Temperature resistance of e-beam polymers
Layers and structures of e-beam polymers possess different temperature resistance properties. PMMA layers are generally the most stable. Structures are maintained even at temperatures up to 260 °C, only a roundening of resist edges occurs and PMMA layers just turn slightly darker in colour. The copolymer of AR-P 617 in contrast begins to significantly change colour already at 240 °C, and layers and structures develop defects. The CSAR polymer is already attacked at approximately 200 °C; a tempering at higher temperatures is thus not recommended. All three polymers can still be removed after a tempering at maximum temperature.
The novolac layers of e-beam resists are generally stable up to 300 °C. Depending on the film thickness however, structures may show a certain rounding and even melt if the layer thickness is > 2 µm. This in particular concerns positive e-beam resists (AR-P 7400), while negative e-beam resists are significantly more stable. A removal is basically impossible after a tempering at maximum temperature, and only a plasma etching step may help to remove the layer.
Overview E-beam positive