WO2002025736A1 - Semiconducteur haute tension - Google Patents

Semiconducteur haute tension Download PDF

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Publication number
WO2002025736A1
WO2002025736A1 PCT/SE2001/001953 SE0101953W WO0225736A1 WO 2002025736 A1 WO2002025736 A1 WO 2002025736A1 SE 0101953 W SE0101953 W SE 0101953W WO 0225736 A1 WO0225736 A1 WO 0225736A1
Authority
WO
WIPO (PCT)
Prior art keywords
active part
contact
voltage
dielectric constant
grading
Prior art date
Application number
PCT/SE2001/001953
Other languages
English (en)
Inventor
Hans Bernhoff
Jan Isberg
Per Skytt
Peter Isberg
Mark Irwin
Carina ÖNNEBY
Mats Dahlund
Eva MÅTEMSSON
Original Assignee
Abb Ab
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Abb Ab filed Critical Abb Ab
Priority to AU2001288157A priority Critical patent/AU2001288157A1/en
Publication of WO2002025736A1 publication Critical patent/WO2002025736A1/fr

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Classifications

    • 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
    • H01L29/408—Electrodes ; Multistep manufacturing processes therefor with an insulating layer with a particular dielectric or electrostatic property, e.g. with static charges or for controlling trapped charges or moving ions, or with a plate acting on the insulator potential or the insulator charges, e.g. for controlling charges effect or potential distribution in the insulating layer, or with a semi-insulating layer contacting directly the semiconductor surface
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/28—Encapsulations, e.g. encapsulating layers, coatings, e.g. for protection
    • H01L23/29—Encapsulations, e.g. encapsulating layers, coatings, e.g. for protection characterised by the material, e.g. carbon
    • H01L23/293—Organic, e.g. plastic
    • H01L23/295—Organic, e.g. plastic containing a filler
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/28—Encapsulations, e.g. encapsulating layers, coatings, e.g. for protection
    • H01L23/31—Encapsulations, e.g. encapsulating layers, coatings, e.g. for protection characterised by the arrangement or shape
    • H01L23/3157—Partial encapsulation or coating
    • H01L23/3192—Multilayer coating
    • 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
    • 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
    • H01L2924/10—Details of semiconductor or other solid state devices to be connected
    • H01L2924/11—Device type
    • H01L2924/13—Discrete devices, e.g. 3 terminal devices
    • H01L2924/1304—Transistor
    • H01L2924/1305—Bipolar Junction Transistor [BJT]
    • H01L2924/13055—Insulated gate bipolar transistor [IGBT]

