Patent Publication Number: US-2020286719-A1

Title: Substrate carrier apparatus, substrate processing apparatus, and method of adjusting temperature of susceptor

Description:
TECHNICAL FIELD 
     Examples are described which relate to a substrate carrier apparatus, a substrate processing apparatus, and a method of adjusting the temperature of a susceptor. 
     BACKGROUND 
     One of wafer processing conditions is temperature setting of a susceptor heater (sometimes referred to simply as a heater, hereinafter). The temperature setting of the heater is done for setting the temperature of a substrate on a susceptor at a desired temperature. In order that the temperature of the substrate is set at a desired temperature, the heater is controlled based on a reference value with an offset. 
     It can take a long time to determine the offset. For example, a series of operations is performed which includes raising the pressure in the chamber to the atmospheric pressure, lowering the temperature of the susceptor, opening the chamber, placing a temperature measuring wafer with a thermometer embedded therein on the susceptor, closing the chamber, raising the temperature of the susceptor, lowering the pressure in the chamber to a near-vacuum pressure, measuring the temperature of the temperature measuring wafer and removing the temperature measuring wafer from the chamber. 
     The gap value between the measured temperature of the temperature measuring wafer and the required wafer processing temperature specified in the recipe is registered as offset data. In processing a product substrate, the required wafer processing temperature is modified based on the offset data. 
     However, the method using the temperature measuring wafer described above involves a long downtime for opening and closing the chamber and raising and lowering the temperature in the chamber and therefore cannot be performed frequently. For this reason, the offset data is updated by taking advantage of the opportunity of replacing a heater. Therefore, the offset data can continue to be used even if the difference between the temperature of the heater and the temperature of the substrate varies as the condition of the apparatus varies over time. As a result, substrates can be processed at temperatures that are not ideal for a long time. 
     SUMMARY 
     Some examples described herein may address the above-described problems. Some examples described herein may provide a substrate carrier apparatus, a substrate processing apparatus and a method of adjusting the temperature of a susceptor that allow the temperature of a substrate to be set at a desired temperature. 
     In some examples, a substrate carrier apparatus includes a shaft, at least one carrier arm that is fixed to the shaft and being configured to rotate as the shaft rotates, and at least one thermometer fixed to the carrier arm. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view showing an example of a substrate processing apparatus; 
         FIG. 2  is a side view showing the example of the substrate processing apparatus; 
         FIG. 3  is a cross-sectional view of the carrier arm; 
         FIG. 4  is a plan view showing an example of the carrier arm; 
         FIG. 5  shows an example of the arrangement of the thermometers; 
         FIG. 6  shows an example of an arrangement for rotation of the shaft; 
         FIG. 7  is a flowchart; and 
         FIG. 8  is an illustration of data obtained by mapping. 
     
    
    
     DETAILED DESCRIPTION 
     A substrate carrier apparatus, a substrate processing apparatus, and a method of adjusting the temperature of a susceptor will be described with reference to the drawings. The same or corresponding components will be denoted by the same reference numerals, and redundant descriptions thereof may be omitted. 
       FIG. 1  is a plan view showing an example of a configuration of a substrate processing apparatus. The substrate processing apparatus includes susceptors  10 ,  12 ,  14  and  16 . The substrate processing apparatus includes a substrate carrier apparatus  20  that supplies a substrate to the susceptors  10 ,  12 ,  14  and  16  and removes the substrate from the susceptors  10 ,  12 ,  14  and  16 . The substrate carrier apparatus  20  may includes a shaft  20 A, and carrier arms  20 B,  20 C,  20 D and  20 E that are fixed to the shaft  20 A and rotate as the shaft  20 A rotates. The substrate carrier apparatus  20  has at least one carrier arm. As the shaft  20 A rotates, the carrier arms  20 B,  20 C,  20 D and  20 E rotates about the shaft  20 A. The carrier arms  20 B,  20 C,  20 D and  20 E move in an x-y plane. 
     The arrangement described above is enclosed in a housing  22 . For example, the substrate processing apparatus may be a quad chamber module (QCM). The QCM can perform the same processing on four substrates on the four susceptors  10 ,  12 ,  14  and  16  kept at the same temperature. The processing performed on the substrates may be film deposition using plasma, etching using plasma, or modification of a film by plasma, for example. 
     A wafer handling chamber  30  is located adjacent to the substrate processing apparatus. In the wafer handling chamber  30 , an arm  32  carries a substrate. For example, a substrate held by the arm  32  may be provided to the substrate processing apparatus, or a substrate may be removed from inside the substrate processing apparatus with the arm  32 . 
