A comprehensive methodology to qualify the reliability of GaN products

A comprehensive methodology to qualify the reliability of GaN products 2 Introduction The industry takes the reliability of silicon power transistors for granted due to over thirty years of experience and continuous improvement. This longstanding experience has resulted in a mature qualification methodology, whereby reliability and quality are certified by running standardized tests. These tests originated from detailed work on the understanding of failure modes, their activation energies and acceleration factors, and the development of a statistical and mathematical framework to extrapolate lifetimes, failure rates and defectivity. This qualification methodology has been proven out now that several generations of silicon parts have been run for their true lifetimes under actual-use conditions. GaN transistors, however, are a more recent development. RF GaN HEMTs on more expensive silicon carbide substrates have become widely used in wireless base stations with proven reliability [1]. The power GaN HEMT, although based on similar fundamentals, has added features to enable higher voltage handling. It is grown on a silicon substrate and uses silicon fabrication-compatible materials to lower cost. Additionally, it needs to be an enhancement-mode (e-mode), or normally-off device, for fail-safe reasons. There are three leading architectures: 1) depletion-mode (d-mode) insulated gate GaN HEMT cascoded with an e-mode Si FET; 2) e-mode insulated gate GaN HEMT; and 3) p-doped, e-mode junction-gate GaN HEMT. These have different failure modes from each other, and from silicon FETs, which brings up the question of how to qualify them. The standard silicon-based qualification recipe is a worthy quality and reliability milestone, but it is not clear what it means for GaN transistors in terms of device lifetime, failure rates and application-relevance. Texas Instruments is an industry leader in semiconductor technology with longtime experience in bringing reliable semiconductor products to market, including non-silicon technologies like ferroelectric random access memory (FRAM). We are well-suited to bring reliable GaN products to market through GaN-relevant qualification methodology and application-relevant testing. TI is designing a comprehensive quality program based on GaN fundamentals and application-relevant testing to provide reliable GaN solutions. The material properties of gallium-nitride (GaN) enable an exciting and disruptive new power switch – the power GaN high-electron mobility transistor (HEMT). This HEMT is a field-effect transistor (FET) with much lower on-resistance. It can switch faster than an equivalently-sized silicon power transistor. These benefits are making power conversion more energy and space efficient. GaN can be grown on silicon substrates, which allows the use …