JP2019184650A - Exposure apparatus, exposure method, and article manufacturing method - Google Patents

Abstract

To provide an exposure apparatus that is advantageous in improving line width uniformity.SOLUTION: An exposure apparatus that irradiates a mask with light from an illumination optical system, and projects a pattern of the mask onto a substrate via the projection optical system comprises: a mask stage which holds and drives the mask; a substrate stage which holds and drives the substrate; and a control part which controls drive of the mask stage and the substrate stage, in which the control part vibrates the mask stage or the substrate stage in a direction parallel with the surface of the substrate based on a difference of line width between a first pattern which is transferred on the substrate by using the exposure apparatus and a second pattern having a longer direction of pattern different from the first pattern, and projects the pattern of the mask onto the substrate.SELECTED DRAWING: Figure 2

Description

The present invention relates to an exposure apparatus, an exposure method, and an article manufacturing method.

  In a lithography process that is one of processes for manufacturing articles such as semiconductor devices and liquid crystal display devices, an exposure apparatus that transfers a mask pattern to an exposure region on a substrate through a projection optical system is used. In recent years, with the miniaturization of the above-described articles, there has been an increasing demand for an exposure apparatus to improve the uniformity of a line width (Critical Dimension: CD) of a pattern transferred to a substrate.

  As a method for improving the line width uniformity, in Japanese Patent Application Laid-Open No. H11-260260, control is performed by moving the substrate holder along the Z direction that is substantially perpendicular to the image surface of the projection system after the start of exposure and before the end of exposure. A method of introducing a specified amount of contrast loss is disclosed. Patent Document 2 discloses a method of moving or vibrating a periodic pattern image and an object to be exposed relative to the optical axis direction of a projection optical system during exposure.

Japanese Patent Laid-Open No. 2005-86212 JP-A-6-29182

  However, the methods of Patent Document 1 and Patent Document 2 move or vibrate the projection optical system or the substrate in the Z direction during exposure, so that the image of the transfer pattern can be applied regardless of which direction the longitudinal direction of the pattern is. The influence caused by defocusing can be evenly distributed.

  An object of the present invention is, for example, to provide an exposure apparatus that is advantageous in terms of improving line width uniformity.

  In order to solve the above-described problems, the present invention is an exposure apparatus that irradiates a mask with light from an illumination optical system and projects a mask pattern onto a substrate via a projection optical system, and holds and drives the mask. A mask stage that holds and drives the substrate, and a control unit that controls the driving of the mask stage and the substrate stage. The control unit transfers the first transferred onto the substrate using the exposure apparatus. Based on the difference in line width between the pattern and the second pattern in which the longitudinal direction of the pattern is different from the first pattern, the mask stage or substrate stage is vibrated in a direction parallel to the surface of the substrate, and the mask pattern is applied to the substrate. Projecting.

  According to the present invention, for example, an exposure apparatus that is advantageous in terms of improving the line width uniformity can be provided.

1 is a perspective view showing a schematic configuration of an exposure apparatus according to a first embodiment. It is a side view which shows schematic structure of the exposure apparatus which concerns on 1st Embodiment. It is a figure explaining a vibration part and its process. It is a flowchart which shows the creation process of the sensitivity data which concerns on 1st Embodiment. It is a figure which shows an example of the measurement result by a vibration measuring device. It is a figure which shows an example of the relationship between the vibration measurement result in process S1, and the line | wire width measurement result in process S2. It is a figure which shows an example of the measurement result by a vibration measuring device when an object unit is vibrated by a vibration drive part. It is a figure which shows an example of the relationship between the vibration measurement result in process S4, and the line | wire width measurement result in process S5. It is a figure which shows an example of sensitivity data. It is a flowchart which shows the exposure process which equalizes the line | wire width of the pattern which concerns on 1st Embodiment. 5 is a diagram illustrating an example of a transfer pattern on a photosensitive substrate P. FIG. It is a figure which shows an example of the control based on an excitation condition. It is a figure which shows an example of the transfer pattern to the photosensitive board | substrate which performed control based on the vibration conditions.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
[First Embodiment]

  1 and 2 are a perspective view and a side view, respectively, showing a schematic configuration of an exposure apparatus according to the first embodiment. Note that a part of FIG. 1 is omitted. In this figure, an exposure apparatus 100 includes a mask stage MST that holds and drives a mask M on which a pattern is formed, a substrate stage PST that holds and drives a photosensitive substrate P, an illumination optical system IL, and a projection optical system. PL, the main control part 60, the vibration measuring device VIM, and the vibration excitation part VI are provided.

