JP2000323388A - Method and device for alignment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow alignment of high precision and efficiency with on limit on a substrate, by considering at a first stage a dislocation information acquired by carrying the substrate to a second stage for alignment for the next alignment. SOLUTION: A wafer is carried from a carrier to a pre-alignment stage (S11), for judging whether it is a second wafer or later (S12). With θ drive amount for a first wafer being set (S13), the set drive amount is included for consideration in a rotation position which is detected from an orientation flat or notch, and the second wafer or later is pre-aligned (S14) for precision alignment (S15). A stage for precision alignment is driven to one below a reduction projection lens, and an electronic circuit pattern of a reticle is transferred to the wafer (S16). All specified wafers are judged to be processed or not (S17). If no step is carried out, the process goes back to a step S11 and wafer process is finished for process completion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positioning method and a positioning apparatus for aligning a substrate with an electronic circuit pattern of a mask or a reticle, for example, in an exposure apparatus for manufacturing a semiconductor device.

[0002]

2. Description of the Related Art Conventionally, a stepper, which is an exposure apparatus, exposes a mask or a reticle electronic circuit pattern onto a wafer, which is a substrate for a silicon integrated circuit, and prints, that is, transfers the pattern. In order to manufacture a semiconductor device having a highly integrated circuit from a wafer, it is important to align the wafer with a mask or a reticle electronic circuit pattern with high accuracy.

FIG. 4 is a flowchart of a conventional wafer processing step. In step S1, a wafer is transferred from a carrier to a preliminary alignment stage. Step S2
Then, the orientation flat or notch provided on the wafer is detected, and the pre-alignment stage is rotated to pre-align the wafer at a predetermined position.
In step S3, the wafer is transferred from the preliminary alignment stage to the XYθ driving stage located below the microscope. Then, the displacement of the target provided on the wafer is measured through a microscope, and the XYθ driving stage is driven to precisely align the wafer. Step S4
Then, the XYθ driving stage is driven below the reduction projection lens to transfer the mask or reticle electronic circuit pattern onto the wafer. In step S5, it is determined whether or not a predetermined number of wafers have been processed. If the predetermined number of wafers have not been processed, the process returns to step S1, and if the predetermined number of wafers have been processed, the processing of the wafer ends. I do.

When a plurality of wafers are processed in parallel, the processing of the next wafer is started at the stage where the previous wafer has been processed in step S3 as shown by arrow C1.
When the previous wafer has been processed in step S4, the processing of the next wafer in step S2 ends.

[0005]

In recent years, the accuracy of preliminary alignment of steppers has been improved, and adjustments for suppressing variations in accuracy between steppers have been advanced.
It is no longer necessary to increase the θ drive amount of the θ drive stage. Also, since the shift component when driving the XYθ driving stage in the θ direction deteriorates the precision of the precision alignment, it is preferable to reduce the θ driving amount. Further, in order to reduce the size and weight of the XYθ drive stage, increase the efficiency, and increase the accuracy, it is desired to reduce the θ drive amount.

However, when the θ drive amount is reduced, there is no problem between the steppers in which the adjustment for suppressing the variation in accuracy is advanced, but the wafer on which the electronic circuit pattern is largely rotated and transferred in another stepper is processed. In such a stepper, the rotation amount of the electronic circuit pattern exceeds the range of the θ drive, so that not only the precise alignment of the wafer becomes impossible, but also the processing capability of the wafer is reduced.

Further, when the wafer is transferred to the XYθ driving stage after the completion of the pre-alignment, a constant rotational deviation always occurs. This shift amount is a shift amount generated due to the deformation of the wafer due to the progress of the heat treatment and is stable within the same lot, and is always transferred to the XYθ driving stage with a constant shift amount within the lot. Become. In other words, this means that precision alignment is performed with different offsets for each lot, which is a factor that hinders the stability of alignment accuracy.

An object of the present invention is to solve the above-mentioned problems,
It is an object of the present invention to provide a positioning method and a positioning device capable of performing positioning with high accuracy and high efficiency without limiting a substrate.

[0009]

According to a first aspect of the present invention, there is provided an alignment method for aligning a substrate on a first stage, and then transporting the substrate to a second stage to shift the position. Information is obtained, and the position shift information is taken into account when positioning the next substrate in the first stage.

