BACKGROUND
The present exemplary embodiments relate to in-process intralayer defect detection and correction and interlayer shunt defect detection and correction. It finds particular application to Printed Organic Electronics (POE) arrays, but can be applied to a wide variety of electronic arrays including, for example, liquid crystal displays (LCD), memory arrays (RAM, ROM, etc.), printed circuit boards (PCB), active matrix displays, and passive matrix displays.
With respect to conventional array fabrication processes, forming patterns using traditional photolithographic mask printing methods is highly productive in producing parts that have the exact same pattern over and over again. With this approach, substrate die yield is highly dependent on the absence of process artifacts (i.e. particles etc). If these artifacts cause a line open in the electrical circuitry, repair by localized line reconnection is expensive, tedious, time consuming and may not be practical. Defective dies are usually marked and rejected after die dicing. When die size becomes very large, as in for example, a POE array or a flat panel display (FPD), rejecting such a large die (large real estate) can be very costly. Moreover, bad or poor NSN+ amorphous silicon chemical vapor deposition (CVD) sometimes makes the substrates un-testable as the matrix arrays become non-functional. In particular, process defects due to layer to layer electrical shunts can sometimes disable an entire read out chip making defect isolation and defect locating impossible. The chip, even if working, may produce unreliable results for detection purposes.
Traditionally, electrical evaluation of array matrices has been performed as a final step (as opposed to an in-process step) in the array matrix fabrication process and has been accomplished by contact or non-contact probing of I/O (input and output) pads that have been patterned and defined. A typical array matrix's large physical size can present quite a challenge for such a high I/O test pad connection count to the outside world. For example, most POE arrays have a very large number of DATA and GATE interconnect lines that require testing. In order to manage electrical testing on such a large physical substrate form factor, contact type probe card based testers such as those from Tokyo Cathode Laboratory and flying probe testers such as those from Acculogic have been used. However, these probe testers (or probers) are capital intensive and do not usually fully test the multilevel device matrix. Static multiple probe approaches (“bed of nail” type) have also been used. The apparatus described in U.S. Pat. No. 6,834,243 (“Apparatus and method for electrical testing of electrical circuits”) is an example that is suitable for high probe count electrical testing. However these “bed of nail” methods require custom fixturing for each device design and are hence very costly.
An example of a LCD panel final test is illustrated by the LCD evaluation method described in U.S. Pat. No. 5,081,687 and RE37,847. This evaluation method uses a video image capture method to detect FPD matrix electrical opens and shorts by comparing the newly acquired display pattern to a previously captured golden standard sample display image pattern result. For these types of measurement, the FPD is energized through contact type edge shorting bars. This approach is also capital intensive and requires the full process fabrication of the device matrix to the pixel level formation so that the LCD panel can be tested. Another approach for testing POE arrays uses an x-ray imaging system after the formation of the active matrix thin film transistors (TFTs). The x-ray images produced by the imaging system show horizontal and vertical defect lines. However, it is very difficult to quantify the exact cause of such line defects. For example, FIG. 1 shows an image test result 100 from an x-ray detector. As shown, locating the defect via this process can be difficult and time consuming.
Later developed processes utilize peripheral shorting bars and/or short circuit rings. For example, U.S. Pat. No. 7,330,583 (“Integrated visual imaging and electronic sensing inspection systems”) utilizes shorting bars to expand the video image capture method to various electronic sensing means such as voltage, e-beam and charge sensing. These shorting bars and/or short circuit rings can be classified into full ring structures or grouped into segmented shorting bar structures. The full ring structures are typically used for static electricity mitigation to protect the array matrix device pixels. An example of this is found in U.S. Pat. No. 5,650,834 (“Active-matrix device having silicide thin film resistor disposed between an input terminal and a short-circuit ring”), where silicided resistors positioned between the edge short circuit ring and the interior array matrix provide static electricity protection for the pixel thin film transistors (TFT).
