JPH04254317A - Semiconductor exposure aligner - Google Patents

Abstract

PURPOSE:To enable rotary correction of high precision, by a method wherein, when an X-Y stage is moved in one direction at the time of reference position correction of rotary direction, the stage is locked in order not to move in a direction of the other axis. CONSTITUTION:Laser interferometers 1, 2 are reset, and a theta rotary mechanism 6 and the laser interferometers 1, 2 are initialized, which are arranged at the starting position of measurement by moving an X-Y stage 4. In this state, the air only on the single side of an X stage 4 is turned OFF, thereby bringing an X guide into close contact with the inner surface single side of the X stage 4. Then an X axis interferometer is turned OFF, and yawing control is performed by moving and controlling the Y stage 4. Then parallel deviation and the like are calculated in the state that the X stage 4 is fixed, and the yawing component of the Y guide and the rotary variation component of a thetarotary table 5 are eliminated. Thereby accurate rotary correction value can be obtained.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to an exposure apparatus for forming patterns on flat objects such as semiconductor wafers or liquid crystal display panels, and particularly for manufacturing high-density integrated circuit chips such as semiconductor memories and arithmetic devices. The present invention relates to an exposure positioning apparatus that can perform highly accurate exposure by accurately holding the posture of an exposed object such as a wafer on which a circuit pattern is to be printed.

0002

2. Description of the Related Art Conventionally, this type of apparatus, for example, an exposure apparatus such as a stepper that projects a pattern drawn on a reticle onto a wafer, is equipped with a function to align the reticle and the wafer. Exposure was performed after alignment.

[0003] Such alignment is generally performed by measuring the amount of misalignment between an original plate such as a reticle on which a pattern to be projected is drawn and an object to be exposed such as a wafer, and adjusting the position of the object based on the result. This has been done by moving the exposed object under laser length measurement control or by moving the original plate and the object to be exposed.

[0004]The device (wafer stage) is positioned using laser beams for each of the X and Y axes, and two laser beams are incident parallel to one axis of the table to detect yawing (rotation) fluctuation components. Was. By the value of this one set (two) laser beams,
Yawing fluctuation components were detected and controlled during movement in the Y plane.

However, in such an XYθ positioning device using interferometer control, the means for returning the origin position when the laser interferometer is reset is a photo SW.
Therefore, there was a problem with its reproducibility (especially in the direction of rotation). Therefore, the relative position of the reticle and the reference mark provided on the wafer stage has been measured to compensate for the fluctuations in the reference mirror surface during reset or over a long period of time. The measurement can be performed using various known methods, such as directly measuring the reticle and reference mark with printing light, or measuring the reticle and wafer with a third eye (detector), and There is a method in which marks on a reticle are directly printed on a wafer stage and the printed pattern is measured with a third eye.

In particular, in situations where it is difficult to detect marks through a projection lens, such as with an excimer stepper, it has always been necessary to directly print the reticle for measurement and correction.

For this purpose, the movement of the wafer stage is controlled only in the Y direction with reference to the guide surface of one axis (for example, the Y axis), and the interferometer on the other axis (X axis) is used only for measurement, so that the movement relative to the Y guide axis is controlled. By detecting the rotational component and feeding back its value to the two axes of yawing measurement, rotational component correction can be performed automatically.

Such a rotational fluctuation correction technique is disclosed, for example, in Japanese Patent Laid-Open No. 61-251028, which was proposed by the applicant of the present application.

[0009]

[Problem to be solved by the invention] However, one shaft (
For example, the means for restricting the other axis (X-axis) in the X direction when moving (Y-axis) relies only on the rigidity of the machine structure, so the mechanical shift and fluctuation components of the stage can cause There was a problem that the direction could not be measured correctly.

Particularly in the case of a static pressure stage, there is a problem in that measurement itself cannot be performed because control in a direction perpendicular to the direction of movement is turned off.

In view of the above-mentioned problems, the present invention makes it possible to easily correct rotational fluctuations due to interferometer reset and mirror changes over time even in a static pressure stage by self-diagnosis, and to achieve extremely high precision and stability. The purpose of the present invention is to provide a positioning device that can perform precise alignment.

0012

[Means and effects for solving the problem] In order to achieve the above object, the drive unit of the axis perpendicular to the moving direction is locked when measuring the rotational direction error, and the fluctuation component to the side perpendicular to the moving direction is removed. , to ensure that the values measured by the interferometer are accurate.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory diagram of the configuration of an embodiment of the present invention, showing a reduction projection exposure apparatus (stepper). In the figure, 8 is a lens, 9 is a reticle, and the components other than these two members constitute a wafer stage system. FIG. 2 shows, according to the present invention,
In the example of the stage, a static pressure type wafer stage is shown.

1 and 2 are laser interferometers, 3 is a mirror (measured surface X, Y), and 4 is an XY table (X, Y stage).
, 5 is a θ rotation table, 6 is a rotation drive mechanism made of a piezoelectric element, 7 is an XY drive unit (motor), and 10 is a control box including a drive circuit and the like. The laser interferometer 2 is installed here in the Y direction.

FIG. 3 shows a cross section of the X table portion of FIG. 2. For the X stage 4, 15 is a nipple for supplying air, and 16 is an air supply plate.

