TWI769423B - A method and device for monitoring attitude of photomask and device for detecting particle size of photomask - Google Patents

Abstract

The present invention discloses a photomask attitude monitoring method, device and photomask particle size detection equipment, wherein the monitoring method comprises: acquiring the distance from at least one calibration point to a standard surface along a first direction; respectively acquiring at least one calibration point to the photomask to be measured The distance from the first detection point along the first direction, the distance from at least one calibration point to the second detection point on the mask to be measured along the first direction, and the distance from at least one calibration point to the third detection point on the mask to be measured along the first direction , and calculate the deflection angle of the mask to be measured relative to the standard surface around the second direction and the deflection angle around the third direction according to the acquired data.

Description

A method and device for monitoring attitude of photomask and device for detecting particle size of photomask

The present invention relates to the technical field of semiconductor lithography, for example, to a mask attitude monitoring method and device, and a mask particle size detection device.

The photomask may be contaminated during clamping, transport, storage and exposure, resulting in defects such as particles, scratches, and pinholes on its surface. During the exposure process, the existence of the above-mentioned defects directly affects the image performance and yield of the lithography machine. In severe cases, the yield can be reduced to zero.

As one of the main parts of the reticle transmission subsystem of the lithography machine, the reticle particle size detection system can detect the size and position of defects on the reticle surface. According to the detection results, the lithography machine operating system or the operator can determine whether the mask can be used for the subsequent exposure process. The inspection results can further be used as input data when removing defects on the reticle.

Constrained by the illumination and imaging system, the reticle needs to be focused and horizontal attitude (deflection Rx around the X-axis and deflection Ry around the Y-axis) detected before the reticle is scanned and tested. Currently, a specially designed reticle is used to measure Rx/Ry. The specially designed reticle is designed with a diffraction mark of a specific structure. When the laser is incident at a specific angle, the linear charge-coupled device (CCD) can receive it. The scattered light intensity of the diffractive mark is used to measure the Rx/Ry of the reticle according to the position and deflection of the spot on the line-scan CCD camera. But this method can only be used in Debugging before the particle size detection of the photomask, and in the specific work project, because the manipulator may be deflected during the reciprocating motion, it cannot always maintain the horizontal state, so that the photomask will also be deflected, resulting in abnormal particle size detection results. At present, it is difficult to directly monitor Rx/Ry online, with high cost and low efficiency.

The photomask may be contaminated during clamping, transport, storage and exposure, resulting in defects such as particles, scratches, and pinholes on its surface. During the exposure process, the existence of the above-mentioned defects directly affects the image performance and yield of the lithography machine. In severe cases, the yield can be reduced to zero.

In a first aspect, an embodiment of the present invention provides a method for monitoring the attitude of a reticle, including: acquiring a distance from at least one calibration point to a standard surface along a first direction; respectively acquiring at least one calibration point to a first detection point on a photomask to be measured along a first detection point. The distance in one direction, the distance from at least one calibration point to the second detection point on the mask to be measured along the first direction, and the distance from at least one calibration point to the third detection point on the mask to be measured along the first direction, wherein the first The projections of the detection point and the second detection point in the standard plane are arranged in the second direction, the projections of the first detection point and the third detection point in the standard plane are arranged in the third direction, the first direction, the second direction and the The third directions are perpendicular to each other, and the standard surface is perpendicular to the first direction; according to the distance from the first detection point to the corresponding calibration point along the first direction, the distance from the calibration point corresponding to the first detection point to the standard surface along the first direction, the The distance from the second detection point to the corresponding calibration point along the first direction, and the distance from the calibration point corresponding to the second detection point to the standard surface along the first direction and the distance between the first detection point and the second detection point along the second direction to calculate the deflection angle of the mask to be measured relative to the standard surface around the third direction; according to the distance from the first detection point to the corresponding calibration point along the first direction, the third The distance from the calibration point corresponding to a detection point to the standard surface in the first direction, the distance from the third detection point to the corresponding calibration point in the first direction, and the distance from the calibration point corresponding to the third detection point to the standard surface in the first direction and the distance between the first detection point and the third detection point along the third direction to calculate the deflection angle of the mask to be measured relative to the standard surface around the second direction.