  The mask M held on the mask stage MST and the photosensitive substrate P held on the substrate stage PST are arranged in a conjugate positional relationship via the projection optical system PL. The exposure apparatus 100 of this embodiment is configured as a so-called mirror scan type exposure apparatus having a large concave mirror. In the following, the height direction of the photosensitive substrate P is the Z-axis direction, the direction perpendicular to the Z-axis direction is the synchronous movement direction of the mask M and the photosensitive substrate P is the Y-axis direction (scanning direction), the Z-axis direction and the Y-axis direction. An orthogonal direction is taken as an X-axis direction. The directions around the X axis, the Y axis, and the Z axis are the θX direction, the θY direction, and the θZ direction.

  The illumination optical system IL illuminates the mask M supported by the mask stage MST with the exposure light EL. The illumination optical system IL can include, for example, a light source, an elliptical mirror, a condenser lens, a limiting slit plate, and a mirror. The light source includes an electromotive high pressure mercury lamp. The elliptical mirror condenses the light beam emitted from the light source. The condenser lens expands and collimates the light beam collected by the elliptical mirror. The limiting slit plate is arranged at a position conjugate with the mask M in order to cut a portion of the parallel light flux from the condenser lens that is not used as irradiation light to the mask M and define an illumination area having a predetermined area. The mirror reflects the light flux from the limiting slit plate and irradiates the mask M with the slit illumination light flux.

  The exposure light EL generated by the illumination optical system IL is, for example, a far-field such as KrF excimer laser light (wavelength 248 nm) in addition to the ultraviolet emission lines (g-line, h-line, i-line) emitted from the mercury lamp. There is ultraviolet light (DUV light). Alternatively, vacuum ultraviolet light (VUV light) such as ArF excimer laser light (wavelength 193 nm) and F2 laser light (wavelength 157 nm) may be used. The illumination optical system IL can be configured as a so-called Koehler illumination system.

  The exposure light EL that has passed through the mask M enters the projection optical system PL. The projection optical system PL projects and transfers the mask pattern of the mask M illuminated with the exposure light EL onto the photosensitive substrate P held on the substrate stage PST. An image of a mask pattern existing in the illumination area of the mask M is formed on the photosensitive substrate P. As shown in FIG. 2, the projection optical system PL can form an image of the mask pattern of the mask M on the photosensitive substrate P via the trapezoidal mirror 52, the convex mirror 53, and the concave mirror 54, for example. The projection area of the projection optical system PL onto the photosensitive substrate P is set to a predetermined shape (for example, an arc shape).

  Mask stage MST includes a mask stage drive unit MSTD. The mask stage MST is configured to scan the mask M with respect to the illumination optical system IL, has a long stroke in the Y-axis direction (scanning direction), and an appropriate stroke in the X-axis direction orthogonal to the scanning direction. Have. The mask stage MST can include a suction unit (not shown) for holding the mask M. The suction part is connected to a vacuum device (not shown), and the mask M is vacuum-sucked and held by the suction part. The mask stage drive unit MSTD drives the mask stage MST in the X axis direction and the Y axis direction. The mask stage driving unit MSTD can be controlled by a main control unit 60 described later.

  The substrate stage PST for driving the photosensitive substrate P includes a substrate stage drive unit PSTD. The substrate stage PST for driving the photosensitive substrate P has a substrate holder for holding the photosensitive substrate P. As with mask stage MST, substrate stage PST has a scanning stroke in the Y-axis direction (scanning direction) and a stroke for step movement in the X-axis direction orthogonal to the scanning direction. Further, the substrate stage PST is configured to be movable in the Z-axis direction and the θX, θY, and θZ directions. The substrate stage drive unit PSTD drives the substrate stage PST in the X axis direction and the Y axis direction. The substrate stage driving unit PSTD can be controlled by the main control unit 60.