       FIG. 2  is a side view showing the example of the configuration of the substrate processing apparatus. Thermometers  40 ,  42 ,  44 ,  46  and  48  are fixed to the carrier arm  20 E. The thermometers  40 ,  42 ,  44 ,  46  and  48  may be thermocouples or resistance temperature sensors, for example. At least one thermometer can be fixed to the carrier arm  20 E. In another example, a different number of thermometers can be used. As described above, the substrate carrier apparatus has the shaft  20 A, the carrier arms  20 B,  20 C,  20 D and  20 E, and the thermometers  40 ,  42 ,  44 ,  46  and  48 . 
     Only one of the carrier arms  20 B,  20 C,  20 D and  20 E shown in  FIG. 1  may be provided with a thermometer. In the example shown in  FIG. 2 , of the carrier arms  20 B,  20 C,  20 D and  20 E, only the carrier arm  20 E has a thermometer fixed thereto. In another example, all of a plurality of carrier arms may be provided with a thermometer. A plurality of thermometers may be provided on one carrier arm, or one thermometer may be provided on one carrier arm. 
       FIG. 2  shows the susceptor  10  and a heater  10   a  fixed to the susceptor  10 . The heater  10   a  can be provided at any position for heating the susceptor  10 . For example, the heater  10   a  may be embedded in the susceptor  10  or provided on a lower surface of the susceptor  10 . All the susceptors  10 ,  12 ,  14  and  16  can be provided with a heater. The heater  10   a  is controlled by a temperature regulator  54 . The temperature regulator  54  receives a command concerning the temperature of the heater  10   a  from a unique platform controller (UPC)  52 , and energizes the heater  10   a  according to the command. 
     In an example, when the carrier arm  20 E is located directly above the susceptor  10 , all the thermometers  40 ,  42 ,  44 ,  46  and  48  fixed to the carrier arm  20 E are located directly above the susceptor  10 . Similarly, when the carrier arm  20 E is located directly above the susceptor  12 ,  14  or  16 , all the thermometers  40 ,  42 ,  44 ,  46  and  48  are located directly above the susceptor  12 ,  14  or  16 . 
     A transfer unit  50  is connected to the thermometers  40 ,  42 ,  44 ,  46  and  48 . In an example, the transfer unit  50  converts the measurement result from the thermometers  40 ,  42 ,  44 ,  46  and  48  into digital data, and transmits the digital data to a control unit. As an example of the control unit, a transfer module controller (TMC)  33  and the UPC  52  are provided. In an example, the transfer unit  50  transmits the digital data on the measurement result (sometimes referred to as a measured temperature, hereinafter) to the TMC  33  by wireless communication. The TMC  33  transfers the digital data on the measurement results to the UPC  52 . The UPC  52  updates an offset for a required wafer processing temperature according to a recipe so as to bring the surface temperature of the susceptor  10  close to a target temperature, based on the measured temperature and the temperature of the heater  10   a  at the time when the measured temperature is obtained. The UPC  52  issues a command including the required wafer processing temperature according to the recipe and the updated offset to the temperature regulator  54 . Then, the temperature regulator  54  can be controlled with the updated offset. 
       FIG. 3  is a cross-sectional view of the carrier arm  20 E. The thermometers  40 ,  42 ,  44 ,  46  and  48  may be exposed on the back surface of the carrier arm  20 E. In another example, the thermometers  40 ,  42 ,  44 ,  46  and  48  may protrude toward the susceptor  10  from the back surface of the carrier arm  20 E. In a further example, recesses may be formed in the back surface of the carrier arm  20 E, and the thermometers  40 ,  42 ,  44 ,  46  and  48  may protrude in the recesses. 
       FIG. 4  is a plan view showing an example of a configuration of the carrier arm. The carrier arm  20 E includes a main body part  20   a  connected to the shaft  20 A, a first branch part  20   b , a second branch part  20   c , and an extension part  20   d . The first branch part  20   b  and the second branch part  20   c  are parts that branch from the main body part  20   a . The extension part  20   d  is connected to the main body part  20   a  and is located further from the shaft  20 A than the main body part  20   a . In an example, the extension part  20   d  is adjacent to the connection between the main body part  20   a  and the first branch part  20   b . While the carrier arm  20 E is rotating, the main body part  20   a  and the extension part  20   d  can pass directly above the susceptors  10 ,  12 ,  14  and  16 .  FIG. 4  shows the main body part  20   a  and the extension part  20   d  located directly above the susceptor  14  during rotation of the carrier arm  20 E. 
       FIG. 5  shows an example of the arrangement of the thermometers  40 ,  42 ,  44 ,  46  and  48 . The thermometers  40 ,  42 ,  44 ,  46  and  48 , which are exposed on the back surface of the carrier arm  20 E, should not be visible in this plan view, so that  FIG. 5  shows the positions at which the thermometers  40 ,  42 ,  44 ,  46  and  48  are exposed on the back surface of the carrier arm  20 E for reference. The thermometers  42 ,  44 ,  46  and  48  may be fixed to the main body part  20   a  and exposed on the back surface of the main body part  20   a , and the thermometer  40  may be fixed to the extension part  20   d  and exposed on the back surface of the extension part  20   d . The dashed lines in  FIG. 5  show an example of trajectories of the thermometers  40 ,  42 ,  44 ,  46  and  48  during rotation of the carrier arm  20 E. The thermometers  40 ,  42 ,  44 ,  46  and  48  pass directly above the susceptor  14  and thereby can measure the temperature of the susceptor  14  at the positions indicated by the five dashed lines. 
       FIG. 6  shows an example of an arrangement for rotation of the shaft  20 A. The shaft  20 A extends through a bearing  62  with a magnetic seal  64  interposed therebetween. The bearing  62  can be held on a chamber  60 . There is a vacuum in the chamber  60 , and the ambient pressure of the chamber  60  is the atmospheric pressure. As a motor  61  rotates the shaft  20 A in response to a command from the TMC  33 , the carrier arm rotates with the difference in pressure between the outside and inside of the chamber  60  maintained by the magnetic seal  64 . 
       FIG. 7  is a flowchart showing an example of a method of adjusting the temperature of a susceptor. First, in Step S 1 , a first substrate procedure is performed. The substrate procedure may include placing substrates on the susceptors  10 ,  12 ,  14  and  16  with the carrier arms  20 B,  20 C,  20 D and  20 E, performing a processing on the substrates, and removing the substrates from the susceptors  10 ,  12 ,  14  and  16  with the carrier arms  20 B,  20 C,  20 D and  20 E, for example. For the substrate procedure, the temperature regulator  54  sets the heater  10   a  at a predetermined temperature in response to a command from the UPC  52 . More specifically, a command including the required wafer processing temperature according to the recipe with a predetermined offset that is intended to bring the surface temperature of the susceptor  10  close to the target temperature is transmitted to the temperature regulator  54 . According to the “required wafer processing temperature according to the recipe” with an offset, the temperature regulator  54  raises the temperature of the heater  10   a . For example, the substrate procedure can be performed with the four susceptors  10 ,  12 ,  14  and  16  at the same temperature. 
     The process then proceeds to Step S 2 . In Step S 2 , the surface temperature of the susceptors  10 ,  12 ,  14  and  16  is measured by at least one thermometer fixed to the carrier arm  20 E. In an example, the surface temperature of the plurality of susceptors  10 ,  12 ,  14  and  16  can be measured while the carrier arm  20 E is rotating. The rotational speed of the carrier arm  20 E can be lower than 3.53 seconds/180°. To improve the accuracy of the temperature measurement, the rotational speed of the carrier arm can be equal to or lower than 10 seconds/180°. The reduced rotation speed of the carrier arm provides accurate measured temperature. In view of this, a rotational speed of the carrier arm  20 E may be reduced with the increasing of the difference between a measured temperature obtained by the thermometer and a target temperature. In measurement of the surface temperature of the susceptor, the distance between the thermometers  40 ,  42 ,  44 ,  46  and  48  and the susceptor can be equal to or less than 4 mm. 
     In another example, the surface temperature of the susceptor can be measured by bringing the carrier arm  20 E close to the susceptor. More specifically, the temperature is measured by bringing the carrier arm close to the susceptor without rotating the carrier arm. This measurement method can make a contribution to speeding up the measurement. 
     If the surface temperature of the susceptor is measured while the carrier arm is rotating, mapping of the surface temperature of the susceptor can be performed.  FIG. 8  is an illustration of data obtained by mapping. In the example shown in  FIG. 8 , five thermometers read different surface temperatures. 
     If the thermometers are fixed to only the carrier arm  20 E, the surface temperature of all the susceptors can be measured by rotating the carrier arm  20 E 360°. On the other hand, if the thermometers are fixed to all of the carrier arms  20 B,  20 C,  20 D and  20 E, the surface temperature of all the susceptors can be measured by rotating the carrier arms only 90°. 
     In the measurement of the surface temperature without rotation of the carrier arm, the surface temperature of a susceptor is measured by bringing the carrier arm close to the susceptor, and then the carrier arm is rotated before measuring the surface temperature of another susceptor. If thermometers are fixed to all the carrier arms  20 B,  20 C,  20 D and  20 E, the surface temperature of all the susceptors can be measured at the same time by bringing the carrier arms close to different susceptors at the same time. 
     In an example, if the measured temperature does not fall within a predetermined range, the process is stopped, and a notice of the abnormality can be given. For example, if the temperature measuring system fails or a crack occurs in a susceptor, the process is stopped, and a notice of the abnormality is given to the user so that the problem is solved. 
