Patent Application
20080063948
Reference will now be made in detail to various exemplary embodiments of the present application, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.
Referring to
At 2, the process illustrated in the embodiment of
At 3, the process of the
At 4 of the embodiment of
Since it is generally the case that a certain percentage of SRAF patterns cannot be resized or reshaped during the process at 4 so as to satisfy all compliance rules, the SRAF patterns corrected in the process at 4 may be checked against the compliance rules to determine which, if any of them, still fail to comply with the compliance rules. If it is determined that some of the illegal SRAF are not corrected during the process at 4 to comply with all the mask making rules, it may be possible to reposition at least some of the remaining illegal SRAFS in a manner which allows them to comply with the mask making rules, as set forth at 5 of
Thus, SRAF found to violate the compliance rules after the process at 4 can be reassigned to a second mask position that is different from the originally assigned SRAF position. In this manner, another group of illegal SRAF patterns can be corrected, in addition to the SRAF patterns corrected as described with reference to 4.
The second SRAF position may allow the SRAF pattern to comply with the preselected compliance rules, even though it may not necessarily comply with all SRAF rules. As discussed above, each SRAF is assigned a first position on the mask according to the SRAF rules, and by reassigning the SRAF to a second position, the SRAF rules may consequently be violated. However, it has been found that it is often the case that it is better to include the SRAF on the photomask, even though it fails to comply with the original SRAF position dictated by the SRAF generating software, rather than delete the SRAF altogether.
After the SRAF patterns are repositioned by the process at 5, additional checks may be carried out to determine if the repositioned SRAF patterns comply with all of the preselected compliance rules. In some embodiments, any repositioned SRAF patterns that are found to violate compliance rules at this point in the process may be deleted. In other embodiments, the processes at 4 and/or 5 may be repeated in an attempt to correct the remaining illegal SRAF patterns so that they comply with the compliance rules. For example, the SRAF pattern may be reassigned to a third position which is different than the second assigned position. In another embodiment, the SRAF may be left in the second position, but resized and/or reshaped, as described in the process at 4, so as to comply with the compliance rules. The processes at 4 and/or 5 may be repeated multiple times in this manner until it is determined that all the SRAF patterns either comply with the preselected compliance rules or have been deleted.
Additional processing may be carried out once all the SRAF patterns have been determined to either comply with the compliance rules or have been deleted. Examples of such additional processing can include, for example, optical proximity correction (OPC) to correct for optical proximity effects, as indicated at 6. Any suitable technique for correcting for optical proximity effects may be employed. Examples of suitable optical phase correction techniques are disclosed in U.S. Pat. No. 6,764,795, issued on Jul. 20, 2004 to Aton et al., the disclosure of which is herein incorporated by reference in its entirety.
After OPC, pattern generation can be carried, which is a process carried out by a computer program that prepares the mask data to go to the mask writer. Suitable software for carrying out pattern generation is well known in the art. One example of a suitable software program known in the art for pattern generation is HERCULES, which is available from SYNOPSYS.
The photomask pattern data prepared using the process of the embodiment of
The embodiments of the present application are not intended to be limited to the processes illustrated in
In order to comply with the minimum spacing rule, SRAF patterns 22 and 24 are each assigned to a second mask position. The second mask positions may be determined by any appropriate method that will satisfy the minimum spacing rule.
In one example, the distance x between SRAF 22 and SRAF 24 resulting from the originally assigned mask positions may be 4 nm, while the minimum spacing rule may require x to be, for example, 40 nm. One or both of the SRAF may be moved a distance that will provide at least the distance needed to meet the minimum spacing rule. For example, each SRAF in the above example may be moved a distance of about 18 nm in opposite directions, to provide the distance x′, as illustrated in
The SRAF patterns can be moved in any direction in the plane of the mask to satisfy the minimum distance requirement. For example, in an x, y Cartesian coordinate system, the SRAF patterns may be moved along an x-axis, a y-axis, or, as illustrated in
The SRAF are not limited to any particular shape. For example, the SRAF patterns may be rectangles, as in the embodiment of
As shown in the embodiment of
Computer 74 may include a personal computer, workstation, network computer, wireless computer, or one or more microprocessors within these or other devices, or any other suitable processing device. Computer 74 may include a processor 76, and an SRAF module 77. Computer 74 may also include other modules, as desired.
