JP2006120661A - Projection aligner and inspection method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection aligner for measuring fluctuation in the numerical aperture and diaphragm of a lens easily and accurately, and to provide a method of inspecting the projection aligner. <P>SOLUTION: The projection aligner comprises a fly eye, the diaphragm, a masking blade; the lens, a reticle stage for holding a reticle in which a mask pattern is formed, a reduction projection lens for reducing the mask pattern on the reticle for projection, and a wafer stage for exposing the mask pattern on the reticle to light. In the projection aligner, a shade is installed at a position for shielding only one portion of luminous flux in parallel with the diaphragm for exposure, at least at the upper or the lower portion of the diaphragm. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a projection exposure apparatus and a projection exposure apparatus inspection method, and more particularly to a projection exposure apparatus and a projection exposure apparatus inspection method that can easily and accurately measure lens aperture ratio and aperture variation.

  In manufacturing a semiconductor integrated circuit device, usually, a photolithography process of 10 or more processes is required. In the photolithography process, a projection exposure apparatus is used, and in recent years, a demand for forming a fine pattern on a mask with high accuracy and stability is increasing.

  The most important factor in determining the performance of the projection exposure apparatus is the performance of the projection lens system composed of around ten lenses. In particular, the numerical aperture (NA) of the projection lens and the lens aperture σ are important. In other words, in order to form a fine pattern accurately and stably, it is important to carry out apparatus management so that there is no effective NA and σ fluctuation of the projection exposure apparatus.

  For this purpose, it is necessary to accurately measure fluctuations in NA and σ during the use of the projection exposure apparatus. Until now, patterns such as dots, pinholes, and grating pinholes were created for each NA and σ on the backside of the reticle, and the reticle pattern was baked on the wafer, or each position was measured with an illuminance distribution meter on the wafer stage. The effective NA and σ of the projection exposure apparatus are measured by a method of measuring the illuminance for each.

  However, in the conventional method for measuring NA and σ of the projection exposure apparatus, it is necessary to redesign the reticle pattern for each NA and σ and to burn the reticle pattern, which is troublesome and hence accurate. There was a problem that could be damaged.

  The present invention has been made based on the recognition of such a problem, and an object of the present invention is to provide a projection exposure apparatus and a projection exposure apparatus inspection method that can easily and accurately measure lens aperture ratio and aperture variation. is there.

In order to achieve the above object, according to one aspect of the present invention,
Fly eye,
Aperture,
A masking blade,
A lens,
A reticle stage for holding a reticle on which a mask pattern is formed;
A reduction projection lens for reducing and projecting the mask pattern on the reticle;
A wafer stage on which the mask pattern on the reticle is exposed;
A projection exposure apparatus comprising:
There is provided a projection exposure apparatus characterized in that exposure can be performed in a state in which a light shielding plate is placed at a position parallel to the diaphragm and shields only a part of a light beam at least above and below the diaphragm.

According to another aspect of the present invention,
Fly eye,
Aperture,
A masking blade,
A lens,
A reticle stage for holding a reticle on which a mask pattern is formed;
A reduction projection lens for reducing and projecting the mask pattern on the reticle;
A wafer stage on which the mask pattern on the reticle is exposed;
A projection exposure apparatus comprising:
There is provided a projection exposure apparatus characterized in that telecentricity can be measured in a state where a light shielding plate is installed at a position parallel to the diaphragm and shields only a part of a light beam at least above and below the diaphragm. The

  Here, any one of a plurality of shielding plates having different light shielding patterns can be selected as the light shielding plate.

Meanwhile, according to yet another aspect of the present invention,
A fly eye, an aperture, a masking blade, a lens, a stage holding a reticle on which a mask pattern is formed, a reduction projection lens for reducing and projecting the mask pattern on the reticle, and on the reticle An inspection method of a projection exposure apparatus having a wafer stage on which the mask pattern is exposed,
Calculate the aperture ratio of the optical system and the change of the aperture by measuring the telecentric value by installing a light shielding plate at a position that is parallel to the aperture and shields only a part of the light beam at least above and below the aperture. An inspection method for a projection exposure apparatus is provided.

  Here, any one of a plurality of shielding plates having different light shielding patterns can be selected as the light shielding plate.

  According to the present invention, it is possible to easily and accurately measure lens aperture ratio and aperture variation without recreating a reticle for each NA and σ.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic view illustrating the structure of a projection exposure apparatus according to an embodiment of the present invention.
That is, FIG. 1 shows the main structure of the optical system of the reduction projection exposure apparatus 1 in which the shielding plate 10 is inserted into the apparatus. As shown in the figure, the light emitted from the light source projects the fly eye 11, the diaphragm 12, the masking blade 13, the lens 14, the reticle 15 on which the mask pattern is formed, and the mask pattern in a reduced size. It passes through the reduction projection lens 16 in this order and reaches the wafer 17. A wafer 17 coated with a photoresist is set in the projection exposure apparatus 1, and one chip is exposed by a reduction projection method through a mask pattern on a reticle 15 that is several times larger than an actual pattern. When finished, the entire surface of the wafer 17 is scanned by the next step-and-repeat method. That is, the exposure is performed by reducing the pattern on the reticle 15 with the reduction projection lens 16 and projecting it onto the wafer 17.

