US20040063311A1 - Structure of thin film transistor and manufacturing method thereof - Google Patents
Structure of thin film transistor and manufacturing method thereof Download PDFInfo
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- US20040063311A1 US20040063311A1 US10/259,137 US25913702A US2004063311A1 US 20040063311 A1 US20040063311 A1 US 20040063311A1 US 25913702 A US25913702 A US 25913702A US 2004063311 A1 US2004063311 A1 US 2004063311A1
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- 239000010409 thin film Substances 0.000 title claims abstract description 23
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 16
- 239000000758 substrate Substances 0.000 claims abstract description 25
- 238000000034 method Methods 0.000 claims abstract description 19
- 238000005530 etching Methods 0.000 claims abstract description 6
- 229910052814 silicon oxide Inorganic materials 0.000 claims description 52
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 39
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 26
- BPUBBGLMJRNUCC-UHFFFAOYSA-N oxygen(2-);tantalum(5+) Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ta+5].[Ta+5] BPUBBGLMJRNUCC-UHFFFAOYSA-N 0.000 claims description 26
- 229910001936 tantalum oxide Inorganic materials 0.000 claims description 26
- 239000000203 mixture Substances 0.000 claims description 22
- CSDREXVUYHZDNP-UHFFFAOYSA-N alumanylidynesilicon Chemical compound [Al].[Si] CSDREXVUYHZDNP-UHFFFAOYSA-N 0.000 claims description 18
- 239000011651 chromium Substances 0.000 claims description 18
- 239000010949 copper Substances 0.000 claims description 18
- 239000004065 semiconductor Substances 0.000 claims description 14
- 229910052581 Si3N4 Inorganic materials 0.000 claims description 13
- 229910020286 SiOxNy Inorganic materials 0.000 claims description 13
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims description 13
- -1 silicon oxide nitride Chemical class 0.000 claims description 13
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 9
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 9
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims description 9
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 9
- 229910052782 aluminium Inorganic materials 0.000 claims description 9
- 229910052804 chromium Inorganic materials 0.000 claims description 9
- 229910052802 copper Inorganic materials 0.000 claims description 9
- 229910052750 molybdenum Inorganic materials 0.000 claims description 9
- 239000011733 molybdenum Substances 0.000 claims description 9
- JZLMRQMUNCKZTP-UHFFFAOYSA-N molybdenum tantalum Chemical compound [Mo].[Ta] JZLMRQMUNCKZTP-UHFFFAOYSA-N 0.000 claims description 9
- MGRWKWACZDFZJT-UHFFFAOYSA-N molybdenum tungsten Chemical compound [Mo].[W] MGRWKWACZDFZJT-UHFFFAOYSA-N 0.000 claims description 9
- 238000001020 plasma etching Methods 0.000 claims description 9
- 229910052715 tantalum Inorganic materials 0.000 claims description 9
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 claims description 9
- 239000011521 glass Substances 0.000 claims description 7
- 229910021420 polycrystalline silicon Inorganic materials 0.000 claims description 7
- 230000005684 electric field Effects 0.000 description 3
- 230000005611 electricity Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 1
- 239000004973 liquid crystal related substance Substances 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
- H01L29/66007—Multistep manufacturing processes
- H01L29/66075—Multistep manufacturing processes of devices having semiconductor bodies comprising group 14 or group 13/15 materials
- H01L29/66227—Multistep manufacturing processes of devices having semiconductor bodies comprising group 14 or group 13/15 materials the devices being controllable only by the electric current supplied or the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched, e.g. three-terminal devices
- H01L29/66409—Unipolar field-effect transistors
- H01L29/66477—Unipolar field-effect transistors with an insulated gate, i.e. MISFET
- H01L29/66742—Thin film unipolar transistors
- H01L29/66772—Monocristalline silicon transistors on insulating substrates, e.g. quartz substrates
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
- H01L29/68—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by only the electric current supplied, or only the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched
- H01L29/76—Unipolar devices, e.g. field effect transistors
- H01L29/772—Field effect transistors
- H01L29/78—Field effect transistors with field effect produced by an insulated gate
- H01L29/786—Thin film transistors, i.e. transistors with a channel being at least partly a thin film
- H01L29/78645—Thin film transistors, i.e. transistors with a channel being at least partly a thin film with multiple gate
Definitions
- the present invention is related to a structure of a thin film transistor and a manufacturing method thereof, and more particularly to a structure of a thin film transistor applied to TFT-LCD and a manufacturing method thereof.
