CN204442197U - A kind of pulsed sputter power supply - Google Patents

Abstract

A pulse sputtering power supply, comprising a sequentially connected three-phase rectifier circuit, an inverter circuit, a high-frequency transformer, a rectifier filter circuit, and a pulse generating circuit; L-tap a-end; inductor L-tap o-end connected to the negative pole of the DC power supply circuit, inductor L-tap b-end connected to the target of the magnetron sputtering device, and the V input end of the switch tube and the substrate of the magnetron sputtering device to be connected to the DC power supply circuit positive pole; the control terminal of the switching tube V is connected with the PWM control circuit. The utility model solves the power supply reliability drop caused by too many power switch tubes in the prior art, and provides a pulse sputtering power supply with good dynamic characteristics, low cost, simple and reliable control, and energy feedback.

Description

A pulse sputtering power supply

technical field

The invention relates to the technical field of magnetron sputtering, in particular to a pulse sputtering power supply.

Background technique

Thin film deposition is the use of energetic ions in the plasma to bombard the surface of the target in a vacuum environment, so that the bombarded atoms or ions on the target are deposited on the surface of the substrate to grow into a thin film with specific functions. Magnetron sputtering technology is a kind of thin film deposition process. It is a sputtering coating process that uses electromagnetic fields to control the trajectory and distribution of ions and electrons in the abnormal glow discharge of gases in a vacuum chamber.

At present, the magnetron sputtering power supply developed at home and abroad mainly includes several types such as DC sputtering power supply, radio frequency sputtering power supply, intermediate frequency sputtering power supply, and pulse sputtering power supply. Intermediate frequency sputtering, radio frequency sputtering and pulse sputtering can overcome the charge accumulation and discharge when making a reaction film during DC sputtering, effectively solve the phenomenon of serious target poisoning, and overcome the phenomenon of anode disappearance during sputtering. Intermediate frequency sputtering requires two twin targets, and the sputtering rate is lower than pulse sputtering. The operating frequency of RF sputtering power supply is more than ten megahertz, and the equipment cost is very high, while pulse sputtering can be directly carried out on DC sputtering equipment. Only a single target is needed, the sputtering rate is higher than that of intermediate frequency sputtering, the operating frequency is tens of kilohertz, and the cost is much lower than that of RF sputtering power supply. The pulse sputtering power supply uses a rectangular wave voltage pulse power supply instead of the traditional DC sputtering power supply for film deposition.

Chinese patent (application number: CN201310024628) discloses a high-energy pulsed magnetron sputtering method and a magnetron sputtering device, wherein the high-energy pulsed magnetron sputtering device includes a vacuum chamber, vacuum equipment, power supply . The central control unit, wherein the power supply includes a pulse generating unit, a bias power supply and a DC power supply; the bias power supply is connected to the sample, the DC power supply is connected to the target, and the pulse generating unit passes The data line is connected with the central control unit, and the pulse generating unit is driven by a DC power supply to generate a pulse current, and outputs the current to the target in the vacuum chamber. However, the high-energy pulsed magnetron sputtering device does not describe the circuit structure of the magnetron sputtering device in detail, but only describes its working principle, which makes it impossible for those skilled in the art to design according to its disclosure.

The Journal of Xi'an University of Technology (Volume 29, No. 2, 2013, author: Chen Guitao, etc.) discloses a new type of FPGA-based asymmetric bipolar pulse magnetron sputtering power supply. This document studies the FPGA-based asymmetric bipolar The extremely pulsed power supply solves the common problems encountered in the magnetron sputtering process, and at the same time obtains excellent film performance and a wider process range. Bidirectional pulse parameters including pulse amplitude, frequency, duty cycle, number of positive and negative directions, and commutation time between positive and negative pulses can be freely adjusted according to the process requirements of the magnetron sputtering power supply. Finally, a 6kW/100kHz prototype is designed. Two independent DC/DC converters are used as DC sources in the front stage, and an asymmetric pulse generator is used in the rear stage. Altera's FPGA (EP3C25Q240C8) is used as the digital processor to realize the digital control of the power supply, and at the same time realize the high-degree-of-freedom control of the post-stage pulse conversion link. The feasibility of the design is further verified through the analysis of experimental results. However, the rectangular voltage generation part of the magnetron sputtering power supply is realized by a full-bridge inverter plus rectification, the number of power switch tubes is large, the cost of the power supply is increased, and the control of the power supply is complicated, which affects the reliability of the power supply.

