Wafer Heater Inversion for Uniform Temperature Control
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Solution Overview
Problem
Current semiconductor wafer processing methods face challenges with non-uniform heat distribution and abrupt chemical gas expansion, leading to pattern damage and inefficient chemical reactions due to direct heating of chemical materials, which limits temperature control and reaction rates.
Innovation Solution
A system and method for heating semiconductor wafers using a wafer heater that covers the entire surface, allowing for direct and controlled heating of the wafer to achieve uniform or differential temperature profiles, avoiding the expansion issues by heating the wafer rather than the chemical materials, and utilizing a supplementary heater for finer control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If overhead heater is used to heat chemical layer on wafer, then chemical reactions can be boosted, but non-uniform heat distribution occurs across the wafer
Solution Approach 1:
Instead of heating the chemical layer from above (conventional method), the patent inverts the approach by heating the wafer substrate from below. This causes heat to conduct upward through the wafer to the chemical layer, achieving more uniform temperature distribution across the entire wafer surface while maintaining the required reaction temperature.
Solution Approach 2:
The wafer substrate acts as an intermediary heat transfer medium. The heating element heats the wafer, which then conducts heat uniformly to the chemical layer on top. This intermediary approach ensures even heat distribution compared to direct overhead heating of the chemical layer.
2Productivity
If chemical materials are heated directly to boost reaction rate, then reaction efficiency improves, but abrupt phase change causes pattern damage and volume expansion
Solution Approach 1:
The wafer substrate serves as an intermediary heating medium that conducts heat to the chemical layer indirectly. This prevents direct heating of the chemical materials, avoiding abrupt phase changes and volume expansion that cause pattern damage, while still achieving the desired reaction temperature through thermal conduction.
Solution Approach 2:
By heating the wafer substrate first before the chemical layer reaches its boiling point, the system prevents sudden phase changes. The gradual heat conduction through the wafer cushions against abrupt temperature spikes in the chemical materials, preventing pattern collapse.
3Temperature
If chemical materials are heated past boiling point, then reaction temperature can be achieved, but temperature control becomes difficult during phase change
Solution Approach 1:
The wafer substrate acts as a thermal buffer and intermediary that provides stable, uniform heat conduction to the chemical layer. This indirect heating method allows for precise temperature control without the complications of direct chemical heating during phase transitions.
Solution Approach 2:
The patent changes the heating parameter from direct chemical layer heating to substrate heating. This parameter change enables continuous temperature control without the plateau effect caused by phase changes, as the wafer substrate can be heated uniformly without undergoing phase transitions itself.
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 precise temperature control, prevents pattern collapse, and enhances chemical reaction rates by allowing heating beyond the boiling point of chemicals without phase change issues, resulting in more uniform and efficient wafer processing.
Implementation Method 1
the heat is directly supplied to the layer formed on the wafer by an overhead heater located above the wafer, and thereby, to the wafer below
Implementation Method 2
some are configured to move over the wafer surface, and some are fixed
Implementation Method 3
the chemical material may need to be heated up past its boiling point for various reasons, at which the material changes from liquid to gas
Implementation Method 4
the abrupt, dramatic volume expansion of the chemical gas following the liquid-gas phase change
Data Source
AI summary
Disclosed are a method and a system for processing wafers in fabricating a semiconductor device where disposing chemicals and wafer heating are needed for chemical reaction. A wafer is placed above a wafer heater such that a second surface faces the wafer heater, and heated from the second surface. A chemical layer is formed on an opposing first surface. The wafer heater is sized and configured to be capable of heating the entire second surface, and adapted to produce a locally differential temperature profile if needed. During heating, an actual temperature profile on the wafer may be monitored and transmitted to a computing system, which may generate a target temperature profile and control the wafer heater to adjust local temperatures on the wafer according to the target temperature profile. A supplemental heater for heating the chemicals may be used for finer control of the wafer temperature.