JP2004012932A - Method for manufacturing mask, exposure method and method for manufacturing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for comparatively simply setting mask patterns and an illuminating condition to improve resolution. <P>SOLUTION: The method for manufacturing a mask suitable for an exposing method for illuminating the mask on which a required pattern and an auxiliary pattern whose size is smaller than the required pattern by a plurality of sorts of light so that the required pattern is resolved and the resolution of the auxiliary pattern is suppressed and projecting light passed through the mask to an object to be exposed through a projecting optical system is provided with a step for setting the dimensions of the required pattern and a step for controlling the dimensions of the required pattern in accordance with the characteristics of resist applied to the object to be exposed. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a mask pattern and a method of setting optimum illumination conditions for the mask pattern, and in particular, relates to a desired pattern and an auxiliary pattern or a dummy pattern having a smaller dimension than the desired pattern (in the present application, both are used). The mask is arranged by illuminating the mask with a plurality of types of light so that the desired pattern is resolved and the resolution of the auxiliary pattern is suppressed. The present invention relates to a method for setting a mask pattern and an illumination condition suitable for an exposure method for projecting transmitted light onto an object to be exposed via a projection optical system.
[0002]
[Prior art]
The projection exposure apparatus is used when manufacturing devices such as ICs, LSIs, and liquid crystal panels using photolithography technology. In order to obtain a smaller resolution with a projection exposure apparatus, a method of shortening the exposure wavelength of the projection exposure apparatus and increasing the numerical aperture (NA) of the projection optical system has been generally adopted.
[0003]
Generally, the resolving power is improved by shortening the wavelength of the exposure light and increasing the numerical aperture. However, the projection exposure apparatus has a pattern that is easy to resolve and a pattern that is difficult to resolve due to its properties. Generally, it is said that a line pattern (hereinafter, L / S pattern) is easier to resolve than a contact hole pattern (hereinafter, C / H pattern). Therefore, the width of the C / H pattern is generally larger than the width of the L / S pattern used for a semiconductor chip or the like. From the above, it can be said that a problem in miniaturization of the photolithography technique is creation of a fine C / H pattern.
[0004]
Conventionally, attempts have been made to change the transfer performance of a pattern by inserting a dummy pattern into a desired C / H pattern. However, the dummy pattern has been inserted mainly to improve the depth of focus. Further, the effective light source shape of the illumination system used in this case has conventionally been a so-called annular shape or quadrupole shape.
[0005]
[Problems to be solved by the invention]
The present inventor has discovered that not only the depth of focus but also the resolution can be improved depending on the method of inserting the dummy pattern, and that the optimal illumination system in that case is not annular illumination or quadrupole illumination. In particular, according to the inventor's experience, quadrupole illumination has a k corresponding to the pattern half pitch of the mask pattern in which the dummy pattern is inserted. ₁ Is almost useless if is less than or equal to 0.25 × √2. Where k ₁ Is calculated using the resolution R, the numerical aperture NA, and the wavelength λ of the exposure light source. ₁ = R · NA / λ. Further, in the prior art, a dummy pattern is inserted only when a desired pattern has a certain period. However, not all desired patterns have a certain period in an actual mask pattern. Therefore, wide adaptation cannot be expected with the prior art.
[0006]
Therefore, an object of the present invention is to provide a method for setting a mask pattern and an illumination condition relatively easily in order to improve resolution.
[0007]
[Means for Solving the Problems]
The method for manufacturing a mask according to the present invention is a method for manufacturing a mask, in which a desired pattern and an auxiliary pattern having a smaller size than the desired pattern are arranged, wherein the desired pattern is resolved and the auxiliary pattern is resolved. A mask manufacturing method suitable for an exposure method of irradiating with a plurality of types of light and projecting light having passed through the mask onto an object to be exposed via a projection optical system so that an image is suppressed. In one embodiment, the method for manufacturing a mask includes the steps of: setting a dimension of the desired pattern; and adjusting the dimension of the desired pattern according to characteristics of a resist applied to the object to be exposed. It is characterized by having. According to such a method, first, the dimensions of a desired pattern are set in consideration of the dimensions to be formed on the object to be exposed and the magnification of the projection optical system, and then the dimensions are determined in consideration of the characteristics of the resist. Fine tune. When the characteristic of the resist is the contrast of the resist, the adjusting step may adjust the dimension of the desired pattern within a range of about 0.85 times to about 1.15 times. The characteristic of the resist may be a threshold of the resist, and the adjusting may adjust the dimension of the desired pattern within a range of about 0.85 times to about 1.15 times. The adjusting may be adjusted by referring to a database that defines a relationship between the characteristics of the resist and the dimensions of the desired pattern.
[0008]
A mask manufacturing method according to another embodiment is a method suitable for the above-described exposure method, wherein a step of setting a size of the desired pattern, a mask error enhancement factor and a line width error for the size of the desired pattern are performed. And determining the minimum pitch so that at least one of the minimum pitches falls within an allowable range by utilizing a relationship between at least one of the mask patterns and a minimum pitch of the mask pattern.
[0009]
A method for manufacturing a mask according to another embodiment is a method suitable for the above-described exposure method, wherein the step of setting the dimension of the desired pattern, the step of setting the dimension of the auxiliary pattern, Using at least one of a mask error enhancement factor, a line width error, a depth of focus, a location error, a size error, and an exposure amount with respect to the dimension of the auxiliary pattern, and at least one of the dimensions is within an allowable range. Adjusting the size of the auxiliary pattern. The adjusting step may be changed within a range of 10% of a size of the auxiliary pattern. The adjusting step may reduce a size of the auxiliary pattern to improve the mask error enhancement factor, the location error, or the size error. The adjusting may include increasing a size of the auxiliary pattern to improve the line width error, the depth of focus, or the exposure amount.
[0010]
A method for manufacturing a mask according to another embodiment is a method suitable for the above-described exposure method, wherein a dimension of the desired pattern is set to a dimension in a second direction orthogonal to the first direction in a first direction. Setting the length of the auxiliary pattern to be longer than that of the auxiliary pattern in the first direction, and setting the length of the auxiliary pattern to be longer in a second direction orthogonal to the first direction in the first direction. The desired pattern may have a rectangular shape, and the auxiliary pattern may have a rectangular shape.
[0011]
A mask manufacturing method according to another embodiment is a method suitable for the above-described exposure method, and in a case where a plurality of types of desired patterns having different shapes are present, the auxiliary patterns having two or more types having different shapes are arranged. It is characterized by the following.
[0012]
A mask manufacturing method according to another embodiment is a method suitable for the above-described exposure method, wherein the desired patterns are formed in first and second regions separated by a distance that does not interfere with each other. And setting the auxiliary pattern as a different pattern for each of the first and second regions. The minimum pitch of the first area may be smaller than the minimum pitch of the second area, and the step of setting the desired pattern may increase a size of a desired pattern in the second area. An exposure method characterized by illuminating a mask manufactured by such a method with an illumination system optimized for the minimum pitch of the first region also constitutes another aspect of the present invention. The step of forming the desired pattern may correct a shape of the desired pattern in the first region. An exposure method characterized by illuminating the mask manufactured by such a method with an illumination system optimized for the minimum pitch of the second region also constitutes another aspect of the present invention.
[0013]
A method of manufacturing a mask according to another embodiment is a method suitable for the above-described exposure method. In a case where two inserted auxiliary patterns overlap or are adjacent to each other, instead of providing the two auxiliary patterns, One auxiliary pattern having a center of gravity of the two auxiliary patterns as a center of gravity is arranged.
[0014]
A method for manufacturing a mask according to another embodiment is a method suitable for the above-described exposure method, wherein the resolution is R, the wavelength of the exposure light is λ, the numerical aperture of the projection optical system is NA, k ₁ = R / (λ / NA), and the minimum vertex interval between two inserted dummy patterns is k ₁ When the converted value becomes 0.20 or less, one auxiliary pattern having a center of gravity of the center of gravity of the two auxiliary patterns is arranged instead of providing the two auxiliary patterns.
[0015]
A mask manufacturing method according to another embodiment is a method suitable for the above-described exposure method, wherein the desired pattern is formed by a periodic pattern having at least two contact holes aligned in any one of two orthogonal directions. Classifying into an isolated pattern having no other contact holes aligned in any of the two orthogonal directions; and for the periodic pattern, based on a cycle as an interval between the at least two contact holes. And arranging the auxiliary pattern in the direction in which the auxiliary patterns are aligned, and a second step of arranging the auxiliary pattern on the isolated pattern based on an arbitrary period.
[0016]
Arranging the auxiliary pattern with respect to the periodic pattern includes determining a size of the auxiliary pattern based on a minimum pitch of the desired pattern; and setting the auxiliary pattern based on the cycle and a hole diameter of the desired pattern. Determining the period of the pattern. The step of determining the size of the auxiliary pattern includes: setting a minimum half pitch of the desired pattern to a resolution of R, a wavelength of exposure light to λ, a numerical aperture of the projection optical system to NA, k ₁ = K when R / (λ / NA) ₁ Determining whether the value is smaller than 0.25 × √2, and setting the size of the auxiliary pattern to a predetermined ratio of the desired pattern when determining that the size is smaller than 0.25 × √2 When the determination step determines that the size is not small, the size of the auxiliary pattern is set to k. ₁ Setting the size to a value equivalent to 0.25 or more in conversion. The predetermined ratio may be 70% or more and 85% or less.
[0017]
The steps of determining the cycle of the auxiliary pattern include: a first determination step of determining whether the hole diameter of the desired pattern is smaller than a first threshold; and a first determination step of less than the first determination step. If the determination is made, a step of terminating abnormally may be further provided. The first threshold value may be not less than 0.25 and not more than 0.25 × √2. A second determining step of determining whether the hole diameter of the desired pattern is equal to or greater than the first threshold and equal to or less than a second threshold; If the determination step 2 determines that the period is not less than the first threshold and not more than the second threshold, the period of the periodic pattern is R, the wavelength of the exposure light is λ, and the numerical aperture of the projection optical system is NA. , K ₁ = K when R / (λ / NA) ₁ A third judgment step of judging whether or not the periodic pattern is equal to or more than a third threshold value; and Arranging the auxiliary pattern in a cycle. A step of arranging the auxiliary pattern according to a value obtained by dividing the cycle of the periodic pattern by a predetermined number when the third determining step determines that the auxiliary pattern is equal to or greater than the third threshold value. The first threshold value is 0.25 or more and 0.25 × √2 or less, the second threshold value is 0.25 × √2 or more and 0.5 or less, and the third threshold value is 1.0 or more１．０. It may be 2 or less.
