JP2013150000A5

JP2013150000A5 -

Info

Publication number: JP2013150000A5
Application number: JP2013062296A
Authority: JP
Filing date: 2013-03-25
Publication date: 2014-07-24

Description

本明細書が開示するＩＧＢＴは、半導体基板と、エミッタ電極と、コレクタ電極と、ゲート電極を有している。半導体基板の上面には、当該上面を平面視したときにトレンチによって仕切られた四角形の領域が形成されている。トレンチの内面は、絶縁膜に覆われている。ゲート電極は、トレンチの内部に配置されている。エミッタ電極は、半導体基板の上面に形成されている。コレクタ電極は、半導体基板の下面に形成されている。四角形の領域内には、エミッタ領域と、ボディ領域と、ドリフト領域と、コレクタ領域が形成されている。エミッタ領域は、ｎ型半導体により構成されており、前記絶縁膜と接しており、エミッタ電極に対してオーミック接続されている。ボディ領域は、ｐ型半導体により構成されており、エミッタ領域に隣接する位置で前記絶縁膜と接しているとともにトレンチの内側コーナー部で前記絶縁膜と接しており、エミッタ電極に対してオーミック接続されている。ドリフト領域は、ｎ型半導体により構成されており、ボディ領域の下側に形成されており、ボディ領域によってエミッタ領域から分離されており、トレンチの下端部の前記絶縁膜と接している。コレクタ領域は、ｐ型半導体により構成されており、ドリフト領域の下側に形成されており、ドリフト領域によってボディ領域から分離されており、コレクタ電極に対してオーミック接続されている。ボディ領域とドリフト領域の間には、高濃度ｎ型領域が形成されている。高濃度ｎ型領域は、ｎ型半導体により構成されており、ボディ領域と接しており、ボディ領域によってエミッタ領域から分離されており、ドリフト領域と接しており、ボディ領域をドリフト領域から分離しており、ドリフト領域よりも高いｎ型不純物濃度を有する。半導体基板を平面視したときに、四角形の領域内において、エミッタ領域が前記絶縁膜と接している境界線の総距離が、ボディ領域が前記絶縁膜と接している境界線の総距離より短い。 The IGBT disclosed in this specification includes a semiconductor substrate, an emitter electrode, a collector electrode, and a gate electrode. On the upper surface of the semiconductor substrate, a quadrangular region partitioned by trenches when the upper surface is viewed in plan is formed. The inner surface of the trench is covered with an insulating film. The gate electrode is disposed inside the trench. The emitter electrode is formed on the upper surface of the semiconductor substrate. The collector electrode is formed on the lower surface of the semiconductor substrate. An emitter region, a body region, a drift region, and a collector region are formed in the rectangular region . The emitter region is made of an n-type semiconductor, is in contact with the insulating film, and is ohmically connected to the emitter electrode. The body region is made of a p-type semiconductor, is in contact with the insulating film at a position adjacent to the emitter region, is in contact with the insulating film at the inner corner of the trench, and is ohmically connected to the emitter electrode. ing. The drift region is made of an n-type semiconductor, is formed below the body region, is separated from the emitter region by the body region, and is in contact with the insulating film at the lower end of the trench. The collector region is made of a p-type semiconductor, is formed below the drift region, is separated from the body region by the drift region, and is ohmically connected to the collector electrode. A high concentration n-type region is formed between the body region and the drift region. The high-concentration n-type region is composed of an n-type semiconductor, is in contact with the body region, is separated from the emitter region by the body region, is in contact with the drift region, and is separated from the drift region. The n-type impurity concentration is higher than that of the drift region. When the semiconductor substrate is viewed in plan, the total distance of the boundary line where the emitter region is in contact with the insulating film is shorter than the total distance of the boundary line where the body region is in contact with the insulating film in the rectangular region.

なお、エミッタ領域は、何れの位置で絶縁膜と接していてもよい。例えば、エミッタ領域は、トレンチの内側コーナー部で絶縁膜と接していてもよいし、それ以外の位置で絶縁膜と接していてもよい。また、ボディ領域は、エミッタ領域に隣接する位置で前記絶縁膜と接しているとともにトレンチの内側コーナー部で前記絶縁膜と接していれば、その他の位置で絶縁膜と接していてもよく、接していなくてもよい。また、上記の「トレンチの内側コーナー部」とは、トレンチが折れ曲がっている部分（すなわち、コーナー）の内側の部分を意味する。 Note that the emitter region may be in contact with the insulating film at any position. For example, the emitter region may be in contact with the insulating film at the inner corner of the trench, or may be in contact with the insulating film at other positions. In addition, the body region may be in contact with the insulating film at a position adjacent to the emitter region and may be in contact with the insulating film at other positions as long as it is in contact with the insulating film at the inner corner of the trench. It does not have to be. In addition, the "inner corner portion of the trench" above, that means the inner part of the portion bent trench (i.e., the corner).

