What Does It Take To Build A Successful Multi-Chip Module Factory?

When it comes to multi-chip module (MCM) manufacturing, fan-out wafer-level and fan-out panel-level packaging have received a lot of coverage recently. Every week, it seems like there is an announcement about “Company XYZ” moving their products into the fan-out wafer-level packaging (FOWLP) or fan-out panel-level packaging (FOPLP) space. But these moves come with challenges that didn’t exist in the advanced packaging assembly space years ago. And it’s these challenges that today’s MCM manufacturers need to address.

Consider this: at the most ambitious panel manufacturing facilities, masking layers may now number a dozen or more layers. Couple that with the fact that there may be more than 60 days of cycle time at some FOWLP facilities, and it becomes clear that the issues MCM factories need to address are looking similar to the issues front-end (FE) fabs faced in the 1980s.

Back then, FE operations drove many of the requirements — from factory automation to data collection and analytics — that we take for granted in today’s semiconductor industry.

The reasons why defect and yield management systems were important to fabs in the 1980s are the same reasons defect and yield management systems are needed now at MCM factories. This holds true for die-first fan-out wafer-level manufacturing and die-last fan-out panel-level manufacturing.

When it comes to FOWLP manufacturing, the operational processes are similar to the operational processes used in semiconductor manufacturing, with lithography, film deposition and etching all playing roles. The two manufacturing environments have several common steps, film etching and polishing being the most obvious. Much like the FE, these MCM tools need dynamic controls and run-to-run management in order to properly function, day in and day out. These facilities can leverage the lessons that have been learned from decades of excursion events and ever faster yield ramps in FE fabs by including integrated metrology defect and yield systems during the initial MCM facility build out.

However, there is at least one difference. Unlike a FE factory, a FOWLP manufacturer requires access to product performance data from both upstream and downstream sources. FOWLP manufacturers need the product traceability of their incoming chips and outgoing modules to isolate issues when it comes to their operations. A FE facility has no need for this, but this additional data is key to successful FOWLP manufacturing.

For both FE fabs and MCM manufacturers, how a factory avoids or embraces defect and yield management significantly impacts revenue. After all, yield loss in both FOWLP and FOPLP manufacturing can negatively affect revenue and disrupt supply chain deliveries. While these are two perennial challenges of the semiconductor industry, they are on everyone’s mind in the era of COVID-19.

Pandemic disruptions or not, losses at any point in the MCM-building process can cost a manufacturer: 1) the operational cost of building a module, 2) the limited capacity lost due to making a nonfunctional module and 3) the cost of good die committed to the module up front.

Given the accelerating needs in the multi-chip assembly space, the pressures for a successful start up and ramp up to production for FOWLP facilities are probably greater than those placed on FE factories decades ago. The successful multi-chip module companies are going to be those that can devote time and resources to manufacturing yield analytics utilizing the latest techniques and products in the factory control and yield management spaces. By combining solid yield analytics and data, these manufacturers will be powering smarting factories and a better bottom line.

Fig. 1: Using yield analytics and consolidated data to power your factory can increase the bottom line.

With over $3 billion set to be invested in MCM manufacturing facilities over the next five years¹, there is a lot at stake for FOWLP and FOPLP manufacturers. As we’ve seen across the semiconductor industry, the manufacturers that can deliver the highest yields consistently will reap rewards for years to come. Data integration coupled with the right analytics software will ensure that your factory will be successful.

[1] Sources: Revenues Yole’s Fan-out packaging 2020, CapEx: Yole’s Equipment and Materials for FO Packaging 2019, Semi Report 15DEC2020 Semiconductor Equipment Consensus Forecast – Record Growth Ahead