Customize etching selectivity and high aspect ratio feature loading through a multi-level pulsing scheme utilizing sinusoidal RF waveforms and custom RF waveforms

Abstract

A method for performing a plasma etching process in a process chamber, the method including applying a source radio frequency (RF) signal to an upper electrode of the process chamber and applying a bias RF signal to a lower electrode of the process chamber, the bias RF signal having two or more pulsed duty cycles, the two or more pulsed duty cycles including a first duty cycle having a first sinusoidal waveform of a first frequency, the first sinusoidal waveform pulsed at a first voltage level, and a second duty cycle having a custom waveform pulsed at a second voltage level, the custom waveform comprising a second sinusoidal waveform of a second frequency combined with a non-sinusoidal waveform.

Description

Technical Field

[0001] Implementations of the present disclosure relate to customizing etch selectivity and high aspect ratio feature loading through a multi-level pulsing scheme utilizing sinusoidal RF waveforms and custom RF waveforms.

Background Art

[0002] In the fabrication of semiconductor devices, reactive ion etching (RIE) is utilized to etch features in a substrate (e.g., a wafer). However, due to the requirements of modern devices, etching of high aspect ratio (HAR) features (e.g., a ratio of height to width greater than 20:1, 30:1, 40:1, 50:1, etc.) may be required, and many challenges remain in the etching of high aspect ratio (HAR) features. Aspect ratio dependent etching (ARDE) is observed where the etching rate decreases as the aspect ratio of the feature being etched increases. Iso-dense loading, where the effect of feature density across the substrate surface affects the etching process, becomes a problem.

[0003] Implementations of the present disclosure arise from such circumstances.

Summary of the Invention

[0004] Implementations of the present disclosure relate to customizing etch selectivity and high aspect ratio feature loading through a multi-level pulsing scheme utilizing sinusoidal RF waveforms and custom RF waveforms.

[0005] In some implementations, a method for performing a plasma etching process in a process chamber includes applying a source radio frequency (RF) signal to an upper electrode of the process chamber and applying a bias RF signal to a lower electrode of the process chamber, wherein the bias RF signal has two or more pulsed duty cycles, and the two or more pulsed duty cycles include a first duty cycle having a first sine wave form of a first frequency and pulsed at a first voltage level, and a second duty cycle having a custom waveform pulsed at a second voltage level, the custom waveform consisting of a second sine wave form of a second frequency combined with a non-sine wave form. A method is provided.

[0006] In some implementations, the source RF signal is configured to generate plasma within a plasma process region disposed between the upper electrode and the lower electrode.

[0007] In some implementations, the bias RF signal is configured to accelerate ions from the plasma toward the lower electrode.

[0008] In some implementations, the first duty cycle produces a first ion energy distribution of ions, and the second duty cycle produces a second ion energy distribution of ions that is narrower than the first ion energy distribution.

[0009] In some implementations, the second voltage level is greater than the first voltage level.

[0010] In some implementations, the second frequency is greater than the first frequency.

[0011] In some implementations, the upper electrode is configured to inductively couple or capacitively couple power into the process chamber.

[0012] In some embodiments, a method for performing a plasma etching process in a process chamber includes applying a source radio frequency (RF) signal to an upper electrode of the process chamber and applying a bias RF signal to a lower electrode of the process chamber, the bias RF signal having two or more pulsed duty cycles, the two or more pulsed duty cycles including a first duty cycle having a sinusoidal waveform of a first frequency and pulsed at a first voltage level, and a second duty cycle having a non-sinusoidal waveform of a second frequency and pulsed at a second voltage level.

[0013] In some embodiments, the source RF signal is configured to generate plasma within a plasma process region disposed between the upper electrode and the lower electrode.

[0014] In some embodiments, the bias RF signal is configured to accelerate ions from the plasma toward the lower electrode.

[0015] In some embodiments, the first duty cycle produces a first ion energy distribution of ions, and the second duty cycle produces a second ion energy distribution of ions that is narrower than the first ion energy distribution.

[0016] In some embodiments, the second voltage level is greater than the first voltage level.

[0017] In some embodiments, the second frequency is greater than the first frequency.

