Chapter 1
What is yield in semiconductor manufacturing?
Yield in semiconductor manufacturing is an important indicator that shows how many of the manufactured products or wafers meet the required quality standards.
When yield decreases, fewer good products are produced for the same volume, leading to losses in materials, equipment operation, energy, and time. Therefore, in semiconductor manufacturing, it is important not only to detect defects but also to understand and improve process conditions that lead to defects.
The final examination alone cannot determine the cause.
While final inspections can identify defective products, the results alone may not allow us to determine "at which process," "when," and "what changed."
To investigate the cause, it is important to measure the changes in state that occur during the manufacturing process and record them as data.
In improving yield, it's important not only to "find the cause after a defect occurs," but also to consider "whether the state changes that lead to defects can be detected during process."
Chapter 2
Reasons why yield is difficult to improve
Even if it's known that yield is declining, improvement cannot be made unless the underlying process or conditions causing the problem can be identified. This is especially true in semiconductor manufacturing, which involves many process, where cause and effect can be quite distant.
The final test only provides the "results."
Even if a defect is identified, it may not be possible to track down which process caused the change in state that led to the defect.
It is difficult to capture changes in state during process.
The condition of the equipment and wafers changes during process. If the necessary conditions are not measured, it is difficult to confirm the changes later.
Multiple conditions change simultaneously.
Quality is influenced by multiple factors, not just one, such as equipment condition, processing conditions, and temperature. Recording process data is crucial for identifying the root cause of problems.
There is a time lag between cause and effect.
Changes that occur during process may only manifest as defects in subsequent process or during final inspection. Data that allows you to check process status over time can provide clues for investigating the cause.
Chapter 3
Relationship between temperature unevenness and CMP/polishing process
In semiconductor manufacturing, temperature conditions are relevant to process states in various stages, including crystal growth, diffusion, CVD, and heat treatment. Even in CMP and polishing process, measuring temperature changes and temperature variations during polishing provides clues to understanding the processing state.
In the CMP and polishing process, the state of the work is difficult to see.
While inspecting a wafer after polishing allows us to confirm its final state, it can be difficult to determine what changes occurred during the polishing process solely through post-completion inspection.
Therefore, one approach is to measure temperature changes during polishing in real time and use that information to check the processing status.
Temperature at a single point cannot capture temperature variations.
If you measure at only one location, you may not be able to capture temperature differences occurring elsewhere on the polished surface. It is important to consider the measurement method and location depending on the range of temperature you want to check.
Category
Measure temperature changes
Measure the temperature inside the polishing process to understand what changes occur during processing.
Visualize
Understand temperature variations
Depending on the object being measured and the measurement method, we can confirm temperature differences that cannot be seen with a single-point measurement.
Compare
Compare with process conditions
We compare temperature data with processing conditions and quality results to use as material for investigating causes and improving process.
Temperature measurement of semiconductor wafer surface polishing
Chino is proposing a measurement method for the semiconductor wafer surface polishing process to understand temperature changes and temperature variations during process.
View semiconductor wafer surface polishing temperature measurement
Chapter 4
Why real-time monitoring helps improve yield
Being able to monitor process in real time allows you to understand the changes occurring during processing, rather than simply waiting for the final inspection results.
Early detection of signs of abnormality
Knowing the normal temperature fluctuations makes it easier to notice any unusual changes.
Record process data chronologically.
By recording the temperature history, if a quality problem occurs, it becomes possible to later check what kind of changes occurred during the manufacturing process.
Compare quality results with process status.
By comparing temperature data with quality results, we can examine the relationship between specific temperature changes and quality status.
Compare before and after the improvement.
Comparing temperature data before and after changing process conditions provides information to confirm how process state has changed as a result of the improvement measures.
Learn more about recording and monitoring.
Chapter 5
Use a temperature measurement system to understand process status.
To utilize temperature data for yield improvement, it is important not only to measure temperature but also to record it, monitor its changes, and make it available for comparison with quality results and process conditions.
| Role | Confirm | The purpose |
|---|---|---|
| Measure | Measurement target, measurement location, temperature range, measurement method | Understand the temperature state during process. |
| Record | Temperature history, measurement cycle, storage method | To allow for checking process status later. |
| Monitor | Normal state, changes during abnormal conditions, real-time display | Make it easier to notice changes during process. |
| compare | Processing conditions, temperature data, quality results | Use as material for cause analysis and improvement planning. |
Temperature data alone does not determine the cause of yield.
Since yield is influenced by multiple factors, temperature data alone cannot be used to determine the cause of defects. Temperature is just one piece of information for understanding process state, and it is important to check it in conjunction with equipment conditions, processing conditions, and quality results.
Considering semiconductor measurement as a whole
In semiconductor manufacturing, various measurements are taken at each stage of process, including not only temperature but also dimensions, film thickness, defects, electrical characteristic, and temperature/humidity. For yield improvement, it's crucial to consider not just one measurement value, but to combine and analyze all the necessary process information.
Chapter 6
Things to consider when planning temperature measurement
When considering temperature measurement in process such as CMP (Chemical Polishing) and polishing, it is important to first clarify what you want to measure.
| Check items | Content to organize |
|---|---|
| Target process | Where in the CMP, polishing, or other process will the measurements be taken? |
| What to measure | What temperature do you want to check: the wafer, the polishing surface, the equipment, or the surrounding area? |
| Phenomenon I want to confirm | Temperature rise, temperature variations, changes over time, changes during abnormal situations, etc. |
| measurement speed | How often do you want to check for changes? |
| Record | Is real-time display sufficient, or is it necessary to keep a history? |
| Comparison with quality data | Which quality results or process conditions do you want to compare the measured temperature to? |
Further reading
Review the document to understand the concept of yield improvement.
You can find detailed information in the PDF document regarding hypothetical causes of low yield, the relationship between temperature variations and CMP/polishing, the necessity of real-time monitoring, and Chino's temperature measurement system for polishing process.
The path to improved yield in semiconductor manufacturing
process This document summarizes strategies for improving yield from the perspectives of monitoring internal conditions and measuring temperature.
You can view an overview on the webpage, and then see the detailed information in the provided documents.
FAQ
FAQ
What is yield in semiconductor manufacturing?
This is an indicator used to see how many of the manufactured products or wafers met the required quality standards. To improve yield, it is important to understand not only the results of defects but also the conditions during process.
Can measuring the temperature reveal the cause of the yield problem?
Temperature alone cannot determine the cause. Temperature is just one piece of information used to check process conditions. By checking it in conjunction with processing conditions, equipment status, and quality results, it can be used to investigate the cause and consider improvements.
What are the benefits of measuring temperature uniformity?
This method allows you to check temperature differences within the measurement target, which are difficult to grasp from the temperature of a single point. By comparing the temperature distribution and changes over time with process conditions, it can be used as information to understand the state of the system.
Can temperature be measured during the CMP/polishing process?
Depending on the object being measured and the equipment conditions, we can consider methods for measuring temperature changes and temperature unevenness during the polishing process. Chino proposes temperature measurement in the semiconductor wafer surface polishing process.
View semiconductor wafer surface polishing temperature measurement
What is the purpose of real-time monitoring?
The purpose is to check temperature changes occurring during process on the spot and identify any differences from normal conditions or signs of abnormalities. The recorded data can also be used later to investigate the cause.
I would like to consult about temperature measurement in semiconductor manufacturing.
Based on factors such as the CMP/polishing process, the object to be measured, the temperature range, the phenomenon to be measured, and whether recording and monitoring are required, we can determine the temperature measurement method best suited to your application.
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