The SEMI M55 standard is a crucial document that outlines the substrate requirements for monocrystalline high-purity silicon carbide wafers. These specifications are specifically designed for wafers of crystallographic polytypes 6H and 4H, which are essential materials in semiconductor and electronic device manufacturing.
This standard serves as a comprehensive guide, detailing not only the basic requirements but also listing additional physical, electrical, and bulk properties that may be necessary for a complete purchase specification. For each of these properties, SEMI M55 refers to documented test methods that can be used to accurately determine their magnitude.
It’s important to note that SEMI M55 is specifically focused on silicon carbide wafers that have undergone polishing on one or both sides. The current specifications do not cover unpolished wafers or those with epitaxial films. However, even for these types of wafers, purchasers can still find the guidelines within SEMI M55 valuable when defining their specific requirements and ensuring quality.
Key Components of SEMI M55 for Silicon Carbide Wafers
SEMI M55 encompasses various critical aspects to ensure the quality and consistency of silicon carbide wafers used in advanced semiconductor applications. These key areas include:
- Substrate Requirements: Defining the fundamental characteristics of the silicon carbide substrate material itself, ensuring it meets the purity and crystalline structure necessary for high-performance devices.
- Physical Properties: Specifying measurable physical attributes of the wafers, such as dimensions, flatness, thickness, and edge contour, which are vital for handling and integration in manufacturing processes.
- Electrical Properties: Addressing the electrical characteristics of the wafers, including resistivity, particularly important for semi-insulating silicon carbide used in high-power and high-frequency electronics.
- Bulk Properties: Outlining requirements related to the material’s internal structure and quality, such as crystallographic orientation and defect density, impacting device performance and reliability.
To ensure accurate assessment and compliance, SEMI M55 extensively references other SEMI standards that provide detailed test methods and guidelines.
Referenced SEMI Standards in M55
SEMI M55 is not a standalone document but is interconnected with a suite of other SEMI standards that provide detailed methodologies and terminologies for the semiconductor industry. Key referenced standards include:
- SEMI M1: “Specification for Polished Single Crystal Silicon Wafers.” While M55 focuses on silicon carbide, M1 provides foundational specifications for polished wafers, offering relevant context and comparison.
- SEMI M59: “Terminology for Silicon Technology.” This standard ensures consistent language and definitions within the silicon and semiconductor industry, crucial for clear communication and specification understanding.
- SEMI M81: “Guide to Defects Found on Monocrystalline Silicon Carbide Substrates.” Essential for identifying and classifying defects specific to silicon carbide wafers, aiding in quality control and material assessment.
- SEMI M83: “Test Method for Determination of Dislocation Etch Pit Density in Monocrystals of III-V Compound Semiconductors.” Provides a method for quantifying dislocation density, a critical defect metric in single-crystal semiconductor materials.
- SEMI M87: “Test Method for Contactless Resistivity Measurement of Semi-Insulating Semiconductors.” Specifically relevant for silicon carbide, this standard details contactless methods for measuring resistivity, important for semi-insulating grades.
- SEMI MF26: “Test Method for Determining the Orientation of a Semiconductive Single Crystal.” Ensures accurate determination of crystallographic orientation, a fundamental property of semiconductor wafers.
- SEMI MF154: “Guide for Identification of Structures and Contaminants Seen on Specular Silicon Surfaces.” Although focused on silicon, this guide offers methodologies applicable to identifying surface structures and contaminants on polished semiconductor surfaces, including silicon carbide.
- SEMI MF523: “Practice for Unaided Visual Inspection of Polished Silicon Wafer Surfaces.” Provides guidelines for visual inspection, a basic yet important quality control step for polished wafers.
- SEMI MF671: “Test Method for Measuring Flat Length on Wafers of Silicon and Other Electronic Materials.” Defines methods for accurately measuring flat lengths on wafers, a dimensional specification.
- SEMI MF673: “Test Method for Measuring Resistivity of Semiconductor Wafers or Sheet Resistance of Semiconductor Films with a Noncontact Eddy-Current Gauge.” Offers an alternative non-contact method for resistivity measurement using eddy-current techniques.
- SEMI MF847: “Test Method for Measuring Crystallographic Orientation of Flats on Single Crystal Silicon Wafers by X-Ray Techniques.” Utilizes X-ray techniques for precise measurement of crystallographic orientation of wafer flats.
- SEMI MF928: “Test Method for Edge Contour of Circular Semiconductor Wafers and Rigid Disk Substrates.” Specifies methods for characterizing the edge profile of circular wafers, important for wafer strength and handling.
- SEMI MF1390: “Test Method for Measuring Bow and Warp on Silicon Wafers by Automated Noncontact Scanning.” Details automated non-contact scanning methods for measuring bow and warp, critical flatness parameters.
- SEMI MF1530: “Test Method for Measuring Flatness, Thickness, and Total Thickness Variation on Silicon Wafer by Automated Noncontact Scanning.” Provides comprehensive automated methods for assessing flatness, thickness, and thickness variation.
- SEMI MF2074: “Guide for Measuring Diameter of Silicon and Other Semiconductor Wafers.” Offers guidance on accurately measuring wafer diameter, a fundamental dimensional parameter.
- SEMI T5: “Specification for Alphanumeric Marking of Round Compound Semiconductor Wafers.” Defines standards for alphanumeric marking on wafers for traceability and identification.
Revision History of SEMI M55
SEMI standards are living documents, constantly evolving to reflect industry advancements and technological changes. SEMI M55 has undergone several revisions, indicating its ongoing relevance and adaptation to industry needs:
- SEMI M55-0921: (Technical revision) – Latest revision, incorporating technical updates.
- SEMI M55-0817: (Complete rewrite to combine SEMI M55.1, SEMI M55.2, SEMI M55.3, and SEMI M55.4) – A significant revision consolidating previous versions into a unified standard.
- SEMI M55-0315: (Designation update) – Update to the standard’s designation.
- SEMI M55-0814: (Technical revision) – Technical updates and refinements.
- SEMI M55-0308: (Technical revision) – Further technical revisions.
- SEMI M55-0705: (Designation update) – Designation update.
- SEMI M55-0304: (Designation update) – Designation update.
- SEMI M55-0303: (First published) – The original publication of the SEMI M55 standard.
Understanding SEMI M55 and its related standards is crucial for anyone involved in the manufacturing, quality control, or procurement of silicon carbide wafers for semiconductor applications. It provides a robust framework for ensuring material quality and consistency in this critical industry.