[0018] In some embodiments, the upper electrode is configured to inductively couple power or capacitively couple power into the process chamber.

[0019] In some implementations, a system for performing a plasma etching process includes a process chamber, a source radio frequency (RF) generator that generates a source RF signal applied to an upper electrode of the process chamber, and a plurality of bias RF generators that generate a bias RF signal applied to a lower electrode of the process chamber. The bias RF signal has two or more pulsed duty cycles, and the two or more pulsed duty cycles include a first duty cycle having a first sinusoidal waveform at a first frequency and pulsed at a first voltage level, and a second duty cycle having a custom waveform pulsed at a second voltage level, the custom waveform consisting of a second sinusoidal waveform at a second frequency combined with a non-sinusoidal waveform. A system is provided.

[0020] In some implementations, the source RF signal is configured to generate plasma within a plasma process region disposed between the upper electrode and the lower electrode.

[0021] In some implementations, the bias RF signal is configured to accelerate ions from the plasma toward the lower electrode.

[0022] In some implementations, the first duty cycle produces a first ion energy distribution of ions, and the second duty cycle produces a second ion energy distribution of ions that is narrower than the first ion energy distribution.

[0023] In some implementations, the second voltage level is greater than the first voltage level.

[0024] In some implementations, the second frequency is greater than the first frequency.

[0025] As will be appreciated, the foregoing represents a summary of some non-limiting implementations of the present disclosure. Additional implementations will be apparent to those skilled in the art in accordance with the scope of the present disclosure.

Brief Description of the Drawings

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Embodiments for Carrying Out the Invention

[0033] Implementations of the present disclosure provide the ability to perform selective etching by ion energy and ion mass on two or more materials of an etching stack, using simultaneous control over high aspect ratio (HAR) etch rate and optimized sparse / dense feature loading, by generating a bias RF signal using both a sinusoidal RF waveform and a custom / tailored RF waveform in a multi-level parsing (MPL) scheme. It should be understood that embodiments of the present invention can be implemented in a number of ways, such as a process, apparatus, system, device, or method on a computer-readable medium. Some embodiments are described below by way of example only, without limitation.

[0034] Selectivity to a material is managed by controlling the ion energy that is above the etching threshold energy of that material. At the same time, optimizing the spread of the ion angular distribution at higher ion energies enables ions to etch high aspect ratio features. In implementations of the present disclosure, conventional sinusoidal bias RF waveforms and customized RF waveforms are utilized with tunable voltage, duty cycle, positive raise width, and amplitude to combine a technique for controlling the etching threshold energy and a technique for controlling the ion angular spread for different materials within the same stack, minimizing the sacrifice to etching metrics.

[0035] Current state-of-the-art techniques utilize sinusoidal waveforms for both continuous wave (CW) high voltage bias pulsing and multi-level parsing (MLP) using single or mixed frequencies and 2 to 4 levels of pulses.

[0036] In an implementation of the present disclosure, for a part of the bias level cycle, both a sine wave MLP scheme and a custom RF waveform are combined. The custom waveform helps modulate (e.g., decrease or increase) and control the ion energy level specific to the etching threshold, enabling control over the ion angle distribution. And multi-level pulsing using a sine wave RF waveform helps control the ion angle spread in higher energy operations. By changing the duty cycle, the number of levels, the operating voltage, and the waveform, control over the etching output is achieved.

[0037] By innovatively mixing both a sine wave RF bias waveform and a custom non-sine wave RF bias waveform in a multi-level pulsing scheme, it becomes possible to control the dependence of etching on ion energy and ion mass so that better selectivity is obtained when multiple materials are involved in features across various aspect ratios.

[0038] FIG. 1 conceptually shows a pulsed RF signal used for plasma processing operations according to an implementation of the present disclosure.

