Chemical vapor deposition tool for preventing or suppressing arcing

Abstract

To provide a Chemical Vapor Deposition (CVD) tool that suppresses or altogether eliminates arcing between a substrate pedestal and substrate.SOLUTION: The CVD tool includes a Direct Current (DC) bias control system arranged to maintain a substrate pedestal 16 provided in a processing chamber at a same or substantially the same DC bias voltage as developed by a plasma in the processing chamber. By maintaining the substrate pedestal 16 and the substrate 18 having the same potential as the plasma at the same or substantially the same voltage potential, arcing is suppressed or altogether eliminated.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of priority to U.S. Application No. 16 / 057,383, filed Aug. 7, 2018, which is incorporated by reference herein for all purposes. [Background technology]

[0002] Plasma-enhanced chemical vapor deposition (PECVD) tools are used to form thin films on substrates. CVD tools typically include a process chamber, a substrate pedestal for supporting the substrate within the process chamber, and a showerhead. During operation, the showerhead distributes reactive gases above the surface of the substrate being processed. To generate the plasma, a radio frequency (RF) potential is applied between two electrodes that are typically provided on the showerhead and / or substrate pedestal. The energized electrons dissociate or dissociate (e.g., "fracture") reactive gases from the plasma, generating chemically reactive radicals. As these radicals react, they deposit on the substrate to form a thin film.

[0003] Arcing is a well-known electrical phenomenon caused by the dielectric breakdown of a normally non-conductive gas that is provided in the gap between two surfaces at different potentials. When arcing occurs, the non-conductive gas breaks down and a strong electric current or discharge jumps across the gap between the two surfaces for a short period of time.

[0004] Arcing is a major problem for PECVD tools. Typically, an electrically resistive material (e.g., a dielectric film) is provided between the substrate and the pedestal. During operation of the tool, the plasma in the processing chamber and the substrate inherently generate a direct current (DC) bias voltage when an RF potential is applied. As a result, a non-zero DC voltage exists between the substrate and the substrate pedestal due to the resistive material.

[0005] If the DC voltage difference exceeds a certain threshold, dielectric breakdown can occur in the gas between the substrate and the substrate pedestal. As thin films form on the substrate, the magnitude of the DC bias voltage tends to increase. As a result, the likelihood of dielectric breakdown increases significantly. In certain types of substrates (such as semiconductor wafers), a sudden burst of discharge or arcing can destroy delicate electrical circuits. Destruction of electrical circuits on semiconductor wafers can reduce yields, resulting in significant production losses and increased costs.

[0006] Thus, there is a need for a CVD tool that reduces or completely eliminates arcing between the substrate and the substrate pedestal. Summary of the Invention

[0007] A chemical vapor deposition (CVD) tool is disclosed that reduces or completely eliminates arcing between a substrate pedestal and a substrate. The tool includes a process chamber, a substrate pedestal for supporting a substrate within the process chamber, and a showerhead disposed within the process chamber. The showerhead is arranged to dispense a gas that is transformed into a plasma that generates a DC bias voltage in response to a radio frequency (RF) potential. The tool also includes a direct current (DC) bias control system arranged to maintain the substrate pedestal at a DC bias voltage that is the same or approximately the same as the DC bias voltage generated by the plasma.

[0008] In a non-exclusive embodiment, the DC bias control system measures the DC current between the plasma and the substrate pedestal and adjusts the DC bias voltage on the substrate pedestal by keeping the DC current constant when the resistance between ground and the substrate is held constant.

[0009] In another non-exclusive embodiment, the DC bias control system is further configured to measure the DC current at the start of the substrate processing and then adjust the DC bias voltage to maintain the measured DC current for the remainder of the substrate processing to compensate for resistance drift.

[0010] In various non-exclusive embodiments, the current path between the plasma and the electrode includes one or more of: (a) a substrate supported on a substrate pedestal, (b) a thin film formed on the substrate, (c) the substrate pedestal, and (d) a power supply connected to the substrate pedestal. The resistance is comprised of one or more of: (f) the substrate, (g) a thin film formed on the substrate, (h) the substrate pedestal, and (i) a resistive component of a power supply system connected to the substrate pedestal. [Brief description of the drawings]

[0011] The present application and its advantages will be better understood with reference to the following description taken in conjunction with the accompanying drawings.

[0012] [Figure 1] 1 is a block diagram of a chemical vapor deposition (CVD) chamber in accordance with a non-exclusive embodiment of the present invention.

