CN103197517B - Workbench balancing-mass mass-center measuring and correcting method - Google Patents

Abstract

The invention relates to a workbench balancing-mass mass-center measuring and correcting method comprising the steps that: the balancing-mass is adopted as a testing and correcting object; horizontal X, Y degrees of freedom (DOF) are in opened ring, and an Rz DOF is in a closed ring; a trajectory is provided for the balancing-mass; balancing-mass zero-speed section displacement measurement output is collected; the balancing-mass displacement data is processed, such that balancing-mass horizontal three-DOF displacement values are obtained; the data obtained by processing is introduced into a mass-center measuring and correcting method, such that an eccentricity amount of the balancing-mass mass-center relative to a centroid is obtained. According to the invention, a mass-center deviation of the balancing-mass mass-center relative to a physical sensor measuring center is determined through the measurement values of the balancing-mass physical sensor. The method is simple and practical. With the method, no additional testing device is needed.

Description

A kind of work-piece platform balancing quality center of mass detection calibration method

Technical field

The present invention relates to photoetching technique, particularly relate to a kind of work-piece platform balancing quality center of mass detection calibration method.

Background technology

Lithographic equipment be a kind of by mask pattern exposure image to the equipment on silicon chip.Known lithographic equipment comprises stepping repetitive and step-by-step scanning type lithographic equipment.The aspect weighing of these lithographic equipments important is exactly accuracy, namely between the light period will the parts of movement can the accuracy of movement, described will the parts of movement have: the mask platform of carrying mask pattern, the silicon wafer stage of carrying silicon chip.Generally, position all can be adopted to feed back, utilize the control system based on PID (proportional-integral-differential) of standard to control.Simultaneously, in order to obtain the position accuracy of Nano grade, and response time fast, just require that lithographic equipment has larger acceleration and the impact less to measuring basis framework, and these two indexs are conflicting often, so, in many lithographic equipments, all adopt the structure of silicon wafer stage-balance mass, silicon wafer stage motor produces the requirement that larger acceleration meets response fast, the counter-force of silicon wafer stage motor is applied in balance mass, and balance mass counter motion absorbs the impact of silicon wafer stage, meets the requirement to the less impact of measuring basis framework.Silicon wafer stage-balance mass system, in motion process, meets barycenter conservation.In reality, balance mass motor drives center to be center of mass point, but measuring center often gets centroid point, like this, when realization controls, just there is the conversion of control signal from position of form center to centroid position, this conversion is closely related with the position deviation of the centre of form with barycenter, if barycenter and position of form center well do not survey school, the words that deviation is larger, control performance would not reach the precision of needs, and the excessive of motor can be caused to exert oneself, and produces larger heat power consumption.So in order to obtain good lithographic equipment performance, the barycenter of balance mass needs accurate calibration.

Summary of the invention

For above-mentioned technical matters, the basic ideas of detection calibration barycenter of the present invention are, in silicon wafer stage-balance mass system, balance mass is under the effect of silicon wafer stage motor counter-force and the motor move under influence of balance mass own, and its moving displacement is detected by corresponding measuring mechanism.Take separately balance mass as research object, balance quality Rz axle and add closed-loop control, its feedback signal is measured conversion by testing agency above-mentioned and is obtained.X and the Y degree of freedom direction open loop of balance mass does not control.When only giving Rz to injection movement locus signal, if the barycenter of balance mass and the centre of form (i.e. the measuring center of measuring mechanism) level are to when overlapping completely, measuring through measuring mechanism the measured value converting the balance mass Rz degree of freedom obtained is follow input trajectory value, and the measured value of X and Y degree of freedom should be zero.But, when the barycenter of balance mass and the centre of form do not overlap, namely when there is X and (or) Y-direction eccentric relative to the centre of form in barycenter, X and (or) the Y-direction of measuring the value that conversion obtains have certain displacement output, and the size that this displacement exports and the angle that Rz rotates and barycenter relevant relative to the bias of centre of form X, Y-direction, we can obtain the bias of the relative centre of form of barycenter by the rotational movement amount of mobile of the output of survey sensor and Rz thus.

Accordingly, the present invention proposes a kind of method that barycenter surveys school, school can be surveyed by balance mass position transducer and go out the barycenter of balance mass under centre of form coordinate system, by the barycenter conservation of silicon wafer stage-balance mass system, obtain the movement locus of the barycenter of silicon wafer stage further.

