JPH0628224B2 - Exposure method and apparatus - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention reduces the disadvantages particularly suitable for semiconductor manufacturing, the exposure method for a large-diameter substrate, and the implementation of the method when used also for a small-diameter substrate. The present invention relates to an exposure apparatus.

BACKGROUND OF THE INVENTION An apparatus called a stepper is known as an exposure apparatus used for semiconductor manufacturing. This stepper reduces the pattern image formed on the original plate, that is, the reticle with the projection lens while stepwise moving the substrate such as a semiconductor wafer under the projection lens, and sequentially exposes it to a plurality of positions on one wafer. It is a thing. From the viewpoint of performance such as resolution and overlay accuracy, the stepper is considered to be a mainstream aligner (exposure device) in the future.

The size of the semiconductor wafer processed by such an aligner is diversified according to the type of the semiconductor device which is a product. That is, in a small-volume mass-production device such as a MOS memory, a large-diameter semiconductor wafer is used in order to increase the number of acquisition devices per wafer by batch processing and reduce costs. The size of the semiconductor wafer in this direction is currently φ6 ″ (φ150 mm), but in 1987 it is expected to be φ8 ″ -10 ″ (φ200 mm-250 mm).

On the other hand, for low-volume, high-mix production devices such as gate arrays,
The size of the semiconductor wafer remains at φ3 ″ to φ4 ″. In addition, F, which uses GaAs as a substrate, has attracted attention recently.
Due to the difficulty of crystal technology, ET and light-emitting devices have a maximum φ
3 ″.

Under such circumstances, it is a stepper capable of handling semiconductor wafers having a diameter of 8 ″ to 10 ″ and φ3 ″ to φ4 ″.
Conventional φ3 ″ to φ4 ″ even when used for semiconductor wafers
It has been earnestly desired to realize an exposure apparatus having less demerits than a commercial exposure apparatus.

However, the conventional exposure apparatus for φ3 ″ to φ4 ″ is simply φ8 ″.
Φ3 ″ to φ4 ″ just by upsizing for up to φ10 ″
The following problems occur when used as an application.

That is, the stroke of the XY stage needs to be 3 to 4 times the wafer size, but the increase of this stroke increases the size of the moving stage including the XY stage and the like.

Therefore, it becomes difficult to guarantee the same accuracy as that before the size increase. Further, in order to guarantee the same accuracy, it is necessary to increase the rigidity of the guide and the like.

Therefore, the stage weight becomes heavier, and it is necessary to strengthen the structure such as the lens holding as a measure against vibration due to the stage weight and the acceleration when moving the stage. It takes time for distance feeding and positioning due to increased time.

The cost increase of the XY stage, the increase in the size of the entire device, and the increase in the cost of the entire device cannot be ignored.

Etc.

These are the equipment for φ8 ″ to φ10 ″, which is simply the size up of the conventional equipment, φ3 ″ to φ4 ″ or φ5 ″.
When it is used for small-diameter wafers such as, for example, the equipment is too large (,) the price is too high (,) Throughput is lower than the dedicated equipment such as φ3 ″ wafer dedicated equipment. It will be a great disadvantage and a burden.

[Object of the Invention] An object of the present invention is to perform an exposure method that is particularly effective for a large-diameter substrate and to treat a large-diameter substrate that implements this method, and also to be used for a small-diameter substrate, with little disadvantage. An object is to provide an exposure apparatus. Specifically, it is possible to provide a compact exposure apparatus that can cope with diversified photosensitive substrate sizes with the same exposure apparatus, and that does not burden the user with the above disadvantages even when processing small-sized substrates. And to provide an advantageous wafer handling method for large diameter wafers.

This "wafer handling method is advantageous" is, for example, a chuck-hand transfer method that is advantageous for flattening the wafer, which shortens the wafer exchange time and improves the throughput. It is possible to have a degree of freedom in the direction of the wafer to be placed on the XY stage and to retry the wafer.

[Outline and Effect of the Invention] In order to achieve the above object, according to the present invention, the positional relationship between the substrate and the XY stage is transferred during the exposure of one substrate, and the substrate is divided into a plurality of regions for exposure, and The transfer of the substrates is performed by picking up the substrate from the XY stage and changing the relative positional relationship between the two while separating the two, and then changing the relative positional relationship between the two. Is again mounted on the XY stage.

