Secure photomask with blocking aperture

• US 7,851,110 B2
• Filed: 04/18/2008
• Issued: 12/14/2010
• Est. Priority Date: 04/20/2007
• Status: Active Grant

• Current Assignee: Phototronics Incorporated
• Original Assignee: Phototronics Incorporated
• Inventors: Progler, Christopher J.
• Primary Examiner(s): Huff; Mark F
• Assistant Examiner(s): Fraser; Stewart A
• Application Number:
  US12/105,992
• Publication Number:
  US 20080261126A1
• Time in Patent Office: 970 Days
• Field of Search: 430/5, 430/270.1, 430/311, 430/322, 324/457, 349/139, 349/4, 359/271, 359/275
• US Class Current: 430/5
• CPC Class Codes: G03F 1/38 Masks having auxiliary features, e.g. special coatings or marks for alignment or testing; Preparation thereof
• CPC Class Codes: G03F 1/40 Electrostatic discharge [ESD] related features, e.g. antistatic coatings or a conductive metal layer around the periphery of the mask substrate

Abstract

A secure photomask including a substrate having one or more pattern layers formed thereon and a blocking aperture disposed below the one or more pattern layers that prevents at least one of unauthorized use and copying of the photomask.

Claims

1. A secure photomask comprising:

a substrate comprising one or more pattern layers formed thereon;

a blocking aperture disposed below the one or more pattern layers that prevents at least one of unauthorized use and copying of the photomask, the blocking aperture being an electrochromic film; and

an electric charge delivery element that delivers electric signals to the electrochromic film to switch the electrochromic film from being substantially opaque to substantially transparent and from being substantially transparent to substantially opaque.

2. The secure photomask of claim 1, wherein the electrochromic film comprises tungsten oxide.

3. The secure photomask of claim 1, wherein the one or more pattern layers comprise at least one antireflective layer.

4. The secure photomask of claim 1, wherein the one or more layers comprise at least one opaque layer.

5. The secure photomask of claim 1, wherein the one or more layers comprise at least one partially transparent layer.

6. The secure photomask of claim 1, wherein the blocking aperture is disposed between the substrate and the pattern layers.

7. The secure photomask of claim 1, wherein the blocking aperture is disposed below the substrate.

8. A secure photomask blank comprising:

a substrate comprising one or more layers formed thereon;

a blocking aperture disposed below the one or more layers that prevents at least one of unauthorized use and copying of a photomask formed from the photomask blank, the blocking aperture being an electrochromic film; and

an electric charge delivery element that delivers electric signals to the electrochromic film to switch the electrochromic film from being substantially opaque to substantially transparent and from being substantially transparent to substantially opaque.

9. The secure photomask blank of claim 8, wherein the electrochromic film comprises tungsten oxide.

10. The secure photomask blank of claim 8, wherein the one or more layers comprise at least one antireflective layer.

11. The secure photomask blank of claim 8, wherein the one or more layers comprise at least one opaque layer.

12. The secure photomask blank of claim 8, wherein the one or more layers comprise at least one partially transparent layer.

13. The secure photomask blank of claim 8, wherein the blocking aperture is disposed between the substrate and the one or more layers.

14. The secure photomask blank of claim 8, wherein the blocking aperture is disposed below the substrate.