US20070093021A1 - Mos transistor with recessed gate and method of fabricating the same - Google Patents
Mos transistor with recessed gate and method of fabricating the same Download PDFInfo
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- US20070093021A1 US20070093021A1 US11/562,138 US56213806A US2007093021A1 US 20070093021 A1 US20070093021 A1 US 20070093021A1 US 56213806 A US56213806 A US 56213806A US 2007093021 A1 US2007093021 A1 US 2007093021A1
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- 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
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
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- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. 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
- H01L29/66568—Lateral single gate silicon transistors
- H01L29/66613—Lateral single gate silicon transistors with a gate recessing step, e.g. using local oxidation
- H01L29/66621—Lateral single gate silicon transistors with a gate recessing step, e.g. using local oxidation using etching to form a recess at the gate location
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- 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
- H01L21/77—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate
- H01L21/78—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices
- H01L21/82—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices to produce devices, e.g. integrated circuits, each consisting of a plurality of components
- H01L21/822—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices to produce devices, e.g. integrated circuits, each consisting of a plurality of components the substrate being a semiconductor, using silicon technology
- H01L21/8232—Field-effect technology
- H01L21/8234—MIS technology, i.e. integration processes of field effect transistors of the conductor-insulator-semiconductor type
- H01L21/823437—MIS technology, i.e. integration processes of field effect transistors of the conductor-insulator-semiconductor type with a particular manufacturing method of the gate conductors, e.g. particular materials, shapes
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- 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
- H01L21/77—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate
- H01L21/78—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices
- H01L21/82—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices to produce devices, e.g. integrated circuits, each consisting of a plurality of components
- H01L21/822—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices to produce devices, e.g. integrated circuits, each consisting of a plurality of components the substrate being a semiconductor, using silicon technology
- H01L21/8232—Field-effect technology
- H01L21/8234—MIS technology, i.e. integration processes of field effect transistors of the conductor-insulator-semiconductor type
- H01L21/823481—MIS technology, i.e. integration processes of field effect transistors of the conductor-insulator-semiconductor type isolation region manufacturing related aspects, e.g. to avoid interaction of isolation region with adjacent structure
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- H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. 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
- H01L29/66537—Unipolar field-effect transistors with an insulated gate, i.e. MISFET using a self aligned punch through stopper or threshold implant under the gate region
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- H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. 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
- H01L29/7833—Field effect transistors with field effect produced by an insulated gate with lightly doped drain or source extension, e.g. LDD MOSFET's; DDD MOSFET's
- H01L29/7835—Field effect transistors with field effect produced by an insulated gate with lightly doped drain or source extension, e.g. LDD MOSFET's; DDD MOSFET's with asymmetrical source and drain regions, e.g. lateral high-voltage MISFETs with drain offset region, extended drain MISFETs
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B12/00—Dynamic random access memory [DRAM] devices
- H10B12/01—Manufacture or treatment
- H10B12/02—Manufacture or treatment for one transistor one-capacitor [1T-1C] memory cells
- H10B12/05—Making the transistor
- H10B12/053—Making the transistor the transistor being at least partially in a trench in the substrate
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- H—ELECTRICITY
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- 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
- H01L21/77—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate
- H01L21/78—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices
- H01L21/82—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices to produce devices, e.g. integrated circuits, each consisting of a plurality of components
- H01L21/822—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices to produce devices, e.g. integrated circuits, each consisting of a plurality of components the substrate being a semiconductor, using silicon technology
- H01L21/8232—Field-effect technology
- H01L21/8234—MIS technology, i.e. integration processes of field effect transistors of the conductor-insulator-semiconductor type
- H01L21/823487—MIS technology, i.e. integration processes of field effect transistors of the conductor-insulator-semiconductor type with a particular manufacturing method of vertical transistor structures, i.e. with channel vertical to the substrate surface
Definitions
- the present invention relates to a semiconductor device and a method of fabricating the same and, more particularly, to a MOS transistor with a recessed gate and a method of fabricating the same.
- FIG. 1 is a plan view of a typical MOS transistor with a recessed gate.
- an active region 11 is defined by a trench isolation layer 11 a formed in a semiconductor substrate.
- a recessed gate 30 is formed to intersect the active region 11 .
- One portion of the active region 11 adjacent to the gate 30 is a source region 13
- another portion of the active region 11 at the other side of gate 30 is a drain region 15 .
- One portion of the active region 11 which is overlapped by the gate 30 is a channel region 17 .
- FIGS. 2 and 3 are sectional views which illustrate the structure of the MOS transistor taken along the lines of I-I′ and II-II′ of FIG. 1 respectively.
- the recessed gate 30 is located in a shallow trench formed in a semiconductor substrate 10 .
- the active regions adjacent to the recessed gate 30 are the source region 13 and the drain region 15 , and the active region under the recessed gate 30 is the channel region 17 .
- a gate insulating layer 20 is interposed between the recessed gate 30 and the channel region 17 .
- the depth of the recessed gate 30 is deeper than the depth of the source/drain region 13 , 15 , therefore the effective channel length L can be lengthened.
- the channel region 17 is located between the trench isolation layers 11 a .
- the source region 13 ( FIG. 1 ) and the drain region 15 ( FIG. 1 ) are located at the front and the back of the channel region 17 respectively, and the recessed gate 30 is located on the channel region 17 .
- the recessed gate 30 has a positive slopped sidewall and the trench isolation layers 11 a also have a positive slopped sidewall.
- the above structure creates a sharp tip 17 a in the channel region 17 at which the recessed gate 30 and the trench isolation layer 11 a adjoin each other. Referring to FIG.
- the sharp tip 17 a is formed along the boundary between the channel region 17 and the trench isolation layer 11 a .
- a channel is formed not only under the recessed gate 30 , and but also in the sharp tip 17 a .
- the channel formed in the sharp tip 17 a can reduce the effective channel length of the MOS transistor with the recessed gate 30 . Therefore, the MOS transistor with the recessed gate may result in a failure to suppress the short channel effect.
- Exemplary embodiments of the present invention provide a MOS transistor with a recessed gate structured for suppressing the reduction of effective channel length.
- the present invention also provides a method of fabricating a MOS transistor with a recessed gate structured to suppress the reduction of effective channel length.
- the present invention provides a MOS transistor which includes a semiconductor substrate, and a trench isolation layer located in a predetermined region of the semiconductor substrate for defining an active region.
- the trench isolation layer has a negative slope on at least a lower sidewall thereof.
- a recessed gate is located in a predetermined region of the active region, and a bottom surface of the recessed gate is placed adjacent or contacts the negatively slopped sidewall of the trench isolation layer.
- the overall sidewall including the lower sidewall of the trench isolation layer may have a negative slope.