In a second aspect, an embodiment of the present invention further provides a mask attitude monitoring device, comprising: at least one distance sensor, disposed above the mask to be measured, and configured to obtain the distance from at least one calibration point to the standard surface along the first direction , and obtain the distance from at least one calibration point to the first detection point on the mask to be measured along the first direction, the distance from at least one calibration point to the second detection point on the mask to be measured along the first direction, and at least one calibration point The distance to the third detection point on the mask to be measured along the first direction, wherein the first direction, the second direction and the third direction are perpendicular to each other, the standard surface is perpendicular to the first direction, and the first detection point and the second detection point are at The projections in the standard plane are arranged along the second direction, and the projections of the first detection point and the third detection point in the standard plane are arranged along the third direction; the moving mechanism is arranged to drive the mask to be measured along the second direction and/or Or move in the third direction; the control and calculation unit is set to be based on the distance from the first detection point to the corresponding calibration point along the first direction, the distance from the calibration point corresponding to the first detection point to the standard surface along the first direction, and the second detection The distance from the point to the corresponding calibration point in the first direction, the distance from the calibration point corresponding to the second detection point to the standard surface in the first direction, and the distance between the first detection point and the second detection point in the second direction Calculate the mask to be measured The deflection angle around the third direction relative to the standard surface; and, according to the distance from the first detection point to the corresponding calibration point along the first direction, the distance from the calibration point corresponding to the first detection point to the standard surface along the first direction, the The distance from the three detection points to the corresponding calibration point along the first direction, the corresponding third detection point The distance from the calibration point to the standard surface along the first direction and the distance between the first detection point and the third detection point along the third direction calculate the deflection angle of the mask to be measured relative to the standard surface around the second direction.

In a third aspect, an embodiment of the present invention further provides an apparatus for detecting the particle size of a reticle, including the reticle attitude monitoring device according to any of the foregoing aspects of the second aspect of the present invention.

The invention provides a photomask attitude monitoring method, device and photomask particle size detection equipment. During the photomask particle size detection process, the attitude of the photomask is monitored online, which simplifies monitoring equipment and improves monitoring efficiency.

101: Distance sensor

200: Mask to be measured

201: Protective film

202: Substrate

300: Mounting the frame

400: Mobile Mechanism

601: Light source

602: Lighting system

603: Absorber

604: Detection unit

a1: The first detection point

a2: The second detection point

a3: The third detection point

A: Standard surface

X: second direction

Y: third direction

Z: the first direction

H1 , H1 ' , H2 , H2 ' , H3 , H3 ' , L1 , L2 : distance

[FIG. 1] A method for monitoring the attitude of a photomask provided by an embodiment of the present invention.

[FIG. 2] is a schematic diagram of calculating the deflection angle of a mask to be measured in an embodiment of the present invention.

[FIG. 3] is a schematic diagram of the distribution of each detection point on the mask to be measured in the embodiment of the present invention.

[FIG. 4] is another schematic diagram of calculating the deflection angle of the mask to be measured in the embodiment of the present invention.

FIG. 5 is a schematic diagram along a third direction of a photomask attitude monitoring device according to an embodiment of the present invention.

[ FIG. 6 ] is a schematic diagram of the mask attitude monitoring device in FIG. 5 along a second direction.

FIG. 7 is a schematic diagram along a third direction of a photomask attitude monitoring device according to an embodiment of the present invention.

[Fig. 8] is a detection principle diagram of the photomask particle inspection detection device provided by the embodiment of the present invention.

The technical means of the embodiments of the present invention will be further described in detail below with reference to the drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those with ordinary knowledge in the art without creative efforts shall fall within the protection scope of the present invention.

In the description of the present invention, unless otherwise expressly specified and limited, the terms "connected", "connected" and "fixed" should be understood in a broad sense, for example, it may be a fixed connection, a detachable connection, or an integrated ; It can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal communication between the two elements or the interaction relationship between the two elements. Those with ordinary knowledge in the art can understand the specific meanings of the above terms in the present invention in specific situations.

In the present invention, unless otherwise specified and limited, the first feature "on" or "under" the second feature may include the first and second features in direct contact, or may include the first and second features Not directly but through additional features therebetween. Moreover, the first feature is "above", "above" and "above" the second feature includes that the first feature is directly above and obliquely above the second feature, or simply means that the first feature is level higher than the second feature. The first feature "below", "below" and "below" the second feature includes that the first feature is directly below and obliquely below the second feature, or simply means that the first feature has a lower level than the second feature.

An embodiment of the present invention provides a mask attitude monitoring method. FIG. 1 is a mask attitude monitoring method provided by an embodiment of the present invention. As shown in FIG. 1 , the mask attitude monitoring method includes steps S11 to S13 .

In step S11, obtain at least one calibration point to the standard surface along the first direction the distance.

The standard plane is a plane perpendicular to the first direction Z. Exemplarily, the at least one calibration point may be three calibration points, and the distances from the three calibration points to the standard surface along the first direction are obtained. It should be noted that the plane on which the three calibration points are located may be parallel to the standard surface. In this case, it is only necessary to obtain the distance from one of the calibration points to the standard surface along the first direction.

In step S12, the distances along the first direction from at least one calibration point to the first detection point, the second detection point and the third detection point on the mask to be measured are acquired.

Among them, the first detection point, the second detection point and the third detection point are located on the mask to be measured and correspond to the three calibration points one-to-one. The projection of the first detection point and the second detection point in the standard plane is along the second direction X arrangement, the projections of the first detection point and the third detection point in the standard plane are arranged along the third direction Y, and the first direction, the second direction and the third direction are perpendicular to each other. Acquiring the distance from at least one calibration point to the first detection point, the second detection point and the third detection point on the mask to be measured along the first direction includes: acquiring the distance from each detection point to the corresponding calibration point along the first direction.

In step S13, the deflection angle of the mask to be measured relative to the standard surface around the second direction and the deflection angle around the third direction are calculated according to the acquired data.

FIG. 2 is a schematic diagram of calculating the deflection angle of a mask to be measured in an embodiment of the present invention, and FIG. 3 is a schematic diagram of the distribution of detection points on the mask to be measured in an embodiment of the present invention. It should be noted that each detection point is not a fixed point on the mask to be measured, but is set according to the detection needs. It only needs to satisfy the projection of the first detection point and the second detection point in the standard plane along the second direction X row. The projections of the first detection point and the third detection point on the standard plane may be arranged along the third direction Y. Taking the calculation of the deflection angle of the mask to be measured relative to the standard surface around the third direction as an example, as shown in FIG. 2 , in an embodiment, according to the distance H from the first detection point a1 to the corresponding calibration point along the first direction Z 1 ' , the distance H 1 from the calibration point corresponding to the first detection point a1 to the standard surface A along the first direction Z 1, the distance H 2 ' from the second detection point a2 to the corresponding calibration point along the first direction Z, the second detection The distance H2 from the calibration point corresponding to the point a2 to the standard surface A along the first direction Z, and the distance L1 between the first detection point a1 and the second detection point a2 along the second direction X, calculate the photomask 200 to be measured relative to the standard surface. The deflection angle θ1 of A around the third direction Y. The distance L1 between the first detection point a1 and the second detection point a2 along the second direction X is the distance along the second direction X between the corresponding two calibration points. In one embodiment, the calculation formula is as follows:

The calculation principle of the deflection angle of the photomask 200 to be measured relative to the standard surface A around the second direction X is similar to the calculation principle of the deflection angle of the photomask 200 to be measured around the second direction Y. In one embodiment, according to the first detection point a1 The distance H 1 ′ to the corresponding calibration point along the first direction Z, the distance H 1 from the calibration point corresponding to the first detection point a1 to the standard surface A along the first direction Z, the third detection point a3 to the corresponding calibration point along the The distance H 3 ′ in the first direction Z, the distance H 3 from the calibration point corresponding to the third detection point a3 to the standard surface A along the first direction Z, and the first detection point a1 and the third detection point a3 along the third direction Y The distance L 2 is calculated, and the deflection angle θ 2 of the mask 200 to be measured relative to the standard surface A around the second direction X is calculated. The distance L2 between the first detection point a1 and the third detection point a3 along the third direction Y is the distance between the corresponding two calibration points along the third direction Y. In one embodiment, the calculation formula is as follows:

In the embodiment of the present invention, the distance from at least one calibration point to the standard surface along the first direction and the distance between at least one calibration point and the first detection point, the second detection point and the third detection point on the mask to be measured along the first direction are obtained. Distance, calculate the second direction of the mask to be measured according to the acquired data The deflection angle and the deflection angle around the third direction can realize the online monitoring of the deflection angle of the photometric mask, the monitoring process is simple, the monitoring efficiency is high, and no specially designed mask and line scan CCD camera are required, and the monitoring cost is low.

In one embodiment, before acquiring the distance from the at least one calibration point to the standard surface along the first direction, the method further includes: leveling the calibration mask, so that the calibration mask is perpendicular to the first direction, and the surface of the calibration mask is calibrated. for the standard surface.

In one embodiment, in the offline state, the calibration reticle is leveled. The calibration reticle may be a reticle with the same parameters and design as the reticle 200 to be measured, so that the calibration reticle is perpendicular to the first direction Z, and the calibration The upper and lower surfaces of the reticle can be used as standard surfaces, and no special design is required to calibrate the reticle.

