CN101581889B - Alignment mark, alignment system and alignment method for photomask processor - Google Patents
Alignment mark, alignment system and alignment method for photomask processor Download PDFInfo
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- CN101581889B CN101581889B CN200910045415.XA CN200910045415A CN101581889B CN 101581889 B CN101581889 B CN 101581889B CN 200910045415 A CN200910045415 A CN 200910045415A CN 101581889 B CN101581889 B CN 101581889B
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- 239000003550 marker Substances 0.000 claims description 91
- 238000007639 printing Methods 0.000 claims description 71
- 238000003384 imaging method Methods 0.000 claims description 30
- 238000009826 distribution Methods 0.000 claims description 11
- 230000000737 periodic effect Effects 0.000 claims description 11
- 238000010606 normalization Methods 0.000 claims description 6
- 238000013341 scale-up Methods 0.000 claims description 5
- 238000001514 detection method Methods 0.000 claims description 3
- 230000002457 bidirectional effect Effects 0.000 abstract 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 7
- 229910052710 silicon Inorganic materials 0.000 description 7
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Abstract
The invention provides an alignment system used for a photomask processor, comprising a mask or a stencil stage on which a transmission-type mask target is carved, an optical intensity detector which is provided with a reference mark, and the like, wherein, the reference mark comprises a reference mark two-dimensional grating which is positioned in the center and is provided with a two-dimensionalstructure, and a plurality of reference mark grating structures which are arranged around the reference mark two-dimensional grating and can be used for bidirectional alignment; the transmission-type mask target comprises an alignment mark two-dimensional grating which is used for the coarse alignment with the reference mark two-dimensional grating and is provided with the two-dimensional structu re, and a plurality of alignment mark grating structures which are arranged around the alignment mark two-dimensional grating and are used for the perfect alignment with the reference mark grating structures, and therefore the alignment accuracy can be effectively improved by the coarse alignment and the perfect alignment; and as the grating comprises a light transmission part and a light-tight part, the contrast grade of an alignment signal can be increased.
Description
Technical field
The present invention relates to the technique of alignment of lithographic equipment, relate in particular to alignment mark, alignment system and alignment methods for lithographic equipment.
Background technology
Two kinds of alignment scheme of the normal employing of existing lithographic equipment, a kind of is the TTL technique of alignment that sees through camera lens, another kind is OA off-axis alignment technology.In TTL technique of alignment, first by the alignment mark on laser lighting mask, make it image in silicon chip plane, then travelling workpiece platform, make the reference marker scanning process alignment mark imaging in work stage, and by the light intensity of light intensity detector sampling imaging, when output largest light intensity, show that the reference marker in work stage overlaps with the alignment mark on mask, this is correct aligned position, and the position measurement that this aligned position is the laser interferometer that moves for monitoring workpiece platform position provides zero reference.And OA off-axis alignment technology is the reference mark that is positioned at datum plate in multiple alignment marks in work stage and work stage by off-axis alignment systematic survey, realizing silicon chip aligning and work stage aims at, aiming at by reference marker in work stage and mask alignment mark again, realize mask registration, and then again by the position relationship of mask and silicon chip, realize mask and silicon chip and aim at.
Existing reference marker and alignment mark are many to be made up of one dimension amplitude grating, and the printing opacity grating also being equated by the equal live width in many intervals forms.When reference marker and alignment mark are completely on time, two gratings overlap completely, thereby the luminous flux maximum seeing through; And when reference marker and alignment mark are less than completely on time, between two gratings, exist relative displacement poor, thereby the luminous flux seeing through will be between maximum value and minimal value.This kind utilizes reference marker scanning alignment mark to realize the method for aligning, and the contrast of its registration signal is poor, moreover, because the grating adopting is one dimension amplitude grating, be therefore only applicable to one dimension and aim at, only can realize a location in direction.
For this reason, a kind of specific coding method of two-dimension zero-position grating had once been introduced by U.S.'s " scientific instrument comment " (Review of Scientific Instruments, JULY 2003, VOLUME 74,7, the 3549 to 3553 pages of NUMBER).In this coding method, absolute zero position can be realized by zero locatino grating and other optical device common combinations.In the time of design zero-bit grid line, require grid line wide, and printing opacity grid line and the arrangement of light tight grid line, printing opacity grid line can be adjacent with printing opacity grid line, also can be adjacent with light tight grid line.Wherein, the most basic feature of zero-bit grid line is exactly that light transmission grid lines line and light tight grid line striped replace.If represent light tight grid line with " 0 ", " 1 " represents printing opacity grid line, whole zero-bit grid line sequence just can one numerical value be that 0 and 1 matrix represents.If up is the luminous flux maximal value of system output, u0 is luminous flux second maximal value of system output, D=u0/up.D is the contrast of light signal strength, and it can be used as the eigenwert of grating encoding matrix, with contrast D be minimised as target designed go out grating, can make output signal and luminous flux density obtain best effect.