[0039] In some implementations, the plasma is generated using an inductively coupled plasma (ICP), or transformer coupled plasma (TCP) system. Examples of ICP / TCP systems include the Kiyo® system manufactured by Lam Research Corporation, which includes systems capable of performing reactive ion etching and atomic layer etching. In one exemplary ICP / TCP system, a source RF signal is applied to the TCP coil, thereby inductively coupling power into the process region of the process chamber to generate a plasma within the process region above the substrate (e.g., wafer) being processed. In some implementations, the source RF signal is a continuous wave (CW) source RF signal having a substantially constant voltage (amplitude), such as that represented by line 100 showing the relationship of voltage to time, rather than being pulsed. In other implementations, the source RF signal can be pulsed and have a voltage pulsing scheme such as that shown by curve 102. For example, the source RF signal can be configured to alternately repeat a high voltage pulse state S1 and a low voltage pulse state S2, as conceptually shown.

[0040] A bias RF signal is applied to a lower electrode above which the substrate is disposed. Generally speaking, the application of the bias RF signal is configured to drive ions generated in the plasma across the plasma sheath and accelerate those ions toward the substrate surface in order to etch the substrate surface. The bias RF signal can be a pulsed signal with a sine wave pulsed at multiple voltages, and further, the frequency of this sine wave can vary depending on the various pulse duty cycles of the pulsing scheme.

[0041] For example, bias RF pulse scheme 104 conceptually shows a pulsing scheme consisting of a first pulse duty cycle of voltage V1 that alternates with a second pulse duty cycle of voltage V2. The underlying waveform is a sine wave of frequency f1 (e.g., from 400 kHz to 60 MHz).

[0042] A further example of a bias RF pulsing scheme has additional pulse voltage levels and frequencies in the figure. For example, in bias RF pulsing scheme 106, the pulsing scheme consists of three states including a first pulse duty cycle of voltage V1, a second pulse duty cycle of voltage V2, and a third pulse duty cycle of voltage V3. During the first pulse duty cycle, the signal has a frequency f1, while during the second and third pulse duty cycles, the signal has a frequency f2.

[0043] In bias RF pulsing scheme 108, the pulsing scheme consists of five states including a first pulse duty cycle of voltage V1, a second pulse duty cycle of voltage V2, a third pulse duty cycle of voltage V3, a fourth pulse duty cycle of voltage V4, and a fifth pulse duty cycle of voltage V5. During the first two pulse duty cycles, the signal has a frequency f1, while during the third, fourth, and fifth pulse duty cycles, the signal has a frequency f2.

[0044] In bias RF pulsing scheme 110, any number of pulse states can exist as shown in the figure, and such pulse states can have different duty cycles as well as different frequencies.

[0045] In some implementations, consecutive pulse states within a single pulse cycle of a given RF pulsing scheme are configured to have increasing voltage levels. In other implementations, the voltage levels of the pulse states can differ in other ways. In some implementations, consecutive pulse states within a single pulse cycle are configured to have increasing frequencies when the frequency changes between pulse states within the cycle (e.g., in the above example, f2 > f1). In other implementations, the frequencies can differ in other ways (e.g., in the above example, f2 < f1).

[0046] In the bias RF pulsing described with reference to FIG. 1, the underlying waveform is a sine wave. However, as will be described in more detail below, further improvements can be achieved through the use of custom / tailored non-sine waveforms.

[0047] FIG. 2 conceptually shows various bias RF pulsing schemes incorporating non-sine waveforms according to implementations of the present disclosure.

[0048] In one example of a bias RF pulsing scheme 200, the pulse cycle consists of two pulse states that alternate between a first pulse state 202 of voltage V1 and a second pulse state 204 of voltage V2. In some implementations, V2 is greater than V1. As shown, the first pulse state 202 has a duty cycle α, and thus the second pulse state 204 has a duty cycle 1 - α. In some implementations, the underlying waveform consists of a sine waveform of frequency f1 combined with a non-sine waveform 206. In other implementations, the underlying waveform consists only of the non-sine waveform 206 and does not include a sine waveform.

[0049] By way of example and without limitation, examples of custom / tailored non-sine waveforms used according to implementations of the present disclosure can include, but are not specifically described herein and are known in the art, any of the following and others, namely, square waves, rectangular waves, trapezoidal waves, triangular waves, sawtooth waves, etc. Non-sine waveforms can also be generated by mixing two or more waveforms, including mixing two or more sine waveforms and / or non-sine waveforms that can have various frequencies, amplitudes, and / or other characteristics.

