Systems and methods for improving planarization using selective atomic layer etching (ALE)

Abstract

To provide a planarization method for a patterned substrate in a spatial atomic layer processing system having a rotating platen.SOLUTION: Typically, a patterned substrate may have features with high and low regions. In order to flatten the patterned substrate or to reduce a height difference between the high and low regions, a selective atomic layer etching (ALE) process is disclosed. By exposing a surface of the patterned substrate to a precursor gas, a modified layer is preferentially formed on the high region of the feature while a rotating platen rotates at a high rotational speed. In the selective ALE process described in this application, the high regions of the feature are preferentially etched until the desired planarization of the feature is achieved, reducing the height difference between the high and low regions by preferentially forming a modified layer on the high region of the feature and then removing the modified layer.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] This application claims the benefit and priority of the filing date of U.S. Non-Provisional Patent Application No. 16 / 944,563, filed on Jul. 31, 2020, which is hereby incorporated by reference in its entirety.

[0002] This application relates to planarization of a substrate. In particular, embodiments of a system and method for planarizing a surface of a substrate are provided herein.

Background Art

[0003] Atomic layer processes, such as atomic layer deposition (ALD) and atomic layer etching (ALE), can provide technologies that can accurately control material properties and nanometer dimensions and have become important in the industry. Atomic layer deposition (ALD) is a well-known technique for forming thin layers on a substrate. In ALD, the substrate is periodically exposed to alternating gas species (or precursors), which react self-limitingly or nearly self-limitingly on the substrate surface, and a thin film or layer is slowly formed on the substrate. Generally, multiple ALD cycles are performed, and by repeating the alternating cycles of gas species, the desired film thickness is deposited or formed.

[0004] Atomic layer etching (ALE) is a well-known technique for continuously removing or etching thin layers (often only one monolayer at a time) through one or more self-limiting or nearly self-limiting reactions. The ALE process often includes multiple ALE cycles of layer modification steps and etching steps. In the layer modification step, the exposed surface of the substrate is modified, and in the etching step, the modified layer is selectively removed. During the layer modification step, the surface of the substrate is exposed to a reactive precursor, the reactive precursor adsorbs to the surface material, reacts, and a modified surface layer is formed. This layer modification step can be self-limiting, for example, if the reaction stops after one monolayer has adsorbed. During the etching step, ions are collided with the surface of the substrate, and the modified surface layer can be removed or etched. Alternatively, other etching removal mechanisms may be used. Also, the etching step can be self-limiting if the energy or chemicals of the etching step are sufficient to remove the modified surface layer but insufficient to etch the underlying material. Generally, multiple ALE cycles are performed to remove or etch to the desired film thickness.

[0005] ALD and ALE processes can be carried out within various atomic layer processing systems or tools. For example, a batch furnace type system can be utilized for performing the ALD or ALE process. A single substrate system, in which the processing chamber is filled with gas and evacuated for a single substrate, is also available. Yet another system is the spatial atomic layer processing system. In the spatial atomic layer processing system, the substrate passes through multiple gas sources (e.g., a gas injector, a gas showerhead, or a gas showerhead having an injector outlet) and moves relatively fast. The necessary gas is injected in proximity to the substrate surface, the substrate rotates periodically, and the ALD or ALE processing step is achieved. SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0006] The planarization function is important in the manufacture of integrated circuits (ICs), which, during the IC manufacturing process, can be used at several levels, defects are suppressed, short circuits are avoided, and selective patterning techniques are performed. Chemical mechanical polishing (CMP) is an example of a planarization technique commonly used in IC manufacturing.

Means for Solving the Problem

[0007] A system and method for planarizing a patterned substrate in a spatial atomic layer processing system are provided. The patterned substrate may have, for example, one or more features having high and low regions, and there may be a height difference between the high and low regions. To planarize the patterned substrate or to reduce the height difference between the high and low regions, the patterned substrate is subjected to a selective atomic layer etching (ALE) process, and a modification layer may be preferentially formed on the high regions of the one or more features compared to the low regions of the one or more features. By preferentially forming a modification layer on the high regions of the one or more features and then removing the modification layer, in the selective ALE process, the high regions of the one or more features are preferentially etched, and the height difference between the high and low regions of the one or more features is reduced.

[0008] In certain embodiments of the selective ALE process described herein, a patterned substrate having one or more features is provided on a rotating platen of a spatial atomic layer processing system, and while the rotating platen is rotating, the surface of the patterned substrate is exposed to a first precursor gas, whereby a modified layer is preferentially formed on the high regions of the one or more features. In certain embodiments, for a given set of process variables (e.g., chemicals and temperature), as the rotation speed increases, preferential formation in the high regions is facilitated. By rotating the rotating platen at a high rotation speed, a modified layer is preferentially formed on the one or more features, and the thickness of the modified layer is greater in the high regions of the one or more features than in the low regions. Thereafter, when the modified layer is removed (in one example, but not limited to, a subsequent plasma removal step), the high regions are preferentially etched, reducing the height difference between the high and low regions of the one or more features.

[0009] By repeating the step of forming the modified layer and the step of removing the modified layer, using the selective ALE process described herein, the height of the one or more features may be gradually reduced until the desired planarization of the one or more features is achieved. Accordingly, a planarization technique using a spatial atomic processing system is provided, and an ALE process for planarizing a substrate is provided. In certain embodiments, the height difference is reduced by 25%. In another embodiment, the height difference is reduced by 50% or more. In this way, planarization may occur. In certain embodiments, the rotating platen is rotated at a speed of 30 RPM or more, and planarization is achieved. In another embodiment, the RPM is 100 RPM or more. For example, an RPM of 200 RPM or more may be used. In another embodiment, the rotating platen may be rotated at a speed of up to 6,000 RPM.

[0010] In one embodiment, a method for planarizing a patterned substrate in a spatial atomic layer processing system is provided. Generally, the method may be initiated by providing at least a first layer as part of the patterned substrate. In one embodiment, the first layer may have at least a portion of one or more features formed on the patterned substrate. In one embodiment, the one or more features may have a high region and a low region, and there may be a height difference between the high region and the low region. The first layer provided on the patterned substrate may include various materials. In one embodiment, the first layer may be an oxide.

