High resolution imagery systems and methods

• US 5,156,943 A
• Filed: 05/08/1990
• Issued: 10/20/1992
• Est. Priority Date: 10/25/1987
• Status: Expired due to Term

• Current Assignee: High Resolution Optics Corporation (Acacia Research Corporation)
• Original Assignee: Theodore R. Whitney
• Inventors: Whitney, Theodore R.
• Primary Examiner(s): McCamish, Marion E.
• Assistant Examiner(s): Dote, Janis L.
• Application Number:
  US07/520,629
• Time in Patent Office: 896 Days
• Field of Search: 430/321, 430/329, 430/324, 430/1, 430/2, 430/323, 430/22, 350/162.16, 350/162.2, 350/162.22, 359/565, 359/569, 359/572
• US Class Current: 430/321
• CPC Class Codes: G02B 27/0037 with diffracting elements G02B27/0056 takes precedence; holographic optical elements G02B5/32; zone systems G02B5/1876
• CPC Class Codes: G02B 27/4211 correcting chromatic aberrations G02B27/0056, G02B27/4222, G02B27/4227 take precedence
• CPC Class Codes: G02B 27/4216 correcting geometrical aberrations
• CPC Class Codes: G02B 27/4222 in projection exposure systems, e.g. photolithographic systems
• CPC Class Codes: G02B 5/1876 Diffractive Fresnel lenses; Zone plates; Kinoforms G02B5/1842, G02B5/1847 take precedence; optical systems having diffractive correction means G02B27/0037; Fresnel lenses operating by refraction G02B3/08
• CPC Class Codes: G02B 5/188 Plurality of such optical elements formed in or on a supporting substrate
• CPC Class Codes: G03F 7/70066 Size and form of the illuminated area in the mask plane, e.g. reticle masking blades or blinds
• CPC Class Codes: G03F 7/70583 Speckle reduction, e.g. coherence control or amplitude/wavefront splitting
• CPC Class Codes: G03F 9/7049 Technique, e.g. interferometric

Abstract

The current limits of resolution of multi-element optical systems are exceeded by reducing the number of elements while introducing at the critical aperture a blazed transmission grating having grating rings of low bending power defined by multiple plateaus. By illuminating the optical train with monochromatic light that constitutes a multiplicity of distributed sources having a substantial temporal coherence but spatial incoherence and by varying the slopes and widths of the grating rings, local phase delays are introduced that adjust aberrations in the optical system, providing an aligned composite wavefront. The system and method may be used for presenting an image, as for a wafer stepper, or for viewing an image, as in a microscope.

Claims

1. The method of making a blazed grating phase lens comprising the steps of:

layering a photoresist material on a light transmissive planar element;

forming the image of a plurality of first tracks on the photoresist material;

forming first tracks of a given differential height on the planar element;

removing the first layer of photoresist material; and

forming, using like sequences, successive tracks on the planar element of differential height that vary in binary fashion to the given differential height and selectively overlay in cumulative fashion to form incrementally varying progressions.

2. The method as set forth in claim 1 above, wherein the images are formed by illuminating through individual photomasks.

3. The method as set forth in claim 2 above, wherein the tracks are concentric circles and wherein the images are formed by dynamic writing of tracks in the photoresist material while rotating the planar element.

4. The method as set forth in claim 1 above, further including the steps of initially writing reference patterns on the planar element at a chosen region, and forming the image of successive tracks with reference to the reference patterns.

5. The method as set forth in claim 4 above, wherein the reference patterns are written at positions chosen within arbitrary limits on opposite sides of the locations for the tracks, wherein the tracks are to be in the form of concentric rings, and further including the steps of calibrating the system by determining the center of the tracks, and radial track position relative to the center, from the reference patterns.