Dr. Jerry Hudgins
Date of this Version
Guenther, Brandon. "Thermal Comparison of Polycrystalline Diamond and AlN in Power Semiconductor Device Packages" Master's Thesis. University of Nebraska-Lincoln, 2018.
The desire for improved thermal management in power semiconductor device packaging is becoming increasingly important due to the progression towards implementing wide-bandgap semiconductor (WBG) materials, such as silicon carbide (SiC) and gallium nitride (GaN). These semiconductor materials have the capability of operating at much higher voltages, temperatures, and frequencies compared to standard silicon-based devices. However, utilizing this enhanced operating region will induce larger thermomechanical stress within the package structure as a consequence of operating at higher junction temperatures around 250-300 °C. To handle the higher and improved operating characteristics from the WBG semiconductors, the current package technology is modified by increasing heat flow through its layers. This modification will improve reliability and operating lifetime of device packages in high power applications.
The focus of this research was on enhancing the thermal performance of the direct bond copper (DBC) substrate in a standard package design by considering the implementation of polycrystalline diamond (PCD) films as a replacement for the commonly used DBC (AlN) substrates. The use of these PCD films in a standard device package has been examined in detail using an emissivity-calibrated thermal (IR) imaging camera experiment that measures and compares the top surface temperature profiles of a commercial module package and two PCD films (Co-PCD and Cu-PCD).
The results from this thermal experiment showed that both of the PCD films reached steady state considerably faster than the AlN substrate. The accelerated top surface temperature profiles of the PCD films demonstrated a faster thermal transient response time, an increased heat flow, and lower thermal resistance that can potentially handle the high operating characteristics of WBG semiconductors. In addition, the Co-PCD film displayed a faster thermal transient response time compared to the Cu-PCD film. The resulting thermal analysis on PCD films can be used to aid future research pertaining to dielectric breakdown strength tests, studying lateral heat flow, ways of interconnection into a device package, and mechanical behavior under thermomechanical stress within a package.
Adviser: Jerry L. Hudgins