WO2020001646A1

WO2020001646A1 - Polarization aberration measuring method for projection objective lens

Info

Publication number: WO2020001646A1
Application number: PCT/CN2019/093838
Authority: WO
Inventors: 倪晟
Original assignee: 上海微电子装备（集团）股份有限公司
Priority date: 2018-06-29
Filing date: 2019-06-28
Publication date: 2020-01-02
Also published as: CN110657954A; TWI692631B; TW202001227A; CN110657954B

Abstract

A polarization aberration measuring method for a projection objective lens, comprising: calculating the Jones matrix of a projection objective lens (PO) by means of a light intensity matrix constructed by all groups of light intensity values that is measured on the basis of a light intensity measuring device (IS) and a λ function matrix constructed by all selected elements, so as to directly calculate the Jones matrix of the projection objective lens (PO), effectively avoiding the resultant error caused by the depolarization effect of transitioning the Mueller matrix to the Jones matrix, improving the measurement and calculation accuracy.

Description

Method for measuring polarization aberration of projection objective

Technical field

The invention relates to the technical field of integrated circuit manufacturing, in particular to a method for measuring polarization aberration of a projection objective.

Background technique

Ellipsometer is the most widely used measurement instrument in the field of ellipsometric measurement. It is a general optical measurement instrument that uses the polarization characteristics of light to obtain the information of the sample to be measured. The basic principle is to project special elliptical polarized light onto the surface of the sample to be measured through a polarizer, and measure the reflected light (or transmitted light) of the sample to be measured to obtain the polarization state change of the polarized light before and after reflection (or transmission). (Including amplitude ratio and phase difference), and then extract the information of the sample to be tested from it.

In recent years, in order to meet the needs of different measurement conditions and user groups, many configurations of ellipsometer have made great progress, including rotary polarizer type, rotary analyzer type, single rotation compensator type and dual rotation compensation. Type and so on. When the ellipsometer is used to measure the sample to be measured, the measurement result often deviates from its true value to a certain extent. There are many reasons for these deviations, including ellipsometer random noise, ellipsometer system error, environmental random noise, and measurement human error factors. Even under the same deviation, the sensitivity of the measurement results to the deviation of the system parameters of different configurations of the ellipsometer is not the same. Therefore, in order to reduce the influence of the deviation on the measurement results of the ellipsometer, a certain method must be used to optimize the analysis of the ellipsometer system parameters, so as to obtain the optimal system parameters of the ellipsometer, and then minimize the deviation to the ellipsometer measurement. Impact of results. Therefore, in the process of ellipsometer design, it is necessary to find the optimal system parameter configuration for the current ellipsometer system structure.

At present, the parameter optimization of the ellipsometer system is mainly focused on the optimization of the phase delay of the ellipsometer compensator. For example, an optimal phase delay of 127 ° is proposed to reduce the effect of the deviation on the measurement results of the ellipsometer. . However, there are many parameters of the ellipsometer, such as the azimuth of the polarizer and analyzer, the number of sampling points, and the azimuth of the compensator. These parameters are also important factors affecting the relationship between the deviation and the measurement results of the ellipsometer. Consider for optimization. The prior art CN103426031B discloses a method for optimizing the parameters of an ellipsometer system. The measurement result of this method is the Muller matrix of the sample. The Muller matrix contains the depolarization effect, and the measurement of the projection lens of the lithography machine cannot be used directly The Muller matrix needs to obtain the polarization aberration of the projection objective after converting the Muller matrix to the Jones matrix. However, because the actual measurement error is directly equivalent to the depolarization effect of the conversion of the Mueller matrix to the Jones matrix, the final measurement result is not accurate enough, resulting in poor imaging results of the produced product.

In view of the shortcomings of the measurement methods for polarization aberrations of projection objectives in the prior art, those skilled in the art have been searching for a solution.

