JP4579367B2 - Scanning exposure apparatus and scanning exposure method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates EXPOSURE APPARATUS 及 beauty EXPOSURE METHOD step-and-scan method sequentially exposing each shot area of the base plate.
[0002]
[Prior art]
Conventionally, in a photolithography process for manufacturing a semiconductor element, a liquid crystal display element, an image pickup element (CCD or the like), a thin film magnetic head or the like, a pattern formed on a reticle as a mask as an original is used as a photosensitive substrate. A batch exposure type exposure apparatus such as a stepper for exposing a wafer is used. Recently, there is a tendency for semiconductor device chips to become larger, and since a pattern having a larger area on the reticle needs to be exposed on the wafer, the reticle and wafer are scanned synchronously, thereby illuminating the projection optical system. A step-and-scan type exposure apparatus that can expose a wider area than the field (the exposure area of the pattern in a stationary state) is widely used.
[0003]
Now, in the batch exposure type scanning exposure apparatus, the operation of stepping the shot area to be exposed to the illumination field, the positioning operation of aligning the shot area and the reticle, and the operation of exposing the shot area are repeated. It is.
[0004]
On the other hand, in a scanning-type scanning exposure apparatus such as the step-and-scan method, the wafer stage, which is a substrate stage, is stepped from the previous shot area to the position where scanning exposure of the next shot area is started. Then, scanning of the reticle stage as the wafer stage and the original stage is started. Then, after accelerating each scanning exposure start position to a predetermined scanning speed, the relative position between the reticle stage and the wafer stage is set with high positioning accuracy.
[0005]
Further, exposure light exposure is started, and scanning exposure is performed by driving the reticle stage and the wafer stage at a predetermined scanning speed. After the scanning exposure is completed, step movement in the non-scanning axis direction is started toward the next shot, and at the same time, scanning is performed for a distance necessary to set the wafer stage before the scanning exposure starts, and then the speed is decelerated. When the scanning with respect to the scanning axis is completed, a series of operations of reversing the scanning direction and starting scanning exposure for the next shot is repeated.
[0006]
In this way, by moving in advance the moving distance required for settling and the distance required for acceleration required before the start of the exposure of the next shot, a predetermined scan can be smoothly performed after the step movement to the scanning start position of the next shot. You can accelerate to speed. Furthermore, the relative position between the reticle stage and the wafer stage can be set with high positioning accuracy.
[0007]
[Problems to be solved by the invention]
In the conventional scanning exposure type scanning exposure apparatus as described above, each time a single shot area on the wafer, which is a substrate, is exposed, exposure is performed by reversing the scanning direction. If the shot layouts are adjacent to each other, step-and-scan scanning exposure can be performed efficiently. However, in the case of a shot layout that includes a line feed for step movement to the next shot area, the distance required for settling + the distance required for acceleration + the exposure size of the shot area from a position distant from the scanning start position for the next shot area. It may happen that a scan has to be started. This depends on the shot layout. However, when such a case occurs, it takes a longer time to move to the next shot area than usual, and there is a problem that the throughput is lowered.
[0008]
The present invention has been made in view of such problems, to shorten the distance traveled step, and an object thereof is to provide a EXPOSURE METHOD AND EXPOSURE APPARATUS capable of improving the throughput.
[0009]
[ Means for Solving the Problems]
The scanning exposure apparatus according to the present invention for achieving the above object includes a master stage which moves the original plate pattern is formed and a substrate stage which moves the substrate to be exposed through the pattern of the original, the The original stage and the substrate are moved by a first distance while synchronously scanning the original stage and the substrate stage through the original stage and the substrate stage, and the substrate stage is accelerated in the scanning axis direction , and then the substrate stage is moved in the scanning axis direction. after moving at a constant speed by a second distance, the shot region of the substrate, an exposure apparatus for exposure light through the pattern of the original,
A line feed detecting means for detecting whether or not a line feed accompanies the step movement of the substrate stage ;
When it is detected by the line feed detecting means that the line movement is not accompanied by the step movement, after the exposure of the shot area is completed, the substrate stage is moved by the second distance in the scanning axis direction, and then in the scanning axis direction. When the substrate stage starts decelerating and it is detected by the line feed detecting means that a line feed is accompanied by a step movement, after the exposure of the shot area is completed, the substrate stage is moved by the second distance in the scanning axis direction. And stage control means for starting the deceleration of the substrate stage in the scanning axis direction without performing.
