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  • H10P72/00—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
  • H10P72/04—Apparatus for manufacture or treatment
  • H10P72/0402—Apparatus for fluid treatment
  • H10P72/0418—Apparatus for fluid treatment for etching
  • H10P72/0422—Apparatus for fluid treatment for etching for wet etching
  • H10P72/0424—Apparatus for fluid treatment for etching for wet etching using mainly spraying means, e.g. nozzles
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  • H10P72/04—Apparatus for manufacture or treatment
  • H10P72/0402—Apparatus for fluid treatment
  • H10P72/0418—Apparatus for fluid treatment for etching
  • H10P72/0422—Apparatus for fluid treatment for etching for wet etching
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C22/73—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals characterised by the process
  • C23C22/77—Controlling or regulating of the coating process
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C22/82—After-treatment
  • C23C22/83—Chemical after-treatment
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F1/00—Etching metallic material by chemical means
  • C23F1/08—Apparatus, e.g. for photomechanical printing surfaces
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F1/00—Etching metallic material by chemical means
  • C23F1/10—Etching compositions
  • C23F1/12—Gaseous compositions
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F1/00—Etching metallic material by chemical means
  • C23F1/10—Etching compositions
  • C23F1/14—Aqueous compositions
  • C23F1/16—Acidic compositions
  • C23F1/28—Acidic compositions for etching iron group metals
• • H—ELECTRICITY
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  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P50/00—Etching of wafers, substrates or parts of devices
  • H10P50/20—Dry etching; Plasma etching; Reactive-ion etching
  • H10P50/24—Dry etching; Plasma etching; Reactive-ion etching of semiconductor materials
  • H10P50/242—Dry etching; Plasma etching; Reactive-ion etching of semiconductor materials of Group IV materials
• • H—ELECTRICITY
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  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P50/00—Etching of wafers, substrates or parts of devices
  • H10P50/60—Wet etching
  • H10P50/64—Wet etching of semiconductor materials
  • H10P50/642—Chemical etching
• • H—ELECTRICITY
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  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P50/00—Etching of wafers, substrates or parts of devices
  • H10P50/60—Wet etching
  • H10P50/66—Wet etching of conductive or resistive materials
  • H10P50/663—Wet etching of conductive or resistive materials by chemical means only
  • H10P50/667—Wet etching of conductive or resistive materials by chemical means only by liquid etching only
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P72/00—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
  • H10P72/04—Apparatus for manufacture or treatment
  • H10P72/0402—Apparatus for fluid treatment
  • H10P72/0418—Apparatus for fluid treatment for etching
  • H10P72/0421—Apparatus for fluid treatment for etching for drying etching
• • H—ELECTRICITY
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  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P72/00—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
  • H10P72/04—Apparatus for manufacture or treatment
  • H10P72/0448—Apparatus for applying a liquid, a resin, an ink or the like
• • H—ELECTRICITY
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  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P72/00—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
  • H10P72/06—Apparatus for monitoring, sorting, marking, testing or measuring
  • H10P72/0612—Production flow monitoring, e.g. for increasing throughput
• • H—ELECTRICITY
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  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P72/00—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
  • H10P72/30—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for conveying, e.g. between different workstations
  • H10P72/32—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for conveying, e.g. between different workstations between different workstations
• • H—ELECTRICITY
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  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P72/00—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
  • H10P72/30—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for conveying, e.g. between different workstations
  • H10P72/33—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for conveying, e.g. between different workstations into and out of processing chamber
• • H—ELECTRICITY
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  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P72/00—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
  • H10P72/70—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping
  • H10P72/76—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping using mechanical means, e.g. clamps or pinches
  • H10P72/7604—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping using mechanical means, e.g. clamps or pinches the wafers being placed on a susceptor, stage or support
  • H10P72/7624—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping using mechanical means, e.g. clamps or pinches the wafers being placed on a susceptor, stage or support characterised by the mechanical construction of the susceptor, stage or support

Definitions

• Plasma etching and wet etching are two well-known techniques.
• Wet etching involves dispensing a chemical solution over the surface of a substrate or immersing the substrate in the chemical solution. Often, the chemical solution contains a solvent, chemicals designed to react with materials on the substrate surface, and chemicals to promote dissolution of the reaction products.
