US20090072299A1 - Semiconductor device having high voltage mos transistor and fabrication method thereof - Google Patents
Semiconductor device having high voltage mos transistor and fabrication method thereof Download PDFInfo
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- US20090072299A1 US20090072299A1 US12/273,272 US27327208A US2009072299A1 US 20090072299 A1 US20090072299 A1 US 20090072299A1 US 27327208 A US27327208 A US 27327208A US 2009072299 A1 US2009072299 A1 US 2009072299A1
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- 239000004065 semiconductor Substances 0.000 title claims abstract description 18
- 238000000034 method Methods 0.000 title abstract description 17
- 238000004519 manufacturing process Methods 0.000 title abstract description 7
- 239000000758 substrate Substances 0.000 claims abstract description 45
- 150000004767 nitrides Chemical class 0.000 abstract description 10
- 238000005516 engineering process Methods 0.000 description 10
- 229920002120 photoresistant polymer Polymers 0.000 description 8
- 230000015556 catabolic process Effects 0.000 description 6
- 238000005530 etching Methods 0.000 description 3
- 239000011810 insulating material Substances 0.000 description 3
- 125000006850 spacer group Chemical group 0.000 description 3
- 238000005468 ion implantation Methods 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 238000011982 device technology Methods 0.000 description 1
- 239000003989 dielectric material Substances 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000001259 photo etching Methods 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
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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
- H01L21/04—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
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- 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
- H01L29/40—Electrodes ; Multistep manufacturing processes therefor
- H01L29/41—Electrodes ; Multistep manufacturing processes therefor characterised by their shape, relative sizes or dispositions
- H01L29/423—Electrodes ; Multistep manufacturing processes therefor characterised by their shape, relative sizes or dispositions not carrying the current to be rectified, amplified or switched
- H01L29/42312—Gate electrodes for field effect devices
- H01L29/42316—Gate electrodes for field effect devices for field-effect transistors
- H01L29/4232—Gate electrodes for field effect devices for field-effect transistors with insulated gate
- H01L29/42364—Gate electrodes for field effect devices for field-effect transistors with insulated gate characterised by the insulating layer, e.g. thickness or uniformity
- H01L29/42368—Gate electrodes for field effect devices for field-effect transistors with insulated gate characterised by the insulating layer, e.g. thickness or uniformity the thickness being non-uniform
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- 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
- H01L29/66553—Unipolar field-effect transistors with an insulated gate, i.e. MISFET using inside spacers, permanent or not
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- 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
- H01L29/66659—Lateral single gate silicon transistors with asymmetry in the channel direction, e.g. lateral high-voltage MISFETs with drain offset region, extended drain MISFETs
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- 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
- H01L29/68—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
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S438/00—Semiconductor device manufacturing: process
- Y10S438/981—Utilizing varying dielectric thickness
Definitions
- the present invention relates generally to semiconductor integrated circuit (IC) technology and, more particularly, to a semiconductor device having a high voltage MOS transistor allowing an increase in breakdown and fabricated with a more simple process.
- IC semiconductor integrated circuit
- MOS metal oxide semiconductor
- FIGS. 1 to 4 are cross-sectional views showing a method of fabricating a conventional semiconductor device having a high voltage MOS transistor.
- a reference character “A” indicates a region where a high voltage MOS transistor is formed. Hereinafter, this region will be referred to as a high voltage region.
- a reference character “B” indicates a region where a low voltage MOS transistor is formed and which will be referred to as a low voltage region.
- a field area 3 is formed in a semiconductor substrate 1 , defining an active area.
- the substrate 1 is selectively etched to form a trench for the field area 3 .
- Suitable insulating material is deposited to fill the trench and then planarized.
- gate oxide layers are formed on the substrate 1 . That is, a relatively thick first gate oxide layer 5 is formed in the high voltage region (A), and a relatively thin second gate oxide layer 7 is formed in the low voltage region (B).