Another example of an LCD panel final test evaluation is illustrated by Orbotech Ltd.'s evaluation method illustrated in U.S. Pat. No. 5,771,068 (“Apparatus and method for display panel inspection”). This final test evaluation used a full field image sensor to capture and analyze a FPD matrix that was stimulated with various pixel patterns.
Non-contact probing methods have also been used. U.S. Pat. No. 6,630,832 (“Method and apparatus for the electrical testing of printed circuit boards employing intermediate layer grounding”) used stimulating and sensing heads and various AC frequencies to probe printed circuit boards (PCBs).
The prior art methods mentioned above apply predominantly to the final stage of testing matrix arrays. Since matrix arrays become a high value added item when fabrication approaches the formation of array pixels, device rejection at this final test stage due to line open, line bridge (i.e. short), and shunt defects becomes very costly. It is thus desirable to have an in-process (or in-fabrication) approach to electrical testing for matrix arrays that is thorough and effective for open, short and shunt defect detection. The exemplary methods and systems utilize a hybrid static peripheral I/O connection method in conjunction with a dynamic probing scheme, an arrangement of sacrificial edge shorting bars (with or without cut lines), and an analytical method to determine defect type and defect locations. For these methods and systems, a previously measured golden standard reference sample result is not required.
BRIEF DESCRIPTION
The presently described embodiments relate to an in-process method of detecting DATA and GATE line defects and an in-process method of detecting shunts between the DATA and GATE layers.
In one aspect, a method and system for in-process yield evaluation and correction in an array type of device are provided. The method and system include measuring an electrical property between individual GATE lines, DATA lines, a DATA bus I/O pad, and a GATE bus I/O pad; and analyzing the measured electrical resistance or capacitance to identify at least one of the following: GATE line open defects, GATE line bridge defects, DATA line open defects, DATA line bridge defects, and interlayer shunt defects.
In another aspect, a method and system for in-process correction of defects in an array type of substrate are provided. The method and system include receiving identified defect types, locations, and process state and dynamically reconfiguring a die or chip design to account for defects on the substrate based at least partially on the received defect types, locations and process state.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an image of a test result from a post-fabrication x-ray detector;
FIG. 2 is a high-level overview of one aspect of the an exemplary system for in-process defect detection and correct for array matrices;
FIG. 3 illustrates how electrical open DATA line data collection measurements are performed for an array matrix;
FIG. 4 illustrates how electrical open GATE line data collection measurements are performed for an array matrix;
FIG. 5 illustrates how DATA and GATE line bridges are identified via resistance measurements;
FIG. 6 illustrates how DATA line to GATE pad resistance measurements assist in identifying interlayer shunt defects;
FIGS. 7
a and 7b illustrate a data plot of the measured resistance for an array matrix both before and after a shunt repair is performed;
FIGS. 8
a and 8b illustrate a data plot of the measured resistance for an array matrix both before and after a shunt repair is performed using a differential data analysis technique;
FIG. 9 shows a simulation of the measured electrical resistance on an array matrix containing shunt defects;
FIG. 10 shows a simulation of the differential resistance measured on an array matrix containing single shunt defects;
FIG. 11 illustrates an array matrix with multiple shunt defects;
FIG. 12 illustrates a data plot showing multiple shunt defects on the same array matrix;
FIG. 13 shows the data plot of FIG. 12 rescaled for better visualization of the multiple shunt defect data;
FIG. 14 shows a simulation of the differential resistance measured on an array matrix containing multiple simultaneous shunt defects;
FIG. 15 illustrates a printed organic electronics array with identified open line defects;
FIG. 16 illustrates the corrected open line defects of FIG. 15 using a VIA layer and a mushroom metal layer;
FIG. 17 illustrates an alternative solution for the correction of open line defects of FIG. 15 using localized line bridging;
FIG. 18
a illustrates a close-up view of an interlayer shunt defect;
FIG. 18
b illustrates the correction of the interlayer shunt defect of FIG. 18a using a laser ablation method; and
FIG. 19 illustrates data measurement points for GATE and DATA layers in an example TFT fabrication in-process flow.
