Wafer Heating Block With Deformable Supports for Warpage Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Increased warpage of wafers in semiconductor manufacturing leads to uneven temperature distribution during heating processes, causing quality issues and a high risk of defects, particularly in ashing processes, due to uneven heat transfer rates.
Innovation Solution
An apparatus with a heater and a heating block featuring support protrusions that deform in response to heat, with a curved upper surface and varying thickness, includes stretchable and unstretchable protrusions made of different materials to uniformly distribute heat across the wafer, reducing warpage-induced temperature differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a wafer with warpage is heated using a conventional heater, then the wafer can be heated, but the heat transfer rate distribution between wafer and heater becomes uneven, causing temperature difference between central portion and edge
Solution Approach 1:
The heating block incorporates support protrusions with different heights at different locations (central portion vs. edge), creating local variations in the heating interface. This local quality adjustment compensates for wafer warpage by ensuring better thermal contact at the central portion where the protrusions are taller, thereby improving heat transfer rate distribution and reducing temperature differences across the wafer surface
Solution Approach 2:
The upper surface of the heating block is designed with a curved shape featuring a concave central portion, which corresponds to the typical dome-shaped warpage of wafers. This curvature enables the heating block to conform to the warped wafer surface, improving thermal contact and heat transfer uniformity across the entire wafer area, thereby resolving the temperature distribution issue
2Temperature
If support protrusions are made uniformly deformable, then heat distribution improves, but control over differential thermal expansion becomes difficult
Solution Approach 1:
The support protrusions are constructed with different material compositions depending on their location. Central support protrusions use a first material with specific thermal expansion characteristics, while edge support protrusions use a second material with different properties. This local differentiation in material quality allows each region to compensate for its specific thermal deformation needs, achieving better overall heat distribution while maintaining controllable differential thermal expansion
Solution Approach 2:
The heating block utilizes composite material construction for the support protrusions, combining materials with different thermal expansion coefficients in specific locations. This composite approach enables the structure to accommodate differential thermal expansion across the heating block while maintaining effective thermal contact with the wafer, thereby improving heat distribution uniformity without excessive device complexity
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 apparatus achieves a temperature difference reduction of about 1°C across the wafer, improving heat transfer and reducing ashing process defects by up to 75%.
Implementation Method 1
at least the support protrusion at the central portion of the heating block, among the plurality of support protrusions, is deformed in response to heating by the heater
Implementation Method 2
a heater; a heating block on an upper surface of the heater
Data Source
AI summary
An apparatus for heating a wafer includes a heater, a heating block on an upper surface of the heater, and a plurality of support protrusions protruding from an upper surface of the heating block, wherein the upper surface of the heating block has a curved shape with a concave central portion, and at least the support protrusion at the central portion of the heating block, among the plurality of support protrusions, is configured to be deformed in response to heating by the heater.