Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
  • H10D64/00—Electrodes of devices having potential barriers
  • H10D64/111—Field plates
  • H10D64/115—Resistive field plates, e.g. semi-insulating field plates
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
  • H10D8/00—Diodes
  • H10D8/01—Manufacture or treatment
  • H10D8/043—Manufacture or treatment of planar diodes
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
  • H10D8/00—Diodes
  • H10D8/411—PN diodes having planar bodies

Definitions

• the present invention relates to a high-voltage diode according to the.
• high-voltage diodes which are intended for higher voltages, in particular above approximately 400 V, have been provided with edge terminations from field plates, field rings, dielectric insulating layers, semi-insulating covers and varying doping in the edge region when using planar structures. These measures are used individually or in combination, although for example also
• EP-B1-0 341 453 discloses a MOS semiconductor component for high reverse voltage, in which field plates are arranged on insulating layers of different thicknesses. Some of these field plates serve as channel or channel stoppers. Such field plates used as channel stoppers in diodes are often connected to the backside potential of the diode by a p-conducting region in the edge region, although a connection via an n-conducting region would in itself be more advantageous because this could reliably prevent a p-conducting channel , However, an additional mask step would be required for such a connection via an n-conducting region in an otherwise customary production process.
• So-called chipping stoppers are intended to prevent crystal defects from spreading from the saw edge into the active area of the respective chips when sawing a disk into individual chips. These chipping stoppers are usually realized by a field oxide between the functional edge area of the chip and the saw frame.
• Yoshida effect when using insulator layers for passivation a drift in the reverse voltage is occasionally observed as a result of an injection of hot electrons during the forward load when switching to the blocking state of the pn junction.
• the semi-insulating layers that are currently used for the passivation of pn junctions consist, for example, of amorphous silicon (a-Si) or of hydrogen-doped amorphous carbon (aC: H), as described in EP-Bl-0 400 178 and EP-Bl-0 381 111.
• a-Si amorphous silicon
• aC hydrogen-doped amorphous carbon
• semi-insulating passivation layers can actively build up image charges and thus shield external charges that penetrate from the outside, as well as dissipating them into specified charge carriers due to their finite specific conductivity. Overall, a semi-insulating passivation leads to a significantly improved long-term stability compared to a dielectric passivation.
• This object is achieved in a high-voltage diode according to the preamble of claim 1 according to the invention by the features contained in the characterizing part.
• the measures (a) and (b) specified in the characterizing part of claim 1 each serve individually to enable a high-voltage diode that can be produced with little effort for masks and adjustment and via a channel stopper, chipping stopper etc. has. Measures (a) and (b) can advantageously be used together. Of course, it is also possible to create a high-voltage diode that only implements one of these measures.
• the high-voltage diode according to the invention can be a fast switching diode or else a rectifier and universal diode in different voltage and current classes.
• the high-voltage diode can have one or more field rings depending on the desired voltage class in its edge area.
• the semiconductor body preferably consists of n-type silicon, into which a p-type trough-shaped zone is introduced.
• a p-type silicon body with an n-type trough-shaped zone can also be provided.
• the semiconductor material is not limited to silicon. Instead of silicon, it is also possible, for example, to use SiC or an A I ⁇ I B v semiconductor material.
• FIGS. 1 to 5 show different steps for producing the high-voltage diode according to the invention.
• n-type silicon substrate 1 shows an n-type silicon substrate 1, to which an approximately 0.5 ⁇ m thick silicon dioxide layer 2 is applied to the front, for example in a furnace process with moist oxidation.
• silicon dioxide another material, for example silicon nitride, can optionally be selected for this layer 2.
• Structures for the anode of the diode and possibly in the edge region for field rings are then introduced into the silicon dioxide layer 2 by means of photolithography.
• a photoresist layer is applied to the silicon dioxide layer 2, exposed and developed.
• An etchant for example during wet chemical etching, is brought into action on the silicon dioxide layer 2 exposed in this way in order to remove the silicon dioxide layer in the areas mentioned.
• This silicon removal can be carried out via the still existing photoresist or via the silicon dioxide layer 2 remaining after removal of the photoresist.
• the arrangement shown in FIG. 2 is thus obtained, which on the silicon substrate 1 contains the remaining parts of the silicon dioxide layer 2 and in windows 3 to 5 for an anode (window 3)
• Field ring (window 4) and adjustment structures shows that are defined in a scratch frame on the edge of the respective semiconductor chip (right edge in Fig. 2) (window 5).
• Window 4 can also be provided several field rings. If necessary, the field rings can also be dispensed with. The adjustment is made on the remaining edges or steps 6 of the window 5 that form adjustment structures.
