Illumination device

• US 5,296,891 A
• Filed: 10/29/1992
• Issued: 03/22/1994
• Est. Priority Date: 05/02/1990
• Status: Expired due to Term

• Current Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Original Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Inventors: Vogt, Holger, Kuck, Heinz, Hess, Gunther, Gehner, Andreas
• Primary Examiner(s): WINTERCORN, RICHARD
• Application Number:
  US07/940,958
• Time in Patent Office: 509 Days
• Field of Search: 355/53, 355/67, 355/71, 353/122, 346/107 R
• US Class Current: 355/67
• CPC Class Codes: G03F 7/70216 Mask projection systems
• CPC Class Codes: G03F 7/70283 Mask effects on the imaging process
• CPC Class Codes: G03F 7/70291 Addressable masks, e.g. spatial light modulators [SLMs], digital micro-mirror devices [DMDs] or liquid crystal display [LCD] patterning devices
• CPC Class Codes: G03F 7/70358 Scanning exposure, i.e. relative movement of patterned beam and workpiece during imaging
• CPC Class Codes: G03F 7/70425 Imaging strategies, e.g. for increasing throughput or resolution, printing product fields larger than the image field or compensating lithography- or non-lithography errors, e.g. proximity correction, mix-and-match, stitching or double patterning

Abstract

The illumination device (1) proposed is designed to produce models (6), or for the direct illumination of electronic elements, and includes a light source (2) and a pattern generator (3).

In order to shorten the necessary writing time or exposure time with a simplified illumination-device structure, the pattern generator (3) includes an optical schlieren system (15, 17) and an active, matrix-addressable surface light generator (13) which has a viscoelastic control layer with a reflective surface (19). Disposed between the schlieren lens (15) and the projection lens (16) in the schlieren system (14) is a mirror device (17) which preferably has two functions, not only deflecting the light from the light source (2) to the surface light modulator (13) but also filtering out undiffracted reflected light. The schlieren lens is located at a distance from the surface light modulator (13) which is short relative to the focal length of the lens. A positioning table (7) designed to hold the model (6), or the electronic element is disposed in such a way that sharp images of surface areas (19a, 19b) of the surface light modulator (13) can be produced on the model or the electronic element.

Claims

1. An illumination device for producing models used for manufacturing electronic elements, or for direct illumination of wafers or substrates during the photolithographic steeps required for their production, or for direct illumination of structures including light-sensitive layers, comprising:

a pulsed laser light source;

a pattern generator;

said pattern generator including an optical Schlieren system and an active, matrix-addressable surface light modulator;

said surface light modulator including a reflective surface having addressed surface areas which diffract incident light and non-addressed surface areas which reflect incident light;

said Schlieren system comprising a Schlieren lens arranged on a side of said surface light modulator, a projection lens facing away from said surface light modulator, and a mirror device arranged between said lenses for directing light coming from said light source onto said reflective surface on said surface light modulator;

means for focussing the light coming from said light source onto said mirror device;

wherein said Schlieren lens is arranged from said surface light modulator at a short distance relative to the focal length of said Schlieren lens;

a filter device arranged between said Schlieren lens and said projection leans, said filter device having a structural design to filter out undiffracted light reflected by said non-addressed surface areas of said surface light modulator and to permit diffracted light reflected by said addressed surface areas to pass via said projection lens to the model, or to the electronic element, or to the structure;

a displaceable positioning table for securing the model, or the electronic element, or the structure so that a sharp image of said addressed surface areas of said surface light modulator is formed on the model, or on the electronic element, or on the structure;

said pulse laser light source having a pulse duration shorter than the minimum structural dimension of the model to be produced, or of the electronic element, or of the structure divided by the displacement rate of said positioning table; and

during the displacement of the positioning table, the model, or the electronic element, or the structure is put together using a plurality of successive partial images by adequate addressing of said surface light modulator.

2. An illumination device according to claim 1, wherein said mirror device is arranged at a distance from said Schlieren lens corresponding to the focal length of said Schlieren lens, and said mirror device is said filter device in that it returns the undiffracted light reflected by said non-addressed surface areas to said light source.

3. An illumination device according to claim 1, wherein said mirror device is arranged at a distance from said Schlieren lens which is shorter than the focal length of said Schlieren lens, and said filter device forms a shutter for undiffracted light reflected by said non-addressed surface areas, said shutter being arranged at a distance from said Schlieren lens greater than the focal length of said Schlieren lens.

4. An illumination device according to claim 1, wherein said mirror device includes a bar-type mirror having a longitudinal axis (y) which extends parallel to a phase structure produced by the waviness of said reflective surface of said surface light modulator.

5. An illumination device according to claim 4, wherein said mirror device includes a plurality of bar-type mirrors, one of said bar-type mirrors being arranged at the focus of said Schlieren lens, and two additional bar-type mirrors are arranged such that the light coming from said light source and deflected by one of said bar-type mirrors towards said surface light modulator will fall on said other bar-type mirror in the case of undiffracted reflection by said non-addressed surface areas of said surface light modulator.

6. An illumination device according to claim 5, comprising:

a beam expansion optical system which transforms the light coming from said light source into a broad, essentially parallel bundle of light,

a first cylindrical lens system oriented in the direction of the phase structure and including a number of cylindrical lenses corresponding to the number of bar-type mirrors; and

a second cylindrical lens system arranged perpendicular to said first cylindrical lens system.

7. An illumination device according to claim 1, wherein said pulsed laser light source is an excimer laser light source.

8. An illumination device according to claim 1, wherein said surface light modulator and said positioning table are controlled such that each pixel of the model, or of the element, or of the structure to be illuminated is illuminated at least twice with partially overlapping images so that the displacement of the imaged pixel corresponds to the distance by which said positioning table has been displaced between the pulses for producing the images.

9. An illumination device according to claim 1, wherein, upon carrying out matrix addressing of said surface light modulator, said surface areas which have been recognized as being incapable of functioning are not addressed.

10. An illumination device according to claim 1, wherein each surface area of said surface light modulator has associated therewith two transistors each provided with one electrodes, which, in response to addressing of the respective surface area, will each produce at least one diffraction grating with said reflective surface arranged on a viscoelastic control layer covering said transistors.

11. An illumination device according to claim 1, comprising an automatic loading and unloading device for wafers or substrates, which permits fully automatic illumination of a batch of wafers or substrates.

12. An illumination device according to claim 1, comprising a preadjustment means and a fine adjustment means permitting accurate, repeated illuminations of the substrates during the production process.

13. An illumination device according to claim 12, wherein said surface light modulator is used as a programmable reference mark during preadjustment and fine adjustment.

14. An illumination device according to claim 1, wherein said surface light modulator has a viscoelastic control layer with said reflective surface arranged thereon.

15. An illumination device according to claim 14, wherein said reflective surface of the surface light modulator is covered with a liquid-crystal layer, and said electrically addressable surface areas cause a phase displacement and, consequently, a diffraction of the incident light.

16. An illumination device according to claim 1, wherein said surface light modulator has a reflective surface including addressable mechanical reeds, wherein bending of said reeds will cause a phase displacement and, consequently, a diffraction of the light.