Patent Number: 
Section: claims

1. An extreme ultraviolet light generation apparatus, comprising:a chamber configured to cause a target substance to be turned into plasma with laser light radiated to a plasma generation region at an internal space of the chamber;a light concentrating mirror configured to concentrate extreme ultraviolet light generated by the turning of the target substance into plasma;a gas supply unit configured to supply gas into the chamber;a magnetic field generation unit configured to generate a magnetic field including a magnetic field axis that crosses a light path of the extreme ultraviolet light;a first exhaust port arranged at a position through which the magnetic field axis passes in the chamber;a second exhaust port arranged at a position opposite to the light concentrating mirror in the chamber with reference to a plane passing through the first exhaust port and being perpendicular to an optical axis of the light concentrating mirror; anda gas exhaust amount adjustment unit configured to adjust a ratio between an exhaust amount of first exhaust gas exhausted from the first exhaust port and an exhaust amount of second exhaust gas exhausted from the second exhaust port. 2. The extreme ultraviolet light generation apparatus according to claim 1,wherein a pair of the first exhaust ports are arranged, andthe pair of first exhaust ports are arranged at positions facing each other along the magnetic field axis in the chamber. 3. The extreme ultraviolet light generation apparatus according to claim 1,wherein the gas exhaust amount adjustment unit includes a first valve arranged in a first exhaust path between the first exhaust port and a first exhaust pump that exhausts the first exhaust gas from the first exhaust port, and a second valve arranged in a second exhaust path between the second exhaust port and a second exhaust pump that exhausts the second exhaust gas from the second exhaust port. 4. The extreme ultraviolet light generation apparatus according to claim 1,wherein the gas exhaust amount adjustment unit includes a first valve arranged in a first exhaust path, through which the first exhaust gas flows and through which flow of the second exhaust gas is suppressed, between the first exhaust port and an exhaust pump that exhausts the first exhaust gas from the first exhaust port and the second exhaust gas from the second exhaust port, and a second valve arranged in a second exhaust path, through which the second exhaust gas flows and through which flow of the first exhaust gas is suppressed, between the second exhaust port and the exhaust pump. 5. The extreme ultraviolet light generation apparatus according to claim 1,wherein the gas exhaust amount adjustment unit includes a second valve arranged in a second exhaust path, through which the second exhaust gas flows and through which flow of the first exhaust gas is suppressed, between the second exhaust port and an exhaust pump that exhausts the first exhaust gas from the first exhaust port and the second exhaust gas from the second exhaust port, andno valve is arranged in the first exhaust path, through which the first exhaust gas flows and through which flow of the second exhaust gas is suppressed, between the first exhaust port and the exhaust pump. 6. The extreme ultraviolet light generation apparatus according to claim 1,further comprising a control unit configured to control the gas exhaust amount adjustment unit to adjust the ratio based on an amount of the gas supplied into the chamber. 7. The extreme ultraviolet light generation apparatus according to claim 6,further comprising a supply gas amount adjustment unit configured to adjust an amount of the gas supplied from the gas supply unit,wherein the control unit controls the supply gas amount adjustment unit to adjust the amount of the gas supplied into the chamber based on intensity of the laser light. 8. The extreme ultraviolet light generation apparatus according to claim 7,wherein the gas supply unit includes a first gas supply unit configured to supply the gas along a reflection surface the light concentrating mirror from an outer periphery of the light concentrating mirror, and a second gas supply unit configured to supply the gas from a through hole formed in the light concentrating mirror, andthe control unit controls the supply gas amount adjustment unit to adjust an amount of the gas supplied from the second gas supply unit. 9. The extreme ultraviolet light generation apparatus according to claim 8,wherein the second gas supply unit supplies the gas in a direction away from the light concentrating mirror. 10. The extreme ultraviolet light generation apparatus according to claim 1,wherein the target substance is tin and the gas contains hydrogen. 11. An electronic device manufacturing method, comprising:generating extreme ultraviolet light using an extreme ultraviolet light generation apparatus;emitting the extreme ultraviolet light to an exposure apparatus; andexposing a photosensitive substrate to the extreme ultraviolet light in the exposure apparatus to produce an electronic device,the extreme ultraviolet light generation apparatus including:a chamber configured to cause a target substance to be turned into plasma with laser light radiated to a plasma generation region at an internal space of the chamber;a light concentrating mirror configured to concentrate the extreme ultraviolet light generated by the turning of the target substance into plasma;a gas supply unit configured to supply gas into the chamber;a magnetic field generation unit configured to generate a magnetic field including a magnetic field axis that crosses a light path of the extreme ultraviolet light;a first exhaust port arranged at a position through which the magnetic field axis passes in the chamber;a second exhaust port arranged at a position opposite to the light concentrating mirror in the chamber with reference to a plane passing through the first exhaust port and being perpendicular to an optical axis of the light concentrating mirror; anda gas exhaust amount adjustment unit configured to adjust a ratio between an exhaust amount of first exhaust gas exhausted from the first exhaust port and an exhaust amount of second exhaust gas exhausted from the second exhaust port.