High-energy atomic layer etching

Abstract

Methods and apparatus for performing high-energy atomic layer etching are provided. The method includes providing a substrate having a material to be etched, exposing a surface of the material to a modification gas to modify the surface and form a modified surface; and exposing the modified surface to high-energy particles to preferentially remove the modified surface relative to an underlying unmodified surface, the high-energy particles having an ion energy sufficient to overcome an average surface binding energy of the underlying unmodified surface. The high-energy particles used have a high energy; in some cases, the power applied to the bias when exposing the modified surface to the high-energy particles is at least 150 eV.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 16 / 148,939, filed October 1, 2018, entitled “HIGH ENERGY ATOMIC LAYER ETCHING,” which claims priority to U.S. Provisional Patent Application No. 62 / 569,443, filed October 6, 2017, entitled “PULSING ATOMIC LAYER ETCHING,” and U.S. Provisional Patent Application No. 62 / 599,613, filed December 15, 2017, both of the contents of which are incorporated herein by reference and used for all purposes. Background Technology

[0003] Semiconductor manufacturing processes involve etching various materials. As three-dimensional structures shrink towards the sub-10nm node, conventional etching processes face unprecedented challenges. For example, pitch load becomes problematic as etch rates are affected by continuously increasing aspect ratios. Challenges related to delivering neutral substances and ions to the etching front, surface reaction rates at the etching front, and removing etch products from the etching front become more significant as devices shrink. Summary of the Invention

[0004] This document provides methods and apparatus for performing high-energy atomic layer etching. One aspect relates to a substrate processing method comprising: providing a substrate containing a material to be etched; exposing a surface of the material to be etched to a modifying gas to modify the surface and form a modified surface; and exposing the modified surface to high-energy particles to preferentially remove the modified surface relative to an underlying unmodified surface, the high-energy particles having ion energies sufficient to overcome the average surface binding energy of the underlying unmodified surface.

[0005] In various embodiments, the ionic energy of the high-energy particles is sufficient to break the bonds of the underlying unmodified surface. The high-energy particles can be delivered in time-separated doses with a duty cycle between about 1% and about 10%.

[0006] In various embodiments, a bias voltage is applied to a substrate support that holds the substrate during the exposure of the modified surface to the high-energy particles.

[0007] In various embodiments, the high-energy particles remove a certain amount of the modified surface, the amount of the modified surface removed being expressed by the following formula:

[0008]

[0009] Where Y is the ion yield of the high-energy particles, F is the flux of the high-energy particles, t is the exposure duration of the high-energy particles, and d is the surface density of the material to be etched.

[0010] In various embodiments, the high-energy particles do not significantly sputter the underlying unmodified material. For example, the modified surface can be exposed to the high-energy particles for a duration sufficient to remove the modified surface in a self-limiting manner.

[0011] On the other hand, a substrate processing method is involved, the method comprising: providing a substrate containing a material to be etched; exposing the surface of the material to be etched to a modifying gas to modify the surface and form a modified surface; and applying a bias while exposing the modified surface to high-energy particles to remove the modified surface, wherein the electrical energy applied to the bias is at least 150 eV.

[0012] In various embodiments, the electrical energy applied to the bias voltage is at least 500 eV.

[0013] On the other hand, a substrate processing method is involved, the method comprising: providing a substrate containing a material to be etched; exposing the surface of the material to be etched to a modifying gas to modify the surface and form a modified surface; and delivering a dose of high-energy particles to the modified surface to remove the modified surface, such that the dose is insufficient to remove the modified surface when delivered using a bias voltage less than the surface binding energy of the unmodified surface.

[0014] On the other hand, a substrate processing method is involved, the method comprising: providing a substrate containing a material to be etched; exposing the surface of the material to be etched to a modifying gas to modify the surface and form a modified surface; and exposing the modified surface to high-energy particles for a duration greater than the duration sufficient to remove the modified surface and the underlying unmodified surface by ion bombardment, so as to preferentially remove at least 80% of the modified surface relative to the underlying unmodified surface.

[0015] On the other hand, a substrate processing method is involved, the method comprising: providing a substrate containing a material to be etched; exposing the surface of the material to be etched to a modifying gas to modify the surface and form a modified surface; and exposing the modified surface to high-energy particles in the form of pulses having a duty cycle of less than 100%.

[0016] On the other hand, a substrate processing method is involved, the method comprising: providing a substrate containing a material to be etched; exposing the surface of the material to be etched to a modifying gas to modify the surface and form a modified surface; and exposing the modified surface to a reduced dose of high-energy particles such that the unreduced dose, when continuously delivered to the modified surface, has an energy higher than the surface binding energy of the material to be etched.

[0017] In various implementations, the dosage is reduced by altering the ion flux of the activated substance.

[0018] In some implementations, the dosage is reduced by varying the duration for which the modified surface is exposed to the activated substance.

[0019] In various embodiments, the reduced dose comprises two or more time-separated pulses of activated material directed to the modified surface to remove at least a portion of the modified surface.

[0020] In some implementations, the dosage is reduced by altering the acceleration of ions in the activated material leading to the modified surface.

[0021] In various embodiments, the dose is reduced by changing the bias applied to the substrate support holding the substrate for directional delivery of the activated substance to the modified surface.

[0022] On the other hand, a substrate processing method is involved, the method comprising: providing a substrate containing a material to be etched; exposing the surface of the material to be etched to a modifying gas to modify the surface and form a modified surface; and exposing the modified surface to high-energy particles in the form of time-separated pulses; and modulating ion energy and dose during the time-separated pulses. In some embodiments, modulating ion energy and dose includes increasing the ion energy and compensating for the increase in ion energy with a reduced dose.

[0023] On the other hand, a substrate processing method is involved, the method comprising: exposing the substrate to a modifying gas to modify the surface of the substrate to form a modified surface; exposing the modified surface of the substrate to a removal gas; and during the exposure of the modified surface to the removal gas, providing a plurality of time-separated pulses of energy generated from an activation source to remove at least some of the modified surface from the substrate.

[0024] In various embodiments, the method further includes repeatedly exposing the substrate to the modified gas and the modified surface to the removal gas in two or more cycles, such that multiple pulses are provided in time during the exposure of the modified surface to the removal gas in each cycle.

[0025] In various implementations, the time-separated multiple pulses of energy comprise at least 100 time-separated pulses of energy per cycle.

[0026] In various embodiments, the temporally separated pulses of energy are sufficient to remove the modified surface but insufficient to physically sputter the modified surface.

[0027] In various embodiments, the energy provided is defined by a bias window of a minimum voltage applied to the substrate during exposure to the removal gas sufficient to remove the modified surface and a maximum voltage applied to the substrate during exposure to the removal gas insufficient to sputter the modified surface.

[0028] In various implementations, the energy is time-separated into multiple pulses at a frequency between about 10 Hz and about 200 Hz.

[0029] In various implementations, the energy is time-separated into multiple pulses, pulsed over a duty cycle ranging from about 1% to about 10%.

[0030] In some implementations, the activation source comprises two or more sources.

[0031] In some implementations, the activation source is selected from the group consisting of radio frequency plasma, bias applied to the substrate, ultraviolet radiation, photons, and combinations thereof.

[0032] In some embodiments, the activation source includes a voltage applied to bias the substrate. The bias voltage may be at least between about 500V and about 1500V. The bias may be pulsed between 0V and a bias voltage between about 500V and about 1500V.

[0033] In some embodiments, the bias voltage is pulsed between a low bias voltage and a high bias voltage, the low bias voltage being between about 100V and about 300V, and the high bias voltage being between about 500V and about 1500V.

[0034] In some implementations, the bias voltage is pulsed using a pulsed frequency between about 10 Hz and about 200 Hz.

[0035] In some implementations, the bias voltage is pulsed using a duty cycle between about 1% and about 20%.

[0036] In some implementations, the activation source comprises radio frequency plasma.

[0037] In some embodiments, the radio frequency plasma is generated by applying power that is pulsed between an OFF state and an ON state, wherein the plasma power in the OFF state is 0W and the plasma power in the ON state is between about 50W and about 900W.

[0038] In some embodiments, the radio frequency plasma is generated by applying power, and the radio frequency plasma power is pulsed between a low plasma power and a high plasma power, the low plasma power being between about 10 W and about 100 W, and the high plasma power being between about 900 W and about 1500 W.

[0039] In some embodiments, the radio frequency plasma is pulsed using a pulsed frequency between about 10 Hz and about 200 Hz.

[0040] In some implementations, the duty cycle of the radio frequency plasma pulsed is between about 1% and about 20%.

[0041] In some embodiments, the activation source comprises radio frequency plasma and a bias applied to the substrate. The bias can be pulsed between 0V and a bias voltage, wherein the bias voltage is between about 500V and about 1500V. The bias can be pulsed between a low bias voltage and a high bias voltage, wherein the low bias voltage is between about 100V and about 300V, and the high bias voltage is between about 500V and about 1500V. The radio frequency plasma can be generated by applying power, and the radio frequency plasma power is pulsed between an OFF state and an ON state, wherein the plasma power in the OFF state is 0W, and the plasma power in the ON state is between about 50W and about 900W. The radio frequency plasma can be pulsed between a low plasma power and a high plasma power, wherein the low plasma power is between about 10W and about 100W, and the high plasma power is between about 900W and about 1500W.

[0042] In various embodiments, the substrate includes one or more narrow features and one or more wide features.

[0043] In some embodiments, the substrate is treated at a substrate temperature between about 0°C and about 120°C.

[0044] In some embodiments, the substrate is treated in a processing chamber having a processing chamber pressure between about 5 mTorr and about 1 Torr during exposure to the modified gas.

[0045] In some embodiments, the substrate is processed in a processing chamber having a processing chamber pressure between about 5 mTorr and about 200 mTorr during exposure to the removal gas.

[0046] On the other hand, a substrate processing method is involved, the method comprising: exposing the substrate to a modifying gas to modify the surface of the substrate to form a modified surface; exposing the modified surface of the substrate to a removal gas; and periodically igniting a plasma in the form of two or more time-separated pulses during the exposure of the modified surface to the removal gas to remove at least some of the modified surface from the substrate.

[0047] The method may further include repeatedly exposing the substrate to the modified gas and the modified surface to the remover gas in two or more cycles, such that two or more pulses of plasma are provided at different times during the exposure of the modified surface to the remover gas in each cycle.

[0048] In some implementations, the time-separated multiple pulses of the plasma comprise at least 100 pulses of energy per cycle.

[0049] The method may further include applying a bias in a pulsed manner during the exposure of the modified surface to the remover gas. In various embodiments, the method may further include repeatedly exposing the substrate to the modified gas and the modified surface to the remover gas in two or more cycles, such that two or more pulses are provided in each cycle, separating the time of plasma and bias during the exposure of the modified surface to the remover gas.

[0050] In some embodiments, the plasma and the time-separated multiple pulses of the bias comprise at least 100 pulses per cycle, the cycle comprising exposing the substrate to the modified gas and the modified surface to the removal gas.

[0051] In some implementations, the plasma and the bias are pulsed at the same frequency.

[0052] In some implementations, the plasma and the bias are pulsed using the same duty cycle.

