Dual-bulb lamphead control methodology

Abstract

The present invention generally relates to methods of controlling UV lamp output to increase irradiance uniformity. The methods generally include determining a baseline irradiance within a chamber, determining the relative irradiance on a substrate corresponding to a first lamp and a second lamp, and determining correction or compensation factors based on the relative irradiances and the baseline irradiance. The lamps are then adjusted via closed loop control using the correction or compensation factors to individually adjust the lamps to the desired output. The lamps may optionally be adjusted to equal irradiances prior to adjusting the lamps to the desired output. The closed loop control ensures process uniformity from substrate to substrate. The irradiance measurement and the correction or compensation factors allow for adjustment of lamp set points due to chamber component degradation, chamber component replacement, or chamber cleaning.

1 . A method of controlling lamp output in a process chamber having at least a first lamp and a second lamp, comprising:
 positioning a first light pipe adjacent to an sensor;   measuring the irradiance from the first lamp through the first light pipe with the sensor, wherein the first light pipe allows substantially only light from the first lamp therethrough to be measured by the sensor;   positioning a second light pipe adjacent to the sensor;   measuring the irradiance from the second lap through the second light pipe with the sensor, wherein the second light pipe allows substantially only light form the second lamp therethrough to be measured by the sensor;   adjusting the irradiance of the first lamp based on the measured irradiance of the first lamp; and   adjusting the irradiance of the second lamp based on the measured irradiance of the second lamp.   
     
     
         2 . The method of  claim 1 , wherein positioning the first light pipe comprises:
 rotating a housing including the first light pipe; and   rotating the first lamp.   
     
     
         3 . The method of  claim 2 , wherein positioning the second light pipe comprises:
 rotating the housing including the second light pipe; and   rotating the second lamp.   
     
     
         4 . The method of  claim 3 , wherein each of the first lamp and the second lamp are coupled to the housing. 
     
     
         5 . The method of  claim 1 , further comprising:
 determining a compensation factor for the first lamp; and   determining a compensation factor for the second lamp.   
     
     
         6 . The method of  claim 1 , wherein:
 measuring the irradiance from the first lamp comprises rotating the first lamp during the measuring; and   measuring the irradiance from the second lamp comprises rotating the second lamp during the measuring.   
     
     
         7 . The method of  claim 1 , wherein adjusting the irradiance of the first lamp comprises adjusting the irradiance of the first lamp using a first closed-loop algorithm, and adjusting the irradiance of the second lamp comprises adjusting the irradiance of the second lamp using a second closed-loop algorithm. 
     
     
         8 . A method of controlling lamp output in a process chamber having at least a first lamp and a second lamp, comprising:
 positioning a first light pipe coupled to a reflective housing adjacent to an sensor;   measuring the irradiance from the first lamp through the first light pipe with the sensor, wherein the first light pipe allows substantially only light from the first lamp therethrough to be measured by the sensor;   positioning a second light pipe coupled to the reflective housing adjacent to the sensor;   measuring the irradiance from the second lap through the second light pipe with the sensor, wherein the second light pipe allows substantially only light form the second lamp therethrough to be measured by the sensor;   determining a compensation factor for the first lamp;   determining a compensation factor for the second lamp;   adjusting the irradiance of the first lamp based on the measured irradiance of the first lamp; and   adjusting the irradiance of the second lamp based on the measured irradiance of the second lamp.   
     
     
         9 . The method of  claim 8 , wherein the first lamp is coupled to the reflective housing, and wherein positioning the first light pipe comprises positioning the first lamp. 
     
     
         10 . The method of  claim 9 , wherein the second lamp is coupled to the reflective housing, and wherein positioning the second light pipe comprises positioning the second lamp. 
     
     
         11 . The method of  claim 10 , wherein:
 measuring the irradiance from the first lamp comprises rotating the first lamp during the measuring; and   measuring the irradiance from the second lamp comprises rotating the second lamp during the measuring.   
     
     
         12 . The method of  claim 8 , wherein adjusting the irradiance of the first lamp comprises adjusting the irradiance of the first lamp using a first closed-loop algorithm, and adjusting the irradiance of the second lamp comprises adjusting the irradiance of the second lamp using a second closed-loop algorithm. 
     
     
         13 . The method of  claim 8 , further comprising ultraviolet curing a substrate disposed in the process chamber using the first lamp and the second lamp. 
     
     
         14 . A process chamber, comprising:
 an irradiance sensor;   a rotatable first lamp;   a rotatable second lamp;   a rotatable reflective housing including a plurality of light pipes, wherein each light pipe is positioned to allow substantially only light from either the first lamp or second lamp therethrough to be measured by the irradiance sensor.   
     
     
         15 . The process chamber of  claim 14 , wherein the rotatable first lamp and the rotatable second lamp are coupled to the rotatable reflective housing. 
     
     
         16 . The process chamber of  claim 14 , wherein the process chamber consists of a single irradiance sensor. 
     
     
         17 . The process chamber of  claim 14 , further comprising a substrate support and quartz window disposed between the substrate support and the rotatable reflective housing. 
     
     
         18 . The process chamber of  claim 17 , wherein each of the first lamp and the second lamp comprise a primary reflector to direct light towards the substrate support. 
     
     
         19 . The process chamber of  claim 14 , wherein interior surfaces of the light pipes are textured.