Acousto-Optic Modulator Scanning Beam for Semiconductor CD Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current semiconductor processing technologies face challenges in achieving tight uniformity of process parameters, such as critical dimension (CD) and overlay (OL), especially with the reduction of feature sizes and increasing wafer sizes, requiring secondary adjustments to primary processes like photolithographic exposure and etching to maintain process control.
Innovation Solution
The use of scanning beams of light, particularly UV or infrared, for secondary adjustments in semiconductor manufacturing, employing mechanical or electro-optical scanning devices like spinning multi-faceted mirrors, galvanometer scanners, or acousto-optic modulators to provide precise energy deposition across substrates, avoiding the limitations of projected light energy sources like excimer lasers with slow pulse rates and high thermal risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If projected light energy sources like excimer lasers are used for secondary adjustments, then energy deposition can be achieved, but the pulse rate is slow and thermal risks increase
Solution Approach 1:
The patent replaces mechanical scanning systems with acousto-optic modulators (AOMs) that use sound waves to diffract and modulate light beams. This substitution enables rapid pulse rate control without mechanical moving parts, directly resolving the contradiction between achieving sufficient energy deposition and maintaining high productivity through fast pulse rates.
Solution Approach 2:
The patent changes the operational parameters by using continuous wave lasers combined with AOM-based pulse modulation instead of traditional pulsed excimer lasers. This allows dynamic control of pulse duration and frequency, enabling both sufficient energy deposition per pulse and high overall pulse rates, thus simultaneously improving power delivery and productivity.
2Power
If projected light energy sources are used, then energy deposition can be achieved, but thermal-induced alterations increase
Solution Approach 1:
The patent employs periodic pulsed action through AOM modulation of continuous wave lasers, delivering energy in precisely controlled short bursts. This periodic delivery allows the substrate to cool between pulses, preventing cumulative thermal buildup and thermal-induced alterations while still achieving the required total energy deposition for secondary adjustments.
Solution Approach 2:
The patent uses continuous wave lasers that are modulated by AOMs, maintaining continuous availability of laser energy while controlling its delivery in pulses. This continuity ensures that energy deposition can proceed without interruption or delays associated with traditional pulsed laser cooling periods, achieving both sufficient power delivery and thermal management.
3Manufacturing precision
If feature sizes are reduced through scaling, then manufacturing precision can be improved, but maintaining CD uniformity becomes increasingly challenging
Solution Approach 1:
The patent applies local quality by enabling spatially selective energy deposition through scanned light beams and AOM-based modulation. Different regions of the substrate can receive customized energy doses to compensate for local variations in process parameters, thereby maintaining CD uniformity across the entire wafer even as feature sizes are reduced and process variations become more significant.
Solution Approach 2:
The patent implements feedback control by using the scanned beam approach with AOM modulation to apply corrective energy deposition based on measured process variations. The system can respond to detected CD deviations by adjusting the energy delivery pattern, creating a closed-loop control mechanism that maintains CD uniformity despite scaling challenges.
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 enables rapid and precise energy input to substrates, improving CD control and productivity while minimizing thermal-induced alterations, allowing for tighter CD control and higher throughput in semiconductor manufacturing.
Implementation Method 1
a scanning beam of light is used for the purpose of energy deposition onto a substrate
Implementation Method 2
employing mechanical or electro-optical scanning devices like spinning multi-faceted mirrors, galvanometer scanners, or acousto-optic modulators to provide precise energy deposition across substrates
Data Source
AI summary
A method and apparatus for treating a substrate and, in particular, making secondary adjustments to the results of a primary process applied to the substrate, leading to improved uniformity of the overall process, in which a substrate is positioned on a substrate holder; a scanning a beam of light is directed onto the surface of the substrate; and the amplitude of the scanned beam is varied by location based on a substrate signature.