CN113138545A - Exposure method and defocus measurement method - Google Patents
Exposure method and defocus measurement method Download PDFInfo
- Publication number
- CN113138545A CN113138545A CN202010065822.3A CN202010065822A CN113138545A CN 113138545 A CN113138545 A CN 113138545A CN 202010065822 A CN202010065822 A CN 202010065822A CN 113138545 A CN113138545 A CN 113138545A
- Authority
- CN
- China
- Prior art keywords
- mark
- overlay
- photoresist layer
- exposure
- area
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F9/00—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically
- G03F9/70—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically for microlithography
- G03F9/7088—Alignment mark detection, e.g. TTR, TTL, off-axis detection, array detector, video detection
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/70483—Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
- G03F7/70591—Testing optical components
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F9/00—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically
- G03F9/70—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically for microlithography
- G03F9/7003—Alignment type or strategy, e.g. leveling, global alignment
Abstract
The invention provides an exposure method and a defocus amount measuring method, wherein the exposure method comprises the following steps: partitioning a mask plate into a graph area and an out-of-focus mark area, wherein the out-of-focus mark area is positioned at the edge of the graph area; and arranging a diaphragm above the mask plate, asymmetrically illuminating the side wall of the photoresist layer by the light penetrating through the defocusing mark area through the diaphragm, symmetrically illuminating the exposure area of the photoresist by the light penetrating through the pattern area, and further completing the exposure of the photoresist layer. By adopting the exposure method provided by the invention, the side wall of the photoresist is asymmetrically illuminated, so that the exposure of an exposure area is not influenced, and the measurement error of the defocus can be reduced, the measurement precision is improved, and the measurement repeatability is reduced when the defocus measurement is carried out after the exposure; in addition, by adopting the exposure method provided by the invention, the mask plate does not need to be designed with a comb-shaped mask, so that the mask design and manufacturing cost can be reduced.
Description
Technical Field
The invention relates to the technical field of semiconductor processing and manufacturing, in particular to an exposure method and a defocus measurement method.
Background
The integrated photoetching is used for photoetching process design and photoetching process control, the process of the integrated photoetching is shown in figure 1, a silicon wafer exposed by a photoetching machine enters measuring equipment to be sleeved, the width of a line and the exposure defocus are measured, the measuring equipment sends measuring data to a computing server after the test is finished, and the computing server computes compensation data of the photoetching machine according to the measuring data.
The exposure defocus measurement function is an important function of the metrology equipment, and the defocus measurement scheme based on the exposure of the comb mask is the mainstream scheme, and the implementation manner is as shown in fig. 2, the comb structure of the comb mask is smaller than the resolution (about 20 nm), and cannot be exposed out of an image, but causes asymmetry to the side wall of the photoresist. The magnitude of the asymmetry is related to the defocus amount at the time of exposure. The asymmetry of the side wall of the photoresist can cause the difference of the diffraction efficiency of +1 order light and-1 order light during scattering measurement, so that the relationship between the defocusing amount and the asymmetry of the diffraction efficiency of the +1 order light and the-1 order light can be established, and the exposure defocusing amount can be calculated according to the asymmetry of the +1 order light and the-1 order light.
In fig. 3, a cross-sectional view of the photoresist is shown when the mark design parameters are optimized for a particular exposure system and photoresist parameters, and it can be seen that the sidewall of the photoresist does not exhibit a significant linear relationship with defocus.
FIG. 4 is a graph showing the relationship between the asymmetry of +1 order light and the defocus amount, and it can be seen that, in the defocus range of 100nm to-100 nm, the asymmetry of +1 order and-1 order diffracted light and the defocus amount do not present a good linear relationship, the slope of linear fitting is 2e-4, and the slope is relatively small, which indicates that the asymmetry of +1 order light and 1 order light is insensitive to the defocus change, which results in poor repeatability and precision of defocus amount measurement. Error analysis shows that this approach results in defocus measurement repeatability above 5nm in general.
In addition, in the prior art, in order to reduce the defocus measurement error, the +1 st order light-1 st order light needs to be sensitive to the change of defocus, i.e. the slope of the straight line in fig. 3 is increased, which is usually achieved by designing and optimizing the comb mask mark, but this inevitably increases the mask design and manufacturing cost.
