JP6955344B2 - Imprint equipment and article manufacturing method - Google Patents

Description

The present invention relates to an imprint technique.

Imprint technology cures the imprint material with the mold in contact with the imprint material placed on the substrate, and separates the mold from the cured imprint material to create a mold pattern on the substrate. It is a transfer technology.

When manufacturing a semiconductor chip using imprint technology, it is required to accurately align the substrate and the mold (hereinafter referred to as "alignment") when the mold is brought into contact with the imprint material on the substrate. NS. As an alignment in an imprinting apparatus, a so-called die-by-die method is known in which alignment is performed by detecting a mark formed on a mold and a mark formed for each shot region of a substrate. In this method, the relative position between the substrate and the mold is feedback-controlled by the calculated position deviation.

In the imprint device, it is assumed that the gap between the mold and the substrate when the mold is brought into contact with the imprint material on the substrate is 1 μm or less, and the imprint material filled in this gap is viscoelastic. It has viscoelasticity, which has both elastic properties. When the mold is brought into contact with the imprint material on the substrate and the mold and the substrate are moved relatively for alignment, a force acts between the mold and the substrate due to the viscoelasticity of the imprint material. Since this force also acts on the pattern of the mold, the fine pattern may be deformed. The relative movement amount of the mold and the substrate at the time of alignment may differ for each shot area. Therefore, the amount of deformation of the mold pattern due to the force acting between the mold and the substrate varies from shot region to shot region. For example, in imprinting of a semiconductor chip, defective chips may occur and the yield may decrease.

Patent Document 1 discloses an imprinting apparatus that aligns a mold and a substrate while vibrating the imprinting material in order to reduce the viscoelasticity of the imprinting material.

Japanese Unexamined Patent Publication No. 2015-149315

However, the vibration applied to reduce the viscoelasticity of the imprint material affects the detection of marks, which may reduce the accuracy of alignment.

In view of the above problems, the present invention provides a more advantageous technique in terms of alignment accuracy.

According to one aspect of the present invention, it is an imprinting apparatus in which a mold is brought into contact with an imprint material on a substrate to form a pattern on the imprint material, and the mold and the imprint material are in contact with each other. The imprint material includes a vibrating unit that vibrates the imprint material and an imaging element that converts light from marks provided on the mold and the substrate into electrical signals. Adjustment that adjusts the frequency of the vibration given by the vibration unit according to the charge accumulation time of the image pickup element and the detection unit that detects the positional deviation between the mold and the substrate in a state where vibration is applied to the An imprinting apparatus characterized by having a portion is provided.

According to the present invention, a technique advantageous in terms of alignment accuracy is provided.

The figure which shows the structure of the imprinting apparatus in embodiment. The control block diagram of the board stage. The figure explaining the influence of the combination of the frequency of vibration given by a vibrating part and the charge accumulation time of an image sensor. The figure explaining the article manufacturing method in embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the following embodiments merely show specific examples of the embodiment of the present invention, and the present invention is not limited to the following embodiments. In addition, not all combinations of features described in the following embodiments are essential for solving the problems of the present invention.

Hereinafter, the imprint device according to the embodiment will be described. The imprinting apparatus brings the imprint material supplied on the substrate into contact with the mold and gives the imprint material energy for curing to form a pattern of the cured product on which the pattern of the mold is transferred. ..

As the imprint material, a curable composition (sometimes referred to as an uncured resin) that cures when energy for curing is applied is used. Electromagnetic waves, heat, etc. can be used as the energy for curing. The electromagnetic wave may be, for example, light whose wavelength is selected from the range of 10 nm or more and 1 mm or less, for example, infrared rays, visible rays, ultraviolet rays, and the like. The curable composition can be a composition that is cured by irradiation with light or by heating. Of these, the photocurable composition that is cured by irradiation with light contains at least a polymerizable compound and a photopolymerization initiator, and may further contain a non-polymerizable compound or a solvent, if necessary. The non-polymerizable compound is at least one selected from the group of sensitizers, hydrogen donors, internal release mold release agents, surfactants, antioxidants, polymer components and the like. The imprint material may be arranged on the substrate in the form of droplets or islands or films formed by connecting a plurality of droplets by the imprint material supply device. The viscosity of the imprint material (viscosity at 25 ° C.) can be, for example, 1 mPa · s or more and 100 mPa · s or less. As the material of the substrate, for example, glass, ceramics, metal, semiconductor, resin and the like can be used. If necessary, a member made of a material different from the substrate may be provided on the surface of the substrate. The substrate is, for example, a silicon substrate, a compound semiconductor substrate, or quartz glass.