DETAILED DESCRIPTION
Aspects of the present exemplary embodiments relate to a system and method for in-process detection and/or correction of intralayer opens and bridges, and interlayer shunts between metal layers, in an array type of device (such as passive matrix or active matrix) during the manufacturing process. The utilization of electrical measurements and data analysis result in identifying potential defect locations and enabling in-process yield assessment and repairs. The exemplary embodiment, in one form, operates on Printed Organic Electronics (POE) arrays. However, the proposed systems and methods can operate on any electronic array including, for example, printed circuit boards, liquid crystal displays, active matrix displays, passive matrix displays, and memory arrays. Also, the exemplary embodiment, in one form, operates on array design architectures constructed with peripheral bus structures which are particularly suited for in-process detection.
FIG. 2 illustrates an example system under one aspect of an exemplary embodiment. The system 200, for implementation with a POE matrix array 202, includes a system controller 204, an electrical measurement device 212, a mushroom metal/VIA layer definition module 206, a laser ablation tool 207, and a printing system—for printing a digital design on the POE matrix array 202—such as a digital lithography printer 208. In operation, the system controller 204 measures one or more electrical properties 210 (such as resistance or capacitance) of the POE matrix array 202 via electrical probes 212. For example, an electrical property may be measured between the individual GATE/DATA lines and the GATE/DATA pads on the POE matrix array 202. The system controller 204 then analyzes the electrical property data 210 to identify and detect defects 214 and data associated with the defects (such as type, location, and process state) which are then sent to the layer definition module 206 and laser ablation tool 207 for correction. The types of defects that may be detected on the POE matrix array 202 include, for example, GATE line bridge and open defects, DATA line bridge and open defects, and interlayer shunt defects. The laser ablation tool 207 corrects identified shunt defects 214 through a laser ablation process on the POE matrix array 202. Concurrently or sequentially with respect to operation of the laser ablation tool 207, the layer definition module 206 defines a modified mushroom metal and/or via layer 216 for the purpose of correcting the identified defects 214. In essence, the layer definition module 206 is capable of dynamically reconfiguring a die or chip design to account for the received defect data 214. The reconfigured design 216 is downloaded by the digital lithography printer 208 for printing of a subsequent mask layer on the POE matrix array 202.
In one exemplary embodiment, the POE matrix array is mounted onto a stage carrier in preparation for electrical measurements. Electrical measurements of the matrix lines are performed by connecting a probe to the matrix array. For convenience, a standard commercial IC probe station with a probe card may be used to probe the matrix lines. The probe station contains a switching matrix which switches the tension of the testing instrument to each one of the lines, one at a time. This type of probe equipment does not require the purchase of an expensive dedicated system. The parts are available off the shelf.
Additionally, the exemplary embodiments described here measure electrical resistance across the matrix array. However, the exemplary embodiments may measure capacitance or any other electrical property instead of resistance to achieve the desired goals.
Identifying Intra-Layer Line Opens
FIG. 3 illustrates an array matrix 300 having an undesired open circuit 320 therein. As shown, the DATA lines (Dlines) run vertically on the matrix 300 and the GATE lines (Glines) run horizontally. The I/O pad 302 at the lower left corner is the DATA I/O pad for a fixed electrical connection from the common data bus 304 to an external electrical return. Similarly, the I/O pad 306 at the lower right corner is the GATE I/O pad. Electrical resistance is measured from the individual DATA lines 308a-308n at the top of the matrix 300 to the DATA I/O pad 302. The measured electrical resistance data is then analyzed with respect to DATA line numbers to identify and locate DATA line open defects.
