US20010041461A1 - Process for forming high voltage junction termination extension oxide - Google Patents
Process for forming high voltage junction termination extension oxide Download PDFInfo
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- US20010041461A1 US20010041461A1 US09/167,177 US16717798D US2001041461A1 US 20010041461 A1 US20010041461 A1 US 20010041461A1 US 16717798 D US16717798 D US 16717798D US 2001041461 A1 US2001041461 A1 US 2001041461A1
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- 230000008569 process Effects 0.000 title abstract description 14
- 239000000758 substrate Substances 0.000 claims abstract description 37
- 239000007943 implant Substances 0.000 claims abstract description 23
- 230000001590 oxidative effect Effects 0.000 claims abstract description 20
- 239000002243 precursor Substances 0.000 claims abstract description 20
- 239000002019 doping agent Substances 0.000 claims abstract description 19
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 17
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 8
- 239000001301 oxygen Substances 0.000 claims abstract description 8
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 8
- 230000005527 interface trap Effects 0.000 claims abstract description 6
- 238000003949 trap density measurement Methods 0.000 claims abstract description 6
- 239000000463 material Substances 0.000 claims abstract description 5
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- 238000004519 manufacturing process Methods 0.000 claims description 3
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- 230000015572 biosynthetic process Effects 0.000 abstract description 19
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- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 14
- 230000003647 oxidation Effects 0.000 description 12
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 8
- 229910052710 silicon Inorganic materials 0.000 description 8
- 239000010703 silicon Substances 0.000 description 8
- 235000012239 silicon dioxide Nutrition 0.000 description 5
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- H01L21/02104—Forming layers
- H01L21/02107—Forming insulating materials on a substrate
- H01L21/02225—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer
- H01L21/02227—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a process other than a deposition process
- H01L21/0223—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a process other than a deposition process formation by oxidation, e.g. oxidation of the substrate
- H01L21/02233—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a process other than a deposition process formation by oxidation, e.g. oxidation of the substrate of the semiconductor substrate or a semiconductor layer
- H01L21/02236—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a process other than a deposition process formation by oxidation, e.g. oxidation of the substrate of the semiconductor substrate or a semiconductor layer group IV semiconductor
- H01L21/02238—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a process other than a deposition process formation by oxidation, e.g. oxidation of the substrate of the semiconductor substrate or a semiconductor layer group IV semiconductor silicon in uncombined form, i.e. pure silicon
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- H01L21/02107—Forming insulating materials on a substrate
- H01L21/02225—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer
- H01L21/02227—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a process other than a deposition process
- H01L21/02255—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a process other than a deposition process formation by thermal treatment
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- H01L21/027—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34
- H01L21/033—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34 comprising inorganic layers
- H01L21/0332—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34 comprising inorganic layers characterised by their composition, e.g. multilayer masks, materials
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- H01L21/0337—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34 comprising inorganic layers characterised by their size, orientation, disposition, behaviour, shape, in horizontal or vertical plane characterised by the process involved to create the mask, e.g. lift-off masks, sidewalls, or to modify the mask, e.g. pre-treatment, post-treatment
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- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/22—Diffusion of impurity materials, e.g. doping materials, electrode materials, into or out of a semiconductor body, or between semiconductor regions; Interactions between two or more impurities; Redistribution of impurities
- H01L21/225—Diffusion of impurity materials, e.g. doping materials, electrode materials, into or out of a semiconductor body, or between semiconductor regions; Interactions between two or more impurities; Redistribution of impurities using diffusion into or out of a solid from or into a solid phase, e.g. a doped oxide layer
- H01L21/2251—Diffusion into or out of group IV semiconductors
- H01L21/2252—Diffusion into or out of group IV semiconductors using predeposition of impurities into the semiconductor surface, e.g. from a gaseous phase
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- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