[0010]
Furthermore, the exposure method of the present invention uses an original stage for moving an original plate on which a pattern is formed, and a substrate stage for moving a substrate exposed through the pattern of the original plate. The substrate stage is moved at a constant speed in the scanning axis direction at a second distance after the substrate stage is moved in the scanning axis direction by a first distance while being synchronously scanned through the original stage and the substrate stage. In an exposure method in which the shot area of the substrate is sequentially exposed through the pattern of the original plate after being moved only by
Detecting whether or not a line feed accompanies the step movement of the substrate stage;
When it is detected that the line movement is not accompanied by the step movement, after the exposure of the shot area is completed, the substrate stage is moved in the scanning axis direction by the second distance, and then the substrate stage is decelerated in the scanning axis direction. When the step movement is detected to be accompanied by a line feed, the substrate stage is moved in the scanning axis direction without moving the second distance in the scanning axis direction after the exposure of the shot area is completed. It is characterized by starting deceleration of the stage.
[0011]
Furthermore, the device manufacturing method of the present invention includes a step of exposing a substrate using the exposure apparatus, and a step of developing the exposed substrate.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings. In the present embodiment, a reticle on a reticle and a wafer on a substrate are scanned synchronously with respect to the projection optical system, thereby sequentially transferring and exposing a pattern on the reticle to each shot area on the wafer. The present invention is applied when exposure is performed with a scanning projection scanning exposure apparatus.
[0015]
FIG. 1 is a diagram showing a schematic configuration of a projection exposure apparatus according to an embodiment of the present invention.
In FIG. 1, the illumination optical system SL includes a light source, a variable field stop that shapes the shape of the illumination light, a condenser lens, and the like. The illumination light IL emitted from the illumination optical system SL illuminates the illumination area on the slit on the reticle R with a uniform illuminance distribution. The pattern in the illumination area on the reticle R is inverted and reduced at a projection magnification α (for example, α = 1/4) via the projection optical system UL, and the image is projected and exposed to a slit-like illumination field on the wafer W. Is done. As the illumination light IL, for example, KrF excimer laser light, ArF excimer laser light, or an ultraviolet bright line (g line, i line, etc.) of an ultrahigh pressure mercury lamp is used.
[0016]
In the following description, the axis is parallel to the optical axis of the illumination light IL, the axis parallel to the paper surface in the plane perpendicular to the optical axis is the X axis, and the axis perpendicular to the paper surface is the Y axis.
The reticle R is placed on the reticle stage 6. The reticle stage 6 finely moves two-dimensionally in a plane perpendicular to the optical axis of the projection optical system UL to position the reticle R, and scans while synchronizing with the wafer stage 1. The reticle stage 6 has a stroke that allows the entire surface of the pattern area of the reticle R to cross at least the illumination area in the scanning axis direction.
[0017]
A bar mirror 7 that reflects the laser beam from the external laser interferometer 26 is fixed to the end of the reticle stage 6. The position of the reticle stage 6 is constantly monitored by a laser interferometer 26. Position information of the reticle stage 6 from the laser interferometer 26 is supplied to the control system 21. The control system 21 controls the position and speed of the reticle stage 6 via the reticle stage drive unit 24 based on the position information.
[0018]
On the other hand, the wafer W is placed on the suction plate on the wafer stage 1. The wafer stage 1 performs a step-and-scan operation that repeats the operation of scanning each shot area on the wafer W. Further, the movement in the heel direction and the movement in the tilt direction are also performed by the control system 21 controlling the wafer stage 1.
[0019]
A bar mirror 2 for reflecting the laser beam from the laser interferometer 25 is provided at the end of the wafer stage 1. The position of the wafer stage 1 is constantly monitored by a laser interferometer 25. Similar to the control of the reticle stage 6, the position and speed of the wafer stage 1 are controlled by the control system 21 via the wafer stage drive unit 23 based on the position information.
[0020]
At the time of scanning exposure, the reticle R is scanned in the + Y direction, for example, at a speed Vr.
In synchronization with this, the wafer W is scanned in the −Y direction at a speed Vw. The ratio (Vw / Vr) between the scanning speeds Vw and Vr exactly matches the projection magnification α from the reticle R to the wafer W of the projection optical system UL. As a result, the pattern on the reticle R is accurately transferred to each shot area of the wafer W.
[0021]
The scanning exposure apparatus according to the present embodiment is a line feed detection unit that detects whether or not a line feed is involved in step movement from the previous shot area on the wafer to the exposure start position of the next shot area in FIG. 1 described above. A detection unit 22 is provided. In addition, stage control means (not shown) for controlling the operation of the wafer stage 1 in accordance with the position of the next shot area with line feed and moving the wafer W to the exposure position is also provided. The line feed detection unit 22 obtains the exposure center coordinates of the next shot area and the exposure size of the shot area from the control system 21, and compares them with the exposure center coordinates of the previous shot area to determine whether or not the next shot area is accompanied by a line feed. Can be detected.
[0022]
If the next shot area is accompanied by a line feed by the stage control means, the wafer stage 1 starts decelerating immediately after the exposure of the previous shot area. Then, in consideration of the scanning distance required for settling, the wafer stage 1 can be immediately moved to a position where scanning exposure to the next shot area is started.
[0023]
In other words, the stage control means performs step movement in the non-scanning axis (X-axis) direction to the next shot area simultaneously with the start of deceleration of the wafer stage 1. Thereafter, the scanning exposure direction is reversed after scanning of the previous shot area in the scanning axis (Y-axis) direction is completed, and scanning exposure of the next shot area is started. Therefore, it is possible to implement the first scanning exposure method of this embodiment.
[0024]
In FIG. 1, 3 is a wafer stage surface plate, 4 is a multi-point AF sensor, 5 is a lens barrel surface plate, 8 is a reticle stage guide, 9 is an outer cylinder, and 22 is a line feed detection unit to be described later. Is shown.
[0025]
Next, scanning exposure for transfer exposure using the above scanning exposure apparatus will be described.
First, transfer exposure refers to stepping, stopping operation, positioning operation, scanning required for settling before exposure start, deceleration or acceleration scanning, light source emission or stopping operation, and scanning exposure. This represents an operation or the like. In the above-described transfer exposure, scanning required for settling before the start of exposure is an element that affects the synchronization accuracy between the wafer stage 1 and the reticle stage 6 at the time of exposure and actual exposure. The scanning required for settling is scanning necessary for the vibration generated when the wafer stage 1 is accelerated so as to reach a predetermined scanning speed at the exposure start position to be settled in a state in which exposure is not hindered. The distance required for settling is determined by the settling time determined by the performance of the wafer stage 1 and the scanning speed.
[0026]
FIG. 2 is a diagram showing the relationship between the speed of the wafer stage 1 (FIG. 1) in the scanning axis (Y-axis) direction and time when scanning exposure is performed. Usually, when performing scanning exposure, it accelerates until it reaches a predetermined exposure speed (section L1). After that, it moves at the same speed by the distance required for settling (section L2), and when the wafer stage 1 is set, exposure is started (section L3). After completion of exposure, step movement to the next shot area in the non-scanning axis (X-axis) direction is performed, and at the same time, moving at a constant speed in the scanning axis direction by the distance required for settling before starting exposure. After (section L4), deceleration is started (section L5). When the movement in the scanning axis direction is completed, the scanning exposure direction is reversed and scanning to the next shot area is started.
[0027]
By repeating this operation, exposure is performed in the layout order of the shot areas arranged on the wafer W (FIG. 1). When exposing adjacent shot areas, the settling distance required before the start of exposure of the next shot area can be advanced in advance by moving at a constant speed by the distance required for settling after the end of exposure. Furthermore, exposure can be performed without stopping scanning during movement between shot areas.
[0028]
FIG. 3 is a diagram illustrating an example of a shot layout for exposing a wafer and a scanning exposure order. For example, as shown in FIG. 3, when the shot areas S1 to S5 are exposed, the exposure is sequentially performed while drawing the exposure trajectory from Path1 to Path4. The scanning exposure of the present invention is effective, for example, in the case of a movement pattern from the shot area S4 to the scanning exposure start position of S5 in FIG. 3 (SB portion).
[0029]
Next, scanning exposure will be described with reference to FIGS. FIG. 4 is an enlarged view of the SB portion of FIG. 3, and is a diagram showing a step movement trajectory of the conventional wafer stage when a line feed is accompanied by movement to the next shot area on the wafer. First, in the conventional scanning exposure method, after the exposure of the shot area S4 is completed, the deceleration is started and stopped after moving at a constant speed by the distance DL2 required for settling. The distance traveled before decelerating and stopping is DL1. After the exposure is completed, the movement in the non-scanning axis (X-axis) direction while scanning in the scanning axis (Y-axis) direction is the step movement to the non-scanning axis to S5 which is the next shot area after the exposure is completed. This is because it has started. Normally, even in the case of a shot layout with a line feed in the movement to the next shot area as in the shot areas S4 to S5, or in the case of adjacent shot layouts as in the shot areas S2 to S3 (FIG. 3), after the exposure is completed After moving at an equal speed by the distance required for settling, the speed is reduced and scanning exposure of the next shot area is started.
