Bonded Wafer Void Suppression via Active Layer Composition Control
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Solution Overview
Problem
The smart cut method for producing bonded wafers faces issues with voids or blisters forming at the bonding interface when the buried oxide film thickness is reduced, leading to yield deterioration, and existing solutions require thickening the active layer or using expensive equipment.
Innovation Solution
A method involving ion implantation of light elements like hydrogen or helium to a predetermined depth, bonding with a support substrate, and exfoliating through heat treatment, while enhancing the active layer's strength by adjusting its composition and applying plasma treatment to prevent voids and blisters without thickening the active layer, even when the insulating film is less than 50 nm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the thickness of the insulating film is reduced to not more than 50 nm, then the uniformity of film thickness is improved and material cost is reduced, but voids or blisters are easily generated at the bonding interface deteriorating yield
Solution Approach 1:
The invention changes the physical and chemical parameters of the active layer by controlling the concentration of interstitial atoms (carbon, oxygen, nitrogen) and performing plasma treatment, rather than changing the thickness parameter. This allows maintaining thin insulating film thickness (not more than 50 nm) while preventing void and blister formation through enhanced layer strength from compositional control.
Solution Approach 2:
The invention applies local quality enhancement by specifically controlling the composition at the bonding interface region. By adjusting interstitial atom concentrations in the active layer and applying plasma treatment to the surface, the local strength and adhesive properties are enhanced precisely where needed (at the bonding interface) without affecting the overall thickness of the active layer.
2Strength
If the thickness of the active layer is thickened to over 750 nm to suppress voids or blisters, then the strength of the active layer is enhanced, but the implantation depth must exceed 750 nm requiring expensive apparatus and larger polishing quantity
Solution Approach 1:
Instead of changing the thickness parameter of the active layer, the invention changes the compositional parameters by controlling interstitial atom concentrations (carbon: 1×10^19 to 1×10^21 atoms/cm³, oxygen: 1×10^18 to 1×10^20 atoms/cm³, nitrogen: 1×10^18 to 1×10^20 atoms/cm³) and applying plasma treatment. This achieves enhanced strength without increasing thickness, avoiding the need for expensive high-voltage implantation apparatus and reducing polishing quantity.
3Ease of manufacture
If the thickness of the active layer is kept thin to reduce polishing quantity, then the manufacturing cost is reduced, but voids or blisters occur at the bonding interface when the insulating film is thin
Solution Approach 1:
The invention changes the chemical composition parameters of the active layer by controlling interstitial atom concentrations and applying plasma treatment, enabling thin active layer thickness (maintaining reduced polishing quantity) while preventing void and blister formation. The compositional enhancement provides sufficient strength at the bonding interface even with thin layers.
Solution Approach 2:
The invention performs preliminary action by controlling the composition and performing plasma treatment on the active layer before bonding. This preliminary compositional optimization and surface treatment enhance the layer strength and adhesive properties in advance, preventing void and blister formation during subsequent bonding and heat treatment processes.
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
Effectively suppresses the occurrence of voids and blisters, maintaining active layer uniformity and reducing material costs by enhancing the active layer's strength and adhesive properties without increasing its thickness.
Implementation Method 1
implanting ions of a light element such as hydrogen or helium to a predetermined depth position of a wafer for active layer
Implementation Method 2
exfoliating the ion implanted portion through a heat treatment
Data Source
AI summary
A bonded wafer is produced by implanting ions of a light element into a wafer for active layer to a predetermined depth position to form an ion implanted layer, bonding the wafer for active layer to a wafer for support substrate directly or through an insulating film of not more than 50 nm, exfoliating the wafer for active layer at the ion implanted layer and thinning an active layer exposed through the exfoliation to form the active layer having a predetermined thickness, in which the thickness of the active layer before the thinning is not more than 750 nm and an elongation of slip dislocation in a strength test of the wafer for active layer before the bonding is not more than 100 μm at a predetermined thickness.