Wafer Yield in the Semiconductor Industry

Submitted by Sri Gavini
In a time where the cost of everything is on the rise, operators and decision-makers are more focused than ever on getting the most out of their particular process. This is particularly true for the semiconductor industry. It is critical to improve throughput and maximize yield during a time where costs can be harder and harder to predict. 

Wafer Yield in the Semiconductor Industry

What is yield exactly?

In the semiconductor industry, yield is defined by the ratio of all the wafers that are produced by the fab to the number of wafers that were introduced to it. Every wafer lost due to one factor, or another is a sunk cost for these fabs.  We can even break yield down even further in this industry, though.  There is wafer fabrication yield, wafer sort yield, and packaging yield.  All of these areas are opportunities for the yield of wafers to be lost.  The key is minimizing mistakes and complications to pave the way for the best possible yield of wafers. 

How is this done?

The first element to improving yield is through improving overall equipment performance by reducing any point of failures and removing legacy/old components. These old components are often the cause of failures that are core reasons that initiate the chain of other problems on the tools, specifically the pneumatic manifolds.  If the equipment is not as effective as possible, the yield will suffer. On these tools, pneumatic manifolds are often overlooked but they could be prime culprits in the tool underperformance. These pneumatic manifolds on the semi tools are often used in opening and closing the Slit Valve Doors (SVD), air piloting process valves, supplying air to the mass flow controllers, and various other critical processes at a certain pressure range and flow rates. Any discrepancy in the pressure and flow rate to the process can compromise the recipe of the process and is in direct relationship to the yield.

Generally speaking, the pneumatic manifolds we find in these semiconductor fabs can be up to 20+ years old. This is costly to maintain as replacement parts can’t always be obtained by the OEM and could be made obsolete by manufacturers as well. Operators must cross their fingers that what they’re buying second-hand on unapproved online sites is going to fulfill the need. Another option is to go through and replace manifolds with more current models. The issue here is the obvious cost and the time to replace associated with this approach. And with yield being tied so closely to cost, this just isn’t a viable solution for most.

Valin engineers are recommending upgrade kits that provide a drop-in, plug-and-play solution both electronically and mechanically.  These kits allow operators to isolate a valve on the manifold to repair it. They no longer need to shut down the manifold air supply, which can ultimately cause process chamber conditions to change. The manifolds remain the same in terms of form and function so there is no fabrication involved. 

We find that these upgrade kits not only eliminate Compressed Dry Air leaks (CDA) but ultimately reduce tool downtime.  I recently contributed an article to Semiconductor Digest Magazine where I discuss this issue and our solution in much greater detail.  I encourage you to take a look if you haven’t already. 

Just to illustrate my point, here are some of the more noticeable benefits of upgrading a pneumatic manifold with these kits:
  • Proven in the field with Fab testing
  • Quick, easy installation (less than 45 minutes)
  • Fit, form, & function remains the same
  • 150 million + valve cycle life expectancy
  • The power consumption of each coil is 0.8w and a switching time of 18 ms
  • Higher Cv (new valve .46 Cv compared to old valve .10 Cv)
  • Complete drop-in replacement kit
  • No fabrication or other items needed
  • Ease of valve replacement (1 self-contained set screw and embedded gasket)
  • No loss of gaskets and screw
  • Individual valve isolation for servicing
  • Fully warrantied manifold to keep tools operational for many years to come

Learn more about Valin's Pneumatic Manifold Retrofit Kits

Contact our team of semiconductor technical specialists at (855) 737-4716, or email our team at manifold@valin.com to learn more.