  The main controller 60 includes, for example, a CPU and a memory, and controls the entire exposure apparatus 100. The main control unit 60 controls each part of the exposure apparatus 100 to perform exposure processing for exposing the photosensitive substrate P.

  The vibration measuring instrument VIM is provided in each part of the mask stage MST, the substrate stage PST, the illumination optical system IL, and the projection optical system PL, and measures the vibration of each part. The vibration measuring device VIM measures, for example, vibrations of the respective portions (that is, amplitudes in the X direction) at positions in the respective Y directions when the mask pattern is transferred to the photosensitive substrate P by the synchronous scanning exposure in the Y direction.

  The excitation unit VI is provided in each part of the mask stage MST, the substrate stage PST, the illumination optical system IL, and the projection optical system PL, and applies vibration to each part. The vibration unit VI can generate vibration in the X direction or the Y direction with respect to a unit (target unit) that is a vibration target. Further, for example, the optical member of the projection optical system can be vibrated in an arbitrary direction so that the image projected onto the substrate by the projection optical system PL vibrates in the X direction or the Y direction. It is also possible to vibrate the wedge-shaped optical member between the mask M and the trapezoidal mirror 52 in the Z direction.

  FIG. 3 is a diagram for explaining the vibration unit VI and its processing. The vibration unit VI may include a data storage unit DS, a vibration amount calculation unit CALC, a vibration control unit VIC, and a vibration drive unit VID. The data storage unit DS stores data necessary for obtaining the amount of excitation such as the measurement result of the line width of the pattern transferred onto the photosensitive substrate P and the measurement result by the vibration measuring instrument VIM, and generates sensitivity data. To do. Details of the sensitivity data will be described later. The excitation amount calculation unit CALC obtains the excitation amount necessary for making the line width of the pattern transferred to the photosensitive substrate P close to uniform (target line width) based on the data stored in the data storage unit DS. . The vibration control unit VIC controls the vibration driving unit VID based on the vibration amount obtained by the vibration amount calculation unit CALC. The vibration drive unit VID drives the target unit to vibrate in the X direction or the Y direction, which is a plane direction perpendicular to the optical axis of the illumination optical system, according to control from the vibration control unit VIC. The data storage unit DS, the excitation amount calculation unit CALC, and the vibration control unit VIC may be provided in the main control unit 60.

  Next, sensitivity data generation processing in the data storage unit DS will be described. Note that, in all the following processes, FIG. 4 is a flowchart showing the sensitivity data creation process according to the first embodiment. In step S1, the vibration measuring device VIM calculates the vibration of each target unit at the position in each Y direction (that is, the amplitude in the X direction) when the mask pattern is transferred to the photosensitive substrate P by Y-direction synchronous scanning exposure. taking measurement. FIG. 5 is a diagram illustrating an example of a measurement result by the vibration measuring device VIM. The vibration measurement result is stored in the data storage unit DS. Here, the target unit is not excited by the vibration drive unit VID.

  In step S2, the line width at each position in the Y direction of the pattern transferred onto the photosensitive substrate P is measured by a measuring instrument (for example, a long dimension measuring instrument), and the measurement result of the line width is the measurement result by the vibration measuring instrument VIM. Similarly, it is stored in the data storage unit DS. The long dimension measuring instrument provided outside may be used. The same applies to the following steps. FIG. 6 is a diagram illustrating an example of the relationship between the vibration measurement result in step S1 and the line width measurement result in step S2. Such information is stored in the data storage unit DS.

  In step S3, the vibration control unit VIC controls the vibration driving unit VID and applies vibration to the target unit when transferring the mask pattern to the photosensitive substrate P by synchronous scanning exposure in the Y direction. The vibration control unit VIC controls the vibration drive unit VID according to the frequency, amplitude, and direction of vibration at each Y position.

  In step S4, the vibration measuring device VIM is configured to transfer the mask pattern to the photosensitive substrate P by synchronous scanning exposure in the Y direction in a state where the target unit is vibrated by the vibration driving unit VID. Measure the vibration of the target unit. FIG. 7 is a diagram illustrating an example of a measurement result by the vibration measuring device VIM when the target unit is vibrated by the vibration driving unit VID. The vibration measurement result when this vibration is applied is also stored in the data storage unit DS.