[0011] Next, the method may include providing the patterned substrate on a rotating platen of the spatial atomic layer processing system and forming a modified layer on the first layer. At least one step of forming the modified layer on the first layer may include exposing the surface of the first layer to a first precursor gas that adsorbs on the surface of the first layer and reacts with the surface of the first layer to form the modified layer. When forming the modified layer, the surface of the first layer may be exposed to various first precursor gases. In one embodiment, the first precursor gas may include trimethylaluminum, BCl3, HF, Cl2, CF4 / O2, and / or F2 / He.

[0012] When forming the modified layer, by rotating the rotating platen at a high rotational speed, it is promoted that the modified layer is preferentially formed in the high regions of one or more features compared to the low regions of the one or more features. In the present application, "preferentially formed" means that the thickness of the modified layer may be greater in the high regions of one or more features than in the low regions of the one or more features. In certain embodiments, depending on the rotational speed of the rotating platen, deposition of the first precursor of the first precursor gas may be promoted in the high regions of one or more features compared to the low regions of the one or more features. In certain embodiments, the rotational speed may be selected from the range of 30 RPM to 240 RPM. In certain embodiments, the rotational speed may be adjusted during one or more of the steps of forming the modified layer and removing the modified layer.

[0013] After the modified layer is formed, in the method, the modified layer may be removed. In certain embodiments, the modified layer may be removed via a plasma removal step. By forming a modified layer on the first layer and then removing the modified layer, in the method, the high regions of one or more features are preferentially etched compared to the low regions of the one or more features, and the height difference between the low regions of the one or more features and the high regions of the one or more features may be reduced. In certain embodiments, in the method, the steps of forming the modified layer and removing the modified layer are repeated, the height difference is further reduced, and the patterned substrate may be planarized. In certain embodiments, by using the method, the height difference between the high region and the low region may be reduced by at least 50%. In another embodiment, another method for planarizing a patterned substrate in a spatial atomic layer processing system is provided. In this embodiment, the method may generally be initiated by providing the patterned substrate on the rotating platen of the spatial atomic layer processing system. As described above, the one or more features formed on the patterned substrate may have high regions and low regions.

[0014] Next, the method may include rotating a rotating platen and exposing the surface of the patterned substrate to a precursor gas to form a modified layer on the patterned substrate. In certain embodiments, the surface of the patterned substrate has an oxide, and the precursor gas may include trimethylaluminum, BCl3, HF, Cl2, CF4 / O2, and / or F2 / He.

[0015] As described above, depending on the rotation speed of the rotating platen, the modified layer may be preferentially formed in the high regions of one or more features. In certain embodiments, the rotation speed of the rotating platen may be selected from the range of 30 RPM to 240 RPM. In another embodiment, the rotation speed of the rotating platen may be selected from the range of 100 RPM to 6,000 RPM. In certain embodiments, the rotation speed of the rotating platen may exceed 200 RPM.

[0016] The method includes removing the modified layer after the modified layer is formed on the patterned substrate, and the high regions of one or more features may be preferentially etched compared to the low regions of one or more features. In certain embodiments, the modified layer may be removed via a plasma removal step. In certain embodiments, the rotation speed of the rotating platen may be adjusted during one or both of the steps of exposing the surface of the patterned substrate to the precursor gas to form the modified layer and removing the modified layer.

[0017] In certain embodiments, in the method, the steps of exposing the surface of the patterned substrate to the precursor gas to form a modified layer and removing the modified layer to gradually reduce the height of the one or more features are repeated until the desired planarization of the one or more features is achieved. In certain embodiments, in the desired planarization, the height difference between the high region and the low region may be reduced by at least 25%. In another embodiment, in the desired planarization, the height difference between the high region and the low region may be reduced by at least 50%.

[0018] A more complete understanding of the present invention and its advantages can be obtained by referring to the following description in conjunction with the accompanying drawings. In the drawings, like reference numerals represent like features. It should be noted, however, that the accompanying drawings show only exemplary embodiments of the disclosed concepts and thus do not limit the scope of the disclosed concepts, and other equally valid embodiments are permitted.

Brief Description of the Drawings

[0019]

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Embodiments for Carrying Out the Invention

[0020] A system and method for planarizing a patterned substrate in a spatial atomic layer processing system are provided. The patterned substrate may have, for example, one or more features having high and low regions, and there may be a height difference between the high and low regions. To planarize the patterned substrate or to reduce the height difference between the high and low regions, the patterned substrate may be subjected to selective atomic layer etching (ALE) processing. In this process, a modified layer is preferentially formed on the high regions of the one or more features compared to the low regions of the one or more features. By preferentially forming a modified layer on the high regions of the one or more features and then removing the modified layer, in the selective ALE process described herein, the high regions of the one or more features are preferentially etched, and the height difference between the high and low regions of the one or more features is reduced.

[0021] In one embodiment of the selective ALE process described herein, a patterned substrate including one or more features is provided on a rotating platen of a spatial atomic layer processing system, and by exposing the surface of the patterned substrate to a first precursor gas during rotation of the rotating platen, a modified layer is preferentially formed on the high regions of the one or more features. In certain embodiments, for a given set of process variables (e.g., chemicals and temperature), as the rotation speed increases, the preferential formation in the high regions increases. By rotating the rotating platen at a high rotation speed, the modified layer is formed more preferentially on the one or more features, and the thickness of the modified layer is greater in the high regions of the one or more features than in the low regions. In certain embodiments, the rotating platen may be rotated at a speed of 30 RPM or more, and a modified layer may be preferentially formed on the high regions. In another embodiment, the rotating platen may be rotated at a speed of 100 RPM or more. For example, an RPM of 200 RPM or more may be utilized. In certain embodiments, when implementing the techniques described herein, a rotation speed of up to 6,000 RPM may be utilized, for example.

[0022] Thereafter, when the modified layer is removed (an example, but not limited to this, is the subsequent plasma removal step), the high regions are preferentially etched, and the height difference between the high and low regions of one or more features is reduced. In certain embodiments, the removal step may be a plasma step. By repeating the step of forming the modified layer and the step of removing the modified layer until the desired planarization of the one or more features is achieved, the height of the one or more features may be gradually reduced using the selective ALE process described herein. In certain embodiments, the height difference between the high and low regions of the one or more features is reduced by 25% and the desired planarization is obtained. In another embodiment, the height difference is reduced by 50% or more. Accordingly, a planarization technique using a spatial atomic processing system is provided, and an ALE process for planarizing (or improving the planarization of) a patterned substrate is provided. As the height of the high features decreases, the area of the ALE chemical increases and the etch amount decreases with the planarization of the features. Thus, in the selective ALE process described herein, planarization of the patterned substrate is achieved without being affected by the physical damage of the conventional CMP technique, and thus it is a preferred alternative to CMP or is used together with CMP to suppress the influence of CMP damage. In certain embodiments, the steps on the substrate may be planarized by at least 25%, in another embodiment 50%, and in yet another embodiment 75% or more.