The above SRAF module 77 can exist as software that includes program instructions in source code, object code, executable code or other formats; program instructions implemented in firmware; or hardware description language (HDL) files. Any of the above can be embodied on a computer readable medium, which include storage devices and signals, in compressed or uncompressed form. Exemplary computer readable storage devices include conventional computer system RAM (random access memory), ROM (read-only memory), EPROM (erasable, programmable ROM), EEPROM (electrically erasable, programmable ROM), and magnetic or optical disks or tapes.
Processor 76 controls the flow of data between input device 72, output device 73, database 751 and SRAF module 77. SRAF module 77 may receive data from database 75, which may include, for example, design data for target features of integrated circuit devices to be patterned, and data describing main feature patterns generated from a main feature generation module (not shown) for printing the target features from the design data. Using such data, the SRAF module 77 can generate SRAF patterns, as described above. SRAF module 77 can then determine if the generated SRAF patterns comply with a preselected set of compliance rules, and identify any illegal SRAF patterns that fail to comply. If any SRAF are identified as illegal the SRAF module 77 can then generate corrected SRAF patterns, as described above. The modules may include instructions operable to prompt the user for input during the above processes, as desired.
In other embodiments, the processes for generating SRAF, determining if the SRAF comply with the preselected compliance rules, and correcting SRAF, may be accomplished by separate modules, which may be stored on separate databases and/or employed by separate processors. For example, the process of generating SRAF may be carried out on a first processor; and the process of determining if the SRAF comply with the rules and then correcting illegal SRAF may be carried out on a second processor.
Database 75 may include any suitable system for storing data. Database 75 may store records 78 that include data associated with the integrated circuit device features to be patterned. Examples of such data include design data for the device features, photomask pattern data, and any other data, such as data regarding SRAF rules and/or compliance rules that may be used to determine if the generated SRAF patterns comply.
Embodiments of the present application are directed to an integrated circuit device and method of forming the integrated circuit device by employing a photomask having a photomask pattern prepared by the processes of the present application. The integrated circuit devices can be prepared by, for example, applying a photoresist to a wafer using techniques well known in the art. The photoresist is then exposed to radiation through a photomask having a photomask pattern prepared by any of the processes of the present application, as described herein. The photoresist can be developed using techniques well known in the art to form a photoresist pattern on the wafer. Processes such as etching or ion implantation can then be carried out using the photoresist pattern to, for example, selectively etch or selectively ion implant portions of the device by techniques well known in the art in order to form features of the integrated circuit device.
In some embodiments, forming the integrated circuit device using a photomask having photomask patterns generated using the processes of the present application can result in improved patterning of the integrated circuit. For example, where SRAF patterns are corrected by reassigning illegal SRAF patterns to second mask positions, as described in 5 of the embodiment of
For the purposes of this specification and appended claims, unless otherwise indicated, all numbers expressing quantities, percentages or proportions, and other numerical values used in the specification and claims, are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the present disclosure. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.
It is noted that, as used in this specification and the appended claims, the singular forms “a,” “an,” and “the,” include plural referents unless expressly and unequivocally limited to one referent. Thus, for example, reference to “an acid” includes two or more different acids. As used herein, the term “include” and its grammatical variants are intended to be non-limiting, such that recitation of items in a list is not to the exclusion of other like items that can be substituted or added to the listed items.
While particular embodiments have been described, alternatives, modifications, variations, improvements, and substantial equivalents that are or can be presently unforeseen can arise to applicants or others skilled in the art. Accordingly, the appended claims as filed and as they can be amended are intended to embrace all such alternatives, modifications variations, improvements, and substantial equivalents.
