Method for manufacturing bonded substrate
A method for bonding a first substrate with a second substrate in a treatment chamber, wherein the treatment chamber accommodates a first holding unit that attracts the first substrate and a second holding unit that attracts the second substrate. The method includes the steps of transporting the first and second substrates as a pair to the treatment chamber; vacuum attracting at least one of the first and second substrates to the associated holding unit by applying an attraction pressure to at least one of the first and second substrates; depressurizing the treatment chamber to a predetermined level; attracting at least one of the substrates by at least one of another holding devices provided in at least one of the holding units after the pressure in the treatment chamber reaches the predetermined vacuum level, and after the pressure in the treatment chamber reaches the predetermined vacuum level, controlling (with a controller) the attraction pressure applied to at least one of the first and second substrates to be substantially equal to the predetermined vacuum level of the treatment chamber.
1. A method for bonding a first substrate with a second substrate in a treatment chamber, wherein the treatment chamber accommodates a first holding unit that attracts the first substrate and a second holding unit that attracts the second substrate, the method comprising the steps of:
transporting the first and second substrates as a pair to the treatment chamber;
vacuum attracting at least one of the first and second substrates to the associated holding unit by applying an attraction pressure to said at least one of the first and second substrates;
depressurizing the treatment chamber to a predetermined level;
attracting said at least one of the substrates by at least one of another holding devices provided in at least one of the holding units after the pressure in the treatment chamber reaches the predetermined vacuum level, and
after the pressure in the treatment chamber reaches the predetermined vacuum level, controlling with a controller the attraction pressure applied to said at least one of the first and second substrates to be substantially equal to the predetermined vacuum level of the treatment chamber.
2. The method according to claim 1 , wherein said another attraction step includes electrostatically attracting said at least one of the first and second substrates to the associated holding unit.
3. The method according to claim 2 , wherein the pressure equalization step is performed when or after the electrostatic attraction step is started.
4. The method according to claim 2 , wherein the electrostatic attraction step includes a sub-step of applying an attraction voltage to an electrode embedded in a dielectric layer formed in each holding unit.
5. The method according to claim 4 , further comprising a step of supplying a separation voltage to the dielectric layer through a conductor connected to the dielectric layer for separating the first or second substrate from the associated holding unit.
6. The method according to claim 1 , further comprising a step of correcting bending of each substrate during the vacuum attraction step.
7. The method according to claim 2 , further comprising:
a step of actuating the first and second holding units to align the first and second substrates after the electrostatic attraction step;
a step of actuating the first and second holding units to press the first and second substrates to each other; and
a step of controlling a pressure applied to each substrate for pressing the first and second substrates to each other.
8. The method according to claim 7 , wherein the alignment step includes a sub-step of aligning an alignment mark of the first substrate with an alignment mark of the second substrate through an image of the alignment marks.
9. The method according to claim 1 , wherein the first and second substrates are an array substrate that has a plurality of switch elements and a color filter substrate, and the panel display is a liquid crystal panel display.
10. The method according to claim 1 , wherein said substantially equalizing the attraction pressure includes controlling the attraction pressure based on the pressure in the treatment chamber.
11. The method according to claim 10 , wherein said substantially equalizing the attraction pressure includes controlling the attraction pressure equal to or slightly lower than the pressure in the treatment chamber.
12. The method according to claim 11 , wherein said vacuum attracting includes vacuum attracting a non-bonding surface of said at least one of the first and second substrates to the associated holding unit while applying the pressure in the treatment chamber to a bonding surface of said at least one of the first and second substrates to the associated holding unit, and wherein said substantially equalizing the attraction pressure includes controlling the attraction pressure applied to the non-bonding surface of said at least one of the first and second substrates equal to or slightly lower than the pressure in the treatment chamber.
13. The method according to claim 1 , wherein the controller controls said attraction pressure applied to said at least one of the first and second substrates to be substantially equal to the predetermined vacuum level of the treatment chamber while keeping said at least one of the first and second substrates attracted to the associated another holding device of the associated holding unit.