Utility model content

The utility model aims at the deficiencies in the prior art, and provides a high-power pulse magnetron sputtering power supply with stable performance, low cost and high pulse peak voltage.

The utility model is realized through the following technical solutions: a pulse sputtering power supply, including a sequentially connected three-phase rectification circuit, an inverter circuit, a high-frequency transformer, a rectification filter circuit, and a pulse generation circuit; it is characterized in that: the pulse generation The structure of the circuit is as follows: the V output terminal of the switching tube is connected to the a terminal of the L tap of the inductor; the O terminal of the L tap of the inductor is connected to the negative pole of the DC power supply circuit, the b terminal of the L tap of the inductor is connected to the target of the magnetron sputtering device, and the V input of the switching tube The terminal and the substrate of the magnetron sputtering device are connected to the positive pole of the DC power supply circuit; the control terminal of the switching tube V is connected to the PWM control circuit.

Preferably: also include central processing unit, drive circuit, signal acquisition module, protection module, upper computer, liquid crystal display module, signal input module; Described central processing unit is ARM system; Described signal acquisition module comprises voltage sampling circuit, current Sampling circuit; the protection module includes overcurrent and short circuit protection circuits.

Preferably, the input end of the three-phase rectifier circuit is connected to the output end of the air switch; the input end of the air switch is connected to a quick recoverable fuse.

Preferably, the drive circuit includes a drive for an inverter circuit and a drive for a pulse generating circuit; the drive signal for the drive circuit is generated by an ARM system and processed by a photoelectric isolation circuit.

Preferably, the current sampling circuit includes a sampling circuit for the output current of the rectification filter circuit and the output current of the pulse generating circuit.

Preferably, the current sampling circuit includes a current sensor, and the current sensor adopts a Hall current sensor.

Preferably, the voltage sampling circuit includes a sampling circuit for the output voltage of the rectification and filtering circuit and for the output voltage of the pulse generating circuit.

Preferably, the voltage sampling circuit and the current sampling circuit are transmitted to the ARM control chip after passing through the A/D sampling circuit.

Preferably, the signal transmission between the upper computer and the ARM system is wireless transmission, preferably 4G network transmission.

Beneficial effects: the utility model solves the power supply reliability drop caused by too many power switch tubes in the prior art, and provides a pulse sputtering power supply with good dynamic characteristics, low cost, and simple and reliable control.

Description of drawings

Accompanying drawing 1 is the structural representation of the utility model;

Accompanying drawing 2 is the utility model DC power supply circuit structure schematic diagram

Accompanying drawing 3 is the structure schematic diagram of the utility model pulse generating circuit;

Accompanying drawing 4 is the utility model voltage sampling circuit schematic diagram;

Accompanying drawing 5 is the schematic diagram of the utility model current sampling circuit;

Accompanying drawing 6 is the schematic diagram of the utility model overcurrent short-circuit protection circuit;

Accompanying drawing 7 is the voltage sampling flowchart of the utility model.

Detailed ways

See attached drawing 1.

A pulse sputtering power supply, comprising a sequentially connected three-phase rectifying circuit, an inverter circuit, a high-frequency transformer, a rectifying and filtering circuit, and a pulse generating circuit; it is characterized in that it includes a central processing unit, a driving circuit, a signal acquisition module, and a protection module , host computer, liquid crystal display module, signal input module; the central processing unit is an ARM system; the signal acquisition module includes a voltage sampling circuit, a current sampling circuit; the protection module includes an overcurrent and short circuit protection circuit. The input end of the three-phase rectifier circuit is connected to the output end of the air switch; the input end of the air switch is connected to a fast recoverable fuse. The drive circuit includes a drive for an inverter circuit and a drive for a pulse generating circuit; the drive signal of the drive circuit is generated by an ARM system and processed by a photoelectric isolation circuit. The current sampling circuit includes a sampling circuit for the output current of the rectification filter circuit and the output current of the pulse generating circuit. The current sampling circuit includes a current sensor, and the current sensor adopts a Hall current sensor. The voltage sampling circuit includes a circuit for sampling the output voltage of the rectification and filtering circuit and the output voltage of the pulse generating circuit. The voltage sampling circuit and the current sampling circuit are transmitted to the ARM system after passing through the A/D sampling circuit. The signal transmission between the upper computer and the ARM system is wireless transmission, preferably 4G network transmission. The signal input of the ARM system is keyboard input or wireless input; the display of the ARM system is liquid crystal display or digital tube display.

