US20140175457A1 - Sic-based trench-type schottky device - Google Patents
Sic-based trench-type schottky device Download PDFInfo
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
- H01L29/12—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
- H01L29/16—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed including, apart from doping materials or other impurities, only elements of Group IV of the Periodic Table
- H01L29/1608—Silicon carbide
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
- H01L29/06—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions
- H01L29/0657—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 the shape of the body
- H01L29/0661—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 the shape of the body specially adapted for altering the breakdown voltage by removing semiconductor material at, or in the neighbourhood of, a reverse biased junction, e.g. by bevelling, moat etching, depletion etching
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/40—Electrodes ; Multistep manufacturing processes therefor
- H01L29/43—Electrodes ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
- H01L29/47—Schottky barrier electrodes
-
- 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
- H01L29/66053—Multistep manufacturing processes of devices having a semiconductor body comprising crystalline silicon carbide
- H01L29/6606—Multistep manufacturing processes of devices having a semiconductor body comprising crystalline silicon carbide the devices being controllable only by variation of the electric current supplied or the electric potential applied, to one or more of the electrodes carrying the current to be rectified, amplified, oscillated or switched, e.g. two-terminal devices
-
- 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
- H01L29/86—Types of semiconductor device ; Multistep manufacturing processes therefor controllable only by variation of the electric current supplied, or only the electric potential applied, to one or more of the electrodes carrying the current to be rectified, amplified, oscillated or switched
- H01L29/861—Diodes
- H01L29/872—Schottky diodes
- H01L29/8725—Schottky diodes of the trench MOS barrier type [TMBS]
Definitions
- Taiwan Application Serial Number 101148717 filed on Dec. 20, 2012, the disclosure of which is hereby incorporated by reference herein in its entirety
- the present disclosure relates to a SiC-based trench-type Schottky device.
- a Schottky barrier diode is an unipolar device in which electrons serve as the main charge carriers for transporting current.
- the device has a low forward voltage drop and a fast switching.
- the leakage current of Schottky diodes increases as reverse bias increases because of the lowering of Schottky barrier under high electric field.
- a high work function is usually used to provide a high Schottky barrier, which will in turn increase the forward voltage drop and turn-on power loss of the device.
- the Schottky diode with a trench structure is one of solutions proposed to compromise above mentioned trade-offs.
- a trench-type Schottky diode usually comprises a plurality of mesas separated by a plurality of trenches.
- a Schottky contact with a lower barrier formed on the mesa provides a low forward voltage drop, while a MOS structure or a Schottky contact with a higher barrier formed in the trenches shield the electric field on the low barrier contact and thus reduces the leakage current at the reverse bias.
- a edge termination structure is usually incorporated in Schottky devices to prevent the premature breakdown due to surface field crowding around the edge of electrode.
- the edge termination structure may be a field plate, a junction termination extension (JTE) or a floating guard rings.
- JTE and floating guard rings form pn junctions by ion implantations around the edges of the device to perturb the surface electric field distribution and improve the blocking capability of the device.
- the ion implantation is usually implemented at up to several hundred ° C. and then post-annealed at a temperature above 1600° C. to activate the dopants, thus make it a costly process.
- Etch terminations such as bevels used in silicon thyristors require a large area and are also not applicable for devices without PNpn junctions.
- one embodiment provides a SiC-based trench-type Schottky device comprising: a SiC substrate having a first surface and an opposing second surface; a first contact metal formed on the second surface of the SiC substrate and configured for forming an ohmic contact between the first contact metal and the SiC substrate; a SiC drift layer formed on the first surface of the SiC substrate and including a cell region and a termination region enclosing the cell region; a plurality of first spaced trenches with a first depth formed in the cell region; a plurality of second spaced trenches with a second depth less than the first depth; a plurality of mesas formed in the SiC drift layer, each defined between neighboring ones of the spaced trenches; an insulating layer formed on sidewalls and bottoms of the spaced trenches; and a second contact metal formed on the mesas and the insulating layer, extending from the cell region to the termination region, and configured for forming a Schot
- another embodiment provides a SiC-based trench-type Schottky device comprising: a SiC substrate having a first surface and an opposing second surface; a first contact metal formed on the second surface of the SiC substrate and configured for forming an ohmic contact between the first contact metal and the SiC substrate; a SiC drift layer formed on the first surface of the SiC substrate and including a cell region and a termination region enclosing the cell region; a plurality of first spaced trenches with a first depth formed in the cell region; a plurality of second spaced trenches with a second depth less than the first depth; a plurality of mesas formed in the SiC drift layer, each defined between neighboring ones of the spaced trenches; a second contact metal layer formed on the mesas and configured for forming a first Schottky contact between the second contact metal and the mesas of the SiC substrate; and a third contact metal formed on sidewalls and bottoms of the spaced
- the ratio of the opening area of the second spaced trenches in total to the area of the termination region is larger than the ratio of the opening area of the first spaced trenches in total to the area of the cell region.
- the SiC drift layer further comprises: a transition region interposed between the cell region and the termination region, wherein a plurality of third spaced trenches with a third depth less than the first depth and more than the second depth are formed in the transition region.
- FIG. 1 schematically shows a vertical cross-section diagram of a SiC-based trench-type Schottky device according to a first embodiment of the present disclosure.
- FIG. 2 schematically shows a top-view layout of the SiC-based trench-type Schottky device in the first embodiment.
- FIG. 3 schematically shows a vertical cross-section diagram of a SiC-based trench-type Schottky device according to a second embodiment of the present disclosure.
- FIGS. 4A and 4B schematically show vertical cross-section and top-view layout diagrams of a SiC-based trench-type Schottky device according to a third embodiment of the present disclosure, respectively.
- FIG. 5 schematically shows a vertical cross-section diagram of the SiC-based trench-type Schottky device in the fourth embodiment.
- FIG. 6 schematically shows a vertical cross-section diagram of a SiC-based trench-type Schottky device according to a fifth embodiment of the present disclosure.
- FIG. 7 schematically shows a vertical cross-section diagram of a SiC-based trench-type Schottky device according to a sixth embodiment of the present disclosure.
- FIG. 8 schematically shows a vertical cross-section diagram of a SiC-based trench-type Schottky device according to a seventh embodiment of the present disclosure.
- FIG. 1 schematically shows a vertical cross-section diagram of a SiC-based trench-type Schottky device according to a first embodiment of the present disclosure.
- the Schottky device 100 includes a SiC substrate 110 , a first contact metal 120 , a SiC drift layer 130 , a plurality of first spaced trenches 140 , a plurality of second spaced trenches 150 , a plurality of mesas 141 and 151 , an insulating layer 160 , a conductor member 170 , and a second contact metal 180 .
- Each component of the Schottky device 100 will be described below in detail.
- the SiC substrate 110 is used as a supporting body for the Schottky device 100 and the fabrication thereof in the semiconductor manufacturing process.
- the SiC substrate 110 can be a heavily doped N-type (referred to as N + -type hereinafter) 4H-SiC semiconductor substrate; for example, an N + -type 4H-SiC wafer of 4 inches in diameter and 350 ⁇ m in thickness with a dopant concentration of 1 ⁇ 10 19 cm ⁇ 3 .
- 4H is one of polytype forms of silicon carbide (SiC), and “H” means the hexagonal crystal lattice structure.
- the SiC substrate 110 can be of another polytype of silicon carbide, such as 3C-SiC, 6H-SiC, or 15R-SiC, where “C” and “R” denote the cubic and rhombohedral crystal lattice structures, respectively.
- the SiC substrate 110 has an upper surface and an opposing lower surface.
- the first contact metal 120 can be disposed on the lower surface of the SiC substrate 110 to form an ohmic contact of low resistance between the first contact metal 120 and the SiC substrate 110 .
- the first contact metal 120 can be used as a cathode of the Schottky device 100 .
- the first contact metal 120 can formed of nickel (Ni).
- Ni nickel
- a Ni film with a thickness of 200 nm can be deposited by the physical vapor deposition (PVD) and treated by annealing at 950° C. for 30 minutes, so that an ohmic contact can be formed on the lower surface of the N + -type 4H-SiC substrate 110 .
- the first contact metal 120 can be formed of another metal material and/or of another thickness. It is noticed that the Schottky device 100 is to be fabricated on the upper surface of the SiC substrate 110 .
- the SiC drift layer 130 can be formed on the upper surface of the SiC substrate 110 , so as to provide a main body for trench fabrication and device operation of the trench-type Schottky device according to the embodiment.
