The present disclosure relates to processing of substrates, and more particularly to a gas mixture preventing stiction of or repairing high aspect ratio (HAR) structures.
The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Substrate processing systems may be used to deposit film on a substrate such as semiconductor wafer or to etch, clean and/or otherwise treat the surface of the substrate. In some processes, the substrates may be subjected to wet processing. In these processes, the substrate may be mounted on a rotary chuck. As the rotary chuck is rotated, fluid nozzles may be used to dispense fluid such as a liquid or gas and/or heat may be applied to treat the substrate.
Some of the substrates include high aspect ratio (HAR) structures. For example, the HAR structures may include nanopillars, trenches or vias. The HAR structures have a width (parallel to a surface of the substrate) that is significantly less than a depth (perpendicular to a surface of the substrate) of the feature. More advanced processes include HAR structures having even higher aspect ratios. Pattern collapse occurs when one or more of the HAR structures collapse, move laterally relative to a surface of the substrate and/or directly contact adjacent HAR structures. Pattern collapse is often encountered during drying after a wet clean process.
Several processes have been used to reduce pattern collapse when drying substrates. For example, the substrate can be dried using supercritical CO2. However, supercritical CO2 is relatively expensive and has implementation issues. The surface of the substrate can be modified with a layer to prevent stiction. However, surface modification is often expensive since it requires extra chemistries to be used and applicable only to a specified film type, e.g., silicon oxide. Surface modification also leads to material loss since the modified layer needs to be removed. The substrate can also be dried using isopropyl alcohol (IPA) that is delivered to the surface of the substrate at a temperature close to the boiling point of IPA. However, some aspect ratios cannot be dried using boiling IPA without pattern collapse.
The substrate can also be treated using hydrogen fluoride (HF) vapor etching in vacuum equipment operated at vacuum pressures. However, the vacuum equipment is typically expensive and cannot be used to perform wet cleaning. The preceding wet clean step is often necessary to remove organic or metal contaminants from the surface of the substrate.
Repairing collapsed structures can be performed using plasma etching in vacuum equipment. However, the plasma etching hardware that is required is expensive.
A gas mixture for treating a substrate in a substrate processing system includes hydrogen fluoride gas, a vapor of alcohol, an additive consisting of a base, and a carrier gas.
In other features, the base is selected from a group consisting of ammonia and an organic base. The base is selected from a group consisting of amines and a heteroaromatic cyclic compound. The heteroaromatic cyclic compound contains at least one nitrogen atom. The heteroaromatic cyclic compound consists of pyridine.
In other features, the additive is in a range from 0.1 parts per million (ppm) to 2000 ppm (mass) of the gas mixture. In other features, the additive is in a range from 1 part per million (ppm) to 500 ppm (mass) of the gas mixture.
In other features, the additive and the alcohol are mixed to create a mixture. The additive comprises 0.01 wt % to 1 wt % of the mixture of the additive and the alcohol. The mixture of the alcohol and the additive is added to the carrier gas and then the hydrogen fluoride gas is added. In other features, the hydrogen fluoride gas, the alcohol and the carrier gas are mixed and then the additive is added.
In other features, the gas mixture includes the hydrogen fluoride gas in a range from 0.5% to 5% volume of the gas mixture, the mixture of the alcohol and the additive in a range from 0.5% to 2.5% volume of the gas mixture, and the carrier gas in a range from 92.5% to 99% volume of the gas mixture.
In other features, the gas mixture includes the hydrogen fluoride gas in a range from 0.05% to 10% volume of the gas mixture, the mixture of the alcohol and the additive in a range from 0.5% to 2.5% volume of the gas mixture, and the carrier gas in a range from 87.5% to 99.45% volume of the gas mixture.
In other features, the alcohol vapor is selected from a group consisting of methanol, isopropyl alcohol and an alcohol including 1 to 4 carbon atoms. The carrier gas consists of molecular nitrogen.
A method for treating high aspect ratio (HAR) structures arranged on a surface of a substrate includes a) spin rinsing the surface of the substrate using a first rinsing liquid; b) spinning off the first rinsing liquid from the surface of the substrate; and c) directing the gas mixture onto the surface of the substrate after the first rinsing liquid is dispensed.
In other features, the substrate includes silicon nitride film and silicon dioxide film that are exposed to etching during c), and the silicon dioxide film is etched relative to the silicon nitride film with a selectivity greater than or equal to four (4) during c).
