Method of aligning two members utilizing marks provided thereon
US4590382A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 24, 1984 |
| Grant date | May 20, 1986 |
| Priority date | — |
| Expiry date | May 24, 2004 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S505/88
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
Alignment marks are formed on the opposite surfaces of a photoelectric mask and a wafer. Each mark has a plurality of lines provided at a predetermined pitch. Widths of the lines of the photoelectric mask are progressively increased. On the while, widths of the lines of the wafer are progressively decreased. The marks of the wafer and the mask are opposite to each other such that lines of the maximum and minimum widths are opposite to each other. The overlapping area of the marks changes quadratically as a function of positional deviation between the mask and the wafer. When the mask is irradiated with ultraviolet light, X-rays are emitted from the mark on the wafer at an intensity corresponding to the overlapping area and are detected by an X-ray detector. The intensity of X-rays emitted changes quadratically as a function of deviation. The electron beam is scanned, and a detection signal is synchronously detected. The obtained PSD signal does not have a nonsensitive region and changes linearly as a function of deviation even if the beam scan width is narrow.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.