• the result of exposure of the substrate surface to the etchant is the removal of material from the substrate.
• Etchant composition and temperature may control the etch rate, specificity, and residual material on the surface of the substrate post etch.
• the desired reactions need to be both thermodynamically and kinetically favorable for a successful etch.
• the requirements for success become much more stringent for etching polycrystalline materials.
• the material removal rate should be uniform at the macroscopic and microscopic levels and occurs at a rate that is compatible with high volume manufacturing. Macroscopic uniformity can be addressed with careful engineering, but microscopic uniformity depends on the chemistry of the etch itself.
• the modification step may modify the exposed surfaces and the etch step may selectively remove the modified layer.
• a series of self-limiting reactions may occur and the cycle may be repeatedly performed.
• the process may use just one cycle.
• an ALE process may also include quasi-ALE processes. In such processes, a series of modification and etch step cycles may still be used.
• the removal step may not be purely self-limiting as after removal of the modified layer, the etch substantially slows down, though it may not completely stop.
• Known ALE techniques have thus far been accomplished in vacuum, or in the gas phase. Such techniques utilize plasma or high-temperature thermochemical reactions to modify the material surface followed by chemical or ligand exchange reaction to volatilize the modified layer. The nature of ALE leads to smoothing of the surface as it is etched.
• a method for improving both the microscopic and macroscopic uniformity of materials during etching is disclosed herein. These improvements may be accomplished through the formation and dissolution of thin, self-limiting layers on the material surface by the use of wet ALE techniques. For etching of polycrystalline materials, these self-limiting reactions can be used to prevent this roughening of the surface during etching.
• a wet ALE process uses sequential, self-limiting reactions to first modify the surface layer of a material and then selectively remove the modified layer.
• a platform for accomplishing the disclosed methods is disclosed. The platform may include a wet chemical supply system arranged to supply the chemical solutions of the wet ALE process.
• the platform may include both a wet etching tool and a dry etching tool in which substrates may move from the dry etching tool to the wet etching tool having environmentally separated chambers.
• the substrate may be processed within the dry and wet etching tools without exposure to the ambient atmosphere.
• a method of etching a substrate may comprise receiving the substrate, the substrate having a first material exposed, the first material comprising a polycrystalline material.
• the method further comprises selectively etching the polycrystalline material, the selectively etching including chemical modification of a surface of the polycrystalline material by exposing the surface to a chemical solution to provide a modified surface layer, and selective removal of the modified surface layer of the polycrystalline material by exposing the modified surface layer to a liquid-phase chemical solution.
• the chemical modification of the surface of the polycrystalline material includes oxidation of the polycrystalline material using an oxidizing agent.
• the oxidizing agent includes an oxygen- containing gaseous environment, a chemical solution containing dissolved oxygen or other oxidizing agent, or a solvent - such as water - that directly participates in the oxidation of the surface.
• the oxidizing agent is an oxygen- saturated chemical solution that includes oxygen dissolved in water, alcohol, or acetone.
• the chemical modification further includes passivation of the modified layer of the polycrystalline material using a complexing agent.
• the complexing agent includes a citrate.
• the chemical modification further includes passivation of the modified layer in the polycrystalline material by exposing the substrate to citric acid.
• the chemical modification includes exposing the substrate to molecular oxygen and a citrate.
• the system also comprises a chemical injection manifold fluidically coupled to the wet process chamber, and configured to cyclically dispense the first chemical solution and the second chemical solutions.
• the system further comprises controller programmably configured to control the time duration for each dispense cycle of the first chemical solution and the second chemical solution.
• the system is arranged wherein the first chemical solution comprises an oxidizing agent.
• the first chemical solution comprises an oxygen-saturated chemical solution.
• the first chemical solution comprises an oxygen- saturated chemical solution that includes oxygen dissolved in water, alcohol, or acetone.
• the system may further be configured wherein the chemical supply system is further arranged to supply a complexing agent.
• the complexing agent includes a citrate.
• the controller is programmably configured to provide the cyclically dispense of the first chemical solution and the second chemical solution partially overlapping in time. In another embodiment, the controller is programmably configured to provide the cyclically dispense of the first chemical solution and the second chemical solution in a manner not overlapping in time.
• the first chemical solution includes a complexing agent and the second chemical solution comprises water.
