The Influence of Wire Speed on Phase Transitions and Residual Stress in Single Crystal Silicon Wafers Sawn by Resin Bonded Diamond Wire Saw

At a Glance

Metadata	Details
Publication Date	2021-04-14
Journal	Micromachines
Authors	Tengyun Liu, Peiqi Ge, Wenbo Bi
Institutions	Qilu University of Technology, Shandong University
Citations	10
Analysis	Full AI Review Included

Technical Documentation & Analysis: Subsurface Damage in Diamond Wire Slicing

Executive Summary

This analysis of the study on residual stress and phase transitions in single crystal silicon (Si) wafers sawn by resin bonded diamond wire highlights critical challenges in high-throughput semiconductor manufacturing, specifically concerning subsurface damage (SSD) and wafer warp.

Core Challenge: High wire speed during diamond wire sawing generates significant subsurface damage, characterized by the formation of amorphous silicon (a-Si) phases (Si-XII and Si-III) and high residual stress.
Key Finding: Increasing wire speed from 150 m/min to 270 m/min resulted in a 3.5-fold increase in the depth of the amorphous silicon layer (from 6.556 nm to 22.73 nm).
Stress Magnitude: Residual stress on the wafer surface layer is mixed, exhibiting both compressive stress (up to 300 MPa) and tensile stress (up to 200 MPa), both of which increase with wire speed.
Mechanism: Higher wire speed promotes material removal in the ductile regime, leading to increased phase transitions and a higher stress gradient that cannot be fully released.
6CCVD Relevance: The need for ultra-low damage surfaces (nm-scale control) and high-precision metrology components directly aligns with 6CCVD’s expertise in high-purity, ultra-smooth MPCVD Single Crystal Diamond (SCD) and Polycrystalline Diamond (PCD) materials.
Solution Focus: 6CCVD provides the foundational diamond materials necessary for next-generation, low-damage slicing tools and high-resolution Raman characterization windows.

Technical Specifications

The following hard data points were extracted from the experimental results, focusing on the relationship between processing parameters and resulting subsurface damage.

Parameter	Value	Unit	Context
Wafer Material	P-type (111) Single Crystal Silicon	N/A	Ingot diameter 56 mm
Diamond Wire Diameter	95 to 105	µm	Resin Bonded Diamond Wire Saw (RBDWS)
Abrasive Size	8 to 16	µm	Diamond abrasive particle range
Abrasive Density	1200	grits/mm²	RBDWS specification
Wire Tension	12	N	Constant parameter across all tests
Feed Speed	0.2	mm/min	Constant parameter across all tests
Max Compressive Stress	300	MPa	Observed residual stress range
Max Tensile Stress	200	MPa	Observed residual stress range
Amorphous Si Raman Shifts	178.9 and 468.5	cm^-1	Indicative of Si-XII and Si-III phases
Stress Calibration	±3.2 cm^-1 corresponds to ±1 GPa	N/A	Basis for residual stress calculation

Amorphous Layer Depth vs. Wire Speed

The depth of the amorphous silicon layer ($d_a$) is a direct measure of subsurface damage (SSD).

Wire Speed ($v_s$)	Raman Intensity Ratio ($r$)	Depth of Amorphous Layer ($d_a$)	Unit
150 m/min	0.13	6.556	nm
210 m/min	0.27	12.39	nm
270 m/min	0.59	22.73	nm

Key Methodologies

The research utilized a multi-wire sawing process followed by high-resolution Raman spectroscopy to quantify subsurface damage.

Sawing Setup: A YJXQ120B multi-wire saw machine was used with resin bonded diamond wire (95-105 µm diameter, 8-16 µm abrasive size).
Material Preparation: P-type (111) single crystal silicon ingots (56 mm diameter) were sliced with a constant feed speed (0.2 mm/min) and wire tension (12 N).
Variable Testing: Three distinct wire speeds were tested: 150 m/min, 210 m/min, and 270 m/min.
Characterization: A Microscope Raman spectrometer was used with a 633 nm excitation laser (1.23 mW power) and a scan range of 100-700 cm^-1.
Data Acquisition: Raman spectra were mapped across 13 points on the as-sawn wafer surface to detect phase transitions (amorphous silicon peaks) and measure Raman peak shifts.
Stress Calculation: Residual stress was calculated based on the Raman shift relative to the natural Si-I peak (521 cm^-1), using the calibration factor of ±3.2 cm^-1 corresponding to ±1 GPa stress.
Amorphous Depth Calculation: The depth of the amorphous layer ($d_a$) was derived from the ratio ($r$) of the amorphous surface area to the un-phase transition surface area, using established curve-fitting equations.

6CCVD Solutions & Capabilities

The findings underscore the critical need for materials that enable precise control over subsurface damage in semiconductor processing. 6CCVD provides the high-performance MPCVD diamond materials essential for both advanced tooling and metrology required to replicate and extend this research.

Applicable Materials

To address the challenges of residual stress and subsurface damage, 6CCVD offers specialized diamond materials:

Optical Grade SCD (Single Crystal Diamond): Ideal for high-precision Raman spectroscopy windows, anvils, or optical components requiring minimal background noise and high transmission purity. Our SCD offers Ra < 1 nm polishing, crucial for minimizing surface scattering in high-resolution metrology setups.
High-Purity PCD (Polycrystalline Diamond): Suitable for developing next-generation fixed abrasive wire saws or wear-resistant tooling. PCD plates up to 125 mm diameter are available, offering superior mechanical robustness for industrial slicing applications.
Boron-Doped Diamond (BDD): For researchers exploring electrochemical methods to monitor or mitigate residual stress, BDD offers a stable, conductive electrode material with exceptional chemical inertness.

Customization Potential

The precise control required in wire sawing necessitates highly customized tooling and metrology components. 6CCVD’s capabilities directly support the scaling and refinement of this research:

Research Requirement	6CCVD Custom Capability	Benefit to Researcher
Large Area Processing	Plates/wafers up to 125 mm (PCD)	Enables scaling up of experimental wafer sizes and industrial tooling.
Precise Thickness Control	SCD/PCD thickness from 0.1 µm to 500 µm	Allows for the fabrication of ultra-thin diamond films for specialized abrasive coatings or sensor integration.
Surface Quality	Polishing to Ra < 1 nm (SCD) and Ra < 5 nm (PCD)	Provides reference standards and metrology components with minimal intrinsic surface defects, essential for accurate nm-scale damage analysis.
Sensor Integration	Custom Metalization (Au, Pt, Pd, Ti, W, Cu)	Facilitates the integration of thermal or strain sensors directly onto diamond tooling or substrates for in situ monitoring of cutting forces and heat generation.

Engineering Support

The relationship between wire speed, phase transition, and residual stress is complex. 6CCVD’s in-house PhD team specializes in the mechanical and thermal properties of diamond and can assist researchers and engineers with:

Material Selection: Guidance on selecting the optimal diamond grade (SCD vs. PCD) and surface finish for advanced slicing tools or high-pressure metrology applications.
Thermal Management: Consultation on using diamond substrates (up to 10 mm thick) for superior heat spreading, which is critical for mitigating the non-uniform thermal energy distribution cited as a cause of residual stress in the paper.
Custom Geometry: Design and fabrication of custom diamond components via laser cutting for specialized wire saw guides or fixture elements requiring extreme hardness and wear resistance.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

Lower warp is required for the single crystal silicon wafers sawn by a fixed diamond wire saw with the thinness of a silicon wafer. The residual stress in the surface layer of the silicon wafer is the primary reason for warp, which is generated by the phase transitions, elastic-plastic deformation, and non-uniform distribution of thermal energy during wire sawing. In this paper, an experiment of multi-wire sawing single crystal silicon is carried out, and the Raman spectra technique is used to detect the phase transitions and residual stress in the surface layer of the silicon wafers. Three different wire speeds are used to study the effect of wire speed on phase transition and residual stress of the silicon wafers. The experimental results indicate that amorphous silicon is generated during resin bonded diamond wire sawing, of which the Raman peaks are at 178.9 cm−1 and 468.5 cm−1. The ratio of the amorphous silicon surface area and the surface area of a single crystal silicon, and the depth of amorphous silicon layer increases with the increasing of wire speed. This indicates that more amorphous silicon is generated. There is both compressive stress and tensile stress on the surface layer of the silicon wafer. The residual tensile stress is between 0 and 200 MPa, and the compressive stress is between 0 and 300 MPa for the experimental results of this paper. Moreover, the residual stress increases with the increase of wire speed, indicating more amorphous silicon generated as well.

Tech Support

Original Source

DOI: https://doi.org/10.3390/mi12040429

References

2021 - Investigation of rapid composite plating of core wire magnetized electroplated diamond wire saw [Crossref]
2014 - Comparison of diamond wire cut and silicon carbide slurry processed silicon wafer surfaces after acidic texturisation [Crossref]
2016 - Effect of growth rate and wafering on residual stress of diamond wire sawn silicon wafers [Crossref]
2016 - Wire sawing technology: A state-of-the-art review [Crossref]
2016 - Phase and stress evolution in diamond microparticles during diamond-coated wire sawing of Si ingots [Crossref]
2015 - Determination of the impact of the wire velocity on the surface damage of diamond wire sawn silicon wafers [Crossref]
2017 - Mechanisms of material removal and subsurface damage in fixed-abrasive diamond wire slicing of single-crystalline silicon [Crossref]
2012 - Study of ductile-to-brittle transition in single grit diamond scribing of silicon: Application to wire sawing of silicon wafers [Crossref]