Cleaning device and cleaning method based on variable-frequency ultrasonic excitation

Abstract

The invention provides a cleaning device and a cleaning method based on variable-frequency ultrasonic excitation, and solves the technical problem that ultrasonic cleaning with single frequency is often difficult to meet requirements in occasions where workpieces with complex shapes are treated or high-precision cleaning is required. The cleaning device comprises an ultrasonic signal driving circuit and a cleaning machine, the cleaning machine comprises groove type cleaning equipment, a flower basket is arranged in the groove type cleaning equipment, a semiconductor wafer is clamped in the flower basket, a vibration plate is arranged at one end of the groove type cleaning equipment, and the vibration plate is connected with the ultrasonic signal driving circuit. At least two piezoelectric ceramics are fixedly arranged at the end, away from the groove type cleaning equipment, of the vibration plate, the ultrasonic drive circuit is used for providing high-frequency signals for the piezoelectric ceramics, local turbulence is generated in the groove type cleaning equipment, and the cleaning effect on semiconductor wafers is improved.

Description

Technical Field

[0001] The present invention relates to a cleaning method and device based on variable frequency ultrasonic excitation, which realizes the removal of microparticles by realizing local eddy current through superposition of vibrations caused by multiple frequencies during ultrasonic transmission in liquid in a cleaning tank. Background Art

[0002] In the field of ultrasonic cleaning technology, traditional methods usually rely on single-frequency ultrasonic vibrations to produce cavitation effects and microjets to achieve the purpose of cleaning. Although this method can effectively remove stains and microparticles on the surface of objects to a certain extent, its cleaning efficiency and effect are often limited by the propagation characteristics of ultrasonic waves in liquids and the formation and rupture mechanism of cavitation bubbles. Especially in the case of processing complex-shaped workpieces or requiring high-precision cleaning, single-frequency ultrasonic cleaning often cannot meet the needs.

[0003] In recent years, with the continuous development of ultrasonic technology, variable frequency ultrasonic technology has gradually become a research hotspot. By changing the frequency of ultrasonic waves, variable frequency ultrasonic technology can adjust the propagation characteristics of ultrasonic waves in liquids, including wavelength, wave speed, and the formation conditions of cavitation bubbles. The advantage of this technology is that it can flexibly select or combine different ultrasonic frequencies according to different cleaning needs to achieve the best cleaning effect.

[0004] In the cleaning method based on variable frequency ultrasound, the superposition application of multiple frequency ultrasound is an important research direction. When ultrasound waves of different frequencies propagate simultaneously in the liquid in the cleaning tank, they interact with each other, resulting in a vibration superposition effect. This superposition not only enhances the energy density of ultrasound in the liquid, but also changes the flow state of the liquid, especially forming local eddies in certain specific areas.

[0005] The formation of local eddy currents is one of the important results of the superposition of multiple frequency ultrasonic waves. Eddy currents are a rotating fluid motion that can form strong shear and impact forces in the cleaning tank. These forces can act more effectively on the microparticles on the surface of the object, peeling them off the surface and dispersing them into the cleaning fluid, thereby achieving more efficient cleaning. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a cleaning device and a cleaning method based on variable frequency ultrasonic excitation, which solves the technical problem that single frequency ultrasonic cleaning often fails to meet the requirements when processing complex-shaped workpieces or requiring high-precision cleaning.

[0007] The above technical objectives of the present invention are achieved through the following technical solutions:

[0008] A cleaning device based on variable frequency ultrasonic excitation includes: an ultrasonic signal driving circuit and a cleaning machine, wherein the cleaning machine includes a trough-type cleaning device, wherein a flower basket is provided in the trough-type cleaning device, wherein a semiconductor wafer is clamped in the flower basket, wherein a vibration plate is provided at one end of the trough-type cleaning device, wherein at least two piezoelectric ceramics are fixedly provided at one end of the vibration plate away from the trough-type cleaning device, and wherein the ultrasonic driving circuit is used to provide a high-frequency signal to the piezoelectric ceramic.

[0009] The ultrasonic signal driving circuit comprises a use end, one end of the use end is connected to a DAC, one end of the DAC is connected to a PWM, one end of the PWM is connected to a power amplifier module, and the power amplifier module is connected to the piezoelectric ceramic.

[0010] The flower basket is made of porous material.

[0011] The vibration plate and the piezoelectric ceramic are connected via insulating glue.

[0012] The insulating glue is epoxy resin or the like.

[0013] Each piece of the piezoelectric ceramic has a different natural frequency.

