High efficiency low cost bipolar high power pulsed magnetron sputtering power supply with a kick pulse

Abstract

This invention relates to a high-efficiency, low-cost bipolar high-power pulsed magnetron sputtering power supply with excitation pulse, belonging to the field of vacuum magnetron sputtering ion plating technology. It includes a high-voltage negative sputtering power supply, a low-voltage positive bias power supply, a pulsed excitation power supply, an energy clamping network, and a pulsed excitation network. The energy clamping network is connected between the inverter bridge and the output terminal to absorb and clamp the reverse electromotive force when the switching devices are turned off, limiting the voltage across each switching device in the inverter bridge to near the DC power supply voltage, thus reducing the device withstand voltage requirements and cost. The pulsed excitation network is connected in series between the output terminal and the load to superimpose an excitation pulse at the beginning of the negative sputtering pulse to excite plasma discharge, improving the target ionization rate and suppressing arcing. This invention reduces device cost and power redundancy, improves power supply efficiency and discharge stability, and enhances ion diffraction by applying a positive voltage through the low-voltage positive bias power supply to neutralize the target surface charge, thereby improving the coating quality.

Description

Technical Field

[0001] This invention relates to a power supply device used in the field of vacuum magnetron sputtering ion plating technology, and more particularly to a high-efficiency, low-cost bipolar high-power pulsed magnetron sputtering power supply with excitation pulse and its application. Background Technology

[0002] Vacuum magnetron sputtering ion plating (DCMS) technology uses a magnetron sputtering target (target material) as the cathode. In a vacuum environment, glow discharge between the target and the anode shell excites gas electrons to generate ions and new electrons. Under the action of an electric field, the gas ions collide with the target material, causing the target material to sputter and generate secondary electrons. Under the combined action of electric and magnetic fields, the secondary electrons ionize more gas atoms to bombard the target surface, thus forming a high deposition rate. Under the action of substrate bias voltage, depending on the medium gas, metals, metal compounds, etc. are deposited on the workpiece to form a high-temperature resistant and corrosion-resistant decorative coating of a specific color; or an ultra-hard self-lubricating coating formed by metals, metal alloys, silicon and metal alloy nitrides, carbides, etc., for use in wear-resistant environments such as cutting tools, drills, molds, turbine blades, and oil-free lubrication; or for optical coatings such as mirror making and the LOW-E glass industry. High-power pulsed magnetron sputtering (HiPIMS) is a novel magnetron sputtering deposition method developed at the beginning of this century. Because it operates under high voltage (approximately 500-1300V depending on the target material, vacuum intensity, and target characteristics) and high current (current density approximately 0.5-3 A / cm², while the highest discharge density in DC magnetron sputtering is generally 0.04 A / cm²), its discharge characteristics fall between glow discharge and arc discharge. Within an extremely short pulse time (typically tens to hundreds of microseconds), extremely high power (peak power reaching 100-1000 times that of DC magnetron sputtering) is applied. This discharge mode generates ultra-dense plasma (density exceeding 10¹³ cm⁻³), thereby highly ionizing the sputtered target atoms (ionization rate reaching 70%-90% or even higher). This extremely high ionization rate brings revolutionary advantages, enabling atomic-scale densification, eliminating columnar crystal structures, and obtaining thin films without pores or resembling bulk materials. Significantly improving film hardness, corrosion resistance, and adhesion, HiPIMS technology can diffract ions to the sides and bottom of complex workpieces, trenches, or holes by applying appropriate bias voltage or utilizing the characteristics of plasma itself, achieving true conformal coating and solving the "shadowing effect" problem of traditional sputtering. High ionization rate means that more substances exist in ionic form, and ions are easily deflected or absorbed during their movement towards the substrate. At the same time, the rapid heating and cooling of the target surface by high-power pulses also suppresses the formation of molten pools and droplet ejection. Therefore, the surface of the film deposited by HiPIMS is exceptionally smooth. In recent years, a bipolar high-power pulsed power supply has been developed. After each negative sputtering pulse, it applies a positive voltage of about 300V to the magnetron sputtering cathode to neutralize the accumulated charge on the target, maintain stable discharge, and further increase ion diffraction capability, improving the film adhesion of complex surface workpieces. This has enabled the application of HiPIMS technology to expand into various fields such as civilian medical, industrial, and aerospace applications.

