Papers by Keyword: Cross-Contamination

Abstract: In order to better understand and model the whole sorption behavior of the HF when in contact with a Cu surface inside a FOUP and thus control the related yield losses, Cu-coated wafers have been exposed to varying HF (ppbv) and H₂O (% RH) airborne concentrations. These experiments have yielded a HF-Cu sorption empirical-mathematical model that may be used as an industrial tool for queue-time or fluoride surface concentration predictions. Besides, the formation of CuF₂ only in case of corrosion is evidenced by the XPS measurements whereas the key role of the H₂O is further confirmed by the desorption experiments. The H₂O retained by the surface is actually responsible for promoting the HF adsorption/desorption onto/from Cu and enables a HF threshold concentration that separates the two well differenced uptake regimes; adsorption and corrosion.

Abstract: Semiconductor manufacturing technologies have developed to the point where molecules, such as water, oxygen and airborne molecular contaminants (AMCs), have become detrimental in specific process conditions. Front Opening Unified Pods (FOUPs) are designed as controlled microenvironments (MEs) that protect processed wafers from AMCs during storage and transport. However, it has been demonstrated that FOUPs are able to accumulate by sorption molecules outgassed by processed wafers. Such contaminants are then able to be subsequently released and transferred to other sensitive wafers leading to detrimental impact [1,2]. This cross-contamination scheme from FOUP to wafer was evidenced especially for volatile acids such as HF or HCl and is responsible of yield losses due to drastic corrosion issues or crystal growth on Cu, Al or TiN materials [1,3,4]. These cross contamination issues can be reduced or controlled using low sorption and outgassing polymer materials as previously reported [4,5]. Another AMC control measure is to purge the FOUP with a dry gas. This provides several advantages, for example, wafers are not easily oxidized thus preventing oxide layers, deposition of hydrocarbons and metal defects [6] However, there is no measured information about the purge impact has on AMC control inside a FOUP. The purpose of this paper is to show and quantify what effect two different FOUP polymers using nitrogen and clean dry air (CDA) purge have on the HF volatile acid control through the Cu-wafers storage.

Abstract: High-k gate dielectrics and metal gate electrodes have become essential for emerging device technologies because they enable the continuous scaling down of devices while maintaining a high performance [. However, since they are composed of novel metallic elements that have never before been used in conventional processes, special care must be taken when handling these materials in the production line. In particular, cross-contamination that occurs due to transporting contamination via processed wafers can cause serious problems such as deterioration of device properties and yield loss [. The process of cleaning the backside and bevel of a wafer is now increasingly important for avoiding these problems. To date, there has been no detailed evaluation of contamination removal on various films performed for elements such as hafnium, which is one of the key elements in high-k/metal gate technologies. In this study, we evaluated hafnium contamination on three types of wafer surface after the cleaning process and investigated the cause of different residual amounts of hafnium contamination on the different wafers.

Abstract: Today, the use of Pods or FOUPs (Front Opening Universal Pod) in IC manufacturing leads to specific molecular contamination issues related to the enclosed environment made with porous polymers (mainly PEEK, PC and PP) that constitute these containers. Indeed, such materials are known to outgass airborne molecular contaminants (AMC), especially polymers additives [1,2]. They are also able to absorb volatile compounds present in their atmosphere coming from the connection to an equipment or from the release of wafers just processed [3,4]. As a result, a reversible outgassing of species previously trapped in plastic is possible. This is especially critical in presence of wafers sensitive to the released contaminants leading then to potential detrimental impacts. This cross-contamination scheme was clearly evidenced for volatile acids in presence of Cu layers leading to corrosion issues [4].