CN105652598A - Apparatus and method for measuring inclination and verticality of photoetching machine mask table - Google Patents

Abstract

The invention discloses an apparatus for measuring the inclination and the verticality of a photoetching machine mask table. The apparatus is characterized by comprising: a light source for proving a plurality of uniformly distributed light spots positioned at a straight line to a mask plate, wherein the alignment direction of the plurality of the light spots is perpendicular to two parallel edges of the mask plate and is parallel to other two parallel edges of the mask plate; a photodetector for detecting the verticality values of the plurality of the light spots reflected by the mask plate; and a processor for calculating the inclination deviation of the mask table according to the verticality values of the light spot.

Description

A kind of device and method measuring mask aligner mask platform gradient and vertical degree

Technical field

The present invention relates to a kind of integrated circuit equipment manufacturing field, particularly relate to a kind of device and method measuring mask aligner mask platform gradient and vertical degree.

Background technology

In scanning mask aligner mask platform motor process in the horizontal direction, what it was vertical performs device due to the restriction of mask platform Marble processing precision, or because adopting the reflecting mirror etc. of interferometer measurement not can keep parallel with desirable face, there is pattern and rising and falling. Therefore at it along level to the scan exposure process moved, the mask of its carrying has certain height and dip deviation relative to the optimal object plane of projection objective. Due to the error term that this situation causes, it is referred to as mask bench scanning inclination and scanning rolling. So for reaching best exposure effect, it is necessary to measuring this departure, horizontal direction scanning motion compensating the deviation of mask platform height and inclination, thus ensureing that mask remains at optimal object plane in scanning process.

Current patented technology CN201010114203.5 (title: a kind of method measuring scanning inclination of mask table in scanning mask aligner), this inventive method is after scan exposure, measure the height tolerance of optimal object plane by the method for alignment, calculate the scanning inclination obtaining mask platform. Or patent CN200910045594.7 (title: the measuring method of mask bench scanning inclination and device), the method uses the multiple row alignment mark on mask to measure, the vertical position of alignment mark aerial image is transformed on object plane, calculates and obtain mask bench scanning inclination.

Summary of the invention

It is an object of the invention to provide a kind of method and apparatus measuring mask aligner mask platform gradient and vertical degree, be applied in scan exposure system.

In order to realize foregoing invention purpose, a kind of device measuring mask aligner mask platform gradient and vertical degree of disclosure, it is characterized in that, including: a light source, for providing equally distributed some hot spots located on a straight line to a mask, two parallel edge-perpendicular of some described hot spot orientations and described mask, the sides aligned parallel parallel with described mask two other bar; One photodetector, for detecting some described hot spots vertical angle value after described mask reflects; One processor, for calculating the dip deviation of mask platform according to the vertical angle value of some described hot spots.

Further, described light source and described photodetector lay respectively at three summits that the both sides of a projection objective, described light source, described mask or described mask platform, and described photodetector three are positioned at the triangle of described three formation.

Further, described light source and described photodetector are positioned at above or below described mask simultaneously.

Further, it is characterised in that described mask platform can horizontal motion time, some described hot spot orientations are vertical with described mask bench scanning direction, for scanning inclination and scanning rolling.

Further, described dip deviation obtains according to described mask bench scanning inclination single order wedge shape, second order wedge shape, scanning rolling.

Further, this mask bench scanning inclination single order wedge shape w_l, second order wedge shape w_q, scanning rolling w_rComputing formula be:

$\left(\begin{array}{cc}{y}_1& y_1^2\\ y_2& y_2^2\\ ...& ...\\ y_n& y_n^2\end{array}\right)\left(\begin{array}{c}{w}_l\\ w_q\end{array}\right)+\left(\begin{array}{c}c\\ c\\ ...\\ c\end{array}\right)=\left(\begin{array}{c}{z}_{M1}\\ z_{M2}\\ ...\\ z_{\mathrm{Mn}}\end{array}\right),\left(\begin{array}{c}{y}_1\\ y_2\\ ...\\ y_n\end{array}\right)\left(w_r\right)+\left(\begin{array}{c}c\\ c\\ ...\\ c\end{array}\right)=\left(\begin{array}{c}{\mathrm{Ry}}_1\\ {\mathrm{Ry}}_2\\ ...\\ {\mathrm{Ry}}_n\end{array}\right);$ Wherein Z_M1,Z_M2������Z_MnIt is the whole height position of each position, mask bench scanning direction mask platform, y₁,y₂��y_nBeing mask platform positional value, c is constant term Z₀��Ry₀��

Further, this Z_MnCalculation beWherein n is the quantity of hot spot.

Disclosure is a kind of measures mask bench scanning inclination and the method for scanning rolling, including: step one, provides equally distributed some hot spots located on a straight line to a mask, and these hot spot orientations some are vertical with this mask bench scanning direction; Step 2, this mask platform, along y level to doing scanning motion, record this hot spot vertical angle value after this mask or this mask platform reflect; Step 3, dip deviation according to this hot spot vertical angle value after this mask or this mask platform reflect and this mask platform this mask platform of position calculation.

Further, this dip deviation obtains according to this mask bench scanning inclination single order wedge shape, second order wedge shape, scanning rolling.

Further, this mask bench scanning inclination single order wedge shape w_l, second order wedge shape w_q, scanning rolling w_rComputing formula be:

$\left(\begin{array}{cc}{y}_1& y_1^2\\ y_2& y_2^2\\ ...& ...\\ y_n& y_n^2\end{array}\right)\left(\begin{array}{c}{w}_l\\ w_q\end{array}\right)+\left(\begin{array}{c}c\\ c\\ ...\\ c\end{array}\right)=\left(\begin{array}{c}{z}_{M1}\\ z_{M2}\\ ...\\ z_{\mathrm{Mn}}\end{array}\right),\left(\begin{array}{c}{y}_1\\ y_2\\ ...\\ y_n\end{array}\right)\left(w_r\right)+\left(\begin{array}{c}c\\ c\\ ...\\ c\end{array}\right)=\left(\begin{array}{c}{\mathrm{Ry}}_1\\ {\mathrm{Ry}}_2\\ ...\\ {\mathrm{Ry}}_n\end{array}\right);$ Wherein Z_M1,Z_M2������Z_MnIt is the whole height position of each position, mask bench scanning direction mask platform, y₁,y₂��y_nBeing mask platform positional value, c is constant term Z₀��Ry₀��

Further, this Z_MnCalculation beWherein n is the quantity of hot spot.

Compared with prior art, method provided by the present invention and device, except comprising the scanning inclination in existing invention, further comprises the scanning of mask platform rolling, for reaching higher precision in the compensation of optimal object plane. Device and measurement procedure that measurement process is used are different from existing inventive method. Existing invention all employ coaxillay aligned method, participates in the subsystem of this measurement system except mask platform self, further comprises object lens, work stage and be directed at subsystem. The present invention uses focusing and leveling measuring system, it is possible to the directly vertical variations with complete machine Inner-world for reference measurement mask platform, and the impact by different subsystems is less. Overall structure is simple.

Accompanying drawing explanation

Can be described in detail by invention below about the advantages and spirit of the present invention and institute's accompanying drawings is further understood.

Fig. 1 is the structural representation of the involved in the present invention device measuring mask bench scanning inclination and scanning rolling;

Fig. 2 measures hot spot to be distributed in the schematic diagram under mask platform zero-bit coordinate system;

Fig. 3 is the schematic diagram measuring hot spot and measurand in measurement process;

Fig. 4 is involved in the present invention measuring mask bench scanning inclination and scan the method flow diagram of rolling.

Detailed description of the invention

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

The present invention provides a kind of method measuring mask aligner mask platform gradient and vertical degree, is applied in scan exposure system. The measurement apparatus that the inventive method is used includes a kind of focusing and leveling system measuring mask mesa shape as shown in Figure 1. This system is likely to the schematic diagram of the photodetection structure adopted, and this system can also realize by the mode of optical grating construction, air pressure, electric capacity or machinery. This structure realizes the measurement of mask height and position change in mask platform horizontal movement process with the principle of triangulation. Including light source, photodetector. Light source and photodetector are distributed in object lens both sides. Illustrate distribution mode two kinds possible as shown in Figure 1.This measurement structure is characterised by, this measurement system can measure in mask platform mask space of a whole page shape along with the change in Y-direction horizontal movement process. In Fig. 1, a figure and b figure is two kinds of embodiments of the device of this measurement mask bench scanning inclination and scanning rolling respectively. As shown in a figure, mask platform 20 is positioned at the top of projection objective 1, and mask 21 is positioned at the top of mask platform 20, and mask platform 20 carries mask 21. Light source 10 and photodetector 30 are positioned at the lower section of mask platform 20. In figure b, light source 10 and photodetector 30 are positioned at the top of mask platform 20.

R1, R2 as shown in Figure 2 ... R6 is that this focusing and leveling system 6 measurement hot spot is distributed in the schematic diagram under mask platform zero-bit coordinate system (RZCS), and each smooth speckle can measure height value Z1n, the Z2n in mask platform horizontally motor process ... Z6n. Hot spot shown in this schematic diagram is 6 along X to distribution, as long as meeting 2 or above number in actually used, it is possible to meet the demand measuring scanning rolling. Hot spot Spreading requirements is just giving mask horizontal movement direction Y as shown in Figure 2, and each hot spot Y-direction position remains unchanged, and X is uniformly distributed to identical interval a, and coverage mask version X as much as possible is to surface. Measurand is the mask of absorption in mask platform or mask platform. For mask platform level to the mask of motor process camber position measurement as shown in Figure 2. The measured zone of 6 hot spots is meet the position of reflectivity requirements outside diagram graph area or graphics field, is not limited to mask for this measurement object, it is also possible to be the mask platform datum plate being horizontally distributed in mask platform.