Although above-mentioned coding method can be applicable to the zero locatino grating of transmission-type one peacekeeping two dimension, but because litho machine requires the size of alignment mark unsuitable excessive, otherwise can waste valuable mask resource, and adopting above-mentioned transmission-type coding zero locatino grating alignment mark, its label size is often difficult to meet the requirement of litho machine; Have again, due to said method employing is random coded system, do not consider the optical interference of actual capabilities generation and the impact of diffraction, so the precision of aligning will be affected greatly, thereby be difficult in high-end litho machine application, therefore, how to improve under the prerequisite of registration signal contrast, improving the real technical task that has become those skilled in the art's solution urgently to be resolved hurrily of alignment precision of litho machine.
Summary of the invention
The object of the present invention is to provide a kind of alignment mark for lithographic equipment, alignment system and alignment methods thereof, to realize high-contrast, high-precision aligning.
To achieve the above object, the present invention has adopted following technical scheme:
For an alignment mark for lithographic equipment, described mark comprises for the Part I structure of coarse alignment with for the Part II structure of fine alignment, and wherein, described the first and second part-structures are by printing opacity unit and light tight unit composition; Described Part II structure comprises multiple optical grating constructions, described each optical grating construction by multiple non-periodic one-dimensional grating tag arrangement form, the printing opacity unit in described one-dimensional grating mark distributes axisymmetricly.
Further, the printing opacity unit of the described Part I structure distribution that is centrosymmetric.Described Part I structure is normalization mark.Described Part II structure is used for realizing both direction and aims at.
Further, the length of each printing opacity unit in any one optical grating construction of described Part II structure equates with width, and the area of light transmission part in multiple optical grating constructions of described Part II structure equates, meets: S=Ni*LW
i* DW
i, the glazed area that wherein S is any one optical grating construction, LW
i, DW
iwith Ni be respectively the number of length, width and the printing opacity unit of printing opacity unit in a certain optical grating construction, i is random natural number.
Further, the glazed area S of any one optical grating construction of described Part II structure and the glazed area of Part I structure are proportionate relationship, meet formula: N0* (DL
0-PAS)
2=a*S, wherein, N0 and DL
0be respectively the number of printing opacity unit in Part I structure and the length of side of each printing opacity unit, PAS is prealignment precision, the scale-up factor between the glazed area S that a is optical grating construction and the glazed area of Part I structure.
The present invention also provides a kind of alignment system for lithographic equipment, in order to realize the position relationship of the first object with respect to the second object, comprise: light-source system, objective system, detection system, and be positioned at the transmission-type alignment mark of the first object and be positioned at the reference marker of the second object, wherein, described transmission-type alignment mark and reference marker comprise for the Part I structure of coarse alignment with for the Part II structure of fine alignment, and described the first and second part-structures are by printing opacity unit and light tight unit composition; Described Part II structure comprises multiple optical grating constructions, described each optical grating construction by multiple non-periodic one-dimensional grating tag arrangement form, printing opacity unit wherein distributes axisymmetricly.
Further, the light transmission part of the Part I structure of described transmission-type alignment mark and the reference marker distribution that is centrosymmetric.The Part I structure of described transmission-type alignment mark and reference marker is normalization mark.Described transmission-type alignment mark is used for realizing both direction with the Part II structure of reference marker and aims at.
Further, the length of each printing opacity unit in any one optical grating construction of described Part II structure equates with width, and the glazed area of multiple optical grating constructions of the Part II structure of described reference marker is equal, meets: S=:Ni*LW
i* DW
i, the glazed area that wherein S is any one optical grating construction, LW
i, DW
iwith Ni be respectively the number of length, width and the printing opacity unit of printing opacity unit in a certain optical grating construction, i is random natural number.
Further, the glazed area S of any one optical grating construction of described Part II structure and the glazed area of Part I structure are proportionate relationship, meet formula: N0* (DL
0-PAS)
2=a*S, wherein, N0 and DL
0be respectively the number of printing opacity unit in Part I structure and the length of side of each printing opacity unit, PAS is prealignment precision, the scale-up factor between the glazed area S that a is optical grating construction and the glazed area of Part I structure.
Further, the printing opacity unit in the Part I structure of described reference marker is that the length of side is DL
0square tiles, the distribution that is centrosymmetric of described printing opacity unit, the light tight unit in the Part I structure of described reference marker is that the length of side is DL
1square fritter; The printing opacity unit of the Part I structure of described transmission-type alignment mark is that the length of side is LL
0square tiles, the distribution that is centrosymmetric of described printing opacity unit, the light tight unit of the Part I structure of described transmission-type alignment mark is that the length of side is LL
1square fritter, wherein, LL
1=N × DL
1, LL
0=N × (DL
0-PAS), N is the convergent-divergent multiple of described projection imaging object lens, PAS is prealignment precision.