[0013] [Figure 2A] FIG. 2 is a top view of a substrate pedestal according to a non-exclusive embodiment of the present invention. [Figure 2B] 2A and 2B are cross-sectional views of a substrate pedestal according to a non-exclusive embodiment of the present invention.

[0014] [Diagram 3] 1 illustrates how arcing may be reduced or prevented according to non-exclusive embodiments of the present invention.

[0015] [Figure 4] A plot showing the unpredictability of the DC bias voltage generated by the plasma in the tool over time.

[0016] [Diagram 5] FIG. 2 is a block diagram illustrating an active DC bias control system for a substrate pedestal in accordance with the present invention.

[0017] [Figure 6] FIG. 1 is a diagram of a CVD chamber having multiple substrate pedestals according to a non-exclusive embodiment of the present invention.

[0018] [Figure 7] FIG. 2 is a block diagram of a system controller used to control a CVD tool in accordance with a non-exclusive embodiment of the present invention.

[0019] In the drawings, like reference numbers may be used to indicate like structural elements. It should also be understood that the depictions in the figures are diagrammatic representations and are not necessarily drawn to scale. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The present application will now be described in detail with reference to several non-exclusive embodiments illustrated in the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. However, it will be apparent to one skilled in the art that the present disclosure may be practiced without some or all of these specific details. In other instances, well-known process steps and / or structures have not been described in detail in order to not unnecessarily obscure the present disclosure.

[0021] 1, a block diagram of a chemical vapor deposition (CVD) tool 10 is shown. The tool 10 includes a process chamber 12, a showerhead 14, a substrate pedestal 16 for positioning a substrate 18 to be processed, a radio frequency (RF) source generator 20, a gas source 22, a system controller 24, and an ESC power supply 26 connected to the substrate pedestal 16 and a direct current (DC) bias control system 28. In various embodiments, the CVD tool may be a plasma enhanced chemical vapor deposition (PECVD) tool, a plasma enhanced atomic layer deposition (PEALD) tool, or other type of CVD tool that uses plasma.

[0022] During operation, reactive gases are supplied to the process chamber 12 from a gas source 22 through the showerhead 14. The gases are distributed inside the chamber 12 through one or more plenums (not shown) within the showerhead 14 to a region within the chamber 12 above the surface of the substrate 18. An RF potential generated by an RF generator 20 is applied to one or more electrodes (not shown) above the substrate pedestal 16. The RF potential ionizes the gases, generating a plasma inside the process chamber 12. Electrically energized electrons in the plasma dissociate (i.e., "split") from the reactive gases, generating chemically reactive radicals. As these radicals react, they deposit on the substrate 18 to form a thin film.

[0023] In various embodiments, the RF generator 20 may be a single RF generator or multiple RF generators capable of generating high, medium, and / or low frequencies. For example, in the case of high frequencies, the RF generator 20 may generate frequencies in the range of 2-100 MHz, preferably 13.56 MHz or 27 MHz. When low frequencies are generated, the range is 50 KHz to 2 MHz, preferably 350 KHz to 600 KHz. In another embodiment, the RF source may be connected to RF electrodes provided on the showerhead 14 rather than the substrate pedestal 16, or on both the showerhead 14 and the substrate pedestal 16.

[0024] A system controller 24 is generally used to control the overall operation of CVD tool 10 and to regulate process conditions during deposition, post-deposition, and / or other processing operations.

[0025] In a non-exclusive embodiment, the substrate pedestal 16 is an electrostatic chuck (ESC) type substrate pedestal. An ESC power supply 26 is provided to supply a counter voltage to electrodes (not shown in FIG. 1 ) embedded in the clamping surface of the substrate pedestal 16 sufficient to generate the electrostatic force necessary to clamp the substrate 18.

[0026] When an RF potential is applied to the process chamber 12 along with the reactive gases, a plasma is generated. In response to the RF potential, the plasma generates a DC bias, typically in the range of 0 to -100 volts. When the substrate 18 is exposed to the plasma, the substrate generates the same or nearly the same DC bias voltage as the plasma. Typically, the substrate pedestal 16 is often maintained at a different voltage. The voltage difference between the substrate pedestal 16 and the substrate 18 is susceptible to arcing.

[0027] A DC bias control system 28 is provided to maintain the substrate pedestal 16 at the same or nearly the same DC bias voltage as that generated by the plasma and substrate 18. Thus, the voltage difference between the substrate pedestal 16 and the substrate 18 is zero or close to zero. As a result, arcing between the substrate pedestal 16 and the substrate 18 is suppressed or completely eliminated.

