US20140042516A1 - Semiconductor memory device and manufacturing method thereof - Google Patents
Semiconductor memory device and manufacturing method thereof Download PDFInfo
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- US20140042516A1 US20140042516A1 US13/715,504 US201213715504A US2014042516A1 US 20140042516 A1 US20140042516 A1 US 20140042516A1 US 201213715504 A US201213715504 A US 201213715504A US 2014042516 A1 US2014042516 A1 US 2014042516A1
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- H10B—ELECTRONIC MEMORY DEVICES
- H10B41/00—Electrically erasable-and-programmable ROM [EEPROM] devices comprising floating gates
- H10B41/30—Electrically erasable-and-programmable ROM [EEPROM] devices comprising floating gates characterised by the memory core region
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/40—Electrodes ; Multistep manufacturing processes therefor
- H01L29/401—Multistep manufacturing processes
- H01L29/4011—Multistep manufacturing processes for data storage electrodes
- H01L29/40114—Multistep manufacturing processes for data storage electrodes the electrodes comprising a conductor-insulator-conductor-insulator-semiconductor structure
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02104—Forming layers
- H01L21/02107—Forming insulating materials on a substrate
- H01L21/02296—Forming insulating materials on a substrate characterised by the treatment performed before or after the formation of the layer
- H01L21/02318—Forming insulating materials on a substrate characterised by the treatment performed before or after the formation of the layer post-treatment
- H01L21/02362—Forming insulating materials on a substrate characterised by the treatment performed before or after the formation of the layer post-treatment formation of intermediate layers, e.g. capping layers or diffusion barriers
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
- H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
- H01L21/76—Making of isolation regions between components
- H01L21/762—Dielectric regions, e.g. EPIC dielectric isolation, LOCOS; Trench refilling techniques, SOI technology, use of channel stoppers
- H01L21/76202—Dielectric regions, e.g. EPIC dielectric isolation, LOCOS; Trench refilling techniques, SOI technology, use of channel stoppers using a local oxidation of silicon, e.g. LOCOS, SWAMI, SILO
- H01L21/76205—Dielectric regions, e.g. EPIC dielectric isolation, LOCOS; Trench refilling techniques, SOI technology, use of channel stoppers using a local oxidation of silicon, e.g. LOCOS, SWAMI, SILO in a region being recessed from the surface, e.g. in a recess, groove, tub or trench region
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
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- H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
- H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
- H01L21/76—Making of isolation regions between components
- H01L21/764—Air gaps
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
- H01L29/06—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions
- H01L29/0603—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions
- H01L29/0642—Isolation within the component, i.e. internal isolation
- H01L29/0649—Dielectric regions, e.g. SiO2 regions, air gaps
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
- H01L29/66007—Multistep manufacturing processes
- H01L29/66075—Multistep manufacturing processes of devices having semiconductor bodies comprising group 14 or group 13/15 materials
- H01L29/66227—Multistep manufacturing processes of devices having semiconductor bodies comprising group 14 or group 13/15 materials the devices being controllable only by the electric current supplied or the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched, e.g. three-terminal devices
- H01L29/66409—Unipolar field-effect transistors
- H01L29/66477—Unipolar field-effect transistors with an insulated gate, i.e. MISFET
- H01L29/66825—Unipolar field-effect transistors with an insulated gate, i.e. MISFET with a floating gate
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
- H01L29/68—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by only the electric current supplied, or only the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched
- H01L29/76—Unipolar devices, e.g. field effect transistors
- H01L29/772—Field effect transistors
- H01L29/78—Field effect transistors with field effect produced by an insulated gate
- H01L29/788—Field effect transistors with field effect produced by an insulated gate with floating gate
Definitions
- the present invention relates to a semiconductor memory device and a method of manufacturing the same, and more particularly, to a semiconductor memory device including an air gap and a method of manufacturing the semiconductor memory device.
- a semiconductor memory device includes a plurality of memory cells for storing data and devices for various operations. High-density integration of the semiconductor memory device has been demanded for large capacity and light weight. Especially, areas of the memory cells occupied in a semiconductor chip is very wide, so that a decrease in sizes of and intervals between the memory cells has continuously become an issue.
- the memory cells are arranged in the unit of a string, a space between the strings, i.e. an isolation region, is filled with a device separation film formed of an insulating material.
- the device separation film serves to block an electrical influence, i.e. interference, between adjacent strings.
- An exemplary semiconductor memory device includes a semiconductor substrate in which isolation regions and active regions are defined, gate lines formed on the semiconductor substrate in a direction crossing the isolation regions, a capping layer configured to define air gaps positioned higher than an upper surface of the semiconductor substrate in the isolation regions.
- An exemplary semiconductor memory device includes a semiconductor substrate in which an isolation region and an active region are defined, a tunnel insulation layer, a floating gate, a capping layer, a dielectric layer, and a control gate formed over the semiconductor substrate of the active region, a trench formed in the semiconductor substrate of the isolation region, and an air gap formed inside the trench, where the capping layer defines an upper surface of the air gap and where the capping layer is positioned higher than a surface of the semiconductor substrate.
- a method of forming an exemplary semiconductor memory device includes forming a tunnel insulation layer and a floating gate on a semiconductor substrate of an active region, forming a trench in the semiconductor substrate of an isolation region, forming, in the trench, a sacrificial layer having an upper surface positioned higher than a surface of the semiconductor substrate, forming a capping layer over the sacrificial layer, and forming an air gap by removing the sacrificial layer without removing the capping layer.
- An exemplary semiconductor memory device includes a plurality of gate lines formed on a semiconductor substrate, and a plurality of capping layers formed between the gate lines, wherein the capping layers define a plurality of air gaps between the gate lines.
- a method of forming an exemplary semiconductor memory device includes forming a plurality of gate lines on a semiconductor substrate; alternately forming sacrificial layers and capping layers on the semiconductor substrate between the gate lines and forming a plurality of air, defined by the capping layers, between the gate lines by removing the sacrificial layers.
- the air gap is formed between the semiconductor memory devices, thereby suppressing interference between the semiconductor memory devices.
- the method of forming the air gap it is possible to form the air gap with a desired size at a desired position by using the sacrificial layer and the capping layer. Accordingly, a position at which interference is minimized is found through a simulation and the air gap is formed at a corresponding position, thereby improving reliability of the semiconductor memory device.
- the plurality of air gaps by is forming the plurality of capping layers between the gate lines. Accordingly, it is simultaneously possible to minimize interference between the gate lines by the plurality of air gaps and to prevent the gate lines from leaning by the plurality of capping layers.
- FIGS. 1A to 1H are cross-sectional views illustrating a method of manufacturing an exemplary semiconductor memory device
- FIGS. 2A to 2K are cross-sectional views illustrating a method of manufacturing an exemplary semiconductor memory
- FIG. 3 is a diagram illustrating a principle of removing an exemplary sacrificial layer
- FIG. 4 is an image a section of an exemplary semiconductor memory device including air gaps
- FIG. 5A is a graph illustrating interference between adjacent cells according to a height of a surface defining an upper portion of an air gap
- FIG. 5B is a graph illustrating interference between adjacent cells according to a height of a surface defining a lower portion of an air gap
- FIG. 5C is a graph illustrating interference between adjacent cells according to a width of an air gap
- FIGS. 6A and 6C are simulation diagrams illustrating interference according to a height of a surface defining an upper portion of an air gap
- FIGS. 7A to 7I are cross sectional views illustrating a method of manufacturing an exemplary semiconductor memory device.
- FIG. 8 is a cross sectional view illustrating a method manufacturing an exemplary semiconductor memory.
- FIGS. 1A to 1H are cross-sectional views illustrating an exemplary method of manufacturing a semiconductor memory device.
- a tunnel insulation layer 103 and a first conductive layer 105 for a floating gate are sequentially formed on a semiconductor substrate 101 , in which an active region and an isolation region are defined.
- the tunnel insulation layer 103 may be formed of an oxide layer
- the first conductive layer 105 may be formed of a polysilicon layer.
- the first conductive layer 105 may be formed of a doped polysilicon layer, in which an impurity has been injected, or may be formed by stacking undoped polysilicon layers, in which an impurity has not been injected.
- a trench 107 is formed by etching the first conductive layer 105 , the tunnel insulation layer 103 , and the semiconductor substrate 101 of the isolation region.
- the trench 107 may be formed by forming a mask pattern (not shown) in which the isolation region is opened on the first conductive layer 105 and sequentially etching the first conductive layer 105 , the tunnel insulation layer 103 , and the semiconductor substrate 101 exposed through the mask pattern (not shown).
- the mask pattern (not shown) may be removed after forming the trench 107 .
- a liner insulation layer 109 is formed over a top surface of surface of the first conductive layer 105 , as well as over a surface of the first conductive layer 105 and a surface of the semiconductor substrate 101 that defines the trench 107 .
- the liner insulation layer 109 minimizes damage to surfaces of the trench 107 during an etching process for forming the trench 107 .
- a sacrificial layer 111 is formed on the liner insulation layer 109 .
- the sacrificial layer 111 which will be removed in a subsequent process to forming an air gap, is formed of a flowable material.
- a carbon-based material (containing about 60% of carbon) may be used for the sacrificial layer 111 .
- the carbon-based material may easily be removed by plasma.
- the carbon-based material for the sacrificial layer 111 may be a Spin-On-Carbon (SOC) layer, a photoresist (PR) layer, or carbon layer for a hard mask.
- SOC Spin-On-Carbon
- PR photoresist
- the sacrificial layer 111 having a flowable property may be formed by a spin coating method.
- a solidification process for transforming the flowable sacrificial layer into a solid is performed.
- the solidification process may be performed by a heat treatment process.
- the first conductive layer 105 is exposed through the etching process. Specifically, the first conductive layer 105 is exposed by etching the sacrificial layer 111 and the liner insulation layer 109 using an etch-back process. When the first conductive layer 105 is exposed, an additional etching process is performed so that a surface of the sacrificial layer 111 becomes lower than that of the first conductive layer 105 .
- Interference between adjacent memory cells and strings is differentiated according to a difference of the height of the remaining sacrificial layer 111 (which defines the air gap) and the height of the semiconductor substrate 101 .
- Testing indicates that for an exemplary semiconductor memory device, the height difference 1Ha should be about 50 ⁇ to about 150 ⁇ . However, the height difference 1Ha may be appropriately changed according to the specific semiconductor memory device.
- a capping layer 113 is formed over the remaining sacrificial layer 111 and the first conductive layer 105 .
- the capping layer 113 is formed of a non-porous material, such as silicon dioxide (SiO 2 ), silicon nitride (SiN), silicon oxynitride (SiON), or silicon carbon nitride (SiCN).
- the capping layer 113 may be formed by an atomic-layer deposition (ALD) method at a low temperature (about 50° C. to about 100° C.) to prevent the sacrificial layer 111 from being damaged or removed.
- ALD atomic-layer deposition
- the capping layer 113 must be formed at a temperature lower than about 300° C.
- the capping layer 113 When the capping layer 113 is formed by the ALD method, step coverage may be improved and it is easy to form the capping layer 113 with a uniform thickness.
- a thickness of the capping layer 113 may be adjusted based on the specific memory device. In order to easily remove the sacrificial layer 111 (during a subsequent removal process), the capping layer 113 may have a thickness of about 5 ⁇ to about 50 ⁇ .
- the sacrificial layer 111 (reference number 111 of FIG. 1D ) under the capping layer 113 is removed by using plasma.
- plasma is generated inside a chamber in which the semiconductor substrate 101 is loaded.
- oxygen, nitrogen, or hydrogen plasma may be generated.
- oxygen plasma is generated will be described as an example.
- FIG. 3 is a diagram illustrating a principle of removing the sacrificial layer in the present invention.
- oxygen radicals are generated and the oxygen radicals pass through the capping layer 113 to reach the sacrificial layer under the capping layer 113 .
- the oxygen radicals and the carbon within the sacrificial layer react each other so that the sacrificial layer 111 is changed into CO 2 or Co radical, and the CO 2 or Co radical passes through the capping layer 111 to be discharged to the outside.
- the sacrificial layer 111 under the capping layer 113 may be removed, and a space in which the sacrificial layer 111 is removed becomes the air gap.
- the air gap has the same height as that of the sacrificial layer, it is possible to freely adjust the height difference 1Ha between the upper portion of the air gap and the upper portion of the semiconductor substrate 101 by adjusting the height of the sacrificial layer in FIG. 1C .
- a first insulation layer 115 is formed on the capping layer 113 in order to supplement is the thickness of the capping layer 113 .
- the first insulation layer 115 is formed of an oxide layer, and is formed, for example, of a flowable material, such as polisilazane (PSZ).
- PSZ polisilazane
- the PSZ layer is a flowable material so that a void is not generated between the first conductive layers 105 . After the PSZ layer is formed, the PSZ layer is solidified by performing a heat treatment process.
- the first insulation layer 115 is etched so that a portion of the first insulation layer 115 is remains on the capping layer 113 in the isolation region.
- a process of etching the first insulation layer 115 is performed so that a thickness 2Ha of the first insulation layer 115 left in the isolation region and the capping layer 113 is enough to support the upper portion of the air gap.
- a dielectric layer 117 is formed over the capping layer and the portion of the first insulation layer 115 . Then a second conductive layer 119 for a control gate is formed on the dielectric layer 117 .
- the dielectric layer 117 may be formed by sequentially stacking an oxide layer, a nitride layer, and an oxide layer. Alternatively, the dielectric layer 117 may be formed in a single layer made of a high dielectric material.
- the second conductive layer 119 is formed as a polysilicon layer, for example, a doped polysilicon layer.
- each of the gate lines may include the tunnel insulation layer 103 , the first conductive layer 105 , the capping layer 113 , the dielectric layer 117 , and the second conductive layer 119 stacked on the semiconductor substrate.
- FIGS. 2A to 2K are cross-sectional views illustrating a method of manufacturing an exemplary semiconductor memory device.
- a tunnel insulation layer 203 and a first conductive layer 205 for a floating gate are sequentially formed on a semiconductor substrate 201 , in which an active region and an isolation region are defined.
- the tunnel insulation layer 203 may be formed of an oxide layer
- the first conductive layer 205 may be formed of a polysilicon layer.
- the first conductive layer 205 may be formed of a doped polysilicon layer in which an impurity has been injected.
- the first conductive layer 205 may be formed by stacking undoped polysilicon layers, in which impurity has not been injected.
- a trench 207 is formed by etching the first conductive layer 205 , the tunnel insulation layer 203 , and the semiconductor substrate 201 of the isolation region.
- the trench 207 may be formed by forming a mask pattern (not shown) in which the isolation region is opened on the first conductive layer 205 and sequentially etching the first conductive layer 205 , the tunnel insulation layer 203 , and the semiconductor substrate 201 exposed through the mask pattern (not shown).
- the mask pattern (not shown) may be removed after forming the trench 207 .
- a liner insulation layer 209 is formed over a top surface of surface of the first conductive layer 205 , as well as over a surface the first conductive layer 205 and a surface of the semiconductor substrate 101 that defines the trench 207 .
- the liner insulation layer 209 minimizes damage generated to the surfaces of the trench 207 during an etching process for forming the trench 207 .
- a lower insulation layer 211 is formed on the liner insulation layer 209 .
- the lower insulation layer 211 which will be removed in a subsequent process to forming an air gap, is formed of a flowable material.
- the lower insulation layer 211 is formed of an oxide layer, such as a flowable PSZ layer, with which inside the trench 207 is filled. After the PSZ layer is formed, the PSZ layer is solidified by performing a heat treatment process.
- the first conductive layer 205 is exposed through an etching process. Specifically, the first conductive layer 205 is exposed by etching the lower insulation layer 211 and the liner insulation layer 209 using an etch-back process. When the first conductive layer 205 is exposed, an additional etching process is performed so that an upper surface of the lower insulation layer 211 becomes lower than that of the first conductive layer 205 . The etching process is performed with an etchant having an etching selectivity that is substantially the same for the lower insulation layer 211 and the liner insulation layer 209 .
- a height difference 1Hb between the upper surface of the remaining lower insulation layer 211 and a surface of the semiconductor substrate 201 , because the upper surface of the remaining lower insulation layer 211 become defines an upper portion of the air gap (which will be subsequently formed). Interference between adjacent memory cells and strings is differentiated according to a difference of the height of the remaining sacrificial layer 111 (which defines the air gap) and the height of the semiconductor substrate 201 . Testing indicates that for an exemplary semiconductor memory device, the height difference 1Hb should be about 50 ⁇ to about 150 ⁇ . However, the height difference 1Hb may be appropriately changed according to the specific semiconductor memory device.
- the lower insulation layer 211 partially etched in order to adjust a height of a surface of the lower insulation layer 211 that will define a lower portion of the air gap (which will be subsequently formed). That is, the etching process is performed so as to adjust a height difference 2Hb between the upper surface of the semiconductor substrate 201 and the upper surface of the remaining lower insulation layer 211 .
- the height difference 2Hb should be about 100 ⁇ to about 400 ⁇ . However, the height difference 2Hb may be appropriately changed according to the specific semiconductor memory device.
- the etching process is performed with an etchant having a greater etching selectivity for the lower insulation layer 211 than for the liner insulation layer 209 . That is, an etching speed of the lower insulation layer 211 is faster than an etching speed of the liner insulation layer.
- a sacrificial layer 213 is formed on the first conductive layer 205 , the lower insulation layer 211 , and the liner insulation layer 209 .
- the sacrificial layer 213 (which will be removed in a subsequent process to form the air gap) a flowable material.
- a carbon-based material (containing about 60% carbon) may be used for the sacrificial layer 213 .
- the carbon-based material may easily be removed by plasma.
- the carbon-based material for the sacrificial layer 213 may be a Spin-On-Carbon (SOC) layer, a photoresist (PR) layer, or a carbon layer for a hard mask.
- SOC Spin-On-Carbon
- PR photoresist
- the sacrificial layer 213 having a flowable property may is be formed by a spin coating method.
- a solidification process for transforming the flowable sacrificial layer 213 into a solid is performed after forming the sacrificial layer 213 .
- the solidification process may be performed by a heat treatment process.
- the first conductive layer 205 is exposed by performing an etching process.
- an additional etching process is performed so that an upper surface of the sacrificial layer 213 becomes lower than a surface of the first conductive layer 205 .
- the height of the upper surface of the sacrificial layer 213 may be adjusted so as to be the same as that of the upper surface of the liner insulation layer 209 , or the height difference between the semiconductor substrate 201 and the upper portion of the sacrificial layer 213 may be adjusted to be the aforementioned height 1Hb.
- a capping layer 215 is formed over the remaining sacrificial layer 213 and the first conductive layer 205 .
- the capping layer 215 is formed of a non-porous material, such as SiO 2 , SiN, SiON, or SiCN.
- the capping layer 215 may be formed by an atomic-layer deposition (ALD) method at a low temperature (about 50° C. to about 100° C.) to prevent the sacrificial layer 213 from being damaged or removed.
- ALD atomic-layer deposition
- a thickness of the capping layer 215 may be adjusted based on the specific memory device. In order to easily remove the sacrificial layer 213 (during a subsequent removal process) the capping layer 215 may have a thickness of about 5 ⁇ to about 50 ⁇ .
- the sacrificial layer 213 (reference number 213 of FIG. 2G ) under the capping layer 215 is removed by using plasma.
- plasma is generated inside a chamber in which the semiconductor substrate 201 is loaded.
- oxygen, nitrogen, or hydrogen plasma may be generated.
- oxygen plasma is generated will be described as an example.
- FIG. 3 is a diagram illustrating a principle of removing the sacrificial layer in the present invention.
- oxygen radicals are generated and the oxygen radicals pass through the capping layer 215 to reach the sacrificial layer 213 under the capping layer 215 . Then, the oxygen radicals and the carbon within the sacrificial layer 213 react each other so that the sacrificial layer 213 is changed into CO 2 or Co radical, and the CO 2 or Co radical passes through the capping layer 215 again to be discharged to the outside.
- the sacrificial layer 213 under the capping layer 215 may be removed, and a space in which the sacrificial layer 213 is removed becomes the air gap.
- the air gap has the same height as that of the sacrificial layer 213 , it is possible to freely adjust the height between the upper portion of the air gap and the upper portion of the semiconductor substrate 201 by adjusting the height of the sacrificial layer 213 in FIG. 2F .
- a first insulation layer 217 is formed on the capping layer 215 in order to supplement the thickness of the capping layer 215 .
- the first insulation layer 217 is formed of an oxide layer, and is formed, for example, of a flowable PSZ layer. After the PSZ layer is formed, the PSZ layer is solidified by performing a heat treatment process.
- the first insulation layer 217 is etched so that a portion of the first insulation layer 217 remains on the capping layer 215 in the isolation region.
- a process of etching the first insulation layer 217 is performed so that a thickness 3Hb of the first insulation layer 217 left in the isolation region and the capping layer 215 is enough to support the upper portion of the air gap.
- a dielectric layer 219 is formed over the capping layer 215 and the portion of the first insulation layer 217 . Then a second conductive layer 221 for a control gate is formed on the dielectric layer 219 .
- the dielectric layer 219 may be formed by sequentially stacking an oxide layer, a nitride layer, and an oxide layer. Alternatively, the dielectric layer 219 may be formed in a single layer made of a high dielectric material.
- the second conductive layer 221 is formed as a polysilicon layer, for example, a doped polysilicon layer.
- gate lines are arranged in a direction crossing the isolation region are formed by performing a patterning process. That each of the gate lines may include the tunnel insulation layer 203 , the first conductive layer 205 , the capping layer 215 , the dielectric layer 219 , and the second conductive layer 221 stacked on the semiconductor substrate.
- FIG. 4 is a picture of a section of a semiconductor memory device including air gaps according to the present invention.
- the air gap is formed inside the isolation region and the height of the air gap is higher than the semiconductor substrate.
- FIG. 5A is a graph illustrating interference between adjacent cells according to a height of the surface defining the upper portion of the air gap.
- FIG. 5B is a graph illustrating interference between adjacent cells according to a height of a surface defining the lower portion of the air gap.
- FIG. 5C is a graph illustrating interference between adjacent cells according to a width of the air gap.
- an X-axis (height) of the graph represents a height difference between the surface defining the upper portion of the air gap and the upper surface of the semiconductor substrate and a Y-axis represents interference.
- a decrease in interference is not remarkable when the height of the surface defining the upper portion of the air gap is lower than the upper surface of the semiconductor substrate (a minus section in the X-axis), but the interference is considerably decreased from a section in which the surface defining the upper portion of the air gap is higher than the upper surface of the semiconductor substrate (a plus section in the X-axis).
- the interference is considerably decreased when the surface defining the upper portion of the air gap is higher than the upper surface of the semiconductor substrate by about 50 ⁇ to about 150 ⁇ .
- an X-axis (height) of the graph represents a height difference between the surface defining the lower portion of the air gap and the upper surface of the semiconductor substrate and a Y-axis represents interference.
- ⁇ 200 ⁇ in the X-axis means that the surface defining the lower portion of the air gap is lower than the upper portion of the semiconductor substrate by 200 ⁇ .
- the interference is decreased as the surface defining the lower portion of the air gap becomes lower than the upper surface of the semiconductor substrate.
- a quantity of an interference change is about 150 my to 130 mV.
- a height difference between the surface defining the lower portion of the air gap and the upper surface of the semiconductor substrate less exerts influence on the interference than a height difference between the surface defining the upper surface of the air gap and the upper surface of the semiconductor substrate.
- an X-axis (height) of the graph represents a ratio (%) of a width of the air gap to a width (trench) of the isolation region and a Y-axis represents interference.
- the interference is decreased.
- the height and the width of the surface defining the upper portion of the air gap exert a large influence on the interference between the memory cells, as compared to the height of the surface defining the lower portion of the air gap.
- the interference between the memory cells may be minimized when the surface defining the upper portion of the air gap is higher than the upper surface of the semiconductor substrate by about 50 ⁇ to about 100 ⁇ , and the width of the air gap is dose to the width of the trench.
- this value is an example obtained as the result of the test.
- a position and a width at which the interference is minimized may be adjusted by appropriately adjusting the position and the width according to the requirements of a specific memory device.
- the height of the sacrificial layer (which defines the upper portion of the air gap) may be adjusted via the processes of the manufacturing the semiconductor memory device. (See e.g., FIGS. 1C and 2F ).
- the width of the sacrificial layer may be adjusted (see FIGS. 1E and 2H ) via the processes of the manufacturing the semiconductor memory device, so that the width of the air gap is close to the width of the trench.
- FIGS. 6A and 6C are simulation diagrams illustrating interference according to a height of the surface defining the upper portion of the air gap.
- FIG. 6A shows interference in a memory device having no air gap.
- FIG. 6B shows interference in a memory device, where a surface defining an upper portion of an air gap is lower than an upper surface of a semiconductor substrate.
- FIG. 6C shows interference in an exemplary memory device, where a surface defining an upper portion of an is higher an upper surface of the semiconductor substrate.
- FIG. 6 darker shading means that a region has more interference than a region with lighter shading. Accordingly, in FIG. 6A , the region affected by interference Ea is wider than the cases shown in FIG. 68 or 6 C that of case B or case C, so it can be seen that interference to an adjacent cell is high. In FIG. 6B , it can be seen that interference Eb is decreased compared to the case in which the memory device has no air gap, shown in FIG. 6A . In FIG. 6C , it can be seen that interference Ec is decreased compared to FIG. 6B in which the upper surface of the air gap is lower than the upper surface of the semiconductor substrate.
- the interference may be effectively decreased as the upper surface of the air gap is higher than the is semiconductor substrate in the active region and is close to the width of the isolation region.
- FIGS. 7A to 7I are cross sectional views illustrating a method of manufacturing an exemplary semiconductor memory device.
- a plurality of gate lines GL is formed on a semiconductor substrate 701 .
- each of the plurality of gate lines GL may be formed in a structure in which a tunnel insulation layer 703 , a floating gate 705 , a dielectric layer 707 , and a control gate 709 are stacked.
- a structure of the plurality of gate lines GL illustrated in the drawing may be variously changed according to specific requirements of a semiconductor memory device.
- a first sacrificial layer 711 having a first thickness, is formed on the semiconductor substrate 701 between each of the plurality of gate lines GL. Specifically, the first sacrificial layer 711 is formed on an entire structure including the gate lines GL, and the first sacrificial layer 711 is formed so as to cover all of upper portions of the gate lines GL so that spaces between the gate lines GL are sufficiently filled with the first sacrificial layer 711 .
- a flowable carbon-based material (containing about 60% of carbon) is used as the sacrificial layer 711 . The carbon-based material may easily be removed by plasma.
- the sacrificial layer 711 may be a Spin-On-Carbon (SOC) layer or a photoresist (PR) layer.
- the sacrificial layer 711 may be formed by a spin coating method.
- a solidification process for transforming the flowable first sacrificial layer 711 into a solid is performed after forming the first sacrificial layer 711 .
- the solidification process may be performed by a heat treatment process.
- the first sacrificial layer 711 is etched to the first thickness (which defines an upper portion of an air gap that will be subsequently formed).
- a first capping layer 713 is formed on a surface of the floating gate 705 , the dielectric layer 707 , the control gate 709 , and the first sacrificial layer 711 .
- the first capping layer 713 is formed of a non-porous material, such as SiO 2 , SiN, SiON, or SiCN.
- the first capping layer 713 is formed by an ALD method at a low temperature (about 50° C. to about 100° C.) so as to prevent the first sacrificial layer 711 from being damaged or partially removed.
- the first capping layer 713 When the first capping layer 713 is formed by the ALD method, step coverage may be improved and it is easy to form the first capping layer 713 with a uniform thickness.
- a thickness of the first capping layer 713 may be adjusted according to the requirements of a specific memory device. In order to easily remove the first sacrificial layer 711 in a subsequent process, the first capping layer 713 may have a thickness of about 5 ⁇ to about 50 ⁇ .
- the first sacrificial layer (reference number 711 of FIG. 7C ) under the first capping layer 713 is removed by using plasma.
- plasma is generated inside a chamber in which the semiconductor substrate 701 is loaded.
- oxygen, nitrogen, or hydrogen plasma may be generated.
- the first sacrificial layer 711 passes through the first capping layer 713 to exit to the outside, as described above with reference to FIG. 3 .
- a space from which the first sacrificial layer 711 is removed becomes a first air gap.
- a second sacrificial layer + 715 is formed on a portion of the first capping layer 713 that covers the first air gap.
- the second sacrificial layer 715 may be formed of the same material, and by the same method, as was used to form the first sacrificial layer 711 , described above with reference to FIG. 7B .
- a second capping layer 717 is formed over a surface of the second sacrificial layer 715 and the first capping layer 713 .
- the second capping layer 717 is formed of a non-porous material, such as SiO 2 , SiN, SiON, or SiCN.
- the second capping layer 717 may be formed by an ALD method at a low temperature (about 50° C. to about 100° C.).
- a thickness of the second capping layer 715 may be adjusted according to the requirements of a specific memory device.
- the second capping layer 715 may have a thickness of about 5 ⁇ to about 50 ⁇ .
- the second sacrificial layer (reference number 715 of FIG. 7E ) under the second capping layer 717 is removed by using plasma.
- plasma may be generated inside a chamber in which the semiconductor substrate 701 is loaded.
- oxygen, nitrogen, or hydrogen plasma may be generated.
- the second sacrificial layer 715 passes through the second capping layer 717 to exit to the outside, as described above with reference to FIG. 3 .
- a space from which the second sacrificial layer 715 is removed becomes a second air gap.
- the second air gap is formed on the second capping layer 717 and has a width that is narrower than a width of the first air gap.
- a third sacrificial layer 719 is formed on a portion of the second capping layer 717 that covers the second air gap.
- the third sacrificial layer 719 may be formed of the same material as that of the first sacrificial layer 711 and the second sacrificial layer 715 .
- the third sacrificial layer 719 is formed so that an upper surface of the third sacrificial layer 719 is substantially coplanar with an upper surface of the second capping layer 717 formed on the gate lines GL.
- the third sacrificial layer 719 may be formed of the same material, and by the same method, as was used to form the first sacrificial layer 711 or the second sacrificial layer 715 .
- a third capping layer 721 is formed on the third sacrificial layer 719 and the second capping layer 717 .
- the third capping layer 721 is formed of a non-porous material, such as SiO 2 , SiN, SiON, or SiCN.
- the third capping layer 721 may be formed using the same method as used to form the first capping layer 713 or the second capping layer 717 .
- the third sacrificial layer (reference number 719 of FIG. 7G ) under the third capping layer 721 is removed by using plasma.
- plasma may be generated inside a chamber in which the semiconductor substrate 701 is loaded.
- oxygen, nitrogen, or hydrogen plasma may be generated.
- the third sacrificial layer 719 passes through the third capping layer 721 to exit to the outside, as described above with reference to FIG. 3 .
- a space from which the third sacrificial layer 719 is removed becomes a third air gap.
- the third air gap is formed on the second capping layer 717 and has a width that is narrower than a width of the second air gap.
- an interlayer insulation layer 723 is formed on the third capping layer 721 , and then a subsequent process performed.
- the first to third capping layers 713 , 715 , and 721 serve as supports between the gate lines GL. That is, if the first to third capping layers 713 , 715 , and 721 where to be removed, so that only a single air gap remained, then the gate lines GL may lean in a side direction. Accordingly, it is simultaneously possible to suppress interference between the gate lines GL and prevent the gate lines GL from leaning.
- FIGS. 7A to 7I show three air gaps are formed between the gate lines GL, but, as shown in FIG. 8 , any number (n) of air gaps may be formed between the gate lines GL.
- Reference numeral 801 in FIG. 8 denotes a semiconductor substrate, and CA 1 to CAn indicate first to n th capping layers. As illustrated in FIGS. 7I and 8 , it is possible to prevent the gate lines GL from leaning and more effectively suppress interference between the gate lines GL, by forming the air gaps to be higher than the upper surfaces of the gate lines GL.
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Abstract
The present disclosure relates to a semiconductor memory, device and a method of forming a semiconductor memory device. The semiconductor memory device includes a semiconductor substrate in which isolation regions and active regions are defined, gate lines formed on the semiconductor substrate in a direction crossing the isolation regions, a capping layer configured to define air gaps positioned higher than an upper surface of the semiconductor substrate in the isolation regions.
Description
- This application is based on and claims priority from Korean Patent Application No. 10-2012-0086915 filed on Aug. 8, 2012, with the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
- 1. Field
- The present invention relates to a semiconductor memory device and a method of manufacturing the same, and more particularly, to a semiconductor memory device including an air gap and a method of manufacturing the semiconductor memory device.
- 2. Discussion of Related Art
- A semiconductor memory device includes a plurality of memory cells for storing data and devices for various operations. High-density integration of the semiconductor memory device has been demanded for large capacity and light weight. Especially, areas of the memory cells occupied in a semiconductor chip is very wide, so that a decrease in sizes of and intervals between the memory cells has continuously become an issue.
- In a NAND flash memory device, the memory cells are arranged in the unit of a string, a space between the strings, i.e. an isolation region, is filled with a device separation film formed of an insulating material. The device separation film serves to block an electrical influence, i.e. interference, between adjacent strings.
- However, as the integration of the semiconductor memory devices is increased, there is a limit in blocking the interference between the strings by the device separation film formed of the insulating material, so that reliability of the semiconductor memory device may deteriorate.
- The present invention has been made in an effort to provide a semiconductor memory device capable of suppressing interference between the semiconductor memory devices and a method of is manufacturing the semiconductor memory device. An exemplary semiconductor memory device, includes a semiconductor substrate in which isolation regions and active regions are defined, gate lines formed on the semiconductor substrate in a direction crossing the isolation regions, a capping layer configured to define air gaps positioned higher than an upper surface of the semiconductor substrate in the isolation regions. An exemplary semiconductor memory device includes a semiconductor substrate in which an isolation region and an active region are defined, a tunnel insulation layer, a floating gate, a capping layer, a dielectric layer, and a control gate formed over the semiconductor substrate of the active region, a trench formed in the semiconductor substrate of the isolation region, and an air gap formed inside the trench, where the capping layer defines an upper surface of the air gap and where the capping layer is positioned higher than a surface of the semiconductor substrate.
- A method of forming an exemplary semiconductor memory device includes forming a tunnel insulation layer and a floating gate on a semiconductor substrate of an active region, forming a trench in the semiconductor substrate of an isolation region, forming, in the trench, a sacrificial layer having an upper surface positioned higher than a surface of the semiconductor substrate, forming a capping layer over the sacrificial layer, and forming an air gap by removing the sacrificial layer without removing the capping layer.
- An exemplary semiconductor memory device includes a plurality of gate lines formed on a semiconductor substrate, and a plurality of capping layers formed between the gate lines, wherein the capping layers define a plurality of air gaps between the gate lines.
- A method of forming an exemplary semiconductor memory device includes forming a plurality of gate lines on a semiconductor substrate; alternately forming sacrificial layers and capping layers on the semiconductor substrate between the gate lines and forming a plurality of air, defined by the capping layers, between the gate lines by removing the sacrificial layers.
- According to the embodiment of the present invention, the air gap is formed between the semiconductor memory devices, thereby suppressing interference between the semiconductor memory devices.
- Further, in the method of forming the air gap, it is possible to form the air gap with a desired size at a desired position by using the sacrificial layer and the capping layer. Accordingly, a position at which interference is minimized is found through a simulation and the air gap is formed at a corresponding position, thereby improving reliability of the semiconductor memory device.
- Further, it is possible to form the plurality of air gaps by is forming the plurality of capping layers between the gate lines. Accordingly, it is simultaneously possible to minimize interference between the gate lines by the plurality of air gaps and to prevent the gate lines from leaning by the plurality of capping layers.
- The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects and features described above, further aspects and features will become apparent by reference to the drawings and the following detailed description.
- The above and other features and advantages of the present invention will become more apparent to those of ordinary skill in the art by describing in detail embodiments thereof with reference to the attached drawings in which:
-
FIGS. 1A to 1H are cross-sectional views illustrating a method of manufacturing an exemplary semiconductor memory device; -
FIGS. 2A to 2K are cross-sectional views illustrating a method of manufacturing an exemplary semiconductor memory; -
FIG. 3 is a diagram illustrating a principle of removing an exemplary sacrificial layer; -
FIG. 4 is an image a section of an exemplary semiconductor memory device including air gaps; -
FIG. 5A is a graph illustrating interference between adjacent cells according to a height of a surface defining an upper portion of an air gap; -
FIG. 5B is a graph illustrating interference between adjacent cells according to a height of a surface defining a lower portion of an air gap; -
FIG. 5C is a graph illustrating interference between adjacent cells according to a width of an air gap; -
FIGS. 6A and 6C are simulation diagrams illustrating interference according to a height of a surface defining an upper portion of an air gap; -
FIGS. 7A to 7I are cross sectional views illustrating a method of manufacturing an exemplary semiconductor memory device; and -
FIG. 8 is a cross sectional view illustrating a method manufacturing an exemplary semiconductor memory. - Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings in detail. However, the present invention is not limited to an embodiment disclosed below and may be implemented in various forms and the scope of the present invention is not limited to the following embodiments. Rather, the embodiment is provided to more sincerely and fully disclose the present invention and to completely transfer the spirit of the present invention to those skilled in the art to which the present invention pertains, and the scope of the present invention should be understood by the claims of the present invention.
-
FIGS. 1A to 1H are cross-sectional views illustrating an exemplary method of manufacturing a semiconductor memory device. - Referring to
FIG. 1A , atunnel insulation layer 103 and a firstconductive layer 105 for a floating gate are sequentially formed on asemiconductor substrate 101, in which an active region and an isolation region are defined. Thetunnel insulation layer 103 may be formed of an oxide layer, and the firstconductive layer 105 may be formed of a polysilicon layer. For example, the firstconductive layer 105 may be formed of a doped polysilicon layer, in which an impurity has been injected, or may be formed by stacking undoped polysilicon layers, in which an impurity has not been injected. - A
trench 107 is formed by etching the firstconductive layer 105, thetunnel insulation layer 103, and thesemiconductor substrate 101 of the isolation region. For example, although it is not illustrated in the drawing, thetrench 107 may be formed by forming a mask pattern (not shown) in which the isolation region is opened on the firstconductive layer 105 and sequentially etching the firstconductive layer 105, thetunnel insulation layer 103, and thesemiconductor substrate 101 exposed through the mask pattern (not shown). The mask pattern (not shown) may be removed after forming thetrench 107. - Referring to
FIG. 1B , aliner insulation layer 109 is formed over a top surface of surface of the firstconductive layer 105, as well as over a surface of the firstconductive layer 105 and a surface of thesemiconductor substrate 101 that defines thetrench 107. Theliner insulation layer 109 minimizes damage to surfaces of thetrench 107 during an etching process for forming thetrench 107. Next, asacrificial layer 111 is formed on theliner insulation layer 109. Thesacrificial layer 111, which will be removed in a subsequent process to forming an air gap, is formed of a flowable material. For example, a carbon-based material (containing about 60% of carbon) may be used for thesacrificial layer 111. The carbon-based material may easily be removed by plasma. For example, the carbon-based material for thesacrificial layer 111 may be a Spin-On-Carbon (SOC) layer, a photoresist (PR) layer, or carbon layer for a hard mask. Thesacrificial layer 111 having a flowable property may be formed by a spin coating method. Next, a solidification process for transforming the flowable sacrificial layer into a solid is performed. The solidification process may be performed by a heat treatment process. - Referring to
FIG. 1C , the firstconductive layer 105 is exposed through the etching process. Specifically, the firstconductive layer 105 is exposed by etching thesacrificial layer 111 and theliner insulation layer 109 using an etch-back process. When the firstconductive layer 105 is exposed, an additional etching process is performed so that a surface of thesacrificial layer 111 becomes lower than that of the firstconductive layer 105. Here, it is very important to adjust a height difference 1Ha between a surface of the remainingsacrificial layer 111 and an upper surface of thesemiconductor substrate 101, because the surface of the remainingsacrificial layer 111 becomes a surface defining an upper portion of the air gap (which will be subsequently formed). Interference between adjacent memory cells and strings is differentiated according to a difference of the height of the remaining sacrificial layer 111 (which defines the air gap) and the height of thesemiconductor substrate 101. Testing indicates that for an exemplary semiconductor memory device, the height difference 1Ha should be about 50 Å to about 150 Å. However, the height difference 1Ha may be appropriately changed according to the specific semiconductor memory device. - Referring to
FIG. 1D , after the height of thesacrificial layer 111 is adjusted, acapping layer 113 is formed over the remainingsacrificial layer 111 and the firstconductive layer 105. Thecapping layer 113 is formed of a non-porous material, such as silicon dioxide (SiO2), silicon nitride (SiN), silicon oxynitride (SiON), or silicon carbon nitride (SiCN). Thecapping layer 113 may be formed by an atomic-layer deposition (ALD) method at a low temperature (about 50° C. to about 100° C.) to prevent thesacrificial layer 111 from being damaged or removed. For example, since the carbon-basedsacrificial layer 111 may be damaged at a temperature of about 300° C. to about 400° C., thecapping layer 113 must be formed at a temperature lower than about 300° C. - When the
capping layer 113 is formed by the ALD method, step coverage may be improved and it is easy to form thecapping layer 113 with a uniform thickness. A thickness of thecapping layer 113 may be adjusted based on the specific memory device. In order to easily remove the sacrificial layer 111 (during a subsequent removal process), thecapping layer 113 may have a thickness of about 5 Å to about 50 Å. - Referring to
FIG. 1E , the sacrificial layer 111 (reference number 111 ofFIG. 1D ) under thecapping layer 113 is removed by using plasma. Specifically, plasma is generated inside a chamber in which thesemiconductor substrate 101 is loaded. For example, oxygen, nitrogen, or hydrogen plasma may be generated. Here, a case in which oxygen plasma is generated will be described as an example. -
FIG. 3 is a diagram illustrating a principle of removing the sacrificial layer in the present invention. - Referring to
FIG. 3 , when oxygen plasma is generated, oxygen radicals are generated and the oxygen radicals pass through thecapping layer 113 to reach the sacrificial layer under thecapping layer 113. Then, the oxygen radicals and the carbon within the sacrificial layer react each other so that thesacrificial layer 111 is changed into CO2 or Co radical, and the CO2 or Co radical passes through thecapping layer 111 to be discharged to the outside. Through the aforementioned process, thesacrificial layer 111 under thecapping layer 113 may be removed, and a space in which thesacrificial layer 111 is removed becomes the air gap. Since the air gap has the same height as that of the sacrificial layer, it is possible to freely adjust the height difference 1Ha between the upper portion of the air gap and the upper portion of thesemiconductor substrate 101 by adjusting the height of the sacrificial layer inFIG. 1C . - Referring to
FIG. 1F , because the thickness of thecapping layer 113 on the upper portion of the air gap is thin, afirst insulation layer 115 is formed on thecapping layer 113 in order to supplement is the thickness of thecapping layer 113. Thefirst insulation layer 115 is formed of an oxide layer, and is formed, for example, of a flowable material, such as polisilazane (PSZ). The PSZ layer is a flowable material so that a void is not generated between the firstconductive layers 105. After the PSZ layer is formed, the PSZ layer is solidified by performing a heat treatment process. - Referring to
FIG. 1G , thefirst insulation layer 115 is etched so that a portion of thefirst insulation layer 115 is remains on thecapping layer 113 in the isolation region. A process of etching thefirst insulation layer 115 is performed so that a thickness 2Ha of thefirst insulation layer 115 left in the isolation region and thecapping layer 113 is enough to support the upper portion of the air gap. - Referring to
FIG. 1H , adielectric layer 117 is formed over the capping layer and the portion of thefirst insulation layer 115. Then a secondconductive layer 119 for a control gate is formed on thedielectric layer 117. For example, thedielectric layer 117 may be formed by sequentially stacking an oxide layer, a nitride layer, and an oxide layer. Alternatively, thedielectric layer 117 may be formed in a single layer made of a high dielectric material. The secondconductive layer 119 is formed as a polysilicon layer, for example, a doped polysilicon layer. - Next, gate lines are arranged in a direction crossing the isolation region by performing a patterning process. That is, each of the gate lines may include the
tunnel insulation layer 103, the firstconductive layer 105, thecapping layer 113, thedielectric layer 117, and the secondconductive layer 119 stacked on the semiconductor substrate. -
FIGS. 2A to 2K are cross-sectional views illustrating a method of manufacturing an exemplary semiconductor memory device. - Referring to
FIG. 2A , atunnel insulation layer 203 and a firstconductive layer 205 for a floating gate are sequentially formed on asemiconductor substrate 201, in which an active region and an isolation region are defined. Thetunnel insulation layer 203 may be formed of an oxide layer, and the firstconductive layer 205 may be formed of a polysilicon layer. For example, the firstconductive layer 205 may be formed of a doped polysilicon layer in which an impurity has been injected. Alternatively, the firstconductive layer 205 may be formed by stacking undoped polysilicon layers, in which impurity has not been injected. - A
trench 207 is formed by etching the firstconductive layer 205, thetunnel insulation layer 203, and thesemiconductor substrate 201 of the isolation region. For example, although it is not illustrated in the drawing, thetrench 207 may be formed by forming a mask pattern (not shown) in which the isolation region is opened on the firstconductive layer 205 and sequentially etching the firstconductive layer 205, thetunnel insulation layer 203, and thesemiconductor substrate 201 exposed through the mask pattern (not shown). The mask pattern (not shown) may be removed after forming thetrench 207. - Referring to
FIG. 2B , aliner insulation layer 209 is formed over a top surface of surface of the firstconductive layer 205, as well as over a surface the firstconductive layer 205 and a surface of thesemiconductor substrate 101 that defines thetrench 207. Theliner insulation layer 209 minimizes damage generated to the surfaces of thetrench 207 during an etching process for forming thetrench 207. Next, alower insulation layer 211 is formed on theliner insulation layer 209. Thelower insulation layer 211, which will be removed in a subsequent process to forming an air gap, is formed of a flowable material. Thelower insulation layer 211 is formed of an oxide layer, such as a flowable PSZ layer, with which inside thetrench 207 is filled. After the PSZ layer is formed, the PSZ layer is solidified by performing a heat treatment process. - Referring to
FIG. 2C , the firstconductive layer 205 is exposed through an etching process. Specifically, the firstconductive layer 205 is exposed by etching thelower insulation layer 211 and theliner insulation layer 209 using an etch-back process. When the firstconductive layer 205 is exposed, an additional etching process is performed so that an upper surface of thelower insulation layer 211 becomes lower than that of the firstconductive layer 205. The etching process is performed with an etchant having an etching selectivity that is substantially the same for thelower insulation layer 211 and theliner insulation layer 209. Here, it is very important to adjust a height difference 1Hb between the upper surface of the remaininglower insulation layer 211 and a surface of thesemiconductor substrate 201, because the upper surface of the remaininglower insulation layer 211 become defines an upper portion of the air gap (which will be subsequently formed). Interference between adjacent memory cells and strings is differentiated according to a difference of the height of the remaining sacrificial layer 111 (which defines the air gap) and the height of thesemiconductor substrate 201. Testing indicates that for an exemplary semiconductor memory device, the height difference 1Hb should be about 50 Å to about 150 Å. However, the height difference 1Hb may be appropriately changed according to the specific semiconductor memory device. - Referring to
FIG. 2D , thelower insulation layer 211 partially etched in order to adjust a height of a surface of thelower insulation layer 211 that will define a lower portion of the air gap (which will be subsequently formed). That is, the etching process is performed so as to adjust a height difference 2Hb between the upper surface of thesemiconductor substrate 201 and the upper surface of the remaininglower insulation layer 211. Testing indicates that for an exemplary semiconductor memory device, the height difference 2Hb should be about 100 Å to about 400 Å. However, the height difference 2Hb may be appropriately changed according to the specific semiconductor memory device. - In this case, the etching process is performed with an etchant having a greater etching selectivity for the
lower insulation layer 211 than for theliner insulation layer 209. That is, an etching speed of thelower insulation layer 211 is faster than an etching speed of the liner insulation layer. - Referring to
FIG. 2E , asacrificial layer 213 is formed on the firstconductive layer 205, thelower insulation layer 211, and theliner insulation layer 209. The sacrificial layer 213 (which will be removed in a subsequent process to form the air gap) a flowable material. For example, a carbon-based material (containing about 60% carbon) may be used for thesacrificial layer 213. The carbon-based material may easily be removed by plasma. For example, the carbon-based material for thesacrificial layer 213 may be a Spin-On-Carbon (SOC) layer, a photoresist (PR) layer, or a carbon layer for a hard mask. Thesacrificial layer 213 having a flowable property may is be formed by a spin coating method. Next, a solidification process for transforming the flowablesacrificial layer 213 into a solid is performed after forming thesacrificial layer 213. The solidification process may be performed by a heat treatment process. - Referring to
FIG. 2F , the firstconductive layer 205 is exposed by performing an etching process. When the firstconductive layer 205 is exposed, an additional etching process is performed so that an upper surface of thesacrificial layer 213 becomes lower than a surface of the firstconductive layer 205. In this case, the height of the upper surface of thesacrificial layer 213 may be adjusted so as to be the same as that of the upper surface of theliner insulation layer 209, or the height difference between thesemiconductor substrate 201 and the upper portion of thesacrificial layer 213 may be adjusted to be the aforementioned height 1Hb. - Referring to
FIG. 2G , after the height of thesacrificial layer 213 is adjusted, acapping layer 215 is formed over the remainingsacrificial layer 213 and the firstconductive layer 205. Thecapping layer 215 is formed of a non-porous material, such as SiO2, SiN, SiON, or SiCN. Thecapping layer 215 may be formed by an atomic-layer deposition (ALD) method at a low temperature (about 50° C. to about 100° C.) to prevent thesacrificial layer 213 from being damaged or removed. When thecapping layer 215 is formed by the ALD method, step coverage may be improved and it is easy to form thecapping layer 215 with a uniform thickness. A thickness of thecapping layer 215 may be adjusted based on the specific memory device. In order to easily remove the sacrificial layer 213 (during a subsequent removal process) thecapping layer 215 may have a thickness of about 5 Å to about 50 Å. - Referring to
FIG. 2H , the sacrificial layer 213 (reference number 213 ofFIG. 2G ) under thecapping layer 215 is removed by using plasma. Specifically, plasma is generated inside a chamber in which thesemiconductor substrate 201 is loaded. For example, oxygen, nitrogen, or hydrogen plasma may be generated. Here, a case in which oxygen plasma is generated will be described as an example. -
FIG. 3 is a diagram illustrating a principle of removing the sacrificial layer in the present invention. - Referring to
FIG. 3 , when oxygen plasma is generated, oxygen radicals are generated and the oxygen radicals pass through thecapping layer 215 to reach thesacrificial layer 213 under thecapping layer 215. Then, the oxygen radicals and the carbon within thesacrificial layer 213 react each other so that thesacrificial layer 213 is changed into CO2 or Co radical, and the CO2 or Co radical passes through thecapping layer 215 again to be discharged to the outside. Through the aforementioned process, thesacrificial layer 213 under thecapping layer 215 may be removed, and a space in which thesacrificial layer 213 is removed becomes the air gap. Since the air gap has the same height as that of thesacrificial layer 213, it is possible to freely adjust the height between the upper portion of the air gap and the upper portion of thesemiconductor substrate 201 by adjusting the height of thesacrificial layer 213 inFIG. 2F . - Referring to
FIG. 2I , because the thickness of thecapping layer 215 on the upper portion of the air gap is thin, afirst insulation layer 217 is formed on thecapping layer 215 in order to supplement the thickness of thecapping layer 215. Thefirst insulation layer 217 is formed of an oxide layer, and is formed, for example, of a flowable PSZ layer. After the PSZ layer is formed, the PSZ layer is solidified by performing a heat treatment process. - Referring to
FIG. 2J , thefirst insulation layer 217 is etched so that a portion of thefirst insulation layer 217 remains on thecapping layer 215 in the isolation region. A process of etching thefirst insulation layer 217 is performed so that a thickness 3Hb of thefirst insulation layer 217 left in the isolation region and thecapping layer 215 is enough to support the upper portion of the air gap. - Referring to
FIG. 2K , a dielectric layer 219 is formed over thecapping layer 215 and the portion of thefirst insulation layer 217. Then a secondconductive layer 221 for a control gate is formed on the dielectric layer 219. For example, the dielectric layer 219 may be formed by sequentially stacking an oxide layer, a nitride layer, and an oxide layer. Alternatively, the dielectric layer 219 may be formed in a single layer made of a high dielectric material. The secondconductive layer 221 is formed as a polysilicon layer, for example, a doped polysilicon layer. - Next, gate lines are arranged in a direction crossing the isolation region are formed by performing a patterning process. That each of the gate lines may include the
tunnel insulation layer 203, the firstconductive layer 205, thecapping layer 215, the dielectric layer 219, and the secondconductive layer 221 stacked on the semiconductor substrate. -
FIG. 4 is a picture of a section of a semiconductor memory device including air gaps according to the present invention. - Referring to
FIG. 4 , the air gap is formed inside the isolation region and the height of the air gap is higher than the semiconductor substrate. Thus, it is possible to suppress interference between the memory cells, especially, the floating gates, and interference channel regions of the strings. - As described above, a difference of interference is generated according to a position and a structure of the air gap, and a test is result of the interference difference will be described below.