Further, the length of each printing opacity unit in any one optical grating construction of described Part II structure equates with width, and the printing opacity unit size of the optical grating construction of the Part II structure of described reference marker and transmission-type alignment mark meets following condition: LR
i=N × (LW
i+ PAS), DR
i=N × DW
i, wherein LW
iand DW
irespectively length and the width of single printing opacity unit in the optical grating construction of reference marker, LR
iand DR
irespectively length and the width of single printing opacity unit in the optical grating construction of transmission-type alignment mark, the convergent-divergent multiple that N is projection objective, PAS is prealignment precision, i is the quantity of optical grating construction in Part II structure.
The present invention also provides a kind of alignment methods for lithographic equipment, in order to realize the position relationship of the first object with respect to the second object, comprise the following steps: transmission-type alignment mark as above is set on the first object, reference marker as above is set on the second object; Utilize alignment mark to complete coarse alignment; On the basis of coarse alignment, utilize reference marker to complete fine alignment.
Further, described coarse alignment step comprises: fix the first object; Mobile the second object, utilizes in described reference marker scanning alignment mark Part I structure imaging and surveys corresponding light intensity; According to the light intensity of imaging, in conjunction with the positional information of the first object and the second object, obtain the relative position of the first object and the second object in the time of largest light intensity value.
Further, described fine alignment step comprises: fix the first object; Mobile the second object, utilizes in described reference marker scanning alignment mark in Part II structure at least one optical grating construction imaging and surveys corresponding light intensity; According to the light intensity of imaging, in conjunction with the positional information of the first object and the second object, obtain the relative position of the first object and the second object in the time of largest light intensity value.
In sum, alignment mark for lithographic equipment of the present invention, alignment system and alignment methods are by being configured for the two-dimensional grating of coarse alignment and the one-dimensional grating group for accurately aiming at, can effectively improve alignment precision, by light transmission part and lightproof part being set in reference marker and transmission-type alignment mark, can effectively improve the contrast of registration signal simultaneously.
Accompanying drawing explanation
Alignment mark for lithographic equipment of the present invention, alignment system and alignment methods thereof are provided by following embodiment and accompanying drawing.
Fig. 1 is the structural representation of the alignment system for lithographic equipment of the present invention.
Fig. 2 is the structural representation of reference marker in the alignment mark of first embodiment of the invention.
Fig. 3 is the structural representation of two-dimensional grating in reference marker.
Fig. 4 a～Fig. 4 f is the structural representation of first embodiment of the invention transmission-type alignment mark.
Fig. 5 is the structural representation of transmission-type alignment mark two-dimensional grating.
Fig. 6 is the structural representation of the reference marker of second embodiment of the invention.
The structural representation of the transmission-type alignment mark that Fig. 7 a～Fig. 7 f is second embodiment of the invention.
Fig. 8 adopts reference marker two-dimensional grating under two-dimensional scan mode, to scan the output characteristics figure that alignment mark two-dimensional grating imaging obtains.
Fig. 9 adopts reference marker grating group under one-dimensional scanning mode, to scan the output characteristics figure that alignment mark grating group imaging obtains.
Figure 10 adopts reference marker grating group under two-dimensional scan mode, to scan the output characteristics figure that alignment mark grating group imaging obtains.
Embodiment
In the following description, various embodiments of the present invention have at length been introduced.Each embodiment for convenience of explanation, is equipped with accompanying drawing with the ratio of exaggerating.Although shown accompanying drawing has been introduced the present invention in conjunction with the embodiments, should be appreciated that the present invention is not limited to described specific embodiment.On the contrary, the intent of the present invention is in the replacement, modification and the equivalence that cover in the spirit and scope of the present invention that claims limit.In addition, in the following description, in order to illustrate that how realizing the present invention has stated a large amount of details to more thoroughly understand the present invention.But, reading after present disclosure, those skilled in the art can not adopt these details to implement the present invention.In other cases, introduce in no detail known combination and device to avoid unnecessarily obscuring the present invention.
To the alignment mark for lithographic equipment of the present invention, alignment system and alignment methods thereof be described in further detail below.
Refer to Fig. 1, it is the structural representation for the alignment system of lithographic equipment.Described alignment system is for realizing the position relationship of mask and wafer.Described alignment system comprises exposure light source 1, illuminator 2, is carved with the mask 3 of transmission-type alignment mark, mask platform 4, for the transmission-type alignment mark on described mask carry out imaging projection objective 5, dispose reference marker and for the light intensity detector 6 of the light intensity of described projection objective 5 imagings of sampling and be placed with the work stage 7 of silicon chip.
Described exposure light source 1 can be DUV light source, or UV light source, and it,, except as exposure, is also used as coaxillay aligned lighting source simultaneously.Described illuminator 2 is for transmitting illuminating bundle, the pattern that it is thrown light in described mask 3 or described mask platform 4.Transmission-type alignment mark on described mask 3 is determined (being detailed later) according to the structure of described reference marker.Described projection objective 5, for the light beam after patterning being projected to silicon chip or work stage 7, is surveyed the light intensity under this transmission by light intensity detector 6.
