Emissivity-Corrected Pyrometry for Stable Multilayer Deposition
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for emissivity-corrected pyrometry in thin film deposition suffer from persistent temperature oscillations due to incomplete emissivity correction, leading to inaccuracies in temperature regulation, particularly in the deposition of GaN or AlGaN on silicon, which affects the reproducibility and yield of electronic components.
Innovation Solution
The method involves measuring emissivity and reflectance values simultaneously or consecutively during the deposition of a first portion of a multilayer structure, calculating a correction value during this phase, and using it to determine the actual substrate temperature during the deposition of a second portion, thereby minimizing temperature oscillations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If emissivity correction is performed using conventional pyrometry methods, then temperature measurement is enabled, but persistent temperature oscillations occur due to incomplete emissivity correction
Solution Approach 1:
The correction value is determined in advance during the deposition of the first portion of the multilayer structure, immediately before deposition of the second portion. This preliminary determination of the correction value eliminates temperature oscillations during the critical deposition process by pre-characterizing the optical properties of the substrate and deposited layers.
Solution Approach 2:
The method uses feedback from reflectance and emissivity measurements to calculate a correction value that compensates for optical property changes. The pyrometer measurement is corrected using this feedback mechanism, where the correction value adjusts the raw temperature measurement to account for varying emissivity of the multilayer structure.
2Measurement precision
If reflectance measurement is performed to determine emissivity correction, then emissivity value can be calculated, but measurement time increases due to sequential measurements
Solution Approach 1:
The method combines reflectance measurement and emissivity measurement into a unified correction approach. By measuring both reflectance and emissivity values and using them together to determine a single correction value, the method eliminates the need for separate measurement cycles and achieves faster characterization of the substrate's optical properties.
Solution Approach 2:
The correction value determination is performed continuously during the deposition process rather than in separate measurement steps. The optical measurements are integrated into the deposition workflow, allowing the correction value to be updated in real-time without interrupting the manufacturing process.
3Measurement precision
If separate deposition process is used to determine correction value, then correction accuracy improves, but production productivity decreases
Solution Approach 1:
The correction value is determined during the deposition of the first portion of the multilayer structure as a preliminary step before the critical second portion deposition. This integrates the correction determination into the manufacturing process itself, eliminating separate calibration runs and maintaining high productivity while achieving accurate correction values.
Solution Approach 2:
The deposition process serves multiple functions: it deposits the multilayer structure for device fabrication and simultaneously determines the correction value for temperature measurement. This multi-functionality eliminates the need for separate correction determination processes and maintains production throughput.
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 reduces temperature oscillations to minimal levels, ensuring precise temperature regulation and improved reproducibility of the deposition process, enhancing the quality of multilayer structures like field effect transistors.
Implementation Method 1
use is made of the relationship between the thermal radiation emitted by the hot measurement object and the temperature of the object, which is described by the known Planck radiation equation
Implementation Method 2
The reflectance is measured by emitting light of the defined wavelength at the location of the sensor, reflecting it upon vertical incidence on the wafer surface
Implementation Method 3
a heating device is regulated against a target value of the temperature of the broad side of the substrate using the actual value in order to control the temperature of the substrate
Data Source
AI summary
A substrate is coated with a multilayer structure which has layers of a first portion and layers of a second portion that are deposited on the layers of the first portion. During the deposition of at least one layer of the second portion, at least one optical measuring apparatus measures an emissivity value and a reflectance value on the broad side of the substrate, which broad side comprises the layer. Using a previously determined correction value, an actual value of a temperature of the broad side of the substrate is calculated and, using the actual value, a heating apparatus is controlled in order to control the temperature of the substrate to match a target value of the temperature of the broad side of the substrate. The correction value is determined during the deposition of the first portion, which is carried out immediately before the deposition of the second portion.