JP2010283304A - Exposure apparatus, exposure method, and device manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exposure apparatus and an exposure method which improve productivity in semiconductor manufacturing process by preventing positioning errors between exposure apparatus different in positioning references to reduce the down time of errors of pre-alignment. <P>SOLUTION: The exposure apparatus includes a detection part for detecting the outer periphery position of a substrate, a calculation part for calculating data about the outer periphery shape of the substrate on the basis of the output of the detection part, an adjustment part for adjusting the position of the substrate on the basis of the output of the calculation part, and a transporting part for transporting the substrate subjected to position adjustment in the adjustment part onto a stage. The exposure apparatus furthermore includes a mark detection part for detecting the position of a mark formed on the substrate on the stage and a changing part for changing a calculation condition or a calculation method in the calculation part on the basis of the output of the mark detection part. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an exposure apparatus and an exposure method for exposing a circuit pattern of an original to a substrate.

  In a semiconductor manufacturing apparatus, positioning (positioning) of a substrate is performed prior to substrate processing (for example, exposure processing or inspection processing). As one process for this positioning, there is a process called pre-alignment (coarse positioning). In this step, before processing the substrate on the substrate stage, rough alignment (pre-alignment) of the substrate is performed so that the amount of positional deviation of the substrate transported and placed on the substrate stage is within a predetermined range. It is a process to be performed.

  In a semiconductor exposure apparatus, pre-alignment positions a substrate that has not yet been subjected to a lithography process (exposure process), and positions of a pattern to be formed (underlying pattern when the next exposure process is performed) Done to determine. Pre-alignment is also a field of view of a measurement device such as an image processing device that positions a substrate on which a mark for measuring the position of the substrate has already been formed at least once and has a high accuracy required in the exposure step. For pre-positioning to feed in.

Conventionally, in the pre-alignment in Patent Document 1 and Patent Document 2, for example, the following method is employed.
(a) A method of aligning a substrate by pressing a plurality of pins against an end portion (substrate outer periphery) of the substrate placed on the substrate holder.
(b) The output result of the measuring instrument using a substrate moving mechanism that holds and moves the substrate in the surface direction and the rotation direction, and a measuring instrument that measures the position of the substrate end using a linear image sensor or the like. The position of the substrate end is obtained based on Furthermore, the method of moving a board | substrate by a board | substrate movement mechanism so that the position of a board | substrate edge part may become a predetermined position.
(c) Using a substrate moving mechanism that holds and moves the substrate in the surface direction and the rotation direction, and a measuring instrument that measures the position of the edge of the substrate using a linear image sensor or the like, the substrate is moved by the substrate moving mechanism. Measure the position of the substrate edge with a measuring instrument while rotating. Further, a method of obtaining the center position of the substrate and the size of the substrate based on the result and moving the substrate by the substrate moving mechanism based on the information.

Japanese Patent Laid-Open No. 11-16806 JP 2005-101455 A

However, the above-described methods (a) and (b) and the method (c) have different positioning reference positions for positioning the substrate. That is, in the methods (a) and (b) described above, the substrate end is aligned at a predetermined position. In the method (c), the center of the substrate is aligned at a predetermined position.
There is a difference in position between substrates positioned by pre-alignment apparatuses having different positioning references when they are transported and placed on the substrate stage after pre-alignment. When the same substrate is processed in a substrate processing apparatus of an exposure apparatus having pre-alignment apparatuses having different positioning references, the following problems arise.

For example, the substrate processing apparatus A has a pre-alignment apparatus using the method (a), and the substrate processing apparatus B has a pre-alignment apparatus using the method (c). The substrate processing apparatus A transfers (exposes) the pattern to the substrate that has not been exposed, and the substrate processing apparatus B processes the substrate in the next step. In this case, the position of the mark on the substrate differs from the position planned in the substrate processing apparatus B due to the difference in positioning reference between the substrate processing apparatus A and the substrate processing apparatus B.
Therefore, there is a problem that a so-called mix and match cannot be obtained between exposure apparatuses having pre-alignment apparatuses having different positioning references. For this reason, recent exposure apparatuses can be pre-aligned by a plurality of methods among the above three methods so that a mix-and-match between different exposure apparatuses can be achieved, and the pre-alignment method can be switched by setting. Configured as follows.

  However, pre-alignment algorithms are not disclosed between different manufacturers of exposure apparatuses, and each company uses its own pre-alignment method. However, due to the difference in the pre-alignment algorithm, for example, even when the same method (c) is used, the method of obtaining the center of the substrate is greatly different. In other words, when the board outline, orientation flat shape, and notch shape have different levels of variation within the standard, how to find the center of the substrate, especially the detection result of the rotation direction using the orientation flat and notch (hereinafter referred to as the θ direction). Are very different.

  FIG. 7 shows the variation in the result of the pre-alignment of the same method (c) between exposure apparatuses of different manufacturers. The θ direction when the number of wafers is plotted on the horizontal axis and the average value is zero on the vertical axis. The variation θ (μrad) between the substrates is shown. In FIG. 7, since a variation of 500 μrad or more is shown, even when the distance between the marks on the substrate is 200 mm when performing measurement for more accurate positioning by image processing or the like, the position is displaced by this θ-direction deviation. Deviates by more than 100 μm. In general, since the field of view of the high-precision positioning of the exposure apparatus is narrower than 100 μm, the mark on the substrate is likely to be out of the measurement field of view, resulting in a prealignment error, the process is stopped, or the process of searching for the mark is entered. Significantly hinders productivity.

  Accordingly, the present invention provides an exposure apparatus and an exposure method that prevent positioning errors between exposure apparatuses having different positioning standards, reduce downtime due to pre-alignment errors, and improve productivity in a semiconductor manufacturing process. For the purpose.

An exposure apparatus of the present invention for solving the above problems includes a detection unit that detects an outer peripheral position of a substrate, a calculation unit that calculates data on the outer peripheral shape of the substrate based on an output of the detection unit, and the calculation unit In an exposure apparatus comprising: an adjustment unit that adjusts the position of the substrate based on the output of; and a transport unit that transports the substrate whose position is adjusted by the adjustment unit onto a stage.
A mark detection unit that detects a position of a mark formed on the substrate on the stage; and a change unit that changes a calculation condition or a calculation method of the calculation unit based on an output of the mark detection unit. Features.
Further, the exposure apparatus of the present invention includes a calculation unit that calculates a position in the rotation direction in the plane of the substrate, an adjustment unit that adjusts a position in the rotation direction of the substrate based on an output of the calculation unit, and the adjustment unit. In an exposure apparatus comprising a transport unit that transports the substrate, the position of which has been adjusted, on a stage, a mark detection unit that detects a position of a mark formed on the substrate on the stage, and an output of the mark detection unit And a changing unit that changes a calculation condition or a calculation method of the calculation unit.

Furthermore, the exposure method of the present invention includes a step of calculating data related to the outer peripheral shape of the substrate;
A step of adjusting the position of the substrate based on a result calculated in the calculation step, a step of transporting the substrate adjusted in position by the adjustment step onto a stage, and a step formed on the substrate on the stage. And a step of changing a calculation condition or a calculation method for calculating data related to the outer peripheral shape of the substrate to be exposed next, based on a result of the detection step. To do.
Furthermore, the exposure method of the present invention includes a step of calculating data relating to the rotation direction in the plane of the substrate, a step of adjusting the position in the rotation direction of the substrate based on the result calculated in the calculation step, and the adjustment Next, based on the result of the detection step, the step of transporting the substrate whose position is adjusted by the step onto the stage, the step of detecting the position of the mark formed on the substrate on the stage, and the detection step And a step of changing a calculation condition or a calculation method for calculating data relating to the position in the rotation direction of the power substrate.

  According to the present invention, positioning errors between exposure apparatuses having different positioning standards are prevented, downtime due to pre-alignment errors is reduced, and productivity in the semiconductor manufacturing process is improved.

It is a schematic block diagram of the substrate processing apparatus in the exposure apparatus of embodiment of this invention. It is a schematic plan view of a pre-alignment apparatus. It is a schematic side view of a pre-alignment apparatus. It is explanatory drawing of the output of the sensor which comprises a board | substrate outer periphery position measuring device. It is explanatory drawing of the data obtained by the sensor which comprises a board | substrate outer periphery position measuring device. It is explanatory drawing of the positional relationship of both wafers at the time of aligning the wafer from which a dimension differs. It is explanatory drawing which shows the dispersion | variation in the mark position at the time of aligning the wafer from which a dimension differs. It is explanatory drawing of the outer periphery data of an orientation flat wafer. It is explanatory drawing which shows the dispersion | variation in the primary differentiation of orientation flat outer periphery data. It is explanatory drawing which shows the variation of a fitting parameter and a mark position. It is an operation | movement flowchart of Embodiment 1 of this invention. It is a whole block diagram of the exposure apparatus of this invention.

