International Business Machines Corporation

Stephen E Knight

Robert K Leidy

Keith J Machia

Reginald R Bowley, Jr

Vincent J Carlos

Dianne L Sundling

James E Doran

Joseph E Shaver

Jed Hickory Rankin

Stephen Ellinwood Luce

Thomas L McDevitt

Edward W Conrad

James Allan Bruce

Orest Bula

Charles Arthur Whiting

Daniel C Cole

Matthew C Nicholls

Joshua J Krueger

A method uses three dimensional feature metrology for implementation of critical image control and feedback of lithographic focus and x/y tilt. The method is for measuring 3 dimensional profile changes in a photo sensitive film and feeding back compensatory exposure tool focus corrections to maintain a stable lithographic process. The measured focus change from the optimal tool focus offset is monitored directly on the critical product images for both contact hole and line images. Z Focus corrections and x/y tilt corrections are fed back independently of dose to maintain critical dimension (CD) control. Additionally, the method can be used to diagnose problems with the focusing system by measuring the relationship between line edge width and barometric pressure.

Contact hole profile and line edge width metrology for critical image control and feedback of lithographic focus

A method uses three dimensional feature metrology for implementation of critical image control and feedback of lithographic focus and x/y tilt. The method is for measuring 3 dimensional profile changes in a photo sensitive film and feeding back compensatory exposure tool focus corrections to maintain a stable lithographic process. The measured focus change from the optimal tool focus offset is monitored directly on the critical product images for both contact hole and line images. Z Focus corrections and x/y tilt corrections are fed back independently of dose to maintain critical dimension (CD) control thereby achieving improved semiconductor wafer printing. Additionally, the method can be used to diagnose problems with the focusing system by measuring the relationship between line edge width and barometric pressure.

A mask/wafer control structure and an algorithm for placement thereof provide for data placement of measurement control structures, called a PLS, Process limiting Structure, on a mask and a plurality of chips on the wafer which provide for tighter control of both mask manufacture and wafer production by providing the most critical design structures for measurement during creation of the mask, and in the photolithography and etch processes. The PLS structures are located at multiple locations throughout the chip, and so they receive the same data preparation as the chip, and measurement tools are able to measure the same features at each fabrication step from fabrication of the mask to final formation of the etched features. Manufacturing control and the interlock between the wafer fabrication and the mask fabrication are enhanced, allowing for improved quality of the final product.

Mask/wafer control structure and algorithm for placement

Fine feature lithography is enhanced by selectively providing exposures to correct for effects such as foreshortening, corner rounding, nested to isolated print bias, feature size dependent bias, and other image biases in semiconductor processing. These results are achieved by increasing the local exposure dose in critical areas of specific images, such as line ends and corners. The general process incorporates techniques which tailor the exposure dose as a function of position to achieve the desired final image shape. The techniques include contrast enhancement layers (CEL), scanning optical beams, and exposures with different masks. In one embodiment the process of forming a pattern comprises the steps of providing a substrate having a photosensitive coating, exposing the center area of the pattern on the photosensitive coating with one mask, and exposing ends of the pattern on the photosensitive coating without exposing the center area with a second mask. The second exposure overlaps the first exposure and may extend beyond the pattern but the second dose is much lower than the first dose.

Process for enhanced lithographic imaging

A method and apparatus according to the present invention achieves improved lithographic printing of semiconductor wafers. An optimum tilt for projection optics in a lithography tool relative to a wafer in a direction perpendicular to a scanning direction is characterized for each of a plurality of wafer technologies and levels. The corresponding optimum tilt is retrieved from a database to adjust the lithography tool accordingly, depending upon what technology and level is being processed.

Method and apparatus for adjusting a tilt of a lithography tool

The invention provides a method for substrate preparation prior to applying photoresist to the substrate. A substrate, such as a TEOS-based silicon dioxide or silicon nitride film, is selected and treated with reactive oxygen. The reactive oxygen can comprise ozone or ozone plasma, for example. After treatment of the substrate, the photoresist, preferably an acid-catalyzed photoresist for use with deep UV sensitization, is applied.

Method for applying photoresist

Growing community of inventors

Essex Junction, VT, United States of America

Stephen E Knight