[0053] On the other hand, a substrate processing method is provided, the method comprising: exposing the substrate to a modifying gas to modify the surface of the substrate to form a modified surface; exposing the modified surface of the substrate to a removal gas; igniting a plasma during the exposure of the modified surface; and periodically applying a bias in the form of two or more time-separated pulses during the exposure of the modified surface to the removal gas to remove at least some of the modified surface from the substrate.

[0054] The method may also include igniting plasma in a pulsed manner during the exposure of the modified surface to the removal gas.

[0055] In some embodiments, the method may further include repeatedly exposing the substrate to the modified gas and the modified surface to the remove gas in two or more cycles, wherein two or more pulses are separated in each cycle at the time during which bias power is provided while the modified surface is exposed to the remove gas.

[0056] In some embodiments, the time-separated multiple pulses of the bias power comprise at least 100 pulses per cycle, the cycle comprising exposing the substrate to the modified gas and exposing the modified surface to the removal gas.

[0057] On the other hand, a substrate processing apparatus is disclosed, the apparatus comprising: a processing chamber including a spray head and a substrate support for holding the substrate having material; a plasma generator; and a controller having a memory and at least one processor, wherein the at least one processor is communicatively connected to the memory, the at least one processor is at least operatively connected to flow control hardware, and the memory stores machine-readable instructions for: introducing a modified gas into the processing chamber; introducing a desorbed gas into the processing chamber; and pulsed an activation source during the introduction of the desorbed gas.

[0058] In various embodiments, the memory also stores machine-readable instructions for operating such that the pulse frequency of the activation source is between about 10 Hz and about 200 Hz during the introduction of the degassing gas.

[0059] In some embodiments, the memory also stores machine-readable instructions for operating the activation source at a cycle time between about 1% and about 10% during the introduction of the degassing gas.

[0060] In some embodiments, the activation source is plasma generated in the processing chamber using plasma power, and the memory also stores machine-readable instructions for pulsed activation source between an OFF state and an ON state, wherein the plasma power in the OFF state is 0W, and the plasma power in the ON state is between about 50W and about 900W.

[0061] In some embodiments, the activation source is plasma generated in the processing chamber, and the memory also stores machine-readable instructions for pulsed activation source between low plasma power and high plasma power, wherein the low plasma power is between about 10 W and about 100 W, and the high plasma power is between about 900 W and about 1500 W.

[0062] In some embodiments, the memory also stores machine-readable instructions for applying a bias to the substrate support in a pulsed manner. For example, the memory may also store machine-readable instructions for pulsed bias voltage between 0V and a bias voltage between approximately 500V and approximately 1500V. In some embodiments, the memory also stores machine-readable instructions for pulsed bias and activation source at the same pulsed frequency. In some embodiments, the memory also stores machine-readable instructions for pulsed bias and activation source at the same pulsed duty cycle.

[0063] On the other hand, it may relate to a substrate processing apparatus comprising: a processing chamber including a spray head and a substrate support for holding the substrate having material; a plasma generator; and a controller having a memory and at least one processor, wherein the at least one processor is communicatively connected to the memory, the at least one processor is at least operatively connected to flow control hardware, and the memory stores machine-readable instructions for: introducing a modified gas into the processing chamber; introducing a desorbent gas into the processing chamber; and causing radio frequency plasma power to be generated in the processing chamber in the form of two or more time-separated pulses during the introduction of the desorbent gas.

[0064] In some embodiments, the memory also stores machine-readable instructions for operating such that the pulse frequency of the radio frequency plasma power is between about 10 Hz and about 200 Hz during the introduction of the degassing gas.

[0065] In some embodiments, the memory also stores machine-readable instructions for operating the radio frequency plasma power between about 1% and about 10% during the introduction of the removal gas.

[0066] In some embodiments, the memory also stores machine-readable instructions for pulsed radio frequency plasma power between an OFF state and an ON state, wherein the plasma power in the OFF state is 0W and the plasma power in the ON state is between about 50W and about 900W.

[0067] In some embodiments, the memory also stores machine-readable instructions for pulsed radio frequency plasma power between a low plasma power and a high plasma power, wherein the low plasma power is between about 10 W and about 100 W, and the high plasma power is between about 900 W and about 1500 W.

[0068] In some embodiments, the memory also stores machine-readable instructions for applying a bias to the substrate support in a pulsed manner.

[0069] In some embodiments, the memory also stores machine-readable instructions for pulsed bias voltage between 0V and a bias voltage between about 500V and about 1500V.

[0070] In some embodiments, the memory also stores machine-readable instructions for causing the bias to pulse between a low bias voltage and a high bias voltage, wherein the low bias voltage is between about 100V and about 300V, and the high bias voltage is between about 500V and about 1500V.

[0071] In some embodiments, the memory also stores machine-readable instructions for causing the bias and the radio frequency plasma power to pulse at the same pulsed frequency.

[0072] In some embodiments, the memory also stores machine-readable instructions for causing the bias and the radio frequency plasma power to pulse at the same pulsed duty cycle.

[0073] On the other hand, a substrate processing apparatus is disclosed, the apparatus comprising: a processing chamber including a spray head and a substrate support for holding the substrate having material; a plasma generator; and a controller having a memory and at least one processor, wherein the at least one processor is communicatively connected to the memory, the at least one processor is at least operatively connected to flow control hardware, and the memory stores machine-readable instructions for: introducing a modified gas into the processing chamber; introducing a desorbed gas into the processing chamber; and causing bias power to be applied to the substrate support and to the substrate in the form of two or more time-separated pulses during the introduction of the desorbed gas.

[0074] In some embodiments, the memory also stores machine-readable instructions for operating such that the pulse frequency of the bias power is between about 10 Hz and about 200 Hz during the introduction of the degassing gas.

[0075] In some embodiments, the memory also stores machine-readable instructions for operating such that the bias power is kept between about 1% and about 10% of its duty cycle during the introduction of the degassing gas.

[0076] In some embodiments, the memory also stores machine-readable instructions for pulsed bias power between an OFF state and an ON state, wherein the bias power in the OFF state is 0V and the bias power in the ON state is between about 500V and about 1500V.

[0077] In some embodiments, the memory also stores machine-readable instructions for pulsed bias power between a low bias power and a high bias power, wherein the low bias power is between about 100V and about 300V, and the high bias power is between about 500V and about 1500V.

[0078] In some embodiments, the memory also stores machine-readable instructions for igniting the plasma by applying plasma power in a pulsed manner during the introduction of the removal gas.

[0079] In some embodiments, the memory also stores machine-readable instructions for pulsed plasma power between 0W and approximately 50W and approximately 900W.

[0080] In some embodiments, the memory also stores machine-readable instructions for pulsed plasma power and bias power at the same pulsed frequency.

[0081] In some embodiments, the memory also stores machine-readable instructions for pulsed plasma power and bias power at the same pulsed duty cycle.

[0082] These and other aspects are further described below with reference to the accompanying drawings. Attached Figure Description

[0083] Figure 1 An exemplary schematic diagram of a substrate subjected to atomic layer etching is shown.

[0084] Figure 2 A three-dimensional schematic diagram of a FinFET semiconductor device is shown.

[0085] Figure 3A and 3B The processing flowchart illustrates the operation of a method according to some embodiments of the present invention.

[0086] Figure 4A-4G The timing diagram illustrates examples of operations performed according to some embodiments of the present invention.

[0087] Figure 4H This is a timing diagram illustrating low-energy and high-energy ALEs.

[0088] Figure 4I and 4J An exemplary schematic diagram illustrating the removal of modified membrane layers at low and high ion energies in ALE.

[0089] Figure 5 This is a schematic diagram of an exemplary processing chamber used for implementing embodiments of the present invention.

[0090] Figure 6 This is a schematic diagram of an exemplary processing apparatus for carrying out embodiments of the present invention.

[0091] Figure 7 A graph showing the relationship between the etching of silicon on the insulator in each cycle and the bias power used in the pulsed ALE, wherein the bias power is pulsed for experiments conducted according to an embodiment of the invention.

[0092] Figure 8A A graph showing the relationship between the etching of amorphous silicon and silicon oxide in each cycle and the bias power used in pulsed ALE, wherein the bias power is pulsed for experiments conducted according to an embodiment of the invention.

[0093] Figure 8B This is a graph showing the etch selectivity as a function of the bias power used in pulsed ALE, where the bias power is relative to... Figure 8A The experiment was pulsed.

[0094] Figure 9A A graph showing the relationship between the etching of amorphous silicon and silicon oxide in each cycle and the bias power used in pulsed ALE, wherein the bias power is pulsed for experiments conducted according to an embodiment of the invention.

[0095] Figure 9B A graph showing the etch selectivity as a function of the pulsed bias power used in ALE, where the bias power is relative to... Figure 9A The experiment was pulsed.

[0096] Figure 10A and 10B The graph shows the pitch load, which is a function of the trench critical dimension used in a pulsed ALE with different bias powers in an experiment conducted according to an embodiment of the present invention.

[0097] Figure 11 A graph depicting the relationship between material etching per cycle using pulsed ALE and material etching per cycle without pulsed ALE is presented.

[0098] Figure 12A An example of an etch model for each cycle based on the function provided by Equation 5B.

[0099] Figure 12B This graph shows the relationship between the etching rate of each cycle and the argon bias in the example of low-energy ALE.

[0100] Figure 13 This is an example of the functional relationship between ion energy and the “on” time of argon exposure for complete removal.

[0101] Figure 14A An example of the functional relationship between the normalized etching for each cycle of ALE and the various “on” times of argon exposure used for pulsed ALE.

[0102] Figure 14B An exemplary etching for each cycle of argon exposure “on” time for simulation and experimental data.

[0103] Figure 15 Exemplary etch rates are shown for various argon biases of silicon and SiCl.

[0104] Figure 16A This is an exemplary diagram showing a substrate exposed to a 50V argon bias in an experiment.

[0105] Figure 16B This is an exemplary diagram showing a substrate exposed to a 200V argon bias in an experiment. Detailed Implementation

[0106] The following description sets forth numerous specific details to provide a thorough understanding of the presented implementation schemes. The disclosed implementation schemes may be implemented without some or all of these specific details. In other cases, well-known processing operations have not been described in detail to avoid unnecessarily obscuring the disclosed implementation schemes. While the disclosed implementation schemes are described in conjunction with specific implementation schemes, it should be understood that this is not intended to limit the disclosed implementation schemes.

[0107] Semiconductor processing typically involves various etching operations. An exemplary technique for processing and forming 3D structures involves reactive ion etching (RIE), which produces directional etching and sidewall passivation. Generally, RIE produces reactive materials, such as halogenated materials from fluorine-containing compounds, chlorine, or hydrogen bromide; and ions, such as helium and / or argon for directional etching; and various materials for passivating sidewall surfaces. However, as the etching depth increases, depth loading occurs in features with different aspect ratios, partly because the material collides with the sidewalls of the feature apertures as it is delivered to the bottom of the feature. Depth loading also occurs due to various isolated regions (such as features with wide feature openings) and dense regions (such as features with narrow feature openings). A feature with a “narrow” opening can be defined as a feature whose opening diameter or linewidth is relatively smaller than that of a “wide” feature. The opening diameter or critical dimension of a wide feature can be at least 1.5 times, or at least 2 times, or at least 5 times, or at least 10 times, or greater than 10 times the critical dimension of a narrow feature. Examples of “narrow” features include those with an opening diameter between about 1 nm and about 10 nm. Examples of “wide” features include those with an opening size on the scale of about several hundred nanometers to about 1 micrometer.

