Multi-mode Microwave Heating Device for Semiconductor Annealing
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Solution Overview
Problem
Microwave anneal processes in semiconductor manufacturing face challenges in achieving uniformity and efficiency due to the high cost and lower efficiency of commercialized 5.8 GHz magnetrons, which are required for suppressing standing-wave effects, whereas the common industrial frequency of 2.45 GHz is more efficient but not typically used for semiconductor annealing.
Innovation Solution
A multi-mode microwave heating device utilizing 2.45 GHz frequency, incorporating a heating chamber, a holder, a rotating and elevating mechanism, multiple microwave transmitters, and both longitudinal- and transverse-polarized rectangular waveguides to excite specific cavity modes, ensuring uniform and efficient heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If 5.8 GHz magnetron is used to suppress standing-wave effects, then heating uniformity is improved, but cost increases and efficiency decreases
Solution Approach 1:
The patent changes the microwave frequency parameter from 5.8 GHz to 2.45 GHz, and simultaneously changes the cavity mode configuration from single-mode to multi-mode (combining TE101, TE102, and TM010 modes). This parameter transformation allows the system to achieve uniform heating at lower frequency with improved efficiency by distributing the heating pattern across multiple modes rather than relying on high frequency single-mode operation.
2Manufacturing precision
If 5.8 GHz magnetron is used to suppress standing-wave effects, then heating uniformity is improved, but device cost increases
Solution Approach 1:
The patent transforms the operating frequency parameter from 5.8 GHz to the more common and cost-effective 2.45 GHz, while compensating for the potential standing-wave issues by introducing multi-mode excitation. This parameter change enables the use of standard, readily available magnetrons and waveguide components at 2.45 GHz, significantly reducing device cost while maintaining heating uniformity through the combined multi-mode approach.
3Power
If 2.45 GHz frequency is used to improve efficiency, then power efficiency is improved, but standing-wave effects increase reducing heating uniformity
Solution Approach 1:
The patent merges multiple cavity modes (TE101, TE102, and TM010 modes) into a single heating system operating at 2.45 GHz. By combining these different modes with complementary field distributions, the system creates a composite heating pattern that covers the substrate uniformly, compensating for the standing-wave effects that would otherwise be present at the lower frequency, thereby achieving both efficiency and uniformity.
4Manufacturing precision
If multi-mode excitation is used to achieve uniform heating at 2.45 GHz, then heating uniformity is improved, but device complexity increases
Solution Approach 1:
The patent segments the microwave heating function into multiple independent waveguide-transmitter units, each capable of exciting a specific cavity mode (TE101, TE102, or TM010). This modular segmentation allows for independent control and optimization of each mode-contributing element, simplifying the overall control architecture while achieving complex multi-mode heating patterns that would be difficult to implement with a single complex transmitter.
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 device achieves efficient and uniform microwave heating by exciting multiple cavity modes, improving production capacity and yield of silicon wafers without the need for high-cost equipment, thus overcoming the limitations of existing microwave anneal technologies.
Implementation Method 1
The microwave transmitters connect to the heating chamber through the longitudinal-polarized rectangular waveguides and through transverse-polarized rectangular waveguides for transmitting the microwaves into the heating chamber
Implementation Method 2
exciting multiple cavity modes of the heating chamber
Implementation Method 3
achieve uniform microwave heating
Data Source
AI summary
A multi-mode microwave heating device includes a heating chamber, a plurality of microwave transmitters, a plurality of longitudinal-polarized rectangular waveguides, a plurality of transverse-polarized rectangular waveguides, and a plurality of half-wave-rectified power supplies. The heating chamber has a holder for holding a to-be-heated object. The holder is connected to a rotating and an elevating mechanism. The microwave transmitters are connected to the heating chamber through the longitudinal-polarized rectangular waveguides as well as connected to the transverse-polarized rectangular waveguides for transmitting microwaves into the heating chamber and to excite multiple cavity modes of the heating chamber, so as to achieve uniform microwave heating. An industrial three-phase alternating current (AC) power source offers multi-phased electricity to the half-wave-rectified power supplies, by which the microwave transmitters are powered, such that the multiple modes are decoupled and uniform microwave heating are achieved.