Disclosure of Invention
The invention aims to provide an exposure method and a defocus measurement method, which are used for solving the problems of high defocus measurement repeatability, poor precision and high mask design and manufacturing cost in the prior art.
To solve the above technical problem, the present invention provides an exposure method, comprising:
partitioning a mask plate into a graph area and an out-of-focus mark area, wherein the out-of-focus mark area is positioned at the edge of the graph area;
and arranging a diaphragm above the mask plate, and realizing asymmetric illumination on the side wall of the photoresist layer by the light penetrating through the defocusing mark area and symmetric illumination on an exposure area of the photoresist by the light penetrating through the graphic area through the diaphragm so as to complete exposure of the photoresist layer.
Optionally, in the exposure method, the graphic area is rectangular, the defocus mark area includes a first mark area and a second mark area, and the first mark area and the second mark area are both rectangular and located on opposite sides of the graphic area.
The invention also provides a defocus measurement method, which comprises the following steps:
completing exposure on the target photoresist layer by using the exposure method;
and calculating the asymmetry of the +1 level light and the-1 level light which are diffracted on the target photoresist layer, and calculating the exposure defocusing amount according to the calculation result and the relationship between the asymmetry of the +1 level light and the-1 level light and the defocusing amount.
Optionally, in the defocus amount measuring method, a relationship between asymmetry of the +1 level light and the defocus amount is a linear relationship, and the method for obtaining the linear relationship includes:
under different defocus amounts, after a test photoresist layer is exposed by the exposure method, the asymmetry of + 1-order light and-1-order light which are diffracted on the test photoresist layer is calculated, and the calculation result is normalized to obtain the linear relation.
Optionally, in the defocus amount measuring method, the method for measuring the asymmetry of +1 order light and-1 order light diffracted on the target photoresist layer includes:
comparing the signal intensity of the + 1-order light and the-1-order light according to the + 1-order diffraction spectrum and the-1-order diffraction spectrum which are respectively obtained at the same position of the illumination pupil;
and obtaining the asymmetry of the +1 level light and the-1 level light which are diffracted on the target photoresist layer according to the difference of the signal intensities.
The invention also provides another defocus measurement method, which comprises the following steps:
sequentially arranging a first alignment mark and a second alignment mark on a substrate for bearing a target photoresist layer and the target photoresist layer, wherein the first alignment mark and the second alignment mark are coaxially arranged;
completing exposure on the target photoresist layer by using the exposure method;
and calculating the overlay errors of the first overlay mark and the second overlay mark, and calculating the defocus amount according to the calculation result and the relationship between the overlay errors and the defocus amount.
Optionally, in the another defocus measurement method, the method for establishing the relationship between the overlay error and the defocus amount includes:
sequentially arranging the first overlay mark and the second overlay mark on a substrate for bearing a test photoresist layer and the test photoresist layer;
under different defocusing amounts, after the exposure method is respectively utilized to expose the test photoresist layer, the overlay errors of the first overlay mark and the second overlay mark are measured, and then the relationship between the overlay errors and the defocusing amounts is established according to the different defocusing amounts and the overlay errors corresponding to the different defocusing amounts.
Optionally, in the another defocus measurement method, the first overlay mark includes a first sub-overlay mark and a second sub-overlay mark, and after the first overlay mark is disposed on a substrate, positions of two side walls of a photoresist layer formed on the substrate on which the first overlay mark is formed respectively correspond to positions of the first sub-overlay mark and the second sub-overlay mark.
Optionally, in the another defocus amount measuring method, the method for calculating the overlay error of the first overlay mark and the second overlay mark includes:
calculating asymmetry of +1 order light and-1 order light diffracted on the first overlay mark and the second overlay mark, respectively;
and calculating the overlay errors of the first overlay mark and the second overlay mark according to the asymmetry of + 1-level light and-1-level light which are diffracted on the first overlay mark and the second overlay mark.
Optionally, in the another defocus measurement method, the first overlay mark and the second overlay mark are gratings with the same period.
