Institute of Microelectronics Technology, Academy of Sciences,
Chernogolovka, Moscow district, 142432, Russia
Today there is an increasing demand for producing real three-dimensional structures, such as blazed gratings, Fresnel lenses, lens arrays, computer generated holograms, diffractive optical elements and etc. In these cases the total area has to be exposed with a continuously variable dose, which of course needs proximity correction as well - but thiswas not available up to now. All established methods for proximity correction aim to correct for two-dimensional structures. Most of them just take care for an absorbed dose of 100% inside the exposed structures not considering the dose distribution outside, which is below the 100% level. Characteristic sizes of the optical elements mentioned above belong to range 100nm-10um so proximity effect correction is a crucial point of the whole technological chain.
The method of "Simple Compensation" introduced by ARISTOV et al  has been developed to a very powerful tool for correction and simulation of proximity effects [2,3,4] which led to the widely used software package "PROXY". We extended this numerical calculation method for 3D correction , where each element of the exposed structure will be assigned by a required absorbed dose. We used such a procedure in iteration and 5-10 iteration are sufficient to obtain self-consisted exposure time distribution T(x,y).
After exposure with T(x,y) and development we obtained as examples stairs, linear and circular zone plates , splitters of microbeam and other prototupe of optoelectrnics interconnects with good reproducing of designed structure with up to ten levels in PMMA resist of micron thickness on Si wafer.As the next step we transferred the resist relief in rigid material by electro-chemical deposition of Cu (Ni). The final step was mechanical printing of in polymer material. Results of optical testing of created lenses showed focus spot about 5um with good efficiency.