JP2003287419A - Pattern-inspection method and apparatus, and mask- manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an accurate mask pattern-inspection method, an accurate mask pattern-inspection apparatus, and a manufacturing method of a mask using the apparatus. <P>SOLUTION: When reference data are to be compared with sensor data by a comparison means 6, a correction value where an adjacent pattern whose measurement is completed is corrected by predetermined pattern conditions. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern defect inspecting method and a pattern inspecting apparatus for a mask, a wafer and the like used in a manufacturing process of semiconductors, liquid crystals and the like, and a mask manufacturing method using the same.

[0002]

2. Description of the Related Art Semiconductor integrated circuits have been increasingly integrated and miniaturized with the improvement of exposure technology and process technology. Along with this, with respect to the photomask and the reticle to be the original plate, it is required to further improve the positional accuracy and the dimensional accuracy and to reduce the minute defects and the foreign matters. For example, it is said that it is necessary to detect a defect having a size of 0.125 μm with a tetraploid mask with respect to a circuit pattern having a width of 0.13 μm on a wafer.

In a pattern defect inspection apparatus such as a photomask, a die-to-database (die-to-database) is used.
There is an inspection method called comparison. In this method, sensor data obtained by imaging a circuit pattern to be inspected with a line sensor is compared with reference data created from CAD data used for designing the pattern, and a mismatch point between the two is detected as a defect.

At the time of inspection, the occurrence of a pseudo defect due to an error in pattern conditions (position, size, corner rounding, brightness) such as positional deviation becomes a problem. Conventionally, as for the correction amount of the pattern condition, the reference data is corrected from the pattern condition measured by the standard mask to perform the pattern inspection. Further, in the recent mask pattern inspection, the inspection is performed by correcting the reference data from the pattern condition measured at the representative point on the mask before the inspection.

As described above, in the pattern defect inspection apparatus,
Since the mismatch point between the sensor data and the reference data is detected as a defect, alignment between the two is particularly important. Factors that impair the alignment between the two include yawing and speed unevenness of the XY axis stage, position offset of the mask, expansion / contraction amount, and rotation amount. Due to these, a pseudo defect occurs due to an error in pattern conditions (position, size, corner rounding, brightness). Therefore, in order to further improve the detection sensitivity of pattern defects in the future, it is necessary to correct the error of the pattern condition by the electric control system or the computer software.

In particular, when the size of the pattern becomes smaller due to the miniaturization of the semiconductor pattern, the shape of the pattern according to the sensor data will be slightly different from the shape of the pattern according to the reference data due to the optical characteristics, which may cause an error. You may recognize. Algorithms to reduce recognition need to prepare and evaluate samples of various pattern sizes.

[0007]

However, when correcting a pseudo defect caused by an error of the above-mentioned pattern conditions (position, size, corner rounding, brightness) with an electric control system or computer software, In order to match with the reference data, there is a problem that the electric control system for correcting the variation in the position of the mask set on the stage becomes complicated and the circuit scale becomes large.

Further, even with an inspection method using a value measured at a representative point in order to increase the defect detection sensitivity, it is not possible to avoid the problem that a pseudo defect occurs due to an error in a pattern condition.

Further, with the miniaturization of semiconductor patterns,
The production of sample masks is a costly and time consuming problem.

Therefore, in order to stably perform the high-precision mask inspection, it is necessary to perform the inspection while correcting the pattern immediately before the adjacent pattern (for example, the stripe inspected immediately before) with the correction amount obtained. .

In order to solve the above problems, it is an object of the present invention to provide a highly accurate mask pattern inspection method and pattern inspection apparatus, and a mask manufacturing method using the same.

[0012]

According to the means of the present invention, in the pattern inspection method for comparing the reference data of the pattern of the object to be inspected with the sensor data by the comparing means to inspect the defect of the pattern. In the pattern inspection method, when the reference data and the sensor data are compared by the comparison means, the reference data corrected in accordance with the pattern inspection condition preliminarily measured from the adjacent pattern after the inspection is used is used. is there.

