Development of New Processing for Preparation Metal Oxides Thin Films with Excimer Laser lrradiation

Direct conversion of metal acetylacetonates and metal organic acid salts into metal oxides thin films using coating photolysis process with an ArF excimer laser under a 200�� is successfully developed. This also opens the possibilities of patterning for electronic device. With normal irradiation, only the ablation of metal organic acid salts occur, but decomposition does not take place. The newly developed two step irradiation method is found to be effective. That is, in the first step, irradiation with the ArF laser at 10mJ/cm² at a repetition rate of 50HZ for 0.5 min. and in the second step, the laser power was raised to 50mJ/cm² at a repetition rate of 10HZ for 5 min. Using this method, the decomposition was observed. This is exceedingly promising technical method for which the applications for a patent both in Japan and abroad have already been applied. Moreover, using this method, an oxide compound consisting two or more metallic elements has been processed directly at normal temperature for the first time in the world. It has proven that these starting materials are effective for not only metal organic acid salts but also for metal acetylacetonates and metal alkoxide with long carbon chain.

Background

For electronics or optical information processing which will be the core technologies of the twenty first century, it is essential to integrate highly functional metal oxide thin films into devices or systems. In many cases, however, many devices or systems which include materials such as semiconductor silicon or organic materials are sensitive to heat treatment. Thus, satisfying both conditions of being able to integrate metal oxides thin films at normal temperature and being able to pattern are very important requirements.

The actual examp]es of the metal oxides tbin Films succeeded
Sn0₂, In₂0₃ (possibility of applying to transparent conductive thin films fbr liquid crystal)

TiO₂ (possibility of applying to photocatalytic thin films)
Fe₂0₃ (possibility of applying to magnetic thin films)
PbTi0₃ (possibility of applying to ferroelectrics thin films)

Characteristics

1. Possible to process metal oxide materials by simply irradiating with excimer laser the materials coated with metal organic compound solution

2. Heating treatment not needed(under 200��) (Heating up to 500�� has been the usual process)

3. Possible to process in normal atmosphere (Not necessary to create vacuum space or to control atmosphere when sputtering or applying gas phase reaction)

4. Possible to pattern

5. Possible to extend the area

6. Possibility of precision control of composites

7. Possible to directly process oxide compounds

8. Has great advantage for applying the method to electronics