Summary of the invention

The purpose of the present invention is to provide a method for measuring the polarization aberration of a projection objective to solve the problem that the measurement result of the polarization aberration measurement method of the projection objective in the prior art is a Muller matrix, and the Muller matrix has a depolarization effect, resulting in a final measurement result The problem is that the accuracy is not high, which affects the imaging effect of the product.

To solve the above technical problems, the present invention provides a method for measuring polarization aberration of a projection objective. The method for measuring polarization aberration of a projection objective includes the following steps:

S1: A first polarizing plate (P1), a first quarter wave plate (Q1), a first condensing lens (L1), a projection objective (PO), a second converging lens (L2), The second quarter-wave plate (Q2), the second polarizer (P2), and the light intensity measuring device (IS);

S2: A rotation angle group set is established, and the elements in the rotation angle group set are the rotation angle of the first polarizer (P1), the rotation angle of the first quarter wave plate (Q1), and the second polarizer ( The combination of the rotation angle formed by the rotation angle of P2) and the rotation angle of the second quarter wave plate (Q2). The elements in the rotation angle group set are different from each other, where the rotation angle is the brightness of the polarizer. The angle between the fast axis of the axis or waveplate and the given direction;

S3: Select an element from the set of rotation angle groups, and adjust the first polarizing plate (P1), the first quarter wave plate (Q1), and the second quarter wave plate ( Q2) and the rotation angle of the second polarizer (P2);

S4: the light intensity measuring device (IS) measures a set of light intensity values corresponding to the current element;

S5: Repeat S3 and S4 at least 16 times to obtain multiple groups of light intensity values, wherein each time S3 is performed, a different element is selected and the multiple groups of light intensity values obtained by the light intensity measurement device (IS) measurement are constructed Is a light intensity matrix. All selected elements are constructed as a lambda function matrix. The elements in the lambda function matrix are the first polarizer (P1), the first quarter wave plate (Q1), and the second quarter. The coefficients of the elements in the Jones matrix of the wave plate (Q2) and the second polarizer (P2) and their complex conjugate products;

S6: Calculate a Jones matrix of a projection objective (PO) according to the light intensity matrix and the lambda function matrix.

Optionally, in the method for measuring the polarization aberration of the projection objective lens, when the Jones matrix of the first condensing lens (L1) and the second converging lens (L2) is not considered, the light intensity value is calculated in S4. The calculation formula used is as follows:

Among them, I is the light intensity value, E _out is the energy of the outgoing light, E _out = J _P2 · J _Q2 · J _PO · J _Q1 · J _P1 · E _in ; * represents the conjugate transpose; J _P1 is the first polarization Jones matrix of the plate (P1), J _P2 is the Jones matrix of the second polarizer (P2), J _Q1 is the Jones matrix of the first quarter wave plate (Q1), and J _Q2 is the second quarter wave Jones matrix of lens (Q2); J _PO is the Jones matrix of projection objective (PO); Jones matrix of wave plate and polarizer are

with

R is the rotation matrix,

α is the rotation angle of the corresponding wave plate or polarizer; E _in is the energy of the incident light.

Optionally, in the method for measuring the polarization aberration of the projection objective lens, in S5, the constructing all selected elements into a lambda function matrix includes the following steps:

S50: Definition

D = J _Q1 · J _P1 · E _in ;

S51: Obtain a formula for calculating the elements in the λ function matrix: λ _{i, j, k, l} = U _l · M _ki · D _j , and calculate all elements in the λ function matrix to construct a λ function matrix;

Among them, U, M, and D are simplified matrices, and the matrices are expressed as U = [U ₁ U ₂ ],

J _P1 is the Jones matrix of the first polarizer (P1), J _P2 is the Jones matrix of the second polarizer (P2), J _Q1 is the Jones matrix of the first quarter wave plate (Q1), and J _Q2 is the first Jones matrix of the quarter-wave plate (Q2); E _in is the energy of the incident light; * represents the conjugate transpose; where i, j, k, l represent the subscripts of the elements in the Jones matrix, and take values respectively 1 or 2; λ _{i, j, k, l} are the elements in the λ function matrix.

