System for compensating dynamic and thermal deformity errors of linear motion single-plane gantry stage in real time, stage apparatus, manufacturing thereof, and measuring and inspection equipment

In a system for compensating dynamic and thermal deformity errors of a linear motion single-plane gantry stage in real time, a stage apparatus using the system, and manufacturing, measuring, and inspecting apparatuses using the system, the system includes: a first two-dimensional position measuring unit arranged in each of two linear edge beams respectively positioned in both sides of the linear motion single-plane gantry stage for measuring the position of an X-axially movable gantry beam to provide a feedback of an X-axial motion thereof; a second two-dimensional position measuring unit for measuring the position of a Y-axially movable slider movable on the X-axially movable gantry beam to provide a feedback of a Y-axial motion thereof; a thermal fixing point provided as a thermal reference for measuring a thermal expansion of the X-axially movable gantry beam; and a compensation control unit for controlling an error motion of the linear motion single-plane gantry stage in real time by measuring dynamic and thermal deformity errors based on the data received from the first and the second two-dimensional position measuring unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to Application No. 10-2013-0150059, filed in the Republic of Korea on Dec. 4, 2013, which is expressly incorporated herein in its entirety by reference thereto.

FIELD OF THE INVENTION

The present application relates to a system for compensating dynamic and thermal deformity errors of a linear motion single-plane gantry stage in real time, a stage apparatus, manufacturing thereof, and measuring and inspection equipment, and more particularly, for example, to a system for compensating dynamic and thermal deformity errors of a linear motion single-plane gantry stage in real time, which measures a linearity and a yaw error due to motions of the linear motion single-plane gantry stage and a thermal deformity error so as to control the real-time compensation for the measured linearity, yaw and thermal deformity errors, and to a stage apparatus applying the system and manufacture thereof, and to measuring and inspection equipment therefor.

BACKGROUND INFORMATION

A linear motion single-plane gantry stage, generally referred to as an H-type gantry stage, may be used in the field of high-speed scanning requiring high static and dynamic accuracy.

In such a linear motion single-plane gantry stage, a dynamic error due to linearity and yaw errors and a thermal deformity error due to thermal expansion influence the determination of the position of the gantry stage resulting in degradation of the accuracy and also of the product quality.

In order to resolve such problems, various techniques have been proposed, but a real-time compensation has not been considered.

SUMMARY

Example embodiments of the present invention provide for accurately measuring dynamic and thermal deformity errors in a linear motion single-plane gantry stage so as to provide real-time compensation.

According to an example embodiment of the present invention, a system for compensating dynamic and thermal deformity errors of a linear motion single-plane gantry stage in real time includes: a first two-dimensional position measuring unit arranged in each of two linear edge beams respectively positioned in both sides of the linear motion single-plane gantry stage for measuring the position of an X-axially moving gantry beam to provide a feedback of an X-axial motion thereof; a second two-dimensional position measuring unit for measuring the position of a Y-axially moving slider moving on the X-axially moving gantry beam to provide a feedback of a Y-axial motion thereof; a thermal fixing point provided as a thermal reference for measuring a thermal expansion of the X-axially moving gantry beam; and a compensation control unit for controlling an error motion of the linear motion single-plane gantry stage in real time by measuring dynamic and thermal deformity errors based on the data received from the first and the second two-dimensional position measuring unit.

Thus, there is provided a system for compensating dynamic and thermal deformity errors of a linear motion single-plane gantry stage in real time, which measures a linearity and a yaw error due to motions of the linear motion single-plane gantry stage and a thermal deformity error so as to control the real-time compensation for the measured linearity, yaw and thermal deformity errors, and to a stage apparatus applying the system, and to manufacturing, measuring and inspection equipment therefor.

DETAILED DESCRIPTION

Example embodiments of the present invention are described in more detail with reference to the appended Figures. Components having the same or similar functions are referred to by the same reference numerals.

It should be understood that the expression that a certain part is connected to another part refers not only a direct connection but also an indirect connection through another component. Furthermore, the expression of including a certain part refers to the inclusion of additional components, unless described to the contrary.

FIG. 1schematically illustrates a system for compensating dynamic and thermal deformity errors of a linear motion single-plane gantry stage in real time according to an example embodiment of the present invention, andFIG. 2is a front view of a system for compensating dynamic and thermal deformity errors of a linear motion single-plane gantry stage in real time according to an example embodiment of the present invention.

Referring toFIGS. 1 and 2, a linear motion single-plane gantry stage100on which a system200for compensating dynamic and thermal deformity errors in real time is mounted includes a base110and two linear edge beams121,122respectively positioned in both sides of the top of the base110, which support a plurality of vertical air bearings131and a plurality of horizontal air bearings132for supporting an X-axially and Y-axially movable assembly. In this case, the position of the vertical air bearings131and the horizontal air bearings132can be determined based both on the cost function for improving the control bandwidth and on the view of mechanical design for improving the intrinsic frequency of the system.