• Figure 4 illustrates the peak-to-peak roughness reduction which may occur in a wet ALE metal etch process.
• Figures 5 and 6 demonstrate exemplary methods for processing a substrate according to the techniques described herein.
• the platform may include both a wet etching tool and a dry etching tool in which substrates may move from the dry etching tool to the wet etching tool having environmentally separated chambers.
• the substrate may be processed within the dry and wet etching tools without exposure to the ambient atmosphere.
• the techniques described herein may be utilized for a wide variety of materials that are known in the substrate processing art. Such materials may include polycrystalline materials.
• the polycrystalline may be a metal.
• the metal may be a transition metal.
• the metal is a noble material.
• the metal may be comprised of ruthenium (Ru) or cobalt (Co).
• the wet etch technique described consists of sequentially exposing the substrate surface to two or more etchant solutions.
• the first etchant reacts with the surface of the substrate in a self-limiting fashion.
• the second etchant dissolves reaction products and exposes a fresh surface that is free to react with the first etchant in subsequent cycles.
• this wet etch ALE relies on the solubility of the reaction products for their removal.
• the reaction products are, however, readily soluble in the second etchant for material to be removed in the digital etch.
• the substrate surface to be removed reacts readily, and in a self- limiting fashion, with components of the first etchant, but does not react with the second etchant.
• the difference in substrate reactivity and product solubility can be accomplished with different chemical additives in a common solvent or with different solvents used for each of the two etchants.
• the techniques described herein offer the opportunity of multiple advantages over other etch approaches.
• the techniques provide the benefits of ALE such as precise control of total etch amount, control of surface roughness, and improvements in wafer-scale uniformity.
• the techniques also provide several benefits of wet etching such as the simplicity of the etch chamber, atmospheric etching conditions, and speed at which it can be accomplished.
• Equation 3 shows an exemplary dissolution reaction of the cobalt oxide when utilizing citric acid in the reaction.
• the oxidation reaction rates (K ox ) are much greater than the dissolution reaction rate (Kd) than surface roughness increases may not occur such as shown in Figure 1 B ( Figure 1 B illustrating the structure with oxidized metal region 120 being cobalt oxide on the structure surface). If the oxidation reaction rates (K ox ) are less than or equal to the dissolution reaction rate (Kd), than surface roughness may increase such as shown in Figure 1 C.
• the native oxide layer is presented as a cobalt oxide. Flowever, the native oxide formed may be composed of cobalt oxides, cobalt hydroxides, cobalt oxyhydroxides or some combination of these species.
• the following is a method for temporally separating the oxidation and dissolution steps of the etch process.
• Each reaction is carried out in its own etch solution.
• the oxidation step is self-limiting, and the dissolution step is selective to remove only the oxidized metal. If these conditions are generally met, the total etch amount will be an integer multiple of the self-limiting oxide thickness.
• Such a process will provide a wet ALE process that leads to decreasing surface roughness as the etch progresses.
• the oxidation step may be carried out with a solvent in which the oxidation products are insoluble. This allows the formation of a self-limiting oxidized layer without any material lost to dissolution.
• the oxidized surface can then be exposed to an etchant that will dissolve the oxidized layer without further oxidizing the surface.
• Complexing agents can be used to promote the solubility of the oxidized metal species. If these complexing agents are present in the oxidizing etchant, then a self- limiting metal complex is formed.
• the native oxide layer may be composed of cobalt oxides, cobalt hydroxides, cobalt oxyhydroxides or some combination of these species. This accomplishes the oxidation portion of the wet ALE.
• Non-aqueous solvents such as acetone or isopropyl alcohol can be used for the complexation step.
• Cobalt citrate is insoluble in these solvents, so a monolayer of cobalt citrate is formed as a self-limiting passivation layer.
• a non- aqueous solution of citric acid can be used as an etch bath or be dispensed over the substrate surface in a spin chamber.
• a self-limiting cobalt citrate layer is formed.
• This reaction is fast and self-limiting.
• the oxidation and complexation step can be accomplished in the same solution if the solution contains both dissolved oxygen and citric acid.
• the etchant may contain both of these components because both reactions are self-limiting and there is no reaction between molecular oxygen and citric acid in solution.