Hereinafter, an exposure apparatus and an exposure method according to embodiments of the present invention will be described with reference to the accompanying drawings.
As shown in FIG. 12, the exposure apparatus of Embodiment 1 includes a lighting device 201, a reticle stage 202 on which a reticle as an original plate is mounted, a projection optical system 203, and a wafer stage (substrate stage) on which a wafer (substrate) is mounted. Stage device 204. The exposure apparatus projects and exposes a circuit pattern formed on a reticle onto a wafer, and may be a step-and-repeat projection exposure method or a step-and-scan projection exposure method.
The illumination device 201 illuminates a reticle on which a circuit pattern is formed, and includes a light source unit and an illumination optical system. The light source unit uses, for example, a laser as a light source. As the laser, an ArF excimer laser with a wavelength of about 193 nm, a KrF excimer laser with a wavelength of about 248 nm, an F2 excimer laser with a wavelength of about 153 nm, or the like can be used. However, the type of laser is not limited to an excimer laser, for example, a YAG laser may be used, and the number of lasers is not limited. When a laser is used as the light source, it is preferable to use a light beam shaping optical system that shapes the parallel light beam from the laser light source into a desired beam shape and an incoherent optical system that makes the coherent laser light beam incoherent. The light source that can be used for the light source unit is not limited to the laser, and one or a plurality of lamps such as a mercury lamp and a xenon lamp can be used. The illumination optical system is an optical system that illuminates the mask, and includes a lens, a mirror, a light integrator, a diaphragm, and the like.

  The projection optical system 203 includes an optical system including only a plurality of lens elements, an optical system (catadioptric optical system) including a plurality of lens elements and at least one concave mirror. Furthermore, an optical system having a plurality of lens elements and at least one diffractive optical element such as a kinoform, an all-mirror optical system, or the like can be used. The reticle stage 202 and the substrate stage device 204 can be moved by, for example, a linear motor. In the case of the step-and-scan projection exposure method, the reticle stage 202 and the substrate stage device 204 move synchronously. Further, in order to align the reticle pattern on the wafer, at least one of the substrate stage device 204 and the reticle stage 202 is provided with a separate actuator. Such an exposure apparatus is used for manufacturing a semiconductor device such as a semiconductor integrated circuit or a device on which a fine pattern such as a micromachine or a thin film magnetic head is formed.

  Next, with reference to FIG. 1, the substrate processing apparatus 50 which comprises the exposure apparatus of Embodiment 1 of this invention is demonstrated. A substrate stage apparatus 204 shown in FIG. 12 has the substrate stage 1 and the base 20 shown in FIG. 1, and the substrate stage 1 is a stage on which the wafer 4 is mounted and moved. The wafer 4 is transferred to the pre-alignment apparatus 3 by a substrate transfer robot (not shown). The wafer 4 transferred to the pre-alignment apparatus 3 is pre-aligned by the pre-alignment apparatus 3 and then transferred to the substrate stage 1 by the substrate transfer mechanism 6. The control device 7 includes a storage unit 8 and controls the pre-alignment device 3, the substrate stage 1, and the base 20.

  Here, when the wafer 4 does not have a pattern, that is, the wafer 4 that has not undergone the exposure process is immediately subjected to high-precision alignment (fine alignment) on the substrate stage 1 after pre-alignment by the pre-alignment apparatus 3. Then, an exposure process is performed. This is because it is not necessary to superimpose reticle patterns.

  On the other hand, if a pattern has already been formed on the wafer 4, after pre-alignment by the pre-alignment apparatus 3, the substrate stage 1 is measured by the mark detector 2 (mark detection unit) in order to measure the position of the pattern. The position of the mark 5 formed on the wafer 4 is detected above (on the stage). The base 20 drives the substrate stage 1 based on the measurement result of the position of the mark 5 so that the pattern to be newly transferred is superimposed with high accuracy on the existing pattern on the wafer 4 (on the substrate). After positioning the wafer 4, an exposure process is executed.

Next, the pre-alignment apparatus 3 provided in the substrate processing apparatus 50 will be described with reference to FIGS. 1, 2, and 3.
The pre-alignment apparatus 3 includes a pre-alignment stage 30 for driving the wafer 4 in the surface direction (horizontal direction, that is, the XY direction) and the rotation direction around the axis (the rotation direction around the Z axis, that is, the θ direction).
The pre-alignment stage 30 includes a substrate holding mechanism 30A (substrate chuck) that holds the wafer 4 by suction. The pre-alignment stage 30 further includes a rotation mechanism 30B that rotates the substrate holding mechanism 30A around the Z axis and a two-dimensional drive mechanism 30C that drives the substrate holding mechanism 30A in the XY directions as drive mechanisms.