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- H01L21/314—Inorganic layers
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- H01L21/31658—Inorganic layers composed of oxides or glassy oxides or oxide based glass formed by oxidation of semiconductor materials, e.g. the body itself by thermal oxidation, e.g. of SiGe
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- H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
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- H01L29/0603—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions
- H01L29/0607—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions for preventing surface leakage or controlling electric field concentration
- H01L29/0611—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions for preventing surface leakage or controlling electric field concentration for increasing or controlling the breakdown voltage of reverse biased devices
- H01L29/0615—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions for preventing surface leakage or controlling electric field concentration for increasing or controlling the breakdown voltage of reverse biased devices by the doping profile or the shape or the arrangement of the PN junction, or with supplementary regions, e.g. junction termination extension [JTE]
- H01L29/0619—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions for preventing surface leakage or controlling electric field concentration for increasing or controlling the breakdown voltage of reverse biased devices by the doping profile or the shape or the arrangement of the PN junction, or with supplementary regions, e.g. junction termination extension [JTE] with a supplementary region doped oppositely to or in rectifying contact with the semiconductor containing or contacting region, e.g. guard rings with PN or Schottky junction
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- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/26—Bombardment with radiation
- H01L21/263—Bombardment with radiation with high-energy radiation
- H01L21/265—Bombardment with radiation with high-energy radiation producing ion implantation
- H01L21/266—Bombardment with radiation with high-energy radiation producing ion implantation using masks
Definitions
- the present invention relates in general to the manufacture of high-voltage semiconductor integrated circuits, and is particularly directed to a new and improved process for forming a junction termination extension (JTE) oxide that enjoys reduced total oxide charge (Qox) and SiO 2 —Si interface trap density (Dit) parameters, thereby offering improved high voltage edge stability.
- JTE junction termination extension
- JTE junction termination extension
- the conventional process begins by exposing the top surface of a semiconductor (silicon) substrate 1 , shown in FIG. 2A, to a ‘wet’ or steam ambient, so as to rapidly grow a relatively thick ubiquitous oxide layer 2 , that is to serve as part of the bulk JTE oxide.
- the oxide layer 2 is then patterned, etched and cleaned/rinsed to open a plurality of implant apertures 3 , which expose corresponding (JTE dopant-implant) surface portions 4 in the top surface of substrate 1 .
- step 105 conductivity type determining impurities 5 are implanted through the implant apertures 3 of the oxide layer 2 , forming a plurality of JTE surface regions shown at 6 in FIG. 2C.
- This implant step introduces unwanted near-surface pockets of crystalline damage 7 in the vicinity of the top surface of the silicon substrate.
- a wet or stream screen oxide layer 8 is rapidly grown directly on the JTE surface regions 6 , as shown in FIG. 2D.
- the oxide layer 8 is grown rapidly and directly upon the implanted surface of the silicon, it is of relatively poor quality, and can be expected to negatively impact the quality of any subsequently formed oxide.
- the device is subjected to a dopant drive-in step 109 , which causes the dopant of the implanted regions 6 to diffuse into the surrounding substrate, and essentially define the JTE structure, as shown at 6 ′ in FIG. 2E. Although some additional dopant diffusion will occur during subsequent oxidation, the bulk of the dopant drive-in is completed in this step.
- the JTE oxide process is completed by performing a further rapid steam or wet oxidation step 111 , which fills in the implant apertures 3 with oxide 9 and results in the JTE structure shown in FIG. 2F.
- each of the oxide layers formed in the process of FIGS. 1 and 2, particularly those overlying the implanted regions, are grown rapidly in a wet or stream atmosphere, they are of relatively low density. As a result they facilitate segregation or out-diffusion of dopants into the oxide, and reduce the quality of any oxide grown thereon. This has the unwanted effect of allowing the total oxide charge (Qox) and SiO 2 —Si interface trap density (Dit) to increase, which degrades high voltage stability.
- the above-referenced shortcomings of conventional JTE oxide formation are effectively obviated by employing precursor densified thin oxide layers to improve the quality of subsequently formed thicker oxide layers, and performing multiple anneals in a dry or non-oxidizing atmosphere to remove implant damage and to set finalized geometry parameters.
- the use of such an atmosphere for post JTE oxidation annealing substantially lowers Qox and Dit.
- a relatively thin and dense precursor oxide layer is ubiquitously grown on the surface of a silicon substrate in a dry oxygen ambient.
