Patent Application
20060141369
This application is based on, and claims priority to, Japanese Application No. 2004-379438, filed Dec. 28, 2004, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a method for making a correction to pattern data and a method for manufacturing semiconctor devices, and particularly to the method for making the correction to pattern data affected by a proximity effect when a pattern is formed on a photomask or wafer and the method for manufacturing semiconductor devices using the above method.
2. Description of the Related Art
In recent years, patterns to be formed by photolithgraphy employed in processes of manufacturing leading-edge semiconductor devices are being made fine and highly-integrated. As a result, a problem occurs in that, in the formation of a pattern with an exposure wavelenth or less, due to an adverse influence by a proximity effect, a shape of a mask pattern using a photomask (hereinafter simply referred to as a “mask”) does not coincide with that of a resist pattern obtained by transferring the mask patter on a wafer.
Also, in the etching process for microfabrication of a front-end layer using a resist pattern on which the mask pattern has been transferred, due to a loading effect which leads to variations in a conversion difference caused by a difference in a pattern shape and a pattern density, a phenomenon occurs that a shape of a resist pattern does not coincide with that of a microfabricated pattern for the front-end layer obtained by the selective etching process.
To solve this problem and to obtain a pattern having a desired dimension and shape, an OPC (Optical Proximity Correction) technology in which a required amount of correction is added to mask pattern data is being employed generally in recent years. To obtain an effect of the OPC techonolgy, it is necessary that a difference between a finally-obtained dimension of a mask pattern and a dimension in mask pattern data is made as small as possible. In the formation of a mask to be used for manufacturing recent leading-edge semiconductor devices in particular, very extremely high accuracy in its linearity, in difference of pattern density, or the like is required. However, at present, it is difficult to satisfy the demand for such extremely high accuracy only by improvement of mask producing processes. This holds true for manufacturing a mask using a nega-type resist in particular. The process of manufacturing a mask using a nega-type resist is employed when a mask for a gate layer requiring extremely high accuracy is produced, thus presenting a serious problem.
A method for correcting such a dimensional error by using the OPC technology is disclosed in, for example, Japanese Unexamined Patent Publication No. 2003-195478. In this method, so-called rule-based OPC technology is applied to a mask process. According to this method, a correlation between a space dimension among adjacent patterns and a dimensional change in a pattern itself is first determined and, by using this result, a necessary dimensional correction is made to mask pattern data.
However, the conventional method disclosed in Japanese Unexamined Patent Publication No. 2003-195478 has a problem that the process in the method has a favorable correcting effect on a simple pattern if including only a line pattern and space, but adversely affects a pattern having a complicated layout.
In view of the foregoing, it is an object of the present invention to provide a method for correcting pattern data which is capable of making a proper correction to data of a pattern having a complicated layout.
It is another object of the present invention to provide a method for manufacturing a semiconductor device which enables a desired microfabricated pattern to be obtained.
According to one aspect of the present invention, there is provided a pattern data correcting method for making a correction to pattern data affected by a proximity effect when a pattern is formed on a photomask or wafer according to design data for a semiconductor device, including the steps of: detecting, according to the design data, a space portion being placed on the photomask or wafer and having a specified size occurring between patterns facing each other in a first direction; producing a pattern data corresponding to an assist pattern that fills the space portion; detecting an edge to be corrected in a position being opposite to an edge of the assist pattern extending in a second direction between the patterns facing each other, out of framing portions of the pattern being placed in parallel and near to the assist pattern; making a correction being independent of a correction to be made to other edge of the framing portions to the detected edge to be corrected; and removing the assist pattern.
According to another aspect of the present invention, there is provided a pattern data correcting method for making a correction to pattern data affected by a proximity effect when a pattern is formed on a photomask or wafer according to design data for a semiconductor device, including the steps of: extracting a region, as an isolated edge, in which a space portion occurring between second patterns facing each other exists within a specified distance in a first direction, out of edges in framing portions of a first pattern; producing pattern data corresponding to an assist pattern that fills the space portion; extracting an edge of the assist pattern extending between the first and second patterns facing each other in a second direction; making a correction to data of the isolated edge according to a length of the edge of the assist pattern and an interval between the assist pattern and the isolated edge; and removing the assist pattern.