FIG. 1 is a diagram showing a configuration of an imprint device according to the present embodiment. The main body 1 of the imprint device is installed on the floor via a tripod or quadruped vibration isolation mechanism 2 using an air spring or the like. The substrate 3 (wafer) is held on the substrate stage 4 by a substrate chuck (not shown). The board stage 4 has sufficient strokes in the X and Y directions so that the entire surface of the board 3 can be imprinted and the board 3 can be moved to a replacement position where the board 3 is loaded and unloaded with a board replacement hand (not shown). ing.

Although the substrate stage 4 is simply shown as one box and wheels in FIG. 1, it may actually have the following structure. As the substrate stage 4, a coarse movement stage having long strokes in the X and Y directions is equipped with a fine movement stage having a short stroke and high positioning accuracy. The configuration of the substrate stage 4 is not limited to this, and a high-precision positioning stage generally used for a substrate stage for a semiconductor exposure apparatus can be used.

The position of the substrate stage 4 in the X direction is measured by a laser interferometer 5 provided on the main body 1 and a reflector (not shown) provided on the substrate stage 4 for reflecting the laser beam. Similarly, a laser interferometer that measures the Y direction is also provided. For the position measurement of the substrate stage 4, an encoder system including a scale substrate provided on the main body 1 and an optical element provided on the substrate stage 4 may be used.

The dispenser 7 as the imprint material supply device provided in the main body 1 supplies the imprint material used in the imprint process onto the substrate 3.

The mold 8 on which the pattern is formed is held by the mold holding portion 9 (imprint head). The mold holding portion 9 can move the mold 8 in the Z direction while holding the mold 8. Here, as shown in FIG. 1, the direction in which the mold 8 held by the mold holding portion 9 is brought closer to or further away from the substrate 3 is the Z direction. Further, the directions orthogonal to the Z direction and parallel to the surface of the substrate 3 are defined as the X direction and the Y direction.

The relative positions of the substrate 3 in the directions (X and Y directions) parallel to the surface of the substrate 3 with respect to the mold 8 are detected by the detection unit 10 provided in the main body 1. The alignment mark is transferred to the position of each shot region on the substrate 3 by the previous processing step. The mold 8 is also provided with an alignment mark corresponding to this. The detection unit 10 irradiates the mold 8 and the substrate 3 with the alignment light, and detects the alignment marks of both by the scope 101. The scope 101 may detect an image of the alignment mark of the mold 8 and the alignment mark of the substrate 3, respectively, or may detect moire fringes caused by the alignment mark of the mold 8 and the alignment mark of the substrate 3. good. The scope 101 includes an image sensor 102 that converts light from alignment marks provided on each of the mold 8 and the substrate 3 into an electric signal. The control unit C calculates the relative positional deviation between the mold 8 and the substrate 3 by performing image processing on the detection result of the scope 101. The cured portion 11 generates ultraviolet rays for curing the imprint material. The generated ultraviolet rays are applied to the imprint material on the substrate via the mold 8.

FIG. 2 is a control block diagram of the substrate stage 4. The position control of the board stage 4 is performed by the board stage control unit 12. The board stage control unit 12 has a feedback control system that feeds back the deviation obtained by subtracting the stage position measured by the laser interference meter 5 from the stage position command sent from the main control unit 14. The positional deviation between the mold 8 and the substrate 3 output from the detection unit 10 is input to the stage position correction calculator 13 and sent to the substrate stage control unit 12 as a stage position correction signal. In the board stage control unit 12, the control calculation is performed with the above-mentioned stage position command plus the stage position correction signal as the target position of the board stage 4. The mechanism for calculating the stage position correction signal by the detection unit 10 and the stage position correction calculator 13 is called alignment feedback control. The control command resulting from the control calculation is sent to the actuator that drives the substrate stage 4 and becomes a driving force to position and control the substrate stage 4. Since these control systems perform complicated calculations, they are configured by a digital computer.