- the thickness of the oxide layer is increased in a steam or wet oxygen atmosphere, causing the growth of a relatively thick silicon dioxide layer. Because the thin precursor oxide layer is highly densified, it increases the density and quality of the thick oxide layer.
- a post-oxidation anneal is then performed in a dry ambient or non-oxidizing atmosphere, which substantially reduces Qox and Dit.
- the oxide then masked and etched to form a plurality of dopant implant apertures in the oxide layer.
- JTE dopants are then implanted through the implant apertures of the oxide layer, forming a plurality of conductivity-modifying semiconductor JTE regions that extend to a prescribed implant depth from the top surface of the silicon substrate.
- the substrate is annealed in a non-oxidizing or inert gas ambient.
- the non-oxidizing atmosphere of the annealing step prevents oxidation of the top surface of the substrate from which the JTE regions extend, and thereby avoids negatively impacting subsequent oxide formation.
- a dry oxide ambient cannot be used to anneal out the crystalline damage during this step, since formation of a highly dense oxide layer may cause the formation of oxidation-induced stacking faults.
- the JTE dopants are then partially driven away from the near-surface portions into adjoining material of the substrate, to prevent segregation of the dopant into the oxide that will be subsequently grown.
- a relatively thin and highly densified bulk oxide precursor layer is then grown on the exposed JTE dopant-implanted surface portions of the substrate to ensure precise control of subsequent oxide formation.
- the bulk of the JTE oxide is then formed in a steam or wet oxygen atmosphere.
- the substrate is annealed in a non-oxidizing or inert gas ambient, to cause a further drive-in of the JTE dopants.
- the dry or non-oxidizing atmosphere of the post JTE oxidation annealing step substantially lowers Qox and Dit.
- the reduction in Qox and Dit may be determined by carrying out conventional capacitance-voltage and associated electrical parameter measurements, such as those commonly employed for MOS capacitor structures.
- FIG. 1 shows the process steps of a conventional JTE oxide process
- FIGS. 2 A- 2 F are diagrammatic sectional views of a JTE semiconductor structure at respective steps of the process of FIG. 1;
- FIGS. 3 A- 3 I are diagrammatic sectional views of a JTE semiconductor structure at respective steps of the JTE oxide process of the present invention.
- FIG. 4 shows the sequence of steps of the JTE oxide formation process of the invention.
- FIGS. 3 A- 3 I show the state of the device at respective steps of the processing flow sequence of FIG. 4.
- the oxidation formation process begins by forming a relatively thick oxide layer 10 (e.g., 800 Angstroms) on a top surface 21 of a clean or epitaxial semiconductor substrate 20 , such as a silicon substrate of a first conductivity type (e.g., N type as a non-limiting example).
- oxide layer 10 is formed by first slowly growing a relatively thin and dense precursor oxide layer, such as silicon dioxide 12 (FIG. 3A) in a dry oxygen (O 2 ) ambient, for example, at a temperature of 900° C., for 120 minutes, to a first thickness (e.g., 300 Angstroms).
- step 403 the thickness of the silicon dioxide layer 10 is increased, by introducing steam (e.g., at a temperature on the order of 1050° C.) or a wet O 2 atmosphere (at a temperature of 1050° C.), for 120 minutes, causing the growth of a relatively thick silicon dioxide layer 14 at the silicon surface and incorporating therein the thin dense oxide layer 12 , to a thickness on the order of 80000 Angstroms, as shown in FIG. 3B. Because the thin precursor oxide layer 12 is a highly compact oxide layer, it increases the density and quality of the thick oxide layer 14 , relative to the oxide layer rapidly formed by the prior art process described previously.
- steam e.g., at a temperature on the order of 1050° C.
- a wet O 2 atmosphere at a temperature of 1050° C.
- a post-oxidation anneal is performed in a dry ambient or non-oxidizing atmosphere, which serves to substantially reduce Qox and Dit.
- the anneal may be carried out at a temperature on the order of 50° C. greater than the steam oxidation temperature (or 1100° C. in the present example), for 30 minutes, in an N 2 ambient.
