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Device and method used for overlay error measurement

An overlay error and overlay mark technology, which is applied in the field of lithography, can solve problems such as the inability to obtain overlay signals, the inability to collect evanescent waves, and the large size of overlay marks, so as to meet the requirements of measurement accuracy and the effective exposure area Small, cost-reducing effect

Active Publication Date: 2016-07-27
SHANGHAI MICRO ELECTRONICS EQUIP (GRP) CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

It can be seen from the above description that, firstly, according to its measurement principle, the size of the overlay mark is relatively large, and it is not feasible to reduce the size of the mark by using a grating with a smaller period or reducing the period number of the mark. The reasons are respectively that when the grating When the period is reduced, the high-order diffracted light may generate evanescent waves that cannot be collected, which will result in the inability to obtain overlay signals; when the period number of overlay marks is reduced to a certain number, the diffracted light of each order will no longer strictly follow the grating. Diffraction equation, the obtained diffracted light signal will not be applied to overlay calculation
Therefore, this solution cannot carry out small mark measurement overlay, let alone realize on-site measurement
Secondly, the scheme obtains overlay information by measuring the diffracted light intensity signal, and the system illumination uniformity and transmittance uniformity will affect the overlay measurement accuracy

Method used

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  • Device and method used for overlay error measurement
  • Device and method used for overlay error measurement
  • Device and method used for overlay error measurement

Examples

Experimental program
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Effect test

Embodiment 1

[0040] Such as figure 2 As shown, the device for overlay error detection of this embodiment includes the following components:

[0041] The light source 41 is used to generate measurement light. Specifically, the light source 41 may be a white light source, a broadband light source or a composite light source composed of several discrete spectral lines. Among them, the white light source can use Xe light source, etc.; the broadband refers to the generation of light including ultraviolet, visible and infrared bands or the combination of the above bands; the composite light source can be obtained by mixing several lasers with different wavelengths.

[0042] The illumination system is used to inject measurement light into the objective lens 410 . Specifically, the illumination system sequentially includes along the direction of light propagation: a collimating beam mirror 42 for collimating the measuring light, a filter 43 for generating monochromatic light, a polarizer 44 for...

Embodiment 2

[0067] Such as Figure 11 As shown, in this embodiment, the polarizer 44 is removed on the basis of embodiment 1, and the remaining parts are the same, that is, the polarizer is not necessarily necessary, and the difference between the above two different aperture stops 45 can be obtained in the case of no polarizer. Overlay signal, and then calculate the overlay error.

[0068] Compared with the prior art, the present invention has the following advantages:

[0069] 1. The present invention uses the position information of diffracted light to measure the overlay error, and the measurement signal is not affected by the uniformity of illumination, uniformity of transmittance, etc.;

[0070] 2. The size of the measurement mark is smaller and the effective exposure area occupied is smaller, thereby reducing the cost of overlay marking and the impact on chip manufacturing;

[0071] 3. Due to the use of small-sized measurement marks, the present invention can be distinguished fro...

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Abstract

The invention discloses a device and a method used for overlay error measurement. The device comprises a light source used for generating measurement lights; an illumination system for enabling the measurement lights to enter an objective lens; the objective lens used for enabling the measurement lights to radiate overlay marks, collecting each primary great diffraction light diffracted by each overlay mark and converging each primary great diffraction light to a pupil plane of the objective lens; and a detector located at the pupil plane of the objective lens and used for detecting the position of each primary great diffraction light at the detector so as to obtain an overlay error. As measurement of the overlay error is carried out by adopting the position information of the diffraction lights, a measurement signal is not affected by illumination uniformity and transmittance uniformity; a measurement mark is small in size, the periodicity is less than 20, and an occupied effective exposure region is small, so that the cost of each overlay mark is reduced; in-field measurement can be realized, and higher requirements of a node for the measurement precision of the overlay error are satisfied.

Description

technical field [0001] The invention relates to the technical field of photolithography, in particular to a device and method for overlay error detection. Background technique [0002] As the lithography pattern CD size enters the process node of 22nm and below, especially the wide application of double patterning (DoublePatterning) technology, the measurement accuracy requirements for the lithography process parameter overlay (overlay) have entered the sub-nanometer field. Due to the limitation of imaging resolution limit, the traditional overlay measurement technology based on imaging and image recognition (English full name: Imaging-Based overlay, abbreviation: IBO) has gradually been unable to meet the requirements of new process nodes for overlay measurement. The overlay measurement technique based on diffracted light detection (English full name: Diffraction-Based overlay, abbreviation: DBO) is gradually becoming the main means of overlay measurement. At present, the ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G03F7/20
Inventor 彭博方陆海亮王帆
Owner SHANGHAI MICRO ELECTRONICS EQUIP (GRP) CO LTD
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