Radiation sensitive polymer systems

MOBEAu AND visWANATHAN Radiation Sensitive Polymer Systems 109... 

MOREAU AND viswANATHAN Radiation Sensitive Polymer Systems 113... 

MOREAU AND VKWANATHAN Radiation Sensitive Polymer Systems 117... 

One of the most suitable systems for grafting is a radiation-sensitive polymer in the presence of radiation-insensitive monomer. With this combination, the grafting of monomer to the polymer backbone is favored... 

In addition to the binary classification based on the imaging tone, resists can be divided on the basis of their design into 1) one-component and 2) multi-component systems (Fig. 4). One-component resists consist of pure radiation-sensitive polymers that must combine all the necessary attributes as mentioned above, and have long lost ground. The modern advanced lithography is ex-... 

The PS/PMMA blends containing 100, 90 and 70 wt% PS showed increasing radiation sensitivity. These systems could be considered dispersions of PMMA in a PS matrix, where the flexural strength is determined by the matrix. Addition of PMMA did not greatly reduce the radiation resistance of PS and addition of 10 wt% PS did not increase the radiation resistance of PMMA. In the blends, a protective effect of higher concentrations of PS was observed — this effect depended on the MW of the component polymers. 

There are a number of important factors that must be considered before applying gamma radiation-induced grafting. These factors include the radiation sensitivity of the polymer/monomer system, radiation dose and dose rate, type and concentration of inhibitor, type of solvent or diluent, and monomer concentration. The effect of such parameters on the grafting efficiency during mutual grafting is given below. 

Ionizing radiation is unselective and has its effect on the monomer, the polymer, the solvent, and any other substances present in the system. The radiation sensitivity of a substrate is measured in terms of its G value or free radical yield G(R). Since radiation-induced grafting proceeds by generation of free radicals on the polymer as well as on the monomer, the highest graft yield is obtained when the free radical yield for the polymer is much greater than that for the monomer. Hence, the free radical yield plays an important role in grafting process [85]. 

Resist systems may be more complicated than just a single polymer in a single solvent. They may be composed of polymer, polymer/dye, or polymer/polymer combinations (where the small molecule dye or additional polymer increases the radiation sensitivity of the resist film) with one or more solvents. The more complicated polymer/dye or polymer/polymer systems have the added possibilities of phase separation or aggregation during the non-equilibrium casting process. Law (16 I investigated the effects of spin casting on a... 

---