[0003] High-power pulsed magnetron sputtering power supplies typically output an open-circuit voltage ranging from 1300V to 2000V, with a load voltage range of approximately 400V to 1000V. Traditional unipolar high-power pulsed power supplies (application number 202311651507.9) have a structure with... Figure 3 As shown, the circuit operates as follows: the main power supply P1 charges C1 through a current-limiting inductor, and the negative power supply P2 charges C2 through a current-limiting inductor L2. When a high-power pulse signal triggers Q1 to conduct, the positive terminal of C1 is connected to the anode of diode D1, effectively in parallel with diode D1. Since the positive terminals of C1 and C2 are both connected to the anodes of diodes D1 and D2, the diodes are reverse-biased and turned off. The energy stored in C1 and C2 is quickly released to the load RL1. Because C1 and C2 are effectively connected in series during the conduction of Q1, the voltage across the load is the sum of the voltage across C1 and the voltage across C2. The sum of these factors rapidly excites the generation of magnetron sputtering target plasma. However, since the capacity of C2 is much smaller than that of C1, the voltage across C2 quickly approaches zero. The subsequent energy of the pulse cycle is maintained by the discharge of the main power supply P1, inductor L1, capacitor C1, until Q1 is turned off and one pulse cycle ends. It is evident that this power supply cannot output bipolar pulse voltage. Another problem is that the discharge time of C2 is uncontrollable. If the capacity is too small, the excitation energy is insufficient. If the capacity is too large, excessive energy storage can easily cause arc discharge after plasma generation, terminating magnetron sputtering and causing target material particle contamination of the film layer due to arc discharge.

[0004] Existing bipolar high-power pulsed magnetron sputtering power supplies have a structure with attached Figure 1 , attached Figure 1The circuit operates as follows: During negative sputtering high-voltage output, the high-voltage negative sputtering power supply PH is turned on via QC and QB, releasing high-power pulse energy to the load LOAD. During positive low-voltage output, the low-voltage positive bias power supply PL is turned on via QC and QD, applying a positive voltage of approximately 300V to the load LOAD to neutralize the accumulated charge during the negative phase and to propel the plasma particles, improving the ion diffraction capability. Because the high-voltage negative sputtering power supply PH voltage is close to 2000V, QC and QB will withstand a turn-off voltage of over 2000V. Therefore, the selected devices must be IGBTs or silicon carbide MOS with a withstand voltage of over 2200V. Due to the actual physical device... The fact that components QA and QB are in one semiconductor module and QC and QD are in another semiconductor module poses a challenge to cost. In addition, since the high-voltage negative sputtering power supply PH requires a voltage of over 1500V to generate the high-density current HiPIMS discharge mode, and once it enters the discharge state, the steady-state load voltage will drop to around 400V-1000V, making the high-voltage negative sputtering power supply PH very inefficient. The power reserve needs to be about 1.5 times greater than the actual output power. Furthermore, this circuit cannot generate the excitation pulse that generates a steep pulse current. The dome-shaped current waveform makes it very easy for the discharge to enter the arc state, which damages the working conditions and is not conducive to improving the high ionization rate of the target material. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention discloses a high-efficiency, low-cost bipolar high-power pulsed magnetron sputtering power supply with excitation pulse, the technical solution of which is as follows: A high-efficiency, low-cost bipolar high-power pulsed magnetron sputtering power supply with excitation pulse, characterized in that it comprises: At least three DC power supplies; An inverter bridge circuit is used to convert direct current into bipolar pulse output; One output terminal is used to connect to the magnetron sputtering target load; An energy clamping network, connected between the inverter bridge and the output, is used to absorb and clamp the back electromotive force generated by the load and output cable when the switching devices are turned off, so that the voltage across each switching device in the inverter bridge is limited to a predetermined range of the DC power supply voltage; and A pulse excitation network, connected in series between the output terminal and the load, is used to superimpose an excitation pulse at the beginning of the negative sputtering pulse to rapidly excite plasma discharge. A first voltage isolation network is used to isolate high-voltage and low-voltage potentials and to provide a path for the reverse electromotive force generated by the high-voltage pulse turn-off, ensuring that it is absorbed by the energy storage elements of the main circuit, thereby guaranteeing the safety of the inverter bridge devices. A second voltage isolation network is used to isolate the effect of the reverse electromotive force generated by the high voltage shutdown on the low voltage, so as to ensure that the forward low voltage forward bias power supply voltage will not deviate from the set value due to the influence of the high voltage circuit.

[0006] Preferably, the inverter bridge is an H-bridge structure composed of first, second, third, and fourth switching devices, wherein the first and second switching devices are connected in series to form a first half-bridge, and the third and fourth switching devices are connected in series to form a second half-bridge; the first half-bridge is connected in parallel to the two ends of a low-voltage positive bias power supply, and the second half-bridge is connected in parallel to the two ends of a high-voltage negative sputtering power supply.

[0007] Preferably, the energy clamping network includes: The energy clamping network includes: A first diode is connected between the midpoint of the first half-bridge and the positive terminal of the low-voltage forward bias power supply. A second diode is connected between the midpoint of the first half-bridge and the midpoint of the second half-bridge; A first capacitor is connected in parallel across the low-voltage forward bias power supply. A second capacitor is connected in parallel across the two ends of the high-voltage negative sputtering power supply; A third capacitor is also connected in parallel across the high-voltage negative sputtering power supply.

