Ion energy control system and control method

Abstract

The invention provides an ion energy control system and a control method, the ion energy control system is used for outputting a voltage with a preset waveform to a bias electrode, and the ion energy control system comprises a waveform generation circuit which generates the voltage with the preset waveform; the output end of the waveform generation circuit is electrically connected with the first end of the oscillation suppression circuit, the second end of the oscillation suppression circuit is used for being electrically connected with a load circuit, and the oscillation suppression circuit is used for suppressing current oscillation in the load circuit when the voltage generated by the waveform generation circuit changes suddenly. According to the ion energy control system, the oscillation suppression circuit is arranged between the waveform generation circuit and the load circuit, when the voltage generated by the waveform generation circuit changes suddenly, current oscillation in the load circuit can be suppressed through the oscillation suppression circuit, the influence on the bias waveform is reduced, and therefore the control precision is improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing, and in particular to an ion energy control system and a control method. Background Art

[0002] Etching is a critical step in semiconductor manufacturing. Etching can make circuit components on a chip by removing surface materials. In the etching process, plasma is usually used to etch materials. Plasma is formed by applying high voltage to a gas, which contains a large number of ions and free electrons. When the plasma comes into contact with the material being processed, the ions hit the surface of the material and etch it.

[0003] In order to achieve high-precision etching, the ion energy needs to be controlled. A bias waveform is usually used to control the ion energy. The bias waveform is a voltage waveform applied during the etching process, which can control the formation of plasma and the energy of the ions. The shape of the bias waveform is very important for controlling the etching process. Therefore, it is necessary to be able to accurately control the shape and amplitude of the bias waveform.

[0004] In practical applications, the parasitic inductance and capacitance in the circuit will form a resonant loop when the voltage suddenly changes. In this resonant loop, energy will be continuously transferred between the parasitic capacitance and the parasitic inductance, resulting in oscillation of voltage and current. This oscillation will deform the bias waveform and make it very difficult to control the ion energy, thus affecting the control of the bias waveform. Summary of the invention

[0005] The present invention aims to solve the problem in the prior art that when the voltage suddenly changes, the parasitic inductance and parasitic capacitance in the circuit will form a resonant loop, thereby affecting the control of the bias waveform.

[0006] According to a first aspect of the present invention, an ion energy control system is disclosed for outputting a voltage of a preset waveform to a bias electrode, the ion energy control system comprising: a waveform generating circuit, the waveform generating circuit generating a voltage of a preset waveform; an oscillation suppression circuit, the output end of the waveform generating circuit being electrically connected to a first end of the oscillation suppression circuit, the second end of the oscillation suppression circuit being electrically connected to a load circuit, the oscillation suppression circuit being used to suppress current oscillations in the load circuit when the voltage generated by the waveform generating circuit changes suddenly.

[0007] Furthermore, the oscillation suppression circuit includes: a unidirectional branch, a first end of which is electrically connected to the waveform generating circuit, the first end of which is used to be electrically connected to the load circuit, the unidirectional branch is conducted in the direction from the output end of the waveform generating circuit to the load circuit, and is disconnected in the direction from the load circuit to the output end of the waveform generating circuit; an oscillation suppression resistor, the oscillation suppression resistor is connected in parallel with the unidirectional branch, and the oscillation suppression resistor is used to consume the energy of the oscillating current in the load circuit when the voltage generated by the waveform generating circuit changes suddenly.

[0008] Furthermore, the unidirectional branch includes: a first unidirectional switch and a first resistor, the first unidirectional switch and the first resistor are arranged in series, the conduction direction of the first unidirectional switch is from the output end of the waveform generating circuit to the load circuit, and the first resistor is smaller than the oscillation suppression resistor.

[0009] Furthermore, there are multiple first unidirectional switches, and the multiple first unidirectional switches are arranged in series.

[0010] Furthermore, the oscillation suppression circuit further includes: an adjustable resistor, wherein the adjustable resistor is connected in parallel with the oscillation suppression resistor.

[0011] Furthermore, the oscillation suppression circuit also includes: a resistance adjustment branch, the resistance adjustment branch is connected in parallel with the oscillation suppression resistor, the resistance adjustment branch has a third resistor and a branch switch arranged in series, and the branch switch is used to control the on and off of the resistance adjustment branch.

[0012] Furthermore, there are multiple resistance adjustment branches, and the multiple resistance adjustment branches are connected in parallel with the oscillation suppression circuit. The multiple resistance adjustment branches adjust the energy rate of consuming the oscillating current by controlling the number of opening and closing of the branch switches.

