Manufacturing method for a semiconductor device, pattern generating method and nontransitory computer readable medium storing a pattern generating program
According to one embodiment, stepped structure is formed on a semiconductor substrate, a processing film is formed to cover the stepped structure, a resist film is formed on the processing film in such a manner as to be thinner at a higher portion of the stepped structure than at a lower portion of the same, and the resist film and the processing film are etched to flatten the processing film.
1. A computer-implemented pattern generating method, comprising:
acquiring step information that is actual measurement values of a stepped structure corresponding to a layout pattern specified by designed layout data;
calculating by computer, based on the step information, a film thickness distribution of a resist film such that a film thickness of the resist film at a higher portion of the stepped structure is thinner than a film thickness of the resist film at a lower portion of the stepped structure;
acquiring an effective transmission rate distribution of an exposure mask according to the film thickness distribution of the resist film,
calculating by computer, a crude density distribution of a light-shielding pattern of the exposure mask according to the effective transmission rate distribution;
changing the layout pattern to acquire the crude density distribution of the light-shielding pattern;
generating mask data corresponding to the changed layout pattern; and forming a semiconductor device using the generated mask data.
2. The pattern generating method of claim 1 , wherein a crude density of the light-shielding pattern is given with a pattern pitch of a resolution limit or less.
3. The pattern generating method of claim 1 , further comprising:
registering a relationship between an etch rate of the resist film and an etch rate of a processing film covering the stepped structure by each gas type; and
registering a relationship between the effective transmission rate of the exposure mask and a residual film of the resist film.
4. The pattern generating method of claim 3 , wherein, in the acquiring of the effective transmission rate distribution, the residual film of the resist film is calculated from the relationship between the etch rate of the resist film and the etch rate of the processing film and the height difference in the stepped structure, and the effective transmission rate of the exposure mask is calculated from the residual film of the resist film.
5. The pattern generating method of claim 4 , wherein,
when the etch rate of the resist film is designated as X, the etch rate of the processing film as Y, the film thickness of the resist film at a lower portion of the stepped structure as T 1 , the film thickness of the processing film at a higher portion of the stepped structure as T 2 , and the film thickness of the resist film at the higher portion of the stepped structure as T 3 ,
the relationship T 1 ×X=T 2 ×Y+T 3 ×X is satisfied.
6. A nontransitory computer readable storage medium storing a pattern generating program to cause a computer to execute:
acquiring step information that is actual measurement values of a stepped structure corresponding to a layout pattern specified by designed layout data;
calculating by computer, based on the step information, a film thickness distribution of a resist film such that a film thickness of the resist film at a higher portion of the stepped structure is thinner than a film thickness of the resist film at a lower portion of the stepped structure;
acquiring an effective transmission rate distribution of an exposure mask according to the film thickness distribution of the resist film;
calculating by computer, a crude density distribution of a light-shielding pattern of the exposure mask according to the effective transmission rate distribution;
changing the layout pattern to acquire the crude density distribution of the light-shielding pattern;
generating mask data corresponding to the changed layout pattern; and forming a semiconductor device using the generated mask data.
7. The nontransitory storage medium of claim 6 , wherein a crude density of the light-shielding pattern is given with a pattern pitch of a resolution limit or less.
8. The nontransitory storage medium of claim 7 , wherein the pattern generating program causes the computer to execute:
registering a relationship between an etch rate of the resist film and an etch rate of a processing film covering the stepped structure by each gas type; and
registering a relationship between an effective transmission rate of the exposure mask and a residual film of the resist film.
9. The nontransitory storage medium of claim 8 , wherein, in the acquiring of the effective transmission rate distribution, the residual film of the resist film is calculated from the relationship between the etch rate of the resist film and the etch rate of the processing film and the height difference in the stepped structure, and the effective transmission rate of the exposure mask is calculated from the residual film of the resist film.