In addition, the pre-alignment apparatus 3 includes an outer peripheral position measuring device 40 (detection unit) that detects the outer peripheral position of the wafer 4 held on the substrate holding mechanism 30A. The outer peripheral position measuring device 40 includes linear image sensors 31A, 31B, and 31C, a measurement light source 32B that is disposed to face the linear image sensor 31B, and a measurement light source that is not illustrated that is disposed to face the linear image sensors 31A and 31B.
In the first embodiment, as a notch indicating a direction, as shown in FIGS. 1 and 6, a wafer 4 having a center 4-1 and a wafer 4 a having a center 4-2 are formed in a V shape on the outer periphery. Alternatively, it has a U-shaped notch 4b. However, the wafers 4 and 4a may have a linear notch (orientation flat) (orientation flat) on the outer periphery thereof.

The control device 7 (calculation unit) is means for calculating data relating to the outer peripheral shape of the wafer 4 based on the output of the outer peripheral position measuring device 40. Data on the outer peripheral shape of the wafer 4 is the position of the V-shaped or U-shaped cutout 4b (notch) or the straight cutout (orientation flat) formed in the wafer 4. The pre-alignment apparatus 3 (adjustment unit) is means for adjusting the position of the wafer 4 based on the output of the control apparatus 7 and performing pre-alignment.
When the wafer 4 is driven by the pre-alignment stage 30 of the pre-alignment apparatus 3 in the rotation direction around the axis (rotation direction around the Z axis, that is, the θ direction), the control device 7 (calculation unit) The position in the rotation direction in the plane is calculated. In this case, the pre-alignment apparatus 3 (adjustment unit) adjusts the position in the rotation direction of the wafer 4 based on the output of the control device 7 (calculation unit).
The substrate transfer mechanism 6 (transfer unit) is means for transferring the wafer 4 whose position has been adjusted by the pre-alignment apparatus 3 onto the substrate stage 1 (on the stage). The substrate stage 1 and the base 20 are stages on which the pre-aligned wafer 4 is transferred. The mark detector 2 (mark detection unit) is means for detecting the position of the mark 5 formed on the wafer 4 on the substrate stage 1 (on the stage). The control device 7 (changing unit) is means for changing the calculation condition or calculation method of the control device 7 (calculating unit) based on the output of the mark detector 2.

  The storage unit 8 is means for storing a plurality of calculation methods by the control device 7 (calculation unit). The control device 7 (changing unit) is means for selecting one from the plurality of calculation methods. The control device 7 changes the calculation method so that the variation in the positions of the marks 5 on the plurality of wafers 4 is reduced. The control device 7 switches the predetermined calculation method so that the variation in the positions of the marks 5 on the plurality of wafers 4 is reduced.

  Next, the operation of the pre-alignment apparatus 3 will be described with reference to FIG. 1, FIG. 2, FIG. 3, and FIG. The pre-alignment apparatus 3 aligns the wafer 4 with respect to the center 4-1 of the wafer 4 shown in FIG. 6 obtained from the data on the outer periphery thereof, that is, the notch 4 b on the outer periphery of the wafer 4 in the XY direction. . First, the wafer 4 is transferred to the pre-alignment stage 30 by a substrate transfer mechanism (not shown). The transferred wafer 4 is sucked and held on the substrate holding mechanism 30A, and then the position of the notch 4b on the outer periphery of the wafer 4 is measured. In this measurement, the output signal of the image sensor 31B is processed each time the wafer 4 rotates by a predetermined angle while the wafer 4 is rotated by the substrate rotation mechanism 30B. Further, data indicating the distance from the rotation center 4-1 to the outer periphery of the wafer 4 with respect to the rotation angle of the wafer 4 is acquired.

  Here, in the outer peripheral position measuring device 40 in which the image sensor 31B and the measurement light source 32B are arranged so as to sandwich the wafer 4 as shown in FIG. 3, the output signal of the image sensor 31B at an arbitrary angle is shown in FIG. The distribution shown in In FIG. 4, the horizontal axis indicates the pixel position of the image sensor 31B, and the vertical axis indicates the value of each pixel (output value of the image sensor 31B). Since the output signal value of the image sensor 31B increases as the received light intensity increases, the output value at the portion 31d where the light from the measurement light source 32B is shielded by the wafer 4 as shown in FIG. The output value in the non-exposed portion 31e becomes high. A boundary 31 f between the portion 31 d having a small output value and the portion 31 e having a large output value indicates the outer periphery of the wafer 4. Note that the positional relationship between the rotation center 4-1 shown in FIG. 6 of the wafer 4 held by the substrate holding mechanism 30A and the image sensor 31B is known. For this reason, the distance from the rotation center 4-1 to the outer periphery of the wafer 4 can be obtained based on the pixel position of the image sensor 31B at the boundary 31f.

  By performing this measurement over the entire outer periphery of the wafer 4 every time the wafer 4 rotates by a predetermined angle, the data shown in FIG. In FIG. 5, the horizontal axis indicates the rotation angle of the wafer 4, the vertical axis indicates the distance from the rotation center 4-1 to the outer periphery of the wafer 4 obtained based on the output of the image sensor 31B, and a steep change point on the graph. Reference numeral 100 </ b> B denotes a notch 4 b of the wafer 4. The angle or direction (Δθ) of the notch 4b of the wafer 4 can be obtained based on the steep change point 100B shown in FIG.

  Further, based on the amplitude of the curve 100A, the eccentric amount (ΔXY) of the center 4-1 of the wafer 4 with respect to the rotation center of the substrate holding mechanism 30A can be calculated. Here, detection of Δθ and ΔXY means detection of the notch 4b and the center 4-1 of the wafer 4. Based on the obtained Δθ and ΔXY, the substrate holding mechanism 30A is rotated (θ direction) and horizontally moved (XY direction) by the rotation mechanism 30B and the two-dimensional drive mechanism 30C, and the notch 4b of the wafer 4 is directed in a predetermined direction. . Further, the center 4-1 of the wafer 4 is roughly positioned at the origin of the pre-alignment stage 30 that is a predetermined target position (step 1).

Next, the rotation (θ direction) is driven so that the notches of the image sensor 31A face each other, and the position of the center 4-1 of the wafer 4 obtained from the data of FIG. Then, the substrate holding mechanism 30A is moved horizontally (XY direction). Therefore, the final pre-alignment of the wafer 4 with the center 4-1 of the wafer 4 as a positioning reference is completed (Step 2).
By the pre-alignment described above, the wafer 4 is aligned at a predetermined position such as an angle in the rotation direction of the wafer 4 at the end of step 2.

  The pre-aligned wafer 4 is transported to the substrate stage 1 by the substrate transport mechanism 6, and then, more accurate positioning and subsequent exposure processing are performed. Here, a base pattern may be formed on the wafer 4, and a pre-alignment process in forming the base pattern may be performed using the center 4-1 of the wafer 4 as a positioning reference. In this case, even if the mark detector 2 is used to observe the mark 5 on the wafer 4 placed on the substrate stage 1, the mark 5 may be out of the visual field of the mark detector 2.

  Usually, when obtaining the center 4-1 of the wafer 4, the calculation is performed on the assumption that the portion other than the notch 4 b or orientation flat is a circle and the size of the wafer 4 conforms to the standard. However, actually, even if the notch 4b or orientation flat is excluded, the wafer 4 is not a circle but a shape having distortion. Also, the size of the wafer 4 varies, for example, by several hundred μm depending on the lot even if it is a 12-inch substrate. For this reason, when the center 4-1 of the wafer 4 is simply obtained from the outline data, the position of the center 4-1 changes depending on a predetermined calculation method to be obtained.

  The notch 4b or orientation flat is also made according to the standard, and when calculating the θ direction, a calculation method conforming to the standard is adopted. However, there is actually a deformation of the outer periphery of the wafer 4, and the outer periphery remains as it is. When the θ direction is obtained in the form of, variation occurs in a form dragged by deformation. FIG. 7 shows the orientation θ obtained from the position of the mark 5 detected by the mark detector 2 by performing pre-alignment called “alignment of the center 4-1 of the same wafer 4” between different manufacturers on the orientation flat wafer 4. The variation in the direction of 25 wafers 4 is shown. The horizontal axis shows the number of wafers 4 and the vertical axis shows the variation between the wafers 4 in the θ direction when the average value is zero. If this is the case, the position error is large and the mark 5 on the wafer 4 does not enter the field of view of the high-precision alignment system, so the sequence stops with an error. Therefore, in the first embodiment, the predetermined calculation method is changed or switched based on the variation data.

Hereinafter, a method for changing the predetermined calculation method using the orientation flat wafer 4 will be described.
FIG. 8 is a signal of the orientation flat wafer 4 in step 1 read by the line sensor 31C. Since the position of the outer periphery of the orientation flat portion changes rapidly as the wafer 4 is rotated, a crest 31g is formed in the orientation flat portion. The inflection point of the crest 31g is regarded as the center of the orientation flat and the θ direction of the wafer 4 is obtained. .

