Apparatus for processing substrate

A substrate processing apparatus, comprising:

• a plurality of substrate holders, each substrate holder comprising a substrate support to support a substrate and a first gas pipe having at least one injection hole;
• a boat to stack the plurality of substrate holders and comprising:
• a second gas pipe connected to the first gas pipe of each of the substrate holders;
• and
• a plurality of protrusions disposed vertically, each protrusion extending radially inward from a body of the boat,
• the second gas pipe being disposed within the protrusions;
• a process chamber in which the substrates are processed;
• a conveying unit to move the boat in or out of the process chamber;
• a first heating unit disposed outside the process chamber;
• a gas supply unit connected to a third gas pipe connected to the second gas pipe, the gas supply unit to supply a gas to the second gas pipe via the third gas pipe;
• and
• a connecting member disposed between each of the substrate holders and the protrusions,
• wherein the first gas pipe is connected to the second gas pipe disposed within each protrusion via the connecting member, and the substrate holders are horizontally supported by the protrusions via the connecting member.