High Precision, Automated CD Metrology Station

METRICS - 5026

Keywords critical dimension measuring tools, metrology, field emission guns, electron optics

Start Date: 01-JAN-90 / Duration: 18 months

[ contact / participants ]

Objectives and Approach

The goal of the METRICS project was to tackle the major risk elements in the development of a critical dimension (CD) measuring tool, based on electron optics, for the sub-half micron regime.

Progress and Results

In the course of the project, all those elements identified as having significant risk have been addressed and suitable solutions developed. Involving four research institutes, three user groups and two instruments companies, the project team has made significant breakthroughs and incremental performance improvements relative to today's technology.

The following elements have been successfully demonstrated.

• Full automation of all relevant SEM functions to match fabline requirements. This included a laser-based closed loop control system to control the height of the wafer relative to the objective lens: this eliminates the need for manual focusing, and allows constant excitation of the objective lens for maximum reproducibility.
• New algorithms that extend the Monte Carlo modelling of electron/matter interaction into the low-voltage region with sufficient accuracy to predict physical profiles based on backscattered and secondary electron yield.
• Metrology software with sub-pixel interpolation for high-precision measurements with maximum ease of use.
• Revolutionary detector designs to maximise the yield of those electrons carrying the most information.
• A low voltage retarding field emission gun electron column that shows performance well in advance of any known commercial system.

These achievements will be consolidated into a metrology system that will satisfy the needs of the industry for sub-half micron metrology. However, a number of the project deliverables will be commercialised from their current form.

Exploitation

Commercialisation already includes:

• Metrology software: Currently being beta-tested by a major IC manufacturer.
• Detector technology: Discussions are now progressing between one of the research partners and the world leader in multichannel plate detectors.
• New column: Commercial agreements have virtually been concluded to integrate the new column into an existing Philips SEM platform to address other applications for low-voltage high-resolution microscopy.
• Automatic working distance control system: This will be further developed by Philips for analytical applications involving larger area image analysis and automated wavelength dispersive spectrometry.

CONTACT POINT

Mr H. Tolner
NEDERLANDSE PHILIPS BEDRIJVEN BV
Building AAE-P, PO Box 218
NL - 5600 MD EINDHOVEN
tel: + 31/ 40-766223
fax: + 31/ 40-766164
telex: 35000

Participants

NEDERLANDSE PHILIPS BEDRIJVEN BV - NL - C
INTEGRATED CIRCUIT TESTING GMBH - D - P
NEDERLANDSE PHILIPS BEDRIJVEN BV - NL - P
RUTHERFORD APPLETON LABORATORY - UK - P
IMEC VZW - B - A
SGS-THOMSON MICROELECTRONICS SRL - I - A
UNIVERSITY OF EDINBURGH - UK - A
SIEMENS AG / SEMICONDUCTOR GROUP - D - A
NEDERLANDSE PHILIPS BEDRIJVEN BV - NL - A

METRICS - 5026, December 1993

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html version of synopsis by Nick Cook