JPH04127641U - exposure equipment - Google Patents

Abstract

(57) [Summary] [Purpose] In reduction projection exposure equipment and electron beam lithography equipment,
It reduces errors due to asynchronous vibration of the structure caused by step movement of the wafer moving table, enabling high speed and high precision. [Structure] An interferometer 12a for laser length measurement is fixed to the wafer 8 side (image side) of the lens 1, and the other end is fixed to the wafer 8 side (image side) of the lens 1. Linear guide 1 fixed to column 3
It is fixed to the interferometer holding plate 11a guided in the expansion and contraction direction by 3a.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This invention is for improving semiconductor manufacturing equipment, especially reduction projection exposure equipment and electron beam lithography equipment. Regarding good.

0002

[Conventional technology]

For example, in the case of a reduction projection exposure system, after the wafer is moved stepwise and stopped, the lens A reduced projection image of the semiconductor circuit pattern is transferred onto the wafer and this process is repeated. However, in order to measure the wafer position, the mirror on the wafer moving stage and the base are A fixed interferometer constitutes a laser interferometer. Meanwhile, on the base The column is fixed, above which the lens and patterned reticle are moved. The table, pattern detector that detects the pattern position on the wafer, etc. are fixed at a fixed position. It is. However, the above structures such as the base, interferometer, column, and lens are not ideal. Since it is not a rigid body, vibration is caused by inertia force when the wafer moving table moves stepwise or stops. and each It vibrates asynchronously and attenuates according to its vibration characteristics. Therefore, the laser length measurement value is Even if exposure is performed after convergence within the range, the transfer accuracy may be insufficient. this To solve this problem, it is necessary to increase the rigidity of the structure and element support, or reduce the inertial force. However, it is quite difficult due to limitations in materials and equipment configuration. After all, high precision is required If the The gimmick is that when demanding high throughput, accuracy must be sacrificed. There is a message.

0003 On the other hand, in the case of an electron beam lithography system, the wafer is moved stepwise and then exposed in two directions after stopping. There are some differences between the pattern transfer method and the pattern data direct writing method. However, there are precedents for asynchronous vibration of the lens barrel and interferometer support that make up the electron lens system. It is also problematic. Also, in the method of synchronized drawing while the wafer is moving, Asynchronous vibrations in various parts due to inertial force inside the machine or when changing direction pose a problem.

0004 Additionally, related devices of this type are discussed, for example, in the following documents:

[0005] 1. Precision Machinery Design Handbook June 30, 1982 Japan Society of Precision Machinery Engineers p619 2. Nikkei Electronics 1984.2.4 p149 3. Japanese Patent Publication No. 59-72135 4. Japanese Patent Publication No. 1983-200726 5. Japanese Patent Publication No. 1983-55210

[0006]

[Problem that the idea aims to solve]

The above-mentioned conventional technology focuses on the lens group configuration, especially between the image side that controls the image formation position and the wafer. The root of the problem lies in the lack of direct measurement. Interferometry is a method close to direct measurement. Composition of a bender mirror installed on the recording side and a corner cube installed on the image side of the lens There is also a method to create a reference beam using a bender mirror and have it interfere with the wafer moving table measurement beam. - Asynchronous vibrations in the support and thermal mass fluctuations in the reference optical path (due to air entering and exiting with different temperatures) Dissatisfaction remains as new errors occur due to changes in optical path length (changes in optical path length).

[0007] The purpose of this invention is to provide a high-speed, high-precision exposure device that does not have the above-mentioned problems. Yes.

[0008]

[Means to solve the problem]

In order to solve the above purpose, in this invention, an interferometer is installed on the image side of the lens. This is how it was done. In addition, as another measure for high speed and high precision, vibration amplitude and inertia force are Since the moving mass of the moving table and the moving mass of the moving table are proportional to each other, it is possible to downsize the moving table and reduce the moving mass. In order to reduce this, the following measures have been prepared.

[0009] 1. A method for measuring the pitching of the moving table and a method for measuring pitching within the moving plane based on the measured value. Means is provided for correcting the position of the wafer at.

0010 2. A light receiver for measuring exposure energy of the wafer is provided within the wafer holding area. 3. Receives the original image projected by the illumination light of the pattern detector instead of the substrate and a light receiver for self-monitoring the device by detecting its relative position with the moving table, etc. is provided within the wafer holding area.

[0011]

[Effect]

In other words, the interferometer and movement installed on the image side of the lens, which controls the imaging position, Laser measurement between the mirrors on the table is like measuring directly between the image and the wafer. This avoids errors caused by asynchronous vibration of the structure in the conventional example.

0012 In addition, the pitching measurement means and wafer position correction means described in Section 1 above usually have Abbe errors. In order to avoid The most effective way to reduce the size of the moving table is to form a mirror on the side of the wafer chuck. shape, resulting in a reduction in vibration amplitude. In addition, the normal wafer chat mentioned in 2 and 3 above. The exposure energy measurement receiver and the self-monitoring receiver are located close to the Because the measurement is performed before wafer exposure, it does not conflict with the wafer holding function and therefore When holding large substrates such as 8-inch wafers, the receivers for them are placed inside the chuck. By providing this, the moving platform can be made smaller and the vibration amplitude can be reduced as a result.

