Bourdon tube gauges are commonly used for measuring pressure, but this doesn’t mean that a bourdon tube gauge is the best pressure measurement solution for all semiconductor applications. As highlighted in a respected 2018 trade magazine article, a mini diaphragm semiconductor gauge is designed specifically to withstand aggressive media and corrosive environments found in some ultra-high purity applications.
Bourdon tube gauges are popular in the semiconductor industry for a number of reasons. Readily available and easy to use, they are a cost-effective pressure solution for most high purity (HP) and ultra-high purity (UHP) applications. However, these upsides do not outweigh the potential downsides when used in applications that call for highly reactive gases.
The director of sales at Valin Corporation, a leading distributor of products for HP applications, wrote about this topic in “Solving the Problem of Bourdon Tubes” — published in the September 2018 issue of the journal Solid State Technology. Here are some highlights from that article.
Corrosion: A Weakness of Bourdon Tubes
Many semiconductor processes today require the use of highly aggressive gases for etching and deposition. As these ultra-pure gases travel from their tanks to the process environment, they can pick up moisture from ambient air if there are leaks anywhere in the gas delivery system. When highly reactive gases meet water, they become corrosive acids.
Bourdon tubes, which are normally made of a very thin un-passivated metal (copper alloy or stainless steel), work by flexing. This movement creates micro fissures over time. These barely detectable crevices are not a problem in many industrial applications. However, when microscopic crevices come into contact with corrosive acids, they quickly become major breaches. Pretty soon, the gauge fails.
A Solution for Semiconductor Gauge Corrosion
If a semiconductor gauge doesn’t use a bourdon tube for measuring pressure, it eliminates a major source of leaks. Here is where WIKA’s UHP mini diaphragm pressure gaugehas a distinct advantage. The flexure – a diaphragm – is made of Inconel® 718, a highly corrosion-resistant super alloy. The 316L stainless steel case is fully passivated and electropolished, and the all wetted parts are sealed from the atmosphere.
WIKA’s Mini Diaphragm Gauges
WIKA manufactures two models of mini diaphragm gauges that are ideal for UHP processes in the semiconductor industry. Additional advantages of these pressure gauges:
- Nominal sizes of 1″ (Model 432.10) and 1.3″ (Model 432.15), ideal for applications with limited space
- Ability to withstand gaseous, liquid, and corrosive media up to 160 psi
- Helium leak testing to meet purity standards
- Compliance with both SEMATECH and SEMI standards
Read the Solid State Technology article for more details on how the mini diaphragm gauge solves the problem of corrosion that plague bourdon tube gauges. Then contact WIKA’s experts to see whether this innovative, high-quality semiconductor gauge is right for your UHP applications.