Waveform shape factor for pulsed PVD power

Abstract

To provide apparatuses and methods to detect / increase / ensure pulsed PVD chamber deposition film performances if power / voltage / current waveforms change.SOLUTION: Power supplies, waveform function generators and methods for controlling a plasma process are described. The power supplies or waveform function generators include a component for executing the method, in which a waveform shape change index is determined during a plasma process, and the waveform shape change index is evaluated for compliance with a predetermined tolerance.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE Embodiments of the present disclosure relate generally to physical vapor deposition (PVD) chambers and methods. In particular, the disclosed embodiments relate to PVD chambers and deposition methods that use pulsed PVD involving controlled power waveforms. [Background technology]

[0002] Current physical vapor deposition (PVD) process chambers are susceptible to degradation of uniformity and repeatability when power regulation changes. Power regulation is typically used to drive pulsed PVD plasma chambers with voltage / current waveforms of a certain shape. Such voltage / current waveforms are designed to achieve certain film characteristics or film attributes.

[0003] As shown in FIG. 1, the same average power, voltage or current can be delivered as pulses with different waveform shapes. Different waveform shapes correspond to different plasma attributes in the PVD chamber. This power / voltage / current waveform shape drifts or changes dramatically due to chamber load conditions, plasma instabilities, chamber plasma arcing or load changes, and sometimes due to power supply malfunctions and power delivery output cable hardware malfunctions. These waveform shape changes change the chamber plasma conditions and therefore affect the thin film attributes. Summary of the Invention [Problem to be solved by the invention]

[0004] Therefore, what is needed is an apparatus and method for detecting / enhancing / ensuring pulsed PVD chamber deposition film performance when power / voltage / current waveforms are varied. [Means for solving the problem]

[0005] One or more embodiments of the present disclosure are directed to a method of controlling a plasma process that includes determining a waveform shape change index during a deposition process, determining whether the waveform shape index is within a predetermined tolerance, and determining a subsequent operation of the plasma process.

[0006] An additional embodiment of the present disclosure is directed to a method for matching a plasma process to a reference plasma process, the method comprising:

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[0007] A further embodiment of the present disclosure is directed to a power supply with a self-diagnostic feature that indicates malfunctions. The self-diagnostic feature includes a waveform shape factor.

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[0008] So that the above-listed features of the present disclosure may be understood in detail, the disclosure briefly outlined above may be more particularly described by reference to embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings illustrate only typical embodiments of the present disclosure and therefore should not be considered as limiting the scope of the present disclosure, since the present disclosure may embrace other embodiments that are equally effective. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 illustrates a waveform shape according to one or more embodiments of the present disclosure. [Figure 2A] FIG. 1 illustrates a waveform shape according to one or more embodiments of the present disclosure. [Figure 2B] FIG. 1 illustrates a waveform shape according to one or more embodiments of the present disclosure. [Figure 2C] FIG. 1 illustrates a waveform shape according to one or more embodiments of the present disclosure. [Figure 2D] FIG. 1 illustrates a waveform shape according to one or more embodiments of the present disclosure. [Diagram 3] FIG. 1 illustrates a method according to one or more embodiments of the present disclosure. [Figure 4] FIG. 1 illustrates a method according to one or more embodiments of the present disclosure. [Diagram 5] FIG. 1 illustrates a power supply in accordance with one or more embodiments of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Before proceeding to describe some exemplary embodiments of the present disclosure, it should be understood that the present disclosure is not limited to the details of structure or process steps set forth in the following description, as the present disclosure may include other embodiments and may be practiced or carried out in various ways.

[0011] As used herein and in the appended claims, the term "substrate" refers to a surface or portion of a surface on which a process is performed. Furthermore, unless otherwise clear from the context, one skilled in the art will understand that a reference to a substrate may also be a reference to only a portion of the substrate. Furthermore, a reference to deposition on a substrate may refer to both a bare substrate and a substrate having one or more films or features deposited or formed thereon.

[0012] As used herein, "substrate" refers to any substrate or any material surface formed on a substrate on which a film treatment is performed during a manufacturing process. For example, substrate surfaces on which treatment can be performed include materials such as silicon, silicon oxide, strained silicon, silicon-on-insulator (SOI), carbon-doped silicon oxide, amorphous silicon, doped silicon, germanium, gallium arsenide, glass, sapphire, and any other materials such as metals, metal nitrides, metal alloys, and other conductive materials, depending on the application. Substrates include, but are not limited to, semiconductor wafers. Substrates can be subjected to pretreatment processes to polish, etch, reduce, oxidize, hydroxylate, anneal, UV cure, e-beam cure, and / or bake the substrate surface. In addition to performing film treatment directly on the surface of the substrate itself, the present disclosure also allows any of the disclosed film treatment steps to be performed on an underlying layer formed on the substrate, as disclosed in more detail below, and the term "substrate surface" is intended to include such underlying layers as the context dictates. Thus, for example, if a film / layer or partial film / layer is deposited on a substrate surface, the exposed surface of the newly deposited film / layer becomes the substrate surface.

