What is the pressure of photoresist development purge nitrogen

In the purging process after photoresist development, the selection of nitrogen pressure should be determined comprehensively in combination with process requirements and cleanliness requirements. The typical pressure range is 0.1~0.8 MPa. The specific analysis is as follows:

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    1. core process requirements driving pressure range

      Conventional development purging
      0.3-0.5 MPa nitrogen is used for most post-development purging of photoresist, which can balance drying efficiency and pattern integrity. For example, after the positive photoresist is developed, the residual developing solution needs to be quickly removed through the pressure range, while avoiding the generation of water marks.

    1. for precision structure purging
      , 0.1-0.2 MPa low-pressure nitrogen gas shall be used for grooves or nano-scale patterns with aspect ratio> 10 to prevent photoresist edge peeling or pattern distortion caused by high-pressure gas flow. For example, in an EUV lithography process, low pressure nitrogen can reduce micron-sized particle adsorption.

    2. some processes of special process adaptation
      require higher pressure (e. g. 0.6~0.8 MPa) to ensure uniform gas flow coverage, or reduce nitrogen consumption by 20% ~ 30% through pulsed purging (e. g. 0.5 seconds start-stop, cycle 2 seconds) while maintaining drying efficiency.

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        2. Oil-free Water Lubrication Air Compressor for

      Cleanliness guarantees
      that the oil-free water lubricated air compressor eliminates oil content through water film lubrication, and the oil content of the output gas is extremely low (≤ 0.003 mg/m & sup3;), which meets the strict requirements of photoresist development on cleanliness (such as Class 1 clean room standard) and avoids product defects caused by oil pollution.

    3. Pressure stability
      This type of air compressor adjusts the speed in real time through permanent magnet frequency conversion technology to match changes in gas demand. For example, when a pressure fluctuation exceeding ± 0.02 MPa is detected, the system automatically starts the standby compressor or adjusts the opening of the pressure reducing valve to ensure a stable purge pressure.

    4. part of the equipment in the multi-stage pressure gradient design
      adopts the combination of the main nozzle (0.4~0.5 MPa) and the auxiliary annular micropore (0.2~0.3 MPa) to form a laminar boundary layer through the pressure difference, accelerate the peeling of the liquid film while reducing eddy current interference, and improve the drying uniformity by more than 30%.

      1. 3. Key Considerations for

      Developer Type and Concentration
      Slightly alkaline developers (e. g., 2.38% TMAH) are sensitive to nitrogen pressure. High pressure may cause developer to splash and contaminate the wafer edge or equipment; low pressure may extend the drying time and increase the risk of particle adsorption. The optimum pressure range needs to be determined experimentally.

    5. Wafer Size and Structural Complexity
      Large-size wafers (such as G10.5 glass substrates) require higher pressure (0.4-0.5 MPa) to ensure uniform airflow coverage; three-dimensional structures (such as TSV vias) require low-pressure pulsed purging to avoid uneven drying caused by airflow vortices.

    6. Cleanliness and particle control
      The purity of nitrogen should be ≥ 99.999 (5N grade) to prevent impurities from contaminating the photoresist. The oil-free water-lubricated air compressor can effectively isolate external particles through a closed water circulation system, and cooperate with a terminal filter (such as a 0.01μm filter element) to ensure the cleanliness of the purge gas.

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