TW520544B - Method and apparatus for measuring bridge caused by mask layout correction - Google Patents

Abstract

A kind of method for measuring bridge caused by mask layout correction is disclosed in the present invention. At first, a mask having layout is provided, in which the layout at least contains the conduction wire pattern, multiple gate electrode patterns connected to the conduction wire pattern, and multiple contact pattern sets. Each contact pattern set contains at least multiple contact patterns and at least surrounds one terminal of the corresponding gate that is not connected with the conduction wire pattern. Then, the layout is corrected; and the corrected layout is transferred to the substrate. The conduction wire, multiple gate electrodes and multiple contact sets are formed on the substrate. After that, these contact sets are electrically connected to a terminal. The electric signal is then added to the conduction wire to measure and determine if there is any electric signal generated due to the bridge at the terminal.

Description

520544 V. Description of the invention α) 5-1 Field of the invention: The present invention relates to a method, a structure and a layout for measuring a bridge between a gate and a contact caused by correction of a mask pattern. 5-2 Background of the Invention: Because the pattern transfer process cannot always transfer the pattern of the photomask to the photoresist, and the development process and the etching process are always inevitable, the pattern actually formed on the substrate is often related to the photomask. The patterns are different but have the following defects: endr rounding, end shorting, corner rounding, critical dimension offset, and bridging phenomena 0 Therefore, in actual semiconductor processes, in order to offset the above-mentioned shortcomings, the mask layout is usually modified after the layout pattern is completed, such as optical proximity correction (〇ptica 1 pr ο X imitycorrecti ο n, 0 PC), and then the subsequent pattern transfer process and other manufacturing processes are performed. Since the substrate pattern is usually shorter or thinner than the mask pattern, the modification of the mask layout is usually to widen, lengthen or add auxiliary patterns to the actual pattern on the mask to offset the mask pattern and the substrate. The gap between the material patterns makes the actual pattern of the substrate pattern and the front mask without correction.

520544 Fifth, the description of invention (2) is the same. In the actual semiconductor manufacturing process, the pattern of the mask contains tens of millions of cells, so the correction of the mask layout is always performed automatically by the computer according to the set rules and parameters. Therefore, although the operator can adjust the modification of the mask layout by modifying predetermined rules and parameters, once the rules and parameters used have been determined, the operator cannot control the correction of each unit one by one. Obviously, as the critical dimensions of semiconductor elements are continuously shortened and the density of semiconductor elements is continuously increased, the possibility of correction of adjacent pattern elements to contact each other (commonly referred to as bridging) is also increased. Refer to the actual required pattern 10 and the correction pattern 11 shown in the first spring diagram A, the first B diagram, the first C diagram, and the first D diagram. Here, the first B diagram is the correction pattern 11 without bridging. The first D picture is a case where the correction pattern 11 is bridged. Because the bridging phenomenon is a side effect of correcting the pattern 11 to the actual desired pattern 10, the appearance of the bridging phenomenon often cannot be eliminated in the pattern transfer process and the etching process, etc., and a bridging should be generated on the substrate pattern. For example, a bridge between a gate pattern (to form a gate) and an adjacent contact pattern (to form a contact connected to a source / drain) or a gate pattern of a transistor pattern and an adjacent transistor pattern The bridging of the gate pattern may cause abnormalities such as short circuits. φ Therefore, how to confirm whether the correction of the mask layout causes abnormal bridges has become an indispensable part of correcting the mask layout. In the conventional technology, or because of the distance between the transistors,

