The microelectronics industry is run on three important principles: precision, pushing the boundaries of miniaturisation and performance with each technological advancement. To achieve any of this, high-resolution photoresists are essential. These are specialised materials that enable the intricate patterning required to fabricate those microelectronic devices. With the demand for smaller, faster and more powerful components ever increasing, high-resolution photoresists are set to play a critical role in precision fabrication for a long time into the future.
Understanding high-resolution photoresists
Photoresists are used as part of the photolithography process. They are light sensitive materials that are essential for defining circuit patterns on semiconductor wafers. It is high-resolution photoresists that are required to achieve the exceptionally fine feature sizes, often at the nanometre scale, that are required to ensure the accuracy needed for modern microelectronics.
High-resolution photoresists function thanks to chemical changes that occur when they are exposed to specific light wavelengths. These changes result in the selective removal of either the exposed or unexposed areas depending on whether a positive or negative resist is chosen. This enables the precise etching of a complex circuit pattern, which is crucial for developing things like transistors, microprocessors and memory chips.
Types of high-resolution photoresists
1. Positive photoresists
When using positive photoresists, it is the exposed regions which become soluble, allowing for selective removal. They are chosen for their superior resolution, which means they are ideal for submicron and nanometre scale features. They are most used in advanced semiconductor manufacturing, such as extreme ultraviolet (EUV) lithography.
2. Negative photoresists
In contrast to positive photoresists, when using negative photoresists, the exposed regions become insoluble to create a robust framework for fabrication. This means they are typically used for applications that require higher etch resistance and durability. They have less resolution than positive resists, but they are extremely useful in applications that require a thicker resist layer.
3. Chemically amplified resists (CARs)
A chemically amplified resist enhances sensitivity to light exposure, therefore reducing the required exposure energy. These types of resists are critical in EUV and deep ultraviolet (DUV) lithography for next-generation chip manufacturing. This is because they enable ultrafine feature sizes for cutting edge microelectronics.
4. Hybrid and advanced photoresists
Hybrid and advanced photoresists have been developed for specific applications such as multi-patterning techniques. They are used in advanced node semiconductor manufacturing to achieve feature sizes below 5nm and incorporate novel polymer structures to enhance both resolution and contrast.
The role of high-resolution photoresists in precision fabrication
As we live in a world that constantly wants our devices to be smaller but with higher levels of performance, it is essential that extreme precision in lithography is used. High-resolution photoresists enable this by allowing semiconductor manufacturers to produce transistors and circuit features at the nanometre scale, enabling modern processors, memory chips and other microelectronic components.
Precision fabrication is needed in microelectronics to help optimise power consumption, speed and efficiency. High-resolution photoresists can facilitate the creation of densely packed circuits which minimise power loss and improve overall device efficiency.
Specialised photoresists with high sensitivity and resolution are also needed in the emerging lithography technologies such as EUV and nanoimprint lithography. These advanced resists contribute to reducing manufacturing costs and increasing production yields by minimising any defects and improving pattern fidelity.
High-resolution photoresists also mean that devices can benefit from enhanced durability and reliability. Thanks to their precise patterning, semiconductor components tend to experience fewer defects, which reduces failure rates and extends the lifespan of electronic products.
Future innovations of high-resolution photoresists
It is likely that the next generation of EUV resists will support even smaller feature sizes that go below 3nm. They will also help to explore novel materials that enable more efficient pattern formation through molecular self-assembly. By combining multiple patterning techniques in hybrid lithography approaches, it may also be possible to achieve superior resolution and cost effectiveness across a range of different production processes.
It is now the case that high-resolution photoresists are proving to be indispensable in precision fabrication for microelectronics. They are helping to enable the continued advancement of semiconductor technology, and so as devices shrink and performance demands grow, the innovations in photoresist materials and processes are likely to drive the next wave of technological breakthroughs. By leveraging cutting edge research, these high-resolution photoresists are likely to remain a key part of semiconductor manufacturing by ensuring the development of faster, smaller and more efficient electronic devices.