The work-piece platform balancing quality center of mass detection calibration method that the present invention proposes, has following steps:

Step one, generate N group Rz track for balance mass, set full test number of times M;

Step 2, barycenter deviation delta x, Δ y are zero when supposing initial, and setting XY is to the searching threshold spec_x of barycenter and spec_y;

The test model of step 3, selection X, Y, Rz axle, is updated in test model by Δ x now, Δ y value, selects one group of Rz track, be injected into test model;

Step 4, testing results model, be balanced quality zero-speed section shift measurement and export, and then the displacement obtaining XYRz Three Degree Of Freedom exports x_pos_cg, y_pos_cg and rz_pos, according to formula: $\left\{\begin{array}{c}\mathrm{\Δy}=\frac{x\_\mathrm{pos}\_\mathrm{cg}}{\mathrm{rz}\_\mathrm{pos}}\\ \mathrm{\Δx}=-\frac{y\_\mathrm{pos}\_\mathrm{cg}}{\mathrm{rz}\_\mathrm{pos}}\end{array}\right.$ Calculate Δ x now, Δ y value record;

Step 5, input next group Rz track, repeat step 3 and step 4, obtain different Δ x, Δ y value record;

After step 6, record N sub-value, be averaging, obtain this group tested after barycenter deviation delta x, Δ y value;

Step 7, judge whether to complete M test, if do not complete, then to the Δ x obtained, Δ y, compare with searching threshold spec_x, the spec_y of setting respectively, if Δ x, Δ y are all less than searching threshold, then think that surveying school completes, and confirm that the side-play amount of barycenter is Δ x, Δ y; If at least one great-than search threshold value in Δ x, Δ y, Δ x now, Δ y value are substituted into test model, repeats step 3 ~ six, until Δ x, Δ y value are less than the searching threshold of setting, complete and survey school; Or until testing time is greater than the testing time M of setting, completes and survey school.

Wherein, described track is the three rank movement locus comprising the kinematic parameters such as displacement, speed and acceleration.

Wherein, described test model is open loop at XY axle, is closed loop at Rz axle.

Wherein, grating scale is utilized to realize the closed loop of described Rz axle.

Wherein, described grating scale is two-dimensional grating chi.

Barycenter detection calibration method of the present invention determines the barycenter deviation at balance mass barycenter relative physics sensor measurement center by the measured value of balance mass physical sensors, the method is simple and practical, and not needing increases extra proving installation.

Accompanying drawing explanation

Can be further understood by following detailed Description Of The Invention and institute's accompanying drawings about the advantages and spirit of the present invention.

Figure 1 shows that the structural representation of the silicon wafer stage in the lithographic equipment that method of the present invention is used;

Figure 2 shows that the fundamental block diagram of the closed-loop control that method of the present invention is used;

Figure 3 shows that the structural representation of the balance mass measuring mechanism that method of the present invention adopts;

Figure 4 shows that balance mass barycenter of the present invention surveys school and online compensation control block diagram;

Figure 5 shows that in a simulation example, at balance mass Rz to closed loop, join the example of the movement locus of Rz axle;

Figure 6 shows that in above-mentioned simulation example, at balance mass Rz to closed loop, and when adding 1mrad movement locus, balance mass level is to the displacement output map of each degree of freedom;

Figure 7 shows that balance mass barycenter test flow chart of the present invention.

Embodiment

Specific embodiments of the invention are described in detail below in conjunction with accompanying drawing.

Figure 1 shows that the structural representation of the silicon wafer stage in the lithographic equipment that method of the present invention is used.The silicon chip be exposed is placed on micropositioner 101, and micropositioner 101 is placed on coarse motion platform 102, uses auxiliary connection 106 to connect between them, and this auxiliary connection can be the multiple auxiliary connections such as air-bearing connection, magnetic bearing connection.Micropositioner 101 can move on the six degree of freedom of space.Coarse motion platform 102 is placed in balance mass 103, uses auxiliary connection 106 to connect between them.Balance mass 103 is placed on basic framework 104.Gage frame 105 is also had on basic framework 104.Balance mass 103 with basic framework 104, all use auxiliary connection 106 to be connected between basic framework 104 with gage frame 105.Described auxiliary connection 106 can adopt the multiple connected modes such as air-bearing connection, magnetic bearing connection.Basic framework 104 is directly placed on ground 107.

In the present embodiment, in order to the silicon chip on energy accurately quick position micropositioner 101, gage frame 105 measures the position of micropositioner 101 relative to gage frame 105, and feed back, compare with micropositioner 101 movement locus of setting, obtain measured deviation, feedback controller carries out adjustment to deviation signal and amplifies, obtain control signal, micropositioner actuator drives micropositioner 101 to move according to control signal, forms close loop control circuit.