- the oxide-coated wafer is then masked, etched and cleaned/rinsed in a conventional manner in step 407 , to provide at least one (e.g., a plurality of) implant apertures 18 in the oxide layer 10 , which thereby selectively expose corresponding (JTE dopant-implant) surface portions 23 in the top surface 21 of the substrate 20 , as shown in FIG. 3C.
- step 409 using a conventional implant operation, such as that described previously, conductivity type determining impurities 19 (e.g., P-type in the present example) are introduced (implanted) through the implant apertures 18 of the oxide layer 10 , so as to form a plurality of (P-type) conductivity-modifying semiconductor (JTE) regions 25 that extend to a prescribed implant depth from the top surface 21 of the substrate 20 , as shown in FIG. 3D.
- this implant step causes crystalline damage in those portions 26 of the JTE regions 25 adjacent to the surface 21 , which must be removed to prevent stack fault formation.
- the substrate is annealed in a non-oxidizing or inert gas ambient, such as but not limited to Ar, H 2 /N 2 forming gas, N 2 , and the like, to repair the displaced lattice sites, resulting in the structure of FIG. 3E.
- a non-oxidizing or inert gas ambient such as but not limited to Ar, H 2 /N 2 forming gas, N 2 , and the like.
- this anneal may be carried out at a temperature on the order of 800° C., for a period of 20 minutes.
- the non-oxidizing atmosphere of the annealing step prevents oxidation of the surface portions 23 of the top surface 21 of the substrate 20 from which the JTE regions extend, and thereby avoids impacting subsequent oxide formation.
- a dry oxide ambient cannot be used to anneal out the crystalline damage during this step, since the formation of a highly dense oxide layer may cause the formation of oxidation-induced stacking faults.
- step 413 a partial drive-in of the conductivity type determining JTE dopants in regions 25 away from the near-surface portions into adjoining (surrounding) material of the semiconductor substrate 20 is performed, resulting in the expanded region structure 25 ′ shown in FIG. 3F.
- This partial drive-in serves to prevent segregation of the dopant into the oxide that will be subsequently grown.
- the respective time and temperature parameters for this step may be on the order of 160 minutes at 1200° C. The less than total dopant drive-in during this step conserves thermal budget, providing for substantial annealing time after the thickness of JTE termination oxide is finalized.
- a relatively thin and highly densified bulk precursor oxide layer 30 is grown on the exposed JTE dopant-implanted surface portions 23 of the top surface 21 of the substrate 20 , in a dry O 2 ambient, for example, at a temperature of 1050° C., for 45 minutes, to a thickness on the order of 600 Angstroms.
- the densified bulk precursor oxide layer 30 ensures precise control of subsequent bulk oxide formation.
- the bulk of the JTE oxide is formed by introducing steam (e.g., at a temperature on the order of 1050° C.) or a wet O 2 atmosphere (at a temperature of 1050° C.), for 170 minutes, causing the growth of a relatively thick silicon dioxide layer 32 on the surface of the silicon, and incorporating the thin dense oxide layer 30 , for example to a thickness on the order of one micron, as shown in FIG. 3H.
- steam e.g., at a temperature on the order of 1050° C.
- a wet O 2 atmosphere at a temperature of 1050° C.
- the substrate is again annealed in a non-oxidizing or inert gas ambient, such as but not limited to Ar, H 2 /N 2 forming gas, N 2 , and the like, referenced above, to effect a further drive-in of the conductivity type determining JTE dopants—forming regions 25 ′′, shown in the structure of FIG. 3I.
- a non-oxidizing or inert gas ambient such as but not limited to Ar, H 2 /N 2 forming gas, N 2 , and the like, referenced above.
- this final, post-JTE oxidation anneal may be carried out at a temperature on the order of 1100° C., for a period of 30 minutes.
- the ‘dry’ or non-oxidizing atmosphere of the post JTE oxidation annealing step substantially lowers Qox and Dit.
- the extent to which high voltage edge stability is improved, as represented by a reduction in Qox and Dit may be determined by carrying out conventional capacitance-voltage and associated electrical parameter measurements,
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Abstract
Description
- The present invention relates in general to the manufacture of high-voltage semiconductor integrated circuits, and is particularly directed to a new and improved process for forming a junction termination extension (JTE) oxide that enjoys reduced total oxide charge (Qox) and SiO2—Si interface trap density (Dit) parameters, thereby offering improved high voltage edge stability.