[0008] Preferably, the pulse excitation network comprises: One excitation pulse power supply; A fifth switching device and a sixth switching device are connected to the excitation pulse power supply and are used to control the application of the excitation pulse; A fourth capacitor is connected in parallel across the excitation pulse power supply to stabilize its voltage; A fifth diode and a sixth diode are connected in antiparallel between the collector and emitter of the fifth and sixth switching devices, respectively, to form a clamping path, which is used to limit the voltage across the fifth and sixth switching devices and to provide a current path for the high-voltage negative sputtering power supply after the excitation pulse ends.

[0009] Preferably, the pulse excitation network is connected in series between the second terminal of the output terminal and the load, and works in conjunction with the inverter bridge circuit, so that in the initial stage of the negative sputtering pulse, the excitation pulse power supply and the high-voltage negative sputtering power supply are output in series and superimposed; after the excitation is completed, the excitation pulse power supply is bypassed by the parallel device in the pulse excitation network, and only the high-voltage negative sputtering power supply is maintained to discharge through the inverter bridge circuit.

[0010] Preferably, the DC power supply includes a high-voltage negative sputtering power supply and a low-voltage positive bias power supply, which are used to provide negative sputtering high-voltage pulses and positive charge neutralization pulses, respectively.

[0011] Preferably, the output voltage of the high-voltage negative sputtering power supply is set to be only slightly higher than the actual voltage required by the load, so as to improve the power supply operating efficiency.

[0012] Preferably, the withstand voltage requirements of each switching device in the inverter bridge and each switching device in the pulse excitation network are slightly higher than the voltage of the DC power supply, thereby allowing the use of low-voltage, low-cost commercial switching devices.

[0013] This invention also discloses an output method for a high-efficiency, low-cost bipolar high-power pulsed magnetron sputtering power supply with excitation pulse as described above, characterized by comprising the following steps: a. In the initial stage of the negative sputtering pulse, the corresponding switching devices in the inverter bridge circuit and the switching devices in the pulse excitation network are simultaneously turned on, so that the excitation pulse power supply and the high-voltage negative sputtering power supply are connected in series and superimposed to output a high-amplitude excitation pulse to the load; b. After excitation is completed, the switching devices in the pulse excitation network are turned off, and only the high-voltage negative sputtering power supply maintains negative sputtering discharge to the load through the inverter bridge and the excitation circuit bypass device; c. After the negative sputtering pulse ends, another set of switching devices in the inverter bridge is turned on to apply a positive bias voltage to the load to neutralize the target surface charge; d. During the turn-off period of the switching devices, the reverse electromotive force is absorbed and clamped by the energy clamping network to ensure that the voltage across each switching device does not exceed the DC power supply voltage.

[0014] The present invention also discloses a magnetron sputtering coating apparatus, characterized in that it includes a high-efficiency, low-cost bipolar high-power pulsed magnetron sputtering power supply with excitation pulse as described above. Beneficial effects

[0015] This invention effectively solves the problems of high device withstand voltage, high cost, low efficiency, and insufficient ionization rate in existing technologies by employing a unique circuit topology. Specifically, an energy clamping network (including diode D1 {a second voltage isolation network used to isolate the influence of the reverse electromotive force generated by high voltage turn-off on the low voltage,}, D2 {a first voltage isolation network used to isolate the high voltage and low voltage potentials and provide a path for the reverse electromotive force generated by the high voltage pulse turn-off,} and capacitor C2) is set between the inverter bridge and the output terminal. When the switching devices are turned off, this network can absorb and clamp the reverse electromotive force generated by the load and output cable, so that the voltage of each switching device (QA, QB, QC, QD) in the inverter bridge is limited to the voltage range of the high voltage negative sputtering power supply PH (approximately 1000V), without having to withstand high voltage stress of more than 2000V; at the same time, due to the clamping structure, the voltage across the switching devices (QE, QF) in the pulse excitation network does not exceed the voltage of the excitation pulse power supply PN (approximately 600V). This design allows all semiconductor devices to use low-cost, readily available commercial devices (such as 1200V / 1700V IGBTs or SiCMOS), avoiding the use of high-voltage IGBTs or silicon carbide MOS with a withstand voltage of 2200V or higher, thereby significantly reducing device costs (by more than 50%) and improving the stability of the supply chain and the overall reliability of the power supply.

[0016] On the other hand, this invention connects the pulse excitation network in series between the output and the load. In the initial stage of the negative sputtering pulse, by simultaneously turning on the corresponding switching devices, the excitation pulse power supply PN and the high-voltage negative sputtering power supply PH are superimposed in series, forming a steep, high-amplitude excitation voltage. This rapidly breaks down the gas to generate dense plasma, thereby achieving an extremely high target ionization rate (up to 90% or more), significantly better than the 50%~70% of existing technologies. The steep current waveform also effectively suppresses arc discharge, improves discharge stability, and reduces target damage. After excitation, the excitation pulse power supply is bypassed, and only the high-voltage negative sputtering power supply PH maintains the discharge. The output voltage of the high-voltage negative sputtering power supply PH is set to be only slightly higher than the actual load voltage (400V~1000V), eliminating the need for an open-circuit high voltage of over 1500V. Therefore, the power efficiency is significantly improved to over 90%, and there is no need to reserve more than 1.5 times the power redundancy. The power supply volume and weight are reduced by more than 30%, further reducing manufacturing costs.

