Donor Substrate Structure for Low-Temperature Single-Crystal Transfer
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Solution Overview
Problem
Current 3D integration techniques face challenges in transferring high-quality single-crystal layers onto receiver substrates with existing electronic components, as conventional methods require high temperatures and cannot handle the thermal limitations of devices with metallization levels, necessitating low-temperature processes for defect repair and interface closure.
Innovation Solution
A donor substrate with a buried weakened plane, a stop layer for selective etching, and an amorphized portion for recrystallization, allowing for direct bonding and low-temperature transfer of a single-crystal thin layer onto a receiver substrate, followed by selective chemical etching to achieve high-quality layer transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional crystalline thin-film growth techniques (epitaxy) are used, then high-quality single-crystal layers can be formed, but high temperatures are required which damage existing electronic components on the receiver substrate
Solution Approach 1:
The process is segmented into distinct stages: (1) forming the single-crystal layer on a separate donor substrate using epitaxy at high temperature, (2) bonding the donor substrate to the receiver substrate at low temperature, and (3) separating the thin layer from the donor substrate. This segmentation allows high-temperature processing to occur on the donor substrate away from sensitive devices, while the receiver substrate remains at low temperature throughout.
Solution Approach 2:
The donor substrate acts as an intermediary carrier that temporarily holds the single-crystal layer during manufacturing. It enables the layer to be formed at high temperature, then transferred to the temperature-sensitive receiver substrate without exposing the receiver to high temperatures. The donor substrate is eventually discarded after transfer.
2Ease of manufacture
If direct bonding of donor substrate to receiver substrate is performed, then layer transfer is enabled, but the bonding interface requires high-temperature closure and defect repair that damages electronic components
Solution Approach 1:
The bonding process parameters are changed to enable low-temperature operation. Specifically, the bonding interface is prepared with amorphous silicon layers that can bond effectively at temperatures below 400°C, and the weakened plane is engineered to allow separation at these low temperatures. This eliminates the need for high-temperature bonding closure.
3Manufacturing precision
If the single-crystal layer is thinned to very thin dimensions, then high-quality transfer is achieved, but the layer becomes difficult to handle and requires high-temperature processing for repair
Solution Approach 1:
The amorphous silicon bonding layer is prepared in advance on the donor substrate, creating a robust bonding interface that can be closed at low temperatures. The weakened plane is also pre-formed through ion implantation, enabling low-temperature separation. These preliminary actions eliminate the need for high-temperature defect repair later.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables the transfer of high-quality single-crystal layers at low temperatures, preserving the integrity of underlying electronic components and avoiding high-temperature processing, thus facilitating the production of advanced electronic devices.
Implementation Method 1
The amorphized sub-portion is recrystallized, in order to restore a single-crystal quality to the first layer
Implementation Method 2
the donor substrate undergoes a thinning step... the Smart Cut method... based on implanting gaseous species in the donor substrate... to form a buried weakened plane; after assembly, during a fracture step, the donor substrate is separated along the weakened plane
Implementation Method 3
an amorphized sub-portion, made amorphous through ion implantation
Data Source
AI summary
A donor substrate for transferring a single-crystal thin layer made of a first material, onto a receiver substrate. The donor substrate comprises: —a buried weakened plane delimiting an upper portion and a lower portion of the donor substrate, —in the upper portion, a first layer, a second layer adjacent to the buried weakened plane, and a stop layer between the first layer and the second layer the first layer composed of the first material, the stop layer being formed of a second material, —an amorphized sub-portion, made amorphous by ion implantation, having a thickness less than that of the upper portion, and including at least the first layer; the second layer comprising at least one single-crystal sub-layer, adjacent to the buried weakened plane. Two embodiments of a method may be used for transferring a single-crystal thin layer from the donor substrate.