JPH0438812A - Sample positioning device - Google Patents

Abstract

PURPOSE:To improve the sample positioning accuracy of the title device even when the size of samples increases by arranging projections for supporting a sample holding table on a rough adjustment stage side in a scattered state in a through space inside a fine adjustment stage so that the projections can be made to function as a rough adjustment stage while the through space is faced to the arrangement of the projections and the base of the rough adjustment stage is positioned below the fine adjustment stage. CONSTITUTION:This sample positioning device is provided with a rough adjustment stage 3 which is movable in two directions of X and Y axes and a fine adjustment stage 4 which is movable in three dimensions of X, Y, and Z axes and the stages 3 and 4 are not mechanically connected with each other so that they can work independently. The stage 3 is constituted of a base 3A which is supported by a rough adjustment driving mechanism 6, etc., and a plurality of projections 3B1...3Bn for supporting a sample holding table 5 arranged on the surface of the base 3A in a scattered state. Through spaces 4A1...4An are formed inside of the stage 3 in corresponding to the projections 3B1...3Bn and the projections 3B1...3Bn are arranged in the spaces 4A1...4An while the base 3A of the stage 3 is positioned below the stage 4. The stages 3 and 4 can hand over the sample holding table 5 to each other when the vertical relation between them is changed by means of a Z-axis deriving mechanism 14.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an apparatus used for positioning a sample, such as a reduction projection exposure apparatus or an electron beam lithography apparatus used in the manufacture of semiconductor integrated circuits. .

[Conventional technology]

Conventionally, this type of positioning device has been required to have high positioning accuracy and to shorten the time required for positioning and, furthermore, the time required for manufacturing. Therefore, the positioning device includes a drive mechanism for coarse adjustment (coarse movement) dedicated to step movement,
A stage equipped with a drive mechanism for fine adjustment (fine movement) is used, and after rough positioning by the coarse movement drive mechanism, fine positioning is performed by the fine movement drive mechanism.

For example, the positioning device disclosed in Japanese Patent Application Laid-Open No. 53-64478 has a coarse movement stage that is movable in the X-axis, Y-axis, Z-axis, etc. The stage is equipped with a fine movement stage and its drive mechanism.

In addition, recently, Honganroganjin applied for the patent application No. 63-28768.
As shown in No. 3, it is movable in three dimensions (specifically, it is movable in the three axes of the X, Y, and Z axes, and it is also capable of minute rotations on the X-axis and Y-axis planes, as well as in the vertical direction. (Also performs slight tilt movement)
We have proposed a system in which a vertically penetrating space is formed inside a functional fine movement stage, and coarse movement stages movable in the X, Y, and Z axes are independently arranged in this space.

In the latter case, the fine movement stage and the coarse movement stage placed inside it can change the height (up and down) positional relationship via a two-axis drive mechanism, and the sample holding table on the stage can be changed. You can change hands. Then, in the case of coarse positioning of the sample, the top surface of the coarse movement stage is set higher than the top surface of the fine movement stage, and the coarse movement stage suction-holds the sample holder via the chuck, and in the case of fine adjustment, Conversely, by making the top surface of the fine movement stage higher than the coarse movement stage,
The fine movement stage holds the sample holder and positions it in each direction.

In this latter method, unlike the former, the fine movement stage is not placed on the coarse movement stage, and the coarse movement stage is movable independently of the fine movement stage.

Therefore, the burden of coarse movement stage movement is light, and the starting current and drive current of the drive mechanism can be reduced. Therefore, in addition to saving power consumption, it is possible to reduce the amount of heat generated and eliminate the cause of errors in laser length measurement used for positioning (air fluctuations due to heat generation), but there are the following points that should be improved.

[Problem to be solved by the invention]

In recent years, the diameter of the sample 1, for example, a wafer, has tended to increase to 8 inches, and as a result, the sample holding table has also increased in size, and the exposure range of the sample has expanded, resulting in a wider movement range of the holding table.

Under these circumstances, when positioning the wafer using the latter device, the coarse movement stage moves the sample holder in steps (coarse positioning), and then the fine movement stage changes the sample holder. Fine positioning is performed, but at this time the coarse movement stage is returned to the initial reference position r.