- High-voltage discrete and integrated circuit devices, which are currently employed in a wide variety of electrical and electronic circuit architectures, are subject to excessive electric field intensity created in the vicinity of a reverse-biased PN junction. One particularly effective mechanism to deal with this problem has been to use a junction termination extension (JTE), as a barrier against the effects of the electric field. In a typical architecture, the JTE device is passivated by a relatively thick bulk oxide layer that is formed by the process sequence shown in FIG. 1, respective steps of which yield a device structure shown in the associated cross-sectional diagrams of FIGS.2A-2F.
- More particularly, as shown at step101, the conventional process begins by exposing the top surface of a semiconductor (silicon)
substrate 1, shown in FIG. 2A, to a ‘wet’ or steam ambient, so as to rapidly grow a relatively thickubiquitous oxide layer 2, that is to serve as part of the bulk JTE oxide. As shown atstep 103 and FIG. 2B, theoxide layer 2 is then patterned, etched and cleaned/rinsed to open a plurality ofimplant apertures 3, which expose corresponding (JTE dopant-implant)surface portions 4 in the top surface ofsubstrate 1. - In
step 105, conductivity type determining impurities 5 are implanted through theimplant apertures 3 of theoxide layer 2, forming a plurality of JTE surface regions shown at 6 in FIG. 2C. This implant step introduces unwanted near-surface pockets of crystalline damage 7 in the vicinity of the top surface of the silicon substrate. In order to remove this crystalline damage and prevent stacking fault formation, atstep 107, a wet or stream screen oxide layer 8 is rapidly grown directly on the JTE surface regions 6, as shown in FIG. 2D. Unfortunately, because the oxide layer 8 is grown rapidly and directly upon the implanted surface of the silicon, it is of relatively poor quality, and can be expected to negatively impact the quality of any subsequently formed oxide. - Following formation of the screen oxide layer8, the device is subjected to a dopant drive-in step 109, which causes the dopant of the implanted regions 6 to diffuse into the surrounding substrate, and essentially define the JTE structure, as shown at 6′ in FIG. 2E. Although some additional dopant diffusion will occur during subsequent oxidation, the bulk of the dopant drive-in is completed in this step. The JTE oxide process is completed by performing a further rapid steam or wet oxidation step 111, which fills in the
implant apertures 3 withoxide 9 and results in the JTE structure shown in FIG. 2F. - Because each of the oxide layers formed in the process of FIGS. 1 and 2, particularly those overlying the implanted regions, are grown rapidly in a wet or stream atmosphere, they are of relatively low density. As a result they facilitate segregation or out-diffusion of dopants into the oxide, and reduce the quality of any oxide grown thereon. This has the unwanted effect of allowing the total oxide charge (Qox) and SiO2—Si interface trap density (Dit) to increase, which degrades high voltage stability.
- In accordance with the present invention, the above-referenced shortcomings of conventional JTE oxide formation are effectively obviated by employing precursor densified thin oxide layers to improve the quality of subsequently formed thicker oxide layers, and performing multiple anneals in a dry or non-oxidizing atmosphere to remove implant damage and to set finalized geometry parameters. The use of such an atmosphere for post JTE oxidation annealing substantially lowers Qox and Dit.
- In order to ensure precise control of subsequent oxide formation, a relatively thin and dense precursor oxide layer is ubiquitously grown on the surface of a silicon substrate in a dry oxygen ambient. The thickness of the oxide layer is increased in a steam or wet oxygen atmosphere, causing the growth of a relatively thick silicon dioxide layer. Because the thin precursor oxide layer is highly densified, it increases the density and quality of the thick oxide layer.
- A post-oxidation anneal is then performed in a dry ambient or non-oxidizing atmosphere, which substantially reduces Qox and Dit. The oxide then masked and etched to form a plurality of dopant implant apertures in the oxide layer. JTE dopants are then implanted through the implant apertures of the oxide layer, forming a plurality of conductivity-modifying semiconductor JTE regions that extend to a prescribed implant depth from the top surface of the silicon substrate.
