CN111580206B - Diffraction grating structure and preparation method thereof - Google Patents
Diffraction grating structure and preparation method thereof Download PDFInfo
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- CN111580206B CN111580206B CN202010594124.2A CN202010594124A CN111580206B CN 111580206 B CN111580206 B CN 111580206B CN 202010594124 A CN202010594124 A CN 202010594124A CN 111580206 B CN111580206 B CN 111580206B
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- G02B5/00—Optical elements other than lenses
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Abstract
The present disclosure provides a diffraction grating structure comprising a plurality of repeating periodic structures, each periodic structure comprising at least one grating ridge and one grating groove, wherein: each periodic structure comprises a plurality of parts from the center to the outside, each part is a gate ridge or a gate groove, and the depth of each part meets a preset condition when the part is the gate groove. On the other hand, the disclosure also provides a preparation method of the diffraction grating structure. Through reasonable arrangement of the positions and the depths of the grating grooves, the 7 th diffraction order has high diffraction efficiency, and meanwhile, the diffraction efficiency of all even diffraction orders is 0, so that the problem that the existing diffraction grating has even diffraction orders, especially high zero diffraction orders, is well solved.
Description
Technical Field
The disclosure relates to the field of semiconductors, and in particular, to a diffraction grating structure and a method for manufacturing the same.
Background
In the technical field of semiconductors, integrated circuits and precision measurement, a phase grating position sensor is often used for observing position information of a target, the phase grating is used as a measurement mark, and a diffracted light beam is generated by acting on incident light, wherein odd diffraction orders are used for generating a measurement signal, and high diffraction orders in the odd diffraction orders are used for improving measurement precision. Due to the limitation of the diffraction characteristics of the grating, the high diffraction order measurement signal is weaker, the signal to noise ratio of the measurement signal is reduced, the stability of the measurement signal is poorer, and the repeatability of position measurement is reduced. However, with the increase of the requirement of measurement accuracy, especially in the field of integrated circuits, the position measurement accuracy needs to reach the nanometer or even sub-nanometer level, and therefore, the signal-to-noise ratio of the measurement signal becomes a key factor that restricts the increase of measurement accuracy. In order to improve the signal-to-noise ratio of the measurement signal, people increase the numerical aperture to obtain more measurement information signals; or adopt annular illumination mode, etc. to reduce zero order light influence. However, since these methods require redesign of the measurement sensor, it is an effective and economical means to enhance the diffraction efficiency of odd diffraction orders to increase the intensity of the measurement signal and to reduce the diffraction efficiency of zero diffraction orders and other even diffraction orders that do not generate the measurement signal by the design of the grating. In order to enhance the diffraction efficiency of the odd diffraction orders, the integrated circuit device manufacturer proposes a grating structure AH74 with enhanced diffraction efficiency of the 7 th diffraction order by way of subdivision. Although the diffraction efficiency of the 7 th diffraction order is enhanced compared with the conventional ideal mark with the groove depth of lambda/4 and the duty ratio of 1: 1, the mark also has stronger even diffraction orders, especially stronger zero diffraction order signals, so that the contrast of the measurement signals is lower.
Disclosure of Invention
Technical problem to be solved
The invention provides a diffraction grating structure and a preparation method thereof, which better solve the problem that the existing diffraction grating has even diffraction orders, especially stronger zero diffraction orders.
(II) technical scheme
The present disclosure provides a diffraction grating structure comprising a plurality of repeating periodic structures, each periodic structure comprising at least one grating ridge and one grating groove, wherein: each periodic structure comprises a plurality of parts from the center to the outside, each part is a gate ridge or a gate groove, and the depth of each part meets a preset condition when the part is the gate groove.
Optionally, each periodic structure includes a first portion, a second portion, a third portion, and a fourth portion in sequence from the center position to the outside.
Optionally, the first portion and the third portion are gate grooves, and the second portion and the fourth portion are gate ridges; or the first part and the third part are gate ridges, and the second part and the fourth part are gate grooves.
Optionally, the width of the first portion is d/28, the width of the second portion is 6d/28, the width of the third portion is 6d/28, and the width of the fourth portion is d/28, where d is the width of the periodic structure.
Optionally, the preset conditions are:
wherein h is the depth of the gate groove, λ is the wavelength of incident light, and n is an integer.