-
FIG. 5A is a graph illustrating interference between adjacent cells according to a height of the surface defining the upper portion of the air gap.FIG. 5B is a graph illustrating interference between adjacent cells according to a height of a surface defining the lower portion of the air gap.FIG. 5C is a graph illustrating interference between adjacent cells according to a width of the air gap. - Referring to
FIG. 5A , an X-axis (height) of the graph represents a height difference between the surface defining the upper portion of the air gap and the upper surface of the semiconductor substrate and a Y-axis represents interference. In the graph, it can be seen that a decrease in interference is not remarkable when the height of the surface defining the upper portion of the air gap is lower than the upper surface of the semiconductor substrate (a minus section in the X-axis), but the interference is considerably decreased from a section in which the surface defining the upper portion of the air gap is higher than the upper surface of the semiconductor substrate (a plus section in the X-axis). In the graph, it can be seen that the interference is considerably decreased when the surface defining the upper portion of the air gap is higher than the upper surface of the semiconductor substrate by about 50 Å to about 150 Å. - Referring to
FIG. 5B , an X-axis (height) of the graph represents a height difference between the surface defining the lower portion of the air gap and the upper surface of the semiconductor substrate and a Y-axis represents interference. For example, “−200 Å” in the X-axis means that the surface defining the lower portion of the air gap is lower than the upper portion of the semiconductor substrate by 200 Å. - As can be seen from the graph of
FIG. 5B , the interference is decreased as the surface defining the lower portion of the air gap becomes lower than the upper surface of the semiconductor substrate. However, a quantity of an interference change is about 150 my to 130 mV. Thus, a height difference between the surface defining the lower portion of the air gap and the upper surface of the semiconductor substrate less exerts influence on the interference than a height difference between the surface defining the upper surface of the air gap and the upper surface of the semiconductor substrate. - Referring to
FIG. 5C , an X-axis (height) of the graph represents a ratio (%) of a width of the air gap to a width (trench) of the isolation region and a Y-axis represents interference. In the graph, it can be seen that as the width of the air gap increases, that is, as the width of the air gap becomes dose to the width of the is trench, the interference is decreased. - As shown in
FIGS. 5A to 5C , the height and the width of the surface defining the upper portion of the air gap exert a large influence on the interference between the memory cells, as compared to the height of the surface defining the lower portion of the air gap. For example, the interference between the memory cells may be minimized when the surface defining the upper portion of the air gap is higher than the upper surface of the semiconductor substrate by about 50 Å to about 100 Å, and the width of the air gap is dose to the width of the trench. However, this value is an example obtained as the result of the test. A position and a width at which the interference is minimized may be adjusted by appropriately adjusting the position and the width according to the requirements of a specific memory device. The height of the sacrificial layer (which defines the upper portion of the air gap) may be adjusted via the processes of the manufacturing the semiconductor memory device. (See e.g.,FIGS. 1C and 2F ). The width of the sacrificial layer may be adjusted (seeFIGS. 1E and 2H ) via the processes of the manufacturing the semiconductor memory device, so that the width of the air gap is close to the width of the trench. -
FIGS. 6A and 6C are simulation diagrams illustrating interference according to a height of the surface defining the upper portion of the air gap. -
FIG. 6A shows interference in a memory device having no air gap.FIG. 6B shows interference in a memory device, where a surface defining an upper portion of an air gap is lower than an upper surface of a semiconductor substrate.FIG. 6C shows interference in an exemplary memory device, where a surface defining an upper portion of an is higher an upper surface of the semiconductor substrate. - In
FIG. 6 , darker shading means that a region has more interference than a region with lighter shading. Accordingly, inFIG. 6A , the region affected by interference Ea is wider than the cases shown inFIG. 68 or 6C that of case B or case C, so it can be seen that interference to an adjacent cell is high. InFIG. 6B , it can be seen that interference Eb is decreased compared to the case in which the memory device has no air gap, shown inFIG. 6A . InFIG. 6C , it can be seen that interference Ec is decreased compared toFIG. 6B in which the upper surface of the air gap is lower than the upper surface of the semiconductor substrate. - As described, it is possible to decrease interference between active regions by forming the air gap. Especially, when the air gap is formed within the isolation region, the interference may be effectively decreased as the upper surface of the air gap is higher than the is semiconductor substrate in the active region and is close to the width of the isolation region.
-
FIGS. 7A to 7I are cross sectional views illustrating a method of manufacturing an exemplary semiconductor memory device. - Referring to
FIG. 7A , a plurality of gate lines GL is formed on asemiconductor substrate 701. For example, each of the plurality of gate lines GL may be formed in a structure in which atunnel insulation layer 703, a floatinggate 705, adielectric layer 707, and acontrol gate 709 are stacked. A structure of the plurality of gate lines GL illustrated in the drawing may be variously changed according to specific requirements of a semiconductor memory device. - Referring to
FIG. 7B , a firstsacrificial layer 711, having a first thickness, is formed on thesemiconductor substrate 701 between each of the plurality of gate lines GL. Specifically, the firstsacrificial layer 711 is formed on an entire structure including the gate lines GL, and the firstsacrificial layer 711 is formed so as to cover all of upper portions of the gate lines GL so that spaces between the gate lines GL are sufficiently filled with the firstsacrificial layer 711. A flowable carbon-based material (containing about 60% of carbon) is used as thesacrificial layer 711. The carbon-based material may easily be removed by plasma. For example, thesacrificial layer 711 may be a Spin-On-Carbon (SOC) layer or a photoresist (PR) layer. Thesacrificial layer 711 may be formed by a spin coating method. Next, a solidification process for transforming the flowable firstsacrificial layer 711 into a solid is performed after forming the firstsacrificial layer 711. The solidification process may be performed by a heat treatment process. Next, the firstsacrificial layer 711 is etched to the first thickness (which defines an upper portion of an air gap that will be subsequently formed). - Referring to
FIG. 7C , afirst capping layer 713 is formed on a surface of the floatinggate 705, thedielectric layer 707, thecontrol gate 709, and the firstsacrificial layer 711. Thefirst capping layer 713 is formed of a non-porous material, such as SiO2, SiN, SiON, or SiCN. Especially, in the process of forming thefirst capping layer 713, thefirst capping layer 713 is formed by an ALD method at a low temperature (about 50° C. to about 100° C.) so as to prevent the firstsacrificial layer 711 from being damaged or partially removed. When thefirst capping layer 713 is formed by the ALD method, step coverage may be improved and it is easy to form thefirst capping layer 713 with a uniform thickness. A thickness of thefirst capping layer 713 may be adjusted according to the requirements of a specific memory device. In order to easily remove the firstsacrificial layer 711 in a subsequent process, thefirst capping layer 713 may have a thickness of about 5 Å to about 50 Å. - Referring to
FIG. 7D , the first sacrificial layer (reference number 711 ofFIG. 7C ) under thefirst capping layer 713 is removed by using plasma. Specifically, plasma is generated inside a chamber in which thesemiconductor substrate 701 is loaded. For example, oxygen, nitrogen, or hydrogen plasma may be generated. When the plasma is generated, the firstsacrificial layer 711 passes through thefirst capping layer 713 to exit to the outside, as described above with reference toFIG. 3 . A space from which the firstsacrificial layer 711 is removed becomes a first air gap. - Referring to
FIG. 7E , a second sacrificial layer +715, having a second thickness, is formed on a portion of thefirst capping layer 713 that covers the first air gap. The secondsacrificial layer 715 may be formed of the same material, and by the same method, as was used to form the firstsacrificial layer 711, described above with reference toFIG. 7B . Next, asecond capping layer 717 is formed over a surface of the secondsacrificial layer 715 and thefirst capping layer 713. Thesecond capping layer 717 is formed of a non-porous material, such as SiO2, SiN, SiON, or SiCN. Thesecond capping layer 717 may be formed by an ALD method at a low temperature (about 50° C. to about 100° C.). A thickness of thesecond capping layer 715 may be adjusted according to the requirements of a specific memory device. For example, thesecond capping layer 715 may have a thickness of about 5 Å to about 50 Å. - Referring to
FIG. 7F , the second sacrificial layer (reference number 715 ofFIG. 7E ) under thesecond capping layer 717 is removed by using plasma. For example plasma may be generated inside a chamber in which thesemiconductor substrate 701 is loaded. For example, oxygen, nitrogen, or hydrogen plasma may be generated. When the plasma is generated, the secondsacrificial layer 715 passes through thesecond capping layer 717 to exit to the outside, as described above with reference toFIG. 3 . A space from which the secondsacrificial layer 715 is removed becomes a second air gap. The second air gap is formed on thesecond capping layer 717 and has a width that is narrower than a width of the first air gap. - Referring to
FIG. 7G , a thirdsacrificial layer 719, having a third thickness, is formed on a portion of thesecond capping layer 717 that covers the second air gap. The thirdsacrificial layer 719 may be formed of the same material as that of the firstsacrificial layer 711 and the secondsacrificial layer 715. The thirdsacrificial layer 719 is formed so that an upper surface of the thirdsacrificial layer 719 is substantially coplanar with an upper surface of thesecond capping layer 717 formed on the gate lines GL. The thirdsacrificial layer 719 may be formed of the same material, and by the same method, as was used to form the firstsacrificial layer 711 or the secondsacrificial layer 715. Athird capping layer 721 is formed on the thirdsacrificial layer 719 and thesecond capping layer 717. Thethird capping layer 721 is formed of a non-porous material, such as SiO2, SiN, SiON, or SiCN. Thethird capping layer 721 may be formed using the same method as used to form thefirst capping layer 713 or thesecond capping layer 717. - Referring to
FIG. 7H , the third sacrificial layer (reference number 719 ofFIG. 7G ) under thethird capping layer 721 is removed by using plasma. For example, plasma may be generated inside a chamber in which thesemiconductor substrate 701 is loaded. For example, oxygen, nitrogen, or hydrogen plasma may be generated. When the plasma is generated, the thirdsacrificial layer 719 passes through thethird capping layer 721 to exit to the outside, as described above with reference toFIG. 3 . A space from which the thirdsacrificial layer 719 is removed becomes a third air gap. The third air gap is formed on thesecond capping layer 717 and has a width that is narrower than a width of the second air gap. - Referring to
FIG. 7I , aninterlayer insulation layer 723 is formed on thethird capping layer 721, and then a subsequent process performed. The first to third capping layers 713, 715, and 721 serve as supports between the gate lines GL. That is, if the first to third capping layers 713, 715, and 721 where to be removed, so that only a single air gap remained, then the gate lines GL may lean in a side direction. Accordingly, it is simultaneously possible to suppress interference between the gate lines GL and prevent the gate lines GL from leaning. - In
FIGS. 7A to 7I , show three air gaps are formed between the gate lines GL, but, as shown inFIG. 8 , any number (n) of air gaps may be formed between the gate lines GL.Reference numeral 801 inFIG. 8 denotes a semiconductor substrate, and CA1 to CAn indicate first to nth capping layers. As illustrated inFIGS. 7I and 8 , it is possible to prevent the gate lines GL from leaning and more effectively suppress interference between the gate lines GL, by forming the air gaps to be higher than the upper surfaces of the gate lines GL. - As described above, an exemplary embodiment has been disclosed in the drawings and the specification. The specific terms used herein are for purposes of illustration, and do not limit the scope of the present invention recited in the claims. Accordingly, those skilled in the art will appreciate that various modifications and other equivalent examples may be made without departing from the scope and spirit of the present disclosure. Therefore, the sole technical protection scope of the present invention will be defined by the technical spirit of the accompanying claims.
