Semiconductor Laser Wafer Composition Evaluation for Yield Control
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Solution Overview
Problem
The semiconductor laser's performance is affected by external disturbances during the epitaxial crystal growth process, leading to fluctuations in composition ratios and film thicknesses, which result in defective wafers and reduced chip yield.
Innovation Solution
A semiconductor laser design that includes a composition evaluation layer on the wafer surface, allowing for X-ray diffraction measurements to determine the composition ratios and film thicknesses, thereby evaluating the wafer quality and identifying defects before further processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of cascade connection periods of the unit multi-quantum well structure increases, then the light emission performance is improved, but the crystal growth time of the active layer lengthens and the effects of external disturbances increase
Solution Approach 1:
The patent introduces a composition evaluation layer during the epitaxial growth process that allows for in-situ measurement of composition ratios and film thicknesses. This preliminary evaluation enables real-time monitoring and adjustment of growth parameters, ensuring that even as the number of cascade connection periods increases, the composition precision is maintained by detecting and correcting deviations before they accumulate
Solution Approach 2:
The patent implements a feedback mechanism where X-ray diffraction measurements are performed during the growth process to monitor the composition ratio and film thickness. The measured values are fed back to control the growth parameters, allowing dynamic adjustment to compensate for external disturbances. This closed-loop control ensures that increasing the number of cascade connection periods does not lead to cumulative composition errors
2Reliability
If the number of cascade connection periods increases, then the light emission performance is improved, but the crystal growth time lengthens leading to increased external disturbance effects
Solution Approach 1:
The real-time monitoring system provides continuous feedback on growth rate and composition, enabling dynamic optimization of the growth process. This allows for maintaining high light emission performance through increased cascade connection periods while minimizing total growth time by adjusting parameters based on actual growth conditions rather than following a fixed time schedule
Solution Approach 2:
The patent utilizes parameter changes in the epitaxial growth process, specifically adjusting temperature, pressure, and source material flux based on real-time measurements. By dynamically changing these parameters during growth, the system can maintain high performance requirements for multiple cascade periods without proportionally increasing the total growth time
3Ease of manufacture
If composition ratios and film thicknesses are not precisely controlled, then the manufacturing process is simpler, but the chip yield is reduced due to defective wafers
Solution Approach 1:
The composition evaluation layer performs self-service by automatically measuring and evaluating its own composition ratio and film thickness during the growth process. This self-monitoring capability eliminates the need for complex post-growth inspection equipment and manual analysis, maintaining manufacturing simplicity while ensuring high chip yield through real-time quality assurance
Solution Approach 2:
The patent replaces complex mechanical measurement and control systems with X-ray diffraction-based optical measurement. This substitution simplifies the manufacturing process by using non-contact, in-situ measurements that require minimal additional equipment while providing precise composition and thickness control to maximize chip yield
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
The evaluation process significantly increases the semiconductor laser chip yield by identifying and rejecting defective wafers, thereby improving the overall productivity and quality of the semiconductor laser chips.
Implementation Method 1
allowing for X-ray diffraction measurements to determine the composition ratios and film thicknesses
Data Source
Figure 1~2
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AI summary
A semiconductor laser wafer (10) includes a substrate (20), a first semiconductor layer (30), an active layer (40), a second semiconductor layer (50), and a composition evaluation layer (60). The active layer (40) is provided on the first semiconductor layer (30); multiple periods of pairs of a light-emitting multi-quantum well region (86) and an injection multi-quantum well region (88) are stacked in the active layer (40); the light-emitting multi-quantum well region (86) is made of a first compound semiconductor and a second compound semiconductor. The second semiconductor layer (50) is provided on the active layer (40). The composition evaluation layer (60) is provided above the active layer (40) and includes a first film (61) and a second film (62); the first film (61) is made of the first compound semiconductor and has a first thickness; and the second film (62) is made of the second compound semiconductor and has a second thickness.