Plasma generating device and control method

Abstract

The application provides a kind of plasma generating device and control method, plasma generating device includes: process cavity;Carry substrate for the carrier;The carrier is installed in the bottom of process cavity;Target material backplate is installed in the top of process cavity;Direct current power supply, the negative pole of direct current power supply is connected with target material backplate, for output and apply first negative high voltage V 负1 To target material backplate;Controllable high voltage power supply, the negative pole of controllable high voltage power supply is connected with high voltage electrode plate, for output and apply second negative high voltage V 负2 To high voltage electrode plate;The first negative high voltage V 负1 And second negative high voltage V 负2 For superimposed generation high voltage electric field of target material surface;Controller, for controlling controllable high voltage power supply to automatically adjust second negative high voltage V 负2 According to the voltage variation of first negative high voltage V 负1 ;The application is helpful to process gas glow discharge, promotes plasma formation;And can improve atomic utilization and improve the step coverage of hole filling process.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of magnetron sputtering technology in PVD, and particularly to a plasma generating device and a control method. BACKGROUND

[0002] In the magnetron sputtering technology, the directional distribution of sputtered atoms is related to the incident direction of ions, ion energy, target surface morphology, etc. Experiments show that for sputtering of higher energy ions, the directional distribution of sputtered atoms has less correlation with the incident direction of ions. Test data show that the distribution of sputtered atoms in different directions generally follows the cosine function (cos n θ) rule, where θ is the included angle between the emission direction of sputtered atoms and the normal line of the target surface, and the size of the index n is related to the ion energy. For a specific ion / atom combination, n = 1 within a certain energy range, and for sputtering of lower and higher energy ions, n values are less than and greater than 1, respectively. Figure 1 A schematic diagram of such distribution is given; for the case of n = 1, the directional distribution of sputtered atoms is similar to a circular spherical surface; for sputtering of lower and higher energy ions, the directional distribution of sputtered atoms is similar to an ellipsoidal surface, but the former is horizontally offset and the latter is vertically offset, as shown in Figure 1 .

[0003] When the ion energy is low, its incident direction can affect the directional distribution of sputtered atoms; the atom distribution sputtered by oblique incident ions can be shifted to the direction of the reflection angle. Low-energy ion sputtering is mainly a surface elastic collision process, and the impacted atoms have strong directionality. Higher energy ions enter the target material surface layer to a greater depth, undergo multiple collision and scattering, and lose their original directionality.

[0004] In the magnetron sputtering, the incident direction and ion energy of positive ions (such as Ar+ ions) in the plasma are mainly determined by the sputtering voltage, and the sputtering voltage is mainly determined by the input power of the target material power supply, the magnetic field strength, the concentration or flow rate of the discharge gas.

[0005] In the prior art, the normal sputtering voltage of common target materials (titanium, copper, aluminum, molybdenum, etc.) is in the range of 300V-600V, generally not exceeding 650V. The existing target surface voltage cannot provide sufficient incident energy for the incident ions of the plasma, and the atom distribution sputtered by lower energy ions presents a horizontally offset ellipsoidal surface, resulting in more atoms being deposited to the area below the substrate, causing waste of sputtered atoms; in addition, the vertical directionality of sputtered atoms is also greatly reduced, and for metal hole filling process, the step coverage of the thin film is significantly reduced.

[0006] In addition, the maximum output voltage of the existing magnetron sputtering direct current power supply does not exceed 850V, which puts certain requirements on the concentration or flow of discharge gas, the strength of the target surface magnetic field, etc. For example, when the target surface magnetic field strength is insufficient or the target material is a ferromagnetic material (such as iron, cobalt, nickel, etc.), or the specific sputtering process has certain requirements on the process gas pressure (for example, it requires a lower gas pressure, because the scattering effect of the target sputtering atoms is enhanced at a higher sputtering pressure, resulting in a much lower kinetic energy of the sputtering atoms, and the film density is reduced), the glow discharge process is often difficult to start. SUMMARY

