Semiconductor Laser Insulation Stack for Active Layer Stress Control
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Solution Overview
Problem
High-temperature film formation in semiconductor laser devices can lead to thermal decomposition of semiconductor materials and increased stress on active layers, compromising reliability and causing damage.
Innovation Solution
A semiconductor laser device manufacturing method involving a stacked structure with a mesa stripe configuration, where a first insulation film is formed using a sputtering method at a low temperature and a second insulation film, thinner than the first, is formed using plasma CVD at a higher temperature, reducing stress and damage to the active layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the insulation film thickness is increased to prevent light leakage, then light confinement efficiency is improved, but stress on the active layer increases causing characteristic changes or crystal defects
Solution Approach 1:
The insulation film is divided into two layers: a first insulation film formed by thermal CVD at high temperature (about 600°C) with thickness of 50 nm, and a second insulation film formed by plasma CVD at low temperature (about 300°C) with thickness of 100 nm. This segmentation allows the total thickness to be sufficient for light confinement while the low-temperature second layer minimizes stress on the active layer.
Solution Approach 2:
The film formation temperature parameter is changed between layers: the first layer is formed at high temperature (600°C) and the second layer at low temperature (300°C). This parameter change enables the second layer to be thicker while applying less stress to the active layer, resolving the contradiction between thickness and stress.
2Reliability
If the insulation film is formed by plasma CVD to improve film quality, then insulation performance is improved, but the active layer is damaged by plasma causing reliability degradation
Solution Approach 1:
The first insulation film is formed by thermal CVD before the second insulation film is formed by plasma CVD. This preliminary action creates a protective barrier that prevents plasma from directly hitting and damaging the active layer, while still allowing the plasma process to create a high-quality insulation film.
Solution Approach 2:
The first insulation film acts as an intermediary layer between the plasma source and the active layer. It protects the active layer from plasma damage while allowing the second insulation film to be formed with good insulation performance through plasma CVD.
3Reliability
If high-temperature film formation is used to form the insulation film, then film density and quality are improved, but semiconductor material is thermally decomposed
Solution Approach 1:
The insulation film formation process is segmented into two stages: first, a thin layer (50 nm) is formed by thermal CVD at high temperature (600°C) to ensure good film quality and adhesion; second, a thicker layer (100 nm) is formed by plasma CVD at low temperature (300°C) to avoid thermal decomposition of the semiconductor material.
Solution Approach 2:
The film formation temperature parameter is changed between the two layers. The first layer is formed at high temperature (600°C) for quality, while the second layer is formed at low temperature (300°C) to protect the semiconductor material from thermal decomposition, maintaining material stability.
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 enhances the reliability of semiconductor laser devices by minimizing stress and damage to the active layer, improving the overall performance and longevity of the devices.
Implementation Method 1
forming a first insulation film on the stacked structure by a sputtering method
Implementation Method 2
forming a second insulation film thinner than the first insulation film, on the first insulation film by a plasma CVD method at a film forming temperature higher than that when the first insulation film has been formed
Data Source
AI summary
The present invention is characterized by comprising: forming a stacked structure in which a lower cladding layer, an active layer and an upper cladding layer are stacked on an InP substrate in a shape having a mesa stripe structure; forming a first insulation film on the stacked structure by a sputtering method; forming a second insulation film thinner than the first insulation film, on the first insulation film by a plasma CVD method at a film forming temperature higher than that when the first insulation film has been formed; and forming a first electrode on the upper cladding layer, and forming a second electrode on a back surface of the InP substrate.