Next, each operation during the imprint process will be described. The board stage 4 moves to a replacement position of the board 3, and the board 3 is mounted on a board chuck (not shown) on the board stage 4 by a board replacement hand (not shown). The control unit C moves the substrate stage 4 so that the shot region, which is the target region for imprint processing on the substrate 3, is below the dispenser 7, and the imprint material is placed on the shot region of the substrate 3 by the dispenser 7. Supply. After moving the substrate stage 4 so that the shot region is below the mold 8, the control unit C lowers the mold 8 by the mold holding unit 9 and brings the mold 8 into contact with the imprint material on the substrate. By this contact, the gap between the mold 8 and the substrate 3 is reduced to, for example, 1 μm or less, and the gap is filled with the imprint material. At the initial stage of this contact, the relative positions of the mold 8 and the substrate 3 in the horizontal direction (X direction, Y direction) are displaced. This misalignment is detected by the detection unit 10 as described above, and the stage correction signal generated by the stage position correction calculator 13 is sent to the board stage control unit 12.

When the substrate stage 4 is moved at the time of the contact, a force acts between the mold 8 and the substrate 3 due to the viscoelasticity of the imprint material filled between the mold 8 and the substrate 3. This is because by moving the substrate stage 4, a force is generated between the substrate 3 and the imprint material, and the reaction force to the imprint material is transmitted to the mold 8, so that a force is also generated between the mold 8 and the imprint material. Works. The viscoelasticity of such an imprint material can be an obstacle to high-speed and high-precision alignment.

It is known that this viscoelasticity is reduced by applying vibration to the imprint material. Therefore, the imprinting apparatus in the present embodiment includes a vibrating unit 6 that applies high-frequency (for example, 1 kHz or more) vibration to the imprinted material on the substrate 3 in a state where the mold 8 and the imprinted material are in contact with each other. The vibrating unit 6 is provided in, for example, the substrate stage 4, and controls the position control mechanism of the substrate stage 4 to directly vibrate the substrate stage 4 itself at a high frequency. In this case, the main control unit 14 also outputs a command including the vibration frequency and amplitude values to the substrate stage control unit 12. As a result, the vibration signal is superimposed on the positioning signal in the control command output from the board stage control unit 12.

Instead, the vibrating section 6 may be provided on the substrate stage 4. In this case, the vibrating unit 6 includes, for example, a voice coil motor (VCM) type vibrator, and the vibrator vibrates at a vibration frequency and amplitude corresponding to a signal input to the voice coil motor. The main control unit 14 generates an input signal to the voice coil motor. The main control unit 14 can control the vibration frequency and intensity of the vibration given to the imprint material by the vibration unit 6 by the frequency and amplitude of the input signal, respectively. The vibration unit 6 vibrates in response to the input signal from the main control unit 14, so that the imprint material can be vibrated and the viscoelasticity of the imprint material can be reduced. The vibrating portion 6 may be provided on the mold holding portion 9 instead of on the substrate stage 4 as long as the vibration is transmitted to the imprint material.

The frequency and magnitude of the vibration is selected from a plurality of imprint conditions including the distance between the mold 8 and the substrate 3 in contact with the imprint material and the type of imprint material used. It can be tentatively determined based on the imprint conditions. In this tentative determination, the force acting between the mold 8 and the imprint material may be measured by the driving force of the substrate stage control unit 12 while changing the vibration frequency and magnitude in advance, and the value actually used may be determined. .. As a guideline for the frequency, for example, 100 Hz or higher is efficient. A more detailed method for determining the frequency will be described later. By moving the substrate stage 4 while vibrating, the alignment between the mold 8 and the substrate 3 is completed. Since the viscoelasticity of the imprint material is reduced by the vibration during alignment, the mold 8 and the substrate 3 can be relatively moved in a state where the force generated between the mold 8 and the imprint material is weakened. The vibration may be stopped when the alignment is completed.

