Method for selectively exposing a light pattern to a photosensitive work surface

• US 20010028993A1
• Filed: 05/25/2001
• Published: 10/11/2001
• Est. Priority Date: 07/27/1999
• Status: Active Grant

• Current Assignee: James E. Sanford
• Original Assignee: James E. Sanford
• Inventors: Sanford, James E.
• Granted Patent: US 6,436,610 B2
• Time in Patent Office: Days
• US Class Current: 430/313
• CPC Class Codes: G02B 26/02 for controlling the intensity of light G02B26/004 takes precedence
• 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 7/70383 Direct write, i.e. pattern is written directly without the use of a mask by one or multiple beams maskless lithography using a programmable mask G03F7/70291

Abstract

A maskless exposure system for selectively exposing a photosensitive work surface, such as a photoresist layer, includes a semiconductor substrate having an elongated aperture. A series of shutters and associated guides are formed upon the substrate using conventional wafer processing methods. The shutters move between a first position covering the aperture and a second position exposing the aperture. A corresponding series of computer-controlled actuators, in the form of electromagnetic coils, cooperate with the shutters for selectively sliding each shutter between its first and second positions. A light beam is directed toward the aperture, and the shutters create a patterned light beam exiting the aperture. A computer-controlled stepper is synchronized with the shutter actuators and adjusts the relationship between the patterned light beam and the photosensitive work surface to direct the patterned light beam at different portions of the work material.

Claims

1. A maskless exposure system for selectively exposing a work material having a photosensitive work surface to light, said maskless exposure system comprising in combination:

a. a substrate having an elongated aperture formed therein, said substrate generally lying in a plane;

b. a source of a light beam directed generally toward the elongated aperture;

c. a plurality of shutter elements movably supported upon said substrate, each of said shutter elements having a first position covering a portion of the elongated aperture and preventing the passage of light through such portion, and each of said shutter elements having a second position exposing a portion of the elongated aperture for allowing the passage of light through such portion, each of said plurality of shutter elements extending generally parallel to the plane of said substrate, said plurality of shutter elements creating a patterned light beam exiting the elongated aperture of said substrate;

d. a plurality of actuators, each of said actuators cooperating with a related one of said plurality of shutter elements for selectively moving said related shutter element between its first position and its second position;

e. a work material support for supporting a work material having a photosensitive work surface; and

f. a stepper for adjusting the relationship between the patterned light beam exiting the elongated aperture of said substrate and the work material support in order to direct the patterned light beam at different portions of the photosensitive work surface of the work material.

2. The maskless exposure system recited by

claim 1

wherein said substrate is formed of a predetermined semiconductor material, and wherein said plurality of shutter elements are formed from a layer of material that was once secured to said substrate.

3. The maskless exposure system recited by

claim 2

wherein said plurality of shutter elements are formed from of semiconductor material.

4. The maskless exposure system recited by

claim 2

wherein said plurality of shutter elements are formed from a layer of metal deposited upon said substrate.

5. The maskless exposure system recited by

claim 1

wherein each of said plurality of shutter elements slides in a linear motion between its first and second positions.

6. The maskless exposure system recited by

claim 5

including a plurality of guides secured to said substrate, each of said guides extending about one of said plurality of shutter elements for guiding movement of said shutter element.

7. The maskless exposure system recited by

claim 5

wherein said plurality of shutter elements includes a first shutter element and a second shutter element, the first shutter element and the second shutter element each having a side edge, and wherein the side edge of the first shutter element extends closely proximate the side edge of the second shutter element when both the first and second shutter elements are in the first position covering a portion of the elongated aperture.

8. The maskless exposure system recited by

claim 7

wherein said further and second shutter elements lie on opposite sides of the elongated aperture.

9. The maskless exposure system recited by

claim 1

wherein each of said plurality of shutter elements incorporates a small permanent magnet, and wherein each of said plurality of actuators includes an electromagnet in the form of a coiled electrical conductor for repelling or attracting a related one of said plurality of shutter elements.

10. The maskless exposure system recited by

claim 9

wherein said plurality of actuators includes first and second actuators, and including magnetic shielding interposed between said first and second actuators.

11. A method for selectively exposing a light pattern to a photosensitive work surface of a work material, said method comprising the steps of:

a. providing a substrate having an elongated aperture formed therein, the substrate generally lying in a plane;

b. providing a beam of light that can be directed generally toward the elongated aperture;

c. supporting a plurality of shutter elements upon the substrate, each of the shutter elements being movable between a first position covering a portion of the elongated aperture and a second position exposing a portion of the elongated aperture, each of the shutter elements extending generally parallel to the plane of the substrate whether in the first position or second position;

d. moving each of the shutter elements to either its first position or its second position to selectively block or pass portions of the beam of light in order to create a first patterned light beam exiting the elongated aperture of the substrate;

e. directing the beam of light toward the elongated aperture for generating the first patterned light beam; and

f. directing the first patterned light beam upon a first portion of the photosensitive work surface of the work material.

