Wafer Chuck Curvature for Retaining Puddle Process Liquids
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Solution Overview
Problem
Conventional puddle processes on semiconductor substrates face challenges in maintaining complete chemical coverage and preventing processing liquids from spilling over the substrate edge due to low surface tension, hydrophobicity, and beveled edges, as well as substrate bowing or warpage.
Innovation Solution
The implementation of wafer chuck designs that reshape the substrate surface to be concave or flat, ensuring complete chemical coverage by clamping the backside center region onto a central planar region and elevating the peripheral edge region, using vacuum pressure or electrostatic charge to retain the processing liquid on the substrate surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a puddle process is performed with the substrate stationary or rotating at low speeds to reduce liquid consumption, then the amount of processing liquid needed is reduced by 50% or more, but complete chemical coverage is difficult to achieve and maintain due to liquid spilling over the substrate edge
Solution Approach 1:
The patent applies curvature by bowing the substrate surface into a concave shape using a heated chuck, which transforms the flat surface into a curved configuration that naturally retains the liquid puddle and prevents spilling over the edges, thereby achieving complete chemical coverage while maintaining low liquid consumption
Solution Approach 2:
The patent changes physical parameters by heating the chuck to a temperature between 50°C and 150°C, which modifies the substrate's mechanical properties and enables controlled bowing of the surface, creating the necessary concave shape for liquid retention without increasing liquid用量
2Stability of the object's composition
If the substrate is processed with beveled edges and hydrophobic surface, then the substrate structure is maintained, but processing liquid tends to fall off the edge due to low surface tension and hydrophobicity
Solution Approach 1:
The patent converts the harmful effect of hydrophobicity and low surface tension (which causes liquid spilling) into a beneficial outcome by using the heated chuck to create a concave surface shape that counteracts these forces, allowing the liquid to be retained despite the substrate's inherent properties
Solution Approach 2:
By inducing a concave curvature in the substrate surface through thermal processing, the patent creates a geometric configuration that naturally contains the liquid puddle, transforming the flat surface that allows spilling into a curved surface that retains liquid
3Shape
If the substrate surface is flat or convex, then the substrate maintains its natural shape, but the liquid puddle cannot be retained and spills over the substrate edge
Solution Approach 1:
The patent deliberately transforms the substrate surface from a flat or convex shape into a concave shape by heating the chuck, creating a curved configuration that naturally retains the liquid puddle and prevents spilling over the edges
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 solution ensures complete chemical coverage across the substrate surface during puddle processes, retains the liquid puddle, and prevents spillage over the substrate edge, enhancing process performance.
Implementation Method 1
using vacuum pressure or electrostatic charge to retain the processing liquid on the substrate surface
Implementation Method 2
using vacuum pressure or electrostatic charge to retain the processing liquid on the substrate surface
Implementation Method 3
liquids tend to fall off the edge of the substrate (even when the substrate is stationary), due to the low surface tension of the liquids dispensed onto the substrate
Data Source
AI summary
Improved wafer chuck designs and methods are provided herein for retaining a processing liquid on a surface of a semiconductor substrate during a puddle process. More specifically, the present disclosure provides various embodiments of wafer chucks that reshape a surface of a semiconductor substrate to ensure that the substrate surface is concave (or completely flat) before a processing liquid is dispensed onto the substrate surface to form a puddle of the processing liquid on the substrate surface. By providing the substrate surface with a concave (or completely flat) shape, the embodiments disclosed herein provide complete chemical coverage across the substrate surface during a puddle process, retain the puddle on the substrate surface and prevent the puddle from spilling over the substrate edge.