See attached drawing 2. The three-phase rectification circuit, the inverter circuit, the high-frequency transformer, and the rectification filter form a DC power supply circuit. Rectifier bridge D1 and filter capacitor C2 form a three-phase rectifier circuit; Q1, Q2, Q3 and Q4 form an inverter circuit; T1 is a high-frequency transformer; rectifier bridge D2, inductor Lo, and capacitor C4 form a rectifier filter circuit. The switching tube Q1 and the switching tube Q4 of the inverter circuit, and the switching tube Q2 and the switching tube Q3 are turned on and off alternately.

The three-phase 380V AC is transformed into 540V DC by the rectifier circuit, the DC is converted into 20KHZ AC by the inverter circuit and sent to the high-frequency transformer for step-up conversion, and the high-voltage and high-frequency AC is converted into DC by rectification and filtering .

The ARM system includes an ARM microcontroller: keyboard input and liquid crystal display are mainly responsible for the preset of power supply parameters and the display of power supply working status. In addition, the ARM system has strong communication capabilities and can communicate with external computers through dedicated interfaces. It is very convenient to implement network management and upgrade of software control program. The ARM system uses the sensor to sample the current and voltage signals, and directly inputs the current and voltage feedback signals into the ARM through signal processing, and converts the analog signals of the current and voltage feedback into digital signals through the A/D converter inside the ARM; The given signals of current, voltage, frequency, and pulse width input by the keyboard are transmitted to ARM in the form of digital quantities; ARM performs calculations based on digital PID control according to the given values and feedback values of each signal to generate PWM pulse sequences; ARM output The PWM signal controls the on-off of the power switching device IGBT in the inverter circuit and the pulse generation circuit through the photoelectric isolation and drive circuit, and obtains the set output voltage and current. The ARM controller is preferably ARM8.

See Figure 3. The structure of the pulse generating circuit is as follows: the V output terminal of the switching tube is connected to the a terminal of the inductance L tap, the o terminal of the inductance L tap is connected to the negative pole of the DC power supply circuit, and the b terminal of the inductance L tap is connected to the target of the magnetron sputtering device. The input terminal of the switch tube V is connected to the positive pole of the DC power supply circuit with the substrate of the magnetron sputtering device; the control terminal of the switch tube V is connected to the PWM control circuit; after the PWM control circuit generates a PWM control signal, it passes through the photoelectric isolation circuit, drives The circuit then controls the on and off of the switching tube in the pulse generating circuit. The switching tube V of the pulse generating circuit is an IGBT tube.

The DC power supply circuit is used to generate DC power, the voltage and current of which are monitored and controlled by the PWM control circuit. The pulse generating circuit is used to generate high-frequency power pulses, and its frequency and duty ratio are controlled by a PWM control circuit. The PWM control circuit is used to collect voltage and current signals, send out DC power supply circuit control signals, and send out pulse generation circuit control signals.

The working principle of the pulse generating circuit: the PWM control circuit controls the switch tube V of the pulse generating circuit to turn on and off. When the switching tube V is turned off, the current flows out from the positive pole of the DC power supply, supplies power to the plasma, and flows back to the negative pole of the DC power supply through the inductor L. At this time, the voltage polarity of the inductor L is negative at the terminal o and positive at the terminal b, storing electric energy; The accumulation of positive charges on the surface of the target causes the plasma load to exhibit capacitive properties. Its polarity is positive up and negative down. When the switch tube V is turned on, the inductance L acts as a transformer at this time. Terminal a and terminal a are output terminals, terminal a and terminal b are terminals with the same name, terminal a and terminal o of the inductor L are connected to the DC power supply circuit, terminal a is higher than the potential of terminal o, so the potential of terminal b is higher than that of terminal a. At this time, the inductance L reversely charges the plasma load to neutralize the accumulated charge on the surface of the target; when the switch tube V is turned off again, an internal circulation occurs in the inductor L, which makes the inductor current quickly balanced. Inductor L has the dual functions of inductance and transformer, and completes energy storage and energy transfer successively. Adjusting the position of the terminal a of the center tap of the inductor L can adjust the reverse charging voltage.

