Classifications

• • 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
  • 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
  • H10P50/246—Dry etching; Plasma etching; Reactive-ion etching of semiconductor materials of Group III-V materials
• • 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
  • H10P14/00—Formation of materials, e.g. in the shape of layers or pillars
  • H10P14/60—Formation of materials, e.g. in the shape of layers or pillars of insulating materials
  • H10P14/63—Formation of materials, e.g. in the shape of layers or pillars of insulating materials characterised by the formation processes
  • H10P14/6302—Non-deposition formation processes
  • H10P14/6319—Formation by plasma treatments, e.g. plasma oxidation of the substrate
• • 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
  • H10P14/00—Formation of materials, e.g. in the shape of layers or pillars
  • H10P14/60—Formation of materials, e.g. in the shape of layers or pillars of insulating materials
  • H10P14/63—Formation of materials, e.g. in the shape of layers or pillars of insulating materials characterised by the formation processes
  • H10P14/6326—Deposition processes
  • H10P14/6328—Deposition from the gas or vapour phase
  • H10P14/6334—Deposition from the gas or vapour phase using decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition
  • H10P14/6339—Deposition from the gas or vapour phase using decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition deposition by cyclic CVD, e.g. ALD, ALE or pulsed CVD
• • 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
  • H10P14/00—Formation of materials, e.g. in the shape of layers or pillars
  • H10P14/60—Formation of materials, e.g. in the shape of layers or pillars of insulating materials
  • H10P14/69—Inorganic materials
  • H10P14/692—Inorganic materials composed of oxides, glassy oxides or oxide-based glasses
  • H10P14/6938—Inorganic materials composed of oxides, glassy oxides or oxide-based glasses the material containing at least one metal element, e.g. metal oxides, metal oxynitrides or metal oxycarbides
  • H10P14/6939—Inorganic materials composed of oxides, glassy oxides or oxide-based glasses the material containing at least one metal element, e.g. metal oxides, metal oxynitrides or metal oxycarbides characterised by the metal
• • 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
  • H10P14/00—Formation of materials, e.g. in the shape of layers or pillars
  • H10P14/60—Formation of materials, e.g. in the shape of layers or pillars of insulating materials
  • H10P14/69—Inorganic materials
  • H10P14/692—Inorganic materials composed of oxides, glassy oxides or oxide-based glasses
  • H10P14/6938—Inorganic materials composed of oxides, glassy oxides or oxide-based glasses the material containing at least one metal element, e.g. metal oxides, metal oxynitrides or metal oxycarbides
  • H10P14/6939—Inorganic materials composed of oxides, glassy oxides or oxide-based glasses the material containing at least one metal element, e.g. metal oxides, metal oxynitrides or metal oxycarbides characterised by the metal
  • H10P14/69391—Inorganic materials composed of oxides, glassy oxides or oxide-based glasses the material containing at least one metal element, e.g. metal oxides, metal oxynitrides or metal oxycarbides characterised by the metal the material containing aluminium, e.g. Al2O3
• • 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
  • H10P50/00—Etching of wafers, substrates or parts of devices
  • H10P50/20—Dry etching; Plasma etching; Reactive-ion etching
  • H10P50/28—Dry etching; Plasma etching; Reactive-ion etching of insulating materials
  • H10P50/282—Dry etching; Plasma etching; Reactive-ion etching of insulating materials of inorganic materials
  • H10P50/283—Dry etching; Plasma etching; Reactive-ion etching of insulating materials of inorganic materials by chemical means
• • 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
  • H10P50/00—Etching of wafers, substrates or parts of devices
  • H10P50/73—Etching of wafers, substrates or parts of devices using masks for insulating materials
• • 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
  • H10P95/00—Generic processes or apparatus for manufacture or treatments not covered by the other groups of this subclass
  • H10P95/06—Planarisation of inorganic insulating materials
  • H10P95/062—Planarisation of inorganic insulating materials involving a dielectric removal step
  • H10P95/064—Planarisation of inorganic insulating materials involving a dielectric removal step the removal being chemical etching

Definitions

• the present invention relates to the field of semiconductor manufacturing and semiconductor devices, and more particularly, to a method of selective etching of silicon oxide relative to silicon nitride.
• the method includes providing a substrate containing a silicon oxide film and a silicon nitride film, a1) exposing the substrate to a first gas that forms a first layer on the silicon oxide film and a second layer on the silicon nitride film, where the first gas contains boron, aluminum, or both, and a2) exposing the substrate to a nitrogen-containing gas that reacts with the first layer to form a first nitride layer on the silicon oxide film and reacts with the second layer to form a second nitride layer on the silicon nitride film, where a thickness of the second nitride layer is greater than a thickness of the first nitride layer.
• the method further includes a3) exposing the substrate to an etching gas that etches the first nitride layer and the silicon oxide film, where the second nitride layer protects the silicon nitride film from etching by the etching gas.
• the method further includes a0) exposing the substrate to a H 2 -containing gas that terminates the silicon oxide film with–OH surface species and terminates the silicon nitride film with–NH x surface species.
• the method includes providing a substrate containing a silicon oxide film and a silicon nitride film, a1) exposing the substrate to a BCl 3 gas that forms a first BCl 3 layer on the silicon oxide film and a second BCl 3 layer on the silicon nitride film, and a2) exposing the substrate to NH 3 gas that reacts with the first BCl 3 layer to form a first boron nitride layer on the silicon oxide film and reacts with the second BCl 3 layer to form a second boron nitride layer on the silicon nitride film, where a thickness of the second boron nitride layer is greater than a thickness of the first boron nitride layer.
• the method further includes a3) exposing the substrate to plasma-excited CF 4 gas that etches the first boron nitride layer and silicon oxide film, where the second boron nitride layer protects the silicon nitride film from etching by the etching gas.
• the method further includes a0) exposing the substrate to a H 2 -containing gas that terminates the silicon oxide film with–OH surface species and terminates the silicon nitride film with–NH x surface species.
• FIG. 1 is a process flow diagram for selective etching of a silicon oxide film relative to a silicon nitride film according to an embodiment of the invention
• FIGS. 2A– 2D schematically show through cross-sectional views a method of selective etching of a silicon oxide film relative to a silicon nitride film according to an embodiment of the invention
• FIG. 3 is a process flow diagram for selective etching of a silicon oxide film relative to a silicon nitride film according to an embodiment of the invention.
• FIGS. 4A– 4E schematically show through cross-sectional views a method of selective etching of a silicon oxide film relative to a silicon nitride film according to an embodiment of the invention.
• FIG. 1 is a process flow diagram for selective etching of a silicon oxide film relative to a silicon nitride film according to an embodiment of the invention
• FIGS. 2A– 2D schematically show through cross-sectional views a method of selective etching of a silicon oxide film relative to a silicon nitride film according to an embodiment of the invention.
• the processing method in the process flow diagram 10 includes, in 12, providing a substrate 2 containing a SiO 2 film 200 and a Si 3 N 4 film 220.
• the SiO 2 film 200 and the Si 3 N 4 film 220 are in the same horizontal plane, but embodiments of the invention may also be applied to films that are not in the same horizontal plane but are offset vertically.
• Si 3 N 4 is the most thermodynamically stable of the silicon nitrides and hence the most commercially important of the silicon nitrides.
• embodiments of the invention may be applied to other silicon nitrides that contain Si and N as the major constituents, where the silicon nitrides can have a wide range of Si and N compositions (Si x N y ).
• SiO 2 is the most thermodynamically stable of the silicon oxides and hence the most commercially important of the silicon oxides.
• embodiments of the invention may be applied to other silicon oxides that contain Si and O as the major constituents, where the silicon oxides can have a wide range of Si and O compositions (Si x O y ).
• the method further includes, in 14, exposing the substrate 2 to a first gas 201.
• the first gas 201 can contain boron, aluminum, or both boron and aluminum.
• the first gas 201 can include a boron hydride, a boron halide, an organoaluminum compound, an aluminum hydride, an aluminum chloride, or a combination thereof.
• the first gas 201 may be selected from the group consisting of BH 3 , BCl 3 , BF 3 , Al(CH 3 ) 3 , AlH 3 , AlCl 3 , and a combination thereof.
• the exposure may be performed with or without plasma excitation of the first gas 201.
• the exposure of the first gas 201 forms a first layer 202 (e.g., BCl 3 ) on the SiO 2 film 200 and a second layer 222 (e.g., BCl 3 ) on the Si 3 N 4 film 220.
• first layer 202 is thinner than the second layer 222 and the former may be incomplete with voids that expose the underlying SiO 2 film 200.
• This preferential adsorption of first gas 201 on the Si 3 N 4 film 220 is attributed to higher adsorption energy of the first gas 201 on the Si 3 N 4 film 220 than on the SiO 2 film 200 and this effect is strongly favored in the absence of plasma excitation or when using remote plasma excitation of the first gas 201.
• the method further includes, in 16, exposing the substrate 2 to a nitrogen-containing gas 203.
• the nitrogen-containing gas 203 may be selected from the group consisting of a nitrogen hydride, a nitrogen halide, N 2 , and a combination thereof.
• the nitrogen hydride can, for example, include NH 3 , N 2 H 4 , or a combination thereof.
• the nitrogen halide can, for example, include NCl 3 .
• the nitrogen- containing gas 203 may be selected from the group consisting of NH 3 , N 2 H 4 , NCl 3 , N 2 , and a combination thereof.
• the exposure may be performed with or without plasma excitation of the nitrogen- containing gas 203.
• the nitrogen-containing gas 203 reacts with the first layer 202 and the second layer 222 to form a first nitride layer 204 and a second nitride layer 224, respectively.
• the first nitride layer 204 and the second nitride layer 224 can contain boron nitride, aluminum nitride, or both.
• the first nitride layer 204 may be incomplete with voids that expose the underlying SiO 2 film 200. However, this is not required and the first nitride layer may be continuous.
• the second nitride layer 224 has a greater thickness than the first nitride layer 204 and is at least substantially continuous on the underlying Si 3 N 4 film 220.
• the first gas 201 contains BCl 3 and the nitrogen-containing gas contains NH 3 .
• the elementary reaction that forms boron nitride (BN) and volatile HCl byproducts can be represented as:
• boron nitride The formation of boron nitride is thermodynamically favorable and boron nitride provides strong etch protection against various commonly used etching gases.
• the exposing steps 14 and 16 may performed alternatively and sequentially. According to another embodiment, the exposing steps 14 and 16 may at least partially overlap in time. As shown by the process arrow 18, the exposing steps 14 and 16 may be repeated at least once until the thickness of the second nitride layer 224 is sufficient to act as an etch stop layer, while the thickness of the first nitride layer 204 is not sufficient to protect the SiO 2 film 200 in a subsequent etching process.
• the method further includes, in 20, exposing the substrate 2 to an etching gas 205.
• the etching gas 205 may be selected from any gas that etches silicon oxide, boron nitride, and aluminum nitride.
• the etching gas 205 may be plasma-excited and can contain a fluorocarbon gas, a hydrofluorocarbon gas, a hydrochlorocarbon gas, a hydrochlorofluorocarbon gas, or a combination thereof.
• the etching gas 205 can contain CF 4 , CF 2 Cl 2 , CH 2 F 2 , CH 4 , CH 3 F, CHF 3 , C 4 H 6 , C 2 H 4 , C 3 H 6 , CH 2 Cl 2 , CH 3 Cl, CHCl 2 , CH 2 ClF, CHCl 2 F, or a combination thereof.
• the etching gas 205 can optionally further include Ar, He, or a combination thereof. The exposure to the etching gas 205 etches the first nitride layer 204 and the SiO 2 film 200.
• the Si 3 N 4 film 220 is not etched as long as the second nitride layer 224 provides adequate protection against the etching gas 205.
• the exposure to the etching gas 205 may be stopped before the second nitride layer 224 ceases to adequately protect the Si 3 N 4 film 220 from etching.