[0007] To solve at least one technical problem in the prior art, embodiments of the present application provide a plasma generation device and a control method, which help the process gas glow discharge, are more conducive to starting the glow, and promote the formation of plasma; and the angle between the emission direction of the sputtering atoms and the normal direction of the target surface of the target material is small, so that more sputtering atoms fall on the substrate, which can improve the atomic utilization rate and the step coverage of the hole filling process. To achieve the above technical purposes, the technical solutions adopted by the embodiments of the present application are as follows:

[0008] In a first aspect, the embodiments of the present application provide a plasma generation device, comprising:

[0009] a process chamber;

[0010] a carrier for carrying a substrate; the carrier is installed at the bottom of the process chamber;

[0011] a target material back plate for carrying a target material; the target material back plate is installed at the top of the process chamber and is opposite to the carrier;

[0012] a direct current power supply, a negative electrode of the direct current power supply is connected with the target material back plate, for outputting and applying a first negative high voltage V 负1 to the target material back plate; a positive electrode of the direct current power supply is grounded;

[0013] a controllable high voltage power supply, a negative electrode of the controllable high voltage power supply is connected with a high voltage electrode plate, for outputting and applying a second negative high voltage V 负2 to the high voltage electrode plate; the high voltage electrode plate is parallel to the target surface of the target material and is insulated from the target material back plate; the first negative high voltage V 负1 and the second negative high voltage V 负2 are used to superimpose a high voltage electric field on the surface of the target material; a positive electrode of the controllable high voltage power supply is grounded;

[0014] a controller, for controlling the controllable high voltage power supply to automatically adjust the second negative high voltage V 负2 according to the voltage change of the first negative high voltage V 负1 ; so that the first negative high voltage V 负1 and the second negative high voltage V 负2the voltage and V 和 Keep consistent.

[0015] Further, the first negative high voltage V 负1 and the second negative high voltage V 负2 The voltage and V 和 is 1800V-2200V.

[0016] Further, the high voltage electrode plate is installed on the side of the target backing plate away from the target, and is insulated from the target backing plate by a gap or an insulating layer.

[0017] Further, the high voltage electrode plate is wrapped by an insulating layer and installed inside the target backing plate; the high voltage electrode plate is connected to the negative electrode of the controllable high voltage power supply through an insulating lead wire penetrating out of the target backing plate.

[0018] Further, the carrier is grounded.

[0019] Further, the controller adopts a PLC controller; is used for collecting the output voltage of the direct current power supply, i.e. the first negative high voltage V 负1 , and is used for issuing a control instruction to the controllable high voltage power supply to adjust the second negative high voltage V 负2 .

[0020] In a second aspect, the embodiment of the present application provides a control method of a plasma generating device, which is suitable for the plasma generating device as described above, and comprises the following steps:

[0021] Step S10, setting the initial voltage value HV1 of the second negative high voltage V 负2 output by the controllable high voltage power supply according to the ignition voltage V1 of the direct current power supply and the preset voltage and V 和 ; that is, HV1=V 和 -V1.

[0022] Step S20, introducing a process gas into the process chamber; at the beginning of the ignition stage, the first negative high voltage V 负1 applied to the target backing plate 4 by the direct current power supply is the ignition voltage V1, and the second negative high voltage V 负2 applied to the high voltage electrode plate by the controllable high voltage power supply is the initial voltage value HV1; V1+HV1=V 和 .

[0023] Step S30, monitoring the first negative high voltage V 负1 output by the direct current power supply; when the first negative high voltage V 负1 drops to the sputtering voltage V2 and remains for a set judgment duration, adjusting the second negative high voltage V 负2 to the working voltage value HV2; V2+HV2=V 和 ; entering the magnetron sputtering stage; and performing the magnetron sputtering process for a set magnetron sputtering duration.

[0024] Further, the ignition voltage V1 is 650V-850V.