The X-axial motion is performed by an X-axially movable gantry beam140. The X-axially movable gantry beam140is held by two moving carriages151,152supported by a plurality of the vertical air bearings131and a plurality of the horizontal air bearings132, and the two moving carriages151,152are X-axially driven by two drive motors161,162. In this case, one (hereinafter referred to as a master shaft) of the two linear edge beams121and122has a greater stiffness than the other (hereinafter referred to as a slave shaft). In other words, the moving carriage151of the master shaft is firmly mounted by the vertical and the horizontal air spring131and132.

The Y-axial motion is performed by an Y-axially movable slider170moving along the X-axially movable gantry beam140, and the Y-axially movable slider170is Y-axially driven by two drive motors181,182.

The system200for compensating dynamic and thermal deformity errors in real time which is mounted on the linear motion single-plane gantry stage100includes a two-dimensional position measuring unit210for providing an X-axial feedback, a two-dimensional position measuring unit220for providing an Y-axial feedback, a thermal fixing point230, and a compensation control unit (seeFIGS. 5 and 6).

The two-dimensional position measuring unit210for providing an X-axial feedback is provided to each of the two linear edge beams121,122so as to measure an X-axial motion, and includes a two-dimensional encoder scale211, a motional direction encoder head212, a vertical direction encoder head213, and an encoder mounting block214.

The two-dimensional encoder scale211is mounted on the base110at both ends of the X-axially movable gantry beam140to measure an X-axial motion, and as described below with reference toFIG. 3, includes a two-dimensional lattice to make a measurement both in the motional direction and in the vertical direction.

The motional direction encoder head212and the vertical direction encoder head213are adapted to measure respectively the displacement in the motional direction and in the vertical direction from the two-dimensional lattice of the two-dimensional encoder scale211.

The encoder mounting block214is adapted to mount the motional direction encoder head212and the vertical direction encoder head213on the X-axially movable gantry beam140.

The two-dimensional position measuring unit220for a Y-axial feedback is adapted to measure a Y-axial motion of the Y-axially movable slider170, and includes a two-dimensional encoder scale221, a motional direction encoder head222, a vertical direction encoder head223, and an additional vertical direction encoder head224for measuring a yaw error.

The two-dimensional encoder scale221is mounted on each of both sides of the X-axially movable gantry beam140to measure a Y-axial motion, and as described below with reference toFIG. 3, includes a two-dimensional lattice to make a measurement both in the motional direction and in the vertical direction.

The motional direction encoder head222and the vertical direction encoder head223are adapted to measure respectively the displacement in the motional direction and in the vertical direction from the two-dimensional lattice of the two-dimensional encoder scale221.

Also, an additional vertical encoder head224is provided to measure a yaw during Y-axial movement. A specific method of measuring a yaw by using the vertical encoder head224is described below with reference toFIG. 4. A measured yaw error may be compensated for by using two servo shafts including the drive motors161,162and the two motional encoder heads212.

The thermal fixing point230is provided as a thermal reference for a thermal expansion of the X-axially movable gantry beam140, fixedly positioned at one end of the two-dimensional encoder scale221included in the two-dimensional position measuring unit220for a Y-axial feedback and immediately above the vertical direction encoder head213included in the two-dimensional position measuring unit210for an X-axial feedback. Accordingly, only at the one end of the two-dimensional encoder scale221is provided a thermal offset readily measured by the single vertical direction encoder head213. In addition, the two-dimensional encoder scale221may be made of a material with a low CTE (coefficient of thermal expansion) such as Zerodur, thus keeping a high accuracy even under a great thermal change throughout the processing region.

The measured value by the vertical direction encoder head213of the two-dimensional position measuring unit210for X-axial feedback is used to provide in real time a signal for compensating both a dynamic linearity error generated upon X-axially driving toward the Y-axially movable slider170driven by two servo shafts including drive motors181,182and the two motional direction encoder heads222and a thermal offset error generated according to a temperature change.

FIG. 3schematically illustrates the structure of the two-dimensional position measuring unit provided in a system for compensating dynamic and thermal deformity errors of a linear motion single-plane gantry stage in real time.

As illustrated inFIG. 3, the two-dimensional encoder scale211includes a two-dimensional lattice for making a measurement both in the motional direction and in the vertical direction. And in the two-dimensional encoder scale211, the motional encoder head212is arranged on the motional direction measurement lattice part, and the vertical direction encoder head213on the vertical direction measurement lattice part.