The first predetermined calculation method for obtaining the θ direction of the wafer 4 is obtained by approximating the signal of the orientation flat wafer 4 shown in FIG.
In this case, the sampling angle when the difference quotient approaches to zero is the apex (center of the orientation flat) of the peak 31g indicated by the signal of the orientation flat wafer 4 in FIG.

  The second predetermined calculation method for obtaining the θ direction of the wafer 4 uses the difference quotient obtained by the first method, linearly approximates N points before and after the zero cross point by y = ax + b, and “y ′ = 0”. Find “x” (sampling angle).

The third predetermined calculation method for determining the direction θ of the wafer, before and after N point of approximately orientation flat central signal of the orientation flat wafer 4 in FIG. 8 is approximated by a quadratic function ^{y = ax 2 + bx + c} , the first derivative y '= 2ax + b To “x” (sampling angle) when “y ′ = 0”. At this time, since y (y _{0 to} y _n ) and x (x _{0 to} x _n ) are known, a, b, and c can be easily obtained by solving simultaneous linear equations using a pseudo inverse matrix.

  The result of calculating the θ direction by the second predetermined calculation method is shown in FIG. 7, and it is shown that the pre-alignment in the exposure layer process of the previous process is not this calculation method. As described above, the predetermined calculation method in the θ direction in the pre-alignment is switched so that an error does not occur in the alignment by detecting the position of the mark 5 on the wafer 4 in the subsequent process due to the difference in the calculation method in the θ direction.

Next, a method for switching the predetermined calculation method will be described.
Necessary information includes the calculation result (data 1) in the θ direction in pre-alignment, the outer peripheral position data (data 2) for one round of the wafer 4 used to calculate this, and mark detection by alignment in the subsequent process. The result (data 3) is obtained. Therefore, these pieces of information are stored for each wafer 4.

  The predetermined calculation method is switched by the following method using these pieces of information. When the exposure apparatus A that processes the exposure layer in the previous process is known in advance, a plurality of (for example, one lot) wafers 4 processed by the exposure apparatus of the first embodiment are measured as adjustments. At this time, if the pre-alignment of the exposure apparatus of Embodiment 1 is the second predetermined calculation method and the exposure apparatus A is the third predetermined calculation method, the mark detection result (data 3) in the exposure apparatus of Embodiment 1 is as shown in FIG. The result shown in FIG.

  Next, the outer circumference position data (data 2) for one round of each wafer 4 is recalculated by the third predetermined calculation method, and this result is compared with the result (data 1) calculated by the original second predetermined calculation method. Then, the difference between data 1 and data 2 is the same as that of data 3. By this adjustment, it is optimal that the wafer 4 processed by the exposure apparatus A is pre-aligned by the third predetermined calculation method.

  During the operation of the exposure apparatus, the pre-alignment method is switched by a method for setting a pre-alignment method with parameters on the exposure apparatus or a method for setting with a file for setting exposure conditions. Thereafter, the wafer processed by the exposure apparatus A can be processed without causing an alignment error. In addition, even if the device that processes the exposure layer of the previous process is not known in advance, an alignment error can usually be generated by automatically performing the same processing as the adjustment processing described above while operating the exposure device. It can process without. However, in this case, some of the first wafers will generate an error, but the results of the pre-alignment method obtained by automatic adjustment will be saved automatically in a file that sets exposure conditions, etc. Can be processed without error from the first wafer.

Next, optimization of pre-alignment calculation parameters, which is a method for changing the predetermined calculation method, will be described.
FIG. 9 shows the first derivative data of the crest 31g in FIG. 8 of several wafers 4 in the same lot as FIG. In the case of the ideal wafer 4, since it is a derivative of a quadratic function, a straight line 31h is shown in FIG. 9, but some wafers 4 have deviations 31j and 31k from the straight line. The wafer 4 showing data deviating from the deviations 31j and 31k is a wafer 4 having a large variation as shown in FIG. For this reason, the pre-alignment in the process of the exposure layer in the previous process is performed by a method that is not affected by the straight line 31h. Therefore, there is a method of obtaining a peak by approximating the peak 31g shown in FIG. 8 with an ideal quadratic function, but the data of FIG. 8 which is the original data for fitting the quadratic function from the straight line 31h in FIG. If misaligned data is included, the fitting result is also dragged.