Alignment mark of the present invention is made up of the reference marker on transmission-type alignment mark and light intensity detector 6 on mask 3.
The first embodiment
Refer to Fig. 2, its schematic diagram that is described reference marker, this reference marker comprises a reference marker two-dimensional grating and multiple reference marker optical grating construction.Described two-dimensional grating is made up of black transparent square and white light tight square, and it has two-dimensional structure in center, is normalization mark, can be the cycle or non-periodic grating.Referring to Fig. 3, is the structural representation of a two-dimensional grating again.In the present embodiment, described two-dimensional grating is rectangle, and the distribution that is centrosymmetric of each black transparent fritter, is square, and the length of side is DL
0, the light tight square tiles length of side of each white is DL
1.Described multiple optical grating construction comprises four optical grating constructions (being grating 1, grating 2, grating 3 and grating 4), and described four optical grating constructions are arranged in the surrounding of two-dimensional grating by " ten " font.Wherein, grating 3 and grating 4 are aimed at for horizontal direction (directions X), and grating 1 and grating 2 are aimed at for vertical direction (Y-direction).In the present embodiment, grating 2 and grating 4 are for catching raster unit, both have different structure (using different encoder matrixs), grating 1 can be turn 90 degrees and obtain around the dextrorotation of the center of this two-dimensional grating by grating 4, grating 3 can be turn 90 degrees and obtain around the dextrorotation of the center of two-dimensional grating by grating 2, therefore, grating 1 and grating 4 can use identical encoder matrix, and grating 2 and grating 3 also can use identical encoder matrix.Have again, grating 1, grating 2, grating 3 and grating 4 respectively all by three non-periodic one-dimensional grating mark be arranged in parallel and form, and the one-dimensional grating mark that is positioned at both sides is symmetrical about the one-dimensional grating mark in the middle of being positioned at, each one-dimensional grating mark is made up of black transparent part and white lightproof part alternative arrangement, and light transmission part is that rotational symmetry distributes, in addition, the multiple black transparent parts in three one-dimensional grating marks in any one optical grating construction all have identical length and width.In this embodiment, introduce the reference marker structure being formed by 4 optical grating constructions, based on thought of the present invention, on two aligning directions of XY, as long as wherein at least one direction has a grating and can realize this invention.
In above-mentioned reference marker, the glazed area of grating 1, grating 2, grating 3 and grating 4 equates, and becomes certain proportionate relationship with the glazed area of reference marker two-dimensional grating, supposes that the length of each printing opacity unit in the one-dimensional grating mark of grating 1 is LW
1, width is DW
1; In the one-dimensional grating mark of grating 2, the length of each printing opacity unit is LW
2, width is DW
2; In the one-dimensional grating mark of grating 3, the length of each printing opacity unit is LW
3, width is DW
3; In the one-dimensional grating mark of grating 4, the length of each printing opacity unit is LW
4, width is DW
4, meet:
S＝N1*LW
1*DW
1＝N2*LW
2*DW
2＝N3*LW
3*DW
3＝N4*LW
4*DW
4
Wherein, N1, N2, N3 and N4 are respectively the number of printing opacity unit in grating 1, grating 2, grating 3 and grating 4, the glazed area that S is each optical grating construction.
In addition between the structure of this glazed area S and two-dimensional grating and prealignment precision, also meet:
N0*(DL
0-PAS)
2＝a*S
Wherein, N0 is the number of black transparent unit in two-dimensional grating, and PAS is prealignment precision (DL
0what in fact-PAS characterized is the length of side of the light transmission part imaging of the printing opacity unit in the alignment mark two-dimensional grating in transmission-type alignment mark, explanation after holding), the scale-up factor between glazed area S and the glazed area of two-dimensional grating that a is each optical grating construction.
