a multi-layer interconnection disposed over the first and the second transistors; a signal interconnection under the first and the second transistors; and a power rail under the signal interconnection and electrically isolated from the signal interconnection, wherein the signal interconnection electrically connects one of the first S/D feature and the first gate to one of the second S/D feature and the second gate.

Abstract: A pupil tracking method includes: retrieving an external eye image of a subject, wherein the external eye image includes a pupil of the subject; performing an image preprocessing on the external eye image, wherein the image preprocessing includes performing a binary conversion on the external eye image to obtain a binary image; finding out a contour boundary of each feature in the binary image, and finding out a pupil feature based on a variance of a distance from the contour boundary of each feature to a corresponding reference point; fitting the contour boundary of the pupil feature by a boundary fitting method to find a center coordinate of the pupil feature. The abovementioned pupil tracking method can track the pupil of the subject's eyeball without using a stereo camera. An ophthalmology inspection device using the abovementioned pupil tracking method is also disclosed.