Method bonding for production of SOI transistor device

A substrate bonding method wherein two substrates are bonded to form a clad substrate, comprising the steps of:

• supporting a first substrate on a first chuck,
• bringing a second substrate into close proximity with said first substrate using a second chuck;
• allowing said second substrate to fall toward said first substrate in free state so that it floats above said first substrate;
• moving a push rod which has a contact surface into a position over said second substrate;
• pressing one point of said second substrate against said first substrate using the push rod;
• and
• allowing bonding which is induced by an attraction force between said first and second substrates to proceed from the location at which said first and second substrates are pressed together and so that said first and second substrates become bonded without the inclusion of air bubbles therebetween.

A method of bonding first and second substrates comprising the steps of:

• supporting the first substrate on a curved stationary surface in a manner which causes the first substrate to assume a curved convex shape;
• releasing the second substrate toward the first substrate while the first substrate is maintained in said convex shape;
• pressing said second substrate into contact with said first substrate with a force of 0.5N to 5N using a push rod having a diameter of 1 to 10 mm;
• and
• allowing said second substrate to bond to said first substrate while said first substrate is in said convex curved shape.