But the closed loop Long Distances motion only by micropositioner 101 does not reach the positioning precision of needs often, so add coarse motion platform 102, the mode adopting rough micro-moving mechanism to combine realizes quick high accuracy location.Adopt balance mass 103 counter motion to reduce the external interference of whole silicon wafer stage system simultaneously.Coarse motion platform 102 and balance mass 103 arrange close loop control circuit equally, utilize optical grating ruler measurement coarse motion platform 102 relative to the position of balance mass 103, utilize optical grating ruler measurement balance mass 103 relative to the position of basic framework 104.Concrete closed control loop can shown in reference diagram 2, wherein track setting module 201 sets the movement locus of Moving Objects module 204, survey sensor module 205 measures the actual motion track of Moving Objects module 204, actual motion track is compared with the movement locus of setting and obtains position error signal 206, position error signal 206 is sent to feedback controller module 202, obtain control signal 207 and control signal is transferred to executor module 203, executor module 203 controlled motion object module 204 moves, survey sensor module 205 again measure Moving Objects module 204 actual motion track and with setting movement locus compared with, and repeat said process, until finally locate.

According to introduction above, in order to realize high-speed, high precision location, need the accurate location of the barycenter relative equilibrium quality centre of form being balanced quality.

Figure 3 shows that the structural representation of the balance mass measuring mechanism that method of the present invention adopts, in figure, SN1 and SN2 is that balance mass measures grating scale, wherein each grating scale SN1 or SN2 is two-dimensional grating chi, namely can measure balance mass in diagram X-direction and the displacement illustrating Y-direction simultaneously, the ruler of grating scale is arranged in the external frame of balance mass lower floor, and its read head is arranged in balance mass.In figure, grey blockage represents measurement initial position, white blockage represent balance mass rotate to an angle after measuring position.Ly1 and Lx1 is the distance that SN1 arrives X-axis and Y-axis, Ly2 and Lx2 is the distance that SN2 arrives X-axis and Y-axis.The circle of filling grid in figure represents balance mass centroid position, and Δ x is respectively the bias of the relative centre of form of balance mass barycenter with Δ y, and wherein centroid point is just at coordinate origin.

If: the measured value of balance mass grating scale SN1, SN2 is: x1, y1 and x2, y2

The logic axial translation value of the balance mass centre of form is: x_pos, y_pos, rz_pos

The logic axial translation value of balance mass barycenter is: x_pos_cg, y_pos_cg, rz_pos_cg

When there is not bias in balance mass, namely when barycenter and the centre of form overlap, Δ x and Δ y is zero, the physical measurements values of balance mass SN1 and SN2 (is expressed as x1, y1 and x2, y2) pass and between the shift value of balance quality center of mass (i.e. the centre of form) logic axle (X to shift value x_pos, Y-direction shift value y_pos, Rz is to shift value rz_pos) is:

$\left\{\begin{array}{c}x\_\mathrm{pos}=x1\frac{\mathrm{Ly}2}{\mathrm{Ly}1+\mathrm{Ly}2}+x2\frac{\mathrm{Ly}1}{\mathrm{Ly}1+\mathrm{Ly}2}\\ y\_\mathrm{pos}=y1\frac{\mathrm{Lx}2}{\mathrm{Lx}1+\mathrm{Lx}2}+y2\frac{\mathrm{Lx}1}{\mathrm{Lx}1+\mathrm{Lx}2}\\ \mathrm{rz}\_\mathrm{pos}=\frac{x2-x1}{\mathrm{Ly}1+\mathrm{Ly}2}=\frac{y1-y2}{\mathrm{Lx}1+\mathrm{Lx}2}\end{array}\right.$ Formula (1).

When Δ x and Δ y is non-vanishing, when namely the barycenter of balance mass and the centre of form do not overlap, the pass between the measured value of balance mass SN1 and SN2 and balance quality center of mass logic axial translation value is:

$\left\{\begin{array}{c}x\_\mathrm{pos}\_\mathrm{cg}=x1\frac{\mathrm{Ly}2-\mathrm{\Δy}}{\mathrm{Ly}1+\mathrm{Ly}2}+x2\frac{\mathrm{Ly}1+\mathrm{\Δy}}{\mathrm{Ly}1+\mathrm{Ly}2}\\ y\_\mathrm{pos}\_\mathrm{cg}=y1\frac{\mathrm{Lx}2-\mathrm{\Δx}}{\mathrm{Lx}1+\mathrm{Lx}2}+y2\frac{\mathrm{Lx}1+\mathrm{\Δx}}{\mathrm{Lx}1+\mathrm{Lx}2}\\ \mathrm{rz}\_\mathrm{pos}\_\mathrm{cg}=\frac{x2-x1}{\mathrm{Ly}1+\mathrm{Ly}2}=\frac{y1-y2}{\mathrm{Lx}1+\mathrm{Lx}2}\end{array}\right.$ Formula (2).

