Tetraethyl Orthosilicate (TEOS)

university wafer substrates

Depositing Tetraethyl Orthosilicate by CVD

A materials scientist requested a quote for the following.

I was wondering if you may provide the service I am in need of. I’d like a quote for depositing tetraethyl orthosilicate by CVD onto an 8” device wafer from 200oC to ambient conditions. I’m looking forward to your response.

We are interested in depositing silanes (preferably TEOS) onto a wafer. We need the deposition to be done at or below 200oC and we can try a variety of deposition treatments if need be.

UniversityWafer, Inc. Quoted:

We have 8” Wafer with 2000 Angstrom of PETEOS layer on it if that works.

Get Your FAST! Or, Buy Online and Start Researching Today!





What semiconductor applications are Tetraethyl Orthosilicate (TEOS) used for?

Tetraethyl orthosilicate (TEOS), also known as tetraethoxysilane, is widely used in the semiconductor industry due to its ability to form high-purity silicon dioxide (SiO₂) films. Here are the main semiconductor applications of TEOS:

1. Chemical Vapor Deposition (CVD) of SiO₂

  • Application: TEOS is a common precursor in plasma-enhanced (PECVD) or low-pressure CVD (LPCVD) processes.

  • Use Case: Depositing conformal dielectric layers (SiO₂) over complex topographies.

  • Advantage: Offers excellent step coverage and uniformity—important for intermetal dielectric (IMD) and shallow trench isolation (STI).

2. Shallow Trench Isolation (STI)

  • Application: TEOS-based oxide is used to fill trenches that isolate transistors in CMOS devices.

  • Why TEOS?: Its deposition and subsequent planarization (via CMP) provide excellent dielectric isolation.

3. Gap Fill and Intermetal Dielectrics

  • TEOS oxide helps fill narrow gaps between metal lines in multilevel metallization.

  • Used in damascene processes where metal interconnects are embedded in a dielectric matrix.

4. Hard Mask and Sacrificial Layers

  • TEOS oxide layers are used as etch masks for patterning underlying layers.

  • Can also act as a sacrificial layer in MEMS or nanofabrication, later removed to release structures.

5. Spin-on Glass (SOG) and Sol-Gel Coatings

  • Although less common than CVD, TEOS is also used in sol-gel processes to form thin oxide films.

  • Particularly useful in low-temperature processing or on substrates sensitive to high temperatures.

6. Silica Nanoparticles and Dielectric Fillers

  • In advanced packaging and dielectric materials (e.g. low-k dielectrics), TEOS is a precursor for making silica nanoparticles or composites.

Key Benefits of Using TEOS:

  • High purity

  • Good conformality

  • Precise control over film thickness and quality

  • Compatible with existing CVD infrastructure

 

 

 

TEOS in Semiconductors

TEOS, or tetraethyl orthosilicate, is a chemical compound widely used in the semiconductor industry, particularly in the process of creating silicon dioxide (SiO2) layers on substrates. Its chemical formula is Si(OC2H5)4, and it is a liquid precursor for depositing high-purity silicon dioxide films via chemical vapor deposition (CVD) processes.

Importance of TEOS in Semiconductors

  • Silicon Dioxide Formation:
    • Silicon dioxide is a critical material in semiconductor devices, serving as an insulator, a gate dielectric Typical TEOS emiconductor device in MOSFETs, and a passivation layer.
    • TEOS is a key precursor for depositing these SiO2 layers because it decomposes at high temperatures to form pure SiO2.
  • Process Compatibility:
    • TEOS-based deposition works well in plasma-enhanced chemical vapor deposition (PECVD) and low-pressure chemical vapor deposition (LPCVD) processes.
    • It enables deposition at relatively low temperatures, making it compatible with devices that cannot tolerate high thermal budgets.
  • Uniformity and Conformality:
    • TEOS-based CVD processes produce films with excellent step coverage and uniformity, essential for modern devices with complex geometries.
  • High Purity:
    • TEOS produces SiO2 with high chemical and structural purity, which is essential for minimizing defects and ensuring device reliability.
  • Applications in Nanotechnology:
    • TEOS is often used to grow SiO2 films for advanced micro- and nanofabrication, including biosensors, MEMS devices, and photonic structures.
  • Etch Stop and Masking Layer:
    • SiO2 deposited from TEOS acts as an effective etch stop or masking layer in various etching processes.

Key Considerations

  • Deposition Parameters: Deposition using TEOS involves careful control of temperature, pressure, and gas flow to achieve desired film properties.
  • Environmental and Safety Factors: TEOS is flammable and can hydrolyze in the presence of water to produce ethanol, so proper handling and storage are essential.

In summary, TEOS is a cornerstone material in the semiconductor industry, offering a reliable and versatile method to produce high-quality SiO2 layers critical for device fabrication. Its role in enabling precise and controlled deposition processes makes it indispensable for advanced semiconductor technologies.

TEOS oxide deposition via LPCVD and PECVD, and how TEOS compares to silane (SiH₄) for forming silicon dioxide films:

🔧 LPCVD vs. PECVD for TEOS Oxide

Feature LPCVD TEOS PECVD TEOS
Temperature 650–750°C ~300–400°C
Pressure Low (0.1–1 Torr) Low (few Torr)
Film Quality Dense, high-quality oxide Slightly lower density, may be porous
Conformality Excellent (ideal for trench fill) Good, but less than LPCVD
Deposition Rate Slower (few hundred Å/min) Faster (~2000 Å/min or more)
Plasma Required? ❌ No ✅ Yes
Applications Shallow trench isolation, gate oxides IMD layers, oxide caps, passivation

Summary:

  • LPCVD TEOS is used when you want high-quality, dense films and can tolerate high temperatures.

  • PECVD TEOS is preferred for temperature-sensitive substrates (like metal layers or low-k dielectrics).

⚖️ TEOS vs. Silane (SiH₄) for Oxide Films

Property TEOS (Si(OC₂H₅)₄) Silane (SiH₄)
Oxide Film SiO₂ SiO₂
Deposition Process LPCVD, PECVD, spin-on LPCVD, PECVD
Deposition Temp. Medium to high (PECVD or LPCVD) Usually lower (300–450°C)
Conformality Very good Poor to moderate
By-products Ethanol-based Hydrogen-rich
Contamination Risk Lower carbon contamination Potentially more H-induced defects
Handling Liquid, easier to store Gas, flammable and pyrophoric

Summary:

  • TEOS is safer and provides better film conformity, especially for high aspect ratio structures.

  • Silane is used where low-temp processes and high throughput are priorities, but often requires N₂O or O₂ plasma to form oxide.

🛠 Example Process Reactions

  • TEOS LPCVD:

    scss
    Si(OC₂H₅)₄ → SiO₂ + byproducts (mainly C₂H₅OH, CO₂)

  • Silane + N₂O or O₂ (PECVD):

    mathematica
       
    SiH₄ + 2O₂ → SiO₂ + 2H₂O

If you're choosing between TEOS and silane for a specific application, I can help you weigh options based on:

  • Temp budget

  • Step coverage needs

  • Throughput

  • CMP compatibility

  • Contamination sensitivity (e.g., for gate dielectrics)