JP3372633B2 - Positioning method and positioning apparatus using the same - Google Patents

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 using the same, and more particularly to a mask or reticle (hereinafter referred to as "mask") in an exposure apparatus for manufacturing a semiconductor element.
Say. ) Is suitable for accurately aligning the wafer to a predetermined position on the XY stage when the electronic circuit pattern formed on the surface is transferred onto the wafer surface.

[0002]

2. Description of the Related Art Conventionally, in an exposure apparatus such as a stepper for manufacturing semiconductor devices, relative alignment between a mask and a wafer has been an important factor for manufacturing highly integrated semiconductor devices.

In aligning the mask and the wafer at this time, first, pre-alignment is performed to precisely align the wafer with a predetermined position on a PA (pre-alignment) stage.

FIG. 5 is a schematic view of a main part of a conventional wafer alignment mechanism for pre-aligning a wafer in an exposure apparatus for manufacturing a semiconductor device.

In the process of processing a semiconductor wafer (hereinafter simply referred to as "wafer") in the manufacture of semiconductor devices, an electronic circuit pattern is exposed and baked on the wafer.
In order to perform this exposure process, the wafer is automatically transferred to the XY stage 6 under the microscope, and the target provided on the wafer is used to align the wafer and the mask.

Generally, prior to the alignment at this time, as shown in FIG. 5, the wafer 1 is once transferred from the carrier 2 to the PA stage 4 by the transfer hand 3, and the wafer 1 is rotated by the PA (pre-alignment) stage 4. The so-called pre-alignment is performed in which the position is adjusted to a predetermined position.

After the pre-alignment of the wafer 1, the feeding hand 5 is used again to move the XY stage 6 under the microscope.
It adopts a two-stage mechanism that conveys to a predetermined position. The pre-alignment at this time is performed using a linearly cut orientation flat (identification surface) 10 provided in advance on a part of the wafer 1. That is, the wafer 1 is rotated by the non-contact rotation unit 8, the identification surface 10 is recognized by the sensor 7, the position in the rotation direction is aligned, and the pressing mechanism 9 performs the pre-alignment operation.

When the pre-alignment operation is completed, the wafer 1 is transferred onto the XY stage 6 by the feeding hand 5, and the wafer chuck (not shown) on the XY stage 6 is carried out.
After that, vacuum suction is performed to correct the surface, and the subsequent wafer process is performed.

Generally, the position reproducibility of pre-alignment is high, and there is no problem when all the steps for wafer processing are processed by the same apparatus.

However, since the mounting positions of the sensor 7 and the pressing mechanism 9 which are the reference of the pre-alignment are different between the respective devices, the alignment of the wafer with respect to the wafer chuck varies among the respective devices.

On the other hand, when a semiconductor element is manufactured through various semiconductor manufacturing processes using a plurality of devices, it is unlikely that the device that processed the previous process and the device that processes the next process are the same.

As a result, when the wafer on the wafer chuck and the mask are precisely aligned after the completion of pre-alignment, the position detection target provided on the wafer surface may not fall within the visual field range of the microscope for target detection. is there.

FIGS. 6A and 6B are explanatory views of a target for position detection printed on the wafer surface by the exposure apparatus.

FIG. 6A shows a wafer 2 in the conventional exposure apparatus A.
The target 18 for position detection and the visual field 17 of the microscope for position detection printed on one surface are shown.

FIG. 6B shows a position detection target 18 and a position detection microscope field 17 printed on the surface of the wafer 22 by an exposure apparatus B different from the conventional exposure apparatus A.

As shown in FIG. 6B, the exposure position of the position detection target 18 is largely deviated between the exposure apparatus A and the exposure apparatus B, and the wafer 22 baked by the exposure apparatus B is aligned by the exposure apparatus A. Then, the position detection target 18 may not enter the visual field 17 of the microscope. At this time, a step of searching for a position detection target is added.

In general, adding such a step delays the alignment time, deteriorates the wafer processing efficiency, and causes a problem in calculating the production plan. Therefore, conventionally, it has been necessary to finely adjust the mounting positions of the sensor 7 and the pressing mechanism 9 for all the devices. For the variations that cannot be absorbed by the above adjustment, the correction amount is calculated based on the alignment data of the several alignment seeking steps for the wafer transferred onto the wafer chuck, and for the wafer transferred onto the subsequent wafer chuck, The alignment was performed by feeding the XY stage with a correction value added to the feed amount.

[0018]

In the conventional alignment method, a great amount of labor is required for fine adjustment of the mounting position of the pre-alignment mechanism, and the movement of the XY stage for searching for alignment and correcting the feed amount is increased. Throughput tended to decrease.

Further, the conventional method of correcting the feed amount of the XY stage is to correct the position detection target that is first printed on the wafer, and to correct the variation of the position of the wafer with respect to the wafer chuck between the devices. Was not considered.

