The present invention is directed to a sensor head which constitutes an optical encoder in combination with a movable scale. The present invention works on the strategy that all of the functional units on the die are not, and do not need to be operational at a given time in the execution of a computer program that is controlling the microelectronic device. The method assembles a geographic location profile of a user based on the first set of information. A sensing mechanism senses movement of the roller ball and generates x-y movement signals corresponding to movement of the computer-pointing device across the surface. After such act of removing, the substrate is processed through a mask pattern comprising the pairs of immediately adjacent second features which alternate with individual of the remaining of the first features. When the substrate is etched by using a processing gas including a second gas containing halogen and carbon and having a carbon number of three or more per molecule, the processing gas is supplied such that a gas flow rate is greater in the peripheral portion than in the central portion.