Method of making high-voltage bipolar/CMOS/DMOS (BCD) devices
View Patent ↗A process for making an integrated circuit is described wherein sequence of mask steps is applied to a substrate or epitaxial layer of p-type material. The sequence consists of sixteen specific mask steps that permit a variety of bipolar/CMOS/DMOS devices to be fabricated. The mask steps include (1) forming at least one N-well in the p-type material, (2) forming an active region, forming a p-type field region, (4) forming a gate oxide, (5) carrying out a p-type implantation, (6) forming polysilicon gate regions, (7) forming a p-base region, (8) forming a N-extended region, (9) forming a p-top region, 10) carrying out an N+ implant, (11) carrying out a P+ implant, (12) forming contacts, (13) depositing a metal layer, (14) forming vias, (15) depositing a metal layer therethrough, and (16) forming a passivation layer. Up to any three of mask steps (4), (7), (8), and (9) may be omitted depending on the type of integrated circuit.
1. A manufacturing process for making various high-voltage bipolar/CMOS/DMOS (BCD) integrated circuits of different type using a limited number of different mask steps, said process comprising:
(a) predefining a set of mask steps, each mask step comprising performing an associated activity through a separate mask distinct from the respective masks associated with the other mask steps of said set of mask steps;
(b) identifying a plurality of specific sequences of mask steps from said predefined set, each specific sequence being associated with the manufacture of one or more specific integrated circuits;
(c) selecting a specific integrated circuit to manufacture;
(d) selecting one of said specific sequences of mask steps from said predefined set of mask steps as a selected specific sequence to manufacture said specific integrated circuit;
(e) providing a starting material selected from the group consisting of: a p-type bulk substrate, and a p-type epitaxial layer over a P+ bulk substrate; and
(f) performing said selected sequence of mask steps on said starting material in numerical order to make said selected specific integrated circuit; and
said predefined set of mask steps consisting essentially of:
(1) a first mask step wherein an n-type implant is performed in said p-type material to form an N-well with the aid of a mask identified as an N-well mask;
(2) a second mask step wherein an active region is formed by etching through an oxidation layer with the aid of a mask identified as an active region mask;
(3) a third mask step wherein a p-type field region is formed by performing a p-type implant with the aid of a mask identified as a P-field mask;
(4) a fourth mask step wherein a gate oxide is etched with the aid of a mask identified as a gate oxide mask;
(5) a fifth mask step wherein a p-type implantation is carried out with the aid of a mask identified as a thin gate oxide mask;
(6) a sixth mask step wherein polysilicon gate regions are etched with the aid of a mask identified as a polysilicon gate patterning mask;
(7) a seventh mask step wherein a p-base region is formed by p-type implantation with the aid of a mask identified as a p-base mask;
(8) an eighth mask step wherein a N-extended region is formed by N-type implantation with the aid of a mask identified as an N-extended region mask;
(9) a ninth mask step wherein a p-top region is formed by p-type implantation with the aid of a mask identified as a P-top mask;
(10) a tenth mask step wherein an N+ implantation is carried out with the aid of a mask identified as an N+ implant mask;
(11) an eleventh mask step wherein a P+ implantation is carried out with the aid of a mask identified as a P+ implant mask;
(12) a twelfth mask step wherein contacts are etched with the aid of a mask identified as a contact mask;
(13) a thirteenth mask step wherein a deposited first metal layer is etched with the aid of a mask identified as a first metal mask;
(14) a fourteenth mask step wherein vias are etched in underlying material with the aid of a mask identified as a vias mask;
(15) a fifteenth mask step wherein a deposited second metal layer is etched with the aid of a mask identified as a second metal mask; and
(16) a sixteenth mask step wherein a passivation layer is etched with the aid of a mask identified as a passivation mask; and
wherein said selected specific sequence consists of at least said mask steps 1 to 3, 5, 6, 9 and 10 to 16.
2. The process as claimed in claim 1 , further comprising at least one of said mask steps 4 and 7 depending on the type of said selected specific integrated circuit.
3. The process as claimed in claim 1 , wherein said selected sequence comprises mask steps 1, 2, 3, 4, 5, 6, 9, 10, 11, 12, 13, 14, 15, and 16.
4. The process as claimed in claim 1 , wherein said selected specific sequence comprises mask steps 1, 2, 3, 4, 5, 6, 7, 9, 10, 11, 12, 13, 14, 1, and 16.