In other features, c) is performed after b). Alternately, c) is performed within 60 seconds after a). The gas mixture is delivered by a nozzle located in a range from 1 mm to 40 mm from the surface of the substrate. The gas mixture is delivered from a nozzle at a dispense velocity in a range from 1 to 50 m/s.
In other features, the gas mixture is delivered from a nozzle at a flow rate of 1 to 20 slm. A cross-sectional area of an orifice of a nozzle delivering the gas mixture is in a range from 3 to 30 mm2. a), b) and c) are performed at a temperature in a range from 20° C. to 400° C. a), b) and c) are performed at a temperature in a range from 50° C. to 150° C. a), b) and c) are performed when the substrate is maintained at a predetermined pressure in a range from 900 hPa to 1100 hPa.
In other features, a), b) and c) are performed with the substrate arranged on a rotary chuck of a device. The gas mixture is delivered from one or more nozzles located in a vapor containment cavity recessed in a substrate-facing surface of a vapor containment head.
Further areas of applicability of the present disclosure will become apparent from the detailed description, the claims and the drawings. The detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the disclosure.
The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:
In the drawings, reference numbers may be reused to identify similar and/or identical elements.
Systems and methods according to the present disclosure relate to a gas mixture including hydrogen fluoride, alcohol and an additive that can be used for processing substrates. In some examples, the gas mixture is used for wet processing and dry etching of a substrate including high aspect ratio (HAR) structures. The wet processing and dry etching can be performed at or near atmospheric pressure in a wet clean tool after the substrate is processed. The combination of wet processing and dry etching in a single hardware device provides a less expensive alternative to the other drying processes and adds little or no processing time. Alternately, the wet processing can be completed in the wet processing tool and the repair process can be performed in a separate repair tool. In some examples, after exposure to a rinsing liquid such as isopropyl alcohol (IPA), a gas mixture is dispensed onto the surface of the substrate.
Patterned structures such as HAR structures on substrates are sensitive to pattern collapse and require advanced drying systems and methods to avoid pattern damage post wet process. Examples of these systems and methods are described in commonly assigned U.S. Provisional Patent Application Ser. No. 62/575,705, filed on Oct. 23, 2017 and entitled “Systems and Methods for Preventing Stiction of High Aspect Ratio Structures and/or Repairing High Aspect Ratio Structures”; and commonly assigned U.S. Provisional Patent Application Ser. No. 62/721,710, filed on Aug. 23, 2018 and entitled “Vapor Containment Head for Preventing Stiction of High Aspect Ratio Structures and/or Repairing High Aspect Ratio Structures”.
In some examples, these systems are used to remove oxide grown at contact locations to prevent subsequent pattern collapse. Some substrates also include exposed hard masks such as a silicon nitride (Si3N4) hard mask. To achieve collapse-free performance, some amount of oxide etching is required. However, it is difficult to etch the oxide without also causing damage to the hard masks.
The additive in the gas mixture according to the present disclosure acts as a proton acceptor and promotes the formation of bifluorine (HF2), which is the active species in oxide etch. Etching of the silicon nitride hard mask is mainly determined by adsorbed HF concentration. The gas mixture described herein provides increased etch selectivity of oxide relative to silicon nitride as compared to the gas mixture without the additive. Using the gas mixture with the additive as described herein can increase the selectivity from less than 1 to greater than or equal to 4.
In some examples, the additive consists of a base. In some examples, the additive is in a range from 0.1 parts per million (ppm) to 2000 ppm (mass) of the gas mixture. In some examples, the base is selected from a group consisting of ammonia (NH3) and an organic base. The base can be selected from a group consisting of amines and a heteroaromatic cyclic compound. In some examples, the heteroaromatic cyclic compound contains at least one nitrogen atom. In other examples, the heteroaromatic cyclic compound consists of pyridine (C2H5N).
In some examples, the gas mixture is prepared by creating a mixture of the additive and the alcohol. The mixture of the alcohol and the additive is added to the carrier gas and then the hydrogen fluoride gas is added. In other examples, the hydrogen fluoride gas, the carrier gas and the alcohol are mixed together to form a gas flow and then the additive is added to the gas flow. In some examples, the additive is in a range from 1 part per million (ppm) to 500 ppm (mass) of the gas mixture.