[0050] In another example 208 of the bias RF pulsing scheme, the pulse cycle consists of three pulse states, including a first pulse state 210 of voltage V1, a subsequent second pulse state 212 of voltage V2, and a subsequent third pulse state 214 of voltage V3. In some implementations, V3 is greater than V2, and V2 is greater than V1. As shown, the first pulse state 210 has a duty cycle α1, the second pulse state 212 has a duty cycle α2, and the third pulse state 214 has a duty cycle 1 - α1 - α2. In some implementations, the waveform underlying the first pulse state 210 is a sine waveform of frequency f1, and the waveform underlying the second pulse state 212 and the third pulse state 214 consists of a sine waveform of frequency f2 combined with a non - sine waveform 216. In other implementations, the waveform underlying the second and third pulse states consists only of the non - sine waveform 216 and does not include a sine waveform. In some implementations, the voltage V2 of the second pulse state 212 and the voltage V3 of the third pulse state 214 are set to be equal, resulting in a two - state pulsing regime.

[0051] In another example 218 of the bias RF pulsing scheme, the pulse cycle consists of three pulse states, including a first pulse state 220 of voltage V1, a subsequent second pulse state 222 of voltage V2, and a subsequent third pulse state 224 of voltage V3. In some implementations, V3 is greater than V2, and V2 is greater than V1. As shown, the first pulse state 220 has a duty cycle α1, the second pulse state 222 has a duty cycle α2, and the third pulse state 224 has a duty cycle 1 - α1 - α2. In some implementations, the waveform underlying the first pulse state 220 consists of a combination of a sine wave of frequency f1 and a non-sine wave 226, and the waveforms underlying the second pulse state 222 and the third pulse state 224 are sine waves of frequency f2. In other implementations, the waveform underlying the first pulse state 220 consists only of the non-sine wave 226 and does not include a sine wave. In some implementations, the voltage V2 of the second pulse state 222 and the voltage V3 of the third pulse state 224 are set to be equal, resulting in a two-state pulsing regime.

[0052] In another example 228 of the bias RF pulsing scheme, the pulse cycle consists of three pulse states, including a first pulse state 230 of voltage V1, a subsequent second pulse state 232 of voltage V2, and a subsequent third pulse state 234 of voltage V3. In some implementations, V3 is greater than V2, and V2 is greater than V1. As shown, the first pulse state 230 has a duty cycle α1, the second pulse state 232 has a duty cycle α2, and the third pulse state 234 has a duty cycle 1 - α1 - α2. In some implementations, the waveform underlying the first pulse state 230 is a sine wave of frequency f1, the waveform underlying the second pulse state 232 consists of a non-sine wave 236, and the waveform underlying the third pulse state 234 is a sine wave of frequency f2. In other implementations, the waveform underlying the second pulse state consists of a mixture of a sine wave and the non-sine wave 236.

[0053] In the above-described implementation, a single non-sinusoidal waveform is applied to one or more pulse states of a multi-state pulsing scheme. However, in some implementations, two or more non-sinusoidal waveforms can be applied as replacements for or in combination with sinusoidal waveforms across various pulse states of the pulse states.

[0054] In the above-described implementation, a bias RF multi-state pulsing scheme having two or three pulse states has been described. However, as will be appreciated, in other implementations, it is possible for there to be four or more states. In such implementations, a given pulse state can use a sinusoidal waveform, a non-sinusoidal waveform, or a mixed waveform consisting of a combination of a non-sinusoidal waveform and a sinusoidal waveform. Further, as will be appreciated, the specific voltage levels and frequencies of the various pulse states can vary in different implementations, similar to the voltage levels and frequencies described above with reference to FIG. 1.

[0055] FIG. 3 is a conceptual graph showing the relationship between ion flux and energy for various bias RF signals applied in a plasma process according to an implementation of the present disclosure.

[0056] As will be appreciated, the graph shown is conceptual and is provided as an example to illustrate the advantages of using non-sinusoidal custom / tailored waveforms in accordance with an implementation of the present disclosure.