According to still another aspect of the present invention, there is provided a method for manufacturing a semiconductor device including the step of: performing exposures by using a photomask formed, with an aim of making a correction to pattern data affected by a proximity effect when a pattern is formed on a photomask or wafer according to design data for a semiconductor device, by detecting, according to the design data, a space portion being placed on the photomask or wafer and having a specified size occurring between patterns facing each other in a first direction, by producing a pattern data corresponding to an assist pattern that fills the space portion, by detecting an edge to be corrected in a position being opposite to an edge of the assist pattern extending in a second direction between the patterns facing each other, out of framing portions of the pattern being placed in parallel and near to the assist pattern, by making a correction being independent of a correction to be made to other edge of the framing portion to the detected edge to be corrected, and by removing the assist pattern.
According to still another aspect of the present invention, there is provided a method for manufacturing a semiconductor device including the step of: performing exposures by using a photomask formed, with an aim of making a correction to pattern data affected by a proximity effect when a pattern is formed on a photomask or wafer according to design data for a semiconductor device, by extracting a region, as an isolated edge, in which a space portion occurring between second patterns facing each other exists within a specified distance in a first direction, out of edges in framing portions of a first pattern, by producing pattern data corresponding to an assist pattern that fills the space portion, by extracting an edge of the assist pattern extending between the first and second patterns facing each other in a second direction, by making a correction to data of the isolated edge according to a length of the edge of the assist pattern and an interval between the assist pattern and the isolated edge and by removing the assist pattern.
The above and other objects, features and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings which illustrate preferred embodiments of the present invention by way of example.
A method is described for making a correction to pattern data affected by a proximity effect when such a patter as shown in
When a proximity-effect correction is made by the conventional method to design data having patterns 1, 2, 3, and 4 as shown in
In the pattern data correcting method shown in
Next, pattern data corresponding to an assist pattern that fills the detected space portion 5 is produced (Step S2).
By using the pattern data correcting method described above, a proper correction can be made to even an edge which is ordinarily handled as an isolated pattern and to which no proper correction is made.
The pattern data correcting method is explained in detail below. The pattern data correcting method described below is realized by operations of a CPU (Central Processing Unit) according to an algorithm of software installed in, for example, a computer.
First, an end 10a of a pattern 10 having a specified length or more in directions of arrows A1 and A2 under a condition is recognized. When another pattern 11 exists within a specified distance L1 (for example, within 2000 nm), the pattern 11 and pattern 10 facing each other are recognzied as an I-shaped portion. Moreover, if a width W1 of the pattern 11 is larger than a value, the pattern 11 and pattern 10 facing each other is recognized as a T-shaped portion. In the example shown in
Moreover, if neither the I-shaped nor T-shaped portion is extracted in the process in Step S11 in
Next, the edge of the assist pattern extending in a direction between patterns facing each other is extracted (Step S13). Here, in the assist pattern 6 as shown in
Thereafter, the edge positioned opposite to edges of the assist pattern extending in a direction of a distance between the patterns facinfg each other, out of framing portions of the pattern being placed in parallel and near to the detected assist pattern is detected as an edge to be corrected (Step S14). More specifically, by detecting a difference between pattern data of the assist pattern with layer definition performed and real pattern data and, as shown in
Next, after a rule check is made, whether or not a correction is made to the detected edge to be corrected is judged (Step S15). In this rule check, unlike in the case of the ordinary proximity-effect correction rule (Line & Space), for example, in the case of the pattern data shown in
If it is judged that the edge to be corrected requires a correction, a correction value is determined according to a butting interval and a space width to make the correction to the edge 4a (Step S16). Here, the correction may be made by referring to a table in which correction values predetermined according to the butting interval and the space width are stored. Thereafter, the produced assist pattern is removed (Step S17) and the correction processing is terminated. Moreover, if it is judged, for example, due to the large space width and butting interval, that the edge to be corrected requires no correction, the correction is not made and, after the completion of the process in Step S17, the correction processing is terminated.
On the other hand, in the process in Step S11, when an I-shaped or T-shaped portion that can meet conditions is not detected, whether or not a correction is made is judged according to the ordinary proximity-effect correction rule (Line & Space) (Step S18) and, if the correctin is to be made, a correction value is determined and according to space and line dimensions and the correction is made to the edge (Step S19). If it is judged that no correction is required, the correction processing is terminated without making the correction.
Thus, by extracting a portion in which patterns face each other in an I-shaped or T-shaped manner under a specified condition, the space portion 5 that influences on the edge 4a as shown in
Next, a method for correcting pattern data of a second embodiment is explained.