On the other hand, in the exposure apparatus for manufacturing semiconductor elements,
Since the deformation of the wafer itself progresses as the exposure process progresses, the wafer is flattened by vacuum suction by the wafer chuck.

However, in the conventional alignment method, since the position of the wafer with respect to the wafer chuck differs from device to device, the correction state of the wafer differs from device to device, greatly affecting the chip position and shape on the wafer.

As a result, there is a problem in that a baseline correction time at the time of alignment, a time loss such as an alignment search, and the like occur.

According to the present invention, as a result of undergoing a plurality of exposure steps, even a deformed wafer can be sent to a predetermined position on the wafer chuck with good reproducibility, and alignment can be performed with high accuracy, and high throughput can be easily achieved. An object of the present invention is to provide an obtained alignment method and an alignment device using the same.

[0024]

(1-1) In the alignment method of the present invention, a reference sample is conveyed onto a first stage, and pre-alignment is performed with respect to a pre-alignment reference on the first stage. After that, the amount of deviation of the target provided on the reference sample from the predetermined position on the second stage is detected by detecting the deviation amount from the predetermined position, and based on the detection result, the pre-alignment different for each alignment device It is characterized in that a correction value relating to the reference mounting position is calculated, and the position of the sample to be aligned on the first stage and / or the second stage is aligned based on the calculation result.

(1-2) The alignment device of the present invention fixes the transported reference sample on the first stage for pre-alignment with respect to the pre-alignment reference, and fixes the reference sample transported from the first stage. A second stage movable within a certain range, a detection unit that detects a deviation amount of a target provided on the reference sample from a predetermined position, and a pre-position that differs for each alignment device based on a detection result by the detection unit. A calculation means for calculating a correction value relating to the attachment position of the alignment reference, and adjusting the position of the sample to be aligned on the first stage and / or the second stage based on the calculation result by the calculation means. Is characterized by.

(1-3) In the method of manufacturing a semiconductor device according to the present invention, the pattern on the mask surface is exposed and transferred onto the wafer surface, and then, when the semiconductor device is manufactured through a developing process, the standard is used. The wafer is transferred onto the first stage and the first
After performing pre-alignment with respect to the pre-alignment reference on the stage, the pre-alignment is carried to the second stage and the deviation amount of the target provided on the reference wafer from the predetermined position is detected on the second stage, and the detection result is obtained. Of the wafer to be aligned on the first stage and / or the second stage based on the calculation result of the correction value relating to the mounting position of the pre-alignment reference which is different for each alignment device. It is characterized by matching the positions.

(1-4) The exposure apparatus of the present invention is an exposure apparatus for exposing and transferring a pattern on a reticle surface onto a wafer surface, and a first stage for pre-aligning a conveyed wafer with respect to a pre-alignment reference. A second stage that fixes the wafer transferred from the first stage and is movable within a certain range; a detection unit that detects a deviation amount of a target provided on the wafer from a predetermined position; and a detection unit that detects the detection amount. Calculating means for calculating a correction value for the mounting position of the pre-alignment reference, which is different for each alignment device, based on the result, and the first stage and / or the second stage based on the calculation result of the calculating means. The feature is that the position of the wafer to be aligned on the stage is aligned. Especially (1-4-1) the pre-alignment reference of the first stage is a sensor and a pressing mechanism. (1-4-2) The correction value has an X component, a Y component, and a θ component, and the X component and the Y component of the correction value are added to the second stage to obtain the θ component of the correction value. Is to be added to the first stage. Is characterized by.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view of a main part of a first embodiment of the present invention, and FIGS. 2 and 3 are flow charts of a correction value measuring operation and an exposure operation in a positioning method of the first embodiment of the present invention.

In this embodiment, the case where the wafer is aligned at a predetermined position and applied to an exposure apparatus for manufacturing a semiconductor element for exposing and transferring the pattern on the mask surface is shown.

In this embodiment, the wafers 1 accommodated in the carrier 2 are transferred to the PA stage 4 one by one by the transfer hand 3. In this PA stage 4, a linear orientation flat 1 in which the wafer 1 is provided on the periphery thereof is provided.
Positioning (pre-alignment) is performed by the pressing mechanism 9 bent at a right angle to the detection by the sensor 7 of 0.

That is, the wafer 1 is rotated by the non-contact rotation unit 8, the identification surface 10 is recognized by the sensor 7, the position in the rotation direction is aligned, and the pressing mechanism 9 performs pre-alignment.

In this embodiment, each element 4, 7, 8, 9 is the first
It forms part of the stage.

