Lucent Technologies Inc.

Masis Mkrtchyan

George Patrick Watson

Raymond A Cirelli

David Lee Windt

Reginald Conway Farrow

Lee Edward Trimble

A process for device fabrication is disclosed. In the process, optical lithography is used to introduce an image of a desired pattern into an energy sensitive material. In the process, a filter element is provided. The filter element has at least two regions of different transmittance, each region denominated an aperture. The regions are selected by obtaining information about the desired pattern and an optical lithographic tool that will be used to introduce the image of the desired pattern into the energy sensitive resist material. A filter element that provides an image that, when developed, will provide features with dimensions within acceptable process tolerances is then designed. The filter element is designed by modeling the effects of each aperture of the filter element on the intensity profile of an image of the desired pattern. The combined effect of the apertures is then determined. If required, an aspect (transmittance, orientation, dimension) of the one or more of the proposed apertures is adjusted to provide a modeled intensity profile that more closely corresponds to the desired lithographic result. Once the aspects of all apertures is determined, the filter element is fabricated and used in the optical lithographic process by placing the filter element in the optical lithography tool.

Process for device fabrication using a variable transmission aperture

The present invention is directed to a lithographic process for device fabrication. In lithographic processes for device fabrication, exposing radiation is used to delineate the image of a pattern into a layer of an energy sensitive resist material formed over a substrate. The pattern is then developed and the pattern is introduced into the underlying substrate. In the present invention, the substrate, typically a silicon wafer, is placed in a tool which utilizes electron beams as the exposing radiation. The silicon wafer has topographic alignment marks formed thereon. The alignment marks are used to orient the wafer in the tool accurately. The placement of the wafer in the tool is monitored by observing the intensity of the electron signal backscattered from the surface of the substrate. The alignment mark configuration is selected to provide a desired contrast between the intensity of the backscattered electron signal in the aligned state and the intensity of backscattered electron signal in the non-aligned state. The alignment mark dimensions that provide the desired contrast for a given intensity of incident electrons are selected by determining a relationship between backscattered electron signal contrast as a function of a dimensionless parameter that is the ratio of an alignment mark dimension (h) to the range (R) of the scattered electrons in the substrate. From this relationship, the desired backscattered electron signal contrast is selected. The value of the dimensionless parameter that corresponds to this data point is then used to determine the alignment mark dimension that will provide the desired backscattered electron signal contrast.

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Stirling, NJ, United States of America

Masis Mkrtchyan