- a nitride layer is formed on the entire substrate 1 and removed from the high voltage region (A) by using typical photo etching process. Then the thick gate oxide layer 5 is thermally grown in the high voltage region. The remaining nitride layer is removed from the low voltage region (B), and the thin gate oxide layer 7 is thermally grown in the low voltage region.
- a gate conductive layer 9 , 11 is formed on the gate oxide layer 5 , 7 , and a first photoresist pattern 13 is formed thereon by using typical photo process.
- the first photoresist pattern 13 selectively exposes the high voltage region (A), fully covering the low voltage region (B).
- the gate conductive layer 9 in the high voltage region (A) is selectively etched until the first gate oxide layer 5 is exposed.
- the first photoresist pattern 13 is used as an etch mask.
- a first gate electrode 9 a is formed in the high voltage region (A).
- the first gate oxide layer 5 is selectively etched using the first photoresist pattern 13 as an etch mask.
- the first gate oxide layer 5 may partially remain after etching.
- the first gate oxide layer 5 is composed of an unetched portion 5 a under the first gate electrode 9 a and a partially etched portion 5 b remaining on the substrate 1 .
- the remaining gate oxide layer 5 b may act as a buffer layer during the subsequent ion implanting process.
- a low doping part 14 of a source/drain is formed in the substrate 1 through a shallow ion implantation.
- the first photoresist pattern 13 is removed, and a second photoresist pattern 15 is formed instead.
- the second photoresist pattern 15 selectively exposes the low voltage region (B), fully covering the high voltage region (A).
- the gate conductive layer 11 is selectively etched using the second photoresist pattern 15 as an etch mask, so a second gate electrode 11 a is formed in the low voltage region (B).
- spacers are formed on sidewalls of the gate electrodes 9 a and 11 a , and a high doping part of the source/drain is formed in the substrate 1 .
- FIG. 5 shows, in a cross-sectional view, a conventional MOS transistor in the high voltage region.
- the spacer 17 is formed on the sidewall of the gate electrode 9 a , and the source/drain 21 is formed in the substrate 1 .
- the source/drain 21 has the low doping part 14 and the high doping part 19 .
- Exemplary, non-limiting embodiments of the present invention provide a semiconductor device having a high voltage MOS transistor allowing an increase in breakdown, and also provide a related fabrication method with a more simple process.
- the method comprises forming a field area in a semiconductor substrate so as to define an active area in a high voltage region and a low voltage region, forming a nitride layer on the substrate, the nitride layer having an opening in the high voltage region, depositing an oxide layer over the substrate, anisotropically etching the oxide layer such that the oxide layer remains only on sidewalls of the opening, forming a first gate oxide layer on the substrate in the opening, removing the nitride layer, forming a second gate oxide layer over the substrate such that the second gate oxide layer has a relatively thinner thickness than the first gate oxide layer, forming gate electrodes in the high voltage region and the low voltage region, and forming source/drain around the gate electrodes in the active area of the substrate.
- the first gate oxide layer can have a thickness of 500 ⁇ 1500 ⁇ and the second gate oxide layer can have a thickness of 50 ⁇ 300 ⁇ .
- the method can further comprise, after the forming of the field area, forming a drift area in the substrate of the high voltage region.
- the semiconductor device comprises a semiconductor substrate having a field area defining an active area, a gate electrode disposed on the active area of the substrate, a gate oxide layer disposed between the gate electrode and the substrate on the active area, having relatively thick portions at edges thereof, and a source/drain formed around the gate electrode in the active area of the substrate.
- the device can further comprise a drift area formed in the substrate to surround the source/drain.
- the gate oxide layer can have a thickness of 500 ⁇ 1500 ⁇ .
- FIGS. 1 to 4 are cross-sectional views showing a method of fabricating a conventional semiconductor device having a high voltage MOS transistor.
- FIG. 5 is a cross-sectional view showing a conventional MOS transistor in a high voltage region.
- FIG. 6 is a cross-sectional view showing a MOS transistor in a high voltage region in accordance with an exemplary embodiment of the present invention.
