Control of etching selectivity in atomic layer etching

Abstract

Apparatus and methods are provided. Some methods can include providing a substrate in a processing chamber, the substrate having a first material adjacent to and overlying a surface of the second material, modifying the layer of the first material by flowing a first process gas over the substrate thereby forming a modified layer of the first material, removing the modified layer of the first material by flowing a second process gas over the substrate, and once the surface of the second material is freed via removal of the modified layer, converting the surface to a converted layer of the second material by flowing a third process gas over the substrate, wherein the first process gas and the second process gas are less reactive with the converted layer than the first material and the second material.

Description

[Technical Field]

[0001] Incorporated by reference: A PCT application is being filed concurrently herewith as part of this application, and each application identified in that concurrently filed PCT application to which this application claims benefit or priority is incorporated herein by reference in its entirety for all purposes. [Background technology]

[0002] Semiconductor fabrication often involves patterning schemes and other processes in which some materials are selectively etched to prevent etching of other exposed surfaces of the substrate. As device geometries become smaller and smaller, processes with high etch selectivity are desired to effectively etch desired materials without etching other materials.

[0003] The background description provided herein is intended to present the contents of the present disclosure generally. Work by the presently named inventors within the scope of what is described in this Background section, as well as aspects of the description that may not otherwise be considered prior art at the time of filing, are not admitted, expressly or impliedly, as prior art against the present disclosure. Summary of the Invention

[0004] The systems, methods, and devices of the present disclosure each have several innovative aspects, no single aspect of which is solely responsible for the desirable attributes disclosed herein, including at least the following embodiments, although additional embodiments may be described in the detailed description or become apparent from the discussion provided herein.

[0005] In some embodiments, a method can be provided that includes providing a substrate in a processing chamber, the substrate having a first material adjacent to and overlying a surface of a second material, modifying the layer of the first material by flowing a first process gas over the substrate, thereby forming a modified layer of the first material, removing the modified layer of the first material by flowing a second process gas over the substrate, and once the surface of the second material is released via removal of the modified layer, converting the surface to a converted layer of the second material by flowing a third process gas over the substrate, wherein the first and second process gases are less reactive with the converted layer than the first and second materials.

[0006] In some embodiments, the method may further include, after conversion, modifying the converted layer to a modified converted layer of the material by flowing a fourth process gas over the substrate, and removing the modified converted layer by flowing a fifth process gas over the substrate.

[0007] In some embodiments, flowing the third process gas may occur before reformulation.

[0008] In some embodiments, flowing the third process gas may occur after reformulation.

[0009] In some such embodiments, flowing the third process gas may occur before the removal.

[0010] In some further such embodiments, the method may further include flowing a purge gas after flowing the third process gas and before removing.

[0011] In some such embodiments, flowing the third process gas may occur after the removal.

[0012] In some embodiments, flowing the third process gas over the substrate may at least partially overlap with flowing the first process gas over the substrate.

[0013] In some embodiments, flowing the third process gas over the substrate may at least partially overlap with flowing the second process gas over the substrate.

[0014] In some embodiments, flowing the third process gas over the substrate may at least partially overlap with flowing the first process gas over the substrate and flowing the second process gas over the substrate.

[0015] In some embodiments, the transformation may occur when the surface of the second material is released during or after removal of the first material.

[0016] In some embodiments, during removal, the second process gas may remove the modified layer of the first material at a first etch rate, and during removal, the second process gas may remove the converted layer at a second etch rate that is less than or equal to about 50% of the first etch rate.

[0017] In some such embodiments, the second etch rate may be less than or equal to about 15% of the first etch rate.

[0018] In some such embodiments, during removal, the second process gas may be capable of removing the second material at a third etch rate that is greater than the first etch rate.

[0019] In some embodiments, a first process gas may include modifying molecules, a second process gas may include removing molecules, and a third process gas may include converting molecules.

[0020] In some embodiments, the third process gas may include a precursor.

[0021] In some embodiments, the conversion layer may be a monolayer of the second material.

[0022] In some embodiments, the first material and the second material may be oxides.

[0023] In some embodiments, the first material and / or the second material may be a semiconductor oxide.

[0024] In some embodiments, the conversion layer may be inert to the second process gas.

[0025] In some embodiments, the reaction between the conversion layer and the second process gas may not produce any by-products.

[0026] In some embodiments, the method may further include repeatedly modifying and removing to remove an amount of the first material prior to the conversion.

[0027] In some embodiments, the first material may include aluminum oxide, the second material may include zinc oxide, the first process gas may include hydrogen fluoride, the second process gas may include trimethylaluminum, the third process gas may include zirconium tetrachloride, and the conversion layer may include zirconium oxide.

[0028] In some embodiments, the method may further include removing the conversion layer by flowing a fourth process gas over the substrate, wherein the fourth process gas includes dimethylaluminum chloride.

[0029] In some embodiments, the conversion may include cation exchange between an element in the third process gas and the second material.

[0030] In some embodiments, the modification and removal may occur while the substrate is maintained at the same, or substantially the same, temperature.

[0031] In some embodiments, the modification may occur while the substrate is maintained at a first temperature, and the removal may occur while the substrate is maintained at a second temperature that is different from the first temperature.

[0032] In some embodiments, water vapor may not be supplied to the substrate during conversion.

[0033] In some embodiments, a method can be provided that can include providing a substrate in a processing chamber, the substrate having a first material adjacent to and overlying a surface of a second material, modifying the layer of the first material by flowing a first process gas over the substrate, thereby forming a modified layer of the first material, removing the modified layer of the first material by flowing a second process gas over the substrate, and selectively converting the surface of the second material into a layer of etch stop material as the surface of the second material is released via removal of the modified layer, the layer of etch stop material being positioned only over the second material such that during removal, the modified layer of the first material and the layer of etch stop material are exposed to a second process gas, the second process gas being less reactive with the layer of etch stop material than with the modified layer of the first material and the second material.

[0034] In some embodiments, an apparatus for semiconductor processing can be provided, the apparatus including: a process chamber including a substrate support configured to support a substrate therein; a process gas unit configured to flow a first process gas including modifying molecules over the substrate in the process chamber, a second process gas including removal molecules over the substrate in the process chamber, and a third process gas including conversion molecules over the substrate in the process chamber; and a controller having instructions configured to: flow the first process gas over the substrate, thereby forming a modified layer of a first material on the substrate, the substrate having a first material adjacent to and overlying a surface of the second material; flow the second process gas over the substrate, thereby removing the modified layer of the first material; and flow the third process gas over the substrate, converting the surface of the second material to a converted layer of the second material upon release, the first and second process gases being less reactive with the converted layer than the first and second materials. [Brief explanation of the drawings]

[0035] [Figure 1] FIG. 1 is an exemplary process flow diagram for performing operations according to disclosed embodiments.

[0036] [Figure 2] FIG. 2 is an exemplary schematic diagram of atomic layer etching according to disclosed embodiments.

[0037] [Figure 3] FIG. 3 is another exemplary process flow diagram for performing operations according to disclosed embodiments.

[0038] [Figure 4A] FIG. 4A is yet another exemplary process flow diagram for performing operations according to disclosed embodiments.

[0039] [Figure 4B] FIG. 4B is another exemplary process flow diagram for performing operations according to disclosed embodiments.

[0040] [Figure 5] FIG. 5 is another exemplary process flow diagram for performing operations according to disclosed embodiments.

[0041] [Figure 6A] FIG. 6A further illustrates various flows of a third process gas over the wafer. [Figure 6B] FIG. 6B further illustrates various flows of a third process gas over the wafer. [Figure 6C] FIG. 6C further illustrates various flows of the third process gas over the wafer. [Figure 6D] FIG. 6D further illustrates various flows of the third process gas over the wafer.

[0042] [Figure 7] FIG. 7 is a diagram illustrating an exemplary apparatus for semiconductor processing according to disclosed embodiments, including thermal atomic layer etching.

[0043] [Figure 8A] FIG. 8A illustrates one embodiment of an adjustable gap capacitively coupled confinement RF plasma reactor that can be used to perform the etching operations described herein. [Figure 8B] FIG. 8B illustrates one embodiment of an adjustable gap capacitively coupled confinement RF plasma reactor that can be used to perform the etching operations described herein. [Figure 8C] FIG. 8C illustrates one embodiment of an adjustable gap capacitively coupled confinement RF plasma reactor that can be used to perform the etching operations described herein.

[0044] [Figure 9]FIG. 9 is a diagram illustrating a semiconductor process cluster architecture having various modules interfacing with a vacuum transfer module.

[0045] [Figure 10] FIG. 10 is a schematic diagram of a process station that can be used to deposit the material.

[0046] [Figure 11] FIG. 11 is a schematic diagram of a multi-station processing tool.

[0047] [Figure 12] FIG. 12 is a block diagram of a processing system suitable for performing thin film deposition processes in accordance with certain embodiments.

[0048] [Figure 13] FIG. 13 is a schematic diagram of a multi-station processing tool.

[0049] [Figure 14] FIG. 14 is another schematic diagram of a multi-station processing tool. DETAILED DESCRIPTION OF THE INVENTION

[0050] In the following description, numerous specific details are set forth to provide a thorough understanding of the presented embodiments. The disclosed embodiments may be practiced without some or all of these specific details. In other instances, well-known process operations have not been described in detail so as not to unnecessarily obscure the disclosed embodiments. While the disclosed embodiments will be described in conjunction with specific embodiments, it will be understood that they are not intended to limit the disclosed embodiments.

[0051] In this application, the terms "semiconductor wafer," "wafer," "substrate," "wafer substrate," and "partially fabricated integrated circuit" are used interchangeably. Those skilled in the art will understand that the term "partially fabricated integrated circuit" can refer to a silicon wafer at any of many stages of integrated circuit fabrication. Wafers or substrates used in the semiconductor device industry typically have diameters of 200 mm, 300 mm, or 450 mm. The following detailed description assumes that the invention is practiced on a wafer. However, the invention is not so limited. Workpieces can be of various shapes, sizes, and materials. In addition to semiconductor wafers, other workpieces that can utilize the invention include various articles such as printed circuit boards, magnetic recording media, magnetic recording sensors, mirrors, optical elements, micromechanical devices, and the like.

[0052] Introduction and Background Semiconductor fabrication processes often involve patterning and etching a variety of materials, including conductors, semiconductors, and dielectrics. Some examples include conductors such as metals or carbon, semiconductors such as silicon or germanium, and dielectrics such as silicon oxide, aluminum oxide, zirconium dioxide, hafnium dioxide, silicon nitride, and titanium nitride. Atomic layer etching ("ALE") processes use a series of self-limiting reactions to remove thin layers of material. Generally, an ALE cycle is a minimum set of operations used to perform a single etching process, such as etching a monolayer. A single ALE cycle etches at least a portion of a film layer on a 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 reactive layer. A cycle may include specific auxiliary operations, such as removing one of the reactants or byproducts, as well as a cleaning operation to remove accumulated residues on the processing chamber surfaces. Generally, a cycle includes one instance of a unique sequence of operations.

[0053] As an example, an ALE cycle can include the following operations: (i) delivery of a first process gas, which is a reactant gas; (ii) purging the reactant gas from the chamber; (iii) delivery of a second process gas, which is a removal gas and optional plasma; and (iv) purging the chamber. In some embodiments, etching can be performed non-conformally. In some cases, a cleaning operation can be performed after one or more cycles to remove residues that have accumulated on the surfaces of the processing chamber. The modification operation generally forms a thin reactive surface layer thinner than the unmodified material, for example, one, two, or three atomic layers thick, or thinner than an entire atomic layer in one cycle.

[0054] Some implementations of the ALE processes described herein may rely on chemical reactions in conjunction with maintaining the substrate at a specific temperature or temperature range to drive the chemical reactions in modification and / or removal operations, which may be considered “thermal ALE.” In some embodiments, this thermal ALE may be considered isotropic etching. In some embodiments, one or more layers of the substrate may be modified by chemical adsorption (hereinafter “chemisorption”) rather than plasma while the substrate is maintained at a first temperature, and then one or more modified layers of the substrate may be removed by desorption rather than plasma while the substrate is at a second temperature. In some embodiments, the first and second temperatures may be the same, while in other embodiments, they may be different from one another. Chemisorption and desorption are temperature-dependent chemical reactions that may occur in separate temperature regimes, partially overlapping temperature regimes, or the same temperature regime. For this reason, some of the thermal ALE techniques described herein maintain the substrate temperature at the same or substantially the same temperature during the modification and removal operations. Some other embodiments adjust the temperature of the substrate between the modification and removal operations to allow and utilize chemisorption that occurs at one temperature for the modification operation, and desorption that occurs at a different temperature for the removal operation.

[0055] In some embodiments of thermal ALE, plasma may be used during the modification operation but not during the removal operation, while in some other embodiments, plasma may be used during both the modification and removal operations, resulting in varying temperatures during these operations.

[0056] In some thermal ALE processes, one or more surface layers of a material may be modified by chemisorption while the substrate is maintained at a first temperature, thereby forming one or more modified surface layers of the substrate. The substrate includes a layer of material and an exposed surface, which may be a uniform layer of material or a heterogeneous layer containing different molecules and elements. A first process gas having modifying molecules may be flowed over the substrate maintained at the first temperature. In some embodiments, the modifying molecules may include a halogen, such as fluorine, to halogenate the exposed molecules on the substrate, while in some embodiments, the modifying molecules may include oxygen to oxidize the exposed molecules on the substrate. The first process gas may also include a carrier gas, such as N2, Ar, He, and Ne. This first temperature allows for chemisorption between the modifying molecules and at least a portion of the molecules on the exposed surface of the material.

[0057] Although the term "first temperature" is used, the temperatures discussed herein can be considered both specific temperatures or temperature ranges, as highlighted in FIGS. 2 and 3. In some embodiments, the first temperature can be, for example, about 20°C to 500°C, about 20°C to 150°C, about 20°C to 100°C, about 20°C to 80°C, about 200°C to 600°C, about 200°C to 500°C, about 200°C to 350°C, or about 350°C to 500°C. Additionally, the substrate can be maintained at that temperature for all, or substantially all (e.g., at least 80%, 90%, or 95%) of the modification operation. The duration of the modification operation can be a duration during which modification of substantially all (e.g., at least 80%, 90%, or 95%) of the desired exposed molecules on the substrate occurs. This may range, for example, from about 0.5 seconds to about 10 seconds, from 0.5 seconds to about 5 seconds, from about 1 second to about 5 seconds, or from about 30 seconds to 2 minutes.