[0028] 2A and 2B, there are shown top and cross-sectional views of a non-exclusive embodiment of the substrate pedestal 16. In this particular embodiment, the body portion 29 of the substrate pedestal 16 is made of a non-conductive ceramic material, such as aluminum nitride. An electrostatic chuck (ESC) surface 30 for clamping the substrate 18 is embedded in the substrate pedestal 16.

[0029] As shown in detail in Figure 2A, the electrode 30 is embedded in the substrate pedestal 16 and comprises a pair of "D-shaped" ESC clamp electrodes 32A and 32B. During clamping, the two electrodes 32A and 32B are provided with voltages of opposite polarity (e.g., + / - 500 volts), respectively. The resulting electrostatic force clamps the substrate 18 to the clamping surface 30 of the substrate pedestal 16.

[0030] Substrate pedestal 16 also includes an RF electrode 34 embedded in, around and through its upper surface 30. Electrodes 32A, 32B, and 34 are connected to RF source 20 and are arranged to provide the necessary RF potential to ionize reactant gases supplied to process chamber 12 to generate a plasma. As shown in detail in FIG. 2B, a cross section shows ESC clamp electrodes 32A and 32B, with RF electrodes 32A, 32B, and 34 embedded in body portion 29 of substrate pedestal 16.

[0031] To reduce or prevent arcing, the DC bias control system 26 provides bias voltages to the left and right electrodes 32A and 32B. For example, if an ESC clamp voltage of + / - 500 volts is applied to the electrodes 32A and 32B, respectively, if the plasma inside the process chamber 12 generates a bias of -10 volts, then a bias voltage V of the same or similar magnitude may be applied. DC is applied to electrodes 32A and 32B. That is, electrode 32A is maintained at 490 volts (500-10) and electrode 32B is maintained at -510 volts (-500-10). In another non-exclusive embodiment, the same bias voltage V DC (eg, −10 V) may also be applied to electrode 34 .

[0032] Since the voltage difference between the two electrodes 32A and 32B remains the same, the bias voltage V DC does not affect the ESC clamping force, but the voltage difference between the board base 16 and the board 18 is reduced to zero or very close to zero, reducing or completely eliminating arcing.

[0033] 3, a diagram illustrating how arcing may be prevented or suppressed is shown. A showerhead 14 introduces one or more reactive gases into the process chamber 12. An RF potential provided by an electrode 34 embedded in the substrate pedestal 16 results in ionization of the reactive gases, creating a plasma.

[0034] In this particular example, a thin conductive film 36, such as a metal layer or a conductive carbon layer, is deposited over a dielectric layer 38. During deposition, layers or films 36 and 38 are formed over both the top surface of substrate 18 and the peripheral portions of substrate pedestal 16. As conductive layer 36 is formed, a negative surface charge, indicated by the letter "e," builds up on the surface of substrate 18.

[0035] The DC bias voltage V is the same as the DC bias voltage generated by the plasma. DC " is applied to electrodes 32A and 32B (not shown) on substrate pedestal 16. Because the voltage difference between substrate 18 and substrate pedestal 16 is the same or nearly the same, the surface charge "e" on substrate 18 is not attracted to substrate pedestal 16. As a result, arcing is suppressed or completely eliminated, especially in the area indicated by ellipse 40 which tends to be the most susceptible locations for arcing.

[0036] During processing of a substrate 18 in the processing chamber 12, the DC bias voltage generated by the plasma tends to change unpredictably over time. For example, during deposition of a conductive (e.g., carbon) layer on a semiconductor wafer, the plasma "sees" the conductive layer as an electrode. Over an extended period of deposition, the layer tends to grow wider and thicker over time on both the wafer and the peripheral top surface of the substrate pedestal 16. As a result of this growth, the plasma tends to spread, changing the DC bias voltage generated by the plasma. However, the DC bias voltage generated by the plasma is typically not linear. As a result, it is very difficult to predict how the generated DC bias voltage of the plasma will change over time.

[0037] 4 is an example plot illustrating the unpredictability of the DC bias voltage generated by a plasma in a CVD tool during deposition. The plot shows that the DC bias voltage tends to decrease over time (e.g., from about −5.0 volts to about −20.0 volts). However, this decrease is not linear. Thus, the plot shows that the DC bias voltage tends to decrease over time (e.g., from about −5.0 volts to about −20.0 volts). DC1 illustrates that when applied to electrodes 32A, 32B, and / or 34, a voltage difference may sometimes exist between the substrate 18 and the substrate pedestal 16 as the DC bias voltage of the plasma is changed. Whenever a voltage difference exists, the substrate 18 is susceptible to arcing. The plot in the figure is provided for illustrative purposes only and to illustrate the non-linearity of the DC bias voltage decrease. It should be understood that in an actual embodiment the plot will vary significantly, but will typically illustrate a decrease in DC bias voltage.