Next, the pre-aligned wafer 1 is transferred to the XY stage 6 by the feeding hand 5. At this time, the XY stage 6 is driven to the wafer 1 receiving position. Then, the wafer 1 transferred onto the XY stage 6 is detected by the microscope 13 as a detection unit for detecting the target, and the target on the wafer 1 is detected.
1 and the Y drive motor 12 are used for precise alignment.

In this embodiment, each element 6, 11, 12 is the second
It forms part of the stage.

Next, the correction value measuring operation in the alignment method of this embodiment will be described with reference to the flow chart of FIG.

Here, a correction value measuring operation for one wafer containing a target for alignment (this wafer will be referred to as a reference wafer) will be described.

First, in step S1, the operator specifies the number of times of measurement with the operation terminal 15 and activates the measurement operation. When the measurement is started, first, the reference wafer is transferred from the carrier 2 to the PA stage 4 by the transfer hand 3.

Next, in step S2, the reference wafer is set to P
Place on A stage 4. The reference wafer placed on the PA stage 4 is pre-aligned in step S3. After the pre-alignment is completed, the reference wafer is transferred from the PA stage 4 to the XY stage 6 by the feeding hand 5.
Then, in step S4, it is placed on the XY stage 6. In step S5, the reference wafer mounted on the XY stage 6 is measured by the target detecting microscope 13 for the amount of displacement of the target provided on the reference wafer from a predetermined position. The measured data is stored in the control calculation means 14.

Next, it is checked in step S6 whether or not the designated number of times has been measured, and if not completed, the operations from step S2 to step S5 are repeated. If the designated number of times is completed in step S6, the process proceeds to step S7, and the reference wafer is collected from the XY stage 6 and returned to the carrier 2.

Finally, the control calculation means 14 performs statistical / calculation processing on the data of the positional deviation amount measured in step S8, and the correction amount (x) in the X direction (x), the Y direction (y) and the rotation direction (θ). , Y, θ) is calculated, the correction value is displayed on the operation terminal 15, and the correction value measurement operation is completed.

Next, referring to FIG. 3, the correction values (x, y, θ) obtained by the correction value measuring operation based on the flowchart of FIG.
The exposure operation of the flowchart of the exposure operation when the electronic circuit pattern on the mask surface is exposed and transferred onto the wafer surface using will be described.

First, the wafer 1 transferred from the carrier 2 to the PA stage 4 is placed on the PA stage 4 in step SS1. Then, in step SS2, a pre-alignment operation is performed. During the pre-alignment operation, the θ component of the correction value is reflected in the pre-alignment end position.

Next, in step SS3, when the XY stage 6 is driven to the wafer receiving position, the x and y components of the correction value are reflected. Then, in step SS4, the wafer 1 is placed on the XY stage 6.

Next, in step SS5, the position of the target on the wafer 1 is detected by the target detecting microscope 13 and fine alignment is performed. However, the step SS5 is not performed for the wafer on which the target is not baked. Then, the exposure process is performed in step SS6, the wafer 1 is recovered from the XY stage 6 in step SS7, and the wafer 1 is returned to the carrier 2 to complete the entire exposure operation.

In the present invention, the correction values (x, y) are applied to the reference wafer 16 by the measurement operation shown in the flowchart of FIG. 2 using the exposure apparatus A and the exposure apparatus B for manufacturing a semiconductor device having the system shown in FIG. , Θ) is calculated. By performing the exposure operation shown in the flowchart of FIG. 3, the wafer is sent to the same position with respect to the wafer chuck (that is, with respect to the XY stage).

As a result, even when the exposure apparatus A and the exposure apparatus B are used, both the reference wafer 16 on the wafer surface is exposed.
The target can be burned at a position corresponding to the target provided in.

FIG. 4 is an explanatory diagram of a target for position detection printed on the wafer surface by the exposure apparatus according to the present invention.

FIG. 4A is an explanatory diagram of the position detecting target 18 provided on the surface of the reference wafer 16 and the field of view 17 of the position detecting microscope.

FIG. 4B is an explanatory view of the target 18 for position detection provided on the surface of the wafer 19 in the exposure apparatus A and the visual field 17 of the microscope for position detection.

FIG. 4C is an explanatory view of the target 18 for position detection provided on the surface of the wafer 20 in the exposure apparatus B and the visual field 17 of the microscope for position detection.

As described above, according to the present invention, the position of the wafer with respect to the wafer chuck is the same regardless of which exposure apparatus is used, and the pattern can be printed at the same position as the reference wafer. The alignment is performed with high precision.

After the wafer is aligned with the predetermined position of the second stage, the pattern on the mask surface is exposed and transferred through the projection optical system or by the proximity method. Then, the exposed and transferred wafer is subjected to a known developing process to manufacture a semiconductor device.