[0018]
When the second determining step determines that the period is not less than the first threshold and not more than the second threshold, the period of the periodic pattern is set to k ₁ A fourth determination step of determining whether or not the auxiliary pattern is equal to or greater than a fourth threshold, and inserting the auxiliary pattern when determining that the fourth step is equal to or greater than the fourth threshold. You don't have to. When the second determining step determines that the period is not less than the first threshold and not more than the second threshold, the period of the periodic pattern is set to k ₁ In the case of conversion in the above, a fourth determination step of determining whether or not the fourth threshold value or more, and if it is determined that the fourth step is not the fourth threshold value or more, in the cycle of the periodic pattern Arranging the auxiliary pattern. The first threshold is 0.25 or more and 0.25 × √2 or less, the second threshold is 0.25 × 以上 2 or more and 0.5 or less, and the fourth threshold is 0.5 × √. It may be 2 or more and 1.0 or less. The step of arranging the auxiliary pattern with respect to the isolated pattern includes: a step of determining whether a periodic pattern exists within a predetermined distance from the isolated pattern; and a step of determining whether the determination step exists. Arranging the auxiliary pattern in accordance with the period of the periodic pattern, and arranging the auxiliary pattern with a half-pitch dimension of the isolated pattern when it is determined that the determining step does not exist. And a step.
[0019]
The periodic pattern includes a first periodic pattern having periodicity in a first direction, and a second pattern having periodicity in a second direction parallel to the first direction. Each of the contact holes forming the second periodic pattern has a contact hole between the first and second periodic patterns when there is no other contact hole in a direction perpendicular to the first and second directions. The method may further include arranging the auxiliary pattern using the first and second intervals in a direction perpendicular to the first and second directions as a cycle. Any of the contact holes forming the periodic pattern may be located between the periodic pattern and the isolated pattern when there is no other contact hole in a second direction perpendicular to the first direction in which the periodic pattern has periodicity. And arranging the auxiliary pattern by using, as a cycle, an interval between the first direction with respect to the second direction and a third direction parallel to the first direction and passing through the isolated pattern. May have.
[0020]
A method for manufacturing a mask according to another embodiment is a method suitable for the above-described exposure method, wherein a part of the desired pattern is arranged at each grid-like point in a predetermined area, and If the number of patterns at a distance of twice or less the distance between the lattice points is 3 or less and the patterns are displaced within 20% of points on the lattice, the displaced pattern is in a lattice shape. The auxiliary pattern is inserted assuming that the auxiliary pattern is arranged.
[0021]
The database as one aspect of the present invention is a database used for setting a mask pattern suitable for the above-described exposure method, and when the characteristics of the resist applied to the object to be exposed are input, the desired A bias to be applied to the dimension of the pattern is displayed.
[0022]
The database of another embodiment is a database used for setting a mask pattern suitable for the above-described exposure method, and includes a tolerance of at least one of a mask error enhancement factor and a line width error, and a dimension of the desired pattern. Is input, the minimum pitch of the mask pattern is displayed.
[0023]
The database of still another embodiment is a database used for setting a mask pattern suitable for the above-described exposure method, and includes a mask error enhancement factor, a line width error, a depth of focus, a location error, a size error, and an exposure amount. When at least one of the allowable range and the dimensions of the desired pattern are input, the dimensions of the auxiliary pattern are displayed.
[0024]
In the above-described exposure method according to another aspect of the present invention, the step of adjusting a coherence factor of an illumination system illuminating the mask such that the depth of focus falls within an allowable range, or the depth of focus falls within an allowable range. Thus, the method includes a step of exposing a plurality of times while moving the object to be exposed in the optical axis direction. The mask may have a dimension of a pattern adjacent to the desired pattern in the auxiliary patterns smaller than dimensions of other auxiliary patterns.
[0025]
A database according to still another embodiment is a database used for setting a mask pattern suitable for the above-described exposure method, and is characterized by expressing a relationship between a type of a mask and a contrast or a line width error.
[0026]
A program for executing the above-described mask manufacturing method and a mask created by the above-described method also constitute another aspect of the present invention. A device manufacturing method including a step of exposing the object to be exposed using the mask and a step of performing a predetermined process on the object to be exposed also constitutes another aspect of the present invention. The claims of the device manufacturing method having the same operation as that of the above-described mask manufacturing method extend to the device itself, which is an intermediate and final product. Such devices include semiconductor chips such as LSI and VLSI, CCDs, LCDs, magnetic sensors, thin-film magnetic heads, and the like.
[0027]
Further objects and other features of the present invention will become apparent from preferred embodiments described below with reference to the accompanying drawings.
[0028]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Hereinafter, what is assumed as an exposure apparatus is an exposure apparatus in which the wavelength of the light source is 248 nm and the numerical aperture of the projection optical system is 0.73, unless otherwise specified. The projection exposure apparatus generally uses reduced projection exposure. In the case of reduced projection exposure, the pattern size and mask pattern to be created differ by a magnification depending on the exposure apparatus. Since the magnification of the exposure apparatus varies depending on the model, in the following, the pattern size on the mask is converted into the dimension on the wafer. For example, when the magnification of the projection exposure apparatus is 0.25, when a pattern of 120 nm is to be created, a pattern of 480 nm must actually be created on the mask. In the case of 20 times, a 600 nm pattern must be formed on the mask. However, in the following, the size of the mask pattern is converted to the size on the wafer to eliminate the distinction for these situations, and is referred to as a 120 nm pattern. In addition, although each pattern includes one or a plurality of contact holes, in the present application, the term “pattern” may mean a part of the pattern or one contact hole.
[0029]
FIG. 1 is a flowchart for explaining a method for setting a mask pattern and illumination conditions according to the present embodiment. An exposure method by forming a mask in which a desired pattern and a dummy pattern smaller than the desired pattern are arranged and resolving only the desired pattern portion is referred to as an exposure method I.
[0030]
Referring to FIG. 1, first, according to a pattern to be formed after exposure, the transmittance of a portion where there is no desired pattern is set to 0, and the transmittance of a portion where a desired pattern is located is set to 1 to create data of a corresponding desired pattern. (Step 1002). Here, the dimensions and arrangement of the desired pattern to be exposed on the wafer are determined.
[0031]
Next, the type of mask (for example, binary mask, halftone mask, phase shift mask, etc.) to be used after setting the desired pattern is determined (step 1004). Here, a mask-specific database appearing in a seventh embodiment described later with reference to FIGS. 14 and 15 is used.
[0032]
Next, a dummy pattern to be inserted and an illumination method are determined for the data of the desired pattern (step 1006).
[0033]
The dimensions of the dummy pattern are determined with reference to FIG. If the desired pattern is a periodic pattern, the period of the dummy pattern is determined with reference to FIG. If the desired pattern is an isolated pattern, the period of the dummy pattern is determined with reference to FIG. The periodic pattern is a pattern having at least two contact holes aligned in any one of two orthogonal directions. The isolated pattern is a pattern including only one contact hole and having no other contact holes aligned in any of the two orthogonal directions. Embodiments 11 and 14 to be described later generalize how to arrange dummy patterns particularly when a desired pattern is not arranged at each grid point.
[0034]
In the determination of the lighting method, a calculation is performed, the lighting conditions are checked, and if the lighting conditions are created within predetermined design rules, the operation is terminated. If the lighting conditions are not created within predetermined design rules, an operation step is performed. Is repeated a predetermined number of times. If the creation of the lighting conditions is not determined to be successful within the predetermined number of times, the process ends as abnormal. The determination of the alternative lighting method is performed by extracting the database (table data), checking the lighting conditions, and ending if the lighting conditions are created in the predetermined design rules, and creating the lighting conditions in the predetermined design rules. If not, returning to the calculation step is repeated a predetermined number of times. If the creation of the lighting conditions is not determined to be successful within the predetermined number of times, the process ends as abnormal.
[0035]
Step 1006 is also used to correct the dummy pattern and / or the illumination method when the processing is returned from step 1020 described below.
[0036]
Next, a desired pattern is checked (step 1008). Here, it is determined whether or not a desired pattern is formed with high accuracy based on mask pattern data and illumination condition data created by inserting a dummy pattern into the desired pattern. That is, in step 1008, it is determined whether or not only the desired pattern is accurately resolved without resolving the dummy pattern. The degree of accuracy is determined according to a certain standard, but may be determined by the user. If there are a plurality of dummy patterns or illumination condition candidates in which only a desired pattern can be resolved, it is preferable to select the one having a larger contrast and the one having a smaller error variation in line width (CD: critical dimension).
[0037]
If step 1008 determines that the desired pattern is not resolved, a correction is made (step 1010). In the correction, a desired pattern, a dummy pattern, and the like are corrected. The dummy pattern and other corrections are mainly performed in step 1006 which is fed back in step 1020 described later, but may be performed in step 1010 for fine adjustment.
[0038]
Correction of a desired pattern will be described in optical proximity correction and Example 1 described later. Optical proximity correction (hereinafter referred to as OPC: Optical Proximity Correction) is a technique for enabling transfer of a desired pattern with high accuracy.
[0039]
For example, as shown in FIG. 24A, if the size of a desired pattern shown by a solid line is larger than a predetermined value shown by a dotted line, as shown in FIG. 24B, OPC is performed to reduce the size of the desired pattern. 24C, if the size of the desired pattern indicated by the solid line is smaller than the predetermined value indicated by the dotted line, as shown in FIG. 24D, the OPC is performed to increase the size of the desired pattern as shown in FIG. Insert OPC is effective, for example, in Example 12 described later.
[0040]
Changing the size and shape of the dummy pattern also leads to correction of a desired pattern. For example, when the size of the desired pattern is smaller than the desired value, the size of the dummy pattern arranged around the desired pattern is increased or the cycle is reduced. Conversely, when the size of the desired pattern is larger than a predetermined value, there are methods such as reducing the size of the dummy pattern arranged around the desired pattern or increasing the period.
[0041]
Changing the number of holes in the dummy pattern arranged around the desired pattern also leads to correction of the desired pattern. For example, the light amount of the desired pattern can be reduced by reducing the number of holes of the dummy pattern arranged around the desired pattern, and the light amount of the desired pattern can be increased by increasing the number of holes of the dummy pattern.
[0042]
Changing the illumination system leads to correction of a desired pattern. For example, in a binary mask, illumination by an illumination system having an effective light source distribution shown in FIG. 7A is effective. However, by changing the size of the light shielding area (a and b in the figure), the hole shape is rounded. And the resolution and the depth of focus can be changed.
[0043]
The correction of the dummy pattern will be described in detail in Examples 2 to 6, 8 to 10, and 13 described later. Other corrections include the minimum pitch, the type of mask, the threshold at which the photoresist applied to the object is exposed, the threshold of the photoresist changed by changing the photoresist applied to the object, and the effective light source. May be changed. For example, since a phase shift mask has the effect of extending the depth of focus and slightly reducing the variation in line width error, it is also effective to change the phase shift mask when the depth of focus is insufficient with a binary mask.
[0044]
After the correction, the desired pattern is checked again (step 1012). Similarly to the check in step 1008, it is determined whether or not only the desired pattern can be accurately resolved without the dummy pattern being resolved. If the check in step 1012 still does not pass, the process of returning to step 1010 is repeated a predetermined number of times (kmax) (steps 1014 and 1016). When the predetermined number of times kmax is exceeded, the process of returning to step 1006 is repeated a predetermined number of times jmax (steps 1018 and 1020).
[0045]
If the check in step 1008 or 1012 does not pass, the process ends as abnormal (step 1022). If the check at step 1008 or 1012 finally passes, fine adjustment of the diameter of the dummy hole is made (step 1024), and finally, the mask pattern data and the illumination conditions are determined (step 1026). Step 1024 may be performed in step 1006 or step 1010 which returns from step 1020.
