Photomask, focus measurement apparatus and focus measurement method

A focus measurement apparatus comprising:

• a photomask including a Fresnel zone pattern with light condensing effect by diffraction, an exposure-dose amount of the Fresnel zone pattern to a transfer object varying in dependence on a focus variation;
• a memory storing data indicating a relation between a film thickness of a resist film being the transfer object from the Fresnel zone pattern obtained using said photomask and a focus variation amount;
• and
• a focus variation amount specifying unit specifying the focus variation amount by making use of a fact that the exposure-dose amount to a resist film depends on the focus variation and the film thickness of the resist film after development process depends on the exposure-dose amount and by checking a measured film thickness value of the resist film with the data stored in said memory.

A focus measurement apparatus comprising:

• a photomask including a Fresnel zone pattern with light condensing effect by diffraction formed thereon, an exposure-dose amount of the Fresnel zone pattern to a transfer object varying in dependence on a focus variation;
• an exposure-dose amount measurement unit measuring the exposure-dose amount from the Fresnel zone pattern;
• a memory storing data indicating a relation between the exposure-dose amount obtained using said photomask and said exposure-dose amount measurement unit and a focus variation amount;
• and
• a focus variation amount specifying unit specifying the focus variation amount by making use of a fact that the exposure-dose amount from the Fresnel zone pattern depends on the focus variation and by checking a measured value of the exposure-dose amount by said exposure-dose amount measurement unit with the data stored in said memory.

A focus measurement method comprising:

• using a photomask including a first mask pattern with light condensing effect of which exposure-dose amount to a transfer object varies in dependence on a focus variation and a second mask pattern for size measurement formed to be projected to a light condensed portion of the first mask pattern when exposed;
• storing data indicating a relation between a size of a transferred pattern of the second mask pattern obtained using said photomask and a focus variation amount, in a memory;
• and
• specifying the focus variation amount while making use of a fact that the size of the transferred pattern of the second mask pattern varies caused by variation in the exposure-dose amount from the first mask pattern arising in dependence on the focus variation and by checking the measured size value with the data stored in said memory.

A focus measurement method comprising:

• using a photomask including a Fresnel zone pattern with light condensing effect formed thereon, an exposure-dose amount of the Fresnel zone pattern to a transfer object varying in dependence on a focus variation,
• storing data indicating a relation between a film thickness of a resist film being the transfer object from the Fresnel zone pattern obtained using said photomask and a focus variation amount, in a memory;
• and
• specifying the focus variation amount while making use of a fact that the exposure-dose amount from the Fresnel zone pattern to a resist film depends on the focus variation and at the same time the film thickness of the resist film after development depends on the exposure-dose amount, and by checking a measured film thickness value of the resist film with the data stored in said memory.

A focus measurement method comprising:

• measuring an exposure-dose amount from a Fresnel zone pattern with light condensing effect by diffraction using a photomask including the Fresnel zone pattern formed thereon, the exposure-dose amount of the Fresnel zone pattern varying in dependence on a focus variation;
• storing data indicating a relation between the exposure-dose amount obtained by said measuring the exposure-dose amount with using said photomask and a focus variation amount, in a memory;
• and
• specifying the focus variation amount by making use of a fact that the exposure-dose amount from the Fresnel zone pattern depends on the focus variation and by checking the measured value of the exposure-dose amount with the data stored in said memory.