- the trench isolation layer may have a positive slope on its upper sidewall and a negative slop on the lower sidewall.
- the trench isolation layer is preferably formed of high-density plasma chemical vapor deposition (HDP-CVD) insulating layer.
- a gate insulating layer may be interposed between the recessed gate and the active region and the recessed gate may be formed of polysilicon.
- the present invention provides a method of fabricating a MOS transistor.
- the method comprises first preparing a semiconductor substrate.
- An isolation trench having a negative slope on at least a lower sidewall is formed in a predetermined region of the semiconductor substrate to define an active region.
- the isolation trench is filled with an insulating layer, and the semiconductor substrate having the isolation trench filled with the insulating layer is polished by using a CMP so as to form a trench isolation layer.
- a recessed gate is formed in a predetermined region of the active region, and a bottom surface of the recessed gate is placed adjacent or contacts the negatively slopped lower sidewall of the trench isolation layer.
- the isolation trench may be formed so as to have a negative slope on the overall sidewall including the lower sidewall.
- the isolation trench may be formed to have a positive slope on its upper sidewall and a negative slope on its lower sidewall.
- negative-slope etching may be employed when the sidewall is formed.
- the negative-slope etching may be performed by a dry etching or a wet etching.
- the dry etching may be performed by using a substrate etching gas including NF 3 and SF 6 .
- a liner is preferably formed inside the isolation trench.
- the filling of the isolation trench with the insulating layer may include partially filling the isolation trench with a first insulating layer.
- the first insulating layer is anisotropically etched to form an insulating spacer on the negatively slopped lower sidewall of the isolation trench.
- the isolation trench having the insulating spacer is substantially completely filled with a second insulating layer.
- the first and second insulating layer is can be formed of an HDP-CVD insulating layers.
- the anisotropically etching of the first insulating layer can be performed by using a reactive ion etching (RIE) process.
- RIE reactive ion etching
- the insulating spacer can be formed to cover at least the negatively slopped lower sidewall.
- a channel trench may be formed in a predetermined region of the active region such that the bottom surface of the channel trench contacts a negatively slopped lower sidewall of the trench isolation layer.
- a gate insulating layer is formed on the bottom surface of the channel trench, and a gate conductive layer is formed on the gate insulating layer to fill the channel trench. Then, the gate conductive layer is patterned. Before forming the gate insulating layer, it is preferable to include a process of performing a channel ion implantation process onto the channel trench.
- the gate conductive layer may be formed of polysilicon.
- FIG. 1 is a plane view of a typical MOS transistor with a recessed gate
- FIG. 2 is a sectional view to illustrate the structure of a MOS transistor taken along the line of I-I′ of FIG. 1 ;
- FIG. 3 is a sectional view to illustrate the structure of a MOS transistor taken along the line of II-II′ of FIG. 1 ;
- FIG. 4 is a plane view to illustrate a part of a typical DRAM cell array region employing a MOS transistor with a recessed gate;
- FIGS. 5 a to 5 f are sectional views to illustrate a method of fabricating a MOS transistor according to a first embodiment of the present invention taken along the line of I-I′ of FIG. 4 ;
- FIGS. 6 a to 6 c are sectional views to illustrate a method of fabricating a MOS transistor according to a second embodiment of the present invention taken along the line of I-I′ of FIG. 4 .
- FIG. 4 is a plan view of a part of a typical DRAM cell array region employing a MOS transistor with a recessed gate.
- an active region 300 is defined by a trench isolation layer located in a semiconductor substrate.
- a word line 700 intersects the active region 300 .
- a portion of the active region 300 , adjacent to the word line 700 is a source region 380 , and another portion of the active region 300 , on the other opposite side to the source region 380 , is a drain region 370 .
- a portion of the active region 300 , overlapped by the word line 700 is a channel region 390 .
- the channel region 390 is recessed into the semiconductor substrate, and a recessed gate 750 , which is a part of the word line 700 , is located on the recessed channel region 390 .
- FIGS. 5 a to 5 f are sectional views to illustrate the processing sequences of a method of fabricating a MOS transistor according to a first embodiment of the present invention taken along the line of I-I′ of FIG. 4 .
- a hard mask pattern 200 including a pad oxide layer 210 , a polishing stop layer 230 , and an oxide layer 250 are sequentially stacked on a semiconductor substrate 100 .
- the hard mask pattern 200 exposes a portion of a semiconductor substrate 100 .
- the pad oxide layer 210 functions as a buffer layer for alleviating the stress applied on the substrate 100 , which occurs during the formation of the polishing stop layer 230 on the substrate 100 .
- the pad oxide layer 210 can be formed of a thermal oxide layer to a thickness of 20 to 200 ⁇ .
- the polishing stop layer 230 is used as a polishing stop point during a subsequent chemical mechanical polishing (CMP) process, and it may be formed of silicon nitride.
- CMP chemical mechanical polishing
- the polishing stop layer 230 is formed to a thickness of several hundreds to approximately 1000 ⁇ .
- the oxide layer 250 is formed so that the hard mask pattern 200 including the oxide layer 250 has a uniform pattern width. The oxide layer 250 can be omitted.
- an isolation trench 105 is formed by etching the exposed portion of the substrate 100 so as to define an active region 106 .
- the active region 106 corresponds to the channel region 390 of FIG. 4 .
- the isolation trench 105 is formed so as to have a negative slope at least on its lower sidewall.
- the overall sidewall 105 a of the isolation trench 105 is formed to have a negative slope.
- “the sidewall of isolation trench has a negative slope” may mean that the width of the isolation trench 105 surrounded by the sidewall is increased toward the lower portion of the isolation trench 105 .
- the isolation trench 105 is formed using a negative-slope etching so that the sidewall 105 a has a negative slope.
- the negative-slope etching can be performed by dry etching or by a wet etching, but dry etching is preferable. Furthermore, in the dry etching, it is preferable to employ a substrate etching gas including NF 3 and SF 6 .
- a thermal oxide layer (not shown) is preferably formed on the bottom and the sidewall of the isolation trench 105 by performing a thermal treatment on the substrate 100 having the isolation trench 105 formed therein.
- the thermal oxide layer cures the damage to the substrate 100 when the isolation trench 105 is formed.
- a liner 320 can be formed on the substrate 100 having the thermal oxide layer.
- the liner 320 covers the sidewall and the bottom surface of the isolation trench 105 .
- the liner 320 is a layer having excellent oxidation-resistant characteristics.
- the liner 320 can be a nitride layer, for example.
- a first insulating layer 330 is formed to partially fill the isolation trench 105 having the liner 320 .
- the first insulating layer 330 may be a layer having an excellent gap-fill characteristic.
