JPH10335232A - Alignment device and method, and exposure system provided therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable an alignment operation to be accurately carried out even in a vibrational environment even if a laser emits a laser beam for a short time by a method wherein the positional deviation of two objects from each other and data related to the relative movement of them are measured on the same timing, and an instruction generated basing on a measurement result is corrected basing on vibration data as to a moving means. SOLUTION: The position of a stage is measured with a laser interference length measuring equipment 10 or the like, and a relative positional deviation of a mask 4 and a wafer 6 from each other is measured with an alignment detector 2. At this point, an alignment measurement is carried out at timing within a stage position measurement time, and the position of the stage is measured on the same timing with the alignment measurement. Then, an operation instruction given to the stage is calculated basing on a difference between a deviation detection value obtained through an alignment measurement and a stage position measurement value obtained then. At this time, when a difference between the vibration center of the stage and an instruction exceeds a tolerance, a wafer stage is moved basing on the difference.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for exposing and transferring a fine electronic circuit pattern formed on a mask onto a wafer, for example, in an exposure apparatus for manufacturing semiconductor devices.
The present invention relates to a technique for performing relative positioning between a mask and a wafer with high accuracy.

[0002]

2. Description of the Related Art In an exposure apparatus for manufacturing a semiconductor device such as an integrated circuit or a liquid crystal panel, when a fine circuit pattern formed on an original (a mask or a reticle) is exposed and transferred onto a wafer, the original and the wafer are transferred. Is important for high integration of semiconductor devices. Particularly in recent exposure apparatuses, alignment accuracy of, for example, submicron or less is required.

In the alignment method, generally, alignment marks are arranged on an original and a wafer, respectively, and relative alignment is obtained by obtaining mutual positional deviation information by utilizing the optical properties.

[0004]

Generally, in an exposure apparatus, the entire exposure apparatus is installed on a table having a vibration isolation function in order to prevent vibration from being transmitted to a wafer stage on which a wafer is mounted. . However, perfect vibration removal is difficult, and the wafer may be slightly displaced by the influence of vibration from the outside of the exposure apparatus or vibration of a motor of a stage driving system. This kind of vibration is frequency
In some cases, a frequency range equivalent to the emission time of laser light for alignment may be reached. Sometimes 50n amplitude
In some cases, a vibration amplitude such as m, which is on par with the allowable accuracy of the alignment, may occur. In order to realize high precision of the exposure apparatus, a countermeasure against this vibration is a problem.

In order to solve the above-mentioned problem, Japanese Patent Application Laid-Open No. 6-36990 has already disclosed that a deviation detection value of the alignment detecting means and a stage position measured value of the stage measuring means are obtained at the same timing as shown in FIG. It is proposed that (operation command value to the stage) = (stage position measurement value) − (displacement detection value).

However, according to this conventional method, if the laser emission time is short with respect to the vibration of the stage, or if the stage itself vibrates at a low frequency, FIG.
Assuming that the command value of the stage does not match the center of the stage vibration as shown in FIG. 2 and the alignment measurement is performed in a short time near the peak of the stage vibration, (stage position measurement value) = ( Since (command value) and (alignment deviation detection value) = 0, (operation command value for stage) = (stage position measurement value) − (displacement detection value)
= (Command value), and the stage is not driven even though the stage position is deviated from the target position (center of vibration).

More specifically, in the conventional method, "a case where the center of vibration matches the command value" as shown in FIG.
It cannot be practically distinguished from "when the vibration center and the command value do not match" as described above, so that the relationship between the command value and the vibration center of the stage cannot be guaranteed.

Here, assuming that the wafer side is aligned with the mask on behalf of the center of the stage vibration at the time of exposure, in the conventional method, a positioning error corresponding to the vibration amplitude of the stage at most depends on the positioning state of the stage. There is a problem that there is a possibility of having

The present invention has been made in view of the above-described problems of the prior art, and has as its object to provide an apparatus and a method capable of performing high-accuracy alignment even in a case where a laser emission time is short in an environment having minute vibration. And It is another object of the present invention to provide an exposure apparatus and a semiconductor device manufacturing method using the apparatus and the method.

