FOUP LPM N2 Purge System

FOUP as a Key Player

FOUPs (Front Opening Unified Pod) play a crucial role in microenvironmental control management in semiconductor manufacturing processes. In a highly sensitive and susceptible factory environment, FOUPs are employed to ensure wafers are free from contaminants and moisture as they move between processes. Taking into consideration longe idle times in-between processes, any instance of contamination or excess humidity can affect yield, wafer-to-wafer consistency and overall tool throughput. Load port purging FOUP containers can help address this obstacle and protect wafers during transfer.

Patterned 300 mm silicon wafers in a FOUP (front opening unified pod). Courtesy of Aaron Hawkins.

The Problem with FOUPs

In ordinary FOUP containers, the polymers can attract AMCs (Airborne Molecular Contaminants) from equipment or freshly processed wafers. If FOUPs become contaminated, they are likely to outgas these contaminants onto wafers–affecting later process quality and overall wafer-to-wafer variation. In addition to AMC, excess moisture and oxygen levels can react with residual process chemicals and in-turn impact process film quality. Nitrogen purging helps address these microenvironmental challenges.

Effects of Nitrogen Purging on Microenvironment

  • Graph showing influence of N2 purge on fluoride.
    Ion chromatography results 0.5 h. after etching, 1 h with nitrogen purging, and 3 h with nitrogen purging for FOUPs storing 12 wafers. Figure 1-1
  • Graph showing decrease in humidity following N2 purging
    Decreased humidity after nitrogen purging. Figure 1-2

In Figure 1-1, one can trace the decrease in AMC before and after N2 purging (Kamoshima et al.). Figure 1-2 shows the steady decrease in humidity after processing numerous wafers.

Retrofitting Load Port Modules with N2 Purge System

For fabs looking to equip their LPMs with N2 functionality, we offer retrofitting services. Retrofit includes installation of newly fabricated Control Box(s) and on-site conversion of LP Stage(s) on existing LPMs. 

Retrofit Specifications and Components

Control Box
<Control Box>
LPM Stage Retrofit
<After retrofit>
<Before retrofit>

Compatibility

N2 purge system retrofitting services are currently available for TDK and Sinfonia (Shinko Electric) LPMs and are compatible with Entegris and Miraial FOUP pods.

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