[0046]
Since most of the method shown in FIG. 1 is computer-executable, the creator only has to create and input a pattern to be finally formed on the resist, and the subsequent generation of mask pattern data and illumination conditions is as described above. Since the steps can be automatically performed by a computer, optimal mask patterns and illumination conditions can be efficiently created even in the design of a large-scale semiconductor integrated circuit. Even if a huge amount of mask data is not processed in a lump, the mask pattern data can be divided and processed, and a method of combining the mask data at the end can be used.
[0047]
It is assumed that the desired pattern 21 is a contact hole (hereinafter, C / H) pattern shown in FIG. 2A, and that p is 220 nm in FIG. FIG. 2B shows a hole number for identifying each hole, which is used in FIG. 15 described later. Dummy holes 32 are inserted vertically and horizontally at a half pitch of 110 nm to form a mask pattern 30 as shown in FIG. That is, the mask pattern 30 shown in FIG. 3 has the same desired pattern 31 and the dummy pattern 32 as the desired pattern 21. At this time, the size of each dummy hole 32 is 90 nm.
[0048]
It is assumed that the illumination system has an effective light source having the shape shown in FIGS. 4 and 7A and 7B. The quadrupole illumination shown in FIG. 4 and the illumination shown in FIGS. 7A and 7B are typically provided by an aperture stop arranged immediately after the exit surface of an optical integrator in an illumination optical system of an exposure apparatus (not shown). Is embodied as a shape. The aperture stop is provided at a position conjugate with the pupil plane of the projection optical system of the exposure apparatus (not shown), and the aperture shape of the aperture stop corresponds to the effective light source shape of the pupil plane of the projection optical system. Therefore, the effective light source shape shown in FIG. 4 is embodied as, for example, an aperture stop 40 having a light transmitting portion 41 and a light shielding portion 42, and the effective light source shape shown in FIG. The effective light source shape shown in FIG. 7B is embodied as an aperture stop 70B having a light blocking part 73 and a light transmitting part 74.
[0049]
FIG. 5A shows the result of an exposure experiment performed on the mask pattern 30 shown in FIG. 3 by the illumination system using the quadrupole illumination shown in FIG. As understood from FIG. 5A, the desired pattern 21 is not resolved well.
[0050]
On the other hand, when an exposure experiment was performed on the mask pattern 30 shown in FIG. 3 using an illumination system having a cross-shaped light shielding portion shown in FIG. 7A, a desired pattern was obtained as shown in FIG. 21 was clearly resolved.
[0051]
The illumination system in FIG. 7A can be divided into two as shown in FIGS. 6A and 6B. Of these, the four portions 61 shown in FIG. 6A have the effect of having a resolution, and the four portions 62 shown in FIG. 6B have the effect of suppressing the resolution of dummy holes. I found out. For this reason, in the present application, light emitted from the illumination system as shown in FIG. 7A is referred to as a plurality of types of light. Similarly, the illumination system shown in FIG. 7B can be divided into a portion contributing to the resolution and a portion contributing to the suppression of the dummy hole resolution. Of course, it goes without saying that the plurality of types of light are not limited to the light provided from the illumination system of FIGS. 7A and 7B. From the above, it is understood that if the dummy pattern 32 is inserted around the desired pattern 21 and the illumination system has a cross-shaped light shielding portion, the desired pattern 21 is resolved.
[0052]
In this example, since the desired pattern is located on the lattice-like points, it can be seen that dummy holes should be inserted intuitively and periodically. However, the pattern in this example is not very realistic.
[0053]
Actually, arbitrary patterns exist, and a method of inserting a dummy pattern into those patterns must be considered. Further, it is better to consider the characteristics of the resist and the characteristics of the dummy pattern. The following examples will introduce what the inventor has discovered assuming many patterns and many real conditions.
[0054]
【Example】
Embodiment 1
It is assumed that p = 220 nm in the desired pattern 21 shown in FIG. Since the desired pattern is arranged at the lattice points, an auxiliary pattern 32 was added as shown in FIG. After that, exposure may be performed with an effective light source shape having a cross-shaped light shielding portion.
[0055]
In this embodiment, the relationship between the characteristics of a resist applied to a wafer and a desired pattern is considered. First, among the characteristics of the resist, the contrast of the resist will be considered. For example, suppose that the creator wants to perform exposure using a line resist instead of a hole resist although the desired pattern is a contact hole. The contrast between the resist for holes and the resist for lines is different from that of the developing solution, and it is known that the resist for holes is good for the contact holes, but the creator wants to use the resist for lines.
[0056]
In such a case, it is possible to prepare by preparing a database in consideration of the characteristics of each resist. The database of the present embodiment shows, for example, a table or a graph showing the relationship between the contrast of the resist with respect to the developer and the bias to the corresponding desired pattern. Here, the contrast with respect to the developer is defined as a value obtained by subtracting a dissolution rate before exposure from a dissolution rate after exposure. The difference is set to be large in the resist of the hole type, and the difference is set small in the line type resist. When drawing a graph based on this, when the vertical axis is the bias to the desired pattern and the horizontal axis is the contrast to the resist developing solution, the bias to the desired pattern is increased if the contrast of the resist to the developing solution decreases, As the contrast of the resist with respect to the developing solution increases, the bias to the desired pattern is reduced, and a graph of a monotonous decrease as shown in FIG. 34 is obtained. “Bias to a desired pattern” is a magnification of a desired pattern with respect to a reference dimension. As described above, the “reference dimension of a desired pattern” is an initial dimension converted into a dimension on a wafer in the present embodiment.
[0057]
For example, consider the case where TOK-DP746HC which is a resist for holes is used. The size of the desired hole is set to 110 nm, the size of the dummy hole is set to 90 nm, the illumination system shown in FIG. 7A is used, the maximum coherence factor σ is set to 0.92, Set a = 0.7 and b = 0.5. Since the light intensity of the isolated hole is weak, it may be increased to about 3 nm by OPC. The isolated hole referred to here is the hole number 1 in FIG. FIG. 8A shows the result of exposure under such conditions. As shown in the figure, it is understood that the desired pattern 21 is well resolved.
[0058]
Next, the case where the line resist UV6-SL is used will be discussed. The contrast of each resist with respect to the developer was applied to the desired pattern by 1.1 times referring to the database. That is, the size of the desired pattern is set to 121 nm (at this time, of course, the pattern period is not changed). The illumination system used the effective light source shape shown in FIG. 7A, the maximum σ was set to 0.92, and a = 0.7 and b = 0.5. FIG. 8B shows the result of exposure under such conditions. As shown in the figure, it is understood that the desired pattern is well resolved.
[0059]
In another example, it is assumed that there is a case in which a good exposure result is obtained with TOK-DP746HC, but a hole resist called JSR-KRFM170Y is desired to be used. There is information on JSR-KRFM170Y in the resist database, according to which the size of the desired hole is set to 110 nm and the size of the dummy hole is set to 90 nm, as shown schematically in FIG. In the illumination system, the maximum σ may be set to 0.92, and a = 0.7 and b = 0.5. When the experiment was performed as described above, good exposure results were obtained, and the results are shown in FIG. 8C.
[0060]
The experimental results of JSR-KRFM170Y indicate that an exposure amount is necessary because the taper is smaller than that of TOK-DP746HC. The choice is up to the user.
[0061]
Thus, in the exposure method I, if there is a resist database, even if each creator has various ideas regarding the resist use method, it is possible to widely cope with the resist method.
[0062]
The inventor made a mask for resists having different contrasts while changing the dimensions of the desired pattern 21 by several nm, and as a result, the bias to the desired pattern was about 0.85 times to about 1 time. .15 times. If it is about 0.85 times or less, a necessary increase in the exposure amount is caused, which causes a decrease in contrast. If it is about 1.15 times or more, a desired pattern 21 is easily connected.
[0063]
The characteristics of the resist are not limited to the contrast of the resist but also include the threshold value of the resist. Therefore, it is preferable that the database also holds the relationship between the desired pattern and the resist threshold. The inventor creates a mask for resists having different threshold values while changing the dimensions of the desired pattern 21 by several nm, and as a result, the bias to the desired pattern is about 0.85 times to about 1 time. .15 times. If it is about 0.85 times or less, a necessary increase in the exposure amount is caused, which causes a decrease in contrast. If it is about 1.15 times or more, a desired pattern 21 is easily connected.
[0064]
Embodiment 2
One of the evaluation amounts of the exposure method I is a mask error enhancement factor (hereinafter, referred to as MEEF: Mask Error Enhancement Factor). Here, MEEF is defined as a ratio of a pattern error on a wafer which occurs when an error occurs in a mask pattern. In general, MEEF should be closer to one. For example, MEEF tends to create a roadmap on the assumption that it is preferable to set the isolated line binary mask to 1.4, the isolated line phase shift mask to 1, the L / S pattern to 2, and the holes to 3 or less. Since the MEEF of the exposure method I is about 3.5 from FIG. 9 described later, it is relatively small. In such a case, if the MEEF database is prepared in advance, it can be dealt with. The MEEF database is a database indicating the relationship between the size of the dummy pattern and the MEEF. For example, in a mask as shown in FIG. 2A, p is 220 nm and the hole diameter is 110 nm. When a dummy pattern is inserted in the vertical and horizontal directions at a period of 220 nm, a mask pattern as shown in FIG. 3 is completed. At this time, MEEF when an error occurs in the dummy pattern only in the horizontal direction is as shown in FIG. In FIG. 30A, the bottom row indicates the size of the desired pattern, and the leftmost column indicates the size of the dummy pattern. Similarly, the MEEF when p is 240 nm and the hole diameter is 110 nm is as shown in FIG. The inventor has discovered that reducing the size of the dummy pattern also reduces the MEEF. This can be determined from the fact that the MEEF is small if the dummy pattern is small for any desired pattern size, taking FIG. 30 as an example. It can be seen that MEEF can be reduced by increasing the desired pattern.
[0065]
It should be noted that if the dummy hole is made smaller, the effect of enhancing the periodicity is reduced, and if the dummy hole is made larger, the resolution will be reduced. Have found that it should. Here, the reference size of the dummy hole is determined according to a flowchart of FIG.
[0066]
From the above, the present inventor has set the size of the dummy hole within 10% of the size determined by FIG. 20A so that the MEEF is within the allowable range without changing the desired pattern 21. I found that I had to adjust it to make it smaller. Since optimization of the illumination system also affects the MEEF, it is preferable that the MEEF database also considers the illumination conditions.
[0067]
The dimensions of the desired pattern 21 shown in FIG. 2A were set to 110 nm, and an auxiliary pattern 32 was inserted as shown in FIG. The size of the auxiliary pattern 32 was set to 85 nm (this corresponds to about 77% of the desired pattern). In the illumination system shown in FIG. 7A, the maximum coherence factor σ was set to 0.92, a = 0.7, and b = 0.5. MEEF when changing the pattern half pitch while maintaining the diameter of each hole of the desired pattern 21 at 110 nm (Since this MEEF has an error in the two-dimensional direction, at first glance, an error occurs in the one-dimensional direction. FIG. 9 shows that the result is different from that in FIG. It can be seen that the pattern half-pitch may be changed to achieve a certain MEEF or less. Although this method changes the desired mask pattern itself, it is an index of a mask pattern to be designed.