[0017] Furthermore, this invention applies a positive voltage to the load after the negative pulse ends by using a low-voltage positive bias power supply PL, neutralizing the accumulated charge on the target surface and driving charged particles in the plasma. This significantly enhances the diffraction capability of ions towards complex workpieces (such as grooves, sidewalls, and blind holes), improving the uniformity of the film layer on the surface of complex-shaped workpieces by more than 30%, and significantly strengthening the film-substrate adhesion. This broadens the application range of HiPIMS technology in precision molds, cutting tools, medical devices, and other fields. The entire circuit topology is simple, with a small number of components. All switching devices operate within a safe voltage range, reducing the device failure rate by more than 80% and significantly extending the power supply's mean time between failures (MTBF). Attached Figure Description

[0018] Figure 1 The diagram shows the topology (a) and voltage and current waveforms (b) of a typical bipolar high-power pulse power supply in the prior art. Figure 2 The diagram shows the topology (a) and voltage and current waveform diagram (b) of a high-efficiency, low-cost bipolar high-power pulsed magnetron sputtering power supply with excitation pulse according to the present invention. Figure 3 The diagram shows the topology of a unipolar high-power pulse power supply (a) and the voltage and current waveforms (b) in the prior art. Detailed Implementation Example 1

[0019] A high-efficiency, low-cost bipolar high-power pulsed magnetron sputtering power supply with excitation pulses includes: at least three DC power supplies; an inverter bridge for converting DC power into a bipolar pulsed output; an output terminal for connecting to a magnetron sputtering target load; and an energy clamping network connected between the inverter bridge and the output terminal for absorbing and clamping the back electromotive force generated by the load and output cable when the switching devices are turned off, thereby limiting the voltage across each switching device in the inverter bridge to a predetermined range of the DC power supply voltage; and A pulse excitation network, connected in series between the output terminal and the load, is used to superimpose an excitation pulse at the beginning of the negative sputtering pulse to rapidly excite plasma discharge.

[0020] like Figure 2 As shown, the inverter bridge circuit consists of a first switching device QA, a second switching device QB, a third switching device QC, and a fourth switching device QD, forming an H-bridge structure. QA and QB form the first half-bridge (low-voltage half-bridge), and QC and QD form the second half-bridge (high-voltage half-bridge). The first half-bridge is connected in parallel to the low-voltage positive bias power supply PL, and the second half-bridge is connected in parallel to the high-voltage negative sputtering power supply PH.

[0021] The energy clamping network includes: a first diode D1, connected between the positive terminal of the low-voltage forward bias power supply PL and the midpoint of the first half-bridge, used to isolate the charging of PL by the reverse electromotive force; a second diode D2, connected between the midpoint of the first half-bridge and the midpoint of the second half-bridge, used to isolate the potential between the high-voltage side and the low-voltage side; a first capacitor C1, connected in parallel across the low-voltage forward bias power supply PL, used for filtering; a second capacitor C2, connected in parallel across the high-voltage negative sputtering power supply PH, used to absorb the reverse electromotive force generated when the switching device is turned off, ensuring the safety of the switching device; and a third capacitor C3, also connected in parallel across PH, used for filtering.

[0022] The pulse excitation network includes: an excitation pulse power supply PN; a fifth switching device QE and a sixth switching device QF, connected to PN, used to control the application of the excitation pulse; a fourth capacitor C4, connected in parallel across PN, used to stabilize its voltage; and a fifth diode DE and a sixth diode DF, connected in anti-parallel between the collector and emitter of QE and QF respectively, forming a clamping path to limit the voltage across QE and QF and provide a current path for PH after the excitation pulse ends. The pulse excitation network is connected in series between the second terminal B of the output and the load LOAD, and works in conjunction with the inverter bridge circuit. This allows the excitation pulse power supply PN and the high-voltage negative sputtering power supply PH to be superimposed in series during the initial stage of the negative sputtering pulse. After excitation is complete, the excitation pulse power supply PN is bypassed by the sixth diode DF, and only the high-voltage negative sputtering power supply PH is maintained by discharge through the inverter bridge circuit.

[0023] The DC power supply includes a high-voltage negative sputtering power supply and a low-voltage positive bias power supply, used to provide negative sputtering high-voltage pulses and positive charge neutralization pulses, respectively. The output voltage of the high-voltage negative sputtering power supply is set to be only slightly higher than the actual voltage required by the load to improve power supply operating efficiency. The withstand voltage requirements of each switching device in the inverter bridge and each switching device in the pulse excitation network are slightly higher than the voltage of the DC power supply, thereby allowing the use of low-voltage, low-cost commercial switching devices.

