Electroless plating apparatus and method

Abstract

An apparatus comprising: a tank configured to hold an electroless plating solution and a substrate on which electroless plating is to be performed, the substrate immersed in the electroless plating solution; one or more transducers arranged to transmit vibrations to the substrate; and a driver configured to provide a drive signal to the one or more transducers, wherein the drive signal is configured to cause the one or more transducers to vibrate the substrate at a resonance frequency of the substrate.

Description

Technical Field

[0001] The present invention is generally related to, for example, a material handling system for electroless electroplating. Prior Technology

[0002] Electroless plating (sometimes referred to as electroless deposition) is a process in which materials such as metals and metal alloys can be deposited onto a surface. Electroless plating processes utilize redox reactions at the deposition surface to autocatalytically reduce metal cations to elemental metals. Electroless plating can be performed on both conductive and non-conductive surfaces, including plastics, oxides, and the like. Summary of the Invention

[0003] Some embodiments of the present invention describe an apparatus comprising: a tank configured to contain an electroless plating solution and a substrate on which electroless plating is to be performed, the substrate being immersed in the electroless plating solution; one or more sensors configured to transmit vibrations to the substrate; and a driver configured to provide a drive signal to the one or more sensors, wherein the drive signal is configured to cause the one or more sensors to vibrate the substrate at one of the resonant frequencies of the substrate.

[0004] This device and other devices described herein may have at least one or more of the following characteristics.

[0005] In some implementations, the one or more sensors are mounted to one or more walls of the slot.

[0006] In some implementations, the one or more sensors are configured to be immersed in the electroless plating solution.

[0007] In some embodiments, the device includes a sensor configured to detect vibration of at least one of the substrate or the electroless plating solution. The driver is configured to: receive an output from the sensor indicating the detection of vibration of the substrate; and generate the drive signal in response to receiving the output from the sensor.

[0008] In some embodiments, the sensor includes: a motion sensor configured to detect movement of the electroless plating solution, a pressure sensor configured to detect pressure of the electroless plating solution, an optical sensor configured to detect movement of the substrate, or a motion sensor configured to detect movement of the substrate.

[0009] In some embodiments, the driver is configured to provide a plurality of test drive signals to one or more sensors. The plurality of test drive signals are configured to cause the one or more sensors to vibrate the substrate at different respective frequencies. The driver is configured to: receive a corresponding output from the sensor for each of the plurality of test drive signals, the corresponding output indicating an amplitude of the vibration of the substrate caused by the test drive signal; and generate the drive signal in response to receiving the corresponding outputs from the sensor. A frequency of the drive signal is based on the amplitude of the vibration caused by the plurality of test drive signals.

[0010] In some implementations, the drive signal has a frequency of less than 1 kHz.

[0011] In some implementations, the frequency of the drive signal is in the range of 200 Hz to 500 Hz.

[0012] In some embodiments, the resonant frequency is within 30 Hz of the maximum resonant frequency of one of the immersion substrates.

[0013] In some embodiments, the resonant frequency is within a range of frequencies demarcated by half-maximum points, at which the vibration amplitude of the substrate is half of the vibration amplitude at a maximum resonant frequency of the immersed substrate.

[0014] In some implementations, the one or more sensors include a first sensor and a second sensor, and the first sensor and the second sensor are disposed on the opposing wall of the slot.

[0015] In some embodiments, the device includes a support configured to hold the substrate in the groove. The support is configured to hold a glass panel, which serves as the substrate.

[0016] In some implementations, the one or more sensors include at least one of the following: a piezoelectric sensor, or an electrodynamic sensor including a diaphragm.

[0017] Some aspects of the present invention describe a method comprising: immersing a substrate in an electroless plating solution in a tank; vibrating the substrate at a resonant frequency; and during the vibration of the substrate, using the electroless plating solution to deposit a material onto the substrate.

[0018] This method, and other methods described herein, may have at least one or more of the following characteristics.

[0019] In some embodiments, vibrating the substrate at the resonant frequency includes vibrations configured to transmit the vibrations to one or more sensors on the substrate.

[0020] In some embodiments, the one or more sensors include at least one of the following: one or more sensors mounted to one or more walls of the tank, or one or more sensors immersed in the electroless electroplating solution.

[0021] In some embodiments, vibrating the substrate involves transmitting vibrations to the substrate through the electroless plating solution.

[0022] In some embodiments, the method includes: measuring the amplitude of a vibration of at least one of the substrate or the electroless plating solution; and determining a resonant frequency of the vibration of the substrate based on the measured amplitude of the vibration.

[0023] In some embodiments, measuring the amplitude of such vibrations includes at least one of the following: measuring the movement of the electroless plating solution, measuring a pressure of the electroless plating solution, or measuring the movement of the substrate.

[0024] In some implementations, the resonant frequency is less than 1 kHz.

[0025] In some embodiments, the resonant frequency is within 30 Hz of the maximum resonant frequency of one of the immersion substrates.

[0026] In some implementations, the substrate includes a glass panel.