[0013] One or more embodiments of the present disclosure provide an apparatus and / or method for quantifying waveform distortion / variation from a predetermined or default waveform shape during chamber operation. In some embodiments, the predetermined or default waveform shape provides known plasma performance for a film having specific attributes. In some embodiments, the default or predetermined waveform shape is stored as a best known method (BKM) for a PVD chamber configuration.

[0014] In some embodiments, the waveform shape factor is calculated based on measurements from the power supply's internal hardware and / or firmware, hi some embodiments, the delivered voltage and / or current is sampled externally and the waveform shape factor is calculated in real-time by an external computer (or computers) that obtains data / information from sensors.

[0015] The waveform coefficient of some embodiments is used to measure process chamber performance over time. In some embodiments, the real-time measured waveform coefficient is compared to a stored BKM waveform coefficient to evaluate PVD chamber performance. This comparison of the real-time measured waveform coefficient of some embodiments indicates whether the system has drifted or changed or whether the system may develop chamber matching issues that may affect chamber performance. In some embodiments, the waveform coefficient of the process chamber is compared to a stored waveform coefficient of a reference or "golden" chamber to enable chamber matching.

[0016] Referring to FIG. 1, as an example, a rectangular voltage waveform (thick solid line) and a triangular waveform (dashed line) are shown. As shown in equations (I) and (II), the mean voltage / average voltage during the pulse of both waveforms is the same. The overall shape of these pulses is different, with the falling triangular pulse having a maximum voltage (V) that is twice that of the rectangular waveform. peak ) The following examples discuss voltage values ​​of these waveforms, but one of ordinary skill in the art will recognize that the values ​​may also represent waveform power or waveform current. Rectangle:

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[0017] 2A, 2B and 2D show other waveform shapes. FIG. 2C shows the falling triangle shape shown in FIG. 1 for comparison. In FIG. 2A, when the shaded area of ​​the "W" shaped area below the V0 line is equal to the shaded area above the V0 line, the average value is equal to V0. In FIG. 2B, when the peak of the triangle is equal to twice the V0 value, the average value is equal to V0. FIG. 2C shows the same falling triangle shape as FIG. 1, with a peak value twice V0 and an average value equal to V0. FIG. 2D shows another falling triangle shape in the opposite direction to FIG. 2C, with a peak value twice V0 and an average value equal to V0. Each of the different waveforms shown in FIG. 2A-2D has the same average value (V) equal to V0 of the rectangular signal. mean ), however, the waveform shapes are different.

[0018] To assess the difference between waveforms having the same average voltage, the waveform shape factor (S) can be determined using equation (III) and the average waveform shape factor (S avg or

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[0019]

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[0020] Using equations (III) and (IV), the theoretical average waveform shape factor for the rectangular waveform pattern shown in FIG.

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[0021] The embodiments shown in FIGS. 2C and 2D appear to be mirror images of each other, but have different average corrugation factors.

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[0022] FIG. 3 illustrates a method 100 according to one or more embodiments of the present disclosure. The method 100 of some embodiments can be used to evaluate drift in plasma processing chamber performance due to changes in plasma impedance caused by arcing instability and / or plasma instability. The methods described herein often refer to the process as a physical vapor deposition or PVD process. However, one skilled in the art will recognize that the methods are applicable to any plasma process and that the present disclosure is not limited to only physical vapor deposition processes. In some embodiments, the method is used to address other commonly found waveform shapes, including triangular shapes, sinusoidal shapes, or envelope (modulation) shapes that include multiple primary frequencies and amplitudes in other forms not shown here. Some embodiments of the present disclosure are used with semiconductor PVD processing. Some embodiments are used with complex power delivery to other industrial loads such as plasma etch processing, scientific laboratory waveform function generators, RADAR launching, and industrial induction heating.

[0023] During the primary plasma power deposition, in process 110, while the power delivered to the plasma chamber is pulsed, the waveform shape factor is calculated according to equation (IV):

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[0024] In some embodiments, the stable waveform shape factor

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[0025] In the process 130, during plasma processing, the waveform shape factor

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[0026] Wave shape coefficients defined in equations (III) and (IV)

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[0027]

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[0028] The final unspecified term (+...) indicates additional parameters added to equation (V) depending on the particular process conditions and hardware used, e.g. secondary frequency, power, phase angle, etc.

