Wafer Chuck Ventilation Apertures for Plasma Etching Temperature Control
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Solution Overview
Problem
The semiconductor industry faces challenges in achieving uniform critical dimension (CD) uniformity during plasma etching due to local temperature gradients on semiconductor wafers, leading to varying etching rates and non-uniformity across the wafer surface.
Innovation Solution
A method and apparatus that utilize a wafer chuck with strategically arranged ventilation apertures and a cooling gas supply system to control wafer temperature by directing cooling gas to the backside of the wafer, ensuring uniform heat dissipation and preventing temperature variations across the wafer diameter, thereby maintaining consistent etching rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma etching is performed without backside cooling, then the process is simple, but local temperature gradients cause non-uniform etching rates and poor CD uniformity
Solution Approach 1:
The wafer chuck is segmented with multiple ventilation apertures distributed across its surface, allowing cooling gas to be delivered to multiple locations simultaneously. This segmented approach enables uniform temperature control across the entire wafer backside without requiring a complex distributed cooling system at each point.
Solution Approach 2:
A cooling gas (such as nitrogen or helium) is introduced as an intermediary substance between the wafer and the cooling system. The gas flows through ventilation apertures in the wafer chuck to reach the wafer backside, acting as a heat transfer medium that efficiently removes heat from the wafer without requiring direct thermal contact between the wafer and solid cooling components.
2Productivity
If wafer temperature is not controlled during plasma etching, then the process is simpler, but etching rates vary across the wafer surface
Solution Approach 1:
Cooling gas is supplied to the wafer backside before and during the plasma etching process to preemptively prevent temperature rise. By applying cooling action in advance and continuously during etching, the wafer temperature is maintained at a controlled level, ensuring consistent etching rates across the wafer surface throughout the process.
Solution Approach 2:
The cooling system utilizes pneumatic flow of gas through ventilation apertures in the wafer chuck. The gas flow is controlled to deliver cooling precisely where needed on the wafer backside, using pressure-driven flow to ensure uniform distribution of cooling across the wafer surface without requiring mechanical moving parts.
3Reliability
If cooling gas is supplied through the wafer chuck, then wafer temperature control is achieved, but additional system components are required
Solution Approach 1:
The wafer chuck serves multiple functions: it holds the wafer during processing, provides electrical grounding, and acts as a gas distribution manifold for cooling. By making the wafer chuck multi-functional, the patent eliminates the need for separate cooling plates or thermal contact components, reducing overall system complexity while maintaining reliable temperature control.
Solution Approach 2:
The wafer chuck structure itself is designed to facilitate cooling by incorporating ventilation apertures directly into it. The chuck serves its own cooling function through its structural design, eliminating the need for external dedicated cooling mechanisms. The gas supply system connects to the chuck, and the chuck's aperture pattern automatically distributes the cooling gas across the wafer backside.
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 enhances CD uniformity, improves electrical parameters of semiconductor devices, reduces manufacturing costs, and minimizes exposure loading in lithography processes, achieving improved Isat sigma and VT sigma by 17% and 15%, respectively.
Implementation Method 1
supplying a cooling gas to a backside of the semiconductor wafer
Data Source
AI summary
A method for processing a semiconductor wafer is provided. The method includes placing a semiconductor wafer on a wafer chuck. The method further includes performing a process over the wafer. The method also includes supplying a cooling gas to the backside of the semiconductor wafer via a groove and a number of ventilation apertures located in the groove. Two of the neighboring ventilation apertures are separated in a circumferential direction relative to the center of the wafer chuck by a predetermined angle that is less than 90 degrees.