Furthermore, in the rule check in Step S26, by detecting a butting interval and a distance for which the edge 6a of the assist pattern 6 has been moved by the process in Step S24, a judgement is made as to whether or not the edge 4a is to be corrected. If the edge 4a is to be corrected, a correction value is determined according to the butting interval and the distance for which the edge 6a of the assist pattern 6 has been moved and then a correction is made to the edge 4a (Step S27). After that, the produced assist pattern 6 is removed (Stpe S28) and the correction processing is terminated. If it is judged that no correction to the edge to be corrected is required, after the completion of the process in Step S28, the correction processing is terminated without making the correction. The processes in Steps S29 and S30 are the same as those in Steps S18 and S19 shown in
Next, a pattern data correcting method of a third embodiment of the present invention is explained.
In the pattern data correcting method of the third embodiment, after an edge (called a first edge in the third embodiment) extending in a direction of a distance between patterns facing each other has been extracted in Step S43, a second edge being vertical to the first edge is further extracted (Step S44). Then, by extending the second edge (Step S45), an edge to be corrected is detected (Step S46).
Furthermore, in the rule check in Step S47, by checking a butting interval and distance for which the second edges 6c and 6d having been extended in Step S45 come to contact with the pattern 4, a judgement is made as to whether or not the edge 4a is to be corrected. If the edge 4a is to be corrected, a correction value is determined according to the butting interval and distance for which the second edges 6c and 6d having been extended come to contact with the pattern 4, and the edge 4a is corrected (Step S48).
Here, the correction value of the edge 4a to be corrected may be determined according to an angle which the extended second edges 6c and 6d form with the edge 4a to be corrected of the pattern 4. For example, a correction table created by using this angle as a parameter to determine the necessity of correction and/or a correction value may be employed as a reference.
Then, the produced assist pattern is removed (Step S49) and the correction processing is terminated. Moreover, if it is judged that no correction to the edge to be corrected is required, after the completion of the process in Step S49, the correction processing is terminated without making the correction. The processes in Steps S50 and S51 are the same as those in Steps S18 and S19 shown in
Next, a pattern data correcting method of a fourth embodiment of the present invention is explained.
In the pattern data correcting method of the first to fourth embodiments, an assist pattern that fills a space portion having a specified size is first produced and an edge to be corrected is detected according to the produced assist pattern. However, an edge recognized as an isolated pattern may be first extracted. This is explained by using a fifth embodiment below.
Next, an assist pattern to fill the space portion 23 is produced (Step S83).
Furthermore, in the rule check in Step S85, by checking a length (butting interval) of each of the extracted edges 24a and 24b and an interval between the assist pattern 24 and the isolated edge 20a to be corrected, a judgement is made as to whetehr or not the isolated edge 20a is corrcted.
Here, to explain a specific judgement standard, a result from evaluation is shown on a dimensional characteristic of a region regarded as an isolated region in an edge in framing portions of a pattern.
As is apparent from this graph, if the space width is 1000 nm or more, the region defined as the isolated edge 20a shows a dimensional characteristic as an ordinary isolated region irrespective of a butting interval value. That is, even if the space width is changed, the dimension is kept constant.
On the other hand, when the space width is 1000 nm or less, dimensional errors in the region defined as the isolated edge 20a gradually increases, which narrows the interval between the pattern 20 and patterns 21 and 22. That is, if a pattern density in an area surrounding a dimensional measurement point becomes high, an etching speed in the entire region decreases and, as a result, a pattern dimension is made large. Moreover, if the butting interval becomes 2000 nm, even when the space width is made narrow, no increase in the dimensional errors occur.
According to the above evaluation results, in the case of patterns as shown in
On the other hand, in the case of the edge having been judged not to be an isolated edge in the process in Step S81, a judgement is made as to whether the correction is made according to an ordinary proximity-effect correction rule (Line & Space) (Step S88) and, if the correction is made, by using, for example, the table 1 described above, a correction value is determined according to space and line dimensions and the correction is made (Step S89). If it is judged that no correction is required, the correction processing is terminated without making the correction.
In the pattern data correcting method of the first to fifth embodiments, either of the processing in which a correction is made to design data according to an ordinary proximity-effect correction rule (processes in Steps S18, S19, S29, S30, S50, S51, S70, S71, S88 and S89) and the processing in which an edge of a pattern likely to be judged as requiring a correction but as an isolated edge (hereinafter called an apparently isolated edge) is detected and a correction is made according to a rule being independent of a rule to be applied to a correction to other edge (processes in Steps S11 to S17, S21 to S28, S41 to S49, S61 to S69, and S81 to S87) is selected depending on conditions. However, the processing in which a correction is made to such an apparently isolated edge as above according to a rule being independent of a rule to be applied to a correction to other edge may be applied to data having been corrected first by using the ordinary proximity-effect correction rule.
Next, a pattern data correcting method of a sixth embodiment is explained.