[0027] In some embodiments, the method includes: vibrating the substrate at a plurality of different frequencies; measuring the vibration amplitude corresponding to at least one of the substrate or the electroless plating solution for each of the plurality of different frequencies; and determining the resonant frequency based on the measured corresponding vibration amplitudes. Simple Explanation of the Diagram

[0028] Figure 1 is a diagram illustrating an example of an electroless electroplating system.

[0029] Figure 2 is a diagram illustrating one example of resonance.

[0030] Figure 3 is a diagram illustrating an example of a drive signal generation program.

[0031] Figure 4 is a diagram illustrating an example of a signal generator.

[0032] Figure 5 is a diagram illustrating an example of a drive signal.

[0033] Figure 6 is a diagram illustrating an example of an electroless electroplating system.

[0034] Figure 7 is a diagram illustrating an example of an electroless electroplating process.

[0035] Figure 8 is a diagram illustrating an example of a computer system. Implementation

[0036] As an alternative to semiconductor and organic substrates (such as silicon wafers), glass substrates (such as glass panels) are gaining increasing attention. Compared to traditional substrates, glass substrates offer lower dielectric constants, thermal stability, ultra-low flatness, and other potential advantages.

[0037] Because glass substrates are insulators, electroless plating, which can be performed on both conductive and non-conductive substrates, is an attractive option for metallization on glass substrates. For example, electroless plating can be performed to deposit metal vias extending through the glass substrate. To perform electroless plating, a substrate is immersed in a suitable electroless plating solution, and metals or metal-containing compounds from the solution are autocatalytically deposited onto the substrate. Electroless plating can also be used for deposition on a variety of other substrates, including silicon and silicon-on-insulator (SOI) substrates, organic substrates, sapphire substrates, and substrates composed of other materials.

[0038] A typical reaction product of hydrogen-based electroless electroplating. Small hydrogen bubbles (e.g., micron-sized or submicron-sized bubbles) can adhere to the reaction surface. If these bubbles are not removed, they can be trapped in the electroless deposition film, resulting in undesirable results such as bubbles and hydrogenated films.

[0039] Mechanical stirring can be used to remove hydrogen bubbles from the reaction surface and provide improved film quality and continuity. The substrate can be agitated using a "vibration" method, in which the substrate or substrate holder is rapidly lifted and dropped onto a hard surface or otherwise shaken with high acceleration / force to generate out-of-plane vibrations, loosening the hydrogen bubbles. However, this method of bubble removal, and other existing methods, may be incompatible with the use of glass substrates, which are prone to breakage in response to mechanical vibration.

[0040] According to some embodiments of the present invention, a vibration-based method for removing bubbles during electroless deposition is provided. Compared to existing methods, vibration may be less likely to cause damage to the substrate and / or may be more effective in removing bubbles, thereby providing a higher quality electroless plating film, such as more complete via filling.

[0041] Figure 1 illustrates an example of an electroless electroplating system 100. System 100 includes a tank 124 (sometimes referred to as an electrolytic cell) in which electroless electroplating is performed on one or more substrates 120. The tank 124 may be made of, for example, stainless steel, plastic, and / or another suitable material. The substrates 120 may be held by one or more substrate holders 122 (e.g., supports with slots, wherein the substrates 120 can be positioned to hold the substrates 120 in place). Alternatively or additionally, the substrate holders 122 may include clamps, jigs, vacuum-based holders, and / or the like.

[0042] In some embodiments, substrate 120 is vertically oriented as shown in FIG1, wherein its flat or substantially flat surface faces laterally and extends vertically relative to a direction of gravity. In some embodiments, this orientation provides improved bubble removal because bubbles from the flat or substantially flat surface or vias extending from the surface may require little or no lateral travel distance to then travel freely upward away from substrate 120. In some embodiments, in addition to vertical orientation, substrates 120 are laterally spaced from each other, as shown in FIG1. ​​This configuration provides improved bubble removal because bubbles from one substrate 120 can travel upward and away from substrate 120 without encountering another substrate 120. However, other configurations and orientations are also within the scope of the invention. For example, in some embodiments, substrates 120 are horizontally oriented and / or stacked vertically spaced from each other. As another example, although FIG1 shows a substrate holder 122 at the bottom or base of one of the slots 124, the substrate holder 122 may be oppositely or additionally configured at the side and / or the top of one of the slots 124, for example, holding the substrate 120 from above. Furthermore, as mentioned above, although substrate 120 is shown as a plurality, in some embodiments there is only a single substrate 120.

[0043] Tank 124 is configured to contain an electroless plating solution, indicated in FIG. 1 by a liquid surface 126. The solution may partially fill tank 124 as shown in FIG. 1, or it may fill the entire tank 124. Tank 124, substrate 120, and / or substrate holder 122 may be configured and / or arranged such that substrate 120 is partially or completely immersed in the solution during electroless plating, for example, partially or completely submerged below liquid surface 126.

