Part-inspecting system

Details Part-inspecting system Part-inspecting system

1997-10-31

2001-07-10

Gordon, Paul P. (Department: 2786)

Data processing: generic control systems or specific application

Specific application, apparatus or process

Product assembly or manufacturing

C700S109000, C700S108000, C250S306000, C250S310000, C382S172000, C382S172000

Reexamination Certificate

active

06259960

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a part-inspecting system for detecting the presence or absence of a defect (e.g., adhering foreign matter or defective pattern) on an inspected part, such as a silicon wafer, storing information used to identify the inspected part and information about defects, managing these kinds of information, and using the stored information for later operations to detect defects on parts. Especially, the invention relates to a part-inspecting system for performing accurate inspections with an electron microscope or the like.
BACKGROUND OF THE INVENTION
In principle, the “defect” referred to herein means every kind of defect, such as adhering foreign material deteriorating the quality of the inspected part and defective pattern. Where “foreign material” and a “defect” are used in the same sentence or paragraph, the former “foreign material” means a defect caused by adhesion of foreign material, while the latter “defect” means a defect due to other than adhesion of foreign material. The “defective pattern” referred to herein means a defect in a pattern formed on a part under inspection and does not embrace any defect such as adhesion of foreign material.
A part-inspecting system (technique J01) for performing detailed inspection according to information obtained by a preliminary inspection as illustrated in
FIGS. 72-76
is known as a part-inspecting system of this kind. This system performs a preliminary inspection, using a commercially available optical part-inspecting apparatus. Information about the results of the preliminary inspection, such as the positions of defects on the inspected part and their size, is stored in memory. Then, the system performs a review inspection, or detailed inspection, with a review apparatus, by reference to the information obtained by the preliminary inspection. A review SEM (scanning electron microscope), an optical review apparatus using an optical microscope, or the like is used as the aforementioned review apparatus.
It is to be noted that “review” referred to herein is to perform detailed inspection of an object under inspection, for knowing the exact position of any defect or foreign material, its shape, or distribution. The “review SEM” using an electron microscope comprises a review SEM body and an EWS (engineering workstation) interfaced to the body by a communications cable.
The controller of the review SEM and the EWS are connected by a communications cable and housed in a common housing. The EWS connected with the SEM controller might be referred to as the SEM EWS. A display device DE for the SEM EWS and a display device D for the SEM controller are both held to the housing described above.
FIG. 72
schematically illustrates a conventional part-inspecting inspecting system of the above-described kind. An optical foreign material-inspecting apparatus
01
, an optical defect-inspecting apparatus
02
, a defect image filing system (DIFS) server
03
for storing information, an EWS (engineering workstation), etc. are connected by a network N such as Ethernet.
The optical foreign material-inspecting apparatus
01
and the optical defect-inspecting apparatus
02
detect foreign materials and defects on an inspected part and produce data regarding the positions and sizes of the detected foreign materials and defects. The outputs from these two kinds of apparatuses are similar in format. Accordingly, the optical foreign material-inspecting apparatus
01
and the optical defect-inspecting apparatus
02
are collectively referred to as the preliminary inspecting equipment (
01
,
02
).
When a part to be inspected (i.e., a bare wafer on which no pattern is formed) is placed in position for inspection, the optical foreign material-inspecting apparatus
01
automatically detects the position and the size of adhering foreign material. Surfscan 6600 and Surfscan 7700 manufactured by TENCOR Corporation are available as such foreign material-inspecting apparatus. As a result of the inspection performed by the inspecting apparatus
01
, a foreign material information file holding the position and the size of any foreign material and other data is delivered.
When a part to be inspected (i.e., a wafer on which a pattern is formed) is placed in position for inspection, the optical defect-inspecting apparatus
02
automatically detects the size and position of any defect (such as adhering foreign material, defective pattern, flaw, or the like). Apparatus
21
XX manufactured by KLA Corporation is commercially available as this defect-inspecting apparatus
02
.
The preliminary inspecting equipment (
01
,
02
) consisting of the optical foreign material-inspecting apparatus
01
and the defect-inspecting apparatus
02
delivers foreign material information files and defect information files, which might be collectively referred to as preliminary inspection information files.
The preliminary inspection information files created by the optical foreign material-inspecting apparatus
01
and the defect-inspecting apparatus
02
are stored in computers ancillary to the optical foreign material-inspecting apparatus
01
and the defect-inspecting apparatus
02
, respectively, or in the DIFS server
03
.
Product serial numbers, lot numbers, wafer identification numbers or codes, data about process steps, data about the fabrication equipment, and date are stored in the preliminary inspection information files. Besides, the number of foreign materials, the number of defects, their positions on the wafer, their sizes, and other data are stored. The preliminary inspection information stored in the preliminary inspection information files can be displayed as shown in
FIGS. 73A and 73B
, for example.
FIGS. 73A and 73B
show an example of preliminary inspection information displayed.
FIG. 73A
shows the contour of a wafer under inspection, as well as the positions of foreign materials or defects on the inspected part.
FIG. 73B
is a list of numbers given to the foreign materials or defects, their positions, their sizes, and other kinds of information. The preliminary inspection information permits one to grasp the situation and tendency of occurrence of defects produced during fabrication of inspected parts. Therefore, a preliminary inspection information file such as a foreign material information file or defect information file is indispensable for a yield management system.
More specifically, a semiconductor fabrication sequence fabricates 200 to 300 semiconductor chips on a bare wafer. If the result of a preliminary inspection needs an accurate inspection, each inspected part (such as a bare wafer or wafer on which semiconductor chips are being produced) is inspected accurately. If foreign materials or defects discovered by the accurate inspection are considered to degrade the quality of the inspected part below the acceptable level, then it is necessary to find and remove the cause of the defects.
If the operator can infer from the information about the preliminary inspection that the process sequence is at fault, the review SEM is used to know, or review, the shapes of foreign materials or defects or the circumstance. The review SEM can perform a quick review by using the information contained in the preliminary inspection information, i.e., the positions and sizes of the foreign materials or defects. A review SEM using a scanning electron microscope or an optical review SEM can be employed as the above-described review SEM.
When an inspected part should be reviewed by the use of the review SEM, the sample stage (not shown) of the review SEM is set on the part. Then, the initial magnification of the review SEM is set to 3000×, for example. Information (hereinafter referred to as the “optical inspection information”) about the positions and sizes of foreign materials or defects previously obtained by the optical foreign material-inspecting apparatus
01
or the defect-inspecting apparatus
02
is read into the SEM EWS. At this time, images shown in
FIGS. 73A and 73B
are displayed on the display device DE connec

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