Optionally, the width of the first portion is 5d/28, the width of the second portion is 2d/28, the width of the third portion is 2d/28, and the width of the fourth portion is 5d/28, where d is the width of the periodic structure.
Optionally, the preset conditions are:
wherein h is the depth of the gate groove, λ is the wavelength of incident light, and n is an integer.
In another aspect, the present disclosure provides a method for manufacturing a diffraction grating structure, including: s1, determining the types of the first part, the second part, the third part and the fourth part, wherein the types comprise gate ridges and gate grooves; s2, determining widths of the first portion, the second portion, the third portion, and the fourth portion; and S3, processing the grating profile according to the type and the width to obtain the diffraction grating structure.
Optionally, wherein the first portion and the third portion are gate grooves, and the second portion and the fourth portion are gate ridges; or the first part and the third part are gate ridges, and the second part and the fourth part are gate grooves.
Optionally, the width of the first portion is d/28, the width of the second portion is 6d/28, the width of the third portion is 6d/28, and the width of the fourth portion is d/28; or the width of the first part is 5d/28, the width of the second part is 2d/28, the width of the third part is 2d/28, and the width of the fourth part is 5d/28, wherein d is the width of the periodic structure.
(III) advantageous effects
The invention provides a diffraction grating structure and a preparation method thereof, wherein the position and the depth of a grating groove are reasonably set, so that the 7 th diffraction order not only has stronger diffraction efficiency, but also the diffraction efficiency of all even diffraction orders is 0, and the problem that even diffraction orders, especially stronger zero diffraction orders exist in the conventional diffraction grating is better solved.
Drawings
Fig. 1 schematically shows a schematic view of a grating structure according to a first approach of an embodiment of the present disclosure;
FIG. 2 schematically illustrates a schematic diagram of a grating structure according to a second aspect of an embodiment of the present disclosure;
figure 3 schematically illustrates a schematic diagram of an AH74 type grating structure according to an embodiment of the present disclosure;
fig. 4 schematically illustrates a process step diagram of a method of fabricating a grating structure according to an embodiment of the present disclosure.
Detailed Description
The utility model provides a diffraction grating structure, the 7 th diffraction order of this structure not only has stronger diffraction efficiency, and all even diffraction order diffraction efficiency all lack the order simultaneously, better solution exist even diffraction order especially the problem of stronger zero diffraction order among the current diffraction grating.
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to specific embodiments and the accompanying drawings.
A diffraction grating structure comprising a plurality of repeating periodic structures, each periodic structure comprising at least one grating ridge and one grating groove, wherein: each periodic structure comprises a plurality of parts from the center to the outside, each part is a gate ridge or a gate groove, and when the part is the gate groove, the depth of the part meets a preset condition.
Specifically, each periodic structure comprises four parts from the center to the outside, namely a first part, a second part, a third part and a fourth part. In the embodiment of the disclosure, the first part and the third part are gate grooves, and the second part and the fourth part are gate ridges; or the first part and the third part are gate ridges, and the second part and the fourth part are gate grooves.
In order to determine the width of each diffraction grating structure, the widths of the first portion, the second portion, the third portion, and the fourth portion must also be determined, and two schemes are disclosed in the embodiments of the present disclosure.
As shown in fig. 1, the first scheme is:
the width of the first part is d/28, the width of the second part is 6d/28, the width of the third part is 6d/28, and the width of the fourth part is d/28, wherein the sum of the widths of the first part and the second part is d/4, the sum of the widths of the third part and the fourth part is also d/4, the first part and the third part are gate grooves, and the second part and the fourth part are gate ridges; or the first part and the third part are gate ridges, and the second part and the fourth part are gate grooves. That is, the first portion and the fourth portion need to be a gate ridge and a gate groove, the second portion and the third portion need to be a gate ridge and a gate groove, the first portion and the second portion cannot be a gate ridge or a gate groove at the same time, and the third portion and the fourth portion can be a gate ridge or a gate groove at the same time. d is the width of the periodic structure. The depth of the gate groove satisfies:
wherein h is the depth of the gate groove, λ is the wavelength of incident light, and n is an integer.
