A PCB trace is defined by its thickness, height, width, and dielectric constant (Er) of the PCB material on which the traces are etched.
While designing controlled impedance PCBs, it is essential to take care of these parameters. You can provide the manufacturer with the number of layers, the value of the impedance traces on specific layers (50Ω, 100Ω on layer 3), and materials for PCB designing.
The manufacturer gives you the stackup that mentions the trace widths on each layer, the number of layers, the thickness of each dielectric in the stackup, trace thickness, and PCB material. He also takes care of the controlled impedance requirements by calculating the feasible thickness, width, and height for the traces that need impedance control. Stick to the following relationships to know how impedance depends on dimensions: