Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
  • H10D8/00—Diodes
  • H10D8/60—Schottky-barrier diodes 
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
  • H10D12/00—Bipolar devices controlled by the field effect, e.g. insulated-gate bipolar transistors [IGBT]
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
  • H10D62/00—Semiconductor bodies, or regions thereof, of devices having potential barriers
  • H10D62/10—Shapes, relative sizes or dispositions of the regions of the semiconductor bodies; Shapes of the semiconductor bodies
  • H10D62/102—Constructional design considerations for preventing surface leakage or controlling electric field concentration
  • H10D62/103—Constructional design considerations for preventing surface leakage or controlling electric field concentration for increasing or controlling the breakdown voltage of reverse-biased devices
  • H10D62/105—Constructional design considerations for preventing surface leakage or controlling electric field concentration for increasing or controlling the breakdown voltage of reverse-biased devices by having particular doping profiles, shapes or arrangements of PN junctions; by having supplementary regions, e.g. junction termination extension [JTE] 
  • H10D62/106—Constructional design considerations for preventing surface leakage or controlling electric field concentration for increasing or controlling the breakdown voltage of reverse-biased devices by having particular doping profiles, shapes or arrangements of PN junctions; by having supplementary regions, e.g. junction termination extension [JTE]  having supplementary regions doped oppositely to or in rectifying contact with regions of the semiconductor bodies, e.g. guard rings with PN or Schottky junctions
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
  • H10D8/00—Diodes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
  • H01L2924/0001—Technical content checked by a classifier
  • H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
  • H10D8/00—Diodes
  • H10D8/50—PIN diodes 