- In order to remove near surface crystalline damage caused by the implant, the substrate is annealed in a non-oxidizing or inert gas ambient. The non-oxidizing atmosphere of the annealing step prevents oxidation of the top surface of the substrate from which the JTE regions extend, and thereby avoids negatively impacting subsequent oxide formation. A dry oxide ambient cannot be used to anneal out the crystalline damage during this step, since formation of a highly dense oxide layer may cause the formation of oxidation-induced stacking faults. The JTE dopants are then partially driven away from the near-surface portions into adjoining material of the substrate, to prevent segregation of the dopant into the oxide that will be subsequently grown.
- A relatively thin and highly densified bulk oxide precursor layer is then grown on the exposed JTE dopant-implanted surface portions of the substrate to ensure precise control of subsequent oxide formation. The bulk of the JTE oxide is then formed in a steam or wet oxygen atmosphere.
- After the bulk oxide has been grown to its desired thickness, the substrate is annealed in a non-oxidizing or inert gas ambient, to cause a further drive-in of the JTE dopants. The dry or non-oxidizing atmosphere of the post JTE oxidation annealing step substantially lowers Qox and Dit. The reduction in Qox and Dit (and thereby the extent to which high voltage edge stability is improved) may be determined by carrying out conventional capacitance-voltage and associated electrical parameter measurements, such as those commonly employed for MOS capacitor structures.
- FIG. 1 shows the process steps of a conventional JTE oxide process;
- FIGS.2A-2F are diagrammatic sectional views of a JTE semiconductor structure at respective steps of the process of FIG. 1;
- FIGS.3A-3I are diagrammatic sectional views of a JTE semiconductor structure at respective steps of the JTE oxide process of the present invention; and
- FIG. 4 shows the sequence of steps of the JTE oxide formation process of the invention.
- The process through which a high voltage junction termination extension oxide is formed on a semiconductor substrate/wafer in accordance with a preferred embodiment of the present invention will now be described with reference to the cross-sectional diagrams of FIGS.3A-3I, that show the state of the device at respective steps of the processing flow sequence of FIG. 4.
- As shown in FIGS. 3A and 3B, the oxidation formation process begins by forming a relatively thick oxide layer10 (e.g., 800 Angstroms) on a
top surface 21 of a clean orepitaxial semiconductor substrate 20, such as a silicon substrate of a first conductivity type (e.g., N type as a non-limiting example). In order to ensure precise control of subsequent oxide formation, instep 401,oxide layer 10 is formed by first slowly growing a relatively thin and dense precursor oxide layer, such as silicon dioxide 12 (FIG. 3A) in a dry oxygen (O2) ambient, for example, at a temperature of 900° C., for 120 minutes, to a first thickness (e.g., 300 Angstroms). - Next, in
step 403, the thickness of thesilicon dioxide layer 10 is increased, by introducing steam (e.g., at a temperature on the order of 1050° C.) or a wet O2 atmosphere (at a temperature of 1050° C.), for 120 minutes, causing the growth of a relatively thicksilicon dioxide layer 14 at the silicon surface and incorporating therein the thindense oxide layer 12, to a thickness on the order of 80000 Angstroms, as shown in FIG. 3B. Because the thinprecursor oxide layer 12 is a highly compact oxide layer, it increases the density and quality of thethick oxide layer 14, relative to the oxide layer rapidly formed by the prior art process described previously. - Next, as shown at
step 405, a post-oxidation anneal is performed in a dry ambient or non-oxidizing atmosphere, which serves to substantially reduce Qox and Dit. For this purpose, the anneal may be carried out at a temperature on the order of 50° C. greater than the steam oxidation temperature (or 1100° C. in the present example), for 30 minutes, in an N2 ambient. The oxide-coated wafer is then masked, etched and cleaned/rinsed in a conventional manner instep 407, to provide at least one (e.g., a plurality of) implant apertures 18 in theoxide layer 10, which thereby selectively expose corresponding (JTE dopant-implant)surface portions 23 in thetop surface 21 of thesubstrate 20, as shown in FIG. 3C. - In step409, using a conventional implant operation, such as that described previously, conductivity type determining impurities 19 (e.g., P-type in the present example) are introduced (implanted) through the implant apertures 18 of the