[0013] Further, the waveform generating circuit includes: a power supply branch, a first end of the power supply branch is used for grounding, a second end of the power supply branch is the output end of the waveform generating circuit, the power supply branch has a first DC source and a first switch arranged in series, and the first switch is located between the first DC source and the second end of the power supply branch; a constant current source branch, a first end of the constant current source branch is used for grounding; a second switch, a first end of the second switch is electrically connected to the first end of the power supply branch, and a second end of the second switch is electrically connected to the second end of the constant current source branch; a third switch, a first end of the third switch is electrically connected to the second end of the power supply branch, and a second end of the third switch is electrically connected to the second end of the constant current source branch.

[0014] Furthermore, the waveform generating circuit also includes: a controller, which is electrically connected to the first switch, the second switch and the third switch respectively, and is used to control the first switch, the second switch and the third switch to open and close in sequence according to a preset order, so that the waveform generating circuit outputs a voltage of a preset waveform.

[0015] Furthermore, the constant current source branch includes: a second DC source, a first end of the second DC source is a ground end; a first inductor, a first end of the first inductor is electrically connected to a second end of the second DC source, and a second end of the first inductor is electrically connected to a second end of the second switch and a second end of the third switch, respectively.

[0016] Furthermore, the constant current source branch includes: a second DC source, a first end of the second DC source is a ground end; a first switch tube, a first end of the first switch tube is electrically connected to the second end of the second DC source, and a second end of the first switch tube is electrically connected to the second end of the second switch and the second end of the third switch respectively; a control unit, the control unit is electrically connected to the first switch tube, and the control unit is used to adjust the on-resistance of the first switch tube to adjust the current flowing through the first switch tube.

[0017] According to the second aspect of the present invention, a control method for an ion energy control system is also disclosed, and the control method is used to control the above-mentioned ion energy control system; the control method comprises: a first time period: controlling the first switch to be disconnected, the second switch to be turned on, and the third switch to be turned on; a second time period: controlling the first switch to be disconnected, the second switch to be turned on, and the third switch to be disconnected; a third time period: controlling the first switch to be turned on, the second switch to be turned on, and the third switch to be disconnected; a fourth time period: controlling the first switch to be disconnected, the second switch to be turned on, and the third switch to be disconnected; a fifth time period: controlling the first switch to be disconnected, the second switch to be turned on, and the third switch to be turned on; a sixth time period: controlling the first switch to be disconnected, the second switch to be disconnected, and the third switch to be turned on.

[0018] The ion energy control system of the present invention sets an oscillation suppression circuit between the waveform generating circuit and the load circuit. When the voltage generated by the waveform generating circuit changes suddenly, the oscillation suppression circuit can suppress the current oscillation in the load circuit, reduce the influence on the bias waveform, and thus improve the control accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the structure of an ion energy control system according to the first embodiment of the present invention;

[0020] Figure 2 is a circuit diagram of an ion energy control system according to a first embodiment of the present invention;

[0021] Figure 3 This is a current flow diagram of the ion energy control system in the t2-t3 phase according to the first embodiment of the present invention;

[0022] Figure 4 This is a current flow diagram of the ion energy control system in the t4-t6 phase according to the first embodiment of the present invention;

[0023] Figure 5 A circuit diagram of an oscillation suppression circuit of an ion energy control system according to a second embodiment of the present invention;

[0024] Figure 6 This is a circuit diagram of an oscillation suppression circuit of an ion energy control system according to a third embodiment of the present invention;

[0025] Figure 7 This is a current flow diagram of the oscillation suppression circuit of the ion energy control system in the third embodiment of the present invention during the t2-t3 phase;

[0026] Figure 8 This is a current flow diagram of the oscillation suppression circuit of the ion energy control system in the third embodiment of the present invention during the t4-t6 phase;

[0027] Fig. 9 This is a current flow diagram of the waveform generating circuit of the ion energy control system in the t0-t1 phase of the first embodiment of the present invention;

[0028] Fig.10 This is a current flow diagram of the waveform generating circuit of the ion energy control system in the first embodiment of the present invention during the t1-t2 phase;

[0029] Fig.11 This is a current flow diagram of the waveform generating circuit of the ion energy control system in the first embodiment of the present invention during the t2-t3 phase;