Fig. 3 is the schematic diagram measuring hot spot and measurand in measurement process. 6 Y-direction coordinates are consistent, and the hot spot being distributed in X direction, interval is uniform. 6 hot spot R1 to R6 are respectively positioned on mask 21, and wherein 4 hot spots are positioned at graphics field, and R1 and R6 is positioned at outside graphics field.

The measuring method of mask aligner mask platform gradient of the present invention and vertical degree comprises the following steps, referring to Fig. 4:

S401: upload mask, owing to mask platform adsorbs mask in level all the time in scanning motion process, so the measurement result of mask is it is believed that keep consistent with the high variable quantity of mask platform.

S402: the mobile mask platform initial position to level to scanning. This position is scanning initial position, it is necessary to meets and measures hot spot requirement within the scope of effective measurement.

S403: mask platform horizontally y does scanning motion. Scanning motion process when this scanning motion process general is with etching system actual exposure keeps consistent.

S404: record each facular height value of focusing and leveling sensor, along y to motor process, 6 measure facula measurement to height value be Z_1n,Z_2n��Z_6n. Wherein n be mask platform along horizontal y to motor process, measure the measurement point number that gets of hot spot, generally this measurement point number is greater than 10, and the precision measuring some measurement result more at most is also more high.

S405: model calculates. The height value Z that each facula measurement obtains_1n,Z_2n��Z_6n, mask platform position y₁,y₂��y_n. Each y is Z to the whole height position of position mask platform_M1,Z_M2������Z_Mn��

Then mask platform at each y to the height of position is:

$Z_M=\frac{\underset{1}{\overset{6}{\mathrm{\Σ}}}{Z}_i}{6}...\left(1\right)$

Wherein 6 is the number measuring hot spot.

Z_R=-Ry X+c (2)

By 6 height value Z measuring hot spot_1n,Z_2n��Z_6nAnd the horizontal level X of each hot spot is for people, can obtain Ry by least square fitting.Have according to the vertical Controlling model of mask platform:

Z_M=w_ly+w_qy²+Z₀����������������������������������������������������������������������������(3)

Ry_M=w_ry+Ry₀������������������������������������������������������������������������������������(4)

Wherein, w_l��w_q��w_rIt is exactly required mask bench scanning inclination single order wedge shape, second order wedge shape, scanning rolling. Formula (3) and (4) can be rewritten as matrix form respectively, and c is constant term Z₀��Ry₀:

$\left(\begin{array}{cc}{y}_1& y_1^2\\ y_2& y_2^2\\ ...& ...\\ y_n& y_n^2\end{array}\right)\left(\begin{array}{c}{w}_l\\ w_q\end{array}\right)+\left(\begin{array}{c}c\\ c\\ ...\\ c\end{array}\right)=\left(\begin{array}{c}{z}_{M1}\\ z_{M2}\\ ...\\ z_{\mathrm{Mn}}\end{array}\right)...\left(5\right)$

$\left(\begin{array}{c}{y}_1\\ y_2\\ ...\\ y_n\end{array}\right)\left(w_r\right)+\left(\begin{array}{c}c\\ c\\ ...\\ c\end{array}\right)=\left(\begin{array}{c}{\mathrm{Ry}}_1\\ {\mathrm{Ry}}_2\\ ...\\ {\mathrm{Ry}}_n\end{array}\right)...\left(6\right)$

Respectively by the position y of mask platform_i(i=1,2,3 ... ..n) substitute into, and can obtain w by least square fitting_l��w_q��w_r��

Compared with prior art, method provided by the present invention and device, except comprising the scanning inclination in existing invention, further comprises the scanning of mask platform rolling, for reaching higher precision in the compensation of optimal object plane. Device and measurement procedure that measurement process is used are different from existing inventive method. Existing invention all employ coaxillay aligned method, participates in the subsystem of this measurement system except mask platform self, further comprises object lens, work stage and be directed at subsystem. The present invention uses focusing and leveling measuring system, it is possible to the directly vertical variations with complete machine Inner-world for reference measurement mask platform, and the impact by different subsystems is less. Overall structure is simple.

The preferred embodiment of the simply present invention described in this specification, above example is only in order to illustrate technical scheme 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 (11)

1. the device measuring mask aligner mask platform gradient and vertical degree, it is characterised in that including:

One light source, for providing equally distributed some hot spots located on a straight line to a mask, two parallel edge-perpendicular of some described hot spot orientations and described mask, the sides aligned parallel parallel with described mask two other bar;

One photodetector, for detecting some described hot spots vertical angle value after described mask reflects;

One processor, for calculating the dip deviation of mask platform according to the vertical angle value of some described hot spots.