[0108] Etching processes typically involve exposing the material to be etched to a combination of etching gases to remove it. However, this removal may not be self-limiting and, in some cases, may etch beyond what is desired or result in undesirable feature profiles. As feature sizes shrink, the need for atomic-scale processes, such as atomic layer etching (ALE), is growing. ALE is a technique for removing thin layers of material using a sequential cycle of self-limiting reactions in nominally self-limiting steps, resulting in numerical and small variations in film thickness. This process is characterized by smoothness and conformability, and, in some cases, directionality.

[0109] Atomic layer etching (ALE) can be used in advanced semiconductor manufacturing (e.g., technology nodes smaller than about 10 nm) for the removal of overlays or pattern-defining etching of ultrathin material layers with atomic-scale depth resolution and control. Generally, any suitable technique can be used to perform ALE. Examples of atomic layer etching techniques are described in U.S. Patent No. 8,883,028, published November 11, 2014, and U.S. Patent No. 8,808,561, published August 19, 2014, which are incorporated herein by reference for the purpose of describing exemplary atomic layer etching and etching techniques. In several embodiments, ALE can be performed using plasma or thermal methods.

[0110] ALE can be performed cyclically. The concept of an “ALE cycle” relates to the discussion of several embodiments herein. Typically, an ALE cycle is a minimal set of operations used to perform a single etching process (e.g., etching a single layer). The result of a cycle is the etching of at least some film layers onto the substrate surface. Typically, an ALE cycle includes a modification operation that forms a reactive layer, followed by a removal operation that removes or etches only this modified layer. The cycle may include certain auxiliary operations, such as scavenging one of the reactants or byproducts. Typically, a cycle includes one example of a unique series of operations. For example, an ALE cycle may include the following operations: (i) supplying reactant gases, (ii) purging reactant gases from the chamber, (iii) supplying a removal gas and optionally plasma, and (iv) purging the chamber. In some embodiments, etching may be performed nonconformally. Figure 1 Two exemplary schematic diagrams of the ALE cycle are shown. Figures 171a-171e illustrate a general ALE cycle. In 171a, a substrate is provided. In 171b, the surface of the substrate is modified. In 171c, preparation for the next step is made. In 171d, the modified layer is etched. In 171e, the modified layer is removed. Similarly, figures 172a-172e show examples of an ALE cycle for etching a silicon film. In 172a, a silicon substrate comprising many silicon atoms is provided. In 172b, the reactant gas chlorine is introduced into the substrate, which modifies the surface of the substrate. The schematic diagram in 172b shows, as an example, some chlorine being adsorbed onto the surface of the substrate. Although... Figure 1 Chlorine is described, but any chlorine-containing compound or suitable reactant can be used. In 172c, the reactant gaseous chlorine is purged from the chamber. In 172d, the gaseous argon is removed using a directed plasma, such as that produced by Ar... +The plasma material and arrows indicate that ion bombardment is performed to remove the modified surface of the substrate. Ion bombardment is performed continuously in low-energy ALE under processing conditions that avoid sputtering of the substrate. In this operation, a bias is applied to the substrate to attract ions toward it. Because power is continuously delivered in this removal operation, the bias power is typically set to avoid sputtering. Therefore, the power applied to the bias is typically in the range of less than about 100V. The bias power depends on the material to be etched; for example, for germanium, the bias power may be between about 10V and about 35V, but for silicon, the bias power may be between about 35V and about 65V. In these examples, germanium sputters at bias power greater than 35V, and silicon sputters at bias power greater than 65V. Therefore, the bias power is typically maintained at a low level to avoid sputtering and to avoid damage to the substrate and surrounding materials. In these examples, the "bias window" of minimum bias power is the minimum bias power required to provide sufficient energy to the substrate to remove the modified material. Therefore, with continuous bias power delivery for germanium at less than 20V and for silicon at less than 35V, the modified surface will not have sufficient energy to be removed from the substrate. In 172e, a purging chamber is used to remove byproducts.

[0111] The cycle can partially etch material from about 0.1 nm to about 50 nm, or material between about 0.1 nm and about 20 nm, or material between about 0.1 nm and about 2 nm, or material between about 0.1 nm and about 5 nm, or material between about 0.2 nm and about 50 nm, or material between about 0.2 nm and about 5 nm. The amount of material etched in the cycle can depend on the purpose of etching in a self-limiting manner. In some embodiments, the ALE cycle can remove less than a single layer of material.

[0112] ALE processing conditions (e.g., chamber pressure, substrate temperature, plasma power, frequency and type, and bias power) depend on the material to be etched, the composition of the gas used to modify the material to be etched, the material beneath the material to be etched, and the composition of the gas used to remove the modified material. However, the combination of these factors makes performing ALE to etch a wide variety of materials challenging.

[0113] Performing ALE in a self-limiting manner without sputtering various materials is challenging and is often limited by certain processing conditions because the bias power is usually kept at a low level to avoid sputtering and damaging the substrate.

[0114] When feature sizes shrink to less than 10 nm feature widths, a 1 nm critical size variation between features can cause significant changes in aspect ratios between features, and a depth loading effect is observed in etching processes performed by conventional ALE (low-energy ALE) with continuous bias. During etching, the amount of material etched per cycle in deeper trenches is less than that in shallower trenches. In some cases, even within a single feature, the amount of material etched per cycle at the bottom of the feature is less than that near the top of the feature. Without being bound by a specific theory, it is generally believed that to achieve the self-confining properties of ALE in extreme 3D structures, it may be necessary to change the ion energy supplied from the plasma. However, for substrates with features of various aspect ratios, if the ion energy is chosen to be sufficient for etching features with large feature openings using ALE, features with narrower feature openings will receive ions with less energy and flux, thus insufficient for etching smaller features. However, if a larger ion energy is chosen to effectively etch features with narrow feature openings, the larger features will experience much higher ion energies, thereby sputtering the surface of the larger features and eliminating the self-confining aspect of ALE. This depth loading effect manifested in 3D structures indicates that the etch rate depends on the geometry of the feature.

[0115] There are several reasons why geometry dependence may exist during etching. One example of a potential challenge is that the charging effect caused by the generation of positive ions can lead to the accumulation of certain positive ions at or near the feature openings of high aspect ratio features due to the narrow feature openings. This results in a charge difference within the feature depth, where the feature openings are more positively charged than the bottom of the feature. Consequently, there is a repulsion between the incoming positively charged ions used to remove the modified surface and the positively charged feature openings, resulting in uneven removal of the modified surface at the bottom of the feature.

[0116] Given the introduction of many new materials into integrated circuit processing and the large number of processing parameters (gas pressure, wafer temperature, plasma power, ion energy, etc.), achieving ALE processing that etches specific materials in a layer-by-layer self-limiting manner without sputtering and avoids charging effects in high aspect ratio features is challenging.

[0117] The document provides a method for controlled atomic layer etching using high energy. The disclosed embodiments involve exposing the surface of the material to be etched to a modifying gas to modify the surface and form a modified surface, and exposing the modified surface to high-energy particles to preferentially remove the modified surface relative to the underlying unmodified surface, the high-energy particles having ion energies sufficient to overcome the average surface binding energy of the underlying unmodified surface.

[0118] For example, the substrate may contain a material to be etched, which has an average surface binding energy (ALE). The material to be etched comprises various material layers. If there is a self-confining aspect of atomic layer etching (ALE), the modifying gas modifies the surface of the material to be etched during exposure to a modifying gas, such that the exposed surface is modified but the underlying material is not modified. When the modified material is exposed to high-energy particles, such as ions, electrons, neutrons, photons, or other substances, the high-energy particles remove the modified surface and leave the underlying unmodified surface, maintaining the self-confining aspect of the ALE. The high-energy particles are delivered at high energies, which can be sufficient to overcome the average surface binding energy of the underlying unmodified surface of the material to be etched. That is, in some embodiments, if high-energy particles are delivered to the surface in large doses, such as delivering many high-energy particles at once, the high-energy particles break the bonds of the underlying material, thereby sputtering the material beneath the modified surface and minimizing the self-confining aspect of the ALE. In contrast, the disclosed embodiments involve modulating the energy of the high-energy particles by the dose delivered, to compensate for the high energy by delivering small doses. In low-energy ALE, a high dose is delivered to compensate for the low energy, meaning high-energy particles are delivered at a low energy level, but the high dose is maintained. This still removes only the modified surface without affecting the underlying unmodified surface, thus maintaining the self-confining nature of the ALE. However, in high-energy ALE, a low dose is delivered to compensate for the high energy, meaning a low dose of high-energy particles is delivered at a much higher energy level than in low-energy ALE (therefore, more modified surface is removed than in low-energy ALE with the same dose) so that the etching still maintains its self-confining properties.

[0119] Various embodiments involve modifying the surface of the material to be etched and exposing the modified surface to a reduced dose of activated material generated from an activation removal gas to remove part or all of the modified surface. The reduced dose can be achieved in various ways. One way to provide a reduced dose of activated material is by delivering the activated material in time-separated pulses, which may involve pulsed plasma power, bias, gas flow, or more synchronously or asynchronously between high / low and on / off processes. The reduced dose is defined as a dose with reduced delivery effect that has energy higher than the sputtering threshold energy of the material to be etched when continuously delivered to the modified surface. In some cases, the sputtering threshold is the surface binding energy of the material to be etched.

[0120] Another way to deliver a reduced dose is to alter the ion flux of the activated material, but with an unreduced dose having energy greater than the surface binding energy. Another example of delivering a reduced dose is to alter the duration for which the modified surface is exposed to the reduced dose of the activated material. This duration may be insufficient to remove the modified surface. For example, a single pulse of reduced dose lasting a specific time period may be insufficient to remove the modified surface, but delivering two or more pulses of reduced dose lasting the same time period over time may be sufficient to remove the modified surface. Another example involves delivering a reduced dose to the modified surface by altering the acceleration of ions generated in the activated material. Another example involves delivering a reduced dose by altering the bias voltage applied to a substrate support and used to directionally deliver the activated material to the modified surface. In some embodiments, the reduced dose is sufficient to remove the modified surface but not sufficient to sputter the underlying unmodified material.

[0121] The aforementioned techniques for ALE (Alternating Layer Removal) are based on obtaining an "ALE window"—a bias voltage applied to a substrate support during the ALE removal operation—to provide sufficient energy to the modified surface to remove molecules from the substrate (lower limit of the ALE window). However, the energy provided is below a threshold energy for the modified surface (upper limit of the ALE window); exceeding this threshold energy would cause physical sputtering of material beneath the modified surface and / or the surface itself. Such techniques focus on providing low bias voltages and low plasma power to avoid sputtering of material on the surface, ensuring that ALE removal is self-limiting and therefore controllable in layer-by-layer processing.

