JPH0274802A - Alignment apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an alignment device, and for example, in an exposure device for manufacturing semiconductor elements, aligning a mask or a reticle (hereinafter referred to as “mask”) or the like on a first object surface. This invention relates to an alignment device suitable for performing relative positioning (alignment) between a mask and a wafer when exposing and transferring a fine electronic circuit pattern formed on a second object surface such as a wafer. .

(Prior art) In exposure equipment for semiconductor manufacturing, relative alignment of the mask and wafer has been an important element for improving performance.Especially in alignment in recent exposure equipment, In order to increase the degree of integration of semiconductor devices, it is required to have alignment accuracy of, for example, submicron or less.

In many alignment devices, a so-called alignment pattern for alignment is provided on the mask and wafer surface.
Alignment of both is performed using the position information obtained from them. As an alignment method at this time, for example, the amount of deviation between both alignment patterns may be detected by performing image processing, or U.S. Pat.
As proposed in No. 037969 and JP-A-56-157033, a zone plate is used as an alignment pattern and a light beam is irradiated onto the zone plate, and at this time, the light beam emitted from the zone plate is focused at a focal point on a predetermined surface. This is done by detecting the position.

In general, an alignment method using a zone plate has the advantage of being able to perform alignment with relatively high precision without being affected by defects in the alignment pattern, compared to a method using a simple alignment pattern.

FIG. 20 is a schematic diagram of a conventional alignment device using a zone plate.

In the same figure, a parallel light beam emitted from a light source 72 passes through a half mirror 74 and is condensed at a condensing point 78 by a condensing lens 76, after which it is placed on a mask alignment pattern 68a on the surface of a mask 68 and a support base 62. The wafer alignment pattern 60a on the surface of the wafer 60 is irradiated. These alignment patterns 68a and 60a are composed of reflective zone plates, and each form a focal point on a plane perpendicular to the optical axis including the focal point 78. At this time, the amount of shift in the position of the converging point on the plane is detected by guiding the light onto the detection section 82 using the condensing lens 76 and the lens 80.

Based on the output signal from the detector 82, the control circuit 8
4 drives the drive circuit 64 to perform relative positioning of the mask 68 and the wafer 60.

FIG. 21 is an explanatory diagram showing the imaging relationship between the light beams from the mask alignment pattern 68a and the wafer alignment pattern 60a shown in FIG. 20.

In the figure, a part of the light beam diverging from the condensing point 78 is diffracted by the mask alignment pattern 68a,
A focal point 78a indicating the mask position is formed near the focal point 78. Further, the other part of the light beam passes through the mask 68 as zero-order transmitted light and enters the wafer alignment pattern 60a on the surface of the wafer 60 without changing its wavefront. At this time, the light beam is diffracted by the wafer alignment pattern 60a, and then passes through the mask 68 again as zero-order transmitted light, condensing near the converging point 78 and focusing on the wafer position.
form. In the figure, when the light beam diffracted by the wafer 60 forms a condensing point, the mask 68 simply acts as a transparent state.

The position of the focal point 78b due to the wafer alignment pattern 60a formed in this way is determined according to the displacement amount Δσ of the wafer 60 with respect to the mask 68 along a plane perpendicular to the optical axis including the focal point 78. It is formed as a deviation amount Δσ' corresponding to Δσ.

In such a method, if the wafer surface is inclined with respect to a reference plane such as a mask, a mask holder surface in a semiconductor exposure device, or a ground plane of an exposure device, the center of gravity of the light beam incident on the sensor will be changes, resulting in an alignment error.

In general, establishing an absolute coordinate system on the sensor and setting its reference origin is difficult due to other alignment error factors, such as tilting of the wafer surface due to warpage or deflection, variation in the center of gravity of the light beam due to uneven resist coating, and alignment light source. There has been a problem in that it is very difficult to set the origin with high precision due to fluctuations in the oscillation wavelength, oscillation output, and beam exit angle, fluctuations in sensor characteristics, and fluctuations due to repeated alignment head positions.

