Considerations

Quartz glass wafers are widely used in semiconductors, optics, micro/nano-fabrication, and optical communications. Due to the extremely high requirements for processing precision, surface quality, and optical and thermal properties, every step—from material selection, processing, cleaning, inspection, to packaging—must be strictly controlled. Prices for quartz glass wafers on the market vary greatly, making it challenging for engineers and procurement managers to select products that meet their needs and guarantee reliable quality.

This article provides a systematic guide to selecting quartz glass wafers, covering four key areas: Requirement Analysis → Technical Specifications → Manufacturer Evaluation → Procurement Strategy.

1. Clearly Define Your Usage Requirements

Before choosing a wafer, clarify the application scenario and performance requirements:

Purpose:

l  Will it be used as a semiconductor process substrate, optical window, or precision carrier?

l  Will subsequent micro/nano-fabrication be involved?

l  If photolithography, deposition, or etching is required, wafers with high flatness and low defect density are essential.

Operating wavelength range:

l  Ultraviolet (185 nm, 254 nm), visible, and near-infrared regions have vastly different transmittance requirements.

l  By defining these requirements first, you can rationally determine the required material grade and processing precision, avoiding both over-specification and insufficient performance.

2. Carefully Verify Technical Specifications

Selecting quartz glass wafers involves more than checking basic parameters like diameter or thickness. The following specifications must be confirmed:

(1) Basic Parameters

Material standard: e.g., JGS1 / JGS2 / JGS3 or other international standards.

Dimensional tolerance: Diameter and thickness accuracy may need to reach ±0.01 mm or tighter.

(2) Geometric Features

TTV (Total Thickness Variation) / LTV (Local Thickness Variation)

Warp / Bow

PERP (Perpendicularity / Parallelism)

Edge chamfering: Reduces chipping risk and improves handling safety.

(3) Surface Characteristics

Surface quality (S/D): Optical-grade products may require 40/20 or even 20/10 specifications.

Roughness (Ra): For coating or precision processing, sub-nanometer roughness is often needed.

(4) Optical Properties

Transmittance: Specify the measurement wavelength, as differences can be significant across ranges.

Refractive index and uniformity: Critical for optical devices.

Bubbles and striae: High-grade quartz should have “no noticeable bubbles or striae.”

(5) Thermal Properties

Coefficient of thermal expansion, thermal conductivity, softening point, melting point: Determine stability under high-temperature processes.

(6) Mechanical Properties

Mohs hardness, Young’s modulus, Poisson’s ratio: Quartz is brittle, and compatibility with equipment clamping is essential to avoid breakage.

3. Manufacturer Production and Inspection Capabilities

Even if the specifications look good on paper, the final product may not consistently meet requirements without precise production equipment and inspection capabilities. Key points to verify include:

Equipment precision: Are high-end CNC machines, polishing tools, and interferometric inspection devices used?

Cleanroom environment: High-grade wafers require processing and cleaning in Class 100–1000 cleanrooms.

Inspection capability: Can the manufacturer provide comprehensive geometric, optical, and surface inspection reports?

Batch consistency: Is there a track record of stable, large-volume supply?

Quality certifications: ISO, RoHS, REACH, and other relevant certifications.

4. Practical Procurement Strategies

Request full inspection reports, including TTV, warp, surface quality, and transmittance.

Start with a small trial batch to verify process compatibility.

Clearly define delivery and acceptance criteria, especially for surface defects and edge chipping.

Beware of “low-price traps”: Significantly cheaper wafers may compromise material quality or processing precision.

Summary: Four-Step Selection Process

1. Define Requirements: Application scenario, wavelength, precision grade

2. Check Specifications: Geometric tolerances, surface quality, optical/thermal/mechanical properties

3. Evaluate Manufacturer: Equipment, environment, inspection capabilities, stability

4. Verify via Trial Production: Start small and scale gradually

In short:

The key to selecting quartz glass wafers = clarify requirements + verify specifications + validate process + ensure stability