[0058] After the modification operation, an optional purge operation can be performed. In some embodiments in which the modification and removal operations are performed at different temperatures, the temperature of the substrate can be brought to a second temperature after the modification operation, and an optional purge operation can be performed. This second temperature can be a temperature at which desorption occurs for one or more modified surface layers. In some embodiments, the second temperature can be higher than the first temperature, and the temperature of the substrate can be increased from the first temperature to the second temperature. In other embodiments, the second temperature can be lower than the first temperature, and in these embodiments, the temperature of the substrate can be actively cooled from the first temperature to the second temperature. The substrate can be heated using radiative heating, convective heating, solid-to-solid heat transfer, or with a plasma. In addition, the top, bottom, or both of the substrate can be heated. In some embodiments, the heating of the substrate can be nonlinear, and the substrate can be actively cooled in various manners. As noted above, in some embodiments, the second temperature can be the same or substantially the same as the first temperature, such that the modification and removal operations are performed at the same or substantially the same temperature.

[0059] The modified surface layer or layers can be removed while the substrate is maintained at the second temperature. In some embodiments, the modified molecules can be removed from the substrate by causing desorption, since only the second temperature allows for desorption of the modified molecules from the substrate. In some other embodiments, a second process gas having the removal molecules can be flowed over the substrate (including over the exposed surface of the substrate). The second process gas may also include a carrier gas, as described above. These removal molecules can react with the modified molecules to form different volatile molecules, which can be considered volatilized molecules. The volatilized molecules can then be removed from the substrate by desorption when the substrate is at the second temperature. In some embodiments, the flow of this second process gas can be part of the removal operation or can be a separate operation that occurs before, after, or during heating of the substrate.

[0060] In some embodiments, the second temperature may be the same as or different from the first temperature, for example, in the range of about 20°C to 500°C, about 20°C to 150°C, about 20°C to 100°C, about 20°C to 80°C, about 200°C to 600°C, about 200°C to 500°C, about 200°C to 350°C, or about 350°C to 500°C. Additionally, the substrate may be maintained at that temperature for all or substantially all (e.g., at least 80%, 90%, or 95%) of the removal operation. The duration of the removal operation may be a duration that results in desorption of substantially all (e.g., at least 80%, 90%, or 95%) of the desired molecules on the substrate. This may be in the range of about 0.5 seconds to about 10 seconds, about 0.5 seconds to about 5 seconds, about 1 second to about 5 seconds, about 0.5 seconds to 2 minutes, or about 30 seconds to 2 minutes.

[0061] In some other ALE processes, ion energy, such as from a plasma, can be used to drive the modification and / or removal operations. In an exemplary modification operation, the substrate can be chlorinated by introducing chlorine into the chamber. While chlorine is used as an exemplary etchant species or etching gas, it will be understood that different etching gases can be introduced into the chamber. The etching gas can be selected depending on the type and chemistry of the substrate being etched. When the plasma is ignited, chlorine can react with the substrate for the etching process, and the chlorine can react with the substrate or be adsorbed onto the surface of the substrate. The species generated from the plasma can be generated directly by forming the plasma in the process chamber containing the substrate, or can be generated remotely in a process chamber not containing the substrate and then delivered into the process chamber containing the substrate.

[0062] In some cases, purging may be performed after any of the operations described herein, including after modification and / or removal operations. A purging operation can remove non-surface-bound active modification molecules, such as chlorine or halogen species, from the process chamber. This can be done by purging and / or evacuating the process chamber to remove the active species without removing the adsorbed layer. In some implementations using a plasma, species generated within the plasma can be removed by stopping the plasma and allowing the remaining species to decay, optionally combined with purging and / or evacuating the chamber. Purging can be done using any inert gas, such as N2, Ar, Ne, He, and combinations thereof.

[0063] In a plasma-based removal operation, the substrate can be etched by directional sputtering, which can include activated or sputtering gases or chemically reactive species that induce removal, by exposing the substrate to an energy source. In some embodiments, the removal operation can be performed by ion bombardment using argon or helium ions. A bias can optionally be turned on during removal to facilitate directional sputtering. In some embodiments, the ALE can be isotropic, while in some other embodiments, the ALE is not isotropic when directional ions are used in the removal process.

[0064] In various examples, the thermal ALE and plasma-assisted ALE modification and removal operations can be repeated in cycles, such as from about 1 to about 30 cycles, or from about 1 to about 20 cycles. Any suitable number of ALE cycles can be included to etch a desired amount of film. In some embodiments, ALE is performed in cycles that etch from about 1 angstrom (Å) to about 50 Å of the surface of the layer on the substrate. In some embodiments, the ALE cycles etch from about 2 Å to about 50 Å of the surface of the layer on the substrate. In some embodiments, each ALE cycle can etch at least about 0.1 Å, 0.5 Å, 1 Å, 2 Å, or 3 Å.

[0065] In some cases, prior to etching, the substrate may include a blanket layer of a material such as silicon or germanium. The substrate may include a patterned mask layer previously deposited and patterned on the substrate. For example, a mask layer may be deposited and patterned on a substrate including a blanket amorphous silicon layer. A layer on the substrate may also be patterned. The substrate may have "features" such as vias or contact holes, which may be characterized by one or more of narrow and / or reentrant openings, constrictions within the feature, and high aspect ratios. One example of a feature is a hole or via in a semiconductor substrate or a layer on the substrate. Another example is a trench in the substrate or layer. In various examples, the feature may have an underlayer, such as a barrier layer or an adhesion layer. Non-limiting examples of underlayers include dielectric layers and conductive layers, such as silicon oxide, silicon nitride, silicon carbide, metal oxides, metal nitrides, metal carbides, and metal layers. Another exemplary feature may include an overhang or ledge that may require etching where directed ions cannot access it.

[0066] In some thermal ALE and / or plasma-assisted ALE processes, it is desirable to etch a target material without etching other materials covered by the target material, which may be described as selectively etching the target material relative to other materials. For some materials and etching chemistries, this selectivity cannot be achieved with typical ALE processes and chemistries. In some of these typical ALE processes, once the etch front removes the target material and reaches other underlying materials, it may undesirably continue etching and removing these other materials. This undesirable etching may occur, for example, when etching high-k dielectrics, high-k oxides, semiconductors, metals, or other oxides covering other high-k dielectrics, high-k oxides, semiconductors, or metals. Therefore, some of these conventional ALE processes do not have the ability to selectively remove one high-k oxide relative to another high-k oxide or semiconductor.

[0067] Highly selective etching technique Techniques and apparatus are provided herein for increasing etch selectivity between materials. This involves etching one material over another, referred to as the target material, and reducing and / or limiting etching of the other material. Some embodiments may include introducing a third process gas that forms an etch stop layer that prevents and / or reduces etching of the underlying material. This third process gas may limit or even eliminate etching of the target material. In some embodiments, the third process gas can be considered both a gas with substantially all (e.g., at least 99% or more) of its components in the gas phase and a vapor whose components can exist in both the gas and liquid phases as suspended droplets. In some implementations, the etch stop layer may be a deposition layer of material that is selectively deposited on the underlying material. The etch stop layer, whether a conversion layer or a deposition layer, may be considered less reactive with etching chemistries than the second layer of material and the modified layer of material, limiting and reducing etching of this etch stop material compared to the second layer of material and the modified layer of material.

[0068] In some implementations, an etch stop layer can be formed by converting the exposed surface of an underlying material into a conversion layer capable of withstanding the etching chemistry used to remove the target material. This etch stop layer, or conversion layer, is formed by conversion of a layer of the underlying material, which in some cases can be achieved by cation exchange between a third process gas and the underlying material without changing the composition of the target material or interfering with the primary etching chemistry used to etch the target material. This can be conversion of at least one monoatomic layer of that material. In some implementations, the etch stop layer is formed via conversion of the surface of the underlying material using a vaporous compound when the surface is exposed. The third process provides cationic components in the vapor phase for this conversion, with the remaining components of this conversion provided by the surface of the underlying material. In some embodiments, the cationic components of the underlying material are converted into volatile molecules that leave or desorb from the surface of the substrate. Cations in the third process gas, e.g., the incoming vapor, exchange their ligands (e.g., chlorine) with ligands (e.g., oxygen) on the surface, thereby becoming solid or non-volatile.

[0069] Additionally, in some embodiments, it may be desirable for the etching chemistry, the third process gas, and the resulting etch stop layer to be compatible with one another, so that, for example, etching of the first material can continue while a conversion layer forms to protect underlying layers of material, and / or so that the etching chemistry does not react with the third process gas or etch the etch stop layer. For example, the first material may not etch simultaneously and / or at the same rate across the entire wafer and / or at various locations across the wafer. For various reasons, some etching processes begin at the center of the wafer and continue radially outward, thereby etching the central region before the edge region. This may result in the desired amount of material being removed in the central region faster than in the edge region, which may require the etching chemistry to continue flowing over the wafer even after the desired material has been removed from a portion of the wafer.

[0070] In another example, a first material may be deposited on the sides and bottom of a hole (or via, or trench), covering a second material also located within the hole. Because the etch rate on horizontal surfaces may be lower than that on vertical surfaces, the bottom and / or top of the hole, via, or trench may be etched to expose the second material before the first material on the sides of the hole is removed. This may require etching to continue within the hole to remove the first material on the sides of the hole, while the second material is exposed at the bottom and / or top of the hole. Therefore, in some embodiments, it may be desirable to continue etching of the first material on the wafer while simultaneously forming a conversion layer on the wafer that exposes the underlying material through etching. Accordingly, some embodiments provided herein use conversion molecules and etching chemistries that do not adversely affect each other, allowing etching of the first material to continue on the wafer while also forming a conversion layer as the underlying material is exposed by the etching.

[0071] The chemical used to etch the target material may etch the etch stop layer at an etch rate that is lower than the etch rate of the target material and / or other materials, for example, an etch rate that is 50%, 25%, 15%, 10%, 5%, 1%, 0.1%, or 0.05% or less of the target material and / or other materials.

[0072] As discussed in more detail below, a third process gas can be introduced during various aspects of processing. This may include co-flowing the third process gas during an ALE process step, such as modification or removal, during one or more ALE cycles, and / or flowing the third process gas while other process gases are not flowing, such as between removal and modification operations. An exemplary process may include performing a modification operation, followed by a purge, then flowing the third process gas, followed by another purge, and then a removal operation. Optionally, the conversion layer may be removed by separate modification operations using different modification molecules and separate removal operations using different removal molecules.

[0073] FIG. 1 illustrates an exemplary process flow diagram for performing operations according to disclosed embodiments. In block 101, a wafer is provided in a processing chamber configured to perform etching of the wafer. The wafer can have at least two materials deposited thereon, with a first material adjacent to and covering a surface of a second material. This covering can be a vertical covering, such that when the wafer is positioned on its bottom side, the first and second materials are disposed vertically, with the first material on top of and covering the second material. Alternatively, or additionally, this covering can be a horizontal covering, such that when the wafer is positioned on its bottom side, the first and second materials are disposed horizontally relative to each other, with the first material covering the second material. In some embodiments, both coverings can be both vertical and horizontal coverings. As mentioned above, this can involve the first material covering the second material along the sidewalls of a hole, via, or trench, creating additional challenges because the etch rate on the horizontal surfaces can exceed the etch rate on the vertical surfaces. For one single hole or via, etching of the vertical surfaces must continue while the conversion layer is formed on and above the horizontal surfaces.

[0074] In block 103, a modification operation of a first material, also considered the target material, may be performed. The modification operation may include flowing a first process gas containing modifying molecules onto the wafer to form a thin reactive surface layer that is more easily removed than the unmodified material in a subsequent removal operation. These modifying molecules may include, for example, halogen species such as chlorine or fluorine. While fluorine is used as an exemplary etchant species in the disclosed embodiment and may be flowed onto the substrate as hydrogen fluoride (HF), it will be understood that in some embodiments, a different etching gas is introduced into the chamber. The etching gas may be selected depending on the type and chemistry of the substrate being etched.

[0075] In some embodiments, activation energy can be provided to help the modifier molecules overcome the activation barrier for adsorption onto the semiconductor. This activation energy can be provided by thermal energy, radical energy, or both, which may include heating the substrate and / or generating a plasma or photons. This adsorption of the modifier molecules onto the first material can be considered chemical adsorption or "chemisorption," which is an energy-dependent (e.g., temperature-dependent) chemical reaction. In some thermal ALE techniques, this chemisorption during the modification operation can occur only over a specific temperature range that allows the molecules in the layer of material and the inflowing modifier molecules to overcome the activation barrier, thereby allowing dissociation and chemical bonding between these molecules and the adsorbate in the modifier molecules. Outside this temperature range, chemisorption may not occur or may occur at an undesirable (e.g., slow) rate.

[0076] Thus, some implementations of block 103 include modifying one or more surface layers of the material by chemisorption while the substrate is maintained at a first temperature, thereby forming one or more modified surface layers of the substrate. The substrate includes a layer of material and an exposed surface, which may be a uniform layer of material or a heterogeneous layer containing different molecules and elements. A first process gas having modifying molecules can be flowed over the substrate maintained at a first temperature. In some embodiments, the modifying molecules can include a halogen, such as fluorine, to halogenate the exposed molecules on the substrate, while in some embodiments, they can include oxygen to oxidize the exposed molecules on the substrate. In various embodiments, the modifying molecules are introduced into the chamber in gaseous or vapor form (e.g., including both gaseous and liquid forms), optionally accompanied by a carrier gas, such as nitrogen, argon, helium, or neon. This first temperature allows for chemisorption between the modifying molecules and at least some of the molecules on the exposed surface of the material.

[0077] Although the term "first temperature" is used, the temperatures discussed herein can be considered both specific temperatures or temperature ranges, as highlighted in FIGS. 2 and 3. In some embodiments, the first temperature can be, for example, about 20°C to 500°C, about 20°C to 150°C, about 20°C to 100°C, about 20°C to 80°C, about 200°C to 600°C, about 200°C to 500°C, about 200°C to 350°C, or about 350°C to 500°C. Additionally, the substrate can be maintained at that temperature for all, or substantially all (e.g., at least 80%, 90%, or 95%) of the modification operation. The duration of the modification operation can be a duration during which modification of substantially all (e.g., at least 80%, 90%, or 95%) of the desired exposed molecules on the substrate occurs. This may be in the range of, for example, about 0.5 seconds to about 10 seconds, 0.5 seconds to about 5 seconds, or about 1 second to about 5 seconds.

[0078] In some embodiments utilizing plasma-assisted modification, the plasma-generated species can be generated directly, for example, by forming a plasma in the process chamber containing the substrate, or can be generated remotely in a process chamber that does not contain the substrate and then delivered into the process chamber that contains the substrate.

[0079] Although not shown in FIG. 1 , an optional purge operation may be performed after block 103. In the purge operation, non-surface-bound active modifier molecules, such as fluorine or chlorine species, may be removed from the process chamber, chamber walls, chamber gas volume, and / or substrate. This can be done by purging and / or evacuating the process chamber to remove the active species without removing the adsorbed layer. Species generated within the plasma can be removed by stopping the plasma and allowing the remaining species to decay, optionally combined with purging and / or evacuating the chamber. Purging can be done using any inert gas, such as N2, Ar, Ne, He, and combinations thereof.