- the SiC drift layer 130 can be a lightly doped N-type (referred to as N ⁇ -type hereinafter) 4H-SiC epitaxial layer.
- the SiC drift layer 130 can be formed of an N ⁇ -type 4H-SiC epitaxial layer of 6 ⁇ m in thickness with a dopant concentration of 6 ⁇ 10 15 cm ⁇ 3 .
- the SiC drift layer 130 can be of another polytype of silicon carbide, such as 3C-SiC, 6H-SiC, or 15R-SiC, of another thickness and dopant concentration.
- a buffer layer 190 of N-type 4H-SiC can be disposed between the SiC drift layer 130 and the SiC substrate 110 , so as to reduce the defects produced during the epitaxial growth of the SiC drift layer 130 , such as micropipe density (MPD) and etching pit density (EPD).
- MPD micropipe density
- EPD etching pit density
- FIG. 2 schematically shows a top-view layout of the SiC-based trench-type Schottky device 100 in the first embodiment.
- the top surface of the SiC drift layer 130 can be arranged into a cell region 131 and a termination region 132 , wherein the termination region 132 is disposed around the edge area of the Schottky device 100 , and the cell region 131 is disposed at the center area of the Schottky device 100 and enclosed by the termination region 132 .
- the first spaced trenches 140 having a first trench depth and the second spaced trenches 150 having a second trench depth can be formed in the cell region 131 and the termination region 132 , respectively, by the photolithography and the reactive ion etching (RIE) processes.
- RIE reactive ion etching
- a first SiO 2 layer (not shown) with a thickness of 3 ⁇ m can be deposited on the SiC drift layer 130 .
- the top-view patterns of the first spaced trenches 140 , the second spaced trenches 150 , and the mesas 141 and 151 can be defined by using the photolithography, so as to remove photoresist above the first and second spaced trenches 140 and 150 and reserve photoresist above the mesas 141 and 151 .
- the CF 4 /O 2 gas can be used in the RIE process to remove the exposed areas of the first SiO 2 layer, and the remaining first SiO 2 layer can be used as a hard mask for the following trench etching.
- the first and second spaced trenches 140 and 150 can be formed in the SiC drift layer 130 by using the RIE process with the SF 6 /O 2 gas.
- proper conditions of the RIE process can be tuned and suitable opening patterns of the first and second spaced trenches 140 and 150 can be set, so that the ratio of the opening area of the second spaced trenches 150 in total to the area of the termination region 132 is larger than the ratio of the opening area of the first spaced trenches 140 in total to the area of the cell region 131 , after the spaced trenches 140 and 150 are fabricated.
- each second spaced trench 150 can be larger than that of each first spaced trench 140 , so that the etching rate for the second spaced trenches 150 is less than that for the first spaced trenches 140 due to the etching gas may be locally consumed faster at the second spaced trenches 150 and hence their etching rate is relatively lower.
- the aspect ratio of opening patterns of the first spaced trenches 140 can be less than that of the second spaced trenches 150 , so that the etched depth of the second spaced trenches 150 in the termination region 132 can be less than that of the first spaced trenches 140 in the cell region 131 after the RIE process, according to the microloading effect and the aspect ratio dependent etch rate (ARDE) effect in the RIE, as mentioned in, for example, J. Vac. Sci. Technol. A, 12(4), p. 1962, 1994. and J. Micromech. Microeng. 20, 075022, 2010
- the first SiO 2 layer can be removed, for example, by the hydrogen fluoride (HF) etching. Then, a second SiO 2 film (not shown) with a thickness of 50 nm can be grown on the SiC drift layer 130 by the wet oxidation process, and a second SiO 2 film (not shown) with a thickness of 200 nm can be grown on the first SiO 2 film by the plasma-enhanced chemical vapor deposition (PECVD) process.
- PECVD plasma-enhanced chemical vapor deposition
- a photoresist layer (not shown) with a thickness of about 1000 nm can be spin-coated on the second SiO 2 layer, and then the second SiO 2 layer on the mesas 141 and 151 is removed by the etching back process. After the remaining photoresist layer is then removed, the second SiO 2 layer on the sidewalls and bottoms of the first and second spaced trenches 140 and 150 remains to be the insulating layer 160 .
- the conducting material 170 can be fabricated, for example, by depositing a heavily doped polysilicon layer with a thickness of about 2 ⁇ m on the SiC drift layer 130 , so as to fill the spaced trenches 140 and 150 .
- the Chemical Mechanical Planarization (CMP) process can be applied to the extra polysilicon and stop at the upper surfaces of the mesas 141 and 151 .
- the conducting material 170 is formed of the polysilicon filled in the spaced trenches 140 and 150 .
- a Ti film with a thickness of 50 nm can be deposited on the SiC drift layer 130 to cover the spaced trenches 140 and 150 and the conductor members 170 .
- the Ti film is then treated by annealing at 500° C. for 10 minutes, so that a Schottky contact can be formed on the mesas 141 and 151 , between the Ti film and the SiC drift layer 130 .
- an Al—Si or Al—Cu alloy layer (not shown) with a thickness of 4 ⁇ m can be deposited on the Ti film, extending from the cell region 131 to the termination region 132 , to be used as an anode of the Schottky device 100 .
- the combination of the Ti film and the alloy film is referred to as the second contact metal 180 .
- the Schottky devices formed on the N + -type 4H-SiC wafer can be separated into individual Schottky device dice, by the die sawing or laser cutting along scribe lines in the termination region 132 .
- Each Schottky device die can be further packaged to be a discrete SiC-based trench-type Schottky device of the present embodiment.
- the horizontal cross-sections of the first and second spaced trenches 140 and 150 can be shaped in bars, rectangles, or hexagons; but the present disclosure is not limited thereto.
- the termination region is usually formed in a beveled structure, especially in a positive bevel, by mechanical cutting. Since defects would be produced on its edge surfaces due to the mechanical cutting, the maximum endurable breakdown voltage in the termination region is less than that in the cell region of the device.
- the reason for the positive bevel formed in the termination region is that the semiconductor pn junction may have a wider depletion region in its beveled termination surface than in its cell region, leading that the electric field would have a smaller strength at the bevel of the termination region than in the cell region, so as to prevent a premature breakdown happened in the termination region.
- the electric field strength in the termination region is about 70% of that in the cell region for a bevel of 45° angle.
- a beveled semiconductor device may have manufacturing cost disadvantages in the mechanical cutting and polishing treatment and layout area substrate wafer, so it is not applicable to the SiC-based device with a small area, such as a Schottky diode.
- the SiC material itself has a threshold breakdown voltage higher than that of Si, so a SiC-based pn junction can be reverse-biased to enter the reach-through mode, i.e., the lightly doped drift layer of a SiC-based device can be depleted completely.
- the deeper first spaced trenches 140 are formed in the cell region 131 , for example, with a depth of 2 ⁇ m, while the shallower second spaced trenches 150 are formed in the termination region 132 , for example, with a depth of 0.7 ⁇ m.
- the electric field strength in the termination region 132 can be about 75% of that in the cell region 131 , so the edge termination can function well. This provides cost advantages by avoiding expensive ion implantation and high-temperature annealing processes and bevel cutting treatment in the device manufacturing.
- FIG. 3 schematically shows a vertical cross-section diagram of a SiC-based trench-type Schottky device 102 according to a second embodiment of the present disclosure.
- a top-view layout of the Schottky device 102 in the embodiment can be referred to FIG. 2 , also.
- the first spaced trenches 140 can have uniform depths in the cell region 131
- the second spaced trenches 150 can have stepped depths in the termination region 132 , wherein the second spaced trenches 150 can have decreasing depths as further away from the cell region 131 , and the maximum depth of the second spaced trenches 150 can be less than the depth of the first spaced trenches 140 .
- Fabrication process of the Schottky device 102 in this embodiment is similar to that of the Schottky device 100 in the first embodiment, except that the first spaced trenches 140 in the cell region 131 can have opening pattern of uniform size while the second spaced trenches 150 in the termination region 132 can have opening patterns of increasing size. Consequently, the ratio of the opening area of the second spaced trenches 150 in total to the area of the termination region 132 is larger than the ratio of the opening area of the first spaced trenches 140 in total to the area of the cell region 131 .
