Week 3 Tissue Related Cancers- Breast Cancer and Oral
Cancer
Breast Cancer and Oral Cancer Statistics
It sounds like you're delving into a detailed process for fabricating SU-8 pillars on a gold pad
and creating a diaphragm for piezoresistive sensors. Here’s a concise summary of the key
points covered:
1. **Fabrication Overview**:
- The module focuses on creating SU-8 pillars on a gold pad and a diaphragm on the silicon
wafer.
2. **Initial Setup**:
- The chip features a layered structure: oxidized silicon wafer, nichrome heater, insulating
layers, interdigitated electrodes, piezoresistive materials, and gold pads.
3. **SU-8 Pillars**:
- **Spin Coating**: SU-8 is spin-coated to achieve a thickness of 50 microns.
- **Soft Bake**: Performed at 65°C.
- **UV Exposure**: A dark field mask is used for negative photoresist, ensuring pillars form
only in exposed areas.
- **Hard Bake**: Conducted at 90-95°C, strengthening the SU-8.
- **Development**: Unexposed areas are removed, leaving SU-8 pillars.
4. **Metal Coating**:
- PVD (Physical Vapor Deposition) is used to coat the SU-8 pillars with metal, typically by
tilting the wafer for effective coverage.
5. **Diaphragm Creation**:
- A positive photoresist is applied to the backside of the wafer, followed by soft baking, UV
exposure, and development.
- A hard bake is done to enhance the photoresist's strength.
- Buffer hydrofluoric acid (BHF) is used to etch the silicon dioxide.
- Deep Reactive Ion Etching (DRIE) creates the diaphragm, allowing for precise control of the
thickness.
6. **Final Structure**:
- The completed chip integrates multiple sensors, including piezoresistive sensors, with a
diaphragm for pressure detection.
7. **Application**:
, - The chips will be used to assess tissue properties, particularly for detecting changes in
electrical, mechanical, thermal, and pH properties in diseased tissues.
This process highlights the intersection of microfabrication techniques and biomedical
applications, illustrating how detailed engineering can enable advanced sensing technologies. If
you have any specific questions or areas you'd like to explore further, feel free to ask!
Fabrication of MEMs-based Biochip for cancer diagnosis
Here’s a concise summary of the key points from the module on depositing a gold pad over
piezoresistive material:
### Overview
- The module focuses on the process of depositing a gold pad on piezoresistive material to
enhance sensor functionality.
### Fabrication Steps
1. **Wafer Structure**:
- Begin with a silicon wafer containing:
- A nichrome heater.
- Interdigitated electrodes made from chrome and gold.
- Piezoresistive material on top.
2. **Insulation Layer**:
- Deposit a layer of silicon dioxide (SiO₂) over the piezoresistive material using PECVD
(Plasma Enhanced Chemical Vapor Deposition) to serve as an insulating layer.
3. **Contact Opening**:
- Use positive photoresist to protect the SiO₂ layer, followed by soft bake at 90°C for 1 minute.
- Employ a dark field mask to expose only the contact regions for gold pad deposition.
- Perform UV exposure and develop the photoresist, resulting in the SiO₂ layer being exposed
in the contact regions.
4. **Etching**:
- After hard baking the photoresist, dip the wafer in buffered hydrofluoric acid (BHF) to etch
away SiO₂ in the exposed areas.
- Strip off the photoresist using acetone.
5. **Gold Pad Deposition**:
- Deposit a thin layer of chrome followed by a gold layer on the exposed areas using PVD
(Physical Vapor Deposition).
6. **Patterning the Gold**:
, - Apply positive photoresist over the gold layer, followed by soft baking.
- Use a bright field mask to protect certain areas during UV exposure.
- Develop the photoresist, leaving it only in the desired regions.
7. **Final Etching**:
- Etch the gold and chrome layers in sequence to achieve the desired gold pad pattern.
- Strip off any remaining photoresist using acetone.
### Conclusion
- The final structure includes a gold pad on the interdigitated electrodes with piezoresistive
material beneath. The module sets the stage for the next steps in the fabrication process,
including the creation of SU-8 pillars and a diaphragm, essential for the biochip's function.
### Future Steps
- The next module will cover the fabrication of SU-8 pillars and the diaphragm, with an emphasis
on their role in detecting tissue property changes, particularly in cancer research.
If you need further clarification or have specific questions about any part of the process, feel
free to ask!
Fabrication of MEMs-based Biochip for cancer diagnosis
Contd..
### Key Points from the Module on Piezoresistive Material Deposition
1. **Overview**:
- This module focuses on depositing piezoresistive material on interdigitated electrodes (IDEs)
fabricated on a silicon dioxide (SiO₂) layer, which acts as an insulator over a micro heater.
2. **Recap of Previous Concepts**:
- Previous discussions included the fabrication of the micro heater, the oxide layer, the
interdigitated electrodes using chrome gold, and the insulating properties of the SiO₂ layers.
3. **Piezoresistive Material Techniques**:
- Two main techniques for depositing piezoresistive material:
- **Standard Lithography**: Involves using photoresist and etching techniques.
- **Lift-off Technique**: A simpler approach that avoids issues with etchants affecting
underlying layers.
4. **Reasons for Using PECVD**:
- PECVD allows for the deposition of SiO₂ at lower temperatures (100-400°C) compared to
thermal oxidation (1100°C), which is critical to avoid damaging temperature-sensitive materials
like nichrome.