Then, one or more positioning operations are repeated to perform exposure and electronic drawing of the sample step by step.

When such an apparatus is used, the positional relationship between the coarse movement stage and the sample holder changes every time the coarse movement stage moves step by step. Therefore, the coarse movement stage does not necessarily chuck the center of the sample holder or its vicinity;
Sometimes the end of the sample holder was chucked in a cantilevered state.

Therefore, as the sample holder becomes larger, when the coarse movement stage that holds it chucks the sample holder at the end position, the coarse movement stage or its support mechanism will bend due to the sample holder's own weight, making positioning difficult. Adversely affect.

In addition, increasing the size of the wafer and thus the sample holder results in an increase in the size of the chuck mechanism of the coarse movement stage. When a large electromagnetic chuck is used as the chuck mechanism, the amount of heat generated by the drive current increases, and the heat is conducted to the sample holder and thermally expands, which adversely affects positioning. There was also a risk that air fluctuations on the optical path of the length measuring device would interfere with accurate position measurement.

In addition, when the coarse movement stage supports only one part of the sample holder at a position offset from the center, move the coarse movement stage to
When moving straight on the axis or the Y axis, rotational force sometimes acts on the coarse movement stage around its support point.

The present invention has been made in view of one or more points, and its main purpose is to provide an apparatus that can improve positioning accuracy by solving the above-mentioned problems associated with increasing sample size. There is a particular thing.

Furthermore, in addition to achieving the above-mentioned main purpose, vibrations generated when the coarse movement X and Y axis drive mechanisms are activated are transmitted to the fine movement table via the frame and the fine movement drive mechanism (for example, a piezoelectric actuator). To provide a positioning device capable of eliminating the situation of transmission (such a situation causes a long settling time for positioning until the vibration ends), and shortening the positioning work and ultimately the sample processing time.

[Means to solve the problem]

In order to achieve the above-mentioned main object, the present invention proposes the following problem-solving means (this will be referred to as the first problem-solving means). In order to facilitate understanding of the content, the description will be made by quoting the reference numerals of the embodiment shown in FIG.

The first problem solving means includes a coarse movement stage 3 that is movable in at least two dimensions of the X axis and Y axis, and a fine movement stage 4 that is movable in three dimensions. and a fine movement stage 4 are made independent without being mechanically connected.

The coarse movement stage 3 includes a base 3A supported by a coarse movement drive mechanism 6, etc., and a plurality of protrusions 3B for supporting the sample stage arranged in a dispersed manner on the upper surface of the base 3A.
On the other hand, the inside of the fine movement stage 4 has a through space 4A (in the embodiment, one through space 4A is 4A, . . . 4An).
5 through space 4A is made to correspond to the arrangement of protrusions 3B and -3Bn on the coarse movement stage 3 side, and the base 3A of the coarse movement stage 3 is positioned below the fine movement stage 4. Meanwhile, the protrusion 3B on the coarse movement stage 3 side...3Bn
By arranging these protrusions 3B, .

That is, the coarse movement stage 3 and the fine movement stage 4 are connected to each other via one of the Z-axis drive mechanisms 14. By changing the height positional relationship between the fine movement stages 4, it is possible to change the holding of the sample holding table 5. In this case, the protrusions 3B...3Bn on the coarse movement stage 3 side play this role.

Further, the second problem-solving means is based on the first problem-solving means described above, and is based on the X-axis of the coarse movement stage 3.

The Y-axis coarse movement drive mechanisms 6, 7 (shown in FIG. 2), etc. are arranged separately from the frame 1 supporting the fine movement stage 4, and the coarse movement drive mechanism and the coarse movement stage 3 are connected by a connecting member. 1o
Connect via.

Furthermore, as an application of the second problem-solving means, when the coarse movement stage 3 is supported by a Z-axis coarse movement drive mechanism in addition to the X-axis and Y-axis, the X-axis and Y-axis combined drive mechanism 6, 7 and the coarse movement stage 3 are connected by a flexible elastic member 10.

[Effect]

Effect of the first problem-solving means...With such a configuration, if the fine movement stage 4 and the coarse movement stage 3 are relatively moved up and down by the z@piece assistance movement mechanism 14, 5 (a) (b) The upper surface of the projections 3B1 to 3Bn on the coarse movement stage 3 side is made higher than the upper surface of the fine movement stage 4.
can be higher than the top surface of the

When roughly adjusting the position of the sample,
The sample holding table 5 is placed on the protrusions 3B1 to aBn.
Place and hold. Thereafter, the coarse movement stage 3 and, in turn, the sample holding table 5 are moved in steps by coarse movement mechanisms 6 and 7 such as the Y-axis and the Y-axis of the coarse movement stage 3. In this way, the sample 16 is roughly positioned.

After that, the operation (b) is selected, and the sample holding table 5 is transferred to the fine movement stage 4 side, and then the fine movement drive mechanism 12.
13 (shown in Figure 2) and 14 to make necessary fine movement adjustments (for example, fine movement of the sample holding table 5 in the ΔX, ΔY, and ΔZ directions, the rotation angle △θ of the Y-axis/Y-axis plane, and the vertical direction). Tilt angle Δ
λ, etc.), and the sample 16 is minutely positioned.

At this time, the coarse movement stage 3 side is returned to the reference position.

By repeating the above operations, the relative position between the sample holding table 5 and the coarse movement stage 3 changes.

Even when such a relative position between the sample holding table 5 and the coarse movement stage 3 changes, the present problem solving means can move the sample holding table 5 to a plurality of protrusions distributed on the base 3A of the coarse movement stage 3. Since it is held at 3B and 3Bn, it is possible to avoid a situation where the end of the sample holding table 5 is cantilevered as in the conventional case.

Therefore, the sample holding table 5 and the like are prevented from being bent due to overflapping.

Moreover, since the coarse movement stage 3 is supported by a plurality of protrusions 3B to 3Bn, the coarse movement stage 3 is aligned with the Y axis.

It is possible to eliminate rotational force generated in the coarse movement stage when it moves straight on the Y axis.

Furthermore, when the coarse movement stage 3 suction-holds the sample holding table 5 with a chuck, the protrusions 3B, ~3Bn of the chuck
It can be distributed and arranged separately.

Therefore, even if an electromagnetic chuck is used as the chuck, each electromagnetic chuck can be made smaller, the amount of heat generated by the chuck mechanism can be suppressed, and deformation of the sample holder 5 due to thermal expansion can be prevented. Eliminate errors in laser length measurement by eliminating air fluctuations caused by heat generation.

Therefore, highly accurate positioning can be performed by the above-mentioned actions.

Operation of the second problem-solving means: In this problem-solving means, the Y-axis of the coarse movement stage 3, the Y-axis drive machine 416°7, etc. are arranged separately from the frame 1, so the movement of the coarse movement stage 3 is In particular, since vibrations from the drive mechanism are not transmitted to the sample holding table 5, minute positioning using the fine movement stage is possible immediately after coarse movement.

The settling time for positioning can be shortened.

In addition, in the second problem solving means, when the Y-axis, Y-axis coarse motion translation mechanisms 6 and 7 and the coarse motion stage 3 are connected by a flexible elastic member 10, the coarse motion stage 3 is
Even if it moves in the axial direction, the movement can be absorbed through the elastic deformation of the elastic member 10, so that it does not interfere with the coarse movement stage and coarse movement adjustment.

〔Example〕

An embodiment of the present invention will be described based on the drawings.

FIG. 1 is a longitudinal cross-sectional view of the sample positioning device according to this embodiment,
Figure 2 is a partially simplified top view.

In these figures, 1 is a frame of the apparatus, and a coarse movement stage 3 and a fine movement stage 4 are arranged in an inner space 2 of the frame 1.

The coarse movement stage 3 is composed of a rectangular base 3A and a plurality of protrusions 3B, . . . 3Bn distributed on the upper surface thereof. In the embodiment, the protrusion 3B is 3B as shown in FIG.
There are a total of 8 pieces, B and 3B. In addition, in Figure 2,
The diagram is drawn without a sample holding table 5, which will be described later. As shown in FIG. 2, the coarse movement stage 3 has an X-axis coarse movement mechanism 6 on one side of its base 3A, and a Y@coarse movement mechanism 7 on the other side through flexible elastic members 10. They are connected and supported via a Z fine/coarse movement drive mechanism (not shown) disposed below these connecting members 10 and the base 3A.

The Z fine coarse movement drive mechanism on the side of the coarse movement stage 3 is used when transferring the sample 16 to and from another transport mechanism (not shown).

X-axis coarse movement drive mechanism 6 and Y-axis coarse movement drive mechanism 7 of this embodiment
is screw rod8. It consists of a screw feeding mechanism such as a servo motor 9, and is arranged separately from the frame 1.

Coarse movement stage 3 can move a stroke of ±25m,
It has a stopping accuracy of 2μm. Then, the screw rod 8 passes through the frame 1, and the rod tip 8 and the coarse movement stage 3 are connected via the flexible connecting member 1o as described above. An electromagnetic chuck 11 is provided on the upper surface of each of the protrusions 3B, -3B.

The fine movement stage 4 has a rectangular shape with a larger area than the coarse movement stage 3, and a plurality of holes (spaces) 4A are provided inside the fine movement stage 4, passing through the fine movement stage 4 in the vertical direction. The hole portion 4A corresponds to the projections 3B1 to 3B on the coarse movement stage side.
There are a total of 8 holes, A to 4A, and these holes are distributed.

The base 3A of the coarse movement stage 3 is located below this fine movement stage 4, and the protrusions 3B1 to 3B are connected to the holes 4A1 to 3B.
4A, respectively.

The fine movement stage 4 is supported by an X@fine fine movement assist mechanism 12, a Y axis fine movement drive mechanism 13, and a Z fine movement cantering mechanism 14. Each of the fine movement drive mechanisms for the X, Y, and Z axes is configured by, for example, a piezoelectric actuator. These piezoelectric elements are capable of displacement of 80 μm, and among these, three Z-axis fine movement drive mechanisms 14 are used to support the fine movement stage 4 at three points, and the displacement amount of each Z-axis fine movement drive mechanism is set to be different. Then, it is also possible to control the vertical inclination Δλ of the fine movement stage 4. Also, the X axis.

By cooperating the fine movement drive mechanisms 12 and 13 on both the Y-axis, it is also possible to obtain a minute rotation Δθ on the X-axis and Y-axis planes. Here, piezoelectric element actuators 12, 13.1
4, △X, ΔY fine movement is ±0.02 μm, ΔZ fine movement is ±0,1 μm, △θ fine movement is ±0.02 μm/20 mm.
, Δλ inclination (tilt) is ±0.1 μm / 20 m
Positioning is performed while maintaining each accuracy of m.

By incorporating the stages 3 and 4 in this manner, these stages can be moved independently of each other. Specifically, the coarse movement stage 3 and the fine movement stage 4 are movable in two directions, the X axis and the Y axis, by securing a space between the protrusion 3B and the hole 4A, and Movement in the Z-axis direction is possible.

Also on the upper surface of the fine movement stage 4, a plurality of electromagnetic chucks 13 are arranged in a distributed manner. Note that the electromagnetic chuck 13 may be omitted because the fine movement stage 4 moves minutely in submicron units.
This is because the sample holding table 5 can sufficiently maintain a fixed state without being chucked unless there is a large impact from the outside.

A sample holding table 5 is arranged above the coarse movement stage 3 and the fine movement stage 4. The sample holding table 5 is equipped with a vacuum suction table 15 for vacuum suctioning the sample 16 on its upper surface, and a mirror 17 for laser length measurement.

Next, the operation of this embodiment will be explained.

When positioning the sample 16, the fine movement stage 4 is lowered to a position 10 μm lower than the protrusion 3B of the coarse movement stage 3 using the three 2@fine movement mechanisms 14 in advance. In this state, the protrusion 3B of the coarse movement stage 3 supports the sample holder 5, and the electromagnetic chuck 11 is operated to attract and hold the sample holder 5 on the protrusion 3B. In this case, the sample holding table 5 is
Due to their size, not all protrusions 3B1 to 3B
It is not supported by n, but is held (chucked) by electromagnetic chucks on at least three protrusions.