(Problems to be Solved by the Invention) The present invention provides a means for eliminating error factors in detecting the amount of deviation when aligning a first object such as a mask and a second object such as a wafer. In addition to the alignment beam as a second signal beam, an alignment beam as a second signal beam is formed from diffracted beams from a linear grating lens of a different order from the first signal beam, and by using these signal beams, high precision can be achieved. In particular, the present invention is characterized in that it provides an alignment device that enables precise alignment, so that the effect of the movement of the center of gravity on the sensor with respect to the inclination of the surface of the second signal beam is completely equal to that of the first signal beam. In addition, the second signal beam is set so that it is subjected to the same movement of the center of gravity as the first signal beam even when the position of the alignment head changes.
To provide an alignment device that enables highly accurate alignment by making fluctuations in the relative positions of a signal light beam and a first signal light beam on a sensor theoretically dependent only on the positional deviation between a mask and a wafer. It is an object.

(Means for solving the problem) When a first object and a second object are opposed to each other for relative positioning, physical optical elements are formed on the first object surface and the second object surface, respectively. The diffraction light generated when light is incident on one of the physical optical elements is made incident on the other physical optical element, and the light quantity distribution of the diffraction pattern generated on a predetermined surface by the other physical optical element is detected by the means. When performing relative positioning of the first object and the second object by detection, one physical optical element A of the two physical optical elements is configured with a linear grating lens,
The structure is such that the light fluxes of different diffraction orders emitted from the physical optical element A have convex lens action and concave lens action at the same time.

In particular, in the present invention, the other physical optical element B of the first or second physical optical element is connected to the first physical optical element B. The first for the second signal. Second
It is composed of two alignment marks B1 and B2, and the first... the first alignment marks B1 and B2. The center of gravity of the light flux of the diffracted light from the second alignment marks B1 and B2 is the first. Detected by the second detection section, or conversely, detected by the first detection section. The diffracted lights from the second alignment marks B1 and B2 are made incident on the physical optical element A, and the beam gravity of the two diffracted lights from the physical optical element A is centered at the first. The second detection section detects the first. The present invention is characterized in that the positioning of the first object and the second object is performed using the output signal from the second detection section.

In addition, the present invention is characterized in that each element is set so that the center of gravity of the two diffracted lights on a predetermined plane is displaced in opposite directions with respect to the positional deviation between the first object and the second object. There is.

(Example) Fig. 1 is a schematic diagram of the main part of the first embodiment of the present invention, and Fig. 2 is a schematic diagram of the main part when the optical path of Fig. 1 is expanded. . 2 is the second object, for example mask 1
The wafer is aligned with the wafer. 3.4 is the first one for alignment. This is a second physical optical element, and is provided on the first object 1 and second object 2 surfaces, respectively.

The first physical optical element 3 is the first physical optical element 3. The first for the second signal. It consists of second alignment marks 3a and 3b, and the second physical optical element 4 consists of a linear grating lens.

In FIG. 1, a light beam from a light source 8 is converted into parallel light by a projection lens 9. Second alignment mark 3a, 3
b is irradiated. And alignment marks 3a, 3
The diffracted light beam of a predetermined order diffracted by b is further diffracted by the alignment mark 4, and the 1st-order diffracted light 6 of the diffracted light is
is incident on the sensor 5a, and the +1st-order diffracted light 7 is incident on the sensor 5b. Then, the spot position information of the diffracted light is processed by a process including a processing circuit; This constitutes an alignment system that moves the first object 1 and the second object 2 to predetermined positions.

In FIG. 1, the X direction is the alignment direction, and the lens action is applied only in this direction to the first . Second
This is done by the alignment marks 3a and 3b. In the plane YZ perpendicular to the alignment direction, the alignment mark 3a has the effect of deflecting the human exit angle.
3b consists of a curved pattern. Among these, the mark shapes have opposite signs of curvature so that the first alignment mark 3a has a convex power and the second alignment mark 3b has a concave power in the alignment direction.

On the other hand, the alignment mark 4, which is the second physical optical element, is composed of a linear grating lens. It has convex power and concave power depending on the sign of the order. At this time, the chief ray of each order of diffracted light is in the same direction as the incident light.

In this embodiment, a reflective physical optical element is used.
The alignment light 6°7 corresponds to the direction diffracted by the second alignment marks 3a and 3b, and the alignment light 6°7 is directed to the sensor 5, respectively.
It is reflected and diffracted in directions a and 5b.

Next, the principle and features of the configuration of the alignment device shown in FIG. 1 will be explained using FIG. 2.