Optionally, in the method for measuring the polarization aberration of the projection objective lens, in S6, calculating the Jones matrix of the projection objective lens (PO) according to the light intensity matrix and the lambda function matrix includes the following steps:

S60: The simplified formula (1) is:

S61: Simplify the formula (2) into a linear function of the projection objective Jones matrix element and its complex conjugate product:

S62: Calculate elements in the Jones matrix of the projection objective (PO) to obtain the Jones matrix of the projection objective (PO);

Where J _{i, j} are the elements in the Jones matrix of the projection objective (PO),

Complex conjugates of the elements in the Jones matrix of the projection objective (PO).

Optionally, in the method for measuring the polarization aberration of the projection objective lens, if S3 and S4 are repeatedly performed more than 16 times in S5, the least square method is used in S6 to calculate the approximate value of the Jones matrix of the projection objective lens.

Optionally, in the method for measuring the polarization aberration of the projection objective lens, in S5, an adjustment step of each rotation angle in the selected element ranges from 30 to 60 degrees.

Optionally, in the method for measuring the polarization aberration of the projection objective lens, the given direction is an X-axis or Y-axis direction.

Optionally, in the method for measuring the polarization aberration of the projection objective lens, the first condensing lens (L1) and the second condensing lens (L2) are both collimating lenses, and the two have different focal lengths.

Optionally, in the method for measuring the polarization aberration of the projection objective lens, the first condensing lens (L1) enables the light incident on the projection objective (PO) to have a first numerical aperture, and the second condensing lens (L2) ) Converting light having a second numerical aperture emitted by the projection objective (PO) into parallel light, the second numerical aperture being larger than the first numerical aperture.

Optionally, in the method for measuring the polarization aberration of the projection objective lens, each point in the light intensity map obtained by the light intensity measurement device (IS) measurement corresponds to a point on the pupil surface of the projection objective lens (PO).

Optionally, in the method for measuring the polarization aberration of the projection objective lens, before the measurement is started, a stable light beam is selected as the incident light.

In the method for measuring the polarization aberration of a projection objective provided by the present invention, the method for measuring the polarization aberration of a projection objective is obtained by measuring a light intensity matrix constructed by all groups of light intensity values based on a light intensity measurement device and constructed by all selected elements. The lambda function matrix calculates the Jones matrix of the projection objective lens, that is, the method of the present invention can directly calculate and obtain the Jones matrix of the projection objective lens. Compared with the existing method, the method of measuring the Mueller matrix first and then converting the Mueller matrix to the Jones matrix , Effectively avoids the result error caused by the depolarization effect of the conversion of the Mueller matrix to the Jones matrix, improves the measurement and calculation accuracy, and improves the product imaging effect.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic structural diagram of a measurement system used in a method for measuring polarization aberration of a projection objective lens according to an embodiment of the present invention; FIG.

FIG. 2 is a flowchart of a method for measuring polarization aberration of a projection objective lens according to an embodiment of the present invention.

detailed description

The method for measuring the polarization aberration of the projection objective lens proposed by the present invention is described in further detail below with reference to the drawings and specific embodiments. The advantages and features of the invention will be apparent from the following description and claims. It should be noted that the drawings are in a very simplified form and all use inaccurate proportions, which are only used to facilitate and clearly assist the description of the embodiments of the present invention.

Please refer to FIG. 1, which is a schematic structural diagram of a measurement system used by the projection objective lens polarization aberration measurement method of the present invention. As shown in FIG. 1, the measurement system includes a first polarizing plate P1, a first quarter-wave plate Q1, a first condensing lens L1, a projection objective PO, and a second condensing lens L2, which are sequentially arranged along the propagation direction of the optical path. , The second quarter-wave plate Q2, the second polarizing plate P2, and the light intensity measuring device IS.

In order to facilitate the understanding of the measurement system of the present invention, the elements involved therein are explained in detail below:

1) Polarizer (Polarizer for short): Light passes through the polarizer, and only components with a certain angle can pass through the polarizer, and the light transmittance of the vertical angle is 0.

