Liquid ejecting apparatus, imprint apparatus, and control method
Patent Information
- Authority / Receiving Office
- TW · TW
- Patent Type
- Patents
- Current Assignee / Owner
- CANON KK
- Filing Date
- 2023-12-05
- Publication Date
- 2026-08-01
Smart Images
Figure TWG2TB001903500_001 
Figure TWG2TB001903500_002 
Figure TWG2TB001903500_003
Abstract
Description
Liquid jet device, imprinting device, and control method The present invention relates to liquid jet technology. In a liquid jet device that jets liquid, there is a need for a recovery process, such as eliminating an orifice blockage or removing one of foreign substances adhering to the periphery of the orifice. Japanese Patent Laid-Open No. 2020-104094 discloses a technique that, in a state where liquid is in contact with a jet surface, cleans the orifice by driving an oscillation element of a jet head. By driving the oscillation element, liquid flows inside and within the periphery of the orifice, and foreign substances such as residues adhering to the inside and on the periphery of the orifice can be removed. In the technique of Japanese Patent Laid-Open No. 2020-104094, there is still room for improving the efficiency of removing foreign substances firmly adhering to the orifice. The present invention provides a technique for improving the efficiency of removing foreign substances adhering to an orifice. According to one aspect of the present invention, there is provided a liquid jet device including: a jet mechanism including a jet surface through which an orifice through which liquid is jetted is open; an oscillation element provided with the orifice; a retention component configured to face the jet surface and configured to retain liquid between the retention component and the jet surface; a detection mechanism for detecting oscillation characteristics of the oscillation element; and a control mechanism that, in a case of cleaning the orifice, drives the oscillation element in a drive cycle based on a detection result of the detection mechanism in a state where the liquid is retained between the retention component and the jet surface. Other features of the present invention will become apparent from the description of the following representative embodiments (refer to the accompanying drawings). Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments are not intended to limit the scope of the claimed invention. Multiple features are described in the embodiments, but the invention is not limited to requiring all such features, and multiple such features can be appropriately combined. In addition, in the accompanying drawings, the same reference numerals are used for the same or similar configurations, and redundant descriptions thereof are omitted. <First Embodiment> <Overview of Imprinting Device> FIG. 1 is a schematic diagram showing the configuration of an imprinting apparatus 101 according to an embodiment of the present invention. In this figure, an arrow Z represents the vertical direction, and arrows X and Y represent horizontal directions orthogonal to each other. The imprinting apparatus 101 is used to manufacture various devices such as semiconductor devices. The imprinting apparatus 101 includes a liquid ejection apparatus 130. The liquid ejection apparatus 130 includes a liquid ejection unit 10 and a recovery unit 80. The liquid ejection unit 10 ejects a liquid 114 (here, a resist) onto an ejection target (a substrate 111 in this embodiment). The liquid 114 is, for example, a photocurable resin having a property of being cured by UV light (UV). The liquid 114 is appropriately selected according to various conditions such as a semiconductor device manufacturing process. In addition to the photocurable property, for example, a liquid that is a thermosetting resist can be used, and the imprinting apparatus can be an apparatus that performs an imprinting process by curing the resist with heat. The liquid 114 may be referred to as an ejection material or an imprinting material. The recovery unit 80 is used in a recovery process for recovering the ejection performance of the liquid ejection unit 10. In the case of this embodiment, the recovery process includes a cleaning process for cleaning the orifice of the liquid ejection unit 10. The imprinting apparatus 101 also includes a light irradiation unit 102, a mold holding mechanism 103, a substrate stage 104, a control unit 106, a measurement unit 122, and a housing 123. The light irradiation unit 102 includes a light source 109 and an optical element 110 for modifying ultraviolet light 108 emitted from the light source 109. The light source 109 is, for example, a halogen lamp that generates i-line or g-line. The ultraviolet light 108 is applied to the liquid 114 via a mold 107. The wavelength of the ultraviolet light 108 is a wavelength corresponding to the liquid 114 to be cured. In the case of an imprinting apparatus that uses a thermosetting resist as a resist, a heat source unit for curing the thermosetting resist is installed instead of the light irradiation unit 102. The mold holding mechanism 103 includes a mold chuck 115 and a mold driving mechanism 116. The mold 107 held by the mold holding mechanism 103 has a rectangular outer shape and has a pattern portion 107a, in which a three-dimensional concavo-convex pattern such as a circuit pattern to be transferred is formed on the surface facing the substrate 111. The material of the mold 107 in this embodiment is a material capable of transmitting ultraviolet light 108, and for example, quartz is used. The mold chuck 115 holds the mold 107 by vacuum suction or electrostatic force. The mold driving mechanism 116 moves the mold 107 by holding and moving the mold chuck 115. The mold driving mechanism 116 can move the mold 107 downward in the Z direction to press the mold 107 against the liquid 114. Moreover, the mold driving mechanism 116 can move the mold 107 upward in the Z direction to pull the mold 107 away from the liquid 114. Examples of actuators that can be used for the mold driving mechanism 116 include linear motors or cylinders. There is an opening area 117 in the center of the mold chuck 115 and the mold driving mechanism 116. The mold 107 has a cavity 107b, and the cavity 107b has a concave shape on the surface irradiated with ultraviolet light 108. The light transmission component 113 is installed in the opening area 117 of the mold driving mechanism 116, and a sealed space 112 surrounded by the light transmission component 113, the cavity 107b, and the opening area 117 is formed. The pressure in the space 112 is controlled by a pressure correction device (not shown). When the pressure correction