Resist

Definition

In the context of nanofabrication, a resist is a photosensitive material used to form a patterned coating on a substrate, which can be either positive or negative. When exposed to light or energy from a scanning probe, the resist undergoes a chemical change that allows selective removal of areas, enabling the creation of intricate patterns necessary for device fabrication.

5 Must Know Facts For Your Next Test

1. Resists are crucial in defining micro and nanoscale patterns during the fabrication of semiconductor devices.
2. The choice between positive and negative resists impacts the final pattern; positive resists become soluble where exposed, while negative resists become insoluble in those areas.
3. Resists must have specific properties such as resolution, sensitivity, and contrast to ensure accurate pattern transfer during fabrication.
4. In scanning probe lithography, resists can be directly written onto substrates with high precision using a scanning probe, allowing for custom nanostructures.
5. Developing the resist after exposure is essential; it determines the final pattern's fidelity and is influenced by factors like developer concentration and time.

Review Questions

• How do positive and negative resists differ in terms of their chemical behavior when exposed to light or energy?
  • Positive resists become more soluble in the developer solution where they are exposed to light or energy, allowing those areas to be washed away and leaving behind the unexposed regions. In contrast, negative resists undergo a cross-linking reaction upon exposure, making the exposed areas less soluble and allowing them to remain on the substrate after development. This fundamental difference affects how patterns are created during the lithography process.
• What role does resist play in the overall lithography process and how does it influence device fabrication?
  • Resist serves as a temporary mask during lithography by defining patterns on substrates. Its ability to undergo chemical changes upon exposure allows for selective removal of material, which is critical for creating intricate designs necessary for semiconductor devices. The quality of the resist affects resolution and pattern fidelity, directly influencing the performance and reliability of the final devices.
• Evaluate the impact of resist choice on the advancements in nanofabrication techniques such as scanning probe lithography.
  • The choice of resist significantly influences advancements in nanofabrication techniques like scanning probe lithography. Different types of resists can enhance resolution and precision, enabling researchers to create increasingly complex nanoscale structures. As new materials and formulations are developed, they can lead to improved sensitivity and contrast, pushing the boundaries of what can be achieved in nanoscale patterning. The evolution of resist technology is therefore essential for advancing various applications in nanoelectronics and beyond.

Related terms

Photoresist: A type of resist that changes its solubility when exposed to light, commonly used in photolithography to create patterns on semiconductor wafers.

Etching: A process used in conjunction with resists to remove material from the surface of a substrate, typically after the resist has been applied and patterned.

Lift-off Process: A technique that involves applying a resist layer, depositing a film, and then removing the resist to leave behind the desired pattern on the substrate.