Method of making symmetrically controlled implanted regions using rotational angle of the substrate

Abstract

A method of fabricating a field effect transistor, wherein impurity diffusion layers of source and drain are formed by an ion implantation method using the gate electrode as the mask by inclining the semiconductor substrate with respect to the ion beam incident direction so as to prevent the channeling effect and also rotating it in planarity with respect to the ion beam scanning plane. As a result, impurity diffusion layers can be formed symmetrically with respect to the gate electrode.

We claim: .[.1. A method of fabricating a field effect transistor comprising the steps of: 
     
        forth in claim 1, wherein m is 1..]. 3. A method of fabricating a field effect transistor comprising the steps of: forming a gate insulation film on a semiconductor substrate and forming a gate electrode on the gate insulation film;   forming a first impurity diffusion layer by first ion implantation on said semiconductor substrate using said gate electrode as the mask, by inclining the direction of an ion beam for said .Iadd.first .Iaddend.ion implantation with respect to said semiconductor substrate surface;   repeating said first ion implantation .[.step.]. by rotating said semiconductor substrate in planarity, .Iadd.wherein the number of ion implantations is 4m times (m is a positive integer), and the angle of rotation of the semiconductor substrate for each step is 90/m degree; .Iaddend.   forming an insulation film on said semiconductor substrate and the gate electrode, and partially removing said insulation film, leaving said insulation film only on the side of the gate electrode, so as to form a gate electrode insulation film side wall;   forming a second impurity diffusion layer, overlapping said first impurity diffusion layer, by second ion implantation on said semiconductor substrate using the gate electrode having said gate electrode insulation film side wall as the mask, by inclining the emission direction of an ion beam for said .Iadd.second .Iaddend.ion implantation with respect to said semiconductor substrate surface.[.; and   repeating said second ion implanting step by rotating said semiconductor   
     
     
        substrate in planarity.].. 4. A method of fabricating a field effect transistor as set forth in claim 3, further comprising a step of heat treatment after forming said second impurity layer. .[.5. A method of fabricating a field effect transistor as set forth in claim 3, wherein, when the number of said ion implantation is 2n times (n is a positive integer), the angle of rotation of said semiconductor substrate for each ion implantation is 180/n degrees..]. .[.6. A method of fabricating a field effect transistor as set forth in claim 3, wherein, the number of said ion implantations is 4m times (m is a positive integer), and the angle of rotation of the semiconductor substrate for each ion implantation is 90/m degrees..]. .[.7. A method of fabricating a field effect transistor as set forth in claim 3, wherein ions are implanted continuously while rotating the semiconductor substrate continuously..]. .[.8. A method of fabricating a field effect transistor as set forth in 
     
     
        claim 5, wherein n is 1..]. 9. A method of fabricating a field effect transistor as set forth in claim .[.6.]. .Iadd.3.Iaddend., wherein m is 1. 
     
     
        0. A method of fabrication a field effect transistor comprising the steps of: forming a buried channel layer on a semiconductor substrate, forming a gate insulation film, and forming a gate electrode on the gate insulation film;   forming a first impurity diffusion layer in the boundary region of said buried channel layer and the semiconductor substrate by implanting .Iadd.a first implantation of .Iaddend.ions in said buried channel layer using said gate electrode as the mask, by inclining the emission direction of an ion beam for said .Iadd.first .Iaddend.ion implantation with respect to said semiconductor substrate;   repeating said first ion implantation by rotating said semiconductor substrate in planarity.Iadd., wherein the number of ion implantations is 4m times (m in a positive integer), and the angle of rotation of the semiconductor substrate for each step is 90/m degrees.Iaddend.;   forming an insulation film on said buried channel layer and the gate electrode, and partially removing said insulation film, leaving said insulation film only on the side of the gate electrode, so as to form a gate electrode insulation film side wall;   forming a second impurity diffusion layer, reaching up to the .[.principal.]. .Iadd.substrate surface .Iaddend.plane of said buried channel layer on said first impurity diffusion layer by a second ion implantation in the buried channel layer using the gate electrodes having said gate electrode insulation film side wall as the mask, by inclining the direction of an ion beam for said .Iadd.second .Iaddend.ion implantation with respect to said buried channel layer surface.[.; and   repeating said second ion implantation step by rotating said semiconductor   
     