device sets the pressure in the space 112 higher than the outside, the pattern portion 107a is bent convexly toward the substrate 111. Therefore, the central portion of the pattern portion 107a contacts the liquid 114. Pressing the mold 107 against the liquid 114 prevents gas (air) from being trapped between the pattern portion 107a and the liquid 114, and the liquid 114 can be filled into all the concave and convex portions of the pattern portion 107a. The depth of the cavity 107b that determines the size of the space 112 is appropriately changed according to the size or material of the mold 107. The substrate stage 104 includes a substrate chuck 119, a substrate stage housing 120, and a stage reference mark 121. The substrate 111 held by the substrate stage is a single crystal silicon substrate or a Silicon on Insulator (SOI) substrate, and the liquid 114 is sprayed on the surface of the substrate 111 to be processed to form a pattern. The substrate chuck 119 holds the substrate 111 by vacuum suction. The substrate stage housing 120 moves the substrate 111 in the X and Y directions and holds the substrate chuck 119 by a mechanical mechanism at the same time. The stage reference mark 121 is used to set the reference position of the substrate 111 in the alignment of the substrate 111 and the mold 107. A linear motor, for example, is used as the actuator of the substrate stage housing 120. The actuator of the substrate stage housing 120 can also include a plurality of drive systems, such as a coarse driving system and a fine driving system. The measurement unit 122 includes an alignment measurement device 127 and a measurement device 128 for observation. The alignment measurement device 127 measures the positional deviation in the X direction and the Y direction between the alignment marks formed on the substrate 111 and the alignment marks formed on the mold 107. The measurement device 128 for observation is, for example, an image capturing device such as a CCD camera; the measurement device 128 for observation images the pattern of the liquid 114 sprayed on the substrate 111 and outputs it to the control unit 106 as image information. The control unit 106 controls the entire imprinting apparatus 101. The control unit 106a is provided in the liquid ejection device 130 and controls the liquid ejection device 130. In the operation of the imprinting apparatus 101, the control unit 106a controls the liquid ejection device 130 based on commands from the control unit 106. The control unit 106 includes, for example, a computer having a CPU, a ROM, and a RAM. The control unit 106 is connected via lines to each component of the imprinting apparatus 101, and the CPU controls each component according to the control program stored in the control ROM. In addition, the control unit 106 includes a display unit and is capable of performing various types of displays. The control unit 106 controls the operations of the mold holding mechanism 103 and the substrate stage 104 based on the measurement information of the measurement unit 122. The control unit 106a includes, for example, a computer having a CPU, a ROM, and a RAM. The CPU controls the components of the liquid ejection device 130 according to the control program stored in the control ROM and commands from the control unit 106. Note that the configuration may be such that instead of having the control unit 106a, the control unit 106 controls the liquid ejection device 130. The housing 123 includes a bottom plate 124, a bridging plate 125, and support columns 126. The substrate stage 104 is placed on the bottom plate 124. The bridging plate 125 fixes the mold holding mechanism 103. The support columns 126 extend from the bottom plate 124 and support the bridging plate 125. The imprinting apparatus 101 includes a mold transfer mechanism (not shown) and a substrate transfer mechanism (not shown). The mold transfer mechanism transfers the mold 107 from the outside of the apparatus to the mold holding mechanism 103, and the substrate transfer mechanism transfers the substrate 111 from the outside of the apparatus to the substrate stage 104. The imprinting apparatus 101 performs an imprinting process including the following series of processes. First, the imprinting apparatus 101 causes the liquid ejection unit 10 to spray the liquid 114 on the substrate 111. Then, the mold 107 having a pattern for molding is pressed against the liquid 114 to be sprayed on the substrate, and in this case, the liquid 114 is cured by irradiating it with light (ultraviolet rays). After that, the pattern of the mold 107 is transferred to the substrate 111 by separating the mold 107 from the liquid 114. <Liquid ejection unit and recovery unit> FIG. 2 is a diagram showing the configuration of the liquid ejection unit 10 and the recovery unit 80. The liquid ejection unit 10 includes a nozzle head 11, a container 12, and a pressure control unit 13. The container 12 contains a liquid 114. The internal space of the container 12 is partitioned into two spaces by a flexible separation membrane 14. The liquid 114 is contained in one space 15 of the container, and the filling liquid is contained in the other space 16 of the container. The thickness of the separation membrane 14 is, for example, 10 μm or more and 200 μm or less. The separation membrane 14 is formed of a material having low permeability to liquids and gases, and can be formed, for example, of a film of a fluoropolymer material such as PFA, or a composite multilayer film in which a fluoropolymer and a plastic material are combined. The space 16 communicates with the pressure control unit 13 via a connection pipe 17, and the space 15 communicates with the nozzle head 11. The pressure control unit 13 includes a reservoir containing a filling liquid, a pressure sensor, a valve for opening or closing the connection pipe 17, etc., and is configured to be able to control the pressure in the space 16. By controlling the pressure of the filling liquid in the space 16 through the pressure control unit 13, it is possible to control the pressure of the liquid 114 in the space 15 via the separation membrane 14. Therefore, the shape of the gas-liquid interface in the nozzle head 11 can be stabilized, and the liquid 114 can be ejected with high reproducibility. The recovery unit 80 includes a lid portion 81 into which the waste liquid of the liquid 114 ejected from the nozzle head 11 enters. The lid portion 81 is a concave component having an opening larger than the opening of the nozzle head 11, and its material is, for example, a PTFE resin cut component for which metal elution is not a problem. The lid portion 81 can