Etching a substrate: processes – Forming or treating optical article
Reexamination Certificate
2001-02-09
2003-03-04
Mills, Gregory (Department: 1763)
Etching a substrate: processes
Forming or treating optical article
C438S463000, C438S690000, C219S121690
Reexamination Certificate
active
06527965
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention generally relates to techniques for fabricating an object. More particularly, the present invention provides a method for fabricating a switch fabric using a high intensity light source. Merely by way of example, the present invention is implemented using such high intensity light source for separating arrays of mirrors on dice from a substrate structure, but it would be recognized that the invention has a much broader range of applicability. The arrays of mirrors can be used in a switching device for long haul communications. The invention can be applied to other types of networks including local area networks, enterprise networks, small switch designs (e.g., two by two) and the like.
As the need for faster communication networks becomes more desirable, digital telephone has progressed. Conventionally, standard analog voice telephone signals have been converted into digital signals. These signals can be 24,000 bits/second and greater in some applications. Other telephone circuits interleave these bit streams from 24 digitized phone lines into a single sequence of 1.5 Mbit/second, commonly called the T1 or DS1 rate. The T1 rate feeds into higher rates such as T2 and T3. A T4 may also be used. Single mode fiber optics have also been used at much higher speeds of data transfer. Here, optical switching networks have also been improved. An example of such optical switching standard is called the Synchronous Optical Network (SONET), which is a packet switching standard designed for telecommunications to use transmission capacity more efficiently than the conventional digital telephone hierarchy, which was noted above. SONET organizes data into 810-byte “frames” that include data on signal routing and designation as well as the signal itself. The frames can be switched individually without breaking the signal up into its components, but still require conventional switching devices.
Most of the conventional switching devices require the need to convert optical signals from a first source into electric signals for switching such optical signals over a communication network. Once the electric signals have been switched, they are converted back into optical signals for transmission over the network. As merely an example, a product called the SN 16000 is BroadLeaf™ Network Operating System (NOS) made by Sycamore Networks, Inc. uses such electrical switching technique. Numerous limitations exist with such conventional electrical switching technique. For example, such electrical switching often requires a lot of complex electronic devices, which make the device difficult to scale. Additionally, such electronic devices become prone to failure, thereby influencing a reliability of the network. The switch is also slow and is only as fast as the electrical devices. Accordingly, techniques for switching optical signals using a purely optical technology have been proposed. Such technology can use a wave guide approach for switching optical signals. Unfortunately, such technology has been difficult to scale for switching a high number of signals from a bundle of optical fibers, which may be desirable today. Other companies have also been attempting to develop technologies for switching such high number of signals, but have been unsuccessful. Such switches are also difficult to manufacture effectively and reliably. Other examples of optical switching networks include access, metropolitan and Dense Wavelength Division Multiplexing (DWDM) networks.
As merely an example, some companies have been attempting to use mirrors to switch an optical beam from one fiber to another. The use of mirrors in telecommunication signals has some advantages such as low signal loss and the like. Such mirrors, however, are often difficult to manufacture in a high density mirror array. In particular, such mirrors are often fragile and prone to damage during fabrication. U.S. Pat. No. 5,969,465, assigned to XROS, Inc. describes such a mirror, which is often difficult to make to form high density array structures. Accordingly, there needs to be improved ways of manufacturing such mirrors before large density arrays of such mirrors can be made effectively and cost efficiently.
From the above, it is seen that an improved way for fabricating a mirror array for switching a plurality of optical signal is highly desirable.
SUMMARY OF THE INVENTION
According to the present invention, a technique including a method and apparatus for fabricating an object such as a switch fabric is provided. More particularly, the present invention provides a method for fabricating a switch fabric using a high intensity light source. Merely by way of example, the present invention is implemented using such high intensity light source for separating arrays of mirrors on dice from a substrate structure, but it would be recognized that the invention has a much broader range of applicability. The arrays of mirrors can be used in a switching device for long haul communications. The invention can be applied to other types of networks including local area networks, enterprise networks, small switch designs (e.g., two by two) and the like.
In a specific embodiment, the present invention provides a method for fabricating an array of mirrors disposed on a die from a substrate. The method includes placing a substrate comprising a plurality of die thereon on a stage. Each of the die comprises a plurality of movable mirror devices (or to be movable mirror devices) in an array configuration. Each die comprises a peripheral region defining a street that surrounds the array configuration. The method forms a plurality of tabs that join one die to another die in the street of the substrate. Each of the tabs also is separated from each other in a sequential manner by a recessed region between at least two of the tabs. The street defined by the tabs and the recessed region defined there between in a sequential manner. The method then directs a beam of high intensity electromagnetic radiation at the street between the one die and the other die to ablate each of the tabs that joins the one die to the other die to separate the one die from the other die to free the die comprising the mirror array from the other dice on the substrate.
Many benefits are achieved by way of the present invention over conventional techniques. For example, the present technique provides an easy to use process that relies upon conventional technology. The technique also can be reduce time for manufacture of the array of mirror from a die, which is one of many die on a substrate. Furthermore, the technique creates almost no damage to movable mirror devices, which are prone to mechanical, electrical, chemical, and thermal damage. Depending upon the embodiment, one or more of these benefits may be achieved. These and other benefits will be described in more throughout the present specification and more particularly below.
Various additional objects, features and advantages of the present invention can be more filly appreciated with reference to the detailed description and accompanying drawings that follow.
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60/023311, Jul. 31, 1996, U.S. Provisional Application.
Gee Dale A.
Sathe Abhijeet D.
Yang Xiao
Culbert Roberts P
Mills Gregory
Nayna Networks, Inc.
Townsend and Townsend / and Crew LLP
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