- TFT-LCD Thin film transistor liquid crystal Display
- TFT-LCD Drain of TFT has a higher electric field while TFT is operating, and there should be an off-state leakage current resulted while the device is shut down, thereby the application of TFT-LCD being limited.
- FIG. 1 illustrates a lightly doped drain structure of the prior art for solving the problem of the off-state leakage current.
- the structure includes an insulating substrate 11 , a source/drain layer 12 , a gate insulating layer 13 and a gate layer 14 , wherein the source/drain layer 12 further includes a drain 121 , a lightly doped drain 1211 , a channel 122 , a source 123 and a lightly doped source 1231 .
- the electric field of the drain 121 is reduced by means of adding lightly doped regions (i.e.
- the lightly doped drain 1211 and the lightly doped source 1231 corresponding to the original source 123 and the original drain 121 respectively near the channel 122 , so as to prevent from the leakage current.
- the TFT-LCD with the lightly doped regions is complex and hard to manufacture. Furthermore the resistance will increases because of the lightly doped degree. As result of the series resistance of the drain 121 and the source 123 increasing, the operating speed of the device reduces and the power dissipation increases.
- the present invention is attempted to improve the prior art and provides a structure of a thin film transistor applied to a TFT-LCD and a manufacturing method thereof for preventing TFT-LCD from the leakage current.
- the method for manufacturing a thin film transistor includes steps of providing an insulating substrate, sequentially forming a source/drain layer, a primary gate insulating layer, and a first conducting layer on the insulating substrate, etching the first conducting layer to form a primary gate, sequentially forming a secondary gate insulating layer and a second conducting layer on the primary gate, and etching the second conducting layer to form a first secondary gate and a second secondary gate.
- the insulating substrate can be a glass.
- the source/drain layer can be a high-doping semiconductor layer.
- the high-doping semiconductor layer can be high-doping polycrystalline silicon.
- the source/drain layer includes a drain, a channel and a source.
- the channel has a length equal to a sum of a length of the primary gate, a width of the secondary insulating layer, a length of the first secondary gate and a length of the second secondary gate.
- the primary gate insulating layer can be one selected from a silicon nitride (SiN x ), a silicon oxide (SiN x ), a silicon oxide nitride (SiO x N y ), a tantalum oxide (TaO x ), an aluminum oxide (AlO x ) and a mixture thereof.
- the first conducting layer can be one selected from chromium (Cr), molybdenum (Mo), tantalum (Ta), tantalum molybdenum (TaMo), tungsten molybdenum (WMo), aluminum (Al), aluminum silicon (AlSi), copper (Cu) and a mixture thereof.
- step (c) can be executed by means of a reactive ion etching.
- the secondary gate insulating layer can be one selected from a silicon nitride (SiN x ), a silicon oxide (SiN x ), a silicon oxide nitride (SiO x N y ), a tantalum oxide (TaO x ), an aluminum oxide (AlO x ) and a mixture thereof.
- the second conducting layer can be one selected from chromium (Cr), molybdenum (Mo), tantalum (Ta), tantalum molybdenum (TaMo), tungsten molybdenum (WMo), aluminum (Al), aluminum silicon (AlSi), copper (Cu) and a mixture thereof.
- step (e) can be executed by means of a reactive ion etching.
- the structure of a thin film transistor includes an insulating substrate, a source/drain layer disposed on the insulating substrate, a primary insulating layer disposed on the source/drain layer, a primary gate disposed on the primary insulating layer, a secondary insulating layer disposed on the primary insulating layer, and a secondary gate disposed on the secondary insulating layer and insulated from the primary gate via the secondary insulating layer.
- the secondary insulating layer further includes a first secondary insulating layer and a second secondary insulating layer.
- the secondary gate further includes a first secondary gate and a second secondary gate disposed on the first secondary insulating layer and the second secondary insulating layer respectively.
- the insulating substrate can be a glass.
- the source/drain layer can be a high-doping semiconductor layer.
- the high-doping semiconductor layer can be high-doping polycrystalline silicon.
- the source/drain layer includes a drain, a channel and a source.
- the channel has a length equal to a sum of a length of the primary gate, a width of the secondary insulating layer, and a length of the secondary gate.