be subjected to acid cleaning so that it can be used in physical and chemical cleaning states. During the recovery process, the lid portion 81 is arranged to face the ejection surface 58 of the nozzle head 11. The lid portion 81 is also used as a retention component that holds the cleaning liquid when cleaning the orifice of the nozzle head 11. The lid portion 81 is configured to be able to be displaced in the Z direction by a driving mechanism (not shown), and the distance between the lid portion 81 and the ejection surface 58 can be adjusted. The recovery unit 80 also includes a waste liquid pipe 85, a valve 83 for opening or closing the waste liquid pipe 85, a waste liquid collection container 82, and a pump 84. The waste liquid pipe 85 communicates with the lid portion 81. The pump 84 is a tubing pump that pumps the waste liquid to the waste liquid collection container 82 via the waste liquid pipe 85, and is ejected onto the lid portion 81. FIG. 3 is a partially enlarged cross-sectional view of the ejection head 11. The ejection head 11 includes a common liquid chamber 56 and a module substrate 57. The module substrate 57 includes a plurality of nozzles 54. Each nozzle 54 is provided with a supply port 21 that opens to the top surface 59 and sucks the liquid 114, and an orifice 19 that opens to the ejection surface 58 and discharges the liquid 114. An oscillation element 18 that generates energy for ejecting the liquid 114 is provided in each nozzle 54. An oscillation element 18 is provided for each orifice. The opening area of the orifice 19 is smaller than the opening area of the supply port 21, and has the smallest cross-sectional area in the flow path of the nozzle 54. In the present embodiment, the oscillation element 18 is a piezoelectric device represented by a piezoelectric element, and hereinafter, the oscillation element 18 may be referred to as the piezoelectric element 18. The supply port 21 communicates with the orifice 19 via a small liquid chamber 20 in the module substrate 57. The driving of the piezoelectric element 18 is controlled by the control unit 106a via the driving circuit 90. By changing the volume of the small liquid chamber 20 through the piezoelectric element 18, the liquid 114 in the small liquid chamber 20 is ejected from the orifice 19. Note that the ejection head 11 may have a configuration similar to that of an inkjet head used in an inkjet printer. Although the ejection head 11 is open to the atmosphere through the orifice 19, the diameter of the orifice 19 is several μm to several tens of μm, and the liquid 114 does not leak due to its own weight due to capillary action. The liquid level near the orifice 19 is maintained in a so-called concave meniscus state. By maintaining the internal pressure of the liquid 114 in the small liquid chamber 20 at a negative pressure of from -0.1 Pa to -1000 Pa through the pressure control unit 13, it is possible to stably maintain the meniscus condition. A liquid repellent treatment is applied to the ejection surface 58 to reliably prevent the liquid 114 from leaking out of the orifice 19. As the liquid repellent treatment, for example, a fluorine-containing compound is applied to the ejection surface 58 in the form of a film. When the diameter of the orifice 19 is a small diameter of several μm to several tens of μm, the ejection performance deteriorates when particles adhere to the inside of the orifice 19, or when a part of the components contained in the liquid 114 dries or solidifies around the orifice 19. Examples of deterioration in ejection performance include not only ejection failure but also changes in ejection amount and ejection direction. When such a decrease in ejection performance occurs, the recovery unit 80 performs a process of recovering the ejection performance. <Control Example> Referring to FIG. 4, a representative process for restoring the ejection head 11 performed by the control unit 106a will be described. FIG. 4 is a flowchart showing a representative example performed by the control unit 106a. The illustrated process is executed at a timing when the liquid 114 is not being ejected onto the substrate 111. For example, the following process is executed after the liquid ejection device 130 is moved to the standby position for performance maintenance. In step S1, the liquid ejection state of each orifice 19 is checked. In step S2, the orifice 19 where ejection failure occurs is identified based on the check result of step S1. For example, the oscillation characteristics of each piezoelectric element 18 are detected, and the liquid ejection state is checked based on the detection result. In this embodiment, the back electromotive force of each piezoelectric element 18 is detected as the oscillation characteristic, and the check is performed based on the signal waveform. That is, the piezoelectric element 18 can also be used to detect the liquid ejection state of the orifice 19. The piezoelectric element 18 is driven by a voltage having an intensity of 30% to 70% of the voltage applied when the liquid 114 is ejected, to change the volume of the small liquid chamber 20 (hereinafter referred to as check oscillation), and oscillation is applied to the liquid 114 in the small liquid chamber 20. For example, when the liquid 114 is ejected from the orifice 19, and a drive pulse of ±10 V is applied to the piezoelectric element 18, a drive pulse of ±6 V is applied to the piezoelectric element 18. In other words, the piezoelectric element 18 is driven to such an extent that oscillation is applied to the liquid 114 in the small liquid chamber 20 without the meniscus of the orifice 19 being broken and the liquid 114 being ejected. Even when the drive of the piezoelectric element 18 is stopped, a back electromotive force is generated in the piezoelectric element 18 due to the residual oscillation of the liquid 114. The back electromotive force is detected by the sensor 91 provided for each orifice 19. The sensor 91 is, for example, a voltage sensor or a current sensor. When the orifice 19 is blocked by foreign matter or when a bubble enters the small liquid chamber 20, the waveform of the back electromotive force is different from the standard state (the waveform when the meniscus is formed). That is, the piezoelectric element 18 outputs a signal corresponding to the liquid ejection state of the corresponding orifice 19. With this signal, the liquid ejection state of each orifice 19 can be individually detected. More specifically, the piezoelectric element 18 (piezoelectric element) is deformed by the application of a voltage, and this deformation changes the pressure of the liquid 114 in the