[0030] Fig.12 This is a current flow diagram of the waveform generating circuit of the ion energy control system in the first embodiment of the present invention during the t3-t4 phase;

[0031] Fig.13 This is a current flow diagram of the waveform generating circuit of the ion energy control system in the first embodiment of the present invention during the t4-t5 phase;

[0032] Fig.14 This is a current flow diagram of the waveform generating circuit of the ion energy control system in the first embodiment of the present invention during the t5-t6 phase;

[0033] Fig.15 This is a switch timing control diagram of a waveform generating circuit of an ion energy control system according to the first embodiment of the present invention;

[0034] Fig.16 is a waveform diagram of sheath voltage in the prior art;

[0035] Fig.17 This is a waveform diagram of the sheath voltage generated by the ion energy control system according to the first embodiment of the present invention;

[0036] Fig.18 Schematic diagram of a waveform generating circuit of an ion energy control system according to a fourth embodiment of the present invention;

[0037] List of reference numerals:

[0038] 10. Waveform generating circuit; 11. Power supply branch; 111. First DC source; 112. First switch; 12. Constant current source branch; 121. Second DC source; 122. First inductor; 123. First switch tube; 124. Control unit; 13. Second switch; 14. Third switch; 15. Controller; 16. First protection element; 17. Second protection element; 18. Third protection element; 20. Oscillation suppression circuit; 21. One-way branch; 211. First one-way switch; 212. First resistor; 22. Oscillation suppression resistor; 23. Adjustable resistor; 24. Resistance adjusting branch; 241. Third resistor; 242. Branch switch; 243. Second one-way switch; 30. Bias electrode; 40. Load circuit. DETAILED DESCRIPTION

[0039] In order to enable those skilled in the art to better understand the technical solution of the present invention, the ion energy control system and the control method thereof provided by the present invention are described in detail below in conjunction with the accompanying drawings.

[0040] The prior art uses a voltage step gradient method, uses four DC sources, controls each DC power supply to supply power alternately through five electronic switches, and controls the timing to turn the electronic switches on and off in a specific order to generate a customized bias waveform. Since the voltage changes step by step through four DC power supplies, the voltage changes step by step, thereby avoiding voltage mutations and weakening the interference of parasitic capacitance and parasitic inductance on the bias waveform.

[0041] However, since four DC power supplies are used in conjunction with five electronic switches, the circuit and switch control timing are more complicated. The overall volume is relatively large, which increases the equipment cost. Moreover, the ion energy control system of the present invention can not only reduce waveform oscillation, but also simplify the circuit structure.

[0042] like Figure 1As shown, the present invention discloses an ion energy control system for outputting a voltage of a preset waveform to a bias electrode 30. The ion energy control system includes: a waveform generating circuit 10 and an oscillation suppression circuit 20. The waveform generating circuit 10 generates a voltage of a preset waveform. The output end of the waveform generating circuit 10 is electrically connected to the first end of the oscillation suppression circuit 20. The second end of the oscillation suppression circuit 20 is used to be electrically connected to a load circuit 40. The oscillation suppression circuit 20 is used to suppress current oscillations in the load circuit 40 when the voltage generated by the waveform generating circuit 10 changes suddenly.

[0043] The ion energy control system of the present invention sets an oscillation suppression circuit 20 between the waveform generating circuit 10 and the load circuit 40. When the voltage generated by the waveform generating circuit 10 suddenly changes, the current oscillation in the load circuit 40 can be suppressed by the oscillation suppression circuit 20, thereby reducing the impact on the bias waveform and improving the control accuracy.

[0044] Combine the following Figure 1 and Figure 2 Embodiment 1 in the present invention is used to specifically describe the ion energy control system of the present invention.

[0045] like Figure 1 and Figure 2 As shown, in this embodiment, the waveform generating circuit 10 includes: a power supply branch 11, a constant current source branch 12, a second switch 13, a third switch 14 and a controller 15.

[0046] The first end of the power branch 11 is used for grounding, the second end of the power branch 11 is the output end of the waveform generating circuit 10, the power branch 11 has a first DC source 111 and a first switch 112 arranged in series, and the first switch 112 is located between the first DC source 111 and the second end of the power branch 11; the first end of the constant current source branch 12 is used for grounding; the first end of the second switch 13 is electrically connected to the first end of the power branch 11, and the second end of the second switch 13 is electrically connected to the second end of the constant current source branch 12; the first end of the third switch 14 is electrically connected to the second end of the power branch 11, and the second end of the third switch 14 is electrically connected to the second end of the constant current source branch 12.