[0029] ΔF(t)=F(t)-F0, where F(t) is the measured real-time frequency and F0 is the moving average of the measured frequency or a predefined value for the application. ΔDT(t)=DT(t)-DT0, where DT(t) is the measured real-time duty cycle and DT0 is the moving average or a predefined value for the application. ΔP(t)=P(t)-P0, where P(t) is the measured real-time power and P0 is the moving average or a predefined value for the application.

[0030] S init≧0, a fixed real number selected for a particular application that is used to offset the baseline as needed, can be set to 0 or a small number (e.g., 10% or less) relative to the magnitude of the near-perfect contribution in this equation. A >0 value can further help tune the sensitivity of the S(t) signal monitoring. In some embodiments, a higher relative value to the near-perfect contribution of the remaining items reduces the monitoring sensitivity.

[0031] Formula (V) can be further divided into formulas (V') and (V'').

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[0032]

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[0033] At decision point 140, the waveform shape coefficient index I s is evaluated to determine whether this value is within a predetermined tolerance value for the process or process chamber. s If it is within the tolerance, the method 100 proceeds to process 130 by calculating the waveform shape coefficient

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[0034] 3, the first two processes 110, 120 are determined using the same process chamber and / or plasma process as the remaining processes in the method 100. This type of method monitors the process chamber and / or plasma process for deviations over time to ensure stable operation of the process chamber.

[0035] 4 illustrates another embodiment in which the method 200 is used for chamber matching. In process 230, the waveform shape factor

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[0036] In process 240, the calculated waveform shape change index I s is compared with a given tolerance. Waveform shape variation index I s is greater than or outside the tolerance, a fault message is generated and / or the plasma process is stopped in process 250. A waveform shape variation index outside the tolerance indicates that the chamber or plasma process is not matched to the process reference or "golden" chamber.

[0037] In some embodiments, the waveform shape change index I s Based on the calculation of the shape coefficient, the waveform shape change index I sis used for in situ process control to identify wafers that may have experienced problems caused by power supply malfunctions or chamber hardware failures and / or by performance drifts that caused plasma load changes.

[0038] In some embodiments, a waveform shape factor is used to ensure that the power supply or waveform generator outputs a waveform shape relative to a predetermined or default shape.

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[0039] In some embodiments, the waveform shape factor is used to provide a self-diagnostic feature that indicates equipment malfunctions.

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[0040] The controller 310 may be one of any form of general purpose computer processor, microcontroller, microprocessor, etc. that can be used in an industrial setting. In some embodiments, there is at least one controller 310. The at least one controller 310 may have a processor, a memory coupled to the processor, input / output devices 320 coupled to the processor, and supporting circuitry for communicating between different electronic components. The memory may include one or more of a transient memory (e.g., random access memory) and a non-transient memory (e.g., storage).

[0041] The memory or computer readable medium of the processor may be one or more of readily available local or remote memories such as random access memory (RAM), read only memory (ROM), floppy disk, hard disk, or any other form of digital storage. The memory may hold a set of instructions executable by the processor to control parameters and components of the system. Support circuits are coupled to the processor for supporting the processor in a conventional manner. The circuits may include, for example, cache, power supplies, clock circuits, input / output circuits, subsystems, etc.

[0042] The process can generally be stored in memory as a software routine that, when executed by a processor, causes the process chamber to perform the process of the present disclosure. The software routine can also be stored and / or executed by a second processor (not shown) that is located remotely from the hardware that the processor is controlling. Some or all of the methods of the present disclosure can also be performed in hardware. Thus, the process can be implemented in software and executed using a computer system, or implemented in hardware, for example as an application specific integrated circuit or other type of hardware implementation, or implemented as a combination of software and hardware. When executed by a processor, the software routine turns a general-purpose computer into a special-purpose computer (controller) that controls the operation of the chamber so that the process is performed.

[0043] In some embodiments, a controller has one or more configurations for performing individual processes or sub-processes for performing a method. The controller can be connected and configured to operate intermediate components for performing the functions of the method. For example, the controller can be connected and configured to control the power or frequency of a power source.

[0044] Throughout this specification, reference to "one embodiment," "certain embodiments," "one or more embodiments," or "an embodiment" means that a particular feature, structure, material, or characteristic described with respect to that embodiment is included in at least one embodiment of the disclosure. Thus, the appearance of phrases such as "in one or more embodiments," "in certain embodiments," "in one embodiment," or "in an embodiment" in various places throughout this specification do not necessarily refer to the same embodiment of the disclosure. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments.

