Lithium-Hydrogen Implantation for Semiconductor Layer Transfer
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Solution Overview
Problem
Existing processes for creating fractures in semiconductor substrates, such as the Smart Cut process, face challenges with high implantation doses and thermal budgets, and are sensitive to implantation parameters, particularly with techniques like He-H co-implantation and boron hydrogen co-implantation, which can damage substrates and limit layer quality.
Innovation Solution
A novel process involving the formation of a high lithium concentration zone followed by hydrogen implantation, where lithium is introduced through ion implantation or electrolysis/diffusion, allowing for effective hydrogen trapping and reduced thermal and dose requirements for fracture formation, with lithium and hydrogen peaks closely located to optimize implantation depths and prevent substrate damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high implantation doses are used to create microcavities for fracture formation, then fracture formation is achieved, but substrate damage increases and layer quality deteriorates
Solution Approach 1:
The patent changes the chemical nature of the implanted ions from heavy ions (He, H, B) to light lithium ions. This parameter change allows achieving the same microcavity formation effect at much lower doses (10^13 to 10^15 Li/cm² compared to 10^16 to 10^17 He-H/cm² or B-H/cm²), thereby reducing substrate damage while maintaining fracture formation capability
Solution Approach 2:
Lithium ions act as temporary agents that create microcavities during the annealing process and then are effectively removed or transformed. The lithium serves its purpose of creating the necessary microcavity structure and does not remain as a harmful contaminant, unlike heavier ions that cause persistent damage
2Reliability
If high thermal budgets are applied to form microcavities and achieve fracture, then fracture formation is successful, but energy consumption increases and substrate damage worsens
Solution Approach 1:
The patent changes the implantation parameters by using lithium ions with specific energy ranges (10 to 210 keV) and doses (10^13 to 10^15 Li/cm²) that create microcavities which can be activated at lower annealing temperatures (300-700°C) compared to conventional methods, thereby reducing the thermal budget required
3Quantity of substance
If He-H co-implantation is used to reduce fracture formation temperature and dose, then implantation dose is reduced, but the process becomes highly sensitive to implantation parameters
Solution Approach 1:
The patent extracts helium and hydrogen from the co-implantation mixture and replaces them with lithium ions alone. This simplifies the implantation process from a complex two-ion system requiring precise control of relative distances, ordering, and dose ratios to a single-ion process with more宽容 process windows
Solution Approach 2:
The patent uses a single type of ion (lithium) rather than a mixture of different ions (He-H or B-H). This homogeneity eliminates the complex interactions between different ion species and their respective implantation profiles, making the process less sensitive to parameter variations
4Temperature
If boron implantation is used to lower fracture formation temperature, then fracture temperature is reduced to 200°C, but boron causes more substrate damage due to heavier atom mass
Solution Approach 1:
The patent changes the implanted ion from heavy boron atoms to light lithium ions. This parameter change allows achieving low fracture formation temperatures while avoiding the substrate damage caused by heavy ion mass, as lithium is much lighter than boron and causes significantly less collision damage during implantation
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 process significantly reduces the thermal budget and total implantation dose, enhances layer quality, and allows for thicker layer transfer with superior crystalline quality, while being easier to implement and less damaging to substrates compared to existing methods.
Implementation Method 1
formation in a silicon substrate of a high lithium concentration zone... and hydrogen implantation in or in the vicinity of the high lithium concentration zone
Implementation Method 2
The formation of a high lithium concentration zone makes it possible to form effective traps for hydrogen, lithium and hydrogen particularly having a strong chemical affinity
Implementation Method 3
hydrogen implantation in or in the vicinity of the high lithium concentration zone
Implementation Method 4
The formation of a high lithium concentration zone makes it possible to form effective traps for hydrogen, lithium and hydrogen particularly having a strong chemical affinity
Implementation Method 5
application of at least one thermal budget to result in the detachment of the layer defined by the implantation
Implementation Method 6
In the case of a heat treatment, the treatment is performed by applying a temperature within a range substantially between 300° C. and 700° C.
Data Source
AI summary
A process for forming a layer (26) of semiconductor material from a substrate (20), or donor substrate, made of the same semiconductor material is described, comprising:formation in said donor substrate of a high lithium concentration zone (22), with a concentration between 5×1018 atoms/cm3 and 5×1020 atoms/cm3,then a hydrogen implantation (24) in the donor substrate, in, or in the vicinity of, the high lithium concentration zone,application of a stiffener (19) with the donor substrate,application of a thermal budget to result in the detachment of the layer (34) defined by the implantation.