[0014] The present invention also provides a cleaning method based on variable frequency ultrasonic excitation, comprising the following steps:

[0015] S1. Fill the tank cleaning equipment with pure water or cleaning liquid;

[0016] S2, placing the semiconductor wafer to be cleaned into the flower basket;

[0017] S3, the user terminal issues a cleaning instruction;

[0018] S4, the instruction drives the PWM module to generate sine wave signals of different frequencies after analog-to-digital conversion by DAC;

[0019] S5, the power amplifier module amplifies the sine wave signal voltage and connects it to piezoelectric ceramics with different natural frequencies;

[0020] S6. The vibration of the piezoelectric ceramics causes local turbulence in the liquid inside the tank cleaning equipment to clean the semiconductor wafer.

[0021] The voltage of the sine wave signal is amplified to 200V or above.

[0022] The ultrasonic frequency excited by the power amplifier module is a high-frequency signal between 200kHz and 1MHz.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. By precisely controlling the superposition of multiple frequency ultrasonic waves, a local vortex is formed in the liquid in the cleaning tank, thereby achieving efficient removal of microparticles;

[0025] 2. It improves the cleaning efficiency and quality, and expands the application scope of ultrasonic cleaning technology;

[0026] 3. Improve the mixing uniformity of the cleaning liquid, accelerate the chemical reaction in the cleaning liquid (such as oxidation, reduction, etc.), and further enhance the cleaning effect;

[0027] 4. Due to the rotational characteristics of the eddy current, it can more effectively clean the blind holes, grooves and other hard-to-reach areas on the surface of the workpiece, improving the comprehensiveness and thoroughness of the cleaning;

[0028] 5. It is not limited by the fixed frequency of traditional ultrasonic cleaning equipment. Through the combination of ultrasonic vibrations of different frequencies, local eddy currents can be achieved inside the cleaning tank to improve the cleaning effect. According to experimental results, it can remove 0.1 micron-level microparticles remaining on the semiconductor wafer in the tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural diagram of the cleaning tank and piezoelectric ceramics;

[0030] Figure 2 is the arrangement diagram of the piezoelectric ceramics;

[0031] Figure 3 It is the circuit schematic diagram of variable frequency drive signal.

[0032] In the above drawings: 101, tank cleaning equipment; 102, flower basket; 103, semiconductor wafer; 104, vibration plate; 105, piezoelectric ceramic; 301, user end; 302, DAC; 303, PWM; 304, power amplifier module. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0034] Example:

[0035] A cleaning device based on variable frequency ultrasonic excitation includes: an ultrasonic signal driving circuit and a cleaning machine, wherein the cleaning machine includes a tank cleaning device 101, wherein a flower basket 102 is arranged in the tank cleaning device 101, wherein a semiconductor wafer 103 is clamped in the flower basket 102, wherein the flower basket 102 is directly sunk into a liquid so that the semiconductor wafer 103 is immersed in the liquid, and the flower basket 102 can be taken out or put in by a mechanical arm, wherein a vibration plate 104 is arranged at one end of the tank cleaning device 101, and the vibration plate 104 can be fixed to the tank cleaning device 101 by insulating glue or the vibration plate 104 can be fixed to the tank cleaning device 101 by mechanical pressure, preferably, as Figure 1As shown, in this embodiment, the vibration plate 104 is fixed to the tank cleaning device 101 by insulating glue. At least two piezoelectric ceramics 105 are fixed to one end of the vibration plate 104 away from the tank cleaning device 101. Preferably, as shown in FIG. Figure 2 As shown, in this embodiment, the piezoelectric ceramic 105 includes 9 pieces. The positive and negative electrodes of the piezoelectric ceramic 105 are welded by flanges, and there is an annular gap between the positive and negative electrodes. Each piezoelectric ceramic 105 has a different natural frequency, and the frequency of the piezoelectric ceramic 105 is between 200kHz and 1MHz. The ultrasonic drive circuit is used to provide a high-frequency signal to the piezoelectric ceramic 105.

[0036] The ultrasonic signal driving circuit includes a use end 301, one end of which is connected to a DAC 302, where DAC is a digital-to-analog converter. One end of the DAC 302 is connected to a PWM 303, where PWM is Pulse Width Modulation. One end of the PWM 303 is connected to a power amplifier module 304, which is connected to the piezoelectric ceramic 105.