Further, if the coordinate of the middle position of the periodic structure is 0, when the first portion and the third portion are gate grooves and the second portion and the fourth portion are gate ridges, the first portion, the second portion, the third portion, and the fourth portion may be further expressed by the following formulas:
when h is 0, this portion is a gate ridge.
When the first portion and the third portion are gate ridges and the second portion and the fourth portion are gate grooves, the first portion, the second portion, the third portion, and the fourth portion may be further expressed as follows:
as shown in fig. 2, the second scheme is:
the width of the first part is 5d/28, the width of the second part is 2d/28, the width of the third part is 2d/28, the width of the fourth part is 5d/28, the sum of the widths of the first part and the second part is d/4, the sum of the widths of the third part and the fourth part is d/4, the first part and the third part are gate grooves, and the second part and the fourth part are gate ridges; or the first part and the third part are gate ridges, and the second part and the fourth part are gate grooves. That is, the first portion and the fourth portion need to be a gate ridge and a gate groove, the second portion and the third portion need to be a gate ridge and a gate groove, the first portion and the second portion cannot be a gate ridge or a gate groove at the same time, and the third portion and the fourth portion can be a gate ridge or a gate groove at the same time. Where d is the width of the periodic structure. The depth of the gate groove satisfies:
wherein h is the depth of the gate groove, λ is the wavelength of incident light, and n is an integer.
Further, if the coordinate of the middle position of the periodic structure is 0, when the first portion and the third portion are gate grooves and the second portion and the fourth portion are gate ridges, the first portion, the second portion, the third portion, and the fourth portion may be further expressed by the following formulas:
when h is 0, this portion is a gate ridge.
When the first portion and the third portion are gate ridges and the second portion and the fourth portion are gate grooves, the first portion, the second portion, the third portion, and the fourth portion may be further expressed as follows:
the two structures can improve the diffraction efficiency of the 7 th diffraction order of the fine-division type, and simultaneously solve the problems that even diffraction orders exist in the conventional AH74 type diffraction grating and the zero diffraction order is strong. The structure of a conventional AH74 type diffraction grating (as shown in fig. 3) can be expressed as:
the performance of the grating structure in the present application is verified below with reference to an existing AH74 type diffraction grating. When the wavelength of incident light is 633nm, and the normal incidence grating structure AH74, the first scheme structure and the second grating structure have a groove depth of 158.25nm, a period of 16 μm, and are made of single crystal silicon, the diffraction efficiency of each diffraction order is as shown in table 1 below:
| |
0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
| AH74 | 7.0％ | 3.3％ | 0.2％ | 0.4％ | 0.3％ | 0.1％ | 1.9％ | 4.6％ | 1.0％ | 0.1％ |
| First scheme | 0.0％ | 4.4％ | 0.0％ | 7.9％ | 0.0％ | 0.4％ | 0.0％ | 2.6％ | 0.0％ | 0.1％ |
| Second embodiment | 0.0％ | 9.1％ | 0.0％ | 0.5％ | 0.0％ | 2.8％ | 0.0％ | 2.6％ | 0.0％ | 0.9％ |
TABLE 1
As can be seen from table 1, the even diffraction orders of AH74 exist, and the diffraction efficiency of the zero diffraction order reaches 7.0%, which is much greater than that of the other diffraction orders, while the even diffraction orders of the first and second schemes, both 0.0%, and the diffraction efficiency of the 7 th diffraction order, 2.6%, is less than 4.6% of AH74, but the diffraction efficiencies are also enhanced enough to measure, and the diffraction efficiencies of the 3 rd and 5 th orders of the first and second schemes are both greater than that of AH74, while the diffraction efficiency of the 9 th diffraction order, 0.9%, of the second scheme is significantly greater than 0.1% of AH 74. Therefore, the first scheme and the second scheme not only enhance the diffraction efficiency of the 7 th diffraction order, but also well solve the problem that even diffraction orders exist, especially the zero-order light is stronger, and the diffraction efficiency of the 3 rd, 5 th and 9 th diffraction orders is enhanced to a different degree compared with AH 74.
On the other hand, the present disclosure also provides a method for manufacturing a diffraction grating structure, as shown in fig. 4, including:
s1, determining the types of the first part, the second part, the third part and the fourth part, wherein the types comprise gate ridges and gate grooves; the first part and the third part are grid grooves, and the second part and the fourth part are grid ridges; or the first part and the third part are gate ridges, and the second part and the fourth part are gate grooves.
