Mössbauer spectroscopy has been used to study tin(II) sensitizer deposits formed on Kapton films (du Pont polyimide) for use in the recently reported photoselective metal deposition (PSMD) process. Combined with previous results, this work shows that the sensitizer is present as a colloid in the sensitizing bath and is adsorbed on the substrate when it is dipped. This activation mechanism would be expected to apply to other insulating substrates as well. The photosensitive substance contains more tetravalent tin than divalent. The divalent tin is oxidized by exposure either to air or to the Pd activation bath. The photosensitive compound is not any well recognized tin oxychloride or hydroxide.

Non-contact electrical metrology offers a fast and cost saving monitoring of dielectrics in IC manufacturing process. This corona-Kelvin measuring technique has entered the maturity stage with about 400 tools installed in silicon IC-fabs. We discuss recent advancements that broaden the spectrum of monitoring parameters and enhance the precision of these measurements. We also discuss the current ongoing extension of corona-Kelvin metrology to the micro scale measurement on sites as small as 30µm x 30µm. This opens new possibilities for non-contact electrical testing of product wafers, rather than expensive process monitor wafers. Micro-measurement is illustrated using flash memory ONO structures and corona induced programming and erasing.

Surface deposits containing hydrated Sn(II) species are generated when substrates are immersed in stannous chloride solutions, and then rinsed in water. These deposits, after a later immersion in an aqueous solution of PdCl2 , are capable of activating electroless plating baths to produce a metal deposit on the substrate. The Sn(II) species, however, can readily be photo‐oxidized by exposure to ultraviolet light in air, yielding Sn(IV) and thereby destroying the latent catalytic surface. Thus, selective electroless metal deposits on a variety of substrates may be generated by exposure through an appropriate mask.

The optical response of a representative PSMD imaging system, stannous chloride sensitized polyimide film, was determined by exposing sensitized substrates to ultraviolet radiation and measuring the resulting decrease in catalytic activity for electroless copper deposition. This activity was determined by measuring light transmission through the deposited metal and substrate.The imaging reaction photoresponse was measured in the 200–400 nm wavelength range. The sensitivity was found greatest at 200 nm, decreasing monotonically with wavelength. The upper limit for useful imaging in air occurred in the vicinity of 350 nm. The imaging reaction rate was also found proportional to I0.7 , where I is the incident Tight intensity. This intensity dependence was found over the entire range of measured wavelengths. An explanation of the system's optical behavior in terms of light‐generated electronhole pairs is offered.

During the past five years great progress has been made in CV replacement metrology which utilizes precise dosing of electric charge on dielectric surfaces achieved with a corona discharge in air. This charge produces controlled changes of electric field in the dielectric film and in the space charge region of semiconductor substrate. The response of the dielectric and semiconductor is monitored in a non-contact manner using three measurements: the contact potential difference (CPD) in the dark, CPD under strong illumination, and the small signal ac-surface photovoltage (ac-SPV). In COCOS metrology these measurements are performed as a Junction of the corona charge placed on the whole wafer. A near equipotential, whole wafer surface is maintained while the semiconductor space charge is transferred from accumulation — through flat band — to deep inversion. Data analysis based on electrostatic equations and charge neutrality gives a total set of electrical parameters, equivalent to those obtained in MOS-CV metrology, characterizing the space charge, the semiconductor-dielectric interface and the dielectric film. The equipotential condition is crucial for reducing charge transport along the surface without creating guard-rings. Using a blanket of corona charge placed over the wafer surface and whole wafer mapping of CPD and SPV, the COCOS metrology enables one to obtain whole wafer maps of almost all parameters. Examples are given, illustrating COCOS application to Si/SiO2, with an emphasis on thin gate oxide reliability.