First, when designa data to produce an original drawing is input (Step S90), an judgement is made as to whether or not a correction is made according to the ordinary proximity-effect correction rule (Line & Space)(Step S91) and, if the correctin is made, a correction value is determined and according to space and line dimensions, and the correction is made (Step S92). When the correction was made and, if it is judged that no correction to the corrected data is required, the original design data is output to a storage medium 30 such as a hard disk drive or the like without making the correction (Step S93).
Thus, by applying the pattern data correcting method of the first to sixth embodiment, a mask obtained by making a proper correction to data of a pattern having a complicated layout and affected by a proximity effect can be produced.
Finally, an example is described in which the mask produced by using the pattern data correcting method as explained above is applied to actual manufacturing of a semiconductor device.
Next, as shown in
Next, as shown in
The N-type impurity diffused region 108 is formed by the implantation of, for example, arsenic ion (As+) with accelerated energy of 100 keV and in a dose of 5×1012 cm−2. Also, the N-type impurity diffused region 109 is formed by the implantation of, for example, arsenic ion (As+) with accelerated energy of 150 keV and in a dose of 5×1013 cm−2. The N-type impurity diffused region 110 is formed by the implantation of, for example, phosphorus ion (P+) with accelerated energy of 300 keV and in a dose of 3×1013 cm−2.
Next, by carrying out wet-etching using, for example, a hydrofluoric water solution, the sacrificial oxide film 102 is removed. Then, for example, by the thermal oxidation method, a silicon oxide film with a film thickness of, for example, 11 nm is made to grow on a device region that is exposed by the removal of the sacrificial oxide film 102 and, as shown in
By a stepper using an ArF exima laser as a light source, exposures of a pattern for a mask produced by the pattern data correcting method in the first to sixth embodiments are performed on the wafer substrate in the state described above. The exposure is performed under conditions of a numerical aperture (NA) being 0.7, ½ zonal illumination (σ value:0.425/0.85), and an amount of exposure being 210 J/cm2.
Next, by thermal treatment as a post exposure baking (PEB) process and developing processing, a resist pattern 113 is formed. Then, by using the resist pattern 113 as a mask, the anti-reflection film 112, the polycrystalline silicon film (not shown), and the gate insulating film 111 are etched to form gate electrodes 114 and 115 made up of a polycrystalline silicon film. Here, the gate electrode 114 serves as a gate electrode of an N-type transistor and the gate electrode 115 serves as a gate electrode of a P-type transistor.
Thus, a study on uniformity in pattern dimensions of the gate electrodes 114 and 115 formed by using the pattern data correcting method employed in the first to sixth embodiments shows that dimensional uniformity obtained by using the mask produced by the pattern data correcting method of the present invention is improved by about 4 nm in length when compared with the case of using the conventional mask.
Moreover, in all the above first to sixth embodiments, the pattern data correcting method is applied when a correction is made to a pattern formed on a mask. However, the pattern data correcting method of the present invention can be also applied when the correction is to be made to data of a pattern which is affected by a proximity effect and is formed on a wafer.
According to the present invention, since a space portion being formed on a photomask or a wafer and having a specified size occurring between patterns facing each other in a first direction is detected according to design data, pattern data corresponding to an assist pattern that fills the space portion is produced, an edge to be corrected placed in a position being opposite to an edge of an assist pattern extending in a second direction between patterns facing each other, out of framing portions of the pattern positioned in parallel and near to the assist pattern, is detected, and a correction being independent of a correction to be made to other edge in the framing portion of the pattern is made to an edge to be corrected, it is possible to make a proper correction to even an edge which is ordinarily recognized as an isolated pattern and to which a proper correction is not made.
Also, since a region where a space portion occurring between second patterns facing each other, out of edges in framing portions of the second pattern, exists is extracted as an isolated edge, pattern data corresponding to a assist pattern that fills the space portion is produced, an edge of a assist pattern extending in a second direction of a distance between the first and second patterns facing each other is extracted, and a correction is made to the isolated edge according to a length of the extracted assist pattern and to an interval between the assist pattern and the above isolated edge, it is possible to make a proper correction to even an edge which is ordinarily recognized as an isolated pattern and to which a proper correction is not made.
Furtheremore, by applying a photmask formed by using the above methods to a process of manufacturing a semiconductor device, it is made possible to form a desired microfabricated pattern.
The foregoing is considered as illustrative only of the principles of the present invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and applications shown and described, and accordingly, all suitable modifications and equivalents may be regarded as falling within the scope of the invention in the appended claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-379438 | Dec 2004 | JP | national |