In summary, the present invention provides an exposure method, which includes: partitioning a mask plate into a graph area and an out-of-focus mark area, wherein the out-of-focus mark area is positioned at the edge of the graph area; and arranging a diaphragm above the mask plate, asymmetrically illuminating the side wall of the photoresist layer by the light penetrating through the defocusing mark area through the diaphragm, symmetrically illuminating the exposure area of the photoresist by the light penetrating through the pattern area, and further completing the exposure of the photoresist layer. The method comprises the following steps that pupil partial shading is carried out on an edge view field in an exposure light path, so that asymmetric illumination is carried out on the side wall of a photoresist layer, the side wall of the photoresist layer presents good asymmetry, and the asymmetry of +1 level light and 1 level light is sensitive to the change of defocus, so that the defocus measurement error can be reduced, the defocus measurement precision can be improved, and the measurement repeatability can be reduced when defocus measurement is carried out after exposure while exposure of an exposure area is not influenced; in addition, by adopting the exposure method provided by the invention, the mask plate does not need to be designed with a comb-shaped mask, so that the mask design and manufacturing cost can be reduced.
The invention also provides a defocus amount measuring method, which comprises the following steps: the exposure method provided by the invention is utilized to complete exposure on the target photoresist layer, the asymmetry of +1 level light and-1 level light which are diffracted on the target photoresist layer is calculated, and the exposure defocusing amount is calculated according to the measurement result and the linear relation between the asymmetry of the +1 level light and the-1 level light and the defocusing amount. After the exposure method provided by the invention is adopted to expose the photoresist layer, the asymmetry of the +1 level light and the-1 level light which are diffracted on the photoresist layer and the defocus amount basically form a linear relation, and under the same exposure system and photoresist parameters, compared with the prior art, the linear slope is increased, so that when the defocus amount is calculated by measuring the asymmetry of the +1 level light and the-1 level light which are diffracted, the defocus measurement repeatability is reduced compared with the prior art.
The invention also provides another defocus amount measuring method, which comprises the following steps: the exposure method provided by the invention is utilized to complete the exposure of the target photoresist layer, the overlay errors of the first overlay mark and the second overlay mark on the substrate for bearing the target photoresist layer are measured, and the defocus value is calculated according to the measurement result and the relationship between the overlay error and the defocus value. After the exposure method provided by the invention is used for exposing a target photoresist layer, the horizontal position of the photoresist layer can be changed, so that the overlay is changed, and the overlay error and the defocusing amount basically have a direct proportional relation.
Drawings
FIG. 1 is a schematic diagram of integrated lithography;
FIG. 2 is a schematic diagram of scattering-based defocus measurements;
FIG. 3 is a cross-sectional view of a photoresist layer after exposure to different defocus amounts using a comb mask;
FIG. 4 is a graph showing the relationship between the asymmetry of normalized + 1-level light and the asymmetry of-1-level light obtained by exposing a photoresist layer through a comb mask at different defocus amounts;
FIG. 5 is a flowchart of an exposure method according to an embodiment of the present invention;
FIG. 6 is a schematic view of an exposure system of a lithography machine;
FIGS. 7 and 8 are sectional views of a mask plate in an embodiment of the present invention;
fig. 9 is a schematic view of exposure performed by the exposure method provided by the embodiment of the invention;
FIGS. 10-15 are schematic views of the shape of the pupil as seen at various positions;
FIG. 16 is a schematic diagram showing the variation of the horizontal position of the lines of the photoresist layer with defocus according to the exposure method provided by the embodiment of the present invention;
FIG. 17 is a flowchart of a defocus measurement method according to an embodiment of the present invention;
FIG. 18 is a schematic diagram illustrating a linear relationship between the asymmetry of the normalized + 1-level light and the-1-level light and the defocus amount obtained by exposure under different defocus amounts by the exposure method provided by the embodiment of the present invention;
FIG. 19 is a schematic diagram of the second embodiment of the present invention in which the overlay error varies with defocus;
fig. 20 is a flowchart of a defocus measurement method according to a second embodiment of the present invention;
FIG. 21 is a schematic view of a set mark according to a second embodiment of the present invention;
wherein the reference numerals are as follows:
11-an illumination pupil; 12-a fourier lens; 13-a mask stage; 141-objective lens entrance end; 142-objective exit end; 143-imaging pupil; 101-a mask plate; 102-silicon wafer side/photoresist layer; 101 a-a first mark region; 101 b-a second mark region; 101 c-graphics area; 15-a diaphragm; 103-a substrate; 104 — a first overlay mark; 105-a second overlay mark; 104 a-a first sub-overlay mark; 104 b-a second sub-overlay mark; 105 a-a third sub-overlay mark; 105 b-fourth sub-overlay mark.
Detailed Description
The exposure method and defocus measurement method proposed by the present invention are further described in detail below with reference to the drawings and specific examples. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention. Further, the structures illustrated in the drawings are often part of actual structures. In particular, the drawings may have different emphasis points and may sometimes be scaled differently.
[ EXAMPLES one ]
First, as shown in fig. 5, an embodiment of the present invention provides an exposure method, including:
s11, partitioning the mask plate into a graph area and an out-of-focus mark area, wherein the out-of-focus mark area is located at the edge of the graph area;
s12, arranging a diaphragm above the mask plate, and enabling the light penetrating through the defocusing mark area to realize asymmetric illumination on the side wall of the photoresist layer and the light penetrating through the graphic area to realize symmetric illumination on the exposure area of the photoresist layer through the diaphragm, thereby completing the exposure of the photoresist layer.
The above steps are described below with reference to FIGS. 6 to 15.
As shown in fig. 6, an optical schematic diagram of an existing exposure system of a lithography machine is shown, the exposure system of the lithography machine includes an illumination light source (only an illumination pupil 11 is labeled in the figure), a fourier lens 12, a mask stage 13 and an objective lens, which are sequentially arranged along an optical path direction, the objective lens includes an objective lens entrance end 141 and an objective lens exit end 142, and an imaging pupil 143 is formed between the objective lens entrance end 141 and the objective lens exit end 142. The light on the illumination pupil 11 passes through the Fourier lens 12 and then uniformly illuminates the mask plate 101 on the mask bearing table 13, the light is diffracted after passing through the mask pattern, and the objective lens 14 collects + 1-level light, -1-level light and 0-level light and then coherently images on the silicon wafer surface (a photoresist layer on a silicon wafer) 102, so that the mask pattern is copied on the silicon wafer surface 102. The exposure system adopts Kohler illumination, the illumination pupil 11 and the mask surface are in Fourier transform relation, the angular distribution on the illumination pupil 11 determines the size of the illumination area of the mask plate 101, and light emitted from all positions on the illumination pupil 11 is converged on the mask plate 101.
Based on the above lithography machine exposure system, in the embodiment of the present invention, step S11 is first executed to partition the mask plate 101 into the pattern area 101a and the defocus mark area, where the defocus mark area is located at the edge of the pattern area 101 a; specifically, as shown in fig. 7 or 8, the graphic area 101a is rectangular, the defocus mark area includes a first mark area 101b and a second mark area 101c, and both the first mark area 101b and the second mark area 101c are rectangular and located on opposite sides of the graphic area 101 a. When the mask plate shown in fig. 7 is used, the regions on the other two sides of the pattern region 101a may be light-transmitting regions.
Next, step S12 is performed, as shown in fig. 9, in which the diaphragm 15 is provided above the mask plate, and the first side (the left side in the drawing) of the diaphragm 15 blocks light emitted from the first position 11a on the pupil from being irradiated onto the first mark area 101 b. Thus, for the first mark region 101b, only illumination of light emitted from the second position 11b of the illumination pupil 11 is received, and accordingly, when the illumination pupil 11 is viewed from the mask plane back, the pupil shape as viewed is asymmetric as shown in fig. 10.
The illumination pupil 11 emits light from the second position 11b to the first mark area 101b for diffraction, the objective lens collects +1 st order diffracted light, 0 st order diffracted light and-1 st order diffracted light and then forms an image in a third position 102a on the silicon wafer surface (on the photoresist layer) in a coherent manner, the third position 102a corresponds to one side wall of the photoresist layer, it can be seen that the third position 102a is only illuminated by the first mark area 101b, and accordingly, when the imaging pupil 143 is viewed from the third position 102a, the observed pupil shape is an asymmetric pupil as shown in fig. 11.
In contrast, the second side (right side in the figure) of the stop 15 blocks the light emitted from the second position 11b of the illumination pupil from reaching the second mark area 101c, and only the illumination of the light emitted from the first position 11a of the illumination pupil 11 is received for the second mark area 101c, and accordingly, when the illumination pupil 11 is viewed from the second mark area 101c, the pupil shape viewed is asymmetric as shown in fig. 12.
The illumination light emitted from the first position 11a of the illumination pupil 11 is diffracted after reaching the second mark area 101c, the objective lens collects the +1 st order diffracted light, the 0 th order diffracted light and the-1 st order diffracted light and then forms a coherent image at a fourth position 102b on the silicon wafer surface (on the photoresist layer) 102, the fourth position 102b corresponds to the other side wall of the photoresist layer, it can be seen that the fourth position 102b is only illuminated by the second mark area 101c, and accordingly, when the imaging pupil 143 is viewed from the fourth position 102b, the viewed pupil shape is an asymmetric pupil as shown in fig. 13.
Since the stop 15 blocks only the defocus mark regions 101b and 101c, the illumination pupil 11 is viewed in the pattern region 101a, the pupil shape is viewed as symmetrical illumination as shown in fig. 14, the imaging pupil 143 is viewed in the exposure region 102c of the silicon wafer surface 102, and the pupil shape is viewed as symmetrical pupil as shown in fig. 15. The exposure area 102c is symmetrically illuminated to ensure the uniformity of the left and right sidewall angles of the photoresist layer.
In order to verify the feasibility of the exposure method provided by the embodiment, simulation was performed by using Zemax simulation software, and when the light source detector gradually moves from the edge of the field of view to the inside of the field of view, a process from disappearance to gradual appearance of one pole of the two-pole light source occurs. Therefore, it is proved that the first mark region 101b and the second mark region 101c are asymmetrically illuminated by setting the diaphragm, and the pattern region is symmetrically illuminated, so that the exposure method provided by the embodiment is feasible.
FIG. 16 shows that, under the same exposure system and photoresist parameters, after exposure is performed by the exposure method provided by the embodiment of the present invention, the horizontal position of the photoresist line changes with defocus and monotonicity, and the change is obvious. Specifically, when the defocus amount is changed from-100 nm to +100nm, the photoresist layer side wall angle is significantly increased. When the side wall of the photoresist layer is obviously increased, the-1 level light asymmetry which is diffracted on the photoresist layer is larger, namely, the +1 level light-1 level light asymmetry reacts to defocusing change more sensitively, so that when the defocusing amount is measured through asymmetry, the defocusing amount measuring error can be reduced, the defocusing amount measuring precision is improved, and the measuring repeatability is reduced.
In view of this, an embodiment of the present invention further provides a defocus measurement method, as shown in fig. 17, the defocus measurement method includes the following steps:
s21, completing exposure on the target photoresist layer by using the exposure method provided by the embodiment of the invention;
s22, measuring the asymmetry of the +1 level light and the-1 level light which are diffracted on the target photoresist layer, and calculating the exposure defocusing amount according to the measurement result and the relationship between the asymmetry of the +1 level light and the-1 level light and the defocusing amount.
In step S22, the method for measuring the asymmetry of +1 order light and-1 order light diffracted on the target photoresist layer includes: respectively obtaining a + 1-order diffraction spectrum and a-1-order diffraction spectrum, and comparing the signal intensity of + 1-order light and-1-order light; and obtaining the asymmetry of the +1 level light and the-1 level light which are diffracted on the target photoresist layer according to the difference of the signal intensities.
By analyzing the cloud images of the signals of +1 st order light and-1 st order light on the illumination pupil plane, the asymmetry of the +1 st order light and the-1 st order light is substantially linear with the defocus amount. In view of this, in this embodiment, preferably, when the relation between the asymmetry of the +1 level light and the asymmetry of the 1 level light is established, the measured asymmetry of the +1 level light and the 1 level light is normalized, and the relation between the asymmetry of the +1 level light and the asymmetry of the 1 level light and the defocus amount is made to be a linear relation by normalizing the amount, that is, the linear relation between the asymmetry of the +1 level light and the defocus amount is established by the following method:
under different defocus amounts, after a test photoresist layer is exposed by the exposure method provided by the embodiment of the invention, the asymmetry of + 1-order light and-1-order light which are diffracted on the test photoresist layer is measured, and the measurement result is normalized to obtain the linear relation.
After the measured asymmetry of the +1 level light and the-1 level light is normalized, the change of the asymmetry of the normalized +1 level light and the 1 level light along with the defocusing amount is shown in fig. 18, as can be seen from fig. 18, in a defocusing range of-100 nm to 100nm, the asymmetry of the +1 level light and the defocusing amount present a good linear relation, the slope of linear fitting is 1e-3 which is 5 times of that of a comb-tooth-shaped mask, and the asymmetry of the +1 level light and the 1 level light is relatively sensitive to the defocusing change. The repeatability of the defocusing measurement caused by the scheme can be within 2nm and is far less than the performance of the comb-shaped mask.
