The effect of gel layer formation during development on critical dimensions

Patterns unfaithful to the aerial images were obtained by the spin-off development method, in which a spin-off step is added to the static development method. The critical dimension (CD) of the isolated line decreased more than that of the dense line as wafer rotation speed increased. The CD difference between the isolated line and the dense line was not due to the alkaline concentration recovery by the stirring effect of the spin-off development method and the aerial image difference between pattern types. It was due to the difference in the ease of removing the semi-dissolving layer, which was observed to cover the sidewall of resist lines, at the boundary between developer and resist during spin-off. The developer flow along the wide space area and the wide area of the layer contacting developer during spin-off are thought to make the CD of the isolated line small. The mechanical removal of the semi-dissolving layer is one of the factors to determine CDs.