The challenges of automating a semiconductor fab

Perhaps more than other industries, semiconductor manufacturing is highly automated. The reasons are the same as in any other industry that seeks automation: Improve quality consistency , increase production output, and reduce manual labor, thereby reducing sources of error.

In semiconductor manufacturing, however, there are some unique technical challenges that set it apart from other industries and are clearly evident in the choice of automation technology components.

These include:

  • Miniaturization

The cleanroom environment required for semiconductor manufacturing is very expensive per square meter. Therefore there is a strong drive to reduce the machine size and consequently the size of all used sensors and other automation components.

The high cost of the cleanroom is by the way also another reason to reduce the role of personnel in the process. This refers not only to personnel costs, but also to the cost of the increased effort required to maintain the cleanroom’s air cleanliness. After all, people are responsible for 75% of particle contamination in cleanrooms.

This brings us to the next challenge:

  • Cleanrorm Environment

When selecting automation technology, it must always be ensured that the cleanroom environment is not contaminated. Therefore, mainly non-contact technologies are used, where there is no abrasion and thus separation and distribution of particles in the air.

Other extreme environment conditions

Semiconductor manufacturing often involves special environmental conditions, such as:

  1. Liquid or gaseous chemicals that can corrode various standard sensor housing materials. Therefore, sensors with special housing materials or coatings such as PTFE or PEEK are often used in semiconductor manufacturing.
  2. The vacuum chamber in which the sensor is vented must be controlled, and the sensor must not expand destructively due to the enclosed gas.
    In addition, the material of the housings is important here for another reason. Vacuum process chambers are designed to provide absolutely controlled environments for manufacturing processes. Many materials outgas in a vacuum and thus contaminate the environment with unwanted particles. This outgassing must be prevented by using certain housing materials.
  3. High temperatures. Semiconductor manufacturing processes often take place at (for automation components) extreme temperatures that the components must withstand.
  4. High pressure, e.g. for sensors in valves.

Switching / measuring speed of the components

APC (Advanced Process Control) is a method for shortening the time between the collection of SPC (Statistical Process Control) data and the application of process corrections. This means that instead of time-consuming external measurement procedures, the focus is on so-called “in situ” measurement procedures. Process variables must therefore be measured in real time or near real time to close the APC loop in less time.

In many cases, sensor applications in semiconductor manufacturing require some very unique mechanical properties and/or increased performance that ultimately require custom sensor solutions. You can read examples and further details about customized sensors in the semiconductor industry in >>this article<<.
Due to the small number of such customized sensors, the costs per sensor can be higher than that of “standard” components. However, the possibly higher costs for automation components are usually quickly recouped by the space savings in the cleanroom or improved output and process quality.

Ultimately, the aim is to achieve a positive return on investment by ensuring that the savings from automation far exceed the costs of automation.

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