LDMOS device resistant to total dose effect

Abstract

The invention belongs to the technical field of radiation-resistant semiconductors. The invention provides a novel LDMOS power device structure which can greatly enhance the total dose effect reinforcement capability of an LDMOS device. LDMOS devices are often used in high-voltage high-power fields. For an LDMOS device withstanding a working voltage of 20V, the thickness of the high-voltage-resistant gate oxide layer is usually dozens of micrometers. The invention, in view of the total dose effect sensitivity of a thick gate oxide layer, provides a method for introducing a thin gate oxide structure into a region close to the source of the thick gate oxide layer in order to form a novel LDMOS device having double gate oxide layers. The novel LDMOS device has beneficial effects that the newly introduced thin gate oxide region still turns off the entire LDMOS device when the high-voltage-resistant thick gate oxide region is affected by a serious space radiation total dose effect; due to the case that the anti-total dose effect capability of the thin oxide layer is better than that of the thick gate oxide, the leakage current between the source and the drain can be suppressed, so thatthe LDMOS device can obtain a good total dose reinforcement effect; and the structure cannot causes other problems such as an increase in area and process incompatibility.

Description

technical field [0001] The present invention relates to integrated circuits, and more particularly to LDMOS devices. Background technique [0002] Semiconductor power devices are another technological highland in the semiconductor industry besides the three major industries of application-specific integrated circuits, semiconductor equipment, and integrated circuit design simulation and design software. Laterally Diffused MOSFET (LDMOS) power devices have the characteristics of high operating voltage and good process compatibility, and are widely used in power switching conversion, microwave / RF power amplification, high-voltage output and other fields. [0003] Such as figure 1 The cross-sectional view of a conventional LDMOS device shown includes 101P-substrate, 102N-drift region, 103P well, 104P+ region, 105N+ source region, 106 source, 107 gate oxide layer, 108 gate, 109 field oxygen, 110 drain , 111N+ drain region. figure 1 The LDMOS device shown uses RESURF (Reduced ...

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Problems solved by technology

figure 1 The LDMOS device shown uses RESURF (Reduced SURface Field) technology and field plate technology to improve the withstand voltage capability. When the device works in a radiation environment, its very thick high-voltage insulating oxide layer will continuously accumulate oxide trap charges and The interface state charge makes the performance parameters of the device gradually degrade and fail, such as the decrease of the electron mobility of the inversion layer, the increase of the leakage current and the drift of the threshold voltage, etc., causing the device to not be turned on and off normally, and resulting in an increase in the overall power consumption of the circuit

[0004] In order to suppress the failure of the total dose of the device, a common method is to thin the thickness of the gate oxide, but this also reduces the high-voltage withstand capability of the gate oxide, making the gate dielectric layer easy to break down; Zhao Qingtai et al. proposed A LDMOS device structure was proposed, application number 201310505168.3, which uses a dielectric isolation gate region to form a multi-gate structure, and at the same time injects heavily doped recombination centers into the gate intervals. This device greatly increases the total dose while strengthening In addition, Xue Shoubin and others proposed that the side of the field oxygen region close to the gate channel region should be implanted with inversion impurities in the drift region, application number 201010280674.3, this method can certainly suppress the total dose of field oxygen radiation charge to a certain extent , but actually want to significantly reduce the leakage level of this region, the required high doping concentration will greatly affect the device performance

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