Three dimensional inspection system

United States Patent [w]

Beaty et al.

US005909285A [ii] Patent Number: [45] Date of Patent:

5,909,285 Jun. 1,1999

[54] THREE DIMENSIONAL INSPECTION SYSTEM

[76] Inventors: Elwin M. Beaty, 13529 Arthur St., Minnetonka, Minn. 55305; David P. Mork, 14605 34th Ave. North, No. 209, Plymouth, Minn. 55447

[21] Appl. No.: 08/955,198 [22] Filed: Oct. 21, 1997

Related U.S. Application Data

[63] Continuation-in-part of application No. 08/850,473, May 5, 1997.

[51] Int. CI.6 G01B 11/24; G06K 9/00

[52] U.S. CI 356/394; 356/237.1; 382/146;

348/126

[58] Field of Search 356/237, 394,

356/395, 396; 348/87, 126; 382/153, 291, 145, 146, 149, 150; 29/721, 759

[56] References Cited

U.S. PATENT DOCUMENTS

5,307,149 4/1994 Palm et al. .

5,355,221 10/1994 Cohen et al. .

5,420,691 5/1995 Kawaguchi 356/375

5,430,548 7/1995 Hiroi et al. .

5,452,080 9/1995 Tomiya 356/237

5.563.702 10/1996 Emery et al. .

5.563.703 10/1996 Lebeau et al 356/237

5,574,668 11/1996 Beaty .

FOREIGN PATENT DOCUMENTS

W09112489 8/1991 WIPO .
WO9207250 4/1992 WIPO .

Primary Examiner—Hoa Q. Pham

Attorney, Agent, or Firm—Han I. Sun; Emil Moffa

[57] ABSTRACT

A part inspection and calibration method for the inspection of integrated circuits includes a camera to image a precision pattern mask deposited on a transparent reticle. Small parts are placed on or above the transparent reticle to be inspected. A light source and overhead light reflective diffuser provide illumination. An overhead mirror or prism reflects a side view of the part under inspection to the camera. The scene of the part is triangulated and the dimensions of the system can thus be calibrated. A reference line is located on the transparent reticle to allow an image through the prism to the camera of the reference line between the side view and the bottom view. A precise reticle mask with dot patterns gives an additional set of information needed for calibration. By imaging more than one dot pattern the missing state values can be resolved using an iterative trigonometric solution. The system optics are designed to focus images for all perspectives without the need for an additional focusing element.

33 Claims, 14 Drawing Sheets