Radiant energy – Irradiation of objects or material – Ion or electron beam irradiation
Reexamination Certificate
1998-07-30
2001-07-17
Nguyen, Kiet T. (Department: 2881)
Radiant energy
Irradiation of objects or material
Ion or electron beam irradiation
C250S492200
Reexamination Certificate
active
06262430
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to multi-layer integrated circuits (ICs), and more particularly to navigation from a frontside of multi-layer ICs.
BACKGROUND OF THE INVENTION
As the size of transistors forming integrated circuits decreases, the number of transistors in a given circuit area increases. The ability to locate one particular transistor in a circuit to perform repairs, for example, becomes significantly more difficult with the number and submicron size of the transistors. A typical approach for locating a particular circuit feature, i.e., transistor, in a silicon device utilizes a scanning electron microscope (SEM) system. While the SEM provides a high resolution topography of a top surface of a silicon device, internal metal interconnect and structure images are not provided by the SEM. Additionally, the common use of a polyimide layer as a protective top layer of silicon devices further inhibits the ability of the SEM to provide useful information for inspecting a device.
In conjunction with the SEM, a CAD (computer aided design) navigation tool typically aids in locating a particular feature of a silicon device. By registering three visible features, such as corner markings used as align marks, on SEM images of the silicon device with equivalent features of a device layout representation in the CAD tool, a position in the silicon device can be located by selecting a corresponding location coordinate in the CAD tool. Usually, this is accomplished by interfacing the computer system running the CAD tool with a stage holding the silicon device and driving the stage to the selected coordinate. Unfortunately, as a mechanical device, limitations exist in the accuracy of stage movement, e.g., to an accuracy of about 3 micron (&mgr;m). Of course, with feature sizes of the silicon device on the order of 0.25 &mgr;m, a difference of 3 &mgr;m will result in missing the desired feature completely.
A further limitation to using a CAD tool is the lack of availability of a layout for every possible circuit design. While an optical image can be taken for a given design to form an image of the structure and features of the design, the image must then be scanned into a computer system and registered with the corresponding SEM image of the silicon device. Such activities are considered too time-consuming and laborious to be a preferred practice.
Accordingly, a need exists for a navigation system that assists in more accurately locating particular features of multi-layer IC devices. The present invention addresses such a need.
SUMMARY OF THE INVENTION
The present invention provides aspects for an integrated system for frontside navigation and access of a multi-layer integrated circuit device. In an exemplary embodiment, an integrated system includes a focused ion beam (FIB) device, the focused ion beam device capable of accessing a desired layer in the multi-layer integrated circuit device. The system further includes an optical imaging device coupled substantially adjacent to the focused ion beam device, the optical imaging device assisting in navigating the multi-layer integrated circuit device from a frontside to a desired location for accessing of the desired layer by the focused ion beam device.
Through the present invention, more convenient identification of a relative position on a silicon device readily occurs by integrating an imaging device with an access and repair device. The imaging device allows better navigation from a frontside, since an operator can see where they are relative to a desired location in the circuit. These and other advantages of the aspects of the present invention will be more fully understood in conjunction with the following detailed description and accompanying drawings.
REFERENCES:
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patent: 5113072 (1992-05-01), Yamaguchi et al.
patent: 5576542 (1996-11-01), Kaga
patent: 5616921 (1997-04-01), Talbot et al.
patent: 5821549 (1998-10-01), Talbot et al.
patent: 6031985 (2000-02-01), Yoshida
Advanced Micro Devices , Inc.
Nguyen Kiet T.
Sawyer Law Group LLP
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