In another embodiment, the relation between the + 1-level light-1 level asymmetry and the defocus amount can also be embodied in a table manner, the + 1-level light-1 level asymmetry and the defocus amount are in one-to-one correspondence through a list, after the exposure is completed and the measurement of the + 1-level light-1 level light asymmetry is performed, the corresponding defocus amount can be obtained through table lookup, and when the measured + 1-level light-1 level light asymmetry is not embodied in the table, the corresponding defocus amount can be obtained by adopting a linear interpolation method.
[ example two ]
It was found that the horizontal position of the photoresist changes with the defocus amount, and as shown in fig. 16, the relationship between the horizontal position change and the defocus amount reaches 0.25 or more. For example, when the defocus amount is 100nm, the photoresist layer is horizontally moved by 25 nm. As shown in fig. 19, the defocus causes a horizontal displacement of the photoresist layer, and thus a change in overlay occurs, and the generated overlay error is substantially proportional to the defocus amount.
In view of this, on the basis of the exposure method provided in the first embodiment, the present embodiment further provides another defocus measurement method, please refer to fig. 20 in combination with fig. 21, where the defocus measurement method includes the following steps:
s31, sequentially disposing a first overlay mark 104 and a second overlay mark 105 on the substrate 103 for bearing the target photoresist layer 102 and the target photoresist layer 102, wherein the first overlay mark 104 and the second overlay mark 105 are coaxially disposed;
s32, completing exposure of the target photoresist layer 102 by using the exposure method provided by the first embodiment;
and S33, calculating the overlay errors of the first overlay mark 104 and the second overlay mark 105, and calculating the defocus amount according to the measurement result and the relationship between the overlay errors and the defocus amount.
Wherein the first overlay mark 104 and the second overlay mark 105 may be gratings with the same period.
In this embodiment, when establishing the relationship between the overlay error and the defocus amount, the following method may be adopted: sequentially arranging the first set of engraving marks 104 and the second set of engraving marks 105 on a substrate for bearing a test photoresist layer and the test photoresist layer; under different defocus amounts, after the test photoresist layer is exposed by using the exposure method according to the first embodiment, overlay errors of the first set of lithography marks 104 and the second set of lithography marks 105 are measured, and then a relationship between the overlay errors and the defocus amounts is established according to the different defocus amounts and the overlay errors corresponding to the different defocus amounts.
In addition, when calculating the overlay errors of the first overlay mark 104 and the second overlay mark 105, the following method may be adopted: calculating asymmetry of +1 order light and-1 order light diffracted on the first overlay mark 104 and the second overlay mark 105, respectively; the overlay errors of the first overlay mark 104 and the second overlay mark 105 are calculated according to the asymmetry of the +1 order light and the-1 order light diffracted on the first overlay mark 104 and the second overlay mark 105.
Referring to fig. 21, in this embodiment, it is preferable that the first set of etching marks include a first alignment sub-mark 104a and a second alignment sub-mark 104b, after the first alignment mark 104 is disposed on a substrate (including a substrate for carrying a target photoresist layer and a substrate for carrying a test photoresist layer), positions of two sidewalls of the photoresist layer formed on the substrate on which the first alignment mark 104 is formed respectively correspond to positions of the first sub-alignment mark 104a and the second sub-alignment mark 104b, that is, positions of exposure regions of the photoresist layer defined by the first sub-alignment mark 104a and the second sub-alignment mark 104b correspond to each other, the second alignment mark 105 includes a third sub-alignment mark 105a and a fourth sub-alignment mark 105b, and the third sub-alignment mark 105a and the first sub-alignment mark 104a are coaxially disposed, the grating may be a grating with the same period, and the fourth sub-overlay mark 105b and the second sub-overlay mark 104b are coaxially disposed, and may be a grating with the same period.
The base 104 in this embodiment may be a silicon substrate.
At different defocus amounts, the second overlay mark 105 is displaced with the photoresist layer 102 in different horizontal directions, and since the first overlay mark 104 is disposed on the substrate and does not move with the movement of the photoresist layer 102, the overlay between the first overlay mark 104 and the second overlay mark 105 varies. Error analysis results show that by adopting the defocus measurement method provided by the embodiment, the defocus measurement repeatability can be reduced to 0.8 nm.
In summary, the exposure method and the defocus measurement method provided by the invention solve the problems of high defocus measurement repeatability, poor precision and high mask design and manufacturing cost in the prior art.
It should be noted that, in the present specification, the embodiments are described in a progressive manner, each embodiment focuses on differences from other embodiments, similar parts between the embodiments may be referred to each other, and different parts between the embodiments may also be used in combination with each other, which is not limited by the present invention.
The above description is only for the purpose of describing the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention, and any variations and modifications made by those skilled in the art based on the above disclosure are within the scope of the appended claims.
Claims (10)
1. An exposure method, comprising:
partitioning a mask plate into a graph area and an out-of-focus mark area, wherein the out-of-focus mark area is positioned at the edge of the graph area;
and arranging a diaphragm above the mask plate, and realizing asymmetric illumination on the side wall of the photoresist layer by the light penetrating through the defocusing mark area and symmetric illumination on an exposure area of the photoresist by the light penetrating through the graphic area through the diaphragm so as to complete exposure of the photoresist layer.
2. The exposure method according to claim 1, wherein the pattern area is rectangular, the defocus mark area includes a first mark area and a second mark area, and the first mark area and the second mark area are both rectangular and located on opposite sides of the pattern area.
3. A defocus amount measurement method, comprising:
performing exposure on the target photoresist layer by using the exposure method according to claim 1 or 2;
and calculating the asymmetry of the +1 level light and the-1 level light which are diffracted on the target photoresist layer, and calculating the exposure defocusing amount according to the calculation result and the relationship between the asymmetry of the +1 level light and the-1 level light and the defocusing amount.
4. The defocus amount measuring method of claim 3, wherein the relation between the asymmetry of the +1 st order light and the defocus amount is a linear relation, and the method for obtaining the linear relation comprises:
after a test photoresist layer is exposed by the exposure method according to claim 1 or 2 under different defocus amounts, calculating asymmetry of +1 order light and-1 order light diffracted on the test photoresist layer, and normalizing the calculation result to obtain the linear relationship.
5. The defocus amount measuring method of claim 3, wherein the method of measuring the asymmetry of +1 order light and-1 order light diffracted on the target photoresist layer comprises:
comparing the signal intensity of the + 1-order light and the-1-order light according to the + 1-order diffraction spectrum and the-1-order diffraction spectrum which are respectively obtained at the same position of the illumination pupil;
and obtaining the asymmetry of the +1 level light and the-1 level light which are diffracted on the target photoresist layer according to the difference of the signal intensities.
6. A defocus amount measurement method, comprising:
sequentially arranging a first alignment mark and a second alignment mark on a substrate for bearing a target photoresist layer and the target photoresist layer, wherein the first alignment mark and the second alignment mark are coaxially arranged;
performing exposure on the target photoresist layer using the exposure method according to claim 1 or 2;
and calculating the overlay errors of the first overlay mark and the second overlay mark, and calculating the defocus amount according to the calculation result and the relationship between the overlay errors and the defocus amount.
7. The defocus amount measuring method of claim 6, wherein the method of establishing the relationship between the overlay error and the defocus amount comprises:
sequentially arranging the first overlay mark and the second overlay mark on a substrate for bearing a test photoresist layer and the test photoresist layer;
under different defocus amounts, after a test photoresist layer is exposed by respectively using the exposure method as claimed in claim 1 or 2, overlay errors of the first overlay mark and the second overlay mark are measured, and then a relationship between the overlay errors and the defocus amounts is established according to the different defocus amounts and the overlay errors corresponding to the different defocus amounts.
8. The defocus amount measuring method of claim 6, wherein the first overlay mark comprises a first sub-overlay mark and a second sub-overlay mark, and after the first overlay mark is disposed on a substrate, positions of two sidewalls of a photoresist layer formed on the substrate on which the first overlay mark is formed correspond to positions of the first sub-overlay mark and the second sub-overlay mark, respectively.