- the first insulating layer 330 is formed of HDP-CVD insulating layer.
- a HDP-CVD insulating layer is a HDP-CVD oxide layer, The HDP-CVD oxide layer is known to have an excellent gap-fill characteristic.
- the first insulating layer 330 is anisotropically etched to form an insulating spacer 335 on the negatively slopped sidewall 105 a .
- the bottom surface of the isolation trench 105 may be exposed.
- the etching of the first insulating layer 330 is preferably performed by using an RIE process.
- the insulating spacer 335 is preferably formed to cover the negatively slopped sidewall 105 a.
- a second insulating layer 350 is formed on the substrate 100 such that the insulating spacer 335 substantially completely fills the isolation trench 105 .
- the second insulating layer 350 is also a layer having an excellent gap-fill characteristic.
- the second insulating layer 350 is HDP-CVD insulating layer.
- HDP-CVD insulating layer is formed of HDP-CVD oxide.
- the isolation trench is formed such that its sidewall has a positive slope. That is, the isolation trench is formed such that its width surrounded by the sidewall is decreased as it goes further toward the lower portion of the isolation trench 105 , thereby minimizing the generation of voids when the isolation trench 105 is filled with an insulating layer. If the isolation trench 105 is formed such that the overall sidewall of the isolation trench has a negative slope, the voids may be generated when the isolation trench 105 is filled with an insulating layer.
- the insulating spacer 335 is formed on the negatively slopped sidewall 105 a of the isolation trench 105 such that the width of the opening in the isolation trench 105 , left by the insulating spacer 335 , is reduced toward the lower portion of the isolation trench 105 .
- the isolation trench 105 can be filled with the second insulating layer 350 without voids.
- the substrate 100 having the isolation trench filled with the second insulating layer 350 is planarized through a CMP process so as to expose the polishing stop layer 230 . Then, a trench isolation layer 370 is formed by removing the exposed polishing stop layer 230 and the pad insulating layer 210 under the polishing stop layer 230 .
- a photoresist pattern 400 is formed on the substrate 100 having the trench isolation layer 370 to expose the active region of the substrate 100 , that is, a channel region 106 .
- the exposed channel region 106 is etched using the photoresist pattern 400 as an etch mask to form a channel trench 600 , and the bottom surface of the channel trench 600 is formed adjacent the negatively slopped sidewall 105 a of the trench isolation layer 370 .
- the channel trench 600 is preferably formed by using a de-coupled plasma source (DPS).
- DPS de-coupled plasma source
- a channel ion implantation into the channel trench 600 is performed using the photoresist pattern 400 as a mask.
- the channel ion implantation is performed to control a threshold voltage as known in the art.
- the photoresist pattern 400 is removed to expose the top portion of the trench isolation layer 370 .
- the substrate 100 is thermally oxidized to form a gate insulating layer 500 on the bottom surface of the channel trench 600 .
- a gate conductive layer is formed on the gate insulating layer 500 to fill the channel trench 600 .
- the gate conductive layer may be formed of polysilicon.
- the gate conductive layer is patterned to form a recessed gate 750 , whereby the source region 380 ( FIG. 4 ) and the drain region 370 ( FIG. 4 ) is exposed.
- a bottom surface of the recessed gate 750 is located adjacent the negatively slopped sidewall 105 a .
- the recessed gate 750 is extended on the trench isolation layer 370 to form a word line 700 .
- the formation of the MOS transistor is completed by performing an ion implantation process onto the exposed source region 380 ( FIG. 4 ) and the exposed drain region 370 ( FIG. 4 ), which are located on the front and the back of the channel region 106 , respectively.
- FIGS. 6 a to 6 c are sectional views to illustrate a method of fabricating a MOS transistor according to a second embodiment of the present invention taken along line of I-I′ of FIG. 4 .
- the method of fabricating the MOS transistor according to a second embodiment of the present invention is the same as the method explained in the first embodiment except the explanation to be described as follows.
- the semiconductor substrate 100 is etched to form an isolation trench 107 , using the hard mask patterns 200 formed on the substrate 100 , and at the same time, an active region i.e. channel region 108 is defined.
- the hard mask patterns 200 include a pad oxide layer 210 , a polishing stop layer 230 , and an oxide layer 250 , which are sequentially stacked.
- the isolation trench 107 is formed to have a negative slope at least on its lower sidewall.
- the isolation trench 107 is formed to have a positive slope on its upper sidewall 107 a and a negative slope on the rest of its sidewall, i.e., lower sidewall 107 b .
- the formation of the negative slope on the lower sidewall 107 b is preferably made by using a negative-slope etching as described in the first embodiment.
- the substrate 100 having the isolation trench 107 is thermally treated to form a thermal oxide layer (not shown) on the bottom and the sidewall of the isolation trench 107 .
- a liner 320 can be formed on the substrate 100 having the thermal oxide layer.
- a first insulating layer is formed on the liner 320 to partially fill the isolation trench 107 .
- the first insulating layer is anisotropically etched to form an insulating spacer 335 on the negatively slopped lower sidewall 107 b .
- the bottom surface of the isolation trench 107 may be exposed at the same time.
- the insulating spacer 335 is preferably formed to cover at least the negatively slopped lower sidewall 107 b .
- the anisotropically etching of the first insulating layer is performed by using a RIE process.
- a second insulating layer 350 is formed on the substrate 100 having the insulating spacer 335 to substantially completely fill the isolation trench 107 .
- the width of the opening left in the isolation trench 107 by the insulating spacer 335 is formed so as to be reduced toward the lower portion of the isolation trench 107 . Therefore, the possibility of the void generation is reduced, and the isolation trench 107 can be filled with the second insulating layer 350 without voids.
- the substrate 100 having the second insulating layer 350 is planarized using a chemical mechanical polishing (CMP) process to expose the polishing stop layer 230 . Then, the exposed polishing stop layer 230 and the pad insulating layer 210 under the exposed polishing stop layer 230 are removed to form a trench isolation layer 370 .
- CMP chemical mechanical polishing
- a channel trench is formed in a predetermined region of the active region i.e. channel region 108 of the substrate 100 having the trench isolation layer 370 .
- the channel trench is formed such that its bottom surface is located adjacent the negatively slopped lower sidewall 107 b of the trench isolation layer 370 .
- the channel trench is preferably formed by using a de-coupled plasma source (DPS).
- DPS de-coupled plasma source
- a gate insulating layer 500 is formed on the bottom surface of the channel trench.
- a gate conductive layer is formed on the gate insulating layer 500 to fill the channel trench.
- the recessed gate 750 is extended on the trench isolation layer 370 to form a word line 700 .
- a bottom surface of the recessed gate 750 is positioned adjacent the negatively slopped lower sidewall 107 b .
