JP3320298B2 - Semiconductor exposure apparatus and semiconductor exposure method using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the fine pattern of a semiconductor integrated circuit which is drawn on the mask, the exposure on the semiconductor wafer, a semiconductor exposure apparatus for forming transfer, in particular the mask and wafer infinitesimal interval (hereinafter proximity The present invention relates to a so-called proximity exposure apparatus for performing exposure by approaching a gap, and a semiconductor manufacturing method using the exposure apparatus.

[0002]

2. Description of the Related Art A typical example of a proximity exposure apparatus is an X-ray exposure apparatus. For example, an X-ray exposure apparatus using an SR light source is disclosed in Japanese Patent Application Laid-Open No. H2-110031.

FIG. 7 shows a general configuration of this X-ray exposure apparatus. 7, reference numeral 101 denotes a mask, 102 denotes a mask chuck for holding the mask, 103 denotes a mask membrane, and 104 denotes a mask chuck base. Reference numeral 105 denotes a wafer, and reference numeral 106 denotes a wafer chuck for holding the wafer 105. Reference numeral 107 denotes a fine movement stage used for positioning the mask 101 and the wafer 105, reference numeral 108 denotes a coarse movement stage used for movement between shots, and reference numeral 109 denotes a stage base to which the guide of the coarse movement stage 108 is fixed. Wafer 105 and wafer chuck 106 are mounted on fine movement stage 107.

In an X-ray exposure apparatus, the pattern of the mask 101 is generally exposed on the wafer 105 by a so-called step-and-repeat method in which the exposure is repeated a plurality of times, and the mask 101 and the wafer 105 are exposed at an interval of 10 to 50 μm. Exposure (proximity exposure) is performed with facing.
In the X-ray mask 101, the portion where the absorber pattern is formed is a thin film 103 (membrane) having a thickness of about 2 μm.

Hereinafter, a procedure for performing exposure by a die-by-die method in a conventional X-ray exposure apparatus will be described.

(1) The coarse movement stage 108 is driven so that the portion of the wafer 105 where the n-th shot is exposed is below the mask membrane 103. (2) The wafer 105 is moved by the fine movement stage 107.
The gap between the mask 101 and the wafer 105 (hereinafter referred to as gap) is measured from the gap at the time of the step (hereinafter referred to as A).
It is driven to the gap for performing F measurement) and performs AF measurement. (3) After the mask 101 and the wafer 105 are parallelized on the fine movement stage 107, the mask 101 and the wafer 1
05 In-plane displacement measurement (hereinafter AA measurement)
Is performed, and AA measurement is performed. (4) The mask 101 and the wafer 105 are aligned and exposed. (5) Retreat to the gap at the time of the step. Hereinafter, (1) to (5) are repeated.

[0007]

In THE INVENTION Problem to be Solved] Conventional proximity exposure apparatus, the mask and the wafer is close to the infinitesimal interval (several tens of [mu] m), when the stage movement such as during step movement, the mask membrane deforms It is assumed that you are doing. Therefore, there are the following problems. (1) The value of the AF measurement changes by the deformation of the mask membrane. (2) When the mask membrane is deformed, the alignment marks on the membrane are displaced in the in-plane direction, and the alignment accuracy is reduced. (3) Transfer accuracy (image performance) decreases.

To solve these problems, for example, AF, AA measurement, and exposure are performed after a sufficient time has elapsed after setting the exposure gap. Alternatively, a method of slowly driving the stage so that the membrane is not deformed can be considered, but in these methods, the throughput is reduced.

SUMMARY OF THE INVENTION It is an object of the present invention to adjust the distance between a mask and a wafer by adjusting the distance between the mask and the wafer based on information on the gap between the mask and the wafer in order to reduce the deformation of the mask membrane during movement of the stage to a predetermined value or less. It is an object of the present invention to provide a semiconductor exposure apparatus and a semiconductor exposure method which have high wafer alignment accuracy and transfer accuracy and high productivity.