[0057] An ongoing challenge in plasma processing is how to obtain control over the ion angle distribution. Generally speaking, when the distribution of ion energy is narrow, a narrow ion angle distribution is also produced, whereby more ions are able to move vertically along the sidewalls of the feature being etched with less loss. As the bias RF frequency increases, the ion energy distribution becomes narrower, but the ion energy also increases. Thus, the challenge is to achieve a narrow ion angle distribution without the need for high energies that may not be suitable for a particular process and that may not allow for selectivity of a given material.

[0058] For example, in the illustrated graph, the relationship between flux and ion energy is conceptually shown for various frequencies. Curve 304 conceptually shows the ion energy distribution of ions accelerated using a relatively high-frequency bias RF signal (e.g., 60 MHz) having a sinusoidal waveform, while curves 302 and 300 conceptually show the ion energy distributions of ions accelerated using bias RF signals of progressively decreasing frequencies (e.g., 13.56 MHz and 1 MHz, respectively). As can be seen from these curves, the ion energy distribution is narrow at relatively high energy levels but becomes broader at lower frequencies (typically exhibiting a bimodal distribution). Thus, the challenge is to achieve a narrow ion energy distribution (and narrow ion angle distribution) at lower frequencies.

[0059] However, by introducing a non-sinusoidal waveform in accordance with the implementations described herein, it is possible to generate lower-energy ions while also resulting in a narrow ion energy distribution. Such an example is conceptually shown by curve 306, demonstrating a narrow ion energy distribution in a low-energy regime achieved through the use of the non-sinusoidal waveforms described herein. Thus, it is possible to obtain control over the ion angle distribution even at low energies, thereby enabling better selectivity in the etching process.

[0060] Figure 4 conceptually shows the advantages of applying a non-sinusoidal waveform to a pulsed bias RF signal according to an implementation of the present disclosure.

[0061] Under current state-of-the-art etching processes, an RF generator 400 generates a sinusoidal waveform 404 (e.g., 13.56 MHz by way of example only), which can be pulsed. The resulting ion energy (conceptually shown by reference numeral 408) may not be sufficient to etch a particular material or to etch to the bottom of a particular high aspect ratio feature. Thus, in order to increase the ion energy, DC power can be additionally applied to the RF signal to increase the ion energy. However, while this increases the ion energy, the energy distribution also spreads, resulting in an ion energy distribution as shown by curve 412.

[0062] Consider the case of feature 414 (conceptually shown in cross-section) having materials A, B, and C. The energy thresholds for etching materials A, B, and C are conceptually shown in graph 410 of energy vs. flux by threshold lines 416, 418, and 420. It is desirable to etch material A at the bottom of feature 414 while not etching materials B and C along the top surface and sidewalls of the substrate, respectively. When a sine waveform 404 is used alone and a high power is applied, some of the ions can have sufficient energy to etch material A. However, this is inefficient and has low throughput because only a small fraction of the ions have sufficient energy to etch material A while most of the ions do not. Considering the spread of ion energy shown by curve 412, the ion angle distribution is quite dispersed, whereby many ions do not enter feature 414 downward and are lost along the sidewalls. When a larger DC power is applied, the ion energy increases, but this pushes the upper end of the ion energy into a regime where materials B and C can be etched, which is not desirable. Thus, selectivity for material A is lost in exchange for achieving higher energy in this way.

[0063] However, as described above, by introducing the non-sinusoidal custom waveform 406 generated by the second RF generator 402, a narrow ion energy distribution represented by curve 422 can be achieved. As mentioned, in some implementations, the non-sinusoidal waveform can be combined with the existing sinusoidal waveform during at least a portion of the pulse cycle, or the non-sinusoidal waveform can replace the existing sinusoidal waveform. As shown by curve 422, the generated ion energy is mainly concentrated at a level sufficient to etch material A without significantly generating species for etching material B or C. Since the ion energy is focused where it exceeds the threshold of material A, efficiency and throughput are improved. By applying a non-sinusoidal custom waveform according to an implementation of the present disclosure, it becomes possible to obtain control of the ion energy distribution and target specific energy levels to provide selectivity for a given material.

