Renesas Electronics Corporation

Yuya Abiko

Satoshi Eguchi

Akio Ichimura

Tetsuya Iida

Natsuo Yamaguchi

Junichi Kogure

Hitoshi Matsuura

Toshiaki Igarashi

Yasuhiro Shirai

Daisuke Taniguchi

Shigeaki Saito

In a vertical power MOSFET having a superjunction structure, the withstand voltage of the power MOSFET can be ensured even if the aspect ratios of an n-type column region and a p-type column region are increased so as to vary the impurity concentration of the p-type column region. P-type semiconductor regions PRare formed on the sides of an n-type column NCadjacent to a p-type column region PC. In this configuration, the p-type semiconductor region PRis formed from the upper end of the n-type column region NCto about a half depth of a height from the upper end to the lower end of the side of the n-type column region NC. This inclines the sides of the overall p-type column region including the p-type semiconductor regions PRand the p-type column region PC

Semiconductor device and method of manufacturing the same

Properties of a semiconductor device are improved. A semiconductor device having a superjunction structure, in which p-type column regions and n-type column regions are periodically arranged, is configured as follows. Each n-type column region has a vertical section including an n-type epitaxial layer located between trenches and a tapered embedded n-type epitaxial film disposed on a side face of the trench. Each p-type column region includes an embedded p-type epitaxial film disposed within the trench. The tapered embedded n-type epitaxial film is thus provided on the sidewall of the trench in which the p-type column region is to be disposed, thereby the p-type column region is allowed to have an inverted trapezoidal shape, leading to an increase in margin for a variation in concentration of a p-type impurity in the p-type column region. On resistance can be reduced by lateral diffusion of an n-type impurity (for example, As).

Semiconductor device and method of manufacturing the semiconductor device

In a semiconductor device including a super junction structure that p-type columns and n-type columns are periodically arranged, a depth of a p-type column region in a cell region that a semiconductor element is formed is made shallower than a depth of a p-type column region in an intermediate region which surrounds the cell region. Thereby, a breakdown voltage of the cell region becomes lower than a breakdown voltage of the intermediate region. An avalanche breakdown phenomenon is caused to occur preferentially in the cell region in which even when an avalanche current is generated, the current is dispersed and smoothly flows. Thereby, it is possible to avoid local current constriction and breakage incidental thereto and consequently it becomes possible to improve avalanche resistance (an avalanche current amount with which a semiconductor device comes to be broken).

Semiconductor device and manufacturing method for the semiconductor device

A super junction structure having a high aspect ratio is formed. An epitaxial layer is dividedly formed in layers using the trench fill process, and when each of the layers has been formed, trenches are formed in that layer. For example, when a first epitaxial layer has been formed, first trenches are formed in the epitaxial layer. Subsequently, when a second epitaxial layer has been formed, second trenches are formed in the epitaxial layer. Subsequently, when a third epitaxial layer has been formed, third trenches are formed in the third epitaxial layer.

Reduction of power consumption of a semiconductor device is aimed. The semiconductor device includes a cell region where a vertical power MOSFET is formed and an intermediate region surrounding the cell region. In each of the cell region and the intermediate region, a plurality of p-type column regions and a plurality of n-type column regions are alternately formed. The n-type column region arranged in the cell region has a defect region formed therein, whereas the n-type column region arranged in the intermediate region does not have the defect region. A defect density in the n-type column region arranged in the cell region is larger than that in the n-type column region arranged in the intermediate region.

Semiconductor device and manufacturing method of the same

To provide a semiconductor device including a power semiconductor element having improved reliability. The semiconductor device has a cell region and a peripheral region formed outside the cell region. The n type impurity concentration of n type column regions in the cell region is made higher than that of n type column regions comprised of an epitaxial layer in the peripheral region. Further, a charge balance is kept in each of the cell region and the peripheral region and each total electric charge is set so that a total electric charge of first p type column regions and a total electric charge of n type column regions in the cell region become larger than a total electric charge of third p type column regions and n type column regions comprised of an epitaxial layer in the peripheral region, respectively.

Semiconductor device and method of manufacturing same

To improve characteristics of a semiconductor device (vertical power MOSFET). A spiral p-type column region having a corner is formed in a peripheral region surrounding a cell region in which a semiconductor element is formed. In an epitaxial layer of the peripheral region surrounding the cell region in which the semiconductor element is formed, a trench spirally surrounding the cell region and having the first and second side faces making up the corner is formed and the trench is filled with the epitaxial layer. By spirally arranging the p-type column region (n-type column region) in such a manner, a drop in a withstand voltage margin due to a hot spot can be avoided. In addition, the continuity of the p-type column region (n-type column region) is maintained. As a result, electric field concentration is alleviated step by step toward the outer periphery and the withstand voltage is therefore increased.

Semiconductor device and manufacturing method for the same

In the manufacturing steps of a super-junction power MOSFET having a drift region having a super junction structure, after the super junction structure is formed, introduction of a body region and the like and heat treatment related thereto are typically performed. However, in the process thereof, a dopant in each of P-type column regions and the like included in the super junction structure is diffused to result in a scattered dopant profile. This causes problems such as degradation of a breakdown voltage when a reverse bias voltage is applied between a drain and a source and an increase in ON resistance. According to the present invention, in a method of manufacturing a silicon-based vertical planar power MOSFET, a body region forming a channel region is formed by selective epitaxial growth.

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Ibaraki, Japan

Yuya Abiko