Semiconductor Layer Separation via Laser-Induced Cracks
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Solution Overview
Problem
In semiconductor processing, achieving precise control over the thickness of semiconductor devices, particularly in insulated gate bipolar transistors (IGBTs), is challenging due to the need for accurate setting of the target distance between the field stop zone and the emitter, which affects short-circuit current capability.
Innovation Solution
A method involving ion implantation of impurities into a semiconductor substrate to absorb electromagnetic radiation, causing local damage to the crystal lattice, followed by thermal processing to create cracks and separate the semiconductor layer from the substrate, allowing for precise thickness control through thermo-mechanical stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods are used to set semiconductor body thickness, then manufacturing process is simpler, but manufacturing precision of thickness is insufficient
Solution Approach 1:
The patent applies preliminary action by introducing impurities into the semiconductor substrate before forming the semiconductor layer. This pre-positioning of impurities creates predetermined absorption centers that will later guide crack formation during laser irradiation, enabling precise thickness control before the actual separation process occurs.
Solution Approach 2:
The patent uses impurities as an intermediary element between the laser radiation and the semiconductor crystal lattice. These impurities absorb electromagnetic radiation and convert it to thermal energy, which then generates localized stress and crack formation. This intermediary mechanism enables precise thickness control without directly irradiating the entire substrate.
2Manufacturing precision
If electromagnetic radiation is used to create local damage for separation, then manufacturing precision is improved, but use of energy increases
Solution Approach 1:
The patent applies local quality by concentrating the impurities in specific regions where separation is needed, rather than uniformly distributing them throughout the substrate. The laser radiation is also focused on specific areas, creating localized damage zones only where separation is required. This localized approach minimizes overall energy consumption while achieving precise separation.
Solution Approach 2:
The patent utilizes parameter changes by controlling the energy, wavelength, and duration of electromagnetic radiation to optimize the separation process. By adjusting these parameters, the process achieves precise separation with minimized energy input, as the impurities are selectively activated only under specific radiation 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 method enables precise adjustment of semiconductor device thickness, enhancing the short-circuit current capability of IGBTs by ensuring accurate separation and forming of semiconductor layers, thereby improving manufacturing efficiency and device performance.
Implementation Method 1
introducing impurities into a part of a semiconductor substrate at a first surface of the semiconductor substrate by ion implantation, the impurities being configured to absorb electromagnetic radiation of an energy smaller than a bandgap energy of the semiconductor substrate
Implementation Method 2
separating the semiconductor layer and the semiconductor substrate by thermal processing of the semiconductor substrate and the semiconductor layer, the thermal processing configured to cause crack formation along the local damage of the crystal lattice by thermo-mechanical stress
Data Source
AI summary
Methods of forming a semiconductor device are provided. A method includes introducing impurities into a part of a semiconductor substrate at a first surface of the semiconductor substrate by ion implantation, the impurities being configured to absorb electromagnetic radiation of an energy smaller than a bandgap energy of the semiconductor substrate. The method further includes forming a semiconductor layer on the first surface of the semiconductor substrate. The method further includes irradiating the semiconductor substrate with electromagnetic radiation configured to be absorbed by the impurities and configured to generate local damage of a crystal lattice of the semiconductor substrate. The method further includes separating the semiconductor layer and the semiconductor substrate by thermal processing of the semiconductor substrate and the semiconductor layer, where the thermal processing is configured to cause crack formation along the local damage of the crystal lattice by thermo-mechanical stress.