• a solvent rinse may be performed to remove excess citric acid solution without disturbing the self-limited cobalt complex.
• This rinse can be accomplished in a solvent bath or by dispensing the solvent over the substrate in a spin chamber.
• the solvent used for the complexation step can be used for the rinse step, but any solvent where the complexing agent is soluble but the metal complex is not soluble can be used.
• This rinse step prevents mixing of the oxidizing/complexing solution and the dissolution solution. A mix of these solutions can spontaneously etch cobalt. Forgoing the rinse step may allow spontaneous etching of cobalt and prevents many of the benefits of the digital etch.
• aqueous solution is used to remove the cobalt citrate layer.
• the substrate can be immersed in a water bath, or water can be dispensed over the substrate surface in a spin chamber.
• Cobalt citrate is readily soluble in aqueous solution; however, cobalt oxide and metallic cobalt are not. This process is shown in the four steps of Figures 2A-2D which show one etch cycle.
• oxidizing, complexing and dissolution solutions are described above are merely exemplary. Thus a wide range of solutions may be utilized, as may be appropriate for the particular material being etched and the concepts described herein are not limited to the particular oxidizing, complexing and dissolution solutions are described.
• oxidizers such as oxygen, ozone, water, nitrous oxide, or hydrogen peroxide
• complexing agents such as citrate, acetate, carboxylate containing species, or amine containing species
• dissolution solutions such as Acetonitrile
• the self-limiting oxide thickness can be changed based on the solvent and oxidizer used.
• the self-limiting thickness of the metal complex layer can be changed by using different complexing agents. For molecular oxygen and citric acid, about 0.28nm of cobalt is removed per etch cycle. Stronger oxidizers do not increase the amount of cobalt removed per etch cycle which suggests that the thickness of the cobalt citrate layer determines the etch rate per cycle.
• plot 405. The initial roughness of an unetched reference is shown as plot 405. This initial roughness of >5nm is reduced to ⁇ 1.5nm after only 10nm of cobalt has been removed as shown by plot 415. This improvement is maintained for additional etching, as shown by plot 410 which illustrates 30nm of cobalt etch.
• the use of a spin chamber is merely one embodiment and a wide variety of differing process tools may be used to perform the techniques described herein.
• the substrate could be dipped in chemical baths containing the etchants.
• the substrate can be sequentially immersed in a baths of each etchant in order with intermediate rinse baths to prevent cross contamination of the chemicals. This process can be repeated until an appropriate amount of material is removed.
• the process may be utilized with aerosol sprays, fogs or mists of each reactant. Further, it will be recognized that a combination of the various described tools for applying the reactants may be used, even within one cycle of the process.
• etching layers in which self-limiting processes are utilized to provide smooth layers.
• One application of such a technique may be for etching metal surfaces for a recess etch for fully self-aligned vias.
• metal-filled trenches in a dielectric material must be selectively etched without increasing the surface roughness of the metal. It will be recognized that such an application is merely exemplary and the techniques described herein may be used for many other applications.
• the wet etching techniques described herein may also be combined with dry etching techniques, such as plasma etching.
• dry etching techniques such as plasma etching.
• selectively dry etching the polycrystalline material may be accomplished first by exposing the polycrystalline material to a gas-phase environment. Then the wet etching techniques described herein may be performed. In this manner, a combination of dry and wet processing may be achieved, with the wet processing providing the wet ALE benefits described herein.
• the wet etching may be utilized to reduce the surface roughness that exists after the dry etching process.
• Figures 5-6 illustrate exemplary methods for use of the processing techniques described herein. It will be recognized that the embodiments of Figures 5-6 are merely exemplary and additional methods may utilize the techniques described herein. Further, additional processing steps may be added to the methods shown in the Figures 5-6 as the steps described are not intended to be exclusive. Moreover, the order of the steps is not limited to the order shown in the figures as different orders may occur and/or various steps may be performed in combination or at the same time.
• Figure 5 illustrates a method for etching a substrate.
• the method comprises step 505 of receiving the substrate, the substrate having a first material exposed, the first material comprising a polycrystalline material.
• the method includes a step 510 of selectively etching the polycrystalline material, the selectively etching including chemical modification of a surface of the polycrystalline material by exposing the surface to a chemical solution to provide a modified surface layer, and selective removal of the modified surface layer of the polycrystalline material by exposing the modified surface layer to a liquid-phase chemical solution.
