Method and apparatus for monitoring cross-sectional shape of a pattern formed on a semiconductor device
View Patent ↗To enable SEM-based management of a cross-sectional shape or manufacturing process parameters of a semiconductor device pattern to be measured, the association between the shape or parameters and SEM image characteristic quantities effective for estimating the shape or parameters is saved as learning data. The image characteristic quantities are collated with learning data to estimate the shape or to monitor the process parameters. Accuracy and reliability is achievable by calculating three kinds of reliability (reliability of the image characteristic quantities, reliability of estimation engines, and reliability of estimating results) based on the distribution of the image characteristic quantities and then judging whether additional learning is necessary, or selecting and adjusting image characteristic quantities and estimation engine based on the reliability.
1. A method for monitoring a semiconductor manufacturing process, comprising the steps of;
acquiring a SEM image of a target pattern formed on a sample by using a SEM image acquisition unit;
calculating feature quantities of textures which indicate a shape of a frequency distribution of signal strength of the target pattern by using a calculation unit; and
estimating a state of the target pattern from the calculated feature quantities by referring a database which is created in advance and which indicates a relationship between an image characteristic quantities based on textural analysis at the top of the pattern and a measured data by using an estimating unit.
2. The method according to claim 1 , wherein in the step of estimating, the state of the target pattern is estimated by using an estimating unit by referring the database which is created in advance in association with the image characteristic quantities based on textural analysis at the top of the pattern obtained from a SEM image of a second sample and a data obtained from measuring the second sample.
3. The method according to claim 1 , wherein in the step of calculating, the image characteristic quantities based on textural analysis at the top of the pattern are calculated by the calculation unit by estimating a frequency distribution of intensity signals of the SEM image of the target pattern, and quantifying the estimated frequency distribution.
4. The method according to claim 1 , wherein in the step of acquiring, a SEM image of a target pattern formed on a sample is acquired by using the SEM image acquisition unit which is on a process of a semiconductor processing in which a predetermined process is completed to form the pattern on the sample.
5. The method according to claim 2 , wherein the feature quantities of the textures obtained from the SEM image of the second sample by using the calculation unit are obtained from SEM images of patterns formed on the second sample which are at least one of having different cross-sectional shapes, being formed by different processing conditions, and having different device characteristics.
6. The method according to claim 1 , wherein in the step of estimating, the measured data is obtained from measuring at least one of cross-sectional shapes of patterns, processing conditions and device characteristics by using the estimation unit.
7. The method according to claim 1 , wherein in the step of estimating, at least one of cross-sectional shapes of the target pattern, processing conditions, and device characteristics is estimated by checking the image characteristic quantities based on textual analysis at the top of the pattern calculated in the calculating step to the database which indicates the relationship between an image characteristic quantities based on textural analysis at the top of the pattern and a measured data.
8. An apparatus for monitoring a semiconductor manufacturing process, comprising:
SEM image acquisition unit which acquires a SEM image of a target pattern formed on a sample;
calculating unit which calculates feature quantities of textures which indicate a shape of a frequency distribution of signal strength of the target pattern; and
estimating unit which estimates a state of the target pattern from the calculated feature quantities by referring a database which is created in advance and which indicates a relationship between an image characteristic quantities based on textural analysis at the top of the pattern and a measured data.
9. The apparatus according to claim 8 , wherein in the estimating unit, the state of the target pattern is estimated by referring the database which is created in advance in association the image characteristic quantities based on textural analysis at the top of the pattern obtained from a SEM image of a second sample and a data obtained from measuring the second sample.
10. The apparatus according to claim 8 , wherein in the calculating unit, the image characteristic quantities based on textural analysis at the top of the pattern are calculated by estimating a frequency distribution of intensity signals of the SEM image of the target pattern, and quantifying the estimated frequency distribution.
11. The apparatus according to claim 8 , wherein in the SEM image acquiring unit, a SEM image of a target pattern formed on a sample is acquired which is on a process of a semiconductor processing in which a predetermined process is completed to form the pattern on the sample.
12. The apparatus according to claim 9 , wherein the image characteristic quantities based on textural analysis at the top of the pattern obtained from SEM image of a second sample are obtained from SEM image of patterns formed on the second sample which are at least one of having different cross-sectional shapes, being formed by different processing conditions, and having different device characteristics.
13. The apparatus according to claim 8 , wherein the estimating unit, the measured data is obtained from measuring at least one of cross-sectional shapes of patterns, processing conditions and device characteristics.
14. The apparatus according to claim 8 , wherein the estimating unit, at least one of cross-sectional shapes of the target pattern, processing conditions, and device characteristics is estimated by checking the image characteristic quantities based on textural analysis at the top of the pattern calculated in the calculating step to the database which indicates the relationship between an image characteristic quantities based on textual analysis at the top of the pattern and a measured data.