Integrated defect yield management and query system

Details Integrated defect yield management and query system Integrated defect yield management and query system

1997-12-04

2001-11-06

Wachsman, Hal (Department: 2857)

Data processing: measuring, calibrating, or testing

Measurement system in a specific environment

Quality evaluation

C702S084000, C702S035000, C700S110000, C700S121000

Reexamination Certificate

active

06314379

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to an integrated defect yield management and query system. More specifically, the defect/yield management system can collect the results of the defect and yield analyses for semiconductor wafers and dies that are generated by scribing the wafers during or after the semiconductor wafer fabrication process, and store these results in a query database. Thereafter, analyzers can analyze various defect events according to these stored test results, to learn the defect characteristics of various process devices. In addition, the system can also integrate with in-situ particle monitor to reflect the real-time process situation.
2. Description of Related Art
In the semiconductor wafer fabrication process, defects may occur in the fabricated wafers due to operational, mechanical or chemical control errors, or the environmental uncertainty. Defects on the wafers may affect the normal operation of integrated circuits, thereby reducing the fabrication yield. Especially, since the fabrication process of the integrated circuits is increasingly complicated and the dimensions of the integrated circuits are continuously shrinking, a particle having a diameter of only 0.3 &mgr;m may cause a severe decrease in the production yield. Therefore, it is very difficult for analyzers to determine which process steps or devices may cause defects, to analyze the defect characteristics of the process devices in the production line, and to locate the defect positions on a wafer or a die.
FIG. 1
(Prior Art) schematically illustrates a defect analysis flowchart in a conventional semiconductor wafer fabrication process. As shown in
FIG. 1
, the defect analysis process may be roughly divided into two portions: an in-line process defect control portion (shown in the left part of
FIG. 1
) and an off-line defect analysis portion (shown in the right part of FIG.
1
). In the in-line process defect control portion, semiconductor wafers are tested after particular process steps, such as a diffusion/thin film process
11
, a photolithography process
12
or an etching process
13
. During these processing steps, the semiconductor wafers may become defective in their bulk or on their surface due to uncertain process environments. Therefore, after these process steps, an inspection step after developer/etching/deposition (AD/EI)
20
is performed to examine the processed wafers by thoroughly inspecting a part of these semiconductor wafers or by scanning. Depending upon the particular defect condition noted during the inspection step
20
, process parameters in the production line may be changed to reduce the likelihood of further defects occurring. Then, based on the inspection results, an image-capturing inspection
30
of the semiconductor wafers is performed to obtain an image showing the sharpness and the composition of defects by optical microscopes, Scanning Electron Microscope (SEM) and element dispersion spectrum. These test results acquired by the in-line inspection steps are immediately sent to a defect management system
10
, which can classify and preserve these test results for subsequent analyses.
Once the entire semiconductor manufacturing process is complete, processed semiconductor wafers are analyzed off-line for defects. These off-line defect analyses include a wafer acceptance test/specification (WAT/SPC)
40
, a quality control (QC) examination
50
, a Circuit Probing/Final Test (CP/FT) yield test
60
and a reliability step
70
. The WAT/SPC step
40
is used to examine the electrical characteristics of the wafers under test by suitable devices. The QC examination
50
is used to visually examine the appearance of the wafers undergoing testing, to decide whether the extant number of defects meets the customer requirements. Then, the CP/FT yield test
60
is used to estimate the process yield. At this time, the wafers are scribed into a plurality of dies and the final test is finished based on dies. Finally, the reliability test
70
is performed under various test conditions. Conventionally, although the QC examination
50
, the CP/FT yield test
60
and the reliability test
70
all are used to analyze visible and invisible defects of the semiconductor wafers, the results acquired through these tests are sent to different departments of the production line to be analyzed. For example, the results acquired by the QC examination
50
and the reliability test
70
are passed to the quality control (QC) department, and the results of the reliability test
60
are sent to the product department. Thus, in a conventional defect analysis system, various defect-related data were distributed to different individual departments. Therefore, it is very difficult to deal with a specific defect event as a whole. In addition, historical defect records are also difficult to maintain.
Furthermore, the conventional process defect management system can not combine the in-situ monitoring equipment, such as particle monitors for controlling the particle number in the fabrication environment, with other in-line or off-line testing devices. In other words, the above-indicated in-situ control data can not be integrated with the in-line test data and the off-line test data. Therefore, it is difficult to provide a complete set of defect-related information for further and real-time analyses. In addition, personnel on the production line can not identify the defect causes in time, and, therefore, an improvement of the production yield is not apparent.
Furthermore, the defect-related information is distributed over the whole production line, and can not be acquired by a simpler interface for the analyzers and the personnel on the production line. This reduces the efficiency of the defect analyses.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide an integrated process defect/yield management and query system, which can harmonize and merge test data acquired by in-line process defect control analyses (such as After developing Inspect (ADI), After Etching Inspect (AEI) and defect inspection), off-line defect/yield analyses (such as visual inspection, yield test and reliability analysis) and in-situ particle monitoring, to create and preserve a complete set of defect-related data and historical defect event records.
Another object of the present invention is to provide an integrated defect/yield management and query system, which can provide an inquiry interface by which to search for a complete set of defect-related data, thereby improving the efficiency of data analysis, and reduce the data-polling time.
The present invention achieves the above-indicated objectives by providing an integrated defect yield management and query system for total quality control of the semiconductor wafer fabrication process. A local area network is used to connect all the devices for testing and inspecting the defect condition of the fabricated semiconductor wafers, a defect yield management server and a client device. These test devices are used to analyze process defects and process yields of semiconductor wafers during the fabrication process and after the fabrication process. After inspection, these devices may provide a plurality of process records corresponding to each of the semiconductor wafers, respectively. The defect yield management server retrieves the process records according to a communication protocol of the local area network, such as the popular Transmission Control Protocol/Internet Protocol (TCP/IP). These process records are stored in a database divided into a plurality of data fields, wherein each field represents a specific defect property of the semiconductor wafers. Therefore, the acquired data can be organized and easily accessed. Through a simple and convenient inquiry interface, the client device can effectively demand the process records stored in the database of the defect yield management server.
Various other objects, advantages and features of the present invention will become read

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