[0038] When a non-zero voltage difference exists, a DC current flows between the plasma and the grounded electrode due to the finite resistance between them. The current path between the plasma and the electrode includes one or more of: (a) a substrate 18 supported by a substrate pedestal 16, (b) a thin film formed on the substrate 18, (c) electrodes 32A, 32B, and 34 on the substrate pedestal 16, (d) a power supply 26 connected to the substrate pedestal 16, and (e) the substrate pedestal 16.

[0039] The resistor is composed of one or more of: (a) substrate 18, (b) a thin film formed on substrate 18, (c) electrodes 32A, 32B, and 34 provided on substrate base 16, which are provided in the above-mentioned current path, and power supply 26 connected to substrate base 16.

[0040] As conditions inside the process chamber 12 change, the DC bias voltage of the plasma changes as described above. When the resistance is fixed, a change in the measured current will indicate a change in the DC bias voltage of the plasma. As a result, ΔV DC The change in value of is proportional to the change in the DC bias voltage generated by the plasma over time. DC By measuring and applying to electrodes 32A, 32B, and / or 34, the DC bias voltage on the substrate pedestal can substantially track the DC bias generated by the plasma and substrate as process conditions change, i.e., the voltage difference between the substrate pedestal 16 and the substrate 18 remains at or near zero as conditions in the process chamber 12 change.

[0041] Referring to Figure 5, a block diagram of DC bias control system 28 is shown. System 28 includes a current measuring device 50 and ESC power supply 26. Current measuring device 50 measures a sample of the current between the plasma and the ground electrode. DC power supply 52 adjusts the bias voltage applied to electrode 32A, electrode 32B, and / or electrode 34 via ESC power supply 26 to maintain a constant current. By maintaining a constant current, the voltage difference between substrate 18 and the substrate pedestal remains at or near zero.

[0042] In various embodiments, the predetermined sampling rate for measuring the current samples may vary widely. For example, the sampling rate may range anywhere from 1 microsecond to 10 seconds. In general, the higher the sampling rate, the more accurately the bias voltage may be adjusted to track changes in the actual DC bias generated by the plasma. As a result, a higher level of arc suppression is likely to be achieved.

[0043] Based on the above, there are several ways to suppress or completely prevent arcing. For example: By maintaining a constant voltage between the substrate 18 and the substrate pedestal 16 (at or near zero volts), arcing can be eliminated or greatly limited. However, as the plasma DC bias voltage changes over time, the voltage difference between the pedestal and the substrate can increase. As a result, the likelihood of arcing will also increase. A feedback loop may be used to measure the sample current and control the DC bias supply 52 to adjust the bias voltage applied to electrodes 32A, 32B, and / or 34 via the ESC power supply 26, thereby maintaining the measured current at a predefined constant value. This method works even if the plasma DC bias voltage changes over time, but is sensitive to changes in resistance. For example, if the resistance changes from substrate to substrate or as layers are added to the substrate, the likelihood of arcing may increase. · The current is measured once and used as the set point for each substrate. The feedback loop described above is then used to adjust the bias voltage applied to electrodes 32A, 32B and / or 34. For the next substrate the set point is measured again and the bias voltage is adjusted accordingly. To compensate for drift in the system, the set point is updated by measuring the current for each substrate. This approach significantly reduces the possibility of arcing even as the plasma DC bias changes over time and / or chamber 12 conditions change.

[0044] The ability to measure the DC current and adjust and apply a DC bias voltage to electrodes 32A, 32B, and / or 34 of the substrate pedestal 16 provides a number of advantages. First, the voltage difference between the substrate pedestal 16 and the substrate 18 remains at or near zero while the substrate 18 is processed in the chamber 12. Second, when one substrate 18 is replaced with another substrate for processing, the current is measured and the DC bias voltage is adjusted to match the current conditions inside the processing chamber 12. Third, the DC bias control system 28 has the ability to adjust the DC bias voltage independent of the tool 10 and / or processing chamber 12. Thus, changing from one CVD tool 10 to the next, or from one processing chamber 12 to the next, does not matter because the DC bias control system 28 has the ability to adjust the DC bias voltage regardless of how the conditions change from one tool to the next.