[0044] Substrate 120 may include (but is not limited to) a glass panel, a semiconductor substrate (e.g., a silicon wafer or a GaAs wafer), a silicon-on-insulator (SOI) substrate, a dielectric substrate (e.g., a sapphire substrate), and / or a printed circuit board. The procedures described herein are applicable to various substrate sizes, including large-area substrates such as glass panels with lateral dimensions of approximately 50 cm by 50 cm. Other substrate sizes (including other sizes of glass substrates) are also within the scope of this invention. For example, substrate 120 may include a silicon wafer having one diameter (e.g., 100 mm, 150 mm, 200 mm, 300 mm, 450 mm, or 675 mm) or another diameter in the range of 100 mm to 675 mm. As a further example, the glass substrate may include, for example, a panel having a length and / or width in the range of 100 mm to 1 m or more.

[0045] Depending on the selection of the substrate and the desired materials(s) to be deposited, any suitable electroless plating solution can be used for electroless plating as described herein. For example, in some embodiments, the electroless plating solution is configured to deposit nickel, copper, palladium, or gold, or an alloy thereof. In some embodiments, the electroless plating solution contains a salt of one of the metals to be deposited, a reducing agent, and one or more optional additives. For example, for depositing copper, the electroless plating solution may contain copper sulfate, a reducing agent (such as formaldehyde), a binding agent (such as tartrate), a pH adjuster (such as sodium hydroxide), and one or more stabilizers. It should be understood that the composition of the electroless plating solution is not limited herein and any composition suitable for depositing(s) of selected materials on substrate 120 is within the scope of this invention. The deposited materials(s) may contain, for example, one or more of the metals listed above, and / or metal alloys(s) such as nickel-phosphorus (Ni-P) and / or nickel-boron (Ni-B).

[0046] Referring again to Figure 1, system 100 includes components configured to vibrate substrate 120 to facilitate the removal of air bubbles from the surface of substrate 120. In some embodiments, system 100 includes one or more sensors 118 driven by a driver 102. Driver 102 includes a controller 106 that controls the operation of driver 102 (e.g., receives sensor output 114 and / or user input 128) and controls the frequency, amplitude, and / or shape of a drive signal 116 output by driver 102 and provided to sensor 118 based on sensor output 114 and / or user input 128. Driver 102 further includes a signal generator 108 configured to generate drive signal 116 based on control of controller 106. Controller 106 and signal generator 108 may be integrated into a common single device (e.g., sharing a housing and / or display) and / or may be at least partially separate. For example, in some implementations, controller 106 is a user device (e.g., a desktop or laptop computer or a mobile device such as a smartphone) separate from signal generator 108. Driver 102 may be a system comprising two or more devices implementing controller 106 and signal generator 108.

[0047] In some embodiments, drive signal 116 is provided to sensor 118 via wired connections(s). In some embodiments, drive signal 116 is provided wirelessly to sensor 118. In some embodiments, sensor 118 is configured to receive a power input (different from drive signal 116) to power its vibration. Power can be provided from an external source or wirelessly via electromagnetic charging using wired power lines (in some embodiments, such connections may be identical to those used for drive signal 116). Alternatively, sensor 118 can be powered using a built-in power source (e.g., a battery or solar charging). In some embodiments, drive signal 116 provides power to vibration, for example, such that a separate power input is not required. Further details regarding signal generator 108 are provided below with reference to FIG. 4.

[0048] Sensor 118 is configured to vibrate in response to drive signal 116, such that its vibration is transmitted to substrate 120 and causes substrate 120 to vibrate, as described below. For example, drive signal 116 having a frequency f can cause sensor 118 to vibrate at a frequency f or approximately f. Various types of sensors 118 are within the scope of this invention. In some embodiments, sensor 118 is a piezoelectric sensor comprising a piezoelectric material that vibrates in response to drive signal 116. For example, sensor 118 may have a "piezoelectric sandwich" structure in which a piezoelectric material is sandwiched between two films or layers. In some embodiments, sensor 118 is an electrodynamic sensor comprising a diaphragm configured to move in response to a magnetic field generated by drive signal 116, for example, as in a speaker or headphones. In embodiments in which sensor 118 is at least partially immersed in an electroless plating solution, sensor 118 may be composed of a material resistant to electroless plating solutions. In some embodiments, one of the vibrating elements of sensor 118 is in contact with an electroless plating solution to transmit vibrations to the solution. In some embodiments, sensor 118 has a lateral dimension similar to the lateral dimension of substrate 120. For example, one of the lateral dimensions of sensor 118 may be at least 80% or at least 100% of the lateral dimension of substrate 120, such as at least 50 cm.

[0049] For the purposes of this invention, it has been recognized that certain types of sensors 118 are particularly suitable for operation as described herein. For example, sensor 118 can be configured to operate in continuous wave mode at a power of at least 150 watts or at least 200 watts and / or at frequencies ranging from 150 Hz to 10 kHz. In some embodiments, sensor 118 comprises a seabed profiling sensor suitable for emitting acoustic pulses toward the seabed. For example, the Massa TR-1075 system manufactured by Massa Products Corporation has been found suitable as a sensor 118. The Massa TR-1075 is capable of operating in continuous wave mode at 200 watts in a range from 2.5 kHz to 10 kHz.

