Dry etch damage and its effect on electronic and optical nanostructures

The creation of nano-structures in 3–5 semiconductors is currently of great interest. If the conventional route of pattern definition in a resist followed by pattern transfer is used, this implies in most cases electron beam lithography and some form of dry etching. Using electron beam lithography, patterns of 10nm width on 40nm centre to centre spacing can be transfered to metal lines on thin substrates; even on normal wafers, linewidths of 25nm on 60nm spacing are achievable with state of the art machines.If the creation of a raised structure is necessary because of the physics of the situation, it is important to consider the damage which may be introduced by dry etching. The methods by which dry etch damage can be revealed are discussed, and the ways in which it can be reduced mentioned. Progress towards understanding the microscopic nature of the damage will be reviewed. Examples are drawn from etching of GaAs/GaAlAs in Silicon tetrachloride and methane/hydrogen.