[0053]

According to the present invention, by setting each element as described above, even a deformed wafer as a result of undergoing a plurality of exposure steps can be reproducibly sent to a predetermined position on the wafer chuck, and a high level can be obtained. It is possible to achieve a positioning method and a positioning device using the same, which can perform accurate positioning and easily obtain high throughput.

In particular, according to the present invention, it is not necessary to finely adjust the mounting position of the pre-alignment mechanism for each exposure apparatus, and since the position of the wafer with respect to the wafer chuck becomes constant, the chip of the exposure apparatus with respect to the wafer is fixed. There is no variation in the printing position, simplification of the search for position adjustment and correction operation, and the effect of improving the alignment efficiency without being affected by the fluctuation of the mark position due to the deformation of the wafer.

[Brief description of drawings]

FIG. 1 is a schematic view of a main part of a first embodiment of the present invention.

FIG. 2 is a flowchart showing a correction value measuring operation of the present invention.

FIG. 3 is a flowchart showing an exposure operation of the exposure apparatus according to the present invention.

FIG. 4 is an explanatory view showing a wafer baked by an exposure apparatus using the present invention.

FIG. 5 is an explanatory diagram showing an outline of a wafer alignment mechanism in a conventional exposure apparatus.

FIG. 6 is an explanatory view showing a wafer baked by a conventional exposure apparatus.

[Explanation of symbols]

1 Wafer 2 Wafer Carrier 3 Transfer Hand 4 PA (Pre-Alignment) Stage 5 Feeding Hand 6 XY Stage 7 Sensor 8 Non-contact Rotating Unit 9 Pushing Mechanism 10 Orientation Flat 11 X Drive Motor 12 Y Drive Motor 13 Target Detection Microscope 14 Control Calculation Means 15 Operation Terminal 16 Reference Wafer 17 Position Detection Microscope Field of View of Device A 18 Position Detection Target 19 Wafer Burned by Device A 20 Wafer Burned by Device B 21 Wafer Burned by Semiconductor Exposure Device A by Conventional Method 22 Wafer baked by semiconductor exposure apparatus B according to conventional method

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-5-283315 (JP, A) JP-A-60-242621 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 21/027 G03F 9/00 G05D 3/12

Claims (6)

(57) [Claims] 1. A reference sample is conveyed onto a first stage, prealigned with respect to a prealignment reference on the first stage, and then conveyed onto a second stage, and the reference is conveyed onto the second stage. Predetermined position of the target provided on the sample
The amount of deviation from the position is detected, and the position is detected based on the detection result.
The pre-alignment reference that is different for each device
Calculate the correction value for the mounting position and use it as the calculation result.
Based on the first stage and / or on the second stage
An alignment method, which comprises aligning the position of a sample to be aligned. 2. Pre-alignment of the transported reference sample
A first stage that performs pre-alignment with respect to a reference, a second stage that fixes the reference sample conveyed from the first stage and is movable within a certain range, and a target provided on the reference sample from a predetermined position. Detecting means for detecting the amount of deviation , alignment based on the detection result by the detecting means
Attaching the pre-alignment reference that is different for each device
And a calculating means for calculating a correction value regarding the position, the calculated
Based on the calculation result by the output means, the first stage or /
And the position of the sample to be aligned on the second stage
Alignment and wherein the keying. 3. When a pattern on a mask surface is exposed and transferred onto a wafer surface and then a semiconductor wafer is manufactured through the developing process, a reference wafer is transferred onto a first stage and the first wafer is transferred to the first stage. A target provided on the reference wafer on the second stage by carrying out pre-alignment with respect to the pre-alignment reference on the stage and then carrying it onto the second stage.
Detecting the amount of deviation from a predetermined position of, based on the detection result
And the pre-alignment that is different for each device to be aligned.
Calculating a correction value regarding the mounting position of the bets reference, the calculation
A method of manufacturing a semiconductor device, characterized in that the position of a wafer to be aligned on the first stage and / or the second stage is aligned based on the result . 4. A exposure apparatus for exposing and transferring a pattern on the reticle plane to the wafer surface, the conveyed wafer flop
A first stage that performs pre-alignment with respect to a realignment reference, a second stage that fixes the wafer transferred from the first stage and is movable within a certain range, and a target provided on the wafer from a predetermined position . A detection unit that detects the amount of deviation , and a position based on the detection result of the detection unit.
The pre-alignment reference that is different for each device
A calculation means for calculating a correction value relating to the mounting position, and a wafer to be aligned on the first stage and / or the second stage based on the calculation result of the calculation means .
An exposure apparatus characterized by aligning positions . 5. The pre-alignment group of the first stage
Quasi is a sensor and a pressing mechanism
The exposure apparatus according to claim 4. 6. The correction value includes an X component, a Y component and a θ component.
And the X and Y components of the correction value are
And the θ component of the correction value is added to the first stage
6. The method according to claim 4 or 5, characterized in that
Exposure equipment.