For the DATA line (Dline) open measurements, the Dline to DATA pad (Dpad) resistance is sampled across the matrix 300 from the Dpad 302 to the individual Dlines 308a-308n, using a probe 309, 310 or other measurement device connected to the system controller 204. Each combination of Dline to Dpad may be measured. For instance, the first measurement might be from Dpad 302 to Dline 308a, the second measurement from Dpad 302 to Dline 308b, and so on.
In FIG. 3, the electrical current between certain Dlines and the Dpad is shown by arrows 312 and 314. The resistance measurements are then plotted with respect to the Dline number and the resistance to create a plotted graph 318. In this manner, the Dline 308a-308n to Dpad 302 measurements assist in identifying Dline electrical opens 320. For a Dline open defect, the collected and plotted data will tend to look like the example graph 318 in FIG. 3 where the high resistance spike locates the open Dline. The vertical line(s) in this plot are for the Dlines that had electrical opens. The plot graph 318 is merely an illustration of a representative scenario with increasing Dline resistance from left to right. This is primarily due to the increasing contribution of the bottom DATA bus's 304 sectional resistance from the matrix's 300 left side to the right side. Thus, an open defect 320 is identified by analyzing the plot data 318 and analyzing the data for unexpected spikes. For the matrix 300 of FIG. 3, the analysis of the plot data 318 shows that there is an open defect 320 at Dline 308b, as evidenced by the vertical spike in the plot data 318.
Similarly, open GATE line (Gline) defect data (represented by horizontal lines in the matrix 400) is collected and analyzed as shown in FIG. 4. The I/O pad 402 at the lower left corner is the DATA I/O pad for a fixed electrical connection from the common data bus 404 to an external electrical return. Similarly, the I/O pad 406 at the lower right corner is the GATE I/O pad. Electrical resistance from the individual GATE lines 408a-408n on the right side of the matrix 400 to the GATE I/O pad 406 are measured. The measured electrical resistance data may then be analyzed with respect to GATE line numbers to identify GATE line open defects.
For the GATE line (Gline) measurements, the GATE bus links 409 are severed before any measurements are taken. Using a probe 410, 412 or other measurement device connected to the system controller 204, the Gline to GATE pad (Gpad) resistance is sampled across the matrix 400 from the Gpad 406 to the individual Glines 408a-408n. Each combination of Gline 408a-408n to Gpad 406 is measured. For instance, the first measurement might be from Gpad 406 to Gline 408a, the second measurement from Gpad 406 to Gline 408b, and so on. In FIG. 4, the electrical current between certain Glines and the Gpad 406 is shown by arrows 414 and 416. The resistance measurements are then plotted with respect to the Gline number and the resistance to create a plotted graph. In this manner, the Gline 408a-408n to Gpad 406 measurements assist in identifying Gline electrical opens. As with a Dline open defect, the collected and plotted Gline data will tend to look like the example graph 418 in FIG. 4 where the high resistance spike locates the open Dline. The plot graph 418 is merely an illustration of a representative detection scenario with increasing Dline resistance from left to right. Thus, an open defect 420 is identified by analyzing the resistance plot data with respect to Dline numbers. For the matrix 400 of FIG. 4, the analysis of the plot data in view of the expected output shows that there is an open at Gline 408b, as evidenced by the vertical spike in the plot data 418.
Identifying Intra-Layer Line Bridges
Dline bridging is identified by the Dline to Dline probe measurements as illustrated in FIG. 5. In the case of Dline bridge detection, probes 500, 502 or other measuring devices such as those connected to the system controller 204 are placed at the end of separate Dlines. The path of electric current between probes 500, 502 is illustrated by arrow 504. The amount of resistance between the probes 500, 502 is measured and recorded. The process is repeated for every combination of Dlines. The recorded data is then plotted on a graph and analyzed to identify bridge defects. For a matrix 506 with no Dline bridges, one would expect a relatively flat resistance level between any two Dlines. However, as shown in graph 508, a bridge between two Dlines will show an abnormally low resistance due to the bridge. As shown in FIG. 5, the matrix 506 contains a bridge 510 between Dlines 512a and 512b, which is shown in the graph 508 as the vertical line perpendicular to the expected resistance.