12. The method recited by

claim 11

including the additional steps of:

g. moving each of the shutter elements to either its first position or its second position to selectively block or pass portions of the beam of light in order to create a second patterned light beam exiting the elongated aperture of the substrate;

h. directing the beam of light toward the elongated aperture for generating the second patterned light beam; and

i. directing the second patterned light beam upon a second portion of the photosensitive work surface of the work material.

13. The method recited by

claim 12

wherein the steps recited in

claim 12

are repeated for third and subsequent portions of the photosensitive work surface of the work material until substantially all portions of the photosensitive work surface have been exposed to a respective patterned light beam.

14. The method recited by

claim 11

wherein the substrate is a wafer made of a semiconductor material, and wherein the shutter elements are formed by the steps of:

a. forming a first sacrificial layer of a material upon a surface of the substrate;

b. depositing a first deposited layer of material upon the first sacrificial layer;

c. patterning the first deposited layer of material to form the shutter elements; and

d. etching the first sacrificial layer underlying the patterned first deposited-layer of material for allowing the shutter elements to move relative to the substrate.

15. The method recited by

claim 14

wherein the first deposited layer of material is semiconductor material.

16. The method recited by

claim 14

wherein the first deposited layer of material is a metal.

17. The method recited by

claim 14

wherein the first sacrificial layer is composed of a material selected from the group consisting of oxides and nitrides of the semiconductor material

18. The method recited by

claim 14

wherein the first sacrificial layer is a polymer material.

19. The method recited by

claim 14

further including the steps of:

e. forming a second sacrificial layer of a material upon the surface of the substrate overlying the first deposited layer;

f. depositing a second deposited layer of material upon the second sacrificial layer;

g. patterning the second deposited layer to form guide elements that bridge across a shutter element; and

h. etching the second sacrificial layer underlying the patterned second deposited second layer for allowing the shutter elements to slide within the guide elements.

20. The method recited by

claim 11

wherein the step of moving each of the plurality of shutter elements between its first and second positions includes the step of sliding each such shutter element along a linear path.

21. The method recited by

claim 20

including the step of positioning each shutter element within at least one surrounding guide for guiding sliding movements of each such shutter element.

22. The method recited by

claim 20

including the step of positioning successive shutter elements on alternating sides of the elongated aperture.

23. The method recited by

claim 20

wherein the step of moving each of the shutter elements includes the steps of:

a. providing a small permanent magnet on each shutter element;

b. forming an electromagnet proximate to each shutter element, each such electromagnet having an electrical coil through which electrical current can flow; and

c. controlling the direction of current flow through each such electrical coil in order to repel or attract each of the shutter elements.

24. A method of forming an electrical coil upon a semiconductor substrate, the electrical coil extending generally along a longitudinal axis said method comprising the steps of:

a. depositing a first layer of metal upon the semiconductor substrate;

b. patterning the deposited first layer of metal to form a plurality of lower rungs of the electrical coil, the plurality of lower rungs extending generally perpendicular to the longitudinal axis of the electrical coil, each of the plurality of lower rungs having opposing first and second ends;

c. forming a first insulative layer of material over the substrate and above the patterned deposited first layer of metal;

d. forming a layer of magnetic material extending the longitudinal axis of the electrical coil and extending above the first insulative layer and extending across the plurality of lower rungs of the electrical coil;

e. forming a second insulative layer of material over the substrate and extending above both the first insulative layer and the layer of magnetic material;

f. etching holes through the first and second insulative layers above the opposing first and second ends of the plurality of lower rungs to expose such opposing first and second ends;

g. depositing a second metal layer upon the substrate over the second insulative layer and within the etched holes exposing the opposing first and second ends of the plurality of lower rungs; and

h. patterning the second metal layer to connect the second end of each lower rung to the first end of a next succeeding lower rung to form the electrical coil.

25. The method recited by

claim 24

including the steps of:

i. forming first and second electrical coils using the steps recited in

claim 24

;

j. depositing magnetic shielding material between the first and second electrical coils, the magnetic shielding material being spaced apart from the first and second electrical coils; and

k. forming a third insulative layer of material over the substrate and extending above both the first and second electrical coils to protect the first and second electrical coils from contacting the magnetic shielding material.