[0024] The first voltage isolation network is a diode D2, with its anode connected to the positive power supply terminal of the first half-bridge composed of QA and QB, and its cathode connected to the positive high-voltage power supply terminal of the second half-bridge composed of QC and QD. It is used to isolate high voltage and low voltage potentials and provide a path for the reverse electromotive force generated by the high voltage pulse turn-off, ensuring that it is absorbed by the main circuit energy storage element C2 to ensure the safety of the inverter bridge device.

[0025] The second voltage isolation network is a diode D1, with its cathode connected to the positive terminal of the low-voltage forward bias power supply PL and its anode connected to the positive voltage input terminal of the first half-bridge composed of QA and QB. It is used to block the influence of the reverse electromotive force generated by the high voltage shutdown on the low voltage, so as to ensure that the forward low-voltage forward bias power supply PL voltage will not deviate from the set value due to the operating state of the high voltage circuit.

[0026] The specific circuit structure and its working process are as follows: A high-efficiency, low-cost bipolar high-power pulsed magnetron sputtering power supply with excitation pulse, wherein: QA, QB, QC, and QD form a basic bridge inverter circuit; D1 is used to isolate the positive A and negative B reverse electromotive force generated by the load LOAD and output cable when QC and QB are turned off, which charges the low-voltage forward bias power supply PL, keeping the low-voltage forward bias power supply PL stable; D2 is used to isolate the potentials of the high-voltage side half-bridge QC and QD of the high-voltage negative sputtering power supply PH from the low-voltage side half-bridge, and clamps the positive A and negative B reverse electromotive force generated by the load LOAD and output cable when QC and QB are turned off through C2, ensuring that the voltage across the QA and QB half-bridges is not significantly higher than that at the PH terminal of the high-voltage negative sputtering power supply, that is, basically equivalent to... The QC and QD half-bridge operating voltages operate as follows: QE, QF, DE, DF, C4, and the excitation pulse power supply PN form the excitation pulse circuit. In the static state, QE and QF are off. When a narrow excitation pulse is applied to the a'' trigger terminal, QE conducts, and the excitation pulse power supply PN is connected in parallel to the diode DF. Simultaneously, the high-voltage negative sputtering power supply PH, with the same phase, conducts through QC and QB, connecting the excitation pulse power supply PN connected in parallel to the diode DF in series to release high-power pulse energy to the load LOAD. Once excitation is complete, QE is off, and the high-voltage negative sputtering power supply PH continues to transfer energy to the load through QC, DF, the load LOAD, and QB until one pulse cycle ends. At this point, QB, QE, QF, and QD are off, and the A and B... The B-positive and A-negative phases will reverse due to the reverse electromotive force, becoming A-positive and B-negative. The reverse electromotive force charges C2 according to DD, DF, LOAD, DA, and D2. Since the parallel capacity of C2 and C3 is much larger than that of C4, and the conduction time of QE is shorter than that of QB and QC, whether the high-voltage negative sputtering power supply PH superimposes and excites the pulse power supply PN to discharge, or the high-voltage negative sputtering power supply PH outputs discharge alone, QA, QB, QC, and QD will not significantly exceed the voltage across C2, that is, they will not significantly exceed the voltage of the high-voltage negative sputtering power supply PH. Due to the clamping structure of QE, DE, QF, and DF, the voltage across QE and QF will not significantly exceed the voltage across C4. When the low-voltage positive bias power supply is output, QA, QF, and QD are synchronously triggered to conduct, and the low-voltage positive bias power supply... A positive voltage of approximately 300V is applied to the bias power supply PL via load LOAD, QF, and QD to neutralize the accumulated charge during the negative phase and to propel the charged particles of the plasma, improving their diffraction ability. Due to the presence of DE, the conduction of QF will not discharge C3, thus providing a positive voltage across the load LOAD that is essentially equivalent to that of the low-voltage positive bias power supply PL. This invention uses QE, DE, QF, DF, and C4 to form a pulse excitation output, which is connected in series with the load LOAD and then connected to the output terminals A and B of the H inverter bridge composed of QA, QB, QC, and QD (similarly, it can also be connected to the output terminals B and A of the H inverter bridge composed of QA, QB, QC, and QD) to achieve the following objectives: 1.The high-voltage no-load output requirement of approximately 2000V and the actual load voltage difference within 1000V are no longer independently supplied by the high-voltage negative sputtering power supply PH. The output no-load voltage can be significantly reduced to slightly higher than the load voltage, greatly improving the power supply's operating efficiency and eliminating the need for redundant design. 2. All semiconductor devices in the power supply can be assembled using readily available, low-cost components, improving operational reliability. 3. The significant reduction in the high-voltage negative sputtering power supply PH also lowers the power supply's internal resistance, improving dynamic response. Combined with the excitation pulse power supply's PN discharge, the discharge process quickly enters a high-power state, increasing the sputtering target ionization rate and effectively suppressing arc formation. Example 2