In view of the structure of above-mentioned reference marker, the corresponding transmission-type alignment mark being engraved on described mask 3 comprises for carrying out coarse alignment with the two-dimensional grating of described reference marker and having the alignment mark two-dimensional grating of two-dimensional structure, and around the configuration of described alignment mark two-dimensional grating, for carrying out with multiple optical grating constructions of reference marker multiple alignment mark optical grating constructions of accurately aiming at, and each alignment mark optical grating construction by multiple non-periodic one-dimensional grating mark be arranged in parallel and form.In the present embodiment, provide six kinds of different structures, as shown in Fig. 4 a～Fig. 4 f, user can be selected according to actual conditions.Wherein, transmission-type alignment mark shown in Fig. 4 a is made up of the rectangular alignment mark two-dimensional grating mediating and two the alignment mark optical grating constructions (being grating 2 ' and grating 4 ') that are symmetrically distributed in described alignment mark two-dimensional grating both sides, two optical grating constructions (being grating 3 ' and the grating 4 ') top in alignment mark two-dimensional grating and right side respectively of the transmission-type alignment mark shown in Fig. 4 b, two optical grating constructions (being grating 1 ' and the grating 4 ') below in alignment mark two-dimensional grating and right side respectively of the transmission-type alignment mark shown in Fig. 4 c, two optical grating constructions (being grating 1 ' and the grating 2 ') below in alignment mark two-dimensional grating and left side respectively of the transmission-type alignment mark shown in Fig. 4 d, two optical grating constructions (being grating 2 ' and the grating 3 ') left side in alignment mark two-dimensional grating and top respectively of the transmission-type alignment mark shown in Fig. 4 e, two optical grating constructions (being grating 1 ' and the grating 3 ') below in alignment mark two-dimensional grating and top respectively of the transmission-type alignment mark shown in Fig. 4 f.In above-mentioned six kinds of structures, alignment mark two-dimensional grating is grating non-periodic, rectangular, and be normalization mark, specifically refer to Fig. 5, this two-dimensional grating is made up of black squares fritter and the lighttight white square fritter of printing opacity, wherein, the distribution that is centrosymmetric of the black squares fritter of printing opacity, its distributing position is identical with the distributing position of black squares fritter in reference marker two-dimensional grating.If the length of side of black squares fritter is LL in alignment mark two-dimensional grating
0, the length of side of lighttight white square fritter is LL
1, have LL
1=N × DL
1, LL
0=N × (DL
0-PAS), wherein N is the convergent-divergent multiple of described projection imaging object lens, PAS is prealignment precision.
In above-mentioned transmission-type alignment mark, each alignment mark optical grating construction forms by being no less than isometric one-dimensional grating arrangement non-periodic.This one-dimensional grating also comprises black transparent part and white lightproof part, and light transmission part distributes axisymmetricly, and the length of each black transparent unit in same optical grating construction is identical with width.Each optical grating construction in six kinds of marks that the present embodiment provides all can be made up of isometric one-dimensional grating row three non-periodics, and be symmetric with one-dimensional grating row placed in the middle, also all comprise black transparent part and white lightproof part simultaneously, in the present embodiment, two optical grating constructions in transmission-type alignment mark can adopt and any two structures that optical grating construction is identical in reference marker optical grating construction, and these two alignment mark optical grating constructions are with respect to the arrangement position of alignment mark two-dimensional grating, with described any two reference marker optical grating constructions after central rotation 180 degree of reference marker two-dimensional grating, arrangement position with respect to reference marker two-dimensional grating is identical.For example, adopt with grating 2 and grating 4 and have the grating 2 ' of same structure and grating 4 ' as alignment mark optical grating construction, grating 2 and grating 4 are exactly grating 2 ' and the grating 4 ' position with respect to alignment mark two-dimensional grating with respect to the position of reference marker two-dimensional grating after central rotation 180 degree of reference marker two-dimensional grating.If the length of each printing opacity unit is LR in the one-dimensional grating mark of grating 1 '
1, width is DR
1, in the one-dimensional grating mark of grating 2 ', the length of each printing opacity unit is LR
2, width is DR
2, in the one-dimensional grating mark of grating 3 ', the length of each printing opacity unit is LR
3, width is DR
3, in the one-dimensional grating mark of grating 4 ', the length of each printing opacity unit is LR
4, width is DR
4, in alignment mark optical grating construction and reference marker optical grating construction, the size relationship of printing opacity unit meets: LR
i=N × (LW
i+ PAS), DR
i=N × DW
i, wherein N is the convergent-divergent multiple of described projection imaging object lens, PAS is prealignment precision, i=1～4.
Above-mentioned reference marker two-dimensional grating forms the Part I structure of whole alignment mark together with alignment mark two-dimensional grating, reference marker optical grating construction forms the Part II structure of whole alignment mark together with alignment mark optical grating construction, wherein, Part I structure is for coarse alignment, and Part II structure is for fine alignment.
The second embodiment
The key distinction of the present embodiment and the first embodiment is, each optical grating construction of the Part II structure of reference marker is separate, has separately different encoder matrixs.Specifically refer to Fig. 6, this reference marker comprises reference marker two-dimensional grating and multiple reference marker optical grating construction (in the present embodiment being four), the structure of two-dimensional grating can be consulted Fig. 3, and four optical grating constructions (grating 1～grating 4) are arranged in the surrounding of two-dimensional grating by " ten " font, wherein, grating 3 and grating 4 are aimed at for horizontal direction (directions X), and grating 1 and grating 2 are aimed at for vertical direction (Y-direction).What grating 1, grating 2, grating 3 and grating 4 used is different encoder matrixs, they respectively by three groups non-periodic one-dimensional grating tag arrangement form.In these four optical grating constructions, the part of white is light tight, black part printing opacity, and the distribution of printing opacity unit is axisymmetric.This reference marker can provide the aligning of orthogonal both direction (horizontal and vertical) simultaneously.
This reference marker two-dimensional grating has two kinds of scan modes: one-dimensional scanning mode (carry out separately the scanning of an X or Y-direction, single pass is only determined the aligned position of X or Y-direction) and two-dimensional scan mode (single pass is determined the aligned position of X and Y-direction simultaneously).Fig. 8 is the output characteristics obtaining under two-dimensional scan mode.
