residualgas

Residual gas refers to the small amount of gas that remains in a vacuum system after it has been pumped down. Even in a high vacuum, there is still a non-zero pressure of gas molecules present. This residual gas can originate from various sources, including outgassing from the vacuum chamber walls, leaks in the system, or the imperfect pumping action of the vacuum pumps.

The composition and pressure of the residual gas are important factors in many scientific and industrial applications. For example, in semiconductor manufacturing, the presence of certain residual gases can contaminate the surface of wafers, leading to defects in the fabricated devices. In particle accelerators, residual gas molecules can collide with the accelerated particles, causing them to scatter and lose energy.

Understanding and controlling residual gas is crucial for achieving and maintaining desired vacuum levels. Techniques such as bake-out procedures can be used to reduce outgassing from chamber materials. Leak detection is essential to identify and repair any ingress of air or other gases into the system. The choice of vacuum pumps also plays a significant role, as different pumps have varying capabilities in handling different types of gases and achieving lower pressures. Analyzing the residual gas composition using mass spectrometry can provide valuable insights into the sources of contamination or leaks.