oxide layer 10, so as to form a plurality of (P-type) conductivity-modifying semiconductor (JTE)regions 25 that extend to a prescribed implant depth from thetop surface 21 of thesubstrate 20, as shown in FIG. 3D. As described previously, this implant step causes crystalline damage in those portions 26 of theJTE regions 25 adjacent to thesurface 21, which must be removed to prevent stack fault formation. - For this purpose, at
step 411, the substrate is annealed in a non-oxidizing or inert gas ambient, such as but not limited to Ar, H2/N2 forming gas, N2, and the like, to repair the displaced lattice sites, resulting in the structure of FIG. 3E. As a non-limiting example, this anneal may be carried out at a temperature on the order of 800° C., for a period of 20 minutes. The non-oxidizing atmosphere of the annealing step prevents oxidation of thesurface portions 23 of thetop surface 21 of thesubstrate 20 from which the JTE regions extend, and thereby avoids impacting subsequent oxide formation. A dry oxide ambient cannot be used to anneal out the crystalline damage during this step, since the formation of a highly dense oxide layer may cause the formation of oxidation-induced stacking faults. - In step413, a partial drive-in of the conductivity type determining JTE dopants in
regions 25 away from the near-surface portions into adjoining (surrounding) material of thesemiconductor substrate 20 is performed, resulting in the expandedregion structure 25′ shown in FIG. 3F. This partial drive-in serves to prevent segregation of the dopant into the oxide that will be subsequently grown. The respective time and temperature parameters for this step may be on the order of 160 minutes at 1200° C. The less than total dopant drive-in during this step conserves thermal budget, providing for substantial annealing time after the thickness of JTE termination oxide is finalized. - Next, as shown in FIG. 3G, and at
step 415, a relatively thin and highly densified bulkprecursor oxide layer 30 is grown on the exposed JTE dopant-implantedsurface portions 23 of thetop surface 21 of thesubstrate 20, in a dry O2 ambient, for example, at a temperature of 1050° C., for 45 minutes, to a thickness on the order of 600 Angstroms. Like the thinprecursor oxide layer 12 formed instep 401, the densified bulkprecursor oxide layer 30 ensures precise control of subsequent bulk oxide formation. - Following the formation of the thin
precursor oxide layer 30 within the implant apertures 18, atstep 417 the bulk of the JTE oxide is formed by introducing steam (e.g., at a temperature on the order of 1050° C.) or a wet O2 atmosphere (at a temperature of 1050° C.), for 170 minutes, causing the growth of a relatively thicksilicon dioxide layer 32 on the surface of the silicon, and incorporating the thindense oxide layer 30, for example to a thickness on the order of one micron, as shown in FIG. 3H. Again since bulkprecursor oxide layer 30 is highly compact and densified, it increases the density and quality of the thickJTE oxide layer 32. Duringstep 417, the thickness ofdense oxide layer 30 is not significantly altered, as its thickness and density make it a substantially diffusion-limited film. - Once the
bulk oxide 32 has been grown to its desired thickness, the substrate is again annealed in a non-oxidizing or inert gas ambient, such as but not limited to Ar, H2/N2 forming gas, N2, and the like, referenced above, to effect a further drive-in of the conductivity type determining JTE dopants—formingregions 25″, shown in the structure of FIG. 3I. As a non-limiting example, this final, post-JTE oxidation anneal may be carried out at a temperature on the order of 1100° C., for a period of 30 minutes. The ‘dry’ or non-oxidizing atmosphere of the post JTE oxidation annealing step substantially lowers Qox and Dit. The extent to which high voltage edge stability is improved, as represented by a reduction in Qox and Dit, may be determined by carrying out conventional capacitance-voltage and associated electrical parameter measurements, such as those commonly employed for MOS capacitor structures. - As will be appreciated from the foregoing description, the above-referenced shortcomings of conventional JTE oxide formation are effectively obviated by employing precursor densified thin oxide layers to improve the quality of subsequently formed thicker oxide layers, and performing multiple anneals in a dry or non-oxidizing atmosphere to remove implant damage and to set finalized geometry parameters. The use of such an atmosphere for post JTE oxidation annealing substantially lowers Qox and Dit.
