Wafer-supporting device and method for producing same
A wafer-supporting device for supporting a wafer thereon adapted to be installed in a semiconductor-processing apparatus includes: a base surface; and protrusions protruding from the base surface and having rounded tips for supporting a wafer thereon. The rounded tips are such that a reverse side of a wafer is supported entirely by the rounded tips by point contact. The protrusions are disposed substantially uniformly on an area of the base surface over which a wafer is placed, wherein the number (N) and the height (H [μm]) of the protrusions as determined in use satisfy the following inequities per area for a 300-mm wafer: (−0.5 N +40)≤ H ≤53;5≤ N ≤100.
1. A wafer-supporting device for supporting a wafer thereon adapted to be installed in a semiconductor-processing apparatus, comprising, without any structures required for or serving as an electric chuck:
a base surface comprising an embedded heating element for heating the base surface; and
protrusions protruding from the base surface and having mechanically ground rounded tips for contacting and supporting a wafer thereon, said rounded tips being such that a reverse side of a wafer is supported entirely by the rounded tips by point contact wherein a total area of the rounded tips of the protrusions contacting the reverse side of the wafer is in a range of 10 −6 % to 10 −3 % of the area of the reverse side of the wafer, said protrusions being entirely formed of a material which is the same as that of the base surface, which material is aluminum, anodic aluminum oxide, or aluminum alloy, so that there is no difference in thermal expansion between the protrusions and the base surface, and being integrally formed mechanically by mechanical grinding of the base surface and distributed substantially uniformly on an area of the base surface over which a wafer is placed,
wherein the number (N) and the height (H [μm]) of the protrusions as determined in use satisfy the following inequalities per area as measured for a 300-mm wafer:
(−0.5 N+ 40)≤ H≤ 53
20≤ N≤ 40
said wafer-supporting device having no clamping mechanism, so as to retain the wafer on the protrusions substantially solely by gravity when in use,
wherein the protrusions disposed on a diametric line of the base surface are arranged at substantially equal intervals,
wherein the base surface and the heating element are configured to move up and down; and
wherein the wafer-supporting device is grounded.
2. The wafer-supporting device according to claim 1 , wherein the protrusions are disposed in a geometric arrangement on the base surface such that each one of the protrusions constitutes a point of each of identical squares or identical regular triangles formed by the protrusions.
3. The wafer-supporting device according to claim 1 , wherein the protrusions are formed of dome-shaped ceramics.
4. The wafer-supporting device according to claim 1 , wherein the rounded tips have a radius of about 1 mm to about 2 mm.
5. A semiconductor-processing apparatus comprising:
a reaction chamber capable of being evacuated;
a susceptor including the wafer-supporting device of claim 1 and a heating block, which is installed inside the reaction chamber; and
a showerhead installed inside the reaction chamber in parallel with the susceptor.
6. The semiconductor-processing apparatus according to claim 5 , further comprising an RF power source wherein the susceptor and the showerhead serve as lower and upper electrodes for generating a plasma.