Refer to Fig. 7 a～Fig. 7 f, for corresponding with above-mentioned reference marker, be engraved in the structure that the transmission-type alignment mark on described mask 3 can be selected, similar with the first embodiment, this transmission-type alignment mark forms (in the present embodiment, being two) by alignment mark two-dimensional grating and multiple alignment mark optical grating construction, wherein, the structure of two-dimensional grating can be consulted Fig. 5, and the selection of two optical grating constructions and arrangement mode also meet: two optical grating constructions in transmission-type alignment mark can adopt with multiple reference marker optical grating constructions in any two structures that optical grating construction is identical, and these two alignment mark optical grating constructions are with respect to the arrangement position of alignment mark two-dimensional grating, with described any two reference marker optical grating constructions after central rotation 180 degree of reference marker two-dimensional grating, arrangement position with respect to reference marker two-dimensional grating is identical.For example, adopt with grating 2 and grating 4 and have the grating 2 ' of same structure and grating 4 ' as raster unit, grating 2 and grating 4 are exactly that grating 2 ' and grating 4 ' (are shown in Fig. 7 a) with respect to the position of alignment mark two-dimensional grating with respect to the position of reference marker two-dimensional grating after central rotation 180 degree of reference marker two-dimensional grating; Adopt with grating 3 and grating 4 and there is the grating 3 ' of same structure and grating 4 ' as raster unit, grating 3 and grating 4 are exactly that grating 3 ' and grating 4 ' (are shown in Fig. 7 b), by that analogy with respect to the position of alignment mark two-dimensional grating with respect to the position of reference marker two-dimensional grating after central rotation 180 degree of reference marker two-dimensional grating.
In addition, the proportional sizes relation of reference marker and transmission-type alignment mark is also corresponding with the first embodiment, i.e. the length of side DR of black squares printing opacity fritter in alignment mark two-dimensional grating
0and the length of side DR of white light tight square tiles
1, with the length of side DW of black squares printing opacity fritter in reference marker two-dimensional grating
0and the length of side DW of white light tight square tiles
1between scale relation meet: DR
0=N × (DW
0-PAS), DR
1=N × DW
1, wherein N is the convergent-divergent multiple of described projection imaging object lens, PAS is prealignment precision; The length L R of each printing opacity unit in alignment mark optical grating construction
iwith width D R
ilength L W with each printing opacity unit in corresponding reference marker optical grating construction
iwith width D W
imeet: LR
i=N × (LW
i+ PAS), DR
i=N × DW
i, wherein N is the convergent-divergent multiple of described projection imaging object lens, PAS is prealignment precision, i=1～4.
Before adopting alignment mark of the present invention to aim at, the first transmission-type alignment mark on the selected mask 3 using, for example, select transmission-type alignment mark as shown in Figure 4 b, then permanent mask platform 4, open again exposure light source 1, the transmission-type alignment mark being thrown light on described mask 3 by illuminator 2, in the silicon chip plane that transmission-type alignment mark is imaged in be placed in work stage 7 by projection objective 5 again, then make work stage 7 move, and adopt the reference marker scanning transmission formula alignment mark imaging on light intensity detector 6.In scanning process, first use reference marker two-dimensional grating to scan the alignment mark two-dimensional grating imaging in the transmission-type alignment mark of corresponding mask 3, and the largest light intensity of being sampled under transmission by light intensity detector 6, and in conjunction with the positional information of mask platform 4 and work stage 7, can obtain a coarse alignment position to realize coarse alignment.In coarse alignment process, because reference marker two-dimensional grating and alignment mark two-dimensional grating are all two dimension, therefore not only can be at every turn only determine the aligned position of a direction (X to or Y-direction), also can carry out two-dimentional scanning (be X to the scanning of Y-direction) simultaneously, so can be determined by once complete scanning the aligned position of X and Y-direction.Complete after coarse alignment, at least one the reference marker optical grating construction (catching raster unit) re-using in the reference marker on light intensity detector scans the alignment mark optical grating construction imaging in the transmission-type alignment mark on mask 3, the corresponding largest light intensity of same collection, in conjunction with the positional information of mask platform 4 and work stage 7, finally obtain accurate aligned position, i.e. the position of mask platform 4 and work stage 7 when light intensity detector detection obtains largest light intensity.