Formula (1) and formula (2) associating can obtain:

$\left\{\begin{array}{c}x\_\mathrm{pos}\_\mathrm{cg}=x1\frac{\mathrm{Ly}2-\mathrm{\Δy}}{\mathrm{Ly}1+\mathrm{Ly}2}+x2\frac{\mathrm{Ly}1+\mathrm{\Δy}}{\mathrm{Ly}1+\mathrm{Ly}2}=x\_\mathrm{pos}+\frac{x2-x1}{\mathrm{Ly}1+\mathrm{Ly}2}\mathrm{\Δy}=x\_\mathrm{pos}+\mathrm{rz}\_\mathrm{pos}\·\mathrm{\Δy}\\ y\_\mathrm{pos}\_\mathrm{cg}=y1\frac{\mathrm{Lx}2-\mathrm{\Δx}}{\mathrm{Lx}1+\mathrm{Lx}2}+y2\frac{\mathrm{Lx}1+\mathrm{\Δx}}{\mathrm{Lx}1+\mathrm{Lx}2}=y\_\mathrm{pos}+\frac{y2-y1}{\mathrm{Lx}1+\mathrm{Lx}2}\mathrm{\Δx}=y\_\mathrm{pos}-\mathrm{rz}\_\mathrm{pos}\·\mathrm{\Δx}\end{array}\right.$

And then can obtain:

$\left\{\begin{array}{c}\mathrm{\Δy}=\frac{x\_\mathrm{pos}\_\mathrm{cg}-x\_\mathrm{pos}}{\mathrm{rz}\_\mathrm{pos}}\\ \mathrm{\Δx}=-\frac{y\_\mathrm{pos}\_\mathrm{cg}-y\_\mathrm{pos}}{\mathrm{rz}\_\mathrm{pos}}\end{array}\right.$ Formula (3)

When Rz adds movement locus to closed loop, and X, Y-direction do not add track (namely set displacement be zero) and open loop time, the displacement x _ pos of X and Y-direction, y_pos are zero.If sensor measurement is to balance mass when X or Y-direction have displacement, this displacement causes because the centre of form and barycenter do not overlap, and namely the relative centre of form coordinate system of barycenter has displacement.Like this, formula (3) can be expressed as further:

$\left\{\begin{array}{c}\mathrm{\Δy}=\frac{x\_\mathrm{pos}\_\mathrm{cg}}{\mathrm{rz}\_\mathrm{pos}}\\ \mathrm{\Δx}=-\frac{y\_\mathrm{pos}\_\mathrm{cg}}{\mathrm{rz}\_\mathrm{pos}}\end{array}\right.$ Formula (4)

As can be seen from formula (4), as long as under we obtain inclined barycenter, the displacement of balance mass X and Y degree of freedom exports, in conjunction with Rz to movement locus, just can calculate the offset of the relative centre of form of balance mass barycenter.

The process flow diagram surveying school below in conjunction with the balance mass barycenter shown in Fig. 7 is described the flow process that barycenter surveys school.This flow process has following steps:

Step one, generate N (N be " 5 " in the present embodiment) for balance mass and organize Rz track, in the present embodiment, this track is the three rank movement locus comprising the kinematic parameters such as displacement, speed and acceleration, sets full test number of times M (in the present embodiment M as " 20 ");

Step 2, barycenter deviation is zero when supposing initial, and namely Δ x, Δ y are zero; Setting XY is to the searching threshold spec_x of barycenter and spec_y, and this threshold value is used for judging whether to proceed search, when the Δ x after searching for, Δ y value are less than threshold value, think and has searched actual barycenter, search for and just can terminate; When the Δ x after searching for, Δ y value are more than or equal to threshold value, then continue search;

Step 3, balance mass Systematic selection test model according to reality, this test model is in the open loop of XY axle, Rz axle closed loop, above-mentioned balance mass module and two-dimensional grating chi is comprised in test model, Δ x now, Δ y value are updated in test model, select one group of Rz track, be injected into test model; In the present embodiment, online compensation model as shown in Figure 4 selected by test model, and movement locus is the three rank movement locus described in step one;

Step 4, testing results model, be balanced quality zero-speed section shift measurement to export (through the displacement data of certain stabilization time after the zero-speed section moment of arrival trajectory planning), the displacement obtaining XYRz Three Degree Of Freedom after displacement data process (the physical axis shift value obtained by balance mass sensor is converted into logic axial translation value) exports x_pos_cg, y_pos_cg and rz_pos, calculates Δ x now, Δ y value record according to formula (4);