  In the projection exposure apparatus according to the embodiment of the present invention, the shielding plate 10 is provided between the stop 12 and the masking blade 13. As shown in the figure, the plate-shaped shielding plate 10 is installed in parallel to both the diaphragm 12 and the masking blade 13. Further, it is installed so as to shield a part of the light that has passed through the diaphragm 12 rather than the entire surface.

FIG. 2 is a schematic view illustrating the planar structure of the shielding plate provided in the projection exposure apparatus according to the embodiment of the invention.
As shown in the figure, the shielding plate 10 has a rectangular plate shape and shields about the right half of the light beam 18 that has passed through the diaphragm 12.

  In this way, telecentricity is measured in advance with the shielding plate 10 provided in the reduced projection exposure apparatus 1. In general, if the shielding plate 10 is not inserted, the chief ray should be parallel to the optical axis 19. However, in the embodiment of the present invention, since the shielding plate 10 is provided between the stop 12 and the masking blade 13, the principal ray 20 is bent and is not parallel to the optical axis 19. That is, the telecentric value has a slope.

  Subsequently, with the same shielding plate 10 provided in the reduction projection exposure apparatus 1, the lens aperture ratio (NA) and the illumination system stop σ are changed, and the telecentricity is measured. As NA and σ change, the chief ray 20 bends further and the telecentric value also changes.

  FIG. 3 is a graph showing the relationship between the (NA × σ) value and the telecentric value. That is, the horizontal axis in the figure represents the (NA × σ) value, and the vertical axis represents the telecentric value. As the (NA × σ) value increases, the telecentric value also increases with a certain slope, indicating that the (NA × σ) value and the telecentric value are in a proportional relationship.

  That is, in the projection exposure apparatus according to the embodiment of the present invention, the NA and σ desired to be monitored are set, and the telecentric value is measured with the shielding plate 10 inserted. By comparing the measured telecentric value with the telecentric value of FIG. 3, it becomes possible to monitor the change of NA and σ. By periodically measuring such telecentric values, it becomes possible to detect changes in NA and σ simply and accurately. As a result, the transfer performance of the projection exposure apparatus can be stabilized.

In the conventional method of measuring using a reticle, it is necessary to redesign and create a reticle pattern for each setting of NA and σ. However, in the projection exposure apparatus according to the embodiment of the present invention, it is not necessary to change the shielding plate 10 for each setting of NA and σ. Therefore, the projection exposure apparatus according to the embodiment of the present invention is effective as a simple method for monitoring changes in NA and σ.
That is, according to the projection exposure apparatus of the present invention, it is possible to easily detect changes in NA and σ while the shielding plate is inserted without redesigning the reticle pattern. As a result, a fine pattern can be formed accurately and stably.

Next, an example in which the shielding plate 10 is modified will be described as a first embodiment of the present invention.
FIG. 4 is a schematic view illustrating the planar structure of the shielding plate provided in the projection exposure apparatus according to the first embodiment of the present invention. As shown in the figure, the shielding plate 10 can take various shapes as well as a rectangle. Moreover, the position which provides the shielding board 10 may be various positions.

In FIG. 4A, the shielding plate 10 has a rectangular plate shape and shields about the lower half of the light beam 18 that has passed through the diaphragm 12. Thus, by changing the position of the shielding plate 10, it is possible to know changes in NA and σ at various positions of the light beam 18.
In FIG. 4B, the shielding plate 10 is L-shaped, and shields a portion of the light beam 18 that has passed through the diaphragm 12 other than the sector shape having a central angle of 90 degrees.
In FIG. 4C, two rectangular plate-shaped shielding plates 10 are provided. These shielding plates are provided in parallel with a distance therebetween, and shield the upper and lower sides of the light beam 18 that has passed through the diaphragm 12.
In FIG. 4D, the shielding plate 10 has a rectangular plate shape and shields about the right half of the light beam 18 that has passed through the diaphragm 12.

  In this way, the shielding plates 10 having different shapes can be attached to the projection exposure apparatus in a revolver manner, and the telecentric values of the respective shielding plates can be measured. As a result, it is possible to know the change of NA and σ in various regions by dividing the light flux in various ways.

  Next, a second embodiment of the present invention will be described.

