JP2006005197A - Aligner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aligner capable of simultaneously observing a plurality of alignment marks irrespective of the size of a pattern region depending on the device, and capable of designing a reticle without being bound by the arrangement places of the alignment marks. <P>SOLUTION: This aligner comprises a projection optical system for projecting a pattern on a first object onto a second object with exposure light; a plurality of measuring devices for illuminating the alignment marks on the second object in a place different from the exposure position of the second object with detection light having a wavelength different from that of the exposure light, detecting the positional information of the marks, and relatively aligning the first and the second objects; and a means for detecting and correcting the deformation of each pattern region of the second object resulting from the heat treatment during a semiconductor device process, and at least one of the measuring devices has a movable means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method of manufacturing a semiconductor device or a liquid crystal display panel, and in particular, in a semiconductor device or liquid crystal display panel manufacturing apparatus, a projection optical system converts an image of a circuit pattern on a reticle or mask surface onto each wafer or glass plate. It is used to manufacture a plurality of semiconductor devices by sequentially projecting and exposing the pattern region to the pattern region of the wafer or plate. The present invention is particularly suitable for an exposure apparatus for manufacturing a semiconductor element or a liquid crystal display panel called a so-called stepper or scanner, and particularly relates to high overlay accuracy and high-speed exposure operation. In the present invention, an exposure apparatus for manufacturing a semiconductor device and a panel exposure apparatus for a liquid crystal display are collectively referred to as a stepper.

  Conventionally, in a projection exposure apparatus for manufacturing a semiconductor, a reticle circuit pattern as a first object is projected and exposed on a wafer as a second object by a projection optical system. Prior to this projection exposure, an observation apparatus (detection means) is used. ) Is used to detect the alignment mark (AA mark) on the wafer surface, and based on the detection result, position alignment of the reticle and wafer, so-called alignment, is performed.

  As the pattern of a semiconductor integrated circuit is miniaturized, in a projection exposure apparatus, it has become necessary to detect and correct the amount of wafer deformation caused by heat treatment in a device process. For example, as disclosed in Japanese Patent Application Laid-Open No. 64-89327 and Japanese Patent Application Laid-Open No. 8-191045, a TTL type or off-axis type microscope has a function of aligning a reticle and a wafer, so-called alignment.

  In the above description, the technique for detecting and correcting the deformation amount of the wafer has been solved. However, when a semiconductor device is patterned on a glass wafer, the deformation amount of the glass wafer due to the influence of the heat treatment of the device process is large. Therefore, in order to accurately measure the deformation amount, at least three locations in each pattern region must be measured. The alignment marks must be sequentially sent to a position where the measuring device can detect them.

  The wafer is deformed by the heat treatment of the device process. In order to detect the amount of deformation, a plurality of alignment marks in each pattern area are observed. However, since the size of the pattern area differs depending on the device, a plurality of alignment marks in one pattern cannot be observed simultaneously. is there. Moreover, if the alignment marks are arranged so that a plurality of alignment marks can be measured simultaneously, there is a problem that the degree of freedom in reticle design is reduced.

  In view of such a conventional problem, the present invention provides a moving means to the alignment mark observation microscope so that a plurality of alignment marks can be observed simultaneously regardless of the size of the pattern region by the device, and the alignment is performed. It is an object of the present invention to provide an exposure apparatus capable of designing a reticle without being restricted by the mark arrangement location.

  In order to solve the above-mentioned problem, in the present invention, the exposure light is different from the projection optical system that projects the pattern of the first object onto the second object with the exposure light and the exposure position of the second object. A plurality of measuring devices that illuminate an alignment mark on the second object with detection light having different wavelengths, detect positional information of the mark, and perform relative alignment between the first object and the second object And an exposure apparatus having means for detecting and correcting a deformation amount of each pattern region of the second object caused by heat treatment of the semiconductor device process, wherein at least one of the measurement apparatuses has movable means. It is characterized by.

  According to a preferred aspect of the present invention, the measuring means has a movable means, and has means for simultaneously observing alignment marks arranged in each pattern area of the second object. . Further, it is desirable that the moving means has means capable of accurately moving to the measurement point of the alignment mark without error.

  According to the present invention, it is possible to accurately measure the amount of deformation of a wafer due to a device process in a short time without interfering with the projection exposure operation even if the size of the pattern region differs depending on the device. In this way, a change in magnification corresponding to the deformation amount of the obtained wafer can be appropriately corrected by a known correction means. As a result, it is possible to always maintain stable exposure regardless of the size of the circuit pattern area to be exposed and the type of wafer to be used, and to provide a high-throughput exposure apparatus with significantly improved image overlay accuracy. be able to.

  FIG. 1 is an overall schematic view of an exposure apparatus according to an embodiment of the present invention. In the figure, light emitted from an exposure light source 1 a irradiates a reticle 3 as a first object, and the pattern image is transferred to a wafer 5 as a second object by a projection optical system 4. The wafer 5 is fixed on a wafer stage 7 disposed on a surface plate 8. The reticle 3 is positioned on the reticle stage 3a by a reticle aligning device (not shown) and then held. The reticle stage 3a is moved in the X, Y, Z, and θ directions by a reticle stage driving means (not shown). The

  The wafer stage 7 can be moved in an XY plane (in a plane perpendicular to the optical axis of the projection optical system 4) by a drive system (not shown), and the amount of movement is for X and Y directions not shown. Monitored with a laser measuring instrument. The movable stage 7 is also movable in the Z direction (the optical axis direction of the projection optical system 4), and the position of the movable stage 7 in the Z direction is monitored by a Z direction position detecting unit (not shown).