FIG. 2 is a schematic diagram showing the optical system developed along the light flux and the light flux passing through the center of each alignment mark in the embodiment of FIG. 1, and showing the projected components onto a plane perpendicular to the plane of incidence.

In FIG. 2, the first object on the surface of the first object. on the second alignment marks 3a, 3b and the second surface of the second object.

Each of the alignment marks 4 is a physical optical element having a one-dimensional lens function (having power only in the plane of the paper), and the alignment light beam is diffracted as shown in the figure. That is, the parallel incident light is focused at the position indicated by the point F1 by the first alignment mark 3a, and is focused at the point F2 by the second alignment mark 3b. On the other hand, the alignment mark 4 has diffraction orders with different signs (here +
It has the function of forming an image of the point F and the point F2 onto the sensor surface S by the lens action of the first order and the second order. The distance between the first object 1 and the second object 2 is g, and the distance between the second object 2 and the sensor 5 is L. The focal lengths of the second alignment marks 3a and 3b are respectively f and f2.

Also, let the amount of relative positional deviation between the first object 1 and the second object 2 be 6, and let the amounts of displacement from the matched state of the center of gravity of the signal light beam at that time be S1 and S2, respectively. Displacement amounts SI and S of the center of gravity of the signal beam
2 is a straight line connecting the focal point F, F2 of the alignment marks 3a, 3b and the optical axis center of the alignment mark 4 and the detection surface 5.
It is determined geometrically as the intersection with Therefore, in order to obtain the displacements of the center of gravity of each signal beam ffl s + , S 2 in opposite directions with respect to the relative positional deviation between the first object 1 and the second object 2, the signs of the imaging magnifications by the alignment mark 4 are set to be opposite to each other. The diffraction orders are selected so that

For example, the displacement amounts S1 and S2 at this time can be expressed quantitatively as follows.

Here, focal length #f+, f2 is f as shown in the figure, positive is r2
If we have a convex lens and a concave lens that have a negative effect and the distance is sufficiently large (compared to f+ and fz),
The positional deviation of the center positions of the signal light beams is magnified and they move in opposite directions.

The difference ΔS between the spot positions on the sensor 5 surface is Δ5=S2−S
, then it becomes.

Further, when the alignment mark 4 is of a reflective type, the same can be obtained. That is, in this case, the alignment mark 4 and subsequent parts in FIG. 2 may be considered by folding back symmetrically with respect to the alignment mark 4.

Next, a case where the second object 2 is tilted by a slight amount β will be described. All the light beams emitted from the alignment mark 4 are inclined at an angle of 2β according to the law of reflection. If the distance fiL is sufficiently large, the amount of movement of the spot due to this inclination is Sβ
=2βL roar.

The spot position on the sensor 5 surface changes for both the convex-concave system and the concave-convex system, and Sl = SI + 2βL S2 = 82 + 2βL Δs' = s2- s, = s2-s, = ΔS, and the difference ΔS between the 5 spot positions depends on the slope. It turns out that there isn't.

In this embodiment, the movement of the signal light flux on the sensor 5 surface S1, S
2 is expressed by equations (1) and (2), f, = 43
If 0 μm f2 = -370 μm g = 30 μm L = 40000 μm, then = -996 = 1016, and if the difference signal 52-S is taken, S2-S = (101 + 99) ε = 2006.

That is, the positional deviation ε between the first object l and the second object 2 can be detected with a sensitivity 200 times greater.

Now, when the resolution of sensor 5 is 1μm, it is 0.005μ
This means that a positional deviation of m can be detected.

When the first object l is a mask and the second object 2 is a wafer, and the alignment is applied to a proximity exposure apparatus, it is better to use the alignment mark 4 on the wafer 2 as a linear grating lens as in this embodiment, or This is preferable in consideration of deformation caused by the process. In addition, depending on the case, the first object 1 side may be used as a linear grating lens.

In this embodiment, the linear grating lens is provided on the second object surface, but the linear grating lens is provided on the first object surface, and the linear grating lens is provided on the second object surface. The object of the present invention can be achieved in the same manner as described above even if a configuration is provided in which a 1.degree. second alignment mark for the second signal is provided.