- each of the second spaced trenches 150 can have a larger opening area than the first spaced trenches 140 , and the second spaced trench 150 close to the cell region 131 can have a larger opening area than the one away from the cell region 131 .
- the first spaced trenches 140 and the second spaced trenches 150 can be fabricated concurrently in the SiC drift layer 130 , with the second spaced trenches 150 having decreasing depths as further away from the center of the Schottky device 102 .
- the device reliability can be improved due to gradual decrease of electric field in the termination region 132 when the Schottky device 102 is in the reverse-biased mode.
- FIGS. 4A and 4B schematically show vertical cross-section and top-view layout diagrams of a SiC-based trench-type Schottky device 103 , respectively, according to a third embodiment of the present disclosure.
- the top surface of the SiC drift layer 130 can include a transition region 133 interposed between the cell region 131 and the termination region 132 .
- a plurality of third spaced trenches 145 can be formed in the transition region 133 , which functions as a buffer region between the cell region 131 and the termination region 132 .
- the first spaced trenches 140 can have a first depth
- the second spaced trenches 150 can have a second depth
- the third spaced trenches 145 can have a third depth, with the third depth less than the first depth and more than the second depth. Fabrication process and the other composition parts of the Schottky device 103 in this embodiment are similar to that of the Schottky device 100 in the first embodiment.
- the first spaced trenches 140 in the cell region 131 can have a first opening pattern of uniform size
- the second spaced trenches 150 in the termination region 132 can have a second opening pattern of uniform size
- the third spaced trenches 145 in the transition region 133 can have a third opening pattern of uniform size, so that the ratio of the opening area of the third spaced trenches 145 in total to the area of the transition region 133 is larger than the ratio of the opening area of the first spaced trenches 140 in total to the area of the cell region 131 while less than the ratio of the opening area of the second spaced trenches 150 in total to the area of the termination region 132 .
- each of the third spaced trenches 145 can have an opening area larger than each of the first spaced trenches 140 while less than each of the second spaced trenches 150 .
- the first spaced trenches 140 , the third spaced trenches 145 , and the second spaced trenches 150 can be fabricated concurrently in the SiC drift layer 130 with the trenches 140 , 145 , and 150 having decreasingly stepped depths as further away from the center of the Schottky device 103 .
- the device reliability can be improved due to gradual decrease of electric field in the Schottky device 103 when it is in the reverse-biased mode.
- FIG. 5 schematically shows a vertical cross-section diagram of the SiC-based trench-type Schottky device 400 in the fourth embodiment, which is the same as the first embodiment except that the polysilicon layer filled in the trenches is omitted.
- the top surface of the SiC drift layer 130 can be arranged into a cell region 131 and a termination region 132 , wherein the termination region 132 is disposed around the edge area of the Schottky device 400 , and the cell region 131 is disposed at the center area of the Schottky device 400 and enclosed by the termination region 132 .
- a first SiO 2 layer (not shown) with a thickness of 3 ⁇ m can be deposited on the SiC drift layer 130 .
- the top-view patterns of the first spaced trenches 140 , the second spaced trenches 150 , and the mesas 141 and 151 can be defined by using the photolithography, so as to remove photoresist (not shown) above the first and second spaced trenches 140 and 150 and reserve photoresist (not shown) above the mesas 141 and 151 .
- the CF 4 /O 2 gas can be used in the RIE process to remove the exposed areas of the first SiO 2 layer, and the remaining first SiO 2 layer can be used as a hard mask for the following trench etching.
- the first and second spaced trenches 140 and 150 can be formed in the SiC drift layer 130 by using the RIE process with the SF 6 /O 2 gas.
- the etching rate for the second spaced trenches 150 is less than that for the first spaced trenches 140 due to the etching gas may be locally consumed too much at the second spaced trenches 150 and hence their etching rate is decreased temporarily.
- the aspect ratio of opening patterns of the first spaced trenches 140 can be less than that of the second spaced trenches 150 , so that the trench depth of the second spaced trenches 150 in the termination region 132 can be less than that of the first spaced trenches 140 in the cell region 131 after the RIE process, according to the microloading effect and the ARDE effect in the RIE.
- the first SiO 2 layer can be removed, for example, by the HF etching.
- a second SiO 2 film (not shown) with a thickness of 50 nm can be grown on the SiC drift layer 130 by the wet oxidation process, and a second SiO 2 film (not shown) with a thickness of 200 nm can be grown on the first SiO 2 film by the PECVD process.
- the combination of the first and second SiO 2 films is referred to as the second SiO 2 layer.
- a photoresist layer (not shown) with a thickness of about 1000 nm can be spin-coated on the second SiO 2 layer, and then the second SiO 2 layer on the mesas 141 and 151 is removed by the etching back process. After the remaining photoresist layer is then removed, the second SiO 2 layer on the sidewalls and bottoms of the first and second spaced trenches 140 and 150 remains to be the insulating layer 160 .
- a Ti film with a thickness of 50 nm can be deposited on the SiC drift layer 130 and concurrently fill the spaced trenches 140 and 150 .
- the second contact metal 180 can take the place of the conducting material 170 and cover the insulating layer 160 layer in the first embodiment.
- the Ti film is treated by annealing at 500° C. for 10 minutes, so that Schottky contacts can be formed on the mesas 141 and 151 , between the second contact metal 180 and the SiC drift layer 130 .
- the MOS structure can be formed in the trenches 140 and 150 and the Schottky contacts of the Schottky device 400 can be formed, both due to the formation of the Ti film.
- an Al—Si or Al—Cu alloy layer with a thickness of 4 ⁇ m can be deposited on the Ti film, extending from the cell region 131 to the termination region 132 , to be used as an anode of the Schottky device 400 .
- the combination of the Ti film and the alloy film is referred to as the second contact metal 180 .
- the Schottky devices 400 formed on the SiC wafer (the SiC substrate) can be separated into individual Schottky device dice, by the die sawing or laser cutting along scribe lines in the termination region 132 . Each Schottky device die can be further packaged to be a discrete SiC-based trench-type Schottky device of this embodiment.
- one of the main features can be that trenches of different depths are respectively formed in the cell and termination regions of the SiC-based Schottky device, and it can be applicable to the Schottky device with the structure of dual-metal trench-type barrier devices as described below.
- FIG. 6 schematically shows a vertical cross-section diagram of a SiC-based trench-type Schottky device according to a fifth embodiment of the present disclosure, which is similar to the structure of the first embodiment, except for adapting the dual-metal trench barriers. As shown in FIG.
- the Schottky device 200 includes a SiC substrate 210 , a first contact metal 220 , a SiC drift layer 230 , a plurality of first spaced trenches 240 , a plurality of second spaced trenches 250 , a plurality of mesas 241 and 251 , a second contact metal 260 , and a third contact metal 270 .
- a SiC substrate 210 a SiC substrate 210
- first contact metal 220 a SiC drift layer 230
- a plurality of first spaced trenches 240 a plurality of second spaced trenches 250
- mesas 241 and 251 a plurality of mesas 241 and 251
- second contact metal 260 includes a third contact metal 270 .
- the SiC substrate 210 is used as a supporting body for the Schottky device 200 and the fabrication thereof in the manufacturing process.
- the SiC substrate 210 can be a N + -type 4H-SiC semiconductor substrate; for example, an N + -type 4H-SiC wafer of 4 inches in diameter and 350 ⁇ m in thickness with a dopant concentration of 1 ⁇ 10 19 cm ⁇ 3 .
- 4H is one of polytype forms of SiC.
- the SiC substrate 210 can be of another polytype of silicon carbide, such as 3C-SiC, 6H-SiC, or 15R-SiC.
- the SiC substrate 210 has an upper surface and an opposing lower surface.
- the first contact metal 220 can be disposed on the lower surface of the SiC substrate 210 to form an ohmic contact of low resistance between the first contact metal 220 and the SiC substrate 210 .
- the first contact metal 220 can be used as a cathode of the Schottky device 200 .
- the first contact metal 220 can formed of Ni.
- a Ni film with a thickness of 200 nm can be deposited by the PVD and treated by annealing at 950° C. for 30 minutes, so that an ohmic contact can be formed on the lower surface of the N + -type 4H-SiC substrate 210 .
- the first contact metal 220 can be formed of another metal material and/or of another thickness. It is noticed that the Schottky device 200 is to be fabricated on the upper surface of the SiC substrate 210 .
- the SiC drift layer 230 can be formed on the upper surface of the SiC substrate 210 , so as to provide a main body for trench fabrication and device operation of the trench-type Schottky device according to the embodiment.
