Since opportunity cost is always a comparison of the path chosen to the path that was not chosen, we will compare two hypothetical systems whose COO on a per wafer output basis is identical, but its granularity is different.  Granularity will tend to go up in integer values.  Let us suppose a system whose out put is equal to one unit of capacity, (i.e., 2000 wafers per month) and another whose out put is equal to two units of capacity (i.e., 4000 wafers per month).  If the need is for one unit of capacity, then if the COO is the same and the more granular system is the clear choice.  If it is two units of capacity then the choices are equal.  However what happens when it is three units of capacity; then four; then five? Capacity needs often develop in incremental steps over the long term instead of in immediate doublings. The investment in the “granular approach” is obviously the more appropriate forward-thinking plan. As needs eventuate, so that capacity can be adjusted to market needs at the lowest possible cost in capital spread over time.

But wait. Everyone knows that we all need to be data driven. We need to have the data that successfully makes the argument that the innovation is working successfully. It is sort of a “chicken and egg” dilemma. If we had the data, then it’s been done and if we don’t have the data we can’t proceed. Ultimately, we have to start someplace. The question is always “where?”

First, we need to start with a better understanding of nature. When all else fails, we as professionals should be thinking through what nature wants to happen. The study of chemistry and the laws of thermodynamics in the discipline of physical chemistry can, and should, instruct us and provide the bridge that we build to cross from no data to innovation; and from innovation, to new data that can provide that lower cost of ownership so vital to the companies that must be creative. Ultimately, it is that creativity that helps to foster success.

As the semiconductor industry has packed more and more functionality and speed into ever smaller chips (here one almost always must refer to Moore’s Law well know to those in the industry), the size and cost of the packaging of the chip has made necessary the creation of new types of wafer processing, which is needed to do wafer-level chip scale packaging.  In this specific technology, photolithographic processing is used so chip outputs and inputs can be repositioned, so as to adapt to interconnect circuitry directly without the intervention of a typical pin out type package.  In this case the chip is “rewired” and “bumped” so that it can be “flipped and bonded” directly to the chip interconnect circuitry.  Such rewiring and bumping is accomplished on the finished device wafer prior to singulation of the wafer into chips.

While the patterning concept is identical to that required to make the chip itself in practice, the geometries are far larger and the need for organic insulating film more prevalent than in the creation of the chip.  This means that the spin cast films are much thicker and there is far more effluent of material leaving the wafer during the required “bakes” done in the thermal modules of the requisite tools.  These thicker films require the following considerations in the design and implementation of the tool.

• The cost of the process must be kept low, thus requiring tools with a low COO.
• The spin cup must be designed to handle thicker films and capable of modulating spin exhaust conditions on a step-by-step basis throughout the process recipe.
• The higher viscosity resists that are used to spin the thicker films means pumps must be geared to accomodate those viscosities.
• The higher viscosity resist requires that the dispense height be preferably programmable rather than adjustable so that it can be varied during the dispense.
• The much thicker films evolve far more solvent and other effluent requiring that the effluent be directed away from cold surfaces where it can condense and require frequent bake module cleaning, or create defective films owing to effluent reflux.

While FEOL tools may be utilized in BEOL, their high cost can be prohibitive, and their performance while tuned to the FEOL is not appropriate to the BEOL provider.

There are some obvious and immediate COO issues that come to mind when used equipment, sometimes more respectfully referred to as “legacy” equipment is purchased as opposed to new equipment. They include:

• Very short warranty. Used or legacy equipment typically has a 30 to 90 day warranty, whereas today’s new equipment will often have a two-year warranty on components and one year on labor.
• Availability of spares. Used equipment, some of which was built up to 30 years ago, is becoming more and more difficult to support as the electronic control means are often no longer in production. While this issue is mitigated when new controls are implemented on old platforms, however this adds to the overall cost.
• Foot print issues. Equipment made before the advent of process stacking, typically done on the thermal modules, occupies more than twice the space as modern tools with Stacking. Used equipment that has stacking capability is often more expensive than new tools with stacking.
• Installation Costs. Frequently it can cost as much to install a used tool as it cost to buy it. That is not the case with new equipment, where installation costs and facility costs are low.

In addition to the direct cost factors noted above, there are more subtle factors that come into play. Including:

• Process support. New tools come with factory process support not typically available in used tools.
• Software support. New tools can be “tweaked” to meet specific customer requirements, whereas used tools typically are not available with ANY software support or modification.
• Capability to meet new process requirements that did not exist at the time of the design and manufacture of the used tool. Such factors as multiple movable dispenses, high reliability robots, hot plates designed to handle thicker photoresist films typically used in special purpose photolithography.
• A great deal of the used “track” equipment was built before the advent of Semi Safety Standards and is difficult, if not impossible, to render safe.

The photoresist process equipment available today is low in cost and high in functionality and reliability. It can be tailored to the specific needs of the very specific customer who buys new and not used.

The aspects (solid dots below) and the responses (open dots below) to COO issues are:

• The cost of the Bill of Materials (BOM) of the tool.
  • Employee identical hardware throughout the product line to improve economy of scale.
  • Minimize non-productive hardware, sensors and interconnect complexity.
  • Do not compromise on component quality, minimize the number of components.

• Minimize Tool Footprint
  • Stack processes where it makes sense to do so
  • Integrate wafer handling and processes to eliminate wasted space

• Maximize Reliability (note the very same responses to minimizing BOM costs improve reliability a clear Win-Win.
  • Employee identical hardware throughout the product line to improve economy of scale. (Enables testing and long term improvement)
  • Minimize non-productive hardware, sensors and interconnect complexity. (components that are not there cannot fail)
  • Do not compromise on component quality, minimize the number of components. (The highest quality components fail less frequently)

• Minimize consumption of materials cost. (Things like photo resist, solvents, gases, etc.)
  • Improve tool functionality while lowering BOM cost
  • Creatively work with customers to take advantage of improved tool functionality.
  • Use software to improve functionality as well as hardware. Software has zero replication cost.

• Increase Tool Throughput
  • Provide wafer handling capability at low cost that balances process times with minimum handling overhead time. Provide smart robotics capability.

Use “Small Grain” tools. By this we mean tools that can be provided in small increments of production while at the same time minimizing COO and Investment in absolute terms. All of the above items support this Aspect.

Now look at the Global Semiconductor Industry and the rise and subsequent consolidation of the Foundries that now dominate the latest mass production semiconductor technologies. There are three possibly four left standing, TSMC, Global Foundries, Samsung and perhaps Intel will enter the battle. The risks of technological advance in the manufacture, as opposed to design, of semiconductors are being born by the foundries. Their hard earned and costly manufacturing skills will be generally available to all who pay the price and have the manufacturing volumes that justify the costly tooling and sustaining engineering.

What of those, who for good reasons of their own, will not or cannot utilize the giant foundries. Such companies will use their own creativity and drive to gain a market advantage owing to their expertise in both designing and building their chips. Such companies will need to find ways to lower their manufacturing costs by effectively lowering the cost of ownership of the tools of production.