- the primary gate insulating layer can be one selected from a silicon nitride (SiN x ), a silicon oxide (SiN x ), a silicon oxide nitride (SiO x N y ), a tantalum oxide (TaO x ), an aluminum oxide (AlO x ) and a mixture thereof.
- the first conducting layer can be one selected from chromium (Cr), molybdenum (Mo), tantalum (Ta), tantalum molybdenum (TaMo), tungsten molybdenum (WMo), aluminum (Al), aluminum silicon (AlSi), copper (Cu) and a mixture thereof.
- the primary gate can be formed by means of a reactive ion etching.
- the secondary gate insulating layer can be one selected from a silicon nitride (SiN x ), a silicon oxide (SiN x ), a silicon oxide nitride (SiO x N y ), a tantalum oxide (TaO x ), an aluminum oxide (AlO x ) and a mixture thereof.
- the second conducting layer can be one selected from chromium (Cr), molybdenum (Mo), tantalum (Ta), tantalum molybdenum (TaMo), tungsten molybdenum (WMo), aluminum (Al), aluminum silicon (AlSi), copper (Cu) and a mixture thereof.
- the secondary gate can be formed by means of a reactive ion etching.
- the structure of a thin film transistor includes an insulating substrate, a source/drain layer disposed on the insulating substrate, a primary insulating layer disposed on the source/drain layer, a primary gate disposed on the primary insulating layer, at least a secondary insulating layer disposed on the primary insulating layer, and at least a secondary gate disposed on the at least a secondary insulating layer and insulated from the primary gate via the at least a secondary insulating layer.
- the insulating substrate can be a glass.
- the source/drain layer can be a high-doping semiconductor layer.
- the high-doping semiconductor layer can be high-doping polycrystalline silicon.
- the source/drain layer includes a drain, a channel and a source.
- the channel has a length equal to a sum of a length of the primary gate, a width of the at least secondary insulating layer, and a length of the at least a secondary gate.
- the primary gate insulating layer can be one selected from a silicon nitride (SiN x ), a silicon oxide (SiN x ), a silicon oxide nitride (SiO x N y ), a tantalum oxide (TaO x ), an aluminum oxide (AlO x ) and a mixture thereof.
- the at least a secondary gate insulating layer can be one selected from a silicon nitride (SiN x ), a silicon oxide (SiN x ), a silicon oxide nitride (SiO x N y ), a tantalum oxide (TaO x ), an aluminum oxide (AlO x ) and a mixture thereof.
- FIG. 1 illustrates a lightly doped drain structure of the prior art for solving the problem of the off-state leakage current
- FIGS. 2 ( a )- 2 ( e ) illustrate the steps of manufacturing the thin film transistor according to the preferred embodiment of the present invention
- FIG. 3 illustrates electricity properties of the present invention compared with those of the prior art.
- FIGS. 2 ( a )- 2 ( d ) illustrate the steps of manufacturing the thin film transistor according to the preferred embodiment of the present invention.
- the method for manufacturing a thin film transistor includes several steps. First, an insulating substrate 21 is provided and a source/drain layer 22 , a primary gate insulating layer 23 , and a first conducting layer 241 are sequentially formed on the insulating substrate 21 , shown in FIG. 2( a ). Secondly, the first conducting layer 241 is etched to form a primary gate 24 , shown in FIG. 2( b ). Thirdly, a secondary gate insulating layer 25 and a second conducting layer 26 are sequentially formed on the primary gate 24 , shown in FIG. 2( c ).
- the second conducting layer 26 and the secondary gate insulating layer 25 are etched to respectively form a first secondary gate 271 and a second secondary gate 272 , and a first secondary gate insulating layer 251 and a second secondary gate insulating layer 252 , shown in FIG. 2( d ).
- FIG. 2( e ) it illustrates the bias status of the thin film transistor including a source bias voltage (VS) 28 , a gate/source bias voltage (VGS) 29 and a drain/source bias voltage (VDS) 210 .
- VS source bias voltage
- VGS gate/source bias voltage
- VDS drain/source bias voltage
- the insulating substrate 21 is a glass substrate
- the source/drain layer 22 is a high-doping semiconductor layer
- the high-doping semiconductor layer is high-doping polycrystalline silicon.
- the source/drain layer 22 includes a drain 221 , a channel 222 and a source 223 .