For detecting GATE layer bridges, a similar arrangement as that used in FIG. 5 for the DATA layer is used, except that measurements are taken for Glines instead of Dlines.
Identifying Interlayer Shunts
In addition to measuring the Dline resistance to the Dpad which reveals the open Dline defects, much can be learned by collecting Dline to Gpad resistance data. FIG. 6 illustrates how Dline 600a-600n to Gpad 602 resistance measurements assist in identifying interlayer shunt defects 604. Using probes 606, 608, 610 or other measurement devices on matrix 650, such as those connected to the system controller 204, current is sent on each Dline 600a-600n, one at a time, from probe 606 to probe 608. Concurrently, the resistance of the current is measured at Gpad 602 with probe 610. The measured resistance data is then analyzed to identify any shunt defects. If there is no electrical shunt 604 on the matrix 650, then the measured resistance at the Gpad 602 should be constant, as shown by the line 614 on the Dline-to-Gpad graph 612. However, an electrical shunt 604 will cause the Gpad 602 to detect a variable amount of resistance from the Dline probe 606 due to the shunt 604 providing a path for the current 618 from the Dline 600a-600n to the Gpad 602. As illustrated by the Dline-to-Gpad data plot 612, the plotted resistance for a matrix 650 containing a shunt defect 604 will produce a “V” shaped plot. The lowest data point 620 of the “V” shaped data plot 616 pinpoints the location of the shunt defect 604. In FIG. 6, the shunt defect 604 is located on Dline 600f.
Alternatively, the shunt defect 604 of FIG. 6 could be identified using a differential data analysis technique which highlights the shunt defect location. With the differential data analysis technique, the resistance data is plotted after compensating for environmental factors such as initial line resistance. A differential data analysis data plot still produces a data set where the lowest resistance value (of the “V” shape) will identify the location of the shunt defect 604.
With respect to FIGS. 7a and 7b, the plotted data for a shunt defect (similar to shunt defect of 604 of FIG. 6) is shown before repair 700 and after repair 702 with a laser ablation tool.
FIGS. 8
a and 8b compare Dline differential plots of an array matrix containing a shunt defect both before repair 800 and after repair 802 with a laser ablation process. With the differential data analysis technique, the resistance data is plotted after compensating for environmental factors such as initial line resistance.
FIG. 9 simulates the Dline to Gpad resistance as a function of Dline position across an array from left to right. If a shunt defect is located on Dline 1, a positive slope linear dependence with position is demonstrated. If the shunt defect is located on Dline 481, a negative slope linear dependence with position results. If the shunt defect is not located at the array boundary (Dline 1 or Dline 481), the resulting curves are “V” shaped. The local plot minima represents the Dline which hosts the shunt defect. The absolute resistance value of the defective Dline can be used to calculate the exact cross point Gline to predict where the shunt defect occurs. However, it may be easier to just visually inspect and run down this defective Dline and locate and isolate the shunt defect.
FIG. 10 simulates the differential resistance of Dline to Gpad to Dline to Dpad vs. Dline # characteristics for single shunt conditions. The corresponding Dline to Gpad vs. Dline # characteristics are illustrated in FIG. 9. The characteristic slope to horizontal “knee” 1000 locates the measured resistance minima more apparently which assists in identifying the Dline impacted by the single shunt defect.
With respect to FIG. 11, a matrix 1100 with multiple shunt defects 1102 is shown. Resistance measurements are taken as shown in FIG. 6. However, the resulting data plot 1104 will show two data minima 1106, 1108 instead of one. Each of these minima 1106, 1108 corresponds to a shunt defect 1102 on the electrical matrix 1100. This concept can be extrapolated to any number of shunt defects on a matrix. For instance, if a matrix contains three shunt defects on different Dlines, then there will be three different minima on the resistance data plot.