nozzle 54. When the piezoelectric element 18 is forced to oscillate, residual oscillation is generated, and a back electromotive force is generated by the piezoelectric effect. The sensor 91 detects the back electromotive force generated by the residual oscillation. In addition, since a back electromotive force is generated for each piezoelectric element 18, in other words, for each nozzle 54, the sensor 91 detects the back electromotive force for each nozzle 54. Figures 6A and 6B are diagrams showing representative signal waveforms (changes in current-time) of back electromotive force when the signal shown in Fig. 6C is applied to the piezoelectric element 18 as an inspection signal for inspection oscillation. The inspection signal of Fig. 6C has, for example, a voltage waveform that changes within a period equal to or less than the natural period estimated for the piezoelectric element 18. For example, if the natural period of the piezoelectric element 18 is estimated to be 4.5 μsec, a voltage having a waveform that changes within 4.5 μsec is applied. Fig. 6A is an example of a normal signal waveform, in which a decrease in injection performance does not occur at the orifice 19. The dashed line in Fig. 6B is an example of the signal waveform in a normal situation, and the solid line is an example of the signal waveform in a situation where a decrease in injection performance occurs. When the meniscus of the liquid 114 stops being formed in the orifice 19, the period of the signal is longer (the frequency is smaller) than in the case where the orifice 19 is normal. In addition, the amplitude may be larger. It is possible to determine a decrease in the injection performance of the orifice 19 based on such a signal waveform difference. It should be noted that the normal signal waveform for comparison can be stored in a storage device such as the ROM of the control unit 106. In addition, instead of storing the signal waveform in the normal state, a threshold value for determining whether injection failure has occurred can be stored. The threshold value can be a threshold value related to the signal period of the back electromotive force, or a threshold value related to the signal amplitude. By this method, the orifice 19 where injection failure occurs is identified in step S2 of Fig. 4. When it is determined in step S2 that injection failure has not occurred in any of the orifices 19, the process of Fig. 4 ends. Here, although the liquid injection state of the orifice 19 is inspected by inspection oscillation, the orifice 19 (nozzle 54) where injection failure occurs can be detected by measuring the presence or absence of landing, the landing position, the speed, and the amount of landing through a landing inspection device (not shown). In step S3, the orifice 19 is selected as the target for performance recovery based on the identification result of step S2. For example, the orifice 19 identified in step S2 is selected as the orifice 19 to be recovered. As another example, the orifices 19 can be grouped according to their positions, and the orifices 19 to be subjected to the recovery process can be selected based on a group-by-group method. As yet another selection method, the orifice 19 identified in step S2 and the orifices 19 within a certain area around those orifices 19 can be selected. As yet another example, if there is at least one orifice 19 having injection failure in step S2, then all the orifices 19 are targets for recovery. In step S4, a recovery process is performed on the orifice 19 selected in step S3. FIG. 5 is a flowchart illustrating a representative process of step S4. In step S11, the cover portion 81 is disposed at a position facing the ejection surface 58. The cover portion 81 can hold the cleaning liquid between the ejection surface 58 and the inner wall surface of the cover portion 81. Thereafter, the small liquid chamber 20 corresponding to the orifice 19 selected in step S3 is pressurized by the pressure control unit 13. By pressurizing the small liquid chamber 20, for example, from +10 kPa to +50 kPa, it is possible to push out foreign substances and the like blocked in the orifice 19. At this time, the liquid 114, foreign substances, etc. ejected from the orifice 19 to the cover portion 81 are discharged to the waste liquid collection container 82 by the pump 84. Since the recovery from the blockage of the orifice 19 may still not be successful even with such a pressurization recovery, the process proceeds to the next cleaning step. In step S13, after the distance between the bottom surface of the cover portion 81 and the ejection surface 58 is within 100 to 500 μm, the cleaning liquid fills between the cover portion 81 and the ejection surface 58. In the present embodiment, the liquid 114 is used as the cleaning liquid. The pressure of the liquid 114 in the small liquid chamber 20 is set to be equal to or higher than 10 kPa by pressurizing the filling liquid in the space 16 through the pressure control unit 13 to about 10 kPa to 30 kPa. Therefore, the liquid 114 is ejected from the orifice 19 as the cleaning liquid. When the space between the cover portion 81 and the ejection surface 58 is filled with the liquid 114, the pressurization of the filling liquid in the space 16 is stopped. Next, the pressure in the small liquid chamber 20 is set to a slightly positive pressure (a few hundred Pa to a few kPa) by the pressure control unit 13, and then the pipe 17 connecting the pressure control unit 13 and the space 16 is closed by closing the valve of the pressure control unit 13. Since the liquid 114 on the cover portion 81 is open to the atmosphere, the pressure of the liquid 114 in the small liquid chamber 20 gradually decreases from a slightly positive pressure to the atmospheric pressure. This prevents the liquid 114 from flowing out of the ejection head 11 and into the cover portion 81, and prevents the liquid 114 from overflowing from the cover portion 81. The pressure of the liquid 114 in the small liquid chamber 20 is maintained at a pressure slightly positive than the atmospheric pressure. Therefore, the liquid 114 on the cover portion 81 is prevented from flowing back to the ejection head 11, and the liquid 114 is retained between the cover portion 81 and the ejection surface 58, as shown in FIG. 7. Next, in the present embodiment, the cleaning of the orifice 19 selected as the recovery target is performed by physically oscillating the small liquid chamber 20 by driving the corresponding piezoelectric element 18. In steps S14 and S15 of FIG. 5, processes related to the setting of the driving period for driving the piezoelectric element 18 are