[0010]

Means and Functions for Solving the Problems The present inventor has provided:
Result of intensive studies to achieve the above object, the mask and the semiconductor web having an absorber pattern on main Nburen
Measuring means for measuring the distance between the mask, the mask and the semiconductor
Adjusting means for adjusting the interval between the body wafers, and the semiconductor wafer for sequentially exposing a plurality of portions of the semiconductor wafer.
Ha and a driving means because moving step, the
In the semi-conductor exposure system exposing the semiconductor wafer to the mask and the semiconductor wafer in a pattern of the mask is brought closer to the minute space, control to step moves the semiconductor wafer while adjusting the distance between the mask and the semiconductor wafer The present invention has been completed by a semiconductor exposure apparatus having means and a semiconductor exposure method using the apparatus.

Further, the semiconductor exposure apparatus of the present invention has the above-mentioned control.
Control means may as maps height information of the semiconductor wafer over the entire surface by preliminarily before Kihaka constant means, said control means said semiconductor based on the result of the mapping
The stage driving path of one body wafer component desirably has a function of determining pre Me.

As described above, according to the present invention, since the step movement is performed while adjusting the distance between the mask and the wafer based on the information on the gap between the mask and the wafer, the accuracy of the alignment between the mask and the wafer, the image performance, and the productivity are improved. Is improved.

[0013]

Embodiment 1 FIG. 1 is a diagram showing a configuration of an X-ray exposure apparatus of the present embodiment and a coordinate system used for explanation. Hereinafter, the X-ray exposure apparatus of the present embodiment will be described with reference to FIG.

In FIG. 1, reference numeral 1 denotes a mask, 2 denotes a mask membrane, 3 denotes a mask chuck for holding the mask 1, and 4 denotes a mask chuck base. 5 is a wafer, 6
Is a wafer chuck for holding the wafer 5. Reference numeral 7 denotes a fine movement stage used for positioning the mask 1 and the wafer 5, and reference numeral 8 denotes a coarse movement stage used for movement between shots. Reference numeral 9 denotes a non-contact displacement meter that measures the height of the wafer 5 from the mask chuck 3 side. The displacement meter 9 can measure the height of the wafer 5 in a non-contact manner. For example, there is a displacement meter that measures the height of the wafer 5 by applying a laser beam to the wafer 5 and measures the reflected light, or a capacitance that measures the capacitance. In addition, the non-contact displacement meter 9
Are required to obtain surface information of the wafer 5. Reference numeral 10 denotes a stage control unit that controls the height of the stage based on the value measured by the distance measurement sensor 9.

Hereinafter, a method of controlling the height of the stage during the step movement of the present invention will be described in accordance with the operation of the exposure apparatus with reference to the flowcharts of FIGS.

(1) First movement of the wafer by the coarse movement stage 8
Move the position of the shot below the mask (step S
1). At this time, the gap between the mask 1 and the wafer 5 is wider than the gap at the time of exposure. (2) The fine movement stage 7 is driven in the Z direction based on the output of the non-contact displacement meter 9 to set the gap between the mask 1 and the wafer 5 at the exposure gap (step S2). At this time, the height of the mask 1 is measured in advance by a system different from that of the exposure apparatus, and the value is stored in the stage control means 10 as data for each mask. It is calculated from the measured value and the height data of the mask. (3) The gap is finely adjusted by a mask and wafer position measuring means (not shown) separate from the non-contact displacement meter 9 (step S).
3) After the alignment, exposure is performed (step S4). (4) After the end of the exposure, the wafer 5 is moved by the coarse movement stage 8 to the position of the second shot without changing the gap (Step S5). Details discussed later Suruga, the position in the Z direction of the fine moving stage 7 as the spatial position of the virtual plane of the wafer is calculated from the output of this time three non-contact displacement gauge 9 is always within a predetermined range The coarse movement stage 8 is driven while being controlled by the stage control means 10 to move to the position of the second shot. (5) When the wafer 5 has moved to the position of the second shot, the gap is finely adjusted by a mask and wafer position measuring means (not shown) (step S6), and after the alignment, exposure is performed (step S7). Thereafter, the same processes as (4) and (5) are repeated to expose the wafer 5 to a predetermined number of shots.

