Wafer Backside Liquid Heating for Uniform Etching Temperature
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Solution Overview
Problem
Temperature fluctuations across wafers during etching processes lead to poor process control and etching uniformity, especially on larger 450 mm wafers, due to the use of high-temperature reactants and traditional etching methods.
Innovation Solution
Preheating or precooling the wafer before dispensing heated etchants using a controlled temperature-regulating system to minimize temperature variations and enhance uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional etching methods with high-temperature reactants are used, then etching capability is achieved, but temperature fluctuations across the wafer increase leading to poor process control
Solution Approach 1:
The wafer is preheated to a predetermined temperature before the etching process begins. This preliminary temperature conditioning ensures that the wafer is at the optimal temperature when etching reactants are introduced, preventing temperature fluctuations during etching and achieving uniform etching across the wafer surface.
Solution Approach 2:
A temperature sensor continuously monitors the wafer temperature during the preheating and etching processes. The controller receives this temperature feedback and dynamically adjusts the heating power to maintain the wafer at the predetermined temperature, thereby eliminating temperature fluctuations and ensuring consistent etching uniformity.
2Productivity
If heated etchants are dispensed directly onto the wafer, then etching reaction is initiated, but temperature variations across the wafer surface increase
Solution Approach 1:
The wafer is preheated to the target temperature before heated etchants are dispensed. This preliminary temperature preparation ensures that when the etchants contact the wafer, minimal temperature variation occurs, maintaining both high etching rate and excellent temperature uniformity across the wafer surface.
Solution Approach 2:
The temperature sensor continuously monitors wafer temperature during etchant dispensing, and the controller adjusts heating power in real-time to compensate for any temperature changes caused by etchant contact, thereby maintaining temperature uniformity while sustaining high etching productivity.
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 method effectively regulates and controls temperature, reducing fluctuations and achieving better etching uniformity across the wafer by rapidly ramping temperature.
Implementation Method 1
dispensing a liquid from a center of the wafer to an edge of the wafer to control a temperature of the wafer
Implementation Method 2
etching an etch layer of the wafer with an etchant during or after dispensing the liquid
Data Source
AI summary
A method includes adjusting a temperature of a liquid; after adjusting the temperature of the liquid, dispensing the liquid onto a backside of a wafer by progressively moving a dispensing position from a center of the wafer toward a peripheral edge of the wafer; etching a target layer on a front side of the wafer using an etchant.