     The process then proceeds to Step S 3 . In Step S 3 , the UPC  52  compares the measured temperature from the thermometers with a predetermined target temperature. The target temperature may be the required wafer processing temperature according to the recipe, for example. In an example, the UPC  52  determines whether or not the difference between the measured temperature and the target temperature is greater than a predetermined value. For example, if the measured temperature is 455° C., the target temperature is 450° C., and the maximum value of the allowable difference is ±2° C., the UPC  52  determines that offset data on the target temperature needs to be updated. The offset data can be stored in a parameter file in a configuration file in the UPC  52 . 
     The process then proceeds to Step S 4 . If it is determined in Step S 3  that the offset data needs to be updated, the offset data is updated in Step S 4 . In the example described above, since the measured temperature is 455° C. and the target temperature is 450° C., the offset data is updated to “−5° C”. In this example, the condition for updating the offset data is that the difference between the measured temperature and the target temperature is greater than a predetermined value. In another example, however, the offset data may be updated whenever the measured temperature is not equal to the target temperature. 
     In  FIG. 7 , the series of processings in Steps S 2 , S 3  and S 4  is shown as an update procedure  1  for the offset data. 
     The process then proceeds to Step S 5 . In Step S 5 , a second substrate procedure is performed. The substrate procedure can be the same as the first substrate procedure except for the temperature of the heater  10   a . In the second substrate procedure, since the target temperature is 450° C., and the offset data is −5° C., so that the UPC  52  instructs the temperature regulator  54  to set the temperature of the heater  10   a  at 445° C. Then, the temperature of the susceptor becomes 445° C., and the measured temperature comes closer to 450° C., which is the target temperature. 
     As described above, details of the control of the heater  10   a  are modified to reduce the difference between the measured temperature from the thermometers and the target temperature. In this example, details of the control of the heater are modified when the difference is greater than the predetermined value. Therefore, the process can be prevented from being complicated because of frequent modifications of details of the control of the heater. Updating the offset data is just an example of the way of modifying details of the control of the heater, and details of the control of the heater may be modified in other ways. 
     After the second substrate procedure ends, an update procedure for the offset data is performed again in Steps S 6 , S 7  and S 8 . The details of Steps S 6 , S 7  and S 8  are basically the same as those of Steps S 2 , S 3  and S 4 . In this update procedure (referred to as an update procedure  2 ), the offset data is updated if necessary. 
     In Step S 9 , a third substrate procedure is performed. The details of the substrate procedure can be the same as those of the first substrate procedure except that the temperature of the heater can be modified. In the third substrate procedure, the UPC  52  issues a command reflecting the latest offset data to the temperature regulator  54 . Then, the temperature of the substrate comes closer to the 450° C., which is the target temperature. 
     Performing measurement of the surface temperature of the susceptor between a plurality of substrate procedures is very simple, compared with the task of determining the offset data that involves placing a dedicated temperature measuring wafer on a susceptor. The update procedure for the offset data may be performed between every substrate procedures or at a particular timing between substrate procedures. 
     In order to maintain the magnetic seal  64  shown in  FIG. 6 , for example, the substrate processing apparatus is required to rotate the shaft  20 A at regular intervals in addition to the opportunities of rotating the shaft  20 A for carrying substrates. The rotations of the shaft  20 A at regular intervals can be said as a maintenance operation. The maintenance operation involves rotating the shaft  20 A to rotate the carrier arms  20 B,  20 C,  20 D and  20 E fixed to the shaft  20 A in the state where the carrier arms  20 B,  20 C,  20 D and  20 E carry no substrate. The maintenance operation involving rotating the shaft  20 A at regular intervals retards deterioration of the magnetic seal  64 . 
     In Step S 10 , the surface temperature of the susceptor is measured with the thermometers fixed to the carrier arm during one of the rotations of the shaft  20 A at regular intervals. In other words, the surface temperature of the susceptor is measured during the maintenance operation. In Steps S 11  and S 12 , the offset data is updated if necessary in the same manner as the update procedures  1  and  2  described above. In an example, this update procedure (referred to as an update procedure  3 ) including Steps S 10 , S 11  and S 12  ends during the maintenance operation. 
     The update procedure  3  proceeds in parallel with the maintenance operation, so that the substrate procedure can be prevented from being delayed because of the update procedure. In Step S 13 , a fourth substrate procedure reflecting the latest offset data is performed. 
     According to the method of adjusting the temperature of the susceptor that involves updating the offset data at an appropriate frequency, the actual temperature of the substrate processed and the required wafer processing temperature according to the recipe can be made to agree with each other or brought close to each other. 
     The TMC  33  and the UPC  52  shown in  FIG. 2  serve as the control unit that acquires the measured temperature, which is the surface temperature, of the susceptor obtained by the thermometers and controls the temperature regulator  54 . The control unit may be a single integrated controller.