[0047] The controller 15 is electrically connected to the first switch 112, the second switch 13 and the third switch 14 respectively, and is used to control the first switch 112, the second switch 13 and the third switch 14 to open and close in a preset order so that the waveform generating circuit 10 outputs a voltage of a preset waveform.

[0048] It should be noted that, in this embodiment, the first switch 112, the second switch 13 and the third switch 14 can be switch tubes, and the control end of each switch tube is electrically connected to the controller 15, so that the opening and closing of the first switch 112, the second switch 13 and the third switch 14 can be controlled by the controller 15.

[0049] It should also be noted that the waveform generating circuit 10 further includes a first protection element 16, a second protection element 17 and a third protection element 18. The first protection element 16 is connected in parallel with the first switch 112, the first end of the first protection element 16 is electrically connected to the first DC source 111, and the second end of the first protection element 16 is electrically connected to the second end of the power branch 11; the second protection element 17 is connected in parallel with the second switch 13, the first end of the second protection element 17 is electrically connected to the first end of the power branch 11, and the second end of the second protection element 17 is electrically connected to the second end of the constant current source branch 12; the third protection element 18 is connected in parallel with the third switch 14, the first end of the third protection element 18 is electrically connected to the second end of the power branch 11, and the second end of the third protection element 18 is electrically connected to the second end of the constant current source branch 12.

[0050] In this embodiment, the first protection element 16, the second protection element 17 and the third protection element 18 are all diodes. The parallel diodes can ensure the safety of the switch tube, prevent the reverse voltage and the high-voltage pulse generated by the inductor from damaging the switch tube, and effectively protect the normal operation of the switch tube.

[0051] The oscillation suppression circuit 20 includes: a unidirectional branch 21 and an oscillation suppression resistor 22. The first end of the unidirectional branch 21 is electrically connected to the waveform generation circuit 10, and the first end of the unidirectional branch 21 is used to be electrically connected to the load circuit 40. The unidirectional branch 21 is turned on in the direction from the output end of the waveform generation circuit 10 to the load circuit 40, and is turned off in the direction from the load circuit 40 to the output end of the waveform generation circuit 10; the oscillation suppression resistor 22 is connected in parallel with the unidirectional branch 21, and the oscillation suppression resistor 22 is used to consume the energy of the oscillation current in the load circuit 40 when the voltage generated by the waveform generation circuit 10 suddenly changes. Among them, the unidirectional branch 21 includes: a first unidirectional switch 211 and a first resistor 212, the first unidirectional switch 211 and the first resistor 212 are arranged in series, the first unidirectional switch 211 is turned on in the direction from the output end of the waveform generation circuit 10 to the load circuit 40, and the first resistor 212 is smaller than the oscillation suppression resistor 22.

[0052] During use, if Figure 3 As shown, when the current flows from the waveform generating circuit 10 to the load circuit 40, that is, the current flows from Figure 3When the current flows from the left side to the right side, the current will pass through the unidirectional branch 21 and the oscillation suppression resistor 22 respectively. Since the first resistor 212 is smaller than the oscillation suppression resistor 22, most of the current will flow through the unidirectional branch 21 to avoid current loss in the oscillation suppression resistor 22.

[0053] like Figure 4 As shown, when the voltage generated by the waveform generating circuit 10 suddenly changes, an oscillating current is generated in the load circuit 40. During the oscillation process, the current flows from the load circuit 40 to the waveform generating circuit 10, that is, the oscillating current flows from the load circuit 40 to the waveform generating circuit 10. Figure 4 The right side of the flow flows to the left side. At this time, due to the action of the first one-way switch 211, the one-way branch 21 Figure 4 The circuit is open from right to left in the middle, so the oscillating current can only pass through the oscillation suppression resistor 22. Since the resistance value of the oscillation suppression resistor 22 is large, the energy of the oscillating current can be effectively consumed, so that the oscillating current decays rapidly, thereby achieving the effect of suppressing current oscillation. In addition, when the first switch 112 is a switch tube, at the moment when the first switch 112 is turned on, the first resistor 212 can limit the size of the transient current on the first switch 112, so as to protect the first switch 112.

