Spin coating of a thin film of photoresist

ht1         initial height of the deposited resist in µm
ht2         final desired thickness of the resist in µm
rot         speed of rotation in rpm
kvis       kinematic viscosity of photoresist in cSt (centistokes)
sel         number denoting the selected result.
              Use 2 for time of rotation

Spin coating of a thin film of photoresist


This interface can be used to calculate the time required to produce a thin film of photoresist by spinning it on a substrate attached to a chuck. The resists spreads on the wafer due to the centrifugal force created by the rotation of the chuck. The spin time is nearly independent of the initial resist thickness especially at high thicknesses. The kinematic viscosity of the resist is given in centistokes (1cSt  = 10-6 m2/s). Based on the desired thickness, viscosity of the resist and speed of rotation, the time of rotation can be set.

The plot gives the time of rotation required to produce a resist of a particular thickness. Thinner the resist, greater is the time required.


-The surface of the wafer is uniform. Uneven surface could affect uniform spreading of resist.
-Temperature and spin speed remains constant.

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