[0122] In contrast, the disclosed embodiments involve operating with high plasma power, high bias voltage, or both. It should be understood that the terms "bias power" and "bias voltage" are used interchangeably herein to describe the voltage at which the substrate support is set when a bias is applied to it. Threshold bias power or threshold bias voltage represents the maximum bias voltage that can be applied to the substrate support before sputtering of the material on the substrate surface on the substrate support. Therefore, threshold bias power depends in part on the material to be etched, the gas used to generate the plasma, the plasma power used to ignite the plasma, and the plasma frequency. The bias power or bias voltage described herein is measured in volts and is represented by "V" or "Vb", where b represents bias. Electron volts (eV) described herein are the amount of energy gained by an electron after being accelerated through a potential difference of 1 volt. The disclosed embodiments can operate at low duty cycle pulses (e.g., between 1% and 10% of the duty cycle). The disclosed embodiments overcome charging problems because the high energy delivered to the activated removal gas is sufficient to overcome repulsion effects. While it's conceivable to attempt to overcome the repulsion effect using higher bias power in low-energy ALEs, this would lead to sputtering or substrate damage due to long exposure times, thus negating the self-confining characteristics of the ALE. In contrast, pulsed ALEs at high energies can overcome the repulsion effect and maintain the self-confining properties of the ALE without sputtering.

[0123] The following will explain further. Figure 13 As shown, it is generally expected that the removal of modified membranes using short operating cycles will be incomplete.

[0124] However, the disclosed implementations involve utilizing short duty cycles as a technique to perform ALE using high energy. It is not intended to be limited to any particular theory; it is generally believed that ALE removal operations are time-dependent.

[0125] This example involves a silicon surface modified with chlorine plasma, and the modified surface with SiCl can be removed using argon plasma. It should be understood that this is provided only as an example, and the expressions below relate to any suitable material for plasma (alternating chlorine) etching and to the energy material used for ALE (alternating argon plasma), which typically includes both low-energy and high-energy ALE.

[0126] Let N0 represent the total number of surface sites on the substrate. The total number of surface sites is obtained by the following formula:

[0127] N0=N+S Formula 1

[0128] Where N represents the total number of unreacted sites (sites where SiCl is retained on the surface), and S represents the total number of reacted sites (sites where only the underlying Si is retained).

[0129] The reaction of chlorine desorption on the substrate is represented by the following equation:

[0130] Si-Si Cl (s) + Ar + ions → Si(s) + SiCl(g) Equation 2

[0131] This formula describes ion-assisted desorption and assumes no reverse reaction, where the rate efficiency Y = yield per ion reaction.

[0132] Assume F represents the ion flux, with units of ions / cm³. 2 -sec.

[0133] Therefore, the expression for the rate is as follows:

[0134]

[0135] The derivative of [S] at time t is expressed by the following formula, assuming that k is related to [S] and t:

[0136]

[0137] The proportion of the surface area that has already reacted is represented by θ as follows:

[0138]

[0139]

[0140] Equation 5A is rewritten as Equation 5B. In Equation 5B, θ(t) represents the amount of removal as a function of time, where Y(ε) is the ion yield of the product removed (0.1 ions at 0 eV). d is in units of 1 / cm 2 Surface density, F is the ion flux (which is approximately ~1E¹⁶ / cm² at 50 eV in some devices). 2 s), where t is the time when the argon ions are "on", such as a 0.2-second dose for a 10% duty cycle of a 2-second operation.

[0141] The following will explain Figure 12B This shows an example of etching for each cycle of ALE using the inverse correlation function of Equation 5A. Not bound by any particular theory, it is generally believed that momentum transport is more efficient at higher energies, thus requiring fewer ions. Figure 4I and 4J Examples are provided. Figure 4I In this process, a low ion energy of 50 eV, delivered to the modified surface, is used to remove the modified surface using argon transported at a velocity of 13000 m / s, where Y ~ 0.1 SiClx / ion. Conversely, in Figure 4J In this process, a high ion energy of 300 eV, delivered to the modified surface, is used for argon removal at a velocity of 33,000 m / s, where Y ~ 0.5 SiClx / ion. Therefore, for a surface that requires 10 ions to remove using low ion energy, the same surface can be removed using only two ions using high ion energy.

[0142] Not bound by a specific theory, although sputtering is enhanced with increasing ion energy, the SiCl surface etches faster than the underlying Si surface, thus contributing little to the etching amount until the reactive layer is removed. If the exposure time is very short, the reactive layer remains for most of the removal time. For example, Figure 15 An example showing the functional relationship between etching rate and argon bias voltage is provided, thus SiCl(1501) is etched faster than Si(1502) at all energies.

[0143] Figure 16A This example demonstrates a low-energy ALE using a 50V bias at 1.5 seconds / cycle, resulting in a smoother surface, a larger exposure time window, and higher resolution / cycle, which causes less damage to the underlying layer. Gray represents TEOS on the substrate. Green represents the underlying material. Figure 16B Examples of the same substrate structure exposed to high-energy pulsed ALE are shown, resulting in: higher yields with similar synergistic effects; improved aspect ratio-dependent etching (ARDE) due to a narrower ion angular distribution function (IADF) (8° at 50 eV and 2° at 500 eV); smaller charging effects; and less redeposition and ion scattering. High-energy ALE can be delivered in short pulses, which would be useful in CCP reactors. High-energy ALE enables a larger ion energy window.

[0144] The disclosed embodiments are suitable for etching a variety of materials, including metals, metallic materials, dielectric materials, semiconductor materials, insulating materials, etc. Non-limiting examples include silicon, silicon oxide, silicon nitride, tungsten, carbon, germanium, metal oxides, and metal nitrides (such as titanium nitride, aluminum nitride, etc.). Although the examples provided herein are for etching silicon, it should be understood that the disclosed embodiments can be used to etch a variety of materials, and the modifying gas chemicals, removal gas chemicals, and processing conditions may vary depending on the material to be etched.

[0145] The methods and apparatus described herein are for performing high-energy atomic layer etching (ALE). High-energy ALE can be used by compensating for high energy with a low dose. In contrast, conventional ALE performed at low energies (low-energy ALE) involves utilizing a high dose of low energy. The dose is defined as the number of ions used during the removal operation of the ALE.

[0146] In some embodiments, high-energy ALE can be performed using an etching process referred to herein as pulsed atomic layer etching. In some cases, the terms "high-energy ALE" and "pulsated ALE" are used interchangeably. A single high-energy ALE cycle comprises at least two operations: 1) surface modification with continuous or pulsed plasma; and 2) removal of the modified surface to remove the modified film using one or more pulsed energy sources, such as bias power, or radio frequency plasma power, or both, or optical energy. Multiple pulses can be used in either the surface modification and / or removal operations within a single high-energy ALE cycle. For example, in some embodiments, 100 or more pulses of bias power pulses can be performed during removal. During removal, bias or power, or both, can be pulsed, and in some cases, other energies such as photonic energy can be used. When both bias and plasma power are pulsed, the pulses can be synchronous or asynchronous. The pulse frequencies can be the same or different. The pulsed conditions can be finely adjusted, including the on / off state of the pulse, or the application of the pulse between low and high power or voltage, the frequency of the pulse, the duty cycle of the pulse, and the duration of the pulse, depending on the modifying chemicals, the degassing chemicals, the material to be etched, the substrate feature profile, and the application of the disclosed embodiments.

[0147] The disclosed embodiments can be performed in a high-energy ALE state (regime) using higher ion energies, ranging from about 10 to about 20 times higher than those of low-energy ALE processing. Some embodiments are performed by synchronously pulsed power of the inductively coupled current and by applying a bias to the substrate through a voltage delivered to the substrate at very low duty cycles, ranging from about 1% to about 10%. The new processing state enables the etching of extremely narrow features with high aspect ratios (e.g., greater than about 30:1), achieving low loading effects and reducing or eliminating lateral etching.

[0148] Pulsed ALE can involve both pulsed plasma and pulsed ion bias, allowing pulsed plasma to be applied during both modification and removal.

[0149] Pulsation during surface modification allows for control over the effective plasma time and can be tailored to the equipment used for the modification. Pulsation during removal can be used to remove the modified surface using high energy. In some embodiments, pulsesation during removal may comprise both pulsed RF plasma and pulsed bias power, and the pulses may be synchronized so that the RF plasma power pulses and the bias power pulses are pulsed at the same pulse frequency and using the same duty cycle.

[0150] Pulsed ALE using pulsed energy provides a way to extend the self-confined synergistic window. Synergy implies favorable etching due to the interaction of both surface modification and removal operations. The extended synergistic window reaches a higher bias / energy state, which compensates for the ion energy / flux loss due to ion scattering associated with extremely narrow 3D structures before reaching the etch front. Therefore, high-energy ALE provides an operating state that results in the same etching / cycling across a wide range of critical dimensions and aspect ratios in a self-confined reaction.

[0151] High-energy ALE extends the cooperative behavior of atomic layer etching to the self-limiting energy window. Under continuous ion bombardment, the sputtering threshold voltage of silicon can, for example, exceed 100V. That is, at a bias power greater than 100V, the silicon surface will be sputtered. Pulsation modes generate plasma and ions at a given frequency and duty cycle. By utilizing power / bias pulsed modes at lower duty cycles, the threshold sputtering bias can be increased to higher bias powers. Therefore, compared to low-energy ALE, bias pulsed modes increase the range and size of the self-limiting energy window by at least an order of magnitude.

[0152] Without being bound by any specific theory, it is believed that pulsed atomic layer etching (ALE) is achieved by reducing the ion flux through pulsed pulses. Since flux equals throughput multiplied by time, it represents the ion dose. As a simple estimate, the dose reduction can be calculated as the ratio of the duty cycle to the step time. For example, for a 10% duty cycle, with a pulsed dose time of 2 seconds instead of 5 seconds, the effective flux reduction is 94%. Therefore, in this example, the wafer is exposed to 0.06 times the original ion dose used in low-energy ALE. The amount of etching per cycle depends on the ion dose and ion energy. Generally, reducing the dose results in a lower amount of etching. Without being bound by any specific theory, it is believed that a lower dose can be compensated for by selecting a higher ion energy.

[0153] Compared to reactive ion etching, high-energy ALE uses two self-confining steps to independently control reactant delivery and surface reaction. A pulsed bias mode redefines the self-confining window of the ALE to provide a state for ALE-etched 3D structures where the bias power or RF power is independent of trench size and aspect ratio. The provided implementations are suitable for both full-scale etching and patterned substrate etching. In some implementations, the bias window of the high-energy ALE may have a non-sharp maximum value so that the maximum bias used by the high-energy ALE that does not cause sputtering is a series of values ​​rather than a single set value.

[0154] The disclosed embodiments extend the ALE energy window, which is referred to as the range of voltages that make etching substantially self-limiting. In some embodiments, the ALE energy window is determined by evaluating an etch versus voltage graph for each cycle, and in some embodiments, the ALE energy window involves identifying the location of an etch plateau in each cycle, with the energy window calculated as ± approximately 10% of the plateau value. In some embodiments, this can be done by determining inflection points: determining the inflection point where the positive slope becomes a slope of 0 (minimum), and determining the inflection point where the slope of 0 becomes a positive slope (maximum). In some embodiments, the ALE energy window is the range of voltages that can be applied to the substrate to remove material from the modified surface without sputtering the substrate. The voltage range includes a minimum voltage and a maximum voltage, the minimum voltage being the minimum voltage required to remove the modified material from the modified surface, and the maximum voltage being the maximum voltage the substrate can withstand before the removal gas sputters onto the substrate.