- the channel 222 has a length equal to a sum of a length of the primary gate 24 , a width of the first secondary insulating layer 251 and the second secondary insulting layer 252 , a length of the first secondary gate 271 and the second secondary gate 272 .
- the primary gate insulating layer 23 and the secondary gate insulating layer 25 can be one selected from a silicon nitride (SiN x ), a silicon oxide (SiN x ), a silicon oxide nitride (SiO x N y ), a tantalum oxide (TaO x ), an aluminum oxide (AlO x ) and a mixture thereof.
- first conducting layer 241 and the second conducting layer 26 are one selected from chromium (Cr), molybdenum (Mo), tantalum (Ta), tantalum molybdenum (TaMo), tungsten molybdenum (WMo), aluminum (Al), aluminum silicon (AMSi), copper (Cu) and a mixture thereof.
- first conducting layer 241 , the second conducting layer 26 and the secondary gate insulating layer 25 are etched by means of a reactive ion etching.
- FIG. 3 it illustrates electricity properties of the present invention compared with those of the prior art.
- the thin film transistor of the present invention causes a lower leakage current.
- the present invention reduces the electric field of the drain region by means of providing a thicker gate insulating layer, so as to improve the problem of the high off-state leakage current of a thin film transistor.
- the present invention introduces four photolithographic processes equal to the traditional one, but doesn't have to add an extra photolithographic process. Therefore, the present invention can solve the drawbacks of the prior art and be practicability.
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- Condensed Matter Physics & Semiconductors (AREA)
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Abstract
A method of manufacturing a thin film transistor for solving the drawbacks of the prior art is disclosed. The method includes steps of providing an insulating substrate, sequentially forming a source/drain layer, a primary gate insulating layer, and a first conducting layer on the insulating substrate, etching the first conducting layer to form a primary gate; sequentially forming a secondary gate insulating layer and a second conducting layer on the primary gate; and etching the second conducting layer to form a first secondary gate and a second secondary gate.
Description
- The present invention is related to a structure of a thin film transistor and a manufacturing method thereof, and more particularly to a structure of a thin film transistor applied to TFT-LCD and a manufacturing method thereof.
- Thin film transistor liquid crystal Display (TFT-LCD) has become one of the most popular and modem information goods. As result of being light, small and portable, having a lower operating voltage, being free of harmful radiation and suited to production on large scale, TFT-LCD substitutes for cathode ray tube display as a caressed computer display device.
- In accordance with the structure of TFT-LCD, Drain of TFT has a higher electric field while TFT is operating, and there should be an off-state leakage current resulted while the device is shut down, thereby the application of TFT-LCD being limited.
- Presently, someone provides a lightly doped drain structure and a field induced drain structure for preventing TFT-LCD from the off-state leakage current. FIG. 1 illustrates a lightly doped drain structure of the prior art for solving the problem of the off-state leakage current. The structure includes an
insulating substrate 11, a source/drain layer 12, agate insulating layer 13 and agate layer 14, wherein the source/drain layer 12 further includes adrain 121, a lightly dopeddrain 1211, achannel 122, asource 123 and a lightly dopedsource 1231. The electric field of thedrain 121 is reduced by means of adding lightly doped regions (i.e. the lightly dopeddrain 1211 and the lightly doped source 1231) corresponding to theoriginal source 123 and theoriginal drain 121 respectively near thechannel 122, so as to prevent from the leakage current. However the TFT-LCD with the lightly doped regions is complex and hard to manufacture. Furthermore the resistance will increases because of the lightly doped degree. As result of the series resistance of thedrain 121 and thesource 123 increasing, the operating speed of the device reduces and the power dissipation increases. - Moreover, another improving structure of field-induction drain has been disclosed. However it has to add an extra photolithographic process for manufacturing the improving structure. The more photolithographic processes are introduced, the more mis-alignment and infected defects are resulted. Therefore, the cost and the manufacturing time of the improving structure must increase and the yield reduces.
- Hence, the present invention is attempted to improve the prior art and provides a structure of a thin film transistor applied to a TFT-LCD and a manufacturing method thereof for preventing TFT-LCD from the leakage current.
- It is one object of the present invention to provide a structure of a thin film transistor applied to TFT-LCD and a manufacturing method thereof.
- It is another object of the present invention to provide a structure of a thin film transistor and a manufacturing method thereof for preventing TFT-LCD from the leakage current.
