The Business Problem
The manufacturing process of memory chips involves around 1,500 steps that need to be performed in sterile conditions to avoid specks of dust from damaging the wafers. However, damages occur nonetheless. The quality issues that arise, scratches, holes etc., are often microscopic and near-invisible to the human eye!
The manufacturing environment is home to a multitude of machines, pipes and parts. These wear out, break down or start dripping. Detecting these issues in an early stage is crucial. Engineers are usually responsible for maintenance. However, even the most highly skilled engineer can miss early indicators that something is wrong.
Inherently, the process of manufacturing memory chips has a lot of potential for error. Relying on human vigilance to identify quality issues and mechanical problems was costing Micron Technology a lot of money, on average $250,000 per hour of downtime (Micron Technology).
This particular business problem is well-suited for AI solutions. The problems are clearly defined, measurable and there is enough in-house data to use Machine Learning (ML) on multiple fronts with good accuracy. The solutions also work with smaller volumes of data, but the accuracy of the ML algorithm will not be as good. As more data is gathered, accuracy will improve.
Another major memory chip manufacturer (Intel) also implemented Machine Vision and Machine Learning algorithms in its wafer production process. A whitepaper on their approach states the following interesting conclusion:
“Similar technology can be used in many different industries-wherever machines capture images, regardless of the original use for those images.”
The ML algorithms are designed to detect anomalies in an earlier stage, with higher precision and frequency than its human counterparts. However, and this cannot be stressed enough, humans are still needed to interpret and act upon the alarms given by the system.
Micron Technology implemented Machine Vision technology into its photolithographic cameras as they etch the circuitry into the wafers. The technology scans for frequently occurring flaws and alerts the engineers whenever a flaw has been detected. Depending on the type of flaw, it takes somewhere between 15 seconds and 15 minutes before the alert is given.
The company’s Auto-Defect-Classification system (ADC) solves the problem of classifying every defect manually. The system makes use of deep learning (Opperman, 2019) to sort and categorise millions of flaws. A whitepaper by Intel explains the ADC system more in-depth.
To further drive the effectiveness and accuracy of AI, Micron implemented thermal imaging to monitor its manufacturing process. “Heat maps” of the factory environment under normal working conditions are overlayed onto a ‘digital twin’, essentially a digital copy of the factory environment. This map then provides a baseline to compare real-time infrared imagery of the factory. If the system spots an anomaly, i.e. irregular temperatures compared to the digital twin, the system sounds alarm.
Possibly the most surprising of the trio, an AI solution has been created to identify unusual noises within the manufacturing process. Similar to your car producing odd sounds, a machine making an unusual sound often indicates trouble. The AI system at Micron has been trained to spot irregularities in sound frequencies by converting sound to visual datapoints. To capture the sounds of individual machinery in a loud environment, audial sensors are placed close to machinery or pumps. Categorisation of sounds and potential causes is done by the engineers.
Benefits & Impact
Firstly, Micron Technology’s AI solutions have increased manufacturing efficiency and accuracy noticeably. Secondly, Worker safety has improved (Workers come into contact with extreme temperatures and harmful substances less frequently). Thirdly, AI solutions have freed up valuable time for the company’s engineers to focus their efforts elsewhere. Lastly, the implementation of AI solutions in the manufacturing process has spread out to other processes in the business, such as product demand forecasts, Increasing the accuracy by 10 to 20 %.
- 10% increase in manufacturing output
- 35% less quality issues
- 25% faster time to yield maturity
- Avoided millions of USD through early detection of machine breakdowns and quality issues
- Freed up time for engineers to focus their efforts elsewhere
- Increased worker safety
- Paves the way for AI solutions in other business processes
Accessibility and Requirements
The driving force behind the three AI solutions implemented at Micron Technology is data, lots and lots of data. The company collects petabytes of manufacturing data from over 8.000 sources and over 500 servers worldwide. This data is send to two environments of the open-source software program “Apache Hadoop” for data mining. Hadoop is designed for parallel processing of large data-sets, meaning that multiple datasets can be processed at the same time.
For Machine Vision over 2.000.000 images are stored in the Hadoop environment. For Acoustic Listening, Micron sends the relevant data to a GPU system to handle the massive workload of the complex machine learning algorithm in a swift manner. GPU’s can continue to accelerate applications by dividing tasks among many processers, allowing it to process the vast amount of data that is poured into the system.
Requirements for AI solutions
- Sufficient images and data on flaws, ‘normal’ sound frequencies and temperatures
- Deep learning algorithm (for classification of flaws for Machine Vision)
- A digital twin (for Thermal Imaging)
- Infrared cameras (for Thermal Imaging)
- Audial sensors (for Acoustic Listening)
- Apache Hadoop for data mining
- GPU systems
- Machine Learning algorithms