Electrostatic chuck

An electrostatic chuck comprising:

• a ceramic dielectric substrate having a first major surface for mounting a suction target and a second major surface on an opposite side from the first major surface;
• a base plate supporting the ceramic dielectric substrate and including a gas feed channel;
• a first porous part provided at a position between the base plate and the first major surface of the ceramic dielectric substrate, the position being opposed to the gas feed channel, the first porous part including a porous section including a plurality of pores, and a first compact section being more compact than the porous section,
• a second porous part provided between the first porous part and the gas feed channel and including a plurality of pores,
• the ceramic dielectric substrate including a first hole part located between the first major surface and the first porous part,
• wherein, as projected on a plane perpendicular to a first direction from the base plate to the ceramic dielectric substrate, the first compact section is configured to overlap the first hole part, and the porous section is configured not to overlap the first hole part,
• and wherein an average value of a diameter of the plurality of pores provided in the second porous part is larger than an average value of a diameter of the plurality of pores provided in the porous section.

An electrostatic chuck comprising:

• a ceramic dielectric substrate having a first major surface for mounting a suction target and a second major surface on an opposite side from the first major surface;
• a base plate supporting the ceramic dielectric substrate and including a gas feed channel;
• a first porous part provided at a position between the base plate and the first major surface of the ceramic dielectric substrate, the position being opposed to the gas feed channel, the first porous part including a porous section including a plurality of pores, and a first compact section being more compact than the porous section,
• a second porous part provided between the first porous part and the gas feed channel and including a plurality of pores,
• the ceramic dielectric substrate including a first hole part located between the first major surface and the first porous part,
• wherein, as projected on a plane perpendicular to a first direction from the base plate to the ceramic dielectric substrate, the first compact section is configured to overlap the first hole part, and the porous section is configured not to overlap the first hole part,
• and wherein an average value of a diameter of the plurality of pores provided in the second porous part is smaller than an average value of a diameter of the plurality of pores provided in the porous section.

An electrostatic chuck comprising:

• a ceramic dielectric substrate having a first major surface for mounting a suction target and a second major surface on an opposite side from the first major surface;
• a base plate supporting the ceramic dielectric substrate and including a gas feed channel;
• a first porous part provided at a position between the base plate and the first major surface of the ceramic dielectric substrate, the position being opposed to the gas feed channel, the first porous part including a porous section including a plurality of pores, and a first compact section being more compact than the porous section,
• a second porous part provided between the first porous part and the gas feed channel and including a plurality of pores,
• the ceramic dielectric substrate including a first hole part located between the first major surface and the first porous part,
• wherein, as projected on a plane perpendicular to a first direction from the base plate to the ceramic dielectric substrate, the first compact section is configured to overlap the first hole part, and the porous section is configured not to overlap the first hole part,
• and wherein:
• the porous section includes a plurality of sparse portions including a plurality of pores including the first pore and the second pore, and a dense portion having a higher density than the sparse portions,
• each of the plurality of sparse portions extends in the first direction,
• the dense portion is located between the plurality of sparse portions,
• the sparse portion includes a wall part provided between the first pore and the second pore, and
• in a second direction substantially orthogonal to the first direction, a minimum dimension of the wall part is smaller than a minimum dimension of the dense portion.

An electrostatic chuck comprising:

• a ceramic dielectric substrate having a first major surface for mounting a suction target and a second major surface on opposite side from the first major surface;
• a base plate supporting the ceramic dielectric substrate and including a gas feed channel;
• a first porous part provided at a position between the base plate and the first major surface of the ceramic dielectric substrate, the position being opposed to the gas feed channel, the first porous part comprising a first porous section including a plurality of pores;
• and
• a second porous part provided between the first porous part and the gas feed channel,
• the ceramic dielectric substrate including a first hole part located between the first major surface and the first porous part,
• the second porous part including a second porous section including a plurality of pores, and a compact section more compact than the second porous section, and
• as projected on a plane perpendicular to a first direction from the base plate to the ceramic dielectric substrate, the compact section being configured to overlap the first hole part, and the second porous section being configured not to overlap the first hole part.

An electrostatic chuck comprising:

• a ceramic dielectric substrate having a first major surface for mounting a suction target and a second major surface on an opposite side from the first major surface;
• a base plate supporting the ceramic dielectric substrate and including a gas feed channel;
• a first porous part provided at a position between the base plate and the first major surface of the ceramic dielectric substrate, the position being opposed to the gas feed channel, the first porous part including a porous section including a plurality of pores, and a first compact section being more compact than the porous section,
• a second porous part provided between the first porous part and the gas feed channel and including a plurality of pores,
• the ceramic dielectric substrate including a first hole part located between the first major surface and the first porous part,
• wherein, as projected on a plane perpendicular to a first direction from the base plate to the ceramic dielectric substrate, the first compact section is configured to overlap the first hole part, and the porous section is configured not to overlap the first hole part,
• and wherein, when a direction generally orthogonal to the first direction is taken as a second direction,
• the first porous part includes a first region located on the ceramic dielectric substrate side in the second direction,
• the ceramic dielectric substrate includes a first substrate region located on the first region side in the second direction,
• the first region is provided to be in contact with the first substrate region, and
• an average grain size in the first region is different from an average grain size in the first substrate region.