2) Quarter-wave plate (QWP, referred to as Q): Light passes through the quarter-wave plate, and the phase difference between the two vertical directions changes pi / 4. Therefore, through different combinations of polarizers and quarter-wave plates, light with different polarization states can be obtained.

3) Condensing lens (Lens, abbreviated as L): It is a kind of lens that is thick in the middle and thin in the periphery, that is, a convex lens; it has the ability to condense light, and is also called a "positive lens".

Preferably, the first condensing lens L1 and the second condensing lens L2 in this embodiment are both collimating lenses, and the two have different focal lengths. In this embodiment, the first polarizing plate P1 is used To ensure that the light incident on the projection objective PO is linearly polarized light; the first condensing lens L1 causes the light incident on the projection objective PO to have a first numerical aperture, and the second condensing lens L2 emits the light of the second numerical aperture emitted from the projection objective PO. Converted into parallel light, the second numerical aperture is larger than the first numerical aperture.

The present invention provides a method for measuring the polarization aberration of a projection objective. The specific measurement process of the method for measuring the polarization aberration of a projection objective of the present invention is described below with reference to FIGS. 1 and 2.

First, step S1 is performed, and a first polarizing plate P1, a first quarter wave plate Q1, a first condensing lens L1, a projection objective lens PO, a second converging lens L2, and a second quarter are set in order along the propagation direction of the optical path. Wave plate Q2, second polarizing plate P2, and light intensity measuring device IS; before the measurement starts, a stable light beam is selected as the incident light. Since the polarizing plate and the wave plate included in the front end of the measurement solution of the present invention modulate the incident light, only the It is only required that the incident light is relatively stable.

Next, step S2 is executed to establish a rotation angle group set, where the elements in the rotation angle group set are the rotation angle of the first polarizer P1, the rotation angle of the first quarter wave plate Q1, and the second polarizer P2. The combination of the rotation angle and the rotation angle of the second quarter wave plate Q2 is a combination of rotation angles. The elements in the rotation angle group set are different from each other. The rotation angle is the bright axis of the polarizer and the speed of the wave plate. The angle between the axis and a given direction (usually the X direction).

Next, step S3 is executed, an element is selected from the set of rotation angles, and the first polarizing plate P1, the first quarter wave plate Q1, the second quarter wave plate Q2, and The second polarizer P2, so that the four elements have a rotation angle corresponding to the selected element.

Next, step S4 is performed, and the light intensity measuring device IS measures a group of light intensity values under the current element.

Each point in the light intensity map obtained by the light intensity measurement device IS corresponds to a point on the pupil surface of the projection objective PO, and each point on the pupil surface of the projection objective PO has an independent Jones matrix. The projection objective of the present invention has polarization The aberration measurement method is based on the correspondence between the points in the light intensity map and the points in the pupil plane of the projection objective lens. Since each point in the pupil surface of the projection objective lens has a set of light intensity values, by separately Solve, measure and obtain the Jones matrix of the pupil plane point of the corresponding projection objective lens, and then obtain the Jones matrix distribution of the pupil plane of the entire projection objective lens.

Specifically, when the Jones matrix of the first condensing lens L1 and the second condensing lens L2 is not considered (because the Jones matrix of the condensing lens has a smaller error than the ideal lens, it is ignored here), the light intensity measurement The calculation formula used by the device IS to measure a group of light intensity values under the current element is:

Among them, I is the light intensity value and E _out is the energy of the outgoing light. According to the light propagation formula, it can be known that E _out = J _P2 · J _Q2 · J _PO · J _Q1 · J _P1 · E _in (where the first is ignored Jones matrix of the condenser lens L1 and the second condenser lens L2);

D = J _Q1 · J _P1 · E _in ; E _in is the energy of the incident light; * represents the conjugate transpose; J _P1 is the Jones matrix of the first polarizer P1, J _P2 is the Jones matrix of the second polarizer P2, J _Q1 is the Jones matrix of the first quarter wave plate Q1, J _Q2 is the Jones matrix of the second quarter wave plate Q2; the Jones matrices of the wave plate and the polarizer are

with

J _PO is the Jones matrix of the projection objective PO; R is the rotation matrix,

α is the rotation angle of the corresponding wave plate or polarizing plate. It can be known from the formula of the rotation matrix R that the light intensity measured by the light intensity measuring device IS is related to the Jones matrix of the projection objective PO and is also related to the rotation angle of the four elements .