[0010]

In order to achieve the above object, the present invention provides a method for moving a first object and a second object relative to each other, and moving the second object relative to the first object. When the movement information of the means is measured at the same timing, a command value is created based on those measured values, and when the moving means is operated, vibration information of the moving means is further detected, and based on the vibration information, The command value is corrected.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An apparatus according to one embodiment of the present invention includes an alignment detecting means for detecting a relative displacement between a first object and a second object, and the alignment detecting means for the first object. A moving unit for relatively moving the second object, a measuring unit for measuring movement information of the moving unit, and a vibration center of the second object is detected in advance, and the measurement at the alignment measurement value and the alignment detection timing is performed. Means for correcting a command value to the moving means obtained based on a measurement value of the means by a deviation from the center of vibration.

[0012]

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

Here, an embodiment in which the present invention is applied to a proximity type X-ray exposure apparatus will be described. The form of the exposure apparatus is not limited to this, and the present invention is also applicable to a reduced exposure type X-ray exposure apparatus and a projection exposure apparatus using i-ray, excimer light, or the like. First Embodiment FIGS. 1 and 2 are block diagrams of an X-ray exposure apparatus according to one embodiment of the present invention. FIG. 1 is a side view and FIG. 2 is a plan view.

In FIG. 1, reference numeral 1 denotes a controller having a computer control function, which controls the entire system. Reference numeral 2 denotes an alignment detector for detecting a relative positional shift between the mask and the wafer, which includes a light source (for example, a semiconductor laser or an LED), a light-receiving sensor (for example, an array sensor such as a CCD) and the like. 3 is a mask chuck, 4 is a mask on which a circuit pattern of a semiconductor device is formed, 5 is an alignment pattern provided on the mask 4, 6 is a semiconductor wafer, 7 is an alignment pattern provided on the wafer 6, Reference numeral 8 denotes a wafer chuck for holding the wafer 6. 9 is a reflecting mirror, 10 is a unit (laser interferometer) including a laser light source and a photodetector of a laser interferometer, 11 is an optical unit of the interferometer, and 12 is a table on which the units 10 and 11 are mounted. , These members 9, 1
The laser interferometer for measuring the position of the stage is constituted by 0, 11, and 12. 13 and 14 are stage mechanisms for mounting the wafer chuck 8 and moving the wafer chuck 8 relative to the mask chuck 3, and 15 is a drive mechanism for moving the stage. Reference numeral 16 denotes an X-ray irradiation system including an X-ray source for generating X-rays as exposure energy.

Next, the operation of positioning the mask and the wafer in the above configuration will be described. FIG. 3 is a flowchart showing a sequence of alignment between the mask and the wafer. First, the mask 4 is set on the mask chuck 3 (Step 101), and the wafer 6 is set on the wafer chuck 8 (Step 102). Next, rough alignment (pre-alignment) of the set mask 4 and wafer 6 is performed (step 103). After the pre-alignment, the positions of the stages 13 and 14 are measured by the laser interferometer 10 and the like, and the relative displacement between the mask 4 and the wafer 6 is measured by the alignment detector 2 (step 1).
04).

FIGS. 4 and 5 show signals at that time. The laser interferometer 10 is used within the measuring time of the stage position.
, The stage position is measured, the alignment measurement is performed at a timing included in the stage position measurement time, and the stage position measurement is performed at the same timing as the alignment measurement.
Specifically, the stage position read signal (STGFL
G), the stage position capture time (STGt
im) is calculated in advance from the natural frequency of the stage (for example, a fixed value of 40 msec).

On the other hand, the cycle (CHGt) of the accumulation time of the sensor (here, CCD) of the alignment detector 2
ime) is set to, for example, 25 msec within a range in which the sensor does not saturate in consideration of the light source intensity and the like, and the light emission time (LDtime) of the light source is controlled in synchronization with the cycle of the accumulation time. The LDtime is specifically set at 0. 0 in consideration of the influence of the process on the wafer side, the transmittance of the alignment mark, the reflectance, and the like. It is set within the range of lmsec to 20 msec.