     
        substrate in planarity.].. 11. A method of fabricating a field effect transistor as set forth in claim 10, further comprising a step of heat treatment after forming said second impurity diffusion layer. .[.12. A method of fabricating a field effect transistor as set forth in claim 10, wherein, when the number of said ion implantation is 2n times (n is a positive integer), the angle of rotation of the semiconductor substrate for each ion implantation is 180/n degrees..]. .[.13. A method of fabricating a field effect transistor as set forth in claim 10, wherein, the number of said ion implantations is 4m times (m is a positive integer), and the angle of rotation of the semiconductor substrate for each ion implantation is 90/m degrees..]. .[.14. A method of fabricating a field effect transistor as set forth in claim 10, wherein ions are implanted continuously while rotating the semiconductor substrate continuously..]. .[.15. A method of fabricating a field effect transistor 
     
     
        as set forth in claim 12, wherein n is 1..]. 16. A method of fabricating a field effect transistor as set forth in claim .[.13.]. .Iadd.10.Iaddend., wherein m is 1. .[.17. A method of fabricating a field effect transistor comprising the steps of: forming a gate electrode on a semiconductor substrate by way of a gate insulation film; and   forming an impurity diffusion layer by implanting ions into said semiconductor substrate using said gate electrode as the mask, by inclining the direction of an ion beam with respect to said semiconductor substrate surface for said ion implantation,   said ion implantation being carried out continuously while said semiconductor substrate is rotated k times (k is a positive integer) in planarity, the substrate being rotated at least 360 degrees during the continuous step of implantation..]. .[.18. A method of fabricating a field   
     
     
        effect transistor as set forth in claim 17, wherein k is 1..]. .Iadd.19. A method of fabricating a field effect transistor comprising the steps of: forming a gate insulation film on a semiconductor substrate and forming a gate electrode on the gate insulation film;   forming a first impurity diffusion layer by first ion implantation on said semiconductor substrate using said gate electrode as the mask, by inclining the direction of an ion beam for said ion implantation with respect to said semiconductor substrate surface;   repeating said first ion implantation step by rotating said semiconductor substrate in planarity;   forming an insulation film on said semiconductor substrate and the gate electrode, and partially removing said insulation film, leaving said insulation film only on the side of the gate electrode, so as to form a gate electrode insulation film side wall; and   forming a second impurity diffusion layer, overlapping said first impurity diffusion layer, by second ion implantation on said semiconductor substrate using the gate electrode having said gate electrode insulation film side wall as the mask, by inclining the emission direction of an ion beam for said ion implantation with respect to said semiconductor   
     
     
        substrate surface. .Iaddend. .Iadd.20.  A method of fabricating field effect transistors as set forth in claim 3, wherein the process of forming gate electrodes on a gate insulation film comprises the steps of forming an elongated first gate electrode for a first transistor and forming an elongated second gate electrode for a second transistor with the directions of elongation of the respective gate electrodes being substantially orthogonal to each other. .Iaddend. .Iadd.21. A method of fabricating field effect transistors as set forth in claim 10, wherein the process of forming gate electrodes on a gate insulation film comprises the steps of forming an elongated first gate electrode for a first transistor and forming an elongated second electrode for a second transistor with the directions of elongation of the respective gate electrodes being 
     
     
        substantially orthogonal to each other. .Iaddend. .Iadd.22.  A method of fabricating a field effect transistor comprising the steps of: forming a buried channel layer on a semiconductor substrate, forming a gate insulation film, and forming a gate electrode on the gate insulation film;   forming a first impurity diffusion layer in the boundary region of said buried channel layer and the semiconductor substrate by a first implantation of ions in said buried channel layer using said gate electrode as the mask, by inclining the emission direction of an ion beam for said ion implantation with respect to said semiconductor substrate;   repeating said first ion implantation by rotating said semiconductor substrate in planarity;   forming an insulation film on said buried channel layer and the gate electrode, and partially removing said insulation film, leaving said insulation film only on the side of the gate electrode, so as to form a gate electrode insulation film side wall; and   forming a second impurity diffusion layer reaching up to the substrate surface plane of said buried channel layer on said first impurity diffusion layer by second ion implantation in the buried channel layer using the gate electrode having said gate electrode insulation film side wall as the mask, by inclining the direction of an ion beam for said second ion implantation with respect to said buried channel layer surface. .Iaddend.