performed. By causing the piezoelectric element 18 to resonate, the cleaning effect is improved. First, in step S14, the natural period of the piezoelectric element 18 is identified. The natural period is identified for each piezoelectric element 18 (for each oscillating element), and the oscillation characteristics of each piezoelectric element 18 are detected, and the natural period is identified based on the detection result. The signal waveform of the back electromotive force has been obtained as the oscillation characteristics of the piezoelectric element 18 in the inspection of the liquid ejection state in step S1. This signal waveform is used to calculate the natural period. The oscillation characteristics of the piezoelectric element 18 can be detected separately from the process of step S1 so as to identify the natural period of the piezoelectric element 18 in step S14. However, according to this embodiment, the detection of the oscillation characteristics can be performed once for two purposes: the inspection of the liquid ejection state and the identification of the natural period. In the identification in step S14, the natural period T is calculated from the signal waveform of the back electromotive force of the piezoelectric element 18. FIG. 8A shows an example thereof. The signal waveform of the back electromotive force is the residual oscillation generated after the oscillation of the piezoelectric element 18 and thus becomes a damped wave. The natural period T is calculated by fitting the signal waveform to a damped wave function. In step S15, the drive period of the piezoelectric element 18 is set based on the natural period T calculated in step S14. FIG. 8B shows the signal waveform (dashed line) obtained when the piezoelectric element 18 is driven after a delay of the natural period T from the signal waveform (solid line) of the back electromotive force generated in the piezoelectric element 18. The dashed line in FIG. 8B indicates that the piezoelectric element 18 is caused to oscillate at a period that is one time the natural period T. The second peak of the solid line waveform when the piezoelectric element 18 is first driven and the first peak of the dashed line waveform when the piezoelectric element 18 is driven overlap with a delay of one time the natural period T. Therefore, the piezoelectric element 18 resonates, the oscillation of the piezoelectric element 18 increases, and the fluidity of the liquid 114 in contact with the ejection surface 58 increases. Foreign matter adhering to the inside or periphery of the orifice 19 is effectively removed. Therefore, by setting the drive period Td to the natural period T, the cleaning performance can be improved. However, the oscillation period Td of the piezoelectric element 18 does not need to be exactly the same as the natural period T to have a cleaning effect, and can be a period within a certain range relative to the natural period T. Assuming that the minimum period of the drive period Td is Td_min and the maximum period is Td_max, the drive period Td is calculated as follows: Td_min ≤ Td ≤ Td_max (Equation 1) As an example, Td_min = T, Td_max = T + T × 0.2. For example, when the natural period T of the piezoelectric element 18 is 4.5 μsec, the drive period Td is 4.5 μsec ≤ Td ≤ 5.4 μsec. When the drive period Td is expressed in terms of the drive frequency fd, it is 185 KHz ≤ fd ≤ 222 KHz. In the orifice 19 (nozzle 54) where injection failure occurs, the natural period T of the piezoelectric element 18 can be several percent to about 30 percent longer than the natural period T in the normal state. In addition, the natural period T can vary depending on the degree of deposition amount related to the orifice 19 and so on. In the present embodiment, the natural period T is calculated for each piezoelectric element 18, and the drive period Td is set for each piezoelectric element 18. Therefore, a cleaning effect suitable for each orifice 19 can be obtained. However, the same drive period Td is set for all the piezoelectric elements 18. In this case, the drive period Td can be set based on the natural period T of any one of the piezoelectric elements 18, or the drive period Td can be set based on the average value of the natural periods T of a plurality of piezoelectric elements 18. In step S16 of FIG. 5, the orifice 19 is cleaned. Here, the piezoelectric element 18 is driven at the drive period Td set in step S15, and at the same time the liquid 114 is retained between the injection surface 58 and the lid portion 81. The orifice 19 (nozzle 54) is cleaned by the physical oscillation of the small liquid chamber 20 generated by the piezoelectric element 18 and the flow of the liquid 114 generated by the oscillation. FIG. 9 shows the waveform of the drive signal applied to the piezoelectric element 18. The horizontal axis represents time, and the vertical axis represents voltage. The drive signal shown is a trapezoidal wave as an example. The trapezoidal wave includes a pulling component (rising edge) 201, a constant voltage component 202, and a pushing component (falling edge) 203. The drive period Td is the sum of the time of the trapezoidal wave and the waiting period Tw at its initial value. With this trapezoidal wave, by the first pulling component 201, the liquid 114 in the lid portion 81 flows into the orifice 19. After the pulling component 201, the voltage is kept constant by the constant voltage component 202. During this time period, the liquid flowing into the orifice 19 from the lid portion 81 decreases. In the subsequent pushing component 203, the liquid 114 in the orifice 19 is pushed out of the lid portion 81. Thereafter, in the waiting period Tw at its initial value, less and less liquid 114 is pushed out of the orifice 19 and into the lid portion 81, and in the subsequent trapezoidal wave, the liquid 114 in the lid portion 81 flows into the orifice 19 again. In terms of the cleaning operation, since the liquid 114 only needs to move between the inside and outside of the lid portion 81 and inside the orifice 19, the waveform for driving the piezoelectric element 18 in the cleaning operation can at least include the pulling component 201 for increasing the voltage and the pushing component 203 for decreasing the voltage. FIG. 9 illustrates a trapezoidal wave, but a square wave, a sawtooth wave, a triangular wave, and a pulse wave can also be similarly used to achieve the cleaning effect. For example, during the imprinting operation, when the maximum driving frequency is 60 KHz, the driving signal can be achieved by adding a plurality of driving signals during this period. In other words, the number