Step 5, input next group Rz track, repeat step 3 and step 4, obtain different Δ x, Δ y value record;

After step 6, record N sub-value, calculate its mean value, obtain this group tested after barycenter deviation delta x, Δ y value;

Step 7, judge whether to complete M test, if do not complete, then to the Δ x obtained, Δ y, respectively with the searching threshold spec_x set, spec_y compares, if Δ x, Δ y is all less than searching threshold, then think that surveying school completes, the offset of the relative centre of form of barycenter is Δ x, Δ y, if Δ x, at least one great-than search threshold value in Δ y, by Δ x now, Δ y value substitutes into test model, repeat step 3 ~ six, until Δ x, Δ y value is less than the searching threshold of setting, complete and survey school, or until testing time is greater than the testing time M of setting, complete and survey school.

Figure 4 shows that balance mass barycenter surveys school and online compensation control block diagram, namely barycenter surveys the schematic diagram of school and online compensation model.In figure, barycenter online compensation model 401 is surveyed school module 405 by barycenter and is obtained the barycenter correction needed, be input in online compensation model, the power calculating physical motor exports, feed in motor and controlled device module 402, two-dimensional grating chi module 403 measures the displacement of balance mass in real time, the displacement being balanced quality Three Degree Of Freedom by measuring modular converter 404 exports, feeding barycenter surveys in school module 405, barycenter surveys school module 405 according to survey school flow process as shown in Figure 7, obtain the offset of barycenter, be input in online compensation model 401 again, real-time compensatory control.

Figure 5 shows that in a simulation example, at balance mass Rz to closed loop, join the movement locus of Rz axle.

Figure 6 shows that in simulation example, at balance mass Rz to closed loop, and when adding 1mrad movement locus, balance mass level is to the displacement output map of each degree of freedom.In Fig. 6 the first width figure refer to balance mass X to displacement export, the second width figure refer to balance mass Y-direction displacement export, the 3rd width figure refer to balance mass Rz to displacement export.

In analysis, add one group of test parameter and carry out actual test, parameter designing and test result are as following table

Can find out, basically identical through eccentricity value and the setting value surveying school, X to the survey school barycenter of Y-direction with set barycenter deviation within 0.15mm scope, primary calibration precision is less than manufacturing tolerance scope.

Just preferred embodiment of the present invention described in this instructions, above embodiment is only in order to illustrate technical scheme of the present invention but not limitation of the present invention.All those skilled in the art, all should be within the scope of the present invention under this invention's idea by the available technical scheme of logical analysis, reasoning, or a limited experiment.

Claims (5)

1. a work-piece platform balancing quality center of mass detection calibration method, is characterized in that having following steps:

Step one, generate N group Rz track for balance mass, set full test number of times M;

Step 2, barycenter deviation when supposing initial , be zero, setting XY is to the searching threshold spec_x of barycenter and spec_y;

Step 3, select the test model of X, Y, Rz axle, by now , value is updated in test model, selects one group of Rz track, is injected into test model;

Step 4, testing results model, be balanced quality zero-speed section shift measurement and export, and then the displacement obtaining XYRz Three Degree Of Freedom exports , with , according to formula: calculate now , be worth and record;

Step 5, input next group Rz track, repeat step 3 and step 4, obtain different , be worth and record;

After step 6, record N sub-value, be averaging, obtain this group tested after barycenter deviation , value;

Step 7, judge whether to complete M test, if do not complete, then to obtaining , , compare with searching threshold spec_x, the spec_y of setting respectively, if , all be less than searching threshold, then think that surveying school completes, and confirm that the side-play amount of barycenter is , ; If , in at least one great-than search threshold value, by now , value substitutes into test model, repeats step 3 ~ six, until , value is less than the searching threshold of setting, completes and surveys school; Or until testing time is greater than the testing time M of setting, completes and survey school.

2. work-piece platform balancing quality center of mass detection calibration method according to claim 1, it is characterized in that, described track is the three rank movement locus comprising the kinematic parameters such as displacement, speed and acceleration.

3. work-piece platform balancing quality center of mass detection calibration method according to claim 1 and 2, is characterized in that, described test model is open loop at XY axle, is closed loop at Rz axle.

4. work-piece platform balancing quality center of mass detection calibration method according to claim 3, is characterized in that, utilizes grating scale to realize the closed loop of described Rz axle.

5. work-piece platform balancing quality center of mass detection calibration method according to claim 4, it is characterized in that, described grating scale is two-dimensional grating chi.