• the silicon dioxide layer can be further etched back wet-chemically via the lacquer mask still present, in order to provide a certain distance 7 between the p-dopings to be introduced later in the windows 3 to 5 and the edges 6 of the adjustment structures or to generate the stage formed by this in the silicon substrate 1.
• the remaining photoresist is removed at the latest after this possible etching back.
• the arrangement shown in FIG. 2 (without additional etching back of the silicon substrate) or in FIG. 3 (with additional etching back of the silicon substrate) is thus present.
• silicon is removed in windows 3 to 5. At least this removal takes place in the window 3 in order to produce an edge or step as an adjustment structure in the area of a trough 8 outside an anode contact 13 (cf. below).
• the arrangement shown in FIG. 2 can thus be generated in such a way that the silicon removal in windows 3 to 5 takes place via the remaining silicon dioxide layer 2 (oxide mask) or via the photoresist still present on this silicon dioxide layer 2.
• Fig. 3 is processed. However, it is also possible to process the arrangement from FIG. 2 in a corresponding manner. In this case, however, there is no distance 7 between the edge of the remaining silicon dioxide layer 2 and the edges 6 of the juicing structures. Rather, these edges 6 of the adjustment structures then directly adjoin the edge of the windows 3 to 5. This is followed by p-doping, for example with boron, in order to produce a p-type trough-shaped zone 8, a p-type field ring 9 and, in the region of the chipping stopper, a p-type ring 10, as shown in FIG. 4 are.
• p-doping for example with boron
• the trough-shaped zone 8 as well as the field ring 9 and the ring 10 can be produced, for example, in one stage by means of ion implantation or else in multiple stages. It is thus possible, particularly for fast-switching diodes for zone 8, to provide them with a p + -conducting anode emitter of low penetration depth, the dopant dose of which is between 1.3 x 10 12 dopant atoms cm “ 2 and 5 x 10 13 dopant atoms cm "2 , and to dope the rest of zone 8 with a dose of about (1.3 ... 3) x 10 12 dopant atoms cm " 2 (see also DE-Al-100 31 461) ,
• the edges 6 are used as adjustment structures, if necessary. It is even possible to carry out the p-type doping for the zone 8, the field ring 9 and the ring 10, that is to say the introduction of the front side p-contact or the p-type emitter with ion implantation at a later point in time.
• Process variant 1 is particularly suitable for base material consisting of silicon substrate wafers obtained by zone drawing (FZ), while process variants 2 and 3 are also suitable for Czochralski (CZ) substrate wafers or for those with epitaxial layers ”) Wafers are beneficial.
• FZ zone drawing
• CZ Czochralski
• the edge passivation layer 12 (and thus the chipping stopper 12a) can optionally also consist of amorphous silicon (a-Si).
• the process step "radiation, if necessary, for setting the charge carrier life” is carried out several times, since depending on the dose used, ion buds and the type of radiation require different temperature budgets to heal radiation damage.
• the edge passivation layer 12 which consists in particular of hydrogen-doped amorphous carbon, partially acts as a chipping stopper 12a and prevents crystal defects from spreading out of a scribe frame into an active area when a silicon wafer is separated or sawn into chips.
• the passivation layer 12 is opened analogously to the contact holes for the anode contact 13 and the channel stopper 14, but there is no covering with metal here.
• the channel stopper 14 acts as a field plate and prevents the further spreading of a space charge zone outwards into the scoring frame. This makes it possible to reduce the necessary edge width, especially in the case of a high-resistance base material for the silicon substrate 1.
• the channel stopper 14 can also be connected to a p-type region, as indicated by a dashed line 17 in FIG. 5.
• This p-conducting region should then have the same electrical potential as the back of the silicon substrate, that is to say it should be connected to the cathode contact 15.
• channel stopper 14 is connected directly to an n-conducting region, as shown in FIG. 5.
• field rings 9 can optionally be provided between the active area, that is to say the trough-shaped zone 8, and a sawing edge 18, and these may also be provided with all or part of metal structures.
• the field ring 9 can also have such a metal structure.
• the high-voltage diode according to the invention can be thanks to the adjustment structures 6, which are located outside the anode contact 13, and the execution of the chipping stopper 12a in the edge region by the passivation layer 12 using only a total of three masking steps for the generation of the structured silicon dioxide layer 2, the Produce the passivation layer 12 and the front-side metallization from the anode contact 13 and the channel stopper 14.
• the adjustment structure 6 can advantageously be used, which allows precise positioning of the anode contact 13 and the channel stopper 14, for example.

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• 2000
  • 2000-09-22 DE DE10047152A patent/DE10047152B4/de not_active Expired - Fee Related
• 2001
  • 2001-08-24 JP JP2002529847A patent/JP2004510333A/ja active Pending
  • 2001-08-24 WO PCT/DE2001/003240 patent/WO2002025740A1/de not_active Ceased
  • 2001-08-24 EP EP01964927A patent/EP1307923B1/de not_active Expired - Lifetime
  • 2001-08-24 DE DE50107925T patent/DE50107925D1/de not_active Expired - Lifetime
• 2003
  • 2003-03-24 US US10/395,425 patent/US6770917B2/en not_active Expired - Lifetime

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