Applied's Module Approach Jumpstarts Transition to Copper

-- Semiconductor International, 11/1/1999

Applied Materials' (Santa Clara, Calif.) Equipment Process and Integration Center (EPIC) scored a significant success by catapulting a semiconductor device manufacturer into the copper world within a three-month window, compressing a process that could have taken years and millions of dollars.

Mosel-Vitelic Inc. (MVI), a Hsinchu, Taiwan, manufacturer of memory chips, needed to evaluate copper technology and approached Applied, supplying 64-Mb wafers processed up to the interconnect level. At the EPIC facility, which emulates a self-contained pilot line where customers can bring wafers to evaluate Applied's copper interconnect technology, the first step was simple adjustment of mask alignment marks to match the EPIC's ASML stepper to its MVI counterpart. Applied then carried out the first level of metal using the damascene process, and did electrical testing to ensure functionality. This was followed by another level of copper and bond pad aluminum, enabling packaging for reliability testing.

MVI's original requirements called for a one-good-die-yield. Applied not only met the parametric and transistor performance targets, but provided a yield that was, according to MVI, 'compatible with aluminum,' successfully telescoping a process that could have taken two to three years down to three months. Although MVI knew little about copper, it now has a clear picture of how copper can be implemented in its new chip designs -- and it did not have to invest heavily in capital equipment or development time.

Fig 1 Memory device processed through two levels of copper interconnect and aluminum bond pad in Applied Materials' EPIC facility. (Source: Mosel-Vitelic Inc.)

'MVI came to us in May,' said Sass Somekh, senior vice president at Applied's Office of the President. 'We started the wafers in June and delivered them on August 31st.' Somekh said Applied carried out all processes that would have been handled at a fab, including metrology, defect inspection, electrical tests and physical characterization. 'The wafers were then shipped back to MVI, who did the functional testing,' he said. 'Had they started from the beginning, they would have had to select equipment, await delivery, set it up, develop the process, and then fine-tune everything for production.'

Ching-Hwa Chen, MVI's Central Lab director, views the work done at EPIC as a transition for equipment manufacturers in providing value-added comprehensive process solutions. Chen said the work has allowed MVI to set its business direction, enabled a solid implementation timeline and made possible a much shorter time to market, as well as lower product cost. 'The program allowed the rapid evaluation of a very complex process flow without requiring us to characterize each step,' said Chen, adding that yields demonstrated on MVI devices exceeded expectations.

Applied's module approach began several years ago, when a customer reported problems in having equipment work together. Although the Applied etcher would etch the competition's metal, it could not etch the Applied metal as well. This resulted in Applied setting up a central Process Sequence Integration (PSI) group, to ensure equipment compatibility. From the beginning this effort was a success, with the PSI group acquiring considerable experience over the years in integrating sequential processes.

'What we found when doing this kind of integration,' said Somekh, 'is that we have the advantage of being able to modify the equipment, which the customer cannot easily do. There's a double benefit to this: we catch problems before we ship, and it allows us to optimize the product for integration. When the customer gets the equipment it is already integrated, and he doesn't have these issues to work out.'

To move from this to the concept of integrating an entire process sequence, only a small step was needed. As Somekh put it, 'If we're optimizing our equipment for the various steps in a sequence, why not offer it all as a module?' Work began two years ago, with shallow trench isolation and on copper interconnect. It now has culminated with a successful customer demonstration resulting in verified yields.

Somekh refers to the module concept as a 'paradigm shift.' As he puts it, 'There are two major industry drivers: One is to introduce technology quickly. Cycle time from going from one technology node to the next has compressed from three to two years. This is one way of doing it.' The second driver, he said, is cost. 'Development costs are high, and everyone's spending to develop the same process -- copper in this instance. The process module concept provides a way to reduce these costs.'

The reasoning is that if a company is able to buy a ready-made technology module, the only effort and expense involved lies in merging it to a specific process. 'Development costs are reduced,' said Somekh, 'and because we developed all the equipment in that module, we can optimize it for better performance. We're convinced that the module's overall yield and productivity is superior to just going out and getting equipment from different suppliers and then making everything work together. Because everything has been developed and optimized as a module, everything runs more efficiently.'

It should be noted the Applied approach works best with the equipment Applied knows best -- i.e., Applied equipment. No implication has been made that the module approach will replace overnight other equipment a device manufacturer might buy. Applied claims what it is providing is a baseline for the user to build upon. This baseline shortens time to market because it provides all the necessary knowledge and can be improved or used as is. In addition, it must be matched to each user's process, because every process is somewhat different.

Essentially, what Applied is offering is consulting services to assist in tailoring that baseline to meet individual application requirements -- different design rules, as well as matching it into the flow and interconnect.

Applied is betting future equipment purchases will be done this way. It is currently reorganizing the entire company to give customers the choice of buying process modules in addition to stand-alone equipment. Applied is shifting from its traditional set-up, with technology divisions such as PVD, CVD, and etch, to groups such as Interconnect, Transistor, Capacitor, etc., to align itself with the way it believes users would like to see these modules.