VCSEL Substrate Heating With Bottom-Side Temperature Sensing
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Solution Overview
Problem
Existing substrate heat treatment apparatuses using laser light-emitting devices face challenges in accurately measuring the temperature of flat substrates due to varying reflectance patterns on the upper surface, making non-contact temperature measurement unreliable.
Innovation Solution
A substrate heat-treating apparatus is designed with a process chamber that includes a beam transmitting plate below and an infrared transmitting plate above the flat substrate, utilizing a VCSEL beam irradiating module and a temperature measuring module with a pyrometer that measures the temperature from the lower surface through a temperature measuring hole, and incorporates a filter unit to minimize the effect of the laser beam on temperature measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If temperature is measured from the upper surface of the flat substrate, then non-contact measurement is achieved, but measurement accuracy deteriorates due to varying reflectance patterns on the upper surface
Solution Approach 1:
The patent inverts the measurement direction by measuring temperature from the lower surface of the substrate instead of the upper surface. The pyrometer is positioned below the substrate to detect thermal radiation from the lower surface, which has uniform properties without the reflectance variations caused by patterns on the upper surface. This inversion resolves the contradiction by maintaining non-contact measurement capability while eliminating the accuracy problem caused by upper surface reflectance variations.
2Use of energy by moving object
If laser beam is irradiated to the upper surface for heating, then heating efficiency is improved, but temperature measurement accuracy deteriorates due to laser beam interference
Solution Approach 1:
The patent extracts the measurement function from the heating path by positioning the pyrometer and temperature measurement hole below the substrate, separate from the upper surface where laser heating occurs. This spatial separation removes the laser beam interference from the measurement path while maintaining efficient heating from the upper surface, thus resolving the contradiction between heating efficiency and measurement accuracy.
Solution Approach 2:
The patent introduces a beam transmitting plate as an intermediary that allows the laser beam to pass through from the upper surface to heat the substrate internally, while the pyrometer measures temperature from the lower surface. This intermediary structure enables simultaneous heating and measurement without direct interference between the laser path and measurement path.
3Temperature
If VCSEL devices are arranged to cover large area, then heating uniformity is improved, but device complexity increases
Solution Approach 1:
The patent utilizes the third dimension (depth) by irradiating laser beams from the lower surface of the substrate through the beam transmitting plate. This vertical irradiation approach from below provides uniform heating across the substrate area without requiring a complex two-dimensional array of VCSEL devices on the upper surface, thus achieving temperature uniformity with reduced device complexity.
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 configuration allows for more accurate temperature measurement by irradiating the laser beam to the upper surface for heating and measuring the temperature from the bottom, reducing the impact of laser beam components on the pyrometer and enhancing temperature uniformity and accuracy.
Implementation Method 1
a beam irradiating module for irradiating a VCSEL beam having a single wavelength to a lower surface of the flat substrate through the beam transmitting plate
Implementation Method 2
a temperature measuring module for measuring the temperature of the lower surface or an upper surface the flat substrate... the temperature measuring module includes a pyrometer
Implementation Method 3
the filter unit includes a color filter that removes a beam in the visible ray region from an incident beam
Data Source
AI summary
The present disclosure discloses a substrate heat-treating apparatus including a process chamber in which a flat substrate to be heat treated is placed, the process chamber comprising a beam transmitting plate placed below the flat substrate and an infrared transmitting plate placed above the flat substrate; a beam irradiating module for irradiating a VCSEL beam having a single wavelength to a lower surface of the flat substrate through the beam transmitting plate; and an temperature measuring module configured to measure the laser beam reflected from the lower surface or an upper surface the flat substrate, thereby measuring the temperature of the flat substrate.