JP2583120B2 - Exposure equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus used for manufacturing a semiconductor device, and more particularly, to a structure for supporting a stage on which a substrate is mounted and a projection lens mounting portion. The present invention relates to a separately provided exposure apparatus.

[Conventional technology]

Conventionally, as an exposure apparatus used for semiconductor element manufacturing,
An apparatus called a so-called stepper is known. This stepper reduces a pattern image formed on an original plate, for example, a reticle, with a projection lens while step-moving a substrate, for example, a semiconductor wafer under a projection lens, and sequentially exposes a plurality of locations on one wafer. Things.

Steppers are regarded as the mainstream of these aligners (exposure apparatuses) in terms of resolution and overlay accuracy.

FIG. 5 shows an example of mounting a structure and an XY stage in a conventional aligner.

1, reference numeral 1 denotes an illuminating unit for illuminating a reticle pattern, 2 denotes a reticle having a pattern to be transferred, 3 denotes a projection lens for projecting the reticle pattern onto a wafer, and 4 denotes a lens barrel support plate that supports the projection lens 3. , 16a is a light emitting section of a focus detecting section for measuring the distance between the focus of the projection lens 3 and the wafer, 16b is a light receiving section of the focus detecting section,
6 is an interferometer for controlling the position of the stage, 9 is the top stage, 10 is the X stage, 11 is the Y stage, and 17 is the X stage.
Reference numeral 18 denotes a DC motor for driving the stage, 18 denotes a DC motor for driving the Y stage, 61 denotes a supporting surface plate on which the whole of the projection lens 3 and the XY stages 10 and 11 are mounted, 62 denotes a frame, and 63 denotes a servo mount.

Semiconductor wafers processed by the aligner having such a configuration tend to use large-diameter and large-sized semiconductor wafers in order to increase the area and cost of semiconductor elements. Currently, the wafer size is φ6 '(φ150mm)
Is the mainstream, but around 1989, φ8 '(φ200mm) is expected to become the mainstream.

On the other hand, semiconductor devices (especially DRAMs) have been highly integrated from the 4M (mega) bit era to the 16M (mega) bit era, and the line width has also become finer. Therefore, there is a strong demand for higher-precision alignment, a higher-precision XY stage, higher throughput, and the like.

[Problems to be solved by the invention]

However, according to the structure of the conventional stepper in which the conventional exposure apparatus for φ3 ′ to φ6 ′ is simply increased in size to φ8 ′ and the XY stage is directly fixed to the support surface plate 61 in FIG. Occurs.

a) In order to increase the stroke of the XY stages 9, 10, and 11, it is necessary to increase the guide stiffness in order to guarantee the same or higher accuracy as the stage before the stroke. Further, in order to satisfy the requirement of the high-precision stage described above, the stage weight has to be further increased more than simply the weight increase due to the stroke up. Therefore, an increase in the excitation force due to the acceleration of the stage movement and a decrease in the relative rigidity of the lens-supporting structure due to an increase in the weight of the projection lens cause a vibration problem, which causes the following problems.

The reinforcement of the structure increases the size and cost of the device.

Since the exposure and alignment operations cannot be performed until the structural system is shaken, productivity is reduced.

b) On the other hand, an increase in the weight of the stage statically increases the moving load, causing a problem that the attitude of the apparatus changes depending on the position of the XY stage. Therefore, the following problems occur.

The alignment accuracy deteriorates.

In order to prevent a decrease in productivity, it is necessary to instantaneously set the apparatus attitude to a constant attitude. Therefore, it is necessary to improve the servo mounting capability in the conventional configuration shown in FIG. 5, which leads to an increase in cost.

In order to make the entire apparatus having the increased weight have a fixed attitude, it is necessary to improve the capability of the servo mount, and it is necessary to increase the size of the servo mount. Therefore, the height of the whole apparatus increases.

c) According to the conventional XY stage support structure as shown in FIG. 5, when a movable part other than the XY stage operates,
There is a problem of exciting the stage. For this reason, problems such as deterioration of alignment accuracy and deterioration of printing accuracy occur.

The present invention has been made in view of such circumstances, and its purpose is to prevent vibration of each part of the device with a compact configuration,
It is an object of the present invention to provide an inexpensive, high-precision, high-throughput exposure apparatus that can always accurately and quickly align the position of a substrate onto which a pattern of an original is projected and exposed with respect to a projection lens.

