Monolithic HVMOSFET active switch array

• US 4,288,801 A
• Filed: 05/30/1979
• Issued: 09/08/1981
• Est. Priority Date: 05/30/1979
• Status: Expired due to Term

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Ronen, Ram S.
• Primary Examiner(s): WOJCIECHOWICZ, EDWARD JOSEPH
• Application Number:
  US06/043,563
• Time in Patent Office: 832 Days
• Field of Search: 357/41, 357/45, 357/46, 357/23, 357/52, 357/51, 357/55
• US Class Current: 257/393
• CPC Class Codes: H01L 29/0603 characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions isolation regions between components H01L21/76; design considerations for integrated circuits H01L27/00; geometrical design considerations for devices H01L29/0657
• CPC Class Codes: H01L 29/0692 Surface layout
• CPC Class Codes: H01L 29/0847 of field-effect transistors with insulated gate H01L29/0653 takes precedence; with a passive supplementary region between source or drain and substrate related to punch-through, capacity or isolation phenomena H01L29/1079; with LDD or DDD structure H01L29/7833; for thin film transistors H01L29/78618
• CPC Class Codes: H01L 29/405 Resistive arrangements, e.g. resistive or semi-insulating field plates
• CPC Class Codes: H01L 29/42368 the thickness being non-uniform
• CPC Class Codes: H01L 29/4238 characterised by the surface lay-out
• CPC Class Codes: H01L 29/435 Resistive materials for field effect devices, e.g. resistive gate for MOSFET or MESFET
• CPC Class Codes: H01L 29/7831 with multiple gate structure FinFETs or MuGFETs H01L29/7855, thin film transistors H01L29/78645
• CPC Class Codes: H01L 29/7835 with asymmetrical source and drain regions, e.g. lateral high-voltage MISFETs with drain offset region, extended drain MISFETs

Abstract

Integrated monolithic arrays of high voltage metal oxide semiconductor field effect transistors having closed geometry grounded peripheries for interdevice isolation are able to function as drivers that may be switched on and off. The HVMOSFET'"'"'S include DMOS-like structures with separate channel and drift regions, closed geometry configurations with center drains, and split oxide topography having relatively thick oxide under a field plate and over a drift region for surface depletion and high voltage field inversion preclusion respectfully. The infra described HVMOSFET includes an active load operatively connected in cascade and connecting to a device switch for forming an integrated HV Active Switch in a monolithic array.

Claims

1. A HVMOSFET cascade switch structure having closed geometry in an integrated array on a monolithic substrate with relatively monotonicall decreasing voltage order from the center out, comprising:

(a) first switch means having a first drain area formed in the substrate at its relative center with a relatively high voltage potential applied thereto, having a first source area formed in the substrate at its relative outer periphery at a predetermined distance and in concentric relation to the first drain, and having a first gate disposed at a predetermined distance and in concentric relation above a first channel formed in the substrate interposably at a predetermined distance and in concentric relation between the relative center and the outer periphery for connection to the first drain area for operation as an active MOS load of the structure relative to the substrate; and

(b) second switch means having a second drain area formed in the substrate at its relative inner periphery that is operatively coincidently common with the first source area, having a fixed common ground voltage potential at a second source area formed in the substrate at the relative outer periphery at a predetermined distance and in concentric relation to the second drain, and having a second gate with a control input voltage potential applied thereto disposed at a predetermined distance and in concentric relation above a second channel formed in the substrate interposably at a predetermined distance and in concentric relation between the relative inner and outer peripheries for controlling the switching of an outputted relatively high voltage potential at the second drain area.

2. The HVMOSFET switch structure of claim 1 wherein the voltage potential decreases relatively monotonically from the relative center of said active load first switch means to said second drive switch means respectively.

3. The HVMOSFET switch structure of claim 1 further including oxide means relatively disposed over the structure for electrical isolation.

4. The HVMOSFET switch structure of claim 3 wherein said oxide means is relatively thick.

5. The HVMOSFET switch structure of claim 3 wherein said oxide means is relatively thick over said first switch active loads means and relatively split oxide over said second switch driver means.

6. The HVMOSFET switch structure of claim 5 wherein the relatively split oxide of said oxide means has a thin portion disposed over the channel area and under the second gate that is relatively adjacent to the source area at the relatively outer periphery and a thick portion disposed over the substrate between the channel area and the drain area at the relative inner periphery of said second switch driver switch means.

7. The HVMOSFET switch structure of claim 6 and 3 further including field plate means relatively disposed over the thick portion of the relatively split oxide of said oxide means and relatively interdisposed between the relative inner and outer periphery of said driver second switch means for directing field lines away from the relative inner periphery of said driver second switch means.

8. The HVMOSFET switch structure of claim 1 wherein the relative concentricity of said second driver switch means to said active load first switch means is relatively circuar circular.

9. The HVMOSFET switch structure of claim 1 wherein the relative concentricity of said driver second switch means to said active load first switch means is relatively elliptical.