- FIGS. 7 to 11 are cross-sectional views showing a method of fabricating a semiconductor device having a high voltage MOS transistor in accordance with an exemplary embodiment of the present invention.
- FIG. 6 is a cross-sectional view showing a MOS transistor in a high voltage region in accordance with an exemplary embodiment of the present invention.
- a field area 103 is formed in a semiconductor substrate 101 , defining an active area.
- a gate oxide layer 111 and a gate electrode 115 a are disposed in a stack on the active area of the substrate 101 , and a source/drain 117 a is formed around the gate electrode 115 a in the active area of the substrate 101 .
- the source/drain 117 a is surrounded with a drift area 105 in the substrate 101 .
- the gate oxide layer 111 has relatively thick portions 109 a at edges thereof. These thick portions 109 a allow an increase in breakdown between the gate electrode 115 a and the drain 117 a.
- FIGS. 7 to 11 are cross-sectional views showing a method of fabricating a semiconductor device having a high voltage MOS transistor in accordance with an exemplary embodiment of the present invention.
- reference characters “A” and “B” indicate a high voltage region and a low voltage region, respectively.
- the field area 103 is formed in the substrate 101 .
- a trench is formed in the substrate 101 by selective etching and filled with suitable insulating material deposited thereon. Then, the insulating material is planarized. While the field area 103 is formed, a thin first oxide layer 104 is simultaneously formed on the substrate 101 . Next, the drift area 105 is formed in the substrate 101 of the high voltage region (A).
- a nitride layer 107 is formed on the substrate 101 and selectively etched to form an opening 108 for the gate electrode in the high voltage region (A).
- a second oxide layer is fully deposited over the substrate 101 and anisotropically etched until the nitride layer 107 is exposed.
- the aforementioned thick portions 109 a of the gate oxide layer are formed in the shape of spacers on sidewalls of the opening 108 .
- the substrate 101 is subjected to thermal oxidation, and thereby the first gate oxide layer 111 is formed on the substrate 101 in the opening 108 .
- the first gate oxide layer 111 can be formed at a thickness of 500 ⁇ 1500 ⁇ .
- the nitride layer 107 and the first oxide layer 104 are completely removed.
- a second gate oxide layer 113 and a gate conductive layer are sequentially formed over the substrate 101 .
- the second gate oxide layer 113 has a relatively thinner thickness, for example, 50 ⁇ 300 ⁇ , in comparison with the first gate oxide layer 111 .
- the gate conductive layer is selectively etched, so the gate electrodes 115 a and 115 b are respectively formed in the high voltage region (A) and the low voltage region (B).
- the source/drain 117 a and 117 b are formed around the gate electrodes 115 a and 115 b in the active area of the substrate 101 .
- the thick portions of the first gate electrode in the high voltage region allow an increase in breakdown between the gate electrode and the drain. Additionally, the method of the invention becomes simpler since it does not require a process of partially removing a gate oxide layer, for a shallow ion implantation, in the high voltage region.
Abstract
A semiconductor device having a high voltage MOS transistor. The device includes a gate oxide layer disposed between a gate electrode and a substrate on an active area and having relatively thick portions at edges thereof. A fabrication method includes forming on the substrate is a nitride layer having an opening in a high voltage region. An oxide layer is deposited over the substrate and anisotropically etched to remain only on sidewalls of the opening. A first gate oxide layer is formed on the substrate in the opening, and the nitride layer is removed. Then a second gate oxide layer is formed over the substrate such that the second gate oxide layer has a relatively thinner thickness than the first gate oxide layer. Gate electrodes are then formed in the high voltage region and the low voltage region.
Description
- This U.S. non-provisional application claims priority under 35 U.S.C. §119 from Korean Patent Application No. 2004-117677, which was filed in the Korean Intellectual Property Office on Dec. 31, 2004, the contents of which are incorporated by reference herein in its entirety.
- 1. Field of the Invention
- The present invention relates generally to semiconductor integrated circuit (IC) technology and, more particularly, to a semiconductor device having a high voltage MOS transistor allowing an increase in breakdown and fabricated with a more simple process.