[0023] FIG. 1 shows an example of a spatial atomic layer processing system that can be used when planarizing a patterned substrate. More specifically, FIG. 1 shows an embodiment of a spatial atomic layer processing system that can be used to gradually reduce the height of one or more features formed on a patterned substrate using the selective ALE process described herein. However, it is understood that the system shown in FIG. 1 is merely an example of a system in which the technology described herein can be utilized. Other spatial atomic layer processing systems may be used to implement the technology described herein.

[0024] FIG. 1 presents a top - down view of a spatial atomic layer processing system 100 as seen from the inside of a processing chamber 105 of the spatial atomic layer processing system 100. As shown in FIG. 1, within the processing chamber 105, a rotating platen 110 for holding one or two or more substrates 115 is provided. Each of the substrates 115 may be placed on a susceptor (not shown) that supplies heat to the substrate. Also, within the processing chamber 105, a number of processing sections and purge sources are provided, and these may be arranged above the rotating platen 110 to provide various gases to the substrate. Also, a gas outlet pump port 140 may be provided.

[0025] In the exemplary embodiment shown in FIG. 1, the spatial atomic layer processing system 100 has three processing sections: a precursor adsorption section 120, an optional processing section 124, and a plasma processing section 128. The precursor adsorption section 120, the optional processing section 124, and the plasma processing section 128 are separated by an inert gas region, and the inert gas is introduced by a purge source 130. The inert gas introduced by the purge source 130 and a separate exhaust structure provided by the gas outlet pumping port 140 enable a high - speed rotation rate of the system without causing an adverse effect of mixing of the precursor and the reactant.

[0026] In certain embodiments of the selective ALE process, all three process compartments may be utilized, although in other embodiments this may not be necessary. For example, in one embodiment, in the selective ALE process, the precursor adsorption compartment 120 may be used to form a modified layer on the patterned substrate, and the plasma treatment compartment 128 may be used to remove the modified layer. In other embodiments, after a modified layer is formed in the precursor adsorption compartment 120 by the selective ALE process and before the modified layer is removed in the plasma treatment compartment 128, any processing compartment 124 may be used to supply one or more gases (e.g., an oxygen-containing gas, an inert gas, or a precursor gas) to the patterned substrate. In the embodiment of FIG. 1, the plasma treatment compartment 128 is used for the etching step of the ALE process, but since the particular atomic layer processing system 100 shown in FIG. 1 is merely exemplary, it is understood that non-plasma techniques for the etching step may also be used.

[0027] Typically, the precursor adsorption compartment 120 may be configured to provide a first precursor gas to one or more substrates 115. When the substrate is rotated under the precursor adsorption compartment 120, the surface of the substrate is exposed to the first precursor gas, which adsorbs onto the surface material and reacts with the surface material to form a modified layer. In the precursor adsorption compartment 120, the first precursor gas may be provided to the substrate in various different ways. In the illustrated embodiment, the precursor adsorption compartment 120 has a showerhead 121 and a precursor gas injector 122, and the first precursor gas is introduced into a processing space disposed above the substrate 115. The showerhead 121 and the precursor gas injector 122 may be configured in any conventional manner.

[0028] The precursor adsorption section 120 may be configured to provide various precursor gases to the substrate 115. For example, in certain embodiments, the first precursor gas may be, but is not limited to, a metal-containing precursor gas such as trimethylaluminum (TMA), titanium tetrachloride (TiCl4), bis-t-butylaminosilane (BTBAS), tetrakis(dimethylamino)titanium (TDMAT), tris(dimethylamino)silane (3DMAS), tetrakisethylmethylamino hafnium (TEMAHf). However, it is understood that the first precursor gas is not strictly limited to a metal-containing precursor gas and may include other precursor gases commonly used in semiconductor processing. For example, alternatively, the precursor adsorption section 120 may provide any gas of a wide range, including, but not limited to, BCl3, O2, Ar, HF, Cl2, CF4, He, NF3, H2, C4F8, CH3F, CHF3, SF6, O3, C3H3F3, HCl, NH4OH, TiCl4, SiCl4, CF4 / O2, and / or F2 / He, etc.

[0029] The plasma processing section 128 is provided to generate a plasma, which can be used for the removal (or etching) of the modified layer. The plasma is generated by supplying one or more processing gases to the plasma processing section 128 while power is applied to one or more electrodes disposed above and / or below the substrate rotating below the plasma processing section 128. In one example embodiment, a source voltage is applied to the upper electrode disposed above the substrate, a bias voltage is applied to the lower electrode disposed below the substrate, and a high-frequency electric field is formed between the upper electrode and the lower electrode. The high-frequency electric field dissociates one or more processing gases supplied to the plasma processing section 128 and converts them into a plasma. This plasma can be used for various processes such as, but not limited to, plasma etching, film deposition, and / or sputtering.

[0030] In an embodiment of the present application, the plasma generated within the plasma processing section 128 is used to remove (or etch) a modified layer, typically one monolayer at a time. When the substrate is rotated beneath the plasma processing section 128, ions collide with the surface of the substrate exposed to the plasma, and the modified layer is removed. As is well known, the bias voltage is selected or adjusted to control the ion bombardment energy, and thus the depth to which the modified layer is removed is controlled.

[0031] Various plasma etching chemistries may be used within the plasma processing section 128 to remove the modified layer. For example, but not limited to, Ar plasma, He plasma, thermal desorption, or plasma chemistries having a wide range of gases including BCl3, O2, Ar, HF, Cl2, CF4, He, NF3, H2, C4F8, CH3F, CHF3, SF6, O3, C3H3F3, HCl, NH4OH, TiCl4, SiCl4, etc. may all be used as is well known.

