Double Resurf Effect Of Ldmos And Power Management Circuit Bcd Process Research

RESURF (REduced SURface Field) technology is one of the most important techniques for lateral power devices. Double RESURF technology can improve devices breakdown voltage and can decrease their On-resistance obviously. In this paper, the author presented a novel double RESURF LDMOS with multiple rings in non-uniform drift region. Moreover, this power device and low voltage power manage circuits have been successfully integrated on the same chip by BCD process. The main work of the author included a double RESURF LDMOS with a uniform P layer design; a novel double RESURF LDMOS with multiple rings in non-uniform drift region research; BCD process design for a power manage circuit; technology experiments of the device and circuit and test results analyse. Author optimised and researched the double RESURF LDMOS with a uniform P layer. The total charge in the Nwell drift region of the double RESURF device can be increased by twice as much as that of the single RESURF device to minimize on-resistance because of the P-top layer. The key problem of double RESURF research is the charge balance between Nwell drift region and P-top layer of double RESURF devices. Only if these two kinds of charges matched, devices may satisfy RESURF theory and will obtain good performance. Author analysed the relationship between the impurity concentration and length of Nwell drift region and P-top layer and breakdown voltage and on-resistance of the traditional double RESURF LDMOS by numerical simulation. The simulation results also indicated that the surface electric field distribution of the device with multiple P-top region structure was more uniform. And a buried P-top layer divided the Nwell drift region into two parallel conduction paths that made the on-resistance of this device was about 2/3 that of the traditional double RESURF LDMOS. This paper presented a novel double RESURF LDMOS with multiple rings in non-uniform drift region. Theory analyse, numerical simulation and experiments indicated that the surface electric field of the device was more...