- 2. Description of the Related Art
- Dramatically growing semiconductor IC technology allows a variety of devices, such as transistors, capacitors and resistors, to be integrated in a single chip. Furthermore, various approaches to effectively embody such devices in the chip have been continuously studied and introduced in the art.
- For example, modern silicon device technology attempts to combine logic technology represented by a CPU (central processing unit) for data processing and memory technology for data storing. Furthermore, such attempts intend to combine analog technology and RF technology together with logic and memory technologies.
- In general, a transistor holds an important position common to logic and memory technologies. However, logic technology considers current drivability, whereas memory technology does reduced leakage current and improved breakdown voltage. Hence, it is required to effectively embody MOS (metal oxide semiconductor) transistors with different gate dielectrics in thickness on a single chip.
-
FIGS. 1 to 4 are cross-sectional views showing a method of fabricating a conventional semiconductor device having a high voltage MOS transistor. In the drawings, a reference character “A” indicates a region where a high voltage MOS transistor is formed. Hereinafter, this region will be referred to as a high voltage region. Similarly, a reference character “B” indicates a region where a low voltage MOS transistor is formed and which will be referred to as a low voltage region. - Referring to
FIG. 1 , afield area 3 is formed in asemiconductor substrate 1, defining an active area. In most cases, thesubstrate 1 is selectively etched to form a trench for thefield area 3. Suitable insulating material is deposited to fill the trench and then planarized. - Next, gate oxide layers are formed on the
substrate 1. That is, a relatively thick firstgate oxide layer 5 is formed in the high voltage region (A), and a relatively thin secondgate oxide layer 7 is formed in the low voltage region (B). Well-known various techniques may be used for forming thegate oxide layers entire substrate 1 and removed from the high voltage region (A) by using typical photo etching process. Then the thickgate oxide layer 5 is thermally grown in the high voltage region. The remaining nitride layer is removed from the low voltage region (B), and the thingate oxide layer 7 is thermally grown in the low voltage region. - Subsequently, a gate
conductive layer 9, 11 is formed on thegate oxide layer photoresist pattern 13 is formed thereon by using typical photo process. Thefirst photoresist pattern 13 selectively exposes the high voltage region (A), fully covering the low voltage region (B). - Next, referring to
FIG. 2 , the gate conductive layer 9 in the high voltage region (A) is selectively etched until the firstgate oxide layer 5 is exposed. Here, thefirst photoresist pattern 13 is used as an etch mask. As a result, afirst gate electrode 9 a is formed in the high voltage region (A). - Next, referring to
FIG. 3 , the firstgate oxide layer 5 is selectively etched using thefirst photoresist pattern 13 as an etch mask. Here, the firstgate oxide layer 5 may partially remain after etching. As a result, the firstgate oxide layer 5 is composed of anunetched portion 5 a under thefirst gate electrode 9 a and a partially etchedportion 5 b remaining on thesubstrate 1. The remaininggate oxide layer 5 b may act as a buffer layer during the subsequent ion implanting process. Alow doping part 14 of a source/drain is formed in thesubstrate 1 through a shallow ion implantation. - Next, referring to
FIG. 4 , the firstphotoresist pattern 13 is removed, and a secondphotoresist pattern 15 is formed instead. The secondphotoresist pattern 15 selectively exposes the low voltage region (B), fully covering the high voltage region (A). Then, the gateconductive layer 11 is selectively etched using thesecond photoresist pattern 15 as an etch mask, so a second gate electrode 11 a is formed in the low voltage region (B). - Thereafter, spacers are formed on sidewalls of the
gate electrodes 9 a and 11 a, and a high doping part of the source/drain is formed in thesubstrate 1. -
FIG. 5 shows, in a cross-sectional view, a conventional MOS transistor in the high voltage region. - Referring to
FIG. 5 , thespacer 17 is formed on the sidewall of thegate electrode 9 a, and the source/drain 21 is formed in thesubstrate 1. The source/drain 21 has thelow doping part 14 and the high doping part 19. - As discussed hereinbefore, to fabricate MOS transistors in both the high and low voltage regions requires additional processes such as partial removal of the first
gate oxide layer 5 in the high voltage region (A). Furthermore, undesirable breakdown may occur in aplace 25 between thegate electrode 9 a and thedrain 21 due to high electric field applied thereto. - Exemplary, non-limiting embodiments of the present invention provide a semiconductor device having a high voltage MOS transistor allowing an increase in breakdown, and also provide a related fabrication method with a more simple process.