[0064] As mentioned above, the ARDE continues to pose the challenge of how to increase the energy of the ions reaching the bottom of the HAR feature. The combination of the reduction in the bias RF frequency and the pulsing of the underlying sinusoidal waveform enables the acceleration of higher energy ions that can be driven into the HAR feature downward by the necessary voltage spikes when the duty cycle is on. However, the control of the angular spread of the incident ion species remains a challenge because many ions are lost on the sidewalls or cannot enter the HAR feature at all. Another challenge is that there are sparse and dense features, as well as various materials, such that even if ions with sufficient energy to reach the bottom can be generated, those ions also tend to etch the mask due to high energy or low selectivity to the mask, at the expense of this point.

[0065] However, by mixing a custom waveform with a sinusoidal waveform in a pulsed bias RF signal, control over the ion energy distribution is achieved in terms of both energy and distribution / spread. This enables targeting the ion energy to achieve etching selectivity. Without being bound by any particular operating theory, it is still hypothesized through explanation that the custom waveform is a different voltage waveform that changes the way ions move through the plasma sheath, thereby changing the ion energy distribution. This enables tuning the sheath capacitance or sheath resistance, causing the ions to behave differently and thereby enabling control over the ion energy distribution. Thus, by changing the waveform, it is possible to tune the ion energy distribution to achieve a narrow distribution at the target energy level. Parameters of the bias RF waveform, such as the selection of non-sinusoidal / custom waveforms, voltage, duty cycle, positive ramp width, and amplitude, can be tuned to yield the desired target energy level and ion energy distribution.

[0066] Figure 5 conceptually shows a method for applying a non-sinusoidal waveform to a bias RF signal to achieve targeted ion energy characteristics according to an implementation of the present disclosure.

[0067] In some implementations, the method is implemented through a user interface of a controller / computer that enables control of the operating parameters of the plasma processing system, including the parameters of the bias RF signal.

[0068] In method operation 500, the type of material being etched and the type of structure being etched are identified. By way of example and without limitation, the structure can be a stack, via, or trench, and can have sidewall materials, various layers, etc.

[0069] In method operation 502, an energy threshold for each material or combined materials (e.g., a layer of combined materials) is identified.

[0070] In method operation 504, based on the energy threshold of the material, a non-sinusoidal waveform to be added to at least a part of the pulsed cycle of the bias RF power is selected. As described above, the non-sinusoidal waveform can also be combined with a sinusoidal waveform in some implementations, or can be used alone in other implementations.

[0071] In method operation 506, the parameters of the bias RF signal are tuned to adjust the target ion energy level and ion energy distribution to their desired states. Examples of tunable parameters include multi-level pulsing levels, duty cycles of the pulses, voltage segregation within the pulse period, waveform tailoring (e.g., peak-to-peak voltage, width of the positive ramp, amplitude of the positive ramp), and gas flow rate of the etchant relative to the passivant.

[0072] In some implementations, at least a portion of method operations 502, 504, or 506 described above are automatically performed by a controller / computer in response to identification of the material being etched and / or the type of structure being etched. For example, the energy threshold can be automatically determined and a pre-defined non-sinusoidal waveform can be automatically applied with default parameters. In some implementations, method operations 504 and 506 are manually performed by an operator through a user interface configured to enable method operations 504 and 506 to be performed in response to input received through the user interface.

[0073] The concepts described herein are applicable to the etching of high aspect ratio features, but are also applicable to low aspect ratio etching processes such as mask openings. The selectivity and ion energy control provided by embodiments of the present invention are useful in such applications as well.

[0074] The concepts described herein are also applicable to atomic layer etching (ALE), which typically aims to remove approximately a monolayer of material per ALE cycle. For example, in a silicon ALE process, typically fluorination is used in the activation step and argon plasma is used in the removal step. However, when using, for example, a typical sinusoidal 13 MHz bias, ion energy spread due to the nature of sheath dynamics and ion energy distribution due to the plasma sheath occur under such a 13 MHz bias. Some species with higher energy than actually required for material removal are generated, and thus cannot be accurately controlled for the etch - pulse cycle. However, by applying a non - sinusoidal waveform as described herein, it becomes possible to use such a tailored waveform to control and generate specific ion energies on - demand, thereby enabling accurate removal of layers and better control over the etch - pulse cycle.