A first object provided on the first object or the second object surface. The first for the second signal. The arrangement state of the second alignment mark is determined by the alignment direction (
The direction may be perpendicular to the X direction, or the direction may be parallel to the X direction. Furthermore, they may be arranged in an overlapping manner within the same area.

FIG. 3 is a schematic diagram of the main part of the second embodiment of the present invention, and FIG. 4 is a schematic diagram of the main part when the optical path in FIG. 3 is expanded.
1st and 2nd alignment marks 3a provided on one surface of the object
, 3b are arranged in the alignment direction (X direction). As shown in FIG. second alignment mark 3a,
The optical axis of 3b is located at the mark boundary, and is set to condense light at each of the four points F, , F2. The movement of the light flux on the surface of the sensor 5 is the same as in the first embodiment.

FIG. 5 is a schematic diagram of the main part of the third embodiment of the present invention, and FIG. 6 is a schematic diagram of the main part when the optical path in FIG. 5 is expanded.
A first lens that acts as a convex lens for the physical optical element 3 on the surface of the object 1.
It is constructed by overlapping an alignment mark 3a and a second alignment mark 3b which acts as a concave lens.

As shown in FIG. The optical axis of the second alignment mark is located at the center of the mark, and the second alignment mark has a convex lens function and a concave lens function, and is set so that the light beam is focused on points F, . . . F2. The movement of the light flux on the surface of the sensor 5 is the same as in the first embodiment.

FIG. 7 is a schematic diagram of the main part of the fourth embodiment of the present invention, and FIG. 8 is a schematic diagram of the main part when the optical path shown in FIG. The light is first projected onto the second physical optical element 4 on the second object 2.

Then, the reflected diffracted light from the second physical optical element 4 is transmitted to the first physical optical element, which is the first physical optical element, on the surface of the first object 1. The diffracted light of a predetermined order is made incident on the second alignment marks 3a, 3b and detected by the sensors 5a, 5b.

The second physical optical element 4 on the second surface of the second object 2 is composed of a linear grating lens, and the incident parallel light beam is diffracted. Among them, the +1st order diffracted light is focused on the focal point F1, and the -1st order diffracted light is focused on the focal point F2. be done. The focal lengths at this time are f+ and -f+, respectively.

The first alignment mark 3a on the first object i has the function of a concave lens so that the light beam focused on the point F is imaged onto the surface of the sensor 5a, and the second alignment mark 3b is on the point F.
It has the function of a convex lens so that the light beam condensed into the sensor 5b is imaged onto the surface of the sensor 5b.

The amount of relative positional deviation between the first object 1 and the second object 2 is -6,
Displacement amount SI of the signal beam position at that time.

S2 is the first... The intersection point between the detection surface 5 and the straight line connecting the optical axis centers of the second alignment marks 3a and 3b and points F1 and F2 is determined by geometrical optics and quantitatively expressed as follows.

Now, if f, = and g = then =40000 μm 400 μm 30 μm ~ 1086 ~ -936 If we take the difference signals S and -S, we get 52-3. = -93ε-108ε= -2016, and 20 for the positional deviation ε between the first object 1 and the second object 2.
It can be detected with 1 times the sensitivity.

FIG. 9 is a schematic diagram of a main part of an embodiment in which the alignment apparatus of the fourth embodiment shown in FIG. 7 is applied to a proxy mirror type exposure apparatus for semiconductor manufacturing.

In FIG. 9, the light emitting system and light receiving system are the alignment light source 8,
Projection lens 9, projection mirror 17 and sensors 5a, 5b,
The processing circuits 10a and 10b are housed in a pickup head 16 that is integrated with the processing circuits 10a and 10b, and the entire structure is movable to an alignment mark position by a stage (not shown). The alignment light beam projected from the pickup head 16 passes through the mask 1, which is the first object supported by the mask holder 15, and reaches the wafer alignment mark 4 on the wafer 2, which is the second object supported by the wafer stage 12. The light is then diffracted by the output alignment mark 3 on the mask 1 surface, which is the first object, and is again sent to the pickup head 16 and received by the sensors 5a and 5b.

Sensor 5a.

The spot information of the diffracted light beam received by 5b is processed by the processing circuit 1.
0a and 10b, the exposure system controller 14
This is recognized as alignment information between mask 1 and wafer 2. Here, a movement signal is sent to the stage controller 11 to move the wafer stage 12 to the optimum position and perform exposure, and the wafer stage 12 is moved.