[0054] It should be noted that, in the above-mentioned first embodiment, the oscillation suppression circuit 20 includes: a unidirectional branch 21 and an oscillation suppression resistor 22, but this is not restrictive. Figure 5 The second embodiment shown is basically the same as the first embodiment, except that, in this embodiment, the oscillation suppression circuit 20 further includes an adjustable resistor 23, which is connected in parallel with the oscillation suppression resistor 22. The resistor can be adjusted to a suitable value according to the waveform test to reduce the voltage and current oscillation degree in the current loop of the ion energy control system and the chamber load equivalent model.

[0055] like Figures 6 to 8 The third embodiment shown also discloses an ion energy control system, which is basically the same as the first embodiment, except that, in this embodiment, the oscillation suppression circuit 20 further includes: a resistance adjustment branch 24, the resistance adjustment branch 24 is connected in parallel with the oscillation suppression resistor 22, and the resistance adjustment branch 24 has a third resistor 241, a second unidirectional switch 243 and a branch switch 242 arranged in series, and the branch switch 242 is used to control the on and off of the resistance adjustment branch 24, and the second unidirectional switch 243 is turned on in the direction from the load circuit 40 to the waveform generation circuit 10. By setting the second unidirectional switch 243, the current flowing from the waveform generation circuit 10 to the load circuit 40 can be prevented from being lost on the third resistor 241. Among them, there are multiple resistance adjustment branches 24, and the multiple resistance adjustment branches 24 are all connected in parallel with the oscillation suppression circuit 20. The multiple resistance adjustment branches 24 adjust the energy rate of the oscillation current by controlling the number of branch switches 242 opened and closed.

[0056] During use, if Figure 7 As shown, when the current flows from the waveform generating circuit 10 to the load circuit 40, that is, the current flows from Figure 7 When the current flows from the left side to the right side, the branch switch 242 is disconnected, and the current passes through the unidirectional branch 21 and the oscillation suppression resistor 22 respectively. Since the first resistor 212 is smaller than the oscillation suppression resistor 22, most of the current flows through the unidirectional branch 21, avoiding the current loss in the oscillation suppression resistor 22.

[0057] like Figure 8 As shown, when the voltage generated by the waveform generating circuit 10 suddenly changes, an oscillating current is generated in the load circuit 40. During the oscillation process, the current flows from the load circuit 40 to the waveform generating circuit 10, that is, the oscillating current flows from the load circuit 40 to the waveform generating circuit 10. Figure 8 The flow from the right side to the left side, at this time, the branch switch 242 is closed, and due to the action of the first unidirectional switch 211, the unidirectional branch 21 is closed. Figure 8 The circuit is open from right to left in the middle, and the oscillating current can only pass through the oscillation suppression resistor 22 and the resistor on the resistance adjustment branch 24. Since the resistance values ​​of the oscillation suppression resistor 22 and the third resistor 241 are relatively large, the energy of the oscillating current can be effectively consumed, so that the oscillating current decays rapidly, thereby achieving the effect of suppressing current oscillation. In addition, by setting multiple resistance adjustment branches 24, the number of branch switches 242 closures can be adjusted according to the waveform test results, so as to adjust the resistance to a suitable value, thereby reducing the voltage and current oscillation degree in the current loop of the ion energy control system and the chamber load equivalent model.

[0058] It should also be noted that, in the present embodiment, the first unidirectional switch 211 is a diode, and there are two first unidirectional switches 211 on the unidirectional branch 21, which are arranged in series. Multiple first unidirectional switches 211 connected in series can reduce the diode equivalent junction capacitance when a single diode is used, thereby preventing the oscillating high-frequency current from flowing through the unidirectional branch 21.

[0059] In the prior art, since it is impossible to suppress the oscillating current generated when the voltage suddenly changes, four DC sources are used to gradually change the voltage in a step-by-step manner to reduce the influence of the oscillating current on the control of the bias waveform. This method uses four DC sources, which not only makes the overall equipment volume larger, but also makes the circuit design and switch control timing complex, resulting in increased costs. Although this step-by-step voltage change method can reduce oscillations, it means that multiple low-potential voltages will be generated, thereby increasing the pulse width and increasing the number of ions in the low-energy peak. Moreover, since there are many switching tubes, the voltage divider on the switching tube is large, and the loss will also increase accordingly.

[0060] Since the present invention is provided with an oscillation suppression circuit 20, when the voltage suddenly changes, the oscillation suppression circuit 20 can suppress the influence of the oscillation current on the control of the bias waveform. Therefore, the number of DC sources can be greatly reduced. For example, in this embodiment, only two DC sources and three switching tubes are used, with fewer components and a simple structure. In addition, the voltage can be directly increased to a preset voltage, the voltage transition stage can be reduced, and the quality of the ion energy control bias waveform can be effectively improved. Since the voltage transition stage is reduced, the waveform period is shorter, and the proportion of low-energy peak ions can be reduced.

