Substrates Used in NanoEngineering Research

Thin Silicon Wafers for Nanoengineering Research

A post doc studying in a NanoEngineering and MicroSystems department requested a quote for the following.

How quickly can you deliver 50 micron thick, double side polished P-doped Boron, (100) wafers to Taiwan? We will do KOH or TMAH directional etch to make 1 and 2 centimeter open windows.

Are 50 micron wafers easy to cleave by hand with a diamond scribe?

Could you quote separately LPCVD nitride - I am not sure of thickness, but I think 2000 Angstroms is plenty. I will find out today. Is it quick and easy for you to do the LPCVD?

Could you quote separately dicing? Half of the wafers would be 2 x 2
centimeters, the other half would be 3 x 3 centimeters. Total die obviously depends on which wafer size we order.

Reference #91412 for specs and pricing.

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

Profilometer Used To Measure Stress Coupon

A PhD candidate requested the following quote.

We are looking for 25-50 mm diameter crystalline quartz wafers for use as stress indicators in our PVD coating operations. Compressive or tensile films cause deformation of the stress coupon that can be measured on a profilometer. For sensitivity, the wafers need to be less than 0.5 mm thick. Do you have a source for these?

Reference #291034 for specs and pricing.

What Is A Optical Profilometer?

An optical profilometer is a type of non-contact profilometer that uses light (typically lasers or white light) to measure the surface profile and topography of materials. Unlike a stylus profilometer, which physically touches the surface, an optical profilometer measures surface features using optical techniques, making it ideal for delicate or soft surfaces that may be damaged by physical contact.

How an Optical Profilometer Works:

1. Light Projection: The profilometer projects light onto the surface of the material, often using laser beams or white light interferometry.

2. Reflection and Interference: The reflected light from the surface is captured by detectors. The way the light reflects depends on the surface features—its peaks and valleys change the phase and intensity of the reflected light.

3. Interferometry (in many cases): One common technique is white light interferometry, where the reflected light from the surface interferes with reference light. By analyzing the interference patterns, the profilometer can determine surface height variations with very high precision, often down to the nanometer level.

4. Data Processing: The optical profilometer processes the captured light information to generate a 3D map of the surface topography, showing the surface's height variations, roughness, and other features.

Types of Optical Profilometers:

1. White Light Interferometry (WLI):

   • Uses white light to measure the surface profile based on interference patterns.
   • Very precise, often used for measuring thin films, step heights, and roughness.

2. Confocal Microscopy:

   • Focuses a beam of light on different heights across the surface, allowing a detailed 3D scan of the topography.
   • Ideal for measuring samples with complex structures.

3. Laser Scanning Profilometer:

   • Projects a laser beam onto the surface, and as the laser moves across the sample, it measures the changes in distance to calculate the surface profile.
   • Can scan large areas quickly, though with slightly lower resolution than interferometric methods.

Key Advantages of Optical Profilometers:

1. Non-Contact Measurement: Since it doesn't physically touch the surface, an optical profilometer can measure delicate, soft, or thin materials without causing damage.

2. High Resolution: Optical profilometers can measure extremely small surface features, with resolution often down to the nanometer level.

3. 3D Surface Mapping: It provides not only 2D profile measurements but also highly detailed 3D maps of the surface topography.

4. Speed: Optical methods are typically faster than contact profilometers, making them suitable for high-throughput measurements.

Applications:

• Thin Film Thickness: Frequently used in industries such as semiconductor manufacturing to measure the thickness and uniformity of thin films.
• Surface Roughness and Texture: Important in industries like automotive, aerospace, and biomedical to ensure product quality and performance.
• MEMS and Microfabrication: Widely used for characterizing microstructures and ensuring precision in microelectromechanical systems (MEMS).

For your projects involving thin films and coatings, an optical profilometer would be especially beneficial if the coatings are delicate or need high-precision, non-contact measurements.

 

What is Nanoengineering?

Nanoengineering is a branch of engineering that focuses on designing, creating, and manipulating materials, devices, and systems at the nanometer scale (typically between 1 to 100 nanometers). It applies the principles of nanoscience, which studies the properties and behaviors of matter at this scale, to develop practical technologies for a wide range of industries.

Here are some key aspects of nanoengineering:

1. Scale: Nanoengineering deals with structures and systems that are incredibly small, often just a few atoms or molecules in size. This small scale allows for precise control over material properties and behaviors that are not observed at larger scales.

2. Materials: At the nanoscale, materials can exhibit unique electrical, optical, mechanical, and chemical properties. For example, carbon nanotubes and graphene have remarkable strength and conductivity compared to bulk materials.

3. Applications: Nanoengineering has diverse applications in industries such as electronics (for smaller, faster transistors and memory), medicine (for targeted drug delivery systems and biosensors), energy (for efficient solar cells and batteries), and materials science (for lightweight and durable materials).