- According to the present invention, the method for manufacturing a thin film transistor, includes steps of providing an insulating substrate, sequentially forming a source/drain layer, a primary gate insulating layer, and a first conducting layer on the insulating substrate, etching the first conducting layer to form a primary gate, sequentially forming a secondary gate insulating layer and a second conducting layer on the primary gate, and etching the second conducting layer to form a first secondary gate and a second secondary gate.
- Certainly, the insulating substrate can be a glass.
- Certainly, the source/drain layer can be a high-doping semiconductor layer.
- Certainly, the high-doping semiconductor layer can be high-doping polycrystalline silicon.
- Preferably, the source/drain layer includes a drain, a channel and a source.
- Preferably, the channel has a length equal to a sum of a length of the primary gate, a width of the secondary insulating layer, a length of the first secondary gate and a length of the second secondary gate.
- Certainly, the primary gate insulating layer can be one selected from a silicon nitride (SiNx), a silicon oxide (SiNx), a silicon oxide nitride (SiOxNy), a tantalum oxide (TaOx), an aluminum oxide (AlOx) and a mixture thereof.
- Certainly, the first conducting layer can be one selected from chromium (Cr), molybdenum (Mo), tantalum (Ta), tantalum molybdenum (TaMo), tungsten molybdenum (WMo), aluminum (Al), aluminum silicon (AlSi), copper (Cu) and a mixture thereof.
- Certainly, the step (c) can be executed by means of a reactive ion etching.
- Certainly, the secondary gate insulating layer can be one selected from a silicon nitride (SiNx), a silicon oxide (SiNx), a silicon oxide nitride (SiOxNy), a tantalum oxide (TaOx), an aluminum oxide (AlOx) and a mixture thereof.
- Certainly, the second conducting layer can be one selected from chromium (Cr), molybdenum (Mo), tantalum (Ta), tantalum molybdenum (TaMo), tungsten molybdenum (WMo), aluminum (Al), aluminum silicon (AlSi), copper (Cu) and a mixture thereof.
- Certainly, the step (e) can be executed by means of a reactive ion etching.
- According to the present invention, the structure of a thin film transistor includes an insulating substrate, a source/drain layer disposed on the insulating substrate, a primary insulating layer disposed on the source/drain layer, a primary gate disposed on the primary insulating layer, a secondary insulating layer disposed on the primary insulating layer, and a secondary gate disposed on the secondary insulating layer and insulated from the primary gate via the secondary insulating layer.
- Preferably, the secondary insulating layer further includes a first secondary insulating layer and a second secondary insulating layer.
- Preferably, the secondary gate further includes a first secondary gate and a second secondary gate disposed on the first secondary insulating layer and the second secondary insulating layer respectively.
- Certainly, the insulating substrate can be a glass.
- Certainly, the source/drain layer can be a high-doping semiconductor layer.
- Certainly, the high-doping semiconductor layer can be high-doping polycrystalline silicon.
- Preferably, the source/drain layer includes a drain, a channel and a source.
- Preferably, the channel has a length equal to a sum of a length of the primary gate, a width of the secondary insulating layer, and a length of the secondary gate.
- Certainly, the primary gate insulating layer can be one selected from a silicon nitride (SiNx), a silicon oxide (SiNx), a silicon oxide nitride (SiOxNy), a tantalum oxide (TaOx), an aluminum oxide (AlOx) and a mixture thereof.
- Certainly, the first conducting layer can be one selected from chromium (Cr), molybdenum (Mo), tantalum (Ta), tantalum molybdenum (TaMo), tungsten molybdenum (WMo), aluminum (Al), aluminum silicon (AlSi), copper (Cu) and a mixture thereof.
- Certainly, the primary gate can be formed by means of a reactive ion etching.
- Certainly, the secondary gate insulating layer can be one selected from a silicon nitride (SiNx), a silicon oxide (SiNx), a silicon oxide nitride (SiOxNy), a tantalum oxide (TaOx), an aluminum oxide (AlOx) and a mixture thereof.
- Certainly, the second conducting layer can be one selected from chromium (Cr), molybdenum (Mo), tantalum (Ta), tantalum molybdenum (TaMo), tungsten molybdenum (WMo), aluminum (Al), aluminum silicon (AlSi), copper (Cu) and a mixture thereof.
- Certainly, the secondary gate can be formed by means of a reactive ion etching.