- a depth of the recessed gate 750 is dependent on the type of a semiconductor device. Therefore, in the formation of the isolation trench 107 , the location of adjoining point of the positively slopped upper sidewall 107 a and the negatively slopped lower sidewall 107 b can be controlled so that the bottom surface of the recessed gate 750 may be placed adjacent the negatively slopped lower sidewall 107 b.
- the trench isolation layer 370 ( FIG. 5 f , FIG. 6 c ) is formed such that at least its lower sidewall 105 a ( FIG. 5 f ), 107 b ( FIG. 6 c ) has a negative slope, and the bottom surface of the recessed gate 750 is placed adjacent the negatively slopped lower sidewall 105 a ( FIG. 5 f ), 107 b ( FIG. 6 c ).
- a sharp tip (referring to 17 a of FIG. 3 ) is not generated between the recessed gate 750 and the trench isolation layer 370 . Therefore, when the MOS transistor with the recessed gate 750 works, a channel is formed only under the recessed gate 750 .
Abstract
A MOS transistor with a recessed gate and a method of fabricating the same: The MOS transistor comprises a semiconductor substrate, and a trench isolation layer located in a predetermined region of the semiconductor substrate for defining an active region. The trench isolation layer has a negative slope on at least a lower sidewall thereof. A recessed gate is located in a predetermined region of the active region, and a bottom surface of the recessed gate is placed adjacent the negatively slopped sidewall of the trench isolation layer.
Description
- This application is a Divisional of U.S. patent application Ser. No. 10/884,223, filed on Jul. 1, 2004, now pending, which claims the benefit of Korean Patent Application No. 2003-0056264, filed on Aug. 13, 2003, the disclosure of which is hereby incorporated herein by reference in its entirety.
- 1. Field of the Invention
- The present invention relates to a semiconductor device and a method of fabricating the same and, more particularly, to a MOS transistor with a recessed gate and a method of fabricating the same.
- 2. Description of the Related Art
- In general when the length of a transistor gate is reduced to a level approaching 0.1 μm or thereabout, several problems can occur. The problems that occur include rolling off of the threshold voltage, decrease of the punch-through voltage due to a short channel effect (SCE) and so on. In order to suppress the short channel effect, one can (a) reduce the junction depth of a source and a drain, or (b) increase the effective channel length. The structure of a metal oxide semiconductor (MOS) transistor with a recessed gate is such that it allows one to implement both of the above listed methods at the same time.
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FIG. 1 is a plan view of a typical MOS transistor with a recessed gate. Referring toFIG. 1 , anactive region 11 is defined by atrench isolation layer 11 a formed in a semiconductor substrate. Arecessed gate 30 is formed to intersect theactive region 11. One portion of theactive region 11 adjacent to thegate 30 is asource region 13, and another portion of theactive region 11 at the other side ofgate 30 is adrain region 15. One portion of theactive region 11 which is overlapped by thegate 30 is achannel region 17. -
FIGS. 2 and 3 are sectional views which illustrate the structure of the MOS transistor taken along the lines of I-I′ and II-II′ ofFIG. 1 respectively. Referring toFIG. 2 , therecessed gate 30 is located in a shallow trench formed in asemiconductor substrate 10. The active regions adjacent to therecessed gate 30 are thesource region 13 and thedrain region 15, and the active region under therecessed gate 30 is thechannel region 17. Agate insulating layer 20 is interposed between therecessed gate 30 and thechannel region 17. The depth of therecessed gate 30 is deeper than the depth of the source/drain region - Referring to
FIG. 3 , thechannel region 17 is located between thetrench isolation layers 11 a. The source region 13 (FIG. 1 ) and the drain region 15 (FIG. 1 ) are located at the front and the back of thechannel region 17 respectively, and therecessed gate 30 is located on thechannel region 17. As shown in the drawing, therecessed gate 30 has a positive slopped sidewall and thetrench isolation layers 11 a also have a positive slopped sidewall. As a result, as shown inFIG. 3 , the above structure creates asharp tip 17 a in thechannel region 17 at which therecessed gate 30 and thetrench isolation layer 11 a adjoin each other. Referring toFIG. 1 , thesharp tip 17 a is formed along the boundary between thechannel region 17 and thetrench isolation layer 11 a. As a result, when such a MOS transistor works, a channel is formed not only under therecessed gate 30, and but also in thesharp tip 17 a. The channel formed in thesharp tip 17 a can reduce the effective channel length of the MOS transistor with therecessed gate 30. Therefore, the MOS transistor with the recessed gate may result in a failure to suppress the short channel effect. - Exemplary embodiments of the present invention provide a MOS transistor with a recessed gate structured for suppressing the reduction of effective channel length. The present invention also provides a method of fabricating a MOS transistor with a recessed gate structured to suppress the reduction of effective channel length.
- According to one embodiment, the present invention provides a MOS transistor which includes a semiconductor substrate, and a trench isolation layer located in a predetermined region of the semiconductor substrate for defining an active region. The trench isolation layer has a negative slope on at least a lower sidewall thereof. A recessed gate is located in a predetermined region of the active region, and a bottom surface of the recessed gate is placed adjacent or contacts the negatively slopped sidewall of the trench isolation layer.
- The overall sidewall including the lower sidewall of the trench isolation layer may have a negative slope. However, alternatively, the trench isolation layer may have a positive slope on its upper sidewall and a negative slop on the lower sidewall. The trench isolation layer is preferably formed of high-density plasma chemical vapor deposition (HDP-CVD) insulating layer.
- A gate insulating layer may be interposed between the recessed gate and the active region and the recessed gate may be formed of polysilicon.
- The present invention provides a method of fabricating a MOS transistor. The method comprises first preparing a semiconductor substrate. An isolation trench having a negative slope on at least a lower sidewall is formed in a predetermined region of the semiconductor substrate to define an active region. The isolation trench is filled with an insulating layer, and the semiconductor substrate having the isolation trench filled with the insulating layer is polished by using a CMP so as to form a trench isolation layer. A recessed gate is formed in a predetermined region of the active region, and a bottom surface of the recessed gate is placed adjacent or contacts the negatively slopped lower sidewall of the trench isolation layer.
- The isolation trench may be formed so as to have a negative slope on the overall sidewall including the lower sidewall. Alternatively, the isolation trench may be formed to have a positive slope on its upper sidewall and a negative slope on its lower sidewall.
- In the process of forming the isolation trench, negative-slope etching may be employed when the sidewall is formed. The negative-slope etching may be performed by a dry etching or a wet etching. The dry etching may be performed by using a substrate etching gas including NF3 and SF6.
- Before the isolation trench is filled with the insulating layer, a liner is preferably formed inside the isolation trench. The filling of the isolation trench with the insulating layer may include partially filling the isolation trench with a first insulating layer. The first insulating layer is anisotropically etched to form an insulating spacer on the negatively slopped lower sidewall of the isolation trench. The isolation trench having the insulating spacer is substantially completely filled with a second insulating layer.
- The first and second insulating layer is can be formed of an HDP-CVD insulating layers. The anisotropically etching of the first insulating layer can be performed by using a reactive ion etching (RIE) process. The insulating spacer can be formed to cover at least the negatively slopped lower sidewall.
- In the process of forming the recessed gate, a channel trench may be formed in a predetermined region of the active region such that the bottom surface of the channel trench contacts a negatively slopped lower sidewall of the trench isolation layer. A gate insulating layer is formed on the bottom surface of the channel trench, and a gate conductive layer is formed on the gate insulating layer to fill the channel trench. Then, the gate conductive layer is patterned. Before forming the gate insulating layer, it is preferable to include a process of performing a channel ion implantation process onto the channel trench. The gate conductive layer may be formed of polysilicon.
- 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 preferred embodiments thereof with reference to the attached drawings in which:
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FIG. 1 is a plane view of a typical MOS transistor with a recessed gate; -
FIG. 2 is a sectional view to illustrate the structure of a MOS transistor taken along the line of I-I′ ofFIG. 1 ; -
FIG. 3 is a sectional view to illustrate the structure of a MOS transistor taken along the line of II-II′ ofFIG. 1 ; -
FIG. 4 is a plane view to illustrate a part of a typical DRAM cell array region employing a MOS transistor with a recessed gate; -
FIGS. 5 a to 5 f are sectional views to illustrate a method of fabricating a MOS transistor according to a first embodiment of the present invention taken along the line of I-I′ ofFIG. 4 ; and -
FIGS. 6 a to 6 c are sectional views to illustrate a method of fabricating a MOS transistor according to a second embodiment of the present invention taken along the line of I-I′ ofFIG. 4 . - The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in different forms and the invention should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the thickness of layers and regions are exaggerated for clarity. Like numbers refer to like elements throughout the specification.
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FIG. 4 is a plan view of a part of a typical DRAM cell array region employing a MOS transistor with a recessed gate. Referring toFIG. 4 , anactive region 300 is defined by a trench isolation layer located in a semiconductor substrate. Aword line 700 intersects theactive region 300. A portion of theactive region 300, adjacent to theword line 700, is asource region 380, and another portion of theactive region 300, on the other opposite side to thesource region 380, is adrain region 370. Further, a portion of theactive region 300, overlapped by theword line 700, is achannel region 390. Thechannel region 390 is recessed into the semiconductor substrate, and a recessedgate 750, which is a part of theword line 700, is located on the recessedchannel region 390. -
FIGS. 5 a to 5 f are sectional views to illustrate the processing sequences of a method of fabricating a MOS transistor according to a first embodiment of the present invention taken along the line of I-I′ ofFIG. 4 . - Referring to
FIG. 5 a, ahard mask pattern 200 including apad oxide layer 210, a polishingstop layer 230, and anoxide layer 250 are sequentially stacked on asemiconductor substrate 100. Thehard mask pattern 200 exposes a portion of asemiconductor substrate 100. - The
pad oxide layer 210 functions as a buffer layer for alleviating the stress applied on thesubstrate 100, which occurs during the formation of the polishingstop layer 230 on thesubstrate 100. Thepad oxide layer 210 can be formed of a thermal oxide layer to a thickness of 20 to 200 Å. The polishingstop layer 230 is used as a polishing stop point during a subsequent chemical mechanical polishing (CMP) process, and it may be formed of silicon nitride. The polishingstop layer 230 is formed to a thickness of several hundreds to approximately 1000 Å. Theoxide layer 250 is formed so that thehard mask pattern 200 including theoxide layer 250 has a uniform pattern width. Theoxide layer 250 can be omitted. - Referring to
FIG. 5 b, anisolation trench 105 is formed by etching the exposed portion of thesubstrate 100 so as to define anactive region 106. Theactive region 106 corresponds to thechannel region 390 ofFIG. 4 . Theisolation trench 105 is formed so as to have a negative slope at least on its lower sidewall. In this embodiment, theoverall sidewall 105 a of theisolation trench 105 is formed to have a negative slope. As used herein the phrase, “the sidewall of isolation trench has a negative slope” may mean that the width of theisolation trench 105 surrounded by the sidewall is increased toward the lower portion of theisolation trench 105. - The
isolation trench 105 is formed using a negative-slope etching so that thesidewall 105 a has a negative slope. The negative-slope etching can be performed by dry etching or by a wet etching, but dry etching is preferable. Furthermore, in the dry etching, it is preferable to employ a substrate etching gas including NF3 and SF6. - Referring to
FIG. 5 c, a thermal oxide layer (not shown) is preferably formed on the bottom and the sidewall of theisolation trench 105 by performing a thermal treatment on thesubstrate 100 having theisolation trench 105 formed therein. The thermal oxide layer cures the damage to thesubstrate 100 when theisolation trench 105 is formed. - A
liner 320 can be formed on thesubstrate 100 having the thermal oxide layer. Theliner 320 covers the sidewall and the bottom surface of theisolation trench 105. Theliner 320 is a layer having excellent oxidation-resistant characteristics. Theliner 320 can be a nitride layer, for example. - A first insulating
layer 330 is formed to partially fill theisolation trench 105 having theliner 320. The first insulatinglayer 330 may be a layer having an excellent gap-fill characteristic. Preferably, the first insulatinglayer 330 is formed of HDP-CVD insulating layer. Preferably, a HDP-CVD insulating layer is a HDP-CVD oxide layer, The HDP-CVD oxide layer is known to have an excellent gap-fill characteristic. - Referring to
FIG. 5 d, the first insulatinglayer 330 is anisotropically etched to form an insulatingspacer 335 on the negatively sloppedsidewall 105 a. During that time, the bottom surface of theisolation trench 105 may be exposed. The etching of the first insulatinglayer 330 is preferably performed by using an RIE process. Further, the insulatingspacer 335 is preferably formed to cover the negatively sloppedsidewall 105 a. - A second insulating
layer 350 is formed on thesubstrate 100 such that the insulatingspacer 335 substantially completely fills theisolation trench 105. The secondinsulating layer 350 is also a layer having an excellent gap-fill characteristic. Preferably, the second insulatinglayer 350 is HDP-CVD insulating layer. Preferably, HDP-CVD insulating layer is formed of HDP-CVD oxide. - In general, the isolation trench is formed such that its sidewall has a positive slope. That is, the isolation trench is formed such that its width surrounded by the sidewall is decreased as it goes further toward the lower portion of the