According to the second aspect of the present invention,
In the pattern inspection method, at least one of position, size, corner rounding, and brightness is used as the pattern condition.

According to the means of the invention of claim 3,
In the pattern inspection method, the pattern condition measured from the adjacent patterns for which the inspection has been completed is for each stripe or block.

According to the means of the invention of claim 4,
The reference data of the pattern of the object to be inspected and the sensor data are compared by a comparison unit, and in the pattern inspection apparatus for inspecting the defect of the pattern, the comparison unit, when comparing the reference data and the sensor data, The pattern inspection apparatus is characterized in that the adjacent patterns that have been inspected are compared using the reference data corrected in accordance with the pattern inspection conditions measured in advance.

Further, according to the means of the invention of claim 5,
The film forming step of forming a film on a substrate, the drawing step of drawing a pattern on the film, the sensor data obtained by imaging the pattern, and the reference data obtained from the design data of the pattern are compared and In a mask manufacturing method of manufacturing a mask by performing an inspection step of inspecting a pattern, according to a pattern inspection condition preliminarily measured from an adjacent pattern that has been inspected when the reference data and the sensor data are compared. It is a method of manufacturing a mask, which is characterized by using corrected previous reference data.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a die-to-database pattern defect inspection apparatus according to an embodiment of the present invention. The mask 1, which is the object to be inspected, is held by the XY stage 2, and the XY stage 2 is continuously moved in the X-axis direction by the stage controller 3 and is step-moved in the Y-axis direction.

Mask 1 held on XY stage 2
A light source 4 is disposed above the light source 4, and the light emitted from the light source 4 is applied to the mask 1 as illumination light. Mask 1
A line sensor 5 for picking up an image of the circuit pattern drawn on the mask 1 is arranged below the position of the sensor 1. The sensor data output from the line sensor 5 is given to a comparison device 6 described later.

On the other hand, in synchronization with the transmission of sensor data from the line sensor 5, the position of the XY stage 2 in the X-axis direction and Y.
A stage position measuring device 7 for detecting the axial position by a laser interferometer, a linear encoder, or the like is provided, and the position data measured by the stage position measuring device 7 is introduced into the pattern condition correction device 8.

The pattern condition correction device 8 transmits a timing signal to the reference data generation device 10. In the reference data generator 10, the design pattern data used in CAD when the circuit pattern is formed on the mask 1 is stored in the database 11
When the pattern condition as the timing signal is given from the pattern condition correction device 8, the reference data is output from the design pattern data at that position.

The timing signal is information for correcting the reference data, which is given when the next stripe is inspected based on the steps for detecting the pattern condition and correcting the pattern condition which will be described later. Therefore, the reference data is corrected based on it.

The corrected reference data output from the reference data generator 10 is introduced into the comparator 6 and compared with the sensor data captured by the line sensor 5. As will be described later, the comparison device 6 measures the pattern condition in the X-axis direction at regular intervals. Then, the measurement result is stored in the pattern condition measuring circuit 13 and input to the pattern condition correcting device 8. The reference data is corrected according to the result and applied as the corrected reference data when the next stripe is inspected.

Next, the alignment operation of the pattern inspection apparatus having the above-mentioned structure will be described. First, as shown in FIG. 2A, the circuit pattern drawn on the mask 1 is inspected in strip units each having a constant width in the Y-axis direction. That is, the entire surface of the mask 1 is inspected by continuously moving the XY stage 2 in the X-axis direction and stepwise moving in the Y-axis direction by the width of the strip.

FIG. 2B shows the positional relationship between the scanning range of the line sensor 5, that is, the sensor pattern region 15 and the reference data range, that is, the reference pattern region 16, at the start of the inspection. .

Originally, the two areas 15 and 16 must be the same. However, if the alignment is not performed, there is a displacement as shown in this figure.