- the SiC drift layer 230 can be an N ⁇ -type 4H-SiC epitaxial layer.
- the SiC drift layer 230 can be formed of an N ⁇ -type 4H-SiC epitaxial layer of 6 ⁇ m in thickness with a dopant concentration of 6 ⁇ 10 15 cm ⁇ 3 .
- the SiC drift layer 230 can be of another polytype of silicon carbide, such as 3C-SiC, 6H-SiC, or 15R-SiC, of another thickness and dopant concentration.
- a buffer layer 290 of N-type 4H-SiC can be disposed between the SiC drift layer 230 and the SiC substrate 210 , so as to reduce the defects produced during the epitaxial growth of the SiC drift layer 230 , such as MPD and EPD.
- FIG. 2 can also provide top-view layout of the SiC-based trench-type Schottky device 200 in the present embodiment.
- the top surface of the SiC drift layer 230 can be arranged into a cell region 231 and a termination region 232 , wherein the termination region 232 is disposed around the edge area of the Schottky device 200 , and the cell region 231 is disposed at the center area of the Schottky device 200 and enclosed by the termination region 232 .
- a Ti film with a thickness of 50 nm and a 3 ⁇ m oxide layer can be deposited on the SiC drift layer 230 in sequence, and then the top-view patterns of the first spaced trenches 240 , the second spaced trenches 250 , and the mesas 241 and 251 can be defined by using the photolithography, so as to remove photoresist above the first and second spaced trenches 240 and 250 and reserve photoresist above the mesas 241 and 251 .
- the CF4 gas can be used in the RIE process to remove the exposed areas of the oxide film, and the oxide film can be used as a hard mask for removing the exposed Ti layer and the following trench etching.
- the first and second spaced trenches 240 and 250 can be formed in the SiC drift layer 230 by using the RIE process with the SF 6 /O 2 gas.
- proper etching of the RIE process can be tuned and suitable opening patterns of the first and second spaced trenches 240 and 250 can be set, so that the ratio of the opening area of the second spaced trenches 250 in total to the area of the termination region 232 is larger than the ratio of the opening area of the first spaced trenches 240 in total to the area of the cell region 231 , after the spaced trenches 240 and 250 are fabricated.
- each second spaced trench 250 can be larger than that of each first spaced trench 240 , so that the etching rate for the second spaced trenches 250 is less than that for the first spaced trenches 140 due to the etching gas may be locally consumed too much at the second spaced trenches 250 and hence their etching rate is decreased temporarily.
- the aspect ratio of opening patterns of the first spaced trenches 240 can be less than that of the second spaced trenches 250 , so that the trench depth of the second spaced trenches 250 in the termination region 232 can be less than that of the first spaced trenches 240 in the cell region 231 after the RIE process, according to the microloading effect and the ARDE effect in the RIE.
- the 50 nm Ti film serves as the second contact metal 260 .
- a Ni film with a thickness of 50 nm can be deposited conformally in trenches 240 and 250 as the third contact metal 270 ; i.e., the third contact metal 270 is covering the second contact metal 260 on the mesas 241 and 251 and sidewalls and bottoms 242 and 252 of the first and second spaced trenches 240 and 250 .
- a first Schottky contact can be formed on the mesas 241 and 251 between the second contact metal (the Ti film in this embodiment) 260 and the SiC drift layer 230
- a second Schottky contact can be formed on the sidewalls and bottoms 242 and 252 of the first and second spaced trenches 240 and 250 between the third contact metal (the Ni film in this embodiment) 270 and the SiC drift layer 230 . Because nickel has a work function larger than titanium, the second Scottky contact has a higher barrier than the first Schottky contact.
- the Schottky device 200 when the Schottky device 200 is forward-biased, the first Schottky contact can be turned on first, providing a lower forward voltage drop and power loss.
- the Schottky device 200 when the Schottky device 200 is in the reverse-biased mode, the depletion region of the high barrier second Schottky contact can extend to shield electric field on the low barrier first Schottky contact and thus reduces the leakage current.
- an Al—Si or Al—Cu alloy layer (not shown) with a thickness of 4 ⁇ m can be deposited on the third contact metal 270 , extending from the cell region 231 to the termination region 232 , to be used as an anode of the Schottky device 200 .
- the Schottky devices formed on the N + -type 4H-SiC wafer (the SiC substrate) can be separated into individual Schottky device dice, by the die sawing or laser cutting along scribe lines in the termination region 132 .
- Each Schottky device die can be further packaged to be a discrete SiC-based trench-type Schottky device of the present embodiment.
- FIG. 7 schematically shows a vertical cross-section diagram of a SiC-based trench-type Schottky device 202 according to a sixth embodiment of the present disclosure.
- a top-view layout of the Schottky device 202 in the embodiment can also be referred to FIG. 2 , also.
- the first spaced trenches 240 can have uniform depths in the cell region 231
- the second spaced trenches 250 can have stepped depths in the termination region 232 , wherein the second spaced trenches 250 can have decreasing depths as further away from the cell region 231 , and the maximum depth of the second spaced trenches 250 can be less than the depth of the first spaced trenches 240 .
- Fabrication process of the Schottky device 202 in this embodiment is similar to that of the Schottky device 200 in the fifth embodiment, except that the first spaced trenches 240 in the cell region 231 can have opening patterns of uniform size while the second spaced trenches 250 in the termination region 232 can have opening patterns of increasing size. Consequently, the ratio of the opening area of the second spaced trenches 250 in total to the area of the termination region 232 is larger than the ratio of the opening area of the first spaced trenches 240 in total to the area of the cell region 231 .
- each of the second spaced trenches 250 can have a larger opening area than the first spaced trenches 240 , and the second spaced trench 250 close to the cell region 231 can have a larger opening area than the one away from the cell region 232 .
- the first spaced trenches 240 and the second spaced trenches 250 can be fabricated concurrently in the SiC drift layer 130 , with the second spaced trenches 250 having decreasing depths as further away from the center of the Schottky device 202 .
- the device reliability can be improved due to gradual decrease of electric field in the termination region 232 when the Schottky device 202 is reversely biased.
- FIG. 8 schematically shows a vertical cross-section diagram of a SiC-based trench-type Schottky device 203 according to a seventh embodiment of the present disclosure.
- a top-view layout of the Schottky device 203 in the embodiment can also be referred to FIG. 4B , also.
- the top surface of the SiC drift layer 230 can include a transition region 233 interposed between the cell region 231 and the termination region 232 .
- a plurality of third spaced trenches 245 can be formed in the transition region 233 , which functions as a buffer region between the cell region 231 and the termination region 232 .
- the first spaced trenches 240 can have uniform first depths
- the second spaced trenches 250 can have uniform second depths
- the third spaced trenches 245 can have uniform third depths, with the third depth less than the first depth and more than the second depth. Fabrication process and the other composition parts of the Schottky device 203 in this embodiment are similar to that of the Schottky device 200 in the fifth embodiment.
- the first spaced trenches 240 in the cell region 231 can have a first opening pattern of uniform size
- the second spaced trenches 250 in the termination region 232 can have a second opening pattern of uniform size
- the third spaced trenches 245 in the transition region 233 can have a third opening pattern of uniform size, so that the ratio of the opening area of the third spaced trenches 245 in total to the area of the transition region 233 is larger than the ratio of the opening area of the first spaced trenches 240 in total to the area of the cell region 231 while less than the ratio of the opening area of the second spaced trenches 250 in total to the area of the termination region 232 .
- each of the third spaced trenches 245 can have an opening area larger than each of the first spaced trenches 240 while less than each of the second spaced trenches 250 .
- the first spaced trenches 240 , the third spaced trenches 245 , and the second spaced trenches 250 can be fabricated concurrently in the SiC drift layer 230 with the trenches 240 , 245 , and 250 having decreasingly stepped depths as further away from the center of the Schottky device 203 .
- the device reliability can be improved due to gradual decrease of electric field in the Schottky device 203 when it is in the reverse-biased mode.
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Abstract
Description
- The present application is based on, and claims priority from, Taiwan Application Serial Number 101148717, filed on Dec. 20, 2012, the disclosure of which is hereby incorporated by reference herein in its entirety
- The present disclosure relates to a SiC-based trench-type Schottky device.
