Granted Patent B2

US 12,724,038 · App. 18/272,640 · Granted Sep 1, 2026

Inventors: Hamed Sadeghian Marnani (Rotterdam, NL); Ioan-Andrei Toacsen (Eindhoven, NL)

Assignee: Nearfield Instruments B.V.

G01Q20/02G01Q30/06G01Q40/00G01Q70/02G03F9/7061G05B2219/37224

Abstract

Claims (44)

1 . A grid plate encoder based positioning system for positioning of an element, the positioning system comprising:

a grid plate with a grid plate surface;

an encoder unit with one or more optical sensors for sensing a grid plate surface pattern of the grid plate surface; and

an input to receive setpoint coordinates specifying a desired position of the element;

wherein said positioning system is configured to:

compute compensated coordinate data corresponding to estimated position data expected from the encoder unit when the element is positioned at the desired position; and

provide the compensated coordinate data as a setpoint to a positioning unit, with feedback control based on the estimated position data obtained from the encoder unit,

the positioning system further comprising:

a wafer stage for carrying a wafer having optically detectable marks at a wafer surface facing the grid plate surface;

a calibration head movable between the wafer stage and the grid plate, the calibration head including the encoder unit with the one or more optical sensors for sensing the grid plate surface pattern of the grid plate surface and a mark sensor for sensing the optically detectable marks;

wherein the calibration head is configured for being positioned at a plurality of mutually different lateral positions and wherein the positioning system is further configured to compute the compensated coordinate data from measurement data obtained from the encoder unit and from the mark sensor at the plurality of mutually different lateral positions.

2 . An atomic force microscope (AFM) system comprising the grid plate encoder based positioning system according to claim 1 , further comprising an AFM head with a probe having a tip to be positioned with the positioning system, wherein the AFM head includes the encoder unit.

3 . A method of positioning the element with the grid plate encoder based positioning system according to claim 1 , the method comprising:

providing the setpoint coordinates indicative of the desired position of the element;

computing the compensated coordinate data indicative for the estimated position data expected from the encoder unit when the element is positioned at the desired position;

providing the compensated coordinate data as the setpoint to the positioning unit, with feedback control based on the estimated position data obtained from the encoder unit.

4 . The grid plate encoder based positioning system according to claim 1 , wherein the compensated coordinate data are computed using a compensation table.

5 . A production system comprising the grid plate encoder based positioning system according to claim 4 , further comprising a production system element to be positioned with the positioning system.

6 . The grid plate encoder based positioning system according to claim 1 , wherein the positioning system is further configured to determine a plurality of grid map calibration parameters.

7 . The grid plate encoder based positioning system according to claim 6 , wherein the plurality of grid map calibration parameters are respective entries in a compensation table, wherein each table entry is addressable as the desired position and comprises the estimated position data.

8 . The grid plate encoder based positioning system according to claim 7 , wherein the compensation table comprises further entries, wherein position indications from the mark sensor specify respective addresses for the further entries, and the estimated position data indicated by the encoder unit are stored in the further entries having the respective addresses.

9 . The grid plate encoder based positioning system according to claim 8 , wherein additional entries in the compensation table are computed by interpolation.

10 . The grid plate encoder based positioning system according to claim 6 , wherein the plurality of grid map calibration parameters define a polynomial that specifies the compensated coordinate data as a function of the setpoint coordinates specifying the desired position of the element.

11 . The grid plate encoder based positioning system according to claim 1 , wherein the encoder unit further comprises a plurality of encoder read heads.

12 . The grid plate encoder based positioning system according to claim 11 , wherein the plurality of encoder read heads comprises a first, a second and a third 1D encoder read head.

13 . The grid plate encoder based positioning system according to claim 12 , wherein the first 1D-encoder read head is for a first planar direction and the second and the third 1D encoder read heads are for a Y-direction.

14 . The grid plate encoder based positioning system according to claim 11 wherein the grid plate surface pattern is provided with a two-dimensional periodic pattern comprising reflecting grid lines on a non-reflective background or reversely.

15 . A production system comprising the grid plate encoder based positioning system according to claim 1 , further comprising a production system element to be positioned with the positioning system.

16 . A method of positioning an element, comprising:

providing a grid plate with a grid plate surface;

providing an encoder unit with one or more optical sensors for sensing a grid plate surface pattern of the grid plate surface;

receiving setpoint coordinates specifying a desired position of the element;

computing compensated coordinate data corresponding to estimated position data expected from the encoder unit when the element is positioned at the desired position;

using feedback control to position the element where the estimated position data correspond to the compensated coordinate data,

wherein the method further comprises:

providing a wafer stage for carrying a wafer having optically detectable marks at a wafer surface facing the grid plate surface;

providing a calibration bead movable between the wafer stage and the grid plate, the calibration head including the encoder unit with the one or more optical sensors for sensing the grid plate surface pattern of the grid plate surface and a mark sensor for sensing the optically detectable marks,

wherein the calibration head is configured for being positioned at a plurality of mutually different lateral positions, and wherein the compensated coordinate data is computed from measurement data obtained from the encoder unit and from the mark sensor at the plurality of mutually different lateral positions.

17 . A non-transitory computer readable medium having instructions to enable a programmable processor to perform one or more steps of the method of claim 16 .

18 . A method of computing compensation parameters for use with a grid plate in a grid plate encoder based positioning system, the grid plate having a grid plate surface with a surface pattern, the grid plate encoder based positioning system comprising an encoder unit with one or more optical sensors for optically sensing the surface pattern at the grid plate surface and a signal processor for computing estimated position data from sense signals obtained from said one or more optical sensors; the method comprising:

providing a reference wafer having optically detectable marks at a wafer surface facing the grid plate surface;

providing a calibration head between the grid plate and the reference wafer, the calibration head having a mark sensor facing said wafer surface and having at least the one or more optical sensors of the encoder unit facing the grid plate surface;

positioning the calibration head at a plurality of laterally different positions between the grid plate and the reference wafer to obtain respective position indications from the mark sensor indicative for its sensed position with respect to the optically detectable marks, and to obtain a respective encoder position indication from the encoder unit indicative for its position with respect to the grid plate surface; and

computing the compensation parameters based on the position indications.

Assignments (1)

Priority Claims (1)

Continuity (1)

References Cited (20)