このＩＧＢＴをオンさせると、絶縁膜と接している範囲のボディ領域にチャネルが形成され、チャネルを通ってエミッタ領域からドリフト領域に電子が流れる。電子は、ドリフト領域を通過してコレクタ領域へ流れる。これと同時に、コレクタ領域からドリフト領域にホールが流入し、ドリフト領域の電気抵抗が低下する。ドリフト領域内のホールは、ボディ領域へ向かって流れる。このとき、ゲート電極の下方のドリフト領域に存在するホールは、ゲート電極を迂回するように流れるので、ゲート電極の下端部の側面近傍のドリフト領域ではホールの濃度が高くなる。特に、トレンチの内側コーナー部の近傍のドリフト領域では、ゲート電極を迂回するホールが集中する。このため、内側コーナー部近傍のドリフト領域では、ホールの濃度が極めて高くなり、電気抵抗が極めて低くなる。このＩＧＢＴでは、トレンチの内側コーナー部の絶縁膜に接するようにボディ領域が形成されている。すなわち、内側コーナー部の絶縁膜に接する位置にチャネルが形成される。この内側コーナー部のチャネルを通って、内側コーナー部近傍のドリフト領域（すなわち、上述した電気抵抗が極めて低い領域）に電子が流入する。このため、電子は、低損失でドリフト領域を通過することができる。さらに、このＩＧＢＴでは、高濃度ｎ型領域によって、ホールがドリフト領域からボディ領域に流れることが抑制される。したがって、ドリフト領域のホールの濃度をより上昇させることが可能であり、ＩＧＢＴのオン抵抗を大幅に低下させることができる。また、トレンチによって仕切られた四角形の領域において、エミッタ領域が絶縁膜と接している境界線の総距離を、ボディ領域が絶縁膜と接している境界線の総距離より短くすることで、チャネルを流れる電流密度を上昇させることができる。このため、ＩＧＢＴの飽和電流が低くなり、ＩＧＢＴに過電圧が印加されたときにＩＧＢＴに高い電流が流れることを抑制することができる。 When the IGBT is turned on, a channel is formed in the body region in contact with the insulating film, and electrons flow from the emitter region to the drift region through the channel. Electrons flow through the drift region to the collector region. At the same time, holes flow from the collector region to the drift region, and the electrical resistance of the drift region decreases. The holes in the drift region flow toward the body region. At this time, holes existing in the drift region below the gate electrode flow so as to bypass the gate electrode, so that the hole concentration is high in the drift region near the side surface of the lower end portion of the gate electrode. In particular, holes that bypass the gate electrode concentrate in the drift region near the inner corner of the trench. For this reason, in the drift region in the vicinity of the inner corner portion, the hole concentration becomes extremely high and the electric resistance becomes extremely low. In this IGBT, a body region is formed so as to be in contact with the insulating film at the inner corner of the trench. That is, a channel is formed at a position in contact with the insulating film at the inner corner portion. Electrons flow into the drift region in the vicinity of the inner corner portion (that is, the above-described region having an extremely low electric resistance) through the channel of the inner corner portion. For this reason, electrons can pass through the drift region with low loss. Furthermore, in this IGBT, the high concentration n-type region suppresses holes from flowing from the drift region to the body region. Therefore, the hole concentration in the drift region can be further increased, and the on-resistance of the IGBT can be significantly reduced. In addition, in the rectangular region partitioned by the trench, the channel is formed by making the total distance of the boundary line where the emitter region is in contact with the insulating film shorter than the total distance of the boundary line where the body region is in contact with the insulating film. The flowing current density can be increased. For this reason, the saturation current of the IGBT is lowered, and it is possible to suppress a high current from flowing through the IGBT when an overvoltage is applied to the IGBT.

Claims

An IGBT,
It has a semiconductor substrate, an emitter electrode, a collector electrode, and a gate electrode,
On the upper surface of the semiconductor substrate, a rectangular region partitioned by a trench when the upper surface is viewed in plan is formed,
The inner surface of the trench is covered with an insulating film,
The gate electrode is arranged inside the trench,
The emitter electrode is formed on the upper surface of the semiconductor substrate,
The collector electrode is formed on the lower surface of the semiconductor substrate,
In the rectangular area ,
an emitter region made of an n-type semiconductor, in contact with the insulating film, and in ohmic contact with the emitter electrode;
A body region that is made of a p-type semiconductor, is in contact with the insulating film at a position adjacent to the emitter region, is in contact with the insulating film at an inner corner of the trench, and is in ohmic contact with the emitter electrode When,
a drift region formed of an n-type semiconductor, formed below the body region, separated from the emitter region by the body region, and in contact with the insulating film at the lower end of the trench;
a collector region made of a p-type semiconductor, formed below the drift region, separated from the body region by the drift region, and ohmic-connected to the collector electrode;
Is formed ,
A high-concentration n-type region is formed between the body region and the drift region,
The high-concentration n-type region is composed of an n-type semiconductor, is in contact with the body region, is separated from the emitter region by the body region, is in contact with the drift region, and is separated from the drift region. And has a higher n-type impurity concentration than the drift region,
When the semiconductor substrate is viewed in plan, the total distance of the boundary line in which the emitter region is in contact with the insulating film is shorter than the total distance of the boundary line in which the body region is in contact with the insulating film in the rectangular region.
IGBT characterized by this.

The body region has a first region that is ohmically connected to the emitter electrode, and a second region that is electrically connected to the emitter electrode through the first region;
The first region is not in contact with the insulating film,
A second region is in contact with the insulating film;
The emitter region is not in contact with the insulating film at the inner corner of the trench;
The IGBT according to claim 1 .

A quadrangular region partitioned by a trench when the top surface of the semiconductor substrate is viewed in plan is formed,
An emitter region and a body region are formed in a rectangular region,
The rectangular area has an aspect ratio in the range of 0.4 to 2.5,
The IGBT according to claim 1 or 2 , characterized in that: