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
  • H10D64/118—Electrodes comprising insulating layers having particular dielectric or electrostatic properties, e.g. having static charges
• • 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

Definitions

• the invention relates to a high-blocking semiconductor device according to the preamble of the main claim.
• planar semiconductor components are protected by a passivation layer made of the oxide of the semiconductor material arranged on them.
• a semiconductor component with such a passivation layer is known for example from GB-PS 10 76 371.
• Suitable passivation substances are, for example, silicone-containing plastics and polyimide lacquers.
• Figure 1 shows an axial section through a known rotationally symmetrical planar semiconductor diode
• Figure 2 shows an axial section through a first embodiment of a rotationally symmetrical planar semiconductor diode according to the invention, which contains a single toroidal auxiliary zone and an annular metal ring which is attached above this auxiliary zone;
• FIG 3 shows an axial section through a second exemplary embodiment of a rotationally symmetrical planar semiconductor diode according to the invention with three toroidal auxiliary zones and an annular metal ring attached above the middle of these zones, only half of the diode being shown from its central axis to the right.
• a semiconductor wafer 10 made of single-crystal silicon with n-conductivity serves as the semiconductor base material.
• a circular main zone 11 with p-conductivity is diffused into the semiconductor die 10 from its upper side (first main surface).
• the p-type main zone 11 forms the anode zone, the remaining n-type region of the semiconductor die forms the cathode zone of the semiconductor diode.
• two toroidal p-type auxiliary zones 1 and 2 which coaxially surround the main zone 11, have been diffused into the semiconductor base material.
• auxiliary zones 1 and 2 Since the two auxiliary zones 1 and 2 were produced in one operation with the main zone 11, the auxiliary zones 1 and 2 have the same diffusion depth, the same diffusion profile and the same surface concentration as the main zone 11.
• a passivation layer 12 consisting of silicon dioxide is formed, which completely covers the upper side of the semiconductor die with the exception of a contact window which is etched free on the main zone 11.
• An anode metallization 13 which is applied to the semiconductor surface after the etching of the contact window within this window and is used for the external connection of the anode zone 11 of the semiconductor diode, is located within the contact window.
• a continuous cathode metallization 14 is applied to the underside of the semiconductor wafer 10.
• a semiconductor diode is known for example from GB-PS 10 76 371.
• a second passivation layer 15 can also be applied to the first passivation layer 12, which is also shown in FIG. 1 and can consist of a silicone-containing plastic or of polyimide lacquer.
• the toroidal auxiliary zones 1, 2 in the hot reverse test have no stabilizing effect on the breakdown voltage: the charges coming from the passivation layer 15 to the interface of the two layers 12 and 15 and the hot electrons reaching the oxide-silicon interface can at the high temperatures to be applied, drift unhindered under the influence of the applied electric field and thus lead to degradation of the blocking characteristic.
• Figure 2 shows an axial section through a first embodiment, which is again to be considered rotationally symmetrical.
• a single toroidal auxiliary zone 1 is provided to increase the breakdown voltage.
• an electrically floating metal ring 16 is applied to the first passivation layer 12 exactly above the toroidal auxiliary zone 1 and coaxially surrounds the main zone 11 and its connecting metallization 13 .
• the electrically floating metal ring 16 has a smaller width than the p-type auxiliary zone 1, so that the metal ring 16 does not overlap the auxiliary zone 1, as seen in the direction perpendicular to the surface of the semiconductor wafer.
• the embodiment of Figure 2 can be modified in a particularly advantageous manner so that it is not designed as a planar diode, but as a planar transistor.
• the central main zone 11 of the semiconductor component is to be operated as the base zone of the transistor.
• Such an arrangement can be used in a particularly advantageous manner as an ignition transistor in a motor vehicle.
• FIG. 3 shows an axial section through a second, preferred exemplary embodiment of a rotationally symmetrical planar semiconductor diode in accordance with the invention, only one half of the diode being shown to the right from the axis of symmetry.
• three toroidal p-type auxiliary zones 1, 2, 3, which run concentrically to this axis, and an electrically floating metal ring 16, which is narrower than the associated second auxiliary zone 2, are provided on the passivation layer 12, especially above the second auxiliary zone 2.
• the high-resistance n-conductive base material of the semiconductor chip 10 has a doping between 5 x 10 13 / cm 3 and 5 x 10 15 / cm 3 .
• Reference number 17 denotes the expected space charge zone, delimited by a dashed line, which results when the diode has a breakdown voltage of 1500 volts and in the hot reverse test with a reverse voltage of 1000 volts, that is to say with two thirds of its breakdown voltage, is charged.
• the auxiliary zones 1, 2, 3 diffused into the semiconductor base material have no stabilizing effect on the breakdown voltage in the hot reverse test: the charges reaching the silicon dioxide layer 12, which mainly originate from the material of the second passivation layer 15, and which are passed on to the Hot electrons reaching the oxide-silicon interface can drift unhindered at temperatures of 150 ° C. and under the influence of the applied electric field and would thus - without the metal ring 16 - become Degradation of the blocking characteristic.
• the electrically floating metal ring 16, which lies above the central auxiliary zone 2 acts as a barrier against the drift of the charges which reach the silicon dioxide layer 12.
• This position of the floating metal ring 16 was chosen because the central auxiliary zone 2 is just within the space charge zone 17 in the hot reverse test with a blocking voltage of 1000 volts. Corresponding to the area ratio of the areas outside and inside the metal ring 16, more negative charges come from the inside than positive charges from the outside onto the metal ring 16. The metal ring 16 is thus charged negatively; at the end of the drift, it is at a lower potential than the second auxiliary zone 2 underneath. Because of the small distance of the metal ring 16 from the point where the space charge zone 17 ends at the top of the semiconductor die 10 and the small number of ion charges therein The reverse voltage therefore does not degrade in the area.
• the metal ring 16 were electrically connected to the second auxiliary tooth 2 underneath through a contact window introduced into the silicon dioxide layer 12, then nega tive charging of the metal ring 16, the second auxiliary zone 2 follow this potential reduction. In the course of the hot reverse test, the space charge zone 17 would thus extend to the third auxiliary zone 3 and also beyond to the n + zone 18. The resulting deterioration of the blocking characteristic when the metal ring 16 is connected has actually been observed in corresponding tests with a semiconductor arrangement modified in this way.
• the invention is not restricted to the exemplary embodiments of high-blocking planar diodes shown in the drawing.
• the ring structures do not have to be circular. Rectangular, diamond-shaped, oval or otherwise shaped ring structures can also be used, the symmetry of the arrangement also not being mandatory.
• the rings must be essentially closed.
• the measures according to the invention can advantageously also be provided with other high-blocking semiconductor components, for example with high-blocking planar transistors or with high-blocking semi-planar thyristors. In the latter.
• the cathode-side high-blocking pn junction is made planar and provided with the ring structure according to the invention described above.

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• Electrodes Of Semiconductors (AREA)
• Semiconductor Integrated Circuits (AREA)

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• 1987
  • 1987-06-25 DE DE19873721001 patent/DE3721001A1/de active Granted
• 1988
  • 1988-05-05 WO PCT/DE1988/000266 patent/WO1988010512A1/de unknown

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