- While we have shown and described an embodiment in accordance with the present invention, it is to be understood that the same is not limited thereto but is susceptible to numerous changes and modifications as are known to a person skilled in the art, and we therefore do not wish to be limited to the details shown and described herein, but intend to cover all such changes and modifications as are obvious to one of ordinary skill in the art.
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US20130316523A1 (en) * | 2012-05-28 | 2013-11-28 | Canon Kabushiki Kaisha | Method of manufacturing a semiconductor device |
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US7144797B2 (en) * | 2004-09-24 | 2006-12-05 | Rensselaer Polytechnic Institute | Semiconductor device having multiple-zone junction termination extension, and method for fabricating the same |
US8828855B2 (en) * | 2007-04-30 | 2014-09-09 | Texas Instruments Incorporated | Transistor performance using a two-step damage anneal |
US8106487B2 (en) | 2008-12-23 | 2012-01-31 | Pratt & Whitney Rocketdyne, Inc. | Semiconductor device having an inorganic coating layer applied over a junction termination extension |
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US4677740A (en) * | 1973-06-29 | 1987-07-07 | Hughes Aircraft Company | Forming monolithic planar opto-isolators by selective implantation and proton bombardment |
US4187125A (en) * | 1976-12-27 | 1980-02-05 | Raytheon Company | Method for manufacturing semiconductor structures by anisotropic and isotropic etching |
US4676869A (en) * | 1986-09-04 | 1987-06-30 | American Telephone And Telegraph Company At&T Bell Laboratories | Integrated circuits having stepped dielectric regions |
US4743569A (en) * | 1987-04-20 | 1988-05-10 | Texas Instruments Incorporated | Two step rapid thermal anneal of implanted compound semiconductor |
FR2620271B1 (en) * | 1987-09-08 | 1990-01-12 | Thomson Semiconducteurs | SEMICONDUCTOR PROTECTION AGAINST OVERVOLTAGES |
US5156989A (en) * | 1988-11-08 | 1992-10-20 | Siliconix, Incorporated | Complementary, isolated DMOS IC technology |
US5141881A (en) * | 1989-04-20 | 1992-08-25 | Sanyo Electric Co., Ltd. | Method for manufacturing a semiconductor integrated circuit |
JPH05121664A (en) * | 1991-10-25 | 1993-05-18 | Nec Corp | Semiconductor device |
US5192712A (en) * | 1992-04-15 | 1993-03-09 | National Semiconductor Corporation | Control and moderation of aluminum in silicon using germanium and germanium with boron |
US5430324A (en) | 1992-07-23 | 1995-07-04 | Siliconix, Incorporated | High voltage transistor having edge termination utilizing trench technology |
US5316981A (en) * | 1992-10-09 | 1994-05-31 | Advanced Micro Devices, Inc. | Method for achieving a high quality thin oxide using a sacrificial oxide anneal |
US5614421A (en) | 1994-03-11 | 1997-03-25 | United Microelectronics Corp. | Method of fabricating junction termination extension structure for high-voltage diode devices |
US5462898A (en) * | 1994-05-25 | 1995-10-31 | Georgia Tech Research Corporation | Methods for passivating silicon devices at low temperature to achieve low interface state density and low recombination velocity while preserving carrier lifetime |
DE69525003T2 (en) | 1994-08-15 | 2003-10-09 | Siliconix Inc., Santa Clara | Method of manufacturing a trench-structure DMOS transistor using seven masks |
US6034396A (en) * | 1998-01-28 | 2000-03-07 | Texas Instruments - Acer Incorporated | Ultra-short channel recessed gate MOSFET with a buried contact |
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US20130316523A1 (en) * | 2012-05-28 | 2013-11-28 | Canon Kabushiki Kaisha | Method of manufacturing a semiconductor device |
US9082699B2 (en) * | 2012-05-28 | 2015-07-14 | Canon Kabushiki Kaisha | Method of manufacturing a semiconductor device |
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