- According to one exemplary embodiment of the present invention, the method comprises forming a field area in a semiconductor substrate so as to define an active area in a high voltage region and a low voltage region, forming a nitride layer on the substrate, the nitride layer having an opening in the high voltage region, depositing an oxide layer over the substrate, anisotropically etching the oxide layer such that the oxide layer remains only on sidewalls of the opening, forming a first gate oxide layer on the substrate in the opening, removing the nitride layer, forming a second gate oxide layer over the substrate such that the second gate oxide layer has a relatively thinner thickness than the first gate oxide layer, forming gate electrodes in the high voltage region and the low voltage region, and forming source/drain around the gate electrodes in the active area of the substrate.
- In the method, the first gate oxide layer can have a thickness of 500˜1500 Å and the second gate oxide layer can have a thickness of 50˜300 Å. The method can further comprise, after the forming of the field area, forming a drift area in the substrate of the high voltage region.
- According to one exemplary embodiment of the present invention, the semiconductor device comprises a semiconductor substrate having a field area defining an active area, a gate electrode disposed on the active area of the substrate, a gate oxide layer disposed between the gate electrode and the substrate on the active area, having relatively thick portions at edges thereof, and a source/drain formed around the gate electrode in the active area of the substrate.
- The device can further comprise a drift area formed in the substrate to surround the source/drain. In the device, the gate oxide layer can have a thickness of 500˜1500 Å.
-
FIGS. 1 to 4 are cross-sectional views showing a method of fabricating a conventional semiconductor device having a high voltage MOS transistor. -
FIG. 5 is a cross-sectional view showing a conventional MOS transistor in a high voltage region. -
FIG. 6 is a cross-sectional view showing a MOS transistor in a high voltage region in accordance with an exemplary embodiment of the present invention. -
FIGS. 7 to 11 are cross-sectional views showing a method of fabricating a semiconductor device having a high voltage MOS transistor in accordance with an exemplary embodiment of the present invention. - An exemplary, non-limiting embodiment of the present invention will now be described more fully hereinafter with reference to the accompanying drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the exemplary embodiment set forth herein. Rather, the disclosed embodiment is provided so that this disclosure will be thorough and complete, and will fully disclose the invention to those skilled in the art. The principles and features of this invention may be employed in varied and numerous embodiments without departing from the scope of the invention.
- In is noted that well-known structures and processes are not described or illustrated in detail to avoid obscuring the essence of the present invention. It is also noted that the figures are not drawn to scale.
