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  Method and apparatus for personalization of semiconductorUSPTO Application #: 20060161254Title: Method and apparatus for personalization of semiconductor Abstract: A system for making small modifications to the pattern in standard processed semiconductor devices. The modifications are made to create a small variable part of the pattern against a large constant part of the same pattern. In a preferred embodiment the exposure of the variable and constant parts are done with the same wavelength in the same combined stepper and code-writer. The invention devices a way of writing variable parts of the chip that is automatic, inexpensive and risk-free. A system for automatic design and production of die-unique patterns is also shown. (end of abstract) Agent: Harness, Dickey & Pierce, P.L.C - Reston, VA, US Inventor: Torbjorn Sandstrom USPTO Applicaton #: 20060161254 - Class: 623009000 (USPTO) Related Patent Categories: Prosthesis (i.e., Artificial Body Members), Parts Thereof, Or Aids And Accessories Therefor, Larynx, Trachea, Tracheobronchial Prosthesis Or Combination Thereof The Patent Description & Claims data below is from USPTO Patent Application 20060161254. Brief Patent Description - Full Patent Description - Patent Application Claims
FIELD OF THE INVENTION [0001] The present invention relates to the production of semiconductor chips and other devices by photolithography. In particular it relates to creating devices with unique codings or other unique visual, optical or electronic properties. In a different sense the invention relates to the device itself and the design process of the device. Yet other aspects of the invention are the creation of tamper-proof implements that carry an electronic signature or cryptographic key. The invention also relates to reliability tracking of electronic devices and systems. Finally, an important aspect of the invention is related to reconfiguring devices containing several design versions or redundance functional units, such as for parametric experiments on an analog chip. BACKGROUND OF THE INVENTION [0002] Modern production of semiconductor chips and also of surface acoustic devices, thin-film magnetic heads and similar devices is done by steppers. Modern steppers use four times reduction, excimer lasers as illumination source and use a step-and-scan principle where the wafer and reticle are scanned during exposure. In this context any type of stepper will be referred to as a stepper or as a scanning stepper where the distinction is important. [0003] The important property of a stepper is that it produces identical copies of the same die by exposing the same mask at each exposure site. By doing so in an efficient way it provides high through-put and production economy. There are situation and cases where the chips should not be identical, such as for parameter try-out in research and development (R&D). The manufacturer is then forced to complicated procedures, like writing part of the pattern in an e-beam pattern generator or performing focussed ion-beam modification of the devices. [0004] In other cases there is a need to provide a unique signature or code or programming to each chip. A common way to include such codes is by using electronically programmable circuits, often by changing reversibly or irreversibly the potential of a floating gate electrode, or by programmable fused links or so called anti-fuse links. In either case there are extra process steps, extra manufacturing cost and/or extra driving involved. SUMMARY OF THE INVENTION [0005] It is therefore an object of the present invention to provide a method and an apparatus to alleviate said shortcomings in the prior art. [0006] This object is achieved with the invention according to the appended claims. [0007] The invention devices a method to do such unique programming in a standard process with very little extra cost incurred. The invention allows virtually every ship to have a visually or electronically readable unique code. The code can be used as a serial number for a processor, for self configuration in networked devices or for tracking of faults and errors back to the lot, wafer and chip during manufacturing, thereby providing data for quality improvement. [0008] Another aspect of the invention is that it provides a design block that can be included in any standard design to provide a visually or electronically readable code or a chip-unique programming. The block can provide a combination of a layout block and a computer program or compilation of data that together provides the desired programming at the time of exposure. The invention devices a method by which the code generation can be specified at design time and executed in an automated fashion. [0009] The words coding, programming and personalization are used interchangeably throughout the application to denote the creation of a function that is different between different dies or chips. The apparatus or attachment that writes the code or programming is called a code-writer. BRIEF DESCRIPTION OF THE DRAWINGS [0010] For exemplifying purposes, the invention will be described in closer detail in the following with reference to embodiments thereof illustrated in the attached drawings. [0011] FIG. 1 shows preferred embodiments of the code writer in the form of a step-and-scan-system and a code-writing attachment using a laser scanner (1a) and an Spatial Light Modulator (SLM) (1b). [0012] FIG. 2 shows a magnified view of the wafer in FIG. 1. [0013] FIG. 3 shows how two code-writing modules can be used to program sixteen identical dies in a single stepper field. [0014] FIG. 4 shows the design information flow. [0015] FIG. 5 shows possible placements of the code-writer's window in a scanning stepper (5a) and a stepping stepper (5b). 5c shows a possible placement with a beam-combiner in the system. [0016] FIG. 6 shows a simple design block for serial output of a programmed code. DETAILED DESCRIPTION OF THE INVENTION [0017] The invention provides elements of creating unique electronic devices, in particular semiconductor chips. The uniqueness can consist of an ID code, a visual marking, an embedded cryptographic key, or any other unique characteristic of the chip. Other uses could be for creating a uniquely coded surface acoustic filter or optical security devices, similar to the holographic area on a credit card. An important application is for R&D work where several versions of a block can be tested, e.g. four designs of an analog amplifier, either by including several designs in the same chip and connecting them only one of them in each chip, or alternatively have the code-writer to write the components differently, e.g. transistors with different width in different chips. Many other uses are possible, some of them new or unforeseen since the invention makes the cost of adding personalizes features to a standard chip very low. An example of a such new use would be a lottery with electronic lots or tokens. [0018] The principle of the invention is that an area of the chip is set aside for programming in the normal reticle set. This area is programmed by a special code-writing system. Another way to express this it to call it a constant and a variable part of the pattern where the constant part comes from the reticle and the variable part from the code-writer. Note that the constant part of the chip extends through all layers while the variable part is normally confined to a single layer. [0019] The coding exposure is made in the same photoresist layer, preferably using the same wavelength, or the exposure wavelengths are close together such as with exposure wavelength 248 nm and coding at 266, exposure at i-line and coding at 364 nm, etc. Preferably the exposure and coding are done with exactly the same wavelength, something that can often be accomplished in the SLM embodiment which can use both discharge lamps and excimer lasers as light sources. Therefore the process will not see the difference between the variable and constant part, and most of the process complexity associated with direct-writing e-beam schemes are absent. None of the hurdles normally associated with direct-writing are present: long writing times are absent since the constant part of the layer is exposed from a normal mask, extensive process development is absent since the process is identical to the standard process, The critical alignment step is absent, but it is already done by the stepper if the code-writer is integrated in the stepper. Bringing the wafer out from the standard process flow, writing in an electron beam system, and reinserting it does not happen either, if the code-writer is integrated into the stepper. Therefore the personalization by the invention is easy, inexpensive and risk-free. Continue reading... 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