[0080] In block 105, a removal operation of the modified layer of the first material is performed. This may include flowing a second process gas containing removal molecules over the substrate and exposing the wafer to an energy source such as thermal energy, plasma, or an activated or sputtering gas, or a removal-inducing chemical reactive species such as argon or helium, to etch the substrate by directional sputtering. In some thermal ALE implementations, the removal operation may be performed at the same or substantially the same temperature (i.e., the first temperature) as the removal operation. In some other thermal ALE implementations, the removal operation may be performed at a second temperature or temperature range different from the first temperature range of the modification operation of block 103.

[0081] In the case of desorption, a particular temperature range can overcome the activation barrier of the modified molecules and release the modified layer from the surface of the substrate. In some instances, the temperature ranges in which chemisorption and desorption occur do not overlap, while in other instances they may overlap partially or completely. Thus, to remove molecules from a substrate using chemisorption and desorption, some embodiments may maintain the substrate at the same or substantially the same temperature during the removal and modification operations. To remove molecules from a substrate using chemisorption and desorption that occur in different temperature regimes, the modification operation in block 103 may occur in a first temperature range, and the removal operation in block 105 may occur in a second, different temperature range that is higher or lower than the first temperature. While some such embodiments may perform multiple cycles to remove multiple layers of material by maintaining the substrate at the same or substantially the same temperature during the removal and modification operations, other embodiments may repeatedly heat and cool the substrate between two temperature regimes for chemisorption and desorption.

[0082] In some embodiments using different temperature regimes, the temperature of the substrate can be brought to a second temperature, different from the first temperature, during or before block 105. In some other embodiments, the second temperature is the same as or substantially the same as the first temperature. This second temperature can be the temperature at which desorption occurs for one or more modified surface layers. In some embodiments, the second temperature can be higher than the first temperature, and in these embodiments, block 105 can include heating the substrate from the first temperature to the second temperature. In some other embodiments, the second temperature can be lower than the first temperature, and in these embodiments, the substrate can be actively cooled from the first temperature to the second temperature. The substrate can be heated using radiative heating, convective heating, solid-to-solid heat transfer, or with a plasma. Additionally, the top, bottom, or both of the substrate can be heated. In some embodiments, the heating of the substrate can be nonlinear, as discussed further below. As also described below, the substrate can be actively cooled in various manners.

[0083] In block 105, the one or more modified surface layers may be removed while the substrate is maintained at the second temperature. In some embodiments, the second temperature alone allows for desorption of the modified molecules from the substrate, thereby removing the modified molecules from the substrate by causing desorption. In some other embodiments, a second process gas having the removing molecules may be flowed over the substrate (including over the exposed surface of the substrate). The second process gas may also include a carrier gas, as described above. These removing molecules may react with the modified molecules to form different volatile molecules, e.g., volatilized molecules. The volatilized molecules may then be removed from the substrate by desorption when the substrate is at the second temperature.

[0084] In some embodiments, the second temperature may be, for example, about 20°C to 500°C, about 20°C to 150°C, about 20°C to 100°C, about 20°C to 80°C, about 200°C to 600°C, about 200°C to 500°C, about 200°C to 350°C, or about 350°C to 500°C. Additionally, the substrate may be maintained at that temperature for all or substantially all (e.g., at least 80%, 90%, or 95%) of the removal operation. The duration of the removal operation may be a duration that results in desorption of substantially all (e.g., at least 80%, 90%, or 95%) of the desired molecules on the substrate. This may be from about 0.5 seconds to about 10 seconds, from about 0.5 seconds to about 5 seconds, or from about 1 second to about 5 seconds. seconds , about 0.5 seconds to 2 minutes, or about 30 seconds to 2 minutes.

[0085] The performance of blocks 103 and 105 can be considered a single ALE cycle. In some embodiments, these blocks 103 and 105 can be repeated to perform multiple cycles and remove atomic monolayers as well as multiple layers of the first material.

[0086] In block 107, the surface of the second material is converted into a conversion layer, i.e., an etch stop layer, capable of or configured to withstand the etching chemistry used to remove the first material. This conversion occurs when the surface of the second material is freed or exposed (e.g., through removal of the first material, including removal of a modified layer of the first material) and in the presence of converting molecules of a third process gas that has been or is being flowed over the wafer. This conversion does not occur if the second material is still covered and not exposed to the converting molecules. In some embodiments, therefore, the etch front must remove the first material by modification and removal as described above to reach and expose the surface of the second material before or when the conversion of the second material occurs. While block 107 is illustrated after block 105, block 107 may occur simultaneously with or after block 105. Additionally, as discussed in more detail below, the third process gas containing the converting molecules may be flowed over the substrate in various ways, such as before and / or during the removal operation of block 105. In various embodiments, the conversion molecules are introduced into the chamber in vapor or gas form, optionally accompanied by a carrier gas such as, for example, nitrogen, argon, helium, or neon.

[0087] FIG. 2 illustrates an exemplary schematic diagram of atomic layer etching according to disclosed embodiments. In diagrams 202a-202e, a single layer of material is etched from a wafer. In 202a, a wafer is provided having a first material, indicated by a shaded circle, having two layers, and a second material, indicated by a white circle, adjacent to and covered by the first material, having three layers. Molecules of the first material are labeled 204, and molecules of the second material are labeled 206. The top layer of the first material can be considered a surface layer 208 of the first material. In 202b, a first process gas having modifying molecules 210 (black circles, some of which are identified by identifier 210) is introduced to the substrate to modify the surface layer 208 of the substrate. The schematic diagram of 202b shows that some of the modifying molecules 210 are adsorbed onto molecules 204 of the surface layer 208 of the substrate, thereby forming a modified surface layer 212 containing modified molecules 214 (one modified molecule 214 is identified inside the dotted oval in 202b). In some thermal ALE techniques, this diagram 202b may occur while the substrate is maintained at the first temperature described above, e.g., a temperature that allows for chemisorption of the modifying molecules on the surface of the first material. In some other implementations, this modification operation may be plasma-assisted. While this diagram shows a single layer being modified, in some embodiments, multiple layers of the first material may be modified.

[0088] In 202c, after the modified molecules 214 and modified surface layer 212 are formed in 202b, the first process gas may optionally be purged from the chamber. In 202d, removal molecules 216 are introduced into the process chamber; in some embodiments, this may occur by flowing a second process gas containing the removal molecules 216 over the substrate. In some thermal ALE embodiments, this removal operation may be performed at a second temperature at which desorption of the modified molecules 214 of the modified surface layer 212 from the substrate occurs; some of these removal operations may not utilize a plasma. In some embodiments, the second temperature is the same as or substantially the same as the first temperature. In other embodiments, the first and second temperatures may be different from one another; in these embodiments, the temperature may be changed from the first temperature to the second temperature by heating or cooling the substrate. In some other embodiments, the second process gas is introduced with a plasma or a directed plasma, and ion bombardment may be performed to remove the modified surface of the substrate. During plasma-assisted operation, a bias may be applied to the substrate to attract ions to the substrate. While this diagram shows a single layer being removed, in some embodiments, multiple layers of the first material may be removed if previously modified. In 202e, the modified molecules 214, and thus the modified surface layer 212, have been removed from the substrate, leaving a second layer 218 of the first material overlying the second material. In the example illustrated in 202e, the modified molecules 210 are not present, but in some embodiments, these modified molecules 210 may be present, for example, as shown in 202b. In some such embodiments, these modified molecules 210 may be introduced in a subsequent process step, such as in diagrams 202f and 202g.

[0089] Diagrams 202f and 202g depict a wafer during and / or after a removal operation, illustrating exemplary transformations of the surface of the second material. During the operations of diagrams 202a-202e, the second material remains covered by the first material; the surface of the second material is not exposed by these operations. In diagram 202f, removal molecules 216 remove or etch a portion of the first material, i.e., a portion of the modified layer 218 of the first material, from that covering the second material 206, thereby exposing the surface of the second material, i.e., liberating this surface through the removal of the modified layer 218 of the first material. This exposed surface of the second material 206 is shown in diagram 202f, with three molecules of the second material 206 within a dotted rectangle 220. Due to the chemistry used to remove the first layer of material, this second material is vulnerable to etching, including, for example, etching at a higher etch rate than the first material. Here, in diagram 202f, a third process gas containing conversion molecules 222 (shown as shaded diamonds) is flowed over the wafer or co-flowed with the second process gas over the wafer, and these conversion molecules 222 convert the exposed surface 220 of the second material into a converted layer of material. In diagram 202g, three molecules of the exposed surface 220 of the second material have been converted by the conversion molecules 222 into a converted layer 224 of material, as shown by the three molecules or converted molecules having a dark shading. This converted layer 224 is an etch stop layer that can withstand the etching chemistry.

[0090] In diagram 202h, the second layer 218 of the first material has been removed, and the illustrated surface of the second material has been converted to a converted layer 224 of material, i.e., converted molecules. In some embodiments, as shown in diagram 202i, the converted layer of material may be removed. This removal may include two operations: a modification operation involving flowing a fourth process gas having other modifying molecules to modify these converted molecules into different volatilized molecules, and a removal operation involving flowing a fifth process gas having other removal molecules (such as molecules 226 in diagram 202i). Like the other process gases, the fourth and fifth process gases may include a carrier gas as listed above. Additionally, these modification and removal steps of the converted layer 224 may be performed sequentially, overlapping, or simultaneously using alternating, overlapping, or concurrent flows of the fourth and fifth process gases.

[0091] In some cases, the illustrations of diagrams 202f and 202g may be considered to be forming an "on-the-fly" etch stop layer. When a second layer of material is exposed and in the presence of a converting molecule, a converted layer of material is formed "on-the-fly." This allows etching of the first material to continue while the exposed underlying second material is protected by the converted or etch stop layer.

[0092] As noted above, in some embodiments, conversion of the second layer of material can occur through cation exchange between the second layer of material and conversion molecules. In some such implementations, the third process gas provides a cation component in the vapor phase that exchanges with a cation compound or component in the layer of material. The cation component of the second material can be converted to a chloride and thereby volatilized as a result of the exchange with the cation component in the third process gas.

[0093] For example, the second material may be zinc oxide, the conversion molecule may be a zirconium compound, and the conversion of the surface of the second material may be a cation exchange of zinc with zirconium to form a zirconium oxide conversion layer on the material. In further examples, the conversion reaction at the surface of the second material comprising zinc may be as follows: Example 1, the second material comprises ZnO (solid) and the third process gas comprises ZrCl4 (gas), thus converting the second material into a conversion layer of ZrO2 (solid) and ZnCl2 (gas), thereby exchanging and removing zinc; Example 2, the second material comprises In2O3 (solid) and the third process gas comprises ZrCl4 (gas), thus converting the second material into a conversion layer of ZrO2 (solid) and InCl3 (gas), thereby exchanging and removing indium; Example 3, the second material comprises Ga2O3 (solid) and the third process gas comprises ZrCl4 (gas), thus converting the second material into a conversion layer of ZrO2 (solid) and GaCl3 (gas), thereby exchanging and removing gallium.

[0094] In these examples, the first material may be Al2O3 (solid), which can be etched by primary chemicals such as HF and trimethylaluminum (TMA). As can be seen in these examples, the cationic components of the second material, zinc, indium, and gallium, are converted to chlorides, which are volatilizable and therefore removable.

[0095] The techniques provided herein may be applicable to wafers having first and second materials with similar properties. This may include, for example, oxides, high-k oxides, and / or materials that are both oxides and semiconductor oxides that can both be etched by the chemistry used to etch the first material. Some examples may include aluminum oxide as the first material and zinc oxide as the second material.

[0096] The techniques provided herein form a converted layer of material capable of and configured to withstand chemicals used to etch a first material, for example, by a converted layer of material that is less reactive to the etching chemicals than the second layer and modified layer of material. This reactivity can be quantified according to various chemical and physical properties, such as etch rate, binding energy, and reactivity. In some embodiments, the relationship between the first material, the modified layer of the first material, the second material, and / or the converted layer of material can be quantified by etch rate. For example, a chemical used to etch a first material may etch the first material (including the modified layer) at a first etch rate and also etch the second material at an unacceptable second etch rate. In some cases, this second etch rate may be greater than or equal to the first etch rate, e.g., at least 50%, 100%, or 200% or greater than the first etch rate. When exposed to a chemical to remove the first material including the modified layer, the converted layer can have an etch rate less than the first etch rate, including less than or equal to 50%, 25%, 15%, 10%, 5%, 2.5%, or 1% of the first etch rate. In one example, the chemical for etching the first material may etch the second material at a second etch rate that is about twice the first etch rate and etch the converted material at a third etch rate that is less than 15% of the first etch rate. In these embodiments, the converted layer of material is considered to be capable of and configured to withstand the chemical used to etch the first material.

[0097] In some embodiments, the relationship between the first material, the modified layer of material, the second material, and / or the converted layer of material can be quantified by reaction by-products. In some cases, the chemical used to remove the first material may react with the second material to produce by-products, which may remove or possibly adversely affect the second material. However, the converted layer of material may, in some such embodiments, react with the removal chemical without producing any by-products or only producing a limited amount of by-products. In some embodiments, the converted layer of material may not react with the removal chemical or may have a limited reaction with the removal chemical. This may prevent or reduce removal of the second material. In some cases, the converted layer of material may be considered passive with respect to the removal chemical.

[0098] Returning to the various techniques provided herein, the third process gas for converting the exposed surface of the second material into a converted layer can be flowed onto the substrate in various ways. In some embodiments, the third process gas may be flowed at various times and / or during various aspects of the etching process and / or ALE cycle. This may include flowing the third process gas before the modification operation, during the modification operation, after the modification operation and before the removal operation, during the removal operation, and / or after the removal operation. In some such embodiments, a purge gas may also be flowed into the chamber after flowing the third process gas and before flowing another process gas.

[0099] In some embodiments, the flow of the third process gas can be initiated during these described periods and stopped during any of the described periods or operations. This may include starting and stopping the flow one or more times during the etching process or ALE cycle. For example, in a single ALE cycle, the flow of the third process gas can be initiated before the modification operation and continue to flow until the end of the removal operation. In another example, the flow of the third process gas can be initiated before or at the beginning of the modification operation, stopped at the end of the modification operation, then started again at the beginning of the removal operation, and stopped at or after the end of the removal operation. In yet another example, the flow of the third process gas can be initiated only after the modification operation or at the beginning of the removal operation, continue throughout the removal operation, and stop at or after the end of the removal operation. In another example, the flow of the third process gas can be initiated during the modification operation, but continue after the start of the modification operation until the end of or after the removal operation. In yet another example, the third process gas may be flowed while the first and second process gases are not flowing, such as before the modification operation, between the modification operation and the removal operation, and / or after the removal operation.

[0100] It should be noted that in some embodiments, the flow of the third process gas and the conversion of the exposed surface of the second material may not occur simultaneously. As discussed herein, the conversion occurs when the surface of the second material is exposed, and the third process gas may be flowed over the substrate before and / or when this surface is exposed during the removal operation. For example, the third process gas may flow over the substrate only before the removal operation and not during the removal operation, such as during or after a modification operation, but the third process gas may still be present during the removal operation so that the conversion molecules can react with the surface of the second material when it is released and exposed. This is discussed in more detail below, including with reference to Figures 6A-6D.

