Method of manufacturing trench mosfet using three masks process having tilt- angle source implants

Abstract

In according with the present invention, a semiconductor device is formed as follows. A contact insulation layer is deposited on the top surface of said silicon layer. A contact mask is applied and following with a dry oxide etching to remove the contact insulation layer from contact open areas. The silicon layer is tilt-angle implanted with a source dopant through the contact open areas and the source dopant is diffused to form source regions, thereby a source mask is saved. A dry silicon etch is carried out to form trenched source-body contacts in the contact open areas, penetrating through the source regions and extending into the body regions.

1 . A method of forming a semiconductor device comprising a plurality of trenched gates surrounded by source regions of a first conductivity type near a top surface of a silicon layer of said first conductivity type encompassed in body regions of a second conductivity type, said method comprising:
 depositing a contact insulation layer on the top surface of said silicon layer;   applying a contact mask and following with a dry oxide etching to remove said contact insulation layer from contact open areas;   performing multiple angle source implants into said silicon layer with a source dopant of said first conductivity type through said contact open areas and diffusing said source dopant to form said source regions in said contact open areas, thereby a source mask is saved; and   carrying out a dry silicon etch to form trenched source-body contacts and trenched gate contacts in said contact open areas, wherein said trenched source-body contacts penetrating through said source regions and extending into said body regions.   
     
     
         2 . The method of  claim 1 , further comprising, after formation of said trenched source-body contacts, a body contact ion implant is carried out and activated by RTA or furnace to form body contact regions of said second conductivity type at least around bottoms of said trenched source-body contacts, having doping concentration higher than said body region. 
     
     
         3 . The method of  claim 1 , wherein said trenched source-body contacts and said trenched gate contacts are filled with Ti/TiN/W or Co/TiN/W metal plugs connecting with a resistance-reduction layer of Ti or Ti/TiN underneath a source metal of Al alloys. 
     
     
         4 . The method of  claim 1 , wherein said multiple angle source implants comprises at least two tilt-angle source implants having a tilt-angle in the range of 5 to 30 degrees with respect to a perpendicular direction to the top surface of said silicon layer. 
     
     
         5 . The method of  claim 4 , wherein said multiple angle source implants further comprises a source implant with zero degree with respect to a perpendicular direction to the top surface of said silicon layer. 
     
     
         6 . A method for manufacturing a trench MOSFET comprising the steps of:
 growing an epitaxial layer of a first conductivity type upon a heavily doped substrate of a first conductivity type;   applying a trench mask and forming a plurality of first gate trenches in active area, and at least a second gate trench having wider gate trench than said first gate trenches in gate runner metal area, and multiple third gate trenches in termination area;   growing a sacrificial oxide layer onto inner surface of the all the gate trenches to remove the plasma damage;   removing said sacrificial oxide and growing or depositing a first insulation layer along said inner surface of said first, second and third gate trenches as a gate oxide;   depositing a doped poly of said first conductivity type into said first, second and third gate trenches and etching back said doped poly to form a plurality of first trenched gates in active area, at least a wider second trenched gate for gate connection and multiple third trenched gates in termination area;   implanting said epitaxial layer with a body dopant of a second conductivity type and diffusing said body dopant to form body regions without using a body mask;   depositing a second insulation layer functioning as a contact insulation layer on the top surface of the epitaxial layer and said first, second and third trenched gates;   applying a contact mask and dry oxide etching to remove said oxide interlayer from contact open areas;   performing multiple angle source implants into said epitaxial layer with a source dopant of said first conductivity type through contact open areas and diffusing said source dopant to form source regions;   forming a plurality of trenched source-body contacts extending into body regions and at least a trenched gate contact extending into doped poly in said second trenched gate by dry silicon and poly etches through said contact open areas, respectively and simultaneously; and   ion implanting said trenched source-body contact with a contact dopant of said second conductivity type through said contact open areas, and activating said contact dopant by RTA or furnace to form body contact regions around at least bottom of said trenched source-body contacts.   
     
     
         7 . The method of  claim 6  further comprising depositing W material filling said trenched source-body contacts and said trenched gate contact and etching back to form W plugs. 
     
     
         8 . The method of  claim 6  wherein said multiple angle source implants comprise at least two tilt-angle source implants having a tilt-angle in the range of 5 to 30 degrees, with respect to a perpendicular direction to the top surface of said epitaxial layer. 
     
     
         9 . The method of  claim 8 , wherein said multiple angle source implants further comprises a source implant with zero degree with respect to a perpendicular direction to the top surface of said silicon layer. 
     
     
         10 . A semiconductor device formed by the method of  claim 1 . 
     
     
         11 . A trench MOSFET formed by the method of  claim 6 .