Onshore Silicon for Long-term Supply Security: Foundry Selection for Military Applications

Kirk Peterson, CFD Foundry Manager, ON Semiconductor

Developing advanced electronics systems for the U.S. military presents a number of challenges for original equipment manufacturers (OEMs). In particular, military applications are subject to increasingly stringent requirements for domestic design, production and verification, while also requiring technology availability over long time periods. First, there is the need to deliver often highly complex designs to stringent and demanding specifications, not only with respect to performance and functionality, but also in terms of reliability in harsh or extreme operating environments. At the same time, military applications require long-term support—including the assurance of supply of the underlying technologies. From a national security perspective, there are significant implications, ranging from ensuring data security throughout the design and production process to potential requirements for personnel clearance. In addition, companies involved in designing military applications must be able to create a viable business model while addressing all of these requirements, even if the target application is likely to be manufactured in relatively low volumes.

The stringent criteria that military electronics suppliers must meet are even more severe when it comes to application-specific ICs (ASICs) and systems-on-chip (SOCs). These devices are at the heart of a growing number of advanced military applications and are often critical to delivering the complex operations required. Ultimately, they play a key role in ensuring military advantage in the field. Because of this, companies that design and supply products for military use must carefully consider the foundry partners to whom they outsource their IC fabrication.

ITAR Compliance

For military applications, it is absolutely essential to establish a reliable, secure supply chain that incorporates the complete path for IC design and reticle and silicon manufacture. In many cases, the U.S. government will dictate a "front-to-back" onshore handling requirement that includes everything from prototyping to fabrication, packaging and final test. However, simply using a U.S.-based foundry partner is not enough. It is also essential to verify that the foundry meets all of the relevant government requirements.

First, there is the need to establish that the foundry is fully compliant with the U.S. government's International Traffic in Arms Regulations (ITAR) requirements. Enforced by the Department of State, ITAR comprises a set of regulations designed to safeguard U.S. national security by controlling the import and export of defense-related products, services and information. Interestingly, in recent years, the scope of ITAR has expanded to cover technology in other areas, including, for example, satellites and launch vehicles. Regardless of the target application, ITAR compliance necessitates well-documented and regularly audited processes covering export management systems to ASIC design and manufacturing.

Trusted Status

In addition to ITAR, there have been increasingly stringent security requirements applied to the onshore manufacture of semiconductors for military applications.

The National Defense Authorization Act of 2009 specifies the need to "identify vulnerabilities in the supply chain of each program's electronics and information processing systems that potentially compromise the level of trust in the systems." This includes an "assessment of methods for verifying the trust of semiconductors procured from commercial sources." This section of the Act implements strategies that "increase the use of trusted foundry services." The Act goes on to define such services as the development and manufacture of ICs for critical defense systems.

In line with the National Defense Authorization Act of 2009, the National Security Agency has established the Trusted Access Program Office (TAPO) to provide a path for the Department of Defense (DoD) and the Intelligence Community to have guaranteed access to "trusted microelectronics technologies for their critical system needs." TAPO provides the DoD and the Intelligence Community a path for:

• Guaranteed access to trusted foundry suppliers for mission applications.
• Ability to fabricate classified designs up to the secret level.
• Low-volume customers to access leading-edge technology.
• Quick turnaround times for prototyping and production.
• Technology support through industry partnership.

For a foundry to achieve trusted status and, thus, be eligible for the TAPO program, the company must demonstrate that it is abiding by a variety of security requirements. How strict these requirements are depends on the level of security classification, and, in general, they cover:

• Chip database media.
• Metal masks.
• Back-end (after first metal).
• Finished product.
• Post processing.

Table 1 illustrates the general security guidelines for what is and isn't classified with regards to trusted foundry status.

Table 1. Trusted Foundry—Classification Status of Wafer Fabrication

Type	Classification Status
Data	CLASSIFIED
Databases (electronic media)	CLASSIFIED
Masks up to 1st metal	UNCLASSIFIED
Individual masks from 1st metal to passivation	UNCLASSIFIED
Any combination of >33% of all back-end layers or >4 masks (whichever is less)	CLASSIFIED
Final passivation layer	UNCLASSIFIED
Visual access of masks at 1X visual magnification	UNCLASSIFIED
Wafers processed up to 1st metal exposure	UNCLASSIFIED
Wafers processed above 1st metal exposure	CLASSIFIED
Visual access of wafers at 1X visual magnification	UNCLASSIFIED
Visual access of wafers at or above 5X visual magnification at 1st metal layer and beyond, or if viewed in groupings of >100 resistors, or if mosaic pictures of multiple transistors are created	CLASSIFIED
Finished product	CLASSIFIED
Scrapped material after 1st metal	CLASSIFIED

