Microwave Wafer Annealing with a Susceptor for Uniform Heating
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Solution Overview
Problem
As semiconductor devices continue to integrate more components into a given area with reduced feature sizes, existing annealing processes face challenges in achieving uniform heating and risk thermal damage due to abrupt changes in electric fields near the edges of wafers.
Innovation Solution
A microwave annealing system with a susceptor having a width equal to or larger than the wafer, coupled with controlled microwave radiation and gas management, to enhance heating uniformity and reduce thermal shock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional annealing processes are used with reduced feature sizes, then integration density is improved, but heating uniformity deteriorates due to abrupt electric field changes at wafer edges
Solution Approach 1:
A susceptor is introduced as an intermediary material between the microwave radiation source and the wafer. The susceptor absorbs microwave energy and converts it to heat, which is then transferred to the wafer. This mediator approach eliminates the problem of abrupt electric field changes at wafer edges by providing a thermal coupling interface that ensures uniform heat distribution across the wafer surface, including at the edges.
Solution Approach 2:
The patent replaces conventional thermal conduction-based heating mechanisms with microwave radiation-based dielectric heating. By using microwave energy that penetrates and heats the wafer volumetrically rather than through surface conduction, the system achieves more uniform heating throughout the wafer thickness and across the surface, eliminating the edge effects that occur with traditional heating methods.
2Productivity
If higher power ramp-up rates are used to improve process efficiency, then productivity is improved, but thermal damage risk increases due to thermal stress
Solution Approach 1:
The susceptor acts as a thermal buffer and mediator that absorbs microwave energy and distributes it uniformly to the wafer. This intermediate layer prevents direct microwave-induced hot spots and allows for higher power ramp-up rates because the susceptor's thermal mass and uniform heat distribution characteristics reduce thermal gradients and stress in the wafer, thereby preventing thermal damage even at higher power levels.
3Manufacturing precision
If microwave radiation is used to improve heating uniformity, then manufacturing precision is improved, but device complexity increases due to susceptor requirements
Solution Approach 1:
The susceptor is designed with homogeneous material properties that ensure uniform microwave absorption and heat distribution across the entire wafer surface. By using materials with consistent dielectric and thermal properties throughout, the system achieves uniform heating without requiring complex susceptor geometries or multi-zone control mechanisms, thereby maintaining simplicity while improving heating uniformity.
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
Improves heating uniformity across wafers, reduces the risk of thermal damage, and enhances process efficiency by allowing higher power ramp-up rates without increasing thermal stress.
Implementation Method 1
using microwave radiation to heat the wafer and the susceptor
Implementation Method 2
The susceptor may include a first region adjacent to a second region, wherein the first region has a first dissipation factor and the second region has a second dissipation factor
Data Source
AI summary
A method includes placing a wafer on a susceptor, wherein the wafer has a first radius, wherein a top surface of the susceptor has a second radius that is greater than the first radius; using microwave radiation to heat the wafer and the susceptor; and removing the wafer from the susceptor.