[0155] In low-energy ALE, the bias window is typically narrower within the range of bias voltages that tend to be reduced to avoid sputtering damage to the substrate. The duration of energy applied to the remover gas can be altered by changing the duty cycle; as the duty cycle decreases, and therefore as the duration of energy exposure decreases, the range and size of the bias window increase so that the bias voltage that can be applied to the substrate can be as large as 10 to 20 times that used during low-energy ALE. Generally, it can be expected that using higher energy to the remover gas during removal will result in more damage; therefore, the amount of energy can be reduced by decreasing the bias voltage or RF plasma power to attempt to mitigate damage. However, without being bound by a specific theory, it is believed that the amount of energy accumulated over time for each set of modifying chemicals, remover gas chemicals, and substrate material chemicals is used to provide the bias window for removing the modified material. In low-energy ALE, certain limitations on bias power are observed to avoid sputtering. However, in high-energy ALE, since the bias is delivered in a pulsed manner over time, the bias power can be as large as 10 or 20 times that used during low-energy ALE. It should be noted that although high-energy ALE is performed in a pulsed manner, other techniques can be used to deliver high energy during ALE in some embodiments. While low-energy ALE at the bias power used in high-energy ALE can cause sputtering, high-energy ALE isolates the high bias power over time, thereby preventing any sputtering on the substrate. The combination of applied energy and time (e.g., duty cycle) and flux (depending on the modifying chemicals, remove gas chemistry, and the material to be etched) can be modified to maximize the bias window using some of the disclosed embodiments.

[0156] The disclosed implementation may be particularly well-suited for features used in etching FinFET applications. Figure 2An exemplary FinFET structure (fin field-effect transistor) 200 is shown. The substrate 202 may be a semiconductor substrate. In this structure, surfaces 214a and 204a correspond to the source region, while 214b and 204b correspond to the drain region. A pad 212 separates the semiconductor material of the substrate 202 from the insulating material 230, such as silicon oxide. Thin gate dielectric layers 206b and 206a may be deposited over the insulating material 230 to separate the insulating material 230 from the gate, which includes spacers 210, a gate electrode 208, and a gate electrode barrier layer 208a. Electrical contacts 250 are formed above the upper portion of the gate. Some of the disclosed embodiments can be used to define fin / shallow trench isolation for trenches formed in the substrate 202, where depth loading is minimal. Furthermore, some of the disclosed embodiments can be adapted for dummy gate removal during gate electrode deposition.

[0157] Figure 3A and 3B The flowchart shows the operation of the method according to some of the disclosed implementation schemes. Figure 3A and 3B The operation can be carried out at a processing chamber pressure between about 1 mTorr and about 100 Torr, such as between about 1 mTorr and about 1 Torr, such as about 50 mTorr. Figure 3A and 3B The operation can be performed at a substrate temperature between about 0°C and about 120°C.

[0158] The following discussion should be understood as follows: Figure 3A Operations 302, 304, 306, 310, and 312 can correspond to and / or equal to... Figure 3B Operations 302, 304, 306, 310, and 312 are described. In operation 302, a substrate is provided to the processing chamber. The substrate may be a silicon wafer, such as a 200-mm wafer, a 300-mm wafer, or a 450-mm wafer, comprising a wafer having one or more layers of material (such as dielectric, conductive, or semiconductive) deposited thereon. The patterned substrate may have "features," such as vias or contact holes, characterized by one or more narrow and / or recessed openings, contractions within the feature, and a high aspect ratio. The feature may be formed in one or more of the aforementioned film layers. One example of a feature is a hole or via in a layer in or on a semiconductor substrate. Another example is a trench in a substrate or layer. In various embodiments, the feature may have an underlying layer, such as a barrier layer or an adhesive layer. Non-limiting examples of the underlying layer include dielectric and conductive layers, such as silicon oxide, silicon nitride, silicon carbide, metal oxides, metal nitrides, metal carbides, and metal layers.

[0159] In some embodiments, the substrate has no features and the surface of the substrate is a cover layer of material. In some embodiments, the substrate includes features of various sizes. In many embodiments, the substrate manufactured by performing the disclosed embodiments may depend on the aspect ratio of the features on the substrate prior to performing the disclosed embodiments. In some embodiments, the features on the substrate disclosed in operation 301 may have an aspect ratio of at least about 2:1, at least about 3:1, at least about 4:1, at least about 6:1, at least about 10:1, at least about 30:1, or higher. Features may also have sizes close to the aperture, such as between about 5 nm and 500 nm, such as an aperture diameter or linewidth between about 25 nm and about 300 nm. The disclosed method can be performed on a substrate with features having an aperture of less than about 20 nm.

[0160] Vias, trenches, or other recessed features can refer to unfilled features or characteristics. According to various embodiments, the feature profile may gradually narrow and / or include overhangs at the feature opening. A concave profile is a profile that narrows from the bottom, closed end, or interior of the feature to the feature opening. Concave profiles can be generated by asymmetric etch kinetics during patterning and / or by overhangs resulting from non-conformal film steps during previous film deposition (such as diffusion barrier layer deposition). In various examples, the width of the feature in the opening at the top of the feature is smaller than the width of the middle and / or bottom of the feature.

[0161] In operation 304, the substrate is exposed to a modifying gas for a period sufficient to at least modify the surface of the substrate. In operation 304, etching chemicals are introduced into the processing chamber. As described herein, in some embodiments involving atomic layer etching utilizing plasma, chemicals may be introduced into the processing chamber to stabilize the reactor or processing chamber before processing the substrate or wafer during the material introduction operation into the processing chamber. The stabilization processing chamber may use the same flow rate, pressure, temperature, and other conditions as the chemicals used in subsequent operations. In some embodiments, the stabilization processing chamber may involve different parameters. In some embodiments, a carrier gas (such as N2, Ar, Ne, He, or combinations thereof) is continuously flowed during operation 304. In some embodiments, the carrier gas is used only during the removal period. In some operations described below, the carrier gas may be used as a purge gas.

[0162] The modification operation forms a thin, reactive surface layer that is more easily removed in subsequent removal operations than the unmodified material. In the modification operation, chlorine may be introduced into the processing chamber to chlorinate the substrate. Chlorine is used as an exemplary etchant material in the disclosed embodiments, but it should be understood that in some embodiments, different etch gases are introduced into the processing chamber. The etch gas may be selected depending on the type of substrate to be etched and the chemicals used. In some embodiments, plasma may be ignited, and then chlorine reacts with the substrate to perform the etching process. In some embodiments, chlorine may react with the substrate or adsorb onto the substrate surface. In many embodiments, chlorine in gaseous form is introduced into the processing chamber, and chlorine may optionally be accompanied by a carrier gas, which may be any of the carrier gases described above. The material generated from the chlorine plasma may be generated directly by forming plasma in a processing chamber containing the substrate, or remotely generated in a processing chamber without a substrate and then supplied to the processing chamber containing the substrate. In some embodiments, plasma is not used and chlorine may be thermally introduced into the processing chamber.

[0163] In various embodiments, the plasma can be inductively coupled plasma or capacitively coupled plasma. Inductively coupled plasma can be configured to be between about 50 W and about 2000 W. In some embodiments, a bias voltage between about 0 V and about 500 V is applied.

[0164] In several embodiments, plasma is ignited to facilitate modification of the substrate surface. In some embodiments, a modifying gas is ignited in a remote plasma chamber to generate plasma material, which is then transported to a processing chamber containing the substrate. In some embodiments, the modifying gas is ignited within the processing chamber.

[0165] In various embodiments, the plasma is pulsed during operation 304. The plasma can be pulsed between an ON state and an OFF state, with the ON state plasma power ranging from approximately 50 W to approximately 2000 W, and the OFF state plasma power being 0 W. In some embodiments, the plasma can be pulsed between a low state and a high state, with the low state plasma power ranging from approximately 10 W to approximately 100 W, and the high state plasma power ranging from approximately 900 W to approximately 1500 W.

[0166] Pulsation can be performed at pulse frequencies between approximately 10 Hz and approximately 200 Hz. The duty cycle for plasma pulsedness of modified gases can be between approximately 1% and approximately 20%. It should be understood that pulsedness can involve repeated cycles, each cycle lasting for a period T. The time period T includes the duration of the pulse ON time (the duration the plasma is in the ON state) and the duration of the OFF time (the duration the plasma is in the OFF state) within a given period. The pulse frequency can be understood as 1 / T. For example, for a pulsed period T = 100 μs, the frequency is 1 / T = 1 / 100 μs or 10 kHz. The duty cycle or duty cycle is the percentage or proportion of the energy source being in the ON state during the period T such that the duty cycle or duty ratio is the pulse ON time divided by T. For example, for a pulsed period T = 100 μs, if the pulse ON time is 70 μs (so that the duration of the energy source being ON in one period is 70 μs) and the pulse OFF time is 30 μs (so that the duration of the energy source being OFF in one period is 30 μs), then the duty cycle is 70%.

[0167] Figure 4H Examples of various duty cycles that can be used for ALE cycles are provided, including 3%, 10%, 40%, and 100% (100% is ALE performed in a fully coordinated manner but at low continuous energy). Figure 4H The diagram shows the "ON" time corresponding to when Ar is turned on.

[0168] In some embodiments, the plasma is pulsed to allow higher energy to be delivered to the modifying gas. In some embodiments, the plasma can be pulsed to enable the equipment used to generate the plasma to operate under specific conditions that address equipment limitations. For example, for equipment unable to deliver plasma power for short, continuous durations, the dose that can be delivered during a short, continuous duration is broken into multiple pulses over a longer period so that the total plasma ON time is the same as the short, continuous duration, facilitating the delivery of plasma power sufficient to modify most or all of the active sites on the substrate surface. For example, if the minimum amount of time required for continuous modification of a silicon surface by chlorine is 400 milliseconds, but the equipment cannot deliver chlorine gas and plasma power for such a short and continuous period, then this 400-millisecond period can be obtained within 2 seconds using a continuous chlorine gas flow and four cycles of 100-millisecond pulsed plasma power followed by 400-millisecond no-plasma power.

[0169] In operation 306, the treatment chamber is optionally purged to remove excess modified gas molecules that have not modified the substrate surface. During the purging operation, unbonded activated chlorine material can be removed from the treatment chamber. This can be accomplished by purging and / or venting the treatment chamber to remove the activated material without removing the absorbed layer. Material generated in the chlorine plasma can be removed by simply stopping the plasma and allowing the remaining material to decay, optionally in conjunction with purging and / or venting the treatment chamber. Purging can be performed using any inert gas such as N2, Ar, Ne, He, and combinations thereof.

[0170] In operation 308a, an activation gas is delivered to the substrate and activated material is generated from the activation gas using an activation source. This activated material is used to remove the modified surface. In operation 308a, the substrate is exposed to a high-energy dose of the activated material to etch the substrate. The activated material can be delivered via a pulsed energy source (such as RF plasma power, bias power, photons, or other energy sources). In some embodiments, more than one high-energy dose is provided during operation 308a in one ALE cycle. The high-energy dose is provided at an energy higher than the threshold energy required to sputter the modified surface and is sustained for a duration insufficient to remove the modified surface using a single energy dose. The activation gas can be an inert or precious gas, such as argon, helium, neon, krypton, xenon, or combinations thereof. In some embodiments, the energy of a single high-energy dose is at least two to at least 15 times the sputtering threshold energy. For example, in some embodiments, for etching silicon using the disclosed embodiments, a high energy dose is provided at a bias power of at least 150 eV, or at least 500 eV, or at least 1000 eV, or between 100 eV and about 1500 eV, relative to an exemplary threshold sputtering bias power of 65 V.

