JPH11345754A - Inspection method for semiconductor device and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To judge the difference in the cross-sectional shape of a semiconductor device using the waveform of a secondary electronic signal obtained by scanning the semiconductor device with an electron beam. SOLUTION: The reference pattern cross-sectional shape S1 of a semiconductor device having a reference shape is scanned with an electron beam to produce a waveform S2 of a secondary electronic signal. On the other hand, the evaluation pattern cross-sectional shape E1 of a semiconductor device to be evaluated is scanned with an electron beam to produce a waveform E2 of a secondary electronic signal. Similarity of the waveforms S2, E2 of secondary electronic signal is then determined by numerization. The pattern has a cross-sectional shape similar to that of a reference semiconductor device if the waveform similarity of the semiconductor device to be evaluated is not less than a specified value, otherwise the pattern has a different cross-sectional shape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of inspecting a semiconductor device with high accuracy by scanning a semiconductor device with an electron beam and judging a difference in the shape of the semiconductor device by using an obtained secondary electron signal waveform. And a manufacturing method.

[0002]

2. Description of the Related Art In recent years, a method of scanning a semiconductor device with an electron beam and measuring a pattern width of the semiconductor device using an obtained secondary electron signal waveform has been generally used as an evaluation of fine processing of the semiconductor device. Has been used. This method is increasingly required for a process that is further complicated by miniaturization, and is an indispensable technique for evaluating a two-dimensional processed shape.

[0003]

However, the information obtained by the above-mentioned conventional method is two-dimensional width measurement information.
No information in the height direction could be obtained. Therefore 3
It was not used for dimensional shape determination.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and provides a semiconductor device inspection method and a semiconductor device manufacturing method for judging a difference in cross-sectional shape of a semiconductor device by using an obtained secondary electron signal waveform. The purpose is to provide.

[0005]

In order to achieve this object, a method for inspecting a semiconductor device and a method for manufacturing the same according to the present invention provide a method of manufacturing a semiconductor device, comprising the steps of: The fact that the shape of the signal waveform also changes is used. A secondary electron signal waveform obtained by scanning an electron beam on a semiconductor device having a reference shape is stored, and the degree of similarity of the secondary electron signal waveform of the semiconductor device is evaluated with respect to the stored secondary electron signal waveform. By comparing, the difference in the shape of the semiconductor device is determined.

[0006] According to this method, a conventional secondary electron signal waveform obtained by scanning an electron beam on a semiconductor device is used.
In addition to the dimensional width information, it is possible to easily determine the difference in the shape of the three-dimensional semiconductor device. In the prior art, it is impossible to detect a difference in a pattern having the same width and a different inclination of the side wall during the process. But,
2 for the change in the sectional shape of the semiconductor device in the present invention
By using a method of quantifying the change in the waveform of the next electron signal to determine, it is possible to detect patterns having the same width and different sidewall inclinations as having different shapes. As a result, finer processing with higher accuracy and less variation can be realized, and process management is indispensable for further miniaturization.

[0007]

(First Embodiment) A first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram for explaining a semiconductor device inspection method according to the present invention, in which a difference in the shape of a semiconductor device is determined by recognizing a secondary electron signal waveform. FIG.
In the semiconductor device having the reference shape,
Is the cross-sectional shape of the reference pattern, and S2 is the secondary electron signal waveform of the reference pattern. In the semiconductor device to be evaluated with respect to the semiconductor device having the reference shape, E1 is a cross-sectional shape of the evaluation pattern E, and E2 is a secondary electron signal waveform of the evaluation pattern. R is a numerical value representing the similarity between the secondary electron signal waveform S2 of the reference pattern and the secondary electron signal waveform E2 of the evaluation pattern.

In the present embodiment, an electron beam is scanned over a cross-sectional shape S1 of a reference pattern of a semiconductor device having a reference shape, and an obtained secondary electron signal waveform S2 is stored as reference waveform information. Next, a secondary electron signal waveform E2 is obtained by scanning an electron beam on the sectional shape E1 of the evaluation pattern of the semiconductor device to be evaluated. Here, the reference secondary electron signal waveform S2
The secondary electron signal waveform E2 is evaluated by performing a differentiation process or an integration process on the secondary electron signal waveform E2 to evaluate the difference in the shape of the secondary electron signal waveform. The waveform similarity R with respect to the secondary electron signal waveform S2 is numerically obtained. At this time, the waveform similarity R can be expressed by the following equation.