FIG. 12 illustrates multiple shunt defects on the same array. For simplicity, two shunt defects are illustrated. Line 1200 is an individual singular shunt defect located at Dline 170. Line 1202 is an individual singular shunt defect on Dline 358. However, when both shunt defects 1200 and 1202 occur on the same array, dual shunt curve 1204 will be produced by the resistance measurements. The dual shunt curve 1204 has two local minimas, which are signatures for the shunt defect host lines Dline 178 and Dline 358. The dual shunt curve 1204 has been rescaled along the Y axis in FIG. 13 for better visualization.
FIG. 14 simulates the differential resistance of Dline to Gpad to Dline to Dpad vs. Dline # characteristics for two simultaneous shunts (shunts at Dline 178 and Dline 358). The characteristic “V” shapes are merged and the local minimas 1400 identify the Dlines impacted by the two shunt defects.
Correcting Identified Defects
The exemplary embodiments also comprise a method and system for dynamically reconfiguring a die (or chip) design to correct for fabrication defects, such as the open-line, bridge and shunt defects identified and/or identified above. This approach takes advantage of the on-demand printing flexibility of a digital lithography system. Chip fabrication defects are identified during the fabrication process and these faults are intelligently interpreted to redefine the chip circuitry. The chip defect type (i.e., intralayer open, intralayer bridge or interlayer shunt), location, process state and other pertinent information is dynamically input into the system so that the system can dynamically modify and re-route the chip circuitry. The new reconfigured circuitry results in modified mask layers which are then downloaded onto the digital lithography system for the printing of subsequent mask layer for the defective substrate.
The exemplary embodiment described requires no additional equipment or layers for the repairs, which call only for modifications of the specifications for layers that are already part of the circuit design. Although the current embodiment and emphasis is on POE arrays, this methodology can be applied to other devices as well. Trace opens and VIA opens in PCB and other low temperature polysilicon application manufacturing can also benefit by using the exemplary embodiment. These techniques can be used to fix memory arrays, FPD arrays etc. as well.
Referring now to FIG. 15, a POE array 1500 with identified open defects 1502, 1504, 1506, 1508 is illustrated. The open defects are identified as shown above with respect to FIG. 3 and FIG. 4. The POE array 1500 contains a set of cut lines 1510 that must be severed from the array 1500 in order to isolate the DATA and Glines from the peripheral buses 1512.
With respect to FIG. 16, the POE array 1500 of FIG. 15 is depicted after mushroom metal layers 1600 are added with a VIA layer 1602 to the array 1500 in order to correct open-line defects 1502, 1504, 1506, 1508. As described with respect to FIG. 2, the layer definition module 206 creates a layer design that includes a mushroom metal layer 1600 and VIA layer 1602 for application on the POE array 1500. The new layer definition is designed such that open defects such as 1502, 1504, 1506, 1508 are corrected by connecting each side opposite the open defect to form an uninterrupted GATE or DATA line. The layer definition module 206 creates the modified layer design such that the new layers 1600, 1602 do not overlap. The mushroom metal layer 1600 and VIA layer 1602 design reconfiguration are then downloaded to a digital lithography printer (FIG. 2, item 208) for pattern definition for a POE circuit.
With respect to FIG. 17, the POE array 1500 of FIG. 15 is depicted with an alternate solution for the open-line defects 1502, 1504, 1506, 1508. This alternative solution utilizes a mushroom metal layer 1700 and a VIA layer 1702 with localized line bridging. This technique is useful if a pixel design rule dictates adequate real estate space on the array 1500 to implement such a fix. The mushroom metal and VIA layer design reconfiguration is then downloaded to a digital lithography printer for pattern definition, as shown in FIG. 19.