FIG. 5 is a schematic view illustrating the cross-sectional structure of the projection exposure apparatus according to the second embodiment of the invention.
As shown in the figure, in the present embodiment, the shielding plate 10 is provided between the diaphragm 12 and the fly eye 11. Thus, even if the shielding plate 10 is installed in front of the diaphragm 12, the principal ray 20 is not parallel to the optical axis but bends, so that changes in NA and σ can be known from the telecentric values. That is, even if the shielding plate 10 is provided between the diaphragm 12 and the fly eye 11, the same effect as that of the projection exposure apparatus according to the embodiment of the present invention can be obtained.

Next, a third embodiment of the present invention will be described. That is, a telecentric measurement method in the projection exposure apparatus according to the embodiment of the present invention will be described.
FIG. 6 is a schematic diagram for explaining a telecentric measurement method in the projection exposure apparatus according to the third embodiment of the present invention.

In order to measure the telecentric value of the projection exposure apparatus according to the embodiment of the present invention, first, a pattern capable of measuring a position such as a line shape is set on the reticle stage, and the X of the projected image on the wafer stage. -Provide a mechanism capable of measuring the position in the Y direction. Then, using the illuminometer on the wafer stage, the telecentric is calculated from the position (X, Y direction) shift amount of the pattern projection image 21 on the reticle when the stage is moved in the focus direction (Z direction).
When the telecentric value is measured in this way, the measurement and telecentric value calculation can be performed in the projection exposure apparatus without printing the combined measurement pattern for calculating the telecentric value on the wafer and without performing the alignment measurement by the development work and the alignment measuring device. Can be processed. This function simplifies monitoring and further shortens the monitoring time.

  In addition, in order to measure the telecentric value of the projection exposure apparatus according to the embodiment of the present invention, for example, the resist pattern of a mark having a shape that can be combined and measured, such as Box in Box, is focused on the wafer 17 and is doubled. A method of calculating telecentricity from the ratio of the focus change amount and the pattern shift amount at the time of performing exposure can also be used.

The embodiments of the present invention have been described above with reference to specific examples.
However, the present invention is not limited to these specific examples. For example, specific structures such as a fly eye, a diaphragm, a masking blade, a reduction lens, and a shielding plate included in the projection exposure apparatus of the present invention are appropriately selected from those known by those skilled in the art within the scope of the present invention. Is done.

It is a schematic diagram which illustrates the structure of the projection exposure apparatus concerning embodiment of this invention. It is a schematic diagram which illustrates the planar structure of the shielding board provided in the projection exposure apparatus concerning embodiment of this invention. It is a graph showing the relationship between the NA × σ value and the telecentric value in the projection exposure apparatus according to the embodiment of the present invention. It is a schematic diagram which illustrates the planar structure of the shielding board provided in the projection exposure apparatus concerning the 1st Example of this invention. It is a schematic diagram which illustrates the cross-section of the projection exposure apparatus concerning the 2nd Example of this invention. It is a schematic diagram for demonstrating the telecentric measuring method in a projection exposure apparatus concerning the 3rd Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Projection exposure apparatus 10 Shielding plate 11 Fly eye 12 Aperture 13 Masking blade 14 Lens 15 Reticle 16 Reduction projection lens 17 Wafer 18 Light beam 19 Optical axis 20 Main light 21 Pattern projection image on reticle

Claims (5)

Fly eye,
Aperture,
A masking blade,
A lens,
A reticle stage for holding a reticle on which a mask pattern is formed;
A reduction projection lens for reducing and projecting the mask pattern on the reticle;
A wafer stage on which the mask pattern on the reticle is exposed;
A projection exposure apparatus comprising:
A projection exposure apparatus characterized in that exposure can be performed in a state in which a light shielding plate is installed at a position parallel to the diaphragm and shields only a part of a light beam at least above and below the diaphragm. Fly eye,
Aperture,
A masking blade,
A lens,
A reticle stage for holding a reticle on which a mask pattern is formed;
A reduction projection lens for reducing and projecting the mask pattern on the reticle;
A wafer stage on which the mask pattern on the reticle is exposed;
A projection exposure apparatus comprising:
A projection exposure apparatus characterized in that telecentricity can be measured in a state where a light-shielding plate is disposed at least above or below the diaphragm in a position parallel to the diaphragm and shielding only a part of a light beam.   The projection exposure apparatus according to claim 1, wherein any one of a plurality of shielding plates having different light shielding patterns can be selected as the light shielding plate. A fly eye, an aperture, a masking blade, a lens, a stage holding a reticle on which a mask pattern is formed, a reduction projection lens for reducing and projecting the mask pattern on the reticle, and on the reticle An inspection method of a projection exposure apparatus having a wafer stage on which the mask pattern is exposed,
Calculate the aperture ratio of the optical system and the change of the aperture by measuring the telecentric value by installing a light shielding plate at a position that is parallel to the aperture and shields only a part of the light beam at least above and below the aperture. An inspection method for a projection exposure apparatus. 5. The projection exposure apparatus inspection method according to claim 4, wherein one of a plurality of shielding plates having different light shielding patterns can be selected as the light shielding plate.

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