[0025] Further, the sputtering voltage V2 is 200V-650V.

[0026] Further, the setting judgment duration is 100ms-200ms.

[0027] The technical scheme provided by the embodiment of the application has the beneficial effects that:

[0028] 1) The second negative high voltage V2 generated by the controllable high voltage power supply 负2 Can follow the first negative high voltage V1 generated by the direct current power supply 负1 The voltage changes automatically adjust, and the high voltage electric field generated by superposition makes the target material surface maintain a stable high voltage electric field at all times.

[0029] 2) The electric field generated by the higher voltage helps the process gas glow discharge, is more conducive to glow, and promotes the formation of plasma, so that the magnetron sputtering process proceeds smoothly.

[0030] 3) Under the action of the enhanced high voltage electric field, the argon ions in the plasma bombard the target material with relatively large kinetic energy, the angle between the sputtered atom exit direction and the target surface normal direction is small, so that more sputtered atoms fall on the substrate, which can improve the atom utilization rate and improve the step coverage of the hole filling process. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is a schematic diagram of the direction distribution of sputtered atoms in the embodiment of the application.

[0032] Figure 2 It is a schematic diagram of the structure of the plasma generating device in the embodiment of the application.

[0033] Figure 3 It is a flow chart of the control method in the embodiment of the application.

[0034] Figure 4 It is a schematic diagram of the thin film measurement point in the embodiment of the application.

[0035] Figure 5 It is a schematic diagram of the thin film thickness distribution in the embodiment of the application when sputtering under an applied high voltage electric field.

[0036] Figure 6 It is a schematic diagram of the thin film thickness distribution in the embodiment of the application when sputtering without an applied high voltage electric field. DETAILED DESCRIPTION

[0037] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application.

[0038] In the description of the embodiments of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0039] In the description of the embodiments of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting" should be understood in a broad sense, for example, it can be a fixed connection, or it can be a detachable connection, or an integral connection; it can be a mechanical connection, or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be a communication between two elements, which can be a wireless connection or a wired connection. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0040] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0041] As shown in Figure 2 The embodiments of the present application propose a plasma generating device, which comprises:

[0042] a process cavity 1;

[0043] a carrier 2 for carrying a substrate 3; the carrier 2 is mounted at the bottom of the process cavity 1;

[0044] a target backing plate 4 for carrying a target material 5; the target backing plate 4 is mounted at the top of the process cavity 1 and is opposite to the carrier 2;

[0045] a direct current power supply 6, a negative electrode of the direct current power supply 6 is connected with the target backing plate 4, for outputting and applying a first negative high voltage V 负1 to the target backing plate 4; a positive electrode of the direct current power supply 6 is grounded;

[0046] a controllable high-voltage power supply 7, a negative electrode of the controllable high-voltage power supply 7 is connected with a high-voltage electrode plate 8, for outputting and applying a second negative high voltage V负2 The high-voltage electrode plate 8 is parallel to the target surface of the target material 5 and is insulated from the target back plate 4; the first negative high voltage V 负1 Second negative high voltage V 负2 Used to generate a high-voltage electric field on the surface of the target material 5; the positive terminal of the controllable high-voltage power supply 7 is grounded;

[0047] Controller 9, used to determine the first negative high voltage V 负1 The voltage change controllable high-voltage power supply 7 automatically adjusts the second negative high voltage V. 负2 ; This enables the first negative high voltage V during the ignition stage and magnetron sputtering stage. 负1 With the second negative high voltage V 负2 voltage and V 和 Maintain consistency;

[0048] In some embodiments, the DC power supply 6 is the existing magnetron sputtering DC power supply, whose maximum output voltage is typically 650V to 850V; the controllable high-voltage power supply 7 and the high-voltage electrode plate 8 are added components in this embodiment; the controllable high-voltage power supply 7 can be a DC boost power supply, and the output voltage is controllable; the substrate 3 on the stage 2 is typically a wafer; the target backplate 4 needs to be conductive, and is typically a metal plate; the process chamber 1 is provided with a gas inlet 101 and a gas extraction port 102; before the PVD magnetron sputtering process is performed, the process chamber 1 needs to be evacuated, and then process gases such as argon are introduced;