isolation trench 105, thereby minimizing the generation of voids when theisolation trench 105 is filled with an insulating layer. If theisolation trench 105 is formed such that the overall sidewall of the isolation trench has a negative slope, the voids may be generated when theisolation trench 105 is filled with an insulating layer. - Therefore, as described above, the insulating
spacer 335 is formed on the negatively sloppedsidewall 105 a of theisolation trench 105 such that the width of the opening in theisolation trench 105, left by the insulatingspacer 335, is reduced toward the lower portion of theisolation trench 105. As a result, theisolation trench 105 can be filled with the second insulatinglayer 350 without voids. - Referring to
FIG. 5 e, thesubstrate 100 having the isolation trench filled with the second insulatinglayer 350 is planarized through a CMP process so as to expose the polishingstop layer 230. Then, atrench isolation layer 370 is formed by removing the exposed polishingstop layer 230 and thepad insulating layer 210 under the polishingstop layer 230. - Then, a
photoresist pattern 400 is formed on thesubstrate 100 having thetrench isolation layer 370 to expose the active region of thesubstrate 100, that is, achannel region 106. The exposedchannel region 106 is etched using thephotoresist pattern 400 as an etch mask to form achannel trench 600, and the bottom surface of thechannel trench 600 is formed adjacent the negatively sloppedsidewall 105 a of thetrench isolation layer 370. Thechannel trench 600 is preferably formed by using a de-coupled plasma source (DPS). - Next, a channel ion implantation into the
channel trench 600 is performed using thephotoresist pattern 400 as a mask. The channel ion implantation is performed to control a threshold voltage as known in the art. - Referring to
FIG. 5 f, thephotoresist pattern 400 is removed to expose the top portion of thetrench isolation layer 370. Next, thesubstrate 100 is thermally oxidized to form agate insulating layer 500 on the bottom surface of thechannel trench 600. A gate conductive layer is formed on thegate insulating layer 500 to fill thechannel trench 600. The gate conductive layer may be formed of polysilicon. Then, the gate conductive layer is patterned to form a recessedgate 750, whereby the source region 380 (FIG. 4 ) and the drain region 370 (FIG. 4 ) is exposed. A bottom surface of the recessedgate 750 is located adjacent the negatively sloppedsidewall 105 a. The recessedgate 750 is extended on thetrench isolation layer 370 to form aword line 700. - Finally, the formation of the MOS transistor is completed by performing an ion implantation process onto the exposed source region 380 (
FIG. 4 ) and the exposed drain region 370 (FIG. 4 ), which are located on the front and the back of thechannel region 106, respectively. -
FIGS. 6 a to 6 c are sectional views to illustrate a method of fabricating a MOS transistor according to a second embodiment of the present invention taken along line of I-I′ ofFIG. 4 . The method of fabricating the MOS transistor according to a second embodiment of the present invention is the same as the method explained in the first embodiment except the explanation to be described as follows. - Referring to
FIG. 6 a, thesemiconductor substrate 100 is etched to form anisolation trench 107, using thehard mask patterns 200 formed on thesubstrate 100, and at the same time, an active region i.e.channel region 108 is defined. Thehard mask patterns 200 include apad oxide layer 210, a polishingstop layer 230, and anoxide layer 250, which are sequentially stacked. Theisolation trench 107 is formed to have a negative slope at least on its lower sidewall. In this embodiment, theisolation trench 107 is formed to have a positive slope on itsupper sidewall 107 a and a negative slope on the rest of its sidewall, i.e.,lower sidewall 107 b. The formation of the negative slope on thelower sidewall 107 b is preferably made by using a negative-slope etching as described in the first embodiment. - Referring to
FIG. 6 b, preferably, thesubstrate 100 having theisolation trench 107 is thermally treated to form a thermal oxide layer (not shown) on the bottom and the sidewall of theisolation trench 107. Aliner 320 can be formed on thesubstrate 100 having the thermal oxide layer. Then, a first insulating layer is formed on theliner 320 to partially fill theisolation trench 107. The first insulating layer is anisotropically etched to form an insulatingspacer 335 on the negatively sloppedlower sidewall 107 b. The bottom surface of theisolation trench 107 may be exposed at the same time. The insulatingspacer 335 is preferably formed to cover at least the negatively sloppedlower sidewall 107 b. The anisotropically etching of the first insulating layer is performed by using a RIE process. - Then, a second insulating
layer 350 is formed on thesubstrate 100 having the insulatingspacer 335 to substantially completely fill theisolation trench 107. When forming the insulatingspacer 335 on the negatively sloppedlower sidewall 107 b of theisolation trench 107, the width of the opening left in theisolation trench 107 by the insulatingspacer 335 is formed so as to be reduced toward the lower portion of theisolation trench 107. Therefore, the possibility of the void generation is reduced, and theisolation trench 107 can be filled with the second insulatinglayer 350 without voids. - Referring to
FIG. 6 c, thesubstrate 100 having the second insulatinglayer 350, is planarized using a chemical mechanical polishing (CMP) process to expose the polishingstop layer 230. Then, the exposed polishingstop layer 230 and thepad insulating layer 210 under the exposed polishingstop layer 230 are removed to form atrench isolation layer 370. - A channel trench is formed in a predetermined region of the active region i.e.
channel region 108 of thesubstrate 100 having thetrench isolation layer 370. The channel trench is formed such that its bottom surface is located adjacent the negatively sloppedlower sidewall 107 b of thetrench isolation layer 370. The channel trench is preferably formed by using a de-coupled plasma source (DPS). - A
gate insulating layer 500 is formed on the bottom surface of the channel trench. A gate conductive layer is formed on thegate insulating layer 500 to fill the channel trench. By patterning the gate conductive layer to form a recessedgate 750, the source region 380 (FIG. 4 ) and the drain region 370 (FIG. 4 ) are exposed. The recessedgate 750 is extended on thetrench isolation layer 370 to form aword line 700. - A bottom surface of the recessed
gate 750 is positioned adjacent the negatively sloppedlower sidewall 107 b. In general, a depth of the recessedgate 750 is dependent on the type of a semiconductor device. Therefore, in the formation of theisolation trench 107, the location of adjoining point of the positively sloppedupper sidewall 107 a and the negatively sloppedlower sidewall 107 b can be controlled so that the bottom surface of the recessedgate 750 may be placed adjacent the negatively sloppedlower sidewall 107 b. - As described above, the trench isolation layer 370 (
FIG. 5 f,FIG. 6 c) is formed such that at least its lower sidewall 105 a (FIG. 5 f), 107 b (FIG. 6 c) has a negative slope, and the bottom surface of the recessedgate 750 is placed adjacent the negatively slopped lower sidewall 105 a (FIG. 5 f), 107 b (FIG. 6 c). As a result, a sharp tip (referring to 17 a ofFIG. 3 ) is not generated between the recessedgate 750 and thetrench isolation layer 370. Therefore, when the MOS transistor with the recessedgate 750 works, a channel is formed only under the recessedgate 750. Consequently, the reduction of an effective channel length due to the sharp tip (referring to 17 a ofFIG. 3 ) can be avoided. Furthermore, a short channel effect such as rolling off of a threshold voltage of a MOS transistor, or punch through can be effectively suppressed. - While the present invention has been particularly shown and described with reference to an exemplary embodiment thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents.