In one embodiment, with continued reference to FIG. 2 , in another embodiment of the present invention, at least one calibration point may be two calibration points, respectively a first calibration point and a second calibration point, and the first calibration point and the second calibration point. The calibration points are arranged along the second direction X, and the distance from at least one calibration point to the first detection point, the second detection point and the third detection point on the photomask to be measured along the first direction is obtained, including: obtaining the first calibration point to the first detection point. A distance H1' from a detection point a1 along the first direction Z, and a distance H2' from the second calibration point to the second detection point a2 along the first direction Z; move the mask 200 to be measured along the third direction Y to obtain the first target The distance from the fixed point to the third detection point a3 along the first direction Z, this distance is taken as the distance H3' from the third detection point a3 to the corresponding calibration point along the first direction Z, wherein the mask 200 to be measured moves along the third direction Y The distance is the distance L2 between the first detection point a1 and the third detection point a3 along the third direction Y.

The embodiment of the present invention can reduce the number of calibration points, simplify the structure of the monitoring device, and can use the mask moving mechanism in the related art to move the mask to be measured, thereby reducing the monitoring cost.

In one embodiment, the first calibration point and the second calibration point are located on the same side of the mask 200 to be measured, as shown in FIG. 2 . FIG. 4 is another schematic diagram of calculating the deflection angle of the mask to be measured according to the embodiment of the present invention. As shown in FIG. 4 , the first calibration point and the second calibration point may also be located on opposite sides of the mask to be measured 200 .

In another embodiment of the present invention, at least one calibration point may be two calibration points, which are a third calibration point and a fourth calibration point respectively, and the third calibration point and the fourth calibration point are arranged along the third direction Y, and obtain The distance from at least one calibration point to the first detection point, the second detection point and the third detection point on the mask to be measured along the first direction Z, including: acquiring the distance from the third calibration point to the first detection point a1 along the first direction Z Distance, this distance is used as the distance H1' from the first detection point a1 to the corresponding calibration point along the first direction Z, and the distance from the fourth calibration point to the third detection point a3 along the first direction, this distance is used as the third detection point The distance H3' from a3 to the corresponding calibration point along the first direction Z; move the mask 200 to be measured along the second direction X to obtain the distance from the third calibration point to the second detection point a2 along the first direction Z, this distance is used as the first The distance H2' from the two detection points a2 to the corresponding calibration point along the first direction Z, wherein the distance that the mask 200 to be measured moves along the second direction X is the first detection point a1 and the second detection point a2 along the second direction X the distance L1.

In one embodiment, the third calibration point and the fourth calibration point are located on the same side or different sides of the mask to be measured.

In another embodiment of the present invention, the calibration point includes a fifth calibration point, and the distance from at least one calibration point to the first detection point, the second detection point and the third detection point on the mask to be measured along the first direction Z is obtained, including : Move the mask 200 to be measured along the second direction X and/or the third direction Y to obtain the distance from the fifth calibration point to the first detection point a1 along the first direction Z, and the distance from the fifth calibration point to the second detection point a2 along the first direction Z The distance in one direction Z and the distance from the fifth calibration point to the third detection point a3 along the first direction Z are taken as the distances H 1 ' , H 2 ' and H from each detection point to the corresponding calibration point along the first direction Z, respectively 3 ' , wherein, the distance that the mask 200 to be measured moves along the second direction X is the distance between the first detection point a1 and the second detection point a2 along the second direction X, and the distance that the mask 200 to be measured moves along the third direction Y is The distance between the first detection point a1 and the third detection point a3 along the third direction Y.

The embodiments of the present invention further reduce the number of calibration points, use one calibration point to complete the monitoring process, simplify the structure of the monitoring device, and use the mask moving mechanism in the related art to move the mask to be measured, thereby reducing monitoring costs.

An embodiment of the present invention further provides a mask attitude monitoring device. FIG. 5 is a schematic diagram of a mask attitude monitoring device provided in an embodiment of the present invention along a third direction, and FIG. 6 is a second direction of the mask attitude monitoring device in FIG. 5 . A schematic diagram of the orientation, as shown in FIG. 5 and FIG. 6 , the mask attitude monitoring device includes: at least one distance sensor 101, which is arranged above the mask 200 to be measured, and is fixed on the mounting frame 300. Exemplarily, at least one distance sensor 101 The distance sensors can be three distance sensors 101, which are configured to obtain the distances from the three calibration points to the standard surface A along the first direction Z, and to obtain the first detection point a1 and the second detection point on the photomask 200 to be measured. The distance from the point a2 and the third detection point a3 to the corresponding calibration point along the first direction Z, wherein the first direction Z, the second direction X and the third direction Y are perpendicular to each other, and the standard plane A is perpendicular to the first direction Z, The projections of the first detection point a1 and the second detection point a2 in the standard plane A are arranged along the second direction X, and the projections of the first detection point a1 and the third detection point a3 in the standard plane A are arranged along the third direction Y cloth, the distance sensor and the detection point are set in one-to-one correspondence. The standard surface A is the upper and lower surfaces of the calibration mask after leveling the calibration mask in the offline state. The calibration mask can be a mask with the same parameters and design as the mask 200 to be measured. Leveling so that the calibration mask is perpendicular to the first direction Z.