[0049] In some embodiments, the first negative high voltage V 负1 With the second negative high voltage V 负2 voltage and V 和 The voltage is 1800V to 2200V, typically, for example, 2000V; in this embodiment, no negative sign is added before the voltage value, but it should be understood that a negative high voltage is applied to the target backplate 4 and the high voltage electrode plate 8.

[0050] In some embodiments, the high-voltage electrode plate 8 is mounted on the side of the target back plate 4 that is away from the target 5, and is insulated from the target back plate 4 by a gap or an insulating layer.

[0051] In some embodiments, the high-voltage electrode plate 8 is wrapped with an insulating layer and installed inside the target back plate 4; the high-voltage electrode plate 8 is connected to the negative terminal of the controllable high-voltage power supply 7 through an insulated wire passing through the target back plate 4.

[0052] In some embodiments, the platform 2 is grounded; in other embodiments, the platform 2 may not be grounded.

[0053] In some embodiments, the controller 9 is a PLC controller; it can acquire the output voltage of the DC power supply 6, i.e., the first negative high voltage V. 负1 It can also issue control commands to the controllable high-voltage power supply 7 to adjust the second negative high voltage V.负2 ;

[0054] The embodiment of the present application also provides a control method of the plasma generating device, comprising the following steps:

[0055] In step S10, the ignition voltage V1 of the direct current power supply 6 and the preset voltage and V 和 The initial voltage value HV1 of the second negative high voltage V 负2 output by the controllable high voltage power supply 7 is set; that is, HV1=V 和 -V1;

[0056] In the embodiment, the ignition voltage V1 of the direct current power supply 6 is 850V, the preset voltage and V 和 is 2000V, and the initial voltage value HV1 of the second negative high voltage V 负2 is 1150V;

[0057] In step S20, the process gas is introduced into the process cavity 1, and at the beginning of the ignition stage, the first negative high voltage V 负1 applied to the target back plate 4 by the direct current power supply 6 is the ignition voltage V1, and the second negative high voltage V 负2 applied to the high voltage electrode plate 8 by the controllable high voltage power supply 7 is the initial voltage value HV1; V1+HV1=V 和 ;

[0058] The ignition stage is very short, about several hundred ms, and then the magnetron sputtering stage is entered; after the process gas glows and discharges, the first negative high voltage V 负1 output by the direct current power supply 6 rapidly decreases from the ignition voltage V1 to the sputtering voltage V2; at this time, the second negative high voltage V 负2 needs to be adjusted immediately;

[0059] In step S30, the first negative high voltage V 负1 output by the direct current power supply 6 is monitored, and when the first negative high voltage V 负1 decreases to the sputtering voltage V2 and remains for a set judgment duration, the second negative high voltage V 负2 is adjusted to the working voltage value HV2; V2+HV2=V 和 ; the magnetron sputtering stage is entered; the magnetron sputtering process is performed for a set magnetron sputtering duration;

[0060] In a specific embodiment, when the sputtering voltage V2 is 600V, the adjusted second negative high voltage V 负2 is 1400V, that is, HV2 is 1400V;

[0061] Further, the ignition voltage V1 is 650V-850V;

[0062] Furthermore, the sputtering voltage V2 is 200V to 650V;

[0063] Furthermore, the set judgment duration is 100ms to 200ms;