[0068]
As described above, the method of changing the MEEF in the exposure method I has been clarified.
[0069]
Embodiment 3
One of the evaluation amounts of the exposure method I is a line width error (hereinafter, referred to as a CD error). Here, the CD error is defined as the ratio of the size of the desired pattern 21 to the size of the pattern actually formed on the wafer from the desired pattern 21. Generally, it is better that the CD error is close to zero.
[0070]
As can be seen from FIG. 10 described later, the CD error of the exposure method I is k ₁ Is relatively small because it is about 13% for a contact hole whose value is close to 0.3 (usually, it is rarely less than 20%), but there are cases where it is desired to further reduce the CD error. Although the CD error has no upper limit, it can be easily corrected by OPC if the CD error is 15% or less based on the experience of the present inventor. In such a case, if a CD error database is prepared in advance, it can be dealt with. The CD error database is a database indicating the relationship between the size of the dummy pattern and the CD error. For example, in a mask as shown in FIG. 2A, p is 220 nm and the hole diameter is 110 nm. When a dummy pattern is inserted in the vertical and horizontal directions at a period of 220 nm, a mask pattern as shown in FIG. 3 is completed. The CD error at this time is as shown in FIG. In FIG. 31 (a), the bottom row indicates the size of the desired pattern, and the leftmost column indicates the size of the dummy pattern. Similarly, the CD error when p is 240 nm and the hole diameter is 110 nm is as shown in FIG. FIG. 31 shows that when the size of the dummy pattern is increased (closer to the desired pattern size), the CD error is reduced. This seems to be because when the size of the dummy hole is increased, it approaches a dense pattern which is generally said to be easily formed in the hole pattern.
[0071]
For the above reason, the size of the dummy hole should be changed within a range of ± 10% of the reference size. Here, the reference size of the dummy hole is determined according to a flowchart of FIG.
[0072]
From the above, the present inventor has set the size of the dummy hole within 10% of the size determined by FIG. 20A so that the CD error is within the allowable range without changing the desired pattern 21. I found that I had to adjust it to make it bigger. Since optimization of the illumination system also affects the CD error, it is preferable that the illumination condition is also considered in the CD error database.
[0073]
The dimensions of the desired pattern 21 shown in FIG. 2A were set to 110 nm, and an auxiliary pattern 32 was inserted as shown in FIG. The size of the auxiliary pattern 32 was set to 85 nm. In the illumination system shown in FIG. 7A, the maximum coherence factor σ was set to 0.92, a = 0.7, and b = 0.5. FIG. 10 shows a CD error when changing the pattern half pitch while maintaining the diameter of each hole of the desired pattern 21 at 110 nm. It can be seen that the pattern half pitch may be changed in order to reduce the error to a certain CD error or less. Although this method changes the desired mask pattern itself, it is an index of a mask pattern to be designed.
[0074]
As described above, the method of changing the CD error in the exposure method I has been clarified.
[0075]
Embodiment 4
One of the evaluation amounts of the exposure method I is a depth of focus (hereinafter, referred to as DOF: Depthof Focus). The DOF gives an allowable range in which the wafer may be shifted from the focal position in the optical axis direction of the exposure apparatus. The tolerance is usually determined so that the size of the desired pattern 21 falls within ± 10% of the desired size. Generally, the larger the DOF, the better.
[0076]
Since the exposure method I can be regarded as exposing a pseudo dense pattern, the DOF is relatively large, but there are cases where the DOF needs to be further increased. Although the lower limit of the DOF differs depending on the user, the symposium held for three days from April 23 to 25, 2002, the opening lecture of Photomask Japan (hereinafter, PMJ: Photomask Japan), "Lithography Strategies for 65 nm Node" It was announced that a 0.4 μm or more DOF would be preferable in the coming era. In such a case, if a DOF error database is prepared in advance, it can be dealt with. The DOF database is a database indicating the relationship between the size of the dummy pattern and the DOF. For example, in a mask as shown in FIG. 2A, p is 240 nm and the hole diameter is 120 nm. When a dummy pattern is inserted in the vertical and horizontal directions at a cycle of 240 nm, a mask pattern as shown in FIG. 3 is completed. At this time, the DOF is as shown in FIG. In FIG. 32, the bottom row indicates the size of the desired pattern, and the leftmost column indicates the size of the dummy pattern. The result of FIG. 32 shows the DOF when the CD becomes 108 nm to 120 nm, and the condition is relatively severe. It can be seen from FIG. 32 that the DOF increases as the size of the dummy pattern increases. FIG. 33 shows a simulation result regarding this. In a mask as shown in FIG. 2A, p is 220 nm and the hole diameter is 110 nm. When a dummy pattern is inserted in the vertical and horizontal directions at a period of 220 nm, a mask pattern as shown in FIG. 3 is completed. When a dummy pattern having a size of 79.5 nm is inserted, the aerial image at each defocus is as shown in FIG. 33 (i). When a dummy pattern having a size of 90.5 nm is inserted, the aerial image at each defocus is obtained. The aerial image is as shown in FIG. It can be visually recognized that the larger the dummy pattern, the larger the DOF.
[0077]
For the above reason, the size of the dummy hole should be changed within a range of ± 10% of the reference size. Here, the reference size of the dummy hole is determined according to a flowchart of FIG.
[0078]
From the above, the present inventor has set the size of the dummy hole within 10% of the size determined by FIG. 20A so that the DOF falls within the allowable range without changing the desired pattern 21. I found that I had to adjust it to make it bigger.
[0079]
Since optimization of the illumination system also affects DOF, it is preferable that the DOF database also considers illumination conditions. For example, it is not advisable to increase the maximum σ when the pattern period is large, and the DOF may increase when the maximum coherence factor σ is reduced. Alternatively, it is also effective to expose a plurality of times while shifting the wafer in the optical axis direction of the exposure apparatus. This method increases the DOF, but requires care. If the wafer is shifted in the direction of the optical axis of the exposure apparatus, the dummy pattern may be resolved. In order to avoid such a situation, it is preferable to correct the dummy pattern. For example, in the mask pattern 30A shown in FIG. 11, the dummy pattern 32A around the desired pattern 31 is smaller than the other dummy patterns 32.
[0080]
As described above, the method of changing the DOF in the exposure method I has been clarified.
[0081]
Embodiment 5
In exposure method I, it is assumed that an elliptical hole is to be formed. For example, assume that there is a desired rectangular pattern 33A as shown in FIG. In practice, such a pattern 33 is often resolved as an elliptical hole. At this time, the square dummy holes 34 were inserted according to the pitch of the desired pattern 33 to form the mask pattern 30B shown in FIG. The symbol attached to the arrow means that the length of the arrow is the same if the symbol is the same. If the illumination system is optimized for the mask pattern 30B shown in FIG. 12B, a desired pattern 33 may be resolved. However, the length of the elliptical hole may be insufficient, and it is necessary to insert a larger OPC than usual. However, when a rectangular dummy hole 35 was inserted instead of the dummy pattern 34 as in a mask pattern 30C shown in FIG. 12C, it was found that an elliptical hole corresponding to the desired pattern 33 was easily formed. Was.
[0082]
An elliptical shape can be easily formed by inserting a dummy pattern by increasing the period in the major axis direction of the elliptical hole. This can be explained as follows. That is, when the dummy holes are inserted at the same period in the vertical and horizontal directions, the diffracted light flies at the same angle in the vertical and horizontal directions and forms an image at the same angle. Next, when the period in the horizontal direction is larger than the period in the vertical direction, the spread angle of the diffracted light becomes smaller than that of the diffracted light in the vertical direction because the period in the horizontal direction is larger than that in the vertical direction. The spread angle of the diffracted light corresponds to a pseudo NA. A large spread of the diffracted light in the vertical direction is equivalent to a large pseudo-NA in the vertical direction, and a small spread of the diffracted light in the horizontal direction is a small pseudo-NA in the horizontal direction. Is equivalent to Comparing the pseudo-NA in the vertical and horizontal directions, the pseudo-NA in the vertical direction is large, so that there is a resolution in the vertical direction and the resolution becomes fine in the vertical direction. On the other hand, since the pseudo NA is small in the horizontal direction, the resolving power is reduced, and a coarse pattern is created.
[0083]
Therefore, the combination of the above two methods makes it easier to create an elliptical hole. As described above, the method of forming the elliptical hole in the exposure method I has been clarified.
[0084]
Embodiment 6
Next, a case will be examined in which a plurality of desired patterns having a plurality of pitches are mixed sufficiently apart from each other, and the mutual influence between the patterns can be ignored. FIG. 13A shows desired patterns 130A and 130B formed in regions s and t surrounded by two dotted lines on one mask 130. FIG. The desired pattern 130A has one square hole 132 and two rectangular holes 134. The desired pattern 130B has three squares 136.
[0085]
The desired pattern 130A in the region s has a pattern interval D ₁ Is narrow. On the other hand, in the region t, the desired pattern 130B is ₂ Is wide. Further, the period P of the pattern of the region t ₂ K for ₁ Is slightly smaller than 1. Period P in region s ₁ And period P in region t ₂ , P ₁ Is smaller. For this reason, it is very difficult to precisely resolve the pattern in the region s, and the light intensity reaching the wafer is different between the region s where the pattern is dense and the region t where the pattern is sparse. Simultaneous resolution of both patterns 130A and 130B is not possible with normal exposure.
[0086]
However, the exposure method I is also effective in such a case. First, as shown in FIG. 13B, a dummy pattern 140A is formed in the region s. As shown in FIG. 13B, since the desired pattern 130A has holes 132 and 134 having two different shapes, the dummy pattern 140A also includes the dummy holes 142 and 144 correspondingly. ing.
[0087]
Thus, in the present embodiment, the way of inserting the dummy pattern 140A is devised. As described in the fifth embodiment, a rectangular desired pattern is preferably a rectangular dummy pattern that is substantially similar thereto, and a square desired pattern is preferably a square dummy pattern that is substantially similar thereto. Therefore, in the region s, dummy patterns having two types of shapes are mixed.
[0088]
In addition, a dummy pattern 140B is provided in the region t, as shown in FIG. As shown in FIG. 13C, the dummy pattern 140B is composed of dummy holes 146, and no dummy holes 146 are inserted between the two holes 136 of the desired pattern 130B. When the dummy hole 146 is inserted, k ₁ Is smaller than 0.5, and has a period less than the theoretical resolution limit. For example, the hole diameter L of the region t ₂ Is 110 nm and the hole interval D ₂ Is 220 nm. As described above, in the exposure apparatus, the wavelength of the light source is 248 nm and the numerical aperture is 0.73. ₂ K for 330 nm ₁ Is about 0.97, and k corresponds to a half cycle thereof. ₁ Is about 0.48, which is below the theoretical resolution limit.
