Abstract: An integrated circuit is provided wherein bipolar, CMOS and DMOS devices are merged together on one chip with fabrication taking place from a CMOS point of view rather than from a bipolar point of view as in the prior art and p-type epitaxial silicon is used as opposed to n-type epitaxial silicon in the prior art. The integrated circuit uses a P+ substrate upon which a P- epitaxial layer is formed. N+ buried regions isolate the DMOS, PMOS and NPN bipolar devices from the P-epitaxial layer. Each of the devices is formed in a N-well with a first level of polysilicon gate layer providing both the gate and masking for the backgate diffusion of the DMOS device and a sidewall oxide later formed on the first level gate layer to control the diffusion of the source and drain regions of the DMOS device to control channel length. A second level of polysilicon layer provides the gate structures for the CMOS devices as well as one plate of a capacitor.

Abstract: An integrated circuit is provided wherein bipolar, CMOS and DMOS devices are merged together on one chip with fabrication taking place from a CMOS point of view rather than from a bipolar point of view as in the prior art and p-type epitaxial silicon is used as opposed to n-type epitaxial silicon in the prior art. The integrated circuit uses a P+ substrate upon which a P-epitaxial layer is formed. N+ buried regions isolate the DMOS, PMOS and NPN bipolar devices from the P-epitaxial layer. Each of the devices is formed in a N-well with a first level of polysilicon gate layer providing both the gate and masking for the backgate diffusion of the DMOS device and a sidewall oxide later formed on the first level gate layer to control the diffusion of the source and drain regions of the DMOS device to control channel length. A second level of polysilicon layer provides the gate structures for the CMOS devices as well as one plate of a capacitor.

Abstract: An integrated circuit having PMOS, NMOS and NPN transistors is described for applications in which both digital and analog circuits are required. The integrated circuit is designed to allow standard CMOS cells to be used in the integrated circuit without redesign. A P+ substrate (48) is provided upon which a first P- epitaxy layer (46) is formed. N+ DUF regions (50,52) are provided for the PMOS and NPN transistors, respectively. The base region (68) is formed in an Nwell (58) by implantation and diffusion. Before diffusion, a nitride layer (70) is formed over the base (68) to provided an inert annealing thereof. The base diffusion and collector diffusion occurs before the CMOS channel stop and source/drain diffusions in order to prevent altering diffusion times for the MOS transistors.

Abstract: High voltage capacitors particularly suited for a BiCMOS process are formed in conjunction with prior art low voltage capacitors. In a first embodiment of a high voltage capacitor, an N+ region (66) is used as a first plate of the capacitor. The thermal gate oxice layer (48) used in conjunction with the MOS transistors (22,24) is also grown over the N+ region (66). Since the thermal oxide growth over the N+ region is accelerated, a thicker oxide region will be formed. A polysilicon plate (70) is formed over the thick oxide region (68) at the same time the first plate (12) of the low voltage capacitor (10) is formed. Alternatively, a nitride layer (18) may be formed over the thick oxide layer (68). The nitride layer (18) is also used in the formation of a low voltage capacitor (10).