[0030]
If adjacent shot layouts such as shot areas S2 to S3 (FIG. 3), after the exposure of shot area S2, the next shot area is moved by a distance DL1 required for deceleration without moving the distance required for settling. Consider the case of starting scanning exposure. In this case, since it is not possible to secure the distance required for the setting of the shot area S3 before the start of exposure, the scanning must be started after the step is moved by the distance required for the setting to the opposite side to the scanning axis direction. Therefore, in this method, the exposure efficiency is deteriorated.
[0031]
On the other hand, in a shot layout that does not involve adjacent line feeds, the next shot area is scanned and exposed smoothly by advance in advance by a distance required for settling.
[0032]
FIG. 5 is an enlarged view of the SB portion of FIG. 3 as in FIG. 4, and shows the trajectory of the step movement of the wafer stage in the present embodiment when the movement to the next shot area on the wafer is accompanied by a line feed. FIG. As shown in FIG. 5, in the scanning exposure of the present embodiment, in the case of a shot layout with line breaks such as shot areas S4 to S5 (FIG. 3), the distance DL3 required for deceleration after the exposure of the shot area S4 is set. After scanning, scanning exposure of the shot area S5 is started. For this reason, the distance DL4 required for settling before the exposure of the shot area S5 is started can be sufficiently taken. For this reason, it is not necessary to scan the distance required for settling after the exposure of the shot area S4.
[0033]
As described above, in the present embodiment, for example, when moving from a shot area S4 to a shot area with a line feed as shown in S5 (FIG. 3), a line feed is detected by the line feed detection process, and the previous shot is performed by the stage control process. The distance required for settling after the exposure of the area is not scanned. This provides scanning exposure for the purpose of shortening the moving distance to the next shot area and improving the throughput.
[0034]
[Embodiment of Device Production Method]
Next, an embodiment of a device production method using the above-described scanning exposure apparatus or scanning exposure method will be described.
FIG. 6 shows a manufacturing flow of a microdevice (a semiconductor chip such as an IC or LSI, a liquid crystal panel, a CCD, a thin film magnetic head, a micromachine, etc.). In step 1 (circuit design), a device pattern is designed. In step 2 (mask production), a mask on which the designed pattern is formed is produced. On the other hand, in step 3 (wafer manufacture), a wafer is manufactured using a material such as silicon or glass. Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the prepared mask and wafer. The next step 5 (assembly) is called a post-process, and is a process for forming a semiconductor chip using the wafer produced in step 4, and is a process such as an assembly process (dicing, bonding), a packaging process (chip encapsulation), or the like. including. In step 6 (inspection), the semiconductor device manufactured in step 5 undergoes inspections such as an operation confirmation test and a durability test. Through these steps, the semiconductor device is completed and shipped (step 7).
[0035]
FIG. 7 shows a detailed flow of the wafer process. In step 11 (oxidation), the wafer surface is oxidized. In step 12 (CVD), an insulating film is formed on the wafer surface. In step 13 (electrode formation), an electrode is formed on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted into the wafer. In step 15 (resist process), a photosensitive agent is applied to the wafer. In step 16 (exposure), the circuit pattern of the mask is printed onto the wafer by exposure using the above-described scanning exposure apparatus and scanning exposure method. In step 17 (development), the exposed wafer is developed.
In step 18 (etching), portions other than the developed resist image are removed. In step 19 (resist stripping), unnecessary resist after etching is removed. By repeatedly performing these steps, multiple circuit patterns are formed on the wafer.
By using the production method of the present embodiment, a highly integrated device that has been difficult to manufacture can be manufactured at low cost.
[0036]
【The invention's effect】
According to the present invention, to shorten the distance to the step movement, it is possible to provide an exposure method and exposure light device can be improved throughput.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of a projection exposure apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram showing the relationship between the speed of a wafer stage in the scanning axis direction and time when scanning exposure is performed.
FIG. 3 is a diagram showing an example of a shot layout for exposing a wafer and a scanning exposure sequence.
4 is an enlarged view of the SB portion of FIG. 3, and is a diagram showing a trajectory of a step movement of a conventional wafer stage when a line feed is accompanied by movement to the next shot area on the wafer.
