Showing papers on "Mask inspection published in 1989"

Semiconductor device inspection template

Abstract: A semiconductor device inspection template for use in visual inspection of semiconductor die or packages includes a selectively patterned transparent film mounted in a sleeve adapted for rapid placement and removal from an optical inspection instrument's optical tube

Automated Visual Inspection Of Integrated Circuits

Abstract: One of the major application fields of image processing techniques is the 'visual inspection'. For a number of rea-sons, the automated visual inspection of Integrated Circuits (IC's) has drawn a lot of attention. : Their very strict design makes them very suitable for an automated inspection. : There is already a lot of experience in the comparable Printed Circuit Board (PCB) and mask inspection. : The mechanical handling of wafers and dice is already an established technology. : Military and medical IC's should be a 100 % failproof. : IC inspection gives a high and allinost immediate payback. In this paper we wil try to give an outline of the problems involved in IC inspection, and the algorithms and methods used to overcome these problems. We will not go into de-tail, but we will try to give a general understanding. Our attention will go to the following topics. : An overview of the inspection process, with an emphasis on the second visual inspection. : The problems encountered in IC inspection, as opposed to the comparable PCB and mask inspection. : The image acquisition devices that can be used to obtain 'inspectable' images. : A general overview of the algorithms that can be used. : A short description of the algorithms developed at the ESAT-MI2 division of the katholieke Universiteit Leuven.

The P300: An Approach to Automated Inspection of Patterned Wafers

Abstract: As IC groundrules shrink, manual optical inspection of multilevel patterned wafers becomes ineffective if not impossible, and efforts to develop automatic wafer inspection systems have expanded. This paper describes one successful approach, the P300 Automatic Wafer Inspection System[1], which uses a greylevel reference comparison of adjacent cells to locate defects on periodic pattern. The defects may be either pattern anomalies or particulates. Experiments demonstrate that the P300, scanning at a rate significantly faster than a human inspector, finds over ninety percent of half micron defects and over ninety-five percent of defects one micron or larger. By basing the inspection algorithm on a cell-to-cell comparison within a frame, as opposed to the conventional chip to chip or chip to CAD database reference, the system avoids detecting false alarms caused by acceptable variations in reflectivity, film thickness, critical dimensions and overlay registration over the surface of the wafer. A simple cell-to-cell comparison, however, would he prone to detecting false alarms due to electronic and digitization noise, aliasing, vibration, and illumination non-uniformity, as well as small scale acceptable process variation. By adding a statistical test to filter out noise and an edge detector to reduce sensitivity on edges, the false positive rate has been kept below a fraction of a percent of the frames inspected. The paper will discribe the system architecture and inspection algorithms and discuss specific inspection applications.

PC based image analyser for mask inspection

Abstract: An image analysis system for mask inspection is presented. A pattern recognition technique is described for registration and checking of masks. This approach has the advantage that the distortions in the image do not affect the accuracy of the pattern matching algorithm. The hardware, consisting of an image acquisition and display system, is discussed. The software used for the removal of noise, extraction of edges, and the corrections for image distortions is also discussed. The algorithm used for the inspection is defined. The results of the algorithm are presented, along with its capability to detect faults. The turnaround time and the future scope of the work are discussed. >

Apparatus and method of mask inspection

Abstract: PURPOSE: To achieve inspection with slight modification of an existing apparatus by scanning a particle beam mask with an inspection beam and forming a scanned beam passage in an electron microscope where the scanning is performed. CONSTITUTION: Through-holes 1, 3 are provided in a beam path of an electron or ion beam projection apparatus that is accurately focused, and preferably a coordinate table for a mask 2 to be inspected is formed, and/or a rotatable container table 4 is disposed at need. Below the table through-hole passages 3 disposed are a secondary quantum or secondary beam 6 emitter surface 5 produced from an inspection beam passing through an X ray transmission region or an opening 1 lay on the container table 4 and a detector 7 for the secondary quantum produced from the emitter surface 5 and for the secondary beam 6 produced from the emitter surface 5. A signal of the detector 7 after modulation may be supplied to an image memory at need.

Automatic Mask Inspection System Using X-ray As A Source

Abstract: A fundamental concept to realize the automatic X-ray mask inspection system using X-ray as a source is shown, and main elemental technologies of the X-ray mask inspection system having been developed in conjunction with the concept is described in this report. Die-to-die comparison rather than absolute inspection in relation to the design data is the purpose of our X-ray mask inspection. An array of X-ray aperture of picture elements both X and Y sides being equal to the design rule of the pattern is used to select the picture elements to be processed parallel in which numbers of identical plural pixels are in X-ray mask if there is no defects. If the transmitted X-ray flux through one of the picture element among selected plural pixels shows material difference in intensity from others, it is then considered as defect. After the first set of picture elements in the die-to-die comparison is completed, the X-ray aperture array is moved by distance being equal to the design rule of the X-ray mask. Similarly other plural pixels of the X-ray mask are inspected in same manner as above. Repetition of this process to scan an area encompassed by a single X-ray aperture pitch make it possible to inspect all the area of the X-ray mask efficiently. Therefore, by using the X-ray aperture array composed of 250x250 array of 0.5μ mx0.5μ m square transparent aperture with two dimensional pitch of 100μ mx100μ m and TV camera having 250x250 array of light sensitive elements, all the area of the X-ray mask with two dimensional length of 25mmx25mm can be inspected only in 44 minutes.