Definitions

  • the present invention relates to a semiconductor device com- prising means for grading an electric field created in the active part of the device when a high voltage is applied thereacross.
  • the "active part” includes the part of the device being of a semiconducting material but neither the contacts made thereto nor surrounding insulating material encapsulating the active part.
  • the active part may also be a heterostructure including semiconducting layers of different materials.
  • the invention is particularly, but not exclusively, directed to semiconductor devices for high power applications.
  • the field grading material also protects the device from surface flash-over.
  • EP 0 343 797 It is also known through EP 0 343 797 to apply a member of an electrically conductive material or a semiconducting material outside the active part of a semiconductor device at a lateral edge thereof for locally reducing the electric field through the lower resistivity in said member than in the active part of the device next thereto when a direct voltage is applied to the device.
  • the object of the present invention is to provide a semiconductor of the type defined in the introduction having means for electric field grading improved in at least some aspects with re- spect to the devices already known discussed above.
  • This object is according to the invention obtained by providing such a device in which said means comprises a first member being of a material having a higher dielectric constant than the material of said active part and applied next to at least a portion of said active part where a high electric field occurs when a high voltage is applied across the device for obtaining a field grading for a condition of changing of said voltage.
  • the present invention goes in the opposite direction of the aim of encapsulations of semiconductor components through purely insulating material. It has in certain applications been an attempt to obtain as low dielectric constants as possible for these insulating materials for obtaining a minimal delay of signals in a circuit to which the device belongs. Higher signal propagation speed and signal carrying capacity are also obtained by lowering the dielectric constant of said insulating material. However, this results in an increase of the electric field at the boundary between the active part and the insulation.
  • the invention goes in the other direction while providing the first semiconductor device having means for electric field grading for surge and alternating voltage operation.
  • the dielectric constant of the material of said first member is substan- tially higher than that of the material of said active part, and it may for instance be more than 1 .5, 2 or 3 times higher than the dielectric constant of the material of said active part of the device.
  • the dielectric constant of the material of the first member is non- linear and adapted to change with the electric field in the material.
  • Such an non-linear dielectric constant may in certain applications be favourable for obtaining a higher dielectric constant where the field is higher.
  • the device has contacts adapted to connect the device to an alter- , nating voltage during operation thereof, and said first member is surrounded by an insulating material.
  • Such a device will have an advantageous field grading thanks to said first member.
  • said device has contacts adapted to connect the device to a direct voltage for direct voltage operation of the device, and said means comprises a second member being of a material having a lower resistivity than the material of the active part and applied in contact with said active part of the device for obtaining a resistive field grading for direct voltage conditions.
  • first member being of a material having a higher dielectric constant than the material of the active part
  • second member being of a material having a lower resistivity than the material of the active part in one and the same device for a combination of a field grading for a condition of changing of said voltage and a resistive field grading for direct voltage conditions.
  • said second member is in contact with two contacts forming a terminal each of the device and establishes a connection therebetween around the active part of the device. This means that a small leakage current may flow from one contact to the other through said second member thus reducing the electric field close to the contacts.
  • the second member is in contact with said active part of the device, which means that it may reduce the electric field at the boundary between the active part and the second member by using lower resistivity of the material of the second member than of the material of the active part next thereto.
  • the device has two contacts arranged on opposite sides of the active part of the device extending laterally beyond the contact, said first member is arranged next to and surrounds the outer edge of the respective contact and the corner formed between the contact and the active part there, and the second member surrounds the first member.
  • said means comprises a plurality of first members arranged at inter- vals in the lateral direction away from said contact towards a lateral outer edge of said active part next to the active part with said second member reaching the active part between adjacent first members and embedding all the first members.
  • Electric field grading at constant voltage and changing voltage conditions over an extended portion of the active part of the device is obtained.
  • the different first members may be of different materials for adapting the field grading properties to the need at the respective location.
  • “Different material” also includes the same basic material filled with different particles.
  • said portion of potential high electric field is a corner between a lateral outer edge of the contact applied on the active part and the active part or an outer edge of the active part of the device.
  • the material of said first member is water. Pure water has a very high dielectric constant and is available at a very low cost. Fur- thermore, the device may be provided with means for circulating the water in contact with the active part of the device for cooling this active part giving the water a double function. However, other liquids than water are also conceivable.
  • the invention also includes preferable uses of a device according to the invention as defined in the appended use claims as well as a method for providing a semiconductor device with means for grading an electric field created in the active part of the device when a high voltage is applied thereacross or form an insulation around at least a part of the active part of the device according to the appended method claims.
  • Fig 1 is a schematic view showing the extension of the equipotential lines in a semiconductor device holding a high voltage and surrounded by a purely insulating material having a lower dielectric constant than the material of the active part of the device according to the prior art and achieved by simulations,
  • Fig 2 is a view corresponding to Fig 1 for a semiconductor device according to a preferred embodiment of the invention, in which the active part is surrounded by a material having a higher dielectric constant than the material of the active part of the device for field grading for a condition of changing voltage applied over the device,
  • Fig 3 is a cross-section view of a semiconductor device ac- cording to a first preferred embodiment of the invention
  • Fig 4 is a view of the device according to Fig 3 in a section along the line IV-IV in Fig 3,
  • Fig 5 is a very schematic view of a device according to a second preferred embodiment of the invention.
  • Fig 6 is a schematic view of a device according to a third preferred embodiment of the invention
  • Fig 7 illustrates very schematically a method for applying an insulating or field grading material onto a semiconductor wafer.
  • Fig 1 it is schematically illustrated in Fig 1 what is occurring at the edge 1 at the respective contact 2, 3 applied on the active part 4 of a semiconductor device when a high voltage in the form of an alternating voltage or the occurrence of a surge is held by the device.
  • the equipotential lines 6 would already at the same dielectric constant of the two materials have a very high density at the edge 1 , and this is due to the lower dielectric constant of the insulation 5 made even worse.
  • Fig 2 illustrates how the present invention solves this problem by introducing a first member 7 instead of the insulation 5 being of a material having a higher dielectric constant than the material of the active part 4.
  • ⁇ is 7 for the active part material
  • ⁇ is 12 for the material of the field grading member 7.
  • Fig 3 illustrates a very preferred embodiment of the invention, in which said first member 7 being of a material with a higher dielectric constant than the material of the active part 4 is arranged next to and surrounds the outer edge 1 of the respective contact 2,3 and the corner formed between the contact and the active part there. Furthermore, additional first members 7', 7", 7'" are arranged at intervals in the lateral direction away from the respective contact towards a lateral outer edge 8 of said active part 4 next to the active part for obtaining an alternating voltage and surge or impulse voltage field grading to utilize the full size of the substrate for field grading.
  • This device is intended for direct voltage operation and is therefor additionally provided with a second member 9 being of a material having a lower resistivity than the material of the active part and applied in contact with said active part of the device between adjacent first members 7-7'" and embedding all the first members for obtaining a resistive grading for direct voltage conditions. Furthermore, the second member 9 is in contact with the two contacts 2,3 while establishing a connection therebetween around the active part of the device. The second member 9 results in a field reduction during direct voltage operation thanks to a lower resistivity of the material thereof than of the material of the active part of the device.
  • the active part 4 of the device is preferably of a wide band gap material, i.e. a material having an energy gap between the valence band and the conduction band exceeding 1 .5 eV, such as SiC or diamond.
  • This means that the active part 4 may be made very thin and still be able to hold a high voltage in the blocking state thereof resulting in high electric fields. Thanks to the arrangement of the first members and the second member an efficient field grading for the steady state direct voltage case and also for surge voltages suddenly occurring may be obtained. It may be mentioned that ⁇ is 5.7 for diamond, and it has for the first member to exceed this value.
  • the different rings may be made of materials having different field grading properties, i.e. different dielectric constants and resistivities.
  • This material may for instance be any gel, composite, varnish, polymer or rubber based material, such as epoxy, silicone gel, silicone rubber or EPDM rubber.
  • Said material can be filled with particles increasing the dielectric constant thereof, such as particles of SiC, BaTi0 3 , Ti0 2 , Al 2 0 3) MgO, ZnO...
  • the rings 7- 7'" could also be thin films (such as BaTi0 3 or Ti0 2 ) with desired properties.
  • Fig 5 illustrates a semiconductor device according to another preferred embodiment of the invention, which differs from that according to Fig 3 by the fact that said first member 7 of a material having a higher dielectric constant than the active part 4 of the device is water, and the entire active part with contacts 2, 3 are fully immersed in a closed vessel 10 filled with water. It is shown how one 2 of the contacts is provided with apertures for obtaining control of the active part of the device through light.
  • Water has a very high dielectric constant, in the order of 80, and has in a pure state a high dielectric strength (200 kV/cm).
  • the water may be filled by nanoparticles (particles having a size of 1-100 nm) for increasing the dielectric constant and/or the dielectric strength. It may be chosen to add such particles with a tendency to absorb ions for taking care of the risk of ionisation of pure water.
  • the pure water could also serve as a resistive field grading due to its relative high conductivity.
  • the water can also be utilised to cool the active part 4 of the device, and means 1 1 is provided for circulating the water in contact with the active part of the device for this sake.
  • a deionizer 1 1 a is arranged to purify the water before recirculation.
  • Another advantage of using water or any other liquid as field grading material is that there will be no mechanical pressure on the active part of the device and no material stresses caused upon thermal expansion as a consequence of different coefficients of thermal expansion.
  • the use of water may also be combined with other field grading members, such as members for additional resistive field grading, e.g. applied on the active part.
  • a device is schematically illustrated in Fig 6.
  • This device has a first member in the form of an O-ring 12 of an elastic material adapted to be applied on the active part of the device while be- ing stretched for storing potential energy therein for obtaining a snug fit to said active part. More exactly, the O-ring is applied around each contact 2, 3 of the device forming a terminal thereof for bearing laterally thereagainst and on portions of the active part of the device next to the contact.
  • This O-ring will preferably be of a material having a higher dielectric constant than the material of the active part 4 and has substantially the same influence upon the electric field as the member 7 in the embodiment according to Fig 3.
  • the O-ring has in a resting (un- stretched) state thereof a cross-section being substantially com- plementary to the cross-section of the transition between said contact and the active part of the device next thereto, which in the present case means a substantially square cross-section, i.e. the shape of the O-ring fits to the shape of the contact and active part at said transition.
  • the contact may be shaped so that an O-ring having a circular cross-section will suit, but it will also be possible to fill out any gap between the O-ring and the regions of the contact and the active part at the transition thereof with any suitable material.
  • the O-ring may be provided with different layers of different materials or of the same material with different additives, so that it may for instance also have a part with a lower resistivity than the resistivity of the active part of the device for field grading at direct voltage operation of the device.
  • the O-ring may also be replaced by a seal with no elastic properties. This embodiment is particularly advantageous when a liquid metal is used as said contact 2 and/or 3, since the O-ring will then also ensure the position of the contact and determine the shape of the contact edge.
  • the devices may be any type of high voltage devices, which may be adapted to hold a voltage of more than 1 kV, perhaps more than 5 kV or even more than 10 kV in the blocking state thereof.
  • rectifying diodes thyristors, IGBTs and MISFETs.
  • Such a device may be used in for instance current valves of converters for converting direct voltage into alternating voltage or direct voltage and conversely, such as in HVDC stations (High Voltage Direct Current).
  • HVDC stations High Voltage Direct Current
  • Other preferable uses are in tap changers and in current limiters, preferably as switches.
  • Fig 7 illustrates a method in the form of a so called spin-on process for providing a semiconductor device with means for grading an electric field created in the active part of the device when a high voltage is applied thereacross or forming an insulation around at least a part of the active part of the device. It is shown how a piece 13, here of a wide band gap semiconductor material, adapted to form the active part of the device is held by a vacuum chuck 14 for not degrading the surface of the piece 13. It is shown by arrows 15 how a negative pressure is formed inside the chuck members 16, 17. However, it would be possible to supply material forming said means through one of these members 16, 17 and create a negative air pressure in only one of them.
  • the material to be applied on the active part 13 is in any case supplied substantially centrally to the active part, which is rotated, so that the material migrates regularly towards the lateral edges of the active part.
  • a constraining mould 20 is provided for preventing the material from moving further laterally than to this resulting in a shaping of the material 19. It is pointed out that the material supplied in this way has not necessarily to be field grading, but it may also be only insulating. It is possible to adjust the rotation speed and the supply rate of the material for influencing the shape of the field grading or insulating member formed in this way.
  • Corresponding materials have until now been applied by dipping the entire piece 13 into a bath of for instance silicon gel, but this may be delicate if the piece 13 is of a fragile material, since it is necessary to hold the piece in some way. However, this is not needed here, and it will also be possible to better distribute particles that may be added to the material 19 through the rotation than if it would be poured onto the piece 13 or a material applied thereon. It is also easier to obtain a determined shape of the material applied, since a layer being thin at the centre and thick at the edges may be obtained, which is not possible when pouring the material on the piece 13.
  • This method is especially suited for applying field grading and insulating materials to fragile substrates (active parts), since it minimizes stresses applied to the substrate during processing. This is particularly important for brittle diamond substrates.
  • the active part of the devices as well as the field grading members may of course have totally different shapes than those shown in the figures. It is noticed that the active part of the de- vices may and will almost always contain intentional dopants as well as inevitable impurities.

