Method and apparatus for preventing a furnace in a semiconductor process from temperature and gas excursion
To prevent a furnace in a semiconductor process from temperature and gas excursion, a paddle and spike thermal couples arranged on the sidewall of the tube and adjacent to the heater, respectively, are connected to a temperature controller to regulate the heater, and a mass controller adjusts the gas flow injected to the tube. In the method, the spike thermal couple, peddle thermal couple and zero point of the mass flow controller are checked to maintain within a first and second temperature ranges and a first gas flow speed range, respectively, and after wafers are loaded and temperature is ramped up, the peddle thermal couple and mass flow controller are checked again to maintain within a third temperature range and second gas flow speed range.
1. A method for preventing temperature and gas excursions in a furnace during semiconductor processing, said furnace having a tube and a heater coiled around said tube, said tube having a sidewall monitored by a first thermal couple and being injected with a gas flow thereto by a mass flow controller, said heater being monitored by a second thermal couple and regulated by a temperature controller responsive to said first and second thermal couples, said method comprising the steps of:
checking whether said second thermal couple is in a first temperature range;
checking whether said first thermal couple is in a second temperature range;
checking whether a zero point of said mass flow controller is in a first gas flow speed range;
loading wafers into said tube;
ramping up a temperature of said tube;
checking whether said first thermal couple is in a third temperature range; and
checking whether said mass flow controller is in a second gas flow speed range.
2. A method according to claim 1 , wherein said first temperature range is ±5° C. around a setting temperature.
3. A method according to claim 1 , wherein said second temperature range is ±5° C. around a setting temperature.
4. A method according to claim 1 , wherein said first gas flow speed range is ±1% around said zero point.
5. A method according to claim 1 , wherein said third temperature range is ±10° C. around a setting temperature.
6. A method according to claim 1 , wherein said second gas flow speed range is ±1% around a setting point.
7. An apparatus for preventing temperature and gas excursions in a furnace during semiconductor processing, said furnace having a tube for performing a main step, said apparatus comprising:
a heater coiling around said tube;
a first thermal couple arranged on a sidewall of said tube for generating a first temperature signal;
a second thermal couple arranged adjacent to said heater for generating a second temperature signal;
a temperature controller for regulating said heater responsive to said first and second temperature signals; and
a mass flow controller for controlling a gas flow injected into said tube;
wherein before said main step, a gas flow zero point is adjusted within a predetermined gas flow speed range, and said first and second thermal couples are adjusted within a first and second temperature ranges, respectively.
8. An apparatus according to claim 7 , wherein said temperature controller checks said first and second temperature signals in turn.