[0032] In certain embodiments, prior to removing the modified layer within the plasma processing section 128, any processing section 124 may be used to provide the substrate 115 with one or more gases (e.g., an oxygen-containing gas, an inert gas, or a second precursor gas). Any processing section 124 may provide one or more gases to the substrate in a variety of different ways. In the illustrated embodiment, any processing section 124 has a showerhead 125 and a gas injector 126, and gas is injected into a processing space disposed above the substrate 115. The showerhead 125 and the gas injector 126 may be configured in any conventional manner.

[0033] Any processing section 124 may be configured to supply a wide variety of gases to the substrate 115. In certain embodiments, any processing section 124 may provide an oxygen-containing gas, such as, for example, oxygen (O2), ozone (O3), to the substrate. When the substrate is rotated under any processing section 124 and the oxygen-containing gas is provided, the surface of the substrate is exposed to the oxygen-containing gas and the modified layer is oxidized. In certain embodiments, the oxidation may be used or assist in the removal of the modified layer. However, it is understood that any processing section 124 is not strictly limited to providing an oxygen-containing gas, and in other embodiments, it may be used to provide other gases to the substrate surface. For example, any processing section 124 may alternatively be used to expose the surface of the substrate to an inert gas (e.g., argon, nitrogen, or other inert gas), or a second precursor gas.

[0034] When the rotating platen 110 rotates (as indicated by the arrow), one or more substrates 115 move sequentially under the precursor adsorption section 120, any processing section 124, and the plasma processing section 128, and one or more cycles of the selective atomic layer etching (ALE) process described herein are performed. After the substrate 115 has rotated past the precursor adsorption section 120 and the plasma processing section 128, the purge source 130 provides a gas purge (e.g., an argon, nitrogen, or other inert gas purge) to suppress gas mixing. Although not shown in FIG. 1, a controller may be provided to control various operating parameters of the spatial atomic layer processing system 100, including, for example, temperature, gas flow, pressure, rotation speed, number of cycles, and the like.

[0035] The selective ALE process described in the present application, although not limited thereto, may be used for planarization of a patterned substrate in a spatial atomic layer processing system, such as the spatial atomic layer processing system 100 shown and described in FIG. 1. In the selective ALE process described in the present application, the rotation of the rotating platen 110 and the substrate 115 may be repeated over a number of cycles necessary to obtain the desired amount of planarization. In certain embodiments, in each rotation of the rotating platen 110, a complete ALE cycle, including layer modification and removal steps, may be performed. In the removal step, if a longer time than that provided by the high rotation speed of the rotating platen 110 is required, the layer modification step and the removal step may be separated, with layer modification being provided by one rotation of the rotating platen 110, while a separate additional rotation is used and the modified layer is removed.

[0036] In certain embodiments of the selective ALE process described in the present application, a patterned substrate including one or more features is provided on a rotating platen of a spatial atomic layer processing system, and while the rotating platen rotates at a high speed, the surface of the patterned substrate is exposed to a first precursor gas, whereby a modified layer may be preferentially formed in the high regions of the one or more features. The high rotation speed shortens the exposure time to the features, effectively forms a depletion state, and eliminates the time for the precursor gas to diffuse under the top surface of the patterned substrate. The first precursor gas adsorbs and reacts with the surface material of the patterned substrate to form a modified layer. Thereafter, when the modified layer is removed (e.g., in a subsequent plasma removal process), the high regions are preferentially etched, reducing the height difference between the high and low regions of the one or more features. By repeating the step of forming the modified layer and the step of removing the modified layer until the desired planarization of the one or more features is obtained, it becomes possible to gradually reduce the height of the one or more features using the selective ALE process described in the present application.

[0037] By rotating the rotating platen at a high rotational speed, it is promoted to preferentially form a modified layer in the high region of one or more features compared to the low region of the one or more features. More specifically, for a certain ALE chemical substance, for example, when the rotating platen is rotated at a rotational speed faster than 30 RPM, a modified layer is preferentially formed on one or more features, and as a result, the thickness of the modified layer becomes larger in the high region than in the low region of the one or more features. FIGS. 2 to 4 show the relationship between the layer thickness and the rotational speed. However, it is understood that the rotational speed may depend on the specific chemical properties used in the ALE process.

[0038] FIG. 2 provides a cross-sectional view of a patterned substrate 200 having one or more features 210 formed on a substrate 205. The patterned substrate 200 may be provided on the rotating platen of the spatial atomic layer processing system as described above with reference to FIG. 1. In the embodiment shown in FIG. 2, while the rotating platen rotates at a relatively low rotational speed, a modified layer 215 is formed on the patterned substrate 200 by exposing the surface of the patterned substrate 200 to a first precursor gas. The first precursor gas adsorbs and reacts on the surface of the patterned substrate 200 to form the modified layer 215. When formed at a low rotational speed, the thickness of the modified layer 215 is substantially equal at the top (T top ), bottom (T bottom ), and side (T side ) of the one or more features 210. Thereafter, when the modified layer 215 is removed (for example, in a subsequent plasma removal process), the high and low regions of the one or more features 210 (or the substrate 205) can be etched equally to some extent. Therefore, when the platen is rotated at a low rotational speed, it becomes difficult to provide the desired planarization.

[0039] Figure 3 provides a cross-sectional view of a patterned substrate 300 having one or more features 310 formed on a substrate 305. The patterned substrate 200 may be provided on a rotating platen of a spatial atomic layer processing system as previously described with reference to FIG. 1. In the embodiment shown in FIG. 3, during rotation of the rotating platen at a relatively high rotation speed (e.g., for a certain ALD chemistry, a rotation speed exceeding 30 RPM), a modified layer 315 is formed on the patterned substrate 300 by exposing the surface of the patterned substrate 300 to a first precursor gas. The first precursor gas adsorbs and reacts on the surface of the patterned substrate 300 to form the modified layer 315. When formed at a high rotation speed, the thickness of the modified layer 315 is greater at the top (T bottom ) and sides (T side ) of one or more features 310 than at the bottom (T top ). This is preferred because when the modified layer 215 is subsequently removed, the top of the feature 210 is preferentially etched.

[0040] To achieve preferential formation of the modified layer 315 at the top of the feature, the rotating platen may typically be rotated at a high rotation speed. In one embodiment, the rotation speed of the rotating platen may be selected from the range between 30 RPM and 240 RPM. In other embodiments, the rotation speed of the rotating platen may be selected from a wider range between 100 RPM and 6,000 RPM. In one embodiment, a rotation speed exceeding 200 RPM may be used to preferentially form the modified layer 315 in the high regions (e.g., the top and / or upper sides) of the feature. However, typically, the rotation speed required to achieve preferential formation of the modified layer 315 on the high regions may depend on the precursor gas species used for the formation of the modified layer.

[0041] FIG. 4 is a graph comparing the thickness (in angstroms) of an exemplary modification layer (e.g., aluminum oxide (Al2O3)) that can be formed on top of a feature as a function of time (seconds) when the rotating platen of the spatial atomic layer processing system is rotated at 30 RPM and 240 RPM. As shown in FIG. 4, the thickness of the modification layer formed on top of the feature increases more rapidly when the rotating platen is rotated at 240 RPM compared to 30 RPM. Al2O3 is an example, and it is understood that other modification layers may be formed.

[0042] FIGS. 5A - 5E show one embodiment of a process flow for planarizing a patterned substrate 400 using the selective ALE process described herein. As shown in FIG. 5A, the patterned substrate 400 may have one or more features 410 formed on a substrate 405. The features 410 shown in FIGS. 5A - 5E may represent any feature or structure on a substrate (e.g., semiconductor wafer) where planarization is desired. In certain embodiments, the height of one or more features 410 may be substantially equal or may vary across the patterned substrate 400. As shown in FIGS. 5B - 5E, the patterned substrate 400 is planarized by performing one or more cycles of the selective ALE process described herein, and the height of one or more features 410 may gradually decrease.

[0043] In certain embodiments, the selective ALE process described herein may be initiated by providing the patterned substrate 400 shown in FIG. 5A on the rotating platen of the spatial atomic layer processing system. In FIG. 5B, while the rotating platen rotates at a relatively high rotational speed, a modification layer 415 is formed on the patterned substrate 400 by exposing the surface of the patterned substrate 400 to a precursor gas. The precursor gas adsorbs and reacts on the surface of the patterned substrate 400 to form the modification layer 415. The rotational speed of the platen and the precursor gas chemistry may be selected such that the modification layer 415 is formed primarily on top 412 and / or upper sides 414 of one or more features 410.

[0044] In FIG. 5C, the modified layer 415 is removed and the height of one or more features 410 is reduced. In certain embodiments, the surface of the patterned substrate 400 may be exposed to a plasma and the modified layer 415 may be removed via plasma atomic layer etching.

[0045] In FIG. 5D, while rotating the rotating platen at a relatively high rotation speed, another modified layer 425 is formed on the patterned substrate 400 by exposing the surface of the patterned substrate 400 to a precursor gas. The precursor gas adsorbs and reacts on the surface of the patterned substrate 400 to form the modified layer 425. As described above, the rotation speed of the platen and the precursor gas chemistry may be selected such that the modified layer 425 is formed mainly on the upper portion 412 and / or the upper side portion 414 of one or more features 410.

[0046] In certain embodiments, the rotation speed of the platen may be the same as when forming the modified layer 415 and the modified layer 425. In another embodiment, the rotation speed of the platen may be adjusted when forming one or more of the modified layers. For example, the rotation speed of the platen may be increased when forming the modified layer 425 compared to the rotation speed used for forming the modified layer 415. By forming additional modified layers and varying the rotation speed of the platen, the preferential formation of the modified layer at the upper and / or upper side portions of the features may be varied using the selective ALE process described herein.

[0047] In FIG. 5E, the modified layer 425 is removed again and the height of one or more features 410 is further reduced. In certain embodiments, the surface of the patterned substrate 400 may be exposed to a plasma and the modified layer 425 may be removed via plasma atomic layer etching.

[0048] The layer modification step (Figs. 5B and 5D) and the removal step (Figs. 5C and 5E) may be repeated over a number of cycles until the desired planarization is achieved. In certain embodiments, the layer modification step and the removal step may be performed for each rotation of the rotating platen. In another embodiment, the layer modification step and the removal step are separated, with the layer modification being performed during one rotation of the platen and the modified layer being removed using a separate additional rotation. Also, when multiple segments are designed within the chamber, it is possible to have a configuration where multiple modification layer steps and removal steps are processed for each rotation.

[0049] Figs. 6A through 6E show another embodiment of a process flow for planarizing a patterned substrate 500 using the selective ALE process described in this application. As shown in Fig. 6A, the patterned substrate 500 may have one or more features 510 formed on a substrate 505. The features 510 shown in Figs. 6A through 6E may represent any feature or structure on a substrate (e.g., a semiconductor wafer) for which planarization is desired. In certain embodiments, the one or more features 510 may have a high region 512 and a low region 514, and the patterned substrate 500 may be planarized by performing the selective ALE process described in this application for one or more cycle numbers, and the height difference between the high region 512 and the low region 514 may gradually decrease.

[0050] In certain embodiments, the selective ALE process described herein may be initiated by providing a patterned substrate 500 on a rotating platen of a spatial atomic layer processing system. In FIG. 6B, while the rotating platen rotates at a relatively high rotational speed, a modified layer 515 is formed on the patterned substrate 500 by exposing the surface of the patterned substrate 500 to a precursor gas. The precursor gas adsorbs and reacts on the surface of the patterned substrate 500 to form the modified layer 515. The rotational speeds of the platen and the precursor gas chemistry may be selected such that the modified layer 515 is preferentially formed in the high regions 512 of the one or more features 510 as compared to the low regions 514 of the one or more features 510. As shown in FIG. 6B, for example, the modified layer 515 may be preferentially formed such that the thickness of the modified layer 515 is greater in the high regions 512 as compared to the low regions 514 of the one or more features 510.

[0051] In FIG. 6C, the modified layer 515 is removed and the height difference between the high regions 512 and the low regions 514 of the one or more features 510 is suppressed or reduced. In certain embodiments, the surface of the patterned substrate 500 may be exposed to a plasma and the modified layer 515 may be removed via plasma atomic layer etching.

[0052] In FIG. 6D, while the rotating platen is rotated at a relatively high rotational speed, another modified layer 525 is formed on the patterned substrate 500 by exposing the surface of the patterned substrate 500 to a precursor gas. The precursor gas adsorbs and reacts on the surface of the patterned substrate 500 to form the modified layer 525. As described above, the rotational speed of the platen and the precursor gas chemistry may be selected such that the modified layer 525 is preferentially formed in the high regions 512 of the one or more features 510 as compared to the low regions 514 of the one or more features 510. As shown in FIG. 6D, for example, the modified layer 525 may be preferentially formed such that the thickness of the modified layer 525 is greater in the high regions 512 as compared to the low regions 514 of the one or more features 510.

