A transformer coupled plasma (TCP) source has been integrated into a production tool and characterized for subhalf micron etching of thin films. A planar 13.56 MHz plasma is produced over a wide pressure range of 1–500 mTorr. Langmuir probe measurements below 10 mTorr show ion densities ≳1012 cm−3 and low plasma potentials. These properties are favorable for high etch rates and low damage to device structures. Radio-frequency power is also supplied to the wafer electrode for dc bias control. Separation of the plasma generation and dc bias functions allows the control of microloading effects upon the etch profiles of dense and isolated lines. Performance of the tool is described for the etching of polysilicon and tungsten polycide films on substrates up to 200 mm in size. The evaluated characteristics include etch rate, selectivity, and microloading. The TCP is shown to be an advanced source with the capability for meeting 64 megabit device requirements.

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This paper presents results from an experimental study of the effects of resist side -wall slope variations on the linewidth measurement accuracy of a Confocal Scanning Laser Microscope (CSLM), as compared with a Scanning Electron Microscope (SEM). Both the top and bottom dimensions of patterned resist features from 0.5µm to 2.0 µm wide were measured using CSLM, cross -sectional SEM and on -axis SEM. Substrates tested included bare silicon and three thicknesses of oxide on silicon. The resist was patterned with a range of deliberate stepper defocus which provided a 15° variation in side -wall angle. Data for the three methods is compared and shows that in this case the CSLM demonstrated good measurement accuracy for independent top and bottom width measurements. Errors due to resist sidewall slope variation were small, random and consistent with the experimental noise level.

This paper describes a semiconductor metrology system based upon ultra-violet wavelength confocal microscopy. The system is capable of linear metrology of resist features down to 0.5 microns linewidth with low dependence on substrate type. Short term precision of better than 5nm standard deviation can be obtained with this system. The optical design for 325nm operation is described together with details of the data acquisition system. Experimental data compares the performance of ultra -violet and visible light versions of the system for resist metrology, showing the benefit of using a wavelength at which the resist is absorbent. Conclusions are drawn about optimal regimes for metrology as well as the extension of this technology to yet shorter ultra-violet wavelengths.