Fabrication of Multiscale 1-Octadecene Monolayer Patterned Arrays Based on a Chemomechanical Method

At a Glance

Metadata	Details
Publication Date	2022-05-30
Journal	Processes
Authors	Liqiu Shi, Feng Yu, Zhouming Hang
Institutions	Zhejiang University of Water Resource and Electric Power
Analysis	Full AI Review Included

Technical Documentation & Analysis: Chemomechanical Patterning using Diamond Tooling

Executive Summary

This research successfully demonstrates a highly efficient chemomechanical method for fabricating patterned self-assembled monolayers (SAMs) on silicon using a diamond tip. This technique is highly relevant to 6CCVD’s expertise in high-precision diamond materials for advanced tooling and surface science applications.

Core Achievement: Fabrication of multiscale 1-octadecene monolayer patterned arrays (10 µm x 3 µm) on hydrogen-terminated silicon via controlled mechanical scribing.
Methodology: A diamond tip was used to mechanically break Si-H bonds in 1-octadecene solution, simultaneously initiating the formation of stable Si-C covalent bonds (chemomechanical self-assembly).
Precision: The scribing depth was precisely controlled at approximately 10 nm, demonstrating nanoscale control over the functionalization process.
Material Confirmation: XPS analysis confirmed the successful grafting, showing a significant increase in the C1s peak and the appearance of the Si-C bond peak at 100.375 eV.
Surface Property Change: The resulting SAMs significantly weakened hydrophilicity, increasing the water contact angle from 77° (Si-H surface) to 102°.
Application Potential: The method offers a fast and convenient route for preparing functionalized surfaces, suitable for creating hydrophobic fences, wet etching masks, and advanced micro/nanoscale structures.
6CCVD Value Proposition: The success of this method hinges on the quality and precision of the diamond tip. 6CCVD provides high-purity Single Crystal Diamond (SCD) materials essential for manufacturing durable, ultra-precise micro-tooling required for repeatable nanoscale scribing.

Technical Specifications

The following hard data points were extracted from the research paper detailing the materials and results of the chemomechanical patterning process.

Parameter	Value	Unit	Context
Substrate Material	Si (100) n-boron	-	Used for SAM patterning
Substrate Thickness	500 ± 25	µm	Silicon wafer specification
Substrate Resistivity	0.001-0.004	Ω·cm	Silicon wafer specification
Scribing Array Dimensions	10 x 3	µm	Rectangular array size
Array Spacing	2	µm	Spacing between arrays
Scribing Depth (Target)	~10	nm	Controlled depth of diamond tip
Contact Angle (Si(100) Bare)	25	°	Before self-assembly
Contact Angle (Si-H Surface)	77	°	Hydrogen-terminated surface
Contact Angle (1-Octadecene SAMs)	102	°	After self-assembly (Hydrophobic)
XPS Si-C Bond Energy	100.375	eV	Confirmed covalent bonding
AFM Tip Elastic Constant	0.12	N/m	V-shaped Si₃N₄ micro cantilever
AFM Scanning Rate	2.0	Hz	Used for morphology and nanofriction

Key Methodologies

The fabrication relies on precise substrate preparation followed by controlled chemomechanical scribing using a high-quality diamond tool.

Silicon Pretreatment: Silicon (100) wafers were ultrasonically cleaned sequentially with acetone, ethanol, and ultra-pure water (5 min each).
Initial Oxide Removal: Etching in 5% HF solution for 5 min to remove the native oxide layer.
Hydroxylation/Cleaning: Heating the substrate in a 4:1:1 volume ratio mixture of water, concentrated hydrochloric acid, and hydrogen peroxide (20 min).
Hydrogen Termination: Nitrogen injection into 40% NH₄F solution (20 min) followed by 10 min immersion in NH₄F solution to etch and remove the oxide layer again, resulting in a hydrogen-terminated silicon surface.
Micromachining System Setup: The pretreated silicon was immersed in 1-octadecene solution within a nitrogen airtight environment, placed on a 3D high-precision stage controlled by a PZT amplifier.
Chemomechanical Scribing: A diamond tool was used to scratch the Si surface following prewritten programs, creating rectangular arrays (10 µm length, 2 µm width, 2 µm spacing) at a controlled depth of ~10 nm.
Characterization: The resulting SAMs were analyzed using X-ray Photoelectron Spectroscopy (XPS), Atomic Force Microscopy (AFM) for morphology and nanofriction, and Sessile Water Contact Angle detection.

