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DE-102025136421-A1 - Signal transmission element

DE102025136421A1DE 102025136421 A1DE102025136421 A1DE 102025136421A1DE-102025136421-A1

Abstract

A signal transmission element comprises a first insulating layer on a semiconductor substrate, first and second windings on it, a second insulating layer covering the first and second windings, third and fourth windings on it, and a protective layer covering the third and fourth windings. The first and third windings are magnetically coupled, as are the second and fourth windings. The first and second windings are connected to each other, such that a current generated by mutual induction between the first and third windings flows through the second winding. The protective layer has a plurality of openings that reach two ends of the third winding and two ends of the fourth winding.

Inventors

  • Manabu Yoshino
  • Takuichiro SHITOMI

Assignees

  • MITSUBISHI ELECTRIC CORPORATION

Dates

Publication Date
20260513
Application Date
20250910
Priority Date
20241111

Claims (8)

  1. A signal transmission element comprising: a first insulating layer (200) provided on a semiconductor substrate (100); a first winding (311) and a second winding (321) provided adjacent to each other on the first insulating layer; a second insulating layer (500) provided on the first insulating layer and covering the first winding and the second winding; a third winding (611) and a fourth winding (621) provided adjacent to each other on the second insulating layer; and a protective layer (700) having an insulating property, wherein the protective layer is provided on the second insulating layer and covers the third winding and the fourth winding, in which the first winding and the third winding are magnetically coupled, the second winding and the fourth winding are magnetically coupled, the first winding and the second winding are connected to each other such that a current generated by mutual induction between the first winding and the third winding flows through the second winding, and the protective layer has a plurality of openings (OP) reaching two ends of the third winding and two ends of the fourth winding.
  2. Signal transmission element according to Claim 1 , wherein the first winding and the second winding are wound in opposite directions, and a central part area end (411a) of the first winding and an outer circumferential part area end (421b) of the second winding are electrically connected to each other, and an outer circumferential part area end (411b) of the first winding and a central part area end (421a) of the second winding are electrically connected to each other.
  3. Signal transmission element according to Claim 1 , wherein the first winding and the second winding are wound in the same direction, and a central part end (412a) of the first winding and a central part end (422a) of the second winding are electrically connected to each other; and an outer circumferential part end of the first winding and an outer circumferential part end of the second winding are electrically connected to each other.
  4. Signal transmission element according to one of the Claims 1 until 3 , wherein the thickness of the second insulating layer is specified as half the thickness required for a dielectric strength between the first winding and the second winding, and between the third winding and the fourth winding.
  5. A signal transmission element comprising: a first insulating layer (200) provided on a semiconductor substrate (100); a first winding (413) and a second winding (423) provided adjacent to each other on the first insulating layer; a second insulating layer (500) provided on the first insulating layer and covering the first and second windings; a third winding (613) and a fourth winding (623) provided adjacent to each other on the second insulating layer; a third insulating layer (800) provided on the second insulating layer and covering the third and fourth windings; a plurality of wiring layers provided on the third insulating layer; a protective layer (700) having an insulating property, wherein the protective layer is provided on the third insulating layer and covers the majority of wiring layers, in which the first winding and the third winding are magnetically coupled, the second winding and the fourth winding are magnetically coupled, the signal transmission element comprising: a first block in which the first winding and the second winding are connected to each other, such that a current generated by mutual induction between the first winding and the third winding flows through the second winding; and a second block having the same configuration as the first block, the first block and the second block being designed to be continuous in a top view, the fourth winding in the first block and the third winding in the second block being connected so that a current flowing through the fourth winding in the first block will flow through the third winding in the second block, and the protective layer having a plurality of openings (OP) reaching two ends of the third winding in the first block and two ends of the fourth winding in the second block.
  6. Signal transmission element according to Claim 5 , wherein the fourth winding in the first block and the third winding in the second block are wound in opposite directions and a central part section end (623a) of the fourth winding of the first block and an outer circumferential part section end (633b) of the third winding of the second block are electrically connected to each other, and an outer circumferential part end (623b) of the fourth winding in the first block and a central part end (633a) of the third winding in the second block are electrically connected to each other.
  7. Signal transmission element according to Claim 5 , wherein the semiconductor substrate is a SOL substrate (100A) comprising: a silicon substrate (110); an embedded insulating layer (120) provided on the silicon substrate; and a semiconductor layer (130) provided on the embedded insulating layer, and the semiconductor layer comprising a separating insulating layer (140) provided in a sub-area corresponding to a sub-area between the first block and the second block in a top view, such that it reaches the embedded insulating layer.
  8. Signal transmission element according to Claim 5 , wherein the fourth winding in the first block and the third winding in the second block are wound in the same direction, and a central part area end (655a) of the fourth winding in the first block and a central part area end (633a) of the third winding in the second block are connected together, and an outer circumferential part area end (655b) of the fourth winding in the first block and an outer circumferential part area end (633b) of the third winding in the second block are connected together.

