JPH0691150B2 - Substrate processing method - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a substrate processing method suitable for semiconductor manufacturing.

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 ″ to 10 ″ (φ200 mm to 250 mm).

On the other hand, for small-quantity, high-mix production devices such as gate arrays,
The size of the semiconductor wafer remains at φ3 ″ to φ4 ″. In addition, FETs and light-emitting devices using GaAs as a substrate, which have recently been receiving attention, have a maximum diameter of 3 "due to the difficulty of crystal technology.

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 ″.
If the size is increased to 10 ″, the following problems will occur when used for φ3 ″ to φ4 ″.

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 size increase of the entire device, and the cost increase of the entire device cannot be ignored.

Etc.

These are the special machines, for example, the φ3 ″ wafer dedicated machine, when the φ8 ″ to 10 ″ apparatus, which is simply the size up of the conventional apparatus, is also used for small diameter wafers such as φ3 ″ to φ4 ″ or φ5 ″. Compared with, the device is too large (,,) The price is too high (,) The throughput decreases (), which is a great disadvantage and a burden to the user.

Therefore, at present, it is advantageous for a compact exposure apparatus and a large-diameter wafer that can cope with diversifying wafer sizes with the same exposure apparatus and that does not burden the user with the above disadvantages even when processing small-sized wafers. Development of a wafer handling method is desired.

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 retry the wafer, which has flexibility in the direction of the wafer to be placed on the XY stage.

[Object of the Invention] An object of the present invention is to provide a substrate processing method capable of further miniaturizing a substrate processing apparatus.

[Summary and Effect of the Invention] In order to achieve the above object, a method of the present invention is a substrate processing method for supplying and collecting a substrate to and from a substrate mounting means for mounting and holding the substrate. A first hand for supplying an unprocessed substrate and placing it on the substrate placing means, a treatment step for treating the substrate held by the substrate placing means, and the first hand. A second hand, which is different from the above, to pick up the processed substrate from the substrate mounting means, and the first hand,
And a collecting step of collecting and collecting the processed substrate picked up by the second hand.

According to this, since the wafer is supplied and collected by the first hand, the collecting hand which is conventionally provided separately from the supplying hand becomes unnecessary. Therefore, by applying this substrate processing method, the device for supplying and collecting the substrate to and from the substrate mounting means can be configured in a small size.

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 particularly shown, they are assumed to have the same configuration as a conventional stepper for φ3 ″ wafer, for example.

In the figure, WD is a base, and on this base WD, a stage WY movable in the Y direction and a stage movable in the X direction
A wafer stage composed of a stage θZ capable of moving (moving up and down) in WX and θ rotation and 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 length measuring lasers using a laser interferometer, HA is a wafer supply / collection hand, HB is a small-diameter wafer collection hand, HC is a wafer transfer hand, W1, W2 Is a wafer and WC is a wafer chuck. On the wafer chuck WC, hand escape portions LL and LR are provided on the left and right so that the hand HB can enter the back surface side of the wafer when the hand HB directly retrieves the wafer from the chuck WC.
Further, the hand HC includes a finger portion FG for picking up the wafer from the chuck WC, an arm AM for moving up and down the finger portion FG, and the like. 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 a sectional view taken along line AA of the wafer chuck WC. This chuck WC has a linear suction groove G on the upper surface.
Are provided in large numbers, and 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. These groups are based on the size of the wafer mounted on this chuck WC.
Further, even if the wafer is transferred by the chuck WC, the entire suction groove of the group connected to either the nipple D1 or D3 and the suction groove of the group connected to the nipple D2 are always covered with the wafer. Is set to. Note that the pattern formed by the suction grooves can be arbitrarily determined if the wafer is always held well and the surface is straightened in accordance with the size of the wafer mounted on the chuck WC and the state of transfer. it can. Also this chuck
Although the WC supports the wafer with lines, it may have a so-called pin chuck structure in which the wafer is supported with points, or the wafer may be surface-supported by providing a large number of suction holes instead of the suction grooves. Good.