[0053] In one embodiment, when forming the modification layer 515 and the modification layer 525, the rotation speed of the platen may be the same. In another embodiment, the rotation speed of the platen may be adjusted when forming one or more of the modification layers. For example, the rotation speed of the platen may be increased when forming the modification layer 525 compared to the rotation speed used when forming the modification layer 515. By gradually increasing the rotation speed of the platen with the formation of additional modification layers, the preferential formation of the modification layer on the upper part and / or the upper side part of the feature may be changed using the selective ALE process described in the present application.

[0054] In FIG. 6E, the modified layer 525 is removed again, and the height difference between the high region 512 and the low region 514 of one or more features 510 is further suppressed or reduced. In one embodiment, the surface of the patterned substrate 500 may be exposed to the plasma, and the modified layer 525 may be removed through plasma atomic layer etching.

[0055] The layer modification (FIGS. 6B and 6D) step and the removal (FIGS. 6C and 6E) step may be repeated in a plurality of cycles until the desired planarization is achieved. In one embodiment, the layer modification step and the removal step may be performed for each rotation of the rotating platen. In other embodiments, the layer modification step and the removal step may be separated such that the layer modification is performed during one rotation of the platen, while a separate additional rotation may be used for the removal of the modification.

[0056] Thus, as shown and referenced in FIGS. 5A through 5E and 6A through 6E, a patterned substrate may be planarized using a selective ALE process. The amount of planarization may vary according to the ALE chemistry used and the number of process cycles. In certain embodiments, using the selective ALE process described herein, the height of one or more features may be gradually reduced until the desired planarization of the one or more features is achieved. Thus, a planarization technique is provided that provides an ALE process for planarizing a substrate using a spatial atomic processing system. In certain embodiments, the height difference is reduced by up to 25%. In another embodiment, the height difference is reduced by 50% or more. In yet other embodiments, the height difference may be almost completely removed.

[0057] Using the techniques described herein, the planarization of all or part of a wide variety of features may be improved. Thus, the physical arrangement and geometric shape of the aforementioned features 410 and 510 are merely examples, and it is understood that the advantages of using the techniques described herein are also significantly obtained in other features. Further, the features may be formed of any wide variety of materials utilized in substrate processing techniques. In one example, the features may be formed of an oxide. In one particular example, the features may be formed of silicon oxide. In yet another example, the features may be formed of silicon, silicon nitride, aluminum oxide, titanium oxide, and / or hafnium oxide. However, other materials may also be used. Also, the features may be formed by a combination of materials and / or structures, and thus, the features need not be uniform and may, for example, be formed by multiple layers of different materials.

[0058] In the above description, the rotational speed of the rotating platen is described as an important variable that can be used and / or controlled for improving the planarization of the patterned substrate. However, it is understood that other variables or combinations of variables for improving planarization can also be used. By way of non-limiting example, the techniques described herein may improve the planarization of the patterned substrate by controlling one or more of the following variables or process conditions: the rotational speed of the rotating platen (e.g., RPM), the chemistry of the various gases used in the selective ALE process (e.g., precursor gas, etching gas, or gas ratios), the duration of the layer modification step and / or the removal step, the number of cycles used to achieve the desired planarization, and other features of the spatial atomic layer processing system (e.g., temperature, pressure, vacuum, etc.). In addition to these, other variables and / or process conditions may be selected and / or controlled to improve the planarization of the patterned substrate. For example, the concentration of one or more gases supplied to the substrate surface, the gap or distance between the plasma source and the substrate surface, and various plasma parameters such as source power and / or bias power may be selected to achieve the desired planarization. Also, other processing parameters such as ozone density, inert gas dilution, gas ratio, and / or gas injector design may be selected to achieve the desired planarization.

[0059] In one embodiment, the spatial atomic layer processing system 100 shown in FIG. 1 is utilized to provide the desired planarization of the patterned substrate, or alternatively, the planarization of the patterned substrate may be improved. The spatial atomic layer processing system 100 shown in FIG. 1 is provided as an example of a processing system in which the techniques described herein may be utilized, but the disclosed techniques are not limited to the system shown in FIG. 1. In one embodiment, one or more members or features may be added to or removed from the spatial atomic layer processing system 100 shown in FIG. 1. In another embodiment, more sophisticated processing systems using an automated recipe database, input from other automated systems, etc. may be used to implement the techniques described herein.

[0060] FIG. 7 shows another embodiment of a spatial atomic layer processing system 600 that can be used for planarization of a patterned substrate. As shown in FIG. 7, typically, the spatial atomic layer processing system 600 may include a processing chamber 605, one or more sensors 610, and a controller 615. In certain embodiments, the processing chamber 605 may be similar to the processing chamber 105 shown in FIG. 1 and may include a rotating platen and a number of processing sections (e.g., a precursor adsorption section 120, any processing section 124, and a plasma processing section 128), a purge source, and a gas outlet pump port. However, the processing chamber 605 is not limited to the processing chamber 105 shown and described in FIG. 1 and may be configured differently in other embodiments.

[0061] In the spatial atomic layer processing system 600 shown in FIG. 6, sensors 610 and a controller 615 are provided to monitor various parameters and automatically adjust one or more variables and / or process conditions of the systems or processes described herein to achieve a planarization goal. In certain embodiments, the planarization goal may be a desired planarization or a desired reduction in the height difference between high and low regions of features on the patterned substrate. In certain embodiments, the planarization goal may include a target throughput number of substrates per unit time.

[0062] Sensor 610 may be coupled to and / or disposed within process chamber 605 to monitor various parameters of the substrate, system 600, and / or the selective ALE process described herein. Sensor 610 may include various sensors, including but not limited to, optical sensors (such as cameras, lasers, light, reflectometers, spectrometers, etc.), capacitive sensors, ultrasonic sensors, gas sensors, or other sensors that can monitor the state of the substrate and / or system 600. In one exemplary embodiment, one or more optical sensors may be used to in-situ measure the height difference between the high and low regions of process chamber 105. In another exemplary embodiment, a spectrometer may be used to measure the film thickness of one or more layers provided on a patterned substrate. In yet another embodiment, a residual gas analyzer (RGA) may be used to detect precursor breakdown for real-time chemical reaction completion detection.

