Characteristic aspects of electron beam curing are described in conjunction with thermal and ultra-violet curings. Advantage and disadvantage of electron beam curing are discussed in comparison with those of other processes.
A few processes commercialized in Japan will be introduced together with some technical features.
Present situation of the electron beam curing in the world is reviewed. At the same time, a comment will be given on the situation among different kinds of radiation processings.
Finally, future prospect of the electron beam curing will be tried to forsee. Importance of the role of electron beam curing in the field of advanced technology will be emphasized.

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Polymethacrylates containing pyrimidine base derivatives, and copolymers of butadiene with methacrylate monomer containing pyrimidine bases were prepared and studied for photodimerization of pyrimidine base units, grafted to the polymer chain. These polymers were found to be applicable as negative type photoresists. Photolysis of the polymers caused dimerization of pyrimidine bases and leaded to the photocrosslinking of the polymer chains. The photolithographic evaluation of these polymers showed high sensitivity, high resolution values of ever 1μm.
On the other hand, the application of polyamides synthesized by polycondensation of the thymine photodimer and various diamines into positive resists were studied. The photolysis of these polymers caused dissociation of the thymine photodimers, leading to the breakage of the polymer chains. These polymer indicated very high resolution values of even 0.3μm.

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Contrast enhancement, wall profile control and sensitivity increase all are important factors for resists used in microlithography. The use of contrast enhancement layers is accompanied by a sacrifice of resist sensitivity and has been limited to application to positive type photoresists. SPACE process has been reported for a negative working electron beam resist. With a controlled UV-flood exposure, enhancements in both contrast and sensitivity of RD2000N resist have been obtained. However, its application is limited to a negative working resist.
The concept of SPACE may be expanded to other types of resists and lithographies such as positive working photoresists. I wish to present here contrast enhancement and resist wall profile control by photochemical surface crosslinkage. With addition of a crosslinking agent like an aromatic bisazide which has its UV absorption band far away from an imaging wavelength, one can obtain contrast enhancement, control of resist wall profiles and reduction of resist thickness loss during image development after photochemical surface crosslinkage.
There are several processes reported for maintaining resist wall profiles at high temperature. However, resist images thicker than 3μm tend to have surface reticulation after high temperature heating. Pulsed electron beam resist hardening solves this problem. Certain chemical treatments of resist images provide not only thermal flow resistance but also specific RIE resistance. These processes for maintaining resist wall profiles at high temperatures will also be presented.

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Various high sensitive electron-beam resists have been reported to be developed. Some of these electron-beam resists can also be applied to X-ray exposure system. However, because of their poor characteristics for X-ray absorption, most of them often show low sensitivity. Poly-1, 3-dichloro-2-propyl acrylate (1, 3-DCPA) enhances absorption at 4.37A of palladium (PdLα) X-ray and show higher X-ray sensitivity, due to the presence of chlorine atom. It is one of the fast negative X-ray resists which show good overall characteristics.
This paper presents experimental results of 1, 3-DCPA which is fabricated in our certain technological process. Sensitivity of the developed resist to Pd X-ray at 4.37A was determined to be 20-30mJ/cm2. When 1, 3-DCPA was applied to the projection lithography, where the gap between mask and silicon wafer was about 30μm, resolution was found to be 1-2μ and contrast to be 0.8-1.0. A new type of high sensitive X-ray negative resist, 1, 3-DCPA, was then developed to meet the requirements of domestics research on X-ray exposure and tests on X-ray exposure technological process.

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