[Means for Solving the Problems] To achieve the above object, an exposure apparatus according to the present invention includes a projection lens for projecting and exposing a pattern formed on an original plate (reticle) onto a substrate (wafer); A substrate stage (YX stage) for moving the substrate in the X and Y directions with respect to the projection lens so as to sequentially project and expose the pattern of the original plate on a plurality of upper positions; A lens barrel support (barrel support) that supports the substrate stage with respect to the floor while being separated from the lens barrel support; A focus detector for measuring a value in a Z direction from a focal position of the projection lens to an upper surface of the substrate moved by the substrate stage from a lens barrel support side; X and Y of the substrate stage relative to the projection lens from side
A laser interferometer for measuring a value corresponding to a position in a direction, and each of the lens barrel support and the stage base in a separated state are installed, and by this installation, the lens barrel support on the floor is provided. It is characterized by having a positioning surface plate for positioning a relative positional relationship between a body and the stage surface plate.

In this case, an air mount is interposed between the lens barrel support and the positioning surface plate, or the light beam is transmitted to the lens mirror to determine the origin of length measurement using the laser interferometer. An air mount capable of irradiating light from the cylinder support side toward the substrate stage side, or between the lens barrel support body and the stage surface plate via the positioning surface plate and capable of controlling the internal air pressure. Is preferably interposed.

And, when an air mount capable of controlling the internal air pressure is interposed between the lens barrel support and the stage base via the positioning base, the lens barrel support and the substrate stage The air pressure in the air mount is controlled so as to keep the relative posture constant, or the laser interferometer measures a value corresponding to the position and posture of the substrate stage with respect to the projection lens in the X and Y directions. Or the data for controlling the air pressure in the air mount when the next substrate is exposed by the apparatus, and the position of the substrate stage when the previous substrate is exposed by the apparatus. Light beam from the lens barrel support side to correct based on the orientation data and to further determine the origin of length measurement using the laser interferometer. More preferably or to be irradiated toward the substrate stage side.

According to the present invention, since the lens barrel support and the stage base are separated from each other and supported on the floor, the pattern formed on the original plate is transferred onto the substrate via the projection lens. When the substrate stage moves the substrate with respect to the projection lens in order to project and expose the plurality of locations in sequence, the vibration caused by the movement of the substrate stage on the stage base supporting the substrate stage causes the lens barrel to support the projection lens. The effect on the support side can be minimized. Also,
By measuring the focus and XY position from the lens barrel support side, it is possible to accurately and quickly measure the focus and XY position even when the substrate stage repeatedly moves and vibrates on the stage-side surface plate. Can be.

Further, by having a positioning platen for positioning the relative positional relationship between the lens barrel support and the stage base on the floor, the lens barrel support and the stage base are separated and supported as described above. Despite this, the exposure apparatus can be easily installed, and the relative positional relationship between the separately mounted lens barrel support and the stage base shifts due to external influences. It is also possible to prevent the operation from being disabled.

When an air mount that can control the internal air pressure is interposed between the lens barrel support and the stage base via the positioning base, vibration on the stage base can be prevented, and It is also possible to maintain the posture of the substrate stage on the stage base in a predetermined state. In addition, the capacity of the air mount can be made smaller than when the entire device is supported by the air mount, and the size of the device can be reduced.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1 to 4 show an exposure apparatus according to one embodiment of the present invention. FIG. 1 is a side view (partially shown) of an embodiment of the apparatus that best illustrates the features of the present invention.

In FIG. 1, reference numeral 1 denotes an illumination unit for illuminating a reticle, 2 denotes a reticle having a pattern to be transferred, 3 denotes a projection lens for projecting a pattern formed on the reticle onto a wafer, and 4 denotes a lens barrel that supports the projection lens. The support 5 is an air mount 6 supporting the lens barrel support 4 is an air mount 5
This is a positioning surface plate for positioning the relative positional relationship between the stage mount 14 and these mounts. 7,8
Reference numeral 7 denotes an XY direction and yawing sensor for determining the origin of the XY stage. Reference numeral 7 denotes a laser for finding the origin fixed to the lens barrel support 4, and reference numeral 8 denotes a two-dimensional sensor arranged on the top stage 9. One or more sets of the laser 7 for locating the origin and the two-dimensional sensor 8 are installed.

9 is mounted on the X stage 10 in the Z direction, θ direction, α
And a top stage having a function of moving and rotating in the β direction. 10 is an X stage movable in the X direction,
11 is a Y stage movable in the Y direction, 12 is an X stage 10
And stage base supporting Y stage 1, 13 is XY
An XY stage base 14 that supports the stages 9 to 12, and 14 is an XY stage mount that prevents vibration of the stage base 13 caused by movement of the stage and insulates vibration from the floor. This mount 14 is generally called an active mount.