[0171] In some embodiments, one or more energy sources are pulsed, while simultaneously delivering one or more energy sources continuously. For example, in some embodiments, the bias power is pulsed while the RF plasma power is continuous. In some embodiments, the RF plasma power is pulsed and the bias power is pulsed. In some embodiments, the RF plasma power is pulsed and the bias power is continuous. In many embodiments, in the case of pulsed power, pulsed power can occur between ON and OFF states, or between low and high states.

[0172] The pulsed plasma power and bias power (including frequency and duty cycle) depend on the material to be etched. The following ranges can be used to remove silicon using chlorine as a modifying gas: For RF plasma power, when pulsed between ON and OFF states, the power during the ON state can be between approximately 50 W and approximately 900 W. For RF plasma power, when pulsed between low and high power, the power during the high power state can be between approximately 900 W and approximately 1500 W, and the power during the low power state can be between approximately 10 W and approximately 100 W. For bias power, when pulsed between ON and OFF states, the bias power can be approximately 10 to approximately 20 times that of a low-energy ALE. For etching silicon, for a duty cycle between approximately 1% and approximately 10%, the bias power during the ON state can be between approximately 100 V and approximately 1500 V. Regarding the bias power, when pulsed between high and low power, for duty cycles ranging from about 1% to about 10%, the high-power bias power can be between about 500V and about 1500V, and for duty cycles ranging from about 1% to about 10%, the low-power bias power can be between about 100V and about 300V. In some embodiments, the bias and RF plasma power are pulsed at least about 100 times during one ALE cycle.

[0173] In one example, the following processing conditions can be used to etch silicon:

[0174] Table 1. Exemplary processing conditions for high-energy ALEs of silicon

[0175]

[0176] In some embodiments, the RF plasma power is continuous, but the bias power is pulsed between ON and OFF states. In some embodiments, when the RF plasma power is continuous, the bias power is pulsed between high and low power. In some embodiments, when the RF plasma power is pulsed between ON and OFF states, the bias power is pulsed between ON and OFF states. In some embodiments, when the RF plasma power is pulsed between high and low power, the bias power is pulsed between ON and OFF states. In some embodiments, when the RF plasma power is pulsed between ON and OFF states, the bias power is pulsed between high and low power. In some embodiments, when the RF plasma power is pulsed between high and low power, the bias power is pulsed between high and low power. In some embodiments, the high bias power can be as high as the maximum bias power sufficient to remove the modified surface without sputtering, and the low bias power can be as low as the minimum bias power sufficient to remove the modified surface for a given RF plasma power and duty cycle.

[0177] In some implementations, the pulsed RF power and bias power are synchronized such that the RF power is on when the bias power is on and off when the bias power is off; or the RF power is on when the bias power is high and off when the bias power is low; or the RF power is high when the bias power is on and low when the bias power is off; or the RF power is high when the bias power is high and low when the bias power is low.

[0178] In some implementations, the pulsed RF power and bias power are asynchronous, such that the RF power is off when the bias power is on, and on when the bias power is off; or the RF power is off when the bias power is high, and on when the bias power is low; or the RF power is low when the bias power is on, and high when the bias power is off; or the RF power is low when the bias power is high, and high when the bias power is low. In some implementations, the pulsed RF power frequency is the same as the pulsed bias power frequency. In some implementations, the pulsed RF power frequency is different from the pulsed bias power frequency.

[0179] Pulsation can be performed at frequencies between about 10 Hz and about 200 Hz (e.g., about 200 Hz). The duty cycle of plasma pulsed activation gas can be between about 1% and about 10%. In various embodiments, reducing the duty cycle increases the range and size of the bias window, thus a smaller duty cycle results in a wider bias window and a larger tolerance for the bias power applied to the substrate.

[0180] against Figure 3B In operation 308b, the modified surface is exposed to high-energy particles to etch the modified surface. The high-energy particles possess ionic energies higher than the average surface binding energy of the unmodified surface beneath the material to be etched. As described above for operation 308a, the high-energy particles can be delivered to the substrate in pulses. In some embodiments, the high-energy particles do not significantly sputter the underlying unmodified material. For example, in one cycle, the amount of underlying unmodified material sputtered by the high-energy particles during removal is less than about 10% of the total material removed by the high-energy particles.

[0181] In various embodiments, operation 308b involves exposing the modified surface to low ion energy such that the exposure of the modified surface is insufficient to remove at least 80% of the modified surface for a duration.

[0182] In operation 310, the treatment chamber is optionally purged to remove excess activation gases and reaction byproducts from the removal operation of operation 308a or 308b.

[0183] In operation 312, operations 304-310 are optionally repeated in several cycles. In various embodiments, the modification and removal operations may be repeated in several cycles, such as between about 1 cycle and about 200 cycles, or between about 1 cycle and about 150 cycles, or between about 1 cycle and about 70 cycles, or between about 1 cycle and about 40 cycles, or between about 1 cycle and about 30 cycles, or between about 1 cycle and about 20 cycles. Any suitable number of ALE cycles may be included to etch the desired amount of film. In some embodiments, ALE is performed in several cycles to etch the surface of the layer on the substrate between about to approximately The thickness is between [a certain value]. In some embodiments, the surface of the layer on the substrate etched in several cycles by the ALE is between approximately [a certain value]. to approximately The thickness between.

[0184] exist Figure 4A-4G Examples of various timing diagrams are depicted. While these diagrams show the RF plasma as off during surface modification, in many embodiments the plasma is turned on during surface modification. Figure 4A-4GIn all examples, the modifying gas is turned on and kept constant during surface modification, and turned off during the purging and removal phases; the removal gas is turned on and kept constant during removal, and turned off during the purging and removal phases. Although not shown, it should be understood that the carrier gas can flow continuously during the etching cycle. In some embodiments, the purging phase gas is the same as the removal gas, so the removal gas can be turned on during the purging phase until no plasma or bias power (not shown) is delivered.

[0185] Figure 4A The diagram shows two etching cycles: surface modification, cleaning, removal, and swirl. During the removal operation, the bias power is pulsed between ON and OFF, while the RF plasma remains constant. Although only four ON pulses are shown for the bias power during removal in one ALE cycle, multiple pulses and various duty cycles, such as those between 1% and 10%, can be used.

[0186] Figure 4B The diagram shows two etching cycles: surface modification, cleaning, removal, and swirl. During the removal operation, the RF plasma remains constant while the bias power is pulsed between low and high power. Although only four high-power pulses are shown for the bias power during removal in one ALE cycle, multiple pulses and various duty cycles, such as those between 1% and 10%, can be used.

[0187] Figure 4C The diagram shows two etching cycles: surface modification, sweeping, removal, and cleaning. During the removal operation, the bias power is pulsed between ON and OFF, and the RF plasma is also pulsed between ON and OFF during the removal operation. Although only four ON pulses are shown during removal in one ALE cycle, multiple pulses and various duty cycles, such as those between 1% and 10%, can be used. In this example, the RF pulses and bias power pulses are pulsed synchronously with the duty cycle at the same frequency.

[0188] Figure 4D The diagram shows two etching cycles: surface modification, sweeping, removal, and cleaning. During the removal operation, the bias power is pulsed between high and low power, and the RF plasma is also pulsed between ON and OFF. Although only four pulses are shown during removal in one ALE cycle, multiple pulses and various duty cycles, such as those between 1% and 10%, can be used. In this example, the RF pulses and bias power pulses are pulsed synchronously with the duty cycle at the same frequency.

[0189] Figure 4ETwo etching cycles are shown: surface modification, sweeping, removal, and cleaning. During the removal operation, the bias power is pulsed between ON and OFF, and the RF plasma is also pulsed between high and low power during the removal operation. Although only four pulses are shown during removal in one ALE cycle, multiple pulses and various duty cycles, such as those between 1% and 10%, can be used. In this example, the RF pulses and bias power pulses are pulsed synchronously with the duty cycle at the same frequency.

[0190] Figure 4F Two etching cycles are shown, involving surface modification, swirl, removal, and swirl again. During the removal operation, the bias power is pulsed between high and low power, and the RF plasma is also pulsed between high and low power. Although only four pulses are shown during removal in one ALE cycle, multiple pulses and various duty cycles, such as those between 1% and 10%, can be used. In this example, the RF pulses and bias power pulses are pulsed synchronously with the duty cycle at the same frequency.

[0191] Figure 4G This example shows two etching cycles: surface modification, cleaning, removal, and purging. During the removal operation, the bias power is pulsed between ON and OFF, and the RF plasma is also pulsed between ON and OFF during the removal operation. While only four bias power pulses (and only three RF plasma pulses) are shown during removal in one ALE cycle, multiple pulses and various duty cycles, such as those between 1% and 10%, can be used. In this example, the RF pulses and bias power pulses are pulsed synchronously with the duty cycle at the same frequency. In another example, the RF pulses and bias power pulses are asynchronous but have the same frequency, so that the bias power is on when the RF plasma is off, and off when the RF plasma is on.

[0192] Figure 4A-4G Examples of pulse timing in various pulsed ALE implementations are provided. It should be understood that many variations may be used in some of the disclosed pulsed ALE implementations.

[0193] This document provides embodiments for achieving etch selectivity. For example, etch selectivity can depend on the material to be etched, the remover and modifier gases used, and the bias power used during the pulse in the ON state. Therefore, a higher selectivity between the two materials can be observed at lower bias power, but a lower selectivity can be observed at higher bias power. Because the disclosed embodiments expand the bias window for operating self-limiting pulsed ALE, this allows for adjusting the etch selectivity of one material relative to another during pulsed ALE using various bias powers to obtain desired etch characteristics and, in some embodiments, desired feature profiles.

[0194] equipment

[0195] Inductively coupled plasma (ICP) reactors applicable to atomic layer etching (ALE) operations in certain embodiments are now described. Such ICP reactors are also described in U.S. Patent Application Publication No. 2014 / 0170853, filed December 10, 2013, entitled “IMAGEREVERSAL WITH AHM GAP FILL FOR MULTIPLE PATTERNING,” which is incorporated herein by reference in its entirety and for all purposes. Although ICP reactors are described herein, it should be understood that capacitively coupled plasma reactors may also be used in some embodiments. In some embodiments, electron cyclotron resonance plasma may be used.