S2, determining widths of the first portion, the second portion, the third portion, and the fourth portion; the width of the first part is d/28, the width of the second part is 6d/28, the width of the third part is 6d/28, and the width of the fourth part is d/28; or the width of the first part is 5d/28, the width of the second part is 2d/28, the width of the third part is 2d/28, and the width of the fourth part is 5d/28, wherein d is the width of the periodic structure.
And S3, processing the grating profile according to the type and the width to obtain the diffraction grating structure.
In summary, the present disclosure provides a diffraction grating structure and a manufacturing method thereof, by reasonably setting the positions and depths of grating grooves, the 7 th diffraction order has a relatively high diffraction efficiency, and at the same time, the diffraction efficiencies of all even diffraction orders are 0, thereby better solving the problem that the existing diffraction grating has even diffraction orders, especially relatively high zero diffraction orders.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention, and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (2)
1. A diffraction grating structure comprising a plurality of repeating periodic structures, each periodic structure comprising at least one grating ridge and one grating groove, wherein:
each periodic structure comprises a plurality of parts from the center to the outside, each part is a grid ridge or a grid groove, and when the parts are the grid grooves, the depth of each part meets a preset condition;
each periodic structure sequentially comprises a first part, a second part, a third part and a fourth part from the center to the outside;
the first part and the third part are grid grooves, and the second part and the fourth part are grid ridges; or the first part and the third part are gate ridges, and the second part and the fourth part are gate grooves;
the width of the first part is d/28, the width of the second part is 6d/28, the width of the third part is 6d/28, the width of the fourth part is d/28, d is the width of the periodic structure, and the preset conditions are as follows:
h is the depth of the gate groove, lambda is the incident light wavelength, and n is an integer; or
The width of the first part is 5d/28, the width of the second part is 2d/28, the width of the third part is 2d/28, the width of the fourth part is 5d/28, d is the width of the periodic structure, and the preset conditions are as follows:
h is the depth of the gate trench, λ is the wavelength of incident light, and n is an integer.
2. A method of making a diffraction grating structure, comprising:
s1, determining the types of the first part, the second part, the third part and the fourth part, wherein the types comprise gate ridges and gate grooves;
s2, determining widths of the first portion, the second portion, the third portion, and the fourth portion;
s3, processing the grating profile according to the type and the width to obtain a diffraction grating structure;
the first part and the third part are grid grooves, and the second part and the fourth part are grid ridges; or the first part and the third part are grid ridges, the second part and the fourth part are grid grooves, and the depth of the grid grooves meets a preset condition;
the width of the first part is d/28, the width of the second part is 6d/28, the width of the third part is 6d/28, the width of the fourth part is d/28, d is the width of the periodic structure, and the preset conditions are as follows:
h is the depth of the gate groove, lambda is the incident light wavelength, and n is an integer;
or, the width of the first portion is 5d/28, the width of the second portion is 2d/28, the width of the third portion is 2d/28, the width of the fourth portion is 5d/28, d is the width of the periodic structure, and the preset condition is that:
h is the depth of the gate trench, λ is the wavelength of incident light, and n is an integer.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN107315211A (en) * | 2016-04-26 | 2017-11-03 | 中国科学院微电子研究所 | Reflective single diffraction order grating and its manufacture method |
| CN108204828A (en) * | 2016-12-20 | 2018-06-26 | 约翰内斯·海德汉博士有限公司 | Optical location device |
| CN110875342A (en) * | 2018-09-03 | 2020-03-10 | 三星电子株式会社 | Image sensor having grating structure therein providing enhanced diffraction of incident light |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN107315211A (en) * | 2016-04-26 | 2017-11-03 | 中国科学院微电子研究所 | Reflective single diffraction order grating and its manufacture method |
| CN108204828A (en) * | 2016-12-20 | 2018-06-26 | 约翰内斯·海德汉博士有限公司 | Optical location device |
| CN110875342A (en) * | 2018-09-03 | 2020-03-10 | 三星电子株式会社 | Image sensor having grating structure therein providing enhanced diffraction of incident light |
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