In some examples, the gas mixture includes the hydrogen fluoride gas in a range from 0.5% to 5% volume of the gas mixture, the mixture of the alcohol and the additive in a range from 0.5% to 2.5% volume of the gas mixture, and the carrier gas in a range from 92.5% to 99% volume of the gas mixture.
In other features, the gas mixture includes the hydrogen fluoride gas in a range from 0.05% to 10% volume of the gas mixture, the mixture of the alcohol and the additive in a range from 0.5% to 2.5% volume of the gas mixture, and the carrier gas in a range from 87.5% to 99.45% volume of the gas mixture.
In some examples, the alcohol vapor is selected from a group consisting of methanol, isopropyl alcohol (IPA) and an alcohol including 1 to 4 carbon atoms. In some examples, the carrier gas consists of molecular nitrogen. In some examples, the carrier gas consists of an inert gas.
The gas mixture described herein may be used for treating high aspect ratio (HAR) structures arranged on a surface of a substrate. As used herein, HAR structures include structures having an aspect ratio greater than 4:1. For example, a method for using the gas mixture may include spin rinsing the surface of the substrate using a first rinsing liquid, spinning off the first rinsing liquid from the surface of the substrate, and directing the gas mixture onto the surface of the substrate after the first rinsing liquid is dispensed. Additional details and examples are set forth below.
Referring now to
In
Referring now to
In some examples, the surface 60 of the rotary chuck 56 is transparent and a heater 61 is arranged under the surface 60. In some examples, the heater 61 includes a plurality of light emitting diodes (LEDs) that are arranged in one or more radial zones to allow radial heating of the substrate 60. In some examples, the heater 61 can be operated to provide a moving heat wave that moves from a central location of the substrate outwardly to a radially outer edge thereof. In some examples, the rotary chuck 56 rotates and the heater 61 is stationary. Suitable examples of a rotary chuck performing radial heating of the substrate are shown and described in U.S. patent application Ser. No. 15/232,594.
In some examples, the rotary chuck 56 is rotated by a motor 62 via a drive shaft 63 as shown. In other examples, the motor 62 includes a rotor and stator and the rotor is driven magnetically without physical contact. Suitable examples are shown in commonly assigned U.S. Pat. No. 6,485,531. Rinsing liquid is delivered by an arm 64 and a nozzle 66 that are scanned across the substrate 58 by a motor 70. A valve 72 selectively supplies the rinsing liquid from a liquid supply 74 to the arm 64.
Another arm 84 (shown in an inactive position in
A motor 90 may be used to scan the nozzle 86 across the substrate 58 and a valve 92 may be used to selectively supply the gas mixture. A gas delivery system 100 includes a vapor supply 102 and a valve 104. In some examples, the vapor supply 102 includes a heated liquid ampoule, bubbler or other vaporizer. In some examples, the additive and the alcohol are supplied as liquids in the ampoule and the carrier gas flows across and entrains the liquid. Then, the hydrogen fluoride gas is added. Alternately, the alcohol is entrained by the carrier gas, the hydrogen fluoride gas is added to the carrier gas prior to or after entraining the alcohol. Then, the additive is then added to the gas mixture. Still other variations are contemplated.
The gas delivery system 100 further includes one or more gas supplies 112-1, 112-2, . . . , and 112-N (collectively gas supplies 112) and valves 114-1, 114-2, . . . , and 114-N (collectively valves 114). An optional manifold 110 may be used to allow the gases and vapors to mix prior to delivery via the optional valve 92. In some examples, mass flow controllers (not shown) are provided to more precisely control the gases and/or solvent vapor. A controller 130 controls the valves, the motors and the gas delivery system 100.
In
Referring now to
In some examples, the rotary chuck 150 includes a plurality of gripping pins 155 arranged thereon and a transparent plate 156 arranged below the substrate 58. A heater 157 such as a printed circuit board including light emitting diodes (LEDs) may be arranged below the transparent plate 156 to heat the substrate 58. In some examples, the heater 157 produces a moving heat wave that is used during cleaning and/or repair. The moving heat wave moves from a central location of the substrate outwardly to a radially outer edge thereof. In some examples, the heater 157 is stationary and the rotary chuck 150 rotates. Suitable examples of a rotary chuck performing radial heating of the substrate are shown and described in commonly assigned U.S. patent application Ser. No. 15/232,594. In some examples, a fan 158 supplies airflow 159 to the top surface of the chamber 151 during processing.