[0010] In a positioning apparatus according to a second aspect of the present invention, the wafer is pre-aligned on a first stage, and then transferred to a second stage to obtain a correction value relating to a positional deviation. When pre-aligning the wafer, the correction value is taken into account.

According to a third aspect of the present invention, there is provided an alignment apparatus, comprising: a first stage for temporarily aligning a substrate; and a second stage for secondly aligning the substrate from the first stage.
And a means for controlling the first stage and the second stage and obtaining positional displacement information of the substrate in the second stage, and aligning the next substrate in the first stage. In doing so, the position shift information is taken into account.

According to a fourth aspect of the present invention, there is provided an alignment apparatus comprising: a first stage for pre-aligning a wafer; a second stage for aligning the wafer from the first stage; A control operation device for controlling the second stage and calculating a correction value relating to the positional deviation of the wafer in the second stage, wherein the correction value is used when the next wafer is aligned in the first stage. Is added.

The positioning device according to a fifth aspect of the present invention provides
Alternatively, in any of the fourth inventions, the operation range of the second stage is limited.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in FIGS. FIG. 1 is a configuration diagram of, for example, a stepper for manufacturing a semiconductor element. A pre-alignment stage 1 for rotating and preliminarily aligning a wafer W as a semiconductor substrate, and precisely aligning the wafer W by driving the wafer W in XYθ directions. The precision alignment stage 2 is arranged in parallel. Precision alignment stage 2
Above the microscope 3, a position detecting means 4 provided with an observation microscope 3 for detecting the position of the wafer W is provided. On the side of the microscope 3, for example, an electronic circuit pattern of a reticle 5 is reduced and projected on the wafer W. A lens 6 is arranged.

The pre-alignment stage 1, the precision alignment stage 2 and the position detecting means 4
Is electrically connected to the control calculation means 8 having The control calculation means 8 controls the preliminary alignment stage 1 and the precision alignment stage 2 based on the signal detected by the position detection means 4 and calculates a correction value for the positional deviation of the wafer W on the precision alignment stage 2. Then, feedback is provided to the pre-alignment stage 1. Further, the output of the control calculation means 8 is:
Transfer means 9 such as a hand for transferring wafer W from preliminary alignment stage 1 to precision alignment stage 2
It is connected to the.

As shown in the perspective view of FIG. 2, a stage main body 11 is rotatably provided on the precision alignment stage 2, and the upper surface of the stage main body 11 holds a wafer W by suction and performs a focus operation. Chuck 1
2 is provided movably up and down. Further, a wafer receiving chuck 13 is provided on the stage body 11 so as to penetrate the wafer chuck 12. The wafer receiving chuck 13 holds the wafer W by suction, and is fixed to the stage main body 11 without a driving system, thereby achieving simplification and weight reduction.

Although not shown, transfer means such as a hand for transferring the wafer W from the carrier to the preliminary alignment stage 1, driving means for driving the preliminary alignment stage 1, and driving of the precision alignment stage 2 A bar mirror used for control, a vacuum means for applying a suction force to the wafer chuck 12 and the wafer receiving chuck 13, a vertical movement means for driving the wafer chuck 12 in the vertical direction, and the like are provided. Upon detection, the stage main body 11 and the wafer chuck 12 are driven integrally in the θ direction.

FIG. 3 is a flowchart of the wafer processing step. In step S11, the wafer W is transferred from the carrier to the pre-alignment stage 1. Step S1
In 2, it is determined whether or not the wafer W is the second wafer or later.
If the wafer W is the second wafer or later, the process proceeds to step S13. If the wafer W is the first wafer, the process proceeds to step S14 without going through step S13. In step S14, a linear orientation flat or a fan-shaped notch provided in advance on the wafer W is detected, and the preliminary alignment stage 1 is rotated to preliminarily align the wafer W at a predetermined position.

In step 15, the pre-aligned wafer W is transferred from the pre-alignment stage 1 to the precision alignment stage 2. At this time, the wafer chuck 12 is driven downward, and the wafer receiving chuck 13 is driven.
Is positioned higher than the wafer chuck 12. Next, after the wafer W is received from the transfer means 9 by the wafer receiving chuck 13, the transfer means 9 is retracted. And
The wafer chuck 12 is driven upward to transfer the wafer W from the wafer receiving chuck 13 to the wafer chuck 12.

