MEASUREMENT METHOD

Abstract

A method for irradiating onto a target optical system plural linearly polarized rays having different polarization directions, and for measuring a polarization characteristic of the target optical system including a birefringence amount R and a fast axis Φ includes the steps of irradiating linearly polarized ray having a polarization direction θ onto the target optical system and obtaining a centroid amount P of the ray that has transmitted through the target optical system, and obtaining the birefringence amount R and the fast axis Φ from P=−R·cos(2θ−Φ) or P=R·cos(2θ−Φ).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing that an actual value of the retardance and a value of the retardance obtained as a result of that a phase difference between a pair of orthogonal elements of the eigenvector (characteristic vector) of the Jones matrix is approximated to nπ are proportional.

FIG. 2 is a graph showing that an actual value of the fast axis and a value of the fast axis obtained as a result of that a phase difference between a pair of orthogonal elements of the eigenvector of the Jones matrix is approximated to nπ are proportional.

FIGS. 3A and 3B show retardance distributions in the pupil of the projection optical system. More particularly, FIG. 3A is directed to a theoretical value, and FIG. 3B is directed to a result of an approximation according to this embodiment.

FIGS. 4A and 4B show fast-axis distributions in the pupil of the projection optical system. More particularly, FIG. 4A is directed to a theoretical value, and FIG. 4B is a result of an approximation according to this embodiment.

FIG. 5 is a schematic block diagram of an exposure apparatus that calculates a centroid amount of the light using the point diffraction interferometry (“PDI”).

FIG. 6 is a schematic block diagram showing a structure of a polarization unit shown in FIG. 5.

FIG. 7 is a schematic block diagram for explaining the PDI.

FIG. 8 is a schematic block diagram of a variation of an exposure apparatus shown in FIG. 5.

FIG. 9 is a schematic block diagram for explaining the PDI of the exposure apparatus shown in FIG. 8.

FIG. 10 is a schematic block diagram of the exposure apparatus that calculates the centroid amount of the light using the lateral sharing interferometry (“LSI”).

FIG. 11 is a schematic block diagram of the LSI of the exposure apparatus shown in FIG. 10.

FIG. 12 is a schematic block diagram of the exposure apparatus that calculates the centroid amount of the light using the ISI lateral shift measurement method.

FIG. 13 is a schematic block diagram for explaining the ISI lateral shift measurement method of the exposure apparatus shown in FIG. 12.

FIG. 14 is a schematic plane view of an ISI mask pattern shown in FIG. 13.

FIG. 15 is a schematic plane view showing another ISI mask pattern applicable to FIG. 13.

FIG. 16 is a schematic block diagram of another exposure apparatus that calculates the centroid amount of the light using the ISI lateral shift measurement method.

FIG. 17 is a schematic block diagram of an exposure apparatus that calculates the centroid amount of the light using the Hartmann measurement method.

FIG. 18 is a schematic block diagram for explaining the Hartmann measurement method by the exposure apparatus shown in FIG. 17.

FIG. 19 is a schematic block diagram of another exposure apparatus that calculates the centroid amount of the light using the Hartmann measurement method.

FIG. 20 is a schematic block diagram for explaining the Hartmann measurement method by the exposure apparatus shown in FIG. 19.

FIG. 21 is a schematic block diagram of an exposure apparatus that calculates the centroid amount of the light using the SPIN measurement method.

FIG. 22 is a schematic block diagram for explaining the SPIN measurement method of the exposure apparatus shown in FIG. 21.

FIG. 23 is a schematic plane view of a measured mark shown in FIG. 21.

FIGS. 24A and 24B are sectional and plane views showing an illustrative application of FIG. 22.

FIGS. 25A and 25B are schematic sectional views of a structure of the mask shown in FIGS. 24A and 24B applicable to the LSI lateral measurement method or another method.

FIG. 26 is a flowchart for explaining a measurement method according to this embodiment.

