CdTe Substrate Surface Treatment for Epitaxial Growth
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Solution Overview
Problem
CdTe-based semiconductor substrates experience surface oxidation and linear polishing damage during storage, leading to decreased epitaxial crystal quality due to uneven oxidation and residual polishing tracks, which are difficult to remove with existing etching methods.
Innovation Solution
A CdTe-based semiconductor substrate with predetermined polishing, etching, and storage treatments to prevent orange peel defects and linear polishing damage, including a light etching treatment of 0.1 µm to 1 µm and storage in a nitrogen gas atmosphere, ensuring no tracks of linear polishing damage are observed by AFM and no orange peel defects are visible under a fluorescent lamp.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching treatment is performed to remove oxidation film and polishing damage, then surface oxidation and polishing damage are removed, but linear polishing damage tracks remain and orange peel defects occur
Solution Approach 1:
The patent applies preliminary action by performing a controlled etching treatment before substrate storage to remove polishing damage tracks and prevent their propagation. The etching conditions are specifically optimized to eliminate linear polishing damage while maintaining surface planarity, and the substrate is then stored in a nitrogen atmosphere to prevent oxidation during storage and transport, eliminating the need for post-storage etching.
2Object-generated harmful factors
If deep etching is performed to remove all polishing damage, then polishing tracks are removed, but substrate planarity deteriorates and orange peel defects occur
Solution Approach 1:
The patent applies parameter changes by precisely controlling etching parameters (etching depth, etching solution concentration, etching time, temperature) to achieve optimal removal of polishing damage tracks while maintaining substrate planarity. The etching depth is controlled within a specific range (0.1-1.0 μm) to remove tracks without creating orange peel defects, and etching conditions are adjusted based on polishing conditions to achieve the best balance between track removal and planarity maintenance.
3Ease of manufacture
If substrate is stored in air atmosphere, then storage is simple, but surface oxidation progresses unevenly and increases polishing damage
Solution Approach 1:
The patent applies inert atmosphere by storing the substrate in a nitrogen gas atmosphere after controlled etching treatment. The nitrogen atmosphere prevents oxidation during storage and transport, maintaining the improved surface quality achieved by etching. The substrate container is designed to maintain nitrogen atmosphere, and oxidation is prevented by controlling nitrogen purity and maintaining appropriate storage conditions, eliminating uneven oxidation while keeping storage practical.
4Shape
If no etching treatment is performed, then substrate planarity is maintained, but linear polishing damage tracks remain and decrease epitaxial crystal quality
Solution Approach 1:
The patent applies partial action by performing a controlled etching treatment that removes only the necessary portion of polishing damage tracks (0.1-1.0 μm depth) without excessive etching that would cause orange peel defects. This partial etching is sufficient to remove tracks that would degrade epitaxial crystal quality while maintaining substrate planarity, achieving the optimal balance between track removal and planarity preservation.
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
Enables the growth of high-quality epitaxial crystals without pre-etching treatment, enhancing the quality and yield of semiconductor devices by maintaining substrate planarity and reducing thickness variation.
Implementation Method 1
storage in a nitrogen gas atmosphere
Implementation Method 2
a light etching treatment with a light etching amount of 0.1 µm to 1 µm
Data Source
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AI summary
Provided is a CdTe-based semiconductor substrate for epitaxial growth, which is capable of growing good-quality epitaxial crystals without urging a substrate user to implement etching treatment before the epitaxial growth. A CdTe-based semiconductor substrate, in which tracks of linear polishing damage with a depth of 1 nm or more are not observed within a viewing range of 10 µm × 10 µm when a surface of the substrate is observed by an atomic force microscope, and orange peel defects are not observed when the surface of the substrate is visually observed under a fluorescent lamp, can grow the good-quality epitaxial crystals.