Definitions

• MOSFET metal oxide semiconductor field effect transistor
• Qrr body diode reverse recovery charge
• trr reducing reverse recovery time
• a rectifier device comprises a substrate of a first polarity, a lightly doped layer of the first polarity coupled to the substrate and a metallization layer disposed with the lightly doped layer.
• the ultrafast recovery diode includes a plurality of wells, separated from one another, formed in the lightly doped layer, comprising doping of a second polarity.
• the plurality of wells connects to the metallization layer.
• the ultrafast recovery diode further includes a plurality of regions, located between wells of said plurality of wells, more highly doped of the first polarity than the lightly doped layer.
• a semiconductor device comprises a rectifier, wherein the rectifier comprises a plurality of P- type wells coupled to a contactable metal layer.
• the plurality of P-type wells injects holes into a channel region between the plurality of P-type wells in a forward -bias condition of the rectifier.
• the plurality of P-type wells pinch off the channel region in a reverse-bias condition of the rectifier.
• the semiconductor device further includes a plurality of N-type wells located between the plurality of P-type wells. The plurality of N-type wells suppresses minority carrier injection from the plurality of P-type wells.
• Figure 1 illustrates a side sectional view of an ultrafast recovery diode, in accordance with embodiments of the present invention.
• Figure 2 illustrates a side, sectional view of an ultrafast recovery diode, in accordance with alternate embodiments of the present invention.
• Figure 3 illustrates exemplary current versus time recovery characteristics, in accordance with embodiments of the present invention.
• the trenches 110 of diode 100 have exemplary depth dimensions of about 0.3 to 0.7 microns.
• the trenches 110 of diode 100 have exemplary width dimensions of about 0.3 to 0.6 microns.
• the trenches 110 have an exemplary pitch of about 0.6 to 1.3 microns. It is appreciated that embodiments in accordance with the present invention are well suited to other dimensions.
• regions between p wells 150 comprise n-type doping, referred to as "n channel enhancement" 160.
• N channel enhancement 160 comprises exemplary doping of about 1.0 x 10 15 to 2.0 x 10 16 atoms per cubic centimeter. It is to be appreciated that such a doping level is generally above a doping level of N- epitaxial layer 180.
• Shottky barrier 170 is formed between the anode metal 140 and the N- epitaxial layer 180. Shottky barrier 170 may be formed, for example, by inherent characteristics of Aluminum disposed adjacent to an N- epitaxial layer, e.g., anode metal 140 comprising Aluminum disposed adjacent to N- epitaxial layer 180. Embodiments in accordance with the present invention are well suited to other formations of Shottky barrier
• FIG. 1 illustrates a side sectional view of an ultrafast recovery diode 200, in accordance with embodiments of the present invention.
• Diode 200 is formed in an N- epitaxial layer 280.
• N channel enhancement 260 comprises exemplary doping of about 1.0 x 10 15 to 2.0 x 10 16 atoms per cubic centimeter. It is to be appreciated that such a doping level is generally above a doping level of N- epitaxial layer 280.
• Shottky barrier 270 is formed between the anode metal 240 and the N- epitaxial layer 280. Shottky barrier 270 may be formed, for example, by inherent characteristics of Aluminum disposed adjacent to an N- epitaxial layer, e.g., anode metal 240 comprising Aluminum disposed adjacent to N- epitaxial layer 280. Embodiments in accordance with the present invention are well suited to other formations of Shottky barrier 270.
• the p-wells 250 pinch off, e.g., a depletion region forms between the P-wells 250, ensuring a desirable breakdown voltage and low leakage for diode 200.
• the n channel characteristics of diode 200 result in improved reverse recovery.
• One mechanism for such improved reverse recovery is believed to be a suppression of minority carrier injection from the p wells 250.
• Diodes 100 and 200 may be understood as comprising a Schottky diode in series with a junction field effect transistor (JFET) channel and the base region of a P intrinsic N (PiN) diode.
• JFET junction field effect transistor
• the PiN diode is conductively modulated by the injection of minority carriers from the gate of the JFET.
• Diodes 100 and 200 should be constructed utilizing relatively fine process geometries as it is desirable to increase the ratio of Schottky barrier area to PiN area to greater than one.
• Diodes 100 ( Figure 1) and 200 ( Figure 2) are now described functionally.
• JFET channel forms between the plurality of P-wells.
• the P wells inject holes into the JFET channel. These additional holes reduce the resistance of the JFET channel, enhancing the forward conduction in the Schottky region of the rectifier.
• a Schottky diode between metal and N- epitaxy is characterized as having a lower forward drop of about 0.3 volts in comparison with PN diode.
• the P-wells starts to inject holes.
• the N channel enhancement regions reduce resistance in the JFET channel thereby delaying onset of a forward bias condition of the p wells. In such a case, a majority of current flows through the JFET channel. Fewer minority carriers results in a decreased density of minority carriers producing beneficial improvements in reverse recovery device performance.
• a depletion region forms around the P-wells.
• embodiments in accordance with the present invention are, in large part, controlled by device geometry rather than doping processes. In general, doping processes produce a varying distribution of dopant density, whereas geometric processes are generally more precise. [0023] It is to be appreciated that embodiments in accordance with the present invention are well suited to performance adjustment via a variety of well known techniques, including, for example, minority carrier lifetime reduction, e.g., including electron irradiation, Argon, Helium or Hydrogen implantation, or the diffusion of a heavy metal, for example Platinum or Gold, singly or in a variety of combinations.
• minority carrier lifetime reduction e.g., including electron irradiation, Argon, Helium or Hydrogen implantation
• a heavy metal for example Platinum or Gold
• Figure 3 illustrates exemplary current versus time recovery characteristics 300, in accordance with embodiments of the present invention.
• Recovery characteristic 310 represents reverse recovery characteristics of an exemplary 600 volt ultrafast diode as known in the conventional art. It is appreciated that the recovery characteristic comprises about three amperes of maximum reverse current and a duration of about 3 x 10 " seconds.
• Recovery characteristic 320 represents reverse recovery characteristics of an exemplary 600 volt diode, in accordance with embodiments of the present invention. It is to be appreciated that the recovery characteristic of this diode comprises significantly less current than the conventional diode of characteristic 310.
• Recovery characteristic 320 shows a maximum reverse current of about 1.3 amps.
• Recovery characteristic 330 represents reverse recovery characteristics of a second exemplary 600 volt diode, in accordance with embodiments of the present invention. It is to be appreciated that the recovery characteristic of this diode comprises significantly less current than the conventional diode of characteristic 310. Recovery characteristic 320 shows a maximum reverse current of about 0.8 amps. Beneficially, the recovery duration is somewhat longer in duration than that of characteristic 310, e.g., about 4.5 x 10 '8 seconds. [0027] It is to be appreciated that embodiments of the present invention are well suited to construction utilizing materials of opposite polarity to those depicted herein.
• Embodiments in accordance with the present invention provide an ultrafast recovery diode with reduced reverse recovery charge that maintains a soft recovery characteristic. Further embodiments in accordance with the present invention provide previously identified features in an ultrafast recovery diode that can be formed in either trench or planer versions. Still other embodiments in accordance with the present invention provide the previously identified features in a manner that is compatible and complimentary with convention semiconductor manufacturing processes and equipment. [0029] Embodiments in accordance with the present invention, ultrafast recovery diode, are thus described. While the present invention has been described in particular embodiments, it should be appreciated that the present invention should not be construed as limited by such embodiments, but rather construed according to the below claims.

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• Electrodes Of Semiconductors (AREA)
• Rectifiers (AREA)
• Junction Field-Effect Transistors (AREA)

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• 2005
  • 2005-12-27 US US11/320,313 patent/US7696598B2/en not_active Expired - Fee Related
• 2006
  • 2006-12-19 WO PCT/US2006/049118 patent/WO2007076056A2/en not_active Ceased
  • 2006-12-19 CN CN2012101351735A patent/CN102683428A/zh active Pending
  • 2006-12-19 CN CN2006800513966A patent/CN101366124B/zh not_active Expired - Fee Related
  • 2006-12-19 JP JP2008548658A patent/JP5059025B2/ja not_active Expired - Fee Related
  • 2006-12-27 TW TW095149314A patent/TWI381532B/zh not_active IP Right Cessation
• 2012
  • 2012-02-29 JP JP2012043607A patent/JP5704652B2/ja not_active Expired - Fee Related

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