Referring now to
In some examples, the showerhead 170 includes a plate including a plurality of through holes. The gas mixture is delivered by the gas delivery system 100 and the valve 92 to a gas plenum 172. The gas mixture flows into the gas plenum 172, through the showerhead 170, and into the chamber 52 to expose the substrate 58. In some examples, a vertical position of the showerhead 170 and the gas plenum 172 is adjusted by one or more motors 174 and shafts 176 to a location closer to the substrate prior to delivery of the gas mixture when repairing or preventing collapse.
Referring now to
After a predetermined period (at 198), the gas mixture including hydrogen fluoride, alcohol and the additive is supplied at 202. In other examples, the gas mixture can be applied in an overlapping manner during 194. The substrate can be either rotating or not rotating when applying the gas mixture.
In some examples, the predetermined period is in a range from 0 to 60 seconds. In some examples the gas mixture starts to be supplied before the rinsing step 192 has ended. The gas mixture is delivered for a predetermined period to prevent collapse and/or to repair HAR structures by removing bridging oxides.
Referring now to
In
In
Referring now to
In some examples, the surface 810 of the rotary chuck 806 is transparent and a heater 811 is arranged under the surface 810. In some examples, the heater 811 includes a plurality of light emitting diodes (LEDs) that are arranged in one or more radial zones to allow radial heating of the substrate 808. In some examples, the heater 811 can be operated to provide a moving heat wave that moves from a central location of the substrate outwardly to a radially outer edge thereof. In some examples, the rotary chuck 806 rotates and the heater 811 is stationary. Suitable examples of a rotary chuck performing radial heating of the substrate are shown and described in U.S. patent application Ser. No. 15/232,594.
In some examples, the rotary chuck 806 is rotated by a motor 812 via a drive shaft 813 as shown. In other examples, the motor 812 includes a rotor and stator and the rotor is driven magnetically without physical contact. Suitable examples are shown in commonly assigned U.S. Pat. No. 6,485,531. Rinsing liquid is delivered by an arm 814 (shown in an inactive position) and a nozzle 816 that are scanned across the substrate 808 by a motor 820. The motor 820 scans the arm across the rotating substrate in a radial direction or arcuate direction. A valve 822 selectively supplies the rinsing liquid from a liquid supply 824.
Another arm 834 (shown in an active position in
A motor 840 may be used to scan the vapor containment head 836 across the substrate 808 and a valve 842 may be used to selectively supply the gas mixture. A gas delivery system 850 includes a vapor supply 852 and a valve 854. In some examples, the vapor supply 852 includes a heated liquid ampoule, bubbler or other vaporizer. The gas delivery system 850 further includes one or more gas supplies 862-1, 862-2, . . . , and 862-N (collectively gas supplies 862) and valves 864-1, 864-2, . . . , and 864-N (collectively valves 864). A manifold 870 may be used to allow the gases to mix prior to delivery via the valve 842. In some examples, mass flow controllers (not shown) and/or secondary valves are provided to more precisely control the gases and/or solvent vapor. A controller 880 controls the valves, the motors and the gas delivery system 850.
In
In
In
In some examples, the vapor containment head 836 includes a heater 897 to control a temperature thereof. In some examples, the heater 897 includes a resistive heater. A temperature sensor 898 such as a thermocouple may be used to sense a temperature of the vapor containment head 836. The controller 880 monitors the temperature sensor 898 and adjusts operation of the heater to provide a desired temperature. In other examples, the heater 897 includes a temperature coefficient of resistance (TCR) heater, which has a resistance that is related to a temperature thereof. If the TCR heater is used, the controller 880 monitors voltage and/or current supplied to the TCR heater to determine the resistance and varies the voltage and current to provide a desired resistance corresponding to a desired temperature.
Referring now to
Referring now to
Fasteners 922 are arranged in bores defined in the flanged lower portion 914 and the second portion 918 to connect the first portion 910 to the second portion 918. The vapor containment head 900 includes a back side surface 926 and a bottom surface 930. The back side surface 926 may be connected to an arm, a nozzle head or other supporting structure. The bottom surface 930 is arranged adjacent to and is swept across a top surface of the substrate during processing.
In
In some examples, the vapor containment cavity 1050 is bounded by side surfaces and a downwardly facing surface of the second portion 918. In some examples, the vapor containment cavity has a generally rectangular cross section with rounded edges in a plane that is perpendicular to the substrate, although other shapes can be used. In some examples, the vapor containment cavity has a banana-shaped cross section in a plane perpendicular to the substrate, although other shapes can be used.