[0050] One or more sensors 118 may be configured in one or more locations such that vibrations of the sensors 118 are transmitted to the substrate 120 to cause corresponding vibrations of the substrate 120. In some embodiments, the sensors 118 are at least partially immersed in the electroless plating solution. For example, the sensors 118 may be suspended in the electroless plating solution in the tank 124 and / or may be mounted to several inner walls of the tank 124, such as several transverse walls and / or a bottom inner wall of the tank 124. For example, in some embodiments, as shown in FIG1, each sensor 118 is configured on one of the four transverse inner walls of the tank 124. Vibrations of the sensors 118 may be transmitted from the sensors 118 to the electroless plating solution and from the electroless plating solution to the substrate 120. For example, vibrations of the substrate 120 may be primarily based on vibrations transmitted from the electroless plating solution to the substrate 120. In some embodiments, vibrating the substrate 120 with an electroless plating solution advantageously provides a relatively spatially uniform vibration distribution to the substrate 120, which can result in effective bubble removal (e.g., removal of bubbles from the entire surface of the substrate 120).

[0051] In some embodiments, sensor 118 is mounted outside the electroless plating solution, for example, to the outer wall of one of the tanks 124. In some embodiments, sensor 118 is attached or otherwise mechanically coupled to substrate holder 122 to at least partially vibrate substrate 120 through substrate holder 122. In some embodiments, sensor 118 is attached or otherwise mechanically coupled to substrate 120, for example, to at least partially vibrate substrate 120 without coupling through the electroless plating solution or substrate holder 122. The aforementioned and other configurations of sensor 118 that allow sensor 118 to vibrate substrate 120 may be the same for all sensors 118, or sensors 118 may be configured differently from each other, for example, using one combination of the above configurations.

[0052] The substrate 120 can vibrate at a frequency that promotes bubble removal. For example, in some embodiments, the substrate 120 can vibrate at a resonant frequency. When the substrate 120 vibrates at a resonant frequency, it will naturally exhibit a larger physical response (amplitude of vibration / movement), corresponding to increased movement and increased bubble removal.

[0053] Figure 2 illustrates an example of a substrate response curve 200 showing the variation of the vibration amplitude of substrate 120 according to the vibration frequency of substrate 120. At a maximum resonant frequency f0, the vibration amplitude is maximized. A high-amplitude substrate response is also observed for a frequency range near the maximum resonant frequency f0. For example, depending on the specific characteristics of substrate 120, the electroless plating solution, and / or other aspects of the electroless plating system 100, a high-amplitude substrate response can be observed for frequencies within a range of the maximum resonant frequency f0 (e.g., from a low resonant frequency f0,L to a high resonant frequency f0,H). The frequencies between f0,L and f0,H can be collectively referred to as resonant frequencies, such that "a resonant frequency" refers to a frequency range. In some embodiments, the resonant frequencies are within approximately 20 Hz of f0, such that f0,L = f0 – 20 Hz and f0,H = f0 + 20 Hz. In some embodiments, the range from f0 is 10 Hz or 30 Hz. In some implementations, f0,L and f0,H define the frequencies of the half-maximum points of the substrate response curve 200, at which the amplitude of the substrate vibration is half of its value at the maximum resonant frequency f0.

[0054] In some embodiments, to induce the substrate 120 to vibrate at a resonant frequency, the drive signal 116 may be configured to have a substantially the same frequency. For example, a 500 Hz drive signal 116 may induce vibration of the resonant substrate at a frequency of 500 Hz or substantially matching 500 Hz. In some embodiments, a frequency of the drive signal 116 may be substantially different from the vibration frequency of the substrate 120 due to the physical response of the electroless plating system 100, the circuitry of the sensor 118, and / or the like.

[0055] Various suitable methods can be used to identify a resonant frequency and generate a drive signal 116 having a resonant frequency or otherwise causing the substrate 120 to vibrate at the resonant frequency. In some embodiments, one or more sensors (e.g., sensors 112a, 112b, 112c shown in FIG. 1) are used to perform the drive signal generation. Sensor 112a is disposed outside the tank 124 and configured to optically measure the electroless plating solution and / or the substrate 120 by receiving light 130. For example, sensor 112a may be a laser displacement sensor configured to measure the movement of one or more substrates 120 by measuring their displacement. When the substrates 120 vibrate resonantly, their displacement / movement will be greater. Sensor 112b is disposed in the tank 124 and configured to measure the movement of the electroless plating solution, for example, by detecting the wave of the electroless plating solution and / or by measuring the pressure of the electroless plating solution. For example, sensor 112b may be a pressure sensor, a wave sensor, a fluid motion detector, or the like. The movement of the electroless plating solution will be greater when substrate 120 vibrates resonantly. For example, when substrate 120 reaches resonance, the movement of the electroless plating solution may exhibit a discontinuity that varies according to the vibration frequency. In some embodiments, a sensor 112c is mechanically coupled to a substrate 120 and / or a substrate holder 122 and configured to measure a degree of movement of substrate 120, for example, using an accelerometer that measures the corresponding movement of the coupled sensor. The degree of movement is highest when substrate 120 vibrates resonantly. The aforementioned and other sensor types are configured to directly or indirectly detect / measure the vibration of substrate 120.

