High voltage shielding arrangement of a charged particle lithography system

1. A projection lens ( 5 ) for use in a charged particle system, said projection lens comprising:

a first metal part ( 36 ) in the form of a projection lens housing of said projection lens, having an outer wall to be set at an electrical potential;

a lens stack ( 35 );

a substantially thin second metal part ( 39 ) in electrical contact with said lens stack ( 35 );

said second metal part ( 39 ) included in said projection lens ( 5 ) and to be set at an electrical potential that is lower than the electric potential of the first metal part ( 36 );

said second metal part ( 39 ) positioned at a distance to said first metal part ( 36 ) and comprising one or more edge parts;

said distance between said first and second metal parts defining a discharge region in which an electric field is present;

said projection lens further comprising an insulator ( 40 );

said discharge region being arranged in the plane of the second metal part ( 39 ), wherein said one or more edge parts facing the discharge region are encapsulated by the insulator ( 40 ), and the second metal part ( 39 ) being included as a conductive coating.

2. A projection lens ( 5 ) according to claim 1 , further comprising

an insulating carrier ( 37 ) provided with a conductive coating ( 38 ) on the outer edge thereof, which conductive coating ( 38 ) is in contact with the projection lens housing ( 36 ),

wherein said second metal part ( 39 ) is included as a circular conductive coating on a central part of the insulating carrier ( 37 ), and

wherein the insulator ( 40 ) is included as a ring placed on and fully covering the outer edge of the second metal part ( 39 ).

3. A charged particle lithography system for projecting an image onto a target, said system comprising an electron optical column ( 4 ), said electron optical column comprising:

a projection lens ( 5 ) comprising a projection lens stack ( 35 ); and

a high voltage shielding arrangement comprising

a first metal part ( 36 ) forming a projection lens housing of said projection lens, wherein said first metal part is to be set at a first electrical potential,

a substantially thin second metal part ( 39 ) to be set at a second electrical potential causing a relatively negative charge with respect to the first metal part ( 36 ), said second metal part being arranged within said projection lens housing and comprising one or more edge parts;

wherein said second metal part ( 39 ) is positioned at a distance to said first metal part ( 36 ) defining a discharge region in which an electric field is present;

wherein in said high voltage shielding arrangement further comprises an electrical insulator, wherein said discharge region is arranged in the plane of the second metal part ( 39 ), wherein said one or more edge parts facing the discharge region are encapsulated by said insulator ( 40 ), and wherein the second metal part ( 39 ) is included as a conductive coating.

4. A charged particle lithography system according to claim 3 , wherein said projection lens ( 5 ) comprises a system of either electrostatic or electromagnetic projection lenses.

5. A charged particle lithography system according to claim 3 , wherein the relative electric potential difference between the first and second metal parts is in the range of 1 kV to 10 kV.

6. A charged particle lithography system according to claim 3 , wherein the electric field strength in the discharge area is in the range of 10 kV/mm to 30 kV/mm.

7. A charged particle lithography system according to claim 3 , wherein the high voltage shielding arrangement prevents electric breakdown and/or electron creep.

8. A charged particle lithography system according to claim 3 , wherein the first metal part is set at ground potential.

9. A charged particle lithography system according to claim 3 , further comprising an insulating top cover ( 34 ), wherein said projection lens housing and said top cover enclose the complete projection lens arrangement.

10. A charged particle lithography system according to claim 3 , further comprising:

a circular insulating carrier ( 37 ) provided with a conductive coating ( 38 ) on the outer edge thereof, which conductive coating ( 38 ) is in contact with the projection lens housing ( 36 ),

wherein said second metal part ( 39 ) is included as a circular conductive coating on a central part of the circular insulating carrier ( 37 ).

11. A charged particle lithography system according to claim 3 , wherein said second metal part ( 39 ) is in electrical contact with said lens stack ( 35 ).

12. A charged particle lithography system according to claim 3 , wherein the insulator ( 40 ) is included as a ring placed on and fully covering the outer edge of the second metal part ( 39 ).