In step S5, if the tilt amount of the stage during the step drive exceeds a predetermined value, the deformation amount of the wafer 5 is large and the wafer 5 may collide with the mask 1, so that the gap , And the exposure is started again in the same sequence as the first shot.

FIG. 3 is a flow chart showing in detail the procedure for detecting such an abnormality in the height of the wafer. The processing for driving the stage in the X and Y directions from the nth shot to the (n + 1) th shot is described. This is shown in a flowchart.

Hereinafter, the processing at the time of this step drive will be described in more detail with reference to FIG. The exposure sequence of the n-th shot is completed (step S8), and the next shot (n +
In the case of step driving to (one shot), the step is moved on the X and Y planes in the direction of n + 1 shots while the gap between the mask 1 and the wafer 5 remains the gap at the time of exposure (step S9) . The output of the previous SL three non-contact displacement gauge 9 calculates the spatial position of the virtual plane of the wafer 5 (step S11). When the position is within the predetermined range, the process proceeds to step S12, in which the position of fine movement stage 7 in the Z direction is controlled by stage control means 10, and the processing from step S9 is repeated. By repeating the processing of S9 to S12 , when the wafer 5 moves to the position of n + 1, the movement on the X and Y planes is ended, and the exposure sequence of the (n + 1) th shot is started (step S14). That is, steps S3 and S4 or steps S6 and S6 in FIG.
The same processing as in step 7 is performed.

On the other hand, when the spatial position of the virtual plane of the wafer 5 calculated from the outputs of the three non-contact displacement gauges 9 exceeds a predetermined range, the process proceeds to step S15, where the gap is temporarily increased and n + 1 shots are performed. The stage is moved to the eye, and the fine movement stage 7 is driven in the Z direction based on the output of the non-contact displacement meter 9 as in the case of the first shot, and the gap between the mask 1 and the wafer 5 is set to the exposure gap (step S15).
The exposure sequence of the (n + 1) th shot is started (step S14).

By performing the above processing, the gap between the mask 1 and the wafer 5 can be reduced from the n-th shot to the (n + 1) -th shot as long as the tilt amount of the stage during step driving does not exceed a predetermined value. Step drive is performed while maintaining the gap at the time of exposure.

Next, the arrangement of the non-contact displacement meter 9 will be described with reference to FIG. FIG. 4 shows the mask 1 used in the present embodiment viewed from the wafer 5 side. In FIGS. 1, 4 and 5, the same reference numerals indicate the same members.

In the case of measuring the distance between the mask 1 and the wafer 5, in this embodiment, since the step movement is performed while maintaining the exposure gap, the membrane 2 may vibrate at the time of the step movement, so that accurate measurement cannot be performed. Therefore, the means for measuring the interval at the time of the step movement does not directly measure the interval between the mask 1 and the wafer 5 through the membrane 2 but the wafer 5
Is more suitable for measuring the height of the mask 1 and calculating the interval from the height of the mask 1 measured in advance. Further, in order to suppress the deformation of the mask membrane 2 within a predetermined size, it is necessary that a pressure change between the membrane 2 and the wafer 5 is equal to or less than a predetermined value. For that purpose, the change in the volume of the space between the membrane 2 and the wafer 5 must be less than a predetermined value.

Therefore, it is more effective if the space surrounded by the points measured by the non-contact displacement meter 9 and the virtual plane calculated from the measured values includes the space surrounded by the mask membrane 2 and the wafer 5. Therefore, in this embodiment, the arrangement of the non-contact displacement meter 9 is outside the n-sided polygon (n = the number of the non-contact displacement meters 9) circumscribing the mask membrane 2 . In addition, when the height of the wafer 5 is measured in a very wide range, the difference between the calculated virtual plane and the actual wafer surface increases. Therefore,
Position of the non-contact displacement meter 9, as shown in FIG. 4, the mask 1
A position about the inside of an n-gon (n = 3) circumscribing is appropriate. However, the effects of the present invention can be obtained with other sensor arrangements.

