Semiconductors, microcircuits, and microchips manufacturing requires very precise condition to be maintained in the manufacturing/ processing area. Many materials used in the assembly and packaging of semiconductors-such as plastic encapsulants, die attach adhesives, and certain PCB laminates-are hygroscopic and thus highly susceptible to high humidity conditions.
Effects of Uncontrolled Humidity
Hygroscopic materials can lead to:
- Corrosion of circuits points
- Operational failure of semiconductor assembly
- Improper adhesion of photoresists
- Condensation on semiconductor surfaces or process equipment
Ingress of corrosive gases into semiconductor assembly or manufacturing area can lead to:
- Corrosion of silver contacts by strong oxidising properties of sulfur compounds, especially H₂S
- Corrosion of copper and aluminium by SO₄²⁻
- Crystal formation by neutralisation reactions between SO₄²⁻ or NO₃⁻ with NH₄⁺
General Recommendation
Relative humidity in some semiconductor assembly areas may be maintained at approximately 30% RH at 20°C (70°F). However, many critical processes in semiconductor manufacturing—particularly in wafer fabrication and advanced packaging—require significantly lower and more precisely controlled humidity levels, often below 10% RH. Additionally, it is important to remove any corrosive gases to protect electronic equipment and devices from the threat of abrupt failures.
Bry-Air Solution
In the assembly area, during the production of semiconductors and integrated circuits, excessive moisture adversely effects the bonding process and increases defects. Photosensitive polymer compounds called photoresists are used to mask circuit lines for etching process. Due to their hygroscopic nature, they can absorb moisture, resulting in swelling, poor adhesion, and bridging of microscopic circuit lines, leading to circuit failure.
Wafer Fabrication Area: During wafer manufacture, spinners spray developer on the wafer surface, causing rapid solvent evaporation and cooling of the wafer. This cooling can result in condensation of water vapour from the air onto the wafer surface, which can alter the characteristics of the developer. The resist also absorbs this moisture, causing the polymer to swell. Maintaining precise and often very low relative humidity levels (significantly below 30% for advanced processes) prevents the wafer surface from cooling below the dew point of the surrounding air, thereby avoiding condensation, process variation, and spoilage.
Photo Lithography Room: Conditions in the photolithography room need to be maintained between 20% to 35% RH at about 70°F. Excessive moisture can affect the adhesion of photoresists, leading to surface defects and process yield loss. Additionally, controlling humidity is critical to prevent condensation on optical equipment and photomasks.
Stress fractures in quartz or glass components usually result from mechanical handling or rapid thermal cycling, rather than direct moisture absorption.
Faster Vacuum Pump Down: If humidity levels are high, operation of vacuum equipment like cryopump slows down due to large load of water vapour.
Protection of EPI equipment: Water vapour or moisture condenses on chilled surfaces of epitaxial equipment corroding of components resulting in operation failure and slowdown of the process.
Bry-Air Desiccant Dehumidifiers can effectively maintain the most stringent humidity conditions required for semiconductor manufacturing areas, since they are capable of maintaining RH as low as 1% or even lower at a constant level, regardless of ambient conditions.
To avoid abrupt failures due to corrosive gases, Bry-Air Gas Phase Filtration (GPF) Systems are the ideal solution. They remove corrosive gases through the process of adsorption and chemisorption. Besides, the GPF systems neutralise odourous gases and make the environment comfortable for humans.
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