The motional direction encoder head212and the vertical direction encoder head213measure accuracy and linearity respectively according to the motional direction and the vertical direction to provide the result to the compensation control unit for a feedback.

FIG. 4illustrates in detail the structure of the Y-axially movable slider in a system for compensating dynamic and thermal deformity errors of a linear motion single-plane gantry stage in real time.

Referring toFIG. 4, two two-dimensional encoder scales221-1,221-2may be mounted on both sides of the X-axially movable gantry beam140.

One two-dimensional encoder scale221-1includes a motional direction encoder head222-1, a vertical direction encoder head223-1, and an additional vertical direction encoder head224, while the other two-dimensional encoder scale221-2includes a motional direction encoder head222-2, and a vertical direction encoder head223-2.

In this case, a yaw error of the Y-axially movable slider may be measured based on the relative distance between the vertical direction encoder head223-1and the additional vertical direction encoder head224.

FIG. 5illustrates the linearity error compensation algorithm by a system for compensating dynamic and thermal deformity errors of a linear motion single-plane gantry stage in real time.

Referring toFIG. 5, the control unit240of the system200for compensating dynamic and thermal deformity errors in real time performs a stage mapping241by receiving a signal from the motional direction encoder head of the X-axial master shaft, and adds the result to a signal (namely, measured linearity error) received from the vertical direction encoder head of the X-axial master shaft in step242.

Then, the output signal of step242is filtered through step243, updating the control loop of the Y-axial master and slave shaft as a reference signal for a linearity error. In this case, the filtering of the output signal from step242is made by using a low pass filter so as to eliminate high frequency noise components, thus producing a low frequency linearity error signal. The filter parameter can be optimized considering the reaction force of the moving slider, the stage dynamic response, and the control bandwidth of the moving slider during the dynamic compensation process.

Thereafter, the control loop of the Y-axial master and the slave shaft subtracts respectively the signal received from the motional direction encoder head of the Y-axial master shaft and the signal received from the motional direction encoder head of the Y-axial slave shaft from the value obtained by adding the target position signal244and the reference signal for the linearity error in steps245,247so as to generate respective control signals delivered through respective PID (proportional-integral-derivative) controllers246,247to the drive motors for the Y-axial master shaft and the Y-axial slave shaft.

Although the linearity error compensation algorithm is described with reference toFIG. 5, the thermal deformity error compensation may also performed in the same manner as the linearity error compensation algorithm.

FIG. 6illustrates a yaw error compensation algorithm by a system for compensating dynamic and thermal deformity errors of a linear motion single-plane gantry stage in real time.

Referring toFIG. 6, the control unit250of the system200for compensating dynamic and thermal deformity errors in real time calculates the difference between the signal received from the vertical direction encoder head of the Y-axial master shaft and the signal received from the additional vertical direction encoder head in step251.

Then, the resulting output signal is filtered through step252. In this case, the filtering of the output signal is made by using a low pass filter so as to eliminate the high frequency noise component due to the motions of the moving slider, thus producing a low frequency yaw error signal. The filter parameter can be optimized considering the reaction force of the gantry beam, the stage dynamic response, and the control bandwidth of the gantry beam during the desired scan motion and the dynamic compensation process.

Thereafter, the filtered result is scaled using a factor lg/(2·lc) in step253. In this case, lc is the distance between the vertical direction encoder head of the Y-axial master shaft and the additional vertical direction encoder head, and lg the distance between the vertical direction encoder head of the X-axial master shaft and the vertical encoder head of the slave shaft (seeFIG. 2).

Then, the output signal of step253updates the control loop of the X-axial master and the slave shaft as a reference signal for a yaw error.

Thereafter, the control loop of the X-axial master and the slave shaft subtracts respectively the signal received from the motional direction encoder head of the X-axial master shaft and the signal received from the motional direction encoder head of the X-axial slave shaft in steps255,258from the value obtained respectively by adding and subtracting the reference signal for the yaw error to and from the target position signal (or vice versa) in steps254,257so as to generate respective control signals delivered through respective PID (proportional-integral-derivative) controllers256,259to the drive motors for the X-axial master shaft and the X-axial slave shaft.

The linear motion single-plane gantry stage using the above-described system for compensating dynamic and thermal deformity errors may be used in all apparatuses for manufacturing, measuring, or inspecting a semiconductor, LCD, LED, OLED, AMOLED, PCB, solar cell, CNT, ceramic material, chemical material, textile material, bio material, etc.

It should be understood that the foregoing description is not intended to be limiting and that substitutions, modifications, and alterations may be made without departing from the spirit and scope hereof.

LIST OF REFERENCE NUMERALS