520544 V. Description of the invention (3) The distance between f is large, or due to the layout of the entire semiconductor element, the gate of the solar core is clearly separated, and so on. Therefore, the focus is only on the measurement and the contact between the two sides Between them, and its operation is shown in Figure A, Figure A and Figure C. The first figure B contains L. When the layout of the transistor to be formed includes the gate 2 1 as shown in the second A, the gate 2 1 is in contact with the gate 2 1 on the two sides of the device area 2 0. Hair: Measure whether such a transistor can form a proper photomask pattern:: Bridges are missing, etc. First, a pattern similar to the second A picture is formed on the photomask and the approximate gate pattern shown in the second B picture 23 and several approximate contact cases 2 4 in the correction element area 2 0 5, here the approximate gate pattern 2 3 and the number of configurations of the < :: pattern 24 are basically similar to the two poles ~ ^ ^, The configuration of the contact 22, but the size and relative distance can be modified without the pattern shown in the second figure B (such as optical proximity correction) 27, the U pattern is transferred to the substrate 25 to form the gate 26 and several contacts As shown in Figure C, here is to emphasize how to detect _ #, σ t :: giant is too close to make some places really bridge this, couple each contact 2 7 to an endpoint, and then apply = this The end point is measured right &mountain; the L number will be represented at the gate pole. If 'r also' is displayed, the correction of the electrical signal at the endpoints triggers a bridge between 7 and gate 2 Chen, which means that the mask layout pattern 23 and several patterns must be modified. The approximate electrode and crystal layout shown in the figure are modified. Helmet method: Pattern 24. Although, it can also be regarded as such that the mask layout pattern of this transistor must be modified to form a proper correction, but the layout of a or even the existing mask layout pattern.

Page 6 520544 V. Description of the invention (4) When connected, it is also the case of the I contact pattern of the case 2 8 and the case 2 9 and its weekly case 2 9 and | measured in the photomask | contact diagram bridged with the simulated contact 2 2 The gate electrode =, because when modifying the second B picture, it is not only necessary to know the beneficial products, but also to know how far the intermediate pole 21 is from the contact 22. As shown in the second picture, it is usually shaped on the photomask :: It is connected to a plurality of similar （-line diagram patterns (even the size and shape are equal). Here, each of the simulated gate patterns 29 has a majority of gate diagrams on its two sides, and here it is: The distance of the contact pattern 2 9 5 is different from that of other simulated gates = the distance of the simulated contact pattern 2 9 5 around it is different. ^ = Layout correction (such as optical proximity correction) and pattern transfer to the bottom hunting 2 substrate 2 5 Corresponding to each analog gate pattern 2 9 and its week {Case 2 9 5 each gate 2 6 and corresponding contact 2 7 rooms, 'Now bridge, you can know what group of analog interpole diagrams 29 = pattern 295 can Comes as a mask corresponding to the closed pole with two 9 dagger cases. Of course 'if not only-the group will not bridge, it should be shaped 2 1 The total difference between the total contact 22 and the transistor to be formed shall prevail. = On M, as the density of semiconductor elements continues to increase, the distance between the individual cells and the distance between the free electrode and the contact in the transistor is gradually increased. The similarity and evolution of the layout of some semiconductor components (such as static random: memory) have made the free terminals of different transistors close to each other. Known techniques 丨 = Measurement of the bridge between the gate and the contact in the transistor Unable to properly fit =: caterpillars may occur. | For example, if the pattern to be formed is similar to the second A picture but the length of the gate 21 is longer, it is possible

520544 V. Description of the invention (5) The situation shown in Figure 2E is formed. Although there is no bridging phenomenon, the terminals of the gate 2 6 are generally referred to as end cap phe omena after correction. Changes in width or hammerheads. Obviously, if the distance between the two transistors is so close that the gate patterns of the two transistors will affect each other when the mask pattern is modified, it is likely that the gates of adjacent transistors will appear as shown in Figure 2F. Bridge between poles. Of course, the second F diagram is only an example, and it may also be that a gate of a transistor is in contact with a certain contact of an adjacent transistor, or a certain contact of a certain transistor and a certain contact of an adjacent transistor Contact bridging occurs. In summary, the conventional technique can only measure the bridge caused by the deformation of the gate and contact (especially the gate) in the same transistor that is generated when the mask layout is modified, and cannot effectively measure the other caused by the bridging. Therefore, it is necessary to modify the conventional technology so as to accurately grasp all the bridges, thereby ensuring the correctness of the photomask layout. 5-3 Purpose and Summary of the Invention: In the above background of the invention, the conventional measurement mask layout correction has various disadvantages that are unavoidable in the technology of bridging. A main object of the present invention is to provide a bridge that can measure various bridges that may occur. practice. A preferred embodiment of the present invention is a measurement mask layout correction

