Stuart E. Brown

Phase shifting and optical proximity corrections to improve CD control on logic devices in manufacturing for sub-0.35-um i-line

The use of I-Line exposure wavelength for manufacturing at and beyond 0.35 micrometers presents many challenges in manufacturing. The lack of resolution, depth of focus, exposure latitude, and iso/dense offsets have caused some to switch from I-Line to DUV. With our installed I-Line base we felt it necessary to implement techniques to extend our tool life, reduce manufacturing costs while improving manufacturing margins. The results of the differential modification techniques were used to reduce the effects of topography, density, and low k lens issues. The differences seen between the binary and phase shift plates show the advantage of phase shifting below 0.35 (mu) manufacturing. We have been able to demonstrate between critical dimension (CD) control using phase shift mask with dense iso compensation over a standard binary reticle. The data shows improved CD control across the stepper field, wafer, and overall lot distribution. The impact of this work was improved speed performance. It also allowed us to move the CDs to smaller dimension because of the better control without increasing fallout due to electrical parametric roll-off.

Process control and optimization of conventional metal process for 0.18-micron logic technology

In this paper we describe the process control and optimization strategy for a conventional metal process for 0.18-micrometer technology. It is well known that the interaction of DUV resists with substrates containing nitrogen, e.g. TiN, leads to resist footing. A technique to minimize this interaction and improve CD control will be presented. We then present process optimization strategies including substrate optimization, resist thickness optimization, and use of top- anti-reflective coating. A comparison of reflectivity simulations with CD control will also be shown. DOF with varying substrate thicknesses will be presented. Strategies for CD control in sub-0.18 micrometer metal patterning will also be presented.

Real-time on-wafer evaluation of contaminant-induced defects from resist processing

In this paper we present a new non-contact, non-destructive method for real-time evaluation of both surface and interface metallic contamination from resists. The method allows for independent testing at the completion of a coat/ash or ash/removal/clean steps in processing. Using a standard 1.2 micrometer resist in both as-received and intentionally doped versions wherein alkaline and transition metals such as K, Fe, Cr, and Cu were added to the initial solution, we demonstrate that at both these crucial steps in resist processing important electrical and material parameters such as bulk Fe concentration, minority carrier diffusion length, relative surface recombination velocity, and surface charge can be detected directly on- a processed test wafer with no electrical test structures using a combination of low and high injection level surface photovoltage. Since most production fabs only test for residual particles in-line, or rely on expensive, time-consuming analytical techniques such as AAS, DLTS, or TXRF to evaluate contaminant metals, this approach offers a faster and a more economical way to control this problem.

Passive evaluation of surface and bulk ionic deposition from resist removal using surface photovoltage

In this paper we report on the application of optical surface photovoltage (SPV) to both quantify and qualify both surface and bulk effects of transition and alkaline metals deposited from photoresist in CZ P-type silicon. Using standard and specially prepared 1.2 /spl mu/ resist chemistry, we will demonstrate systematically that specific ions can affect surface charge and minority carrier lifetime. We will also show how the technique can be used for nondestructive, in-line assessment of resist-deposited contaminant metals.

Manufacturing engineering use of data management to analyze and control stepper performance in existing fabs and on stepper evaluations for new tools

This paper describes the program used to improve data collection and analysis methods in a sub-micron manufacturing environment to control photolithography steppers. The program provides any user a standard method for analysis. The benefits of this methodology are a reduction in analysis time, uniform analysis by use of similar algorithms, and the reduction in the use of multiple database programs. The programs outputs include customized reports, focus exposure curves, data tables, and SPC charts. By storing all information, historical data can be accessible in these output forms. This paper briefly explains the medium used to transfer the data from the stepper and metrology systems. Explanation of the use and results of the on-line data analysis program and examples of the programs output are also given. The program was developed to support manufacturing from 0.8 micrometers to 0.35 micrometers i-line production. The authors feel the programs are flexible enough to add more outputs for different technologies.