Multi-Mode Microwave Annealing for Semiconductor Wafer Uniformity
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Solution Overview
Problem
Microwave annealing in semiconductor manufacturing faces challenges in achieving uniformity and efficiency due to the limitations of existing microwave frequencies and equipment, particularly with the higher costs and lower efficiency of 5.8 GHz magnetrons compared to 2.45 GHz systems, which affects the production capacity and yield of silicon wafers.
Innovation Solution
A multi-mode microwave heating device using the common industrial frequency of 2.45 GHz, with a method that adjusts the capacitance of half-wave-rectified power supplies to extend microwave power pulse bandwidth, producing multiple overlapped couplings and exciting multiple microwave modes in the heating chamber to achieve uniform heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If 5.8 GHz magnetron is used for microwave annealing, then standing-wave effects are suppressed and annealing 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 introduces multi-mode operation by adjusting cavity dimensions and using mode coupling techniques. This allows the system to achieve uniform heating at the lower frequency by exciting multiple resonant modes simultaneously, resolving the contradiction between frequency and heating uniformity while maintaining production capacity.
Solution Approach 2:
The patent introduces dynamic control of microwave modes by adjusting cavity dimensions and using mode coupling techniques. The system dynamically switches between different microwave modes (TE101, TE201, TE011, etc.) to maintain uniform heating distribution, replacing the static high-frequency approach with a dynamic multi-mode control strategy at 2.45 GHz.
2Manufacturing precision
If 5.8 GHz magnetron is used for microwave annealing, then standing-wave effects are suppressed and annealing uniformity is improved, but efficiency decreases
Solution Approach 1:
The patent changes the operating frequency from 5.8 GHz to 2.45 GHz and compensates for the longer wavelength by exciting multiple microwave modes simultaneously. This parameter change, combined with mode coupling techniques, maintains heating efficiency while achieving uniform annealing, resolving the contradiction between frequency and energy efficiency.
Solution Approach 2:
The patent segments the heating process into multiple microwave modes (TE101, TE201, TE011, etc.) that are excited simultaneously. Each mode contributes to the overall heating pattern, and their combined effect achieves uniform heating distribution without requiring high frequency, thereby maintaining energy efficiency.
3Productivity
If 2.45 GHz magnetron is used for microwave annealing, then cost decreases and efficiency increases, but heating uniformity deteriorates due to standing-wave effects
Solution Approach 1:
The patent introduces dynamic multi-mode control at 2.45 GHz, where multiple microwave modes are excited and controlled to adapt to different heating requirements. This dynamic approach eliminates standing-wave patterns by distributing energy across multiple modes, achieving both cost efficiency and heating uniformity.
Solution Approach 2:
The patent creates a composite heating field by combining multiple microwave modes (TE101, TE201, TE011, etc.) at 2.45 GHz. The superposition of these modes produces a uniform energy distribution pattern, effectively eliminating standing-wave effects while maintaining the cost and efficiency advantages of 2.45 GHz operation.
4Loss of energy
If 2.45 GHz magnetron is used for microwave annealing, then cost decreases and efficiency increases, but heating uniformity deteriorates due to standing-wave effects
Solution Approach 1:
The patent segments the microwave heating field into multiple independent modes (TE101, TE201, TE011, etc.) at 2.45 GHz. By controlling and combining these segmented modes, the system achieves uniform energy distribution while maintaining high heating efficiency, resolving the contradiction between efficiency and uniformity.
Solution Approach 2:
The patent creates a composite microwave field structure by superimposing multiple modes at 2.45 GHz. This composite approach distributes energy uniformly throughout the heating chamber while maintaining the efficiency advantages of 2.45 GHz operation, eliminating standing-wave effects through constructive interference patterns.
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 enhances both the efficiency and uniformity of microwave heating, reducing annealing time and sheet resistance while minimizing heating ununiformity, thereby improving the production capacity and yield of semiconductor devices.
Implementation Method 1
Provide a plurality of half-wave-rectified power supplies to connect the microwave transmitters
Implementation Method 2
the half-wave-rectified power supplies have capacitances respectively. Adjust the value of the capacitance of half-wave-rectified power supply
Implementation Method 3
Arrange a plurality of microwave transmitters outside the heating chamber to transmit microwave into the heating chamber
Implementation Method 4
exciting multiple microwave modes in the heating chamber
Implementation Method 5
Install a plurality of longitudinal waveguides and a plurality of transverse waveguides in between the heating chamber and the microwave transmitters
Implementation Method 6
exciting multiple microwave modes in the heating chamber
Implementation Method 7
Shrink in wavelength of commercialized microwave anneal equipment leads to suppression of standing-wave effects
Data Source
AI summary
An operating method of microwave heating device is provided, in which a holder is disposed in a heating chamber, and a plurality of microwave transmitters are arranged outside the heating chamber. A plurality of half-wave-rectified power supplies are provided to connect the microwave transmitters, and the half-wave-rectified power supplies have capacitances respectively. A plurality of longitudinal waveguides and a plurality of transverse waveguides are installed in between the heating chamber and the microwave transmitters. The capacitance of each of the capacitors of the half-wave-rectified power supplies is adjusted, such that the microwave power pulse bandwidth of the microwave transmitters are extended to produce a plurality of overlapped couplings. The half-wave-rectified power supplies supply power to the microwave transmitters, so that the microwaves are guided into the heating chamber by the longitudinal waveguides and the transverse waveguides for exciting multiple microwave modes in the heating chamber.