The means for measuring yawing is not limited to laser length measurement, but it is also possible to use a collimator or the like.

When the laser interferometers 1 and 2 are reset, the rotational drive mechanism 6 drives them to their initial positions. In this state, the rotational directions of the interferometers 1 and 2 are also initialized, so the accuracy of their reproduction becomes a problem.

Therefore, the X-direction interferometer of the air guide shown in FIG. 2 is turned off, and the X stage 4 is fixed to the X guide by air (self-locking).

Specifically, as shown in FIG. 4(A), the air supplied from the nipples 15-■,
), turn on the air supply only to nipple 15-■.
Make it FF. Then, the X stage 4 moves the nipple 15-
■The top is placed on the surface plate by the air supplied from the X guide 12.
The air supply plate 16-2 and the X guide 12 are brought into close contact with each other. In this state, measurement control is performed only in the Y direction, and the linear motor 7 is driven along the Y guide 12. At this time, the parallel deviation with the Y guide is calculated based on the reference mirror surface measurement value in the X direction, and the value is sent as a correction value to the interferometers 1 and 2, and the reference for the rotation direction is determined by moving the rotation mechanism 6. .

At this time, if yawing control is performed using the laser interferometers 1 and 2 so that the rotation mechanism in the Y direction does not fluctuate, the yawing component of the Y guide and the rotation fluctuation component of the θ rotary table can be removed from the measurement. This allows for more accurate rotation correction. This series of steps is shown in the flowchart of FIG.

In FIG. 5, first, the laser interferometer is reset (step 31), and the θ rotation mechanism and laser interferometer are initialized (steps 32, 33). Subsequently, the XY stage is moved and placed at the measurement start position (step 34). In this state, as described above, turn off the air on only one side of the X stage, and bring the X guide into close contact with one side of the inner surface of the
5). Now turn off the X-axis interferometer (step 36)
, and control the movement of the Y stage (step 37), and perform yawing control (step 38). At this time, with the X stage fixed and the yawing component of the Y guide and the rotational fluctuation component of the θ rotary table removed, parallel deviation etc. are calculated as described above, and accurate rotation correction values are obtained (steps 39 to 39). 44).

[0022] The above example is based on the Y guide, but
The same thing can be said even if the X guide side is used as a reference.

Furthermore, if the parallelism between the guide surface and the reticle surface is guaranteed in advance, or if the residual difference is known, it is possible to always guarantee the parallelism of the reticle.

Although the above embodiments have been described on the wafer stage side, the same applies to the reticle side. FIG. 3 shows a configuration example in which a position measuring means similar to that in FIG. 1 is provided on the reticle stage side.

Further, although the above embodiment is an example of a wafer stage using a static pressure guide, the same can be said of a stage whose guide surface is sliding or rolling.

Furthermore, although the above embodiment assumes a stage that performs yawing control, if it is limited to mechanical changes over time such as in the mirror mounting portion, it can be used as a rotational fluctuation check. The single-axis stage can also be used as a regular check function.

[0027]

[Effects of the Invention] As explained above, according to the present invention,
The rotational origin reproducibility error when resetting the interferometer and the rotational fluctuation component due to changes over time in the mirror mounting part (if the interferometer is not reset) can be detected by automatic measurement using your own interferometer, rather than by direct exposure using a printing light. Can be easily corrected. Furthermore, since it is possible to remove the yawing component of the guide portion during measurement, it is possible to perform rotation correction with extremely high accuracy.

From the above, it is possible to provide a high-precision positioning device such as a stepper that has extremely high overlay accuracy, high productivity, and high flexibility.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the configuration of an exposure apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a static pressure wafer stage according to an embodiment of the present invention.

FIG. 3 is a configuration explanatory diagram of another embodiment of the present invention.

FIG. 4 is an explanatory diagram of the operation of the embodiment of the present invention.

FIG. 5 is a flowchart of an embodiment of the invention.

[Explanation of symbols]

1, 2 Laser interferometer 3 Mirror 4 XY table (X stage, Y stage) 5
θ rotation table (fine movement stage) 6 θ rotation drive mechanism 7 Drive motor (X motor, Y motor) 8
Projection lens 9 Reticle 10 Control box 11 Wafer chuck 12 Guide (Y guide, X guide) 14 Wafer

Claims (2)

[Claims] 1. An original plate having a pattern to be exposed and transferred, an exposed object onto which the pattern is projected, positioning means for mutually positioning the original plate and the exposed object, and the original plate or the exposed object is mounted. an XY table, a rotary table rotatable in a plane parallel to the XY plane, a position detection means for detecting the position of the original plate or the exposed object in each of the X and Y directions, a rotation control means for the rotary table, and the position In an apparatus equipped with a calculation means for correcting the reference position in the rotational direction at the time of resetting the rotary table based on the detection result of the detection means, when the XY stage is moved in one direction when correcting the reference position in the rotational direction, A semiconductor exposure device characterized by locking the stage so that it does not move toward the other axis. 2. When moving the XY table along one direction of the 2. The semiconductor exposure apparatus according to claim 1, wherein fluctuations in the guide and rotational drive mechanism are removed by actively performing yawing control.