Through holes 1054 pass from an inner plenum (shown below) defined by the vapor containment head 900 through the bottom surface 930 to supply vapor and/or other gases into the vapor containment cavity 1050. While through holes 1054 are shown, one or more nozzles or slit-shaped nozzles can be used. Alternately, fluid passages may pass through the body of the vapor containment head and connect directly to through holes, nozzles or slit-shaped nozzles. In some examples, the through holes 1054 have a diameter in a range from 0.1 mm to 2 mm, although other diameters can be used. In some examples, the through holes 1054 have a diameter in a range from 0.4 mm to 0.6 mm, although other diameters can be used. In some examples, the vapor containment cavity defines an area covering 0.1% to 30% of the substrate area. Alternatively one or more slit-shaped nozzles can be used.
The number of through holes 1054 and their relative arrangement can be varied. Likewise, a cross-sectional shape of the vapor containment head 900 and a shape of the vapor containment cavity 1050 can be varied. In some examples, the through holes 1054 are arranged adjacent to a leading-edge of the vapor containment head 900 as it is swept across the rotating substrate during processing (with rows of through holes 1054 arranged perpendicular to a sweep direction). In some examples, the through holes 1054 of the vapor containment head are cleared from an edge of the substrate when the vapor containment head is not in use.
Referring now to
In some examples, a seal 1120 (such as a gasket of an O-ring arranged in a channel (not shown) formed on the first portion 910 and/or the second portion 918) may be used to provide a seal between the first portion 910 and the second portion 918. In other examples, the first portion 910 and the second portion 918 may be welded together to provide a seal.
A tube gripping element 1130 arranged at an opening of a gas flow passage 1134 grips an end of a tube 1132. In some examples, the gas flow passage 1134 is arranged in a horizontal direction. The gas flow passage 1134 fluidly connects to a gas flow passage 1138. In some examples, the gas flow passage 1138 is arranged in a vertical direction. The gas flow passage 1138 fluidly connects the gas flow passage 1134 to the internal plenum 1110.
A tube gripping element 1140 arranged at an opening of a gas flow passage 1144 grips an end of a tube 1142. In some examples, a gas flow passage 1144 is arranged in a horizontal direction and fluidly connects to a gas flow passage 1148. In some examples, the gas flow passage 1148 is arranged in a vertical direction. The gas flow passage 1148 fluidly connects the gas flow passage 1144 to the internal plenum 1110.
In some examples, the through holes 1054 are arranged adjacent to an edge such as a leading edge 1160 of the vapor containment head 900. In some examples, the through holes 1054 include staggered rows including 9, 8 and 9 through holes 1054, although additional or fewer rows and/or through holes can be used. In some examples, the through holes 1054 are arranged in an area that is less than or equal to 25% of the area defined by the vapor containment cavity 1050. In
The foregoing description is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent upon a study of the drawings, the specification, and the following claims. It should be understood that one or more steps within a method may be executed in different order (or concurrently) without altering the principles of the present disclosure. Further, although each of the embodiments is described above as having certain features, any one or more of those features described with respect to any embodiment of the disclosure can be implemented in and/or combined with features of any of the other embodiments, even if that combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and permutations of one or more embodiments with one another remain within the scope of this disclosure.
Spatial and functional relationships between elements (for example, between modules, circuit elements, semiconductor layers, etc.) are described using various terms, including “connected,” “engaged,” “coupled,” “adjacent,” “next to,” “on top of,” “above,” “below,” and “disposed.” Unless explicitly described as being “direct,” when a relationship between first and second elements is described in the above disclosure, that relationship can be a direct relationship where no other intervening elements are present between the first and second elements, but can also be an indirect relationship where one or more intervening elements are present (either spatially or functionally) between the first and second elements. As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean “at least one of A, at least one of B, and at least one of C.”
The present disclosure is a U.S. National Phase Application under 35 U.S.C. 371 of International Application No. PCT/US2019/053249, filed on Sep. 26, 2019, which claims the benefit of U.S. Provisional Application No. 62/740,562, filed on Oct. 3, 2018. The entire disclosures of the applications referenced above are incorporated herein by reference.
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PCT/US2019/053249 | 9/26/2019 | WO |
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WO2020/072278 | 4/9/2020 | WO | A |
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