Reference numeral 15 denotes a laser interferometer for measuring the relative position between the projection lens 3 and the XY stage and measuring the attitude of the XY stage. Reference numeral 16a denotes a focus detection unit for measuring the distance between the focal position of the projection lens 3 and the upper surface of the wafer. And 16b is a light receiving unit of the focus detecting unit. These light emitting sections 16
a and the light receiving section 16b are fixed to the projection lens 3, respectively. Reference numeral 17 denotes a driving DC servo motor for moving the X stage 10 in the X direction, and reference numeral 18 denotes a driving CD servo motor for moving the X stage 10 and the Y stage 11 in the Y direction.

FIG. 2 is a perspective view showing the arrangement of the measurement system for the XY stage of the exposure apparatus of the present embodiment.
FIG. 3 is a diagram showing in detail a portion of a laser interferometer 15 and the like in the vicinity of FIG.

In the same figure, 21 is a laser head as a light source, 22 is a reflection mirror mounted on the top (θ-Z and tilt) stage 9 in FIG. 1, 23 is a laser interferometer, and 24 is a converter for converting an interference draft into an electric signal. 1, a projection lens 25 is the same as the projection lens 3 of FIG. 1, and 26 is a reflection mirror fixed to the projection lens 3.

FIG. 3 is a detailed view of a so-called active mount (number 14 in FIG. 1) for the XY stage of the exposure apparatus of the present embodiment.

In the figure, 31 is a voice coil motor for applying a force to the XY stage base 13 in the XY direction, and 32 is an air having high rigidity in the Z direction (vertical direction on the paper) and low rigidity in the XY direction. This is a laminated rubber mount fixed on the mount. 33 is an air mount fixed to the fixed body with high rigidity in the XY direction and low in the Z direction, 36 is a servo valve that controls the internal pressure of the air mount 33, 37 is a fixed body, and 38 is a platen 13 for the XY stage. This is a non-contact type displacement meter that detects inclination.

FIG. 4 is a block diagram of a stage and an XY stage mount section control system of the exposure apparatus of the present embodiment.

In the figure, reference numeral 41 stores the step amount and moving speed of the XY stage and the air pressure of the air mount corresponding to the inclination of the stage base after moving the stage, transmits an operation command to each driver, and furthermore, the required step amount and It is a control computer that gives feedback to the position and speed of the stage at the moment based on the moving speed. 42 is 1st
An origin position locating unit corresponding to the origin position locating laser 7 and the two-dimensional sensor 8 in the figure, 43 is shot arrangement information inputted from the outside, and 44 is a laser for XY position measurement and yawing measurement shown in FIG. It is a measurement system. Reference numeral 45 denotes an X for driving a DC servo motor 46 (numbers 17 and 18 in FIG. 1) in the XY direction.
Y servo driver, 47 is the top stage. Reference numeral 48 denotes an active damper controller, and a servo valve 49 (third
It comprises an air mount pressure controller for controlling the number 36 in FIG. 3 and a voice coil motor driver for driving the voice coil motor 50 (number 31 in FIG. 3). 51 is an accelerometer mounted on the stage base 13, and 52 is an XY stage base
Non-contact type displacement gauge that detects inclination of 13 (numbering in Fig. 3)
38) and 53 are focus detection units (numbers 16a and 16b in FIG. 1).

Next, the operation of the exposure apparatus of this embodiment will be described with reference to FIGS.

First, the origin for measuring the relative position and orientation of the main body and the XY stage is determined by using the laser light from the laser head 21 fixed to the lens barrel support 4 and the top stage 9.
It is determined by the two-dimensional sensor 8 arranged above. Thereafter, the original point is not rewritten until a body reset command is input to the control computer.

Next, the shot arrangement (layout) and the amount of movement in the X and Y directions are input to the control computer 41 in advance for each semiconductor wafer to be exposed. The control computer 41 obtains the inclination of the stage base 13 after moving the stage from these data and the moving load of the stage, and calculates and sets the pressure and speed servo and positioning servo switching position of each mount to correct the inclination. .

Then, a drive command of the DC servo motor 46 is issued to the servo driver 45 of the XY stage, and the servo valve 49 is sent to the pressure controller in the active damper controller 48.
Is issued. Next, after the XY stage is switched from the speed servo to the positioning servo, the voice coil motor driver in the active damper controller 48 receives the voice coil motor 50 from the acceleration data from the accelerometer 51 mounted on the stage base 13. Is issued. As a result, the vibration of the stage base 13 is damped, and at the same time, a servo valve drive command is issued to the pressure controller in the active damper controller 48.

Next, θ (yawing), α (rolling) and α (rolling), which are differences between data from the laser measurement system 44 indicating the position and orientation of the focus detection unit 53 and the stage and a predetermined layout stored in the control computer 41, Calculate β (pitching). Then, a command is issued to the XY stage servo driver 45 for the XY component, and to the top stage drive driver for the θ, α, and β components, and the DC servo motor 46 and the top stage 47 are matched with a predetermined layout (position / posture). Drive to do.