[0045] Although the present disclosure has been described herein with reference to specific embodiments, those skilled in the art will recognize that the described embodiments are merely illustrative of the principles and applications of the present disclosure. It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed method and apparatus without departing from the spirit and scope of the present disclosure. Thus, the present disclosure may include modifications and variations that come within the scope of the claims and their equivalents.

Claims

1. 1. A method for controlling a plasma process, comprising the steps of: determining a waveform shape variation index during said deposition process; determining whether the waveform shape index is within a predetermined tolerance and determining subsequent operation of the plasma process; The method includes:

2. The waveform shape change index is represented by the formula (V): [0010] (VI) is determined in real time using [0025] is the average waveform shape factor, [0030] The method of claim 1 , wherein:

3. The average waveform shape coefficient [0045] is represented by formula (IV) [0050] (IV) where the integral is calculated from time 0 to time T on 3. The method of claim 2, wherein the pulse length is up to S(t) and S(t) is the waveform shape factor.

4. The waveform shape coefficient S(t) at time t is expressed by the formula (III) or the formula (V): [006] (III) 【number】 (V) The method of claim 3, wherein the calculation is performed using 【Request 5】 【Number 7】 The method of claim 4 , wherein:

6. The method of claim 5 , wherein the average reference waveform shape factor is determined from a first power pulse of the plasma process.

7. 7. The method of claim 6, wherein the waveform shape factor index is a monitoring index that monitors the process chamber and / or plasma process for deviations over time to ensure stable operation of the process chamber.

8. The method of claim 5 , wherein the average reference waveform shape factor is determined from a reference plasma process or a reference processing chamber.

9. The method of claim 8 , wherein the waveform shape factor index matches a target plasma process or processing chamber to the reference plasma process or reference processing chamber, respectively.

10. 5. The method of claim 4, wherein if the waveform shape index is within the predetermined tolerance, the subsequent operation includes continuing the deposition process, and wherein the determining of the waveform shape variation index during the deposition process is repeated, the determining of whether the waveform shape index is within the predetermined tolerance, and the determining of the subsequent operation of the deposition process are repeated.

11. 5. The method of claim 4, wherein if the waveform shape variation index is outside the predetermined tolerance range, the subsequent action includes one or more of notifying a user of the presence of a fault or tolerance failure or automatically stopping the plasma process.

12. 1. A method for matching a plasma process to a reference plasma process, comprising: During the plasma process, the waveform shape factor [0080] To determine, The waveform shape coefficient [0097] and the average reference waveform shape coefficient from the reference plasma process [0089] and the waveform shape change index I s To determine, The waveform shape index I s determining whether the plasma process is consistent with the reference plasma process based on The method includes:

13. The waveform shape coefficient ##EQU00011## is represented by formula (IV) ##EQU00012## (IV) where the integral is calculated from time 0 to time T on 13. The method of claim 12, wherein the pulse length is up to S(t) and S(t) is the waveform shape factor.

14. The waveform shape change index I s Formula (V) ##EQU00013## (V) is determined in real time using ##EQU14## is the average waveform shape factor, ##EQU00015## The method of claim 13 , wherein:

15. The waveform shape coefficient S(t) at time t is expressed by the formula (III): ##EQU00016## (III) where v t is the voltage, current or power at time t, and v mean is an average voltage, current or power, or the waveform shape coefficient S(t) at time t is expressed by the formula (V): ##EQU00017## (V) The method of claim 14, wherein the calculation is performed using

16. Determining whether the plasma process is consistent with the reference plasma process is performed using the waveform shape variation index I s 16. The method of claim 15, comprising comparing the value of the first dimension to a predetermined tolerance.

17. 17. The method of claim 16, wherein if the waveform shape index is within the predetermined tolerance, the subsequent operation includes continuing the deposition process, and wherein the determining of the waveform shape variation index during the deposition process is repeated, the determining of whether the waveform shape index is within the predetermined tolerance, and the determining of the subsequent operation of the deposition process are repeated.

18. 20. The method of claim 17, wherein if the waveform shape variation index is outside the predetermined tolerance range, the subsequent action includes one or more of notifying a user of the presence of a fault or tolerance failure or automatically stopping the plasma process.

19. A power supply having a self-diagnostic function for indicating malfunctions, the self-diagnostic function comprising: a waveform shape factor [0018] or Waveform Shape Change Index I s a controller configured to determine one or more of:

20. 20. The power supply of claim 19, further comprising one or more inputs / outputs for accepting user input and / or providing user feedback reporting one or more of the measured waveform shape factors or waveform shape change indices.

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