A computer-controlled electron-beam machine for microcircuit fabrication

The main advantages of electron-beam methods for the fabrication of microcircuits are: 1) improvement in resolution; and 2) ease of automation. A computer-controlled electron-beam machine has been developed from a high-resolution scanning electron microscope and has incorporated several important features for use in microfabrication, such as an LaB6gun to improve brightness and stability, and a special electron collection system based on channel multipliers, which is particularly suitable for use with large flat specimens. The control system is based on a small general-purpose computer with a flexible data input facility which can be made compatible with the output of most computer-aided mask design facilities. The input data is based upon rectangular shapes but additional nonrectangular shapes can also be handled. Several of the important technical areas of the machine have been evaluated, e.g., resolution, speed of operation, area of coverage, etc. It has been found that speed of operation and area of coverage are both related to the beam diameter used and the effect of this rather complicated interrelationship has been studied. The machine has been used to generate patterns on mask and wafers and results indicate that it has direct application to microcircuit manufacturing and one immediate use would be to develop it into a mask maker where it could produce a complete set of standard size masks (1x) in one working day.