The moving mechanism 400 is configured to drive the mask 200 to be measured along the second direction X And/or moving in the third direction Y, the moving mechanism 400 may be a manipulator, and the free end of the manipulator is provided with a fork, which is configured to carry the mask 200 to be measured.

The control and calculation unit (not shown in the figure) is configured to calculate the deflection angle of the mask 200 to be measured relative to the standard surface A around the second direction X and the deflection angle around the third direction Y according to the data obtained by the distance sensor 101 .

In one embodiment, according to the distance H 1 ′ from the first detection point a1 to the corresponding calibration point along the first direction Z, and the distance H 1 from the calibration point corresponding to the first detection point a1 to the standard surface A along the first direction z , the distance H 2 ′ from the second detection point a2 to the corresponding calibration point along the first direction Z, the distance H 2 from the calibration point corresponding to the second detection point a2 to the standard surface A along the first direction Z and the first detection point a1 The distance L 1 from the second detection point a2 along the second direction X is used to calculate the deflection angle θ 1 of the mask 200 to be measured relative to the standard surface A around the third direction Y. The distance L 1 between the first detection point a1 and the second detection point a2 along the second direction X is the distance between the corresponding two distance sensors 101 along the second direction X. In one embodiment, the calculation formula is as follows:

The calculation principle of the deflection angle of the photomask 200 to be measured relative to the standard surface A around the second direction X is similar to the calculation principle of the deflection angle of the photomask 200 to be measured around the second direction Y. In one embodiment, according to the first detection point a1 The distance H 1 ′ to the corresponding calibration point along the first direction Z, the distance H 1 from the calibration point corresponding to the first detection point a1 to the standard surface A along the first direction Z, the third detection point a3 to the corresponding calibration point along the The distance H 3 ′ in the first direction Z, the distance H 3 from the calibration point corresponding to the third detection point a3 to the standard surface A along the first direction Z, and the first detection point a1 and the third detection point a3 along the third direction Y The distance L 2 is calculated, and the deflection angle θ 2 of the mask 200 to be measured relative to the standard surface A around the second direction X is calculated. The distance L 2 between the first detection point a1 and the third detection point a3 along the third direction Y is the distance between the corresponding two distance sensors 101 along the third direction Y. In one embodiment, the calculation formula is as follows:

In this embodiment of the present invention, at least one distance sensor is used to obtain the distance from at least one calibration point to the standard surface along the first direction, and at least one calibration point to the first detection point, the second detection point and the third detection point on the mask to be measured The distance of the point along the first direction, the control calculation unit calculates the deflection angle of the mask to be measured around the second direction and the deflection angle around the third direction according to the acquired data, which can realize online monitoring of the deflection angle of the mask to be measured, and the monitoring process is simple , high monitoring efficiency, and no need for specially designed reticle and line array CCD camera, low monitoring cost.

In another embodiment of the present invention, referring to FIG. 5 , the mask attitude monitoring apparatus includes two distance sensors 101 arranged along the second direction X, corresponding to the first calibration point and the second calibration point respectively. The two distance sensors 101 first obtain the distance H 1 ′ from the first calibration point to the first detection point a1 along the first direction Z, and the distance H 2 from the second calibration point to the second detection point a2 along the first direction Z ' . Next, the control computing unit controls the moving mechanism 400 to carry the mask 200 to be measured to move along the third direction Y, and the corresponding distance sensor 101 obtains the distance from the first calibration point to the third detection point a3 along the first direction Z, and the distance is taken as The distance H 3 ′ from the third detection point a3 to the corresponding calibration point along the first direction Z, wherein the distance that the mask 200 to be measured moves along the third direction Y is the distance between the first detection point a1 and the third detection point a3 along the third direction Y Distance L 2 in direction Y.

Referring to FIG. 6 , in another embodiment of the present invention, the mask attitude monitoring apparatus includes two distance sensors 101 arranged along the third direction Y, corresponding to the third calibration point and the fourth calibration point respectively. The two distance sensors 101 first obtain the distance H 1 ′ from the third calibration point to the first detection point a1 along the first direction Z, and the distance H 3 from the fourth calibration point to the third detection point a3 along the first direction Z ' . Then, the control computing unit controls the moving mechanism to carry the mask 200 to be measured to move along the second direction X, and the corresponding distance sensor 101 obtains the distance from the third calibration point to the second detection point a2 along the first direction Z, and this distance is used as the first direction Z. The distance H 2 ′ from the two detection points a2 to the corresponding calibration point along the first direction Z, wherein the distance that the mask 200 to be measured moves along the second direction X is the first detection point a1 and the second detection point a2 along the second direction X distance L 2.