[0056] One or more of these and / or other sensor types and / or positioning devices can be used to measure the movement of the electroless plating solution and / or substrate 120. Sensor output 114 (e.g., containing data or signals indicating movement) can be provided to controller 106, and controller 106 can generate control signal 110 based on sensor output 114. For example, control signal 110 can control the frequency and / or amplitude of one of drive signals 116, and the frequency and / or amplitude can be determined by controller 106 based on sensor output 114.

[0057] Figure 3 illustrates an example of a program 300 for tuning drive signal 116. Program 300 may be executed, for example, by driver 102. Controller 106 may provide control signal 110 that causes signal generator 108 to generate drive signal(s) according to program 300.

[0058] Program 300 includes providing a plurality of test drive signals (302) that cause the sensor to vibrate the substrate at its respective frequencies. For example, controller 106 controls signal generator 108 to send test drive signals to sensor 118, wherein the test drive signals cause sensor 118 to vibrate substrate 120 at different respective frequencies. For example, referring to FIG2, first, second, third, and fourth test drive signals may cause substrate 120 to vibrate at frequencies f1, f2, f3, and f4, respectively. The test drive signals may have frequencies different from each other. The test drive signals may cause substrate 120 to vibrate at frequencies substantially matching the frequencies of the test drive signals. The test drive signals may cause substrate 120 to vibrate at resonant and / or non-resonant frequencies.

[0059] The procedure 300 includes receiving sensor outputs (304) that indicate the amplitude of movement and / or vibration corresponding to each of a plurality of test drive signals. For example, sensor output 114 may be received by controller 106 from one or more sensors (e.g., sensors 112a, 112b, and / or 112c). Sensor output 114 may indicate the amplitude of movement and / or vibration of one or more of the substrate 120 and / or the electroless plating solution, as discussed above. The indicated amplitude of movement and / or vibration may be absolute and / or relative.

[0060] Procedure 300 includes generating a drive signal (306) based on the received sensor output. For example, one frequency of the drive signal (e.g., drive signal 116, to be used during electroless plating) may be based on sensor output 114. In some embodiments, a test drive signal corresponding to one of the highest measured motion / vibration amplitudes is selected as the drive signal. The drive signal may have a frequency substantially matching one of the frequencies of the test drive signals that cause the highest measured motion / vibration amplitude.

[0061] In some implementations, as part of a resonant frequency identification procedure, elements of procedure 300 are executed sequentially or iteratively. For example, the drive signal frequency is scanned across a range considered to include a resonant frequency (e.g., the maximum resonant frequency f0), and the drive signal corresponding to each scanned frequency is a test drive signal. For example, starting from f1, the drive signal frequency can be scanned up to f4, and movement can be measured for each drive signal frequency. From the frequencies of the test drive signals, the drive signal frequency corresponding to the highest measured movement can be identified as a resonant frequency and used for drive signal 116. As another example, starting from f1, the drive signal frequency can be scanned upwards (corresponding to an increase in movement / vibration amplitude) until a decrease in the measured movement / vibration amplitude is detected; the immediately preceding test frequency (e.g., f0) corresponding to a maximum response can be used for drive signal 116 to cause substrate 120 to vibrate at a resonant frequency. As another example, an optimization algorithm (such as the golden section search method or a quasi-Newton method) can be used to iteratively test various test drive signal frequencies until one of the test drive signal frequencies that provides a local maximum value of the measured movement / vibration is identified; this test drive signal frequency can be used to drive the frequency of the signal 116 to cause the substrate 120 to vibrate at a resonant frequency.

[0062] The control of the test drive signal frequency, the processing of sensor output 114, the selection of the drive signal 116 frequency, frequency iteration / scanning, and / or other control and processing states of program 300 can be executed by controller 106 by providing corresponding control signals 110 to signal generator 108. In some embodiments, at least some states of program 300 or other states generated by drive signal 116 are executed based on user input 128 (which can be received by controller 106). For example, a user can input a starting frequency for the test drive signal scan, a selected frequency of the drive signal, an amplitude of drive signal 116, and / or the like.

[0063] In some implementations, in response to identifying a drive signal frequency corresponding to a resonant frequency or in response to selecting a drive signal frequency for drive signal 116, the amplitude of drive signal 116 is increased compared to the amplitude of the test drive signal. For example, for the purpose of resonant frequency identification, iterative testing with test drive signals of different frequencies can be performed using a low-amplitude signal, and the drive signal 116 generated during electroless plating can be a high-amplitude signal.

[0064] Figure 4 illustrates one example of a signal generator 108. In some embodiments, as shown in Figure 4, the signal generator 108 includes a function generator 402 and an amplifier 404. The function generator 402 generates a low-power signal 406, which is then amplified by the amplifier 404 as a drive signal 116 provided to the sensor 118. The drive signal 116 may have an amplitude greater than that of the low-power signal 406. In some embodiments, the low-power signal 406 and the drive signal 116 have the same waveform shape and / or the same frequency. For example, the drive signal 116 may be an amplified version of the low-power signal 406. A control signal 110 may cause the function generator 402 to output the low-power signal 406 at a specified frequency. For example, the control signal 110 may specify a frequency of the test drive signal during drive signal tuning as in procedure 300, and may specify a selected frequency for generating the drive signal 116 for electroless plating. The control signal 110 can cause the amplifier 404 to output the drive signal 116 with a specified amplitude or amplification level (e.g., a lower amplitude / smaller amplification during drive signal tuning as in procedure 300 and a higher amplitude and / or more amplification for generating the drive signal 116 for electroless electroplating).