[0101] FIG. 3 illustrates another exemplary process flow diagram for performing operations according to disclosed embodiments. In FIG. 3, blocks 301, 303, and 305 are the same as blocks 101, 103, and 105 of FIG. 1, except that a third process gas is co-flowed or simultaneously flowed over the wafer in block 309 during some or all of the modification operation in block 303. Block 309 can begin simultaneously with or after the start of the modification operation in block 303; in some embodiments, block 309 can begin before the start of the modification operation in block 303. In block 307, the surface of the second material is converted to a converted layer when exposed and in the presence of the third process gas. In some embodiments, the third process gas can be co-flowed during the removal operation in block 305. In some other embodiments, the third process gas is not flowing during the removal operation in block 305, but the third process gas is still present around the wafer so that the surface of the second material is freed and exposed and converted to a converted layer. An optional purge may be performed after blocks 303 and / or 309.

[0102] 4A illustrates yet another exemplary process flow diagram for performing operations according to disclosed embodiments. In FIG. 4A, blocks 401, 403, and 405 are the same as blocks 101, 103, and 105 of FIG. 1, except that a third process gas is co-flowed or simultaneously flowed over the wafer in block 407 during some or all of the removal operation in block 405. Also, in block 407, the surface of the second material is converted to a converted layer when exposed and in the presence of the third process gas. In some embodiments, block 407 can begin simultaneously with or after the start of the removal operation in block 405; in some embodiments, block 407 can begin before the start of the removal operation in block 405.

[0103] FIG. 4B illustrates another exemplary process flow diagram for performing operations according to disclosed embodiments. In FIG. 4B, blocks 401, 403, and 405 are the same as FIG. 4A, except that a third process gas is flowed between the modification operation of block 403 and the removal operation of block 405, such that in some embodiments, the third process gas is not flowed onto the substrate between blocks 403 and 405. During the removal operation of block 405, similar to block 307 in FIG. 3, block 411 indicates that the surface of the second material is converted to a conversion layer when exposed and in the presence of the third process gas. In some embodiments, an optional purge operation may be performed after block 409 and before blocks 405 and 411.

[0104] Alternatively or additionally, the third process gas may be flowed only during a portion of the total etching performed on the wafer. This may include, for example, flowing the third process gas after performing N ALE cycles on the wafer, where the total number of ALE cycles is N+X ALE cycles. This may also include flowing the third process gas after performing a portion of the ALE cycles, such as after performing at least 10%, 50%, 80%, or 95% of the total ALE cycles. FIG. 5 illustrates another exemplary process flow diagram for performing operations according to disclosed embodiments. Blocks 501, 503, and 505 of FIG. 5 are the same as those of FIG. 1, where blocks 503 and 505 are repeated for N ALE cycles or etching cycles. If decision step 511 determines that N ALE cycles have been performed, block 507 is performed, during which a third process gas is flowed over the wafer to convert the surface of the second material into a conversion layer when the surface is exposed and in the presence of the third process gas. This block 507 may be performed for one or more etching cycles after N cycles have been performed. Block 507 may also be performed in any manner described herein, such as by flowing a third process gas between the modification and / or removal operations, or between the modification and removal operations, as shown in FIG.

[0105] Additional illustrations for flowing a third process gas during some etching operations are shown in FIGS. 6A-6D, which illustrate schematic diagrams of ALE cycles according to disclosed embodiments. In these FIGS. 6A-6D, diagrams 602a-602f illustrate a wafer during a single ALE cycle. 602a shows the wafer before a modification operation, corresponding to operation 202e in FIG. 2. For example, the shaded circles represent a first layer of material, and the open circles represent a second layer of material. Diagram 602b, similar to diagram 202b, illustrates the wafer during a modification operation during which a first process gas containing modification molecules 610 is flowed over the wafer, forming modified molecules 614 and a modified layer 618 of the first material. In some thermal ALE implementations, the modification in diagram 602b may be performed while the substrate is maintained at a first temperature or a first temperature range. 602c shows the wafer with modified layer 618 after the modification operation of diagram 602b and before the removal operation.

[0106] Diagrams 602d and 602e of Figures 6A-6D show a wafer during a removal operation and may correspond to diagrams 202f and 202g of Figure 2. In diagram 602d, a second process gas containing removal molecules 616 is flowed over the wafer, causing removal of modified molecules 614 that free and expose a surface 820 of the second material. Also in diagram 602d, conversion molecules 622 are present around the wafer, and in the presence of conversion molecules 622, the exposed surface 820 of the second material is removed, as shown in diagram 602e. 620 is converted to a conversion layer 624. In illustration 602f, the modified layer 624 is removed, leaving the conversion layer, which may correspond to illustration 202h in Figure 2. Although not shown here, an optional separate modification and removal operation can be performed to remove the conversion layer.

[0107] In some embodiments, the removal operations of diagrams 602d and 602e in Figures 6A-6D can be performed using a thermal ALE in which the substrate is maintained at the same or substantially the same temperature as the modification operation of diagram 602b. In some other embodiments, these removal operations of diagrams 602d and 602e can be performed while the substrate is maintained at a second temperature or second temperature range that is different from the first temperature or first temperature range of the modification operation of diagram 602b. Some implementations can include heating or actively cooling the substrate between diagrams 602b and 602d and 602e to vary the substrate temperature. In some other embodiments, the modification operation of diagram 602b and / or the removal operations of diagrams 602d and 602e can be plasma-assisted operations.

[0108] 6A-6D further illustrate various flows of a third process gas over the wafer. In FIG. 6A, a third process gas having conversion molecules 622 is flowed over the wafer at least in diagram 602a before the modification operation in 602b. As shown, conversion molecules 622 in FIG. 6A are present between diagrams 602a-602e, and in some embodiments, FIG. 6A may illustrate the third process gas flowing during the entire ALE cycle. In some such embodiments, the third process gas may begin flowing over the wafer in diagram 602a before the modification operation in 602b and continue flowing over the wafer after the modification operation in diagram 602c and during the removal operations in diagrams 602d and 602e. In some embodiments, the third process gas may flow only during diagram 602a (which may be considered to be flowing while the first and second process gases are not flowing), only between diagrams 602a and 602b, or only between diagrams 602a, 602b, and 602c, and then stopped, while the third process gas with the converted molecules continues to be present in diagrams 602a-602e, which may still be considered a complete ALE cycle. For example, the third process gas may flow only between diagrams 602a and 602b, and then stopped, but continue to be present between diagrams 602c-602e.

[0109] In Figure 6B, a third process gas having conversion molecules 622 is flowed over the substrate during at least a portion of the modification operation of diagram 602b. As noted above, the third process gas flow can be initiated simultaneously with or after the initiation of the modification operation. In some embodiments, the third process gas may continue to flow over the wafer after the modification operation of diagram 602c and during the removal operations of diagrams 602d and 602e. In some embodiments, the flow of the third process gas may be stopped after the modification operation, an optional purge may be performed, and then the third process gas may not be flowed thereafter, such as during the removal operations of diagrams 602d and 602e, although the third process gas may still be present. In some other implementations, the flow of the third process gas may be stopped after the modification operation, an optional purge may be performed, and then the flow of the third process gas may be initiated before or during the removal operations of diagrams 602d and 602e. As shown, a third process gas having converting molecules 622 continues to be present between diagrams 602b-602e even if it is not flowing between some or all of these diagrams, e.g., not flowing between 602d and 602e. Some embodiments of this Figure 6B may correspond to the technique of Figure 3.

[0110] In Figure 6C, a third process gas having conversion molecules 622 is flowed over the substrate after the modification operation of diagram 602b and before the removal operation, as shown by the conversion molecules present in diagram 602c. In some embodiments, the flow of the third process gas does not flow during the removal operations of diagrams 602d and 602e, but may be turned off so that it is still present during these operations, which can be considered a flow while the first and second process gases are not flowing. Some embodiments of this Figure 6C may correspond to the technique of Figure 4B. In some embodiments, the third process gas may continue to flow over the wafer after the modification operation of diagram 602c and during the removal operations of diagrams 602d and 602e.

[0111] In Figure 6D, a third process gas is flowed over the substrate during the removal operations of diagrams 602d and 602e. As noted above, the third process gas flow can begin simultaneously with or after the start of the removal operations. Some embodiments of this Figure 6D may correspond to the technique of Figure 4A.

[0112] Depending on the chemistry involved in the ALE operation, it may be advantageous to flow a third process gas at various times, including those shown in Figures 6A-6D. For example, the third process gas may be incompatible with or react undesirably with the first process gas and / or the first layer of material. Therefore, it may be advantageous to prevent or reduce these undesirable effects by flowing only the third process gas, for example, after the modification operation and / or during the removal operation shown in Figures 6C and 6D. In some other embodiments, the undesirable effects of flowing a third process gas during the ALE cycle are limited, and thus, for example, it may be flowed throughout the ALE cycle, as shown in Figure 6A.

[0113] In some embodiments, the flow rate of the third process gas may remain constant. In other embodiments, it may be advantageous to vary the flow rate of the third process gas. This may include, for example, increasing the flow rate of the third process gas during the removal operation to provide more converted molecules as the removal operation progresses. Some exemplary flow rates may be between about 50 sccm and 1000 sccm.

[0114] In some embodiments, converting the second layer of material into an etch stop layer may be considered as selectively converting a surface of the second material into a layer of etch stop material when the surface of the second material is released via removal of the modified layer, the layer of etch stop material being positioned only over the second material. In some such embodiments, during removal, the modified layer of the first material and the layer of etch stop material may be exposed to a second process gas, which may be less reactive with the layer of etch stop material than the modified layer of the first material and the second material.

[0115] In some embodiments, instead of converting the layer of the second material to a conversion layer, selective deposition can be performed to deposit an etch-stop layer on the second material. This deposition can be performed after or simultaneously with the removal operation, as the case may be. In some embodiments, this selective deposition of the layer of etch-stop material can occur when the surface of the second portion of the second material is free. This selectivity can also include depositing the layer of etch-stop material on the freed second material, but is limited to not depositing the layer of etch-stop material on the targeted first material. In some embodiments, this can include selectively converting the surface of the second material to a layer of etch-stop material once the surface of the second material is freed via removal of the modified layer, where the layer of etch-stop material is positioned only on the second material, such that during removal, the modified layer of the first material and the layer of etch-stop material are exposed to a second process gas, which is less reactive with the layer of etch-stop material than with the modified layer of the first material and the second material.

[0116] The deposited etch stop layer can have the same properties and characteristics as the conversion layer described above, including a deposited etch stop layer capable of and configured to withstand the chemicals used to etch the first material, including having an etch rate lower than the first etch rate (i.e., the etch rate at which the chemical removes the first material, including the modified layer), including 50%, 25%, 15%, 10%, 5%, 2.5%, or 1% or less of the first etch rate; a binding energy greater than the binding energy of the modified layer and / or equal to or greater than the binding energy of the chemical species used for removal; and / or a binding energy that reacts with the removal chemical without producing any or limited amounts of by-products.

[0117] The selective deposition may occur in the same chamber or in a different chamber. This selective deposition can be achieved using various deposition processes, such as chemical vapor deposition (CVD) or atomic layer deposition (ALD). Some CVD processes may deposit a film on a wafer surface by flowing one or more gas reactants that form film precursors and by-products into a reactor. The precursors are delivered to the wafer surface, where they are adsorbed by the wafer, diffuse into the wafer, and deposited on the wafer through a chemical reaction that involves the generation of a plasma in PECVD.

[0118] In a typical PECVD reaction, a substrate is heated to an operating temperature and exposed to one or more volatile precursors that react and / or decompose to produce the desired deposit on the substrate surface. The PECVD process generally begins by flowing one or more reactants into a reaction chamber. Reactant delivery can continue while a plasma is generated and the substrate surface is exposed to the plasma, thereby causing deposition on the substrate surface. This process continues until the desired film thickness is reached, after which the plasma is typically extinguished and the flow of reactants is stopped. The reaction chamber can then be purged, and post-deposition steps can be performed.

[0119] Some other deposition processes involve multiple film deposition cycles, each producing a "discrete" film thickness. ALD is one such film deposition method, but any technique used repeatedly in succession to form thin layers of film can be considered to involve multiple deposition cycles. ALD is a film formation technique well suited to depositing conformal films due to the fact that a single ALD cycle deposits only a single thin layer of material, with the thickness limited by the amount of one or more film precursor reactants that can adsorb to the substrate surface (i.e., form an adsorption-limiting layer) prior to the film-forming chemical reaction itself. Multiple "ALD cycles" can then be used to build up films of desired thickness, each thin and conformal so that the resulting film substantially conforms to the shape of the underlying device structure. In certain embodiments, each ALD cycle includes the following steps: (1) exposure of the substrate surface to a first precursor; (2) purging of the reaction chamber in which the substrate is located; (3) activation of a reaction on the substrate surface, typically with a plasma and / or a second precursor; and (4) purging of the reaction chamber in which the substrate is located. The duration of each ALD cycle can typically be less than 25 seconds, or less than 10 seconds, or less than 5 seconds. The plasma exposure step (or steps) of an ALD cycle can be of short duration, such as, for example, 1 second or less. The plasma can also be of other durations longer than 1 second, such as, for example, 2 seconds, 5 seconds, or 10 seconds.

[0120] Purpose The techniques and apparatus provided herein can be used with a variety of chemistries. In one example, the first material can be aluminum oxide and the second material can be zinc oxide. The aluminum oxide can be etched using a process gas containing the removal molecule trimethylaluminum (TMA), which can also remove the underlying zinc oxide. To prevent the zinc oxide from being removed by the TMA, a third process gas containing a zirconium conversion molecule can be flowed over the wafer to convert the zinc oxide layer into a zirconium oxide conversion layer that does not react with TMA. In some embodiments, the zirconium conversion molecule can include zirconium tetrachloride. In some embodiments, the zirconium oxide conversion layer can be removed by flowing a fourth process gas containing dimethylaluminum chloride (DMAC) over the wafer. In some cases, removal of this conversion layer or etch stop layer can include flowing hydrogen fluoride (HF) as a modification operation followed by flowing DMAC in a removal operation.

[0121] As also noted above, another example may include aluminum oxide covering a second material, which may be indium gallium zinc oxide (IGZO). To etch this aluminum oxide, a first process gas containing hydrogen fluoride (HF) may be used in the modification operation, and the removal molecule may include TMA, which can again remove the underlying IGZO. Thus, a third process gas may be used, such as zirconium chloride, e.g., ZrCl4, to convert the exposed IGZO surface to zirconium oxide, such as ZrO2 (solid) or ZrO2. 、 or zirconium, such as tetrakis(ethylmethylamino)zirconium(IV) (TEMAZ). In this example and the example above, etching of the aluminum oxide layer can continue during the conversion reaction.

