Optimized junction termination of semiconductor components

Abstract

The invention relates to a semiconductor component which is capable of blocking such as an (IGBT), a thyristor, a GTO or diodes, especially schottky diodes. An insulator profile section ( 10 a , 10 b , 10 c , 10 d , 11 ) provided in the border area of an anode metallic coating ( 1, 31 ) is fixed (directly in the edge area) on the substrate ( 9 ) of the component. The insulator profile has a curved area (KB) and a base area (SB), said curved area having a surface (OF) which begins flat and curves outward and upward in a steadily increasing manner. A metallic coating (MET 1; 30 a , 30 b , 30 c , 30 d , 31 b ) is deposited on the surface (OF). Said coating directly follows the surface curvature and laterally extends the inner anode metallic coating. The upper end of the curved metallic coating (MET 1; 30 a , 30 b . . . ) is distanced and insulated from one of these surrounding outer metallic coatings (MET 2; 3 ) by the surrounding base area (SB) of the insulator profile ( 10 a , . . . , 11 ) such that an extensively constant course of the line of force which evades extreme values results between both metallic coatings ( 1, 31 , MET 1; 3 , MET 2 ) when reverse voltage or blocking voltage is applied between the interspaced metallic coatings.

1 . Semiconductor component capable of blocking, such as an IGBT, a thyristor, a GTO or a diode, especially a Schottky diode, wherein 
 (a) an insulator profile ( 10   a ,  10   b ,  10   c ,  10   d ,  11 ) is provided in a termination portion of an anode metallic coating ( 1 ,  31 ) and is fixed (directly in the termination portion) on a substrate ( 9 ) of the component and having a curved portion (KB) and a base portion (SB), said insulator profile comprising a surface (OF) in the curved portion (KB), which begins flat and is curved outwards and upwards in a steadily increasing manner;    (b) a metallic coating (MET 1 ;  30   a ,  30   b ,  30   c ,  30   d ,  31   b ) is deposited on the surface (OF), which coating directly follows the surface curvature and laterally extends the inner anode metallic coating;    (c) to space an upper end of the curved metallic coating (MET 1 ;  30   a ,  30   b  . . . ) in an insulating manner by the surrounding base portion (SB) of the insulator profile ( 10   a , . . . ,  11 ) from an outer metallic coating (MET 2 ; 3 ) surrounding said base portion such that a substantially constant course of flux lines avoiding peak values results between both metallic coatings ( 1 ,  31 , MET 1 ;  3 , MET 2 ), when one of reverse bias voltage and blocking voltage is applied between the spaced metallic coatings.    
     
     
         2 . Component according to  claim 1 , wherein a plurality of insulator profiles ( 10   b ,  10   c ,  10   d ), especially two or three insulator profiles, each having a curved portion (KB) and base portion (SB), are arranged in a staggered manner around the inner anode metallic coating ( 1 ), said plurality of insulator profiles being all fixed on the substrate ( 9 ), wherein the curved metallic coating ( 30   b ) of the innermost insulator profile conductingly passes over into the anode metallic coating ( 1 ) and the surrounding outer metallic coating ( 3 ) of the outermost insulator profile ( 10   d ) is provided as a cathode metallic coating ( 3 ) of the component.  
     
     
         3 . Component according to  claim 2 , wherein the steady course of curvature of the curved metallic coatings ( 30   b ,  30   c ,  30   d ) is the steeper towards the outside, the further outward the associated insulator profile ( 10   b ,  10   c ,  10   d ) is located relative to the inner anode metallic coating ( 1 ).  
     
     
         4 . Component according to  claim 1 , wherein only one insulator profile ( 10   a ) surrounds the anode metallic coating ( 1 ,  31 ), said insulator profile ( 10   a ) having a height in the base portion (SB), said height being more than 5 μm, in particular substantially 10 μm, and 
 the metallic coating ( 30   a ) in the upper portion of the curved portion of the insulator profile is noticeably inclined (more than 10°), in particular between 15° and 20°, relative to a surface of the substrate ( 9 ), and  
 a lateral distance of an upper end of the curved portion (KB) from an inner end of the outer metallic coating ( 3 ) is not less than, in particular substantially, ten times the height of the base portion (SB) of the insulator profile ( 10   a ).  
 