[0065] Function generator 402 may include analog and / or digital circuitry configured to output signals (e.g., one or more types of periodic signals). For example, function generator 402 may be or include a tone generator. Function generator 402 may be controllable to output signals with controllable / selectable frequencies. Amplifier 404 may include any suitable analog and / or digital amplifier circuitry.

[0066] The drive signal 116 can have any suitable waveform. The drive signal 116 can be periodic. In some embodiments, the drive signal 116 is sinusoidal. In some embodiments, the drive signal 116 has a non-sinusoidal periodic shape, such as a square, triangle, or sawtooth shape.

[0067] Among other feasible factors, the frequency of the drive signal 116 may depend on several materials and / or dimensions of the substrate 120 and the composition of the electroless plating solution, such as its density and viscosity. These and / or other factors may affect the resonant frequency of the substrate 120, and the frequency of the drive signal 116 may vary accordingly to induce vibration at a resonant frequency. In some embodiments, the drive signal 116 has a frequency of at least 100 Hz. In some embodiments, the drive signal 116 has a sub-ultrasonic frequency, for example, less than 20 kHz or less than 10 kHz. In some embodiments, the drive signal has a frequency in the range of 100 Hz, 200 Hz, or 300 Hz to 500 Hz, 600 Hz, or 1000 Hz. These frequencies have been found to effectively achieve resonance in glass panels that may have an inherent resonant frequency of about 500 Hz, which decreases when the glass panel is immersed in a solution. The driver 102 (e.g., function generator 402) can be configured or controlled to output signals having such frequencies. The aforementioned frequencies and frequency ranges can also be applied to the vibration frequency of the substrate 120. For example, the drive signal 116 can be configured to cause the substrate 120 to vibrate at a frequency in the range of 200 Hz to 500 Hz.

[0068] Different types of substrates 120 may have different resonant frequencies and may vibrate at corresponding frequencies. For example, an immersed glass substrate / panel may have a resonant frequency in the range of 100 Hz, 200 Hz, or 300 Hz to 500 Hz, 600 Hz, or 1000 Hz (e.g., about 350 Hz to 450 Hz). A silicon wafer may have a resonant frequency in the range of 20 kHz to 250 kHz.

[0069] In some embodiments, when multiple sensors 118 are present, a common drive signal 116 is provided to the sensors 118. In some embodiments, different drive signals are provided to different sensors. For example, as shown in FIG5, a first drive signal 116-1 is provided to one or more first sensors 118-1, 118-2, and a second drive signal 116-2 is provided to one or more second sensors 118-3, 118-4. The first and second drive signals 116-1, 116-2 may differ in one or more aspects of amplitude, frequency, phase, and shape. In some embodiments, the first and second drive signals 116-1, 116-2 have a common frequency and a phase between them. Compared with the vibration waves from sensors 118-3, 118-4 to substrate 120, the phase can be configured to explain the different propagation times of the vibration waves from sensors 118-1, 118-2 to substrate 120, for example, based on the different distances between sensors 118 and substrate 120. For example, the phase can be configured to reduce or eliminate the phase between the respective vibrations received at the substrate 120 from sensors 118-1, 118-2 and sensors 118-3, 118-4.

[0070] Figure 6 illustrates another example of the configuration of one of the sensors 118 in a slot 124. The substrates 120 are vertically oriented and parallel to each other, extending in the yz plane and spaced apart in the x direction. Viewed from the angle of Figure 6, sensors 118-6 and 118-8 are mounted on the left and right walls (e.g., inner or outer walls) of the slot 124 (e.g., walls opposite each other along the x direction). Sensors 118-6 and 118-8 may extend along the y direction to cover most or all of the substrate 120 along the y direction. Sensor 118-5 is mounted on the bottom inner wall of one of the slots 124 and may extend along the y direction to cover most or all of the substrate 120 along the y direction. Sensors 118-9, 118-10, 118-11, and 118-12 are positioned at the corners of the slot 124 to provide a "loudspeaker effect" that enhances the vibration of the substrate 120. Although not shown in Figure 6, from the angle of Figure 6, the sensor 118 may be mounted opposite or additionally on the inner wall of the slot 124 before / after (e.g., walls opposite each other in the y direction).

[0071] Figure 7 illustrates an example of a process 700 for electroless electroplating. Process 700 can be performed using the electroless electroplating system and apparatus described herein and using the methods and procedures described with respect to Figures 1 to 6. For example, process 700 can be performed using electroless electroplating system 100. All descriptions provided with respect to Figures 1 to 6 also apply to process 700.

[0072] As shown in Figure 7, process 700 includes immersing a substrate in an electroless plating solution (702). For example, the substrate may be a glass panel, and the electroless plating solution may be any suitable solution for electroless deposition of a metal or metal alloy onto the substrate. For example, the electroless plating solution may contain at least a metal salt and a reducing agent.

