Recently, according to the official website of the State Intellectual Property Office, Huawei Technologies Co., Ltd. announced a patent related to lithography technology on November 15, with the patent application number 202110524685X.
In integrated circuit manufacturing, lithography covers the transfer, processing and formation of micro-nano graphics and determines the characteristic size of the circuit on the integrated circuit wafer and the number of transistors in the chip. It is one of the key technologies in manufacturing of integrated circuits. circuit manufacturing.
As the semiconductor process advances to 7nm and below nodes, extreme ultraviolet (extreme ultraviolet, EUV) lithography has become the lithography technology of choice.
In the related art EUV lithographic machine, when a strong coherent light source is used for lithography, the multiple sub-beams split by the coherent light through the illumination system have a fixed phase relationship. When these sub-beams are projected onto the mask and superimposed, they will form a fixed Therefore, it is necessary to perform decoherence processing (or avoid coherence effects) first to obtain a uniform light effect to ensure the normal progress of the photolithography process.
According to the disclosure, the patent application provides a mirror, a lithography device and a method of controlling the same, involving the field of optics,It can solve the problem that coherent light cannot be homogenized due to the formation of a fixed interference pattern, and is optimized on the basis of the extreme ultraviolet light lithography device to achieve the purpose of homogenization.
The lithographic apparatus comprises a coherent light source 1, a mirror 2 (also called a decoherent mirror) and an illumination system 3. In which, the reflective mirror 2 can be rotated; for example, a rotary device may be provided in the photolithography apparatus, and the reflecting mirror 2 may rotate guided by the rotary device, as shown in the following figure.
In the photolithography apparatus, after being reflected by the rotating mirror 2, the light emitted by the coherent light source 1 is split into multiple sub-beams by the illumination system 3 and projected onto the mask plate 4 for photolithography.
Furthermore, in the lithography apparatus, the above illumination system 3 is an important component and its main function is to provide highly uniform illumination (uniform light), control the exposure dose and realize off-axis illumination, etc. , in order to improve the resolution of the lithography and increase the depth of focus. The uniform light function of the lighting system 3 can be realized by a Kohler lighting structure.
The illumination system 3 comprises a field flyeye mirror 31 (field flyeye mirror, FFM), a diaphragm flyeye mirror 32 (diaphragm flyeye mirror, PFM) and a group of relay mirrors 33;
Wherein, the relay mirror assembly 33 may generally include two or more relay mirrors. The illumination system 3 divides the light beam from the coherent light source 1 into several sub-beams through the composite lens of the visual field 31, and each sub-beam is adjusted according to the direction of irradiation and the shape of the visual field through the diaphragm composite lens 32, and then adjusted via the relay lens assembly 33. After adjusting the size and/or shape of the field of view, it is projected onto the illuminated area of the reticle 4 .
By placing the reflector 2 on the optical path between the coherent light source 1 and the illumination system 3, in this case, the phase of the light emitted by the coherent light source 1 is continuously changed after being reflected by the rotating reflector 2.
In this way, when the light reflected by the mirror 2 is divided into several sub-beams by the illumination system 3 and projected onto the mask 4, the interference pattern formed in the illuminated area of the mask 4 changes constantly, so that the illumination L’ cumulative light intensity of the visual field within the exposure time is uniformed, so as to achieve the purpose of uniformity of light, and thus solve the problem in the related art that the light cannot be uniform due to the formation of a pattern of fixed interference from coherent light.