[0063] Controller 615 is coupled to receive data from sensor 610 and is configured to control one or more process parameters of process chamber 605 based on the sensor data. In certain embodiments, controller 615 may be configured to analyze the data collected by sensor 610, provide feedback, and control various process parameters of the members of process chamber 605. In certain embodiments, controller 615 may use or analyze the sensor data to determine when to end one or more steps of the selective ALE process described herein. For example, controller 615 may receive data from a residual gas analyzer and detect an endpoint of a layer modification step. In another example, controller 615 may utilize spectroscopic ellipsometry to detect an average film thickness on a rotating substrate and provide an indication of film thickness changes during the selective ALE process. In certain embodiments, controller 615 may automatically terminate the selective ALE process when a planarization goal is achieved, e.g., when a desired planarization or a desired reduction in the height difference between high and low regions of features is achieved. In certain embodiments, controller 615 may automatically adjust one or more parameters during processing to achieve a planarization goal. Also, the sensor data and the controller may be used to achieve a desired substrate throughput goal. Further, the sensor data and the controller may be used to achieve a desired planarization goal together with a desired substrate throughput goal, or to achieve an alternative balance of various goals.

[0064] It should be noted that the controller 615 described in the present application can be implemented in a wide variety of ways. In one example, the controller may be a computer. In another example, the controller 615 may have one or more programmable integrated circuits, which may be programmed to provide the functions described in the present application. For example, one or more processors (e.g., microprocessors, microcontrollers, central processing units, etc.), programmable logic devices (e.g., complex programmable logic devices (CPLDs)), field programmable gate arrays (FPGAs), etc.), and / or other programmable integrated circuits may be programmed with software or other programming instructions to implement the functions described in the present application in the controller 94. Further, the software or other programming instructions may be stored on one or more non-transitory computer-readable media (e.g., memory storage devices, flash memories, dynamic random access memories (DRAMs), reprogrammable storage devices, hard drives, floppy disks (registered trademarks), DVDs, CD-ROMs, etc.), and it is noted that when the software or other programming instructions are executed by the programmable integrated circuit, the programmable integrated circuit executes the processes, functions, and / or capabilities described in the present application. Other modifications are also possible.

[0065] Figures 8-9 show embodiments of a method of utilizing the technology described in the present application. The embodiments shown in Figures 8-9 are merely examples, and it is understood that the technology described in the present application can be utilized in additional ways. Also, the steps described are not intended to be exclusive, and additional processing steps may be added to the methods shown in Figures 8-9. Further, the order of the steps is not limited to the order shown in the figures, and different orders may occur and / or various steps may be combined or performed simultaneously.

[0066] FIG. 8 shows one embodiment of a method 700 for planarizing a patterned substrate in a spatial atomic layer processing system. In method 700, in step 710, at least a first layer is provided as part of the patterned substrate. In certain embodiments, the first layer may have at least a portion of one or more features formed on the patterned substrate. In certain embodiments, the one or more features may have a high region and a low region, and there may be a height difference between the high region and the low region. Next, in method 700, the patterned substrate may be provided on a rotating platen of the spatial atomic layer processing system (step 720).

[0067] In method 700, in step 730, a modified layer is formed on the first layer. At least one step of forming a modified layer on the first layer may include exposing the surface of the first layer to a first precursor gas, and the first precursor gas adsorbs and reacts on the surface of the first layer to form the modified layer. By rotating the rotating platen at a higher rotational speed, preferential formation of the modified layer on the high regions of the one or more features is promoted compared to the low regions of the one or more features.

[0068] In method 700, in step 740, the modified layer is removed. By forming a modified layer on the first layer (step 730) and then removing the modified layer (step 740), in method 700, the high regions of the one or more features are preferentially etched compared to the low regions of the one or more features, and the height difference between the high regions of the one or more features and the low regions of the one or more features is reduced (step 750). In certain embodiments, in method 700, the steps of forming the modified layer and removing the modified layer may be repeated, and in step 760, the patterned structure may be further planarized.

[0069] FIG. 9 shows one embodiment of a method 800 for planarizing a patterned substrate in a spatial atomic layer processing system. In method 800, in step 810, a patterned substrate is provided on a rotating platen of the spatial atomic layer processing system. As described above, one or more features formed on the patterned substrate can have high regions and low regions. In method 800, in step 820, the rotating platen is rotated. In method 800, in step 830, the surface of the patterned substrate is exposed to a precursor gas, and a modified layer is formed on the patterned substrate. In method 800, due to the rotation speed of the rotating platen, the modified layer is preferentially formed in the high regions of the one or more features.

[0070] In method 800, in step 840, the modified layer is removed, and the high regions of the one or more features are preferentially etched compared to the low regions of the one or more features. In method 800, in step 850, until the desired planarization of the one or more features is achieved, the steps of exposing the surface of the patterned substrate to the precursor gas to form a modified layer and removing the modified layer to gradually reduce the height of the one or more features are repeated. In certain embodiments, in the desired planarization, the height difference between the high regions and the low regions may be reduced by at least 25%.

[0071] Throughout this specification, the terms "one embodiment" or "certain embodiments" are used to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention, but not necessarily in each embodiment. It should be noted that the appearance of the phrases "in one embodiment" or "in certain embodiments" in various places in this specification does not necessarily mean the same embodiment of the present invention. Further, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments. Various additional layers and / or structures may be included, and / or in other embodiments, the described features may be omitted.

[0072] As used herein, the term "substrate" means a base material or structure on which materials are formed, and includes these. It is clear that the substrate may include a single material, multiple layers of different materials, one or more layers having regions of different materials or regions of different structures therein, etc. These materials may include semiconductors, insulators, conductors, or combinations thereof. For example, the substrate may be a semiconductor substrate, a base semiconductor layer on a support structure, a metal electrode, or a semiconductor substrate having one or more layers, structures, or regions formed thereon. The substrate may be a conventional silicon substrate or other bulk substrate having a layer of semiconductor material. As used herein, the term "bulk substrate" means silicon-on-insulator (SOI) substrates such as silicon-on-sapphire (SOS) substrates and silicon-on-glass (SOG) substrates, epitaxial layers of silicon on a base semiconductor substrate, in addition to silicon wafers, and also means other semiconductors or optoelectronic materials such as silicon germanium, germanium, gallium arsenide, gallium nitride, and indium phosphide, and includes these. The substrate may be doped or undoped.

[0073] Systems and methods for processing substrates are described in various embodiments. The substrate may include any material portion or structure of a device, particularly a semiconductor or other electronic device, for example, a base substrate structure such as a semiconductor substrate, or a layer on or covering the base substrate structure such as a thin film. Thus, the substrate is not intended to be limited to any particular base structure, underlying layer, or coating layer, patterned or unpatterned layer, but rather any such layer or base structure, as well as any combination of layers and / or base structures is contemplated to be included.

[0074] One of ordinary skill in the art will appreciate that the various embodiments may be practiced without using one or more of the specific details, or by using other alternative and / or additional methods, materials, or components. To avoid obscuring aspects of the various embodiments of the present invention, in other instances, well-known structures, materials, or operations are not shown in detail or described in detail. Similarly, for purposes of explanation, specific numbers, materials, and configurations are shown to fully understand the present invention. However, the present invention may be practiced without specific details. Further, it is understood that the various embodiments shown in the drawings are for purposes of illustration and are not necessarily to scale.

[0075] From this description, further modifications and alternative embodiments of the described systems and methods will be apparent to one of ordinary skill in the art. Accordingly, it is understood that the described systems and methods are not limited to these exemplary arrangements. The forms of the systems and methods shown and described in this application are to be understood as exemplary embodiments. Various changes may be made in practice. Accordingly, although the present invention is described with reference to specific embodiments, various modifications and changes can be made without departing from the scope of the present invention. Accordingly, the specification and drawings are to be interpreted in an illustrative sense rather than a limiting sense, and such changes are intended to be included within the scope of the present invention. Further, any advantages, benefits, or solutions to the problems described in this application with respect to a particular embodiment are not intended to be construed as a critical, essential, or essential feature or element of any or all of the claims.

Description of Reference Numerals

[0076] 100 Spatial atomic layer processing system 105 Processing chamber 110 Rotating platen 115 Substrate 120 Precursor adsorption section 124 Optional processing section 128 Plasma processing section 140 Outlet pump port

Claims

1. A method for planarizing a patterned substrate in a spatial atomic layer processing system, comprising: providing at least a first layer on the patterned substrate, wherein the patterned substrate has an upper surface, a lower surface, and sidewalls between the upper surface and the lower surface, wherein a part of the first layer has a first thickness on the upper surface and a second thickness of a part of the first layer on at least one of the sidewalls or the lower surface; providing the patterned substrate on a rotating platen of the spatial atomic layer processing system, wherein the rotating platen has a rotation speed of at least 30 RPM; forming a modified layer on the first layer, wherein in at least one of the steps of forming the modified layer on the first layer, the surface of the first layer is exposed to a first precursor gas, which adsorbs on the surface of the first layer and reacts with the surface of the first layer to form the modified layer; rotating the rotating platen at a high rotation speed, whereby the modified layer is preferentially formed on the part of the first layer on the upper surface compared to the part of the first layer on the sidewalls or the lower surface; removing the modified layer, wherein in the steps of forming the modified layer on the first layer and removing the modified layer, the part of the first layer on the upper surface is preferentially etched compared to the part of the first layer on the sidewalls or the lower surface, reducing the height difference between the remaining first layer on the upper surface and the remaining first layer on the sidewalls or the lower surface; repeating the steps of forming the modified layer and removing the modified layer, wherein the rotation speed of the rotating platen is adjusted during one or more of the steps of forming the modified layer and removing the modified layer; A method having the above steps.

2. The method according to claim 1, wherein the deposition of the first precursor of the first precursor gas is enhanced on the first layer on the upper surface compared to the first layer on the sidewalls or the lower surface due to the rotation speed of the rotating platen.

3. The method according to claim 1, wherein the rotation speed of the rotating platen is selected from the range of 30 RPM to 240 RPM.

4. The method according to claim 1, wherein the difference in height is reduced by at least 50%.

5. The method according to claim 1, wherein the thickness of the modified layer is greater in a part of the first layer on the upper surface than on the first layer on the side wall or the lower surface.

6. The first precursor gas is trimethylaluminum, BCl 3 , HF, Cl 2 , C.F. 4 / O 2 , and / or F 2 The method of claim 1, wherein the aryl group is aryl.

7. The method according to claim 6, wherein the first layer contains an oxide.

8. The method according to claim 7, wherein the step of removing the modified layer comprises a plasma removal step.

9. The method according to claim 1, wherein the step of removing the modified layer comprises a plasma removal step.

10. The method according to claim 1, wherein the first layer contains an oxide.

11. A method for planarizing a patterned substrate in a spatial atomic layer processing system, comprising: providing the patterned substrate on a rotating platen of the spatial atomic layer processing system, wherein the patterned substrate has an upper surface, a lower surface, and side wall surfaces between the upper surface and the lower surface; rotating the rotating platen; exposing the surface of the patterned substrate to a precursor gas to form a modified layer on the patterned substrate, wherein the modified layer is preferentially formed on the upper surface according to the rotation speed of the rotating platen; removing the modified layer such that the upper surface is preferentially etched compared to the lower surface or the side wall surface; repeating the steps of exposing the surface of the patterned substrate to a precursor gas to form a modified layer and removing the modified layer to reduce the height difference between the upper surface and the lower surface until the desired planarization of the patterned substrate is achieved, wherein in the desired planarization, the height difference is reduced by at least 25%; wherein the rotation speed of the rotating platen is adjusted during one or more of the steps of exposing the surface of the patterned substrate to a precursor gas to form a modified layer and removing the modified layer.

12.

13. The method according to claim 11, wherein the rotation speed of the rotating platen is selected from the range of 30 RPM to 240 RPM.

14.

15. ​ ​ ​ ​ The precursor gas is trimethylaluminum, BCl 3 , HF, Cl 2 , CF 4 / O 2 , and / or F 2 / He, the method according to claim 11. ​ The surface of the patterned substrate contains an oxide, according to the method of claim 14.

16. The surface of the patterned substrate contains an oxide, according to the method of claim 11.

17. The rotational speed of the rotating platen exceeds 200 RPM, according to the method of claim 16.

18. The step of removing the modified layer has a plasma removal step, according to the method of claim 11.

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