Claims (15)
1. A method of fabricating a MOS transistor comprising:
a) preparing a semiconductor substrate;
b) forming an isolation trench having a negative slope on at least a lower sidewall in the semiconductor substrate to define an active region therein;
c) filling the isolation trench with an insulating layer;
d) planarizing the semiconductor substrate having the isolation trench filled with the insulating layer so as to form a trench isolation layer; and
e) forming a recessed gate in the active region, a bottom surface of the recessed gate adjacent the negatively slopped lower sidewall of the trench isolation layer.
2. The method of fabricating a MOS transistor according to claim 1 , wherein forming the isolation trench is performed such that the isolation trench has a negative slope on the overall sidewall including the lower sidewall.
3. The method of fabricating a MOS transistor according to claim 1 , wherein forming the isolation trench is performed such that the isolation trench has a positive slope on an upper sidewall and a negative slope on the lower sidewall.
4. The method of fabricating a MOS transistor according to claim 1 , wherein forming the isolation trench is performed by using a negative-slope etching such that the sidewall has a negative slope.
5. The method of fabricating a MOS transistor according to claim 4 , wherein the negative-slope etching is performed using a dry etching or wet etching process.
6. The method of fabricating a MOS transistor according to claim 5 , wherein the dry etching is performed using a etching gas including NF3 and SF6.
7. The method of fabricating a MOS transistor according to claim 1 , further comprising forming a liner inside the isolation trench, before filling the isolation trench with the insulating layer.
8. The method of fabricating a MOS transistor according to claim 1 , wherein filling the isolation trench with the insulating layer comprises:
i) partially filling the isolation trench with a first insulating layer;
ii) etching anisotropically the first insulating layer to form an insulating spacer on at least a portion of the negatively slopped lower sidewall of the isolation trench; and
iii) filling the isolation trench having the insulating spacer therein with a second insulating layer.
9. The method of fabricating a MOS transistor according to claim 8 , wherein the first insulating layer is formed of HDP-CVD insulating layer.
10. The method of fabricating a MOS transistor according to claim 8 , wherein the second insulating layer is formed of HDP-CVD insulating layer.
11. The method of fabricating a MOS transistor according to claim 8 , wherein the step of etching anisotropically the first insulating layer is performed using a RIE process.
12. The method of fabricating a MOS transistor according to claim 8 , wherein the insulating spacer is formed to cover at least a portion of the negatively slopped lower sidewall.
13. The method of fabricating a MOS transistor according to claim 1 , wherein forming the recessed gate comprises:
i) forming a channel trench in a predetermined region of the active region such that a bottom surface of the channel trench is placed adjacent a negatively slopped lower sidewall of the trench isolation layer;
ii) forming a gate insulating layer on the bottom surface of the channel trench;
iii) forming a gate conductive layer on the gate insulating layer to fill the channel trench; and
iv) patterning the gate conductive layer.
14. The method of fabricating a MOS transistor according to claim 13 , further comprising performing a channel ion implantation process onto the channel trench before forming the gate insulating layer.
15. The method of fabricating a MOS transistor according to claim 13 , wherein the gate conductive layer is formed of polysilicon.
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US11/562,138 US20070093021A1 (en) | 2003-08-13 | 2006-11-21 | Mos transistor with recessed gate and method of fabricating the same |
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KR2003-56264 | 2003-08-13 | ||
US10/884,223 US7157770B2 (en) | 2003-08-13 | 2004-07-01 | MOS transistor with recessed gate and method of fabricating the same |
US11/562,138 US20070093021A1 (en) | 2003-08-13 | 2006-11-21 | Mos transistor with recessed gate and method of fabricating the same |
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US11/562,251 Abandoned US20070090435A1 (en) | 2003-08-13 | 2006-11-21 | Mos transistor with recessed gate and method of fabricating the same |
US11/562,138 Abandoned US20070093021A1 (en) | 2003-08-13 | 2006-11-21 | Mos transistor with recessed gate and method of fabricating the same |
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Families Citing this family (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7326619B2 (en) * | 2003-08-20 | 2008-02-05 | Samsung Electronics Co., Ltd. | Method of manufacturing integrated circuit device including recessed channel transistor |
US7306552B2 (en) * | 2004-12-03 | 2007-12-11 | Samsung Electronics Co., Ltd. | Semiconductor device having load resistor and method of fabricating the same |
KR100663363B1 (en) * | 2005-06-10 | 2007-01-02 | 삼성전자주식회사 | Recessed transistors removing fence of semiconductor substrate on sidewall of device isolation layer and methods of forming the same |
KR100641944B1 (en) * | 2005-07-21 | 2006-11-02 | 주식회사 하이닉스반도체 | Transistor of semiconductor device and method for forming the same |
US7223650B2 (en) * | 2005-10-12 | 2007-05-29 | Intel Corporation | Self-aligned gate isolation |
US7902597B2 (en) | 2006-03-22 | 2011-03-08 | Samsung Electronics Co., Ltd. | Transistors with laterally extended active regions and methods of fabricating same |
KR100745934B1 (en) | 2006-06-30 | 2007-08-02 | 주식회사 하이닉스반도체 | Semiconductor device and method for forming the same |
US9748341B2 (en) | 2013-07-02 | 2017-08-29 | General Electric Company | Metal-oxide-semiconductor (MOS) devices with increased channel periphery |
US9024328B2 (en) | 2013-07-02 | 2015-05-05 | General Electric Company | Metal-oxide-semiconductor (MOS) devices with increased channel periphery and methods of manufacture |
US9646871B2 (en) * | 2014-07-22 | 2017-05-09 | Taiwan Semiconductor Manufacturing Company Ltd. | Semiconductor structure with shallow trench isolation and manufacturing method thereof |