Thereafter, the sample holding table 5 is step-fed in the X-axis and Y-axis directions via the X-axis coarse movement drive mechanism 6 and the Y-axis coarse movement adjustment mechanism 7.

In this embodiment, since the coarse movement stage 3 moves the sample holding table 5 in steps of 15 mm and moving it within 1.40 m5, an acceleration of 0°4G is applied to the sample holding table 5. The adsorption force of the electromagnetic chuck 1]-, which does not shift against the acceleration, is achieved by using a chuck material of 520C, chemical nickel plating of 10 to 20 μm, and a coil of 0.
．． This can be obtained by passing a current of 1 to 0.2 A (7 LA in the case of a conventional large electromagnetic chuck). With this current value, the temperature change in the coil can be suppressed to 0.5° C. or less.

After the above coarse movement adjustment, the three Z-axis piezoelectric element actuators 14 are extended and the fine movement stage 4 is raised to a position 10 μm higher than the upper surface of the projection 3B of the coarse movement table 3. At this time, the electromagnetic chuck 11 on the coarse movement stage 3 side is turned off, and the electromagnetic chuck 13 on the fine movement stage 4 side is turned on. In this way, the sample holding table 5 is transferred to the fine movement stage 4 side and held by the fine movement stage 4 by suction. At this time, the coarse movement stage 3 is returned to the original reference position.

Thereafter, the piezoelectric element actuators 12, 13, 14, etc. around the X-axis, Y-axis, and Z-axis are used to perform minute positioning of the sample holding table 5 and eventually the sample 16 (positioning in each direction of ΔX, ΔY, and ΔZ, minute positioning of Δθ rotate.

(inclination adjustment of Δλ) is performed.

By repeating the coarse positioning and fine positioning described above, exposure or electronic drawing of the sample 16 per unit step is performed one after another. In this case, the coarse movement stage 3 and the sample holding table 5
Since the relative position of changes with each step feed,
The protrusion 3B that supports the sample holding table 5 also changes.

According to this embodiment, the following effects can be achieved.

First, since the coarse movement stage 3 can be driven independently of the fine movement stage 4, the burden of driving force on the coarse movement stage 3 is reduced.

■Also. Even if the relative position between the sample holding table 5 and the coarse movement stage 3 changes, the sample holding table 5 is held by suction by at least three of the projections 3B1 to 3Bn of the coarse movement stage 3, so it is not possible to use the conventional method. Cantilever can be avoided. Therefore, the occurrence of deflection due to overhang of the sample holding table 5 etc. is prevented.

In addition, the sample holding table 5 is attached to the protrusions 3B□ to 3 of the coarse movement stage 3.
Since the Bn is adsorbed and held by at least three protrusions,
When the coarse movement stage 3 is moved straight along the X and Y axes, rotational force acting on the coarse movement stage can be eliminated.

Furthermore, since the electromagnetic chucks 11 on the coarse movement stage 3 side are dispersed, each electromagnetic chuck 11 is made small, the amount of heat generated by the electromagnetic chuck 11 is suppressed, and deformation of the sample holder 5 due to thermal expansion is prevented. Eliminate errors in laser length measurement by eliminating air fluctuations. Therefore, highly accurate positioning can be performed by each of one or more actions.

■Since the drive mechanisms 6°7 for the X-axis, Y-axis, etc. of the coarse movement stage 3 are arranged separately from the frame 1, vibrations from the drive mechanisms are not transmitted to the sample holder 5 even when the coarse movement stage 3 is moving. Therefore, the positioning settling time when entering fine positioning adjustment after coarse movement can be shortened. Specifically, in this example.

Even if the time required for positioning per unit step includes coarse movement of 15 mm step movement and subsequent fine movement, it is 0.
．． The time can be reduced to 4 seconds or less.

In the embodiment, the through space 4A on the fine movement stage 4 side into which the protrusions 3B1 to 3Bn are fitted is constituted by the holes 4A to 4An, but some of the holes 4A may be replaced with notched grooves, or , it is also possible to form one hole on the fine movement stage 4 side that can accommodate the protrusions 3B1 to 3Bn all together.