- A Schottky barrier diode is an unipolar device in which electrons serve as the main charge carriers for transporting current. The device has a low forward voltage drop and a fast switching. However, the leakage current of Schottky diodes increases as reverse bias increases because of the lowering of Schottky barrier under high electric field. To reduce the leakage current at the reverse bias, a high work function is usually used to provide a high Schottky barrier, which will in turn increase the forward voltage drop and turn-on power loss of the device. The Schottky diode with a trench structure is one of solutions proposed to compromise above mentioned trade-offs. A trench-type Schottky diode usually comprises a plurality of mesas separated by a plurality of trenches. A Schottky contact with a lower barrier formed on the mesa provides a low forward voltage drop, while a MOS structure or a Schottky contact with a higher barrier formed in the trenches shield the electric field on the low barrier contact and thus reduces the leakage current at the reverse bias.
- A edge termination structure is usually incorporated in Schottky devices to prevent the premature breakdown due to surface field crowding around the edge of electrode. The edge termination structure may be a field plate, a junction termination extension (JTE) or a floating guard rings. JTE and floating guard rings form pn junctions by ion implantations around the edges of the device to perturb the surface electric field distribution and improve the blocking capability of the device. In SiC carbide devices, the ion implantation is usually implemented at up to several hundred ° C. and then post-annealed at a temperature above 1600° C. to activate the dopants, thus make it a costly process. Etch terminations such as bevels used in silicon thyristors require a large area and are also not applicable for devices without PNpn junctions.
- According to one aspect of the present disclosure, one embodiment provides a SiC-based trench-type Schottky device comprising: a SiC substrate having a first surface and an opposing second surface; a first contact metal formed on the second surface of the SiC substrate and configured for forming an ohmic contact between the first contact metal and the SiC substrate; a SiC drift layer formed on the first surface of the SiC substrate and including a cell region and a termination region enclosing the cell region; a plurality of first spaced trenches with a first depth formed in the cell region; a plurality of second spaced trenches with a second depth less than the first depth; a plurality of mesas formed in the SiC drift layer, each defined between neighboring ones of the spaced trenches; an insulating layer formed on sidewalls and bottoms of the spaced trenches; and a second contact metal formed on the mesas and the insulating layer, extending from the cell region to the termination region, and configured for forming a Schottky contact between the second contact metal and the mesas of the SiC substrate.
- According to another aspect of the present disclosure, another embodiment provides a SiC-based trench-type Schottky device comprising: a SiC substrate having a first surface and an opposing second surface; a first contact metal formed on the second surface of the SiC substrate and configured for forming an ohmic contact between the first contact metal and the SiC substrate; a SiC drift layer formed on the first surface of the SiC substrate and including a cell region and a termination region enclosing the cell region; a plurality of first spaced trenches with a first depth formed in the cell region; a plurality of second spaced trenches with a second depth less than the first depth; a plurality of mesas formed in the SiC drift layer, each defined between neighboring ones of the spaced trenches; a second contact metal layer formed on the mesas and configured for forming a first Schottky contact between the second contact metal and the mesas of the SiC substrate; and a third contact metal formed on sidewalls and bottoms of the spaced trenches and configured for forming a second Schottky contact between the third contact metal and the sidewalls and bottoms of the spaced trenches of the SiC substrate; wherein work function of the second contact metal is less than that of the third contact metal.
- In some embodiments, the ratio of the opening area of the second spaced trenches in total to the area of the termination region is larger than the ratio of the opening area of the first spaced trenches in total to the area of the cell region.
- In some embodiments, the SiC drift layer further comprises: a transition region interposed between the cell region and the termination region, wherein a plurality of third spaced trenches with a third depth less than the first depth and more than the second depth are formed in the transition region.
- Further scope of applicability of the present application will become more apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the disclosure, are given by way of illustration only, since various changes and modifications within the spirit and scope of the disclosure will become apparent to those skilled in the art from this detailed description.
- The present disclosure will become more fully understood from the detailed description given herein below and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present disclosure and wherein:
-
FIG. 1 schematically shows a vertical cross-section diagram of a SiC-based trench-type Schottky device according to a first embodiment of the present disclosure. -
FIG. 2 schematically shows a top-view layout of the SiC-based trench-type Schottky device in the first embodiment. -
FIG. 3 schematically shows a vertical cross-section diagram of a SiC-based trench-type Schottky device according to a second embodiment of the present disclosure. -
FIGS. 4A and 4B schematically show vertical cross-section and top-view layout diagrams of a SiC-based trench-type Schottky device according to a third embodiment of the present disclosure, respectively. -
FIG. 5 schematically shows a vertical cross-section diagram of the SiC-based trench-type Schottky device in the fourth embodiment. -
FIG. 6 schematically shows a vertical cross-section diagram of a SiC-based trench-type Schottky device according to a fifth embodiment of the present disclosure. -
FIG. 7 schematically shows a vertical cross-section diagram of a SiC-based trench-type Schottky device according to a sixth embodiment of the present disclosure. -
FIG. 8 schematically shows a vertical cross-section diagram of a SiC-based trench-type Schottky device according to a seventh embodiment of the present disclosure. - For further understanding and recognizing the fulfilled functions and structural characteristics of the disclosure, several exemplary embodiments cooperating with detailed description are presented as the following.
-
FIG. 1 schematically shows a vertical cross-section diagram of a SiC-based trench-type Schottky device according to a first embodiment of the present disclosure. As shown inFIG. 1 , theSchottky device 100 includes aSiC substrate 110, afirst contact metal 120, aSiC drift layer 130, a plurality of first spacedtrenches 140, a plurality of second spacedtrenches 150, a plurality ofmesas insulating layer 160, aconductor member 170, and asecond contact metal 180. Each component of the Schottkydevice 100 will be described below in detail. - The
SiC substrate 110 is used as a supporting body for the Schottkydevice 100 and the fabrication thereof in the semiconductor manufacturing process. In the embodiment, theSiC substrate 110 can be a heavily doped N-type (referred to as N+-type hereinafter) 4H-SiC semiconductor substrate; for example, an N+-type 4H-SiC wafer of 4 inches in diameter and 350 μm in thickness with a dopant concentration of 1×1019 cm−3. Here, 4H is one of polytype forms of silicon carbide (SiC), and “H” means the hexagonal crystal lattice structure. But it is not limited thereto; theSiC substrate 110 can be of another polytype of silicon carbide, such as 3C-SiC, 6H-SiC, or 15R-SiC, where “C” and “R” denote the cubic and rhombohedral crystal lattice structures, respectively. - The
SiC substrate 110 has an upper surface and an opposing lower surface. Thefirst contact metal 120 can be disposed on the lower surface of theSiC substrate 110 to form an ohmic contact of low resistance between thefirst contact metal 120 and theSiC substrate 110. Thus, thefirst contact metal 120 can be used as a cathode of the Schottkydevice 100. Thefirst contact metal 120 can formed of nickel (Ni). For example, a Ni film with a thickness of 200 nm can be deposited by the physical vapor deposition (PVD) and treated by annealing at 950° C. for 30 minutes, so that an ohmic contact can be formed on the lower surface of the N+-type 4H-SiC substrate 110. But it is not limited thereto; thefirst contact metal 120 can be formed of another metal material and/or of another thickness. It is noticed that the Schottkydevice 100 is to be fabricated on the upper surface of theSiC substrate 110. - The
SiC drift layer 130 can be formed on the upper surface of theSiC substrate 110, so as to provide a main body for trench fabrication and device operation of the trench-type Schottky device according to the embodiment. Here, theSiC drift layer 130 can be a lightly doped N-type (referred to as N−-type hereinafter) 4H-SiC epitaxial layer. For example, theSiC drift layer 130 can be formed of an N−-type 4H-SiC epitaxial layer of 6 μm in thickness with a dopant concentration of 6×1015 cm−3. But it is not limited thereto; theSiC drift layer 130 can be of another polytype of silicon carbide, such as 3C-SiC, 6H-SiC, or 15R-SiC, of another thickness and dopant concentration. Moreover, abuffer layer 190 of N-type 4H-SiC can be disposed between theSiC drift layer 130 and theSiC substrate 110, so as to reduce the defects produced during the epitaxial growth of theSiC drift layer 130, such as micropipe density (MPD) and etching pit density (EPD). -
