Numerically compensating SEM-induced charging using diffusion-based model
Systems and methods for image enhancement are disclosed. A method for enhancing an image may include acquiring a scanning electron microscopy (SEM) image. The method may also include simulating diffused charge associated with a position of the SEM image. The method may further include providing an enhanced SEM image based on the SEM image and the diffused charge.
1. A method for enhancing an image, the method comprising:
acquiring a scanning electron microscopy (SEM) image of a sample;
simulating a SEM-induced charging effect associated with a position of the SEM image, wherein the simulated SEM-induced charging effect comprises a simulated diffused charge accumulated on or near a surface of the sample induced by an electron beam scanning over the surface of the sample; and
providing an enhanced SEM image based on the SEM image and the simulated SEM-induced charging effect.
2. The method of claim 1 , wherein acquiring the SEM image comprises:
acquiring the SEM image by scanning a surface of a sample.
3. The method of claim 1 , wherein acquiring the SEM image comprises:
receiving the SEM image from a database.
4. The method of claim 1 , wherein the SEM image comprises a pattern of a structure at the position of the SEM image, and the pattern comprises a SEM-induced charging artifact.
5. The method of claim 1 , further comprising:
after acquiring the SEM image, extracting a pattern from the SEM image.
6. The method of claim 5 , wherein a pattern comprises a contour.
7. The method of claim 5 , wherein the pattern is associated with a height change on the surface of the sample.
8. The method of claim 5 , wherein extracting the pattern from the SEM image comprises:
extracting the pattern as pixels of the SEM image, wherein pixel values of the pixels satisfy a threshold condition, and wherein the threshold condition comprises a pixel brightness value above or below a predetermined value or within a predetermined range, or a pixel location within an edge bloom region.
9. The method of claim 1 , wherein simulating the SEM-induced charging effect associated with the position of the SEM image comprises:
determining a first model, wherein the first model is based on movement of the diffused charged induced by the SEM-induced charging effect at the position; and
applying the first model to the SEM image to simulate the SEM-induced charging effect.
10. The method of claim 1 , wherein simulating the SEM-induced charging effect associated with the position of the SEM image comprises:
simulating the diffused charged based on a diffusing charge distribution and a duration of the electron beam illuminating the position, wherein the position is in a scanning path of the electron beam of the SEM, and the diffusing charged distribution comprises a diffusion coefficient.
11. The method of claim 10 , wherein the diffusing charge distribution is one of a one-dimensional diffusing charge distribution, a two-dimensional diffusing charged distribution, or a three-dimensional diffusing charge distribution.
12. The method of claim 11 , wherein a dimension of the one-dimensional diffusing charged distribution is substantially parallel with a direction of the scanning path.
13. The method of claim 1 , wherein simulating the SEM-induced charging effect associated with the position of the SEM image comprises:
determining a second model, wherein the second model is based on a charge density of the diffused charge induced by the SEM-induced charging effect at the position and a weighting of the charged density; and
applying the second model to the SEM image to simulate the SEM-induced charging effect.
14. The method of claim 1 , wherein simulating the SEM-induced charging effect associated with the position of the SEM image comprises:
determining, for a set of positions of the SEM image, charge density values and weight values associated with the set of positions; and
simulating the diffused charge at the position by performing a convolution of the charge density values and the weight values at the position.
15. An inspection system, comprising:
a memory storing a set of instructions; and
a processor configured to execute the set of instructions to cause the inspection system to:
acquire a scanning electron microscopy (SEM) image of a sample;
simulate a SEM-induced charging effect associated with a position of the SEM image, wherein the simulated SEM-induced charging effect comprises a simulated diffused charge accumulated on or near a surface of the sample induced by an electron beam scanning over the surface of the sample; and
provide an enhanced SEM image based on the SEM image and the simulated SEM-induced charging effect.