FIG. 27 is a graph showing that a phase difference between a pair of orthogonal elements of the eigenvector in the Jones matrix can be approximated to nπ when the birefringence amount is small.

FIG. 28 is a flowchart for explaining manufacture of a device.

FIG. 29 is a detailed flowchart of a wafer process of step 4 shown in FIG. 28.

Claims

1. A method for irradiating onto a target optical system plural linearly polarized rays having different polarization directions, and for measuring a polarization characteristic of the target optical system including a birefringence amount R and a fast axis Φ, said method comprising the steps of: irradiating linearly polarized ray having a polarization direction θ onto the target optical system and obtaining a centroid amount P of the ray that has transmitted through the target optical system; andobtaining the birefringence amount R and the fast axis Φ from P=−R·cos(2θ−Φ) or P=R·cos(2θ−Φ).

2. A method according to claim 1, wherein the polarization characteristic further includes a Jones matrix M defined in the following equation, and said method further comprising the step of obtaining the Jones matrix M by irradiating two linearly polarized rays having different polarization directions onto the target optical system and measuring transmittances A and A′ of the target optical system for the two linearly polarized rays: M=[A·exp(−i·m), a·exp(−i·b); a·exp(−i·b), A′·exp(i·m)]a=2A″·sin R·Ex·Ey, A″=(A+A′)/2,b±π/2,m=Arg{A·Ey2·exp(−i·R)+A′·Ex2·exp(i·R)},Ex=√{(1+cos Φ)2},Ex2+Ey2=1

3. A method for irradiating onto a target optical system plural linearly polarized rays having different polarization directions, and for measuring a polarization characteristic of the target optical system, said method comprising the steps of: obtaining a relationship between an actual value of the polarization characteristic of the target optical system and a value of the polarization characteristic obtained under an approximation of an eigenvector of a Jones matrix of the target optical system to a linearly polarized ray;obtaining a centroid amount determined by light intensities and phases of two rays divided due to birefringence of the target optical system; andcalculating the polarization characteristic based on the relationship and the centroid amount of the rays.

4. A method according to claim 3, wherein the relationship is a proportion.

5. A method according to claim 3, wherein the target optical system includes plural lenses, and a distribution range of the birefringence amount falls within 30°.

6. A method according to claim 3, further comprising the step of changing the polarization direction of the ray.

7. A method according to claim 3, wherein said centroid obtaining step utilizes a point diffraction interferometry, a lateral shearing interferometry, or Hartmann method.

8. An exposure apparatus comprising a projection optical system for projecting a reticle pattern onto a substrate, the projection optical system being adjusted based on a polarization characteristic measured by a method that irradiates onto the projection optical system plural linearly polarized rays having different polarization directions, the polarization characteristic including a birefringence amount R and a fast axis Φ of the target optical system, the method including the steps of irradiating the linearly polarized ray having a polarization direction θ onto the target optical system and obtaining a centroid amount P of the ray that has transmitted through the target optical system, and obtaining the birefringence amount R and the fast axis Φ from P=−R·cos(2θ−Φ) or P=R·cos(2θ−Φ).

9. A device manufacturing method comprising the steps of: exposing a substrate using an exposure apparatus; anddeveloping the substrate exposed,wherein the exposure apparatus includes a projection optical system for projecting a reticle pattern onto a substrate, the projection optical system being adjusted based on a polarization characteristic measured by a measurement method that irradiates onto the projection optical system plural linearly polarized rays having different polarization directions, the polarization characteristic including a birefringence amount R and a fast axis Φ of the target optical system, the measurement method including the steps of irradiating the linearly polarized ray having a polarization direction θ onto the target optical system and obtaining a centroid amount P of the ray that has transmitted through the target optical system, and obtaining the birefringence amount R and the fast axis Φ from P=−R·cos(2θ−Φ) or P=R·cos(2θ−Φ).