〔Effect of the invention〕

As described above, in the first problem solving means, even if the positioning device is a system in which a coarse movement stage is arranged independently inside a fine movement stage, the coarse movement stage holds the sample holder with a plurality of protrusions. This eliminates bending caused by overhanging the sample holding table, etc.

It also guarantees stable movement of the coarse movement stage in the X-axis, Y-axis, etc., and when using an electromagnetic chuck mechanism,
Since the amount of heat generated is suppressed, the sample can be positioned with extremely high precision even if the sample holding table becomes large.

Furthermore, according to the second problem solving means,
Even when the axis and Y@1fl movement mechanisms are in operation, their vibrations are not transmitted to the sample holder, so the settling time for subsequent fine positioning is shortened, and the overall positioning work and sample processing time can be shortened. .

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of a sample positioning device according to an embodiment of the present invention, and FIG. 2 is a partially omitted top view of the above embodiment. l...Frame, 3...Coarse movement stage, 3A...
Base, 3 B (3] 3. to 3I3n) ・Protrusion, ... Fine movement stage, 4 A (4A1 to 4 A n )-H passage space (
(hole), Fig. 5... Sample holding table, 6... X-axis coarse movement and quiet movement mechanism. 7...Y-axis coarse movement mechanism, 10...Connecting member,...X fine movement mechanism,...YM fine movement mechanism 14..., 4. , □8) Extending 4 knees, 1 Frame, 3 Coarse movement stage, 3A Base, 3 B (3B+-3BI+) Protrusion, 4 Fine movement stage, 4A (4A+~4A ,, 1. Penetration space (hole), 5. Sample holding table, 6.
X-axis fine movement drive mechanism, 13...Y-axis fine movement drive mechanism, 14
Z fine movement drive W & customization, 16...sample.

Claims (1)

[Claims] 1. A coarse movement stage movable in at least two dimensions of the X-axis and Y-axis, and a fine movement stage movable in three dimensions;
The coarse movement stage is independently arranged in a vertically penetrating space formed inside the fine movement stage, and the height positional relationship of the coarse movement stage and the fine movement stage is changed via a Z-axis drive mechanism to hold the sample. In the sample positioning device in which the stage can be switched between the coarse movement stage and the fine movement stage, the coarse movement stage includes a base supported by a coarse movement drive mechanism, and a state in which the coarse movement stage is distributed on the upper surface of the base. The through space inside the fine movement stage corresponds to the arrangement of the projections on the coarse movement stage side, and the base of the coarse movement stage is connected to the base of the fine movement stage. A sample positioning device characterized in that the plurality of protrusions function as a coarse movement stage by distributing the protrusions in a penetrating space inside the fine movement stage while positioning the protrusions downward. 2. The sample positioning device according to claim 1, wherein the through space formed inside the fine movement stage comprises a plurality of holes or notch-shaped grooves distributed in the fine movement stage. 3. The sample positioning device according to claim 1 or 2, wherein a chuck mechanism is provided on the upper surface of each protrusion of the coarse movement stage and on the upper surface of the fine movement stage to attract the sample stage in response to a control signal. 4. In any one of claims 1 to 3, the X-axis and Y-axis coarse movement drive mechanisms of the drive mechanism of the coarse movement stage are separated from a frame supporting the fine movement stage. A sample positioning device in which the X-axis and Y-axis coarse movement drive mechanisms and the coarse movement stage are connected via a connecting member. 5. In any one of claims 1 to 4, the coarse movement stage is supported via coarse movement drive mechanisms for each of the X-axis, Y-axis, and Z-axis, and among these, the coarse movement stage is ,Y
The shaft coarse movement drive mechanism is arranged separately from the frame supporting the fine movement stage, and the X-axis, Y-axis coarse movement drive mechanism and the coarse movement stage are connected to each other via a flexible elastic member. sample positioning device connected to the 6. In any one of claims 1 to 5, the fine movement stage is provided with fine movement drive mechanisms for X, Y, and Z axes, and the X and Y axes cooperate to move the shaft·
The Y-axis plane is finely rotated, and three Z-axis fine movement drive mechanisms are used to support the fine movement stage at three points, and the fine movement amount of each Z-axis fine movement drive mechanism is varied to control the inclination of the fine movement stage. A sample positioning device that makes this possible.