The sequence proceeds to step 104, and when the command REQ is turned on, stage position reading is started in the cycle of the next accumulation time. In the figure, signal A
Is a counter clock obtained by the logical sum of the sample clock corresponding to the reading cycle of the signal of the laser interferometer 10 and STGFLG.
The count value increases by the time set by the FLG, a write signal is issued to the memory at the same time, and the output value of the laser interferometer 10 is sequentially stored from the address 0 of the memory. Then, after the elapse of STGtime, data values stored from address 0 to the address of the count value are read, an average value thereof is calculated, and the average value is set as the vibration center of the stage (step 105).

The alignment measurement signal (AAFL)
G) starts light emission of the light source from the CCD accumulation cycle two cycles ahead when the command REQ is turned ON (AAFLG is O
N, at time T1), and turn off (time T2) after emitting light for the time of LDtime. The count value C1 at the time T1 and the count value C2 at the time T2 are stored in a memory, and after the lapse of LDtime, the count value C
An average value is calculated from the data stored from the address of 1 to the address of the count value C2, and is set as the stage position measurement value at the same timing as the alignment measurement.

Here, the stage position measurement time (STGt)
In the standpoint of measuring the timing of the start of the image (im) so that the timing of the measurement time of the stage and the timing of the alignment measurement do not shift as much as possible, in FIG.

[0021]

(Equation 1) Is calculated in advance, the time corresponding to B (= CHGtime-Delay) in the figure is loaded to the counter from the next cycle in which the REQ is turned on, and the position measurement of the stage is started after counting. As a result, the alignment measurement is performed just near the center of the measurement time of the stage, and more accurate measurement can be performed.

Next, in step 106 of FIG. 3, an operation command value to the stage is calculated from a difference between a deviation detection value by alignment measurement and a stage position measurement value at that time.

As shown in FIG. 4, when the deviation detected by the alignment measurement is α, the difference between the measured position of the stage and the vibration center at that time is γ, and the difference between the command value and the vibration center is β, β is It is calculated from the difference between the measured vibration center and the command value, and the stage is positioned by the following equation.

[0024]

(Equation 2) As described above, when the command value matches the center of vibration, the positioning drive of the stage is completed.

Next, in step 107 of FIG. 3, it is determined whether or not the difference (the above β) between the center of vibration of the stage and the command value is within an allowable value. If the result of the determination is that the value exceeds the allowable value, the wafer stage is driven by this β (step 108) and the process returns to step 104. If the result of the determination in step 107 is within the allowable value (for example, 20 nm or less), the operation proceeds to the exposure operation (step 109). In the exposure operation, the mask is irradiated with X-rays generated from the X-ray irradiation system, and the circuit pattern on the mask is exposed and transferred to the wafer.

In a conventional step-and-repeat type exposure apparatus, after stage movement or step movement after pre-alignment, alignment and exposure are performed after the stage vibration is stabilized to the extent necessary for exposure. . The detection of the stabilization is performed, for example, by confirming that the vibration amplitude of the stage has become equal to or less than a predetermined value based on a signal of the laser interferometer 10.

In the apparatus shown in FIG. 1, the alignment can be detected at the time of one or more stabilization checks for detecting the stabilization of the stage. As shown in FIG. 6, even when the alignment detection is performed before stabilization, the accuracy of the alignment detection value is equal to or smaller than that of the conventional example because the stage vibration is corrected as described above. improves. Moreover, since the alignment can be detected without waiting for the stabilization of the stage, the throughput is improved.

In the above embodiment, an example in one axis direction is shown for simplicity of explanation. However, in practice, a similar configuration is provided in both xy directions, and alignment is performed in two axes xy. Done. In addition, the alignment method described above includes
The present invention can be applied not only to the xy directions but also to the alignment in the space direction (z direction) between the mask and the wafer.