[0013]

【Example】

A reduction projection exposure apparatus is shown in FIGS. 1 to 4 as an embodiment of the present invention. In the figure A reduction lens 1 is attached to a column 3 fixed on a base 2 supported by anti-vibration. ing. In addition, the illumination system 4 illuminates the reticle uniformly, and the reticle moving table 5 moves the reticle to a predetermined position. A semiconductor circuit pattern is formed on the reticle 6 aligned with the The pattern image is transferred to the wafer 8 on the wafer moving stage 7 by the reduction lens 1. , and the pattern detector 9 detects the alignment pattern of the wafer 8 through the reduction lens 1. They are arranged to satisfy each imaging relationship so that they can be detected. On the other hand, The wafer moving table 7 moves the wafer in the Y direction, X direction, θx, θy, With a 5-stage stacked structure of dθz, dX, dY, dZ direction compound fine movement, Z movement, θz movement, Mainly composed of light alloy materials. In addition, for each of the above-mentioned moving means, for example, X and Y are This method uses a ball screw to drive a line-guided table by converting rotational motion into linear motion. Therefore, θx~dZ is the piezoelectric element actuator with elastic hinges at both ends. This method uses a method that directly makes compound micro-movement of a supported platform to guide movement in directions other than the expansion/contraction direction. Therefore, Z is a platform approximately guided by a four-bar link, and the same linear motion as X and Y is further levered. θz is guided by a cylindrical fit on the Z stand by the method of driving by changing the direction with -. The lever attached to the wafer chuck is driven directly in the same way as X and Y. However, since each of the above-mentioned systems is a known technique, detailed explanation will be omitted.

[0014] Next, the mirrors 10a and 10b for laser length measurement are operated step by step. It is arranged perpendicularly to the upper surface of the dZ fine movement section. (Place the mirror on the top surface of the moving table. The provision above Z and θz is not adopted for the following reasons. That is, Z is the wafer The thickness variation of This is a correction operation that is performed after the operation, but in this example, the guide surface can be fixed by vacuum suction after the operation. Since the rigidity is relatively low, there is a risk of worsening the vibration characteristics of the moving platform, and θz Therefore, there is a risk that the rotation accuracy requirements for the wafer loader will become stricter. ) On the other hand, the lower part (image side) of the reduction lens 1 is made of a material with a small expansion coefficient. The interferometer holding plates 11a and 11b are fixed and are connected to the mirrors 10a and 10b for laser measurement. The interferometers 12a and 12b constituting the long meter are held at the other end, and the upper part is fixed to the column 3. It is guided in the expansion and contraction direction by fixed linear guides 13a and 13b. here In addition to the position (X, Y) of the wafer moving table 7, the laser length measuring meter also measures the position change due to movement. X , Y axes have three optical paths: X, Xp, Xy, and Y, Yp, Yy. The pitching and yaw are calculated from each measurement value using the following formula, for example. Ru.

[0015] Amount of movement in the X direction from the reference point X, Xp, Xy Amount of movement in the Y direction from the reference point Y, Yp, Yy Pitching due to movement in the X direction θy∝X−Xp Pitching due to movement in Y direction θx∝Y-Yp Yawing due to movement in the X direction (dθz)x∝X−Xy Yawing due to movement in the Y direction (dθz)y∝Y−Yy…(Equation 1) These measurement values are provided at the tip of the reduction lens to measure the surface shape of the wafer. A control CPU (not shown) is used along with the measured values of a leveling sensor (not shown). ) to control the drive system in the form of a software servo system, etc. However, since these control systems are well known, their explanation will be omitted.

[0016] Further, a wafer chuck for suctioning and fixing the wafer 8 is provided at the top of the wafer moving table 7. A hole 14 is provided as the upper element for the θz movement, and the wafer exposure energy is stored inside the hole. A light receiver 15 for measuring energy is provided, and the illumination light from the pattern detector 9 By receiving the dedicated pattern image projected by the wafer and detecting the relative position with the wafer moving table A self-monitoring light receiver 16 is provided to monitor the positional relationship of each element. Each of the above The elements are configured to be centrally controlled by a control device (not shown) including a CPU. There is.

[0017] Next, the operation of the device will be explained. First, load the wafer as an initialization operation. Before starting the process, exposure energy measurement and self-monitoring measurements are performed using each of the above methods to ensure that the product is in good condition. After confirming that everything is good, we move on to the exposure operation. In other words, the wafer is loaded onto the moving table. The wafer surface is aligned with the image plane (levelling). (so that the detected value matches the target value) and then is driven in X and Y to a predetermined position. The fine alignment mark position of the wafer is driven by θz so that it matches the target, and the wafer is X and Y directions that remain due to errors between the wafer outline and pattern position at the time of full loading The exposure target position is corrected by adding the error, and the step movement to the target position and exposure are as follows. are performed sequentially. First, move to the vicinity of the laser length measurement values X and Y, which are the first target positions. Step movement, and then perform the following precise positioning operations sequentially or in parallel.