After the imprint material is cured by applying ultraviolet rays to the imprint material by the cured portion 11, the mold holding portion 9 is raised to separate the mold 8 from the imprint material, and the imprint process for one shot area is completed. do. After that, in each shot area, supply of imprint material on the substrate, contact with the imprint material of the mold, vibration, alignment during vibration, curing of the imprint material, separation from the imprint material of the mold, Repeat the sequence of. Since the alignment is performed during the vibration in each shot region, the force acting between the mold 8 and the imprint material becomes small when the alignment is completed.

When the imprinting process of the entire surface of the substrate is completed, the substrate stage 4 moves to the substrate exchange position, and the imprinted substrate 3 is collected by the substrate exchange hand. After that, the next substrate 3 is mounted on the substrate chuck, and the imprint sequence of the entire surface of the substrate is executed again.

In the above example, the substrate stage 4 is moved when the mold 8 and the substrate 3 are aligned, but the mold holding portion 9 may be provided with a moving mechanism in the XY direction to move the mold 8. In this case, there is a position control system for the mold holding unit 9 in the XY direction, and the stage position correction signal by the stage position correction calculator 13 is also sent to the mold holding unit 9. In order to align the mold 8 and the substrate 3, at least one of the substrate stage 4 and the mold holding portion 9 may be moved.

Next, a method for determining the frequency of vibration given to the imprint material by the vibrating unit 6 will be described. First, the characteristics of the detection unit 10 will be described. As described above, the detection unit 10 irradiates the alignment marks provided on the mold 8 and the substrate 3 with the alignment light, and detects the reflected light with the scope 101. As described above, the scope 101 includes an image pickup element 102 (light receiving element). In order to accurately detect the deviation of the mark, an appropriate charge accumulation time of the reflected light in the image sensor 102 is required. The charge accumulation time can be determined based on the type of alignment mark, the type and thickness of the imprint material, the characteristics of the light receiving element, and the like.

The influence of the combination of the frequency of vibration given by the vibrating unit 6 and the charge accumulation time of the image pickup device 102 will be described with reference to FIG. For example, the charge accumulation time is 3 milliseconds. When relative vibration occurs between the mold 8 and the substrate 3, the light receiving element outputs a time-averaged signal with a charge accumulation time of 3 milliseconds. Since the detection unit 10 calculates the relative positional deviation between the mold 8 and the substrate 3 based on the signal of the light receiving element, the calculation result is also a time-averaged value with a charge accumulation time of 3 milliseconds.

FIG. 3A shows an example when the vibration frequency is 400 Hz. The solid line shows that the misalignment between the mold 8 and the substrate 3 is vibrated at a frequency of 400 Hz. The round plot is the output value of the detection unit 10 calculated at intervals of 3 milliseconds, and the broken line is a straight line connecting the round plots for easy understanding. As can be seen in this figure, the mold 8 and the substrate 3 generate a relative vibration of 400 Hz, but the center (baseline) thereof is zero. However, the output value of the detection unit 10 is not zero, and a frequency component lower than the vibration frequency is generated. This low frequency component is a detection error at the time of alignment, and there is a risk that the alignment will be performed at an incorrect position or the alignment feedback control system will oscillate.

FIG. 3B shows an example when the vibration frequency is 333.33 Hz. 333.33 Hz is a frequency at which the output becomes zero and becomes insensitive when time-averaged with a charge accumulation time of 3 milliseconds. In this case, the output value of the detection unit 10 is zero, which is the center value of the actual vibration given by the vibration, without being affected by the vibration. As described above, the detection unit 10 has a frequency characteristic derived from the charge accumulation time of the image sensor 102. Therefore, in the present embodiment, the frequency of vibration applied by the vibrating unit 6 is set to a value having a correlation with the charge accumulation time of the image pickup device 102. Specifically, the frequency of vibration may be set to a frequency that represents the frequency at which the output becomes insensitive, that is, zero, or its harmonics, among the frequency characteristics. More specifically, the frequency of vibration may be set to the frequency indicated by the reciprocal of the charge accumulation time or a multiple thereof. The multiple can be, for example, 2 or 3.

