Monitoring of Ammonia Airborne Molecular Contamination in Semiconductor Fabrication

- NH3 Monitor -

Airborne molecular contaminants (AMCs) cause product quality issues in modern semiconductor production, even at extremely low ppb concentrations. AMCs first became an issue with the introduction of chemically amplified resists in the 1990s. A defect occurred once the photolytically initiated acids within the resist were neutralized by airborne ammonia (NH3) from cleanroom. This interaction is device defect relevant as it deteriorates line width and line structures. Therefore, measurement of ammonia airborne molecular contamination in cleanroom became common, and Ion Chromatography has been used for a long time.

Ammonia contamination in the cleanroom may come from different, sometimes unexpected sources: outside air intake, evaporation from personnel or leakage from the equipment. Time to time there are random events leading to the increase of ammonia concentration and resulting in haze on optical surface of reticles and mirrors. However, it is problematic to rapidly identify and eliminate the source of ammonia contamination before affecting production yields, as it may come from anywhere.

Manual analysis of AMCs does not provide high spatial resolution and may delay with the detection of contamination, resulting in the spread of contamination through the cleanroom and leading to the yield deterioration.

In order to minimize the yield loss caused by ammonia airborne molecular contamination, it is highly important to obtain analysis data with high spatial resolution for quick determination of contamination source and immediate countermeasures.


Voice of Cleanroom Facility Quality Department Managers

  • Need to increase spatial resolution of analysis but increase of manual sampling and analysis is expensive and has big time gap
  • Requirements to the design of analytical system vary from fab to fab

Solution from HORIBA

Features of NH3 Monitor

  • Line Selector with multiple sampling points for high spatial resolution
    Customized to customer requirements for 4, 8, 16 and more sampling points.
    Measurement range: max. 0-1000 ppb, min. 0-100 ppb, LDL 1 ppb.


  • Time and cost efficiency
    Automated measurement, no special skills required.
    Helps to reduce management cost, time and labor cost.


  • Transportable
    Portable system on the trolley cart enables use of one system at different cleanrooms of the building.
    Allows to get AMC monitoring data from different premises of the fab: warehouse, cleanroom etc.


AMC Monitoring System

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HORIBA’s Solution for Semiconductor Cleanroom

In the cleanroom, where AMC analysis is performed manually, sampling only at point [5] of Figure 1 may cause a delay in detection of contamination and spread of AMC trough the whole cleanroom. HORIBA multi-point measurement system composed from Line Selector and AMC Monitoring System with multiple sampling points [1] [2] [3] [4] [5] at Figure 1 allows to increase spatial resolution of analysis, which leads to the early detection of AMC source and rapid countermeasures. Such multipoint AMC monitoring system may contribute to the improvement in production yields, device quality and reliability. 

Multi-point AMC Monitoring

Figure 1 Multi-point AMC Monitoring

Example of Operations and Different Types of System




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