  In step S5, the line width at each position in the Y direction of the pattern transferred onto the photosensitive substrate P in a state where the target unit is vibrated by the vibration drive unit VID is measured by the measuring device, and the measurement result of the line width is stored as data. Stored in the part DS. FIG. 8 is a diagram illustrating an example of the relationship between the vibration measurement result in step S4 and the line width measurement result in step S5. Such information is stored in the data storage unit DS.

  In step S6, the measurement result of the vibration measuring device VIM in step S1, the measurement result of the line width in step S2, the measurement result of the vibration measuring device VIM in step S4, and the measurement result of the line width in step S5 are used. To obtain sensitivity data of vibration and line width. FIG. 9 is a diagram illustrating an example of sensitivity data. In FIG. 9, the amplitude in a specific X direction and the line width measurement result in that state are set as the starting point (0), the increase in amplitude in the X direction from the starting point is set on the horizontal axis, and the increase in amplitude on the horizontal axis. The line width measurement results corresponding to are shown on the vertical axis. Here, if the increase in amplitude in the X direction is x and the line width measurement result is y, it can be expressed as a function of y = f (x). Further, by obtaining an inverse function x = g (y) for this function, an increase in the amplitude in the X direction (vibration amount) necessary for obtaining a desired line width measurement result can be obtained.

  In the present embodiment, the generation of sensitivity data focusing on the amplitude of vibration has been described as an example. However, sensitivity data can be similarly generated regarding the frequency and direction of vibration in addition to the amplitude.

  Next, an exposure process for making the line width of the pattern transferred to the photosensitive substrate P uniform will be described. FIG. 10 is a flowchart showing an exposure process for making the line width of the pattern uniform according to the first embodiment. In step S11, the vibration measuring device VIM calculates the vibration of each target unit (that is, the amplitude in the X direction) at the position in each Y direction when the mask pattern is transferred to the photosensitive substrate P by Y-direction synchronous scanning exposure. taking measurement. The vibration measurement result at each position in the Y direction measured by the vibration measuring instrument VIM is stored in the data storage unit DS. This measurement result is the same as the measurement result shown in FIG.

  In step S12, the line width at each position in the Y direction of the pattern transferred onto the photosensitive substrate P is measured by a measuring instrument (for example, a long dimension measuring instrument), and the measurement result of the line width is the measurement result by the vibration measuring instrument VIM. As well as the data storage unit DS. The long dimension measuring instrument provided outside may be used. The same applies to the following steps. The relationship between the vibration measurement result stored in the data storage unit DS in step S11 and the line width measurement result stored in the data storage unit DS in step S12 is the same as that in FIG. FIG. 11 is a diagram illustrating an example of a transfer pattern of the photosensitive substrate P. In FIG. 11, a plurality of regions A including four pattern directions are repeatedly formed in one shot region S of the photosensitive substrate P. The directions in which the four patterns included in the region A extend (longitudinal direction of the pattern) are different. In FIG. 11, H patterns 11-1, V patterns 11-2, S patterns 11-3, and T patterns 11-4 are shown as transfer patterns in different pattern directions. The dotted line portion of the H pattern 11-1 indicates the target line width, and the solid line portion of the H pattern 11-1 indicates the line width measurement result stored in the data storage unit DS. In FIG. 11, the V pattern 11-2, the S pattern 11-3, and the T pattern 11-4 have the target line width, whereas only the line width of the H pattern 11-1 is smaller than the target line width. . Here, the target line width in any pattern is the same.

  In step S13, the excitation amount calculation unit CALC is necessary to bring the line width closer to the target line width based on the difference between the result of measuring the line width of the transfer pattern formed on the photosensitive substrate P and the target line width. The amount of vibration that becomes is obtained. The vibration amount calculation unit CALC calculates the vibration amount, and then uses the sensitivity data stored in the data storage unit DS to use the vibration frequency at each position in the Y direction that satisfies the required vibration amount. The amplitude or the direction of excitation (excitation conditions) is determined. For example, when the mask stage MST is vibrated, it can be vibrated at a frequency of about 20 Hz in the X direction and about 30 Hz in the Y direction. When the substrate stage PST is vibrated, it can be vibrated at a frequency of 10 to 12 Hz in each of the X direction and the Y direction. The excitation amount calculation unit CALC outputs the determined excitation condition to the vibration control unit VIC.