[0027] The output method of the high-efficiency, low-cost bipolar high-power pulsed magnetron sputtering power supply with excitation pulse described in Example 1 includes the following steps: a. In the initial stage of the negative sputtering pulse, the corresponding switching devices in the inverter bridge circuit and the switching devices in the pulse excitation network are simultaneously turned on, so that the excitation pulse power supply and the high-voltage negative sputtering power supply are connected in series and superimposed to output a high-amplitude excitation pulse to the load; b. After excitation is completed, the switching devices in the pulse excitation network are turned off, and only the high-voltage negative sputtering power supply maintains negative sputtering discharge to the load through the inverter bridge; c. After the negative sputtering pulse ends, another set of switching devices in the inverter bridge is turned on to apply a positive bias voltage to the load to neutralize the target surface charge; d. During the turn-off period of the switching devices, the reverse electromotive force is absorbed and clamped by the energy clamping network, so that the voltage across each switching device does not significantly exceed the DC power supply voltage.

[0028] e. During the static and dynamic phases of the entire circuit, the first voltage isolation network is used to isolate high and low voltage potentials and to provide a path for the reverse electromotive force generated by the high voltage pulse turn-off, ensuring that it is absorbed by the main circuit energy storage element to guarantee the safety of the inverter bridge device.

[0029] f. During the static and dynamic periods of the entire circuit, the second voltage isolation network is used to isolate the effect of the reverse electromotive force generated by the high voltage shutdown on the low voltage, so as to ensure that the forward low voltage forward bias power supply voltage is not affected by the high voltage circuit and deviates from the set value.

[0030] The following circuit Figure 2 A detailed explanation of the specific implementation process and working principle of the output method (ad): Step a: Synchronous superposition of excitation pulses in the initial stage of negative sputtering pulses. In the initial stage of the negative sputtering pulse (usually a few microseconds to tens of microseconds), the control circuit applies a narrow pulse trigger signal to the a'' trigger terminal, and simultaneously applies a conduction signal to the gates of QC and QB. At this time, QE is turned on, and the excitation pulse power supply PN is connected in parallel across diode DF; at the same time, QC and QB are turned on, and the positive terminal of the high-voltage negative sputtering power supply PH returns to the negative terminal of PH through QC, the load LOAD, and QB to form the main circuit. Since the excitation pulse power supply PN is connected in parallel across DF, and DF is cut off due to reverse voltage caused by the conduction of QE, the excitation pulse power supply PN and the high-voltage negative sputtering power supply PH form a series relationship, jointly applying voltage to the load LOAD. At this time, the voltage across the load is the sum of the high-voltage negative sputtering power supply PH voltage and the excitation pulse power supply PN voltage (for example, if the high-voltage negative sputtering power supply PH outputs 1000V and the excitation pulse power supply PN outputs 500V, then the load will withstand 1500V). This superimposed high voltage quickly breaks down the gas on the target surface, generating dense plasma and forming a steep pulse current rising edge, thus achieving rapid excitation.

[0031] Step b: Maintain negative sputtering discharge after excitation is complete. After the excitation pulse ends (typically lasting several microseconds to tens of microseconds), the control circuit shuts off the trigger signal of QE, causing QE to be cut off. At this time, the excitation pulse power supply PN is disconnected from the main circuit, but QC and QB remain conducting. The high-voltage negative sputtering power supply PH continues to supply energy to the load through QC, diode DF (because QC is conducting, the positive terminal of DF is at a high potential, and the negative terminal is at a low potential, so DF is forward conducting), load LOAD, and QB, maintaining negative sputtering discharge. At this time, the voltage across the load drops to the voltage value of the high-voltage negative sputtering power supply PH (e.g., 800V), and the current is supplied solely by the high-voltage negative sputtering power supply PH. The discharge enters the steady-state sputtering stage until the preset negative pulse width ends.

[0032] Step c: Apply a positive bias voltage after the negative pulse ends. After the negative sputtering pulse ends, the control circuit first turns off QC and QB. Then, after a set dead time (typically tens of microseconds), a turn-on signal is simultaneously applied to the gates of QA, QF, and QD. The positive terminal of the low-voltage positive bias power supply PL flows through QA, the load LOAD (current flows from A to B, opposite to the negative pulse), QF, and QD back to the negative terminal of PL, forming a loop. A positive voltage of approximately 300V is applied to the load LOAD. Due to the presence of diode DE (its cathode is connected to the collector of QF, and its anode to the positive terminal of C4), DE is cut off when QF is on, preventing C4 from discharging to the load and ensuring that the voltage across the load is approximately equal to the output voltage of the low-voltage positive bias power supply PL. This positive voltage is used to neutralize the positive charge accumulated on the target surface during negative sputtering and to propel charged particles in the plasma, enhancing the diffraction ability of ions towards the workpiece sidewalls, grooves, and other areas.

