JP3166358B2 - Mask pattern arrangement method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mask pattern arranging method for a projection exposure mask used for forming fine patterns in various solid-state devices such as semiconductor devices, superconductor devices, magnetic devices, optical integrated circuit devices, and the like. Things.

[0002]

2. Description of the Related Art Heretofore, a reduction projection exposure method has been mainly used for forming a fine pattern in a solid-state device such as a large-scale integrated circuit. One of the methods that can dramatically improve the resolving power using the above method is a method of introducing a phase difference between exposure lights that have passed through adjacent transmission regions on a mask (hereinafter, a phase shift method). There is).

[0003] In this method, for example, in the case of a repetitive pattern of an elongated transmissive region and an opaque region, one of the transmissive regions is set so that the phase difference of light passing through adjacent transmissive regions on the mask becomes approximately 180 degrees. A transparent material (hereinafter referred to as a phase shifter) for introducing a phase difference every other time is provided on the mask. A mask used in the phase shift method can be manufactured by providing a phase shifter on a predetermined transmission region of a chromium mask that has been conventionally used. Regarding this, for example, I-E-I-E, Transaction on Electron Devices, E-29, Number 12 (19)
1982) p. 1828 to p. 1836 (IEEE, T
rans. Electron Devices, ED2
9, No. 12 (1982) pp 1828-1836)
Are discussed in

In the above-described method of arranging the mask pattern of the phase shift mask, in particular, as a method of arranging the phase shifter pattern, for example, a mask pattern designer designs the size, shape, and the like of the phase shifter pattern to form the phase shifter pattern. How to place them one by one in a predetermined position,
Alternatively, as described in the 38th Applied Physics-related Lecture Lecture Book No. 2.29p-ZC-16 and the 39th Applied Physics-Related Lecture Lecture Book No. 2.30p-NA-9, There is a method of automatically arranging shifter patterns.

[0005]

In the above prior art, a designer designs a shape, a size and a position of a phase shifter pattern, arranges the phase shifter pattern on a predetermined transmission pattern, and arranges a mask pattern according to the arrangement data. Therefore, there is a problem that the mask pattern arranging process is complicated. In addition, in the method of automatically arranging the phase shifter pattern, there is a contradiction in the phase shifter pattern arrangement such that a phase shifter pattern edge is arranged in a continuous transmission region and becomes a light shielding pattern, and the automatic arrangement is performed. If it becomes impossible, the designer must design the shape, dimensions, and position in the same manner as described above and rearrange the phase shifter pattern, which also complicates the mask pattern arrangement process. there were. Also, when removing the phase shifter pattern once disposed, the phase shifter pattern must be selected from the beginning.

[0006]

SUMMARY OF THE INVENTION The above-mentioned problem is caused by a phase difference having a predetermined transmission pattern used for exposing a mask pattern on a substrate using an optical system and a phase shifter pattern for giving a phase difference to the transmitted light. In the mask pattern arranging method of the shift mask, a step of arranging a predetermined transmission pattern, a step of selecting a transmission pattern to arrange a phase shifter pattern, and executing an instruction to arrange the phase shifter pattern on the transmission pattern by executing an instruction. And a step of automatically arranging the phase shifter pattern. Further, the dimension of the phase shifter pattern can be further reduced to the transmission pattern dimension of arranging the phase shifter pattern by the phase shifter pattern arrangement accuracy in the phase shifter pattern processing step. , A mask putter with dimensions that add or subtract processing accuracy Sequence method further includes the step of selecting the transmission pattern of arranging the phase shifter pattern,
Removing the phase shifter pattern arranged on the transmission pattern by executing an instruction to remove the phase shifter pattern.

[0007]

In a phase shift mask, for example, in a line-and-space pattern in which an elongated transmission area and an opaque area are periodically arranged repeatedly, a phase shifter pattern for giving a phase difference of 180 degrees to exposure light is arranged every other transmission area. I do.

In order to manufacture such a phase shift mask, usually, a step of processing a light shielding film to form a light shielding pattern and then processing a phase shifter film is performed. Than this,
Transmission pattern (light shielding pattern) for processing light shielding film
And a step of drawing a phase shifter pattern for processing the phase shifter film are required.