Second Embodiment Next, another embodiment of the signal processing system will be described with reference to FIGS.
This will be described with reference to FIG. FIG. 7 is a block diagram of a signal processing system according to the second embodiment, and FIG. 8 is a flowchart showing a processing sequence. In FIG. 7, the computer 62 can read a measurement value of the laser interferometer 10, a stage position readout signal (STGFLG), and an alignment measurement signal (AAFLG) via an interface (I / F) circuit 61. . The computer 62 executes the laser interferometer 1 according to the procedure shown in the flowchart of FIG.
The signal of 0 is read out to the array M [i] during the time when the signal STGFLG is ON, and for the time when AAFLG is ON, the measurement start sample value j1 and the measurement end sample value j2 are stored, and after the measurement is completed. The average of the read N1 samples is determined, and the average is used as the center of the stage vibration. The average of the N2 samples from samples j1 to j2 is determined, and the average of the stage position measurement values at the same timing as the alignment measurement is obtained. And

[0030]

Next, an embodiment of a device manufacturing method using the above-described exposure apparatus will be described. FIG. 9 shows a flow of manufacturing micro devices (semiconductor chips such as ICs and LSIs, liquid crystal panels, CCDs, thin-film magnetic heads, micromachines, etc.). Step 1 (circuit design)
Now, the circuit design of the semiconductor device will be performed. Step 2
(Mask production) produces a mask on which the designed circuit pattern is formed. On the other hand, in step 3 (wafer manufacturing), a wafer is manufactured using a material such as silicon. Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the prepared mask and wafer. Next, Step 5 (assembly) is called a post-process, and is a process of forming a semiconductor chip using the wafer produced in Step 4, and includes processes such as an assembly process (dicing and bonding) and a packaging process (chip encapsulation). including. Step 6
In (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device manufactured in step 5 are performed. Through these steps, a semiconductor device is completed and shipped (step 7).

FIG. 10 shows a detailed flow of the wafer process. Step 11 (oxidation) oxidizes the wafer's surface. Step 12 (CVD) forms an insulating film on the wafer surface. Step 13 (electrode formation) forms electrodes on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted into the wafer. Step 1
In 5 (resist processing), a photosensitive agent is applied to the wafer. Step 16 (exposure) uses the above-described exposure apparatus to print and expose the circuit pattern of the mask onto the wafer. Step 17 (development) develops the exposed wafer. In step 18 (etching), portions other than the developed resist image are removed. In step 19 (resist stripping), unnecessary resist after etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer.

By using the manufacturing method of this embodiment, it is possible to manufacture a highly integrated semiconductor device which has conventionally been difficult to manufacture.

[0033]

According to the present invention, even when the wafer or the wafer stage has vibration, high-precision alignment can be performed without being affected by the vibration. If the present invention is applied to an exposure apparatus or semiconductor device manufacturing, a highly accurate semiconductor device can be manufactured.

In particular, like global alignment,
When the alignment with the center of vibration of the stage is required in a single alignment without the drive-in operation or the like, the use of the present invention makes it possible to correct the stage vibration, so that high-precision exposure is possible.

Further, if the present invention is applied and the alignment measurement is performed in the stabilization check before the stage is settled, the target value of the stage can be obtained within the stage settling time, thereby improving the throughput. Connect.

[Brief description of the drawings]

FIG. 1 is a side view showing a configuration of an exposure apparatus according to a first embodiment of the present invention.

FIG. 2 is a plan view of the apparatus of FIG.

FIG. 3 is a flowchart showing an operation sequence of the apparatus shown in FIG. 1;

FIG. 4 is a diagram showing alignment detection and stage position detection in the apparatus of FIG.

FIG. 5 is a diagram showing detection timings of an alignment detector and a laser interferometer in the apparatus of FIG.

FIG. 6 is a diagram showing timings of stage setting and alignment measurement in a modification of the first embodiment of the present invention.

FIG. 7 is a block diagram of a signal processing system according to a second embodiment of the present invention.

8 is a diagram showing a processing sequence of the signal processing system of FIG.

FIG. 9 is a diagram showing a flow of manufacturing a semiconductor device.

FIG. 10 is a diagram showing a detailed flow of a wafer process in FIG. 9;

FIG. 11 is a diagram showing alignment detection and stage position detection in a conventional example.