of driving signals per unit time can be different between the case where the liquid is ejected from the orifice 19 onto the substrate 111 and the case where the orifice 19 is cleaned. Therefore, as shown in FIG. 9, the number of driving signals (trapezoidal waves) and the waiting period Tw can be adjusted, and the piezoelectric element 18 can be driven at the desired oscillation period Td of the driving waveform. The voltage of the driving signal during cleaning can be approximately 20% to 40% greater than the voltage applied to the piezoelectric element 18 during ejection in the imprinting operation. The cleaning effect can be further enhanced. When the piezoelectric element 18 is driven at the driving period Td during cleaning, the load on the driving circuit 90 may increase. Therefore, the driving time and the driving pause time of the piezoelectric element 18 can be alternately set, and cleaning can be repeatedly performed in short cycles with intervals therebetween. By not driving the piezoelectric element 18 for the orifice 19 that is not the target of the recovery process, it is possible to prevent contaminants from flowing into the orifice 19 and avoid secondary contamination. After the cleaning is completed, in step S17 of FIG. 5, the gap between the cover portion 81 and the ejection surface 58 is widened. Then, in order to replace the liquid 114 in the ejection head 11, the liquid 114 is discharged from the orifice 19 into the cover portion 81 in the same manner as the pressurization recovery process in step S12. Therefore, it is possible to prevent foreign matter from entering the orifice 19 again. Thereafter, the pump 84 is driven to discharge the liquid 114 between the ejection surface 58 and the cover portion 81. The ejection surface 58 of the ejection head 11 can be cleaned using a suction nozzle (not shown). Cleaning is performed by sucking and removing the cleaning liquid (liquid 114) adhering to the ejection surface 58. The suction starts with the suction nozzle directly connected to the negative pressure source being within 100 μm of the ejection surface 58 of the ejection head 11, and the suction nozzle scans the ejection surface 58 to suck out the droplets still on the surface of the ejection surface 58 while maintaining the distance from the ejection surface 58. The suction opening gap of the suction nozzle is set between 100 μm and 200 μm. The remaining droplets may temporarily bring the ejection surface 58 and the tip of the suction nozzle into conduction with the liquid 114. A PTFE resin suction nozzle can be used to avoid the risk of metal contamination. In step S18, a confirmation process is performed. Here, a check similar to that in step S1 is performed again, and the check oscillation is performed again to confirm whether there is an orifice 19 where ejection failure has occurred, just in case. If there is an orifice 19 where ejection failure has occurred, the recovery process (S4) is performed again. In the case of secondary contamination, such contamination can be eliminated. If there is no orifice 19 where ejection failure has occurred, the process ends. In this embodiment, the liquid ejection device 130 is mounted on the imprinting device 101 to perform the inspection oscillation of the ejection head 11, and calculate the natural period T of the piezoelectric element 18 from the oscillation characteristics obtained by the inspection oscillation, so as to set the oscillation period Td of the piezoelectric element 18 in the cleaning operation. However, before mounting the liquid ejection device 130 in the imprinting device 101, the inspection oscillation can be performed, and the oscillation period Td of the piezoelectric element 18 used in the cleaning operation can be set in advance. <Second Embodiment> When the driving period Td is short, the load on the drive circuit 90 is heavy. On the other hand, the longer the cleaning time by the oscillation of the piezoelectric element 18 is continuously performed, the greater the effect. By performing such cleaning for several hours to several days, even stubborn foreign matters can be removed. In this embodiment, cleaning is performed by driving the piezoelectric element 18 at a lower driving frequency than in the first embodiment. During cleaning, when the piezoelectric element 18 is oscillated at a period that is a natural multiple of the natural period T of the piezoelectric element 18, the piezoelectric element 18 resonates and the oscillation of the piezoelectric element 18 increases. By increasing the fluidity of the liquid 114 in contact with the ejection surface 58, the cleaning effect can be improved. FIG. 10A shows the signal waveform (dashed line) when the piezoelectric element 18 is driven with a delay of twice the natural period T from the signal waveform (solid line) of the back electromotive force generated in the piezoelectric element 18. That is, the dashed line in FIG. 10A indicates that the piezoelectric element 18 is caused to oscillate at a period twice the natural period T. The third peak of the waveform of the solid line when the piezoelectric element 18 is first driven overlaps with the first peak of the waveform of the dashed line when the piezoelectric element 18 is driven with a delay of twice the natural period T. Therefore, the piezoelectric element 18 resonates, the oscillation of the piezoelectric element 18 increases, and the fluidity of the liquid 114 in contact with the ejection surface 58 increases. Foreign matters adhering to the inside or periphery of the orifice 19 are effectively removed. Therefore, by setting the driving period Td to 2 or more times the natural period T, the cleaning performance can be improved. However, the oscillation period Td of the piezoelectric element 18 does not need to be exactly the same as 2 or more times the natural period T to have a cleaning effect, and can be a period within a certain range relative to the natural period T. Assuming that the multiple of the oscillation period Td of the piezoelectric element is (a natural number of 2 or greater) relative to the natural period T, the minimum period of the driving period Tdn is Tdn_min and the maximum period is Tdn_max, then the driving period Tdn can be expressed as: Tdn_min ≤ Tdn ≤ Tdn_max (Equation 2) (n is a natural number of 2 or greater) As an example, Tdn_min = n×T - (T×0.2), and Tdn_max = n×T + (T×0.2). FIG. 10B shows the waveform of the drive signal applied to the piezoelectric element 18. The horizontal axis represents time, and the vertical axis represents voltage. Similar to the example of FIG. 9, the drive signal shown is a trapezoidal wave as an example. In the case where