Next, step S5 is performed, and S3 and S4 are repeatedly performed at least 16 times to obtain multiple groups of light intensity values, wherein each time S3 is performed, a different element is selected, and the multiple groups of light intensity obtained by the light intensity measurement device IS are measured. The value is constructed as a light intensity matrix, and all selected elements are constructed as a lambda function matrix. The elements in the lambda function matrix are the first polarizer P1, the first quarter wave plate Q1, and the second quarter wave plate. Coefficients of the elements in the Jones matrix of Q2 and the second polarizer P2 and their complex conjugate products; preferably, the adjustment step of each rotation angle in the selected elements is 30 to 60 degrees, that is, two adjacent selected elements The difference between the rotation angles of the same object in the range of 30 to 60 degrees. In this embodiment, the adjustment step of the rotation angle of the same object in two adjacent selected elements is 45 degrees.

In addition to the polarization aberration measurement method of the projection objective lens of the present invention, the polarization aberration measurement method of the projection objective lens can also measure the polarization aberration of other elements.

The process of constructing all selected elements into a lambda function matrix and obtaining the Jones matrix of the projection objective PO is as follows:

S50: Definition

D = J _Q1 · J _P1 · E _in ;

S51: The simplified formula (1) is:

S52: Simplify the formula (2) into a linear function of the projection objective Jones matrix element and its complex conjugate product:

Specifically, formula (3) is based on different elements selected in the set of rotation angle groups, and different groups of light intensity values can be obtained based on the light intensity measuring device IS. Using a linear algebraic relationship, it can be obtained:

Among them, x, y = 1,2; to the left of the equal sign is the light intensity column I, which represents the measurement of different rotation angles of the four elements; to the right of the equal sign, the number of rows of the λ function matrix represents the number of measurements, and each column of the λ function matrix is The coefficient corresponding to the product of the Jones matrix element of the projection objective PO; the subscript indicates the product form of the Jones matrix element of the projection objective PO, and the superscript indicates the group number of the light intensity group.

Rewriting formula (4) into matrix form, we can get:

I = Γ (n) X

Among them, I is a light intensity matrix, Γ is a lambda function matrix, and X is a matrix composed of a projection objective Jones matrix element and a complex conjugate product thereof.

S53: Obtain a formula for calculating the elements in the λ function matrix: λ _{i, j, k, l} = U _l · M _ki · D _j , and calculate all elements in the λ function matrix Γ to construct a λ function matrix Γ;

J _P1 is the Jones matrix of the first polarizer P1, J _P2 is the Jones matrix of the second polarizer P2, J _Q1 is the Jones matrix of the first quarter wave plate Q1, and J _Q2 is the second quarter wave Jones matrix of slice Q2; E _in is the energy of the incident light; * represents the conjugate transpose; where i, j, k, l represent the subscripts of the elements in the Jones matrix of the projection objective PO, which take values 1 or 2 respectively; λ _{i, j, k, l} are the elements in the λ function matrix.

Next, step S6 is performed to calculate a Jones matrix of the projection objective PO according to the light intensity matrix and the lambda function matrix.

Specifically, by adjusting the first polarizer P1, the first quarter-wave plate Q1, the second quarter-wave plate Q2, and the second polarizer P2 with different rotation angles, the Jones matrix of the projection objective PO can be adjusted. Solve unknown parameters involved in.

Preferably, if S3 and S4 are repeatedly performed more than 16 times in S5, the least square method is used in S6 to calculate the approximate value of the Jones matrix of the projection objective lens, thereby effectively avoiding calculation errors and improving the calculation accuracy.