[0089]
When the dummy patterns 140A and 140B are inserted in this manner, the pitch P ₁ Is the pitch P of the region t ₂ Is smaller than the pitch P of the region s. ₁ The lighting conditions were optimized according to. As a result, it was possible to transfer the pattern satisfactorily. However, in those processes, the size of the dummy pattern was adjusted between the respective regions, and the size of the desired pattern 130B in the region t was increased.
[0090]
Hereinafter, a method for improving the depth of focus in the region t in addition to the good resolution of the desired patterns 130A and 130B will be described. That is, in the above-described example, the depth of focus in the region t may be small. This is the pitch P of the region t ₂ Is so large that a so-called forbidden pitch phenomenon occurs in the illumination system adapted to the region s. The forbidden pitch phenomenon is a phenomenon in which the DOF sharply decreases over a certain period or more. This is because normal imaging is performed using the 0th-order light, the 1st-order light, and the -1st-order light. On the other hand, if the pattern period is too large, the second or higher order diffracted light contributes to the pattern formation. It is. In order to prevent this, it is necessary to optimize the illumination system in accordance with the region t. In that case, the result was obtained that the pattern in the region s was not resolved well. This is because there is a conflicting principle that the depth of focus decreases when priority is given to the resolution, and the resolution decreases when priority is given to the depth of focus. FIG. 13A is an example of such a conflicting pattern. On the other hand, the present inventor has discovered that, as shown in FIG. 13D, by changing the pattern of the region s by OPC, it is possible to prevent a decrease in resolution. In FIG. 13D, a part of the desired pattern 130A in the region s is reduced by OPC. Specifically, the desired hole 132 indicated by a dotted line is changed to a desired hole 132A indicated by a solid line, and the desired hole 134 indicated by a dotted line is changed to a desired hole 134A indicated by a solid line. This is because the mask data is increased instead of increasing the depth of focus. The creator can decide whether to give priority to the depth of focus or the size of the mask data.
[0091]
According to this embodiment, a pattern that cannot be normally resolved can be resolved with sufficient resolution and depth of focus.
[0092]
Embodiment 7
Next, features of the binary mask, the halftone mask, and the phase shift mask will be described. It is assumed that p = 220 nm in the desired pattern 21 shown in FIG. Since the desired patterns 21 are arranged in a lattice pattern, the auxiliary pattern 32 shown in FIG. At this time, it is assumed that the hole diameter of the desired pattern 21 is 110 nm. In the case of a binary mask and a halftone mask, exposure may be performed with an illumination system having an effective light source distribution as shown in FIG. 7A. In this case, the maximum coherence factor σ is 0.92 in FIG. a = 0.7 and b = 0.5 were set. In the mask shown in FIG. 3, a so-called phase shift mask in which adjacent holes have a phase difference of 180 degrees uses an illumination system having an effective light source distribution as shown in FIG. When a = 0.2 and b = 0.1 were set, a desired pattern was resolved.
[0093]
FIG. 14 shows a graph in which the contrast of the pattern 21 shown in FIG. 2A is evaluated by simulation. It can be understood that the difference in contrast between the various masks. FIG. 15 shows a graph in which the line width uniformity was evaluated by simulation. In FIG. 15, the horizontal axis of the graph is a hole number, which corresponds to that shown in FIG. The vertical axis represents the line width at each hole number appropriately, and visually represents the line width uniformity. A straight line in the graph means that the line width uniformity is good.
[0094]
From FIGS. 14 and 15, a database for each mask can be created for the contrast and the CD error. If a database for each mask is created according to this embodiment, it is possible to select a mask according to the creator's preference, and it is also easy to select an optimal mask for a given pattern.
[0095]
Embodiment 8
When the distance between the two inserted dummy patterns is equal to or less than a predetermined value, there is a high possibility that the dummy patterns will be resolved, and it is necessary to review the insertion method.
[0096]
First, when two inserted dummy patterns 161 overlap as shown in FIG. 16A, as shown in FIG. 16D, a dummy pattern whose center of gravity coincides with the center of the center of gravity of both dummy patterns 161 is obtained. 161 is arranged. In FIG. 16D, two squares drawn by dotted lines are the original dummy patterns 161, and the squares drawn by solid lines are the dummy patterns 161 created after reviewing the insertion method.
[0097]
Next, when the two inserted dummy patterns 161 are adjacent to each other as shown in FIG. 16B, a dummy whose center of gravity matches the center of the center of gravity of both dummy patterns 161 as shown in FIG. The pattern 161 is arranged. In FIG. 16E, two squares drawn by dotted lines are the original dummy patterns 161, and the squares drawn in practice are the dummy patterns 161 created after reviewing the insertion method.
[0098]
Finally, a case is considered where the two inserted dummy patterns 161 are arranged at a distance equal to or less than a predetermined distance as shown in FIG. The predetermined distance is the center distance D of the dummy pattern. ₁ Is k ₁ This is the case where the conversion is about 0.5 or less. Surprisingly, this often does not require much attention. This is because the resolution of such a dummy pattern can be substantially avoided by properly selecting the illumination system. However, the minimum vertex interval D between each inserted dummy pattern ₂ Is k ₁ When converted to 0.2 or less, it is preferable to arrange an auxiliary pattern 161 having the center of gravity of the center of both auxiliary patterns as the center as shown in FIG. This is because there is a meaning in preparing for a case where the resolution is obtained, and there is a possibility that making the mask is difficult. The square drawn by the dotted line in FIG. 16F is the original dummy pattern 161, and the square drawn by practice is the dummy pattern 161 created after reviewing the insertion method.
[0099]
Dummy pattern center spacing D ₁ Is k ₁ In many cases, it is not necessary to be concerned even if the value is reduced to about 0.5 or less, but it is necessary to remember the existence of an adjacent dummy pattern just in case. This is the same whether a human inserts a dummy pattern or a case where a computer inserts a dummy pattern. In particular, if you leave it to the computer, it is necessary to perform an operation to temporarily store such locations, and check that such locations are not resolved during the final pattern check. Should have such an algorithm.
[0100]
As described above, a method for coping with the case where the two inserted dummy patterns overlap, are adjacent to each other, or have a predetermined distance or less has been clarified.
[0101]
Embodiment 9
A feature of the mask in the exposure method I is that a dummy pattern is inserted into a desired pattern. Therefore, it is necessary to examine in detail the effect of the dummy pattern on the desired pattern. In this embodiment, a so-called location error was examined. Here, the location error means, for example, that the center 172 of the mask pattern 171 which should have been originally arranged in a line is slightly shifted as shown in FIG. With current mask making techniques, there are usually 2-3 nm location errors on the mask.
[0102]
A dummy pattern 32 was inserted into the desired pattern 21 shown in FIG. 2A as shown in FIG. The number of dummy patterns is 112.
[0103]
A simulation has been performed on the effect of the location error on the desired pattern 21, and a method thereof will be introduced. A set W1x of 112 random numbers having an average of 0 and a standard deviation of 2.5 / 4 is created. Separately, a set W1y of 112 random numbers having an average of 0 and a standard deviation of 2.5 / 4 is further created. The unit of W1x is set to nm and set as a location error in the x direction, and similarly, the unit of W1y is set as nm and reflected as a location error in the y direction in the dummy pattern. As a result, a simulation was performed to determine how the line width of the desired pattern 21 is affected as compared with the ideal case without a location error. In order to increase the reliability, a simulation was performed by considering nine types of random numbers in addition to one type of random numbers (W1x, W1y). This operation was repeated for dummy patterns of ten different sizes. Similarly, a similar simulation was performed while changing the dimensions of a desired pattern to improve reliability. As a result of a simulation that took a great deal of time and labor, it was found that a desired pattern was hardly affected by a location error if the size of the dummy pattern was small. For example, when the sizes of the desired pattern and the dummy pattern are changed as shown in FIG. 27, the influence of the location error is as shown in FIG. In the graph of FIG. 28, the horizontal axis is the file number shown in FIG. 27, and the vertical axis corresponds to the location error. The larger the value, the greater the influence of the location error.
[0104]
A location error database can be created based on the result of the present embodiment. The location error database is a database representing the relationship between the location error and the size of the dummy pattern. By referring to such a database, it is possible to create a mask that is resistant to location errors. That is, the creator can refer to the location error database and adjust the size of the dummy pattern so that the location error is within an allowable range.
[0105]
Embodiment 10
A feature of the mask in the exposure method I is that a dummy pattern is inserted into a desired pattern. Therefore, it is necessary to examine in detail the effect of the dummy pattern on the desired pattern. In the present embodiment, a so-called size error was examined. Here, the size error means that, as shown in FIG. 18, for example, a dummy pattern 181 which is originally formed along a dotted line as originally designed and deviates from a predetermined size as a solid-line dummy pattern 182 is formed. It refers to the shift when it is lost.
[0106]
A dummy pattern 32 was inserted into the desired pattern 21 shown in FIG. 2A as shown in FIG. The number of dummy patterns is 112.
[0107]
We simulated the effect of the size error on the desired pattern. A set R1x of 112 random numbers is created such that the average is 0 and the standard deviation is 2% of the size of the desired pattern. Separately, a set R1y of 112 random numbers is further created such that the average is 0 and the standard deviation is 2% of the size of the desired pattern. The unit of R1x is nm and the size error in the x direction is set, and similarly, the unit of R1y is nm and the size error in the y direction is reflected on the dummy pattern. As a result, a simulation was performed to determine how the line width of a desired pattern is affected as compared with an ideal case without a size error. In order to increase the reliability, a simulation was performed on one type of random numbers (R1x, R1y), considering nine more random numbers. This operation was repeated for dummy patterns of ten different sizes. Similarly, in order to improve the reliability, the same simulation was performed while changing the dimensions of a desired pattern. As a result of a simulation that took a great deal of time and effort, it was found that if the size of the dummy pattern was small, the desired pattern was hardly affected by the size error. For example, when the sizes of the desired pattern and the dummy pattern are changed as shown in FIG. 27, the influence of the size error is as shown in FIG. In the graph of FIG. 29, the horizontal axis is the file number shown in FIG. 27, and the vertical axis corresponds to the size error. The larger the value, the greater the effect of the error error.
[0108]
A size error database can be created based on the result of this embodiment. The size error database is a database representing the relationship between the size error and the size of the dummy pattern. By referring to such a database, it is possible to create a mask that is resistant to size errors. That is, the creator can refer to the size error database and adjust the size of the dummy pattern so that the size error is within an allowable range.
[0109]
Embodiment 11
As shown in FIG. 19A, consider a pattern 190 in which a plurality of periods are mixed. Conventionally, it has been impossible to insert a dummy pattern into such a desired pattern 190. This is because the assumption that the dummy pattern is periodically inserted cannot be used. However, according to the present invention, a dummy pattern can be inserted into such a pattern 190 according to the flowchart shown in FIG.
[0110]
FIG. 20A is a flowchart for determining the size of the dummy pattern. The dimensions of the dummy holes in the above embodiment are determined by FIG. The v in FIG. 20A can be freely set by the creator. First, k for the minimum half pitch p of the desired pattern ₁ Is smaller than 0.25 × √2 (step 1102). If step 1102 determines that it is, the size of the dummy pattern is set to v% of the desired pattern (step 1104). On the other hand, if the step 1102 determines that this is not the case, the size of the dummy pattern is k ₁ Is set to a size equivalent to 0.25 or less (step 1106).