As shown in the schematic diagram for explaining the mask inspection method in FIG. 3, in the case of the inspection apparatus using the line sensor 5, the XY stage 2 moves in the lateral direction of the line sensor 5 and the line sensor 5 moves. Images are continuously captured from the edge of the mask 1. At this time, the mask 1 with the width of the line sensor 5
The area from the left end to the right end of is a stripe S, and
Regions obtained by dividing the stripe S are referred to as blocks B, respectively.

The detection and correction of a pseudo defect caused by an error in pattern conditions (position, size, corner rounding, brightness) will be described below.

FIG. 4 is a flow chart showing the steps for detecting the pattern condition and correcting it. The basic idea is that the pattern condition (position, size, corner rounding, brightness) that needs to be corrected at the time of pattern inspection is inspected while being corrected by the correction amount obtained from the adjacent pattern inspected immediately before. It is possible to inspect.
That is, after the inspection is started (S1), when the stripe S is inspected, the pattern conditions (position, size, corner rounding, and brightness) obtained when inspecting the previous stripe S are set (S2). The stripe S is inspected using the set pattern condition (S3). The pattern condition (position, size, corner rounding, brightness) is calculated, and the correction amount of the next stripe S is calculated (S4). As a method of adopting the calculation result of the correction amount in the next inspection of the stripe S, either the stripe S or the block B is selected (S5). Depending on the selection result, the correction value for each stripe S is adopted (S6) or the correction value for each block B is adopted (S7). The process is shifted to the inspection of the next stripe S according to the adoption result of the correction value (S8).

Next, detection of pattern conditions (position, size, corner rounding, brightness) and correction of reference data based on the result will be described. (A) Displacement As shown in the schematic view of FIG. 5A and the sectional profile corresponding to FIG. 5B, the stripe S of the sensor data detected by the line sensor 5 and the X-axis direction of the reference data are shown. Edge positions at both ends of A and B are detected for each of the Y-axis directions, and the centers of the respective data in the X-axis direction and the Y-axis direction are calculated. The centers of the X-axis direction and the Y-axis direction are compared with the reference data and the sensor data, and the positional deviation is detected by the difference between the centers of the X-axis direction and the Y-axis direction of both data. Correct the reference data. (B) Size Further, as shown in the schematic view of FIG. 6A and the cross-sectional profile corresponding to FIG. 6B, the pattern size when a white pattern is formed on a black background is defined as the line width. For example, the line width error of both data can be measured. That is, in FIG. 6B, the line width error from the reference data of the white pattern is detected by the difference between the width Lws of the predetermined portion at both ends of the sensor data and the width Lwr of the corresponding portion of the reference data, and the reference data is detected. To correct.

A schematic diagram is shown in FIG. 7 (a) and FIG. 7 (b).
Even if a black pattern is formed on a white background, the explanation is the same except that white and black are reversed when a white pattern is formed on a black background. . (C) Corner Rounding As shown in the schematic diagram of FIG. 8, the corner rounding (curvature) of the sensor data detected by the line sensor 5 and the reference data is compared. The difference between the curvature (Rr) of the reference data and the curvature (Rs) of the sensor data is calculated to calculate a correction value for the curvature, and the reference data is corrected based on this correction value. (D) Since the laser interferometer is used to detect the position of the stage in which the expansion / contraction rate sensor data is captured, the measured value is as shown in FIG. The data is stretched and needs to be corrected. The expansion / contraction correction method may be performed by calculating the expansion / contraction correction amount for one stripe from the positional deviation amount of all locks B in the stripe S or by calculating the expansion / contraction correction amount for each part of the blocks in the stripe. is there. As shown in FIG. 9B, the expansion / contraction correction amount is obtained for each stripe S from the amount of positional deviation between the sensor data and the reference data for each block B of the stripe S. That is, the amount of positional deviation of each stripe S is sequentially detected for each block B, and the expansion / contraction correction amount between blocks is obtained. The reference data is corrected from the calculated expansion / contraction correction amount of the stripe S. (E) Luminance As shown in FIG. 10, the stripe length (Ls) of the sensor data detected by the line sensor 5 is compared with the stripe length (Lr) of the corresponding reference data, and the difference between both stripe lengths is compared. The expansion / contraction ratio (Ls / Lr) is calculated based on the above to correct the reference data.