When using the least squares calculation, X = (Γ ^T (n) Γ (n)) ^-1 · Γ (n) ^T · I, by adjusting the first polarizer P1 and the first quarter with different rotation angles The wave plate Q1, the second quarter wave plate Q2, and the second polarizing plate P2 can solve the 7 unknown parameters involved in the Jones matrix of the projection objective PO:

Here J _{xx is} set to a real number and does not include a phase portion, so this method cannot measure wave aberrations.

When the projection objective lens polarization aberration measurement method of the present invention uses the least square method to calculate the Jones matrix of the projection objective lens, the main error source lies in the least square method, that is, the λ function matrix Γ. To reduce the calculation error, the λ function matrix can be reduced The condition number of Γ.

The analysis of the λ function matrix Γ shows that Γ is composed of two parts, that is, the part in front of the projection objective (P1, Q1) and the part behind the projection objective (Q2, P2). The Jones matrix of the two parts determines the λ of each row Coefficient, so the condition number of Γ is determined by the rotation angle (direction angle) of the front and back parts. For each group of rotation angle combinations determined, the condition number of Γ can be calculated, so that a rotation angle combination with a smaller number of conditions can be found to reduce the effect of random errors on the measurement results.

As for the method disclosed in the embodiment, since it corresponds to the structure disclosed in the embodiment, the description is relatively simple, and the relevant part may refer to the description of the structure part.

In summary, in the projection objective lens polarization aberration measurement method provided by the present invention, the projection objective lens polarization aberration measurement method obtains a light intensity matrix constructed by all groups of light intensity values and all selected The lambda function matrix constructed by the elements calculates the Jones matrix of the projection objective lens, that is, the measurement method of the present invention can directly calculate and obtain the Jones matrix of the projection objective lens. Compared with the existing method, the Mueller matrix is obtained by measuring first, and then the Mueller matrix is converted to Jones. The matrix method effectively avoids the result error caused by the depolarization effect of the conversion of the Mueller matrix to the Jones matrix, improves the measurement and calculation accuracy, and improves the product imaging effect.

The above description is only a description of the preferred embodiments of the present invention, and does not limit the scope of the present invention. Any changes and modifications made by those of ordinary skill in the art according to the above disclosure shall fall into the protection scope of the claims.

Claims

A method for measuring the polarization aberration of a projection objective, characterized in that the method for measuring the polarization aberration of a projection objective includes the following steps:

S1: A first polarizing plate (P1), a first quarter wave plate (Q1), a first condensing lens (L1), a projection objective (PO), a second converging lens (L2), The second quarter-wave plate (Q2), the second polarizer (P2), and the light intensity measuring device (IS);

S2: A rotation angle group set is established, and the elements in the rotation angle group set are the rotation angle of the first polarizer (P1), the rotation angle of the first quarter wave plate (Q1), and the second polarizer ( The combination of the rotation angle formed by the rotation angle of P2) and the rotation angle of the second quarter wave plate (Q2). The elements in the rotation angle group set are different from each other, where the rotation angle is the brightness of the polarizer. The angle between the fast axis of the axis or waveplate and the given direction;

S3: Select an element from the set of rotation angle groups, and adjust the first polarizing plate (P1), the first quarter wave plate (Q1), and the second quarter wave plate ( Q2) and the rotation angle of the second polarizer (P2);

S4: the light intensity measuring device (IS) measures a set of light intensity values corresponding to the current element;

S5: Repeat S3 and S4 at least 16 times to obtain multiple groups of light intensity values, wherein each time S3 is performed, a different element is selected and the multiple groups of light intensity values obtained by the light intensity measurement device (IS) measurement are constructed Is a light intensity matrix. All selected elements are constructed as a lambda function matrix. The elements in the lambda function matrix are the first polarizer (P1), the first quarter wave plate (Q1), and the second quarter. The coefficients of the elements in the Jones matrix of the wave plate (Q2) and the second polarizer (P2) and their complex conjugate products;

