Device Photolithography: Forward

DEVOTED T O T H E S C I E N T I F I C AND E N G I N E E R I N G ASPECTS OF ELECTRICAL C O M M U N I C A T I O N Copyright © 1970, American Telephone and Telegraph Company Device Photolithography Foreword The fabrication of semiconductor and thin-film integrated circuits requires the delineation of precisely defined patterns in various materials in order to obtain the required functional performance of the device. Photolithographic processing has primarily been used for this purpose, requiring that masks be generated as the basic "tool" for producing integrated circuits. This issue is devoted to a detailed description of a new mask-making system intended to satisfy the Bell System's requirements for increasing numbers of increasingly complex masks. The system features high precision and large throughput made possible by a specially designed family of machines linked together by a computer-controlled information system. The heart of the system is the primary pattern generator (PPG) which produces the original artwork by scanning a tv-like raster pattern on a photographic plate with a focused laser beam. The horizontal deflection of the beam is provided by reflecting it off a spinning polygonal mirror while the vertical motion of the plate is provided by a precision stepping table. The laser beam is modulated by an acoustooptic element under the control of a digital data stream which contains the topographic information. The machine is capable of generating a 22-cm by 18-cm pattern with an address structure of 32,000 by 26,000 units in about 10 minutes.