Here, in the step of processing the phase shifter pattern, a predetermined phase shifter pattern is aligned and drawn on the transmission pattern formed by processing the light-shielding film. For this reason, when arranging mask patterns, it is necessary to arrange the phase shifter pattern at a predetermined position in consideration of positional accuracy, processing accuracy, and the like.

Conventionally, as a method of arranging a phase shifter pattern, for example, a mask pattern designer considers the arrangement accuracy, processing accuracy and the like, and considers the size, shape,
A method of forming positions and arranging them on a predetermined transmission pattern has been used. Alternatively, a method of arranging a predetermined phase shifter pattern using a program for automatically arranging a phase shifter pattern after arranging a predetermined transmission pattern has also been used. However, in the latter method, when a contradiction in the phase shifter pattern arrangement occurs, the initial setting for arranging the phase shifter pattern is changed and the phase shifter pattern is arranged again by using the above program, or automatically by the above program. If it cannot be arranged, it is necessary for the designer to judge and rearrange the phase shifter pattern.

Here, as an example of the contradiction in the arrangement of the phase shifter pattern, there is a case where the phase shifter pattern edge is arranged in a continuous transmission pattern area. That is, the phase difference changes by 180 degrees at the edge of the phase shifter pattern and is transferred as a light-shielding pattern, so that a continuous resist pattern corresponding to the transmission pattern area cannot be formed.

As described above, in the prior art, the phase shifter pattern is arranged and the mask pattern is arranged according to the arrangement data, so that the mask pattern arranging process is complicated. Therefore, in order to make this process simpler, the shape, size, and position of the phase shifter pattern are automatically formed by selecting a transmission pattern for arranging the phase shifter pattern and executing an instruction to arrange the phase shifter pattern. Then, a mask pattern arrangement system is constructed so as to arrange the phase shifter pattern.

Conventionally, a designer sets and arranges the shape, size, and the like of the phase shifter pattern so that the phase shifter pattern is arranged in a desired area. On the other hand, in the present invention, the transmission pattern for arranging the phase shifter pattern is selected and the phase shifter pattern can be arranged by executing the instruction for arranging the phase shifter pattern. Therefore, the arrangement of the phase shifter pattern is performed more easily. be able to.

FIG. 1 shows an example of a process flow chart. First, Step 1 of arranging a predetermined transmission pattern is performed. Next, Step 2 of selecting a transmission pattern on which the phase shifter pattern is to be arranged is performed. A plurality of transparent pattern figures may be selected. Finally, a step 3 of arranging the phase shifter pattern by executing an instruction to arrange the phase shifter pattern is performed.
By repeating the above steps, a desired phase shifter pattern can be arranged.

As described above, the mask pattern designer does not need to consider the size, shape, and the like of the phase shifter pattern for each transmission pattern in which the phase shifter pattern is arranged. It is only necessary to judge whether or not to perform the selection, execute the instruction to arrange the phase shifter pattern. Therefore, the phase shifter pattern can be efficiently arranged.

Next, further explanation will be given using a specific example. For example, let us consider a case where a transmission pattern as shown in FIG. 2 is designed and a phase shifter pattern is arranged thereon.

Here, the mask pattern is defined as a mask pattern arranging CAD (Computer Aided Design).
ng) Consider the case of arranging using a system.

First, after the transmission pattern 10 and the transmission pattern 11 for disposing the phase shifter pattern are arranged as the same transmission pattern, or during the disposition, the transmission pattern 11 for disposing the phase shifter pattern is selected on the CAD system. As a method of selecting a transparent pattern figure, for example, when a mouse is used as a pointing device in a CAD system, a mouse cursor indicating the position of the mouse is moved to a transparent pattern 1 where a phase shifter pattern is arranged.
There is a method in which the user moves into the area 1 and clicks the left mouse button to make a selection.

Here, by changing the transmission pattern display method between the selected transmission pattern and the non-selected transmission pattern, the selected state of the transmission pattern can be easily determined. For example, if the display color of the unselected transmission pattern is green and the display color of the selected transmission pattern is red, it is possible to distinguish between the different colors. Needless to say, the arrangement efficiency can be improved if the selected state can be canceled when an incorrect transmission pattern is selected.

Next, an instruction for arranging the phase shifter pattern is executed. This includes a method of inputting and executing an instruction from a keyboard, a method of selecting and executing an instruction from a menu on a screen of a CAD system, and the like.

Here, as a method of displaying that the phase shifter pattern has been arranged, a method of setting the display color of the transmission pattern in which the phase shifter pattern is arranged to a color different from the above-mentioned green and red, for example, light blue, For example, as shown in FIG. 2, the phase shifter pattern 1
For example, there is a method of superimposing 2 and displaying.

On the other hand, in order to actually arrange the phase shifter patterns, the size and shape of the phase shifter patterns to be arranged must be determined.

Here, as an example of an actual mask arrangement step, a case where a phase shifter film is laminated on a mask substrate after a transmission pattern has been determined, and this is processed into a phase shifter pattern by wet etching using a negative resist. Think.
When a silicon oxide film having a refractive index of 1.45 at an exposure wavelength of 365 nm (i-line of a high pressure mercury lamp) is used for the phase shifter, the thickness of the phase shifter is about 406 nm. If this film is wet-etched, it will be side-etched about 0.4 μm above the mask from the edge of the resist pattern.
It is necessary to increase the size of the phase shifter pattern by μm. If the amount of misalignment when writing the phase shifter pattern is 0.2 μm or less on the mask, the size must be increased accordingly.
Further, when another transmission pattern exists adjacent to the transmission pattern in which the phase shifter pattern is arranged, it is necessary to consider that the determined phase shift pattern does not affect the other transmission pattern. . this is,
For example, if the correction amount of the phase shifter pattern dimension is inappropriate, it is to prevent an unnecessary phase shifter pattern from being determined to be overlapped on an adjacent transmission pattern.

Although the parameters such as the phase shifter dimension conversion amount described above are set in advance,
If it is registered as one of the instructions or setting states of the CAD program or as an initial setting parameter of the mask pattern array, the pattern designer does not need to consider a processing error at the time of mask arrangement, and the pattern arrangement is not required. The process is simplified. Therefore, the efficiency of the pattern arrangement step can be improved.

As described above, the phase shifter pattern 12 can be easily arranged.

It is to be noted that there is also a method in which a transmission pattern in which a phase shifter pattern is arranged is selected and, at the same time, a phase shifter pattern is automatically arranged. For example, the state in which the transmission pattern is arranged (mode) and the state in which the phase shifter pattern is arranged (mode) may be set to be different states. That is, in the mode in which the transmission pattern is arranged, the transmission pattern is arranged, and in the mode in which the phase shifter pattern is arranged, the transmission pattern in which the phase shifter pattern is arranged is selected so that the phase shifter pattern is automatically arranged. Switching between these modes can be easily performed by a command of the CAD system. Further, when removing the arranged phase shifter pattern, it goes without saying that a mode for removing the phase shifter pattern may be set in the same manner.

On the other hand, when removing the phase shifter pattern once disposed, the pattern arrangement step can be simplified by removing the phase shifter pattern by the same operation. For example, when the presence or absence of the phase shifter is displayed by color as described above, the phase shifter pattern itself is set to C
Since the selection cannot be made on the screen of the AD system, the transmission pattern in which the phase shifter pattern is arranged may be selected, and the phase shifter pattern may be removed by executing a command for removing the phase shifter pattern.

[0028]

【Example】

<Embodiment 1> FIGS. 5 and 6 show the outline of the present invention.

On the first screen 61, a mask pattern of one part of the entire mask pattern is displayed. These mask patterns are composed of a plurality of transmission patterns A and B. In FIG. 5, the mouse cursor 64 is
Mouse 5 used as a pointing device
4 can be moved by human operation. Therefore,
The mouse cursor 64 is moved into the figure of the transmission pattern A where the phase shifter pattern is to be arranged, and the mouse button is clicked. This information is transmitted to the data processing unit 52, and the transmission pattern A is used by using the phase shift pattern arrangement parameters registered in the data processing unit 52 in advance.
Is performed to obtain a phase shift pattern according to. Thus, the phase shift pattern C indicated by the new hatched portion in FIG. 6 can be obtained. It is also possible to output the result to the data output unit 53. The details will be described below as an embodiment of the present invention.

An embodiment of the present invention will be described below.

A mask pattern of a phase shift mask for a 64-Mbit DRAM (dynamic random access memory) wiring pattern arranging process having a minimum design dimension of 0.35 μm was arranged. The phase shift masks arranged in this embodiment are used in an i-line (365 nm wavelength) reduction projection exposure apparatus having a reduction ratio of 5: 1. A mask pattern arranging method according to the present embodiment will be described with reference to FIG.

First, a predetermined transmission pattern is designed, and a CAD (Computer Aide) for mask pattern arrangement is used.
The transmission pattern was arranged using a (d Design) system (step 1).

Next, a transmission pattern figure on which a phase shifter pattern is to be arranged was selected on the CAD system (step 2). The CAD system used in this embodiment uses a mouse as a pointing device, and a mouse cursor is moved into a transparent pattern figure and a mouse button is clicked to select a transparent pattern in which a phase shifter pattern is arranged. There are three mouse buttons, left, middle, and right, used in this embodiment. In this embodiment, the transparent pattern figure is selected by clicking the left mouse button. Here, when the mouse cursor is not in the transparent pattern figure, the transparent pattern figure closest to the mouse cursor may be selected as the transparent pattern in which the phase shifter pattern is arranged. It goes without saying that the method of selecting the transparent pattern figure is not limited to the above.

After the above operation was repeated a plurality of times to select a plurality of transparent pattern figures, an instruction for arranging a phase shifter pattern was selected and executed from a menu on the screen to arrange the phase shifter pattern (step 3). For this instruction selection, the mouse cursor was moved to a portion of the menu on the screen indicating the instruction for arranging the phase shifter pattern, and the mouse button was clicked for selection. The method of inputting the command is not limited to this, and a similar command may be input from a keyboard, for example. By the above operation, the phase shifter pattern is automatically arranged on the transmission pattern selected above.

Here, for the phase shifter pattern arranged as described above, it is necessary to consider an arrangement error, a dimensional error, an error generated at the time of etching, and the like when determining the phase shifter pattern.

The arrangement parameters for determining the size and shape of the phase shifter pattern arranged above may be set in advance under the following conditions. For example, the correction amount differs depending on the method of etching the phase shifter film, for example, anisotropic dry etching or wet etching, depending on whether the resist used for processing the phase shifter pattern is a negative type or a positive type. In addition, it is necessary to consider an arrangement error (arrangement accuracy) and a dimensional error (dimensional accuracy) at the time of drawing and determining the phase shifter pattern. Furthermore, since the phase shifter film thickness changes depending on the wavelength of the exposure light used at the time of pattern transfer, the material of the phase shifter film, and the like, it is necessary to consider that these influence the processing accuracy.

In this embodiment, when a silicon oxide film having a refractive index of 1.45 for an exposure wavelength of 365 nm is used as a phase shifter, the optimum value of the phase shifter film thickness is 406 nm.
m. When a negative resist and a wet etching method are used for processing the phase shifter film, the resist pattern size is increased by about 0.4 μm on one side and about 0.8 μm in width in consideration of side etching of about 406 nm by wet etching. . In addition, since the maximum displacement of the superposition of the phase shifter pattern drawing was 0.2 μm, the width was further increased by 0.4 μm. Further, the width is further increased by 0.2 μm in consideration of processing variations at the time of processing the phase shifter pattern. As described above, the dimension of the resist pattern is set to be 1.4 μm larger than the dimension of the transmission pattern on which the phase shifter pattern is arranged. Since the dimensions described above are dimensions on the mask, considering the reduction ratio, the dimension of the phase shifter pattern may be enlarged by 0.28 μm as compared with the dimension of the transmission pattern. In addition,
Here, a case is considered where the pattern arrangement is designed with dimensions on the substrate to which the mask pattern is transferred.

If the layout parameters such as the phase shifter dimension conversion values as described above are registered as, for example, one of the command menus of the CAD system or as the initial setting parameters of the pattern layout, the pattern designer can use the mask. Since parameters can be easily set without having to consider processing errors or the like at the time of arrangement, the pattern arranging step is further simplified. Therefore, the efficiency of the pattern arrangement step can be increased. In the present embodiment, before arranging the first phase shifter pattern, a command for inputting the setting parameters of the CAD system is input and executed from the keyboard to design the above arrangement parameters.

By using the mask pattern data designed as described above, the desired phase shift mask can be arranged. Further, by using the arranged phase shift masks, the semiconductor elements could be arranged at a high yield.

<Embodiment 2> In this embodiment, as described in Embodiment 1, fifteen transmission pattern figures on which phase shifter patterns are arranged are selected (Step 2). At this point, one of the figures that became the transparent pattern figure to be selected was selected by mistake, so move the mouse cursor to the incorrectly selected transparent pattern figure on the screen and click the left mouse button. To release the selection (Step 4). Next, as described in the first embodiment, five more transmission pattern figures on which the phase shifter patterns are arranged are selected,
An instruction to arrange the phase shifter pattern was selected from a menu on the screen and executed (step 3). By the above operation,
The phase shifter pattern was automatically placed on the transmission pattern selected above. By using the mask pattern data designed as described above, a desired phase shift mask could be arranged.

Embodiment 3 In this embodiment, after arranging transmission patterns as described in Embodiment 1, a transmission pattern figure on which a phase shifter pattern is arranged is selected on a CAD system. In this embodiment, an area including a transmission pattern in which a phase shifter pattern is arranged is set on the screen of the CAD system, and a transmission pattern figure included in this area is selected. Here, there are various methods for setting a region including a transmission pattern in which a phase shifter pattern is arranged. For example, in the present embodiment, a command for designating a region including the phase shifter pattern is selected from a menu on the screen, a rectangular region is set by designating two diagonal vertices of the rectangular region, and the rectangular region is set in the rectangular region. The included transmission patterns were selected. The method of designating the area is not limited to this, and various other methods such as a method of setting the area by designating the vertices of the polygonal area can be used.

Although the phase shifter patterns were arranged as described above, it was found that one phase shifter pattern was incorrectly arranged. Then, the mouse cursor was moved into this transparent pattern figure on the screen and the left mouse button was clicked on to select the transparent pattern in which the phase shifter pattern was erroneously arranged (step 5). Next, an instruction to remove the arranged phase shifter pattern was selected and executed from a menu on the screen (step 6). Through the above operation, one phase shifter pattern that was incorrectly arranged was removed.

By using the mask pattern data designed as described above, a desired phase shift mask could be arranged.

<Embodiment 4> 6 having a minimum design size of 0.3 μm
A mask pattern of a phase shift mask for a 4 megabit DRAM (dynamic random access memory) wiring pattern arranging process was arranged. The phase shift mask arranged in this embodiment is a KrF excimer laser (wavelength 2
48 nm) used in a reduction projection exposure apparatus.

First, the CAD system is set to a mode for arranging transmission patterns, and a predetermined transmission pattern is designed.
The transmission pattern was arranged using a CAD system for mask pattern arrangement.

Next, the CAD system was switched to a mode in which a phase shifter pattern was arranged, and a transmission pattern figure in which the phase shifter pattern was arranged was selected on the CAD system. The CAD system used in this embodiment uses a mouse as a pointing device. The mouse cursor is moved into the transparent pattern figure and the left button of the mouse is clicked to select a transparent pattern in which the phase shifter pattern is to be arranged. Here, it goes without saying that the method of selecting the transparent pattern figure is not limited to the above. Further, the mode can be switched easily by a command of the CAD system. When the arranged phase shifter pattern is removed, a mode for removing the phase shifter pattern may be set in the same manner.

A phase shifter pattern is automatically arranged for the transmission pattern selected above. The above operation was repeated a plurality of times to arrange a desired phase shifter pattern on a desired transmission pattern.

