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Alignment device and alignment method

A technology for aligning devices and aligning marks, which is applied in the direction of photolithography exposure devices, microlithography exposure equipment, instruments, etc., can solve the problems of limiting the period and direction of silicon wafer marks, reducing alignment accuracy, etc., to avoid drift Error, the effect of improving the alignment accuracy

Active Publication Date: 2019-04-12
SHANGHAI MICRO ELECTRONICS EQUIP (GRP) CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the above scheme requires a reference grating, which limits the period and direction that can be used for silicon wafer marking, and the drift of the reference grating will also be introduced into the alignment error, which reduces the alignment accuracy. Therefore, it is necessary to invent a method that does not need to use a reference grating. Alignment device and method

Method used

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  • Alignment device and alignment method

Examples

Experimental program
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Effect test

Embodiment 1

[0043] Please refer to image 3 , the alignment device provided by the present invention includes an area array detector 500, an imaging lens 400, a dichroic prism 600, a projection system 200, and an alignment mark 310. The mark 310 is located on the silicon wafer 300. The alignment mark 310 includes two groups of gratings with different periods, namely the first grating 311 and the second grating 312. The illumination light provided by the illuminating device 100 passes through the dichroic prism 600. , the projection system 200 reaches the alignment mark 310, and diffracts through the projection system 200, the dichroic prism 600, and the imaging lens 400 to form a moiré fringe image on the area detector 500 .

[0044] The illumination device 100 provides collimated illumination light. Illumination light can be broadband light (such as 450-750nm), or light of multiple wavelengths, such as wavelengths of λ 1 , lambda 2 , lambda 3 laser. Preferably, it may also include ...

Embodiment 2

[0064] The difference between this embodiment and Embodiment 1 is that an aperture stop (not shown) is added between the dichroic prism 600 and the imaging lens 400, since the 0th-order diffracted light diffracted from the alignment mark 310 (that is, the exit angle is 0 ° diffracted light) or reflected light with a reflection angle of 0° after being incident on the alignment mark 310 will affect the formation of moiré fringes, making the moiré fringe image lighten and the definition reduced. The addition of an aperture diaphragm between 400 can block the 0th order diffracted light or the reflected light with a reflection angle of 0°, thereby reducing the influencing factors of the formation of moiré fringes and making the moiré fringes clearer.

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Abstract

Two groups of optical gratings, with tiny difference periodically, which are arranged side by side serve as alignment marks, a projection system with an optical amplification factor of -1 is arranged on the alignment marks, when lighting light is radiated on one group of optical gratings and is diffracted at a diffraction angle of theta 1, diffraction light is overturned at the angle of 180 degrees after passing through the projection system and then is reflected onto the other group of optical gratings, due to the fact that the periods of the two groups of optical gratings are similar, light rays diffracted at an extremely small diffraction angle of theta 2 (sin theta 2 is equal to sin theta 1 - sin theta 3, theta 3 is the diffusion angle of the light rays after being normally incident into the other group of optical gratings, and the difference between theta 1 and theta 3 is extremely small) from the other group of optical gratings can form moire fringes on an area array detector in sequence, the light rays are transmitted to a processing unit, the offset distance of the alignment marks is calculated, silicon wafers on a workpiece table is moved so that the alignment marks are moved, and the alignment is completed until the offset distance of the alignment marks is 0. According to the method, the moire fringes can be formed in a self-reference manner, and reference optical gratings do not need to be used, so that drift error caused by the reference optical gratings is avoided, and the alignment precision is improved.

Description

technical field [0001] The invention relates to the field of semiconductor photolithography, in particular to an alignment device and an alignment method. Background technique [0002] In the manufacturing process of semiconductor IC integrated circuits, a complete chip usually needs to undergo multiple photolithography exposures before it can be completed. Except for the first photolithography, the photolithography of other levels must be accurately positioned before exposure, so as to ensure the correct relative position between the graphics of each layer. Instant overlay accuracy. Normally, the overlay accuracy is 1 / 3 to 1 / 5 of the resolution index of the lithography machine. For a 100nm lithography machine, the overlay accuracy index is required to be less than 35nm. When the feature size CD is required to be smaller, the requirements for overlay accuracy and the resulting alignment accuracy become more stringent. For example, a 90nm CD size requires an alignment accur...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G03F7/20G03F9/00
CPCG03F7/70141G03F7/70258G03F9/7076
Inventor 周钰颖陆海亮
Owner SHANGHAI MICRO ELECTRONICS EQUIP (GRP) CO LTD