Fig. 8 to Figure 10 adopts alignment mark of the present invention to scan the output characteristics figure obtaining.Wherein, Fig. 8 adopts reference marker two-dimensional grating under the mode of two-dimensional scan, to scan the output characteristics figure that alignment mark two-dimensional grating imaging obtains.In figure, horizontal ordinate represents the position signalling of X and Y-direction, and ordinate represents light intensity signal.The position of the corresponding X of light intensity maximum and Y is required aligned position.Fig. 9 is the output characteristics figure that adopts reference marker optical grating construction one-dimensional scanning alignment mark optical grating construction imaging to obtain.In figure, horizontal ordinate represents the position signalling of X or Y-direction, and ordinate represents light intensity signal.The position of the corresponding X of light intensity maximum or Y-direction is required aligned position.Figure 10 is the output characteristics figure that adopts reference marker optical grating construction two-dimensional scan alignment mark optical grating construction imaging to obtain.In figure, horizontal ordinate represents the position signalling of Y and Z-direction, and ordinate represents light intensity signal.The position of the corresponding Y of light intensity maximum and Z-direction is required aligned position.
In sum, the present invention, by adopting special coding, has greatly eliminated optical interference and the impact of diffraction on alignment precision that in alignment procedures, may exist, and has controlled the size of alignment mark.This alignment mark structure resetting is good, obtains registration signal contrast high, can realize more high-precision aligning, has possessed the advantage of the high precision of one dimension alignment mark and the signal high-contrast of code-shaped mark simultaneously.Mark structure of the present invention not only can be applied to field of lithography, can also be used in the manufacture process of the accurate devices such as MEMS (micro electro mechanical system) (MEMS) device, Micro-Opto-Electro-Mechanical Systems (MOEMS) device, LCD panel LCD, realize high-precision alignment and aligning.
Claims (14)
1. for an alignment mark for lithographic equipment, described mark comprises for the Part I structure of coarse alignment with for the Part II structure of fine alignment, it is characterized in that:
Described the first and second part-structures are by printing opacity unit and light tight unit composition;
Described Part II structure comprises multiple optical grating constructions, described each optical grating construction by multiple non-periodic one-dimensional grating tag arrangement form, the printing opacity unit in described one-dimensional grating mark distributes axisymmetricly;
The length of each printing opacity unit in any one optical grating construction of described Part II structure equates with width, and the area of printing opacity unit in multiple optical grating constructions of described Part II structure equates, meets: S=Ni*LW
i* DW
i, the glazed area that wherein S is any one optical grating construction, LW
i, DW
iwith Ni be respectively the number of length, width and the printing opacity unit of printing opacity unit in a certain optical grating construction, i is random natural number;
The glazed area S of any one optical grating construction of described Part II structure and the glazed area of Part I structure are proportionate relationship, meet formula: N0* (DL
0-PAS)
2=a*S, wherein, N0 and DL
0be respectively the number of printing opacity unit in Part I structure and the length of side of each printing opacity unit, PAS is prealignment precision, the scale-up factor between the glazed area S that a is optical grating construction and the glazed area of Part I structure.
2. an alignment mark as claimed in claim 1, is characterized in that, the distribution that is centrosymmetric of the printing opacity unit of described Part I structure.
3. an alignment mark as claimed in claim 1, is characterized in that, described Part I structure is normalization mark.
4. an alignment mark as claimed in claim 1, is characterized in that, described Part I structure is rectangle.
5. an alignment mark as claimed in claim 1, is characterized in that, described Part II structure is used for realizing both direction and aims at.
6. the alignment system for lithographic equipment, in order to realize the position relationship of the first object with respect to the second object, comprise: light-source system, projection imaging object lens, detection system, and be positioned at the transmission-type alignment mark of the first object and be positioned at the reference marker of the second object, it is characterized in that: described transmission-type alignment mark and reference marker comprise for the Part I structure of coarse alignment with for the Part II structure of fine alignment, described the first and second part-structures are by printing opacity unit and light tight unit composition; Described Part II structure comprises multiple optical grating constructions, described each optical grating construction by multiple non-periodic one-dimensional grating tag arrangement form, the printing opacity unit in described one-dimensional grating mark distributes axisymmetricly;
The length of each printing opacity unit in any one optical grating construction of described Part II structure equates with width, and the glazed area of multiple optical grating constructions of the Part II structure of described reference marker is equal, meets: S=Ni*LW
i* DW
i, the glazed area that wherein S is any one optical grating construction, LW
i, DW
iwith Ni be respectively the number of length, width and the printing opacity unit of printing opacity unit in a certain optical grating construction, i is random natural number;
The glazed area S of any one optical grating construction of described Part II structure and the glazed area of Part I structure are proportionate relationship, meet formula: N0* (DL
0-PAS)
2=a*S, wherein, N0 and DL
0be respectively the number of printing opacity unit in Part I structure and the length of side of each printing opacity unit, PAS is prealignment precision, the scale-up factor between the glazed area S that a is optical grating construction and the glazed area of Part I structure.
7. an alignment system as claimed in claim 6, is characterized in that, the distribution that is centrosymmetric of the light transmission part of the Part I structure of described transmission-type alignment mark and reference marker.
8. an alignment system as claimed in claim 6, is characterized in that, the Part I structure of described transmission-type alignment mark and reference marker is normalization mark.
9. an alignment system as claimed in claim 6, is characterized in that, described transmission-type alignment mark is used for realizing both direction with the Part II structure of reference marker and aims at.