the multiple n = 2, when the natural period of the piezoelectric element 18 is estimated to be 4.5 μsec, the drive period Td2 is 8.1 μsec ≤ Td2 ≤ 9.9 μsec. When expressing the drive period Td2 in terms of the drive frequency f2, it is 101 KHz ≤ f2 ≤ 123 KHz. When the value of the multiple n increases, the drive period Tdn increases, and thus, the flow of the liquid 114 between the drives of the piezoelectric element 18 becomes weaker, which may reduce the cleaning efficiency. In this regard, the multiple n can be a natural number equal to or less than 7. <Third Embodiment> During cleaning, the liquid 114 between the spray head 11 and the cover portion 81 can be circulated and filtered simultaneously. FIG. 11 is a diagram showing an example of the configuration of the present invention. The recovery unit 80' includes a cleaning device 60. The cleaning device 60 is a device for cleaning each orifice 19 with a cleaning liquid, and includes a circulation device 61, a cover portion 81' instead of the cover portion 81, and a filter 66. The cleaning liquid is, for example, a liquid similar to the liquid 114, or a liquid using one of the materials contained in the liquid 114. Multiple types of cleaning liquids can be used for a single cleaning. For example, after cleaning with a liquid different from the liquid 114 as the cleaning liquid, the liquid 114 can be used as the cleaning liquid for cleaning. The cover portion 81' is detachably attached to the spray head 11. The circulation device 61 is a mechanism for circulating the cleaning liquid supplied to and discharged from the cover portion 81'. The filter 66 is provided in the middle of the circulation path of the cleaning liquid and purifies the cleaning liquid. By circulating the cleaning liquid, the amount of cleaning liquid consumed can be reduced. The circulation device 61 includes a container TK for storing the cleaning liquid, pipes 62 and 63, and a pump 65. The pipe 62 connects the container TK and the cover portion 81' to form a flow path for supplying the cleaning liquid. The pipe 63 connects the container TK and the cover portion 81' to form a flow path for discharging (recovery side) the cleaning liquid. In the present embodiment, the pump 65 is provided in the middle of the pipe 62 and pumps the cleaning liquid to the cover portion 81'. The filter 66 is provided in the middle of the pipe 62 and downstream of the pump 65, and purifies the cleaning liquid flowing through the pipe 62. Even if debris generated by the pump 65 is mixed into the cleaning liquid, the debris is removed by the filter 66. The tile-shaped member 75 is disposed on the bottom surface of the spray head 11. The tile-shaped member 75 holds the spray surface 58 on which a plurality of orifices 19 are formed, the protection assembly 73 that protects the spray surface 58, and the filler 74 that fills the gap between the spray surface 58 and the protection assembly 73. The lid portion 81' is a component that forms a storage space for storing the cleaning liquid so that the cleaning liquid contacts the spray surface 58. The lid portion 81' is, for example, a PTFE resin cutting member for which metal elution is not a problem. The lid portion 81' can be used in physical and chemical cleaning states by performing acid cleaning on the lid portion 81' after the molding process. The supply port 81a and the plurality of discharge ports 81b are formed in the lid portion 81'. The supply port 81a is connected to the pipe 62, and the plurality of discharge ports 81b are connected to the pipe 63. The cleaning liquid pumped out from the pump 65 is supplied to the lid portion 81' through the supply port 81a and discharged from the lid portion 81' through the plurality of discharge ports 81b. The pressure (P1) of the cleaning liquid pumped into the lid portion 81' can be measured by the pressure gauge included in the pump 65. By controlling the pressure (P2) inside the spray head 11 through the pressure control device 13, the magnitude relationship between the pressure P1 and the pressure P2 can be controlled. Also, in the case of this embodiment, the orifices 19 can be cleaned by the cleaning procedure shown in FIGS. 4 and 5 of the first embodiment. In step S13 of FIG. 5, when the cleaning liquid fills the space between the lid portion 81' and the spray surface 58, the cleaning liquid stored in the container TK can be used. In this case, the pump 65 is driven to supply the cleaning liquid into the lid portion 81'. During cleaning, the piezoelectric element 18 is driven in the driving period Td, and at the same time the pump 65 is driven to circulate the cleaning liquid between the lid portion 81' and the container TK. The circulation of the cleaning liquid can enhance the flow of the cleaning liquid around the orifice 19. The foreign matter separated from the periphery of the orifice 19 by the driving of the piezoelectric element 18 reaches the filter 66 through the action of the circulation device 61 and is captured. Since the cleaning liquid is purified by the filter 66, the cleaning liquid can be reused, and even when cleaning is performed for a long time, the amount of cleaning liquid consumed can be suppressed. Other embodiments Embodiments of the present invention can also be implemented by a computer of a system or device, which reads and executes computer-executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be more fully referred to as a "non-transitory computer-readable storage medium") to perform the functions of one or more of the above embodiments, and / or it includes one or more circuits (e.g., an application-specific integrated circuit (ASIC)) for performing the functions of one or more of the above embodiments, and is implemented by a method performed by a computer of a system or device that, for example, reads and executes computer-executable instructions from a storage medium to perform the functions of one or more of the above embodiments, and / or controls the one or more circuits to perform the functions of one or more of the above embodiments. The computer may include one or more processors (e.g., a central processing unit (CPU), a microprocessing unit (MPU)), and may include a network of separate computers or separate processors to read and execute computer-executable instructions. The computer-executable instructions, for example, may be provided to the computer from a network or a storage medium. The storage medium may include, for example, one or more hard disks, random access memory (RAM), read-only memory (ROM), the storage of a distributed computing system, optical discs (such as, compact disc (CD), digital versatile disc (DVD), Blu-ray Disc (BD) TM ), flash memory devices, memory cards, and so on. Although the present invention has been described with reference to representative embodiments, it is to be understood that the present invention is not limited to the disclosed representative embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to cover all such variations and equivalent structures and functions. 10: Liquid ejection unit 11: Nozzle head 12: Container 13: Pressure control unit 14: Separation membrane 15: A space 16: Another space 17: Connection pipe 18: Oscillation element (piezoelectric element) 19: Orifice 20: Liquid chamber 21: Supply port 54: Nozzle 56: Common liquid chamber 57: Module substrate 58: Spray surface 59: Top surface 60: Cleaning equipment 61: Circulation equipment 62: Pipe 63: Pipe 65: Pump 66: Filter 73: Protection component 74: Filler 75: Tile 80, 80': Recovery unit 81, 81': Cover part 81a: Feed port 81b: Discharge port 82: Waste liquid collection container 83: Valve 84: Pump 85: Waste liquid pipe 90: Drive circuit 91: Sensor 101: Imprinting equipment 102: Light irradiation unit 103: Mold holding mechanism 104: Substrate stage 106: Control unit 106a: Control unit 107: Mold 107a: Pattern part 107b: Cavity 108: Ultraviolet light 109: Light source 110: Optical element 111: Substrate 112: Space 113: Light transmission component 114: Liquid 115: Mold chuck 116: Mold drive mechanism 117: Opening area 119: Substrate chuck 120: Substrate stage housing 121: Stage reference mark 122: Measuring unit 123: Housing 124: Bottom plate 125: Bridging plate 126: Support column 127: Alignment measuring device 128: Measuring device for observation 130: Liquid jetting equipment 201: Pulling component 202: Constant voltage component 203: Pushing component [FIG. 1] is a schematic diagram showing the configuration of an imprinting device. [FIG. 2] is a view showing a liquid ejection unit and a recovery unit. [FIG. 3] is a partial enlarged cross-sectional view of a nozzle head. [FIG. 4] is a flowchart showing an example controlled by a control unit. [FIG. 5] is a flowchart showing an example controlled by a control unit. [FIGS. 6A and 6B] are views showing signal waves of back electromotive force. [FIG. 6C] is a view showing an example of a detection signal. [FIG. 7] is a schematic view showing a state where a cleaning liquid has filled between a spray surface and a cover part. [FIG. 8A] is a view showing an example of a method for identifying a natural period. [FIG. 8B] is a view showing an example of a method for setting a drive period. [FIG. 9] is a view showing an example of a drive signal. [Fig. 10A] is a view showing an example of another method for setting a driving period. [Fig. 10B] is a view showing an example of a driving signal. [Fig. 11] is a view for explaining the configuration for circulating the cleaning liquid.
Claims
1. A liquid jetting device, comprising: A spraying mechanism includes a spraying surface through which liquid is sprayed out through an open orifice; an oscillating element provided with the orifice; a retaining assembly disposed opposite the spraying surface and configured to retain liquid between the retaining assembly and the spraying surface; a detection mechanism for detecting the oscillation characteristics of the oscillating element; and a control mechanism for identifying the natural period of the oscillating element based on the detection result of the detection mechanism, and, when cleaning the orifice, driving the oscillating element in a driving cycle based on the natural period while the liquid system is retained between the retaining assembly and the spraying surface, wherein the natural period is T and the driving cycle is Td, where T≤Td≤T×1.
2.
2. A liquid jetting device, comprising: A spraying mechanism includes a spraying surface through which liquid is sprayed out through an open orifice; an oscillating element provided with the orifice; a retaining assembly disposed opposite the spraying surface and configured to retain liquid between the retaining assembly and the spraying surface; a detection mechanism for detecting the oscillation characteristics of the oscillating element; and a control mechanism for identifying the natural period of the oscillating element based on the detection result of the detection mechanism, and, when cleaning the orifice, driving the oscillating element in a driving cycle based on the natural period while the liquid system is retained between the retaining assembly and the spraying surface, wherein the natural period is T, and the driving cycle is Td, (n×T–T×0.2)≤Td≤(n×T+T×0.2), where n is a natural number of 2 or greater.
3. The liquid jetting device as claimed in claim 1 or 2, wherein a plurality of orifices are opened in the jetting surface, the oscillating element is provided with each orifice, and the control mechanism is configured to identify the natural cycle and set the drive cycle for each oscillating element.
4. The liquid jetting device of claim 1 or 2, wherein the oscillating element is a piezoelectric element, the system being configured to be driven by the supply of a drive signal to generate energy for causing liquid to be jetted from the orifice, and the control mechanism being configured to drive the piezoelectric element by a different number of drive signals per unit time between the situation of causing liquid to be jetted from the orifice onto the jetting target and the situation of cleaning the orifice.
5. The liquid injection device as claimed in claim 4, wherein the waveform of the drive signal is a trapezoidal wave, a square wave, a sawtooth wave, or a triangular wave.
6. The liquid jetting device of claim 1 or 2, including a collection container, is configured to collect the liquid retained between the jetting surface and the retention component.
7. The liquid jetting device of claim 1 or 2, including a circulation mechanism for causing liquid to circulate through a filter between a container and a space between the jetting surface and the retention component.
8. The liquid jetting device of claim 1 or 2, wherein the oscillating element is a piezoelectric element disposed in a liquid chamber connected to the orifice, and the detection mechanism is configured to detect back electromotive force, which is output by the piezoelectric element due to the oscillation of the liquid in the liquid chamber driven by the piezoelectric element.
9. The liquid jetting device of claim 8, wherein the control mechanism is configured to: check the jetting state of the orifice based on the signal waveform of the back electromotive force; and set the drive cycle based on the signal waveform of the back electromotive force.