The PWM control circuit is composed of ARM microcontroller and peripheral protection circuit. Its functions: acquisition and calculation of current and voltage signals; generation of pulse width modulation signals; protection of abnormal arc discharge; generation of constant current, constant voltage and constant power characteristics, generation of pulse signals and adjustment of frequency.

In the present invention, the pulse sputtering power supply voltage sampling circuit and current sampling circuit are shown in Figures 4-5, and an overcurrent and short circuit protection circuit is added, as shown in Figure 6.

See Figure 4 for a schematic diagram of the voltage sampling circuit. After the sampling voltage is divided by resistors R11 and R22, it enters the low-pass filter composed of inductor L11 and capacitor C11 to filter out high-frequency interference components, and then sends it to the proportional amplification circuit composed of operational amplifier OA1, resistors R13 and R14 for impedance After conversion, it is sent to the optocoupler OI for photoelectric isolation, and then sent to the operational amplifier OA2 for impedance transformation. Finally, the sampling voltage is sent to the analog-to-digital conversion part of the ARM, and sent to the overcurrent and short circuit protection circuit all the way. The operational amplifier can be optional OP07, OP27, UA741 integrated chip; the optocoupler is a linear optocoupler, optional PC817A-C integrated chip.

Refer to the schematic diagram of the current sampling circuit shown in Fig. 5 . The Hall current sensor LEM.A outputs the sampling current value according to a certain ratio, and then sends it to the low-pass filter composed of L1 and C1 to filter out high-frequency interference components, and then sends it to the voltage follower composed of the operational amplifier OA for impedance transformation , and finally the sampling current is sent all the way to the analog-to-digital conversion part of the ARM, and all the way to the overcurrent and short circuit protection circuit. The model of the Hall current sensor is preferably a LEM45 integrated module.

Refer to the schematic diagram of the overcurrent and short circuit protection circuit shown in Fig. 6 . Resistors R21, R22 and R25 and voltage comparator CP1 form a current comparison circuit, resistors R23, R24 and R26 and voltage comparator CP2 form a voltage comparison circuit, timer integrated circuit is NE555, together with R27, C22 and C21 form a monostable circuit Among them, pin 2 is the trigger terminal, and pin 3 is the output terminal.

During the coating process, the gas discharge changes from glow discharge to arc discharge, the current will rise rapidly, and the voltage will drop rapidly, which is not allowed by the coating process. The invention adopts a double comparator circuit to realize overcurrent and short circuit protection. The comparison circuit is preferably an LM339 chip.

When the current sampling value exceeds the set value (set by the voltage divider value of R21 and R22), the voltage comparator CP1 outputs a low level, and the NAND gate NAND outputs a high level; when the voltage sampling value is lower than the set value (set by R23 and R24 voltage divider setting) will also make the NAND gate NAND output high level. If the monostable circuit is triggered, a high-level single-pulse signal is output, one way is sent to the photoelectric isolation, and the PWM control signal transmission is stopped; one way is sent to the ARM interrupt port, and the ARM executes the interrupt program to stop the output of the PWM control signal. It realizes double protection, achieves the purpose of rapidly suppressing arc discharge, and protects power supply and target.

The utility model particularly emphasizes that the above-mentioned pulse generating circuit, voltage sampling circuit, current sampling circuit overcurrent and its short-circuit protection circuit are classic circuits designed by the inventor after years of research and development and creative labor, especially the pulse generating circuit. Obtained by the inventor's creative efforts, the design of the above circuit better ensures the reliability of the pulse sputtering power supply, good dynamic characteristics, low cost, simple and reliable control, and has the advantages of energy feedback.

