CONFINED ETCHANT LAYER TECHNIQUE FOR 2-DIMENSIONAL LITHOGRAPHY AT HIGH-RESOLUTION USING ELECTROCHEMICAL SCANNING-TUNNELING-MICROSCOPY

In order to realize two-dimensional lithography at high resolution (se veral tens of nanometres), a new approach to the lithography of a fine pattern using a confined etchant layer technique (CELT) in an electro chemical system is presented. A mould plate of conductive material wit h a high-resolution line pattern (which can be prepared with the aid o f e.g. electron beams) is used instead of the tip in scanning tunnelli ng microscopy (STM). The etchant species is generated at the surface o f the mould plate by electrochemical photochemical or photoelectrochem ical methods, then diffuses away from the surface of the mould plate. The key feature of CELT is the design of a chemical reaction which rap idly destroys the etchant (e.g. within microseconds on average) follow ing its generation. Therefore, the gradient of the concentration of et chant can be greatly enhanced and the thickness of the diffusion layer can be greatly decreased to several tens of nanometres. Thus, the etc hant layer is confined and its outer boundary can essentially retain t he fine structure of the pattern of the mould plate. Then the substrat e to be corroded is adjusted by ECSTM to approach the mould plate with in several tens of nanometres and the corroded pattern can retain the fine structure giving a resolution of several tens of nanometres.