US10546937B2 (en) | 2017-11-21 | 2020-01-28 | Taiwan Semiconductor Manufacturing Co., Ltd. | Structures and methods for noise isolation in semiconductor devices |
US10546770B2 (en) * | 2018-05-02 | 2020-01-28 | Varian Semiconductor Equipment Associates, Inc. | Method and device isolation structure in finFET |
CN117637816A (en) * | 2018-05-31 | 2024-03-01 | 长江存储科技有限责任公司 | Semiconductor device and method for manufacturing the same |
Citations (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4551743A (en) * | 1980-08-29 | 1985-11-05 | Tokyo Shibaura Denki Kabushiki Kaisha | Semiconductor integrated circuit with isolation region made of dielectric material |
US4845048A (en) * | 1986-06-12 | 1989-07-04 | Matsushita Electric Industrial Co., Ltd. | Method of fabricating semiconductor device |
US5264382A (en) * | 1990-03-20 | 1993-11-23 | Fujitsu Limited | Method of producing semiconductor device using dummy gate structure |
US5891807A (en) * | 1997-09-25 | 1999-04-06 | Siemens Aktiengesellschaft | Formation of a bottle shaped trench |
US5915192A (en) * | 1997-09-12 | 1999-06-22 | Taiwan Semiconductor Manufacturing Co., Ltd. | Method for forming shallow trench isolation |
US5933749A (en) * | 1997-10-27 | 1999-08-03 | United Microelectronics Corp. | Method for removing a top corner of a trench |
US6261957B1 (en) * | 1999-08-20 | 2001-07-17 | Taiwan Semiconductor Manufacturing Company | Self-planarized gap-filling by HDPCVD for shallow trench isolation |
US6277707B1 (en) * | 1998-12-16 | 2001-08-21 | Lsi Logic Corporation | Method of manufacturing semiconductor device having a recessed gate structure |
US6313008B1 (en) * | 2001-01-25 | 2001-11-06 | Chartered Semiconductor Manufacturing Inc. | Method to form a balloon shaped STI using a micro machining technique to remove heavily doped silicon |
US20020019113A1 (en) * | 2000-08-02 | 2002-02-14 | Samsung Electronics, Co., Ltd. | Method for self-aligned shallow trench isolation and method of manufacturing non-volatile memory device comprising the same |
US20020072197A1 (en) * | 2000-07-25 | 2002-06-13 | Samsung Electronics Co., Ltd. | Method for self-aligned shallow trench isolation and method of manufacturing non-volatile memory device using the same |
US6465842B2 (en) * | 1998-06-25 | 2002-10-15 | Kabushiki Kaisha Toshiba | MIS semiconductor device and method of fabricating the same |
US6627514B1 (en) * | 1999-11-12 | 2003-09-30 | Samsung Electronics Co., Ltd. | Semiconductor device having a Y-shaped isolation layer and simplified method for manufacturing the Y-shaped isolation layer to prevent divot formation |
US20040099906A1 (en) * | 2002-11-26 | 2004-05-27 | Mosel Vitelic Corporation | Trench isolation without grooving |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR100341480B1 (en) * | 2000-05-26 | 2002-06-21 | 윤종용 | Method for self-aligned shallow trench isolation |
KR100578656B1 (en) * | 2003-06-30 | 2006-05-11 | 에스티마이크로일렉트로닉스 엔.브이. | Method for forming a floating gate in flash memory device |
US20050202638A1 (en) * | 2004-03-11 | 2005-09-15 | Jia-Wei Yang | Method of reducing step height |
-
2003
- 2003-08-13 KR KR10-2003-0056264A patent/KR100487657B1/en not_active IP Right Cessation
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2004
- 2004-07-01 US US10/884,223 patent/US7157770B2/en not_active Expired - Fee Related
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2006
- 2006-11-21 US US11/562,251 patent/US20070090435A1/en not_active Abandoned
- 2006-11-21 US US11/562,138 patent/US20070093021A1/en not_active Abandoned
Patent Citations (15)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4551743A (en) * | 1980-08-29 | 1985-11-05 | Tokyo Shibaura Denki Kabushiki Kaisha | Semiconductor integrated circuit with isolation region made of dielectric material |
US4845048A (en) * | 1986-06-12 | 1989-07-04 | Matsushita Electric Industrial Co., Ltd. | Method of fabricating semiconductor device |
US5264382A (en) * | 1990-03-20 | 1993-11-23 | Fujitsu Limited | Method of producing semiconductor device using dummy gate structure |
US5915192A (en) * | 1997-09-12 | 1999-06-22 | Taiwan Semiconductor Manufacturing Co., Ltd. | Method for forming shallow trench isolation |
US5891807A (en) * | 1997-09-25 | 1999-04-06 | Siemens Aktiengesellschaft | Formation of a bottle shaped trench |
US5933749A (en) * | 1997-10-27 | 1999-08-03 | United Microelectronics Corp. | Method for removing a top corner of a trench |
US6465842B2 (en) * | 1998-06-25 | 2002-10-15 | Kabushiki Kaisha Toshiba | MIS semiconductor device and method of fabricating the same |
US6277707B1 (en) * | 1998-12-16 | 2001-08-21 | Lsi Logic Corporation | Method of manufacturing semiconductor device having a recessed gate structure |
US6261957B1 (en) * | 1999-08-20 | 2001-07-17 | Taiwan Semiconductor Manufacturing Company | Self-planarized gap-filling by HDPCVD for shallow trench isolation |
US6627514B1 (en) * | 1999-11-12 | 2003-09-30 | Samsung Electronics Co., Ltd. | Semiconductor device having a Y-shaped isolation layer and simplified method for manufacturing the Y-shaped isolation layer to prevent divot formation |
US20020072197A1 (en) * | 2000-07-25 | 2002-06-13 | Samsung Electronics Co., Ltd. | Method for self-aligned shallow trench isolation and method of manufacturing non-volatile memory device using the same |
US20020019113A1 (en) * | 2000-08-02 | 2002-02-14 | Samsung Electronics, Co., Ltd. | Method for self-aligned shallow trench isolation and method of manufacturing non-volatile memory device comprising the same |
US6548374B2 (en) * | 2000-08-02 | 2003-04-15 | Samsung Electronics Co., Ltd. | Method for self-aligned shallow trench isolation and method of manufacturing non-volatile memory device comprising the same |
US6313008B1 (en) * | 2001-01-25 | 2001-11-06 | Chartered Semiconductor Manufacturing Inc. | Method to form a balloon shaped STI using a micro machining technique to remove heavily doped silicon |
US20040099906A1 (en) * | 2002-11-26 | 2004-05-27 | Mosel Vitelic Corporation | Trench isolation without grooving |
Also Published As
Publication number | Publication date |
---|---|
US20050035427A1 (en) | 2005-02-17 |
US7157770B2 (en) | 2007-01-02 |
KR20050018187A (en) | 2005-02-23 |
US20070090435A1 (en) | 2007-04-26 |
KR100487657B1 (en) | 2005-05-03 |
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