[0061] Combine the following Figures 9 to 15 The control method of the ion energy control system according to the first embodiment of the present invention is described in detail.

[0062] In such Figures 9 to 14 In the first embodiment, the constant current source branch 12 includes: a second DC source 121 and a first inductor 122, the first end of the second DC source 121 is a ground end; the first end of the first inductor 122 is electrically connected to the second end of the second DC source 121, and the second end of the first inductor 122 is electrically connected to the second end of the second switch 13 and the second end of the third switch 14 respectively.

[0063] like Fig.15 As shown, each cycle of the bias waveform is divided into six stages from t0 to t6, and the control method includes the following steps:

[0064] First time period: control the first switch 112 to be turned off, the second switch 13 to be turned on, and the third switch 14 to be turned on. Fig. 9 As shown, in the t0-t1 stage, the first switch 112 is turned off, the second switch 13 is turned on, and the third switch 14 is turned on. In this stage, the first inductor 122 stores energy, the current of the first inductor 122 gradually increases, and the output potential of the waveform generating circuit 10 rises to the ground potential.

[0065] The second time period: the first switch 112 is turned off, the second switch 13 is turned on, and the third switch 14 is turned off. Fig.10 As shown, in the period t1-t2, the first switch 112 is turned off, the second switch 13 is turned on, and the third switch 14 is turned off. In this period, the current of the first inductor 122 continues to increase.

[0066] The third time period: the first switch 112 is turned on, the second switch 13 is turned on, and the third switch 14 is turned off. Fig.11 As shown, in the period t2-t3, the first switch 112 is turned on, the second switch 13 is turned on, and the third switch 14 is turned off. In this period, the first inductor 122 continues to store energy, and the output potential of the waveform generating circuit 10 rises to the voltage of the first DC source 111.

[0067] The fourth time period: the first switch 112 is turned off, the second switch 13 is turned on, and the third switch 14 is turned off. Fig.12 As shown, in the stage t3-t4, the first switch 112 is turned off, the second switch 13 is turned on, and the third switch 14 is turned on. In this stage, the first inductor 122 continues to store energy.

[0068] The fifth time period: the first switch 112 is turned off, the second switch 13 is turned on, and the third switch 14 is turned on. Fig.13 As shown, in the stage t4-t5, the first switch 112 is turned off, the second switch 13 is turned on, and the third switch 14 is turned on. In this stage, the first inductor 122 continues to store energy, and the output potential of the waveform generating circuit 10 drops to the ground potential.

[0069] The sixth time period: the first switch 112 is turned off, the second switch 13 is turned off, and the third switch 14 is turned on. Fig.14 As shown, in the t5-t6 phase, the first switch 112 is turned off, the second switch 13 is turned off, and the third switch 14 is turned on. The current in the first inductor 122 cannot suddenly change and continue to flow. The first inductor 122 extracts charge from the plasma load. At the same time, the voltage waveform at the output end of the waveform generating circuit 10 is formed as shown in FIG. Fig.15 In the middle Tslope stage slope, after the voltage across the first inductor 122 is reversed, the current in the first inductor 122 gradually decreases.

[0070] It should be noted that by adjusting the voltage of the second DC source 121, the slope of the Tslope stage can be adjusted to a suitable steepness. Fig.15 Uchuck is similar to the negative bias waveform, where Uchuck is Figure 1 Voltage waveform on the wafer surface in the middle chamber.

[0071] It should also be noted that if Figure 3 As shown, during the t2-t3 phase, the current flows from the waveform generating circuit 10 to the load circuit 40, that is, the current flows from the waveform generating circuit 10 to the load circuit 40. Figure 3 When the current flows from the left side to the right side, the current will pass through the unidirectional branch 21 and the oscillation suppression resistor 22 respectively. Since the first resistor 212 is smaller than the oscillation suppression resistor 22, most of the current will flow through the unidirectional branch 21 to avoid current loss in the oscillation suppression resistor 22.

