Shadow Ring for Laser Anneal Temperature Detection
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Solution Overview
Problem
Conventional thermal annealing processes for semiconductor substrates are inefficient, as they heat the entire substrate, leading to slow temperature ramp rates and extended exposure to high temperatures, which can cause thermal stresses and physical deformation or breakage, especially near the edges of larger substrates.
Innovation Solution
A method and apparatus that use a shadow ring or edge ring energy blocker to selectively block electromagnetic energy from reaching the substrate edges, allowing for precise temperature measurement and control, thereby preventing thermal stresses and deformation by blocking initial light while allowing emitted light to be detected for temperature determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the entire substrate is heated in conventional RTP processes, then the substrate can be uniformly heated, but the heating and cooling rates are limited by substrate size, resulting in slow temperature ramp rates
Solution Approach 1:
The patent applies local quality by using a laser beam to heat only specific regions of the substrate surface rather than heating the entire substrate. The laser energy is concentrated on localized areas, enabling rapid temperature changes in treated regions while leaving other areas at lower temperatures, thus achieving high ramp rates without being limited by overall substrate size.
2Reliability
If the substrate is held at elevated temperature for extended periods to ensure complete annealing, then annealing quality improves, but thermal stresses accumulate causing physical deformation or breakage at substrate edges
Solution Approach 1:
The patent uses local quality by applying laser energy only to specific regions requiring annealing rather than heating the entire substrate. This localized heating achieves the necessary thermal treatment in the target areas while minimizing overall substrate exposure to high temperatures, reducing thermal stress accumulation and preventing edge deformation.
Solution Approach 2:
The patent extracts the heating function from a global process and applies it only where needed. By using a laser beam that can be precisely positioned and controlled, the system delivers thermal energy only to the specific regions requiring annealing, removing the unnecessary exposure of other substrate areas to high temperatures and thereby reducing thermal stresses.
3Temperature
If scanning laser techniques are used to anneal substrate surfaces, then heating rates improve, but uniformity control becomes difficult due to overlap issues between scanned regions
Solution Approach 1:
The patent incorporates feedback mechanisms to monitor and control the laser annealing process. By measuring parameters such as substrate temperature, beam position, and processing conditions in real-time, the system can adjust laser power and scanning speed to maintain uniform annealing across the substrate surface, eliminating the uniformity problems associated with simple scanning techniques.
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 solution enables efficient and uniform thermal processing of semiconductor substrates without damaging the edges, allowing for faster temperature ramp rates and reduced exposure to high temperatures, thus improving the processing efficiency and substrate integrity.
Implementation Method 1
radiating an initial light from a light source towards a surface of a substrate, heating the substrate by exposing the surface of the substrate to the initial light
Implementation Method 2
radiating emitted light from a portion of the surface of the substrate, passing the emitted light through an energy blocker and towards a detector, such as a thermal sensor, and determining a temperature of the portion of the surface of the substrate from the emitted light with the detector or thermal sensor
Data Source
AI summary
Embodiments of the invention provide a method and an apparatus for detecting the temperature of a substrate surface. In one embodiment, a method for measuring the temperature is provided which includes exposing the surface of the substrate to a laser beam radiating from a laser source, radiating emitted light from a portion of the surface of the substrate, through the shadow ring, and towards a thermal sensor, and determining the temperature of the portion of the surface of the substrate from the emitted light. The substrate may be disposed on a substrate support within a treatment region and a shadow ring may be disposed between the laser source and the surface of the substrate. The shadow ring may be selectively opaque to the laser beam and transparent to the emitted light.