S6: Calculate a Jones matrix of a projection objective (PO) according to the light intensity matrix and the lambda function matrix.
The method for measuring the polarization aberration of a projection objective according to claim 1, wherein the light is calculated in S4 when the Jones matrix of the first condensing lens (L1) and the second condensing lens (L2) is not considered. The calculation formula for the strong value is as follows:

Among them, I is the light intensity value, E out is the energy of the outgoing light, E out = J P2 · J Q2 · J PO · J Q1 · J P1 · E in ; * represents the conjugate transpose; J P1 is the first polarization Jones matrix of the plate (P1), J P2 is the Jones matrix of the second polarizer (P2), J Q1 is the Jones matrix of the first quarter wave plate (Q1), and J Q2 is the second quarter wave Jones matrix of lens (Q2); J PO is the Jones matrix of projection objective (PO); Jones matrix of wave plate and polarizer are
with
R is the rotation matrix,
α is the rotation angle of the corresponding wave plate or polarizer; Ein is the energy of incident light.
The method for measuring the polarization aberration of a projection objective according to claim 2, wherein in S5, the step of constructing all selected elements into a lambda function matrix comprises the following steps:

S50: Definition
D = J Q1 · J P1 · E in ;

S51: Obtain a formula for calculating the elements in the λ function matrix: λ i, j, k, l = U l · M ki · D j , and calculate all elements in the λ function matrix to construct a λ function matrix;

Among them, U, M, and D are simplified matrices, and the matrices are expressed as U = [U 1 U 2 ],
J P1 is the Jones matrix of the first polarizer (P1), J P2 is the Jones matrix of the second polarizer (P2), J Q1 is the Jones matrix of the first quarter wave plate (Q1), and J Q2 is the first Jones matrix of the quarter-wave plate (Q2); E in is the energy of the incident light; * represents the conjugate transpose; where i, j, k, l represent the subscripts of the elements in the Jones matrix, and take values respectively 1 or 2; λ i, j, k, l are the elements in the λ function matrix.
The method for measuring polarization aberration of a projection objective according to claim 3, wherein in S6, calculating the Jones matrix of the projection objective (PO) according to the light intensity matrix and the lambda function matrix comprises the following steps:

S60: The simplified formula (1) is:

S61: Simplify the formula (2) into a linear function of the projection objective Jones matrix element and its complex conjugate product:

S62: Calculate elements in the Jones matrix of the projection objective (PO) to obtain the Jones matrix of the projection objective (PO);

Where J i, j are the elements in the Jones matrix of the projection objective (PO),
Complex conjugate of the elements in the Jones matrix of the projection objective (PO).
The method for measuring the polarization aberration of a projection objective according to claim 1, wherein if S3 and S4 are repeatedly performed more than 16 times in S5, the least square method is used in S6 to calculate an approximate value of the Jones matrix of the projection objective.
The method for measuring the polarization aberration of a projection objective according to claim 5, characterized in that, in S5, an adjustment step of each rotation angle in the selected element ranges from 30 to 60 degrees.
The method for measuring the polarization aberration of a projection objective according to claim 6, wherein the given direction is an X-axis or Y-axis direction.
The method of measuring the polarization aberration of a projection objective according to claim 1, wherein the first condensing lens (L1) and the second condensing lens (L2) are collimating lenses, and the two have different focal length.
The method of measuring the polarization aberration of a projection objective according to claim 1, wherein the first condensing lens (L1) enables light incident on the projection objective (PO) to have a first numerical aperture, and the second condensing lens (L2) converting light having a second numerical aperture emitted by the projection objective (PO) into parallel light, the second numerical aperture being larger than the first numerical aperture.
The method for measuring polarization aberration of a projection objective according to claim 1, characterized in that each point in the light intensity map obtained by the light intensity measurement device (IS) measurement corresponds to a point on the pupil surface of the projection objective (PO) .
The method for measuring the polarization aberration of a projection objective according to claim 1, wherein before the measurement is started, a stable light beam is selected as the incident light.