Power Semiconductor Devices, Methods, and Structures with Embedded Dielectric Layers Containing Permanent Charges

Abstract

Power devices using refilled trenches with permanent charge at or near their sidewalls. These trenches extend vertically into a drift region.

1 - 59 . (canceled) 
     
     
         60 . A method for operating a power device which switches between an ON state and an OFF state, comprising:
 controlling ON-state current by use of a current-controlling structure at a first surface of a semiconductor mass; said ON-state current flowing through a drift region, to provide a controllable electrical connection between a first source/drain region, at said first surface, and a second source/drain region which is not otherwise connected to said first source/drain region; and   blocking current, in the OFF state, using said drift region in conjunction said current-controlling structure;   wherein bottomless trenches extend into said drift region, and at least some ones of said trenches are at least partially filled with a trench filling material which is not an insulator, and which is electrically connected to said second source/drain region;   wherein said current-controlling structure comprises a source, a body, and a gate which is capacitively coupled to control inversion of a nearby portion of said body.   
     
     
         61 . (canceled) 
     
     
         62 . The method of  claim 60 , wherein said bottomless trenches have immobile electrostatic charge in proximity to sidewalls thereof. 
     
     
         63 . The method of  claim 60 , wherein said trench filling material is silicon. 
     
     
         64 . The method of  claim 60 , wherein said trench filling material is a substantially crystalline semiconductor material. 
     
     
         65 . The method of  claim 60 , wherein said trench filling material is substantially the same semiconductor material as parts of said drift region outside said trenches. 
     
     
         66 . The method of  claim 60 , wherein said semiconductor mass is monocrystalline silicon. 
     
     
         67 . A method for operating a power device, comprising:
 controlling turn-on and turn-off using an array of semiconductor devices; wherein said devices include trenches which have a first minimum width, and which have been angle-implanted with ions which provide immobile electrostatic charge; and   providing a graded transition of voltage outside said array, using peripheral trenches which have graduated minimum widths, including widths which are less than said first minimum width; wherein narrower ones of said peripheral trenches have a lower density of said ions in bottom portions thereof, as compared with upper portions thereof, than do wider ones of said trenches.   
     
     
         68 . The method of  claim 67 , wherein said devices are trench transistors. 
     
     
         69 . The method of  claim 67 , wherein said trenches are bottomless. 
     
     
         70 - 97 . (canceled)