4. Techniques: Nanofabrication methods such as lithography, self-assembly, and chemical vapor deposition are commonly used to build nano-scale structures. Scientists also use tools like scanning tunneling microscopes and atomic force microscopes to observe and manipulate materials at the atomic level.

In essence, nanoengineering merges physics, chemistry, biology, and materials science to innovate at the nanoscale for practical, real-world solutions.

What Substrates Do Nanoengineers Work With?

Nanoengineers work with a variety of substrates depending on the application, material system, and fabrication techniques they are using. Common substrates in nanoengineering include:

1. Silicon (Si)

• Applications: Widely used in the semiconductor industry for electronics and integrated circuits.
• Properties: Offers good thermal and electrical properties, making it an ideal base for fabricating nanoscale devices like transistors and sensors.
• Surface Modifications: Silicon can be passivated or coated with thin films for advanced applications.

2. Silicon Dioxide (SiO2)

• Applications: Used in microelectronics and nanophotonics. It's often applied as an insulating layer.
• Properties: It's an electrical insulator with excellent thermal stability, commonly used as a thin film on top of silicon.

3. Fused Quartz

• Applications: Used in optical and electronic applications, especially for growing carbon nanotubes or nanowires.
• Properties: High purity and heat resistance, which makes it useful for high-temperature processes like chemical vapor deposition (CVD).

4. Graphene and Other 2D Materials

• Applications: Utilized in electronics, flexible devices, and sensors due to exceptional electrical and mechanical properties.
• Properties: Graphene is highly conductive and mechanically strong, making it a leading material for next-generation electronics.

5. Glass

• Applications: Used in photonic devices, sensors, and bio-nanoengineering applications.
• Properties: Transparent, chemically stable, and customizable for various optical and electronic uses.

6. Metal Substrates (Gold, Silver, Copper, Platinum)

• Applications: Used for nano-scale coatings, plasmonic devices, and electronic applications.
• Properties: Metals like gold and silver are used for their excellent conductive and plasmonic properties, especially in nanoscale optical devices.

7. Polymer Substrates (Polydimethylsiloxane - PDMS
, PMMA)

• Applications: Frequently used in flexible electronics, nanoimprint lithography, and bioengineering.
• Properties: Flexible and low-cost, making them ideal for applications like flexible sensors or lab-on-a-chip devices.

8. Alumina (Aluminum Oxide, Al2O3)

• Applications: Used in nanostructuring, especially as a template in processes like anodic aluminum oxide (AAO) for nanoporous materials.
• Properties: Chemically stable and has high thermal resistance, making it suitable for various fabrication processes.

9. Gallium Nitride (GaN)

• Applications: Often used in high-power and high-frequency electronic devices, like LEDs and power transistors.
• Properties: GaN has excellent electron mobility and wide bandgap, useful for optoelectronic devices at the nanoscale.

10. Sapphire (Al2O3)

• Applications: Employed in optoelectronics, particularly for high-performance nanodevices like LEDs.
• Properties: It's a crystalline substrate with high hardness and thermal stability, suitable for high-temperature fabrication.

11. Titanium Dioxide (TiO2)

• Applications: Utilized in photovoltaics, sensors, and photocatalytic applications.
• Properties: TiO₂ is known for its optical properties, such as high refractive index and photocatalytic activity, making it useful in energy-harvesting and sensing devices.

12. Boron Nitride (BN)

• Applications: Used in nanophotonics, thermal management systems, and graphene-based devices as a dielectric layer.
• Properties: Boron nitride has good thermal conductivity and is chemically inert, which can complement graphene or other 2D materials in layered structures.

13. Mica

• Applications: Commonly used in surface science studies and molecular-scale fabrication.
• Properties: Mica is a naturally cleavable material that provides atomically flat surfaces, making it suitable for nanostructure deposition and imaging.

14. Carbon-based Substrates

• Applications: Include diamond-like carbon, carbon nanotubes (CNTs), and amorphous carbon films.
• Properties: These materials exhibit unique electrical, thermal, and mechanical properties for nanodevices, especially in fields like energy storage and nanomechanics.

Nanoengineers choose substrates based on the required properties for a given project, such as conductivity, optical characteristics, thermal stability, and chemical compatibility with the materials being used.

Do Low Quality Substrates Work Well With a Profilometer?

Using low-quality substrates with a profilometer may pose challenges, particularly in achieving accurate, reliable measurements. The quality of the substrate directly affects the results obtained from profilometer measurements, whether it is a contact or non-contact type. Here's how substrate quality impacts profilometer performance:

1. Surface Roughness and Imperfections:

• High Roughness or Defects: If the substrate has significant roughness or defects, it can skew the measurements by introducing variations that don't represent the actual feature of interest, especially when evaluating thin films or surface coatings.
• Profilometer Sensitivity: A highly sensitive profilometer may pick up substrate imperfections, leading to inaccurate surface roughness or thickness measurements of the applied film.