Here, the phase shifter pattern arranged above has a phase shifter pattern size larger than the transmission pattern size in consideration of an arrangement error at the time of forming the phase shifter pattern, a dimensional error, an error at the time of etching, and the like. It goes without saying that the arrangement must be small.

By using the mask pattern data arranged as described above, the desired phase shift mask can be arranged.

[0050]

As described above, according to the present invention, the mask pattern arranging step can be simplified, and the arrangement efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a process flowchart showing a process flow according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a mask pattern arrangement according to the present invention.

FIG. 3 is a process flowchart showing a process flow according to an embodiment of the present invention.

FIG. 4 is a process flowchart showing a process flow according to an embodiment of the present invention.

FIG. 5 is a diagram showing an outline of the present invention.

FIG. 6 is a diagram showing an outline of the present invention.

[Explanation of symbols]

1: a step of arranging a transmission pattern, 2: a step of selecting a transmission pattern in which a phase shifter pattern is arranged, 3: a step of arranging a phase shifter pattern, 4: a selection of a transmission pattern in which a phase shifter pattern is arranged is released. 5: a step of selecting a transmission pattern in which a phase shifter pattern is erroneously arranged, 6: a step of removing the phase shifter pattern, 10: a transmission pattern, 11: a transmission pattern in which a phase shifter is arranged, 12: a phase shifter pattern, 51: display unit, 52: data processing unit, 53: data output unit, 54: mouse, 61: first screen, 62: second screen, 63: third screen, 64: mouse cursor.

Claims (8)

(57) [Claims] 1. A CAD system comprising: a display screen for displaying a mask pattern; a pointing device for designating a specific pattern on the display screen; and a data processing unit for arranging a phase shifter pattern on the pattern designated by the pointing device. In a method of arranging mask patterns using a system, a step of arranging a transmission pattern on the display screen, and a step of selecting a transmission pattern for arranging an inner phase shifter pattern of the transmission pattern by designating the same with the pointing device, Arranging a phase shift pattern on the selected transmission pattern, wherein the selected transmission pattern has a different display method from the non-selected transmission pattern on the display screen and can be determined. A method of arranging a mask pattern as a feature. 2. The method according to claim 1 , wherein the size of the phase shift pattern is determined using an arrangement parameter registered in advance in consideration of an arrangement error, a dimensional error, and a processing error of the phase shifter pattern. The method for arranging the mask patterns described in the above. 3. The mask pattern arrangement method according to claim 1, wherein a part of the mask pattern is displayed on the display screen. 4. The method according to claim 1, wherein a color display is used as the display method, and a color displayed by a selected transmission pattern and a non-selected transmission pattern is changed. Arrangement method of mask pattern. A step wherein selecting the transmission pattern of placing the inner phase Shifutapatan of the transmission pattern, and the step of disposing the phase shift pattern based on the placement parameters of the phase shift pattern to said selected transmission pattern on the The method according to any one of claims 1 to 4, wherein the method is performed simultaneously. CAD with 6. A display screen for displaying a mask pattern, and a pointing device for indicating a specific pattern of the display screen, and a data processing unit to place the phase Shifutapatan the pointing device at the indicated pattern on In a method of manufacturing a phase shift mask using an array of patterns obtained by using a system, a step of arranging a transmission pattern on the display screen, and a transmission pattern for arranging an inner phase shifter pattern of the transmission pattern is indicated by the pointing device. The masking pattern obtained through the step of selecting by performing, and arranging a phase shifter pattern on the selected transmission pattern, wherein the transmission pattern is formed in an opaque region on a mask substrate, Forming the phase shifter pattern on the selected transmission pattern Wherein the selected transmission pattern has a different display method from the non-selected transmission pattern on the display screen and can be distinguished from the selected transmission pattern. 7. A method of manufacturing a phase shift mask according to claim 6, wherein the said light shielding region that chromium is provided. Wherein said phase Shifutapatan the method of manufacturing a phase shift mask according to claim 6 or 7, characterized in that it is formed of a silicon oxide film.