In addition, the utility model also discloses a pulse sputtering power supply control method, which includes a main module, a human-computer interaction sub-module, a fault judgment sub-module, and a closed-loop control sub-module; the closed-loop control sub-module further includes an expert control sub-module module; wherein, the main module mainly completes the soft start, the acquisition of external data, the expert control sub-module of the closed-loop system regulator, the formation of the pulse generation circuit, overvoltage, overcurrent, short circuit protection and other work. The main module mainly includes a fault judgment sub-module, an interrupt detection sub-module, and a calculation sub-module.

Wherein said failure judging sub-module judges whether the power supply works normally, if there is a fault, then carry out fault handling, carry out analog-to-digital conversion and algorithm to judge the value of input and output by the A/D function of ARM embedded operating system; The module adjusts the output voltage and current of the power supply.

In addition, the closed-loop control sub-module may include a PID control sub-module or a fuzzy control sub-module.

7 is an embodiment of a voltage sampling subroutine flow chart. In the initialization process, first reset each input port of ARM, after initialization, start the interrupt program, if there is an interrupt request, it will respond, otherwise, data acquisition and reference value will be read, and then the data will be processed, and the output will be controlled accordingly. , overvoltage, short circuit or overcurrent occurs, then carry out troubleshooting.

In the above description, many specific details are set forth in order to fully understand the utility model. However, the above descriptions are only preferred embodiments of the present invention, and the present invention can be implemented in many other ways different from those described here, so the present invention is not limited by the specific implementations disclosed above. At the same time, any person skilled in the art can use the methods and technical content disclosed above to make many possible changes and modifications to the technical solution of the utility model without departing from the scope of the technical solution of the present invention, or modify it to be equivalent to the equivalent change. Example. All the content that does not deviate from the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present utility model still belong to the protection scope of the technical solution of the utility model.

Claims (9)

1. a pulsed sputter power supply, comprises the rectified three-phase circuit, inverter circuit, high frequency transformer, current rectifying and wave filtering circuit, the pulse generating circuit that are linked in sequence; It is characterized in that: the structure of described pulse generating circuit is: comprise switching tube V output and be connected to inductance L tap a and hold; Inductance L tap o end is connected to DC power supply circuit negative pole, and inductance L tap b end is connected with magnetic control sputtering device target, and switching tube V input and magnetic control sputtering device substrate are connected in DC power supply circuit positive pole jointly; The control end of described switching tube V is connected with pwm control circuit.

2. pulsed sputter power supply according to claim 1, is characterized by: also comprise central processing unit, drive circuit, signal acquisition module, protection module, host computer, LCD MODULE, signal input module; Described central processing unit is ARM system; Described signal acquisition module comprises voltage sampling circuit, current sampling circuit; Described protection module comprises overcurrent and short-circuit protection circuit.

3. pulsed sputter power supply according to claim 1, is characterized by: the input of described rectified three-phase circuit is connected with air switch output; The input of described air switch connects can recover protective tube fast.

4. pulsed sputter power supply according to claim 2, is characterized by: described drive circuit comprises the driving of driving to inverter circuit and paired pulses circuit for generating; The drive singal of described drive circuit is produced by ARM system and generates after photoelectric isolating circuit process.

5. pulsed sputter power supply according to claim 2, is characterized by: described current sampling circuit comprises the output current sample circuit of output current to described current rectifying and wave filtering circuit and paired pulses circuit for generating.

6. pulsed sputter power supply according to claim 5, is characterized by: described current sampling circuit comprises current sensor, and described current sensor adopts Hall current sensor.

7. pulsed sputter power supply according to claim 2, is characterized by: described voltage sampling circuit comprises the output voltage sampling circuit of output voltage to described current rectifying and wave filtering circuit and paired pulses circuit for generating.

8. pulsed sputter power supply according to claim 2, is characterized by: described voltage sampling circuit, current sampling circuit are transferred to ARM system after A/D sample circuit.

9. pulsed sputter power supply according to claim 2, is characterized by: the Signal transmissions between described host computer and ARM system is 4G Internet Transmission.