6CCVD Solutions & Capabilities

The successful implementation of the chemomechanical method requires ultra-hard, highly precise tooling, a core competency of 6CCVD. We offer materials and services to support and advance this type of nanoscale surface engineering.

Applicable Materials

To replicate or extend the high-precision chemomechanical scribing demonstrated in this research, Optical Grade Single Crystal Diamond (SCD) is the ideal material for the diamond tip tool.

SCD for Tooling: SCD offers unmatched hardness and wear resistance, ensuring the tip maintains its geometry and sharpness for repeatable, controlled material removal at the 10 nm scale, even under high load/friction conditions.
PCD Substrates: For researchers looking to apply this functionalization technique to non-silicon materials, 6CCVD can supply Polycrystalline Diamond (PCD) plates (up to 125mm) or Boron-Doped Diamond (BDD) films, providing robust, chemically inert substrates for extreme environment SAMs.

Customization Potential

6CCVD’s advanced manufacturing capabilities directly address the precision requirements of this research:

Requirement in Paper	6CCVD Customization Solution	Technical Specification
High-Precision Tooling	Custom SCD Blanks and Tips	SCD thickness (0.1 µm - 500 µm) for optimal tip geometry and stability.
Ultra-Smooth Surfaces	Advanced Polishing Services	SCD polishing achieving surface roughness Ra < 1 nm, critical for minimizing friction and ensuring predictable contact mechanics.
System Integration	Custom Metalization	Internal capability to deposit Au, Pt, Pd, Ti, W, or Cu for robust electrical and mechanical interfacing with PZT/dynamometer systems.
Large-Scale Patterning	Large Area Substrates	PCD plates available up to 125mm diameter for scaling up patterned array fabrication.

Engineering Support

6CCVD’s in-house PhD team provides expert consultation on material selection and design optimization for advanced surface functionalization, nanofriction analysis, and high-precision micro-tooling projects. We can assist researchers in selecting the optimal diamond grade and crystallographic orientation for maximum tool life and scribing accuracy in similar Chemomechanical Surface Patterning projects.

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

View Original Abstract

A controlled and self-assembled micromachining system was built to fabricate a mico/nanoscale monolayer patterned array on a silicon surface using a diamond tip. The process was as follows: (1) we preprocessed a silicon wafer to obtain a hydrogen-terminated silicon surface; (2) we scratched three rectangular arrays of 10 μm × 3 μm with a spacing of 2 μm on the silicon surface with a diamond tip in 1-octadecene solution; the Si-H bonds were broken, and silicon free radicals were formed; (3) the 1-octadecene molecules were connected with silicon atoms based on Si-C covalent bonds, and the 1-octadecene nano monolayer was self-assembled on the patterned arrays of the silicon surface. Atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and Sessile water contact angles were used to detect and characterize the self-assembled monolayers (SAMs). The XPS results showed that the Si2p peak and the O1s peak were significantly decreased after self-assembly; however, the C1s peak was successively significantly increased. Sessile water contact angles showed that the hydrophilicity was weakened after the formation of 1-octenecene SAMs on the silicon substrate. The nanofriction of the sample was measured with AFM. The change in nanofriction also demonstrated that the SAMs were formed in accordance with the patterned array. We demonstrated that, by using this method, self-assembled multiscale structures on silicon substrate can be formed quickly and conveniently.

Tech Support

Original Source

DOI: https://doi.org/10.3390/pr10061090

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