When alignment is completed, an exposure beam is projected onto the exposure area indicated by E, and printing is completed. At this time, the alignment light constitutes an oblique optical system and an oblique optical system, and no evacuation operation is required.

FIG. 10 is a schematic diagram of the main part of the fifth embodiment of the present invention, and FIG. 11 is a schematic diagram of the main part when the optical path in FIG. 10 is developed.

In this embodiment, as in the fourth embodiment shown in FIG. A system is constructed in which the diffracted light is incident on the second alignment marks 3a and 3b and detected by sensors 5a and 5b. The 1° second alignment marks 3a and 3b on the first object 1 are arranged in the alignment direction.

As shown in FIG. 2nd alignment mark 3
The optical axes of a and 3b are at the mark boundary, and each point Fl1
The light is set to be focused at the position of point F2, and the movement on the surface of the sensor 5 is the same as in the fourth embodiment.

FIG. 12 is a schematic diagram of the main part of a sixth embodiment of the present invention, and FIG. 13 is a schematic diagram of the main part when the optical path in FIG. 12 is developed.

In this embodiment, the incident position of the alignment light beam on the sensor surface 5 when there is no relative positional deviation between the first object 1 and the second object 2 is defined as the alignment direction and the perpendicular cross section passing through the center of the alignment mark, and the light beam on the sensor surface. It constitutes a system twisted by length Sc from .

The alignment mark 4 on the second object 2 and the focusing state of its diffracted light are the same as in the fourth embodiment, and the first object! A deflection action is added to the upper alignment marks 3a and 3b, and the first
Sensor 5 when there is no positional deviation between object 1 and second object 2.
Position S shifted by an upper distance of 11 isc. It is set so that the signal light flux comes to .

The signal light flux reaches this point S due to the positional deviation ε between the first object 1 and the second object 2. move in opposite directions centering on the us
1 and s2 are the same as in the fourth embodiment.

FIG. 14 is a schematic diagram of a main part of a seventh embodiment of the present invention, and FIG. 15 is a schematic diagram of a main part when the optical path in FIG. 14 is developed.

In this embodiment, the incident position of the alignment light beam on the sensor surface 5 when there is no positional deviation between the first object 1 and the second object 2 is determined from the intersection line of the sensor surface and a cross section perpendicular to the alignment direction passing through the center of the alignment mark. Distance in two systems: uneven and uneven! Sot.

Twisted by an amount different from SO2, 5orr = so2Sol
It is configured by adding an offset. Second object 2
The upper alignment mark 4 and the focusing state of its diffracted light are the same as in the fourth embodiment, and a deflection effect is added to the alignment marks 3a and 3b on the first object 1, and the first object 1 and the second object 2 are The distance asc+ on the sensor surface 5 with no positional deviation.

Position S shifted by SC2. It is set so that the signal light flux comes to I+SO2.

The signal light flux reaches this point S in accordance with the positional deviation ε between the first object 1 and the second object 2. 1 and point S. 2 in opposite directions, and ff1s+ and s2 are the same as in the fourth embodiment.

FIG. 16 is a schematic diagram of the main part of the eighth embodiment of the present invention, and FIG. 17 is a schematic diagram of the main part when the optical path in FIG. 16 is developed.

In this embodiment, the first object on one surface of the first object. Second alignment marks 3a and 3b are arranged in the alignment direction (X direction).

1st. The optical axes of the second alignment marks 3a and 3b are located at the center of each alignment mark, and a deviation occurs on the sensor 5 surface by the amount of optical axis deviation from the alignment mark 4 on the second object 2 surface. When the second object 2 is not displaced, the signal light beam reaches a point S on the sensor 5. Come to the I+SO2 position.

The signal light flux reaches this point S in accordance with the positional deviation ε between the first object 1 and the second object 2. 1 and point S. 2 in opposite directions, and the amounts S1 and S are the same as in the fourth embodiment.

FIG. 18 is a schematic diagram of the main part of the ninth embodiment of the present invention, and FIG. 19 is a schematic diagram of the main part when the optical path in FIG. 18 is expanded.

