I. Key Properties of Quartz Wafers

1. High Purity and Chemical Stability

Quartz (SiO₂) is resistant to acids, alkalis, and corrosion, making it suitable for use in harsh process environments.

2. Low Thermal Expansion Coefficient

Quartz wafers feature an extremely low thermal expansion coefficient (approximately 0.55×10⁻⁶/℃), which is close to that of silicon (2.6×10⁻⁶/℃). This similarity significantly reduces thermal stress issues during semiconductor processes.

3. Excellent Electrical Insulation

Quartz provides very high electrical resistivity (>10¹⁶ Ω·cm), making it ideal for high-frequency and high-power electronic applications where insulation performance is critical.

4. Optical Transparency

Quartz wafers exhibit high transmittance from the ultraviolet to the infrared spectrum, making them suitable for optoelectronic packaging and photonic device integration.

5. High Rigidity and Precision Machinability

Quartz materials maintain strong mechanical rigidity and allow high-precision microfabrication, including:

• Etching

• Laser drilling

• Precision grinding

These processes enable the fabrication of complex microstructures required in advanced semiconductor packaging.

II. Main Application Scenarios in Packaging

1. Interposer

In 2.5D and 3D semiconductor packaging, quartz wafers can replace or complement traditional silicon interposers to connect multiple chips and substrates.

Advantages

• Low dielectric constant (~3.8) reduces signal crosstalk and transmission delay, making it suitable for high-frequency communication chips.

• Low loss factor improves high-speed signal integrity, especially in millimeter-wave and terahertz applications.

2. TSV (Through-Silicon Via) Carrier

Quartz wafers can function as insulating substrates for TSV structures. Vertical vias are created through laser drilling or wet etching, enabling vertical electrical interconnections between stacked chips.

Advantages

• High insulation prevents current leakage, supporting high-density interconnections.

• Excellent thermal stability reduces deformation caused by thermal cycling.

3. MEMS and Sensor Packaging

Quartz wafers are widely used as packaging substrates for MEMS devices, including accelerometers and gyroscopes. They provide sealed cavities to protect delicate microstructures.

Advantages

• Vacuum sealing with Silicon Wafers can be achieved through anodic bonding.

• Optical transparency enables easier testing and integration of optical MEMS devices such as micromirrors.

4. Optoelectronic Integrated Packaging

Quartz wafers are also applied in Photonic Integrated Circuits (PICs) as optical waveguide substrates for coupling and packaging optical communication chips.

Advantages

• Transparency supports precise optical signal transmission and alignment.

• Low thermal expansion ensures stable performance of optical components under temperature fluctuations.

5. RF Device Packaging

Quartz wafers are increasingly used in 5G and future 6G RF device packaging, including RF filters and antenna modules.

Advantages

• Low dielectric loss improves the Q-factor of RF components, enhancing filter performance and signal quality.

6. Wafer-Level Packaging (WLP)

Quartz wafers can serve as temporary carrier substrates during wafer-level packaging processes.

Functions

• Provide mechanical support for ultra-thin wafer processing

• Prevent warpage and cracking during advanced semiconductor manufacturing steps