Thin Silicon Transfer Using Ion-Implanted SOI Cleavage Layers
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Solution Overview
Problem
Current methods for transferring thin silicon layers in semiconductor wafer manufacturing, such as back etch SOI and hydrogen implantation, are time-consuming, costly, and lack suitable thickness uniformity for layers thinner than a few microns, and existing bonding techniques result in weak van der Waal's forces that require high-temperature annealing.
Innovation Solution
A method involving the implantation of H2+ and He+ ions into a silicon dioxide layer of a donor substrate, followed by annealing to form a damage layer, bonding with a handle substrate, and cleaving at the damage layer to transfer silicon layers of specific thickness between 500 Angstroms and 2500 Angstroms, enabling the production of fully-depleted SOI structures with improved uniformity and reduced manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If back etch SOI method is used to transfer thin silicon layers, then layer transfer is achieved, but the process is time-consuming and costly
Solution Approach 1:
The patent applies preliminary action by forming a damage layer through ion implantation before the bonding step. This pre-prepared damage layer serves as a predetermined cleavage plane that enables rapid layer transfer after bonding, eliminating the need for time-consuming back etching processes while maintaining precise thickness control.
2Manufacturing precision
If back etch SOI method is used, then layer transfer is achieved, but substantial portion of donor wafer is wasted
Solution Approach 1:
The patent implements discarding and recovering by enabling the donor substrate to be reused. The damage layer formation through ion implantation allows selective cleavage at the damage layer while preserving the bulk donor substrate, which can then be recovered and reused for additional layer transfers, dramatically reducing material waste compared to back etch methods.
3Manufacturing precision
If hydrogen implantation is used for layer transfer, then thickness uniformity is improved, but the process becomes more complex
Solution Approach 1:
The patent applies parameter changes by utilizing ion implantation with specific energy levels (5-50 keV) and doses (1×10^15 to 1×10^17 ions/cm²) to create a damage layer at a controlled depth. By adjusting these parameters, the thickness of the transferred layer can be precisely controlled while maintaining uniformity, achieving similar results to hydrogen implantation but with a more straightforward process flow.
4Ease of manufacture
If van der Waal's bonding is used to bond wafers, then bonding is initiated, but the bond is weak and requires high-temperature annealing
Solution Approach 1:
The patent applies preliminary action by performing surface activation treatments (plasma treatment, chemical etching, or oxidation) before bonding to enhance surface reactivity. This preliminary preparation creates stronger initial bonds between wafers, reducing the strength of van der Waal's forces and enabling subsequent bonding at lower temperatures with shorter annealing times.
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
This method allows for the efficient transfer of thin silicon layers with improved thickness uniformity and reduced manufacturing costs, enabling the production of high-performance CMOS applications with limited silicon and buried oxide layer thickness, while also recycling the donor substrate.
Implementation Method 1
implanting H2+ ions, H+ ions, or a combination of H2+ ions and H+ ions through a silicon dioxide layer in contact with a front surface of the single crystal silicon donor substrate
Implementation Method 2
implanting He+ ions through the silicon dioxide layer in contact with the front surface of a single crystal silicon donor substrate
Implementation Method 3
annealing the ion implanted single crystal silicon donor substrate at a temperature and for a duration sufficient to form a damage layer
Implementation Method 4
bonding the silicon dioxide layer in contact with the front surface of the single crystal silicon donor substrate to a dielectric layer in contact with the handle substrate
Implementation Method 5
cleaving the annealed multilayer substrate at the damage layer in the single crystal silicon donor substrate to thereby transfer the silicon layer
Data Source
AI summary
A method for preparing semiconductor on insulator structures comprises transferring a thin layer of silicon from a donor substrate onto a handle substrate.