[0033] Step d: Clamping back electromotive force during switch turn-off At the end of each pulse cycle and after all switching devices are turned off (e.g., when QC and QB are turned off at the end of a negative pulse, or when QA, QF, and QD are turned off at the end of a positive pulse), taking the turn-off of QC and QB at the end of a negative pulse as an example, due to the distributed inductance and residual energy in the load LOAD and output cable, a reverse electromotive force will be generated between the output terminals A and B (the polarity is A positive and B negative, which is opposite to A negative and B positive when the device is turned on during a negative pulse). The current path of the reverse electromotive force is: C2 negative terminal → DD cathode → DD anode → DF cathode → DF anode → load LOAD → DA cathode → DA anode → D2 cathode → D2 anode → C2 positive terminal, completing the entire charging process of C2. Because the anode of diode DE is connected to the positive terminal of the excitation power supply PN, and the cathode of DE is connected to the anode of diode DF, DE is in reverse cutoff, isolating the discharge path of C4. The excitation power supply PN does not participate in the entire discharge process of the reverse electromotive force. Furthermore, since the energy of the reverse electromotive force is only stored in the load LOAD and the connecting cable, and LOAD has basically time-domain capacitance characteristics, the capacity of the absorption capacitor C2 is large enough that the total stored energy is insufficient to significantly increase the voltage across C2. Thus, the voltage across A and B is clamped to the voltage across C2, which is near the voltage value of the high-voltage negative sputtering power supply PH. Taking the turn-off of QA and QD at the end of the positive pulse as an example, due to the accumulated charge in the load LOAD during the positive pulse and the distributed inductance in the output cable, a reverse electromotive force (EMF) will be generated between the output terminals A and B (polarity A negative B positive, opposite to A positive B negative when turned on during the positive pulse). The current path of this reverse EMF is: C2 negative terminal → DB cathode → DB anode → load LOAD → DE cathode → DE anode → C4 positive terminal → C4 negative terminal → DC cathode → DC anode → C2 positive terminal, completing the entire charging process of C2. The voltage across the excitation pulse power supply C4 is exactly opposite in polarity to the reverse electromotive force (EMF) of the circuit, thus largely canceling out a portion of the reverse EMF. Furthermore, since the low-voltage bias power supply PL is only around 300V and the charge energy accumulated on the load LOAD is limited, the total reverse EMF energy during this period is far less than the cycle during which the negative pulse ends and turns off QC and QB. C2 can quickly absorb the energy of the reverse EMF and clamp the voltage across A and B to near the voltage across C2, i.e., the voltage of the high-voltage negative sputtering power supply PH. These two processes ensure that the voltage across QA, QB, QC, and QD during the turn-off period does not significantly exceed the voltage of the high-voltage negative sputtering power supply PH. Simultaneously, due to the clamping effect of D3 and D4, the voltage across QE and QF does not exceed the voltage across C4, i.e., the voltage of the excitation pulse power supply PN. This ensures that all switching devices operate within a safe voltage range, avoiding the risk of high-voltage breakdown.

[0034] The above four steps are repeated sequentially to realize the complete working process of a high-efficiency, low-cost bipolar high-power pulsed magnetron sputtering power supply with excitation pulse.

[0035] This invention, through its unique topology combining an energy clamping network and a pulse excitation network, completely solves key technical challenges in existing technologies, such as high voltage withstand capability of switching devices, high cost, low power efficiency, non-steep discharge waveforms, and insufficient ionization rate. This technical solution not only clamps the voltage stress of all switching devices in the inverter bridge and pulse excitation network within the DC power supply voltage range, thus significantly reducing reliance on high-voltage devices and substantially reducing manufacturing costs and power redundancy; simultaneously, by superimposing the excitation pulse with the main power supply in series, it achieves a steep current rise edge, significantly improving the target ionization rate and effectively suppressing arc discharge. Combined with the neutralization effect of the forward bias voltage on the target surface charge, it further enhances ion diffraction capability and improves the coating uniformity of complex workpieces. While improving power supply operating efficiency and reliability, this invention provides a practical, low-cost, high-performance solution for the widespread application of high-power pulsed magnetron sputtering technology in high-end coating fields such as precision molds, cutting tools, and medical devices.

[0036] This invention utilizes two 1700V half-bridge modules connected in series with a high-voltage and low-voltage isolation diode to form an H-bridge, and a 1200V half-bridge module connected in parallel with the excitation power supply to form a pulse excitation circuit. While meeting the requirement of high voltage output above 1700V, the circuit topology achieves stable bipolar high-power pulse output, significantly reduces device cost and power redundancy, improves power efficiency and discharge stability, and applies a positive voltage through a low-voltage forward bias power supply to neutralize the target surface charge, thereby enhancing ion diffraction capability and improving coating quality.

[0037] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection claimed by the appended claims and their equivalents is defined.