[0111]
FIG. 20B is a flowchart for determining the period of the dummy pattern when the desired pattern is a periodic pattern. In FIG. 20B, the creator can freely set g1, g2, g3, and g4. Theoretically, g1 = 0.25, g2 = 0.50, g3 = 2 × g2, and g4 = 2 × g2 are good. However, each value may be changed in consideration of past experience and the performance of the exposure apparatus.
[0112]
First, it is determined whether or not the hole diameter of the desired pattern (s in FIG. 19A) is less than the first threshold value g1 (step 1202). If step 1202 determines that it is, the process ends abnormally (step 1204). On the other hand, if step 1202 determines that it is not the case, it is determined whether the hole diameter of the desired pattern is equal to or more than the first threshold g1 and equal to or less than the second threshold g2 (step 1206). Here, the period of the periodic pattern is P ₁ And
[0113]
If step 1206 determines that the value is not less than the first threshold and not more than the second threshold, P ₂ = P ₁ Toki (Step 1208), P ₂ To k ₁ Then, it is determined whether or not the value is equal to or more than the third threshold value g3 (step 1210).
[0114]
If step 1210 determines that it is not greater than or equal to the third threshold g3, the cycle P ₂ Then, a dummy pattern is inserted (step 1212). If it is determined in step 1210 that the value is equal to or larger than the third threshold value g3, i = i + 1 is set (step 1214), and P ₁ Is obtained by dividing i ₂ (Step 1216), and the process returns to step 1210. Finally, the period P ₂ Then, a dummy pattern is inserted (step 1212).
[0115]
If step 1206 determines that the value is not greater than or equal to the first threshold value g1 and less than or equal to the second threshold value g2, P ₂ = P ₁ Toki (Step 1218), P ₂ To k ₁ It is determined whether or not the value is equal to or greater than the fourth threshold value g4 when converted by (step 1220). If step 1220 determines that the value is equal to or greater than the fourth threshold value g4, P ₂ K minus the hole diameter ₁ Is not greater than or equal to a fifth threshold value g5 (step 1222), otherwise, no dummy pattern is inserted (step 1226). On the other hand, if step 1120 determines that the value is not equal to or greater than the fourth threshold value g4, or if step 1222 determines that the value is equal to or less than the fifth threshold value g5, the cycle P ₂ To arrange a dummy pattern (step 1224).
[0116]
Referring to FIG. 19A, first, it is checked whether there is a pattern in the vertical direction and the horizontal direction. The pattern 191 has no pattern in the vertical and horizontal directions. The pattern 192 has a pattern in the horizontal direction, and the interval is 3p ′ ″. Where p '''is k ₁ It is assumed that the value is equal to or less than g3 in FIG. The pattern 193 had a pattern at a position spaced apart by p on the right side and 2p on the left side in the horizontal direction. Where p is k ₁ It is assumed that the value is equal to or less than g3 in FIG.
[0117]
At first glance, the pattern shown in FIG. However, in this embodiment, if there are at least two patterns, a period is recognized there, and if there is only one pattern, any period may be created.
[0118]
According to this principle, in the case of the pattern 190 shown in FIG. 19A, the pattern 191 is treated as an isolated pattern, the pattern 192 is treated as a pattern having a period 3p ′ ″ in the horizontal direction, and the pattern 193 is processed in the horizontal direction. What is necessary is just to handle so that it may have 2p. Such a cycle is derived by the flowchart of FIG. The flowchart of FIG. 20C is applied to how to insert the cycle of the isolated pattern. More specifically, it is determined whether or not a periodic pattern exists within a predetermined distance from the isolated pattern (step 1302). If it is determined that step 1302 exists, the dummy pattern is adjusted according to the cycle of the pattern. Are arranged (step 1304), and when it is determined that step 1302 does not exist, the dummy pattern is arranged with the size of the isolated pattern set to a half pitch (step 1306).
[0119]
Now with the prospect insertion method of the dummy pattern in the lateral direction. FIG. 19B shows a state where the dummy pattern is inserted only in the horizontal direction.
[0120]
Next is to insert a pattern in the vertical direction, but there is no pattern directly above or below any of the patterns. However, when the patterns arranged in the horizontal direction are connected by lines, it can be seen that there is a certain line spacing. In this case, their line spacing is 2p 'and p''. However, it is assumed that both p ′ and p ″ are equal to or less than g3 in FIG. From the above, it is sufficient to insert a dummy hole at p ′ and p ″ in the vertical direction. The final result is shown in FIG.
[0121]
According to the present embodiment, it is possible to insert a dummy pattern even for a pattern having no apparent period.
[0122]
Embodiment 12
Consider the pattern 200 shown in FIG. In this pattern 200, a lattice is formed at a constant period, and the center 212 of the pattern 210 is arranged on each lattice point, but it is assumed that only one pattern 220 has no center on that lattice point. . In addition, it is assumed that the center 222 of the pattern 220 is slightly displaced from the lattice point.
[0123]
In such a case, the dummy pattern 230 may be inserted ignoring the positional shift of the pattern 220. This is because OPC may be inserted. If this displacement is within 20% of the grating period, there is no particular problem and it can be avoided by inserting OPC. Finally, as shown in FIG. 21B, a mask pattern 201 in which the dummy pattern 230 is inserted is created.
[0124]
Embodiment 13
Hereinafter, an example of the relationship between the size of the dummy pattern and the exposure amount will be described. It is assumed that p = 220 nm in the desired pattern 21 shown in FIG. Since the desired pattern 21 is on a grid-like point, as shown in FIG. 3, the auxiliary pattern 32 was inserted to form the mask pattern 30.
[0125]
At this time, the hole diameter of the desired pattern 21 is 110 nn. When the size of the dummy pattern is 80 nm, 460 J / m ² A good pattern could be exposed with the exposure amount of. The result is shown in FIG. Next, when the size of the dummy pattern is 90 nm, 435 J / m ² A good pattern could be exposed with the exposure amount of. The result is shown in FIG. As will be understood, the larger the size of the dummy pattern, the smaller the required exposure dose. By utilizing this property, the creator can determine the exposure amount within a certain range.
[0126]
Similarly, it is possible to change the exposure amount by changing the number of dummy patterns. By increasing the number of dummy patterns, exposure with a small exposure amount becomes possible. The exposure amount can be adjusted very effectively up to two rounds of the dummy pattern around the desired pattern, but the effect of adjusting the exposure amount becomes weaker when three or more rounds of the dummy pattern are inserted.
[0127]
An exposure amount database can be created based on the result of this embodiment. The exposure amount database is a database representing a relationship between the exposure amount and the size of the dummy pattern and / or the number of the dummy patterns. By referring to such a database, the creator can adjust the size of the dummy pattern corresponding to the desired exposure amount. As described above, according to the present embodiment, the exposure amount can be adjusted.
[0128]
Embodiment 14
An example according to the flowchart of FIG. 20 will be introduced. Here, in order to simplify the discussion, the case of FIGS. 20A and 20B will be discussed. The program created by the inventor here assumes an exposure apparatus having a wavelength of 248 nm and a numerical aperture of 0.73.
[0129]
When the desired pattern period was changed to 280 nm and the desired pattern hole diameter was changed, the result as shown in FIG. 23 was obtained. The unit of the numerical value in FIG. 23 is nanometer. At this time, the values of g1, g2, g3, g4, and g5 in FIG. 20B are 0.29, 0.40, 1.20, 0.80, and 0.25, respectively. is there.
[0130]
The inventor performed a simulation using a result obtained from a program created in accordance with the flowchart of FIG. 20, and confirmed that a desired pattern could be transferred with high accuracy.
[0131]
The resolving power of a projection exposure apparatus often changes between 0.25 and √2. Therefore, g1 is 0.25 or more and 0.25 × √2 or less, g2 is 0.25 × √2 or more and 0.5 or less, g3 is 1.0 or more and 以下 2 or less, and g4 is 0.5 × √2 or more and 1 or less. It was found that by setting g5 to be equal to or less than 0.0 and g5 being equal to or greater than 0.25 and 0.25 × 2, it is possible to determine the period of the dummy pattern for almost all the patterns.
[0132]
As described above, according to the flowchart of FIG. 20, the period and size of the dummy pattern can be easily determined.
[0133]
Next, an embodiment of a device manufacturing method using the above-described exposure apparatus will be described with reference to FIGS. FIG. 24 is a flowchart for explaining the manufacture of devices (semiconductor chips such as ICs and LSIs, LCDs, CCDs, and the like). Here, the manufacture of a semiconductor chip will be described as an example. In step 1 (circuit design), the circuit of the device is designed. Step 2 (mask fabrication) forms a mask on which the designed circuit pattern is formed. In step 3 (wafer manufacture), a wafer is manufactured using a material such as silicon. Step 4 (wafer process) is referred to as a preprocess, and an actual circuit is formed on the wafer by the lithography technique of the present invention using the mask and the wafer. Step 5 (assembly) is called a post-process, and is a process of forming a semiconductor chip using the wafer created in step 4, and includes processes such as an assembly process (dicing and bonding) and a packaging process (chip encapsulation). . In step 6 (inspection), inspections such as an operation check test and a durability test of the semiconductor device created in step 5 are performed. Through these steps, a semiconductor device is completed and shipped (step 7).
[0134]
FIG. 25 is a detailed flowchart of the wafer process in Step 4. Step 11 (oxidation) oxidizes the wafer's surface. Step 12 (CVD) forms an insulating film on the surface of the wafer. Step 13 (electrode formation) forms electrodes on the wafer by vapor deposition or the like. Step 14 (ion implantation) implants ions into the wafer. In step 15 (resist processing), a photosensitive agent is applied to the wafer. Step 16 (exposure) uses the exposure apparatus to expose a circuit pattern on the mask onto the wafer. Step 17 (development) develops the exposed wafer. Step 18 (etching) removes portions other than the developed resist image. Step 19 (resist stripping) removes unnecessary resist after etching. By repeating these steps, multiple circuit patterns are formed on the wafer.
[0135]
【The invention's effect】
As described above, according to the present invention, the data creator only needs to create and input a pattern to be finally formed on the resist, and the subsequent generation of mask pattern data is automatically performed by a computer according to the above procedure. Therefore, an optimal mask pattern can be efficiently created even in the design of a large-scale semiconductor integrated circuit.
[Brief description of the drawings]
FIG. 1 is a flowchart illustrating a method for setting a mask pattern and an illumination condition according to the present invention.
FIG. 2A is a schematic plan view showing a desired pattern, and FIG. 2B is a plan view in which holes constituting the desired pattern are provided with identification hole numbers.
FIG. 3 is a schematic plan view of a mask pattern obtained by inserting a dummy pattern into a desired pattern.
FIG. 4 is a schematic plan view of quadrupole illumination.
5 (a) shows the results of an exposure experiment in which the mask pattern shown in FIG. 3 was illuminated by the illumination system shown in FIG. 4, and FIG. 5 (b) shows the results of the exposure system shown in FIG. 7 (a). 4 shows the results of an exposure experiment in which the mask pattern shown in FIG. 3 was illuminated.