FIG. 12 is a diagram showing alignment detection and stage position detection in a conventional example.

[Explanation of symbols]

1: controller, 2: alignment detector, 3: mask chuck, 4: mask, 5: alignment pattern,
6: wafer, 7: alignment pattern, 8: wafer chuck, 9: mirror, 10: laser interferometer, 11,
12: Units other than the laser interferometer constituting the laser interferometer, 13, 14: stage mechanism, 15: drive mechanism, 61: I / F circuit, 62: computer.

Claims (8)

[Claims] An alignment detecting unit that detects a relative displacement between a first object and a second object; a moving unit that relatively moves the second object with respect to the first object; and a movement of the moving unit. Measuring means for measuring information; vibration detecting means for detecting vibration information of the moving means; detection values of the alignment detecting means obtained by synchronizing the alignment detecting means and the measuring means; timing of the alignment detection A means for operating the moving means based on the measurement value of the measuring means and the vibration information. 2. The method according to claim 1, wherein the measuring unit performs the measurement at a period shorter than a detection period of the alignment detecting unit, and the vibration detecting unit performs the measurement based on a plurality of measurement values sequentially output from the measuring unit. The means for detecting the vibration information including the vibration center information and operating the moving means is a movement command value to the moving means obtained based on the alignment detection value and the measurement value of the measuring means at the alignment detection timing. 2. The positioning apparatus according to claim 1, wherein the moving means is operated based on a value corrected by a deviation from a vibration center of the moving means at the alignment detection timing. 3. A first step of detecting a relative displacement between a first object and a second object, a second step of measuring position information of the second object, and a plurality of measurements in the second step Value based on the second
A third step of detecting vibration information of the object, the second object based on the detection value in the first step, the measurement value in the second step at the timing when the detection value is obtained, and the vibration information Calculating a positional shift of the first object with respect to the vibration center of the object, and adjusting a positional relationship between the first object and the second object based on the calculated value. . 4. An aligning means for aligning an original on which an exposure pattern is formed with an object to be exposed, and an exposure pattern of the original on an object to be exposed when the original and the object to be exposed are aligned. Transfer means for exposing and transferring, the alignment means, alignment detecting means for detecting a relative displacement between the original and the object to be exposed, and movement for relatively moving the object to be exposed with respect to the original. Means, measuring means for measuring movement information of the moving means, vibration information detecting means for detecting vibration information of the moving means, and the alignment detecting means obtained by synchronizing the alignment detecting means and the measuring means Means for operating the moving means based on the detected value, the measured value of the measuring means at the timing of the alignment detection, and the vibration information. Exposure apparatus according to symptoms. 5. The measuring means performs the measurement in a cycle shorter than a detection cycle of the alignment detecting means, and the vibration detecting means detects the vibration of the moving means based on a plurality of measurement values sequentially output from the measuring means. The means for detecting the vibration information including the vibration center information and operating the moving means outputs a movement command value to the moving means obtained based on the alignment detection value and the measurement value of the measuring means at the alignment detection timing. 5. The exposure apparatus according to claim 4, wherein the moving unit is operated based on a value corrected by a deviation from a vibration center of the moving unit at the alignment detection timing. 6. The positioning device according to claim 4, wherein the positioning device executes the positioning even before the vibration of the moving device is settled below the amplitude required for the exposure transfer. Exposure equipment. 7. An alignment step for aligning an original on which a circuit pattern is formed with a wafer, and a transfer step for exposing and transferring a circuit pattern of the original onto the wafer in the state where the alignment has been performed. The positioning step includes: a first step of detecting a relative displacement between the original plate and the wafer; a second step of measuring position information of the wafer; and a plurality of measurement values in the second step. A third step of detecting vibration information of the wafer by using the detection value in the first step, the measurement value in the second step at the timing when the detection value is obtained, and the vibration information. Calculating a positional shift of the original with respect to the vibration center of the above, and adjusting a positional relationship between the original and the wafer based on the calculated value. A method for manufacturing a semiconductor device. 8. A semiconductor device manufactured by the method of claim 7.