The restrictions cover everything from photography—at no time can pictures be taken of a product and saved during the manufacturing process, when it is finished or during post processing without prior approval from the government—to personnel clearance (PCL) for operations that support classified wafer fabrication and storage. In the case of the latter, all classified products (including reticles and wafers) must be locked in Defense Security Service (DSS)-approved storage containers when not being actively processed. There must be a clear "chain of custody" throughout the manufacturing process, and the organization will be required to have personnel with SECRET PCL. In addition, any product requiring post processing and testing will require the use of cleared personnel and adherence to the DSS requirements in areas such as storage, inventory and marking.

Finally, trusted foundry status also places stringent criteria on IT networks. Typically, these will be physically separated from those associated with normal commercial fabrication activities and must be capable of interfacing with the government Secret Internet Protocol Router Network (SIPRNET). Such networks enable the transfer of classified information and databases between cleared government contractors and the trusted foundry.

Beyond Compliance

Of course, being able to prove ITAR compliance and demonstrate trusted foundry status is completely irrelevant if the foundry cannot provide the necessary technologies and services. Availability of suitable processes is clearly critical, especially as the offshoring of many other applications and processes has reduced the number of onshore fabs capable of working at 0.35μm and below.

Figure 1. Process Platforms for Military Designs

Figure 1 illustrates the types of custom foundry mixed-signal platforms that are currently available through U.S.-based onshore facilities. These platforms include an industry-compatible 0.18μm CMOS process technology targeted at low-power, highly integrated digital and mixed-signal SOC devices that are ideal for new and emerging military applications.

Suitable for SOCs requiring up to 500K gates, this process features between four and six levels of metal and allows designers to integrate 1.8V core voltages with 3.3V input/output (I/O). Options for integrated passive devices include resistors and nominal [1.0 femtofarad per micron squared (fF/μm²)] and high-value (2.0 fF/μm²) stackable metal-insulator-metal (MIM) capacitors. A design kit offers comprehensive core, I/O and memory libraries with memory options including 64 Kbit synchronous single-port and dual-port static random access memory (SRAM) and 64 Kbit VIA-programmable read-only memory (ROM).

But, again, a suitable selection of process geometries is only part of the story. Availability of specialty services such as advanced die stitching and shuttle services for prototyping should also be evaluated, as should availability of intellectual property (IP). Access to silicon-proven synthesizable IP blocks for interface functions such as Ethernet media access controllers (MACs); Universal Serial Bus (USB), Peripheral Component Interconnect (PCI) Express or blocks for microcontrollers; timing generators; and memory controllers, for example, can significantly simplify the design and development process and greatly reduce the need for respins.

Finally, no discussion of onshore foundry services and long-term supply security is complete without reference to process longevity. Military products have lifetimes that are often measured in decades, and the implications and costs associated with component obsolescence and end-of-life (EoL) can be severe. This situation is exacerbated by the fact that the majority of military designs are less likely to be implemented in cutting-edge processes that are in their infancy and, therefore, likely to have a number of years of life ahead of them. It is essential, therefore, that the evaluation criteria for a suitable foundry partner should also take into consideration the organization's process longevity history and their stated commitment to future support.

Even More to Onshore

While all of the issues covered here are relevant to military applications, there are a number of reasons why commercial applications can also benefit from onshore custom foundry services.

High on this list is the protection of valuable IP. As many companies have learned, choosing a low-cost offshore foundry partner does not always guarantee such protection, and many more are nervous about the offshoring trend for this reason. Dealing with an onshore partner who can demonstrate commitment to IP protection through strong military capabilities is increasingly attractive to such companies.

Finally, outside of the issues of technology, support, services, compliance, IP protection and supply security we should not forget that there are other factors that can tip the balance in favor of the onshore route. From a logistics perspective, there may be the opportunity to reduce shipping costs and lead times, while also creating strong working relationships, minimizing misunderstandings and ensuring that potential problems are quickly rectified.

About the Author

Kirk Peterson manages the ON Semiconductor North American custom foundry group, with more than 28 years of experience in engineering, marketing and business development. He began his career at Analog Devices and Intel before joining ON Semiconductor. Kirk graduated from Idaho State University with a B.S. in mathematics with computer science emphasis. He attained the Project Management Institute's Project Management Professional (PMP) status in 2005 and is a certified black belt in Lean Six Sigma. You can reach Kirk Peterson at kirk.peterson@onsemi.com or 208-233-4690.

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