Alignment error measuring method and device
A technology of alignment error and measurement method, which is applied in the field of optics, can solve problems such as high sampling density and affecting measurement accuracy, and achieve the effect of measuring objects directly, improving measurement accuracy and measurement accuracy, and ensuring accuracy
Active Publication Date: 2020-02-21
INST OF MICROELECTRONICS CHINESE ACAD OF SCI
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Problems solved by technology
Since the spot size at the diffraction order pupil is much smaller than the size of the entire pupil, the sampling density is very high when measuring wave aberration, otherwise the measurement accuracy will be affected
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[0034] In order to make the purpose, technical solutions and advantages of the present disclosure clearer, the present disclosure will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.
[0035] figure 1 A flow chart of the alignment error measurement method provided by the embodiment of the present disclosure is schematically shown.
[0036] refer to figure 1 , combined with figure 2 and image 3 ,right figure 1 The method shown is described in detail. like figure 1 As shown, the alignment error measuring method includes operation S110-operation S140.
[0037] S110, separately screen the diffracted beams of more than one diffraction order generated by the alignment mark at each preset position, and obtain the diffracted beams of +n diffraction order and the diffracted beam of -n diffraction order at each preset position , the number of preset positions is four or more.
[0038] In the embodim...
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The invention provides an alignment error measurement method. The method comprises the steps that more than one diffraction beam of diffraction order generated by the alignment mark at each preset position is separately screened to acquire a diffraction beam of +n diffraction order and a diffraction beam of -n diffraction order at each preset position, wherein the number of preset positions is four or more; the diffraction beam of +n diffraction order and the diffraction beam of -n diffraction order at each preset position are interfered respectively to encode phase changes introduced by alignment mark structure changes and wave aberrations into generated interference signals; the light intensity distribution of the interference signal at each preset position is detected separately; and alignment errors introduced by alignment mark structural changes and wave aberrations are calculated based on the light intensity distribution of the interference signals at four or more preset positions. The invention further provides an alignment error measurement device.
Description
technical field [0001] The present disclosure relates to the field of optics, and in particular, to a method and device for measuring alignment errors. Background technique [0002] According to the extreme ultraviolet lithography technology roadmap, as the critical dimension (CD) enters the process node of 7nm and below, the overlay accuracy requirement is less than 2nm. The alignment sensor is used to measure the relative positional relationship between the silicon wafer and the mask, which is a prerequisite for overlaying. The accuracy requirement is generally 1 / 3 to 1 / 5 of the overlay accuracy, so the accuracy of the alignment sensor should reach sub-nanometer order of magnitude. In the alignment sensor, the structure of the phase grating mark changes due to the influence of etching, deposition, chemical mechanical polishing and temperature changes during the processing and subsequent processing of the phase grating mark. The influence of phase grating alignment table ...
Claims
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Login to View More IPC IPC(8): G03F9/00
CPCG03F9/7088
Inventor 李璟杨光华齐月静陈进新卢增雄折昌美
Owner INST OF MICROELECTRONICS CHINESE ACAD OF SCI