FIG. 6A is a plan view schematically showing an illumination portion contributing to resolution, and FIG. 6B is a plan view schematically showing an illumination portion for suppressing a dummy pattern. is there.
FIG. 7 is a diagram illustrating an example of an illumination system that generates a plurality of types of light applicable to the present invention. In particular, FIG. 7A illustrates an illumination system suitable for a binary mask into which a dummy pattern is inserted. FIG. 7B is a diagram of an illumination system suitable for a phase shift mask in which a dummy pattern is inserted.
8 (a), 8 (b) and 8 (c) show the results of an exposure experiment of Example 1. FIG.
FIG. 9 is a graph showing a relationship between a half pitch of a mask pattern used in Example 2 and a mask error enhancement factor.
FIG. 10 is a graph showing a relationship between a half pitch of a mask pattern used in Example 3 and a line width error.
FIG. 11 is a schematic plan view showing a modified example of the mask pattern of FIG. 3 used in the fourth embodiment.
FIG. 12A is a schematic plan view showing a desired rectangular pattern used in the fifth embodiment. FIG. 12B is a schematic plan view showing a mask pattern created by inserting a square dummy pattern into the desired pattern shown in FIG. FIG. 12C is a schematic plan view showing a mask pattern created by inserting a rectangular dummy pattern into the desired pattern shown in FIG.
FIG. 13A is a schematic plan view showing a desired pattern used in a sixth embodiment, and FIG. 13B shows an example in which a dummy pattern is inserted into a region s in FIG. 13A. 13C is a diagram illustrating an example in which a dummy pattern is inserted into a region t in FIG. 13A, and FIG. 13D is a diagram illustrating a case where a dummy pattern is inserted into a region s in FIG. 13A. It is a figure showing the example which inserted OPC.
FIG. 14 is a graph showing the relationship between various masks and contrast used in Example 7.
FIG. 15 is a graph showing the relationship between various masks and line width uniformity used in Example 7.
FIG. 16 is a diagram schematically showing a dummy pattern insertion example in which a problem is likely to occur.
FIG. 17 is a diagram schematically illustrating a location error used in the ninth embodiment.
FIG. 18 is a diagram schematically illustrating a size error used in the tenth embodiment.
FIG. 19A is a diagram illustrating an example of a desired pattern in which a plurality of periods are mixed. FIG. 19B is a diagram illustrating an example in which a dummy pattern is inserted in one direction of the pattern of FIG. 19A. FIG. 19C is a diagram illustrating an example in which a dummy pattern is inserted into the pattern of FIG. 19A.
FIG. 20A is a flowchart illustrating a method of determining the size of a dummy pattern used in the eleventh embodiment. FIG. 20B is a flowchart illustrating a method used in the eleventh embodiment for determining the period of the dummy pattern when the desired pattern is a periodic pattern. FIG. 20C is a flowchart illustrating a method used in the eleventh embodiment for determining a dummy pattern period when a desired pattern is an isolated pattern.
FIG. 21A is a schematic plan view illustrating an example of a desired pattern having no periodicity in a part used in Example 12; FIG. 21B is a schematic plan view showing a mask pattern created by inserting a dummy pattern into the desired pattern shown in FIG.
FIGS. 22A and 22B show the results of an exposure experiment of Example 13. FIGS.
FIG. 23 shows a result of a program created by the inventor.
FIG. 24 is a plan view for explaining OPC.
FIG. 25 is a flowchart for explaining a device manufacturing method having the exposure apparatus of the present invention.
FIG. 26 is a detailed flowchart of step 4 shown in FIG. 25.
FIG. 27 is a diagram showing names provided for convenience to identify the size of a desired pattern and the size of an auxiliary pattern.
FIG. 28 is a diagram illustrating a degree of a location error.
FIG. 29 is a diagram illustrating a degree of a size error.
FIG. 30 is a database showing a relationship between dimensions of dummy patterns and MEEF.
FIG. 31 is a database showing a relationship between a dimension of a dummy pattern and a CD error.
FIG. 32 is a database showing a relationship between dimensions of a dummy pattern and DOF.
FIG. 33 is a diagram showing a simulation result when the mask pattern shown in FIG. 3 is used.
FIG. 34 is a graph showing a relationship between bias to a desired pattern and contrast of a resist.
[Explanation of symbols]
21, 31, 33 desired pattern
30-30C mask pattern
32, 34, 35 dummy pattern
61, 62, 72, 74 Light transmitting part
71, 73 Shading part
130A, 130B, 132, 134, 136 desired pattern
140A, 142, 144, 146, 161 dummy pattern
171 Mask pattern corresponding to desired pattern
172 Center of mask pattern corresponding to desired pattern
181 Mask pattern that should be created
182 Mask pattern actually created
191, 192, 193, 210, 220 Desired pattern
194, 230 dummy pattern

Claims (52)

A mask in which a desired pattern and an auxiliary pattern having a smaller dimension than the desired pattern are arranged is divided into a plurality of types so that the desired pattern is resolved and the resolution of the auxiliary pattern is suppressed. The method of manufacturing a mask suitable for an exposure method of projecting light passing through the mask onto the object to be exposed through a projection optical system by illuminating with the light,
Setting the dimensions of the desired pattern;
Adjusting the size of the desired pattern according to characteristics of a resist applied to the object to be exposed. The characteristic of the resist is the contrast of the resist,
The method of claim 1, wherein the adjusting step adjusts the bias to the desired pattern within a range from about 0.85 times to about 1.15 times. The characteristic of the resist is a threshold of the resist,
The method of claim 1, wherein the adjusting step adjusts the bias to the desired pattern within a range from about 0.85 times to about 1.15 times. The method according to claim 1, wherein the adjusting step adjusts by referring to a database that defines a relationship between the characteristic of the resist and the dimension of the desired pattern. A mask in which a desired pattern and an auxiliary pattern smaller in size than the desired pattern are arranged is illuminated so that the desired pattern is resolved and the resolution of the auxiliary pattern is suppressed. A database used for setting a mask pattern suitable for an exposure method of projecting the light having passed through the mask onto an object to be exposed via a projection optical system,
A database for displaying a bias to the desired pattern when characteristics of a resist applied to the object to be exposed are input. A mask in which a desired pattern and an auxiliary pattern having a smaller dimension than the desired pattern are arranged is divided into a plurality of types so that the desired pattern is resolved and the resolution of the auxiliary pattern is suppressed. The method of manufacturing a mask suitable for an exposure method of projecting light passing through the mask onto the object to be exposed through a projection optical system by illuminating with the light,
Setting the dimensions of the desired pattern;
Utilizing a relationship between at least one of a mask error enhancement factor and a line width error with respect to the size of the desired pattern and a minimum pitch of the mask pattern, the minimum pitch is determined such that the at least one is within an allowable range. Performing the steps of: A mask in which a desired pattern and an auxiliary pattern smaller in size than the desired pattern are arranged is illuminated so that the desired pattern is resolved and the resolution of the auxiliary pattern is suppressed. A database used for setting a mask pattern suitable for an exposure method of projecting the light having passed through the mask onto an object to be exposed via a projection optical system,
A database for displaying a minimum pitch of a mask pattern when an allowable range of at least one of a mask error enhancement factor and a line width error and a dimension of the desired pattern are input. A method for manufacturing a mask in which a desired pattern and an auxiliary pattern having a smaller dimension than the desired pattern are arranged,
Setting the dimensions of the desired pattern;
Setting the dimensions of the auxiliary pattern;
Relationship between at least one of a mask error enhancement factor, a line width error, a depth of focus, a location error of the auxiliary pattern, a size error of the auxiliary pattern, and an exposure amount with respect to the size of the desired pattern, and a size of the auxiliary pattern. Adjusting the size of the auxiliary pattern so that at least one of the sizes is within an allowable range. A mask in which a desired pattern and an auxiliary pattern having a smaller dimension than the desired pattern are arranged is divided into a plurality of types so that the desired pattern is resolved and the resolution of the auxiliary pattern is suppressed. The method of manufacturing a mask suitable for an exposure method of projecting light passing through the mask onto the object to be exposed through a projection optical system by illuminating with the light,
Setting the dimensions of the desired pattern;
Setting the dimensions of the auxiliary pattern;
Relationship between at least one of a mask error enhancement factor, a line width error, a depth of focus, a location error of the auxiliary pattern, a size error of the auxiliary pattern, and an exposure amount with respect to the size of the desired pattern, and a size of the auxiliary pattern. Adjusting the size of the auxiliary pattern so that at least one of the sizes is within an allowable range. The method according to claim 9, wherein the adjusting step changes the size within ± 10% of the size of the auxiliary pattern. 10. The method of claim 9, wherein the adjusting step reduces a size of the auxiliary pattern to improve the mask error enhancement factor, the location error, or the size error. The method according to claim 9, wherein the adjusting step increases a size of the auxiliary pattern to improve the line width error, the depth of focus, or the exposure amount. A mask in which a desired pattern and an auxiliary pattern smaller in size than the desired pattern are arranged is illuminated so that the desired pattern is resolved and the resolution of the auxiliary pattern is suppressed. A database used for setting a mask pattern suitable for an exposure method of projecting the light having passed through the mask onto an object to be exposed via a projection optical system,
When an allowable range of at least one of a mask error enhancement factor, a line width error, a depth of focus, a location error, a size error, and an exposure amount and the dimensions of the desired pattern are input, the dimensions of the auxiliary pattern are displayed. And the database. A mask in which a desired pattern and an auxiliary pattern having a size smaller than the desired pattern are arranged is divided into a plurality of types so that the desired pattern is resolved and the resolution of the auxiliary pattern is suppressed. An exposure method for projecting light passing through the mask onto the object to be exposed via a projection optical system by illuminating with light of
Adjusting the coherence factor of an illumination system that illuminates the mask such that the depth of focus is within an acceptable range. A mask in which a desired pattern and an auxiliary pattern having a size smaller than the desired pattern are arranged is divided into a plurality of types so that the desired pattern is resolved and the resolution of the auxiliary pattern is suppressed. An exposure method for projecting light passing through the mask onto the object to be exposed via a projection optical system by illuminating with light of
Exposing the object to be exposed a plurality of times while moving the object in the optical axis direction such that the depth of focus falls within an allowable range. 16. The method according to claim 15, wherein the mask has a dimension of a pattern adjacent to the desired pattern in the auxiliary pattern is smaller than a dimension of another auxiliary pattern. A mask in which a desired pattern and an auxiliary pattern having a smaller dimension than the desired pattern are arranged is divided into a plurality of types so that the desired pattern is resolved and the resolution of the auxiliary pattern is suppressed. The method of manufacturing a mask suitable for an exposure method of projecting light passing through the mask onto the object to be exposed through a projection optical system by illuminating with the light,
Setting the dimension of the desired pattern longer in a first direction than in a second direction orthogonal to the first direction;
Setting the dimension of the auxiliary pattern in the first direction to be longer than the dimension in a second direction orthogonal to the first direction. 18. The method of claim 17, wherein the desired pattern has a rectangular shape and the auxiliary pattern has a rectangular shape. A method for manufacturing a mask in which a desired pattern and an auxiliary pattern having a smaller dimension than the desired pattern are arranged,
A method comprising arranging a plurality of types of auxiliary patterns having different shapes corresponding to each of the shapes when a plurality of types of desired patterns having different shapes exist. A method for manufacturing a mask in which a desired pattern and an auxiliary pattern having a smaller dimension than the desired pattern are arranged,