[0045] 6, a diagram of a CVD chamber 12 having multiple substrate pedestals 16 is shown. In this particular embodiment, the CVD tool 10 is referred to as a "quad" tool because the process chamber 12 has four substrate pedestals 16A-16D. Thus, the DC bias control system 28 controls four bias voltages ΔV DC(+ / -), each calculated respectively for the four substrate pedestals 16A-16D as described above. It should be understood that the illustrated quad tool 10 is merely exemplary and should not be construed as limiting. The system for suppressing or eliminating arcing may be used in CVD tools having any number of substrate pedestals.

[0046] FIG. 7 is a high-level block diagram illustrating the system controller 24. The computer system 24 may have many physical forms, ranging from integrated circuits to printed circuit boards, small handheld devices, personal computers, servers, and supercomputers, any of which may have one or more processors. The computer system 24 may further include an electronic display device 804 (for displaying images, text, and other data), a non-transitory main memory 806 (e.g., random access memory (RAM)), a storage device 808 (e.g., a hard disk drive), a removable storage device 810 (e.g., an optical disk drive), a user interface device 812 (e.g., a keyboard, touch screen, keypad, mouse, or other pointing device), and a communication interface 814 (e.g., a wireless network interface). The communication interface 814 allows software and data to be transferred between the system controller 24 and external devices via a link. The system controller 24 may also include a communication infrastructure 816 (e.g., a communication bus, crossover bar, or network) to which the aforementioned devices / modules are connected.

[0047] The term "non-transitory computer-readable medium" is used generally to refer to main memory, secondary memory, removable memory, and storage devices (including hard disks, flash memory, disk drive memory, CD-ROMs, and other forms of persistent memory) and should not be construed to include transitory objects such as carrier waves or carrier signals.

[0048] In certain embodiments, a system controller 24, which runs or executes system software or system code, controls all or at least most of the operations of the tool 10 (e.g., operations controlling the timing of processing operations, the frequency and power of operation of the RF generator 20, the pressure inside the processing chamber 12, the flow rates, concentrations, and temperatures of gases to the processing chamber 12 and their relative mixture, and the temperature of the substrate 18 supported by the substrate holder 16).

[0049] Information transferred through communications interface 814 may be signals in the form of electronic, electromagnetic, optical, etc., or other signals that may be received by communications interface 814 over a communications link that transmits signals, and may be implemented using wires or cables, fiber optics, telephone lines, cellular phone links, radio frequency links, and / or other communications circuitry. Using such communications interfaces, one or more processors 802 are expected to receive information from a network or output information to a network. Additionally, method embodiments may be performed solely by a processor in cooperation with a remote processor that shares some of the processing, or may be performed over a network, such as the Internet.

[0050] It should be understood that the embodiments described herein are merely exemplary and should not be construed as limiting in any way. In general, the present application is intended to include showerheads having at least two sets of holes defining two helical patterns and two plenums for the two patterns.

[0051] Although only a few embodiments have been described in detail, it should be understood that the present application may be embodied in many other forms without departing from the spirit or scope of the disclosure set forth herein For example, the substrate may be a semiconductor wafer, a discrete semiconductor device, a flat panel display, or other type of workpiece.

[0052] Thus, the present embodiments should not be considered as illustrative and restrictive and should not be limited to the details described herein, but may be modified within the scope of the appended claims and their equivalents.

Claims

1. 1. A chemical vapor deposition (CVD) tool comprising: a processing chamber; a substrate pedestal for supporting a substrate within the processing chamber; a showerhead disposed within the processing chamber and configured to dispense a gas that is transformed into a plasma within the processing chamber in response to a radio frequency (RF) potential, the plasma generating a DC bias voltage; a direct current (DC) bias control system configured to maintain the substrate pedestal at a DC bias voltage that is the same as, or approximately the same as, the DC bias voltage generated by the plasma in the processing chamber; A CVD tool comprising:

2. 2. The CVD tool of claim 1, The CVD tool, wherein the DC bias control system is further configured to adjust the DC bias voltage of the substrate pedestal as the DC bias voltage generated by the plasma changes.

3. 3. The CVD tool of claim 2, The DC bias control system includes: measuring a current along a current path between the plasma and a ground electrode; adjusting the DC bias voltage of the substrate pedestal to maintain the measured current at zero or a constant predetermined value; adjusting the DC bias voltage of the substrate pedestal.

