INDUSTRY COMPONENT

Secondary Flat

Secondary flat is a precision reference surface on gallium arsenide wafers used for crystal orientation alignment in semiconductor manufacturing.

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Component Specifications

Definition
The secondary flat is a precisely ground and polished flat surface located at a specific angular position relative to the primary flat on high-purity gallium arsenide wafer substrates. It serves as a secondary orientation reference for automated handling equipment during semiconductor device fabrication, ensuring proper crystal orientation alignment for epitaxial growth, lithography, and other critical processes. The secondary flat's position is determined by the wafer's crystal structure and doping type.
Working Principle
The secondary flat functions as a mechanical and optical reference marker that interacts with wafer handling robots, aligners, and inspection systems. Its precise angular relationship to the primary flat (typically 90° or 180° depending on crystal orientation) allows equipment to determine the wafer's exact crystallographic orientation. This ensures that semiconductor devices are fabricated along specific crystal planes for optimal electrical performance.
Materials
High-purity Gallium Arsenide (GaAs) single crystal, typically undoped or doped with specific elements (Si, Zn, Cr) depending on application requirements. Surface finish: Mirror-polished to <0.5 nm Ra roughness.
Technical Parameters
  • depth 0.5-1.0 mm
  • width 1.5-3.0 mm
  • length 15-30 mm
  • edge_chamfer 0.1-0.3 mm
  • angular_tolerance ±0.5°
  • position_accuracy ±0.1 mm
  • surface_roughness <0.5 nm Ra
Standards
SEMI M1, SEMI M20, ISO 14644, IEC 60749

Industry Taxonomies & Aliases

Commonly used trade names and technical identifiers for Secondary Flat.

secondary flat gallium arsenide wafer semiconductor orientation GaAs substrate crystal alignment wafer handling semiconductor manufacturing orientation flat primary flat Secondary Flat in Computer, Electronic and Optical Product Manufacturing

Parent Products

This component is used in the following industrial products

High-Purity Gallium Arsenide Wafer Substrate

Semiconductor-grade GaAs wafer for RF communication device fabrication.

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Engineering Analysis

Risks & Mitigation
  • Misalignment during automated handling
  • Contamination from improper cleaning
  • Mechanical damage during transport
  • Orientation errors in lithography
FMEA Triads
Trigger: Incorrect angular positioning during wafer fabrication
Failure: Device performance degradation due to wrong crystal orientation
Mitigation: Implement automated optical inspection with angular verification systems
Trigger: Mechanical damage from improper handling equipment
Failure: Wafer breakage or edge chipping affecting yield
Mitigation: Use compliant end-effectors with force feedback in wafer handlers

Industrial Ecosystem

Compatible With

Interchangeable Parts

Compliance & Inspection

Tolerance
Angular tolerance: ±0.5°, Position tolerance: ±0.1 mm, Surface roughness: <0.5 nm Ra
Test Method
Laser scanning microscopy for dimensional verification, Atomic force microscopy for surface roughness, Automated optical inspection for angular positioning

Procurement Evaluation Criteria

Not customer reviews or live demand data. These dimensions support RFQ preparation and supplier evaluation.

Technical documentation
4/5
Manufacturing capability
4/5
Inspection readiness
5/5
Supplier transparency
3/5

These scores are example evaluation dimensions, not real customer ratings, country-specific buyer feedback, or live inquiry activity.

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Frequently Asked Questions

What is the difference between primary flat and secondary flat on GaAs wafers?

The primary flat indicates the crystal plane orientation and is typically longer, while the secondary flat provides additional orientation information (doping type or specific crystal direction) and is shorter. Their angular relationship determines the exact crystallographic orientation.

Why is secondary flat positioning critical in GaAs wafer processing?

Accurate secondary flat positioning ensures proper alignment of epitaxial layers and device structures with crystal planes, which directly affects electron mobility, optical properties, and device performance in GaAs-based semiconductors.

Can I contact factories directly?

Yes, each factory profile provides direct contact information.

Data Basis

CNFX manufacturer profiles, technical classification, publicly available product information, and ongoing plausibility checks.

Preliminary Technical Classification
This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

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