Podcast
Questions and Answers
What is microcontamination primarily concerned with?
What is microcontamination primarily concerned with?
- Micro foreign material or energy affecting products (correct)
- Detection of visible dust in the air
- Measurement of temperature variations
- Monitoring chemical reactions in laboratories
Which of the following is NOT a control measure in wafer fabrication for microcontamination?
Which of the following is NOT a control measure in wafer fabrication for microcontamination?
- Electromagnetic Shielding (correct)
- Clean Room
- Ultra Pure Water
- ESD Control
How does defect density influence yield according to the provided information?
How does defect density influence yield according to the provided information?
- Lower defect density increases yield (correct)
- Yield is directly proportional to defect density
- Higher defect density increases yield
- Defect density has no effect on yield
According to Poisson's principles, yield is exponentially inversely proportional to which of the following?
According to Poisson's principles, yield is exponentially inversely proportional to which of the following?
What typically causes short circuits and/or ESD damaged devices in microcontamination?
What typically causes short circuits and/or ESD damaged devices in microcontamination?
Why does a smaller product size lead to a higher production yield?
Why does a smaller product size lead to a higher production yield?
What is the detrimental effect of microcontamination on a product?
What is the detrimental effect of microcontamination on a product?
Which of the following statements about microcontamination and yield is true?
Which of the following statements about microcontamination and yield is true?
What is the range of sizes for particulates classified as contaminants?
What is the range of sizes for particulates classified as contaminants?
Why does device yield improve as things get smaller according to Poisson?
Why does device yield improve as things get smaller according to Poisson?
Which of these is a characteristic of airborne particulates?
Which of these is a characteristic of airborne particulates?
What size range of particulates can be considered invisible?
What size range of particulates can be considered invisible?
Which of the following is NOT an example of invisible airborne particulates?
Which of the following is NOT an example of invisible airborne particulates?
In the context of microcontamination control, why is the size of particulates critical?
In the context of microcontamination control, why is the size of particulates critical?
What is a cleanroom designed to control?
What is a cleanroom designed to control?
Which particle size is closest to that of human hair?
Which particle size is closest to that of human hair?
What type of dust is categorized as aerosols?
What type of dust is categorized as aerosols?
Which of the following characteristics is NOT true for particulates in contamination control?
Which of the following characteristics is NOT true for particulates in contamination control?
What is the maximum allowable number of particles greater than 0.5µm in a Class 1000 cleanroom per cubic foot?
What is the maximum allowable number of particles greater than 0.5µm in a Class 1000 cleanroom per cubic foot?
Which filtration mechanism is primarily effective for small particles?
Which filtration mechanism is primarily effective for small particles?
At what specific particle size does HEPA filter efficiency peak?
At what specific particle size does HEPA filter efficiency peak?
What airflow speed is recommended for cleanroom operation?
What airflow speed is recommended for cleanroom operation?
What is the primary reason for changing HEPA filters in a cleanroom?
What is the primary reason for changing HEPA filters in a cleanroom?
Which part of cleanroom attire is typically used to prevent contamination from saliva?
Which part of cleanroom attire is typically used to prevent contamination from saliva?
What is the role of a raised floor in cleanroom operation?
What is the role of a raised floor in cleanroom operation?
What is a common source of contaminants in a cleanroom environment?
What is a common source of contaminants in a cleanroom environment?
Study Notes
Microcontamination Overview
- Microcontamination refers to foreign materials or energy that negatively impact a product or process.
- Examples include solid particles, ions in liquids, molecular gases, vibrations, electromagnetic interference, and electrostatic discharge.
Microcontamination Control in Wafer Fabrication
- Critical measures include maintaining a cleanroom environment, utilizing ultra-pure water, and implementing electrostatic discharge (ESD) control.
Effects of Microcontamination
- Direct impact on product or process yield, performance, and reliability.
- Particle-related failures can cause short circuits or ESD damage to devices.
Yield and Microcontamination
- Yield (Y) is exponentially inversely proportional to both the area of the product (Y = e^-AD) and defect density.
- Larger product size increases susceptibility to contamination; smaller sizes enhance yield in a cleaner environment.
- Poisson's principles indicate yield is heavily influenced by microcontamination control measures.
Particulate Contaminants
- Contaminants size ranges from 0.01 to 100µm, typically invisible and airborne due to their lightness.
- In comparison, human hair ranges from 75-100µm, while visible particles are approximately 35µm.
Cleanroom Environment
- A cleanroom controls airborne particle concentration and has designated clean zones.
- Cleanroom class is defined by the number of particles (>0.5µm) per cubic foot, with Class 1000 having less than 1000 particles.
Cleanroom Operation
- Key components include filtration systems and airflow control.
- Filtration techniques encompass gravity, inertial impaction, direct interception, electrostatics, and diffusion.
Filtration Efficiency
- HEPA filters achieve 99.997% efficiency at 0.3µm, while ULPA filters reach 99.999997% efficiency at 0.12µm.
- Filtration maintenance is crucial, with filter changes indicated by decreased airflow speed.
Airflow Control in Cleanrooms
- Recommended airflow speeds are between 70 to 110ft/min (0.35 to 0.45m/s).
- Laminar flow systems combined with raised floors help eliminate standing air.
Contaminants from Personnel
- Human activity is a significant contamination source; skin, sweat, and saliva contribute to particle contamination.
- Cleanroom protocols require specific apparel like face masks, hairnets, jumpsuits, booties, and gloves to minimize contamination.
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Description
This quiz covers essential concepts of microcontamination, particularly in the context of wafer fabrication. It highlights the various forms of micro contaminations such as particles, ions, and energy interferences, along with the control measures like clean rooms and ultra-pure water. Test your knowledge on how to maintain the integrity of processes in semiconductor manufacturing.