4. 4. The CVD tool of claim 3, The CVD tool, wherein the DC bias control system is further configured to use the measured current as a set point at the start of processing of the substrate and to adjust the DC bias voltage of the substrate pedestal during subsequent processing of the substrate.

5. 5. The CVD tool of claim 4, The current path between the plasma and the electrode is (a) the substrate supported by the substrate pedestal; (b) any thin film formed on the substrate; (c) an electrode provided on the substrate base; (d) a power supply connected to the substrate pedestal; and (e) the substrate base; 1. A CVD tool comprising:

6. 5. The CVD tool of claim 4, The resistance value is (a) the substrate, (b) any thin film formed on the substrate; (c) an electrode provided on the substrate base; and (d) a power source connected to the substrate pedestal; The CVD tool is calculated from the resistance of one or more of the following:

7. 2. The CVD tool of claim 1, 1. The CVD tool, wherein the substrate pedestal is an electrostatic chuck (ESC) type substrate pedestal comprising a first electrode and a second electrode maintained at opposing clamping potentials, the opposing clamping potentials being adjusted to the same or approximately the same DC bias voltage as that generated by the plasma in the processing chamber.

8. 2. The CVD tool of claim 1, The CVD tool, wherein the substrate pedestal comprises an RF electrode for providing the RF potential to the plasma in the processing chamber.

9. 9. The CVD tool of claim 8, A CVD tool, wherein the RF electrode is regulated with a DC bias voltage that is the same or approximately the same as that generated by the plasma in the processing chamber.

10. 2. The CVD tool of claim 1, The DC bias control system includes: a current measuring device for measuring a current between the plasma and an electrode; a control power supply for controlling a DC bias voltage to an electrode provided on the substrate base in response to the current measuring device; A CVD tool comprising:

11. 8. The CVD tool of claim 7, A CVD tool, wherein the electrodes provided on the substrate pedestal are positive and negative electrodes used to electrostatically clamp the substrate to the substrate pedestal.

12. 2. The CVD tool of claim 1, The CVD tool, wherein the processing chamber further comprises two or more substrate pedestals.

13. 15. The CVD tool of claim 14, The CVD tool, wherein the DC bias control system is further configured to maintain the two or more substrate pedestals at the same or approximately the same DC bias voltage as the plasma in the processing chamber.

14. 2. The CVD tool of claim 1, By approximately the same, it is meant that the DC bias voltage generated by the plasma and the substrate pedestal have a voltage difference of 10.0 volts or less.

15. 2. The CVD tool of claim 1, By approximately the same, it is meant that the DC bias voltage generated by the plasma and the substrate pedestal have a voltage difference of 0.1 volts or less.

16. 1. A chemical vapor deposition (CVD) tool comprising: A CVD tool comprising: a direct current (DC) bias control system arranged to maintain a substrate pedestal disposed in a processing chamber at a DC bias voltage that is the same or approximately the same as that generated by a plasma within said processing chamber.

17. 17. The CVD tool of claim 16, A CVD tool, wherein the substrate pedestal comprises electrostatic clamping (ESC) electrodes of opposite polarity for clamping a substrate to the substrate pedestal, and the DC bias voltage is applied to the ESC electrodes of opposite polarity.

18. 17. The CVD tool of claim 16, The DC bias control system adjusts the DC bias voltage as the DC bias voltage generated by the plasma changes within the process chamber.

19. 17. The CVD tool of claim 16, The DC bias control system includes: a current measuring device for measuring a current between the plasma and an electrode; A CVD tool comprising: an ESC power supply for applying a DC bias offset to an electrode disposed on the substrate pedestal, the DC bias offset being balanced against the measured current.

20. 20. The CVD tool of claim 19, The current path between the plasma and the electrode is (a) a substrate supported by the substrate pedestal; (b) any thin film formed on the substrate; (c) an electrode provided on the substrate base; (d) a power supply connected to the substrate pedestal; and (e) the substrate base; 1. A CVD tool comprising:

21. 20. The CVD tool of claim 19, The resistance value is (a) a substrate; (b) any thin film formed on the substrate; (c) an electrode provided on the substrate base; and (d) a power source connected to the substrate pedestal; The CVD tool is calculated from the resistance of one or more of the following:

22. 22. The CVD tool of claim 21, By approximately the same, it is meant that the DC bias voltage generated by the plasma and the substrate pedestal have a voltage difference of 10.0 volts or less.

23. 22. The CVD tool of claim 21, By approximately the same, it is meant that the DC bias voltage generated by the plasma and the substrate pedestal have a voltage difference of 0.1 volts or less.

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