[0075] FIG. 6 conceptually shows an inductively coupled plasma system according to an implementation of the present disclosure.

[0076] The various implementations described herein can be implemented in an inductively coupled plasma (ICP) system. An exemplary ICP system or apparatus can include a chamber 601 having a gas injector / showerhead / nozzle 603 for dispensing a gas (605, 607, 609) (e.g., a precursor, an etchant, an oxidizer, a purge gas, etc.) or other chemistry into the chamber, a chamber wall 611, and a lower electrode 613 for holding a substrate or wafer 615 to be processed, which can include an electrostatic electrode for chucking and de-chucking the wafer. The lower electrode 613 is heated for thermal control, thereby enabling the substrate 615 to be heated to a desired temperature. In some implementations, the lower electrode 613 can be charged using an RF power source 617 to provide a bias voltage according to the implementations of the present disclosure. In some embodiments, the lower electrode 613 may also be referred to as a chuck. The RF power source 617 can be defined by one or more RF generators as needed to generate a bias RF signal according to the implementations of the present disclosure.

[0077] An RF power source 619 is configured to supply power to an RF antenna / coil 621 disposed above a dielectric window 623 to generate a plasma 625 above the substrate 615 within the process space. In some implementations, the chamber wall is heated to assist with thermal management and efficiency. A vacuum source 627 provides a vacuum for evacuating gas from the chamber 601. The system or apparatus can include a system controller 629 for controlling some or all of the operation of the chamber or apparatus, such as modulating the chamber pressure, inert gas flow, plasma power, plasma frequency, reactive gas flow (e.g., precursor, etchant, oxidizer, etc.), bias power, temperature, vacuum settings, and other process conditions.

[0078] In some implementations, the system / apparatus can include two or more chambers for processing substrates.

[0079] FIG. 7 shows a control module 700 for controlling the systems described herein, according to an implementation of the present disclosure.

[0080] For example, control module 700 can include a processor, a memory, and one or more interfaces. Using control module 700, devices within the system can be controlled, in part, based on sensed values. For example, control module 700 can control one or more of valve 702, filter heater 704, pump 706, and other devices 708 based on sensed values and other control parameters. Control module 700 receives sensed values from, by way of example only, pressure gauge 710, flow meter 712, temperature sensor 714, and / or other sensors 716. Using control module 700, process conditions during reactant delivery and plasma processing can also be controlled. Control module 700 typically includes one or more memory devices and one or more processors.

[0081] Control module 700 can control the activities of a reactant delivery system and a plasma processing apparatus. Control module 700 executes a computer program that includes a set of instructions for controlling process timing, delivery system temperature, pressure differential across filters, valve position, gas mixing, chamber pressure, chamber temperature, wafer temperature, RF power level, wafer ESC or wafer pedestal position, and other parameters of a particular process. Control module 700 can also monitor the pressure differential and automatically switch vapor reactant delivery from one or more paths to one or more other paths. Other computer programs stored on a memory device associated with control module 700 can also be used in some implementations.

[0082] Typically, a user interface is associated with the control module 700. The user interface can include a display 718 (e.g., a display screen and / or a graphical software display of device and / or process conditions), as well as user input devices 720 such as a pointing device, keyboard, touch screen, microphone, and the like.

[0083] A computer program for controlling the delivery of reactants, plasma processing, and other processes in a process sequence can be written in any conventional computer-readable programming language, such as assembly language, C, C++, Pascal, Fortran, or others. The compiled object code or script is executed by the processor to perform the tasks identified within the program.

[0084] The control module parameters are related to process conditions such as, for example, filter pressure differential, composition and flow rate of process gas, temperature, pressure, plasma conditions such as RF power level and RF frequency, cooling gas pressure, and chamber wall temperature.

[0085] The system software can be designed or configured in many different ways. For example, various chamber component subroutines or control objects can be described to control the operation of the chamber components necessary to perform the deposition process of the present invention. Examples of programs or program sections for this purpose include substrate positioning code, process gas control code, pressure control code, heater control code, and plasma control code.