A method comprising arranging a plurality of types of auxiliary patterns having different shapes corresponding to each of the shapes when a plurality of types of desired patterns having different shapes exist. A mask in which a desired pattern and an auxiliary pattern having a smaller dimension than the desired pattern are arranged is divided into a plurality of types so that the desired pattern is resolved and the resolution of the auxiliary pattern is suppressed. The method of manufacturing a mask suitable for an exposure method of projecting light passing through the mask onto the object to be exposed through a projection optical system by illuminating with the light,
A method comprising: arranging two or more types of auxiliary patterns having different shapes when there are a plurality of types of desired patterns having different shapes. A mask in which a desired pattern and an auxiliary pattern having a smaller dimension than the desired pattern are arranged is divided into a plurality of types so that the desired pattern is resolved and the resolution of the auxiliary pattern is suppressed. The method of manufacturing a mask suitable for an exposure method of projecting light passing through the mask onto the object to be exposed through a projection optical system by illuminating with the light,
Forming the desired patterns in first and second regions separated by a distance that does not interfere with each other;
Setting the auxiliary pattern as a different pattern for each of the first and second regions. Distance never said to interfere with each other, the resolution R, the wavelength of the exposure light lambda, when converted to the numerical aperture of the projection optical system in k ₁ when placed _{NA, k 1 = R / (} λ / NA) and 23. The method of claim 22, wherein the number is two or more. The minimum pitch of the first region is smaller than the minimum pitch of the second region,
23. The method of claim 22, wherein the step of setting the desired pattern includes increasing a size of the desired pattern in the second region. 25. An exposure method, comprising illuminating a mask manufactured by the method according to claim 24 with an illumination system optimized for the minimum pitch of the first region. 23. The method according to claim 22, wherein the step of forming the desired pattern corrects a shape of the desired pattern in the first region. 27. An exposure method, comprising illuminating a mask manufactured by the method according to claim 26 with an illumination system optimized for the minimum pitch of the second region. A mask in which a desired pattern and an auxiliary pattern smaller in size than the desired pattern are arranged is illuminated so that the desired pattern is resolved and the resolution of the auxiliary pattern is suppressed. A database used for setting a mask pattern suitable for an exposure method of projecting light having passed through the mask onto an object to be exposed via a projection optical system, and represents a relationship between a mask type and a contrast or a line width error. A database characterized by that: A mask in which a desired pattern and an auxiliary pattern having a smaller dimension than the desired pattern are arranged is divided into a plurality of types so that the desired pattern is resolved and the resolution of the auxiliary pattern is suppressed. The method of manufacturing a mask suitable for an exposure method of projecting light passing through the mask onto the object to be exposed through a projection optical system by illuminating with the light,
When two inserted auxiliary patterns overlap or are adjacent to each other, instead of providing the two auxiliary patterns, an auxiliary pattern whose center of gravity is the center of the two auxiliary patterns is arranged. A mask in which a desired pattern and an auxiliary pattern having a size smaller than the desired pattern are arranged is divided into a plurality of types so that the desired pattern is resolved and the resolution of the auxiliary pattern is suppressed. A method of manufacturing a mask suitable for an exposure method of projecting light passing through the mask onto the object to be exposed through a projection optical system by illuminating with light of
0 resolution R, the wavelength of the exposure light lambda, the numerical aperture of the projection optical system _{NA, k 1 = R / (} λ / NA) and to the minimum vertex distance between two dummy patterns to be inserted at k ₁ terms. When the number is 20 or less, instead of providing the two auxiliary patterns, one auxiliary pattern whose center of gravity is the center of the two auxiliary patterns is arranged. A mask in which a desired pattern and an auxiliary pattern having a size smaller than the desired pattern are arranged is divided into a plurality of types so that the desired pattern is resolved and the resolution of the auxiliary pattern is suppressed. A method of manufacturing a mask suitable for an exposure method of projecting light passing through the mask onto the object to be exposed through a projection optical system by illuminating with light of
A periodic pattern having at least two contact holes for aligning the desired pattern in any one of the two orthogonal directions, and an isolated pattern having no other contact holes aligned in any of the two orthogonal directions. Categorizing into
For the periodic pattern, arranging the auxiliary patterns in the aligned direction based on a period as an interval between the at least two contact holes;
A second step of arranging the auxiliary pattern based on an arbitrary period for the isolated pattern. Arranging the auxiliary pattern with respect to the periodic pattern,
Determining the size of the auxiliary pattern based on the minimum pitch of the desired pattern,
The method of claim 31, further comprising: determining a period of the auxiliary pattern based on the period and a hole diameter of the desired pattern. Determining the size of the auxiliary pattern,
If the minimum half pitch of the desired pattern, by converting the resolution R, the wavelength of the exposure light lambda, the numerical aperture of the projection optical system NA, in _{k 1 = R / (λ /} NA) and k ₁ when placed Determining whether it is less than 0.25x√2;
Setting the dimension of the auxiliary pattern to a predetermined ratio of the desired pattern, when determining that the determining step is small;
If the determining step determines not smaller The method of claim 32, wherein the a step of setting the dimension corresponding to the dimension of the auxiliary pattern to 0.25 or more by k ₁ terms. The method according to claim 33, wherein the predetermined ratio is not less than 70% and not more than 85%. Determining the cycle of the auxiliary pattern,
A first determining step of determining whether the hole diameter of the desired pattern is less than a first threshold,
33. The method of claim 32, further comprising terminating abnormally if the first determining step determines that the value is less than the first threshold. The method according to claim 35, wherein the first threshold is not less than 0.25 and not more than 0.25 * √2. A second determining step of determining whether the hole diameter of the desired pattern is equal to or greater than the first threshold and equal to or less than a second threshold when the first determining step determines that the hole diameter is not less than;
When the second determination step determines that the period is not less than the first threshold and not more than the second threshold, the period of the periodic pattern is R, the wavelength of the exposure light is λ, the numerical aperture of the projection optical system. the NA, when converted with _{k 1 = R / (λ /} NA) and k ₁ when placed, a third determination step of determining whether the whether the third threshold value or more,
36. The method according to claim 35, further comprising, if the third determining step determines that the auxiliary pattern is not equal to or greater than the third threshold value, arranging the auxiliary pattern at a cycle of the periodic pattern. And arranging the auxiliary pattern according to a value obtained by dividing the cycle of the periodic pattern by a predetermined number when the third determining step determines that the auxiliary pattern is equal to or greater than the third threshold value. 38. The method of claim 37. The first threshold value is 0.25 or more and 0.25 × √2 or less, the second threshold value is 0.25 × √2 or more and 0.5 or less, and the third threshold value is 1.0 or more１．０. 39. The method according to claim 37, wherein the number is 2 or less. If such second determination step determines that the not first threshold value or more second threshold value or less, the period of the periodic pattern when converted in k _1, determining whether the whether the fourth threshold value or more A fourth determining step of:
When said fourth step is equal to or greater than the fourth threshold value, the value obtained by subtracting the hole diameter of the desired pattern from the converted value of the period of the periodic pattern in k ₁ is a fifth threshold value A fifth determining step of determining whether or not:
The method according to claim 37, wherein the auxiliary pattern is not inserted if it is determined in the fifth step that the difference is equal to or less than the fifth threshold value. If such second determination step determines that the not first threshold value or more second threshold value or less, the period of the periodic pattern when converted in k _1, determining whether the whether the fourth threshold value or more A fourth determining step of:
38. The method according to claim 37, further comprising the step of arranging the auxiliary pattern at a period of the periodic pattern when the fourth step determines that the auxiliary pattern is not equal to or larger than the fourth threshold value. The first threshold is 0.25 or more and 0.25 × √2 or less, the second threshold is 0.25 × 以上 2 or more and 0.5 or less, and the fourth threshold is 0.5 × √. 42. The method according to claim 40, wherein the value is 2 or more and 1.0 or less. Arranging the auxiliary pattern with respect to the isolated pattern,
Determining whether a periodic pattern exists within a predetermined distance from the isolated pattern,
A step of arranging the auxiliary pattern in accordance with the cycle of the periodic pattern when it is determined that the determining step exists; and
32. The method according to claim 31, further comprising, if it is determined that the determining step does not exist, setting the size of the isolated pattern to a half pitch and arranging the auxiliary pattern. The periodic pattern includes a first periodic pattern having periodicity in a first direction, and a second pattern having periodicity in a second direction parallel to the first direction. In the case where no other contact hole exists in a direction perpendicular to the first and second directions, none of the contact holes constituting the second periodic pattern
A step of arranging the auxiliary pattern between the first and second periodic patterns, with the first and second periodic pattern intervals in a direction perpendicular to the first and second directions as a period; 32. The method of claim 31, wherein: When none of the contact holes constituting the periodic pattern has another contact hole in a second direction perpendicular to the first direction in which the periodic pattern has periodicity,
Between the periodic pattern and the isolated pattern, using the interval between the first direction with respect to the second direction and a third direction parallel to the first direction and passing through the isolated pattern as a cycle, The method of claim 31, further comprising arranging the auxiliary pattern. A mask in which a desired pattern and an auxiliary pattern having a smaller dimension than the desired pattern are arranged is divided into a plurality of types so that the desired pattern is resolved and the resolution of the auxiliary pattern is suppressed. The method of manufacturing a mask suitable for an exposure method of projecting light passing through the mask onto the object to be exposed through a projection optical system by illuminating with the light,
A part of the desired pattern is arranged at each grid-like point in a predetermined area, and the number of patterns at a distance of twice or less the interval between the grid points from the predetermined area is 3 or less, and Is characterized in that, if the pattern is shifted from the point on the grid within 20% of the interval between the grid points, the auxiliary pattern is inserted by assuming that the shifted pattern is arranged in a grid. And how. A program for executing the method according to any one of claims 1 to 4, 6, 9 to 11, 17 to 24, 26, and 33 to 46. A mask formed by the method according to any one of claims 1 to 4, 6, 9 to 11, 17 to 24, 26, and 33 to 46. A first desired pattern;
A first auxiliary pattern which is arranged near the first desired pattern, has a smaller size than the first desired pattern, and has a shape substantially similar to the first pattern;
A second desired pattern different in shape from the first desired pattern;
A second auxiliary pattern which is arranged near the second desired pattern, has a smaller size than the second desired pattern, and has a shape substantially similar to the second pattern. Mask. A plurality of the first auxiliary patterns are arranged in a first cycle around the first desired pattern, and a second auxiliary pattern is arranged around a second desired pattern around the second desired pattern. 50. The mask according to claim 49, wherein a plurality of the masks are arranged in a cycle. The mask according to claim 44.5 or 50, wherein the first desired pattern and the second desired pattern are patterns for contact holes. Exposing the object to be exposed using the mask according to any one of claims 48 to 51,
Performing a predetermined process on the exposed object to be exposed.

Images