10. an alignment system as claimed in claim 6, is characterized in that, the printing opacity unit in the Part I structure of described reference marker is that the length of side is DL
0square tiles, the distribution that is centrosymmetric of described printing opacity unit, the light tight unit in the Part I structure of described reference marker is that the length of side is DL
1square fritter; The printing opacity unit of the Part I structure of described transmission-type alignment mark is that the length of side is LL
0square tiles, the distribution that is centrosymmetric of described printing opacity unit, the light tight unit of the Part I structure of described transmission-type alignment mark is that the length of side is LL
1square fritter, wherein, LL
1=N × DL
1, LL
0=N × (DL
0-PAS), N is the convergent-divergent multiple of described projection imaging object lens, PAS is prealignment precision.
11. 1 kinds of alignment systems as claimed in claim 6, it is characterized in that, the length of each printing opacity unit in any one optical grating construction of described Part II structure equates with width, and the printing opacity unit size of the optical grating construction of the Part II structure of described reference marker and transmission-type alignment mark meets following condition:
LR
i=N × (LW
i+ PAS), DR
i=N × DW
i, wherein LW
iand DW
irespectively length and the width of single printing opacity unit in the optical grating construction of reference marker, LR
iand DR
ibe respectively length and the width of single printing opacity unit in the optical grating construction of transmission-type alignment mark, N is the convergent-divergent multiple of projection imaging object lens, and PAS is prealignment precision, and i is the quantity of optical grating construction in Part II structure.
12. 1 kinds of alignment methods for lithographic equipment, in order to realize the position relationship of the first object with respect to the second object, have adopted the alignment system as described in any one in claim 6～11, comprise the following steps:
Described transmission-type alignment mark is set on the first object, described reference marker is set on the second object;
Utilize alignment mark to complete coarse alignment;
On the basis of coarse alignment, utilize reference marker to complete fine alignment.
13. alignment methods as claimed in claim 12, is characterized in that, described coarse alignment step comprises:
Fix the first object;
Mobile the second object, utilizes in described reference marker scanning alignment mark Part I structure imaging and surveys corresponding light intensity;
According to the light intensity of imaging, in conjunction with the positional information of the first object and the second object, obtain the relative position of the first object and the second object in the time of largest light intensity value.
14. alignment methods as claimed in claim 12, is characterized in that, described fine alignment step comprises:
Fix the first object;
Mobile the second object, utilizes in described reference marker scanning alignment mark in Part II structure at least one optical grating construction imaging and surveys corresponding light intensity;
According to the light intensity of imaging, in conjunction with the positional information of the first object and the second object, obtain the relative position of the first object and the second object in the time of largest light intensity value.
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|---|---|---|---|---|
| NL2005434A (en) | 2009-12-18 | 2011-06-21 | Asml Netherlands Bv | Imprint lithography. |
| CN102096349B (en) * | 2010-12-31 | 2012-05-30 | 中国科学院光电技术研究所 | Double-grating automatic alignment system for proximity nano lithography |
| CN103885283B (en) * | 2012-12-19 | 2017-06-27 | 上海微电子装备有限公司 | A kind of method for normalizing of mask registration signal |
| CN104253113B (en) * | 2013-06-28 | 2017-07-11 | 上海华虹宏力半导体制造有限公司 | The telltale mark used during a kind of measurement and its recognition methods |
| CN104678720B (en) * | 2013-12-03 | 2017-01-04 | 上海微电子装备有限公司 | Utilize the method that mask alignment system carries out work stage datum plate rotated detection |
| CN105737879A (en) * | 2016-03-01 | 2016-07-06 | 中国电子科技集团公司第十三研究所 | Micron grade raster calibration sample wafer with step height |
| KR101665569B1 (en) * | 2016-05-19 | 2016-10-12 | (주)오로스 테크놀로지 | Overlay mark, overlay measurement method and semiconductor device manufacturing method using the overlay mark |
| CN109507850B (en) * | 2018-12-19 | 2020-12-11 | 惠科股份有限公司 | Exposure parameter determination method and device and terminal equipment |
| CN115056585A (en) * | 2022-06-15 | 2022-09-16 | 云南侨通包装印刷有限公司 | Printing method of holographic true color on package |
| CN116661041B (en) * | 2023-07-28 | 2023-11-10 | 北京至格科技有限公司 | Grating positioning mark preparation method |
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Address after: 201203 Zhangjiang High Tech Park, Shanghai, Zhang Dong Road, No. 1525 Co-patentee after: Shanghai Micro And High Precision Mechine Engineering Co., Ltd. Patentee after: Shanghai microelectronics equipment (Group) Limited by Share Ltd Address before: 201203 Zhangjiang High Tech Park, Shanghai, Zhang Dong Road, No. 1525 Co-patentee before: Shanghai Micro And High Precision Mechine Engineering Co., Ltd. Patentee before: Shanghai Micro Electronics Equipment Co., Ltd. |
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