Adjustable Transmission Phase Shift Mask

Abstract

A phase shift mask having transmission properties that are dependent at least in part on an intensity of an incident light beam. The phase shift mask has a mask substrate that is substantially transparent to the incident light beam. A first phase shift layer is disposed on the mask substrate. The first phase shift layer has a refractive index that is nonlinear with the intensity of the incident light beam. The refractive index of the first phase shift layer changes with the intensity of the incident light beam on the phase shift mask. By using a first phase shift layer on the phase shift mask that has a refractive index that is non linear with the intensity of the incident light beam, properties of a light beam transmitted through the first phase shift layer, such as interference patterns in the transmitted light beam, can be adjusted by adjusting the intensity of the incident light beam. Thus, in this manner there is provided an additional tool by which the exposure patterns produced by the phase shift mask can be adjusted. In other words, the transmission properties of the phase shift mask are adjustable with the intensity of the incident light beam.

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         7 . An integrated circuit having a structure with feature sizes smaller than a wavelength of the incident light beam, the structure patterned with a phase shift mask having transmission properties that are dependent at least in part on an intensity of an incident light beam, the phase shift mask comprising: 
 a mask substrate that is substantially transparent to the incident light beam, and    a patterned first phase shift layer disposed on the mask substrate, the first phase shift layer having a refractive index that is nonlinear with the intensity of the incident light beam, wherein the refractive index of the first phase shift layer changes with the intensity of the incident light beam on the phase shift mask.    
     
     
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         20 . An integrated circuit formed with the method of: 
 applying photoresist to a layer on a substrate,    passing an incident light beam through a phase shift mask to produce a transmitted light beam, where the phase shift mask includes a mask substrate that is substantially transparent to the incident light beam, and a first phase shift layer disposed on the mask substrate, the first phase shift layer having a refractive index that is nonlinear with an intensity of the incident light beam, wherein the refractive index of the first phase shift layer changes with the intensity of the incident light beam on the phase shift mask,    adjusting properties of the transmitted light beam as propagated through the first phase shift layer by adjusting the intensity of the incident light beam,    exposing the desired pattern in the photoresist with the transmitted light beam, where the adjusted properties of the transmitted light beam assist in producing the desired pattern,    developing the photoresist to provide an etching mask, and    etching the layer on the substrate to form a structure of the integrated circuit,    where the structure of the integrated circuit has feature sizes smaller than a wavelength of the incident light beam.