FIG. 2 schematically shows a top-view layout of the SiC-based trench-type Schottkydevice 100 in the first embodiment. Referring to bothFIGS. 1 and 2 , the top surface of theSiC drift layer 130 can be arranged into acell region 131 and atermination region 132, wherein thetermination region 132 is disposed around the edge area of the Schottkydevice 100, and thecell region 131 is disposed at the center area of theSchottky device 100 and enclosed by thetermination region 132. Concurrently, the first spacedtrenches 140 having a first trench depth and the second spacedtrenches 150 having a second trench depth can be formed in thecell region 131 and thetermination region 132, respectively, by the photolithography and the reactive ion etching (RIE) processes. For example, a first SiO2 layer (not shown) with a thickness of 3 μm can be deposited on theSiC drift layer 130. Then, the top-view patterns of the first spacedtrenches 140, the second spacedtrenches 150, and themesas trenches mesas trenches SiC drift layer 130 by using the RIE process with the SF6/O2 gas. - In the trench etching, proper conditions of the RIE process can be tuned and suitable opening patterns of the first and second spaced
trenches trenches 150 in total to the area of thetermination region 132 is larger than the ratio of the opening area of the first spacedtrenches 140 in total to the area of thecell region 131, after thespaced trenches trench 150 can be larger than that of each first spacedtrench 140, so that the etching rate for the second spacedtrenches 150 is less than that for the first spacedtrenches 140 due to the etching gas may be locally consumed faster at the second spacedtrenches 150 and hence their etching rate is relatively lower. In another example, the aspect ratio of opening patterns of the first spacedtrenches 140 can be less than that of the second spacedtrenches 150, so that the etched depth of the second spacedtrenches 150 in thetermination region 132 can be less than that of the first spacedtrenches 140 in thecell region 131 after the RIE process, according to the microloading effect and the aspect ratio dependent etch rate (ARDE) effect in the RIE, as mentioned in, for example, J. Vac. Sci. Technol. A, 12(4), p. 1962, 1994. and J. Micromech. Microeng. 20, 075022, 2010 - After the trench etching, the first SiO2 layer can be removed, for example, by the hydrogen fluoride (HF) etching. Then, a second SiO2 film (not shown) with a thickness of 50 nm can be grown on the
SiC drift layer 130 by the wet oxidation process, and a second SiO2 film (not shown) with a thickness of 200 nm can be grown on the first SiO2 film by the plasma-enhanced chemical vapor deposition (PECVD) process. Hereafter, the combination of the first and second SiO2 films is referred to as the second SiO2 layer. Next, a photoresist layer (not shown) with a thickness of about 1000 nm can be spin-coated on the second SiO2 layer, and then the second SiO2 layer on themesas trenches layer 160. - Then, the conducting
material 170 can be fabricated, for example, by depositing a heavily doped polysilicon layer with a thickness of about 2 μm on theSiC drift layer 130, so as to fill the spacedtrenches mesas material 170 is formed of the polysilicon filled in the spacedtrenches - To fabricate the
second contact metal 180, for example, a Ti film with a thickness of 50 nm can be deposited on theSiC drift layer 130 to cover the spacedtrenches conductor members 170. The Ti film is then treated by annealing at 500° C. for 10 minutes, so that a Schottky contact can be formed on themesas SiC drift layer 130. After that, an Al—Si or Al—Cu alloy layer (not shown) with a thickness of 4 μm can be deposited on the Ti film, extending from thecell region 131 to thetermination region 132, to be used as an anode of theSchottky device 100. Wherein, the combination of the Ti film and the alloy film is referred to as thesecond contact metal 180. - After the above fabrication process, the Schottky devices formed on the N+-type 4H-SiC wafer (the SiC substrate) can be separated into individual Schottky device dice, by the die sawing or laser cutting along scribe lines in the
termination region 132. Each Schottky device die can be further packaged to be a discrete SiC-based trench-type Schottky device of the present embodiment. Moreover, the horizontal cross-sections of the first and second spacedtrenches - Regarding a semiconductor device involved in high current and voltage, such as a thyristor, its termination region is usually formed in a beveled structure, especially in a positive bevel, by mechanical cutting. Since defects would be produced on its edge surfaces due to the mechanical cutting, the maximum endurable breakdown voltage in the termination region is less than that in the cell region of the device. The reason for the positive bevel formed in the termination region is that the semiconductor pn junction may have a wider depletion region in its beveled termination surface than in its cell region, leading that the electric field would have a smaller strength at the bevel of the termination region than in the cell region, so as to prevent a premature breakdown happened in the termination region. For example, the electric field strength in the termination region is about 70% of that in the cell region for a bevel of 45° angle. Nevertheless, a beveled semiconductor device may have manufacturing cost disadvantages in the mechanical cutting and polishing treatment and layout area substrate wafer, so it is not applicable to the SiC-based device with a small area, such as a Schottky diode.
- The SiC material itself has a threshold breakdown voltage higher than that of Si, so a SiC-based pn junction can be reverse-biased to enter the reach-through mode, i.e., the lightly doped drift layer of a SiC-based device can be depleted completely. In the embodiments of the present disclosure, the deeper first spaced
trenches 140 are formed in thecell region 131, for example, with a depth of 2 μm, while the shallower second spacedtrenches 150 are formed in thetermination region 132, for example, with a depth of 0.7 μm. Thereby, the electric field strength in thetermination region 132 can be about 75% of that in thecell region 131, so the edge termination can function well. This provides cost advantages by avoiding expensive ion implantation and high-temperature annealing processes and bevel cutting treatment in the device manufacturing. -
FIG. 3 schematically shows a vertical cross-section diagram of a SiC-based trench-type Schottky device 102 according to a second embodiment of the present disclosure. A top-view layout of theSchottky device 102 in the embodiment can be referred toFIG. 2 , also. Referring to bothFIGS. 2 and 3 , the first spacedtrenches 140 can have uniform depths in thecell region 131, while the second spacedtrenches 150 can have stepped depths in thetermination region 132, wherein the second spacedtrenches 150 can have decreasing depths as further away from thecell region 131, and the maximum depth of the second spacedtrenches 150 can be less than the depth of the first spacedtrenches 140. Fabrication process of theSchottky device 102 in this embodiment is similar to that of theSchottky device 100 in the first embodiment, except that the first spacedtrenches 140 in thecell region 131 can have opening pattern of uniform size while the second spacedtrenches 150 in thetermination region 132 can have opening patterns of increasing size. Consequently, the ratio of the opening area of the second spacedtrenches 150 in total to the area of thetermination region 132 is larger than the ratio of the opening area of the first spacedtrenches 140 in total to the area of thecell region 131. Also, each of the second spacedtrenches 150 can have a larger opening area than the first spacedtrenches 140, and the second spacedtrench 150 close to thecell region 131 can have a larger opening area than the one away from thecell region 131. Thereby, the first spacedtrenches 140 and the second spacedtrenches 150 can be fabricated concurrently in theSiC drift layer 130, with the second spacedtrenches 150 having decreasing depths as further away from the center of theSchottky device 102. The device reliability can be improved due to gradual decrease of electric field in thetermination region 132 when theSchottky device 102 is in the reverse-biased mode. -
FIGS. 4A and 4B schematically show vertical cross-section and top-view layout diagrams of a SiC-based trench-type Schottky device 103, respectively, according to a third embodiment of the present disclosure. Referring toFIGS. 4A and 4B , the top surface of theSiC drift layer 130 can include atransition region 133 interposed between thecell region 131 and thetermination region 132. A plurality of third spacedtrenches 145 can be formed in thetransition region 133, which functions as a buffer region between thecell region 131 and thetermination region 132. Uniformly, the first spacedtrenches 140 can have a first depth, the second spacedtrenches 150 can have a second depth, and the third spacedtrenches 145 can have a third depth, with the third depth less than the first depth and more than the second depth. Fabrication process and the other composition parts of theSchottky device 103 in this embodiment are similar to that of theSchottky device 100 in the first embodiment. - In the embodiment, the first spaced