[0086] Although the previous implementation forms have been described in some detail for the purpose of clarifying understanding, it will be apparent that specific changes and modifications can be made within the scope of the disclosed implementation forms. Note that there are many alternative ways to implement the processes, systems, and devices of the implementation forms of the present invention. Therefore, the implementation forms of the present invention should be regarded as exemplary and not restrictive, and those implementation forms should not be limited to the details given in this specification.

Claims

1. A method for performing a plasma etching process in a process chamber, comprising: applying a source radio frequency (RF) signal to an upper electrode of the process chamber; applying a bias RF signal to a lower electrode of the process chamber; wherein the bias RF signal has two or more pulsed duty cycles, and the two or more pulsed duty cycles include a first duty cycle having a first sinusoidal waveform of a first frequency and pulsed at a first voltage level; a second duty cycle having a custom waveform pulsed at a second voltage level, the custom waveform comprising a second sinusoidal waveform of a second frequency combined with a non-sinusoidal waveform; A method.

2. The method according to claim 1, wherein the source RF signal is configured to generate plasma in a plasma process region disposed between the upper electrode and the lower electrode.

3. The method according to claim 2, wherein the bias RF signal is configured to accelerate ions from the plasma toward the lower electrode.

4. The method according to claim 3, wherein the first duty cycle produces a first ion energy distribution of the ions; the second duty cycle produces a second ion energy distribution of the ions that is narrower than the first ion energy distribution.

5. The method according to claim 1, wherein the second voltage level is greater than the first voltage level.

6. The method according to claim 1, wherein the second frequency is greater than the first frequency.

7. The method according to claim 1, wherein the upper electrode is configured to inductively couple or capacitively couple power into the process chamber.

8. A method for performing a plasma etching process in a process chamber, comprising: applying a source radio frequency (RF) signal to an upper electrode of the process chamber; applying a bias RF signal to a lower electrode of the process chamber; wherein the bias RF signal has two or more pulsed duty cycles, and the two or more pulsed duty cycles include A first duty cycle having a sinusoidal waveform of a first frequency and being pulsed at a first voltage level, A second duty cycle having a non-sinusoidal waveform of a second frequency and being pulsed at a second voltage level A method comprising.

9. The method according to claim 8, The method wherein the source RF signal is configured to generate plasma in a plasma process region disposed between the upper electrode and the lower electrode.

10. The method according to claim 9, The method wherein the bias RF signal is configured to accelerate ions from the plasma towards the lower electrode.

11. The method according to claim 10, The method wherein the first duty cycle produces a first ion energy distribution of the ions, The method wherein the second duty cycle produces a second ion energy distribution of the ions that is narrower than the first ion energy distribution.

12. The method according to claim 8, The method wherein the second voltage level is greater than the first voltage level.

13. The method according to claim 8, The method wherein the second frequency is greater than the first frequency.

14. The method according to claim 8, The method wherein the upper electrode is configured to inductively couple or capacitively couple power into the process chamber.

15. A system for performing a plasma etching process, A process chamber, A source radio frequency (RF) generator that generates a source RF signal applied to an upper electrode of the process chamber, A plurality of bias RF generators that generate a bias RF signal applied to a lower electrode of the process chamber Comprising, The bias RF signal has two or more pulsed duty cycles, and the two or more pulsed duty cycles are A first duty cycle having a first sinusoidal waveform of a first frequency and being pulsed at a first voltage level, A second duty cycle having a custom waveform pulsed at a second voltage level, the custom waveform comprising a second sinusoidal waveform of a second frequency combined with a non-sinusoidal waveform A system comprising.

16. The system according to claim 15, A system configured such that the source RF signal generates plasma within a plasma process region disposed between the upper electrode and the lower electrode. [

17. ] The system according to claim 16, A system configured such that the bias RF signal accelerates ions from the plasma toward the lower electrode. [

18. ] The system according to claim 17, wherein the first duty cycle produces a first ion energy distribution of the ions, and the second duty cycle produces a second ion energy distribution of the ions that is narrower than the first ion energy distribution. [

19. ] The system according to claim 15, wherein the second voltage level is greater than the first voltage level. [

20. ] The system according to claim 15, wherein the second frequency is greater than the first frequency.

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