Photomask, method for manufacturing the same, projection aligner using the photomask, and projection exposing method

A projection exposure process in which a pattern for transfer which has been formed on the pattern surface of a photomask is illuminated by an exposure beam coming from an illumination optical system and an image of the pattern is formed on a photosensitive substrate via a projection optical system, said photomask having a transmitting member having transmission to the exposure beam, disposed apart from the pattern surface by a stated interval;

• the process comprising the steps of:
• locating the photomask in an optical path extending between the illumination optical system and the projection optical system;
• and
• setting an interval between the pattern surface and the projection optical system at a value determined in accordance with the thickness of the transmitting member of the photomask.

A photomask to be mounted on a projection exposure apparatus with which a pattern for transfer which has been formed on the pattern surface of the photomask is projection-exposed onto a photosensitive substrate by the aid of an exposure beam;

• said photomask comprising;
• a transmitting member having transmission to the exposure beam, disposed apart from the pattern surface by a stated interval;
• and
• a mounting surface supported by a mask stage of the projection exposure apparatus;
• said mounting surface of the photomask and said pattern surface being set apart by a stated distance in the thickness direction of the transmitting member;
• said stated distance being determined taking account of the thickness of the transmitting member.

A process for producing a photomask on which a pattern for transfer is formed and is to be irradiated by a stated exposure beam;

• the process comprising the steps of:
• preparing a transmitting member having transmission to the exposure beam;
• forming on the photomask a pattern for transfer;
• and
• attaching the transmitting member to the photomask in such a way that the transmitting member stands apart by a stated interval from the surface where the pattern for transfer has been formed;
• said step of preparing the transmitting member having an auxiliary step of examining the transmitting member with respect to at least one of the thickness, isophase and refractive index.

A process for producing a photomask on which a pattern for transfer is formed and is to be irradiated by a stated exposure beam;

• the process comprising the steps of:
• preparing a transmitting member having transmission to the exposure beam;
• forming on the photomask a pattern for transfer;
• and
• attaching the transmitting member to the photomask in such a way that the transmitting member stands apart by a stated interval from the surface where the pattern for transfer has been formed;
• said step of preparing the transmitting member having an auxiliary step of examining the transmitting member,
• wherein at least one condition of the following conditions (a′), (b′) and (c) is examined in the step of preparing the transmitting member:
• |ΔTc′|≦0.1λ, (a′)
• |ΔΦc′|≦0.1λ, (b′)
• |Δn|×h<0.1λ, (c)
• where;
• λ:
• wavelength (m) of the exposure beam;
• ΔTc′:
• maximum width (cm) of deviation of the thickness of the transmitting member from a linear approximation obtained when the thickness is linearly approximated;
• ΔΦc′:
• maximum width (cm) of deviation of the isophase plane of plane waves made incident on the transmitting member and having passed through the transmitting member, from a linear approximation obtained when the isophase plane is linearly approximated;
• Δn:
• difference in refractive index of the transmitting member with respect to the exposure beam, between its maximum value and its minimum value;
• and
• h:
• thickness (cm) of the transmitting member.