• Figure 6 illustrates a method for etching a substrate.
• the method comprises step 605 of receiving the substrate with a first material composed of a polycrystalline material, and a second material composed of a different material, wherein an exposed surface of the polycrystalline material has a surface roughness characterized by a first surface roughness value.
• the method then includes step 610 of reducing the surface roughness to a second surface roughness value by exposing the substrate to a first wet chemical solution to chemically modify the polycrystalline material to create a chemically modified layer, followed by exposing the substrate to a second wet chemical solution to dissolve the chemically modified layer.
• the techniques described herein may be utilized with a wide range of processing systems, apparatus, and platforms.
• the techniques may be utilized in a wet etch processing system as shown in Figure 7A, and the wet etch processing system can be used in combination with a dry etch processing system as shown in processing platform embodiment of Figure 7B.
• Other variations can also be implemented.
• FIG. 7A is a block diagram of one example embodiment for a wet etch processing system 700 that can be used with respect to the disclosed techniques to etch (such as the wet ALE techniques described herein) a material on the surface of a substrate 706,.
• the wet etch processing system 700 includes a wet process chamber 710.
• the wet process chamber 710 may be a pressure controlled chamber.
• a substrate 706 (in one example a semiconductor wafer) is held on a substrate holder 708, such as for example an electrostatic chuck.
• the substrate holder 708 can also be configured to rotate at a controlled speed.
• a chemical supply system 702 (such as a wet chemical supply system) and a chemical injection manifold for a wet etch solution (for example a wet ALE etch as described herein) are used with the wet process chamber 710.
• the chemical supply system 702 can include reservoirs to hold the various liquid etch solutions and/or be connected to chemical supply line inputs.
• the chemical injection manifold 704 may be fluidly coupled to the wet process chamber 710. In operation, the chemical injection manifold may selectively apply desired chemicals to the wet process chamber 710, for example via a liquid delivery tube with a dispensing nozzle positioned within the wet process chamber 710.
• Components of the wet etch processing system 700 can be coupled to, and controlled by, a controller 712 that in turn can be coupled to a corresponding memory storage unit and user interface (not shown). Various processing operations can be executed via the user interface, and various processing recipes and operations can be stored in a storage unit. Accordingly, a given substrate 706 can be processed within the wet process chamber 710 with various techniques. It will be recognized that controller 712 may be coupled to various components of the wet etch processing system 700 to receive inputs from and provide outputs to the components.
• the software or other programming instructions can be stored in one or more non-transitory computer-readable mediums (e.g., memory storage devices, flash memory, dynamic random access memory (DRAM), reprogrammable storage devices, hard drives, floppy disks, DVDs, CD-ROMs, etc.), and the software or other programming instructions when executed by the programmable integrated circuits cause the programmable integrated circuits to perform the processes, functions, and/or capabilities described herein. Other variations could also be implemented.
• non-transitory computer-readable mediums e.g., memory storage devices, flash memory, dynamic random access memory (DRAM), reprogrammable storage devices, hard drives, floppy disks, DVDs, CD-ROMs, etc.
• FIG. 7B is a block diagram of an example embodiment for a platform 750 including a wet etch processing system 700 (such as for example as described in Figure 7 A) and a dry etch processing system 752.
• the wet etch processing system 700 may dispense various liquid etch solutions onto a material to perform a wet ALE process such as described above.
• the dry etch processing system 752 can implement any desired dry etch process that etches or removes material from a substrate being processed. For example, as discussed above, selectively dry etching a polycrystalline material may be accomplished first by exposing the polycrystalline material to a gas-phase environment of a dry etch. In operation, the dry etch processing system 752 etches a material on a substrate using dry etch chemistry.
• the dry etch processing system 752 can implement any of a wide variety of dry etch processes, such as for example, a plasma etch process, a reactive ion etch (RIE) process, a chemical vapor etch (CVE) process, an atomic layer etch (ALE) dry process, and/or other dry etch processes.
• a dry etch process may be performed before or after a wet etch process.
• a dry etch process can be carried out in a dry etch process chamber for the dry etch processing system 752 to remove material from the substrate resulting in a first surface roughness.

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