FIG. 5 is an enlarged view of the SB portion of FIG. 3, and is a diagram showing a trajectory of step movement of the wafer stage in the present embodiment when line feed is accompanied by movement to the next shot area on the wafer.
FIG. 6 is a diagram showing a flow of manufacturing a microdevice.
7 is a flowchart showing a detailed flow of the wafer process in FIG. 6. FIG.
[Explanation of symbols]
SL: illumination optical system, IL: illumination light, R: reticle, W: wafer (photosensitive substrate), UL: projection optical system, 1: wafer stage, 2: bar mirror, 3: wafer stage surface plate, 4: multipoint AF Sensor: 5: Lens platen, 6: Reticle stage, 7: Bar mirror, 8: Reticle stage guide, 9: Outer cylinder, 21: Control system, 22: Line feed detection unit, 23: Wafer stage drive unit, 24: Reticle Stage drive unit, 25, 26: Laser interferometer, L1: Section that accelerates until a predetermined exposure speed is reached, L2: Section that moves at constant speed by the distance required for settling, L3: Section that starts exposure, L4: Settling A section moving at a constant speed in the scanning axis direction by the required distance, L5: a section decelerating in the scanning axis direction, S1, S2, S3, S4, S5: Shot area, Path1, Path2, Path3, Pa h4: trajectory to be exposed, DL1: distance required for deceleration without moving the distance required for settling, DL2: distance required for settling (distance moving at constant speed), DL3: distance required for deceleration, DL4: distance required for settling, SB: Reference to FIG. 4 and FIG.

Claims (5)

An original stage for moving an original on which a pattern is formed; and a substrate stage for moving a substrate exposed through the pattern of the original; and the original and the substrate via the original stage and the substrate stage. The substrate stage is moved by a first distance while being synchronously scanned and accelerating the substrate stage in the scanning axis direction, and then the substrate stage is moved by a second distance at a constant speed in the scanning axis direction. In an exposure apparatus that exposes a shot area through the pattern of the original plate,
A line feed detecting means for detecting whether or not a line feed accompanies the step movement of the substrate stage;
When it is detected by the line feed detecting means that the line movement is not accompanied by the step movement, after the exposure of the shot area is completed, the substrate stage is moved by the second distance in the scanning axis direction, and then in the scanning axis direction. When the substrate stage starts decelerating and the line feed detecting means detects that the step movement involves a line feed, after the exposure of the shot area is completed, the substrate stage is moved by the second distance in the scanning axis direction. An exposure apparatus comprising: stage control means for starting the deceleration of the substrate stage in the scanning axis direction without performing it. The line feed detecting means detects whether or not the line movement is accompanied by a step movement by comparing the center coordinates of the shot area before and after the step movement, and the stage control means detects the substrate stage simultaneously with the start of the deceleration. The exposure apparatus according to claim 1, wherein the exposure apparatus is moved stepwise in a non-scanning axis direction, and the scanning direction of the substrate stage in the scanning axis direction is reversed after the deceleration is completed. Using an original stage for moving an original on which a pattern is formed and a substrate stage for moving a substrate exposed through the pattern of the original, the original and the substrate are transferred via the original stage and the substrate stage. The substrate stage is moved by a first distance while being synchronously scanned and accelerating the substrate stage in the scanning axis direction, and then the substrate stage is moved by a second distance at a constant speed in the scanning axis direction. In the exposure method of sequentially exposing the shot area through the pattern of the original plate,
Detecting whether or not a line feed accompanies the step movement of the substrate stage;
When it is detected that the line movement is not accompanied by the step movement, after the exposure of the shot area is completed, the substrate stage is moved in the scanning axis direction by the second distance, and then the substrate stage is decelerated in the scanning axis direction. When the step movement is detected to be accompanied by a line feed, the substrate stage is moved in the scanning axis direction without moving the second distance in the scanning axis direction after the exposure of the shot area is completed. An exposure method characterized by starting deceleration of a stage. In the detection, the center coordinates of the shot area before and after the step movement are compared to detect whether or not the line movement is accompanied by the step movement. Simultaneously with the start of the deceleration, the substrate stage is moved in the non-scanning axis direction. 4. The exposure method according to claim 3, wherein the scanning direction of the substrate stage in the scanning axis direction is reversed after the step movement is performed and the deceleration is completed. Exposing the substrate using the exposure apparatus according to claim 1;
And developing the exposed substrate. A device manufacturing method comprising:

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