[0072] like Figure 4 As shown, in the stage t4-t6, the voltage generated by the waveform generating circuit 10 suddenly changes, and an oscillating current is generated in the load circuit 40. During the oscillation process, the current flows from the load circuit 40 to the waveform generating circuit 10, that is, the oscillating current flows from the load circuit 40 to the waveform generating circuit 10. Figure 4 The right side of the flow flows to the left side. At this time, due to the action of the first one-way switch 211, the one-way branch 21 Figure 4The circuit is open from right to left in the middle, so the oscillating current can only pass through the oscillation suppression resistor 22. Since the resistance value of the oscillation suppression resistor 22 is large, the energy of the oscillating current can be effectively consumed, so that the oscillating current decays rapidly, thereby achieving the effect of suppressing current oscillation.

[0073] like Fig.16 As shown, it is the waveform of the sheath voltage when the oscillation suppression circuit 20 of the present invention is not used. Because the current on the parasitic inductance of the loop cannot change suddenly, the loop current continuously charges and discharges the parasitic capacitance, and the voltage has strong oscillations in the Tpulse stage and the Tslope stage.

[0074] like Fig.17 As shown, when the oscillation suppression circuit 20 of the present invention is used, the oscillation suppression circuit 20 can absorb the oscillation energy and there is almost no oscillating sheath voltage waveform.

[0075] The present invention uses three voltage stages (t0-t2, t2-t4, t4-t6) to generate ion energy control bias. Compared with the prior art, the Tpulse stage reduces the residence time of two voltage stages, and the Tpulse stage time can be controlled to be shorter. The number of low-energy ions accelerated during this time period is relatively smaller, and the proportion of low-energy peak ions is smaller. Moreover, since the number of DC power supplies, switch tubes and diodes used is reduced, the cost is reduced, and the circuit design and switch control timing are simplified.

[0076] It should be noted that in the above embodiment 1, it should be noted that the constant current source branch 12 includes: a second DC source 121 and a first inductor 122, but this is not restrictive. Fig.18 In the fourth embodiment shown, it is basically the same as the first embodiment, except that the constant current source branch 12 includes: a second DC source 121, a first switch tube 123 and a control unit 124, the first end of the second DC source 121 is a ground end; the first end of the first switch tube 123 is electrically connected to the second end of the second DC source 121, and the second end of the first switch tube 123 is electrically connected to the second end of the second switch 13 and the second end of the third switch 14 respectively; the control unit 124 is electrically connected to the first switch tube 123, and the control unit 124 is used to adjust the on-resistance of the first switch tube 123 to adjust the current flowing through the first switch tube 123. The constant current source is constructed by using the dynamic resistance characteristics of the first switch tube 123. When the voltage of the second DC source 121 is constant and appropriate, the voltage of the DC source in the control unit 124 is adjusted, the output level of the comparator changes, the control voltage of the first switch tube 123 changes, and the on-resistance of the first switch tube 123 changes, thereby adjusting the current flowing through the first switch tube 123. This implementation method has higher compensation current control accuracy.

[0077] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. An ion energy control system for outputting a voltage of a preset waveform to a bias electrode (30), characterized in that: The ion energy control system comprises: A waveform generating circuit (10), wherein the waveform generating circuit (10) generates a voltage of a preset waveform; An oscillation suppression circuit (20), wherein the output end of the waveform generating circuit (10) is electrically connected to a first end of the oscillation suppression circuit (20), and the second end of the oscillation suppression circuit (20) is used to be electrically connected to a load circuit (40), and the oscillation suppression circuit (20) is used to suppress current oscillation in the load circuit (40) when the voltage generated by the waveform generating circuit (10) changes suddenly.

2. The ion energy control system according to claim 1, characterized in that: The oscillation suppression circuit (20) comprises: a unidirectional branch (21), wherein a first end of the unidirectional branch (21) is electrically connected to the waveform generating circuit (10), and the first end of the unidirectional branch (21) is used to be electrically connected to the load circuit (40), the unidirectional branch (21) is conductive in a direction from the output end of the waveform generating circuit (10) to the load circuit (40), and is disconnected in a direction from the load circuit (40) to the output end of the waveform generating circuit (10); An oscillation suppression resistor (22), the oscillation suppression resistor (22) being connected in parallel with the unidirectional branch (21), the oscillation suppression resistor (22) being used to consume energy of an oscillating current in the load circuit (40) when the voltage generated by the waveform generating circuit (10) changes suddenly.

3. The ion energy control system according to claim 2, characterized in that: The unidirectional branch (21) comprises: a first unidirectional switch (211) and a first resistor (212); the first unidirectional switch (211) and the first resistor (212) are arranged in series; the first unidirectional switch (211) is turned on in a direction from the output end of the waveform generating circuit (10) to the load circuit (40); and the first resistor (212) is smaller than the oscillation suppression resistor (22).