[0122] ALE device Referring now to FIG. 7 , an example of a substrate processing chamber 720 for selectively etching materials according to the present disclosure is shown. While a particular substrate processing chamber is shown and described, the methods described herein may be implemented on other types of substrate processing systems. FIG. 7 illustrates an exemplary apparatus 720 for semiconductor processing according to disclosed embodiments, including thermal atomic layer etching, which includes a processing chamber 722, a process gas unit 724, a substrate heating unit 726, and a substrate cooling unit 728. The processing chamber 722 has a chamber wall 730 that at least partially bounds and defines a chamber interior 732 (which may be considered a plenum volume). The process gas unit 724 is configured to flow a process gas, which may include liquids and / or gases, such as reactants, modifying molecules, converting molecules, or removing molecules, over a substrate 734 in the chamber interior 732. The process gas unit 724 also includes one or more flow features 742, such as holes, nozzles (two of which are shown), or showerheads, configured to flow a first process gas onto the substrate 734. The one or more flow features 742 can be positioned above, below, to the sides, or a combination of locations within the chamber interior 732, such as, for example, on the walls, top, and bottom of the processing chamber. The process gas unit 724 may include a mixing vessel for blending and / or conditioning the process gases delivered to the chamber interior 732. One or more mixing vessel inlet valves can control the introduction of the process gases into the mixing vessel.

[0123] The process gas unit 724 may include a first process gas source 736, a first process liquid source 738, a vaporization point (not shown) capable of vaporizing the first liquid into a gas, and a carrier gas source 740. Some reactants may be stored in liquid form before vaporization and after delivery to the process chamber 722. The first process gas may, in some embodiments, include an oxidizing gas, a halogenated gas, or another gas configured to modify one or more layers of material on a substrate without the use of a plasma. In some implementations, the vaporization point may be a heated liquid injection module. In some other implementations, the vaporization point may be a heated vaporizer. In still other implementations, the vaporization point may be eliminated from the process station. In some implementations, a liquid flow controller (LFC) may be provided upstream of the vaporization point to control the mass flow rate of the liquid vaporized and delivered to the chamber interior 732. The carrier gas source 740 includes one or more carrier gases or liquids that can be flowed with the process gas, which may be inert gases such as N2, Ar, Ne, or He. The apparatus 720 may also include a vacuum pump 733 configured to pump the interior of the chamber to a low pressure, such as a vacuum having a pressure of 1 mTorr or 10 Torr, for example.

[0124] The chamber interior 732 includes substrate support features 735 configured to support and thermally levitate a substrate 734 within the chamber. The substrate support features 735 may include, for example, clamps, horizontal pins or supports, vertical pins or supports, and semicircular rings that support the substrate 734 within the chamber interior 732. These features are configured to support the substrate 734 such that the thermal mass of the substrate 734 is reduced as much as possible to the thermal mass of the substrate alone. Thus, each substrate support feature 735 can minimize contact with the substrate 734 and may be the minimum number of features required to adequately support the substrate during processing (e.g., to support the weight of the substrate and prevent inelastic deformation of the substrate). For example, the surface area of ​​one substrate support feature 735 in contact with the substrate may be less than about 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the total surface area of ​​the backside of the substrate, and for example, two, three, or four features may also be utilized.

[0125] In one example, the support feature 735 may include two or more vertical pins having a groove that is wound or spiraled along a vertical longitudinal axis and offset at various distances from the longitudinal axis and configured to support a substrate. As the vertical pin rotates along its longitudinal axis and the edge of the substrate is positioned within the groove, the edge of the groove, and therefore the edge of the substrate, moves further away from the longitudinal axis. When multiple vertical pins are used to support a substrate, rotation of the vertical pins causes the grooves to apply a support force to the substrate in a direction perpendicular to the longitudinal axis.

[0126] In some embodiments, the chamber 722 may include a wafer support pedestal including substrate lift pins. During thermal ALE processing, the lift pins may support and position the substrate from the pedestal such that there is substantially no thermal energy transfer between the pedestal and the substrate (e.g., less than 10%, 5%, 1%, 0.5%, or 0.1% of the energy transferred between the two). In other embodiments, the chamber 722 may not have a pedestal. In some embodiments, an electrostatic chuck (ESC) may be used that includes a substrate heating unit 726 configured to heat the substrate to a temperature provided herein, such as between about 20°C and 500°C.

[0127] The substrate heating unit 726 is configured to heat the substrate to multiple temperatures and maintain such temperatures for, for example, at least 1 second, 5 seconds, 10 seconds, 30 seconds, 1 minute, 2 minutes, or 3 minutes. In some embodiments, the substrate heating unit 726 is configured to heat the substrate between at least two temperature ranges (a first range is about 20°C to 150°C, and a second range is about 200°C to 600°C) and maintain the substrate at a temperature within these ranges for, for example, at least 1 second, 5 seconds, or 10 seconds. Additionally, in some embodiments, the substrate heating unit 726 is configured to heat the substrate from the first temperature range to the second temperature range in, for example, less than about 250 milliseconds, 150 milliseconds, 100 milliseconds, or 50 milliseconds.

[0128] The substrate heating unit 726 can utilize radiant heating, convective heating, laser heating, plasma heating, solid-state heat transfer, or a combination thereof. For radiant heating, the substrate heating unit 726 can be used for radiant light heating, infrared heating, ultraviolet heating, microwave heating, radio frequency heating, and induction heating. For example, the substrate heating unit 726 can include light-emitting diodes (LEDs) that emit visible light having wavelengths ranging from 400 nanometers (nm) to 800 nm. In another example, infrared heating can use one or more infrared emitters (e.g., near-infrared heaters) that emit infrared radiation in the range of 780 nanometers (nm) to 1400 nm, one or more infrared emitters (e.g., mid-infrared heaters) that emit infrared radiation in the range of 1400 nm to 3000 nm, and one or more infrared emitters (e.g., far-infrared heaters) that emit infrared radiation above 3000 nm. This may include, for example, heat lamps, light-emitting diodes (e.g., LEDs), ceramic heaters, quartz heaters, or multiple gradient index (GRIN) lenses connected to an optical energy source. The GRIN lens is configured to deliver thermal energy (heat or light) from the optical energy source to the substrate in a uniform manner, and the light source may be a laser or high-intensity light source that transfers thermal energy to the GRIN lens through a conduit such as a fiber optic cable. The heating elements utilized by the substrate heating unit 726 may be positioned above, below, to the side of the substrate 734, or a combination thereof, and may be positioned inside, outside, or both of the chamber interior 732. In FIG. 7 , the heating elements utilized by the substrate heating unit 726 include multiple LEDs 726A positioned both above and below the substrate 734, with a lower heating element positioned inside the chamber interior 732 and an upper heating element positioned outside the chamber interior 732. In some embodiments, for portions of the heating element positioned outside the chamber 722, the chamber 722 may have a window 754 that allows radiation to be transmitted into the chamber interior 732 and onto the substrate 734.In some embodiments, this window 754 may be an optical-grade quartz plate, while in other embodiments it may be a transparent indium tin oxide (ITO) window. In some embodiments, the substrate heating unit 726 includes multiple LEDs 726A and may be positioned only below the substrate 734, which may include an interior of the pedestal or ESC that may also include a window through which light emitted by the LEDs can pass to reach the backside of the substrate.

[0129] For convection heating, the substrate heating unit 726 can flow heated gas into the chamber interior 732 to heat the substrate. The substrate heating unit 726 can include a heated gas source, a heating unit configured to heat the heated gas to a desired temperature, such as at least 20° C., 100° C., 250° C., 350° C., 500° C., and 600° C., and heated flow features, such as nozzles or holes, that allow the heated gas to flow into the chamber interior 732 and over the substrate 734. These heated flow features can be positioned above, below, to the side of the substrate, or a combination thereof.

[0130] In the case of laser heating, the substrate heating unit 726 can have one or more lasers configured to heat the substrate inside the chamber. These lasers can be stationary or configured to move (e.g., scanning lasers) and can be positioned above, below, or both above the substrate; the lasers can also be positioned inside, outside, or both above and below the chamber interior. As with radiant heating described above, in the case of lasers positioned outside the chamber interior, the chamber can include a window that allows the laser emission to reach the substrate.

[0131] In the case of plasma heating, the substrate heating unit 726 can have features configured to generate and maintain a plasma inside the chamber to heat the substrate. Features that can generate a plasma are discussed in more detail below. Additionally, in some embodiments, the chamber interior can include vertical pins positioned below the substrate and configured to support the wafer. During substrate heating, the substrate can be supported only by the vertical pins, and a plasma can be generated between the bottom of the substrate and a surface below the substrate, such as the bottom wall of the chamber or a wafer support pedestal. This plasma can heat and maintain the temperature of the substrate at a desired temperature.

[0132] In the case of solid-state heat transfer, the substrate heating unit 726 can have one or more heating surfaces configured to contact and heat the substrate inside the chamber. In some embodiments, the substrate heating unit 726 can have a heating platen, such as a flat surface or the surface of a substrate pedestal, configured to contact and heat the backside of the substrate. This heating platen may have heating elements, such as heating coils, heating fluid, or the radiant heating described above, that can heat the surface of the heating platen. The substrate can be heated when the backside of the substrate is in direct contact with the heating platen or is offset from the heating platen but close enough to receive thermal energy from the heating platen. When this solid-state heat transfer is used to heat the substrate, the substrate is separated from the heating platen when it cools. While some conventional ALE devices may have a substrate pedestal that includes both heating and cooling elements, these devices cannot rapidly cycle between thermal ALE temperatures (e.g., in less than 250 milliseconds) due to the large thermal mass of the pedestal, which is repeatedly heated and cooled. For example, it may take several seconds or minutes to heat the pedestal from a first temperature range (e.g., 20°C-100°C) to a second temperature range (e.g., 200°C-500°C), and several seconds or minutes to cool the pedestal from the second temperature range to a lower temperature that can cool the substrate to the first temperature range. Therefore, after using this solid-to-solid heating technique, the heating platen and substrate are separated from each other, which may be achieved, for example, by moving the substrate and / or heating platen away from each other. Without this separation, cooling of the thermal mass of both the substrate and heating platen occurs, increasing cooling time and reducing substrate throughput. In some embodiments, an ESC or pedestal with a substrate heating unit and cooling Peltier elements can enable fast heating and cooling times (e.g., about 30 seconds to cool the substrate to the desired temperature).

[0133] The substrate cooling unit 728 of FIG. 7 is configured to actively cool the substrate. In some embodiments, the substrate cooling unit 728 flows a cooling gas over the substrate 734 to actively cool the substrate 734. The substrate cooling unit 728 can include a cooling fluid source 748 that can include a cooling fluid (gas or liquid) and a chiller 750 configured to cool the cooling fluid to a desired temperature, such as, for example, 0° C., −50° C., −100° C., −150° C., −170° C., −200° C., and −250° C. or lower. The substrate cooling unit 728 includes piping and coolant flow features 752, e.g., nozzles or holes, configured to flow the coolant fluid into the chamber interior 732. In some embodiments, the fluid can be in a liquid state when flowing into the chamber 722 and can change to a vapor state upon reaching the chamber interior 732, for example, if the chamber interior 732 is at a low pressure, such as, for example, 1 Torr. The cooling fluid can be an inert element, such as nitrogen, argon, or helium. In some embodiments, the flow rate of the cooling fluid into the chamber interior 732 may be, for example, at least 10 liters / second, 50 liters / second, 100 liters / second, 150 liters / second, 200 liters / second, 250 liters / second, and 300 liters / second.

[0134] Various factors can increase the ability of a cooling fluid to cool a substrate. It has been discovered through various experiments that a higher cooling fluid flow rate will cool the substrate faster. In one exemplary experiment, it was found that flowing a cooling gas at approximately -196°C over a substrate at a flow rate of 1 liter / second reduced the substrate temperature from approximately 220°C to approximately 215°C in approximately 5,000 milliseconds, while flowing the same cooling gas at a flow rate of 10 liters / second reduced the substrate temperature from approximately 220°C to approximately 195°C in approximately 5,000 milliseconds. It has also been discovered that the gap between the substrate and the top of the chamber (1052 in Figure 10) can also affect substrate cooling, with a smaller gap resulting in faster cooling. In one example, it was discovered that a substrate separated from the top of the chamber by a gap of about 50 micrometers was cooled from about 220°C to about 215°C in about 5,000 milliseconds using a cooling gas at about -196°C, and a substrate separated from the top of the chamber by a gap of about 5 millimeters was cooled from about 220°C to about 209°C in about 5,000 milliseconds using the same cooling gas. Thus, it was discovered that the higher the flow rate and the smaller the gap, the faster the substrate cooled.

[0135] In some embodiments, the substrate cooling unit 728 can actively cool the substrate 734 using solid-to-solid heat transfer. In some of these embodiments, a cooling platen, such as a flat cooling surface, can be used to contact and cool the bottom of the substrate. This platen can be cooled by flowing a cooling fluid over, through, or under the platen. When using this solid-to-solid cooling, similar to the solid-to-solid heating described above, the substrate is separated from the cooling platen during heating, for example, by lifting the substrate away from the cooling platen with lift pins. Without this separation, more cooling is required to cool the thermal mass of both the substrate and the cooling platen, resulting in increased process time and reduced throughput. In some embodiments, radiative heating of the top of the substrate or plasma heating of the bottom of the substrate can be used in conjunction with solid-to-solid cooling.

[0136] In some embodiments, the substrate cooling unit 728 can use laser cooling to cool the substrate. This can enable cooling of a substrate containing thulium molecules on at least the exposed surface of the substrate by utilizing the inverse Navier-Stokes reaction. For example, the temperature of the substrate manifests itself as phonons, and laser cooling emits photons onto the substrate surface, which interact with and capture phonons in the thulium, leaving phonons from the thulium at a higher energy level in the substrate. Removal of these phonons reduces the temperature of the substrate. To enable this laser cooling, thulium can be doped onto the surface of the substrate, and this doping can be incorporated into the techniques listed above, such as after or before an operation, such as a removal operation.

[0137] As noted above, some embodiments of the apparatus can include a plasma source configured to generate a plasma within the chamber, which can be a capacitively coupled plasma (CCP), an inductively coupled plasma (ICP), a top remote plasma, or a bottom remote plasma.

[0138] In some embodiments, the apparatus described herein may include a controller configured to control various aspects of the apparatus to perform the techniques described herein. For example, in FIG. 7 , apparatus 720 includes a controller 766 (which may include one or more physical or logical controllers) communicatively coupled to the processing chamber and controlling some or all of the operation of the processing chamber. The system controller 766 may include one or more memory devices 768 and one or more processors 770. In some embodiments, the apparatus includes, for example, a switching system for controlling flow rates and durations, a substrate heating unit, a substrate cooling unit, loading and unloading of a substrate in the chamber, thermal levitation of the substrate, and a process gas unit when the disclosed embodiments are implemented. In some embodiments, the apparatus can have a switching time of up to about 500 ms, or up to about 750 ms. The switching time may depend on the flow chemistry, the selected recipe, the reactor configuration, and other factors.

