Novel Scalable Transfer Approach for Discrete III‐Nitride Devices Using Wafer‐Scale Patterned h‐BN/Sapphire Substrate for Pick‐and‐Place Applications

Abstract

The mechanical release of III‐nitride devices using h‐BN is a promising approach for heterogeneous integration. Upscaling this technology for industrial level requires solutions that allow a simple pick‐and‐place technique of selected devices for integration while preserving device performance. An advance that satisfies both of these requirements is demonstrated in this work. It is based on a lateral control of the h‐BN quality, using patterned sapphire with a SiO2 mask, to achieve localized van der Waals epitaxy of high‐quality GaN based device structures. After process fabrication, the devices can be individually picked and placed on a foreign substrate without the need for a dicing step. In addition, this approach could reduce delamination of h‐BN on large diameter substrates because each h‐BN region is smaller, with independent device structures. Discrete InGaN LEDs on h‐BN are grown and fabricated on 2 in. patterned sapphire using a SiO2 mask. A set of devices are selectively released and transferred to flexible aluminum tape. The transferred LEDs exhibit blue light emission around 435 nm. The approach presented here is scalable on any wafer size, can be applied to other types of nitride‐based devices, and can be compatible with commercial pick‐and‐place handlers for mass production.

Effectiveness of selective area growth using van der Waals h-BN layer for crack-free transfer of large-size III-N devices onto arbitrary substrates

“…In this approach, the localized vdWs epitaxy reduces the 3D heterostructures delamination, since they are localized to relatively small unmasked area of 1 mm 2 to 1 cm 2 and separated from each other. The details of the approach have been reported elsewhere 11 . In addition, the SAVWE makes the transfer easier since after process fabrication, devices are pre-diced and can be individually lifted-off and placed on an arbitrary substrate.…”

“…The fabrication of the LEDs follows the process described in Ref. 11 using optical lithography. Dry etching was accomplished by Cl 2 /Ar inductively coupled plasma (ICP).…”

“…Recent reports have been made of transfer of some key opto-electronic devices (HEMTs, LEDs and solar cells) to flexible and rigid substrates 8 – 10 . A simple lift-off of pre-diced devices has also been demonstrated 11 . This technique consists of patterning the epi-wafer surfaces using a dielectric mask so that growth selectively occurs in millimetric areas.…”

Spalling‐Induced Liftoff and Transfer of Electronic Films Using a van der Waals Release Layer

“…Recently, selective area liftoff of GaN films grown on BN was demonstrated but required masking with SiO 2 prior to BN film deposition. [37] In that situation, the material nucleation process was modified due to the mask which actually improved the crystal quality. [38] In the selective liftoff process described herein, the area selection step is performed at the back-end.…”

“…The width of the laser scribing line was ≈10 µm, which results in more area lost compared to the ≈1 µm mask line width in ref. [37]. After separating the devices using thermal release tape, the devices were released from the tape using a hotplate, then in a bath of liquid, the metals were etched from the freestanding GaN/device flakes.…”