R = r (E2 / S2) (r is a constant) If the waveform similarity R of the semiconductor device to be evaluated is a certain value or more, it is a pattern having the same cross-sectional shape as the reference semiconductor device. If the waveform similarity R is equal to or less than a predetermined value, the pattern has a cross-sectional shape different from that of the reference semiconductor device.

According to this embodiment, the shape of the three-dimensional semiconductor device can be grasped by comparing the similarity of the secondary electron signal waveforms obtained by scanning the semiconductor device with an electron beam. And the quality of the shape can be easily quantified and determined.

Next, the case where the present invention is used for determining the shape of a resist pattern will be described with reference to the drawings.
FIG. 2 illustrates a method of manufacturing a semiconductor device according to the present invention, in which the similarity of secondary electron signal waveforms is compared and the resist is regenerated when the similarity is less than a certain value in the resist pattern forming step. FIG.

In FIG. 2, the normal cross-sectional shape in the resist pattern forming step has a waveform similarity R of k (constant value) or more. An electron beam is scanned over the evaluation pattern, and if the waveform similarity R of the obtained secondary electron signal waveform is equal to or greater than k, it is determined that a normal resist pattern has been formed, and the next step of semiconductor manufacturing processing is performed. If the waveform similarity R of the obtained secondary electron signal waveform is less than k, it is determined that an abnormal resist pattern has been formed, and the resist is regenerated.

According to the present embodiment, a method of manufacturing a semiconductor device which enables a more accurate three-dimensional shape determination in the resist pattern formation process from the conventional two-dimensional width only determination in the resist pattern formation process. It is.

The high-precision fine processing method using this method will be described in more detail with reference to FIG. FIG. 3 is a diagram illustrating a comparison between a conventional method and the case where the present invention is used in a fine processing step of etching a base film using a resist pattern as a mask.

In FIG. 3, reference numeral 11 denotes a cross-sectional shape of the resist pattern in sample A, and reference numeral 12 denotes a cross-sectional shape of the resist pattern in sample B. As a result of scanning the resist pattern of these samples with an electron beam, 21 is a secondary electron signal waveform of the resist pattern in sample A, and 22 is a sample B
5 shows a secondary electron signal waveform of the resist pattern in FIG.
The widths of the resist patterns of Sample A and Sample B obtained from the secondary electron signal waveforms are such that W1 is 0.3 μm in the resist pattern size of Sample A and W2 is 0.3 μm in the resist pattern size of Sample B.

When the resist patterns of the samples A and B are judged based on the conventional two-dimensional width information, the pattern size can be determined to be 0.3 μm and the same finish can be judged, and the etching process is performed as the next step. Reference numeral 14 denotes the cross-sectional shape of the etching pattern in the sample A and the etching pattern dimension W4 is 0.3 μm, and reference numeral 15 denotes the cross-sectional shape of the etching pattern in the sample B and the etching pattern dimension W5 is 0.25 μm. In Sample A, the cross-sectional shape of the 11 resist patterns has a vertical shape, and the resist pattern is etched to be the same as the resist dimensions by performing etching in a faithful manner. However, in Sample B, the cross-sectional shape of the 12 resist patterns has an inclination, and the bottom dimension of the cross section is 0.3 μm, but the top dimension is small. When the resist pattern 12 having the cross-sectional shape having this inclination is etched, the etching proceeds to the base film because the resist is thin at the bottom portion, and the dimension after the etching is smaller than the resist dimension by 0.25 μm.
And a CD loss occurs. In the conventional method,
Finished dimensions after etching are: W4 = 0.3 μm, W
5 = 0.25 μm, which naturally causes variations in characteristics.

On the other hand, the present invention uses not only two-dimensional width information,
By incorporating the determination of the three-dimensional cross-sectional shape, the processing accuracy of the cross-sectional shape of the resist pattern is increased, and as a result, the characteristics are intended to be stabilized.

In the present invention, when judging the finish of the resist pattern of the sample A and the sample B, the width of the resist pattern and the waveform similarity of the secondary electron signal waveform are compared based on the secondary electron signal waveform. R1 is the waveform similarity of the resist pattern in sample A, and R2 is the waveform similarity of the resist pattern in sample B. Here, the criterion for determining the waveform similarity in the resist pattern forming step is k or more. Sample A has a resist pattern dimension W1 = 0.3 μm,
Since the waveform similarity R1 ≧ k, the etching process in the next step may be performed. 14 is the cross-sectional shape of the etching pattern in sample A, and W4 is the etching pattern dimension in sample A of 0.3 μm. On the other hand, the sample B has the resist pattern dimension W2 = 0.3 μm, but since the waveform similarity R2 <k, the resist pattern forming process is performed again after the resist is reproduced as an abnormal pattern. Reference numeral 13 denotes a cross-sectional shape of the resist pattern of the sample B after the resist regenerating process, and reference numeral 23 denotes a secondary electron signal waveform of the resist pattern of the sample B after the resist regenerating process. Here, in the sample B on which the resist pattern forming process was performed again, W3 is a resist pattern dimension after the resist regenerating process, and R3 is a waveform similarity k of the resist pattern after the resist regenerating process. The resist pattern shape here is such that the resist pattern dimension W3 = 0.
3 μm and the waveform similarity R3 ≧ k, which is a determination result that the next etching process may be performed. Reference numeral 16 denotes a cross-sectional shape of the etching pattern in the sample B, and W6 denotes an etching pattern dimension in the sample B of 0.3 μm. The cross-sectional shape 13 of the sample B after the re-formation of the resist pattern determined from the resist pattern dimension W3 and the waveform similarity R3 has the same shape as the cross-sectional shape 11 of the resist pattern of the sample A. Is the same finish as W4 = 0.3 μm for sample A and W6 = 0.3 μm for sample B.

According to the present embodiment, it is possible to make the variation in the finished dimensions after processing extremely small, so that fine processing with higher accuracy and less variation can be realized for miniaturization of the process. As a result, stable device characteristics can be obtained.

(Embodiment 2) Next, a second embodiment of the present invention will be described with reference to the drawings. FIG.
Is a waveform that stores the change of the secondary electron signal waveform with respect to the focus fluctuation of the exposure apparatus, and stores the similarity of the secondary electron signal waveform obtained from the pattern obtained by performing the preceding exposure for only one slice from the lot (50 slices). , The amount of deviation from the best focus at the time of the preceding exposure is estimated, and the result is fed back to the focus correction of the main body exposure of the remaining 49 slices of the lot.

In FIG. 4, the focus setting value of the exposure apparatus is set to B when the best focus is set, B when the focus surface is in the lower direction of the pattern = (B + α), and when the focus surface is in the upper direction of the pattern = (B−β). . In the resist pattern forming step, a1 is the cross-sectional shape of the exposure device focus setting value = (B + α), a2 is the secondary electron signal waveform obtained by scanning the cross-sectional shape a1 with an electron beam, and b1 is the focus setting value of the exposure device. = Section shape of best focus, b
2 is a secondary electron signal waveform obtained by scanning the sectional shape b1 with an electron beam, and c1 is a focus set value of the exposure apparatus = (B−
The cross-sectional shape of β), c2, is a secondary electron signal waveform obtained by scanning the cross-sectional shape c1 with an electron beam.

In this embodiment, the focus fluctuation of the exposure apparatus [focus setting value: (B + α) to (B-β)]
Of the secondary electron signal waveform with respect to [secondary electron signal waveform:
a2 to c2] are stored in a table. Based on the stored information, the amount of deviation of the best focus of the previously exposed pattern is estimated and fed back to the main body exposure.

This will be described in detail with reference to FIG. In FIG. 5, P1 is a cross-sectional shape of the pre-exposed pattern, and P2 is a secondary electron signal waveform obtained by scanning the cross-sectional shape P1 with an electron beam.

In this embodiment, the secondary electron signal waveform P2 obtained from the pattern P1 previously exposed by the exposure device is
The closest signal waveform is recognized based on the change in the secondary electron signal waveform stored in FIG. 4 [secondary electron signal waveform: a2 to c2]. Here, the secondary electron signal waveform a2 in FIG. 4 has the waveform shape most similar to the secondary electron signal waveform P2 of the preceding exposure pattern. Then, it can be estimated that the focus of the preceding exposure pattern is shifted by (α) from the best focus, and the focus of the exposure apparatus is corrected by (−α) with respect to the set value at the time of the preceding exposure. Perform body exposure. As a result, the cross-sectional shape obtained with the best focus can be realized in the main body exposure.

According to the present embodiment, it is possible to feed back the shift amount of the focus of the preceding exposure to the main body exposure by using the change of the secondary electron signal waveform with respect to the focus change of the exposure apparatus, and it is impossible to perform the conventional correction. It is possible to suppress the fluctuation of the focus of the exposure apparatus which did not exist. As a result, a very high-precision microfabrication technique becomes possible, and this is a method for manufacturing a semiconductor device capable of manufacturing a device having stable characteristics.

[0027]

According to the present invention, not only the conventional two-dimensional width information but also the change in the shape of the secondary electron signal waveform is obtained by using the secondary electron signal waveform obtained by scanning the semiconductor device with an electron beam. By numerically expressing the semiconductor device, it is possible to realize a semiconductor device inspection method capable of easily performing a three-dimensional shape determination of a semiconductor device and a semiconductor device manufacturing method capable of performing highly accurate fine processing. is there.

According to the present invention, it is possible to obtain a stable processed shape in a semiconductor process having many unstable elements with respect to daily environmental changes, and as a result, it is possible to maintain stable device characteristics against further miniaturization. It is possible to secure a high yield.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a semiconductor device inspection method according to a first embodiment of the present invention;

FIG. 2 is an explanatory diagram of a method for manufacturing a semiconductor device according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating a method of manufacturing the semiconductor device according to the first embodiment of the present invention.

FIG. 4 is a diagram illustrating a method of manufacturing a semiconductor device according to a second embodiment of the present invention.

FIG. 5 is a diagram illustrating a method of manufacturing a semiconductor device according to a second embodiment of the present invention.

[Explanation of symbols]

S1 Cross-sectional shape of reference pattern S2 Secondary electron signal waveform of reference pattern E1 Cross-sectional shape of evaluation pattern E2 Secondary electron signal waveform of evaluation pattern R Waveform similarity 11 Cross-sectional shape of resist pattern in sample A 12 Resist pattern in sample B Cross-sectional shape 13 Cross-sectional shape of resist pattern in sample B after resist regenerating treatment 14 Cross-sectional shape of etching pattern in sample A 15 Cross-sectional shape of etching pattern according to prior art in sample B 16 Cross-sectional shape of etching pattern according to the present invention in sample B 21 Secondary electron signal waveform of resist pattern in sample A 22 Secondary electron signal waveform of resist pattern in sample B 23 Secondary electron signal waveform of resist pattern in sample B after resist regeneration processing W1 Register in sample A Pattern size W2 Resist pattern size of sample B W3 Resist pattern size of sample B after resist regeneration treatment W4 Etch pattern size of sample A W5 Etch pattern size of sample B according to prior art W6 Etch pattern size of sample B according to the present invention R1 R2 Waveform similarity of resist pattern in sample A R2 Waveform similarity of resist pattern in sample B R3 Waveform similarity of resist pattern in sample B after resist regeneration processing a1 Cross-sectional shape when exposure apparatus focus (B + α) is set a2 Cross-sectional shape a1 B1 Cross-sectional shape at exposure apparatus focus (best focus) b2 Secondary electron signal waveform at cross-section shape b1 c1 Cross-sectional shape at exposure apparatus focus (B-β) setting c2 Cross-sectional shape Secondary electron signal waveform P1 prior exposure pattern cross-sectional shape P2 prior exposure pattern of the secondary electron signal waveform at 1

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Claims (3)

[Claims] An inspection method of a semiconductor device using an electron beam scanned on a semiconductor device and using an obtained secondary electron signal waveform, wherein a reference is made to a secondary electron signal waveform obtained from a semiconductor device having a reference shape. Accumulating as waveform information, accumulating a secondary electron signal waveform obtained from the semiconductor device to be evaluated as evaluation waveform information, and quantifying the similarity of the evaluation waveform information with respect to the reference waveform information for comparison And a step of determining a difference in shape of the semiconductor device. 2. In a resist pattern forming step, similarity between evaluation waveform information, which is a secondary electron signal waveform based on a pattern to be evaluated, and reference waveform information, which is a secondary electron signal waveform based on a reference pattern, is quantified. Compare
A method of manufacturing a semiconductor device, comprising: determining a reproduction of a resist when the value is equal to or less than a predetermined value. 3. A first step of accumulating a change in a secondary electron signal waveform with respect to a focus change of an exposure device, and a step of converting a secondary electron signal waveform obtained from a previously exposed pattern into the first electron signal waveform.
A second step of recognizing a secondary electron signal waveform having the highest similarity in the step of; and estimating a shift amount from a best focus in a pattern in which the secondary electron signal waveform having the highest similarity is obtained; A third step of feeding back the amount to the focus correction of the main body exposure.