RFLDMOS device and manufacturing method thereof

Abstract

The invention provides a radio frequency (RF) laterally diffused metal oxide semiconductor (LDMOS) device and a manufacturing method thereof, which are characterized in that a substrate is provided, an epitaxial layer is formed on the substrate, a thick gate oxide layer is grown above the epitaxial layer, a source region forming region, a partial gate forming region close to a source and a partial drift region forming region close to a gate are opened by photoetching, and the thick gate oxide layer in the photoetching opening region is removed by utilizing a wet etching process. And forming undercuts at the two ends of the remaining thick gate oxide layer, growing a thin gate oxide layer above the epitaxial layer, forming a stepped gate oxide layer by the thin gate oxide layer and the thick gate oxide layer, and performing a subsequent process to form the stepped Faraday shielding case. According to the stepped Faraday shielding case, the breakdown voltage is considered, meanwhile, the hot carrier performance is improved, the resistance to ground of the Faraday shielding case is reduced, the reliability and the frequency characteristic of a device are effectively improved, and the single-layer Faraday shielding case can achieve the effect of a traditional Faraday shielding case with two layers or even three layers; the photoetching level of the Faraday shielding case is reduced, the process is simplified, and the cost is saved.

Description

technical field [0001] The invention relates to the technical field of semiconductor manufacturing, in particular to an RFLDMOS device and a manufacturing method thereof. Background technique [0002] RFLDMOS (Radio Frequency Laterally Diffused Metal Oxide Semiconductor, Radio Frequency Laterally Diffused Metal Oxide Semiconductor) is a radio frequency power device with high gain, high linearity, high withstand voltage, and high output power. RFLDMOS devices are widely used in radio frequency base stations, wireless broadcasting stations, radar and other fields. Using power array and multi-chip synthesis, the output power of the product can reach more than 500W. [0003] Faraday shields are often used in RFLDMOS devices. Such as figure 1 As shown, it is shown as a cross-sectional view of an RFLDMOS device with a layer of Faraday shield, an epitaxial layer 12 is provided on a substrate 11, a source region 15 and a drain region 17 are respectively located in a body region 14...

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