Cancer
Breast Cancer and Oral Cancer Statistics
It sounds like you're delving into a detailed process for fabricating SU-8 pillars on a gold pad
and creating a diaphragm for piezoresistive sensors. Here’s a concise summary of the key
points covered:
1. **Fabrication Overview**:
- The module focuses on creating SU-8 pillars on a gold pad and a diaphragm on the silicon
wafer.
2. **Initial Setup**:
- The chip features a layered structure: oxidized silicon wafer, nichrome heater, insulating
layers, interdigitated electrodes, piezoresistive materials, and gold pads.
3. **SU-8 Pillars**:
- **Spin Coating**: SU-8 is spin-coated to achieve a thickness of 50 microns.
- **Soft Bake**: Performed at 65°C.
- **UV Exposure**: A dark field mask is used for negative photoresist, ensuring pillars form
only in exposed areas.
- **Hard Bake**: Conducted at 90-95°C, strengthening the SU-8.
- **Development**: Unexposed areas are removed, leaving SU-8 pillars.
4. **Metal Coating**:
- PVD (Physical Vapor Deposition) is used to coat the SU-8 pillars with metal, typically by
tilting the wafer for effective coverage.
5. **Diaphragm Creation**:
- A positive photoresist is applied to the backside of the wafer, followed by soft baking, UV
exposure, and development.
- A hard bake is done to enhance the photoresist's strength.
- Buffer hydrofluoric acid (BHF) is used to etch the silicon dioxide.
- Deep Reactive Ion Etching (DRIE) creates the diaphragm, allowing for precise control of the
thickness.
6. **Final Structure**:
- The completed chip integrates multiple sensors, including piezoresistive sensors, with a
diaphragm for pressure detection.
7. **Application**:
, - The chips will be used to assess tissue properties, particularly for detecting changes in
electrical, mechanical, thermal, and pH properties in diseased tissues.
This process highlights the intersection of microfabrication techniques and biomedical
applications, illustrating how detailed engineering can enable advanced sensing technologies. If
you have any specific questions or areas you'd like to explore further, feel free to ask!
Fabrication of MEMs-based Biochip for cancer diagnosis
Here’s a concise summary of the key points from the module on depositing a gold pad over
piezoresistive material:
### Overview
- The module focuses on the process of depositing a gold pad on piezoresistive material to
enhance sensor functionality.
### Fabrication Steps
1. **Wafer Structure**:
- Begin with a silicon wafer containing:
- A nichrome heater.
- Interdigitated electrodes made from chrome and gold.
- Piezoresistive material on top.
2. **Insulation Layer**:
- Deposit a layer of silicon dioxide (SiO₂) over the piezoresistive material using PECVD
(Plasma Enhanced Chemical Vapor Deposition) to serve as an insulating layer.
3. **Contact Opening**:
- Use positive photoresist to protect the SiO₂ layer, followed by soft bake at 90°C for 1 minute.
- Employ a dark field mask to expose only the contact regions for gold pad deposition.
- Perform UV exposure and develop the photoresist, resulting in the SiO₂ layer being exposed
in the contact regions.
4. **Etching**:
- After hard baking the photoresist, dip the wafer in buffered hydrofluoric acid (BHF) to etch
away SiO₂ in the exposed areas.
- Strip off the photoresist using acetone.
5. **Gold Pad Deposition**:
- Deposit a thin layer of chrome followed by a gold layer on the exposed areas using PVD
(Physical Vapor Deposition).
6. **Patterning the Gold**:
, - Apply positive photoresist over the gold layer, followed by soft baking.
- Use a bright field mask to protect certain areas during UV exposure.
- Develop the photoresist, leaving it only in the desired regions.
7. **Final Etching**:
- Etch the gold and chrome layers in sequence to achieve the desired gold pad pattern.
- Strip off any remaining photoresist using acetone.
### Conclusion
- The final structure includes a gold pad on the interdigitated electrodes with piezoresistive
material beneath. The module sets the stage for the next steps in the fabrication process,
including the creation of SU-8 pillars and a diaphragm, essential for the biochip's function.
### Future Steps
- The next module will cover the fabrication of SU-8 pillars and the diaphragm, with an emphasis
on their role in detecting tissue property changes, particularly in cancer research.
If you need further clarification or have specific questions about any part of the process, feel
free to ask!
Fabrication of MEMs-based Biochip for cancer diagnosis
Contd..
### Key Points from the Module on Piezoresistive Material Deposition
1. **Overview**:
- This module focuses on depositing piezoresistive material on interdigitated electrodes (IDEs)
fabricated on a silicon dioxide (SiO₂) layer, which acts as an insulator over a micro heater.
2. **Recap of Previous Concepts**:
- Previous discussions included the fabrication of the micro heater, the oxide layer, the
interdigitated electrodes using chrome gold, and the insulating properties of the SiO₂ layers.
3. **Piezoresistive Material Techniques**:
- Two main techniques for depositing piezoresistive material:
- **Standard Lithography**: Involves using photoresist and etching techniques.
- **Lift-off Technique**: A simpler approach that avoids issues with etchants affecting
underlying layers.
4. **Reasons for Using PECVD**:
- PECVD allows for the deposition of SiO₂ at lower temperatures (100-400°C) compared to
thermal oxidation (1100°C), which is critical to avoid damaging temperature-sensitive materials
like nichrome.