- According to the present invention, the structure of a thin film transistor includes an insulating substrate, a source/drain layer disposed on the insulating substrate, a primary insulating layer disposed on the source/drain layer, a primary gate disposed on the primary insulating layer, at least a secondary insulating layer disposed on the primary insulating layer, and at least a secondary gate disposed on the at least a secondary insulating layer and insulated from the primary gate via the at least a secondary insulating layer.
- Certainly, the insulating substrate can be a glass.
- Certainly, the source/drain layer can be a high-doping semiconductor layer.
- Certainly, the high-doping semiconductor layer can be high-doping polycrystalline silicon.
- Preferably, the source/drain layer includes a drain, a channel and a source.
- Preferably, the channel has a length equal to a sum of a length of the primary gate, a width of the at least secondary insulating layer, and a length of the at least a secondary gate.
- Certainly, the primary gate insulating layer can be one selected from a silicon nitride (SiNx), a silicon oxide (SiNx), a silicon oxide nitride (SiOxNy), a tantalum oxide (TaOx), an aluminum oxide (AlOx) and a mixture thereof.
- Certainly, the at least a secondary gate insulating layer can be one selected from a silicon nitride (SiNx), a silicon oxide (SiNx), a silicon oxide nitride (SiOxNy), a tantalum oxide (TaOx), an aluminum oxide (AlOx) and a mixture thereof.
- Now the foregoing and other features and advantages of the present invention will be more clearly understood through the following descriptions with reference to the drawings, wherein:
- FIG. 1 illustrates a lightly doped drain structure of the prior art for solving the problem of the off-state leakage current;
- FIGS.2(a)-2(e) illustrate the steps of manufacturing the thin film transistor according to the preferred embodiment of the present invention;
- FIG. 3 illustrates electricity properties of the present invention compared with those of the prior art.
- FIGS.2(a)-2(d) illustrate the steps of manufacturing the thin film transistor according to the preferred embodiment of the present invention. The method for manufacturing a thin film transistor includes several steps. First, an
insulating substrate 21 is provided and a source/drain layer 22, a primarygate insulating layer 23, and a first conductinglayer 241 are sequentially formed on theinsulating substrate 21, shown in FIG. 2(a). Secondly, the first conductinglayer 241 is etched to form aprimary gate 24, shown in FIG. 2(b). Thirdly, a secondarygate insulating layer 25 and asecond conducting layer 26 are sequentially formed on theprimary gate 24, shown in FIG. 2(c). Finally, thesecond conducting layer 26 and the secondarygate insulating layer 25 are etched to respectively form a firstsecondary gate 271 and a secondsecondary gate 272, and a first secondarygate insulating layer 251 and a second secondarygate insulating layer 252, shown in FIG. 2(d). As to FIG. 2(e), it illustrates the bias status of the thin film transistor including a source bias voltage (VS) 28, a gate/source bias voltage (VGS) 29 and a drain/source bias voltage (VDS) 210. - According to the above embodiment of the present invention, the insulating
substrate 21 is a glass substrate, the source/drain layer 22 is a high-doping semiconductor layer, and the high-doping semiconductor layer is high-doping polycrystalline silicon. Furthermore, the source/drain layer 22 includes adrain 221, achannel 222 and asource 223. Meanwhile, thechannel 222 has a length equal to a sum of a length of theprimary gate 24, a width of the first secondary insulatinglayer 251 and the second secondaryinsulting layer 252, a length of the firstsecondary gate 271 and the secondsecondary gate 272. - As to the primary
gate insulating layer 23 and the secondarygate insulating layer 25, they can be one selected from a silicon nitride (SiNx), a silicon oxide (SiNx), a silicon oxide nitride (SiOxNy), a tantalum oxide (TaOx), an aluminum oxide (AlOx) and a mixture thereof. However thefirst conducting layer 241 and thesecond conducting layer 26 are one selected from chromium (Cr), molybdenum (Mo), tantalum (Ta), tantalum molybdenum (TaMo), tungsten molybdenum (WMo), aluminum (Al), aluminum silicon (AMSi), copper (Cu) and a mixture thereof. Meanwhile, thefirst conducting layer 241, thesecond conducting layer 26 and the secondarygate insulating layer 25 are etched by means of a reactive ion etching. - Referring to FIG. 3, it illustrates electricity properties of the present invention compared with those of the prior art. As result of operating the thin film transistor according to the bias status of FIG. 2(e), the thin film transistor of the present invention causes a lower leakage current. In FIG. 3, when the thin film transistor of the present invention and the thin film transistor of the prior art are operated in the same condition (VDS=10V), the leakage current caused by the present invention is lower than that caused by the prior art. While VDS=15V, the leakage current (1×10−9A) of the present invention is 100 times as that (1×10−7A) of the prior art.