-
FIG. 6 is a cross-sectional view showing a MOS transistor in a high voltage region in accordance with an exemplary embodiment of the present invention. - Referring to
FIG. 6 , afield area 103 is formed in asemiconductor substrate 101, defining an active area. Agate oxide layer 111 and agate electrode 115 a are disposed in a stack on the active area of thesubstrate 101, and a source/drain 117 a is formed around thegate electrode 115 a in the active area of thesubstrate 101. The source/drain 117 a is surrounded with adrift area 105 in thesubstrate 101. Thegate oxide layer 111 has relativelythick portions 109 a at edges thereof. Thesethick portions 109 a allow an increase in breakdown between thegate electrode 115 a and thedrain 117 a. -
FIGS. 7 to 11 are cross-sectional views showing a method of fabricating a semiconductor device having a high voltage MOS transistor in accordance with an exemplary embodiment of the present invention. Like previous drawings, reference characters “A” and “B” indicate a high voltage region and a low voltage region, respectively. - Referring to
FIG. 7 , after a well (not shown) is formed in thesubstrate 101, thefield area 103 is formed in thesubstrate 101. For example, to form thefield area 103, a trench is formed in thesubstrate 101 by selective etching and filled with suitable insulating material deposited thereon. Then, the insulating material is planarized. While thefield area 103 is formed, a thinfirst oxide layer 104 is simultaneously formed on thesubstrate 101. Next, thedrift area 105 is formed in thesubstrate 101 of the high voltage region (A). - Next, referring to
FIG. 8 , anitride layer 107 is formed on thesubstrate 101 and selectively etched to form anopening 108 for the gate electrode in the high voltage region (A). - Next, referring to
FIG. 9 , a second oxide layer is fully deposited over thesubstrate 101 and anisotropically etched until thenitride layer 107 is exposed. Hence, the aforementionedthick portions 109 a of the gate oxide layer are formed in the shape of spacers on sidewalls of theopening 108. - Next, referring to
FIG. 10 , thesubstrate 101 is subjected to thermal oxidation, and thereby the firstgate oxide layer 111 is formed on thesubstrate 101 in theopening 108. For example, the firstgate oxide layer 111 can be formed at a thickness of 500˜1500 Å. Thereafter, thenitride layer 107 and thefirst oxide layer 104 are completely removed. - Next, referring to
FIG. 11 , a secondgate oxide layer 113 and a gate conductive layer are sequentially formed over thesubstrate 101. The secondgate oxide layer 113 has a relatively thinner thickness, for example, 50˜300 Å, in comparison with the firstgate oxide layer 111. Then, the gate conductive layer is selectively etched, so thegate electrodes - Next, by using typical technique, the source/
drain gate electrodes substrate 101. - As discussed above, the thick portions of the first gate electrode in the high voltage region allow an increase in breakdown between the gate electrode and the drain. Additionally, the method of the invention becomes simpler since it does not require a process of partially removing a gate oxide layer, for a shallow ion implantation, in the high voltage region.
- While this invention has been particularly shown and described with reference to an exemplary embodiment thereof, it will be understood by those skilled 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.
Claims (4)
1-3. (canceled)
4. A semiconductor device comprising:
a semiconductor substrate having a field area defining an active area;
a gate electrode disposed on the active area of the substrate;
a gate oxide layer disposed between the gate electrode and the substrate on the active area, having relatively thick portions at edges thereof; and
a source/drain formed around the gate electrode in the active area of the substrate.
5. The device of claim 4 , further comprising:
a drift area formed in the substrate to surround the source/drain.
6. The device of claim 4 , wherein the gate oxide layer has a thickness of 500˜1500 Å.
Priority Applications (1)
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US12/273,272 US20090072299A1 (en) | 2004-12-31 | 2008-11-18 | Semiconductor device having high voltage mos transistor and fabrication method thereof |
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KR10-2004-0117677 | 2004-12-31 | ||
KR1020040117677A KR100628642B1 (en) | 2004-12-31 | 2004-12-31 | High Voltage MOS Transistor and Method for Forming the Same |
US11/320,859 US7468300B2 (en) | 2004-12-31 | 2005-12-30 | Semiconductor device having high voltage MOS transistor and fabrication method thereof |
US12/273,272 US20090072299A1 (en) | 2004-12-31 | 2008-11-18 | Semiconductor device having high voltage mos transistor and fabrication method thereof |
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US12/273,272 Abandoned US20090072299A1 (en) | 2004-12-31 | 2008-11-18 | Semiconductor device having high voltage mos transistor and fabrication method thereof |
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US10224407B2 (en) | 2017-02-28 | 2019-03-05 | Sandisk Technologies Llc | High voltage field effect transistor with laterally extended gate dielectric and method of making thereof |
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Also Published As
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KR20060079473A (en) | 2006-07-06 |
US20060148183A1 (en) | 2006-07-06 |
KR100628642B1 (en) | 2006-09-26 |
US7468300B2 (en) | 2008-12-23 |
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