A modified lift-off technique to prevent pattern following effect in microfabrication

A surface micromachining technique is proposed which significantly reduces the undesirable pattern following effect and prevents disturbance in subsequent layers of the structure. This modified lift off method starting from a flat surface embeds the base layer of microstructure in the substrate in order to maintain initial surface profile, and thus allows fabrication of subsequent layers to start from another flat surface. Theoretically, multi layer structures can be fabricated by this technique layer by layer with minimum disturbance caused by pattern following effect. It also eliminates the misalignment error which is a common structure disorder in multilayer structures. The technique is illustrated and used for fabrication of aluminum and copper bias lines on a glass and silicon substrates. An even surface profile with average step height of 10 nm has been achieved. The proposed technique can be extended to other materials with proper adjustments.