Projection lens systems

#This invention relates to projection lens systems for exposure lithography in which a pattern on a mask or reticle is transferred onto a substrate such as a semiconductor wafer or glass plate. More particularly, the present invention is directed to projection lens systems that have high resolution, high numerical apertures, and wide fields of view. In addition, the projection lens systems are substantially doubly telecentric and diffraction limited. Such projection lens systems provide optimal lithography for I-line, g-line, and excimer laser applications.

#In semiconductor device manufacturing, projection optical systems are used to transfer integrated circuit (IC) patterns such as large scale integrated (LSI) circuit patterns from a reticle onto a wafer or semiconductor substrate upon which the semiconductor device is to be formed. Because of the difference in the relative sizes of the reticle, which is typically larger than the resulting semiconductor device, projection optical systems must be reduction projection optical systems. A reticle is also known as a mask and the resulting semiconductor device is also known as a die or a semiconductor chip.

#Modern integrated circuits are becoming more integrated; that is, more and more functions are being designed into circuits to be manufactured on a single die. However, to maintain or improve the performance and speed of the semiconductor devices being manufactured there is a major effort not to allow the die to grow in size. In order to maintain the same or a reduced die size, the reduction projection optical system for the manufacture of the more complex semiconductor devices must have a wider exposure area, higher resolution, and a higher numerical aperture.

#The accompanying drawings incorporated in and forming a part of the specification, illustrate the present invention, and together with the detailed description below serve to explain the principles of the invention. In the drawings:

#FIG. 1A is a schematic diagram of the projection lens system according to a first embodiment of the present invention.

#FIG. 1B shows the longitudinal spherical aberration, the astigmatic field curves, and the distortion of the projection lens system shown in FIG. 1A.

#The following detailed description is of the presently preferred embodiments of the present invention. It is to be understood that while the detailed description is given utilizing the drawings briefly described above, the invention is not limited to the illustrated embodiments. In the detailed description, like reference numbers refer to like elements.

#Referring now to the Figures, the embodiments of the present invention will now be described. According to standard practice in the optical art, drawings of optical lens systems, such as those shown in the Figures, have the object space, defined as all the space from the first element or surface of a system towards the object and beyond, shown on the left in the drawing. Similarly, the image space, defined as all the space from the last element or surface of a system towards the image and beyond, is shown on the right in the drawing.

#Referring to FIG. 1A, a first embodiment of a projection lens system in accordance with the present invention is shown. In general, a projection lens system such as the projection lens system shown in FIG. 1A includes an illumination system (IS) 100, a reticle 102 mounted on a reticle stage 104, located at the object or reticle plane 106, a projection lens system 108, a substrate 110, located at the image or substrate plane 112, and mounted on a substrate stage 114. As can be appreciated by a person of ordinary skill in the exposure lithography art, the above components are mounted in a stable secure structure which is not shown in this or any of the succeeding figures. The required mounting structure is well known in the exposure lithography art and will not be discussed.