In-Situ UV Intensity Measurement in Semiconductor Cure Tools
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Solution Overview
Problem
Existing UV radiation treatment methods for thin films face challenges in maintaining consistent film properties due to UV lamp intensity drifts and optical part solarization, which can lead to unsuitable conditions for mass manufacturing, especially when dealing with temperature-sensitive materials like nickel silicide and copper-containing devices.
Innovation Solution
A semiconductor processing apparatus with a UV radiation assembly and a detector system that includes a UV intensity detector and a calibration substrate, allowing for real-time measurement and adjustment of UV intensity to maintain consistent treatment, while also addressing window deposits and bulb degradation through corrective actions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If UV radiation is used to cure thin films at lower temperatures, then temperature-sensitive materials are protected from damage, but UV lamp intensity drifts and optical part solarization occur over time leading to inconsistent film properties
Solution Approach 1:
The system performs preliminary calibration by measuring UV intensity with a detector before processing and comparing it to a reference value. Based on this preliminary measurement, the control system pre-adjusts lamp power or exposure time to compensate for intensity drift, ensuring consistent film properties from the start of production or after maintenance events.
Solution Approach 2:
The patent implements a feedback control system where a UV detector continuously or periodically measures the actual UV intensity reaching the substrate. This measured value is fed back to the control system, which automatically adjusts lamp power or exposure duration to maintain the desired UV dose, compensating for lamp degradation and optical part solarization in real-time.
2Reliability
If UV intensity is increased to compensate for lamp degradation, then film curing effectiveness is maintained, but damage to optical parts and solarization worsen
Solution Approach 1:
The feedback control system precisely modulates UV lamp power based on actual measured intensity, avoiding excessive compensation. By continuously monitoring UV intensity and making small, precise adjustments to lamp power, the system maintains film curing consistency while preventing overheating and damage to optical components that would result from aggressive intensity increases.
Solution Approach 2:
The system dynamically adjusts UV lamp power or exposure time based on real-time detector feedback rather than using fixed high intensity. This dynamic control allows the system to use minimal necessary UV intensity to achieve the required film properties, reducing thermal load and harmful effects on optical parts while maintaining curing effectiveness.
3Manufacturing precision
If thermal processing is used to treat thin films, then film stresses and other properties can be modified, but substrate temperatures must be high causing damage to copper containing devices and nickel silicide
Solution Approach 1:
The patent replaces thermal processing with UV radiation processing to achieve film stress control and property modification. Instead of heating the substrate to high temperatures (>400°C for nickel silicide, >500°C for general thermal treatment), the system uses UV photons to induce chemical changes and stress in the thin films at lower temperatures, protecting temperature-sensitive materials like copper interconnects and nickel silicide contacts from damage.
Solution Approach 2:
The system changes the processing parameter from temperature to UV radiation intensity and exposure time. By controlling UV dose (intensity × time) rather than substrate temperature, the patent achieves film stress control and property modification without subjecting temperature-sensitive materials to damaging high temperatures, enabling processing of copper-containing devices and nickel silicide structures.
4Reliability
If UV exposure time is extended to ensure adequate curing, then film properties are improved, but productivity decreases due to longer processing time
Solution Approach 1:
The real-time UV intensity measurement and feedback control system allows the system to maintain consistent film properties with optimized, shorter exposure times. By precisely controlling UV dose through feedback, the system achieves reliable film curing without the need for extended exposure times, thereby maintaining high productivity for mass manufacturing while ensuring adequate film property consistency.
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
Ensures consistent UV cure of thin films by compensating for intensity deviations, reducing the risk of damage to temperature-sensitive materials and enabling continuous operation without shutting down the system, thus improving wafer-to-wafer uniformity and extending equipment lifespan.
Implementation Method 1
A UV detector measures UV intensity from time to time
Implementation Method 2
A UV radiation assembly external to the process chamber. The UV radiation assembly transmits radiation into the chamber on a substrate holder through a chamber window
Implementation Method 3
one or more reflectors operable to direct a portion of the UV radiation through the window towards the substrate holder
Implementation Method 4
Irradiation of the low-k or spacer nitride films permits modulation of desired film properties such as dielectric constant or film stress at lower temperatures
Data Source
AI summary
Consistent ultraviolet (UV) intensity for a semiconductor UV cure chamber is measured in-situ with a hot pedestal in vacuum by measuring reflected UV light from a calibration substrate at a UV detector mounted in the lamp assembly. The measurement apparatus includes a UV detector, a cover that protects the detector from UV light while not in use, and a mirror disposed between the chamber window and the UV detector. Measured UV intensity from the substrate reflection and from the mirror reflection help determine a course of maintenance action to maintain wafer-to-wafer uniformity.