trenches 140 in thecell region 131 can have a first opening pattern of uniform size, the second spacedtrenches 150 in thetermination region 132 can have a second opening pattern of uniform size, and the third spacedtrenches 145 in thetransition region 133 can have a third opening pattern of uniform size, so that the ratio of the opening area of the third spacedtrenches 145 in total to the area of thetransition region 133 is larger than the ratio of the opening area of the first spacedtrenches 140 in total to the area of thecell region 131 while less than the ratio of the opening area of the second spacedtrenches 150 in total to the area of thetermination region 132. For example, each of the third spacedtrenches 145 can have an opening area larger than each of the first spacedtrenches 140 while less than each of the second spacedtrenches 150. Thereby, according to the fabrication process similar to the first embodiment, the first spacedtrenches 140, the third spacedtrenches 145, and the second spacedtrenches 150 can be fabricated concurrently in theSiC drift layer 130 with thetrenches Schottky device 103. The device reliability can be improved due to gradual decrease of electric field in theSchottky device 103 when it is in the reverse-biased mode. -
FIG. 5 schematically shows a vertical cross-section diagram of the SiC-based trench-type Schottky device 400 in the fourth embodiment, which is the same as the first embodiment except that the polysilicon layer filled in the trenches is omitted. Referring toFIG. 5 , the top surface of theSiC drift layer 130 can be arranged into acell region 131 and atermination region 132, wherein thetermination region 132 is disposed around the edge area of theSchottky device 400, and thecell region 131 is disposed at the center area of theSchottky device 400 and enclosed by thetermination region 132. A first SiO2 layer (not shown) with a thickness of 3 μm can be deposited on theSiC drift layer 130. Then, the top-view patterns of the first spacedtrenches 140, the second spacedtrenches 150, and themesas trenches mesas trenches SiC drift layer 130 by using the RIE process with the SF6/O2 gas. - In the trench etching, proper conditions of the RIE process can be tuned and suitable opening patterns of the first spaced
trenches 140 in thecell region 131 and the second spacedtrenches 150 in thetermination region 132 can be set, so that the second spacedtrenches 150 can have an opening area larger than the first spacedtrenches 140. Thus, the etching rate for the second spacedtrenches 150 is less than that for the first spacedtrenches 140 due to the etching gas may be locally consumed too much at the second spacedtrenches 150 and hence their etching rate is decreased temporarily. In another example, the aspect ratio of opening patterns of the first spacedtrenches 140 can be less than that of the second spacedtrenches 150, so that the trench depth of the second spacedtrenches 150 in thetermination region 132 can be less than that of the first spacedtrenches 140 in thecell region 131 after the RIE process, according to the microloading effect and the ARDE effect in the RIE. After the trench etching, the first SiO2 layer can be removed, for example, by the HF etching. Then, a second SiO2 film (not shown) with a thickness of 50 nm can be grown on theSiC drift layer 130 by the wet oxidation process, and a second SiO2 film (not shown) with a thickness of 200 nm can be grown on the first SiO2 film by the PECVD process. Hereafter, the combination of the first and second SiO2 films is referred to as the second SiO2 layer. Next, a photoresist layer (not shown) with a thickness of about 1000 nm can be spin-coated on the second SiO2 layer, and then the second SiO2 layer on themesas trenches layer 160. - To fabricate the
second contact metal 180, for example, a Ti film with a thickness of 50 nm can be deposited on theSiC drift layer 130 and concurrently fill the spacedtrenches second contact metal 180 can take the place of the conductingmaterial 170 and cover the insulatinglayer 160 layer in the first embodiment. Then, the Ti film is treated by annealing at 500° C. for 10 minutes, so that Schottky contacts can be formed on themesas second contact metal 180 and theSiC drift layer 130. Thus, the MOS structure can be formed in thetrenches Schottky device 400 can be formed, both due to the formation of the Ti film. - After that, an Al—Si or Al—Cu alloy layer with a thickness of 4 μm can be deposited on the Ti film, extending from the
cell region 131 to thetermination region 132, to be used as an anode of theSchottky device 400. Wherein, the combination of the Ti film and the alloy film is referred to as thesecond contact metal 180. After the above fabrication process, theSchottky devices 400 formed on the SiC wafer (the SiC substrate) can be separated into individual Schottky device dice, by the die sawing or laser cutting along scribe lines in thetermination region 132. Each Schottky device die can be further packaged to be a discrete SiC-based trench-type Schottky device of this embodiment. - In the present disclosure, one of the main features can be that trenches of different depths are respectively formed in the cell and termination regions of the SiC-based Schottky device, and it can be applicable to the Schottky device with the structure of dual-metal trench-type barrier devices as described below.
FIG. 6 schematically shows a vertical cross-section diagram of a SiC-based trench-type Schottky device according to a fifth embodiment of the present disclosure, which is similar to the structure of the first embodiment, except for adapting the dual-metal trench barriers. As shown inFIG. 6 , theSchottky device 200 includes aSiC substrate 210, afirst contact metal 220, aSiC drift layer 230, a plurality of first spacedtrenches 240, a plurality of second spacedtrenches 250, a plurality ofmesas second contact metal 260, and athird contact metal 270. Each component of theSchottky device 200 will be described below in detail. - The
SiC substrate 210 is used as a supporting body for theSchottky device 200 and the fabrication thereof in the manufacturing process. In the embodiment, theSiC substrate 210 can be a N+-type 4H-SiC semiconductor substrate; for example, an N+-type 4H-SiC wafer of 4 inches in diameter and 350 μm in thickness with a dopant concentration of 1×1019 cm−3. Here, 4H is one of polytype forms of SiC. But it is not limited thereto; theSiC substrate 210 can be of another polytype of silicon carbide, such as 3C-SiC, 6H-SiC, or 15R-SiC. - The
SiC substrate 210 has an upper surface and an opposing lower surface. Thefirst contact metal 220 can be disposed on the lower surface of theSiC substrate 210 to form an ohmic contact of low resistance between thefirst contact metal 220 and theSiC substrate 210. Thus, thefirst contact metal 220 can be used as a cathode of theSchottky device 200. Thefirst contact metal 220 can formed of Ni. For example, a Ni film with a thickness of 200 nm can be deposited by the PVD and treated by annealing at 950° C. for 30 minutes, so that an ohmic contact can be formed on the lower surface of the N+-type 4H-SiC substrate 210. But it is not limited thereto; thefirst contact metal 220 can be formed of another metal material and/or of another thickness. It is noticed that theSchottky device 200 is to be fabricated on the upper surface of theSiC substrate 210. - The
SiC drift layer 230 can be formed on the upper surface of theSiC substrate 210, so as to provide a main body for trench fabrication and device operation of the trench-type Schottky device according to the embodiment. Here, theSiC drift layer 230 can be an N−-type 4H-SiC epitaxial layer. For example, theSiC drift layer 230 can be formed of an N−-type 4H-SiC epitaxial layer of 6 μm in thickness with a dopant concentration of 6×1015 cm−3. But it is not limited thereto; theSiC drift layer 230 can be of another polytype of silicon carbide, such as 3C-SiC, 6H-SiC, or 15R-SiC, of another thickness and dopant concentration. Moreover, abuffer layer 290 of N-type 4H-SiC can be disposed between theSiC drift layer 230 and theSiC substrate 210, so as to reduce the defects produced during the epitaxial growth of theSiC drift layer 230, such as MPD and EPD. -
FIG. 2 can also provide top-view layout of the SiC-based trench-type Schottky device 200 in the present embodiment. Referring to bothFIGS. 6 and 2 , the top surface of theSiC drift layer 230 can be arranged into acell region 231 and atermination region 232, wherein thetermination region 232 is disposed around the edge area of theSchottky device 200, and thecell region 231 is disposed at the center area of theSchottky device 200 and enclosed by thetermination region 232. To fabricate thesecond contact metal 260, for example, a Ti film with a thickness of 50 nm and a 3 μm oxide layer can be deposited on theSiC drift layer 230 in sequence, and then the top-view patterns of the first spacedtrenches 240, the second spacedtrenches 250, and themesas trenches mesas trenches SiC drift layer 230 by using the RIE process with the SF6/O2 gas. - In the trench etching, proper etching of the RIE process can be tuned and suitable opening patterns of the first and second spaced
