Method for preparing polyimide micro-graph on surface of GaN-based material

The invention provides a method for preparing a polyimide micro-graph on the surface of a GaN-based material, belonging to the technical field of semiconductors. The method comprises the following steps of: preparing a photoresist geometric graph mask layer on the surface of the GaN-based material; evaporating a shading layer; after carrying out Lift-off treatment, immersing by acetone and absolute ethyl alcohol, washing by de-ionized and baking; coating a negative polyimide thin film on a GaN base; baking, exposing, developing and carrying out photographic fixing to obtain the polyimide micro-graph; then curing the polyimide micro-graph at low temperature to remove a residual metal shading layer on the GaN base; and then, curing the polyimide micro-graph at high temperature. The polyimide micro-graph is used as a surface protection film, an interlayer insulation film and a deep groove filler of a GaN chip and particularly can solve the problem of surface planarization of a multi-chip assembly.