Wafer Edge Protective Coating for Clean Photoresist Patterning
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Solution Overview
Problem
Existing resist coating methods contaminate the edges and backside of semiconductor wafers, leading to contamination-related issues, poor yield, and inefficiencies in lithography processes due to resist residual and undesired humps.
Innovation Solution
A protective layer is applied to the edge portion of the wafer using a chemical solution containing acid-labile groups, thermal acid generators, and a solubility control unit, which is selectively coated and cured to form a polymer material that prevents resist material deposition, followed by coating a photoresist layer on the front surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If existing resist coating methods (spin coating) are used to coat the wafer, then the resist material is formed on all regions of the wafer including edges and backside surface, but this leads to contamination of the coater chuck and track, and creates resist residual on wafer edges
Solution Approach 1:
The coating process is segmented into two distinct stages: first applying a protective layer to the edge portion, then applying the resist layer to the front surface. This segmentation prevents the resist from contacting the edge and backside, eliminating contamination while maintaining complete resist coverage on the active area.
Solution Approach 2:
A protective layer acts as an intermediary between the coating system and the wafer edge. This intermediate layer receives the resist coating material during application, preventing direct contact between the resist and the wafer edge/backside, thereby eliminating contamination while allowing complete resist coverage on the front surface.
2Quantity of substance
If resist material is coated on all regions including edges and backside, then complete coverage is achieved, but patterning stability is disturbed and erroneous leveling readings occur
Solution Approach 1:
The wafer surface is segmented into two zones with different coating treatments: the edge portion receives only the protective layer while the front surface receives both protective and resist layers. This ensures uniform resist thickness and proper leveling only on the active patterning area, eliminating patterning stability issues.
Solution Approach 2:
Different regions of the wafer are given different coating qualities: the edge portion has a protective layer with specific properties that prevent resist adhesion, while the front surface has the full resist coating with optimized thickness and uniformity for high-precision patterning.
3Object-affected harmful factors
If edge bead rinse or backside rinse is used to remove resist from edges, then contamination is reduced, but undesired humps are created which become defect sources
Solution Approach 1:
The protective layer is applied to the edge portion before the resist coating step. This preliminary action prevents resist material from adhering to the edge and backside in the first place, eliminating the need for subsequent rinsing operations that would create humps and defects.
4Manufacturing precision
If additional coating is performed to address resist residual, then patterning quality is improved, but contamination to wafers and lithography system increases and manufacturing throughput decreases
Solution Approach 1:
The protective layer is applied in advance to the edge portion before the main resist coating. This preliminary protective measure prevents resist residual and contamination issues from occurring, eliminating the need for additional corrective coating steps and maintaining high manufacturing throughput.
Solution Approach 2:
The problematic resist coating on the edge and backside is extracted or removed by replacing it with a protective layer that has different properties. This allows the main resist coating to be applied cleanly to only the front surface, improving patterning quality without requiring additional processing steps.
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 protective layer effectively prevents resist material from adhering to the edge and backside of the wafer, reducing contamination, improving patterning stability, and enhancing manufacturing throughput by minimizing defects and improving yield.
Implementation Method 1
the chemical solution is spin coated over the edge portion of the semiconductor substrate and cured to form a protective layer
Implementation Method 2
chemical solution containing acid-labile groups, thermal acid generators, and a solubility control unit
Implementation Method 3
the chemical solution is spin coated over the edge portion of the semiconductor substrate
Data Source
AI summary
A method of manufacturing a semiconductor device includes forming a first protective layer over an edge portion of a first main surface of a semiconductor substrate. A metal-containing photoresist layer is formed over the first main surface of the semiconductor substrate. The first protective layer is removed, and the metal-containing photoresist layer is selectively exposed to actinic radiation. A second protective layer is formed over the edge portion of the first main surface of the semiconductor substrate. The selectively exposed photoresist layer is developed to form a patterned photoresist layer, and the second protective layer is removed.