[0139] In some embodiments, the controller 766 is part of an apparatus or system, such as may be part of the examples described above. Such a system or apparatus may include semiconductor processing equipment, including one or more processing tools, one or more chambers, one or more processing platforms, and / or specific processing components (e.g., gas flow systems, substrate heating units, substrate cooling units, etc.). These systems may be integrated with electronics for controlling system operation before, during, and after semiconductor wafer or substrate processing. Such electronics may be referred to as a "controller" and may control various components or subcomponents of one or more systems. The controller 766 may be programmed to control any of the processes disclosed herein, depending on the processing parameters and / or type of system. Such processes may include process 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 motion settings, wafer transfer to and from tools and other transfer tools connected or interfaced with a particular system, and / or wafer transfer to and from load locks.

[0140] Broadly, the controller 766 may be defined as electronic equipment having various integrated circuits, logic, memory, and / or software that receive instructions, issue instructions, control operations, enable cleaning operations, enable endpoint measurements, etc. The integrated circuits may include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application-specific integrated circuits (ASICs), and / or one or more microprocessors, i.e., microcontrollers, that execute program instructions (e.g., software). The program instructions may be instructions communicated to the controller in the form of various individual settings (or program files) that define operational parameters for performing a particular process on or for a semiconductor wafer or for a system. The operational parameters, in some embodiments, may be part of a recipe defined by a process engineer to implement one or more processing operations in the fabrication of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or wafer dies.

[0141] The controller 766, in some embodiments, may be part of, coupled to, or a combination of a computer integrated with, coupled to, or otherwise networked to the system. For example, the controller may be in the “cloud” or all or part of a fab host computer system. This allows for remote access to wafer processing. The computer may provide remote access to the system to monitor the current progress of a fabrication operation, review the history of past fabrication operations, review trends or performance criteria from multiple fabrication operations, modify parameters of a current process, configure processing operations following a current process, or initiate a new process. In some examples, a remote computer (e.g., a server) can provide process recipes to the system over a network. Such a network may include a local network or the Internet. The remote computer may include a user interface that allows entry or programming of parameters and / or settings, which are then communicated from the remote computer to the system. In some examples, the controller 766 receives instructions in the form of data. Such data identifies parameters for each processing operation performed during one or more operations. It should be understood that the parameters may be specific to the type of process being performed and the type of tool the controller is configured to interface with or control. Thus, as discussed above, the controller 766 may be distributed, for example, by comprising one or more individual controllers networked together and cooperating toward a common purpose (such as the processes and controls described herein). An example of a distributed controller for such purposes would include one or more integrated circuits on the chamber in communication with one or more integrated circuits located remotely (e.g., at the platform level or as part of a remote computer) and coupled to control the process in the chamber.

[0142] As noted above, depending on the one or more process operations being performed by the equipment, the controller 766 may communicate with one or more other equipment circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, nearby tools, tools located throughout the factory, a main computer, another controller, or tools used in material transport to and from tool locations and / or load ports in a semiconductor fabrication factory.

[0143] Also, as noted above, the controller is configured to implement any of the techniques described above. For example, referring to the apparatus 720 of FIG. 7 and the technique of FIG. 1, in some embodiments, the controller 766 is configured so that the substrate heating unit 726 brings (i.e., heats or actively cools) a substrate 734 positioned on the substrate support feature 735 to a first temperature and the process gas unit 724 flows a first process gas to the substrate 734. As noted above, the first process gas is configured to modify one or more surface layers of material on the substrate 734 by chemisorption while the substrate is maintained at the first temperature, in some embodiments without the use of a plasma. The controller 766 can be further configured so that the substrate heating unit 726 maintains the substrate 734 at a second temperature after modification, and the one or more modified surface layers on the substrate 734 can be removed by desorption while the substrate 734 is maintained at the second temperature. The controller 766 may further be configured to cause the process gas unit 724 to flow a third process gas onto the substrate to convert the exposed surface of the second material into a converted layer of material, i.e., an etch stop layer, as described herein.

[0144] 8A-8C illustrate one embodiment of an adjustable-gap capacitively coupled confinement RF plasma reactor 800 that can be used to perform the etching operations described herein. As shown, a vacuum chamber 802 includes a chamber housing 804 that encloses an interior space containing a lower electrode 806. At the top of the chamber 802, an upper electrode 808 is vertically spaced apart from a lower electrode 806. The planes of the upper and lower electrodes 808, 806 are substantially parallel to and perpendicular to the vertical direction between the electrodes. Preferably, the upper and lower electrodes 808, 806 are circular and coaxial with respect to the vertical axis. The lower surface of the upper electrode 808 faces the upper surface of the lower electrode 806. The spaced-apart facing electrode surfaces define an adjustable gap 810 therebetween. During operation, the lower electrode 806 is supplied with RF power by an RF power source (match) 820. RF power is supplied to the lower electrode 806 through an RF supply conduit 822, an RF strap 824, and an RF power member 826. A grounded shield 836 surrounds the RF power member 826 and can provide a more uniform RF field to the lower electrode 806. As described in commonly owned U.S. Pat. No. 7,732,728, the entire contents of which are incorporated herein by reference, a wafer is inserted through a wafer port 882 and supported in a gap 810 on the lower electrode 806 for processing, and a process gas is supplied to the gap 810 and excited into a plasma state by RF power. The upper electrode 808 may be energized or grounded.

[0145] 8A-8C, the lower electrode 806 is supported on a lower electrode support plate 816. An insulating ring 814 interposed between the lower electrode 806 and the lower electrode support plate 816 insulates the lower electrode 806 from the support plate 816.

[0146] An RF bias housing 830 supports the lower electrode 806 on an RF bias housing bowl 832. The bowl 832 is connected to a conduit support plate 838 by an arm 834 of the RF bias housing 830 through an opening in the chamber wall plate 818. In a preferred embodiment, the RF bias housing bowl 832 and the RF bias housing arm 834 are integrally formed as one component, although the arm 834 and the bowl 832 could also be two separate components that are bolted or joined together.

[0147] The RF bias housing arm 834 includes one or more hollow passages for passing RF power and equipment, such as gas coolant, liquid coolant, RF energy, cables for lift pin control, electrical monitoring and actuation signals, from outside the vacuum chamber 802 to inside the vacuum chamber 802 in the space behind the lower electrode 806. The RF supply conduit 822 is insulated from the RF bias housing arm 834, which provides a return path for RF power to the RF power supply 820. The equipment conduit 840 provides passage for the equipment components. Further details of the equipment components are described in U.S. Patent Nos. 5,948,704 and 7,732,728 and are not shown here for simplicity. The gap 810 is preferably surrounded by a confinement ring assembly or shroud (not shown), details of which can be found in commonly owned, published U.S. Patent No. 7,740,736, which is incorporated herein by reference. The interior of vacuum chamber 802 is maintained at low pressure by connection to a vacuum pump through vacuum portal 880 .

[0148] The conduit support plate 838 is attached to an actuation mechanism 842. The actuation mechanism 842, such as a servomechanical motor, stepper motor, or the like, is attached to a vertical linear bearing 844 by a screw gear 846, such as a ball screw, and a motor for rotating the ball screw. During operation to adjust the size of the gap 810, the actuation mechanism 842 moves along the vertical linear bearing 844. FIG. 8A shows the arrangement when the actuation mechanism 842 is in a high position on the linear bearing 844, resulting in a small gap 810a. FIG. 8B shows the arrangement when the actuation mechanism 842 is in an intermediate position on the linear bearing 844. As shown, the lower electrode 806, RF bias housing 830, conduit support plate 838, and RF power supply 820 all move downward relative to the chamber housing 804 and upper electrode 808, resulting in a medium-sized gap 810b.

[0149] 8C shows a large gap 810c when the actuation mechanism 842 is in a low position on the linear bearing. Preferably, the upper and lower electrodes 808, 806 remain coaxial during gap adjustment, and the opposing surfaces of the upper and lower electrodes across the gap remain parallel.

[0150] This embodiment allows for adjusting the gap 810 between the bottom and top electrodes 806, 808 in the CCP chamber 802 during multi-step process recipes (such as BARC, HARC, and STRIP) to maintain uniform etching across large diameter substrates, such as 300 mm wafers or flat panel displays. In particular, the chamber involves a mechanical arrangement that enables the linear motion necessary to provide an adjustable gap between the bottom and top electrodes 806, 808.

[0151] 8A shows a laterally biased bellows 850 sealed at its proximal end to a conduit support plate 838 and at its distal end to a stepped flange 828 of a chamber wall plate 818. The inner diameter of the stepped flange defines an opening 612 in the chamber wall plate 818 through which an RF bias housing arm 834 passes. The distal end of the bellows 850 is clamped by a clamp ring 652.

[0152] Laterally deflected bellows 850 provides a vacuum seal while allowing vertical movement of RF bias housing 830, conduit support plate 838, and actuation mechanism 842. RF bias housing 830, conduit support plate 838, and actuation mechanism 842 can be referred to as a cantilever assembly. Preferably, RF power supply 820 moves with the cantilever assembly and can be attached to conduit support plate 838. FIG. 8B shows bellows 850 in a neutral position when the cantilever assembly is in the intermediate position. FIG. 8C shows laterally deflected bellows 850 when the cantilever assembly is in the low position.

[0153] A labyrinth seal 848 provides a particle barrier between the bellows 850 and the interior of the plasma processing chamber housing 804. A fixed shield 856 is rigidly attached to the inner wall of the chamber housing 804 by the chamber wall plate 818 such that a movable shield plate 858 provides a labyrinth groove 860 (slot) that moves vertically to accommodate vertical movement of the cantilever assembly. The outer portion of the movable shield plate 858 remains within the slot at all vertical positions of the lower electrode 606.

[0154] In the illustrated embodiment, the labyrinth seal 848 includes a fixed shield 856 attached to the inner surface of the chamber wall plate 818 around an opening 812 in the chamber wall plate 818 that defines a labyrinth groove 860. A movable shield plate 858 is attached and extends radially from the RF bias housing arm 834, which passes through the opening 812 in the chamber wall plate 818. The movable shield plate 858 extends into the labyrinth groove 860 and is spaced from the fixed shield 856 by a first gap and from the inner surface of the chamber wall plate 818 by a second gap, allowing the cantilever assembly to move vertically. The labyrinth seal 848 blocks particles shed from the bellows 850 from migrating into the vacuum chamber interior 805 and blocks radicals from the process gas plasma from migrating into the bellows 850. The radicals that enter the bellows 850 can form deposits that can then be shed.

[0155] 8A shows the movable shield plate 858 in a higher position within the labyrinth groove 860 above the RF bias housing arm 834 when the cantilever assembly is in a high position (small gap 810a). FIG. 8C shows the movable shield plate 858 in a lower position within the labyrinth groove 860 above the RF bias housing arm 834 when the cantilever assembly is in a low position (large gap 810c). FIG. 8B shows the movable shield plate 858 in a neutral or intermediate position within the labyrinth groove 860 when the cantilever assembly is in an intermediate position (medium gap 810b). Although the labyrinth seal 848 is shown as symmetrical with respect to the RF bias housing arm 834, in other embodiments, the labyrinth seal 848 may be asymmetric with respect to the RF bias arm 834.

[0156] FIG. 9 illustrates a semiconductor process cluster architecture with various modules interfacing with a vacuum transfer module 938 (VTM). The arrangement of transfer modules for "transferring" substrates between multiple storage facilities and processing modules is sometimes referred to as a "cluster tool architecture" system. An airlock 930, also known as a loadlock or transfer module, is shown in the VTM 938 with four processing modules 920a-920d, which can be individually optimized to perform various fabrication processes. By way of example, processing modules 920a-920d can be implemented to perform substrate etching, deposition, ion implantation, substrate cleaning, sputtering, and / or other semiconductor processes, as well as laser metrology and other defect detection and defect identification methods. One or more of the processing modules (any of 920a-920d) can be implemented as disclosed herein, i.e., to etch recessed features into substrates. The airlock 930 and process modules 920a-920d are sometimes referred to as "stations." Each station has a facet 936 that interfaces the station to the VTM 938. Inside the facets, sensors 1-18 are used to detect the passage of substrate 926 as it moves between the respective stations.

[0157] A robot 922 transfers substrates between stations. In one embodiment, the robot can have one arm, and in another embodiment, the robot can have two arms, each arm having an end effector 924 for picking up substrates for transfer. A front-end robot 932 in an atmospheric transfer module (ATM) 940 can be used to transfer substrates from cassettes or front-opening unified pods (FOUPs) 934 in a load port module (LPM) 942 to the airlock 930. A module center 928 in the process modules 920a-920d is one location for depositing substrates. An aligner 944 in the ATM 940 can be used to align the substrates.

[0158] In an exemplary processing method, a substrate is placed into one of the FOUPs 934 within the LPM 942. The front-end robot 932 transfers the substrate from the FOUP 934 to the aligner 944, which allows the substrate 926 to be properly centered before being etched, deposited, or otherwise processed. After alignment, the substrate is moved into the airlock 930 by the front-end robot 932. Because the airlock module has the ability to match the environment between the ATM and the VTM, the substrate can be moved between the two pressure environments without being damaged. From the airlock module 930, the substrate is moved by the robot 922 through the VTM 938 to one of the process modules 920a-920d, e.g., process module 920a. To accomplish this substrate movement, the robot 922 uses end effectors 924 on each of its arms. In process module 920a, the substrate undergoes etching as described above. The robot 922 then moves the substrate from the processing module 920a to its next desired location.

[0159] It should be noted that the computer controlling the movement of the substrates may be local to the cluster architecture, or may be located external to the cluster architecture or at a remote location within the manufacturing floor and connected to the cluster architecture via a network.

[0160] Deposition Equipment 10 schematically illustrates one embodiment of a process station 1000 that can be used to deposit materials using atomic layer deposition (ALD) and / or chemical vapor deposition (CVD), either of which may be plasma-enhanced. For simplicity, the process station 1000 is illustrated as a stand-alone process station having a process chamber body 1002 for maintaining a low-pressure environment. However, it will be understood that multiple process stations 1000 may be included in a common process tool environment. Furthermore, it will be understood that in some embodiments, one or more hardware parameters of the process station 1000 (including those described in detail below) may be programmably adjusted by one or more computer controllers.

[0161] The process station 1000 is in fluid communication with a reactant delivery system 1001 for delivering process gases to a distribution showerhead 1006. The reactant delivery system 1001 includes a mixing vessel 1004 for blending and / or conditioning the process gases delivered to the showerhead 1006. One or more mixing vessel inlet valves 1020 can control the introduction of process gases into the mixing vessel 1004. Similarly, a showerhead inlet valve 1005 can control the introduction of process gases to the showerhead 1006.

