A semiconductor wafer has an alignment mark for use in aligning the wafer with
exposure equipment during the manufacturing of a semiconductor device. The wafer
is made by forming a chemical mechanical polishing target layer over an alignment
mark layer, chemically-mechanically polishing the target layer to planarize the
same, and prior to forming the chemical mechanical polishing target layer over
the alignment mark layer, forming a dense pattern of lands or trenches in the alignment
layer of dimensions and an inter-spacing preselected to inhibit a dishing phenomenon
from occurring in the target layer as the result of its being chemically-mechanically
polished. The lands or trenches may be disposed in at least a 22 array of
rows and columns. An alignment system for use with this wafer irradiates the mark
with light, and includes an image sensor which produces both a Y-axis alignment
waveform signal from light reflecting from the column(s) of lands or trenches and
an X-axis alignment waveform signal from light reflecting from the row(s) of lands
or trenches. Alternatively, the lands or trenches may be disposed along at least
two lines arranged in the shape of a chevron. In this case, the alignment system
scans an illuminated cross-shaped pattern of a reticle across the alignment mark.
A photo-detection unit collects the reflected light and determines the relative
amounts of light coming from the wafer surface, from one of the lines of lands
or trenches of the alignment mark, and from the other such line of lands or trenches.