As described above, the mask membrane 2 and the wafer 5
The step movement is performed while adjusting the gap between the mask membrane 2 and the wafer 5 such that the amount of change in the volume between the mask membrane 2 and the wafer 5 becomes equal to or less than a predetermined value based on the measured value of the gap. Deformation can be reduced to a predetermined value or less, and the following effects can be obtained.

(1) AF and AA measurements can be performed with high accuracy. (2) The image performance is improved. (3) Since the gap is not widened for each shot, the step movement can be made faster and the throughput can be improved.

Although the first embodiment has described the case of the die-by-die alignment method, the above-described step moving method is also effective at the time of measurement and exposure of the alignment of a mask and a wafer by the global alignment method.

In this embodiment, the height of the wafer stage is adjusted to adjust the gap. However, the same effect can be naturally obtained by adjusting the height on the mask stage side. Example 2 In Example 2, a wafer 5 previously chucked was used.
This is a method of measuring the height of the entire surface and mapping the height of the wafer 5. FIG. 5 is a view showing a semiconductor exposure apparatus according to the present embodiment. In the figure, reference numeral 11 denotes a measuring means for measuring an interval between the mask 1 and the wafer 5.

The present invention will be described below according to the operation of the exposure apparatus. FIG. 6 shows this in a flowchart.

(1) The distance between the wafer 5 and the mask 1 chucked with a gap that does not deform the mask membrane 2 even when the stage is moved stepwise is measured at a plurality of points by the measuring means 11 (step S16). (2) The information obtained in (1) is processed, the height of the entire wafer is mapped, and loaded into the stage control means 10 (step S17). (3) In the stage control means 10, the wafer when passing under the mask membrane 2 so that the volume change between the mask membrane 2 and the wafer 5 becomes less than a predetermined value in the path of the step movement based on the map. The height and posture of 5 are calculated. Therefore, for example, from the n-th shot to the n-th shot
For example, the movement path when step-moving to the +1 shot is divided into ten, and the membrane 2 and the wafer 5 at the ten positions are divided.
So that the volume of the portion between each is within a predetermined range,
The posture of the stage at each position is determined from the created map. As a result, the path when moving from the n-th shot to the (n + 1) -th shot is a smooth drive connecting the ten positions. In addition to the method of calculating the volume, there is also a method of calculating the posture of the stage such that the height of the wafer 5 at the center of the membrane at each position and the normal vector of the wafer surface at that position are within a predetermined range. is there. A drive path for one wafer is determined by the above method (step S18). (4) The wafer 5 is moved to the position of the first shot while adjusting the height of the wafer 5 based on a predetermined stage drive path (Step S19). (5) The mask 1 and the wafer 5 are aligned and exposed (Steps S20 to S22). (6) The wafer 5 is moved to the position of the second shot while adjusting the height of the wafer 5 based on a predetermined stage drive path (Step S23). (7) The mask 1 and the wafer 5 are aligned and exposed (Steps S24 and S25). Hereinafter, the same processes as (6) and (7) are repeated to expose the wafer 5 to a predetermined number of shots.

As a result of the mapping, the stage is moved by widening the gap at a position where the deformation of the wafer 5 is so large that the gap cannot be set. The stage is controlled so that shots for which a gap cannot be set are skipped in advance.

As described above, the following effects can be obtained by mapping the height of the wafer 5 in advance and determining the drive path of the stage by the means for measuring the distance between the mask 1 and the wafer 5.

(1) There is no need to adjust the gap at the position of each shot, and the improvement in throughput can be measured. (2) Since a position having a large deformation can be specified in advance, it is not necessary to determine an error for each shot, and the throughput is improved. (3) The height distribution of the entire wafer 5 can be calculated by statistically processing the height information, so that the distance between the mask 1 and the wafer 5 can be adjusted with higher precision.