[0162] Some reactants, such as BTBAS, may be stored in liquid form before vaporization at the process station and subsequent delivery to the process station. For example, the embodiment of FIG. 10 includes a vaporization point 1003 for vaporizing the liquid reactant delivered to a mixing vessel 1004. In some embodiments, the vaporization point 1003 may be a heated vaporizer. The reactant vapor generated from such a vaporizer may condense in downstream delivery piping. Exposure of incompatible gases to the condensed reactant may generate small particles. These small particles may clog the piping, interfere with valve operation, or contaminate the substrate. Some approaches to addressing these issues involve cleaning and / or evacuating the delivery piping to remove residual reactant. However, cleaning the delivery piping may increase the process station cycle time and reduce process station throughput. Therefore, in some embodiments, the delivery piping downstream of the vaporization point 1003 may be heat traced. In some examples, the mixing vessel 1004 may also be heat traced. In one non-limiting example, the piping downstream of vaporization point 1003 has an elevated temperature profile ranging from about 100° C. to about 150° C. at mixing vessel 1004.

[0163] In some embodiments, the reactant liquid can be vaporized in a liquid injector. For example, the liquid injector can inject pulses of liquid reactant into a carrier gas stream upstream of the mixing vessel. In one scenario, the liquid injector can vaporize the reactant by flashing the liquid from high pressure to low pressure. In another scenario, the liquid injector can atomize the liquid into dispersed microdroplets, which are subsequently vaporized in a heated delivery pipe. It will be appreciated that small droplets can vaporize faster than large droplets, reducing the delay between liquid injection and full vaporization. The faster the vaporization, the shorter the length of piping downstream from the vaporization point 1003 can be. In one scenario, the liquid injector can be attached directly to the mixing vessel 1004. In another scenario, the liquid injector can be attached directly to the showerhead 1006.

[0164] In some embodiments, a liquid flow controller can be provided upstream of the vaporization point 1003 to control the mass flow rate of the liquid vaporized and delivered to the process station 1000. For example, the liquid flow controller (LFC) can include a thermal mass flow meter (MFM) located downstream of the LFC. The plunger valve of the LFC can then be adjusted in response to a feedback control signal provided by a proportional-integral-derivative (PID) controller in electronic communication with the MFM. However, stabilizing the liquid flow using feedback control can take one second or more, which can extend the dosing time of the liquid reactant. Therefore, in some embodiments, the LFC can be dynamically switched between a feedback control mode and a direct control mode. In some embodiments, the LFC can be dynamically switched from the feedback control mode to the direct control mode by disabling the sensing tube and PID controller of the LFC.

[0165] The showerhead 1006 distributes process gases toward the substrate 1012. In the embodiment shown in Figure 10, the substrate 1012 is shown positioned below the showerhead 1006 and resting on a pedestal 1008. It will be understood that the showerhead 1006 may have any suitable shape and any suitable number and arrangement of ports for distributing process gases to the substrate 1012.

[0166] In some embodiments, a micro-volume 1007 is located below the showerhead 1006. Performing ALD and / or CVD processes in a micro-volume rather than the full volume of the process station can reduce reactant exposure and clean-up time, reduce the time to change process conditions (e.g., pressure, temperature, etc.), limit exposure of the process station robot to process gases, and the like. Exemplary micro-volume sizes include, but are not limited to, volumes between 0.1 liters and 2 liters. This micro-volume also impacts productivity throughput. While the deposition rate per cycle is reduced, cycle time is simultaneously reduced. In some cases, the latter effect is effective enough to improve the overall throughput of the module for a given target film thickness.

[0167] In some embodiments, the pedestal 1008 can be raised or lowered to expose the substrate 1012 to the micro-volume 1007 and / or to change the volume of the micro-volume 1007. For example, during a substrate transfer phase, the pedestal 1008 can be lowered to allow the substrate 1012 to be loaded onto the pedestal 1008. During a deposition process phase, the pedestal 1008 can be raised to position the substrate 1012 within the micro-volume 1007. In some embodiments, the micro-volume 1007 can completely surround the substrate 1012 as well as a portion of the pedestal 1008, creating a region of high flow impedance during the deposition process.

[0168] Optionally, the pedestal 1008 may be lowered and / or raised during portions of the deposition process to adjust the process pressure, reactant concentration, etc. within the micro-volume 1007. In one scenario in which the process chamber body 1002 remains at base pressure during the deposition process, the micro-volume 1007 can be evacuated by lowering the pedestal 1008. Exemplary ratios of micro-volume to process chamber volume include, but are not limited to, volume ratios of 1:900 to 1:10. It will be appreciated that in some embodiments, the height of the pedestal can be programmatically adjusted by a suitable computer controller.

[0169] In another scenario, adjusting the height of the pedestal 1008 may allow for varying the plasma density during plasma activation and / or plasma treatment cycles involved in the deposition process. At the end of the deposition process stage, the pedestal 1008 may be lowered to allow removal of the substrate 1012 from the pedestal 1008 during another substrate transfer stage.

[0170] While the exemplary micro-volume variations described herein refer to a height-adjustable pedestal, it will be understood that in some embodiments, the position of the showerhead 1006 can be adjusted relative to the pedestal 1008 to vary the volume of the micro-volume 1007. Furthermore, it will be understood that the vertical position of the pedestal 1008 and / or the showerhead 1006 may be varied by any suitable mechanism within the scope of the present disclosure. In some embodiments, the pedestal 1008 may include a rotation axis for rotating the orientation of the substrate 1012. It will be understood that in some embodiments, one or more of these exemplary adjustments may be implemented programmatically by one or more suitable computer controllers.

[0171] Returning to the embodiment shown in FIG. 10 , the showerhead 1006 and pedestal 1008 are in electrical communication with an RF power source 1014 and matching network 1016 to power the plasma. In some embodiments, the plasma energy can be controlled by controlling one or more of the process station pressure, gas concentration, RF source power, RF source frequency, and plasma power pulse timing. For example, the RF power source 1014 and matching network 1016 can operate at any suitable power to form a plasma having a desired composition of radical species. Examples of suitable powers are included above. Similarly, the RF power source 1014 can provide RF power at any suitable frequency. In some embodiments, the RF power source 1014 can be configured to control high-frequency and low-frequency RF power sources independently of each other. Exemplary low-frequency RF frequencies can include, but are not limited to, frequencies between 50 kHz and 500 kHz. Exemplary high-frequency RF frequencies can include, but are not limited to, frequencies between 1.8 MHz and 2.45 GHz. It will be appreciated that any suitable parameters can be adjusted, either discretely or continuously, to provide plasma energy for surface reactions. In one non-limiting example, the plasma power can be pulsed intermittently to reduce ion bombardment at the substrate surface compared to a continuously powered plasma.

[0172] In some embodiments, the plasma can be monitored in situ by one or more plasma monitors. In one scenario, plasma power can be monitored by one or more voltage and current sensors (e.g., VI probes). In another scenario, plasma density and / or process gas concentrations can be measured by one or more optical emission spectroscopy (OES) sensors. In some embodiments, one or more plasma parameters can be programmatically adjusted based on measurements from such in situ plasma monitors. For example, OES sensors can be used in a feedback loop to provide programmatic control of plasma power. It will be appreciated that in some embodiments, other monitors can be used to monitor the plasma and other process characteristics. Such monitors can include, but are not limited to, infrared (IR) monitors, acoustic monitors, and pressure transducers.

[0173] In some embodiments, the plasma may be controlled via input / output control (IOC) sequence instructions. In one example, instructions for setting plasma conditions for a plasma process step may be included in the corresponding plasma activation recipe step of a deposition process recipe. In some cases, process recipe steps may be arranged in a sequence such that all instructions for a deposition process step are executed simultaneously with that process step. In some embodiments, instructions for setting one or more plasma parameters may be included in a recipe step preceding a plasma process step. For example, a first recipe step may include instructions for setting the flow rate of an inert gas and / or precursor gas, instructions for setting a plasma generator to a power setpoint, and a time delay instruction for the first recipe step. A second, subsequent recipe step may include instructions for enabling the plasma generator and a time delay instruction for the second recipe step. A third recipe step may include instructions for disabling the plasma generator and a time delay instruction for the third recipe step. It will be understood that these recipe steps may be further subdivided and / or repeated in any suitable manner within the scope of the present disclosure.

[0174] In some deposition processes, plasma strikes last several seconds or longer. In certain implementations, much shorter strikes may be used. These may be on the order of 10 ms to 1 second, typically about 20 to 80 ms, with 50 ms being a specific example. Such very short RF strikes require very rapid stabilization of the plasma. To achieve this, the plasma generator may be configured so that the impedance match is preset to a specific voltage while allowing the frequency to vary. Traditionally, RF plasmas are generated at an RF frequency of about 13.56 MHz. In various embodiments disclosed herein, the frequency is allowed to vary to values ​​different from this standard value. By allowing the frequency to vary while fixing the impedance match at a predetermined voltage, the plasma can stabilize much more quickly, which may be important when using the very short strikes associated with certain deposition cycles.

[0175] In some embodiments, the pedestal 1008 may be temperature controlled via a heater 1010. Additionally, in some embodiments, pressure control for the deposition process station 1000 may be provided by a butterfly valve 1018. As shown in the embodiment of FIG. 10, the butterfly valve 1018 throttles the vacuum provided by a downstream vacuum pump (not shown). However, in some embodiments, pressure control for the process station 1000 may also be adjusted by varying the flow rate of one or more gases introduced into the process station 1000.

[0176] FIG. 11 shows a schematic diagram of one embodiment of a multi-station processing tool 1100 including an inbound load lock 1102 and an outbound load lock 1104, either or both of which may include a remote plasma source. A robot 1106 is configured to move wafers at atmospheric pressure from a cassette loaded via a pod 1108 to the inbound load lock 1102 through an atmospheric pressure port 1110. The wafer is placed by the robot 1106 on a pedestal 1112 of the inbound load lock 1102, the atmospheric pressure port 1110 is closed, and the load lock is pumped down. If the inbound load lock 1102 includes a remote plasma source, the wafer may undergo remote plasma processing within the load lock before being introduced into the processing chamber 1114. Additionally, the wafer may also be heated in the inbound load lock 1102 to remove moisture and absorbed gases, for example. The chamber transfer port 1116 to the processing chamber 1114 is then opened and another robot (not shown) moves the wafer into the reactor and places it on a pedestal in the first station shown in the reactor for processing. While the embodiment shown in Figure 11 includes a load lock, it will be understood that in some embodiments the wafer may enter the process station directly.

[0177] The illustrated processing chamber 1114 includes four process stations, numbered 1 through 4 in the embodiment shown in FIG. 11 . Each station includes a heated pedestal (shown at 1118 for station 1) and a gas line inlet. It will be understood that in some embodiments, each process station may have a different purpose or multiple purposes. While the illustrated processing chamber 1114 includes four stations, it will be understood that a processing chamber according to the present disclosure may have any suitable number of stations. For example, in some embodiments, a processing chamber may have five or more stations, while in other embodiments, a processing chamber may have three or fewer stations.

[0178] FIG. 11 also illustrates one embodiment of a wafer handling system 1190 for transferring wafers within the processing chamber 1114. In some embodiments, the wafer handling system 1190 can transfer wafers between various process stations and / or between process stations and load locks. It will be understood that any suitable wafer handling system may be used. Non-limiting examples include a wafer carousel and a wafer handling robot. FIG. 11 also illustrates one embodiment of a system controller 1150 used to control the process conditions and hardware states of the process tool 1100. The system controller 1150 may include one or more memory devices 1156, one or more mass storage devices 1154, and one or more processors 1152. The processor 1152 may include a CPU or computer, analog and / or digital input / output connections, stepper motor controller boards, etc.

[0179] FIG. 12 is a block diagram of a processing system suitable for performing a thin film deposition process according to certain embodiments. System 1200 includes a transfer module 1203. Transfer module 1203 provides a clean, pressurized environment to minimize the risk of substrate contamination during processing as the substrate moves between various reactor modules. Attached to transfer module 1203 are two multi-station reactors 1209 and 1210, each capable of performing atomic layer deposition (ALD) and / or chemical vapor deposition (CVD) according to certain embodiments. Reactors 1209 and 1210 can include multiple stations 1211, 1213, 1215, and 1217 that can perform operations sequentially or non-sequentially according to disclosed embodiments. The stations may include a heated pedestal or substrate support, one or more gas inlets, or a showerhead or distribution plate.

[0180] The transfer module 1203 may be fitted with one or more single- or multi-station modules 1207 capable of performing plasma or chemical (non-plasma) pre-cleaning or any other process described in connection with the disclosed methods. Module 1207 may optionally be used for various processes, such as preparing substrates for deposition processes. Module 1207 may also be designed / configured to perform various other processes, such as etching or polishing. The system 1200 also includes one or more wafer source modules 1201 that store unprocessed and processed wafers. An atmospheric robot (not shown) in the atmospheric transfer chamber 1219 can initially remove wafers from the source modules 1201 and transfer them to the load lock 1221. A wafer transfer device (typically a robot arm unit) in the transfer module 1203 moves wafers from the load lock 1221 to modules attached to the transfer module 1203 and between modules.

[0181] In various embodiments, a system controller 1229 is used to control process conditions during deposition as described herein.

[0182] It will be appreciated that multiple process stations may be included in a multi-station processing tool environment, as shown in FIG. 13 , which illustrates a schematic diagram of one embodiment of a multi-station processing tool. The processing apparatus 1300 employs an integrated circuit fabrication chamber 1363 that includes multiple fabrication process stations, each of which may be used to perform a processing operation on a substrate held in a wafer holder, such as a pedestal, at a particular process station. In the embodiment of FIG. 13 , an integrated circuit fabrication chamber 1363 is shown having four process stations 1351, 1352, 1353, and 1354. Other similar multi-station processing apparatuses may have a greater or lesser number of process stations depending on the implementation and, for example, the desired level of parallel wafer processing, size / space constraints, cost constraints, etc. Also shown in Figure 13 is a substrate handler robot 1375 that can operate under the control of the system controller 1390 and is configured to move substrates from a wafer cassette (not shown in Figure 13) and from the loading port 1380 to the integrated circuit fabrication chamber 1363 and to one of the process stations 1351, 1352, 1353, and 1354.

[0183] 13 also illustrates one embodiment of a system controller 1390 used to control the process conditions and hardware states of the processing device 1300. The system controller 1390 may include one or more memory devices, one or more mass storage devices, and one or more processors, as described herein.

[0184] The RF subsystem 1395 can generate and transmit RF power to the integrated circuit fabrication chamber 1363 via the radio frequency input port 1367. In certain embodiments, the integrated circuit fabrication chamber 1363 can include input ports in addition to the radio frequency input port 1367 (the additional input ports are not shown in FIG. 13 ). Thus, the integrated circuit fabrication chamber 1363 can utilize eight RF input ports. In certain embodiments, the process stations 1351-1354 of the integrated circuit fabrication chamber 165 can each utilize a first and second input port, where the first input port can transmit a signal having a first frequency and the second input port can transmit a signal having a second frequency. The use of dual frequencies can result in improved plasma characteristics.