[0073] The procedure 700 includes vibrating a substrate (704) at a resonant frequency of one of the substrates. For example, one or more sensors may be vibrated, and the vibration of the sensors may be transmitted to the substrate to cause vibration at a resonant frequency.

[0074] Procedure 700 includes depositing a material onto the substrate using an electroless plating solution during substrate vibration (706). For example, the electroless plating solution can autocatalytically deposit a metal or metal alloy onto the substrate. In some embodiments, operation 706 includes heating the electroless plating solution and / or the substrate to a high temperature (e.g., at least 50°C). The material may include, for example, nickel, copper, palladium, gold, or an alloy thereof. In some embodiments, a conductive via is formed through the deposited material. In some embodiments, a trace or conductive plane is formed on the substrate by the deposited material.

[0075] For example, based on the deposition rate and target layer thickness, electroless plating during resonant frequency vibration can be performed for any suitable duration. For example, in some embodiments, electroless plating is performed for a duration ranging from 10 minutes to 60 minutes. After electroless plating is complete, the substrate can be removed from its tank and moved to another tank for rinsing. The rinsed substrate can then be dried, and further processing can be performed. For example, in some embodiments, the substrate is annealed after drying. In some embodiments, electroplating is performed to deposit additional conductive material on the electroless deposition layer.

[0076] Figure 8 is a block diagram illustrating a computer system 800. In some embodiments, the controller 106 is similar to or associated with a computer system (such as computer system 800). The computer system 800 can be configured to perform the operations described herein and performed by the controller 106.

[0077] Computer system 800 can refer to any system that includes a general-purpose or special-purpose computing system. For example, computer system 800 can include a personal computer, a server computer, a cloud computing system, a laptop computer, a household appliance, and the like. As shown in Figure 8, computer system 800 can include at least one processor 810, a memory 820, a storage system 830, a network adapter 840, an input / output (I / O) interface 850, and a display 860.

[0078] At least one processor 810 can execute a program module containing computer system executable instructions. The program module may include routines, programs, objects, components, logic, data structures, and the like that perform a specific task or implement a specific type of abstract data. Memory 820 may include a computer system readable, non-transitory medium in the form of volatile memory (such as random access memory (RAM)). At least one processor 810 can access memory 820 and execute instructions loaded into memory 820. Storage system 830 can non-volatilely store information and may include at least one program product comprising a program module configured to control a driver 102 as described herein (e.g., processing sensor output 114 and / or generating control signals 110). By way of non-limiting examples, a program may include an operating system, at least one application, other program modules, and program data.

[0079] Network adapter 840 provides a connection to a local area network (LAN), a wide area network (WAN), and / or a shared network (such as the Internet). I / O interface 850 provides a communication channel with a peripheral device (such as a keyboard, an indicator device, and an audio system). Display 860 can output various information segments for the user to view.

[0080] In some implementations, the control, tuning, driving, and other procedures disclosed above are implemented as a computer program product or implemented using a computer program product. The computer program product may include a non-transitory computer-readable medium (or storage medium) containing computer-readable program instructions for causing at least one processor 810 to perform driver control. The computer-readable instructions may be (but are not limited to) compiler instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, status setting data, or source or object code written in at least one programming language.

[0081] Computer-readable media can be any type of media capable of non-temporarily storing and storing instructions executable by at least one processor 810 or any instruction-executable device. Computer-readable media can be an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any combination thereof, but is not limited thereto. For example, computer-readable media can be a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an electrically erasable read-only memory (EEPROM), a flash memory, a static random access memory (SRAM), an optical disc (CD), a digital versatile disc (DVD), a memory stick, a floppy disk, a mechanical encoding device (such as a punch card), or any combination thereof.

[0082] Several embodiments have been described. However, it should be understood that various modifications can be made. Although the present invention contains numerous details of specific embodiments, these details should not be construed as limiting the scope of any invention or claim, but rather as descriptions of features characteristic of a particular embodiment of a particular invention. Certain features described in the context of individual embodiments of the invention may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented individually in multiple embodiments or in any suitable sub-combination. Furthermore, although features may be described above as acting in a particular combination, and even initially claimed as such, one or more features from a claimed combination may, in some cases, be removed from that combination, and the claimed combination may refer to a sub-combination or a variation thereof.

[0083] Similarly, although operations are depicted in a specific order in the diagram, this should not be construed as requiring the operations to be performed in the specific order shown or in sequence, or to perform all the drawn operations to achieve the desired result.

[0084] 100: Electroless Electroplating System

[0085] 102: Drive

[0086] 106: Controller

[0087] 108: Signal Generator

[0088] 110: Control signal

[0089] 112a: Sensor

[0090] 112b: Sensor

[0091] 112c: Sensor

[0092] 114: Sensor Output

[0093] 116: Drive signal

[0094] 116-1: First drive signal

[0095] 116-2: Second drive signal

[0096] 118: Sensor

[0097] 118-1: Sensor

[0098] 118-2: Sensor

[0099] 118-3: Sensor

[0100] 118-4: Sensor

[0101] 118-5: Sensor

[0102] 118-6: Sensor

[0103] 118-8: Sensor

[0104] 118-9: Sensor

[0105] 118-10: Sensors

[0106] 118-11: Sensors

[0107] 118-12: Sensors

[0108] 120:Substrate

[0109] 122:Substrate holder

[0110] 124: slot

[0111] 126: Liquid surface

[0112] 128: User Input

[0113] 130: Light

[0114] 200: Substrate response curve

[0115] 300: Program

[0116] 302: Provides a plurality of test drive signals that cause the sensor to vibrate the substrate at its respective frequency.

