Capacitor wafer, preparation method thereof and semiconductor device

The invention discloses a capacitor wafer and a preparation method thereof, and a semiconductor device, and relates to the field of semiconductor technologies, the minimum thickness of a dielectric layer formed for the first time is larger than the lower limit of a target thickness range, and then the thickness of the dielectric layer is optimized to reach a required performance index, namely, the dielectric layer which is slightly thicker is formed firstly, and then the dielectric layer which is slightly thicker is formed; and the thickness uniformity of the dielectric layer is adjusted by thinning the dielectric layer to a target thickness range, so that the target deviation of the thickness of the dielectric layer and the capacitance value of the corresponding capacitor in the chip and between the chips is less than 1%, and the influence of different process chambers, different PM periods and different process adjustment stages on the deposition thickness of the dielectric layer is solved. And after the up