How MIBK works on PMMA developer in electron beam lithography?

Electron beam lithography technology is one of the key processes in microelectronics manufacturing, and the developer plays an important role in this process. In this paper, the principle of MIBK (methyl isobutyl ketone) on PMMA (polymethyl methacrylate) developer in electron beam lithography will be discussed in depth.

What are MIBK and PMMA?

MIBK is a ketone solvent with high boiling point and low toxicity, which is widely used in the development process of lithography technology. PMMA is a commonly used electron beam photoresist known for its high resolution and excellent processing properties. In electron beam lithography, PMMA is coated on the surface of the substrate. After electron beam exposure, the exposed area needs to be dissolved by a developer to achieve pattern transfer.

The role of MIBK in the development process

in electron beam lithography, PMMA photoresist will undergo chemical crosslinking reaction under the irradiation of electron beam. The role of the developer is to selectively dissolve these cross-linked domains to form the desired micro-or nano-scale pattern. MIBK as an efficient developer, mainly through the following aspects to play a role:

1. dissolved cross-linked product: PMMA after electron beam exposure, the degree of crosslinking significantly increased, the formation of insoluble areas. MIBK can effectively dissolve these cross-linked products to achieve development.
2. control development rate: The high boiling point and low volatility of MIBK enable it to be used at higher temperatures, thereby increasing the development rate. At the same time, its chemical stability makes it difficult to decompose during the development process, ensuring the stability and consistency of the development process.
3. Improve development uniformity: MIBK can uniformly penetrate into all areas of the PMMA photoresist, thereby achieving a uniform development effect.

In-depth analysis of MIBK developing mechanism

in electron beam lithography, the development process of PMMA photoresist can be divided into the following steps:

1. photoresist coating: PMMA solution is coated on the surface of the substrate, and a uniform film is formed after spin coating and baking.
2. electron beam exposure: The electron beam is irradiated on the PMMA film, causing the cross-linking reaction of the photoresist molecular chain to form the exposed area. The molecular chains in the unexposed regions retain their original structure.
3. Developer treatment the MIBK developer is in contact with the PMMA film to dissolve the cross-linked exposed areas so that the exposed areas are selectively removed, thereby forming the desired pattern.

MIBK can selectively dissolve the cross-linked regions of PMMA during the development process, mainly related to its polarity, solubility and chemical stability. The molecular structure of MIBK enables it to form a strong intermolecular force with the cross-linked product of PMMA, thereby achieving an efficient dissolution effect.

Factors Affecting the Development Effect

in practical application, the effect of MIBK developer is affected by many factors, including the concentration of MIBK, developing temperature and time. Here is an analysis of some key factors:

1. MIBK concentration: The concentration of MIBK directly affects the development rate and development depth. A higher MIBK concentration can generally increase the development rate, but an excessively high concentration may cause excessive dissolution of the substrate material and affect the development effect.
2. developing temperature: The increase of the development temperature can accelerate the development rate, but too high temperature may cause the volatilization and decomposition of MIBK, which affects the stability of the development process.
3. Development time: The length of the development time needs to find a balance between the dissolution effect and the damage of the substrate material. An excessively long development time may cause the PMMA in the unexposed areas to be partially dissolved, affecting the resolution of the pattern.

Advantages of MIBK developer

compared with other developers, the application of MIBK in PMMA developer has significant advantages:

1. high boiling point and low volatility: The high boiling point of MIBK enables it to be used at higher temperatures, thereby increasing the development rate. At the same time, its low volatility makes it difficult to evaporate during the development process, ensuring the stability and consistency of the development process.
2. Excellent dissolving capacity: MIBK can efficiently dissolve the cross-linked product of PMMA, thereby achieving a high-resolution development effect.
3. Good chemical stability: MIBK is not easy to decompose during the development process, thereby extending the service life of the developer.

Summary

the action principle of MIBK in PMMA developer is to achieve development by dissolving the cross-linked product of PMMA. Its high boiling point, low volatility and excellent solubility make MIBK one of the commonly used developers in electron beam lithography. In practical application, the effect of MIBK developer is affected by many factors, such as concentration, temperature and time, so it is necessary to optimize these parameters reasonably to obtain the best development effect. With the continuous development of microelectronics technology, the application of MIBK developer in electron beam lithography will be more extensive.