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 area TE of the XY stage is 200 mm × 230 mm (Y stage equivalent to that of the φ3 ″ wafer dedicated machine).
WY movable distance 230mm, X stage WX movable distance 200mm),
The case where the effective screen of the projection lens PO is φ20 mm and the actual element pattern of 5 mm × 16 mm is formed on the φ10 ″ wafer as much as possible will be described.
Since it is 20 mm, two real element patterns are formed on the reticle RT, and two real element patterns (10 mm × 16 mm) are printed by one exposure to improve the throughput. In the conventional exposure method, the wafer W1 is XY
No matter how it is mounted on the stage, it is impossible to print the actual element pattern on the entire surface. Therefore, here
As shown in FIG. 4, the exposure surface of the wafer is divided into two areas each included in the movable area of the XY stage, one area is exposed, and then the position of the wafer with respect to the XY stage is changed to move the other area. Expose. 2 on the wafer like this
As can be seen from FIG. 4, the maximum diameter of the wafer that can be processed when divided into two areas and exposed is the diagonal stroke of the rectangular movable area of the XY stage and the area TE exposed at one time.
It depends on the size of.

When the exposure start is instructed after setting the reticle RT and the like, this exposure apparatus starts the following divided exposure operation under the control of the 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 hand HC holds the wafer W2, the hand HA receives the wafer W and carries it out (FIG. 3b).

Then, the XY stage is moved, and the first shot S11 of the first region of the wafer W1 is sent under the projection lens PO to be exposed (FIG. 3b).
2, S13, ..., the first on the right side of the dividing line DL in FIG.
All shots in the area are exposed by step-and-repeat. In parallel with this exposure operation, the hand HC is rotated by 180 ° and kept in the state of FIG. 3c.

When the exposure of the first area is completed, the XY stage is moved to the transfer position side (right in the drawing), and the chuck WC
The upper wafer W1 is picked up by the hand HC (Fig. 3c). Then, the XY stage reaches the transfer position (Fig. 3d).
Then, the hand HC is lowered to mount the wafer W1 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 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 where the chuck WC is moved.
The upper exposed wafer W1 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), and at the same time, the hand HC
Is rotated by 180 ° to return to the state of FIG. 3A in which the unexposed wafer is shown by W1 and the exposed wafer is shown by W2.

As described above, when the wafer is unloaded from the chuck WC by the hand HA, the hand HC first picks up the exposed wafer from the chuck WC, and further rotates 180 ° to put the exposed wafer on the side of the hand HA. The chuck WC does not need a notch for escaping the hand HA, and can support the wafer 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 device, the size to fit in the chuck WC,
That is, a wafer with a short diameter of the chuck WC, for example, a diameter of φ5 ″ or less, is directly collected from the XY stage by the hand HB. This makes it necessary to replace or set the hand HC when processing a small diameter wafer. For small-diameter wafers, the same usability as for small-diameter wafer dedicated machines is realized.

In this apparatus, the wafers are transferred during the exposure of one wafer, which causes a time loss. However, with a 10 inch full stroke XY stage and 8
In the case of inch full stroke XY stage, the step time of the same distance is longer in the 10 "device because of its mass as described above. For example, if the step time per 10 mm is 0.4 seconds in the 8" device, With a 10 ″ device, it takes 0.5 seconds.
Therefore, the number of shots is 25 for the φ10 ″ wafer in FIG.
Since it is 0, the step time per wafer is 100 seconds for the 8 ″ apparatus and 125 seconds for the 10 ″ apparatus. That is,
In the case of the 8 ″ device, the processing time per wafer is still 15 seconds shorter than that of the 10 ″ device even if the transfer time of 10 seconds is expected.

[Modification] In the above-described embodiment, the chuck WC is tilted at 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, in the above, the chuck is used for the X-axis and the Y-axis.
Although WC is tilted, the chuck WC may be tilted toward the chip array on the wafer with the major axis 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 conventional X feed can be performed.
The speed of the X stage and the Y stage becomes a combined high speed as compared with the case of sending only by the stage, which is useful for improving the throughput. That is, if the speed ratio between the X stage and the Y stage is 4: 3, the above chip arrangement is θ = tan with respect to the X axis.
^-1 (3/4) When tilted, the speed becomes 5, which is the fastest.

Further, in the above description, when transferring wafers 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 for moving in a direction parallel to the image plane of the projection lens PO without any rotational component, and to perform the above-mentioned transfer by this mechanism.

Furthermore, when collecting wafers with the above hand HB,
If you pick up the wafer from the XY stage by HC and then rotate this hand HC by 90 ° and hand it over to the hand HB, the hand relief parts LR and LL of the chuck WC are not necessary, and the wafer is more stable in a wider range. Can be supported by.

