APM (NH4OH/H2O2/H2O) based cleaning mixtures offer interesting perspectives for use as single chemistry cleaning solutions. It is known that such mixtures can remove organic contamination because of the oxidizing nature of the H2O2 and they have very good particle removal properties. In order to optimize the APM clean with respect to metallic contamination, complexing agents need to be added (= APM+(TM)). In this paper, the metal removal efficiency of APM cleaning mixtures is explored as function of dilution ratio, temperature and complexing agent concentration. An optimal removal for all metals is obtained using concentrated APM solutions at higher temperatures with a metal complexing agent. In addition, it is recommended to implement an acidified rinse after the APM to prevent the deposition of metals such as Ca+2 during final rinsing.

Single chemistry cleaning may serve as a potential substitute for the conventionally used RCA cleaning sequence to meet progressively stringent requirements during semiconductor fabrication. The current study involves stability determination of aromatic complexing agents (CAs) such as catechol, 8hqsa and pyridinone-type compounds employed in 1/4/20 APM and related cleaning mixtures (like 1.65/1/5 NC and TPM) at 35degreesC and 50degreesC. The CA concentration was monitored as a function of UV absorption after periodic sampling from corresponding solutions. CA degradation was assumed to follow a linear or an exponential decay representing rate equation laws of zeroth and first or pseudo-first order, respectively, and the lifetimes of the CAs (t(1/2)) deduced accordingly. Compound 'X' was the most stable of all CAs under investigation. All others were less stable by a factor of 3-5. The stability of CAs may be discriminated according to their radical scavenging capability and where applicable the oxidation potentials of their tautomers.

Sub-micrometer particles on a wafer surface can have a detrimental effect on the yield in semiconductor device manufacturing and with shrinking dimensions of IC structures, this effect becomes more and more important. The critical particle sizes as set by the ITRS roadmap indicate that for sub-100-nm technologies, particles on the order of a few tens of nanometers will have to be removed. Therefore, there is a growing need to optimise the surface cleaning in order to control the density of these particles. In this paper, an overview is given of the current state-of-the-art in wafer cleaning technology and various approaches to achieve a good removal of all kinds of particles on various substrates are presented.

As dimensions scale down and government, regulations are becoming stricter, the industry is moving to dilute single step cleaning, preferably with,low etching and re-usable chemicals. In combination with a single tank tool this provides a high throughput process that can be run on a low footprint tool, economically translated: a low Cost of Ownership. This article shows that APM+ -a chelating agent modified APM- run in a Single Tank Tool, is a good alternative for traditional cleaning sequences. APM+ is able to remove metals without risk for redeposition, without altering other APM properties like particle neutrality and removal. Electrical data show that a yield, of almost 100 % is easily attained, compared to 0 % for the same chelating agent free APM solution with added metal contaminants, proving the possibilities of APM+ as an alternative for future cleaning.

We have studied the particle removal efficiency of HF-based cleaning mixtures used to clean wafer surfaces during semiconductor manufacturing. SiO2, Si3N4, and metallic oxide (Al2O3, TiO2) particles can be easily removed from silicon wafers using a HF-based clean, whereas the removal of metallic particles and especially Si and polymeric particles is much more difficult. This is explained in terms of surface hydrophobicity effects. For thermal oxide wafer substrates, a low removal efficiency is observed for the positively charged Si3N4 and Al2O3 particles. This has been explained previously by redeposition of the particles from the carry-over layer during the final rinse [R. Vos, I. Cornelissen, M. Meuris, P. Mertens, and M. Heyns, in Cleaning Technology in Semiconductor Device Manufacturing VI, J. Ruzyllo, T. Hattori, and R. E. Novak, Editors, PV 99-36, p. 461, The Electrochemical Society Proceedings Series, Pennington, NJ (1999)]. Surfactants are found to increase the removal of Si and polymeric particles from silicon substrates. This is attributed to the elimination of hydrophobic attraction forces. In addition, the surfactant is also successful in preventing the particles from redepositing during the final rinse treatment, because during the rinse, both the particle and the substrate have the same surface charge. (C) 2001 The Electrochemical Society.