The present invention relates to an electron microscope for observing or detecting a surface or inside of a semiconductor wafer or a mask for exposing a semiconductor pattern for faults and/or foreign objects, particularly to an electron microscope for observing or detecting a surface or inside using coordinates of faults and/or faults which were measured by another wafer/mask inspecting apparatus.
Faults or objects on a semiconductor wafer or a mask for exposing a semiconductor pattern may give fatal problems to the semiconductor performances and reduce the efficiency of production of semiconductors.
Therefore, to increase the production efficiency of semiconductors, it is required to remove unwanted objects from wafers and masks and faults from semiconductor patterns or mask patterns on the wafers as much as possible. Therefore, it is thought to be very important to detect and observe wafers and masks for faults and/or objects (hereinafter generically described as faults) in the production of semiconductors and analyze the causes of the faults.
Recently, semiconductors have become smaller and smaller and their performance may be seriously damaged by even a fault of about 0.1 micron on a wafer. Conventionally an optical fault inspector or an optical object inspector (hereinafter generically described as an inspector) is used to locate faults on a wafer, move the field of view of the electron microscope to the location where the faults exist according to information on fault coordinates or the like obtained by said inspector, observe and identify the fault.
However, a wafer/mask area to be observed at a time at a magnification is limited although it is dependent upon the size of a display screen of the electron microscope. Therefore, if fault coordinates measured by another inspector contain errors, the fault cannot be caught in the field of view of the electron microscope.
Although various techniques have been supported to eliminate coordinate errors between the electron microscope and another inspector, such techniques cannot assure coordinate accuracies high enough to capture all faults in the field of view of the electron microscope.
To search faults, the operator gradually moves the field of view of the electron microscope using a pointing device (such as a mouse or a trackball) according to fault coordinates measured by another inspector and the location of the field of view of the electron microscope in reference to a wafer map, a die/chip diagram or an optical microscope image which is displayed separately. The conditions of observation of the electron microscope (such as a magnification) is calculated and set from data obtained by another inspector.
However, at a high magnification, for example, ×10,000 of the electron microscope, said conventional techniques do not have any means to show where the observation is made now and it is very difficult to move the field of view of the electron microscope to a position for observation.
Further, to detect target faults in the field of view of the electron microscope or to set conditions of observation for the field, the conventional technique must calculate observation conditions such as a magnification for each fault from numeric data obtained by another inspector.
Further, the conventional technique cannot use coordinate errors obtained in search of a fault easily for search of other faults, searching of the conventional technique is not efficient.
Furthermore, in case both an area which was already observed by an electron microscope and an area which has not been observed are separately displayed on-screen, it sometimes happened that the conventional technique could not change conditions of observation of the electron microscope or involuntarily initialized displays.