The control unit C may have a setting unit 141 for setting the charge accumulation time, as shown in FIG. As described above, the setting unit 141 can set the charge accumulation time based on the type of alignment mark, the type and thickness of the imprint material, the characteristics of the light receiving element, and the like. Alternatively, the setting unit 141 may set the charge accumulation time according to an instruction from the user. The control unit C may further include an adjustment unit 142 that adjusts the frequency of vibration given by the vibration unit 6 according to the charge accumulation time set by the setting unit 141, as shown in FIG.

Even if the vibration frequency deviates slightly from the dead frequency, the detection error during alignment may be extremely small and may not affect the alignment. That is, the vibration frequency in the actually excited state may be in the vicinity of the target frequency determined from the frequency characteristics of the detection unit 10. Further, even if the vibration is performed at the target frequency due to the characteristics of the imprint material, the actual vibration frequency may deviate from the target frequency. In this case, the target frequency may be adjusted so that the output of the detection unit 10 does not have a frequency component near the vibration frequency. For example, the adjusting unit 142 sets the vibration frequency so that the absolute value of the relative error R is 0.3 or less (that is, 30% or less) with respect to the frequency indicated by the reciprocal of the charge accumulation time set by the setting unit 141 or a multiple thereof. It may be adjusted to one of the values of. The adjusting unit 142 outputs the adjusted vibration frequency value to the main control unit 14. The relative error R is expressed by, for example, the following equation.

R = (target frequency-actual frequency) / target frequency Specifically, the permissible range of frequency error should be considered as follows. When the period of the vibration frequency coincides with the charge accumulation time of the light receiving element, in principle, the influence of the vibration does not appear in the output value of the detection unit 10. When the vibration frequency deviates by x%, x% of the vibration amplitude approximately appears in the detection unit 10 as a detection error. For example, in FIG. 3B, when the detection error is allowed up to 5, since the amplitude of the applied vibration is 50, a frequency error of 10% can be allowed. In reality, the charge accumulation time of the light receiving element is controlled by the digital control system, so that it is extremely accurate. Since the main control unit 14 that commands vibration is also composed of a digital control system, the vibration frequency can be finely adjusted. Therefore, by adjusting the target frequency while evaluating the output of the detection unit 10 as described above, it is easy to keep the target frequency within a desired error range.

In the embodiment, the adjusting unit 142 adjusts the vibration frequency so that the fluctuation of the output value of the image sensor 102 is within the permissible range, for example. At this time, for example, as described above, the adjusting unit 142 has a plurality of imprint conditions including the distance between the mold 8 and the substrate 3 in the state of being in contact with the imprint material and the type of the imprint material. The frequency of vibration is tentatively determined based on the imprint conditions selected from among them. After that, the adjusting unit 142 can adjust the frequency of vibration based on the tentatively determined frequency so that the fluctuation of the output value of the image sensor 102 is within the permissible range.

As described above, according to the present embodiment, since a detection error during alignment does not occur, it is possible to prevent alignment at an erroneous position or oscillation of the alignment feedback control system, and high-precision alignment is realized. NS.

<Embodiment of Article Manufacturing Method>
The article manufacturing method according to the embodiment of the present invention is suitable for manufacturing articles such as microdevices such as semiconductor devices and elements having a fine structure, for example. The article manufacturing method of the present embodiment includes a first step (a step of performing an imprint process on a substrate) of forming a pattern on an imprint material on a substrate by using the imprint device. The article manufacturing method further includes a second step of processing (processing) the substrate (imprinted substrate) on which the pattern is formed in the first step. Further, such a manufacturing method includes other well-known steps (oxidation, film formation, vapor deposition, doping, flattening, etching, resist peeling, dicing, bonding, packaging, etc.). The article manufacturing method of the present embodiment is advantageous in at least one of the performance, quality, productivity, and production cost of the article as compared with the conventional method. A specific example will be shown below.

The pattern of the cured product formed by using the imprint device is used permanently for at least a part of various articles or temporarily in manufacturing various articles. The article is an electric circuit element, an optical element, a MEMS, a recording element, a sensor, a mold, or the like. Examples of the electric circuit element include volatile or non-volatile 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 a mold for imprinting.

The pattern of the cured product is used as it is as a constituent member of at least a part of the above-mentioned article, or is temporarily used as a resist mask. The resist mask is removed after etching, ion implantation, or the like in the substrate processing process.

