Far-Edge Wafer Pyrometer Alignment for Uniform CVD Temperature
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Solution Overview
Problem
Existing semiconductor processing methods, particularly chemical vapor deposition (CVD), face challenges in accurately measuring and controlling wafer temperatures, especially at the far edge, leading to nonuniform temperature distributions and potential defects in epitaxial films due to localized heating by infrared lamps.
Innovation Solution
A reactor system with a pyrometer mounting assembly and alignment jig is used to support multiple pyrometers for precise measurement of center and edge wafer temperatures, employing a smaller field of view for the edge pyrometer and a fiber optic sensor to ensure accurate alignment, allowing for uniform temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If radiant heating with infrared lamps is used to heat wafers, then heating efficiency is improved, but nonuniform temperature distribution and localized hot spots occur on the substrate surface
Solution Approach 1:
The heating system is segmented into multiple independent infrared lamp zones positioned at different locations (front, center, rear) around the reaction chamber. Each zone can be independently controlled to provide localized heating, allowing compensation for temperature nonuniformities and hot spots while maintaining overall heating efficiency.
Solution Approach 2:
Different regions of the reaction chamber receive different heating intensities through independently controlled lamp zones. The system applies local quality control by adjusting the radiant heating intensity in specific areas to achieve uniform temperature distribution across the substrate surface, rather than applying uniform heating throughout.
2Measurement precision
If multiple pyrometers are used to measure center and edge wafer temperatures, then temperature measurement precision is improved, but device complexity increases
Solution Approach 1:
The pyrometer mounting assembly serves multiple functions: it provides mechanical support for multiple pyrometers, enables precise positioning and alignment of each pyrometer with its target location (center or edge of wafer), and allows for temperature measurements at multiple locations simultaneously. This multi-functional design achieves comprehensive temperature monitoring without proportionally increasing system complexity.
3Measurement precision
If an alignment jig with fiber optic sensor is used to align the edge pyrometer, then alignment precision is improved, but device complexity increases
Solution Approach 1:
A fiber optic sensor acts as an intermediary tool in the alignment process. The sensor detects the wafer edge position and provides feedback information to guide the positioning of the edge pyrometer. This intermediary mechanism enables precise alignment without requiring complex mechanical alignment fixtures or manual adjustment procedures.
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 system provides accurate and repeatable measurement of wafer temperatures, reducing thermal gradients and improving the quality of deposited films by ensuring uniform temperature distribution across the wafer.
Implementation Method 1
a pyrometer adapted to measure a center wafer temperature and an edge pyrometer adapted to measure a far edge wafer temperature
Implementation Method 2
The edge sensor may be oriented by the slot in the alignment jig to receive a signal through a second transmission channel, offset a predefined distance from the first transmission channel, in the lamp bank into the reaction chamber
Implementation Method 3
Radiant heating generally involves positioning infrared lamps around a reaction chamber or reactor containing the substrate upon which material is to be deposited
Data Source
AI summary
A reactor system designed to provide accurate monitoring of wafer temperatures during deposition steps. The reactor system includes a pyrometer mounting assembly supporting and positioning three or more pyrometers (e.g., infrared (IR) pyrometers) relative to the reaction chamber to measure a center wafer temperature and an edge wafer temperature as well as reaction chamber temperature. The pyrometer mounting assembly provides a small spot size or temperature sensing area with the edge pyrometer to accurately measure edge wafer temperatures. A jig assembly, and installation method for each tool setup, is provided for use in achieving accurate alignment of the IR pyrometer sensing spot (and the edge pyrometer) relative to the wafer, when the pyrometer mounting assembly is mounted upon a lamp bank in the reactor system or in tool setup. The wafer edge temperature sensing with the reactor system assembled with proper alignment ensures accurate and repeatable measurement of wafer temperatures.