Claims

1. A high-efficiency, low-cost bipolar high-power pulsed magnetron sputtering power supply with excitation pulse, characterized in that, include: At least three DC power supplies; An inverter bridge circuit is used to convert direct current into bipolar pulse output; One output terminal is used to connect to the magnetron sputtering target load; An energy clamping network is connected between the inverter bridge and the output terminal to absorb and clamp the reverse electromotive force generated by the load and output cable when the switching devices are turned off, so that the voltage of each switching device in the inverter bridge is limited to near the high voltage negative sputtering power supply voltage. as well as A pulse excitation network, connected in series between the output terminal and the load, is used to superimpose an excitation pulse at the beginning of the negative sputtering pulse to rapidly excite plasma discharge. A first voltage isolation network is used to isolate high voltage and low voltage potentials and to provide a path for the reverse electromotive force generated by the high voltage pulse turn-off. A second voltage isolation network is used to isolate the effect of the back electromotive force generated by the high voltage shutdown on the low voltage.

2. The high-efficiency, low-cost bipolar high-power pulsed magnetron sputtering power supply with excitation pulse according to claim 1, characterized in that, The inverter bridge is composed of a first, second, third, and fourth switching device to form an H-bridge structure. The first and second switching devices are connected in series to form a first half-bridge, and the third and fourth switching devices are connected in series to form a second half-bridge. The first half-bridge is connected in parallel to the two ends of a low-voltage positive bias power supply, and the second half-bridge is connected in parallel to the two ends of a high-voltage negative sputtering power supply.

3. The high-efficiency, low-cost bipolar high-power pulsed magnetron sputtering power supply with excitation pulse according to claim 2, characterized in that, The energy clamping network includes: The energy clamping network includes: A first diode is connected between the midpoint of the first half-bridge and the positive terminal of the low-voltage forward bias power supply. A second diode is connected between the midpoint of the first half-bridge and the midpoint of the second half-bridge; A first capacitor is connected in parallel across the low-voltage forward bias power supply. A second capacitor is connected in parallel across the two ends of the high-voltage negative sputtering power supply; A third capacitor is also connected in parallel across the high-voltage negative sputtering power supply.

4. The high-efficiency, low-cost bipolar high-power pulsed magnetron sputtering power supply with excitation pulse according to claim 1, characterized in that, The pulse excitation network includes: One excitation pulse power supply; A fifth switching device and a sixth switching device are connected to the excitation pulse power supply and are used to control the application of the excitation pulse; A fourth capacitor is connected in parallel across the excitation pulse power supply to stabilize its voltage; A fifth diode and a sixth diode are connected in antiparallel between the collector and emitter of the fifth and sixth switching devices, respectively, to form a clamping path.

5. The high-efficiency, low-cost bipolar high-power pulsed magnetron sputtering power supply with excitation pulse according to claim 1, characterized in that, The pulse excitation network is connected in series between the second or first terminal of the output and the load, and works in conjunction with the inverter bridge circuit, so that in the initial stage of the negative sputtering pulse, the excitation pulse power supply and the high-voltage negative sputtering power supply are output in series and superimposed; after the excitation is completed, the excitation pulse power supply is bypassed by the devices in the pulse excitation network, and only the high-voltage negative sputtering power supply is maintained to discharge through the inverter bridge circuit.

6. The high-efficiency, low-cost bipolar high-power pulsed magnetron sputtering power supply with excitation pulse according to claim 1, characterized in that, The DC power supply includes a high-voltage negative sputtering power supply and a low-voltage positive bias power supply, which are used to provide negative sputtering high-voltage pulses and positive charge neutralization pulses, respectively.

7. The high-efficiency, low-cost bipolar high-power pulsed magnetron sputtering power supply with excitation pulse according to claim 6, characterized in that, The output voltage of the high-voltage negative sputtering power supply is set to be only slightly higher than the actual voltage required by the load in order to improve the power supply operating efficiency.

8. The high-efficiency, low-cost bipolar high-power pulsed magnetron sputtering power supply with excitation pulse according to claim 1, characterized in that, The withstand voltage requirements of each switching device in the inverter bridge circuit and each switching device in the pulse excitation network are slightly higher than the voltage of the DC power supply.

9. A method for outputting a high-efficiency, low-cost bipolar high-power pulsed magnetron sputtering power supply with excitation pulse as described in any one of claims 1 to 8, characterized in that, Includes the following steps: a. In the initial stage of the negative sputtering pulse, the corresponding switching devices in the inverter bridge circuit and the switching devices in the pulse excitation network are simultaneously turned on, so that the excitation pulse power supply and the high-voltage negative sputtering power supply are connected in series and superimposed to output a high-amplitude excitation pulse to the load; b. After excitation is completed, the switching devices in the pulse excitation network are turned off, and only the high-voltage negative sputtering power supply maintains negative sputtering discharge to the load through the inverter bridge and the excitation circuit bypass device; c. After the negative sputtering pulse ends, another set of switching devices in the inverter bridge is turned on to apply a positive bias voltage to the load to neutralize the target surface charge; d. During the turn-off period of the switching devices, the reverse electromotive force is absorbed and clamped by the energy clamping network to ensure that the voltage across each switching device does not exceed the DC power supply voltage.

10. A magnetron sputtering coating apparatus, characterized in that, Including the high-efficiency, low-cost bipolar high-power pulsed magnetron sputtering power supply with excitation pulse as described in any one of claims 1 to 8.

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