The signal intensity gradually decreases as the pattern size of the sensor data decreases. For example, in the case of a white square pattern with a side of 0.7 μm, the maximum value is 85%.
To a certain extent. Therefore, in consideration of the decrease,
The signal intensity of the reference data is multiplied by a constant coefficient to correct the maximum value of the signal intensity. The coefficient to be corrected by this reference data may be obtained in advance by an experiment such as optical simulation for each pattern size, set in a lookup table, and the correction coefficient may be selected according to the size of the reference pattern.

It is not necessary to detect all of these pattern conditions (position, size, corner rounding, brightness) in an actual inspection apparatus and correct them according to these conditions. It is sufficient to use one.

Using these, the mask 1 which is the object to be inspected
When the inspection is performed, a pseudo defect due to an error in the pattern condition does not occur, and thus stable and highly accurate mask 1 inspection can be performed.

In the above case, the inspection was performed by comparing with the reference data by a die-to-database, but the die-to-die (die-
To-die) can also be performed. In that case,
As shown in FIG. 1, two (plural) light sources 4 and the like are arranged with respect to the XY stage 2, and the mask 1 as the inspection object has two
A pattern formed on the masks 1a and 1b in a repetitive pattern such as individual patterning is targeted, and by comparing the data of the masks 1a and 1b, a difference can be detected and an inspection can be performed.

If the object to be inspected is a non-transparent material such as a wafer for the light, it is necessary to measure the reflected light. Therefore, in the block diagram of the pattern inspection apparatus shown in FIG. The position of the sensor 5 may be set to a position where the reflected light from the wafer can be received.

Next, a method of manufacturing a hard mask using the above inspection method will be described. FIG. 12 is a flowchart showing the hard mask manufacturing process.

In the hard mask 1, except for the relief effect of the soft mask 1, in order to overcome the weak film strength, an image of a metal or metal oxide layer is formed on a glass substrate to form a photomask. . First, the glass substrate is polished and washed (S11), and a chromium film having a predetermined thickness is formed on the glass substrate by a sputtering method during vacuum deposition (S12). Next, a photoresist having a resist film thickness of usually 0.4 to 0.8 μm is applied (S13), prebaked (S14), and then exposed according to the pattern to be formed (S15). Then, development is performed by a spray method or an immersion method using an automatic developing device or the like (S16). Post-baking is performed after development (S17).
In this post-baking, when the temperature is too high, the resist causes a plastic flow (softening phenomenon) and changes in shape, so that the temperature and time settings must be carefully controlled. next,
Etching is performed (S18). For the etching, the wet method is easy to use if a dipping method is used, but there is a drawback that the undercut is 0.5 μm or more and the dimension of the image line is narrower than the resist line width. A dry etching method such as sputter etching is often used. Next, the resist is peeled off (S
19) After that, cleaning is performed and each inspection is performed (S2).
0). For the pattern inspection at that time, the above-described pattern inspection of the present invention is used. After that, if there is a defective part, it is corrected (S2
1) After the correction, the product is cleaned and shipped (S22). The above manufacturing process is an example, and various modified processes can be used for manufacturing. As described above, in the above-described embodiment, the pattern condition (position, size, corner rounding, brightness) that needs correction for each inspection of one stripe is inspected immediately before the pattern inspection of the non-inspection body. Since the inspection is performed while correcting with the correction amount obtained from the adjacent pattern, the defect of the inspection due to the pseudo defect can be eliminated and the defect detection sensitivity can be improved, and the mask and the wafer can be inspected with high accuracy.

Further, it is not necessary for the inspection apparatus operator to preset the correction amount of the delicate pattern condition for each mask, which saves manpower and time. Also,
The inspection can be automated, and a mask inspection method capable of continuous automatic inspection and a mask manufacturing method using the same can be realized.

In the above-described embodiment, the mask used in the semiconductor manufacturing process is exemplified as the inspection object, but the invention is not limited to the mask and may be applied to the wafer or the like as the inspection object. it can.

[0040]

According to the present invention, it is possible to continuously and automatically inspect an object to be inspected such as a mask with high accuracy.

Moreover, a highly productive mask manufacturing method can be realized.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a pattern inspection apparatus of the present invention.

2A and 2B are explanatory views of a positioning operation of the pattern inspection apparatus.

FIG. 3 is a schematic diagram illustrating a mask inspection method.

FIG. 4 is a flowchart showing steps for detecting a pattern condition and correcting the pattern condition.

FIG. 5A and FIG. 5B are explanatory views for detecting a pattern condition.

FIG. 6A and FIG. 6B are explanatory diagrams of detection of pattern conditions.

FIG. 7A and FIG. 7B are explanatory views for detecting a pattern condition.

FIG. 8 is an explanatory diagram of detection of a pattern condition.

FIG. 9 is an explanatory diagram of detection of a pattern condition.

FIG. 10 is an explanatory diagram of detection of a pattern condition.

FIG. 11 is an explanatory diagram of a two-piece mask.

FIG. 12 is a flowchart showing a hard mask manufacturing process.

[Explanation of symbols]

1, 1a, 1b ... Mask, 2 ... XY stage, 5 ... Line sensor, 6 ... Comparison device, 7 ... Position measuring device, 8 ... Stage position correcting device, 13 ... Pattern condition measuring circuit

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) G06T 1/00 305 G06T 1/00 305A 5B057 7/00 300 7/00 300E 5L096 H01L 21/027 H01L 21/66 J 21 / 66 21/30 502P (72) Hiroshi Inoue 33, Shinisogo-cho, Isogo-ku, Yokohama MM03 PP12 QQ38 2F069 AA03 AA31 AA49 AA53 AA60 BB15 CC06 DD16 GG07 GG72 JJ14 2G051 AA56 AB02 CA03 DA07 EA11 EA12 EA14 EA16 EB01 CA08 CA03 CA02 DA03 CA07 DB02 CA02 DB03 CA02 DA02 DB5 CA10 A02

Claims (5)

[Claims] 1. A pattern inspection method for inspecting a defect of a pattern by comparing reference data of a pattern of an object to be inspected with sensor data, and comparing the reference data with the sensor data by the comparing means. A pattern inspection method characterized by using the previous period reference data corrected by the pattern inspection condition measured in advance from the adjacent pattern which has been inspected. 2. The pattern inspection method according to claim 1, wherein the pattern condition uses at least one of position, size, corner rounding, and brightness. 3. The pattern inspection method according to claim 1, wherein the pattern condition measured from the adjacent pattern for which the inspection is completed is stripe or block. 4. A pattern inspection apparatus for comparing reference data of a pattern of an object to be inspected with sensor data by a comparison means, and inspecting a defect of the pattern, wherein the comparison means compares the reference data and the sensor data. In the pattern inspection apparatus, the reference data is compared with the previous period reference data corrected by a pattern inspection condition measured in advance from an adjacent pattern that has been inspected. 5. A film forming step of forming a film on a substrate, a drawing step of drawing a pattern on the film, sensor data obtained by imaging the pattern, and reference data obtained from design data of the pattern. In the mask manufacturing method of manufacturing a mask by performing an inspection process of comparing the reference data with the sensor data, the reference data used when comparing the reference data with the sensor data is A method for manufacturing a mask, characterized in that the reference data corrected based on a pattern inspection condition previously measured from the pattern to be used is used.