[0064] The time from the ignition stage to entering the stable magnetron sputtering stage is very short, typically less than 1 second in this embodiment; in this embodiment, the first negative high voltage V during the ignition stage and the magnetron sputtering stage is... 负1 With the second negative high voltage V 负2 voltage and V 和 Maintaining consistency ensures a stable high-voltage electric field on the target surface. On one hand, the higher voltage generates an electric field that facilitates glow discharge of the process gas, promoting ignition and plasma formation, thus ensuring smooth magnetron sputtering. On the other hand, the applied high voltage (second negative high voltage V) ensures a stable high-voltage electric field on the target surface. 负2 The electric field on the target surface is significantly enhanced. Under the action of the enhanced high-voltage electric field, the argon ions in the plasma are affected by the electric field of the cathode sheath (the first negative high voltage V). 负1 The generated) and the applied high-voltage electric field (second negative high voltage V) 负2 The dual acceleration generated by the sputtering atoms, along with the large kinetic energy, bombards the target material. The angle between the ejection direction of the sputtered atoms and the normal direction of the target surface is small, and the distribution of sputtered atoms tends to be a vertically offset elliptical surface, so that more sputtered atoms fall on the substrate, improving the atom utilization rate. In addition, the vertical orientation of the sputtered atoms is stronger, which has a significant effect on improving the step coverage of the hole filling process.

[0065] Example 1

[0066] The SJI-SEMI Depommerits P188+ Pro PVD system was used, employing a 99.999% pure titanium target with a diameter of 320–321 mm and a target-stage distance of 90 mm. First, the wafer was transferred to the DC reactive magnetron sputtering chamber, with the stage substrate temperature set at 200°C and the chamber vacuum maintained at 5.0 × 10⁻⁶. -8 Torr below; using 3000W sputtering power, pre-sputtering the target for 10 minutes;

[0067] Then, set the second negative high voltage V of the controllable high voltage power supply output. 负2 The initial voltage value HV1 is 1150V; a DC power supply with an ignition voltage V1 of 850V is used, and the sum of V1 and HV1 is 2000V. Then, argon gas at 25 sccm is introduced into the process chamber, and the chamber pressure is 1.3 mToor; the sputtering power of the DC power supply is 3000W; after successful ignition, the sputtering voltage V2 of the DC power supply is obtained through the controller, and the second negative high voltage V output of the controllable high voltage power supply is adjusted. 负2The working voltage value HV2 is 2000V; the sum of V2 and HV2 is 2000V; the total magnetron sputtering time is 120s, and the metal titanium film is obtained, and the film thickness is about 1500A measured by a scanning electron microscope;

[0068] In addition, without a controllable high-voltage power supply, only a direct-current power supply is used for magnetron sputtering, and the film thickness is about 1200A measured by a scanning electron microscope; thus, it can be known that the argon ions in the plasma with large kinetic energy bombard the target under the action of the applied high-voltage electric field, the angle between the sputtered atom direction and the normal direction of the target surface is small, and the sputtered atoms fall more on the substrate; finally, the atomic utilization or deposition rate is increased by about 25%.

[0069] Example Two

[0070] When sputtering metal films with the same thickness, the step coverage of the sputtering under the action of the applied high-voltage electric field is compared with the step coverage of the sputtering without the action of the applied high-voltage electric field.

[0071] The film measurement points are as shown in FIG. 2, that is, Figure 4 Figure 4 The five short line segments in the middle of FIG. 2 represent the film measurement points; the step coverage is defined as the ratio of the film thickness of the sidewall or the bottom of the micro-hole to the film thickness at the top plane of the substrate; the cross-sectional film thickness distribution in the micro-hole of the substrate is observed under a scanning electron microscope; the step coverage of the sputtering under the action of the applied high-voltage electric field is shown in FIG. 3, and the step coverage of the ordinary sputtering, that is, the sputtering without the action of the applied high-voltage electric field, is shown in FIG. 4; the calculated step coverage is shown in Table 1; the step coverage of the sidewall can be averaged. Figure 5 Figure 6

[0072]

[0073] Table 1

[0074] When the sputtering is under the action of the applied high-voltage electric field, the argon ions with large kinetic energy bombard the target, the sputtered atom direction distribution tends to be an elliptical surface with longitudinal deviation, the vertical directionality of the sputtered atoms is stronger, and the step coverage for the hole filling process is obviously improved.

