Control of HF Volatile Contamination in FOUP Environment by Advanced Polymers and Clean Gas Purge
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  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.
Paul Mertens, Marc Meuris and Marc Heyns
P. González-Aguirre et al., "Control of HF Volatile Contamination in FOUP Environment by Advanced Polymers and Clean Gas Purge", Solid State Phenomena, Vol. 219, pp. 247-250, 2015