With respect to FIGS. 18a and 18b, a close-up view of shunt defect 1800 is shown. After the shunt defect 1800 is identified (as shown in FIG. 18a), a laser ablation method is used to electrically isolate the shunt defect 1800 (as shown in FIG. 18b). In this case, laser cuts 1802, 1804 above and below the intersecting Gline 1806 are sufficient. After the laser ablation cuts 1802, 1804 are made, the shunt defect 1800 then degenerates to a Dline open since the line was cut near the shunt defect 1800. At this stage, the new Dline open can be corrected the same as the open defects above in FIGS. 16 and 17.
FIG. 19 is a flow chart illustrating the data measurement points 1902, 1904, 1910, 1912 for the GATE and DATA (aka S/D) layers in an example TFT fabrication in-process flow. The process can be performed by the in-process defect detection and correction system 200 of FIG. 2.
At step 1900, a GATE pattern is formed on a substrate via a printing process utilizing digital lithography based design.
At step 1902, the system controller (FIG. 2, item 204) measures the Gline resistance from the gate pads to the Gate bus I/O pad as shown in FIG. 4. The exemplary embodiment enables the improved strategy of detecting Gline faults because there are GATE level buses on opposing sides of the Glines (as shown by items 422 and 424 of FIG. 4). This facilitates an optimized dual feed GATE dielectric anodization scheme. It also helps to provide a better ground plane for shunt detection.
At step 1904, the Gline resistance measured in step 1902 is plotted and analyzed by the system controller (FIG. 2, item 204) as shown in FIGS. 4 and 5. The resulting defect data (FIG. 2, item 214) is then sent to the layer definition module (FIG. 2, item 206) and laser ablation tool (FIG. 2, item 207) for defect correction. Any open or bridge defects detected here will be corrected in step 1916.
At step 1906, additional TFT fabrication processing is performed.
At step 1908, a DATA pattern is formed on the substrate via a printing process utilizing digital lithography based design.
At step 1910, the Dline resistance from the DATA pads to the DATA bus I/O pad and GATE bus I/O pad is measured as shown in FIGS. 3, 5, 6 and 11. The measuring process is similar to that of step 1902.
At step 1912, the measured resistance from step 1910 is plotted and analyzed (in a manner similar to step 1904) in order to detect Dline defects and shunt defects. Any defects detected here will be corrected in step 1916.
At step 1914, any necessary additional TFT fabrication processing is performed.
At step 1916, the defect knowledge gained in steps 1904 and 1912 by the system controller (FIG. 2, item 204) is fed forward to defect processing modules (FIG. 2, items 206, 207) for re-routing the defective lines around the POE array matrix using the yet un-processed VIA and Mushroom Metal layers. Open-line defects are repaired by applying VIA and mushroom metal layers around the POE array matrix to bridge the electrical signal path that was severed because of the open defect. FIG. 16 illustrates such a design re-configuration using these new layers which are then downloaded to a maskless digital lithography printer (FIG. 2, item 208) for patterning. An alternate embodiment can perform localized “spot” bridge repair of open line defects inside the POE array matrix using the VIA and mushroom metal layers, if design rules permit. The alternate embodiment is illustrated in FIG. 17 where the line bridge repair is localized within the matrix array. This technique is useful if the pixel design rule dictates adequate real estate space to implement such a fix. For bridge and shunt defects, a laser ablation process (or any other suitable alternative) is used to isolate the defect. In the case of a shunt defect, the laser ablation process will change the shunt defect into an open line defect (as shown in FIG. 18b), which can then be repaired with the VIA and mushroom metal layer definitions as described above. Since this is a maskless lithography process, no new mask cost is associated with these mask layer updates. As a result, near perfect POE imagers can then be realized.
At step 1918, the fabrication of the TFT POE array matrix is completed. If desired, the fabricated product can then be tested using conventional techniques such as x-ray imaging.
It will be appreciated that various of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Also that various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.
Patent Application
20110185322