Here, regarding the α component and the β component, the data is fed back to the control computer 41, and the table of the relationship between the position and the inclination of the stage is rewritten.

Exposure is performed after the positioning of the XY stage is completed as described above.

〔The invention's effect〕

As described above, according to the present invention, when the substrate stage moves the substrate with respect to the projection lens to project and expose a pattern formed on the original plate in order of a plurality of locations on the substrate via the projection lens, It is possible to minimize the influence of the vibration generated by the movement of the substrate stage on the stage base supporting the substrate stage on the lens barrel support supporting the projection lens. Further, even when the substrate stage repeatedly moves and the stage-side platen vibrates, the focus and the XY position can be measured accurately and quickly. Furthermore, despite the fact that the lens barrel support and the stage base are separated and supported, the exposure position can be easily set, and the lens that is separately installed due to external influences. It is possible to prevent the relative positional relationship between the lens barrel support and the stage base from being shifted, thereby preventing the exposure operation from being disabled. When an air mount capable of controlling the internal air pressure is interposed between the lens barrel support and the stage base via the positioning base, vibration on the stage base can be prevented and the stage base can be prevented. It is also possible to maintain the posture of the substrate stage on the side in a predetermined state. In addition, the capacity of the air mount for that purpose can be made smaller than when the entire apparatus is supported by the air mount, and the apparatus can be made more compact.

Therefore, it is possible to provide an inexpensive exposure apparatus with high accuracy and high throughput.

[Brief description of the drawings]

FIG. 1 is a front view of an exposure apparatus (stepper) according to one embodiment of the present invention, FIG. 2 is a perspective view showing an arrangement of a measurement system of the apparatus of the above embodiment, and FIG. FIG. 4 is a cross-sectional view showing a detailed structure of a stage mount of the apparatus of FIG. 1, FIG. 4 is a block diagram of a stage and mount control system of the apparatus of the above embodiment, and FIG. 5 is a front view of a conventional exposure apparatus. . 1: Illumination unit, 3: Projection lens, 4: Barrel support, 5: Air mount for main unit, 6: Positioning table, 9: Top stage, 10: X stage, 11: Y stage, 14: For XY stage Mount (active damper), 41: Control computer, 44: Laser measurement system for XY position measurement and yaw measurement, 45: XY servo driver, 48: Active damper controller, 51: Accelerometer, 52: Non-contact displacement meter.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location H01L 21/30 526B 516Z

Claims (8)

(57) [Claims] A projection lens for projecting and exposing a pattern formed on an original onto a substrate; and a projection lens for projecting and exposing the pattern of the original on a plurality of locations on the substrate sequentially. A substrate stage that moves in the X and Y directions, a lens barrel support that supports the barrel of the projection lens with respect to the floor, and the substrate stage that is separated from the lens barrel support. Focus detection for measuring a value corresponding to a distance in the Z direction between a stage base supported on the floor and a focal position of the projection lens from the lens barrel support side and an upper surface of the substrate moved by the substrate stage. And X of the substrate stage with respect to the projection lens from the lens barrel support side.
And a laser interferometer for measuring a value corresponding to a position in the Y direction, and the lens barrel support and the stage base in a separated state are respectively installed. With this installation, the lens mirror on the floor is provided. An exposure apparatus comprising: a positioning surface plate for positioning a relative positional relationship between a cylinder support and the stage surface plate. 2. An exposure apparatus according to claim 1, wherein an air mount is interposed between said lens barrel support and said positioning platen. 3. The method according to claim 1, further comprising irradiating a light beam from said lens barrel support side to said substrate stage side to determine an origin of length measurement using said laser interferometer. 3. The exposure apparatus according to claim 1. 4. An air mount capable of controlling an internal air pressure is interposed between said lens barrel support and said stage base via said positioning base. 2. The exposure apparatus according to 1. 5. The exposure apparatus according to claim 4, wherein an air pressure in the air mount is controlled so that a relative posture between the lens barrel support and the substrate stage is kept constant. 6. The laser interferometer according to claim 5, wherein the laser interferometer measures values corresponding to the position and orientation of the substrate stage with respect to the projection lens in the X and Y directions.
3. The exposure apparatus according to claim 1. 7. The data for controlling the air pressure in the air mount when the next substrate is exposed by the apparatus, and the position and posture of the substrate stage when the previous substrate is exposed by the apparatus. The exposure apparatus according to claim 6, wherein the correction is performed based on the data. 8. The apparatus according to claim 6, wherein a light beam is emitted from said lens barrel support side to said substrate stage side to determine an origin of length measurement using said laser interferometer. 3. The exposure apparatus according to claim 1.