[0185] As described above, one or more process stations may be included in a multi-station processing tool. FIG. 14 shows a schematic diagram of one embodiment of a multi-station processing tool 1400 including an inbound load lock 1402 and an outbound load lock 1404, either or both of which may include a remote plasma source. A robot 1406 is configured to transfer a substrate or wafer at atmospheric pressure from a cassette loaded via a pod 1408 to the inbound load lock 1402 through an atmospheric pressure port 1410. The substrate is placed by the robot 1406 on a pedestal 1412 of the inbound load lock 1402, the atmospheric pressure port 1410 is closed, and the load lock is pumped down. If the inbound load lock 1402 includes a remote plasma source, the substrate may undergo remote plasma processing within the load lock before being introduced into the processing chamber 1414. Additionally, the substrate may also be heated in the inbound load lock 1402, for example, to remove moisture and absorbed gases. The chamber transfer port 1416 to the processing chamber 1414 is then opened, and another robot (not shown) moves the substrate into the reactor and places it on the pedestal of the first station shown in the reactor for processing. While the embodiment illustrated in Figure 14 includes a load lock, it will be understood that in some embodiments, the substrate may enter the process station directly. In various embodiments, an immersion gas is introduced into the station as the substrate is placed on the pedestal 1412 by the robot 1406.

[0186] The illustrated processing chamber 1414 includes four process stations, numbered 1 through 4 in the embodiment shown in FIG. 14 . Each station has a heated pedestal (shown at 1418 for station 1) and a gas line inlet. It will be understood that in some embodiments, each process station may have a different purpose or multiple purposes. For example, in some embodiments, a process station may be switchable between an ALD process mode and a PEALD process mode. Additionally or alternatively, in some embodiments, the processing chamber 1414 may include one or more matched pairs of an ALD process station and a plasma-enhanced ALD process station. While the illustrated processing chamber 1414 includes four stations, it will be understood that a processing chamber according to the present disclosure may have any suitable number of stations. For example, in some embodiments, the processing chamber may have five or more stations, while in other embodiments, the processing chamber may have three or fewer stations.

[0187] FIG. 14 illustrates one embodiment of a wafer handling system 1490 for transferring substrates within the processing chamber 1414. In some embodiments, the wafer handling system 1490 can transfer substrates between various process stations and / or between process stations and load locks. It will be understood that any suitable wafer handling system may be used. Non-limiting examples include a wafer carousel and a wafer handling robot. FIG. 14 also illustrates one embodiment of a system controller 1450 used to control the process conditions and hardware states of the process tool 1400. The system controller 1450 can include one or more memory devices 1456, one or more mass storage devices 1454, and one or more processors 1452. The processor 1452 can include a CPU or computer, analog and / or digital input / output connections, stepper motor controller boards, etc. In some embodiments, the system controller 1450 includes machine-readable instructions for performing operations as described herein.

[0188] In some embodiments, the system controller 1450 controls the activities of the process tool 1400. The system controller 1450 executes system control software 1458 stored on the mass storage device 1454, loaded into the memory device 1456, and executed by the processor 1452. Alternatively, the control logic may be hard-coded into the system controller 1450. Application-specific integrated circuits, programmable logic devices (e.g., field-programmable gate arrays, or FPGAs), or the like may be used for these purposes. In the following description, whenever "software" or "code" is used, functionally equivalent hard-coded logic may be used instead. The system control software 1458 may include instructions for controlling the timing, mixture of gases, gas flow rates, chamber and / or station pressures, chamber and / or station temperatures, substrate temperatures, target power levels, RF power levels, substrate pedestal, chuck and / or susceptor positions, and other parameters of a particular process performed by the process tool 1400. The system control software 1458 may be configured in any suitable manner. For example, various process tool component subroutines or control objects may be written to control the operation of the process tool components used to perform the various process tool processes. The system control software 1458 may be coded in any suitable computer-readable programming language.

[0189] While the subject matter disclosed herein has been particularly described with reference to illustrated embodiments, it will be understood that various changes, modifications, and adaptations can be made based on this disclosure and are intended to be within the scope of the invention. It is understood that the description is not limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the scope of the claims. The present disclosure can also be realized in the following forms. [Form 1] 1. A method comprising: providing a substrate in a processing chamber, the substrate having a first material adjacent to and overlying a surface of a second material; modifying the layer of first material by flowing a first process gas over the substrate, thereby forming a modified layer of the first material; removing the modified layer of the first material by flowing a second process gas over the substrate; Once the surface of the second material is released via removal of the modified layer, converting the surface to a converted layer of the second material by flowing a third process gas over the substrate, wherein the first process gas and the second process gas are less reactive with the converted layer than the first material and the second material. A method comprising: [Form 2] 2. The method of claim 1, after the conversion, modifying the converted layer into a modified converted layer of material by flowing a fourth process gas over the substrate; removing the modified conversion layer by flowing a fifth process gas onto the substrate; The method further comprises: [Form 3] 2. The method of claim 1, The method, wherein flowing the third process gas occurs before the reforming. [Form 4] 2. The method of claim 1, The method, wherein flowing the third process gas occurs after the reforming. [Form 5] 5. The method of claim 4, The method, wherein the flowing of the third process gas occurs before the removing. [Form 6] 6. The method of claim 5, The method further comprising flowing a purge gas after flowing the third process gas and before said removing. [Form 7] 5. The method of claim 4, The method wherein the flowing of the third process gas occurs after the removing. [Form 8] 2. The method of claim 1, The method, wherein flowing the third process gas over the substrate at least partially overlaps with flowing the first process gas over the substrate. [Form 9] 2. The method of claim 1, The method, wherein flowing the third process gas over the substrate at least partially overlaps with flowing the second process gas over the substrate. [Form 10] 2. The method of claim 1, The method, wherein flowing the third process gas over the substrate at least partially overlaps with flowing the first process gas over the substrate and flowing the second process gas over the substrate. [Form 11] 2. The method of claim 1, The method wherein said transformation occurs when said surface of said second material is released during or after said removal of said first material. [Form 12] 2. The method of claim 1, During the removing, the second process gas removes the modified layer of the first material at a first etch rate; During the removing, the second process gas removes the conversion layer at a second etch rate that is less than or equal to about 50% of the first etch rate. method. [Form 13] 13. The method of claim 12, further comprising: The method, wherein the second etch rate is less than or equal to about 15% of the first etch rate. [Form 14] 13. The method of claim 12, further comprising: During the removing, the second process gas is capable of removing the second material at a third etch rate that is greater than the first etch rate. [Form 15] 2. The method of claim 1, the first process gas includes modifying molecules; the second process gas includes removal molecules; the third process gas comprises a conversion molecule; method. [Form 16] 2. The method of claim 1, The method wherein the third process gas comprises a precursor. [Form 17] 2. The method of claim 1, The method wherein the conversion layer is a monolayer of the second material. [Form 18] 2. The method of claim 1, The method, wherein the first material and the second material are oxides. [Form 19] 2. The method of claim 1, The method, wherein the first material and / or the second material is a semiconductor oxide. [Form 20] 2. The method of claim 1, The method wherein the conversion layer is inert to the second process gas. [Form 21] 2. The method of claim 1, The method, wherein the reaction between the conversion layer and the second process gas does not produce by-products. [Form 22] 2. The method of claim 1, repeating said modifying and said removing to remove an amount of said first material prior to said converting. The method further comprises: [Form 23] 2. The method of claim 1, the first material includes aluminum oxide; the second material comprises zinc oxide; the first process gas comprises hydrogen fluoride; the second process gas comprises trimethylaluminum; the third process gas comprises zirconium tetrachloride; the conversion layer comprises zirconium oxide; method. [Form 24] 2. The method of claim 1, removing the conversion layer by flowing a fourth process gas over the substrate, the fourth process gas comprising dimethylaluminum chloride; The method further comprises: [Form 25] 2. The method of claim 1, The method, wherein the conversion comprises a cation exchange between an element in the third process gas and the second material. [Form 26] 2. The method of claim 1, A method wherein said modifying and said removing are performed while said substrate is maintained at the same or substantially the same temperature. [Form 27] 2. The method of claim 1, the modification is performed while the substrate is maintained at a first temperature; the removing occurs while the substrate is maintained at a second temperature different from the first temperature. method. [Form 28] 2. The method of claim 1, The method wherein water vapor is not supplied to the substrate during the conversion. [Form 29] 1. A method comprising: providing a substrate in a processing chamber, the substrate having a first material adjacent to and overlying a surface of a second material; modifying the layer of first material by flowing a first process gas over the substrate, thereby forming a modified layer of the first material; removing the modified layer of the first material by flowing a second process gas over the substrate; selectively converting the surface of the second material into a layer of etch stop material once the surface of the second material is released through removal of the modified layer, the layer of etch stop material being positioned only on the second material such that during the removal, the modified layer of the first material and the layer of etch stop material are exposed to the second process gas, the second process gas being less reactive with the layer of etch stop material than with the modified layer of the first material and the second material; A method comprising: [Form 30] 1. An apparatus for semiconductor processing, comprising: a processing chamber including an interior and a substrate support configured to support a substrate within the interior; a process gas unit configured to flow a first process gas comprising modifying molecules over the substrate in the processing chamber, a second process gas comprising removing molecules over the substrate in the processing chamber, and a third process gas comprising converting molecules over the substrate in the processing chamber; flowing the first process gas onto the substrate, thereby forming a modified layer of a first material on the substrate, the substrate having the first material adjacent to and overlying a surface of a second material; flowing the second process gas over the substrate, thereby removing the modified layer of the first material; The third process gas is flowed over the substrate, and upon release of the surface of the second material, converts the surface to a conversion layer of the second material, the first process gas and the second process gas being less reactive with the conversion layer than the first material and the second material. a controller having instructions configured to An apparatus comprising:

Claims

1. 1. A method comprising: providing a substrate in a processing chamber, the substrate having a first material adjacent to and overlying a surface of a second material; modifying the layer of first material by flowing a first process gas over the substrate, thereby forming a modified layer of the first material; removing the modified layer of the first material by flowing a second process gas over the substrate; Once the surface of the second material is released via removal of the modified layer, converting the surface into a converted layer of the second material by flowing a third process gas over the substrate, wherein the first process gas and the second process gas are less reactive with the converted layer than the first material and the second material. A method comprising:

2. 10. The method of claim 1, after the conversion, modifying the converted layer into a modified converted layer of material by flowing a fourth process gas over the substrate; removing the modified conversion layer by flowing a fifth process gas over the substrate; The method further comprises:

3. 10. The method of claim 1, The method, wherein flowing the third process gas occurs before the reforming.

4. 10. The method of claim 1, The method, wherein flowing the third process gas occurs after the reforming.

5. 5. The method of claim 4, The method, wherein the flowing of the third process gas occurs before the removing.

6. 6. The method of claim 5, The method further comprising flowing a purge gas after flowing the third process gas and before said removing.

7. 5. The method of claim 4, The method, wherein the flowing of the third process gas occurs after the removing.

8. 10. The method of claim 1, The method, wherein flowing the third process gas over the substrate at least partially overlaps with flowing the first process gas over the substrate.

9. 10. The method of claim 1, The method, wherein flowing the third process gas over the substrate at least partially overlaps with flowing the second process gas over the substrate.

10. 10. The method of claim 1, The method, wherein flowing the third process gas over the substrate at least partially overlaps with flowing the first process gas over the substrate and flowing the second process gas over the substrate.

11. 10. The method of claim 1, The method wherein said transformation occurs when said surface of said second material is released during or after said removal of said first material.

12. 10. The method of claim 1, During the removing, the second process gas removes the modified layer of the first material at a first etch rate; During the removing, the second process gas removes the conversion layer at a second etch rate that is less than or equal to about 50% of the first etch rate. method.

13. 13. The method of claim 12, The method, wherein the second etch rate is less than or equal to about 15% of the first etch rate.

14. 13. The method of claim 12, During the removing, the second process gas is capable of removing the second material at a third etch rate that is greater than the first etch rate.

15. 10. The method of claim 1, the first process gas comprises a modifying molecule; the second process gas includes removal molecules; the third process gas includes a conversion molecule; method.

16. 10. The method of claim 1, The method wherein the third process gas comprises a precursor.

17. 10. The method of claim 1, The method wherein the conversion layer is a monolayer of the second material.

18. 10. The method of claim 1, The method, wherein the first material and the second material are oxides.

19. 10. The method of claim 1, The method, wherein the first material and / or the second material is a semiconductor oxide.

20. 10. The method of claim 1, The method wherein the conversion layer is inert to the second process gas.

21. 10. The method of claim 1, The method, wherein the reaction between the conversion layer and the second process gas does not produce by-products.

22. 10. The method of claim 1, repeating said modifying and said removing to remove an amount of said first material prior to said converting. The method further comprises:

23. 10. The method of claim 1, the first material includes aluminum oxide; the second material comprises zinc oxide; the first process gas comprises hydrogen fluoride; the second process gas comprises trimethylaluminum; the third process gas comprises zirconium tetrachloride; the conversion layer comprises zirconium oxide; method.

24. 10. The method of claim 1, removing the conversion layer by flowing a fourth process gas over the substrate, the fourth process gas comprising dimethylaluminum chloride; The method further comprises:

25. 10. The method of claim 1, The method wherein the conversion comprises a cation exchange between an element in the third process gas and the second material.

26. 10. The method of claim 1, A method wherein said modifying and said removing are performed while said substrate is maintained at the same or substantially the same temperature.

27. 10. The method of claim 1, the modification is performed while the substrate is maintained at a first temperature; the removing occurs while the substrate is maintained at a second temperature different from the first temperature. method.

28. 10. The method of claim 1, The method wherein water vapor is not supplied to the substrate during the conversion.

29. 1. A method comprising: providing a substrate in a processing chamber, the substrate having a first material adjacent to and overlying a surface of a second material; modifying the layer of the first material by flowing a first process gas over the substrate, thereby forming a modified layer of the first material; removing the modified layer of the first material by flowing a second process gas over the substrate; selectively converting the surface of the second material into a layer of etch stop material once the surface of the second material is released through removal of the modified layer, the layer of etch stop material being positioned only on the second material such that during the removal, the modified layer of the first material and the layer of etch stop material are exposed to the second process gas, the second process gas being less reactive with the layer of etch stop material than with the modified layer of the first material and the second material; A method comprising:

30. 1. An apparatus for semiconductor processing, comprising: a processing chamber including an interior and a substrate support configured to support a substrate within the interior; a process gas unit configured to flow a first process gas comprising modifying molecules over the substrate in the processing chamber, a second process gas comprising removing molecules over the substrate in the processing chamber, and a third process gas comprising converting molecules over the substrate in the processing chamber; flowing the first process gas onto the substrate, thereby forming a modified layer of a first material on the substrate, the substrate having the first material adjacent to and overlying a surface of a second material; flowing the second process gas over the substrate, thereby removing the modified layer of the first material; The third process gas is flowed over the substrate, and upon release of the surface of the second material, converts the surface to a conversion layer of the second material, the first process gas and the second process gas being less reactive with the conversion layer than the first material and the second material. a controller having instructions configured to An apparatus comprising:

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