9. The defocus amount measuring method of claim 6, wherein the method of calculating the overlay error of the first overlay mark and the second overlay mark comprises:
calculating asymmetry of +1 order light and-1 order light diffracted on the first overlay mark and the second overlay mark, respectively;
and calculating the overlay errors of the first overlay mark and the second overlay mark according to the asymmetry of + 1-level light and-1-level light which are diffracted on the first overlay mark and the second overlay mark.
10. The defocus amount measuring method of claim 6, wherein the first overlay mark and the second overlay mark are gratings with the same period.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010065822.3A CN113138545B (en) | 2020-01-20 | 2020-01-20 | Exposure method and defocus measurement method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010065822.3A CN113138545B (en) | 2020-01-20 | 2020-01-20 | Exposure method and defocus measurement method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113138545A true CN113138545A (en) | 2021-07-20 |
| CN113138545B CN113138545B (en) | 2022-06-03 |
Family
ID=76808900
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010065822.3A Active CN113138545B (en) | 2020-01-20 | 2020-01-20 | Exposure method and defocus measurement method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113138545B (en) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20050219515A1 (en) * | 2004-04-06 | 2005-10-06 | Hiroshi Morohoshi | Aberration measuring method |
| JP2006030466A (en) * | 2004-07-14 | 2006-02-02 | Matsushita Electric Ind Co Ltd | Exposure mask, reference data preparation method, focus measurement method, exposure apparatus manadement method, and electronic device manufacturing method |
| CN103383524A (en) * | 2012-05-02 | 2013-11-06 | 上海微电子装备有限公司 | Defocus measuring method for photoetching equipment |
| US20170003606A1 (en) * | 2015-06-30 | 2017-01-05 | Kabushiki Kaisha Toshiba | Mask alignment mark, photomask, exposure apparatus, exposure method, and manufacturing method of device |
-
2020
- 2020-01-20 CN CN202010065822.3A patent/CN113138545B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20050219515A1 (en) * | 2004-04-06 | 2005-10-06 | Hiroshi Morohoshi | Aberration measuring method |
| JP2006030466A (en) * | 2004-07-14 | 2006-02-02 | Matsushita Electric Ind Co Ltd | Exposure mask, reference data preparation method, focus measurement method, exposure apparatus manadement method, and electronic device manufacturing method |
| CN103383524A (en) * | 2012-05-02 | 2013-11-06 | 上海微电子装备有限公司 | Defocus measuring method for photoetching equipment |
| US20170003606A1 (en) * | 2015-06-30 | 2017-01-05 | Kabushiki Kaisha Toshiba | Mask alignment mark, photomask, exposure apparatus, exposure method, and manufacturing method of device |
Also Published As
| Publication number | Publication date |
|---|---|
| CN113138545B (en) | 2022-06-03 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US11640116B2 (en) | Metrology method, computer product and system | |
| US10379445B2 (en) | Metrology method, target and substrate | |
| KR101960403B1 (en) | Inspection apparatus, inspection method and manufacturing method | |
| KR102048794B1 (en) | Instrumentation methods and devices, computer programs and lithography systems | |
| JP6618551B2 (en) | Inspection apparatus, inspection method, lithographic apparatus, patterning device, and manufacturing method | |
| EP1006413B1 (en) | Alignment method and exposure apparatus using the same | |
| KR100255399B1 (en) | Condition optimization method for measuring overlay accuracy of pattern | |
| US20230044632A1 (en) | Dark field digital holographic microscope and associated metrology method | |
| US10571812B2 (en) | Method of calibrating focus measurements, measurement method and metrology apparatus, lithographic system and device manufacturing method | |
| US20190094703A1 (en) | Method to Determine a Patterning Process Parameter | |
| EP3531191A1 (en) | Metrology apparatus and method for determining a characteristic of one or more structures on a substrate | |
| CN113138545B (en) | Exposure method and defocus measurement method | |
| TWI808557B (en) | Method of metrology and associated apparatuses | |
| KR20220065038A (en) | Methods and associated methods for inferring processing parameters such as focus, and manufacturing methods | |
| TW202409523A (en) | Method and apparatuses for fourier transform spectrometry | |
| KR20240036031A (en) | Measurement methods and measurement devices | |
| WO2021073873A1 (en) | Method and apparatus for coherence scrambling in metrology applications | |
| JP2005351833A (en) | Shearing interferometer, measuring method by shearing interferometer, method of manufacturing projection optical system, projection optical system, and exposure device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |