Quartz Window Anti-Reflective Coating for Uniform Wafer Flash Heating
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Solution Overview
Problem
Existing flash lamp annealing methods face challenges such as light reflection at the quartz window of the chamber, leading to reduced light impingement on the semiconductor wafer, non-uniform temperature distribution, and increased power consumption, which hinder achieving low thermal history and uniform heating.
Innovation Solution
The heat treatment apparatus incorporates an anti-reflective film on the quartz parts, particularly the upper chamber window, to reduce light reflection and enhance light transmission, ensuring uniform temperature distribution and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If light irradiation is used for heating substrate, then heating speed is improved, but light reflection at quartz window reduces heating efficiency
Solution Approach 1:
The patent applies an anti-reflective film on the quartz window to convert the harmful reflection effect into a beneficial one by reducing light reflection and increasing light transmission, thereby improving heating efficiency and reducing energy loss
Solution Approach 2:
The patent changes the optical parameters of the quartz window by coating it with an anti-reflective film, which modifies the reflection and transmission characteristics of light at the quartz window interface, thereby improving light utilization efficiency
2Temperature
If flash irradiation is used to achieve low thermal history, then diffusion of impurities is suppressed, but uniformity of temperature distribution is impaired
Solution Approach 1:
The patent applies anti-reflective film treatment to specific regions of the quartz window, particularly targeting areas that correspond to cold spots on the substrate, to locally enhance light transmission and compensate for non-uniform temperature distribution
Solution Approach 2:
The patent uses temperature distribution feedback to determine the optimal placement and design of anti-reflective film regions on the quartz window, creating a closed-loop system that compensates for cold spots and improves overall temperature uniformity
3Temperature
If preheating temperature is reduced to achieve lower thermal history, then jump temperature during flash irradiation must be increased, but light reflection reduces the amount of light impinging on substrate
Solution Approach 1:
The anti-reflective film converts the harmful reflection effect into a benefit by maximizing light transmission through the quartz window, ensuring that the full power of the light source is utilized for heating the substrate, thereby achieving the required jump temperature with lower overall power consumption
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 anti-reflective film improves light impingement on the semiconductor wafer, especially in regions with lower temperatures, resulting in more uniform temperature distribution and lower power consumption, thus achieving a lower thermal history.
Implementation Method 1
flashes of light are reflected at an interface of a quart window of a chamber which is present between the flash lamps and a semiconductor wafer
Implementation Method 2
an anti-reflective film is formed on a quart part provided between the heating light source and the substrate held by the holder
Implementation Method 3
The wavelength of light emitted from the xenon flash lamps is shorter than that of light emitted from conventional halogen lamps, and approximately coincides with a fundamental absorption band of a silicon semiconductor wafer. Thus, when a semiconductor wafer is irradiated with a flash of light emitted from the xenon flash lamps, the temperature of the semiconductor wafer can be raised rapidly
Implementation Method 4
The xenon flash lamps have a spectral distribution of radiation ranging from ultraviolet to near-infrared regions
Data Source
AI summary
An anti-reflective film is formed on upper and lower surfaces of an upper chamber window which is one quartz part provided between a semiconductor wafer held in a chamber by a holder and flash lamps provided over the chamber. The anti-reflective film is composed of a multi-layer combination of multiple types of dielectric films. The anti-reflective film reduces the reflectance of light in a wavelength range including at least a target wavelength when the target wavelength is a wavelength component such that an intensity relative to a maximum peak which has the highest intensity is not less than 0.1 in a spectrum of the flash lamps. The formation of the anti-reflective film on the upper chamber window made of quartz reduces the reflectance of flashes of light at the upper and lower surfaces of the upper chamber window to suppress the reflection of light at the interfaces.