[0034]

As described above, according to the invention of the semiconductor exposure method according to the present application, the deformation of the mask membrane can be reduced to a predetermined value or less, and high precision alignment,
It is possible to improve the image performance and the throughput. Further, according to the invention of the semiconductor exposure apparatus according to the present application, it is possible to reduce the deformation of the mask membrane to a predetermined value or less, and achieve a high-precision alignment, an improvement in image performance, and an improvement in throughput. realizable. Further, according to the invention of the semiconductor exposure apparatus having the control means for mapping the height information of the entire surface of the wafer by the mask and wafer distance measuring means in advance, it is not necessary to adjust the gap at each shot position, thereby improving the throughput. I can measure. Further, according to the invention of the semiconductor exposure apparatus having the function of previously determining the stage drive path for one wafer based on the mapping result, the position where the gap cannot be adjusted is specified in advance, and the position is determined by the gap. Spread the stage and move the stage. In addition, the stage in which a gap cannot be set can be controlled so as to be skipped in advance, thereby improving the throughput.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view illustrating a device configuration according to a first embodiment.

FIG. 2 is a flowchart illustrating an exposure procedure according to the first embodiment.

FIG. 3 is a flowchart illustrating a wafer height abnormality detection procedure according to the first embodiment.

FIG. 4 is a schematic plan view showing an arrangement of a displacement meter according to the first embodiment.

FIG. 5 is a schematic cross-sectional view illustrating a device configuration according to a second embodiment.

FIG. 6 is a flowchart illustrating an exposure procedure according to the second embodiment.

FIG. 7 is a schematic sectional view showing the configuration of a conventional X-ray exposure apparatus.

[Explanation of symbols]

1: mask, 2: mask membrane, 3: mask chuck, 4: mask chuck base, 5: wafer, 6: wafer chuck, 7: fine movement stage, 8: coarse movement stage,
9: non-contact displacement meter, 10: stage controller, 11: measuring means, 101: mask, 102: mask chuck, 10
3: mask membrane, 104: mask chuck base, 105: wafer, 106: wafer chuck, 10
7: fine movement stage, 108: coarse movement stage, 109: stage base.

Continuation of the front page (56) References JP-A-4-150012 (JP, A) JP-A-2-94515 (JP, A) JP-A-1-238014 (JP, A) JP-A-63-155723 (JP) JP-A-60-154618 (JP, A) JP-A-56-90523 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/027 G03F 7/20 521 G21K 5/02

Claims (4)

(57) [Claims] And 1. A measuring means for measuring the distance between the mask and the semiconductor weblog Ha having an absorber pattern on main Nburen, and adjusting means for adjusting the distance between the mask and the semiconductor wafer, a plurality of portions of said semiconductor wafer To sequentially expose
And a driving means for moving the step to the semiconductor wafer in order, small between the semiconductor wafer and the mask
The semiconductor wafer in the pattern of the mask in close proximity to a gap.
Using a semi-conductor exposure system you exposure Ha, in the semiconductor exposure method <br/>, based on information of said measuring means, and the mask
Semiconductor exposure wherein the Rukoto moving step the semiconductor wafer while adjusting the distance the adjusting means of the semiconductor wafer. 2. A measuring means for measuring the distance between the mask and the semiconductor weblog Ha having an absorber pattern on main Nburen, and adjusting means for adjusting the distance between the mask and the semiconductor wafer, the multiple of said semiconductor wafer For exposing parts sequentially
And a driving means because the semiconductor wafer is moved step in order, small between the semiconductor wafer and the mask
The semiconductor wafer in the pattern of the mask in close proximity to a gap.
In the semi-conductor exposure system you exposure Ha, the semiconductor wafer while adjusting the distance between the front SL mask the semiconductor wafer
A semiconductor exposure apparatus having control means for step-moving an object. Wherein said control means is a semiconductor exposure apparatus according to claim 2, wherein the mapping to Turkey <br/> height information of the semiconductor wafer over the entire surface by pre Me before Kihaka constant means. 4. 請 characterized by having a based on the result of said control means has the mapping function of predetermining the stage driving path of one sheet of the semiconductor wafer
The semiconductor exposure apparatus according to claim 3 .