     
     
         5 . Component according to  claim 1 , wherein only one insulator profile ( 10   a ) surrounds the anode metallic coating ( 1 ,  31 ), said insulator profile ( 11 ) being flat in the base portion (SB) and having a height of less than 5 μm, in particular substantially 2 μm, and 
 an upper portion of the metallic coating ( 31   b ) is slightly curved, especially inclined by a maximum of approx. 10° relative to the surface of the substrate ( 9 ), wherein a distance of said upper end of the only slightly curved metallic coating ( 31   b ) from an inner end of the outer metallic coating ( 3 ) is more than ten times the height of the base portion (SB), in particular more than fifty times to two-hundred times the height of the base portion (SB),  
 wherein the anode ( 31 ) extends along a curved hood ( 32 ,  32   a ) running particularly analogously to the curved portion in a continued manner in a distance (h 41 ) above the insulator profile ( 11 ), and  
 an insulating mass ( 41 ) is provided between the insulator profile ( 11 ) and the hood ( 32 ).  
 
     
     
         6 . Semiconductor component capable of blocking according to any one of the previous claims for power electronics; or method for producing a termination portion of said component, wherein the insulator profile ( 10   a ,  10   b ) including said curved surface (OF), which is free of steps, is produced or may be produced by gray-tone lithography in the termination portion of an anode ( 1 ;  31 ), wherein 
 (a) the substrate ( 9 ) is covered with an insulating layer ( 10 ) having a thickness of in particular between 0.5 μm and 15 μm;    (b) said insulator layer having a thickness is covered with a photosensitive to layer (photoresist layer;  20 );    (c) the photoresist layer ( 20 ) is exposed through a mask, which changes in its gray-tone value in accordance with the course of curvature of the surface (OF) of at least one insulator profile ( 10   a ,  10   b ,  10   c ,  10   d ), and is subsequently structured to form at least one resist remainder ( 20   a ,  20   b ,  20   c ,  20   d );    (d) the structured photoresist layer ( 20   a ,  20   b ,  20   c ,  20   d ) and the insulator layer ( 10 ) are substantially planely removed by a dry-etching process, in order to transfer the at least one resist remainder—defined by the structuring—by shape into the insulator ( 10 ) and to form ( 10   a ,  10   b ,  10   c ,  10   d ) at least one insulator profile around the anode ( 1 ;  31 ).    
     
     
         7 . Component according to  claim 5 , wherein the curvature ( 32   a , r) of the hood ( 32 ), extending particularly as a quarter circle, is greater or more pronounced than the curvature of the laterally extended metallic coating ( 31   b ).  
     
     
         8 . Component according to any one of  claims 1  to  4 , wherein a transition ( 31   a ) of the curved metallic coating ( 31   b ) to the anode metallic coating ( 31 ) is provided through a small step (d) of the insulator profile at an inner end of the curved portion (KB) of the insulator profile ( 11 ), wherein said small step is in an order of magnitude of 5 nm to 30 nm so that the insulator profile does not terminate towards the anode metallic coating ( 31 ) completely free of steps.  
     
     
         9 . Component or method according to any one of the previous claims, wherein—after metallizing the curved surface (OF) of the insulator profile ( 10   a )—a wall-like casting compound ( 40 ) is deposited around the one or at least one of the plurality of insulator profiles ( 10   c ), which casting compound insulatingly overlaps the metallic coatings (MET 1 , MET 2 ) on both ends of the insulator profile ( 10   a ).  
     
     
         10 . Component according to  claim 2  or  3 , wherein below each of the plurality of insulator profiles ( 10   c ,  10   d ), which are arranged in an outwards staggered manner, a strip-shaped—ring-strip shaped for a circular anode ( 1 )—compensating area is diffused into the substrate ( 9 ) as a zone ( 7   a ,  7   b ) in order to transfer the potential present at the component at the respective location when a voltage is applied from the substrate area to the respective metallic coating ( 30   c ,  30   d ) of the respective insulator profile ( 10   c ,  10   d ), wherein the width of the strip is smaller than the width of the respective associated insulator profile and at least slightly overlaps the end of the insulator profile ( 10   b ) located further inwards.  
     
     
         11 . Component or method according to  claim 6 , wherein the curved surface of the at least one insulator profile is metallized ( 31 ), wherein the structuring according to feature (c) is effected prior thereto by developing the exposed photoresist layer ( 20 ) and is transferred into the insulator layer ( 10 ) according to feature (d).  
     
     
         12 . Component according to any one of the previous claims, comprising a substrate ( 9 ) made of silicon carbide (SiC), which has a very low diffusion constant for doting substances.  
     
     
         13 . Component according to  claim 5 , wherein an intermediate region (b 10 ) is formed between the curved portion of the hood ( 32   a ) and the laterally extended, curved metallic coating ( 31   b ), in which intermediate region the hood ( 32 ) has a substantially constant distance from the base portion ( 11 , SB).  
     
     
         14 . Component according to  claim 5  or  13 , wherein the base portion (SB) also extends below the curved hood portion ( 32   a ).