  A wafer stage reference mark 7a is placed on the wafer stage 7, and a reticle reference plate 3b is placed on the reticle stage 3a. Reference numeral 2 denotes a TTL-ONAXIS alignment microscope (hereinafter abbreviated as a TTL microscope) as a first measuring means. The TTL microscope 2 simultaneously observes the wafer stage reference mark 7a on the wafer stage 7 through the reticle reference mark 3b and the projection lens 4, and aligns the reticle stage and the wafer stage. Further, since the positional relationship can be corrected with respect to the change over time, the positional relationship is maintained.

  Reference numerals 6a, 6b, and 6c (6b and 6c do not appear in FIG. 1) are off-axis microscopes as the second measuring means, which are placed at positions different from the exposure positions regardless of the TTL method. The wafer stage reference mark 7a observed with the TTL microscope is sent to the observation position of the wafer stage up to the observation position of the off-axis microscope. The first measuring device and the second measuring device are aligned by monitoring the amount fed in with a laser length measuring device. Further, since the positional relationship can be corrected with respect to a change with time, the positional relationship is maintained.

  On the wafer 5, a circuit pattern formed up to the previous process and a plurality of alignment marks (alignment marks) 5a, 5b, 5c arranged in a certain positional relationship with the circuit pattern are formed. At least two of the alignment marks 5a, 5b, and 5c on the wafer 5 are measured by the off-axis microscopes 6a, 6b, and 6c, and the relative positioning with respect to the reticle 3 is performed.

  The projection optical system 4 is carried on a lens barrel surface plate (not shown). As will be described later, a predetermined lens among a plurality of lenses constituting the projection optical system 4 can be moved as means for correcting magnification by deformation of the wafer. The lens driving means is disposed on the screen.

  2 and 3 are schematic views illustrating an example of a plurality of off-axis microscopes according to an embodiment of the present invention. 2 and 3, the driving unit of the off-axis microscope does not appear. The off-axis microscopes 6b and 6c are movable in the direction of the arrows, and the positional relationship is maintained because the positional relationship is monitored by an optical scale or a laser length measuring device. The off-axis microscopes 6a, 6b and 6c A plurality of wafer alignment marks (alignment marks) 5a, 5b, and 5c formed in each pattern region on the wafer up to the previous process are simultaneously observed to measure the deformation amount of the wafer caused by the heat treatment of the device process.

  Next, moving means of the off-axis microscope will be described. FIG. 4 is a first example of an off-axis microscope driving unit in the present invention.

  The off-axis microscope unit 11 is driven by a linear motor 9 through an air bearing 12, and the amount of movement is read with an optical scale of 10. The linear motor 9 may be a stepping motor via a ball screw or the like, and the optical scale 10 may be a laser length measuring device. Although excitation of the drive motor can be considered as a method of stopping, in the present invention, there is a concern about the influence of heat. Therefore, it is desirable to drop the supply air of the air bearing 12 and lock with the magnet 13.

  FIG. 5 shows a second example of an off-axis microscope driving unit according to the present invention.

  The difference from the first example is that a linear motion guide 16 is used as a guide, and a locking mechanism is provided by a suction pad 14 and a magnet 13 via a leaf spring 15 as a stopping method.

It is the schematic which shows the structure of the projection exposure apparatus by the Example of this invention. FIG. 2 is a plan view of the arrangement of the projection optical system and the off-axis microscope in FIG. 1 as viewed from above, and is an example of a device. FIG. 2 is a plan view of the arrangement of the projection optical system and the off-axis microscope in FIG. 1 as viewed from above, and is an example of a device. It is the schematic which shows the drive part of the 1st Example of the off-axis microscope in this invention. It is the schematic which shows the drive part of the 2nd Example of the off-axis microscope in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a Exposure light source 1b Mirror 1c Condensing lens 2 TTL alignment microscope 3 Reticle 3a Reticle stage 3b Reticle reference mark 4 Projection optical system 5 Wafer 5a-5c Alignment mark 6a Reference | standard off-axis microscope 6b Y movable off-axis microscope 6c X movable Off-axis microscope 7 Wafer stage 7a Wafer stage reference mark 8 Wafer stage surface plate 9 Linear motor 10 Optical scale 11 Off-axis microscope 12 Air bearing 13 Magnet 14 Suction pad 15 Leaf spring 16 Linear guide

Claims (5)

  The projection optical system for projecting the pattern of the first object onto the second object with the exposure light and the detection light having a wavelength different from the exposure position of the second object on the second object A plurality of measuring devices that illuminate the alignment mark of the first mark, detect position information of the mark, and perform relative alignment between the first object and the second object, and are generated by heat treatment of a semiconductor device process. An exposure apparatus having means for detecting and correcting a deformation amount of each pattern area of two objects, wherein at least one of the measurement apparatuses has movable means.   2. The exposure apparatus according to claim 1, wherein when the semiconductor device is manufactured by projecting and transferring the circuit pattern of the first object onto the second object, a plurality of the alignments arranged in the exposure region of each pattern. An exposure apparatus that measures marks simultaneously.   3. The exposure apparatus according to claim 1, wherein the moving means includes a linear motion driving mechanism, and a plurality of the alignment marks arranged in the exposure area of each pattern via a linear motion guide or the like. The exposure apparatus is characterized in that it moves to a position where it can be observed simultaneously.   4. The exposure apparatus according to claim 3, wherein the moving means includes measuring means such as a laser length measuring device or an optical scale, and monitors the moving amount and the positional relationship of the measuring apparatus. .   4. The exposure apparatus according to claim 3, wherein the moving means includes a lock mechanism for stopping after moving the alignment mark to a position where it can be observed simultaneously.

Images