With the wafer W held by the wafer chuck 12, the precision alignment stage 2 is driven so that a target provided in advance on the wafer W is positioned within the observation field of the microscope 3. Next, the displacement of the target of the wafer W is measured through the microscope 3, and the stage main body 11 and the wafer chuck 12 are integrally rotated and driven in the θ direction to precisely align the wafer W. Then, the θ drive amount is stored in the control calculation means 9.

On the other hand, in step 13, the first wafer W
Is set, and in step 14, the second and subsequent wafers W are pre-aligned, taking into account the θ drive amount set in step S13, to the rotational position detected from the orientation flat or the notch. And step S
At 15, the wafer W is precisely aligned as described above.

In step 14, step 1
The θ drive amount of the first wafer W obtained in step 3 is given as an offset for preliminary alignment, and then the second and subsequent wafers W are pre-aligned using an orientation flat or a notch. May be employed.

In step S16, the precision alignment stage 2 is driven below the reduction projection lens 6 to transfer the electronic circuit pattern of the reticle 5 onto the wafer W. In step S17, it is determined whether all the specified wafers W have been processed. If not all the wafers W have been processed, the process returns to step S11. If all the wafers W have been processed, the processing of the wafer W is performed. finish.

In order to process wafers W in parallel,
As shown by arrow C2, in step S15, when the previous wafer W has been processed, the processing of the next wafer W is started. When the previous wafer W has been processed in step S16, the processing of the next wafer W in step S14 ends.

In general, the amount of rotation of the electronic circuit pattern on the wafer W has the same tendency in the same lot, and the variation in the amount of rotation of the electronic circuit pattern in the lot is small. When the θ drive amount is taken into account during the alignment, the rotation amount of the precision alignment stage 2 can be reduced even when the rotation amount of the electronic circuit pattern is large.

Further, since the amount of rotation deviation generated for each lot due to the deformation of the wafer is added to the θ drive amount at the time of preliminary alignment as described in the embodiment, the alignment accuracy within the lot is reduced. Variation can be suppressed.

[0027]

As described above, the positioning method and the positioning apparatus according to the present invention take into account the correction value relating to the displacement in the second stage when the next substrate is positioned in the first stage. Therefore, even when the amount of rotation of the pattern on the substrate is large, the amount of rotation of the second stage can be reduced, and positioning can be performed with high accuracy and high efficiency without limiting the substrate.

Further, the alignment can be performed with high efficiency.
Eliminating variations in alignment accuracy between lots, it is possible to always achieve stable and accurate alignment.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a stepper.

FIG. 2 is a perspective view of a precision alignment stage.

FIG. 3 is a flowchart of a wafer processing step.

FIG. 4 is a flowchart of a conventional wafer processing step.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Preliminary alignment stage 2 Precision alignment stage 3 Microscope 4 Position detection means 5 Reticle 6 Reduction projection lens 7 Monitor 8 Control calculation means 9 Transport means W Wafer

Claims (5)

[Claims] Claims: 1. A substrate is positioned on a first stage,
Thereafter, the substrate is conveyed to a second stage to obtain positional deviation information, and the positional deviation information is taken into account when positioning the next substrate in the first stage. 2. A pre-alignment of a wafer on a first stage, and thereafter, a transfer to a second stage to obtain a correction value relating to a positional shift, wherein the pre-alignment of a next wafer in the first stage is performed. A positioning device characterized by taking into account a correction value. 3. A first stage for temporarily aligning the substrate, a second stage for secondly aligning the substrate from the first stage, the first stage and the second stage. Means for controlling the stage and obtaining positional deviation information of the substrate in the second stage, and taking into account the positional deviation information when positioning the next substrate in the first stage. Characteristic alignment device. 4. A first stage for pre-aligning a wafer, a second stage for aligning the wafer from the first stage, and controlling the first and second stages and controlling the first and second stages. A control operation device for calculating a correction value relating to the positional deviation of the wafer in the second stage, wherein the correction value is taken into account when aligning the next wafer in the first stage. Matching device. 5. The positioning apparatus according to claim 3, wherein an operation range of the second stage is limited.