[0196] Figure 5 A cross-sectional view of an inductively coupled plasma etching apparatus 500 suitable for implementing certain embodiments of this document is schematically shown, an example being Kiyo. TMThe reactor is manufactured by Lam Research Corp. in Fremont, California. The inductively coupled plasma device 500 includes a main processing chamber 501 structurally defined by chamber walls 501 and windows 511. Chamber walls 501 may be made of stainless steel or aluminum. Windows 511 may be made of quartz or other dielectric materials. An optional internal plasma grid 550 divides the main processing chamber 501 into an upper sub-chamber 502 and a lower sub-chamber 503. In most embodiments, the plasma grid 550 can be removed, thereby utilizing the chamber space formed by sub-chambers 502 and 503. A chuck 517 is positioned in the lower sub-chamber 503 near its bottom inner surface. The chuck 517 is configured to receive and hold a semiconductor wafer 519 on which etching and deposition processes are performed. The chuck 517 may be an electrostatic chuck used to support the wafer 519 when it is present. In some embodiments, an edge ring (not shown) surrounds chuck 517 and has an upper surface that is generally in the same plane as the top surface of wafer 519 (when the wafer is present above chuck 517). Chuck 517 also includes electrostatic electrodes for clamping and releasing the wafer. Filters and DC clamping power sources (not shown) may be provided for this purpose. Other control systems may also be provided for lifting wafer 519 away from chuck 517. Chuck 517 can be charged with RF power source 523. RF power source 523 is connected to matching circuit 521 via connector 527. Bias power can be delivered to chuck 517 to apply bias to the substrate. In various embodiments, the bias power can be set to a value between 0V (no bias) and approximately 2000V, or between 0V and approximately 1800V, or between 0V and approximately 1500V, or between 500V and approximately 1500V. Matching circuit 521 is connected to chuck 517 via connector 527. In this way, the RF power source 523 is connected to the chuck 517.

[0197] The element used for plasma generation includes a coil 533 located above window 511. In some embodiments, the disclosed embodiments do not use a coil. The coil 533 is made of a conductive material and includes at least one full turn. Figure 5The example of coil 533 shown includes three turns. The cross-section of coil 533 is indicated by symbols; coils with an "X" symbol indicate that coil 533 extends rotatably into the page, while coils with a "●" symbol indicate that coil 533 extends rotatably out of the page. The elements for plasma generation also include an RF power source 541 configured to provide RF power to coil 533. Generally, RF power source 541 is connected to matching circuit 539 via connector 545. Matching circuit 539 is connected to coil 533 via connector 543. In this way, RF power source 541 is connected to coil 533. For ALE cycles, RF power source 541 can be pulsed at a frequency between 10 Hz and 200 Hz during modification operations using a duty cycle between 1% and 20% and / or during removal operations using a duty cycle between 1% and 20% and a frequency between 10 Hz and 200 Hz. Optional Faraday shield 549 is positioned between coil 533 and window 511. Faraday shield 549 is held in a spaced-out relationship relative to coil 533. Faraday shield 549 is positioned directly above window 511. Coil 533, Faraday shield 549, and window 511 are each configured to be substantially parallel to each other. Faraday shield prevents the deposition of metal or other substances on the dielectric window of plasma chamber 501.

[0198] Processing gases (e.g., chlorine, argon, oxygen, etc.) can flow into processing chamber 501 through one or more main gas inlets 560 located in upper chamber 502 and / or through one or more side gas inlets 570. Similarly, although not explicitly shown, similar gas inlets can be used to supply processing gases to the capacitively coupled plasma processing chamber. A vacuum pump, such as a single-stage or two-stage dry mechanical pump and / or turbomolecular pump 540, can be used to evacuate processing gases from processing chamber 501 and maintain pressure within processing chamber 501. For example, this pump can be used to evacuate chamber 501 during ALE purging operations. Valve-controlled conduits can be used to fluidly connect a vacuum pump to processing chamber 501 to optionally control the application of the vacuum environment provided by the vacuum pump. This can be done using closed-loop controlled flow-limiting devices such as throttle valves (not shown) or pendulum valves (not shown) during plasma processing. Similarly, a vacuum pump and valves can also be used with controlled fluid connections to the capacitively coupled plasma processing chamber.

[0199] During operation of the device, one or more process gases may be supplied through gas inlets 560 and / or 570. In some embodiments, the process gas may be supplied only through the main gas inlet 560 or only through the side gas inlet 570. In some cases, the gas inlets shown in the figure may be replaced by more complex gas inlets, for example, by one or more nozzles. The Faraday shield 549 and / or optional grid 550 may include internal channels and orifices that allow the process gas to be delivered to the chamber 501. One or both of the Faraday shield 549 and optional grid 550 may serve as nozzles for delivering the process gas. In some embodiments, a liquid evaporation and delivery system may be located upstream of the chamber 501, such that once the liquid reactant or precursor is evaporated, the evaporated reactant or precursor is introduced into the chamber 501 through gas inlets 560 and / or 570. Exemplary liquid precursors include SiCl4 and silamide.

[0200] Radio frequency (RF) power is supplied from RF power source 541 to coil 533 to cause RF current to flow through coil 533. The RF current flowing through coil 533 generates an electromagnetic field around coil 533. The electromagnetic field induces a current in upper sub-chamber 502. The generated ions and radicals interact physically and chemically with wafer 519 to optionally etch features and deposit layers on the wafer.

[0201] If a plasma grid is used such that both an upper sub-chamber 502 and a lower sub-chamber 503 exist, an induced current acts on the gas present in the upper sub-chamber 502 to generate an electron-ion plasma in the upper sub-chamber 502. An optional internal plasma grid 550 limits the amount of hot electrons in the lower sub-chamber 503. In some embodiments, the device is designed and operated such that the plasma present in the lower sub-chamber 503 is an ion-ion plasma.

[0202] Both the upper electron-ion plasma and the lower ion-ion plasma can contain both cations and anions, but the ion-ion plasma will have a larger anion:cation ratio. Volatile etching and / or deposition byproducts can be removed from the lower sub-chamber 503 through port 522. The chuck 517 disclosed herein can be operated at temperatures ranging from about -200°C to about 600°C or from about -20°C to about 250°C to process substrates for etching tantalum; the chuck 517 can be set at temperatures below about 0°C. The temperature depends on the processing operation and specific formulation, as well as the tools used.

[0203] When installed in a clean room or manufacturing plant, chamber 501 can be coupled to facilities (not shown). Facilities include piping that provides process gases, vacuum, temperature control, and environmental particulate control. These facilities are coupled to chamber 501 when installed in the target manufacturing plant. Furthermore, chamber 501 can be coupled to a transfer chamber, allowing for the use of typical automation to move semiconductor wafers in and out of chamber 501 by robots.

[0204] In some embodiments, system controller 530 (which may include one or more physical or logic controllers) controls some or all of the operations of the processing chamber. System controller 530 may include one or more memory devices and one or more processors. In some embodiments, the device includes a switching system for controlling flow rate and duration when the disclosed embodiments are performed. In some embodiments, the device may have a switching time of up to about 500 ms or up to about 750 ms. The switching time may depend on the flowing chemical substance, formulation selection, reactor architecture, and other factors.

[0205] In some implementations, controller 530 is part of a system, which may be part of the examples described above. Such a system may include a semiconductor processing apparatus comprising one or more processing tools, one or more processing chambers, one or more platforms for processing, and / or specific processing components (wafer substrate supports, airflow systems, etc.). These systems may be integrated with electronics for controlling their operation before, during, and after processing semiconductor wafers or substrates. The electronics may be referred to as a “controller”, which can control various elements or sub-components of one or more systems. Depending on the processing parameters and / or the type of system, controller 530 may be programmed to control any of the processes disclosed herein, including controlling processing gas delivery, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, position and operation settings, wafer transfer tools and other transfer tools, and / or loading locks connected to or interfaced with a specific system.

[0206] Broadly speaking, controller 530 can be defined as an electronic device having various integrated circuits, logic, memory, and / or software that receive instructions, issue instructions, control operations, enable cleaning operations, enable endpoint measurements, etc. Integrated circuits can include chips in the form of firmware storing program instructions, digital signal processors (DSPs), chips defined as application-specific integrated circuits (ASICs), and / or one or more microprocessors or microcontrollers that execute program instructions (e.g., software). Program instructions can be instructions that communicate to the controller in the form of various individual settings (or program files) that define operating parameters for performing specific processes on or for a semiconductor wafer or system. In some embodiments, operating parameters can be part of a recipe defined by a processing engineer for completing one or more processing steps during the fabrication of one or more layers, materials, metals, oxides, silicon, silica, surfaces, circuits, and / or dies of a wafer. In some embodiments, controller 530 can be used to determine a temperature window for ALE modification operations, or a processing condition window for ALE removal operations, or both.

[0207] In some implementations, controller 530 may be part of or coupled to a computer integrated with, coupled to, or connected via a network to the system or a combination thereof. For example, the controller may be in the “cloud” or be all or part of a fab host system that allows remote access to wafer processing. The computer may enable remote access to the system to monitor the current progress of manufacturing operations, examine the history of past manufacturing operations, examine trends or performance criteria of multiple manufacturing operations, change parameters of the current processing, set processing steps to follow the current processing, or start a new processing. In some instances, a remote computer (e.g., a server) may provide processing recipes to the system via a network, which may include a local network or the Internet. The remote computer may include a user interface capable of inputting or programming parameters and / or settings that are then communicated from the remote computer to the system. In some instances, controller 530 receives instructions in the form of data specifying parameters for each processing step to be performed during one or more operations. It should be understood that the parameters may be specific to the type of processing to be performed and the type of tool to which the controller is configured to connect to or control the tool. Therefore, as described above, the controller 530 can be distributed, for example, by including one or more discrete controllers connected together via a network and operating toward a common goal (e.g., the processing and control described herein). An example of a distributed controller for these purposes could be one or more integrated circuits on a room that communicate with one or more remote integrated circuits (e.g., at the platform level or as part of a remote computer), which together control processing within the room.

[0208] Exemplary systems may include, but are not limited to, plasma etching chambers or modules, deposition chambers or modules, rotary cleaning chambers or modules, metal plating chambers or modules, cleaning chambers or modules, chamfering edge etching chambers or modules, physical vapor deposition (PVD) chambers or modules, chemical vapor deposition (CVD) chambers or modules, ALD chambers or modules, ALE chambers or modules, ion implantation chambers or modules, orbital chambers or modules, and any other semiconductor processing systems that may be associated with or used in the fabrication and / or manufacturing of semiconductor wafers.

[0209] As described above, depending on one or more processing steps the tool is to perform, the controller may communicate with one or more other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, neighboring tools, tools located throughout the plant, a host, another controller, or tools used in material handling that transports wafer containers to and from tool locations and / or loading ports within the semiconductor manufacturing plant.

[0210] Figure 6 A semiconductor processing cluster architecture is described, in which each module interfaces with a vacuum transfer module 638 (VTM). The configuration of the transfer module, which “transfers” wafers between multiple memory devices and processing modules, can be referred to as a “cluster tooling architecture” system. A hermetically sealed chamber 630 (also referred to as a load lock or transfer module) is shown in the VTM 638 having four processing modules 620a-620d, which can be individually optimized to perform various manufacturing processes. For example, processing modules 620a-620d can be implemented to perform substrate etching, deposition, ion implantation, wafer cleaning, sputtering, and / or other semiconductor processes. One or more of the substrate etching processing modules (any one or more of 620a-620d) can be implemented as disclosed herein, i.e., for introducing a modifying gas, for introducing a removal gas, and other suitable functions according to the disclosed embodiments. The hermetically sealed chamber 630 and processing modules 620 can be referred to as “stations.” Each station has a facet 636 connecting the station to the VTM 638. Within each facet, sensors 1-18 are used to detect the passage of substrate 626 as it moves between stations.

[0211] Robotic arm 622 transfers wafer 626 between stations. In one embodiment, robotic arm 622 has one arm, while in another embodiment, robotic arm 622 has two arms, each with an end effector 624 to pick up wafers (e.g., wafer 626) for transport. In atmospheric transfer module (ATM) 640, front-end robotic arm 632 is used to transfer wafer 626 from a wafer cassette or front-opening standard cassette (FOUP) 634 in load port module (LPM) 642 to airtight chamber 630. Module center 628 within processing module 620 is a location for placing wafer 626. Aligner 644 in ATM 640 is used to align the wafer.