As a result, the stroke of the XY stage can be reduced, and the device can be reasonably made compact.

Further, in one embodiment of the present invention, an arm hung on the stage side based on the lens barrel surface plate is configured,
Make effective use of this. That is, it is used as a temporary holding arm for wafers when transferring wafers and as a temporary holding arm for exposed wafers when replacing wafers on the stage.

Description of Embodiments Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic configuration of a wafer stage and its vicinity in a wafer transfer position of a semiconductor exposure apparatus (stepper) according to an embodiment of the present invention. Although the reticle stage, the projection lens, the TTL alignment optical system, and the like of the apparatus shown in the figure are not shown in particular, they are assumed to have the same structure as a conventional stepper for φ3 ″ wafer, for example.

In the figure, WD is a base, and on this base WD, Y
A wafer stage including a stage WY movable in the X direction, a stage WX movable in the X direction, and a stage θZ rotatable in the θ direction and movable (elevating) in the Z direction is mounted. The stage WY and the stage WX form an XY stage. Other structures such as the projection lens are also mounted or fixed on the base WD.

MX and MY are optical squares of a laser measuring system using a laser interferometer, HA is a wafer supply / collection hand, and HB.
Is a hand for collecting a small diameter wafer, HC is a hand for transferring a wafer, W1 and W2 are wafers, and WC is a wafer chuck. In the wafer chuck WC, when the hand HB directly collects the wafer from the chuck WC, the hand escape portion L is provided so that the hand HB can enter the back surface side of the wafer.
L and LR are provided on the left and right. Further, the hand HC has a finger portion F for picking up the wafer from the chuck WC.
G, an arm AM for raising and lowering and rotating the finger portion FG. The rotation center of the arm AM is eccentric with respect to the wafer W1 to be picked up.

FIG. 2 is a top view and AA cross-sectional view of the wafer chuck WC. A large number of linear suction grooves G are provided on the upper surface of the chuck WC. These suction grooves are appropriately divided into groups, and a vacuum of another system is supplied to each group via the nipples D1, D2, D3. It is like this. These groups depend on the size of the wafer mounted on the chuck WC, and when the wafer is transferred by the chuck WC, all the suction grooves and the nipple D2 of the group connected to either the nipple D1 or D3. It is set so that the entire suction groove of the connected group is always covered with the wafer. It should be noted that the pattern formed by the suction grooves may be arbitrarily determined in accordance with the size of the wafer to be mounted on the chuck WC and the state of transfer when the wafer is always held well and the surface is straightened. it can. Further, although the chuck WC supports the wafer by a line, it may have a so-called pin chuck structure in which the wafer is supported by a point, and a large number of suction holes are provided instead of the suction grooves to support the surface of the wafer. You may do it.

FIG. 3 is an explanatory view showing each operation stage of the apparatus of FIG. In the figure, RT is a reticle and PO is a projection lens.

Next, the operation of the exposure apparatus having the above configuration will be described. Here, as shown in FIG. 4, the movable region T of the XY stage is
E is 200 mm x 230 mm, which is equivalent to a φ3 ″ wafer dedicated machine (movable distance of Y stage WY 230 mm, movable distance of X stage WX 2
00mm), the effective screen of the projection lens PO is φ20mm, 5mm
A description will be given of a case of forming as many as 16 mm actual element patterns on a φ10 ″ wafer. Since the effective screen of the projection lens PO is φ20 mm, two actual element patterns are formed on the reticle RT. By printing two real element patterns (10 mm × 16 mm) each in one exposure,
Improve throughput. Further, in the conventional exposure method, it is impossible to print the actual element pattern on the entire surface, no matter how the wafer W1 is mounted on the XY stage. Therefore, here, as shown in FIG. 4, the exposure surface of the wafer is divided into two regions each included in the movable region of the XY stage, one region is exposed, and then the position of the wafer with respect to the XY stage is changed. And expose the other area. As can be seen from FIG. 4, the maximum diameter of the wafer that can be processed when the wafer is divided into two areas and exposed is as follows. It depends on the size of the area TE to be exposed.

When an exposure start command is issued after setting the reticle RT and the like, this exposure apparatus starts the following divided exposure operation under the control of a CPU (not shown).

That is, first, with the chuck WC tilted so that the major axis direction coincides with the directions of the diagonal lines a to a of the movable region in FIG. 4, the wafer W1 is taken out from the wafer carrier (not shown) and placed on the chuck WC by the hand HA. Place (Fig. 3a). The positional relationship of the wafer W1 with respect to the chuck WC at this time is shown by a chain double-dashed line in FIG. If the wafer W2 is held by the hand HC, the hand HA receives the wafer W and carries it out (FIG. 3b).

Then, the XY stage is moved, the first shot S11 of the first region of the wafer W1 is sent under the projection lens PO to be exposed (FIG. 3b), and thereafter, while the XY stage is sent, S12, S13, .. and so on, all the shots in the first area on the right side of the dividing line DL in FIG. 4 are exposed by step-and-repeat. Hand H in parallel with this exposure operation
Rotate C 180 ° and keep it in the state of FIG. 3c.

When the exposure of the first region is completed, the XY stage is moved to the transfer position side (the right direction in the drawing), and the wafer W1 on the chuck WC is picked up by the hand HC in the middle thereof (FIG. 3c). When the XY stage reaches the transfer position (FIG. 3d), the hand HC is lowered and the wafer W1 is placed on the chuck WC again, and the chuck WC side is positioned below the second region of the wafer W1. (Fig. 3e). In this state, the XY stage is moved in the same manner as described above, and the first shot S21 of the second region of the wafer W1 is sent under the projection lens PO to be exposed (FIG. 3f), and hereinafter, S22, S23 ,. Then, all the shots in the second area on the left side of the dividing line DL in FIG. 4 are exposed by step-and-repeat. In parallel with these exposure operations, a new unexposed wafer W2 is supplied to the hand HA (Fig. 3f).

When the exposure of the entire surface of the wafer is completed in this way, the XY stage is moved to the transfer position, and the exposed wafer W1 on the chuck WC is picked up by the hand HC (FIG. 3g). Then, the unexposed wafer W2 is brought from the hand HA onto the chuck WC (FIG. 3h),
At the same time, the hand HC is rotated 180 ° and the unexposed wafer W
1. Return the exposed wafer to the state of W2 shown in FIG. 3 (a).

As described above, when the wafer is unloaded from the chuck WC by the hand HA, first, the hand HC picks up the exposed wafer from the chuck WC, and further rotates 180 ° to put the exposed wafer in the hand HA side. The chuck WC does not need a notch to escape the hand HA,
The wafer can be supported in a wider range, that is, more stably. Further, a hand for collecting wafers (especially, a hand for large-diameter wafers) is not required, which is useful for downsizing of the apparatus.

In this apparatus, a wafer having a size that fits into the chuck WC, that is, a wafer having a short diameter of the chuck WC, for example, φ5 ″ or less, is directly recovered from the XY stage by the hand HB. Saves time and effort when exchanging or setting hand HC when processing
For small diameter wafers, it has the same usability as the small diameter wafer dedicated machine.

In this apparatus, the wafers are transferred during the exposure of one wafer, which causes a time loss. However, in the 10-inch full-stroke XY stage and the 8-inch full-stroke XY stage, the step time for the same distance is longer in the 10 "device due to the masses as described above. For example, the step time per 10 mm is If 0.4 ″ is used for an 8 ″ device, 0.5 second is used for a 10 ″ device. Therefore, in the case of the φ10 ″ wafer of FIG. 4, since the number of shots is 250, the step time per wafer is An 8 ″ device will take 100 seconds and a 10 ″ device will take 125 seconds. In other words, in the case of the 8 ″ device, the processing time per wafer is still 15 times more than that of the 10 ″ device, even if the transfer time of 10 seconds is expected.
Seconds will be short.

[Modification] In the above-described embodiment, the chuck WC is tilted about 45 ° with respect to the X-axis and the Y-axis, more precisely, parallel to the diagonal lines a to a of the movable region of the XY stage. However, when the dividing line DL can be set parallel to the X or Y axis, that is, when processing a wafer having a diameter of 230 mm or less in the above description, it is not always necessary to tilt.

