Radio frequency ldmos device and manufacturing method thereof

Abstract

The invention discloses a radio frequency LDMOS device. A buried layer is contained in a drift region, wherein the doping type of the drift region and the doping type of the buried layer are opposite. The buried layer is surrounded by the drift region and a drain region. The buried layer and a channel region are spaced at a certain distance. The doping concentration of the buried layer and the doping concentration of the drift region meet the requirement that when the working voltage is applied to the drain region, the buried layer and the drift region are exhausted completely. Under the condition that when the working voltage is applied to the drain region, the buried layer and the drift region are exhausted completely, the higher the doping concentration of the drain region is, the smaller the source-drain on-resistance of the radio frequency LDMOS device is. When the working voltage is applied to the drain region, the larger the completely exhausted region formed in the buried layer and the drift region is, the smaller the source-drain stray capacitance of the radio frequency LDMOS device is. The invention further discloses a manufacturing method of the radio frequency LDMOS device. By the adoption of the radio frequency LDMOS device, the source-drain on-resistance and the source-drain stray capacitance of the radio frequency LEDMOS device can be reduced at the same time, and the performance of the device is improved.

Description

technical field [0001] The invention relates to the field of semiconductor integrated circuit manufacturing, in particular to a radio frequency LDMOS device; the invention also relates to a method for manufacturing the radio frequency LDMOS device. Background technique [0002] RF Lateral Field Effect Transistor (RF LDMOS) is a common device used in RF base stations and broadcasting stations. High breakdown voltage, low source-drain on-resistance (RDSON) and low source-drain parasitic capacitance (Coss) are device characteristics that RF LDMOS must have. In order to minimize the parasitic capacitance between the source region, the channel and the substrate, a heavily doped substrate material and a lightly doped epitaxial layer are usually used, and tungsten deep contact holes are used to connect the source region, channel, and substrate. epitaxial layer and substrate. Such as figure 1 Shown is a schematic structural diagram of an existing radio frequency LDMOS device. Tak...

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Problems solved by technology

To keep RDSON low, it is necessary to increase the doping concentration of the drift region 103 as much as possible, but this may cause the drift region 103 to not be completely depleted when a high voltage is applied to the drain region 106, resulting in a drop in breakdown voltage

In addition, the main factor restricting the decline of Coss is the junction capacitance from the drift region 103 to the silicon substrate 101. If the concentration of the drift region 103 increases, the junction capacitance will also increase, which is also not conducive to the decline of Coss.

Therefore, the two parameters of RDSON and Coss are mutually restricted, and the existing device structure cannot reduce both of them at the same time by increasing the concentration of the drift region, so the device characteristics of the existing RF LDMOS are difficult to achieve excellent performance

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