High-voltage integrated vertical resistor and manufacturing process thereof

Abstract

The manufacturing process comprises the steps of growing epitaxially a first layer from a semiconductor material substrate, forming in the first layer a first and a second buried region spaced from one another and having conductivity of the type opposite that of the first layer; growing epitaxially on the first layer a second layer of semiconductor material having the same type of conductivity as the first layer; forming in the second layer a trench extending in depth beyond the buried regions, arranged between the buried regions, and having, in plan view, a frame shape; forming an oxide layer covering the lateral walls and the base wall of the trench; and filling the remaining part of the trench with an isolating material. By this means, the portion of the second layer surrounded by the trench defines a first high-voltage resistor having a vertical structure and current flow, whereas the portion of the first layer arranged below the trench defines a second high-voltage resistor arranged in series with the first high-voltage resistor, and also having a vertical structure and current flow.

I claim:  
     
         1 . An integrated device comprising a high-voltage resistor integrated in a semiconductor material body wherein said high-voltage resistor has a vertical current flow structure.  
     
     
         2 . An integrated device according to    claim 1    wherein said high-voltage resistor has conductivity of the same type as that of said semiconductor material body.  
     
     
         3 . An integrated device according to    claim 1    wherein said high-voltage resistor is formed by a portion of said semiconductor material body extending between a first and a second surface of the semiconductor material body, and delimited at least partially by an insulation region extending from said first surface towards said second surface of said semiconductor material body.  
     
     
         4 . An integrated device according to    claim 3    wherein said insulation region has a closed shape in plan view.  
     
     
         5 . An integrated device according to    claim 3    wherein said insulation region is formed entirely of isolating material.  
     
     
         6 . An integrated device according to    claim 3   , further comprising a first and a second region having conductivity opposite that of said semiconductor material body, and arranged on opposite sides of said insulation region.  
     
     
         7 . An integrated device according to    claim 1   , further comprising first and second electronic devices formed in said semiconductor material body on opposite sides of said insulation region.  
     
     
         8 . A process for manufacturing an integrated device that includes a high-voltage resistor, the method comprising: 
 forming a semiconductor material body; and    forming in a said semiconductor material body a high-voltage resistor having a vertical current flow structure.    
     
     
         9 . A manufacturing process according to    claim 8    wherein forming a high-voltage resistor comprises the step of: 
 forming in said semiconductor material body an insulation region extending from a first surface towards a second surface of the semiconductor material body, and delimiting at least partially a portion of said semiconductor material body.  
 
     
     
         10 . A manufacturing process according to    claim 9    wherein said insulation region has a closed shape in plan view.  
     
     
         11 . A manufacturing process according to    claim 9    wherein forming an insulation region comprises: 
 forming a trench having a closed shape in plan view; and  
 filling said trench with an insulating material.  
 
     
     
         12 . A manufacturing process according to    claim 11    wherein filling said trench comprises the step of forming an oxide layer filling said trench completely.  
     
     
         13 . A manufacturing process according to    claim 11    wherein said step of filling said trench comprises the steps of: 
 forming an oxide layer covering lateral walls and a base wall of said trench, and filling the trench partially; and  
 filling the remaining part of said trench with an insulating material.  
 
     
     
         14 . A manufacturing process according to    claim 9   , further comprising: 
 forming in said semiconductor material body, a first and a second buried region spaced from one another and having a type of conductivity opposite that of the semiconductor material body; wherein said insulation region is arranged between said first and second buried regions and extends in depth beyond the first and second buried regions.    
     
     
         15 . A manufacturing process according to    claim 9   , further comprising: 
 forming in the portion of said semiconductor material body surrounded by said insulation region, and at said first surface, a region with low resistivity and having the same type of conductivity as said semiconductor material body.    
     
     
         16 . A manufacturing process according to    claim 9   , further comprising: 
 forming in the portion of said semiconductor material body surrounded by said region of isolation, and at said first surface, a region with low resistivity and having conductivity of the type opposite that of said semiconductor material body.    
     
     
         17 . A process for manufacturing an integrated device comprising a high-voltage resistor, the method comprising: 
 forming a semiconductor material body;    forming in said semiconductor material body a buried region having conductivity opposite that of the semiconductor material body;    forming a trench having a closed shape in plan view;    forming an oxide layer covering the lateral walls and the base wall of said trench; and    filling a remaining part of said trench with a conductive material.    
     
     
         18 . A manufacturing process according to    claim 17   , further comprising: 
 forming in the portion of said semiconductor material body surrounded by said trench, and at said first surface, a first region with low resistivity and having the same type of conductivity as said semiconductor material body.    
     
     
         19 . A manufacturing process according to    claim 17   , further comprising: 
 forming in the portion of said semiconductor material body surrounded by said trench, a second region having the same type of conductivity as said buried region.    
     
     
         20 . An integrated device, comprising: 
 a semiconductor body having a surface;    a doped semiconductor region extending longitudinally into the semiconductor body from the surface, the semiconductor region being a resistor extending transversely with respect to the surface; and    an insulating region extending longitudinally into the semiconductor body from the surface, the insulating region laterally surrounding the semiconductor region.    
     
     
         21 . The device of    claim 20    wherein the insulating region is open at a bottom portion such that the semiconductor region is contiguous with the semiconductor body.  
     
     
         22 . The device of    claim 20    wherein the semiconductor region has a rectangular cross-section and the insulating region has a rectangular frame shape.  
     
     
         23 . The device of    claim 20    wherein the insulating region is completely of electrically isolating material.  
     
     
         24 . The device of    claim 20    wherein the insulating region includes insulating walls made of electrically insulating material and a conductive filler that is laterally surrounded by the insulating walls.  
     
     
         25 . The device of    claim 24    wherein the semiconductor region includes an upper region of a first conductivity type; a middle region of a second conductivity type, opposite to the first conductivity type; and a lower region of the first conductivity type, the middle region being positioned between the upper and lower regions such that a transistor is formed that includes the conductive filler as a gate, the upper region as a first source/drain, and the lower region as a second source/drain.  
     
     
         26 . The device of    claim 20   , further comprising first and second semiconductor regions having conductivity opposite to a conductivity of the semiconductor material body, and arranged immediately adjacent to opposite sides of the insulation region.  
     
     
         27 . The device of    claim 20    wherein the semiconductor region includes an upper region adjacent to the surface of the semiconductor body and a lower region positioned below the upper region, the upper region being doped at a higher doping level compared to the lower region.  
     
     
         28 . The device of    claim 20    wherein the semiconductor region includes an upper region adjacent to the surface of the semiconductor body and a lower region positioned below the upper region, the upper region having a conductivity type opposite to a conductivity type of the lower region, thereby forming a diode.