Layer-Scale and Chip-Scale Transfer Techniques for Functional Devices and Systems: A Review

Abstract

Hetero-integration of functional semiconductor layers and devices has received strong research interest from both academia and industry. While conventional techniques such as pick-and-place and wafer bonding can partially address this challenge, a variety of new layer transfer and chip-scale transfer technologies have been developed. In this review, we summarize such transfer techniques for heterogeneous integration of ultrathin semiconductor layers or chips to a receiving substrate for many applications, such as microdisplays and flexible electronics. We showed that a wide range of materials, devices, and systems with expanded functionalities and improved performance can be demonstrated by using these technologies. Finally, we give a detailed analysis of the advantages and disadvantages of these techniques, and discuss the future research directions of layer transfer and chip transfer techniques.

Low‐Energy UV Ultrafast Laser Controlled Lift‐Off for High‐Quality Flexible GaN‐Based Device

“…The total processing time of this strategy is less than ≈20 s, which is 2–3 orders of magnitude more efficient compared to the CLO method (which normally takes a few hours or a few days) at sample areas close to the wafer level. [ 13 ] Although the current mechanical release method only takes a few seconds, [ 19 ] it inevitably requires a tedious sacrificial layer growth process to weaken the bond between the substrate and the film. In our strategy, it only requires one‐step laser scanning for the separation of GaN film, effectively simplifying the fabrication process of GaN‐based devices.…”

“…[ 17,18 ] Among these approaches, LLO is favored by the industrial field because of its pollution‐free, stable, and convenient integration characteristics for removing a GaN layer from a sapphire substrate and then transferring the GaN layer onto a potential foreign substrate. [ 19 ] In Table 1 , the recent studies using LLO process for separation of GaN layer from sapphire substrate have been benchmarked and concluded. Normally, excimer lasers and nanosecond ultraviolet lasers are used for the LLO process because the photon energy of these two sources is larger than the bandgap of GaN but less than the bandgap of sapphire.…”

Technology and Applications of Micro-LEDs: Their Characteristics, Fabrication, Advancement, and Challenges

“…For conventional LEDs, mechanical bending during operation induces strain and potential self-heating, causing a degradation in the device performance, which may limit the utilization of μLEDs in flexible substrates. ,, In 2020, Asad et al demonstrated several intermediary metal bonding layers and developed a “paste-and-cut” technique to transfer GaN μLEDs from sapphire substrates to flexible platforms. They also investigated the effect of LED geometry on the performance of the flexible devices.…”

Laser‐Based Micro/Nano‐Processing Techniques for Microscale LEDs and Full‐Color Displays

“…The development of techniques that can transfer LED chips from the growth substrate to another substrate is of great importance, which is driven by a few primary considerations. [117,118] The first driving force is to improve the LED optical performance and thermal stability. This is particularly true for general lighting, where high-power LEDs must be used.…”