Method of manufacturing both low and high voltage BiCMOS transistors in the same semiconductor substrate

Claim 1

A method for manufacturing a semiconductor device, comprising: forming ion-implanted regions so as to make first and third regions of a second conductive type at a predetermined part of one side of a semiconductor substrate of a first conductive type, forming ion-implanted regions so as to make a fifth region of a first conductive type between fourth and sixth regions of a second conductive type at a predetermined part of said first conductive type semiconductor substrate, forming first to sixth regions by activation of impurities in said ion-implanted regions, forming an epitaxial layer on the entire surface of the structure, forming ion-implanted regions of a second conductive type in the epitaxial layer of said first and third regions, forming ion-implanted regions of a second conductive type in the epitaxial layer on said fourth and sixth regions, forming ion-implanted regions of a first conductive type in the epitaxial layer on said third and fifth regions, forming seventh to twelfth regions on said first to sixth regions by activation of impurities in said ion-implanted regions, injecting impurities of a second conductive type into a predetermined part of said ninth and twelfth regions for forming a collector region of a bipolar transistor, injecting impurities of the first conductive type and the second conductive type into predetermined parts of said seventh and eighth regions for forming source and drain regions of a high voltage MOS transistor, forming a first oxide layer on said seventh and eighth regions, followed by formation of a first polysilicon layer on said first thick oxide layer, forming a second oxide layer on said tenth and eleventh regions, followed by formation of a second polysilicon layer on said second oxide layer, forming ion-implanted regions for source and drain regions of high and low first and second conductive type MOS transistors and for emitter and base regions of high and low voltage bipolar transistors, activating the impurities in said ion-implanted regions, and forming electrodes.

Claim 2

A method for manufacturing a semiconductor device, comprising: forming ion-implanted regions so as to make first and third regions of a second conductive type at a predetermined part of one side of a semiconductor substrate of a first conductive type, forming ion-implanted regions so as to make a fifth region of a first conductive type between fourth and sixth regions of a second conductive type at a predetermined part of said first conductive type semiconductor substrate, forming first to sixth regions by activation of impurities in said ion-implanted regions, forming an epitaxial layer on the entire surface of the structure, forming ion-implanted regions of a second conductive type in the epitaxial layer of said first and third regions, forming ion-implanted regions of a second conductive type in the epitaxial layer on said fourth and sixth regions, forming ion-implanted regions of a first conductive type in the epitaxial layer on said third and fifth regions, forming seventh to twelfth regions on said first to sixth regions by activation of impurities in said ion-implanted regions, injecting impurities of a second conductive type into a predetermined part of said ninth and twelfth regions for forming a collector region of a bipolar transistor, injecting impurities of the first conductive type and the second conductive type into predetermined parts of said seventh and eighth regions for forming source and drain regions of a high voltage MOS transistor, forming a first oxide layer on said seventh and eighth regions, followed by formation of a first polysilicon layer on said first thick oxide layer, forming a second oxide layer on said tenth and eleventh regions, followed by formation of a second polysilicon layer on said second oxide layer, forming ion-implanted regions for source and drain regions of high and low first and second conductive type MOS transistors and for emitter and base regions of high and low voltage bipolar transistors, activating the impurities in said ion-implanted regions, and forming electrodes.