Surface and subsurface microstructure properties of monocrystalline silicon cut by electroplated diamond wire saw

At a Glance

Metadata	Details
Publication Date	2025-09-28
Journal	Surface Science and Technology
Authors	Dong Hui, Yufei Gao, Chunfeng Yang
Institutions	Shandong University, Shandong Jiaotong University
Analysis	Full AI Review Included

Technical Documentation & Analysis: MPCVD Diamond for High-Precision Slicing Tools

Executive Summary

This analysis focuses on optimizing diamond wire sawing parameters for monocrystalline silicon (mono-Si) wafers, directly addressing critical quality metrics relevant to the photovoltaic and microelectronics industries. The findings underscore the necessity of high-performance diamond materials to minimize surface damage.

Core Challenge: Minimizing Saw Mark Peak-Valley (PV) values and Subsurface Damage (SSD) depth, which currently range up to 5.3 µm (PV) and 22.8 µm (SSD) under tested conditions.
Dominant Factor: Specimen Feed Speed ($V_f$) was identified as having the greatest impact on both PV and SSD values, followed by specimen length and wire speed.
Material Removal Mode: Wafer surface generation is a mixed mode of brittle (resulting in pits) and ductile (resulting in grooves) material removal.
Quality Target: Achieving low SSD (ideally < 4 µm) requires high-performance wire saw cutting machines and superior diamond abrasive quality, a key area where 6CCVD’s materials excel.
Optimization Strategy: To improve wafer quality, researchers must increase wire speed ($V_s$) and decrease feed speed ($V_f$) and specimen length ($L$).
6CCVD Value Proposition: 6CCVD supplies high-purity, custom MPCVD diamond materials (SCD and PCD) necessary to manufacture the next generation of high-speed, low-damage diamond wire tooling required to meet stringent SSD targets.

Technical Specifications

The following hard data points were extracted from the experimental results and material descriptions, highlighting the performance achieved and the critical parameters involved in the slicing process.

Parameter	Value	Unit	Context
Core Wire Diameter	120	µm	Electroplated Diamond Wire
Envelope Diameter	160	µm	Electroplated Diamond Wire
Abrasive Type	Nickel Coated Diamond	N/A	Electroplated Abrasive
Abrasive Size	15-20	µm	Used in Wire Saw
Abrasive Density	120-130	grits/mm	Used in Wire Saw
Saw Mark Waviness (PV) Range	1.468 to 5.3	µm	Across all tested parameters
Subsurface Damage (SSD) Range	7 to 22.8	µm	Across all tested parameters
Surface Roughness (Ra) Range	0.525 to 0.712	µm	Dependent on Wire Speed
Desired SSD Target (Industry)	< 4	µm	Required for high-performance wafers
Critical Cutting Depth	Brittle-Ductile Transition	N/A	Determines SSD formation

Key Methodologies

The experiment utilized single factor and orthogonal experimental designs to isolate the influence of three primary variables on wafer quality metrics (PV and SSD).

Equipment: Reciprocating single diamond wire saw device (WXD170).
Workpiece Material: Monocrystalline silicon (mono-Si) bricks/rods.
Cooling/Lubrication: Deionized water.
Measurement Tools: Keyence laser confocal microscope (VK-X200K) for surface topography, PV, and SSD.
SSD Measurement Preparation: Wafer specimens were inlayed, lapped, polished, and corroded using an acidic solution (H₂O:HF49%:CrO₃ = 200 ml: 200 ml: 30 g) to reveal subsurface microcracks.
Orthogonal Experimental Parameters (3 Factors, 3 Levels):

Factor	Level 1	Level 2	Level 3	Unit
(A) Specimen Feed Speed ($V_f$)	0.8	1.0	1.2	mm/min
(B) Diamond Wire Speed ($V_s$)	60	80	100	m/min
(C) Specimen Length ($L$)	20	30	40	mm

6CCVD Solutions & Capabilities

The research highlights a clear need for advanced diamond abrasive technology to push SSD values below the current experimental minimum of 7 µm and achieve the industry target of < 4 µm. 6CCVD’s MPCVD diamond materials provide the necessary foundation for this next generation of high-performance slicing tools.

Applicable Materials

The performance of the diamond abrasive is paramount. 6CCVD recommends the following materials for tooling manufacturers seeking to replicate or extend this research into high-speed, low-damage slicing:

High-Purity Polycrystalline Diamond (PCD):
- Application: Ideal for manufacturing large-area, high-strength diamond wire dies or wear parts in the wire saw system, ensuring superior dimensional stability and reduced lateral vibration (a key cause of high PV values).
- Capability Match: 6CCVD offers PCD plates/wafers up to 125mm in diameter, allowing for the creation of robust, large-scale tooling components.
Single Crystal Diamond (SCD) Substrates:
- Application: Used for ultra-precision dies, guides, or specialized abrasive particles where maximum hardness, thermal stability, and low defect density are critical for maintaining a consistent cutting depth ($g$) and minimizing brittle fracture.
- Capability Match: SCD available in thicknesses from 0.1 µm up to 500 µm, with polishing quality Ra < 1nm for critical contact surfaces, ensuring minimal friction and superior wire guidance accuracy.

Customization Potential

The paper notes that wire bow and lateral forces significantly influence PV and SSD. Custom tooling components require precise dimensions and specialized surface treatments.

Research Requirement	6CCVD Customization Capability	Benefit to Slicing Process
High-Precision Tooling Components	Custom SCD/PCD Substrates (up to 10mm thickness)	Enhanced rigidity and reduced wire vibration, directly lowering PV values.
Specialized Wire Guides/Dies	Custom dimensions and laser cutting services	Ensures tighter tolerances on wire path, minimizing lateral force fluctuations.
Tooling Integration	Internal Metalization Services (Au, Pt, Pd, Ti, W, Cu)	Allows for robust bonding and integration of diamond components into electroplated or resin-bonded wire saw systems.
Surface Quality	PCD Polishing to Ra < 5nm (Inch-size)	Reduces friction and wear on guide wheels and dies, extending tool life and maintaining high wire speed stability.

Engineering Support

The transition to “larger silicon wafer size and finer diamond wire diameter” requires sophisticated material selection. 6CCVD’s in-house PhD team specializes in the mechanical and thermal properties of MPCVD diamond.

Consultation Focus: We assist engineers in selecting the optimal diamond material (SCD vs. PCD) and geometry to achieve the desired brittle-ductile transition control, enabling low SSD (< 4 µm) slicing performance at high wire speeds.
Global Supply Chain: 6CCVD provides reliable, global shipping (DDU default, DDP available) to ensure rapid deployment of custom diamond solutions for high-volume manufacturing environments.

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

Tech Support

Original Source

DOI: https://doi.org/10.1007/s44251-025-00098-1