Further, although the chuck WC is tilted with respect to the X axis and the Y axis in the above description, the chuck WC is tilted with respect to the chip arrangement on the wafer in a state where the major axis is set parallel or at right angles to the X axis. (See Fig. 4c). In this case, since the main step feed of the wafer can be performed by simultaneously driving the X stage and the Y stage, the speed of the X stage and the Y stage is combined and faster than the case of sending only the conventional X stage. Speed, which helps improve throughput. That is, if the speed ratio of the X stage and the Y stage is 4: 3, the chip arrangement is θ with respect to the X axis.
= Tan ^-1 (3/4) When tilted, the speed becomes 5, which is the fastest.

Further, in the above description, when wafers are being transferred during exposure, the wafers are simply moved up and down, and the wafers are displaced by the amount of movement of the XY stage during this movement. It is also possible to provide a mechanism above the XY stage, which moves in a direction parallel to the image plane of the projection lens PO without a rotational component, and to perform the above-mentioned transfer by this mechanism.

Furthermore, when the wafer is picked up by the above hand HB, the wafer is picked up from the XY stage by the hand HC, and then this hand HC is rotated by 90 ° and handed over to the hand HB. The LL becomes unnecessary, and the wafer can be supported in a wider range, that is, more stably.

Other Embodiments In the above-described embodiments, the chuck WC is mounted and demounted (loaded, unloaded and transferred) on and from the XY stage while the chuck WC remains on the XY stage, but the wafer is fixed to the chuck. It is also possible to attach / detach the XY stage together with the chuck in this state. In this case, two of the same shape
If one chuck is prepared so that one is on the XY stage and the other is in the wafer transfer system, replacement of the unexposed wafer and the exposed wafer by the supply / collection hand HA can be performed without any problem. be able to.

FIG. 5 shows a case where the wafer W and the wafer chuck WC are integrally attached and detached to and from the XY stage (loading (exchange) → first area exposure → transfer → second area exposure → unloading (exchange)). FIG. This operation is performed in exactly the same way as the case of attaching and detaching only the wafer of FIG. 3 except that the wafer W and the chuck WC are always integrated.

The merit of integrally treating the wafer W and the chuck WC in this way is that the possibility of wafer damage is reduced as compared with the case where the wafer is handled alone, and the chuck W is
If the outer dimension of C is kept constant, it is not necessary to replace or reset the mechanical parts of the hand HC and the hand HA of FIG. 9 described later according to the wafer size.

FIG. 6 shows an example of a chuck used for this integrated attachment / detachment. In the figure, the chuck WC is formed in a disk shape having a diameter slightly larger than the diameter of the wafer W. N
R and NL are notches for separating and transferring the wafer from the chuck WC when the wafer is taken in and out from a wafer carrier (not shown). The chuck WC has a portion P which is projected in the diameter direction so as not to be covered by the wafer.
R and PL are provided, and the projections PR and PL are provided with alignment AR and AL, respectively. If the relative positional relationship between the wafer and the chuck is measured in advance by the marks AR and AL and the alignment mark on the wafer in the transfer system or the like, the marks AR and AL can be referred to when the wafer is mounted on the XY stage. This helps to align the wafer at a higher speed and with higher accuracy. Further, prior to the integrated transfer of the wafer and the chuck during the exposure, the positional relationship between the alignment marks AR and AL on the chuck, the apparatus side or reticle side reference mark (not shown), and the XY stage is read and this value is stored. At the same time, after the transfer, the positional relationship between the marks AR and AL and the measurement side or the reticle side reference mark and the XY stage is read again, the error before and after the transfer is calculated, and the rotational component is corrected by the θZ stage. , XY components are added as offset values to the position of the XY stage, and the unexposed region on the wafer is exposed, which also helps to improve the throughput.

FIG. 7 shows another embodiment of the integrated detachable type. In the figure, HA is a wafer chuck WC replacement hand, H
C is a hand for lifting the chuck WC. The operation is exactly the same as that shown in FIG. The hand HA realizes the exchange of the wafer and the chuck with respect to the stage WXY by holding the wafer chuck WC on the side surface and rotating it around the axis AS.

