Optical inspection method and apparatus including intensity modulation of a light beam and detection of light scattered at an inspection position

An exposure system, comprising:

• an optical inspecting device for inspecting an original having a pattern to be exposed, said inspecting device comprising (a) an optical system for modulating an intensity distribution of light to be projected to an inspection position where the inspection is to be carried out, said optical system comprising (i) light source means for generating first and second light beams being superposed one upon another and having different frequencies w1 and w2, respectively, said light source means including one of an acousto-optic device and a dual-frequency laser for emitting a dual-frequency laser beam having different frequency components corresponding to those of the two light beams, respectively, (b) a lens for substantially collecting the superposed first and second light beams at an inspection position, said lens projecting the first and second light beams onto the inspection position along the same direction, wherein, as a result of the collection of the first and second light beams, heterodyne interference at a modulation frequency .vertline.w1-w2.vertline. is produced in the neighborhood of the inspection position, and (c) detecting means, comprising a synchronism detector, for detecting scattered light, being scattered at the inspection position, having the modulation frequency .vertline.w1-w2.vertline.;
• and
• an exposure device for exposing the pattern of the original to print the pattern on a substrate.

An original cleaning and inspecting system, comprising:

• a cleaning device for cleaning an original;
• and
• an optical inspecting device for inspecting the original cleaned by said cleaning device, said inspecting device comprising (a) an optical system for modulating an intensity distribution of light to be projected to an inspection position where the inspection is to be carried out, said optical system comprising (i) light source means for generating first and second light beams being superposed one upon another and having different frequencies w1 and w2, respectively, said light source means including one of an acousto-optic device and a dual-frequency laser for emitting a dual-frequency laser beam having different frequency components corresponding to those of the two light beams, respectively, and (ii) a lens for substantially collecting the superposed first and second light beams at an inspection position, said lens projecting the first and second light beams onto the inspection position along the same direction, wherein, as a result of the collection of the first and second light beams, heterodyne interference at a modulation frequency .vertline.w1-w2.vertline. is produced in the neighborhood of the inspection position, and (b) detecting means, comprising a synchronism detector, for detecting scattered light, being scattered at the inspection position, having the modulation frequency .vertline.w1-w2.vertline..

A semiconductor device manufacturing method, comprising the steps of:

• inspecting an original having a circuit pattern, said inspecting step comprising (a) modulating an intensity distribution of light to be projected to an inspection position on the original where the inspection is to be carried out, said modulating step comprising (1) generating first and second light beams being superposed one upon another and having different frequencies w1 and w2, respectively, by using one of an acousto-optic device and a dual-frequency laser for emitting a dual-frequency laser beam having different frequency components corresponding to those of the two light beams, respectively, and (2) substantially collecting the first and second light beams, being superposed one upon another, at an inspection position by using a lens, projecting the first and second light beams, by the lens, onto the inspection position along the same direction, and producing, as a result of the collection of the first and second light beams, heterodyne interference at a modulation frequency .vertline.w1-w2.vertline., in the neighborhood of the inspection position and (b) detecting, by use of a synchronism detector, scattered light being scattered at the inspection position, having the modulation frequency .vertline.w1-w2.vertline.;
• and
• exposing the circuit pattern of the inspected original to print the pattern on a wafer.

A semiconductor device manufactured by a method which comprises the steps of:

• inspecting an original having a circuit pattern, said inspecting step comprising (a) modulating an intensity distribution of light to be projected to an inspection position on the original where the inspection is to be carried out, said modulating step comprising (1) generating first and second light beams being superposed upon one another and having different frequencies w1 and w2, respectively, by using one of an acousto-optic device and a dual-frequency laser for emitting a dual-frequency laser beam having different frequency components corresponding to those of the two light beams, respectively, and (2) substantially collecting the first and second light beams, being superposed one upon another, at an inspection position by using a lens, projecting the first and second light beams, by the lens, onto the inspection position along the same direction, and producing, as a result of the collection of the first and second light beams, heterodyne interference at a modulation frequency .vertline.w1-w2.vertline., in the neighborhood of the inspection position and (b) detecting, by use of a synchronism detector, scattered light being scattered at the inspection position, having the modulation frequency .vertline.w1-w2.vertline.;
• and
• exposing the circuit pattern of the inspected original to print the pattern on a wafer.