• Plasma excitation of the etching gas 205 may be performed in conventional commercial plasma processing systems, including Inductively Coupled Plasma (ICP) systems, Capacitively Coupled Plasma (CCP) systems, microwave plasma systems, remote plasma systems that generate plasma excited species upstream from the substrate, electron cyclotron resonance (ECR) systems, and other systems.
• ICP Inductively Coupled Plasma
• CCP Capacitively Coupled Plasma
• ECR electron cyclotron resonance
• the exposing steps 14, 16, and 20 may be repeated at least once to redeposit the first nitride layer 204 and the second nitride layer 224 and further etch the SiO 2 film 202.
• the exposure to the etching gas 205 fully removes the first nitride layer 204 from the substrate 2 and etches the SiO 2 film 202.
• the exposure to the etching gas 205 may only partially remove the first nitride layer 204 and etch the SiO 2 film 202 before exposing steps 14 and 16 are repeated.
• the second nitride layer 224 may be removed using dry or wet etching processes that use strong oxidizing agents.
• FIG. 3 is a process flow diagram for selective etching of a silicon oxide film relative to a silicon nitride film according to an embodiment of the invention
• FIGS. 4A– 4E schematically show through cross-sectional views a method of selective etching of a silicon oxide film relative to a silicon nitride film according to an embodiment of the invention.
• the processing method in the process flow diagram 30 is similar to the process flow diagram 10 in FIG.
• the former further includes a pre-treatment step of exposing the substrate to a H 2 -containing gas that enhances the preferential formation of a first layer on a silicon nitride film relative to on a silicon oxide film, and thereby enhances the subsequent formation of a nitride layer on the silicon nitride film.
• the process flow diagram 30 includes, in 32, providing a substrate 4 containing a SiO 2 film 400 and a Si 3 N 4 film 420. This is schematically shown in FIG. 4A. Thereafter, in 34, the method includes exposing the substrate 4 to a H 2 -containing gas 401. This is schematically shown in FIG. 4B. The exposure to the H 2 -containing gas 401 results in termination of the SiO 2 film 400 with a -OH surface 402 and termination of the Si 3 N 4 film 420 with a–NH x surface 422.
• the method further includes, in 36, exposing the substrate 4 to a first gas 403.
• the exposure to the first gas 403 forms a first layer 404 (e.g., BCl 3 ) on the SiO 2 film 400 and a second layer 424 (e.g., BCl 3 ) on the Si 3 N 4 film 420. This is schematically shown in FIG. 4C.
• the method further includes, in 38, exposing the substrate 4 to nitrogen-containing gas 405.
• the nitrogen-containing gas 405 reacts with the first layer 404 and the second layer 424 to form a first nitride layer 406 and a second nitride layer 426, respectively.
• the exposing steps 34, 36 and 38 may performed alternatively and sequentially.
• the exposing steps 34, 36 and 38 may at least partially overlap in time.
• the exposing steps 34, 36, and 38 or the exposing steps 36 and 38 may be repeated at least once until the thickness of the second nitride layer 426 is sufficient to act as an etch stop layer, while the thickness of the first nitride layer 406 is not sufficient to protect the SiO 2 film 400 during a subsequent etching process.
• the method further includes, in 42, exposing the substrate 4 to an etching gas 407.
• an etching gas 407. This is schematically shown in FIG. 4E.
• the exposure to the etching gas 407 etches the first nitride layer 406 and the SiO 2 film 400.
• the second nitride layer 426 is partially etched, the Si 3 N 4 film 420 is not etched as long as the second nitride layer 426 provides adequate protection against the etching gas 407.
• the exposure to the etching gas 407 may be stopped before the second nitride layer 426 ceases to adequately protect the Si 3 N 4 film 420 from etching.
• the exposing steps 34, 36, 38, and 42 may be repeated at least once to redeposit the first nitride layer 406 and the second nitride layer 426 and further etch the SiO 2 film 402.
• the exposure to the etching gas 407 fully removes the first nitride layer 406 from the substrate 4 and etches the SiO 2 film 402.
• the exposure to the etching gas 407 may only partially remove the first nitride layer 406 and etch the SiO 2 film 402 before exposing steps 36, 38, and 42, or before exposing steps 34, 36, 38, and 42, are repeated.

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• 2020
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