Browse Prior Art Database

COMBINED OPTICAL OVERLAY/CD TARGET ARRAY

IP.com Disclosure Number: IPCOM000030862D
Original Publication Date: 2004-Aug-30
Included in the Prior Art Database: 2004-Aug-30
Document File: 2 page(s) / 22K

Publishing Venue

National Institute of Standards and Technology

Related People

Richard Silver: INVENTOR [+2]

Abstract

This is a write up to describe a new invention which consists of a method and target design for overlay and critical dimension mesurements using optical methods. The key is two fold. One aspect is to allow optical overlay measurements using device sized dimensions and the other aspect is to enable critcal dimention measurement, but using the same target. The targets are unique for overlay alone, but provide a particularly interesting application when combined with CD measurements.

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Provisional Patent Application:

This is a write up to describe a new invention which consists of a method and target design for overlay and critical dimension measurements using optical methods. The key is two fold. One aspect is to allow optical overlay measurements using device sized dimensions and the other aspect is to enable critical dimension measurements, but using the same target. The targets are unique for overlay alone, but provide a particularly interesting application when combined with CD measurements.

The target design, shown in Figure 1, is composed two sets of lines at one level and a second set at a different level. The bars or lines can be spaced at a particular design to enhance the measurements as described elsewhere. The line or trench features can be either segmented or continuous as shown in the figure.

An example design may be 5 to 10 lines, 4 microns in length, 100 nm in width with a spacing of 400 nm, in each set of components. There are two sets of components at one level and a second single set of target components (more could be used, but to no obvious advantage) at a second level, again as shown in the figure. A similar line array is placed directly to the side, in the direction of the length of the lines at the same level. The gap between these same single level sets of lines may be for example 5 microns. A similar single set of lines is placed at a second photolithographic level having a similar design, but with a 0.5 or 1 micron lateral separation.

The level one targets each have a well defined centerline. The two targets together have a unique centerline. The l...