[Other Embodiments] In the above-described embodiment, the chuck WC is mounted and removed (loaded, unloaded, and transferred) on the XY stage while the chuck WC is placed on the XY stage, but the wafer is fixed to the chuck. It is also possible to attach and detach the XY stage together with the chuck in this state. In this case, if two chucks of the same shape are prepared so that one is on the XY stage and the other is in the wafer transfer system, an unexposed wafer and an exposed wafer by the supply / collection combined hand HA Can be replaced without any problem.

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

In this way, the advantage of handling the wafer W and the chuck WC integrally is that the possibility of wafer damage is reduced compared to the case of handling the wafer alone, and if the outer dimensions of the chuck WC are made constant, the hand HC And the ninth described below
It is not necessary to replace or reset the mechanical parts such as the hand HA shown in the figure 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. NR, NL
Is a notch for separating and delivering the wafer from the chuck WC when loading / unloading the wafer to / from a wafer carrier (not shown). Further, the chuck WC is provided with portions PR and PL which are projected in the diameter direction so as not to be covered by the wafer, and the alignment marks AR and PL are respectively provided on the projections PR and PL.
AL is provided. If the relative position relationship between the wafer and the chuck is measured in advance in the transfer system, etc., by using the marks AR, AL and the alignment mark on the wafer, refer to the marks AR, AL when mounting on the XY stage. This helps to align the wafer at a higher speed and with higher accuracy. In addition, 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 the value is stored. At the same time, after the transfer, the positional relationship between the marks AR, AL and the apparatus 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. For the XY component, if this is added to the position of the XY stage as an offset value and the unexposed region on the wafer is exposed, this also helps improve the throughput.

FIG. 7 shows another embodiment of the integrated detachable type. In the figure, HA is a wafer chuck WC replacement hand, and HC is a chuck WC lifting hand. The operation is exactly the same as that shown in FIG. The hand HA is realized by exchanging 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 taken out from the supply carrier SC and is positioned after pre-alignment at a pre-alignment position (not shown) and is on standby.
After being placed on WC0, it is handed over to hand HA as an integrated body of 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 shows a hand HC and a chuck suitable for the integrated attachment / detachment.
1 schematically shows the structures of WC and stage WS. When handing the wafer W and the chuck WC to the hand HC, the chuck WC is opened at the opening of the rubber packing P1 of the hand HC.
A vacuum is supplied through the tube T1 by covering the hole H1 on the surface of the tube. Then, conduit U1, packing P1, conduit U2 and suction hole
The pressure of H2 is reduced, and the chuck WC is sucked by the hand HC by the packing P1 while the wafer W is sucked by the suction hole H2. In this case, the chucking of the wafer W by the chuck WC causes
Since it suffices that the integration of the chuck WC with the chuck WC is realized, a small number of suction holes H2 are provided in the peripheral portion of the wafer W here.

On the other hand, when the wafer W and the chuck WC are delivered to the stage WS, a 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, from tube T2 to packing P2
And the suction hole H4 is decompressed via the conduit U3 and the chuck WC
The wafer W is adsorbed on the stage WS by the packing P2 while the wafer W is adsorbed on the adsorption hole H4. Since the chucking of the wafer W by the chuck WC in this case 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 supply / collection hand, HB: Small-diameter wafer collection 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 (6)

[Claims] 1. A substrate processing method for supplying and collecting a substrate to and from a substrate mounting means for mounting and holding the substrate, wherein an unprocessed substrate is supplied by a first hand. The substrate mounting is performed by a supplying step of mounting the substrate on the mounting means, a processing step of processing the substrate held by the substrate mounting means, and a second hand different from the first hand. And a collecting step of collecting the processed substrate picked up by the second hand by the first hand and collecting the processed substrate by the first hand. . 2. The method according to claim 1, further comprising a step of placing another unprocessed substrate on the substrate placing means by the first hand between the picking up step and the collecting step. The substrate processing method described. 3. The substrate processing method according to claim 1, wherein the substrate is exposed in the processing step. 4. The substrate processing method according to claim 3, wherein in the processing step, a plurality of regions of the substrate are sequentially exposed. 5. The substrate processing method according to claim 1, further comprising a step of collecting the processed substrate in a direction different from that of the first hand by the third hand. 6. The substrate processing method according to claim 5, wherein whether to collect with the first hand or with the third hand is determined according to the size of the substrate.