Semiconductor Optical Device Fabrication via Halogen Gas Epitaxy
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Solution Overview
Problem
Conventional methods for producing integrated semiconductor optical devices result in abnormal growth of semiconductor layers along the side faces, leading to increased thickness and bending, which complicates the alignment and optical coupling between laser diodes and electroabsorption optical modulators, thereby reducing optical coupling efficiency.
Innovation Solution
A method involving the use of an insulating-film mask for selective etching and growth of semiconductor layers, where an etching gas containing a halogen element, such as hydrogen chloride, is supplied to control the growth rate and prevent abnormal growth, allowing for flat surfaces and improved alignment between semiconductor optical devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If semiconductor layers are grown by conventional metal organic vapor phase epitaxy method, then the semiconductor layers can be formed, but abnormal growth occurs along the side faces leading to increased thickness and bending
Solution Approach 1:
The patent applies preliminary anti-action by introducing an etching gas containing a halogen element during the semiconductor layer growth process. This etching gas acts in advance to prevent the abnormal growth that would otherwise occur along the side faces of etched structures. The halogen-containing gas reacts with the semiconductor material surface before excessive growth can occur, thereby suppressing the formation of thickened side regions and maintaining flat surfaces.
Solution Approach 2:
The patent changes the chemical composition parameters of the gas phase environment by introducing a halogen-containing etching gas into the metal organic vapor phase epitaxy process. This parameter change transforms the growth environment from purely depositional to a combined deposition-etching environment, where the halogen gas reacts with the semiconductor surface to prevent abnormal growth while allowing controlled layer formation.
2Ease of manufacture
If the semiconductor laminate is etched to form a mesa structure, then the first semiconductor optical device can be formed, but the side face creates a region where abnormal growth occurs
Solution Approach 1:
The etching gas introduced during growth acts preliminarily to counteract the tendency for abnormal growth at the mesa side faces. By having the halogen-containing gas present during the growth process, the system prevents the formation of thickened regions that would compromise the alignment between different semiconductor optical devices formed on the same substrate.
3Productivity
If material gas is supplied for growing semiconductor layers, then the layers can be formed, but the material gas accumulates at the side face of the mesa leading to increased thickness
Solution Approach 1:
The patent changes the gas composition parameters by adding a halogen-containing etching gas to the material gas mixture. This parameter change creates a chemical environment where the etching reaction counterbalances the deposition reaction at the mesa side faces, preventing material gas accumulation and ensuring uniform layer thickness across different regions.
Solution Approach 2:
The patent converts the potentially harmful accumulation of material gas at the mesa side faces into a beneficial effect by introducing the halogen-containing etching gas. The etching reaction, which might seem to reduce growth rate, actually prevents the harmful thickening by removing excess material that would otherwise accumulate, thereby maintaining uniform thickness while preserving overall productivity.
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 suppresses abnormal growth, ensuring flat semiconductor layers and improved optical coupling efficiency between laser diodes and electroabsorption optical modulators, enhancing the performance of integrated semiconductor optical devices.
Implementation Method 1
selectively growing a first semiconductor layer for the second semiconductor optical device by a metal organic vapor phase epitaxy method
Implementation Method 2
growing a first semiconductor layer... by a metal organic vapor phase epitaxy method
Implementation Method 3
The semiconductor laminate on which the stripe mask is formed is etched by an etching gas composed of the methyl iodide
Implementation Method 4
an etching gas containing a halogen element is supplied in addition to a material gas for the growing of the first semiconductor layer
Data Source
AI summary
The invention discloses a method of producing on a substrate a semiconductor optical device having a laser diode and an EA optical modulator. An etched side face of a first semiconductor portion is formed. Then, for example, a first optical confinement layer and an active layer both for the EA optical modulator are grown by the metal organic vapor phase epitaxy method. The first optical confinement layer is grown by supplying hydrogen chloride in addition to a material gas. When the first optical confinement layer is grown, the formation of a thick semiconductor layer along the etched side face, which is an abnormally grown semiconductor layer, is decreased. Subsequently, the active layer for the EA optical modulator is grown. This method can suppress the active layer for the EA optical modulator from bending caused by the abnormally grown semiconductor layer.