In the transfer system, the unexposed wafer W0 is supplied by the supply carrier SC.
After being taken out from the wafer chuck WC0, the wafer W0 is placed on the wafer chuck WC0 which is positioned after pre-alignment at a pre-alignment position (not shown), and is then transferred to the hand HA as an integrated body of the wafers W0 and WC0. The exposed wafer received from the hand HA is conveyed to a predetermined position together with the chuck, then separated from the chuck and stored in the recovery carrier RC.

FIG. 8 schematically shows the structures of the hand HC, the chuck WC, and the stage WS suitable for the above-mentioned integrated attachment / detachment. When the wafer W and the chuck WC are delivered to the hand HC, the opening of the rubber packing P1 of the hand HC covers the hole H1 on the surface of the chuck WC, and the vacuum is supplied through the tube T1. Then, the pipeline U1, the packing P
1, the pressure in the conduit U2 and the suction hole H2 is reduced, and the chuck W
C is the packing P1 with the wafer W being sucked by the suction hole H2.
Is absorbed by the hand HC. The chucking of the wafer W by the chuck WC in this case is performed by the chucking of the wafer W and the chuck WC.
It is sufficient if it is realized to the extent that the integration with
Here, a small number of suction holes H2 are provided in the peripheral portion of the wafer W.

On the other hand, when the wafer W and the chuck WC are delivered to the stage WS, vacuum is supplied through the tube T2 with the opening of the rubber packing P2 of the stage WS covering the hole H3 on the back surface of the chuck WC. Then, the tube T
2 through the packing P2 and the conduit U3 to the suction hole H4
Is depressurized, and the chuck WC is adsorbed to the stage WS by the packing P2 while adsorbing the wafer W in the adsorption hole H4.
In this case, since the chucking of the wafer W by the chuck WC is preferably such that the wafer W is flattened, the suction holes H4 are provided over the entire back surface of the wafer W. The chuck WC can be provided with another vacuum suction system, for example, for the hand HA having an opening on the side surface, if necessary.

[Brief description of drawings]

FIG. 1 is a schematic view of a main part of a semiconductor exposure apparatus according to an embodiment of the present invention, FIG. 2 is an enlarged top view of a wafer chuck in FIG. 1 and its sectional view taken along line AA, and FIG. FIG. 4 is an operation explanatory view of the apparatus of FIG. 1, FIG. 4 is a chip layout view of a wafer to be exposed by the apparatus of FIG. 1 and an actual element pattern layout view within an effective exposure plane, and FIG. FIG. 6 is a perspective view of a wafer chuck used in the apparatus of FIG. 5, and FIG. 7 is a schematic top view of a semiconductor exposure apparatus according to still another embodiment of the present invention. FIG. 8 is a structural explanatory view of a wafer chuck, a transfer hand, and an XY stage suitable for use in the apparatus of FIG. 5 or 7. RT: Reticle, PO: Projection lens, WY: Y-direction moving stage, WX: X-direction moving stage, θZ: θZ stage, WXY: XY stage, HA: Wafer supplying / collecting hand, HB: Small-diameter wafer collecting hand , HC: Wafer transfer hand, AM: Arm, W, W1, W2: Wafer, DL: Dividing line, S11, S12, ..., S21, S22, ...: Shot, WC: Wafer chuck, AR, AL: Position Alignment mark, G: suction groove, D1, D2, D3: nipple.

Claims (16)