[0018] 1. The unevenness of the wafer surface should be brought closest to the image plane (leveling within the shot area of the wafer). leveling and focus drive (θx, so that the detection value approaches the target value), θy, dZ).

[0019] 2. θx, θy measured by laser as a result of adding leveling and pitching Abbe errors eθx, eθy (here, e is the wafer surface and the X, Y optical path as shown in the figure). Indicates the interval between ) is fed back to change the target values X and Y, and the dX, dY mechanism is Drive and push.

[0020] X'=X±eθy Y'=Y±eθx...(Math. 2) (If e=5mm, θy=0.000005rad, eθy is 0.03 microns. (about a meter) 3. Set the laser length measurement value (dθz)x or (dθz)y of yawing to zero. The dθz mechanism is driven so that the (Here, for example, yawing when moving in the X direction is (dθz)x is used. If the mirror that is the coordinate reference is not straight, the difference d= (dθz)x−(dθz)y reflects the error, so when initializing , Y movement to register each other's mirror errors and add them to the target position in advance to determine the coordinates. It is also possible to correct the curvature of. ) After the above operations are completed and the wafer is precisely positioned, the lighting system shutter is opened. The circuit pattern image is exposed to the resist on the wafer surface, and then the above X and Y steps are performed. After repeating movement, precise positioning, and exposure, the wafer is unloaded after the specified area has been exposed. then move on to exposure of the next wafer.

[0021] Here, as an effect peculiar to the above embodiment, the wafer is A means for Z-driving the laser length measuring mirror is constructed on the mounting surface of the laser length measuring mirror, and after driving the Because it is attached and fixed, it is possible to make the mobile platform smaller and more rigid, resulting in lower vibration amplitude and One example is that the decay time can be reduced.

[0022] Next, FIG. 5 shows an electron beam lithography apparatus as another embodiment of the present invention. In the figure, An electron optical system 21 consisting of an electron gun and an electron lens is used in a vacuum exposure chamber 22. The introduced electron beam 23 is transferred from the load chamber 24 onto the wafer moving table 7. The wafer 8 inserted therein is exposed to light. On the other hand, on the wafer moving table 7 Mirrors 10a and 10b are arranged orthogonally to each other and fix the lower end of the electron optical system 21. interferometers 12a and 12b fixed to the top plate 25 of the exposure chamber 22, A laser length measuring meter is constructed between the The position of the wafer 8 is measured and controlled by the laser beam 28 incident on the wafer 8. There is. Note that other configurations and operations related to the electron beam lithography system are known technologies, so detailed explanations are not provided. Omit the description.

[0023]

[Effect of the idea]

According to the present invention, the interferometer for laser length measurement is placed on the substrate side of the lens (the image side) that controls the image position. side), it is possible to avoid errors caused by asynchronous vibrations of other structures. Also By correcting the position based on the pitching measurement value, the mirror is placed under the lens. Since the moving platform can be made smaller, the moving mass, inertial force, and vibration amplitude can be reduced. Ma In addition, a receiver for exposure energy measurement and a receiver for self-monitoring are placed inside the wafer chuck. By doing so, the movable table can be downsized, and the same effect as described above can be obtained. Also small Because the distance between the mirror and the wafer becomes smaller due to temperature change, expansion due to temperature changes, Errors due to shrinkage are also reduced. All of the above effects realize high-speed, high-precision exposure equipment. This contributes to

[Brief explanation of drawings]

FIG. 1 is a front view of a reduction projection exposure apparatus that is an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II' in FIG. 1;

FIG. 3 is a sectional view taken along line JJ' in FIG. 2;

FIG. 4 is a sectional view taken along line K-K' in FIG. 2;

FIG. 5 is a front view of an electron beam lithography apparatus according to another embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1... Reduction lens, 2... Base, 3... Column, 4... Reticle moving table, 6... Reticle, 7... Wafer moving table, 8... Wafer, 9... Pattern detector, 10a, 10b... Mirror, 1
1a, 11b... Interferometer holding plate, 12a, 12b... Interferometer, 13a, 13b... Linear guide, 14... Wafer chuck, 15... Light receiver for measuring exposure energy, 16... Light receiver for self-monitoring, 21... Electron optical system , 22... Exposure chamber, 23... Electron beam, 25... Top plate, 28... Laser light.

Claims (4)

[Scope of utility model registration request] 1. In an exposure apparatus that forms a pattern on a substrate using light or a charged particle beam, an interferometer for measuring the position of a substrate moving stage with a laser is located on the substrate side of a lens that modifies the light, etc. An exposure device characterized in that it is provided on the (image side). 2. The exposure apparatus according to claim 1, further comprising means for measuring pitching of the movable table and means for correcting the position of the substrate within the movable plane based on the measured value. 3. The exposure apparatus according to claim 1, wherein a light receiver for measuring exposure energy of the substrate is provided within a holding area of the substrate. 4. Holding a light receiver on the substrate for self-monitoring the device by receiving the original image projected by the illumination light of the pattern position detector instead of the substrate and detecting the relative position with the moving table. 2. The exposure apparatus according to claim 1, wherein the exposure apparatus is provided within a region.