  For this reason, in Embodiment 1, the data acquisition range when approximating with this quadratic function is used as a parameter. FIG. 10 is a graph of the variation in the θ direction between the wafers 4 as in FIG. 7. The same 25 wafers 4 are processed by the third predetermined calculation method described above. The difference in variation shown in FIG. 10 is due to the difference in the fitting data acquisition range (number of data N used for quadratic function approximation). Even with the same 25 wafers 4, the positional accuracy greatly depends on the number of data N used for fitting, and when this number of data is optimized, the variation of 500 μm or more as shown in FIG. 10 is 150 μm. It is reduced to the following, and the accuracy of alignment is remarkably improved.

For this reason, in the first embodiment, when the pre-alignment method described above, that is, the predetermined calculation method is switched and adjusted, the following processing is added to further improve the alignment accuracy.
After determining that the pre-alignment is based on the third predetermined calculation method by the adjustment described above, how the variation of the detection position result of the mark 5 of the 25 wafers 4 changes while swinging the fitting data acquisition range. Simulate. Furthermore, the acquisition range of the fitting data when the variation is minimized is determined, and the determined data number N is stored in the parameter data for each lot.

Next, the operation sequence of the exposure apparatus according to the first embodiment of the present invention will be described with reference to FIG.
The wafer 4 is carried into the pre-alignment apparatus 3 by a substrate transfer mechanism (not shown) shown in FIG. It is assumed that a pattern has already been formed on the wafer 4. (Step 101)
The wafer 4 is pre-aligned by the pre-alignment apparatus 3. The pre-alignment parameter at the beginning of the lot is a predetermined parameter. The calculation result by the predetermined calculation method of pre-alignment and the data of each line sensor 31A, 31B, 31C are preserve | saved at the memory | storage part 8 of the control apparatus 7 of the pre-alignment apparatus 3. FIG. (Step 102)

  The position of the mark 5 on the wafer 4 is measured by the mark detector 2. At this time, the information on the position of the mark 5 is stored in the storage unit 8 of the control device 7 of the mark detector 2. For example, if the parameter of the process 102 is inappropriate at the beginning of the lot, the mark 5 on the wafer 4 may not be within the observation field of view of the mark detector 2 in this process 103. In that case, the substrate stage device 204 (base 20, substrate stage 1) that enters the search sequence and holds the wafer 4 moves so that the position of the mark 5 is positioned within the detection range of the mark 5. At this time, the driving amount of the wafer 4 is also stored in the storage unit 8 of the control device 7 in the same manner as the position of the mark 5. (Step 103)

The predetermined calculation method is changed based on the pre-alignment data acquired in step 102 and the position data of the mark 5 by the mark detector 2 acquired in step 103 so far. That is, the predetermined calculation method for the data of the line sensors 31A, 31B, and 31C acquired in step 102 is changed and optimized so that the variation in the inspection result of the mark detector 2 in FIG. 10 is minimized. (Step 106)
Based on the detection result of the mark 5 in step 103, the pattern position on the wafer 4 is obtained, and the base 20 is driven to expose the wafer 4. (Step 104)

  It is determined whether or not the lot has been completed. If the lot has not been completed, the next wafer 4 is loaded and the sequence is continued from step 101. If the lot has been completed, the process proceeds to step 107. In the sequence of the exposure apparatus according to the first embodiment, in order to increase the throughput by performing a parallel operation, the wafers 4 are loaded into the exposure apparatus for every plurality, and the processes 101 and 102 are performed in parallel with the process 104. In particular, in a type of exposure apparatus having two bases 20 that has become the mainstream recently, the operations of steps 101, 102, and 103 can be performed in parallel with the step 104. However, in any case, when focusing on one wafer 4, there is no difference from the flow shown in FIG. (Step 105)

The predetermined calculation method is changed based on the pre-alignment data acquired in step 102 in the lot finished in step 105 and the position data of the mark 5 by the mark detector 2 acquired in step 103. That is, the predetermined calculation method of the data of the line sensors 31A, 31B, and 31C acquired in step 102 is changed and optimized so that the variation in the inspection result of the mark detector 2 shown in FIG. 10 is minimized. If only the step 106 is sufficiently effective, the step 107 may be omitted. (Step 107)
The above steps 101 to 107 are repeated until all lots are completed. (Step 108)

  In the above process, the processes 106 and 107 are repeated for each lot, but if the difference between the lots is small, there is no need to correct the parameters again. For example, the processes 106 and 107 are inserted at the head of the lot, and the processes 106 and 107 are performed from the subsequent processes. 107 may be omitted. 11 automatically optimizes the parameters. However, if data can be acquired in advance, parameters corresponding to the wafer 4 may be set in advance and selected. Also in this case, the steps 106 and 107 can be omitted from the sequence.