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • Ceramic Engineering (AREA)
  • Physical Or Chemical Processes And Apparatus (AREA)
  • Die Bonding (AREA)

Abstract

L'invention concerne un dispositif à semiconducteur comportant un organe (7) servant à répartir le champ électrique créé dans la partie active (4) du dispositif lorsqu'une tension élevée y est appliquée. Ledit organe comprend un élément (7) constitué d'un matériau dont la constante diélectrique est plus élevée que celle du matériau de ladite partie active, cet élément étant appliqué à côté d'au moins une partie de ladite partie active dans laquelle se crée un champ électrique élevé lorsqu'une tension élevée est appliquée au dispositif pour réaliser une répartition de champ dans le cas de changement de tension.
PCT/SE2001/001953 2000-09-21 2001-09-13 Semiconducteur haute tension WO2002025736A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2001288157A AU2001288157A1 (en) 2000-09-21 2001-09-13 A high voltage semiconductor

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE0003360A SE0003360D0 (sv) 2000-09-21 2000-09-21 A semiconductor device
SE0003360-5 2000-09-21

Publications (1)

Publication Number Publication Date
WO2002025736A1 true WO2002025736A1 (fr) 2002-03-28

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ID=20281094

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Application Number Title Priority Date Filing Date
PCT/SE2001/001953 WO2002025736A1 (fr) 2000-09-21 2001-09-13 Semiconducteur haute tension

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Country Link
AU (1) AU2001288157A1 (fr)
SE (1) SE0003360D0 (fr)
WO (1) WO2002025736A1 (fr)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0343797A1 (fr) * 1988-05-25 1989-11-29 Powerex, Inc. Thyristor à haute tension pourvu d'une extension à gradation de champ en vue d'augmenter la tension de blocage
US4890150A (en) * 1985-12-05 1989-12-26 North American Philips Corporation Dielectric passivation
EP0519741A2 (fr) * 1991-06-21 1992-12-23 Kabushiki Kaisha Toshiba Elément semi-conducteur à haute tension de claquage
WO2000008686A2 (fr) * 1998-08-05 2000-02-17 Infineon Technologies Ag Substrat de modules haute tension
JP2000100831A (ja) * 1998-09-22 2000-04-07 Nec Corp 電界効果型トランジスタ

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4890150A (en) * 1985-12-05 1989-12-26 North American Philips Corporation Dielectric passivation
EP0343797A1 (fr) * 1988-05-25 1989-11-29 Powerex, Inc. Thyristor à haute tension pourvu d'une extension à gradation de champ en vue d'augmenter la tension de blocage
EP0519741A2 (fr) * 1991-06-21 1992-12-23 Kabushiki Kaisha Toshiba Elément semi-conducteur à haute tension de claquage
WO2000008686A2 (fr) * 1998-08-05 2000-02-17 Infineon Technologies Ag Substrat de modules haute tension
JP2000100831A (ja) * 1998-09-22 2000-04-07 Nec Corp 電界効果型トランジスタ

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN *

Also Published As

Publication number Publication date
AU2001288157A1 (en) 2002-04-02
SE0003360D0 (sv) 2000-09-21

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