Phase shifting mask comprising a multilayer structure and method of forming a pattern using the same

A transmission phase shifting mask comprising:

• a substrate transparent to exposure light;
• a region which is formed on said substrate and translucent to exposure light;
• and
• a region which is formed on said substrate and transparent to exposure light,
• wherein a phase difference between light transmitted through said translucent region and light transmitted through said transparent region is set to be a desired value, and absolute values of complex indexes of refraction of materials constituting said translucent region are set to gradually increase away from a substrate side up to a maximum value, and gradually decrease afterward.

A method of forming a pattern, comprising the steps of:

• preparing a transmission phase shifting mask in which a transparent region and a translucent region are on a transparent substrate, said translucent region formed by stacking a first translucent layer for reflection reduction, a second translucent layer, and a third translucent layer for reflection reduction, said first translucent layer being formed on said substrate and having a larger absolute value of a complex index of refraction than that of said substrate, said second translucent film being formed above said first translucent layer and having a larger absolute value of a complex index of refraction than that of said first translucent layer, said third translucent layer being formed above said second translucent layer and having an absolute value of a complex index of refraction between that of said second translucent layer and that of an atmosphere through which said exposure light enters said third layer, and a phase difference of about 180.degree. is formed between light transmitted through said translucent region and light transmitted through said transparent region;
• radiating exposure light having a shorter wavelength than an ultraviolet ray on said transmission phase shifting mask, and exposing a pattern image of said mask onto a substrate, on which at least one photosensitive resin layer is formed, through an exposure optical system;
• and
• removing the photosensitive resin layer from a region other than a desired region in accordance with an exposure amount difference due to the mask pattern image.

A method of forming a pattern, comprising the steps of:

• preparing a transmission phase shifting mask in which a translucent region and a transparent region are formed on a transparent substrate, and absolute values of complex indexes of refraction of materials constituting said translucent region gradually increase away from a transparent substrate side up to a maximum value, and gradually decrease afterward;
• radiating exposure light having a shorter wavelength than an ultraviolet ray on said transmission phase shifting mask, and exposing a pattern image of said mask onto a substrate, on which at least one photosensitive resin layer is formed, through an exposure optical system;
• and
• removing the photosensitive resin layer from a region other than a desired region in accordance with an exposure amount difference due to the mask pattern image.