- Accordingly, the present invention reduces the electric field of the drain region by means of providing a thicker gate insulating layer, so as to improve the problem of the high off-state leakage current of a thin film transistor. Comparing with the prior art, the present invention introduces four photolithographic processes equal to the traditional one, but doesn't have to add an extra photolithographic process. Therefore, the present invention can solve the drawbacks of the prior art and be practicability.
- Although the present invention has been described and illustrated in detail, it is to be clearly understood that the same is by the way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of the present invention being limited only by the terms of the appended claims.
Claims (34)
1. A method for manufacturing a thin film transistor, comprising steps of:
(a) providing an insulating substrate;
(b) sequentially forming a source/drain layer, a primary gate insulating layer, and a first conducting layer on said insulating substrate;
(c) etching said first conducting layer to form a primary gate;
(d) sequentially forming a secondary gate insulating layer and a second conducting layer on said primary gate; and
(e) etching said second conducting layer to form a first secondary gate and a second secondary gate.
2. The method according to claim 1 , wherein said insulating substrate is a glass.
3. The method according to claim 1 , wherein said source/drain layer is a high-doping semiconductor layer.
4. The method according to claim 3 , wherein said high-doping semiconductor layer is high-doping polycrystalline silicon.
5. The method according to claim 1 , wherein said source/drain layer comprises a drain, a channel and a source.
6. The method according to claim 5 , wherein said channel has a length equal to a sum of a length of said primary gate, a width of said secondary insulating layer, a length of said first secondary gate and a length of said second secondary gate.
7. The method according to claim 1 , wherein said primary gate insulating layer is one selected from a silicon nitride (SiNx), a silicon oxide (SiNx), a silicon oxide nitride (SiOxNy), a tantalum oxide (TaOx), an aluminum oxide (AlOx) and a mixture thereof.
8. The method according to claim 1 , wherein said first conducting layer is one selected from chromium (Cr), molybdenum (Mo), tantalum (Ta), tantalum molybdenum (TaMo), tungsten molybdenum (WMo), aluminum (Al), aluminum silicon (AlSi), copper (Cu) and a mixture thereof.
9. The method according to claim 1 , wherein said step (c) is executed by means of a reactive ion etching.
10. The method according to claim 1 , wherein said secondary gate insulating layer is one selected from a silicon nitride (SiNx), a silicon oxide (SiNx), a silicon oxide nitride (SiOxNy), a tantalum oxide (TaOx), an aluminum oxide (AlOx) and a mixture thereof.
11. The method according to claim 1 , wherein said second conducting layer is one selected from chromium (Cr), molybdenum (Mo), tantalum (Ta), tantalum molybdenum (TaMo), tungsten molybdenum (WMo), aluminum (Al), aluminum silicon (AlSi), copper (Cu) and a mixture thereof.
12. The method according to claim 1 , wherein said step (e) is executed by means of a reactive ion etching.
13. A structure of a thin film transistor comprising:
an insulating substrate;
a source/drain layer disposed on said insulating substrate;
a primary insulating layer disposed on said source/drain layer;
a primary gate disposed on said primary insulating layer;
a secondary insulating layer disposed on said primary insulating layer; and
a secondary gate disposed on said secondary insulating layer and insulated from said primary gate via said secondary insulating layer.
14. The structure according to claim 13 , wherein said secondary insulating layer further comprises a first secondary insulating layer and a second secondary insulating layer.
15. The structure according to claim 14 , wherein said secondary gate further comprises a first secondary gate and a second secondary gate disposed on said first secondary insulating layer and said second secondary insulating layer respectively.
16. The structure according to claim 13 , wherein said insulating substrate is a glass.
17. The structure according to claim 13 , wherein said source/drain layer is a high-doping semiconductor layer.
18. The structure according to claim 17 , wherein said high-doping semiconductor layer is high-doping polycrystalline silicon.