[0117] 304: Receives sensor outputs indicating the movement and / or vibration amplitude corresponding to each of a plurality of drive test signals.

[0118] 306: Generate a drive signal based on the received sensor output.

[0119] 402: Function Generator

[0120] 404: Amplifier

[0121] 406: Low power signal

[0122] 700: Program

[0123] 702: Immerse the substrate in an electroless electroplating solution.

[0124] 704: The substrate vibrates at its resonant frequency.

[0125] 706: Depositing material on a substrate using an electroless plating solution during substrate vibration.

[0126] 800: Computer System

[0127] 810: Processor

[0128] 820: Memory

[0129] 830: Storage System

[0130] 840: Network Adapter

[0131] 850: Input / Output (I / O) Interface

[0132] 860: Monitor

Claims

1. An electroless electroplating apparatus, comprising: A tank configured to contain an electroless plating solution and a substrate on which electroless plating is to be performed, the substrate being immersed in the electroless plating solution; one or more sensors configured to transmit vibrations to the substrate; and a driver configured to provide a drive signal to the one or more sensors, wherein the drive signal is configured to cause the one or more sensors to vibrate the substrate at one of the resonant frequencies of the substrate.

2. The device as requested in item 1, wherein the one or more sensors are mounted to one or more walls of the slot.

3. The device of claim 1, wherein the one or more sensors are configured to be immersed in the electroless plating solution.

4. The device of claim 1, comprising a sensor configured to detect vibration of at least one of the substrate or the electroless plating solution, wherein the driver is configured to: receive from the sensor an output indicating the detection of vibration of the substrate; and generate the drive signal in response to receiving the output from the sensor.

5. The device as claimed in claim 4, wherein the sensor includes: A motion sensor configured to detect the movement of the electroless plating solution, a pressure sensor configured to detect a pressure of the electroless plating solution, an optical sensor configured to detect the movement of the substrate, or a motion sensor configured to detect the movement of the substrate.

6. The device of claim 4, wherein the driver is configured to: provide a plurality of test drive signals to the one or more sensors, wherein the plurality of test drive signals are configured to cause the one or more sensors to vibrate the substrate at different respective frequencies; receive a corresponding output from the sensor for each of the plurality of test drive signals, the corresponding output indicating an amplitude of the vibration of the substrate caused by the test drive signal; and generate the drive signal in response to receiving the corresponding outputs from the sensor, wherein a frequency of the drive signal is based on the amplitude of the vibration caused by the plurality of test drive signals.

7. The device of claim 1, wherein the drive signal has a frequency of less than 1 kHz.

8. The device of claim 1, wherein the resonant frequency is within 30 Hz of one of the maximum resonant frequencies of the immersion substrate.

9. The apparatus of claim 1, comprising a support configured to hold the substrate in the groove, wherein the support is configured to hold a glass panel serving as the substrate.

10. The device of claim 1, wherein the one or more sensors include at least one of the following: a piezoelectric sensor, or an electrodynamic transducer comprising a diaphragm.

11. An electroless electroplating method, comprising: A substrate is immersed in an electroless electroplating solution in a tank; The substrate vibrates at one of its resonant frequencies; During the vibration of the substrate, an electroless plating solution is used to deposit a material onto the substrate.

12. The method of claim 11, wherein vibrating the substrate at the resonant frequency includes the vibration being configured to transmit the vibration to one or more sensors on the substrate.

13. The method of claim 12, wherein the one or more sensors include at least one of the following: one or more sensors mounted to one or more walls of the tank, or one or more sensors immersed in the electroless plating solution.

14. The method of claim 11, wherein vibrating the substrate includes transmitting vibration to the substrate through the electroless plating solution.

15. The method of claim 11, comprising: Measure the amplitude of the vibration of at least one of the substrate or the electroless plating solution; And based on the measured amplitude of such vibrations, a resonant frequency of the vibration of the substrate is determined.

16. The method of claim 15, wherein measuring the amplitude of the vibrations includes at least one of: measuring the movement of the electroless plating solution, measuring a pressure of the electroless plating solution, or measuring the movement of the substrate.

17. The method of claim 11, wherein the resonant frequency is less than 1 kHz.

18. The method of claim 11, wherein the resonant frequency is within 30 Hz of one of the maximum resonant frequencies of the immersion substrate.

19. The method of claim 11, wherein the substrate includes a glass panel.

20. The method of claim 11, comprising: The substrate vibrates at multiple different frequencies; For each of the plurality of different frequencies, the vibration amplitude corresponding to at least one of the substrate or the electroless plating solution is measured; and the resonant frequency is determined based on the measured corresponding vibration amplitudes.

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