2. the device measuring mask platform gradient and vertical degree as claimed in claim 1, it is characterized in that, described light source and described photodetector lay respectively at the both sides of a projection objective, described light source, described mask or described mask platform, and described photodetector three is positioned at three summits of triangle that described three is formed.

3. the device measuring mask platform gradient and vertical degree as claimed in claim 2, it is characterised in that described light source and described photodetector are positioned at above or below described mask simultaneously.

4. the as claimed in claim 1 device measuring mask platform gradient and vertical degree, it is characterised in that described mask platform can horizontal motion time, some described hot spot orientations are vertical with described mask bench scanning direction, roll for scanning inclination and scanning.

5. the device measuring mask platform gradient and vertical degree as claimed in claim 1, it is characterised in that described dip deviation obtains according to described mask bench scanning inclination single order wedge shape, second order wedge shape, scanning rolling.

6. right wants the device of the measurement mask platform gradient as described in 5 and vertical degree, it is characterised in that described mask bench scanning inclination single order wedge shape w_l, second order wedge shape w_q, scanning rolling w_rComputing formula be:

$\left(\begin{array}{cc}{y}_1& y_1^2\\ y_2& y_2^2\\ ...& ...\\ y_n& y_n^2\end{array}\right)\left(\begin{array}{c}{w}_l\\ w_q\end{array}\right)+\left(\begin{array}{c}c\\ c\\ ...\\ c\end{array}\right)=\left(\begin{array}{c}{z}_{M1}\\ z_{M2}\\ ...\\ z_{\mathrm{Mn}}\end{array}\right),$

$\left(\begin{array}{c}{y}_1\\ y_2\\ ...\\ y_n\end{array}\right)\left(w_r\right)+\left(\begin{array}{c}c\\ c\\ ...\\ c\end{array}\right)=\left(\begin{array}{c}{\mathrm{Ry}}_1\\ {\mathrm{Ry}}_2\\ ...\\ {\mathrm{Ry}}_n\end{array}\right);$ Wherein Z_M1,Z_M2������Z_MnIt is the whole height position of each position, mask bench scanning direction mask platform, y₁,y₂��y_nBeing mask platform positional value, c is constant term Z₀��Ry₀��

7. right wants the device of the measurement mask platform gradient as described in 6 and vertical degree, it is characterised in that described Z_MnCalculation beWherein n is the quantity of hot spot.

8. the method measuring mask aligner mask platform gradient and vertical degree, it is characterised in that including:

Step one, providing equally distributed some hot spots located on a straight line to a mask, some described hot spot orientations are vertical with described mask bench scanning direction;

Step 2, described mask platform, along y level to doing scanning motion, record the described hot spot vertical angle value after described mask or described mask platform reflect;

Step 3, according to the described hot spot vertical angle value after described mask or described mask platform reflect and described mask platform position calculation the dip deviation of mask platform.

9. the method measuring mask aligner mask platform gradient and vertical degree as claimed in claim 8, it is characterised in that described dip deviation obtains according to described mask bench scanning inclination single order wedge shape, second order wedge shape, scanning rolling.

10. the method measuring mask aligner mask platform gradient and vertical degree as claimed in claim 9, it is characterised in that described mask bench scanning inclination single order wedge shape w_l, second order wedge shape w_q, scanning rolling w_rComputing formula be:

$\left(\begin{array}{cc}{y}_1& y_1^2\\ y_2& y_2^2\\ ...& ...\\ y_n& y_n^2\end{array}\right)\left(\begin{array}{c}{w}_l\\ w_q\end{array}\right)+\left(\begin{array}{c}c\\ c\\ ...\\ c\end{array}\right)=\left(\begin{array}{c}{z}_{M1}\\ z_{M2}\\ ...\\ z_{\mathrm{Mn}}\end{array}\right),$

$\left(\begin{array}{c}{y}_1\\ y_2\\ ...\\ y_n\end{array}\right)\left(w_r\right)+\left(\begin{array}{c}c\\ c\\ ...\\ c\end{array}\right)=\left(\begin{array}{c}{\mathrm{Ry}}_1\\ {\mathrm{Ry}}_2\\ ...\\ {\mathrm{Ry}}_n\end{array}\right);$ Wherein Z_M1,Z_M2������Z_MnIt is the whole height position of each position, mask bench scanning direction mask platform, y₁,y₂��y_nBeing mask platform positional value, c is constant term Z₀��Ry₀��

11. the method measuring mask aligner mask platform gradient and vertical degree as claimed in claim 10, it is characterised in that described Z_MnCalculation beWherein n is the quantity of hot spot.