Description

background Technical field The present disclosure relates to a signal transmission element and in particular to a signal transmission element of an isolated type. Description of the state of the art An isolated signal transmission element (transducer element) is an element that transmits a signal in a state where its input and output are electrically and physically isolated. For example, in a gate driver of a power chip, a microcomputer is connected to an input for control purposes, and a gate of the power chip is connected to an output, transmitting a signal from the microcomputer to the power chip. However, if a power chip subjected to a high voltage experiences a dielectric breakdown, the input and output sides are electrically and physically isolated for system safety, such as protecting the microcomputer and preventing electric shock. In an insulated signal transmission element that forms magnetic coupling in a direction perpendicular to a semiconductor substrate, it is necessary to etch a thick insulating layer between the winding of the upper layer and the winding of the lower layer in order to bring an electrode from a winding of a lower layer near the semiconductor substrate to an element surface, as for example in 21 the disclosed Japanese patent application no. 2023-124329 depicted. In the disclosed Japanese patent application no. 2023-124329 It is necessary to etch a thick insulating layer between the winding of the upper layer and the winding of the lower layer in order to bring the winding of the lower layer out to the element surface, and there is a problem that the processing load of the wafer process increases. Summary One objective of the present disclosure is to provide a signal transmission element which does not require a step of bringing out a winding from a lower layer to an element surface. A signal transmission element according to the present disclosure comprises: a first insulating layer provided on a semiconductor substrate; a first winding and a second winding provided adjacent to each other on the first insulating layer; a second insulating layer provided on the first insulating layer and covering the first and second windings; a third winding and a fourth winding provided adjacent to each other on the second insulating layer; and an insulating protective layer provided on the second insulating layer and covering the third and fourth windings. The first and third windings are magnetically coupled, the second and fourth windings are magnetically coupled, and the first and second windings are connected to each other such that a current generated by mutual induction between the first and third windings flows through the second winding, and the protective layer has a plurality of openings reaching two ends of the third winding and two ends of the fourth winding. According to the signal transmission element as disclosed herein, since both the third winding on the input side and the fourth winding on the output side are provided on the second insulating layer, it is possible to obtain electrodes on the input side and the output side only by removing the protective layer, without removing the second insulating layer, even if the thickness of the second insulating layer increases, so that it is possible to obtain a signal transmission element which does not require a step of bringing the winding of the lower layer out to the element surface. These and other tasks, features, aspects and advantages of the present disclosure will become more apparent from the following detailed description of the present disclosure when it is accepted in conjunction with the accompanying drawings. Brief description of the drawings 1 is a cross-sectional view that represents a configuration of a signal transmission element according to a first preferred embodiment;2 is a top view that schematically represents a plane configuration of a metal wiring layer on one side of a lower layer of the signal transmission element according to the first preferred embodiment;3 is a top view that schematically depicts a plane configuration of a metal wiring system layer on one side of an upper layer of the signal transmission element according to the first preferred embodiment;4 is a top view that schematically represents a plane configuration of a modification of the metal wiring layer on the side of the lower layer of the signal transmission element according to the first preferred embodiment;5 is a cross-sectional view that represents a configuration of a modification of the signal transmission element according to the first preferred embodiment;6 is a cross-sectional view that represents a configuration of a signal transmission element according to a second preferred embodiment;7 is a top view that schematically represents a plane configuration of a metal wiring layer on one side of a lower layer of the signal transmission element according to the second preferred embodiment; 8 is a top view that schematically represe