520544 V. Description of the invention (6) Bridging method. First, a mask including at least a conductive line pattern, a plurality of gate patterns connected to the conductive line pattern, and a plurality of contact pattern groups is provided. Any one of the contact pattern groups corresponds to a gate pattern and is separated from the gate pattern. Contains most contact patterns and surrounds at least the end of the corresponding gate that is not connected to the wire pattern. Then modify the mask layout and transfer the revised layout to the substrate, and form a conductor, most gates, and most contact groups on the substrate. Then, each contact group is electrically coupled to a terminal, and an electric signal is applied to the conductor to measure whether an electric signal due to bridging occurs at the terminal. Another preferred embodiment of the present invention is a photomask having a layout capable of measuring the distortion of the gate pattern caused by the photomask layout modification φ. The photomask includes at least a wire pattern, a plurality of gate patterns connected to the wire pattern, and a plurality of contact pattern groups. Any one of the contact pattern groups corresponds to a gate pattern and is separated from the gate pattern. Each of the contact pattern groups includes at least a plurality of contact patterns and surrounds at least one end of the corresponding gate that is not connected to the wire pattern. Another preferred embodiment of the present invention is a structure capable of measuring a bridge between a gate and a contact. The structure includes at least a gate on a substrate, a dielectric layer covering the substrate and the gate, and is located in the dielectric layer. A plurality of contacts that are in contact with the substrate. These contacts are separated from each other and at least part of the gates are connected to each other with a diameter of φ and a conductor layer located on the dielectric layer and electrically coupled to the contacts. 5-4 Invention Details:

520544 V. Description of the invention (7) Examination of the test base diagram. Knowing that I have received training from ^ F, I also consider that the bridge is "the first book, the test is not 0, the basic connection is available", and the wide bridge is not a C variant, the technical student is full After the two-terminal technical crystal question is completed, the first-known electric question is more and more common. No, it is better than the gate but not wider. Seeing the question and thinking about the answer to the end of the question, the step test bridge leads to the final question can be touched with a time) ^ pole figure is introduced and then touched.) Gate test F long place. Although connecting and detecting 1-4, Jiuyi's wide-width problem and &, long-energy f two-variable interrogation poles (; the most widely known gate width poles and D in the gate-starting practice, two gate-change principles Concerns lead to the crystal ends, the first place and the test to see that the electricity finally said that the poles can only be changed by a pole, and the amount of poles can be changed.

In view of this problem, the basic concept of the present invention is to relate the relationship between the simulated contact pattern and the simulated gate pattern in the conventional technology, or the relationship between the approximate contact pattern and the approximate gate pattern. The simulated contact pattern is located only in the simulated gate. Both sides of the pattern extend to simulate a contact pattern around the gate pattern. In order to detect the bridge caused by the length and width of the analog gate terminal, the analog contact pattern should preferably surround the terminal of the analog gate pattern, and at least one analog contact pattern should be adjacent to the analog gate pattern. The terminal is either an extended area located at the end of the analog gate pattern. In order to specifically explain the basic concept of the present invention, a preferred embodiment of the present invention is a mask layout that can be used to measure the gate pattern deformation caused by the mask layout correction. As shown in FIGS. 3A and 3B, this embodiment includes at least a lead pattern 31, a plurality of gate patterns 32, and a plurality of contact patterns.

Page 10 520544 V. Description of the invention (8) The plurality of contact pattern groups formed by item 3 3, and any of the contact patterns includes at least a plurality of contact patterns 3 3. As shown in FIGS. 3A and 3B, each of the gate patterns 32 is connected to the wiring pattern 31 and these gate patterns 32 are separated from each other. At the same time, these contact pattern groups are also separated from each other and any contact pattern group is not in contact with the gate patterns 32. In fact, these contact pattern groups correspond one-to-one with these gate patterns 32, and most of the contact patterns of any one of the contact pattern groups are also separated from each other, and most of the contact patterns 32 of any one of the contact pattern groups are at least The side surrounding the corresponding gate pattern 3 2 that is not in contact with the wire pattern 3 1 |. Obviously, the third diagram A shows only the case where the gate pattern 31 is changed in length or width, while the third diagram B shows only the measurement which is a mixture of the third diagram A and the conventional technology. Two methods on both sides of the gate pattern 3 2. The third diagram A clearly highlights a big difference between this embodiment and the conventional technology, while the third diagram B applies this embodiment to measuring bridges caused by deformation of any gate pattern. Further, in order to ensure that the variable length of the gate pattern 32 or the terminal widening can be accurately detected, as shown in FIG. 3C, any contact pattern group can have at least the adjacent corresponding gate pattern 3 2 At least one contact pattern 3 3 at the end. Even as shown in FIG. 3D, when the gate pattern 32 corresponding to any contact pattern group is extended along the axis 34 by one end surrounded by the contact pattern group,

520544 V. Description of the invention (9) At least one contact pattern 3 3 is located on the axis 3 4 but is not in contact with the gate pattern 3 2 Of course, this embodiment can be applied to measure many different transistor layouts at the same time, that is, The contours of different gate patterns 32 can be completely different, and different contact pattern groups can also have different numbers and distributions of contact patterns. However, as mentioned in the second D figure and related texts, in order to confirm the distance between the gate pattern 32 and the corresponding contact pattern group, contact can be avoided, or it can be confirmed that the distance between adjacent gate patterns 32 is large. The contact can be avoided from a long distance. Generally speaking, any gate pattern 32 is similar (or even equal) to the contour of other gate patterns 320, and the distribution pattern of most contact patterns 3 3 in any contact pattern group is also It is similar to the distribution pattern of most of the contact patterns 3 3 in other contact pattern groups, except that the distance between the majority of the contact patterns 3 3 in any gate pattern group and a corresponding gate pattern 3 2 is different from other gate pattern groups. The distances between most of the contact patterns 3 3 and the corresponding gate patterns 32 are different. For example, the adjacent gate pattern 3 2 of any contact pattern group may not be in contact with the wire pattern 31 at one end of the contact pattern 3 3 and the distance between the gate pattern 3 2 and any other contact pattern. The adjacent gate pattern 3 2 corresponds to one of the contact patterns 3 1 and one of the contact patterns 3 1 and the contact pattern 3 3 and the gate pattern 3 2 are not at the same distance, or any contact pattern group is located at the corresponding gate. The distance between most of the contact patterns 3 2 on both sides of the pole pattern 3 2 and the gate pattern 3 2 is corresponding to any other contact pattern group located on the gate pattern 3 2. The contact patterns 3 3 on both sides of the gate pattern and the gate pattern 3 The distance between 2 is not the same.

Page 12 520544 V. Description of the Invention Another preferred embodiment of the present invention is the application of the previous preferred embodiment: A method for measuring bridging caused by correction of a mask layout. As shown in Figure 4, it includes at least the following basic steps. As shown in the mask layout block 41, a mask having a layout is provided. This layout includes at least a wire pattern, a plurality of contact pattern groups, and a plurality of gate patterns respectively connected to the wire pattern. Any contact pattern group corresponds to a gate pattern and is separated from this gate pattern. Any contact pattern The group includes at least a plurality of contact patterns and surrounds at least one end of the corresponding gate that is not connected to the wire pattern. In brief, the layout pattern of this mask is the mask layout proposed by the previous φ preferred embodiment. In general, the mask layout will meet at least one of the following restrictions: first, at least one of the contact patterns in any of the contact pattern groups is arranged along the edge of the corresponding gate pattern, and at least one contact pattern is located at the gate The end of the pattern that is not in contact with the wire pattern. Second, the distances between the contact patterns and the corresponding gate patterns in different contact pattern groups are different. Third, the adjacent gate pattern of any contact pattern group is not in contact with the wire pattern. The distance between one of the contact patterns and the gate pattern is the gate pattern of one of the other contact pattern groups. One of the contact ends of the wire pattern_ The distance between a contact pattern and the gate pattern is different. Modify the layout as shown in the pattern correction block 4 2. In this case, a computer or the like automatically follows the rules set by the operator, such as parameters or algorithms.

Page 13 520544 V. Description of the invention (11) Correct the layout. The commonly used correction method is the optical proximity correction method. As shown in the transfer block 43, the modified layout is transferred to the substrate, and a conductive wire, a plurality of gates, and a plurality of contact groups are formed on the substrate. As shown in the coupling block 44, the contact groups are electrically coupled to a terminal. Generally speaking, the substrate and the gates are first covered with a dielectric layer, but the contact groups are not covered by the dielectric layer, and then a conductor layer is formed on the dielectric layer to be electrically coupled. These touch the terminal. As shown in measurement block 45, apply an electrical signal to the wire and measure if an electrical signal is present at this terminal. Another preferred embodiment of the present invention is a structure capable of measuring a bridge between a gate and a contact. As shown in FIG. 5A and FIG. 5B, at least the gate 5 1, the dielectric layer 5 2, and a plurality of contacts 5 3 and the conductor layer are included. Here, for simplicity, the conductor layer is not shown and only a partial cross-sectional view of the complete structure is shown. The gate electrode 51 is located on the substrate 50. The dielectric layer 5 2 covers the substrate 50 and the gate 51, but does not completely cover any one of the contacts 53. These contacts 5 3 are located in the dielectric layer 5 2 and are in contact with the substrate 50. These contacts are separated from each other and at least partially surround the gate 51. The conductor layer 54 is located on the dielectric layer 53 and electrically connects these contacts 53.

Page 14 520544 V. Description of the invention (12) Here, these contacts 5 2 are usually arranged along the edge of the gate 51, and there may be at least one contact 5 2 at one end of the gate 51, and this contact 5 2 is often It is adjacent to one end of the gate 51. Further, when one end of the gate electrode 51 surrounded by the contacts 5 2 extends along an axis, at least one contact 5 2 is located on the axis but does not contact the gate electrode 51. In addition, the gate 51 is usually electrically coupled to a power source, and the conductor layer 54 is connected to a detector. The detector here is used to detect the signal flowing from the gate 5 1 to the conductor layer 5 4 through at least one contact 5 2 bridged with the gate 5 1, such as an electrical signal, to determine whether the gate 5 1 is connected to these. Contact 5 2 occurs 0 bridge. Obviously, the structure proposed in this embodiment can be obtained by transferring the mask layout of the previous two embodiments to the substrate. At this time, the arrangement of the gate and each contact in this structure depends on the modified (such as The layout of the mask of the optical proximity correction method. However, this embodiment does not limit how this structure is formed, and this embodiment can be applied to detect any bridge caused by gate deformation. As for the bridge, it is caused by the mask layout correction or the exposure program and the etching program. Caused by an error is not the focus of this embodiment. The above are merely preferred embodiments of the present invention, and are not intended to limit the scope of patent application for the present invention; all other equivalent changes or modifications made without departing from the spirit disclosed by the present invention shall be included in the following Within the scope of patent application.

520544 on page 15 The diagrams briefly illustrate the first A to D diagrams to show the relationship between the actual desired pattern and the correction pattern, and show the situation where the correction pattern is bridged or not. Second A to F Schematic diagrams for the concepts, contents, advantages and disadvantages of the conventional technology; Figures 3A to 3D are basic schematic diagrams of a preferred embodiment of the present invention; and Figure 4 is the basic diagrams of another preferred embodiment of the present invention. Schematic diagrams; and FIGS. 5A and 5B are basic diagrams of still another preferred embodiment of the present invention. Symbols of the main parts: 10 Actually required patterns 11 Correction patterns 2 0 Element area 2 0 5 Correction element area 2 1 Gate 22 Contact 2 3 Approximate gate pattern 24 Approximate contact pattern

Page 16 520544

Schematic description on page 17 25 Substrate 26 Gate 27 Contact 28 Wire pattern 29 Simulation gate pattern 295 Simulation contact pattern 31 Wire pattern 32 Gate pattern 33 Contact pattern 34 Axis 41 Mask layout block 42 Pattern correction block 43 Transfer Block 44 Coupling Block 45 Measurement block 51 Gate 52 Dielectric layer 53 Contact

Claims (1)

520544 _Case No. 90114646_ 年月 日 __ 'Six, the scope of the patent application structure, when the end of the gate surrounded by the contacts is extended along an axis. At least one of the contacts is located on the axis but not Make contact with this gate. 7. For the structure that can measure the bridge between the gate and the contact, the configuration of the gate and the contacts depends on the layout of a photomask modified by the optical proximity correction method. 8. —A mask layout that can be used to measure the distortion of the gate pattern caused by the mask layout correction, including: a wire pattern: 麄 a plurality of gate patterns, which are separated from each other and connected— The wire pattern; and a plurality of contact pattern groups, the contact pattern groups are separated from each other and any of the contact pattern groups are not in contact with the gate patterns, and any of the contact pattern groups corresponds to a gate pattern and At least: a plurality of contact patterns separated from each other and surrounding at least one side of the corresponding gate pattern that is not in contact with the wire pattern. 9. For the mask layout that can be used to measure the distortion of the gate pattern induced by the mask layout correction in item 8 of the patent application scope, any of the gate patterns is similar to the outline of other gate patterns. 1 〇 As cited in the scope of patent application No. 9 can be used to measure the mask layout correction Page 19 520544 _ Case No. 90Π4646_ Year Month Date __ VI. The mask layout of the gate pattern deformation issued by the patent application scope. The contact patterns of any of the contact pattern groups are distributed in contact with other ones. The contact patterns of the pattern groups are distributed in a similar manner. 1 1. If the photomask layout can be used to measure the deformation of the gate pattern caused by the photomask layout correction, the contact patterns of any of the contact pattern groups and a corresponding one of the gates The distances between the patterns are different from the distances between the contact patterns of other contact pattern groups and a corresponding one of the gate patterns. 1 2. As for the mask layout that can be used to measure the deformation of the gate pattern caused by the mask layout correction according to item 8 of the patent application scope, when any one of the contact pattern groups corresponds to the gate pattern, the contact pattern group is When the enclosed end extends along an axis, at least one of the contact patterns is located on the axis but does not contact the gate pattern. Fan Li specially requested to apply for the measurement of the light exposure of the layout cover of the case of Zhengjiexiu to the Zhengjiexiu Bureau. The deformation of the layout of the cover item can be determined by the LF line guide. The response to the pole gate of the unplanned picture is close to β— 粦 is 0. The end of the picture is in touch with the contact. The connection is measured in the case of the plan. The light is measured to use the feasible item. 3 I-< Li Zhuan requested that if the adjacent graphs of the group of cases touch one another and contact the subsequent plans, the line guide will distribute the cover and Guangwei ’s case diagram to change the poles of the case. Similar Page 20 15 · —A method for measuring the layout of a photomask provides a method for bridging, including: i ^ mask '4 photomask has a layout, the layout contains at least one wire pattern; / G δ. This pattern is connected to other idle patterns ::: pole: The case is connected to the conductor most of the contact patterns Chong &. The gate pattern and the gate pattern "; Corresponds to -5 ^ ^ ^ Mouth woods are separated from each other 'any one of the contact diagrams is fortunate: contact the pattern and at least surround the corresponding-the end of the idle pole figure that is not connected to the wire pattern; _ Revise the layout; and then modify the layout Han Ming _ a guide 岣 ^. A to a substrate, and ¥,, spring, a plurality of gates and a plurality of contact groups are formed on the substrate; electrical Couple the contact groups to a terminal; and the terminal applies an electrical signal to the wire and measures whether the electrical signal appears in the terminal 6. If applying for special wealth, this = the electrical layer covers the substrate and the electrodes, but let :: Ϊ cover the electrical layer, and then form a-conductor layer in the contact with the villages Contact, by which these connections are electrically coupled Page 21 520544 _Case No. 90114646_Year Month and Date_ VI. Scope of patent application Group to this terminal. Item 5 of the measurement of the masked light of the current repair bureau-Fan Wei Fan specially asked the staff member of the bureau of Shen Ruqiao to make a corrective exercise-from Fa Shaozheng to repairing the photon near the brain. ， The law of the local law moves from the rule to the rule of the bow is being repaired to cover the light measurement item 5 1—I Fan Li specially asked to apply some of the plans along the line to touch the middle of the plan -The connection plan of the French side touches that. One end is less than one and touches in parallel, the line edge of the line chart is connected with the unpatterned pole figure, the gate is one of the items that should be measured in the masking light of the correcting position of the institute, 5 r— I Wei Fanli specially requested that the phase of Shen Ruqiao and the plan contact some of the middle phase maps of the same case. Do not touch the gates of the square poles of the case plan that are not separated from each other at the same distance. The response should be similar to β, 粦The plan of the group touches the ΥΠΊ ## in the Ren Fangyu Γ method, the alchemist's spoon is white. The connection plan of the optical bridge for the measurement of the optical measurement of the bridge in the repair station of the Caiwei Institute is shown in the figure. The gate should be connected to the adjacent picture of the case, and the contacts of the picture of the case shall be connected to some of the contacts of the picture, and the front line of the case shall be connected with the system and the distance from the tor gate. Connect to the end of the 1-contact case diagram 0 line coherent phase should not and away from the case pattern Page 22