[0075] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present application and not to limit the present application. Although the present application is described in detail with reference to the embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the spirit and scope of the technical solutions of the present application, and they should be covered in the scope of the claims of the present application.​​​

Claims

1. A plasma generating device, characterized in that, include: Process cavity (1); A stage (2) is used to support a substrate (3); the stage (2) is installed at the bottom of the process chamber (1); The target back plate (4) is used to support the target (5); the target back plate (4) is installed on the top of the process cavity (1) and is positioned opposite to the stage (2); A DC power supply (6) is connected to the negative terminal of the target backplate (4) for outputting and applying a first negative high voltage V to the target backplate (4). 负1 The positive terminal of the DC power supply (6) is grounded; A controllable high-voltage power supply (7) is provided, the negative terminal of which is connected to a high-voltage electrode plate (8) for outputting and applying a second negative high voltage V to the high-voltage electrode plate (8). 负2 The high-voltage electrode plate (8) is parallel to the target surface of the target material (5) and insulated from the target back plate (4); the first negative high voltage V 负1 Second negative high voltage V 负2 Used to generate a high-voltage electric field on the surface of the target material (5); the positive terminal of the controllable high-voltage power supply (7) is grounded; Controller (9), used to determine the first negative high voltage V 负1 The voltage change controllable high voltage power supply (7) automatically adjusts the second negative high voltage V 负2 ; This enables the first negative high voltage V during the ignition stage and magnetron sputtering stage. 负1 With the second negative high voltage V 负2 voltage and V 和 same; The high-voltage electrode plate (8) is installed on the side of the target back plate (4) that is away from the target (5) and is insulated from the target back plate (4) by a gap or an insulating layer.

2. The plasma generating apparatus as described in claim 1, characterized in that, The first negative high voltage V 负1 With the second negative high voltage V 负2 voltage and V 和 The voltage range is 1800V to 2200V.

3. The plasma generating apparatus as described in claim 1, characterized in that, The platform (2) is grounded.

4. The plasma generating apparatus as described in claim 1, characterized in that, The controller (9) is a PLC controller; it is used to collect the output voltage of the DC power supply (6), i.e., the first negative high voltage V. 负1 And used to issue control commands to the controllable high voltage power supply (7) to regulate the second negative high voltage V. 负2 .

5. A control method for a plasma generator, applicable to the plasma generator as described in any one of claims 1 to 4, comprising the following steps: Step S10, based on the ignition voltage V1 of the DC power supply (6) and the preset voltage and V... 和 The second negative high voltage V output by the controllable high voltage power supply (7) is set. 负2 The initial voltage value is HV1; that is, HV1 = V. 和 -V1; Step S20: Process gas is introduced into the process chamber (1). At the start of the ignition stage, a first negative high voltage V is applied to the target backplate (4) through the DC power supply (6). 负1 The ignition voltage V1 is the second negative high voltage V applied to the high-voltage electrode plate (8) by the controllable high-voltage power supply (7). 负2 The initial voltage value is HV1; V1 + HV1 = V 和 ; Step S30: Monitor the first negative high voltage V output by the DC power supply (6). 负1 When the first negative high voltage V 负1 When the voltage drops to sputtering voltage V2 and remains at that level for a set judgment time, adjust the second negative high voltage V. 负2 The operating voltage value is HV2; V2 + HV2 = V 和 Enter the magnetron sputtering stage; perform the magnetron sputtering process according to the set magnetron sputtering duration.

6. The control method for the plasma generator as described in claim 5, characterized in that, The ignition voltage V1 is 650V to 850V.

7. The control method for the plasma generator as described in claim 5, characterized in that, The sputtering voltage V2 is 200V to 650V.

8. The control method for the plasma generator as described in claim 5, characterized in that, The set judgment time is 100ms to 200ms.

Images