2. Non-Uniformity:

• Warping or Bowing: Substrates with uneven surfaces, warping, or bowing can result in erroneous curvature measurements, which is crucial when evaluating film stress. Optical profilometers may struggle to accurately measure the surface if it is highly non-uniform.
• Film Stress Calculation: Low-quality substrates may introduce incorrect curvature baselines, affecting thin-film stress calculations.

3. Adhesion Problems:

• Coating Adhesion: If the substrate is of low quality, thin films or coatings might not adhere well. Poor adhesion can cause delamination or cracking, leading to inaccurate profilometer measurements of thickness and surface properties.

4. Surface Cleanliness:

• Contamination or Surface Particles: Profilometers, especially non-contact types, are highly sensitive to surface particles or contamination. If the substrate is contaminated with dust, residues, or other particles, these can interfere with profilometer readings, leading to inaccurate or noisy data.

5. Compatibility with Measurement Method:

• Optical Profilometers: Optical profilometers rely on light reflection from the surface. If the substrate is too rough, too reflective, or insufficiently reflective (low-quality optical properties), the measurement can be distorted or fail altogether.
• Stylus Profilometers: A contact profilometer with a stylus can be affected by low-quality substrates, especially if they are too rough or soft, causing the stylus to skip or drag inaccurately.

Silicon Germanium (SiGe) and Profilometer Measurements

A research scientist requested the following quote.

8-in Si Wafers with SiGe waveguides. Polishing down 1 um.

I want to add that we are not very stringent on specifications. You can this on a best efforts basis. If you have an optical profilometer to tell that polishing has reached silicon, it will suffice.

Please let me know if you have any questions regarding the cross section.

Reference #313273 for specs and pricing.

How to Work Around Low-Quality Substrates:

If you're limited to using low-quality substrates, there are a few ways to mitigate potential issues with profilometer measurements:

1. Surface Preparation: Cleaning and treating the surface of the substrate before measuring can improve the quality of the measurements. Even for low-quality substrates, removing contaminants or polishing the surface can help reduce interference.

2. Multiple Measurements: Taking multiple profilometer measurements across different areas of the substrate can help average out imperfections and provide a more representative measurement.

3. Using Optical Techniques: For substrates that are too rough for a stylus profilometer, using a non-contact, optical profilometer may help by avoiding physical interaction with the surface, although rough surfaces may still affect optical measurements.

In conclusion, low-quality substrates can work with profilometers, but the results may be less accurate or reliable. It is crucial to account for substrate imperfections when interpreting the data, and preparation or alternative measurement techniques may be necessary to obtain usable results.

What Is A Dektak Stylus?

A Dektak stylus refers to the stylus used in Dektak profilometers, which are highly regarded devices for surface measurement, particularly in research and industrial applications. Dektak is a brand from Bruker, a leading company in the field of precision measurement tools. The Dektak stylus profilometers are known for their accuracy in measuring surface topography, step height, roughness, and thin film thickness through contact-based methods.

Key Features of a Dektak Stylus Profilometer:

1. Stylus Contact Method:

   • A diamond-tipped stylus physically touches the surface of the material being measured and traces its contours.
   • The stylus is mechanically sensitive, allowing it to detect very small vertical displacements, often in the nanometer range.

2. High Precision:

   • Dektak profilometers are known for their high precision, capable of measuring features such as surface roughness, texture, and thin film thickness with nanometer accuracy.
   • They are used in industries like semiconductors, materials science, MEMS, and coatings to characterize surface features.

3. Step Height and Roughness Measurement:

   • The profilometer measures step heights (changes in surface height) by tracking the vertical deflection of the stylus as it moves horizontally across the sample surface.
   • This is particularly useful in microelectronics and thin film applications where precise thickness and roughness are critical.

4. Adjustable Stylus Force:

   • The force exerted by the stylus on the sample can be adjusted to optimize measurements for different materials, from hard surfaces like metals to more delicate films or substrates.
   • Reducing the force helps prevent damage to soft or sensitive surfaces.

5. Automated Scanning:

   • Dektak profilometers often feature automated scanning, where the stylus moves across the sample in a controlled, programmable path, ensuring repeatable and consistent measurements.

Applications of Dektak Stylus Profilometers:

• Thin Film Thickness Measurement: Dektak stylus profilometers are frequently used to measure the thickness of thin films and coatings deposited on substrates.
• Surface Roughness: They are employed in industries where surface texture and roughness are critical for product performance, such as optics, aerospace, and semiconductors.
• Microelectronics: Dektak profilometers are ideal for measuring step heights and pattern features in integrated circuits and MEMS devices.
• Stress Measurement: By measuring the curvature of a substrate before and after thin film deposition, Dektak stylus profilometers can be used to evaluate film stress.

In summary, a Dektak stylus is a highly precise mechanical probe used in Dektak's contact-based profilometers to measure surface characteristics. Its reliability and precision make it a standard tool for surface metrology in various scientific and industrial fields.