trenches trenches 250 in total to the area of thetermination region 232 is larger than the ratio of the opening area of the first spacedtrenches 240 in total to the area of thecell region 231, after the spacedtrenches trench 250 can be larger than that of each first spacedtrench 240, so that the etching rate for the second spacedtrenches 250 is less than that for the first spacedtrenches 140 due to the etching gas may be locally consumed too much at the second spacedtrenches 250 and hence their etching rate is decreased temporarily. In another example, the aspect ratio of opening patterns of the first spacedtrenches 240 can be less than that of the second spacedtrenches 250, so that the trench depth of the second spacedtrenches 250 in thetermination region 232 can be less than that of the first spacedtrenches 240 in thecell region 231 after the RIE process, according to the microloading effect and the ARDE effect in the RIE. - After the trench etching, the 50 nm Ti film serves as the
second contact metal 260. Then, a Ni film with a thickness of 50 nm can be deposited conformally intrenches third contact metal 270; i.e., thethird contact metal 270 is covering thesecond contact metal 260 on themesas bottoms trenches prepared device 200 at 500 for 10 minutes, a first Schottky contact can be formed on themesas SiC drift layer 230, and a second Schottky contact can be formed on the sidewalls andbottoms trenches SiC drift layer 230. Because nickel has a work function larger than titanium, the second Scottky contact has a higher barrier than the first Schottky contact. Thereby, when theSchottky device 200 is forward-biased, the first Schottky contact can be turned on first, providing a lower forward voltage drop and power loss. On the other hand, when theSchottky device 200 is in the reverse-biased mode, the depletion region of the high barrier second Schottky contact can extend to shield electric field on the low barrier first Schottky contact and thus reduces the leakage current. - Then, an Al—Si or Al—Cu alloy layer (not shown) with a thickness of 4 μm can be deposited on the
third contact metal 270, extending from thecell region 231 to thetermination region 232, to be used as an anode of theSchottky device 200. After the above fabrication process, the Schottky devices formed on the N+-type 4H-SiC wafer (the SiC substrate) can be separated into individual Schottky device dice, by the die sawing or laser cutting along scribe lines in thetermination region 132. Each Schottky device die can be further packaged to be a discrete SiC-based trench-type Schottky device of the present embodiment. -
FIG. 7 schematically shows a vertical cross-section diagram of a SiC-based trench-type Schottky device 202 according to a sixth embodiment of the present disclosure. A top-view layout of theSchottky device 202 in the embodiment can also be referred toFIG. 2 , also. Referring to bothFIGS. 2 and 7 , the first spacedtrenches 240 can have uniform depths in thecell region 231, while the second spacedtrenches 250 can have stepped depths in thetermination region 232, wherein the second spacedtrenches 250 can have decreasing depths as further away from thecell region 231, and the maximum depth of the second spacedtrenches 250 can be less than the depth of the first spacedtrenches 240. Fabrication process of theSchottky device 202 in this embodiment is similar to that of theSchottky device 200 in the fifth embodiment, except that the first spacedtrenches 240 in thecell region 231 can have opening patterns of uniform size while the second spacedtrenches 250 in thetermination region 232 can have opening patterns of increasing size. Consequently, the ratio of the opening area of the second spacedtrenches 250 in total to the area of thetermination region 232 is larger than the ratio of the opening area of the first spacedtrenches 240 in total to the area of thecell region 231. Also, each of the second spacedtrenches 250 can have a larger opening area than the first spacedtrenches 240, and the second spacedtrench 250 close to thecell region 231 can have a larger opening area than the one away from thecell region 232. Thereby, the first spacedtrenches 240 and the second spacedtrenches 250 can be fabricated concurrently in theSiC drift layer 130, with the second spacedtrenches 250 having decreasing depths as further away from the center of theSchottky device 202. The device reliability can be improved due to gradual decrease of electric field in thetermination region 232 when theSchottky device 202 is reversely biased. -
FIG. 8 schematically shows a vertical cross-section diagram of a SiC-based trench-type Schottky device 203 according to a seventh embodiment of the present disclosure. A top-view layout of theSchottky device 203 in the embodiment can also be referred toFIG. 4B , also. Referring toFIGS. 4B and 8 , the top surface of theSiC drift layer 230 can include atransition region 233 interposed between thecell region 231 and thetermination region 232. A plurality of third spacedtrenches 245 can be formed in thetransition region 233, which functions as a buffer region between thecell region 231 and thetermination region 232. The first spacedtrenches 240 can have uniform first depths, the second spacedtrenches 250 can have uniform second depths, and the third spacedtrenches 245 can have uniform third depths, with the third depth less than the first depth and more than the second depth. Fabrication process and the other composition parts of theSchottky device 203 in this embodiment are similar to that of theSchottky device 200 in the fifth embodiment. - In the embodiment, the first spaced
trenches 240 in thecell region 231 can have a first opening pattern of uniform size, the second spacedtrenches 250 in thetermination region 232 can have a second opening pattern of uniform size, and the third spacedtrenches 245 in thetransition region 233 can have a third opening pattern of uniform size, so that the ratio of the opening area of the third spacedtrenches 245 in total to the area of thetransition region 233 is larger than the ratio of the opening area of the first spacedtrenches 240 in total to the area of thecell region 231 while less than the ratio of the opening area of the second spacedtrenches 250 in total to the area of thetermination region 232. For example, each of the third spacedtrenches 245 can have an opening area larger than each of the first spacedtrenches 240 while less than each of the second spacedtrenches 250. Thereby, according to the fabrication process similar to the first embodiment, the first spacedtrenches 240, the third spacedtrenches 245, and the second spacedtrenches 250 can be fabricated concurrently in theSiC drift layer 230 with thetrenches Schottky device 203. The device reliability can be improved due to gradual decrease of electric field in theSchottky device 203 when it is in the reverse-biased mode. - With respect to the above description then, it is to be realized that the optimum dimensional relationships for the parts of the disclosure, to include variations in size, materials, shape, form, function and manner of operation, assembly and use, are deemed readily apparent and obvious to one skilled in the art, and all equivalent relationships to those illustrated in the drawings and described in the specification are intended to be encompassed by the present disclosure.
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TW101148717A TWI469341B (en) | 2012-12-20 | 2012-12-20 | Silicon carbide trench schottky barrier devices |
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TW101148717A | 2012-12-20 |
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Family Cites Families (17)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5506421A (en) * | 1992-11-24 | 1996-04-09 | Cree Research, Inc. | Power MOSFET in silicon carbide |
US5365102A (en) * | 1993-07-06 | 1994-11-15 | North Carolina State University | Schottky barrier rectifier with MOS trench |
US5323040A (en) * | 1993-09-27 | 1994-06-21 | North Carolina State University At Raleigh | Silicon carbide field effect device |
US5612232A (en) * | 1996-03-29 | 1997-03-18 | Motorola | Method of fabricating semiconductor devices and the devices |
JP3628613B2 (en) * | 1997-11-03 | 2005-03-16 | インフィネオン テクノロジース アクチエンゲゼルシャフト | High pressure resistant edge structure for semiconductor components |
US6362495B1 (en) | 1998-03-05 | 2002-03-26 | Purdue Research Foundation | Dual-metal-trench silicon carbide Schottky pinch rectifier |
JP3691736B2 (en) * | 2000-07-31 | 2005-09-07 | 新電元工業株式会社 | Semiconductor device |
US6562706B1 (en) | 2001-12-03 | 2003-05-13 | Industrial Technology Research Institute | Structure and manufacturing method of SiC dual metal trench Schottky diode |
US6855970B2 (en) | 2002-03-25 | 2005-02-15 | Kabushiki Kaisha Toshiba | High-breakdown-voltage semiconductor device |
US7323402B2 (en) | 2002-07-11 | 2008-01-29 | International Rectifier Corporation | Trench Schottky barrier diode with differential oxide thickness |
US7638841B2 (en) * | 2003-05-20 | 2009-12-29 | Fairchild Semiconductor Corporation | Power semiconductor devices and methods of manufacture |
US7754550B2 (en) | 2003-07-10 | 2010-07-13 | International Rectifier Corporation | Process for forming thick oxides on Si or SiC for semiconductor devices |
US7973381B2 (en) | 2003-09-08 | 2011-07-05 | International Rectifier Corporation | Thick field oxide termination for trench schottky device |
JP2006073740A (en) * | 2004-09-01 | 2006-03-16 | Toshiba Corp | Semiconductor device and its manufacturing method |
JP5133548B2 (en) | 2006-09-29 | 2013-01-30 | 富士フイルム株式会社 | Laser annealing method and laser annealing apparatus using the same |
TWI469221B (en) * | 2009-06-26 | 2015-01-11 | Pfc Device Co | Trench schottky diode and manufacturing mehtod thereof |
JP2011114028A (en) * | 2009-11-24 | 2011-06-09 | Toyota Motor Corp | SiC SEMICONDUCTOR DEVICE, AND METHOD OF MANUFACTURING THE SAME |
-
2012
- 2012-12-20 TW TW101148717A patent/TWI469341B/en active
- 2012-12-26 US US13/727,432 patent/US8766279B1/en active Active
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