[Claims] 1. A substrate having a photosensitive thin film is mounted on an XY stage, and a pattern of an original plate reduced and projected by a projection lens by step-moving the substrate on the XY stage is applied to each of a plurality of shots on the substrate. A step-and-repeat exposure method in which exposure is sequentially performed, wherein the upper surface of the substrate is divided into a plurality of regions in advance, and a series of exposures according to the step-and-repeat method is first performed on one region, and thereafter, the exposure is performed. The substrate is picked up from the XY stage, the relative positional relationship between the two is changed in a state where the two are separated, and then the substrate is mounted on the XY stage again with the relative positional relationship between the two being changed. Then, a series of exposures by the step-and-repeat method is performed on an unexposed area on the substrate. 2. The exposure method according to claim 1, which is applied when the size of the substrate is larger than a size that can be covered by the movable region of the XY stage. 3. A projection lens, a plate for holding an original plate on the object plane side of the projection lens, an illumination means for illuminating the original plate, and a chuck for holding a substrate having a photosensitive thin film on the image plane of the projection lens. And an XY stage that mounts the chuck and can move in a direction parallel to the image plane, and repeatedly exposes the projection image of the original plate by the projection lens onto the substrate while sending the XY stage. A step-and-repeat type exposure apparatus, in which the substrate is picked up from the XY stage and the relative positional relationship between the two is changed, and then the relative positional relationship between the two is changed. Substrate transfer means for mounting the substrate again on the XY stage in such a state that a series of repetitive exposures are performed on a partial area on the substrate, and the relative positional relationship is changed. 2. An exposure apparatus comprising: a divided repetitive exposure control means for repeating a series of repetitive exposures for a part or all of the unexposed area on the substrate by a necessary number of times. 4. A substrate which is smaller than a size which can be covered by a movable region of the XY stage is subjected to normal repetitive exposure, and a large substrate is divided into a plurality of regions to perform the repetitive repetitive exposure. The exposure apparatus according to item 3 above. 5. The maximum diameter of a substrate that can be processed when the substrate is divided into two regions for exposure is determined by the diagonal stroke of the rectangular movable region of the XY stage and the region exposed at one time. The exposure apparatus according to claim 3 or 4, which is a value obtained by adding the size. 6. The arrangement direction of chips to be baked on the substrate is
90 with respect to the X and Y running directions of the XY stage
Claims 3 to 5 having an angle other than an integral multiple of °
The exposure apparatus according to any one of items. 7. The exposure apparatus according to claim 6, wherein the arranging direction of the chips is parallel to a diagonal line of a rectangular movable area of the XY stage. 8. The substrate transfer means also serves as a carrying-out substrate temporary holding device when the substrate on the XY stage is replaced, and the exposed substrate is not exposed to the XY stage after being picked up by the transfer means. The exposure apparatus according to claim 7, wherein the substrate is carried in and the exposed substrate is carried out from the transfer means with a single hand. 9. The substrate transfer means eccentrically picks up and holds the substrate, and when the relative position of the XY stage with respect to the substrate is changed, the substrate is vertically moved without rotating and displacing, and when the substrate is replaced. 9. The exposure apparatus according to claim 8, wherein the exposure substrate is rotated 180 degrees to shift the exposed substrate to the hand side. 10. The substrate transfer means comprises a mechanism which is provided above the XY stage and moves the substrate after the series of exposures in a direction parallel to the image plane without rotation components. The exposure apparatus according to any one of claims 3 to 7. 11. A substrate transfer means for detaching the substrate together with the XY stage together with the chuck while fixing the substrate to the chuck. The exposure apparatus described. 12. The exposure apparatus according to claim 11, wherein the chuck has an alignment mark on a portion of the surface that is not covered with the substrate. 13. Prior to the integrated transfer of the substrate and the chuck, the positional relationship between a plurality of alignment marks on the chuck, the apparatus side or original plate side reference mark, and the XY stage is read and the values are stored. After the transfer, the positional relationship between the alignment marks at a plurality of points, the apparatus side or original plate side reference mark, and the XY stage is read again, the error before and after the transfer is calculated, and the rotation component is corrected by the rotation mechanism. The XY component is added to the position of the XY stage as an offset value, and the unexposed region on the substrate is exposed.
The exposure apparatus according to the item. 14. A chuck having two chucks of the same shape, one of which is on the XY stage and the other of which is in a transfer system for the substrate, and the substrate and the chuck are exchanged as a unit when exchanging the substrate. The exposure apparatus according to any one of items 11 to 13 in the above range. 15. The chuck according to claim 3, wherein the chuck has a surface, a line or a point for supporting the substrate only in a region where the substrate can be exposed by moving the XY stage and in the vicinity thereof. The exposure apparatus according to any one of claims. 16. The chuck has an adsorption groove for holding and flattening the substrate, which is provided only in a portion of the surface covered with the substrate, and a pipeline for supplying a vacuum to the adsorption groove. The exposure apparatus according to claim 15 having.