In this embodiment, the first physical optical element 3 on the first surface of the first object and the second physical optical element 4 on the second surface of the second object have two types: a convex-concave system and a concave-convex system.
The offset of the system is constructed by an alignment mark 4 made of a near grating lens on the second object 2. The light beam incident on the alignment mark 4 on the second object 2 becomes two light beams having wavefronts converging at the positions of points F1 and F2 at times J/FL. Point F1 and point F2 are points tilted from the normal line at the center of the alignment mark, and are the first object! The signal light flux in the direction connecting the optical axis centers of the upper first and second alignment marks 3a and 3b and these points is a point S. 1° point S. As shown in 2, the sensor will be in a different position.

The signal light flux reaches this point S in accordance with the positional deviation ε between the first object 1 and the second object 2. 1 and point S. 2 in opposite directions, and IS+ and S2 are the same as in the fourth embodiment.

(Effects of the Invention) According to the present invention, a first object, such as a mask, and a second object, such as a wafer, which are aligned, have a first object having the above-mentioned optical properties. Each of the second physical optical elements is formed, and one of the physical optical elements is composed of a linear grating lens element, whereby the diffracted light on a predetermined surface is adjusted to the amount of deviation from each other by two detection systems of different orders. By setting the signs to be opposite to each other, a positioning device having the following effects is achieved.

(b) Even if the center of gravity of the alignment light changes due to an inclined surface, uneven resist coating, or local inclination such as warping that occurs during the exposure process, the relative position of the two alignment signal lights will change. By detecting the position of the center of gravity, it is possible to accurately detect positional deviations without being affected by the inclination of the sea urchin surface.

(b) Since the position of the alignment head has changed relative to the mask, the center of gravity position of the alignment signal light on the sensor has changed, and 'C' also detects the relative center of gravity position of the two alignment signal lights. Therefore, it is not affected by the positional deviation of the alignment head.

(c) By configuring two systems with the same alignment mark, it is possible to effectively obtain a total magnification, and it is possible to obtain an alignment signal with approximately twice the sensitivity compared to the case of each system alone. can.

(d) Two systems of claws can be constructed using the linear grating lens, and alignment marks are simplified and easy to create.

(e) Since a linear grating lens is used, the tolerance in the alignment and orthogonal directions is large.

[Brief explanation of the drawing]

1st. Third. Fifth. 7th. 10th. 12th゜14th. 16th. FIG. 18 is a schematic diagram of main parts of the first to ninth embodiments of the present invention, and FIG. 4th. No. 6゜No. 8. 11th. 13th. 15th. 17th. FIG. 19 is a schematic diagram of the main parts when the optical paths of the first to ninth embodiments of the present invention are developed in order, and FIG. FIGS. 20 and 21 are schematic diagrams of main parts of one embodiment of the present invention when applied, and are schematic diagrams of a conventional positioning device. In the figure, 1 is the first object, 2 is the second object, and 3.4 is the first object.
．． The second physical optical elements 3a and 3b are respectively connected to the first physical optical elements 3a and 3b. 2nd alignment mark, 5, 5a, 5b are sensors, 6.7 is a diffracted light, 8 is a light source, 9 is a projection lens, 10, 10a, 10
b is a processing circuit, 11 is a stage controller, 12 is a wafer stage, 14 is an exposure system controller, 15
is a mask holder.

Claims (2)

[Claims] (1) When relative positioning is performed by making a first object and a second object face each other, a physical optical element is formed on the first object surface and the second object surface, and one of the physical optical elements is formed on the first object surface and the second object surface. The diffraction light generated when light is incident on the optical element is made incident on the other physical optical element, and the light quantity distribution of the diffraction pattern generated on a predetermined surface by the other physical optical element is detected by the detection means. When performing relative positioning between the first object and the second object, one of the two physical optical elements A is configured with a linear grating lens, and the difference emitted from the physical optical element A is A positioning device characterized in that it is configured to simultaneously have a convex lens action and a concave lens action on a light beam of a diffraction order. (2) The other physical optical element B of the two physical optical elements is aligned with the first and second signal alignment marks B1 and B.
A combination of the physical optical element A and the physical optical element B constitutes two alignment systems, a convex-concave system and a concave-convex system, and utilizes diffraction from the two alignment systems. 2. The positioning apparatus according to claim 1, wherein the relative positioning of the first object and the second object is performed by using the first object and the second object.