Semiconductor Mask Layer with Openings for Epitaxial Growth
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Solution Overview
Problem
Existing methods for producing semiconductor chips face challenges in achieving cost-efficiency and flexibility, particularly in epitaxial growth where growth selectivity between planar and structured surfaces is low, and in optimizing light outcoupling for optoelectronic chips.
Innovation Solution
A method involving a sapphire growth substrate with a smooth, unstructured surface and a mask layer made of semiconductor oxide, nitride, or metal nitride is used, where the mask material is selectively etchable and allows semiconductor material to grow better on the substrate surface, enabling epitaxial deposition and improving light outcoupling by patterning the mask layer to form semiconductor islands that coalesce into a layer sequence, which can be singulated into chips with enhanced optical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pre-structured sapphire substrates are used for growing GaN-based layers, then growth selectivity is improved, but device complexity and production cost increase
Solution Approach 1:
The patent applies preliminary action by depositing a mask layer on the unstructured sapphire substrate surface before epitaxial growth. This mask layer is then patterned with openings that serve as nucleation sites for semiconductor material growth. The preliminary masking and patterning steps enable growth selectivity without requiring pre-structured substrates, thus resolving the contradiction between growth selectivity and substrate complexity
Solution Approach 2:
The mask layer acts as an intermediary between the unstructured sapphire substrate and the semiconductor material. By introducing this intermediate layer with controlled openings, the patent achieves growth selectivity while maintaining substrate simplicity. The mask layer mediates the interaction between substrate and semiconductor, enabling precise growth control without direct substrate structuring
2Reliability
If a mask layer with openings is introduced for epitaxial growth, then growth selectivity and light outcoupling are improved, but manufacturing process complexity increases
Solution Approach 1:
The mask layer serves multiple functions: it provides growth selectivity during epitaxy, enables light outcoupling through its opening pattern, and can be removed selectively to release the semiconductor layer. This multi-functionality reduces the need for separate process steps and structures, thereby improving growth selectivity while limiting overall process complexity
Solution Approach 2:
The patent utilizes parameter changes in the mask layer material properties, specifically selecting materials with different etch rates relative to the sapphire substrate. This allows selective removal of the mask layer after growth, simplifying the overall process by enabling easy mask removal without affecting the substrate or grown layers
3Ease of manufacture
If mask material is selected for rapid etching decomposition, then ease of mask removal is improved, but manufacturing precision may be compromised
Solution Approach 1:
The patent applies local quality by ensuring the mask layer completely covers the growth surface except at the intended opening locations. The openings are precisely positioned and sized to control where semiconductor material grows. This localized masking approach ensures that rapid etching of the mask material does not compromise growth precision, as the mask maintains its protective function exactly where needed during the epitaxial process
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 production of semiconductor chips with improved cost-efficiency, flexibility, and enhanced light outcoupling, reducing the need for pre-structured substrates and simplifying the production process, while achieving high crystalline quality and optical performance.
Implementation Method 1
the mask material is selected such that it is decomposed by etching, e.g., wet-chemical etching, more rapidly than the material of the growth surface, namely sapphire, and more rapidly than a semiconductor material to be applied later
Implementation Method 2
The growth surface of the growth substrate is provided for the semiconductor material to be deposited thereon, e.g., epitaxially
Data Source
AI summary
A semiconductor chip is disclosed. In an embodiment a semiconductor chip includes a multiply-connected mask layer comprising openings, the openings completely penetrate the mask layer and a semiconductor layer sequence, which, at least in places, is in direct contact with the mask layer, wherein the semiconductor layer sequence is disposed on the mask layer, wherein the mask layer comprises a light-transmissive material, and wherein the light-transmissive material comprises an optical refractive index for light which is smaller than a refractive index of the semiconductor layer sequence.