19. The structure according to claim 13 , wherein said source/drain layer comprises a drain, a channel and a source.
20. The structure according to claim 19 , wherein said channel has a length equal to a sum of a length of said primary gate, a width of said secondary insulating layer, and a length of said secondary gate.
21. The structure according to claim 13 , wherein said primary gate insulating layer is one selected from a silicon nitride (SiNx), a silicon oxide (SiNx), a silicon oxide nitride (SiOxNy), a tantalum oxide (TaOx), an aluminum oxide (AlOx) and a mixture thereof.
22. The structure according to claim 13 , wherein said first conducting layer is one selected from chromium (Cr), molybdenum (Mo), tantalum (Ta), tantalum molybdenum (TaMo), tungsten molybdenum (WMo), aluminum (Al), aluminum silicon (AlSi), copper (Cu) and a mixture thereof.
23. The structure according to claim 13 , wherein said primary gate is formed by means of a reactive ion etching.
24. The structure according to claim 13 , wherein said secondary gate insulating layer is one selected from a silicon nitride (SiNx), a silicon oxide (SiNx), a silicon oxide nitride (SiOxNy), a tantalum oxide (TaOx), an aluminum oxide (AlOx) and a mixture thereof.
25. The structure according to claim 13 , wherein said second conducting layer is one selected from chromium (Cr), molybdenum (Mo), tantalum (Ta), tantalum molybdenum (TaMo), tungsten molybdenum (WMo), aluminum (Al), aluminum silicon (AlSi), copper (Cu) and a mixture thereof.
26. The structure according to claim 13 , wherein said secondary gate is formed by means of a reactive ion etching.
27. A structure of a thin film transistor comprising:
an insulating substrate;
a source/drain layer disposed on said insulating substrate;
a primary insulating layer disposed on said source/drain layer;
a primary gate disposed on said primary insulating layer;
at least a secondary insulating layer disposed on said primary insulating layer; and
at least a secondary gate disposed on said at least a secondary insulating layer and insulated from said primary gate via said at least a secondary insulating layer.
28. The structure according to claim 27 , wherein said insulating substrate is a glass.
29. The structure according to claim 27 , wherein said source/drain layer is a high-doping semiconductor layer.
30. The structure according to claim 29 , wherein said high-doping semiconductor layer is high-doping polycrystalline silicon.
31. The structure according to claim 27 , wherein said source/drain layer comprises a drain, a channel and a source.
32. The structure according to claim 31 , wherein said channel has a length equal to a sum of a length of said primary gate, a width of said at least secondary insulating layer, and a length of said at least a secondary gate.
33. The structure according to claim 27 , wherein said primary gate insulating layer is one selected from a silicon nitride (SiNx), a silicon oxide (SiNx), a silicon oxide nitride (SiOxNy), a tantalum oxide (TaOx), an aluminum oxide (AlOx) and a mixture thereof.
34. The structure according to claim 29 , wherein said at least a secondary gate insulating layer is one selected from a silicon nitride (SiNx), a silicon oxide (SiNx), a silicon oxide nitride (SiOxNy), a tantalum oxide (TaOx), an aluminum oxide (AlOx) and a mixture thereof.
Priority Applications (3)
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US10/259,137 US20040063311A1 (en) | 2002-09-26 | 2002-09-26 | Structure of thin film transistor and manufacturing method thereof |
US10/632,641 US6969890B2 (en) | 2002-09-26 | 2003-08-01 | Structure of thin film transistor |
US10/913,584 US6991973B2 (en) | 2002-09-26 | 2004-08-05 | Manufacturing method of thin film transistor |
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US10/259,137 US20040063311A1 (en) | 2002-09-26 | 2002-09-26 | Structure of thin film transistor and manufacturing method thereof |
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US10/632,641 Division US6969890B2 (en) | 2002-09-26 | 2003-08-01 | Structure of thin film transistor |
US10/913,584 Continuation-In-Part US6991973B2 (en) | 2002-09-26 | 2004-08-05 | Manufacturing method of thin film transistor |
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US10/632,641 Expired - Fee Related US6969890B2 (en) | 2002-09-26 | 2003-08-01 | Structure of thin film transistor |
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US6812105B1 (en) * | 2003-07-16 | 2004-11-02 | International Business Machines Corporation | Ultra-thin channel device with raised source and drain and solid source extension doping |
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US6969890B2 (en) | 2005-11-29 |
US20040061174A1 (en) | 2004-04-01 |
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