FIG. 7 is a schematic diagram of a mask attitude monitoring device along a third direction according to an embodiment of the present invention. In one embodiment, referring to FIG. 5 , 6 or 7 , the two distance sensors 101 are located at the same side of the mask 200 to be measured. side or side.

The embodiment of the present invention can reduce the number of distance sensors, simplify the structure of the monitoring device, and can use the mask moving mechanism in the related art to move the mask to be measured, thereby reducing the monitoring cost.

In another embodiment of the present invention, the mask posture monitoring apparatus includes a distance sensor 101 corresponding to the fifth calibration point. In one embodiment, the moving mechanism 400 moves the mask 200 to be measured along the second direction X and/or the third direction Y, and the distance sensor 101 obtains the distance from the fifth calibration point to the first detection point a1 along the first direction Z , the distance from the fifth calibration point to the second detection point a2 along the first direction Z, and the distance from the fifth calibration point to the third detection point a3 along the first direction Z, respectively as each detection point to the corresponding calibration point along the first direction Z The distances H 1 ′ , H 2 ′ and H 3 ′ in the direction Z, wherein the distance that the mask 200 to be measured moves along the second direction X is the distance L between the first detection point a1 and the second detection point a2 along the second direction X 1. The distance that the mask 200 to be measured moves along the third direction Y is the distance L2 between the first detection point a1 and the third detection point a3 along the third direction Y.

In the embodiment of the present invention, the number of distance sensors is further reduced, the monitoring process can be completed by using one distance sensor, the structure of the monitoring device is simplified, and the The mask moving mechanism moves the mask to be measured to reduce monitoring costs.

An embodiment of the present invention further provides a photomask particle size detection device, including the photomask attitude monitoring device according to any of the above embodiments of the present invention.

As one of the main parts of the reticle transmission subsystem of the lithography machine, the reticle particle size detection equipment can detect the size and position of the contamination particles on the surface of the protective film (pellicle) and the surface (glass) of the reticle. According to the detection results, the lithography machine operating system or the operator can determine whether the mask can be used for the subsequent exposure process. The detection results can further be used as input data when removing contaminating particles from the reticle.

FIG. 8 is a detection principle diagram of a photomask particle inspection detection device provided by an embodiment of the present invention. As shown in FIG. 8 , a set of illumination and detection units are respectively configured on the surfaces of the protective film 201 and the substrate 202 of the photomask. In order to improve the detection sensitivity of particles, the reticle particle detection adopts dark field scattering measurement technology, which can detect particles smaller than the size of the picture element.

After the light generated by the light source 601 is collimated, expanded and homogenized by the illumination system 602, it is incident on the pellicle surface (or glass surface) at a certain inclination angle, and a high-brightness linear light spot is formed on the pellicle surface, which is the detection area. , the detection area is distributed along the third direction Y, when the detection area has no pollution particles, the light beam enters the absorption device 603 along the mirror reflection direction, and the detection unit 604 cannot detect the optical signal at this time; when there are pollution particles in the detection area, part of the beam The particles are scattered into the detection unit 604, and the particle size is determined according to the detected light intensity value. The moving mechanism carries the mask to move along the second direction X, and the detection area scans the entire surface of the mask.

It should be understood that the azimuth or positional relationship such as the term "on" is based on the azimuth or positional relationship shown in the drawings, and is only for the convenience of description and simplification of operations, rather than indicating or obscuring. The indicated device or element must have a particular orientation, be constructed and operate in a particular orientation, and therefore should not be construed as limiting the invention.

In the description of this specification, description with reference to the terms "an embodiment" and the like means that a feature, structure, material or characteristic in conjunction with the embodiment is included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment.

In addition, it should be understood that although this specification is described in terms of embodiments, not every embodiment only includes an independent technical means, and these descriptions in the specification are only for the purpose of clarifying devices, and those with ordinary knowledge in the art should take the description as As a whole, the technical means in each embodiment can also be appropriately combined to form other embodiments that can be understood by those with ordinary knowledge in the art.

The present invention claims the priority of the Chinese patent invention with application number 201811630079.0 submitted to the China Patent Office on December 28, 2018, the entire contents of which are incorporated herein by reference.

Claims (11)

A method for monitoring the attitude of a photomask, which is characterized by comprising: obtaining the distances from two calibration points to a standard surface along a first direction; respectively obtaining the distances from the two calibration points to a first detection point on a photomask to be measured along the first direction The distance from the two calibration points to the second detection point on the mask to be measured along the first direction, and the distance from the two calibration points to the third detection point on the mask to be measured along the first direction, wherein, The projections of the first detection point and the second detection point in the standard plane are arranged in the second direction, and the projections of the first detection point and the third detection point in the standard plane are arranged in the third direction, The first direction, the second direction and the third direction are perpendicular to each other, and the standard plane is perpendicular to the first direction; according to the distance from the first detection point to the corresponding calibration point along the first direction, the first detection point corresponds to The distance from the calibration point to the standard surface along the first direction, the distance from the second detection point to the corresponding calibration point along the first direction, the calibration point corresponding to the second detection point to the standard surface along the first direction direction, and the distance between the first detection point and the second detection point along the second direction, calculate the deflection angle of the photomask to be measured relative to the standard surface around the third direction; according to the first detection point to The distance from the corresponding calibration point along the first direction, the distance from the calibration point corresponding to the first detection point to the standard surface along the first direction, and the distance from the third detection point to the corresponding calibration point along the first direction , the distance from the calibration point corresponding to the third detection point to the standard surface along the first direction, and the distance between the first detection point and the third detection point along the third direction, calculate the relative distance of the mask to be measured relative to the standard The deflection angle of the surface around the second direction; wherein, the two calibration points are located on opposite sides of the photomask to be measured. According to the mask attitude monitoring method described in item 1 of the scope of the application, before obtaining the distance from the two calibration points to the standard surface along the first direction, the method further comprises: leveling the calibration mask, so that the calibration light The mask is perpendicular to the first direction, and the surface of the calibration mask is the standard surface. The mask attitude monitoring method according to item 1 of the scope of application, wherein the two calibration points include a first calibration point and a second calibration point, and the first calibration point and the second calibration point are arranged along the second direction cloth, respectively obtain the distance from the two calibration points to the first detection point on the mask to be measured along the first direction, the distance from the two calibration points to the second detection point on the mask to be measured along the first direction, and the above The distance from the two calibration points to the third detection point on the mask to be measured along the first direction includes: obtaining the distance from the first calibration point to the first detection point along the first direction, and the second calibration point to the distance of the second detection point along the first direction; move the mask to be measured along the third direction to obtain the distance from the first calibration point to the third detection point along the first direction, wherein the mask to be measured The distance moved along the third direction is the distance between the first detection point and the third detection point along the third direction. The mask attitude monitoring method according to item 1 of the scope of the application, wherein the two calibration points include a third calibration point and a fourth calibration point, and the third calibration point and the fourth calibration point are arranged along the third direction cloth, respectively obtain the distance from the two calibration points to the first detection point on the mask to be measured along the first direction, the distance from the two calibration points to the second detection point on the mask to be measured along the first direction, and the above Two calibration points to the third detection point on the mask to be measured The distance in one direction includes: obtaining the distance from the third calibration point to the first detection point along the first direction, and the distance from the fourth calibration point to the third detection point along the first direction; Move the mask to be measured in two directions to obtain the distance from the third calibration point to the second detection point along the first direction, wherein the distance that the mask to be measured moves along the second direction is the first detection point and the The distance of the second detection point along the aforementioned second direction. The method for monitoring the attitude of the mask according to item 1 of the claimed scope, wherein calculating the deflection angle of the mask to be measured relative to the standard surface around the third direction comprises: calculating the relative to the mask to be measured according to the following formula. The deflection angle of the standard surface around the aforementioned third direction,

Wherein, θ1 is the deflection angle of the mask to be measured relative to the standard surface around the third direction, H 1 ′ is the distance from the first detection point to the corresponding calibration point along the first direction, and H 1 is the first The distance from the calibration point corresponding to the detection point to the standard surface along the first direction, H 2 ′ is the distance from the second detection point to the corresponding calibration point along the first direction, H 2 is the distance corresponding to the second detection point The distance from the calibration point to the standard surface along the first direction, L 1 is the distance between the first detection point and the second detection point along the second direction. The method for monitoring the attitude of the mask according to item 1 of the claimed scope, wherein calculating the deflection angle of the mask to be measured relative to the standard surface around the second direction comprises: calculating the relative to the mask to be measured relative to the mask according to the following formula The deflection angle of the standard plane around the aforementioned second direction,

Wherein, θ2 is the deflection angle of the mask to be measured relative to the standard surface around the second direction, H 1 ′ is the distance from the first detection point to the corresponding calibration point along the first direction, and H 1 is the first direction The distance from the calibration point corresponding to the detection point to the standard surface along the first direction, H 3 ′ is the distance from the third detection point to the corresponding calibration point along the first direction, H 3 is the distance corresponding to the third detection point The distance from the calibration point to the standard surface along the first direction, L 2 is the distance between the first detection point and the third detection point along the third direction. A mask attitude monitoring device, which is characterized by comprising: at least one distance sensor, arranged above the mask to be measured, set to obtain the distances from two calibration points to the standard surface along the first direction, and respectively obtain The distance from the two calibration points to the first detection point on the mask to be measured along the first direction, the distance from the two calibration points to the second detection point on the mask to be measured along the first direction, and the two calibration points The distance from the third detection point on the mask to be measured along the first direction, wherein the first direction, the second direction and the third direction are perpendicular to each other, the standard plane is perpendicular to the first direction, and the first detection point is perpendicular to the first direction. The projection of the second detection point on the standard plane is arranged along the second direction, and the projection of the first detection point and the third detection point on the standard plane is arranged along the third direction; the moving mechanism is set In order to drive the photomask to be measured to move in at least one of the second direction and the third direction; the control and calculation unit is set to, according to the distance from the first detection point to the corresponding calibration point along the first direction, the above The distance from the calibration point corresponding to the first detection point to the standard surface along the first direction, the distance from the second detection point to the corresponding calibration point along the first direction, and the calibration point corresponding to the second detection point to the standard the distance of the face along the aforementioned first direction, and Calculate the distance between the first detection point and the second detection point along the second direction, and calculate the deflection angle of the photomask to be measured relative to the standard surface around the third direction; and, according to the first detection point to the corresponding calibration point The distance along the first direction, the distance from the calibration point corresponding to the first detection point to the standard surface along the first direction, the distance from the third detection point to the corresponding calibration point along the first direction, the third The distance from the calibration point corresponding to the detection point to the standard surface along the first direction, and the distance between the first detection point and the third detection point along the third direction, calculate the distance of the photomask to be measured relative to the standard surface around the first Deflection angles in two directions; wherein, the two calibration points are located on opposite sides of the photomask to be measured. The mask attitude monitoring device according to claim 7, wherein the mask attitude monitoring device comprises two distance sensors, and the two distance sensors are arranged along the second direction. The mask attitude monitoring device as described in claim 7, wherein the mask attitude monitoring device comprises two distance sensors, and the two distance sensors are arranged along the third direction. The photomask attitude monitoring device as described in claim 8 or 9, wherein the two distance sensors are located on the same side or different sides of the photomask to be measured. A photomask particle size detection device is characterized by comprising a light source, an illumination system, a photomask attitude monitoring device, an absorption device, and a detection unit; the light source is configured to emit light beams; the lighting system is configured to collimate the light beams, After beam expansion and homogenization, it is irradiated on the mask to be measured; The aforementioned reticle attitude monitoring device is configured to detect the attitude of the aforementioned reticle to be measured, and the aforementioned reticle attitude monitoring device includes: at least one distance sensor, a moving mechanism, and a control computing unit; wherein, the aforementioned at least one distance sensor It is arranged above the mask to be measured, and is set to obtain the distance from two at least one calibration point to the standard surface along the first direction, and to obtain the two at least one calibration point to the first detection point on the mask to be measured. The distance in one direction, the distance from the two at least one calibration point to the second detection point on the mask to be measured along the first direction, and the distance from the two at least one calibration point to the third detection point on the mask to be measured along the first The distance between the directions, wherein the first direction, the second direction and the third direction are perpendicular to each other, the standard plane is perpendicular to the first direction, and the projections of the first detection point and the second detection point in the standard plane are along the The second direction is arranged, the projections of the first detection point and the third detection point on the standard plane are arranged along the third direction; the moving mechanism is arranged to drive the photomask to be measured along the second direction and Move in at least one direction in the third direction; the control and calculation unit is set to: according to the distance from the first detection point to the corresponding calibration point along the first direction, the calibration point corresponding to the first detection point to the standard surface The distance along the aforementioned first direction, the distance along the aforementioned first direction from the aforementioned second detection point to the corresponding calibration point, the distance along the aforementioned first direction from the calibration point corresponding to the aforementioned second detection point to the aforementioned standard surface, and the first Calculate the distance between the detection point and the second detection point along the second direction, and calculate the deflection angle of the photomask to be measured relative to the standard surface around the third direction; and, according to the first detection point to the corresponding calibration point along the The distance in the first direction, the distance from the calibration point corresponding to the first detection point to the standard surface along the first direction, the third detection point The distance from the measurement point to the corresponding calibration point along the first direction, the distance from the calibration point corresponding to the third detection point to the standard surface along the first direction, and the first detection point and the third detection point along the first detection point. The distance in the three directions is calculated, and the deflection angle of the mask to be measured relative to the standard surface around the second direction is calculated; wherein, the two calibration points are located on opposite sides of the mask to be measured; the absorption device is set to absorb the mask to be measured. The detection unit is configured to detect the scattered light of the photomask to be measured, and to determine the particle size of the photomask to be detected according to the light intensity value of the scattered light.

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