Next, the article manufacturing method will be described. As shown in FIG. 4A, a substrate 1z such as a silicon substrate on which a work material 2z such as an insulator is formed on the surface is prepared, and subsequently, a substrate 1z such as a silicon substrate is prepared and then injected into the surface of the work material 2z by an inkjet method or the like. The printing material 3z is applied. Here, a state in which a plurality of droplet-shaped imprint materials 3z are applied onto the substrate is shown.

As shown in FIG. 4B, the imprint mold 4z is opposed to the imprint material 3z on the substrate with the side on which the uneven pattern is formed facing. As shown in FIG. 4C, the substrate 1 to which the imprint material 3z is applied is brought into contact with the mold 4z, and pressure is applied. The imprint material 3z is filled in the gap between the mold 4z and the work material 2z. In this state, when light is irradiated through the mold 4z as energy for curing, the imprint material 3z is cured.

As shown in FIG. 4D, when the mold 4z and the substrate 1z are separated from each other after the imprint material 3z is cured, a pattern of the cured product of the imprint material 3z is formed on the substrate 1z. The pattern of the cured product has a shape in which the concave portion of the mold corresponds to the convex portion of the cured product and the concave portion of the mold corresponds to the convex portion of the cured product, that is, the uneven pattern of the mold 4z is transferred to the imprint material 3z. It means that it has been done (the above is the first step).

As shown in FIG. 4 (e), when etching is performed using the pattern of the cured product as an etching resistant type, the portion of the surface of the work material 2z that has no cured product or remains thin is removed, and the groove 5z is formed. (Second step). As shown in FIG. 4 (f), when the pattern of the cured product is removed, an article in which the groove 5z is formed on the surface of the work material 2z can be obtained. Here, the pattern of the cured product is removed, but it may not be removed even after processing, and may be used, for example, as a film for interlayer insulation contained in a semiconductor element or the like, that is, as a constituent member of an article.

1: Main body 4: Substrate stage, 7: Dispenser, 10: Detection part, 11: Hardened part

Claims (8)

An imprinting apparatus that forms a pattern on the imprinting material by bringing a mold into contact with the imprinting material on the substrate.
A vibrating portion that vibrates the imprint material in a state where the mold and the imprint material are in contact with each other.
The mold and the substrate include an image pickup element that converts light from a mark provided on each of the mold and the substrate into an electric signal, and the imprint material is vibrated by the vibrating portion. And the detector that detects the misalignment of
An adjustment unit that adjusts the frequency of the vibration given by the vibration unit according to the charge accumulation time of the image sensor, and an adjustment unit.
An imprinting device characterized by having. The adjustment unit, the imprint apparatus according to claim 1, wherein the frequency of vibration, characterized by that you set the frequency or a multiple thereof represented by the reciprocal of the charge accumulation time. The imprinting apparatus according to claim 2, wherein the multiple is 2 or 3. It further has a setting unit for setting the charge accumulation time, and has a setting unit.
The adjusting unit adjusts the frequency of the vibration according to the charge accumulation time set by the setting unit .
Imprint apparatus according to claim 1, wherein the this. The adjusting unit sets the frequency of the vibration to a frequency indicated by the reciprocal of the charge accumulation time set by the setting unit or a multiple thereof, and the absolute value of the relative error is 0.3 or less. The imprinting apparatus according to claim 4, wherein the imprinting apparatus is adjusted to. The imprint device according to claim 4, wherein the adjusting unit adjusts the frequency of the vibration so that the fluctuation of the output value of the image sensor is within an allowable range. The adjusting unit is an imprint selected from a plurality of imprint conditions including the distance between the mold and the substrate in contact with the imprint material and the type of the imprint material. The frequency of the vibration is tentatively determined based on the conditions, and the frequency of the vibration is adjusted based on the tentatively determined frequency so that the fluctuation of the output value of the imaging element falls within the permissible range. The imprinting apparatus according to claim 6. A first step of forming a pattern on a substrate using the imprinting apparatus according to any one of claims 1 to 7.
A second step of processing the substrate on which the pattern was formed in the first step, and
A method for producing an article, which comprises the above and manufactures an article from the substrate subjected to the treatment in the second step.

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