Wafer carrier

1. A wafer carrier comprising:

a lower unit of which a semiconductor wafer is placed, wherein the lower unit comprises a lower surface that meets a side surface that is substantially perpendicular to the lower surface; and

an upper unit detachably attached to the lower unit, and forming a sealed chamber for housing the semiconductor wafer between the upper unit and the lower unit, wherein

concave portions are formed in the side surface of the lower unit,

the upper unit is provided with plural lock mechanisms that fix the lower unit to the upper unit, the plural lock mechanisms abut on the side surface of the lower unit in the concave portions,

each lock mechanism includes a spherical body fitted to the concave portion of the lower unit, a lock lever provided in the upper unit so as to swing, wherein the lock lever includes a tip portion of which abuts on the spherical body to press the spherical body to the concave portion side of the lower unit and a spring member that biases the tip portion of the lock lever to the spherical body side, and

the spherical body of respective lock mechanisms abut on the side surface of the lower unit, and a lowermost part of the spherical body is positioned above a plane formed by the lower surface of the lower unit in a direction of the upper unit.

2. The wafer carrier according to claim 1 , wherein a through hole formed in a swinging direction of the lock lever of the lock mechanism is formed in the upper unit, and the spherical body is provided so as to reciprocate in the through hole, and

a convex portion protruding to a central side of the through hole and inclined to the lock lever is formed at an end portion of the sealed chamber side inside the through hole.

3. The wafer carrier according to claim 1 , wherein the upper unit is provided with a guide member that guides extension and contraction of the spring member in the direction of the spherical body.

4. The wafer carrier according to claim 1 , wherein the lock mechanisms are built in the upper unit.

5. The wafer carrier according to claim 1 , wherein the spherical body is made of a metal, and

the lock lever is made of a resin.

6. The wafer carrier according to claim 1 , wherein plural lug portions having different shapes from each other and protruding outward are formed in the side surface of the lower unit,

the concave portions are formed in side surfaces of the lug portions, and

concave positioning portions are respectively formed in the upper unit so as to correspond to the lug portions of the lower unit.