  In step S14, the vibration control unit VIC controls the vibration drive unit VID based on the vibration condition output from the vibration amount calculation unit CALC, and projects the mask pattern onto the photosensitive substrate P using the projection optical system. To do. Specifically, the vibration control unit VIC controls the vibration drive unit VID based on the excitation condition when the mask pattern is projected onto the photosensitive substrate P by synchronous scanning exposure in the Y direction. Thereby, the target unit is vibrated. Note that at least one target unit to be vibrated may be used. FIG. 12 is a diagram illustrating an example of control based on the excitation condition. In FIG. 12, the excitation is controlled by the amplitude. Compared with the vibration measurement result of FIG. 6, it can be seen that the vibration is applied in the X direction at a predetermined position in the Y direction. This also makes the line width in the X direction uniform.

  FIG. 13 is a diagram illustrating an example of a transfer pattern onto the photosensitive substrate P that has been controlled based on the excitation condition. Compared with the H pattern 11-1 in FIG. 11, the line width of the H pattern 13-1 in FIG. 13 is corrected to an ideal line width. At this time, since vibration in the X direction is applied, the line widths of the S pattern 13-3 and the T pattern 13-4 are affected, but the average line width is stabilized. As described above, according to the present embodiment, the line width can be corrected in a specific pattern direction, and the line width can be made uniform.

  In the present embodiment, the line width in the X direction is corrected as an example, but the line width in the Y direction can also be corrected. Moreover, it is also possible to correct line widths such as the line widths of the S pattern 13-3 and the T pattern 13-4 by combining the excitation in the X direction and the Y direction.

  Furthermore, in this embodiment, the vibration stage VI is provided in the mask stage MST, the substrate stage PST, the illumination optical system IL, and the projection optical system PL, but at least one unit is controlled by the vibration section VI. Thus, the effect of the present invention can be obtained. Moreover, the effect of this invention can be acquired by providing the vibration part VI in at least any one unit. The mask stage MST or the substrate stage PST may be vibrated by using the mask stage driving unit MSTD or the substrate stage driving unit PSTD as the vibration driving unit VID. When the mask stage drive unit MSTD or the substrate stage drive unit PSTD is used as the vibration drive unit VID, the main control unit 60 is used as the data storage unit DS, the excitation amount calculation unit CALC, and the vibration control unit VIC. In this case, it is not necessary to provide a new mechanism.

(Embodiment related to article manufacturing method)
The article manufacturing method according to the present embodiment is suitable for manufacturing articles such as semiconductor devices, display devices, and elements having a fine structure. For example, the article is an electric circuit element, an optical element, a MEMS, a recording element, a sensor, or a mold. Examples of the electric circuit elements include volatile or nonvolatile semiconductor memories such as DRAM, SRAM, flash memory, and MRAM, and semiconductor elements such as LSI, CCD, image sensor, and FPGA. Examples of the mold include an imprint mold. In the method for manufacturing an article according to the present embodiment, a latent image pattern is formed on the photosensitive agent applied to the substrate using the above-described exposure apparatus (a step of exposing the substrate), and the latent image pattern is formed in this step. Developing the substrate. Further, the manufacturing method includes other well-known steps (oxidation, film formation, vapor deposition, doping, planarization, etching, resist stripping, dicing, bonding, packaging, and the like). As the substrate, glass, ceramics, metal, semiconductor, resin, or the like is used, and a member made of a material different from the substrate may be formed on the surface as necessary. Specific examples of the substrate include a silicon wafer, a compound semiconductor wafer, and quartz glass.

(Other embodiments)
As mentioned above, although embodiment of this invention has been described, this invention is not limited to these embodiment, A various change is possible within the range of the summary.

DESCRIPTION OF SYMBOLS 100 Exposure apparatus M Mask MST Mask stage P Photosensitive substrate PST Substrate stage VI Excitation part VIC Vibration control part VID Vibration drive part VIM Vibration measuring instrument

Claims (15)

An exposure apparatus that irradiates a mask with light from an illumination optical system and projects a pattern of the mask onto a substrate via a projection optical system,
A mask stage for holding and driving the mask;
A substrate stage for holding and driving the substrate;
A control unit for controlling the driving of the mask stage and the substrate stage,
The control unit is configured to determine the mask stage based on a difference in line width between a first pattern transferred onto the substrate using the exposure apparatus and a second pattern having a pattern longitudinal direction different from the first pattern. Alternatively, the exposure apparatus characterized in that the substrate stage is vibrated in a direction parallel to the surface of the substrate to project the mask pattern onto the substrate.   The control unit vibrates the mask stage or the substrate stage so as to vibrate in a first direction parallel to the surface of the substrate or in a second direction perpendicular to the first direction. Item 4. The exposure apparatus according to Item 1.   The control unit, based on the measurement result of the vibration of the mask stage or the substrate stage in a state where the vibration is not driven and the first information which is the line width of the pattern transferred onto the substrate, The exposure apparatus according to claim 1, wherein an amount of vibration applied to the substrate stage is obtained.   The control unit calculates the amount of excitation based on the measurement result of vibration of the mask stage or the substrate stage in a vibration driven state and second information that is a line width of a pattern transferred onto the substrate. The exposure apparatus according to claim 1, wherein the exposure apparatus is obtained.   5. The exposure according to claim 1, wherein the control unit generates data for obtaining the amount of excitation using the first information and the second information. 6. apparatus.   The exposure apparatus according to claim 1, wherein the control unit determines a frequency, an amplitude, or a direction of vibration of the mask stage or the substrate stage. An exposure apparatus that irradiates a mask with light from an illumination optical system and transfers a pattern of the mask onto a substrate via a projection optical system,
A mask stage for holding and driving the mask;
A substrate stage for holding and driving the substrate;
And at least one excitation unit that applies vibration to any part of the exposure apparatus,
The at least one vibration unit is based on a difference in line width between a first pattern transferred onto the substrate using the exposure apparatus and a second pattern having a longitudinal direction different from that of the first pattern. , Each part of the exposure apparatus is vibrated so that a projection image of the mask pattern projected by the projection optical system vibrates in a direction parallel to the surface of the substrate, and the mask pattern is projected onto the substrate. An exposure apparatus characterized by that.   The at least one excitation unit vibrates such that each unit vibrates in a first direction parallel to a surface of the substrate or in a second direction perpendicular to the first direction. 8. The exposure apparatus according to 7.   The at least one excitation unit is configured to transfer each unit based on the measurement result of the vibration of each unit in a state in which the unit is not driven by vibration and the third information that is the line width of the pattern transferred onto the substrate. The exposure apparatus according to claim 7, wherein the amount of vibration is calculated.   The at least one excitation unit obtains the amount of excitation based on a measurement result of vibration of each unit in a vibration-driven state and fourth information that is a line width of a pattern transferred onto the substrate. The exposure apparatus according to any one of claims 7 to 9, wherein   The said at least 1 vibration part produces | generates the data for calculating | requiring the said vibration amount using said 3rd information and said 4th information, The any one of Claim 7 thru | or 10 characterized by the above-mentioned. The exposure apparatus described in 1.   12. The exposure apparatus according to claim 7, wherein the at least one excitation unit obtains the frequency, amplitude, or direction of vibration of each unit.   The at least one excitation unit is provided in the illumination optical system, the projection optical system, the mask stage, or the substrate stage, according to any one of claims 7 to 12. Exposure device. An exposure method for irradiating a mask with light from an illumination optical system and projecting the pattern of the mask onto a substrate via a projection optical system,
Measuring the line width of the first pattern transferred onto the substrate and the line width of the second pattern in which the longitudinal direction of the pattern is different from the first pattern;
Based on the difference between the measured line widths of the first and second patterns, the illumination optical system, the projection optical system, the mask or the substrate is vibrated in a direction parallel to the surface of the substrate, and the mask Projecting the pattern onto the substrate. An exposure method comprising: Forming a pattern on a substrate using the exposure apparatus according to claim 1;
Developing the substrate on which the pattern is formed in the step;
An article manufacturing method comprising:

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