UV Irradiation Array for 450 mm Wafer Cross Talk Reduction
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Solution Overview
Problem
Existing UV lamp systems face challenges in achieving uniform and intense UV radiation coverage over larger semi-conductor wafers, such as 450 mm diameter wafers, due to 'cross talk' between multiple magnetrons, leading to reduced magnetron lifespan and difficulty in maintaining power density, especially with the increasing surface area requirements.
Innovation Solution
The solution involves an array of nine RF irradiator units, each with a single magnetron and chamber, arranged in three rows to minimize cross talk, coupled with a closed loop control for real-time power adjustments to ensure uniform UV distribution across the 450 mm diameter wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple magnetrons are used in a single cavity to treat 300 mm wafers, then the UV radiation intensity and uniformity are sufficient, but cross talk interference occurs between magnetrons leading to reduced lifespan and operational reliability
Solution Approach 1:
The single large cavity is divided into multiple separate cavities, each housing a single magnetron. This segmentation eliminates cross talk interference between magnetrons while maintaining sufficient UV radiation coverage for 450 mm wafers through the array configuration.
2Area of stationary object
If the wafer diameter is increased to 450 mm, then the surface area increases to 159,043 mm2, but maintaining the same power density requires 27 kilowatts which is difficult to achieve with existing single or dual magnetron systems
Solution Approach 1:
Multiple independent magnetron units are combined in an array configuration to achieve the cumulative power output of 27 kilowatts or more. Each magnetron contributes to the total power while operating independently in its own cavity, enabling treatment of 450 mm wafers with adequate power density.
3Area of stationary object
If the number of magnetrons is increased to cover larger wafer areas, then the coverage area increases, but the complexity of the system and control requirements increase significantly
Solution Approach 1:
The system is segmented into identical, modular magnetron units that can be independently controlled. This modularity simplifies the overall control architecture compared to managing a single complex high-power system, as each unit follows the same control protocol and can be individually adjusted.
Solution Approach 2:
The closed loop control system dynamically adjusts operational parameters of each magnetron unit based on real-time feedback from sensors. This enables uniform UV distribution across the large wafer surface by compensating for variations in distance, angle, and radiation intensity at different positions.
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 provides optimal intensity, dosage, and uniformity of UV radiation over the entire 450 mm diameter wafer, extending the life of the magnetrons and maintaining high productivity by reducing interference and ensuring consistent power delivery.
Implementation Method 1
an RF generator operable to generate a radiation energy field to excite the plasma lamp bulb and emit the ultraviolet light
Implementation Method 2
The plasma emits a characteristic spectrum of electromagnetic radiation strongly weighted with spectral lines or photons having UV and infrared wavelengths
Implementation Method 3
The openings in the metal screen transmit the UV light for irradiating a substrate positioned outside the chamber, yet substantially block the emission of RF or microwave energy
Implementation Method 4
UV lamp systems are commonly used for treating semi-conductor wafers for use in the electronics industry
Data Source
AI summary
An apparatus for generating ultraviolet light and irradiating a 450 mm diameter semi-conductor wafer. The apparatus includes a plenum and an array of nine RF irradiator units coupled with the plenum. Each irradiator unit includes a plasma lamp bulb and an RF generator operable to generate a radiation energy field to excite the plasma lamp bulb and emit the ultraviolet light. The nine irradiator units are arranged in three rows with three of the irradiator units in each row.