4. The ion energy control system according to claim 3, characterized in that: There are a plurality of the first unidirectional switches (211), and the plurality of the first unidirectional switches (211) are arranged in series.

5. The ion energy control system according to claim 2, characterized in that: The oscillation suppression circuit (20) further includes: An adjustable resistor (23), the adjustable resistor (23) being connected in parallel with the oscillation suppression resistor (22).

6. The ion energy control system according to claim 2, characterized in that: The oscillation suppression circuit (20) further includes: A resistance regulating branch (24), the resistance regulating branch (24) being connected in parallel with the oscillation suppression resistor (22), the resistance regulating branch (24) having a third resistor (241) and a branch switch (242) arranged in series, the branch switch (242) being used to control the on and off of the resistance regulating branch (24).

7. The ion energy control system according to claim 6, characterized in that: There are multiple resistance adjustment branches (24), and the multiple resistance adjustment branches (24) are connected in parallel with the oscillation suppression circuit (20). The multiple resistance adjustment branches (24) adjust the energy rate of the oscillating current by controlling the number of openings and closings of the branch switches (242).

8. The ion energy control system according to any one of claims 1 to 7, characterized in that: The waveform generating circuit (10) comprises: A power branch (11), wherein a first end of the power branch (11) is used for grounding, a second end of the power branch (11) is an output end of the waveform generating circuit (10), the power branch (11) comprises a first direct current source (111) and a first switch (112) which are arranged in series, and the first switch (112) is located between the first direct current source (111) and the second end of the power branch (11); A constant current source branch (12), wherein a first end of the constant current source branch (12) is used for grounding; a second switch (13), wherein a first end of the second switch (13) is electrically connected to a first end of the power source branch (11), and a second end of the second switch (13) is electrically connected to a second end of the constant current source branch (12); A third switch (14), wherein a first end of the third switch (14) is electrically connected to a second end of the power supply branch (11), and a second end of the third switch (14) is electrically connected to a second end of the constant current source branch (12).

9. The ion energy control system according to claim 8, characterized in that: The waveform generating circuit (10) further comprises: A controller (15), the controller (15) being electrically connected to the first switch (112), the second switch (13) and the third switch (14) respectively, the controller (15) being used to control the first switch (112), the second switch (13) and the third switch (14) to open and close in sequence according to a preset sequence, so that the waveform generating circuit (10) outputs a voltage of a preset waveform.

10. The ion energy control system according to claim 8, characterized in that: The constant current source branch (12) comprises: A second direct current source (121), wherein a first end of the second direct current source (121) is a ground end; A first inductor (122), wherein a first end of the first inductor (122) is electrically connected to a second end of the second DC source (121), and a second end of the first inductor (122) is electrically connected to a second end of the second switch (13) and a second end of the third switch (14), respectively.

11. The ion energy control system according to claim 8, characterized in that: The constant current source branch (12) comprises: A second direct current source (121), wherein a first end of the second direct current source (121) is a ground end; a first switch tube (123), wherein a first end of the first switch tube (123) is electrically connected to a second end of the second direct current source (121), and a second end of the first switch tube (123) is electrically connected to a second end of the second switch (13) and a second end of the third switch (14); A control unit (124), the control unit (124) being electrically connected to the first switch tube (123), the control unit (124) being used to adjust the on-resistance of the first switch tube (123) so as to adjust the current flowing through the first switch tube (123).

12. A control method for an ion energy control system, characterized in that: The control method is used to control the ion energy control system according to any one of claims 8 to 11; the control method comprises: First time period: controlling the first switch (112) to be turned off, the second switch (13) to be turned on, and the third switch (14) to be turned on; In the second time period: the first switch (112) is controlled to be turned off, the second switch (13) is controlled to be turned on, and the third switch (14) is controlled to be turned off; A third time period: controlling the first switch (112) to be turned on, the second switch (13) to be turned on, and the third switch (14) to be turned off; Fourth time period: controlling the first switch (112) to be turned off, the second switch (13) to be turned on, and the third switch (14) to be turned off; Fifth time period: controlling the first switch (112) to be turned off, the second switch (13) to be turned on, and the third switch (14) to be turned on; Sixth time period: controlling the first switch (112) to be turned off, the second switch (13) to be turned off, and the third switch (14) to be turned on.

Images