Low energy electron beam lithography

摘要

A low energy electron beam lithography system uses an 2 KeV electron beam of about two hundred microamperes, a 4 Division Complementary Mask (4DCM) formed from a monocrystalline silicon wafer with membranes about 100 nm thick that are surrounded by supporting silicon struts, and spaced about 50 microns from an electron sensitive resist layer about 20 nm thick that covers a nonmetallic conductive layer that covers a semiconductor wafer. Distortions in the 4DCM and semiconductor wafer are sensed and an error distortion signal is generated that results in the electron beam being tilted so as to compensate for the distortions to minimize image placement errors.

主权项

1. A system for patterning an electron sensitive resist layer covering a semiconductor wafer comprising:
an electron beam system characterized by an accelerating voltage of about 0.5 to about 5 KV, an electron beam current of about 50 to about 800 microamperes, the beam having a diameter of about 1 to about 9 mm, and fine deflectors for adjusting tilt of the electron beam; an n Division Complementary Mask (nDCM), where n is an integer 2 or greater, having struts that support each membrane that has formed therein a pattern that is to be transferred to the resist layer, the thickness of the resist layer being about 10 to about 300 nm, and the thickness of each membrane being about 50 to about 500 nm, the nDCM and the resist layer being spaced about 10 to about 300 microns from each other and being positioned in the path of the electron beam; the resist layer having a thickness of about 10 to 300 nm; a nonmetallic conductor layer having a thickness of about 50 nm and lying under the resist layer; a distortion sensor having an output, said distortion sensor being adapted to sense alignment distortions between the membranes of the nDCM and the semiconductor wafer and provide at the output thereof signals representative of alignment distortion errors between the membranes of the nDCM and semiconductor wafer; and a system control unit having an input coupled to the output of the distortion sensor for controlling overall operation of the system, said system control unit being adapted to generate from signals received from the distortion sensor a distortion error correction signal at an output thereof that is coupled to inputs of the fine deflectors whereby the tilt of the electron beam is adjusted such that alignment distortion errors between the membranes of the nDCM and the semiconductor wafer are compensated for so as minimize image placement errors.