  As described above, according to the exposure apparatus of the first embodiment, even with a wafer exposed by an exposure apparatus having a different positioning reference, prealignment can be performed with high accuracy without being affected by variations in the shape of the wafer. As a result, it is possible to reduce the downtime due to the pre-alignment error and the increase in the tact time due to the changeover driving, thereby improving the productivity in the semiconductor manufacturing process.

[Embodiment of Device Manufacturing Method]
Next, a method for manufacturing a device (semiconductor device, liquid crystal display device, etc.) according to an embodiment of the present invention will be described. In this method, an exposure apparatus to which the present invention is applied can be used.
A semiconductor device is manufactured through a pre-process for producing an integrated circuit on a wafer (semiconductor substrate) and a post-process for completing an integrated circuit chip on the wafer produced in the pre-process as a product. The pre-process may include a step of exposing the wafer coated with the photosensitive agent using the above-described exposure apparatus, and a step of developing the wafer exposed in the step. The post-process can include an assembly process (dicing, bonding) and a packaging process (encapsulation). Moreover, a liquid crystal display device is manufactured by passing through the process of forming a transparent electrode. The step of forming the transparent electrode includes a step of applying a photosensitive agent to a glass substrate on which a transparent conductive film is deposited, a step of exposing the glass substrate on which the photosensitive agent is applied, using the above-described exposure apparatus, and the step And developing the glass substrate exposed in step (b).
The device manufacturing method of this embodiment is more advantageous than the conventional one in at least one of device productivity, quality and production cost, and safety.
As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

DESCRIPTION OF SYMBOLS 1 Substrate stage 2 Mark detector 3 Pre-alignment device 4 Wafer 5 Mark 6 Substrate transport mechanism 7 Control device 8 Storage unit 20 Base 30 Pre-alignment stage 30A Substrate holding mechanism 30B Substrate rotation mechanism 30C Two-dimensional drive mechanisms 31A, 31B, 31C Sensors 32A, 32B, 32C Measurement light source 40 Perimeter position measuring device 201 Illumination system unit 202 Reticle stage 203 Projection optical system 204 Substrate stage device

Claims (6)

A detection unit that detects the outer peripheral position of the substrate, a calculation unit that calculates data on the outer peripheral shape of the substrate based on the output of the detection unit, and an adjustment unit that adjusts the position of the substrate based on the output of the calculation unit And an exposure apparatus comprising a transport unit that transports the substrate whose position is adjusted by the adjustment unit onto a stage,
A mark detection unit for detecting a position of a mark formed on the substrate on the stage;
A changing unit that changes a calculation condition or a calculation method of the calculation unit based on an output of the mark detection unit;
An exposure apparatus comprising: A storage unit for storing a plurality of calculation methods by the calculation unit;
The exposure apparatus according to claim 1, wherein the changing unit selects one of the plurality of calculation methods.   The exposure apparatus according to claim 1, wherein the data related to the outer peripheral shape is a position of a notch or an orientation flat formed in the substrate. A calculation unit that calculates a position in the rotation direction in the plane of the substrate, an adjustment unit that adjusts a position in the rotation direction of the substrate based on an output of the calculation unit, and a stage that adjusts the position of the substrate by the adjustment unit In an exposure apparatus comprising a transport unit that transports upward,
A mark detection unit for detecting a position of a mark formed on the substrate on the stage;
A changing unit that changes a calculation condition or a calculation method of the calculation unit based on an output of the mark detection unit;
An exposure apparatus comprising: Calculating data related to the outer peripheral shape of the substrate;
Adjusting the position of the substrate based on the result calculated in the calculating step;
Transporting the substrate, the position of which has been adjusted by the adjusting step, onto a stage;
Detecting a position of a mark formed on the substrate on the stage;
Based on the result of the detection step, a step of changing a calculation condition or a calculation method for calculating data on the outer peripheral shape of the substrate to be exposed next;
An exposure method comprising: Calculating data relating to the direction of rotation in the plane of the substrate;
Adjusting the rotational position of the substrate based on the result calculated in the calculating step;
Transporting the substrate, the position of which has been adjusted by the adjusting step, onto a stage;
Detecting a position of a mark formed on the substrate on the stage;
Changing a calculation condition or a calculation method for calculating data relating to a position in a rotation direction of the substrate to be exposed next based on a result of the detection step;
An exposure method comprising:

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