[0037] The cleaning machine includes a tank cleaning device 101, in which a flower basket 102 is arranged. The flower basket 102 is made of porous material, which is conducive to the passage of liquid. A semiconductor wafer 103 is sandwiched in the flower basket 102. A vibration plate 104 is arranged at one end of the tank cleaning device 101. At least two piezoelectric ceramics 105 are fixedly arranged at one end of the vibration plate 104 away from the tank cleaning device 101. The ultrasonic frequency excited by the power amplifier module 304 is a high-frequency signal between 200kHz and 1MHz, wherein the ultrasonic signal of 200kHz to 400kHz excites a part of the piezoelectric ceramics 105 to realize the cavitation effect to generate impact force to remove particles larger than 0.5 microns, and the ultrasonic signal of 400kHz to 1Mhz excites the remaining piezoelectric ceramics 105 to realize the micro-flow effect to remove micro-particles between 0.2-0.5 microns, and the local eddy current generated by the superposition of vibrations of multiple frequencies further removes micro-particles between 0.01-0.2 microns.

[0038] The vibration plate 104 and the piezoelectric ceramic 105 are connected by insulating glue.

[0039] The insulating glue is epoxy resin or the like.

[0040] The present invention also provides a cleaning method based on variable frequency ultrasonic excitation, comprising the following steps:

[0041] S1, pure water or cleaning liquid is placed inside the tank cleaning device 101;

[0042] S2, placing the semiconductor wafer 103 to be cleaned into the flower basket 102;

[0043] S3, the user terminal 301 issues a cleaning instruction;

[0044] S4, the instruction drives the PWM module 303 to generate sine wave signals of different frequencies after analog-to-digital conversion by DAC 302;

[0045] S5, the power amplifier module 304 amplifies the sine wave signal voltage and connects it to the piezoelectric ceramics 105 with different natural frequencies;

[0046] S6 , the piezoelectric ceramic 105 vibrates to generate local turbulence in the liquid inside the tank-type cleaning equipment to clean the semiconductor wafer 103 .

[0047] The voltage of the sine wave signal is amplified to 200V or above, preferably, the voltage of the sine wave signal is amplified to 200-300V.

[0048] The ultrasonic wave frequency excited by the power amplifier module 304 is a high frequency signal between 200 kHz and 1 MHz.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A cleaning device based on variable frequency ultrasonic excitation, characterized in that: include: An ultrasonic signal driving circuit and a cleaning machine, the cleaning machine comprising a tank-type cleaning device (101), wherein a flower basket (102) is provided in the tank-type cleaning device (101), wherein a semiconductor wafer (103) is clamped in the flower basket (102), wherein a vibration plate (104) is provided at one end of the tank-type cleaning device (101), wherein at least two piezoelectric ceramics (105) are fixedly provided at one end of the vibration plate (104) away from the tank-type cleaning device (101), and wherein the ultrasonic driving circuit is used to provide a high-frequency signal to the piezoelectric ceramics (105).

2. A cleaning device based on variable frequency ultrasonic excitation according to claim 1, characterized in that: The ultrasonic signal driving circuit comprises a use end (301), one end of the use end (301) is connected to a DAC (302), one end of the DAC (302) is connected to a PWM (303), one end of the PWM (303) is connected to a power amplifier module (304), and the power amplifier module (304) is connected to the piezoelectric ceramic (105).

3. A cleaning device based on variable frequency ultrasonic excitation according to claim 2, characterized in that: The flower basket (102) is made of porous material.

4. A cleaning device based on variable frequency ultrasonic excitation according to claim 2, characterized in that: The vibration plate (104) and the piezoelectric ceramic (105) are connected via insulating glue.

5. The cleaning device based on variable frequency ultrasonic excitation according to claim 2, characterized in that: The insulating glue is epoxy resin or the like.

6. The cleaning device based on variable frequency ultrasonic excitation according to claim 2, characterized in that: Each piece of the piezoelectric ceramic (105) has a different natural frequency.

7. A cleaning method for a cleaning device based on variable frequency ultrasonic excitation according to claims 1-6, characterized in that: The following steps are involved: S1, filling the tank-type cleaning device (101) with pure water or cleaning liquid; S2, placing the semiconductor wafer (103) to be cleaned into the flower basket (102); S3, the user end (301) issues a cleaning instruction; S4, the instruction drives the PWM module (303) to generate sine wave signals of different frequencies after analog-to-digital conversion by the DAC (302); S5, the power amplifier module (304) amplifies the sine wave signal voltage and connects it to piezoelectric ceramics (105) with different natural frequencies; S6. The piezoelectric ceramic (105) vibrates to generate local turbulence in the liquid inside the tank cleaning device to clean the semiconductor wafer (103).

8. The cleaning method based on variable frequency ultrasonic excitation according to claim 7, characterized in that: The voltage of the sine wave signal is amplified to 200V or above.

9. The cleaning method based on variable frequency ultrasonic excitation according to claim 7, characterized in that: The ultrasonic wave frequency excited by the power amplifier module (304) is a high frequency signal between 200kHz and 1MHz.

Images