Claims (59)
1. A semiconductor memory device, comprising:
a semiconductor substrate in which isolation regions and active regions are defined;
gate lines formed on the semiconductor substrate in a direction crossing the isolation regions; and
a capping layer configured to define air gaps positioned higher than an upper surface of the semiconductor substrate in the isolation regions.
2. The semiconductor memory device of claim 1 , where the air gaps are formed in trenches defined in the isolation regions of the semiconductor substrate.
3. The semiconductor memory device of claim 1 , where the capping layer is higher than the upper surface of the semiconductor substrate in the active regions by about 50 Å to about 150 Å.
4. The semiconductor memory device of claim 2 , where the air gap has a same width as a width of the isolation region.
5. The semiconductor memory device of claim 2 , further comprising:
a liner insulation layer formed over a surface of the trenches, where a width of the air gap is a same width as a width of the trenches having the liner isolation layer.
6. The semiconductor memory device of claim 1 , further comprising:
a lower insulation layer to define a lower portion of the air gap in the isolation regions.
7. The semiconductor memory device of claim 6 , where the lower insulation layer is formed of a flowable material.
8. The semiconductor memory device of claim 7 , where the flowable material is a polisilazane (PSZ).
9. The semiconductor memory device of claim 6 , where an upper surface of the lower insulation layer is lower than an upper surface of the semiconductor substrate of the active regions by about 100 Å to about 400 Å.
10. The semiconductor memory device of claim 1 , where the capping layer is formed of a non-porous material.
11. The semiconductor memory device of claim 10 , where the non-porous material includes a silicon dioxide (SiO2), a silicon nitride (SiN), a silicon oxynitride SiON, or a silicon carbide nitride (SiCN).
12. The semiconductor memory device of claim 1 , where the capping layer is formed by atomic layer deposition (ALD).
13. The semiconductor memory device of claim 1 , where the capping layer has a thickness of about 5 Å to about 50 Å.
14. The semiconductor memory device of claim 1 , where each of the gate lines comprises a plurality of layers stacked on the semiconductor substrate, the plurality of layers including:
a tunnel insulation layer,
a first conductive layer for a floating gate,
the capping layer, a dielectric layer, and
a second conductive layer for a control gate.
15. The semiconductor memory device of claim 14 , further comprising:
an insulation layer formed between the capping layer and the dielectric layer in the isolation region.
16. The semiconductor memory device of claim 15 , were the insulation layer and the capping layer support the upper portion of the air gap.
17. The semiconductor memory device of claim 15 , where the insulation layer is formed of a flowable material.
18. The semiconductor memory device of claim 17 , where the flowable material is a polisilazane (PSZ) layer.
19. A semiconductor memory device, comprising:
a semiconductor substrate in which an isolation region and an active region are defined;
a tunnel insulation layer, a floating gate, a capping layer, a dielectric layer, and a control gate formed over the semiconductor substrate of the active region;
a trench formed in the semiconductor substrate of the isolation region; and
an air gap formed inside the trench,
where the capping layer defines an upper surface of the air gap and where the capping layer is positioned higher than a surface of the semiconductor substrate.
20. The semiconductor memory device of claim 19 , where the capping layer is formed of a non-porous material.
21. The semiconductor memory device of claim 20 , where the non-porous material includes a silicon dioxide (SiO2), a silicon nitride (SiN) a silicon oxynitride SiON, or a silicon carbide nitride (SiCN).
22. The semiconductor memory device of claim 19 , where the capping layer has a thickness of about 5 Å to about 50 Å.
23. The semiconductor memory device of claim 19 , further comprising:
a lower insulation layer filling a lower portion of the trench, where the lower insulation layer is to define a lower surface of the air gap.
24. A method of manufacturing a semiconductor memory device, the method comprising:
forming a tunnel insulation layer and a floating gate on a semiconductor substrate of an active region;
forming a trench in the semiconductor substrate of an isolation region;
forming, in the trench, a sacrificial layer having an upper surface positioned higher than a surface of the semiconductor substrate;
forming a capping layer over the sacrificial layer; and
forming an air gap by removing the sacrificial layer without removing the capping layer.
25. The method of claim 24 , where the sacrificial layer is a flowable material containing carbon.
26. The method of claim 25 , where sacrificial layer is a Spin-On-Carbon (SOC) layer or a photoresist (PR) layer.
27. The method of claim 25 , further comprising:
forming the sacrificial layer by spin coating.
28. The method of claim 24 , where forming the sacrificial layer comprises:
filling the trench with the sacrificial layer;
solidifying the sacrificial layer by performing a heat treatment process; and
etching the sacrificial layer so that an upper surface of the sacrificial layer is positioned higher than the surface of the semiconductor substrate.
29. The method of claim 28 , where etching the sacrificial layer further comprises:
etching the sacrificial layer so that the upper surface of the sacrificial layer is about 50 Å to about 150 Å higher than the surface of the semiconductor substrate.
30. The method of claim 24 , further comprising:
forming a lower insulation layer in a lower portion of the trench before forming the sacrificial layer in the trench.
31. The method of claim 30 , where the lower insulation layer is formed of a flowable material.
32. The met hod of claim 31 , where the flowable material is a polisilazane (PSZ).
33. The method of claim 30 , where forming the lower insulation layer further comprises:
solidifying the lower insulation layer by performing a heat treatment process; and
etching the lower insulation layer so that an upper surface of the lower insulation layer is lower than the surface of the semiconductor substrate.
34. The method of claim 33 , where etching the lower insulation layer further comprises:
etching the lower insulation layer to be about 100 Å to about 400 Å lower than the surface of the semiconductor substrate.
35. The method of claim 24 , where the capping layer is formed of a non-porous material.
36. The method of claim 35 , where the non-porous material includes a silicon dioxide (SiO2), a silicon nitride (SiN), a silicon oxynitride SiON, or a silicon carbide nitride (SiCN).
37. The method of claim 24 , where the capping layer is formed by atomic layer deposition (ALD) method at a low temperature.
38. The method of claim 37 , where the low temperature includes a temperature range of about 50° C. to about 100° C.
39. The method of claim 24 , where the capping layer has a thickness of about 5 Å to about 50 Å.
40. The method of claim 24 , where removing the sacrificial layer further comprises:
removing the sacrificial layer via plasma.
41. The method of claim 40 , where the plasma is an oxygen, a nitrogen, or a hydrogen plasma.
42. The method of claim 24 , further comprising;
forming an insulation layer on the capping layer after forming the air gap; and
etching the insulation layer so that only a portion of the insulation layer remains in the isolation region over the capping layer.
43. The method of claim 42 , where the insulation layer is formed of a flowable material.
44. The method of claim 43 , where the flowable material is a polisilazane (PSZ) layer.
45. A semiconductor memory device comprising;
a plurality of gate lines formed on a semiconductor substrate; and
a plurality of capping layers formed between the gate lines, wherein the capping layers define a plurality of air gaps between the gate lines.
46. The semiconductor memory device of claim 45 , where the capping layers are formed of non porous materials.
47. The semiconductor memory device of claim 46 , where the non-porous a materials include silicon dioxide (SiO2), a silicon nitride (SiN), a silicon oxynitride SiON, or a silicon carbide nitride (SiCN).
48. The semiconductor memory device of claim 45 , where the plurality of capping layers are formed to have a thickness of about 5 Å to about 50 Å.
49. The semiconductor memory device of claim 45 , where a width of an air gap, of the plurality of air gaps, formed at an upper portion of a gate line, of the plurality of gate lines, is narrower than a width of the air gap formed at a lower portion of the gate line.
50. A method of manufacturing a semiconductor memory is device, the method comprising:
forming a plurality of gate lines on a semiconductor substrate;
alternately forming sacrificial layers and capping layers on the semiconductor substrate between the gate lines and
forming a plurality of air, defined by the capping layers, between the gate lines by removing the sacrificial layers.
51. The method of claim 50 , where alternately forming the sacrificial layers and the capping layers further comprises:
forming a sacrificial layer between the gate lines;
solidifying the sacrificial layer;
etching the sacrificial layer so that a remaining portion of the sacrificial layer has a predetermined thickness; and
forming the capping layer over the remaining portion of the sacrificial layer.
52. The method of claim 50 , where the sacrificial layer is formed of a flowable material containing carbon.
53. The method of claim 52 , where the sacrificial layer is a Spin-On-Carbon (SOC) layer or a photoresist (PR) layer.
54. The method of claim 52 , where the sacrificial layer is formed by spin coating.
55. The method of claim 50 , where the capping layer is formed of a non-porous material.
56. The method of claim 50 , where the non-porous layer material includes a silicon dioxide (SiO2), a silicon nitride (SiN), a silicon oxynitride SiON, or a silicon carbide nitride (SiCN).
57. The method of claim 50 , where the capping layer is formed by atomic layer deposition (ALD) at a low temperature.
58. The method of claim 57 , where the low temperature includes a temperature range of about 50° C. to about 100° C.
59. The method of claim 50 , where the capping layer is has a is thickness of about 5 Å to about 50 Å.
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Also Published As
Publication number | Publication date |
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CN103579249B (en) | 2019-02-01 |
CN103579249A (en) | 2014-02-12 |
US9947543B2 (en) | 2018-04-17 |
US20160111291A1 (en) | 2016-04-21 |
KR20140020476A (en) | 2014-02-19 |
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