LDMOS chip light doped drift region structure and forming method

Abstract

The invention relates to a lightly-doped drift region structure of an LDMOS chip and a formation method, a thin film layer is firstly covered on the upper surface of an LDD structure before the doping to form an LDD vicinal structure after being covered by the thin film layer, an ion injection barrier layer is formed at the LDD vicinal structure through the physical and chemical methods to further form the LDD structure before the doping, the thickness of the barrier layer is gradually reduced from one side which is near to a gate region to the other side which is near to a drain region, the ion injection of N-type impurities is finally carried out on the surface of the LDMOS chip device, and the LDD structure with the simultaneous approximate linear increase along vertical and horizontaldirections is finally formed. The LDD simultaneously forms the concentration gradients along the horizontal and the vertical directions, thereby leading the LDD doping concentration to be linearly increased from the side which is near to a gate to the side which is near to a drain; compared with the conventional LDMOS, the lightly-doped drift region structure can improve the device breakdown voltage under the situation of maintaining the resistance of the drain unchanged basically or greatly reducing the resistance of the drain at the same time of maintaining the device breakdown voltage unchanged basically, thereby improving the frequency and the power performance of the LDMOS device.

Description

Technical field [0001] The invention relates to a semiconductor chip structure, in particular to a new structure forming method of a lightly doped drift region of an LDMOS chip, which is mainly used in the fields of communication, radar and the like. Background technique [0002] Lateral double diffused metal oxide semiconductor (LDMOS) devices have a wide range of applications in communications, radar and other fields due to their many advantages. In order to obtain larger output power and higher reliability, it is usually required that the source and drain regions have a higher reverse breakdown voltage. The conventional method is to make a lightly doped drift region (LDD) on the side of the drain of the MOS transistor to reduce the doping concentration of the drain region and expand the width of the ionization layer to obtain a higher reverse breakdown voltage. [0003] Figure 1 shows the structure of a conventional LDMOS chip, including source 1, P+ substrate 2, P-type double ...

AI Technical Summary

Problems solved by technology

However, the reduction of LDD doping concentration will lead to the reduction of the total amount of LDD impurities, which will cause the source-drain on-resistance to increase, resulting in a sharp decrease in the high-frequency gain of the LDMOS device, and the deterioration of the frequency and power characteristics of the device.

Therefore, reducing the drain resistance and increasing the breakdown voltage of the device are a pair of contradictions that are difficult to reconcile with conventional LDD structure LDMOS chips.

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