Enveloping device and vertical heat-treating apparatus for semiconductor process system

An enveloping device having a sealing mechanism for a semiconductor process system, comprising:

• a casing having first and second parts detachably assembled to envelop a pressure-reduced space;
• a member configured to apply a mechanical force to join said first and second parts;
• a first flange arranged on said first part, and being provided with a looped first mirror surface, and a looped first counter surface arranged around said first mirror surface, said first mirror surface having a surface roughness of Ra=0.06 μm or less;
• a second flange arranged on said second part, and being provided with a looped second mirror surface, and a looped second counter surface arranged around said second mirror surface, said second mirror surface having a surface roughness of Ra=0.06 μm or less, said first and second mirror surfaces facing and contacting each other to form an inner seal for substantially airtightly sealing said pressure-reduced space, said first and second counter surfaces facing each other with a gap therebetween;
• a looped seal member arranged in said gap such that an outer seal is formed by said first and second counter surfaces and said seal member, and a looped buffer space, substantially airtightly closed, is formed between said inner and outer seals;
• and
• a buffer exhaust mechanism configured to exhaust and set said buffer space to a pressure-reduced state.