Pulsed Laser Heating for Uniform Structure Thinning
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Solution Overview
Problem
Existing methods for treating structures with a useful layer, such as semiconductor-on-insulator (SeOI) types, face challenges in reducing thickness variations, particularly beyond a spatial wavelength threshold, leading to non-uniformities that are difficult to correct.
Innovation Solution
A method involving a pulsed laser beam that heats the useful layer, with a wavelength differing by less than 15 nm from a central wavelength where the reflectivity sensitivity with respect to the insulating layer is zero, allowing for controlled heating based on thickness variations, enabling uniform thinning or thickening reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional heating is used, then the process is simple to implement, but it cannot reduce thickness non-uniformities beyond a certain spatial wavelength threshold
Solution Approach 1:
The patent replaces the conventional mechanical heating system (heating resistors or halogen lamps) with a laser-based heating system. This substitution enables precise spatial and temporal control of the thermal field, allowing the system to address thickness non-uniformities across a broader range of spatial wavelengths while maintaining operational simplicity through computer-controlled laser scanning.
2Manufacturing precision
If the laser wavelength is not precisely controlled, then the heating efficiency varies, but the process becomes easier to implement
Solution Approach 1:
The patent identifies and controls the laser wavelength as a critical parameter to optimize heating efficiency and uniformity. By selecting a specific wavelength that matches the absorption characteristics of the useful layer material, the system achieves maximum heating efficiency. The wavelength is precisely controlled through laser source selection and stabilization mechanisms, ensuring consistent thermal response across different processing conditions.
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 approach effectively reduces thickness variations by selectively heating areas of the useful layer, enhancing the kinetics of etching or epitaxy reactions, thereby improving the uniformity of the layer thickness across the structure.
Implementation Method 1
the useful layer is heated by a pulsed laser beam, the beam sweeping at least part of the free surface of the useful layer
Implementation Method 2
the wavelength of the beam being different by less than 15 nm, preferably less than 7 nm, from a central wavelength for which the partial derivative of the reflectivity of the structure with respect to the thickness of the insulating layer is zero
Implementation Method 3
chemical species being capable of reacting chemically with the useful layer, with a kinetics strictly increasing as a function of the temperature of the useful layer
Implementation Method 4
The type of chemical reaction depends on the nature of the chemical species 6 and the useful layer 2, and can then take the form of a thinning by etching of the useful layer 2
Implementation Method 5
or a thickening by epitaxy of the useful layer 2
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a process for treating a structure, the structure comprising, from its back side to its front side, a carrier substrate (4), an insulating layer (3) and a useful layer (2), the useful layer (2) having a free surface (S), the structure being placed in an atmosphere containing chemical species (6), the chemical species (6) being capable of reacting chemically with the useful layer (2); this treatment process is noteworthy in that the useful layer (2) is heated by a pulsed laser beam (8), the beam (8) sweeping the free surface (S), the wavelength of the beam (8) differing by at most plus or minus 15 nm from a central wavelength, the central wavelength being chosen so that the sensitivity of the reflectivity of the structure (1) relative to the insulating layer (3) is zero.