[0212] In one exemplary processing method, a wafer is placed in one of a plurality of FOUPs 634 within an LPM 642. A front-end robot 632 transfers the wafer from the FOUP 634 to an alignment unit 644, which allows the wafer 626 to be properly centered before etching or processing. After alignment, the wafer 626 is moved by the front-end robot 632 into an airtight chamber 630. Because the airtight module has the ability to match the environments between ATM and VTM, the wafer 626 can move between the two pressure environments without damage. From the airtight module 630, the wafer 626 is moved by the robot 622 through the VTM 638 and into one of the processing modules 620a-620d. To achieve this wafer movement, the robot 622 uses end effectors 624 on each of its arms. Once the wafer 626 has been processed, it is moved from the processing modules 620a-320d into the airtight module 630 by the robot 622. The chip 626 can be moved from here to one of the multiple FOUPs 634 or to the aligner 644 via the front-end robot 632.

[0213] It should be noted that the computer controlling the movement of the chip can be local to the cluster architecture, or it can be located outside the cluster architecture in the manufacturing plant, or at a remote location connected to the cluster architecture via a network. (See above for reference.) Figure 5 The controller can be used Figure 6 The tools implemented in the process.

[0214] experiment

[0215] Experiment 1

[0216] Experiments were conducted on silicon on an insulating material on a substrate by exposing the substrate to 40 cycles of pulsed atomic layer etching. Each cycle consisted of: a 200 sccm chlorine dose pulsed at 100 Hz for modification at 40 mTorr; argon purging; a 400 sccm helium flow with 300 W plasma, using pulsed bias (ON / OFF) at 100 Hz; and argon purging again. The etching for each cycle was determined for each trial, and a different bias power was used for the ON-state bias in each trial, ranging from 100 to 500 V in 50 V increments. Figure 7 The graph plots the relationship between bias power and etch thickness (in angstroms) for each cycle, showing a saturated etch rate with a self-limiting state at a high bias power between 300V and 500V, which is significantly higher than the self-limiting bias power in continuous ALE. Figure 7 The Y-axis in the graph is a linear scale.

[0217] Experiment 2

[0218] Experiments were conducted to determine the etching depth per cycle for amorphous silicon and silicon oxide materials on the substrate. Both amorphous silicon and silicon oxide were exposed to 70 cycles of pulsed atomic layer etching using helium as the removal gas. Each cycle consisted of: 180 sccm of chlorine and 180 sccm of helium pulsed at 100 Hz at 20 mTorr, without bias; argon purging; 400 sccm of helium flow, 0 W plasma, with pulsed bias (ON / OFF) at 100 Hz; and argon purging again. The etching depth for each cycle was determined for various bias powers for the ON-state bias, ranging from 100 to 500 V in 100 V increments. Figure 8A The graph plots the relationship between bias power and etch thickness (in angstroms) per cycle, showing that amorphous silicon (triangles) has a higher etch amount per cycle than silicon oxide (circles). Figure 8A The Y-axis in the graph is a linear scale. The etch selectivity ratio of amorphous silicon to silicon oxide is calculated and displayed. Figure 8B The results show a higher selectivity at lower bias power and a lower selectivity at higher bias power. These results demonstrate that a wider bias power range can be tuned using pulsed ALE to achieve the desired etch selectivity.

[0219] Experiment 3

[0220] Experiments were conducted to determine the etching amount per cycle for amorphous silicon and silicon oxide materials on the substrate. Both amorphous silicon and silicon oxide were exposed to 200 cycles of pulsed atomic layer etching using argon as the removal gas. Each cycle consisted of: pulsed 180 sccm of chlorine and 180 sccm of helium at 100 Hz at 20 mTorr, without bias and with a plasma power of 200 W; argon purging; 400 sccm of argon flow, 0 W plasma power, with pulsed bias (ON / OFF) at 100 Hz; argon purging. The etching amount per cycle was determined for various bias powers for the ON state bias, ranging from 200 to 400 V in increments of 25 V or 50 V. Figure 9A The graph plotted the relationship between bias power and etch thickness (in angstroms) per cycle, showing that amorphous silicon (triangles) has a higher etch amount per cycle than silicon oxide (circles). Figure 9A The Y-axis in the graph is a linear scale. The etch selectivity ratio of amorphous silicon to silicon oxide is calculated and displayed. Figure 9B The results show a higher selectivity at lower bias power and a lower selectivity at higher bias power. These results demonstrate that a wider bias power range can be tuned using pulsed ALE to achieve optimal etch selectivity.

[0221] Experiment 4

[0222] Experiments were conducted on a patterned substrate using pulsed ALE, with helium as the purge gas. The substrate pattern comprised both isolated and dense structures; the isolated structures had 80 nm features, while the dense structures had approximately 5 nm features near the feature openings, with feature depths ranging from 60 nm to 80 nm. The substrate was exposed to multiple cycles of pulsed ALE at a substrate temperature of 120 °C. Each cycle included: a chlorine dose using plasma; a helium purge; exposure to helium purge gas using plasma for 3 seconds each, with a pulsed bias at 25% duty cycle and a bias power between 0 V and 65 V; and a helium purge. The load percentage of the pitch was calculated for various trenches with a wide range of critical dimensions, and the results were plotted. Figure 10A As shown in the figure, the pitch load decreases when the groove size increases.

[0223] Patterns with similar structures were exposed to multiple cycles of pulsed ALE at a substrate temperature of 120°C. Each cycle included: a chlorine dose using plasma; a helium purge; exposure to helium removal gas using plasma, each exposure lasting 3 seconds, with pulsed bias at 10% of the duty cycle and bias power ranging from 0V to 150V; and a helium purge. The load percentage of the pitch was calculated for various trenches with critical dimension ranges, and the results were plotted. Figure 10BAs shown in the figure, the pitch load decreases when the groove size increases.

[0224] An image of the substrate shows that for trenches with feature openings less than 10 nm, a higher helium bias with pulses between 0 V and 150 V for 10 V pulses achieves a more similar etch depth for each feature across the entire substrate compared to a substrate exposed to a low helium bias with pulses between 0 V and 65 V using 25% duty cycles.

[0225] Experiment 4

[0226] Figure 11 The diagram shows a comparison of the etch amount per cycle versus bias for three different curves during the removal operation. Curve 1002 shows an example of the etch amount per cycle when ALE is performed with a 2-second exposure time and 3% duty cycle during the removal operation. Curve 1101 shows an example of the etch amount per cycle when ALE is performed with a 2-second exposure time and 10% duty cycle during the removal operation. The first two are compared to curve 1103, which shows ALE performed with a 7-second exposure time during removal without pulsed bias (e.g., 100% duty cycle). As shown, the pulsed implementation saturates (saturates at approximately 900 eV at 10% duty cycle and approximately 1500 eV at 3% duty cycle), but the data provided by the non-pulsed implementation does not exhibit a specific saturation bias.

[0227] Experiment 4

[0228] Figure 12A This shows an example of experimental data collected regarding the relationship between the amount of etch and the bias voltage for each cycle during successive exposures in the removal process. Arrow 1201 shows an example of an ALE window representing the voltage at etch saturation for each cycle.

[0229] Figure 12B An example showing the relationship between the amount of etching per cycle and time in a continuous ALE of silicon is presented. In contrast, the literature shows that the amount of etching by the ion beam in the etching reactor (as a function of the duration of argon exposure) involves an increase in the amount of etching with argon exposure between 100 and 300 seconds, followed by a relatively horizontal slope of the amount of etching up to about 650 seconds, and then a slight increase in the amount of etching after argon exposure exceeds 700 seconds in some cases.

[0230] Experiment 5

[0231] Figure 13 The energy of ions that are completely removed is shown to depend on the "ON" time of the argon ions.

[0232] Figure 14AThis shows the ALE range for various ON times on a silicon substrate using chlorine as the modifying gas and argon as the removal gas, assuming a flux rate of F = F0(1 + a*V). 偏置 ^1.5), where F0 is determined by experimental data. For example, curve 1401 represents the normalized etch amount / cycle at 0.06 seconds per pulse, curve 1402 represents the normalized etch amount / cycle at 0.2 seconds per pulse, curve 1403 represents the normalized etch amount / cycle at 0.5 seconds per pulse, curve 1405 represents the normalized etch amount / cycle at 1 second per pulse, curve 1407 represents the normalized etch amount / cycle at 2 seconds per pulse, curve 1408 represents the normalized etch amount / cycle at 3 seconds per pulse, and curve 1409 represents the normalized etch amount / cycle at 7 seconds per pulse. Line 1410 shows the amount etched away in one layer.

[0233] Figure 14B An exemplary simulation fit is shown, illustrating the etching amount per cycle of pulsed ALE, which enables complete removal using a specific argon ON time and leveraging the ALE coordination effect. These results demonstrate that, even with significantly higher ON times during the removal process, pulsed ALE allows for complete removal with higher etch rates / cycles without substantial sputtering.

[0234] in conclusion

[0235] While the foregoing embodiments have been described in considerable detail for the purpose of clarity, it will be apparent that certain variations and modifications may be made within the scope of the appended claims. It should be noted that many alternative methods exist for implementing the embodiments of the invention, including processes, systems, and apparatus. Therefore, the embodiments of the invention should be considered illustrative rather than restrictive, and are not limited to the details given herein.

Claims

1. A substrate processing method, the method comprising: Provide a substrate containing the material to be etched; The surface of the material to be etched is exposed to a modifying gas to modify the surface and form a modified surface; as well as The modified surface is exposed to high-energy particles and a bias is applied to preferentially remove the modified surface relative to the underlying unmodified surface. The high-energy particles possess ion energies sufficient to overcome the average surface binding energy of the underlying unmodified surface. Its characteristic is that the electrical energy applied to the bias is at least 150 eV. The high-energy particles remove a certain amount of the modified surface, and the amount of the modified surface removed is expressed by the following formula: Where Y is the ion yield of the high-energy particles, F is the flux of the high-energy particles, t is the exposure duration of the high-energy particles, and d is the surface density of the material to be etched.

2. The method of claim 1, wherein the ionic energy of the high-energy particle is sufficient to break the bonds of the underlying unmodified surface.

3. The method of claim 1, wherein the high-energy particles are delivered in a time-separated dose, the time-separated dose having a duty cycle of less than 100% or between 1% and 20%.

4. The method of claim 1, wherein a bias voltage is applied to a substrate support holding the substrate during the exposure of the modified surface to the high-energy particles.

5. The method of claim 1, wherein the high-energy particles do not significantly sputter the material of the underlying unmodified surface.

6. The method of claim 1, wherein the modified surface is exposed to the high-energy particles for a duration sufficient to remove the modified surface in a self-limiting manner.

7. The method according to any one of claims 1-6, wherein the electrical energy applied to the bias is at least 500 eV.

8. The method according to any one of claims 1-6, wherein the high-energy particles remove a certain amount of the modified surface, and the flux F of the high-energy particles is expressed by the following formula: F=F0(1+a*V 偏置 ^1.5), Where F0 is determined by experimental data, and V 偏置 It is a bias voltage measured in volts.

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