Calorimetric dose monitor for ion implantation equipment

Claim 3

Apparatus for determining ion beam dose during ion implantation of semiconductor wafers comprising: ion source means for directing a beam of ions to an implant station; semiconductor wafer support means comprising a disk mounted for rotation and having multiple implantation sites for periodically rotating one or more semiconductor wafers through the ion beam to treat said wafers; calorimeter means fixed to said wafer support means between two of the implantation sites and having a beam facing surface to periodically intercept said beam, said calorimeter means including thermal path means for conducting heat generated when the ions impact the beam facing surface away from said beam facing surface along the thermal path means; heat sink means maintained at a reference temperature in thermal contact with said thermal path means for maintaining a portion of the thermal path means at a relatively uniform temperature; temperature sensing means for measuring a temperature difference between two points along said thermal path; and means for converting said temperature difference to a beam dose.

Claim 4

Apparatus for determining ion beam dose during ion implantation of semiconductor wafers comprising: ion source means for directing a beam of ions to an implant station; semiconductor wafer support means comprising a disk mounted for rotation and having multiple implantation sites for periodically rotating one or more semiconductor wafers through the ion beam to treat said wafers; calorimeter means fixed to said wafer support means between two of the implantation sites and having a beam facing surface to periodically intercept said beam, said calorimeter means including thermal path means for conducting heat generated when the ions impact the beam facing surface away from said beam facing surface along the thermal path means; heat sink means maintained at a reference temperature in thermal contact with said thermal path means for maintaining a portion of the thermal path means at a relatively uniform temperature; temperature sensing means for measuring a temperature difference between two points along said thermal path; and means for converting said temperature difference to a beam dose.

Claim 5

An apparatus of claim 2 wherein the beam facing surface of said calorimeter is generally rectangular and has a length approximately equal to a maximum width of said wafers.

Claim 6

The apparatus of claim 2 wherein the temperature sensing means comprises two thermistors spaced along the thermal path for converting a temperature into an electrical output.

Claim 7

The apparatus of claim 4 wherein the thermal path means comprises a tungsten rod coupled to a calorimeter mass at one end and the heat sink at an opposite end.

Claim 8

The apparatus of claim 3 where the calorimeter means comprises a silicon layer covering a silver calorimeter mass.

Claim 9

The apparatus of claim 2 where the calorimeter means comprises a number of different calorimeter masses spaced to intercept different portions of the ion beam, each having a separate thermal path means.

Claim 10

Apparatus for determining ion beam dose during ion implantation of semiconductor wafers comprising: ion source means for directing a beam of ions to an implant station; semiconductor wafer support means comprising a disk mounted for rotation having a support surface defining multiple implantation sites for rotating one or more semiconductor wafers through the ion beam to treat said wafers said support surface defining at least one opening to intercept said beam of ions at periodic intervals to define at least one beam dose determining position; calorimeter means fixed to the disk between two of the implantation sites having a beam facing surface positioned to periodically intercept said beam as said at least one opening intercepts said beam, said calorimeter means including thermal path means for conducting heat away from said surface as the heat is generated by beam impingement on the beam facing surface of the calorimeter; heat sink means in thermal contact with said thermal path for maintaining a part of the thermal path means at a reference temperature; temperature sensing means for measuring a temperature gradient along said thermal path; and means for converting said temperature gradient to a beam dose.

Claim 11

Apparatus for determining ion beam dose during ion implantation of semiconductor wafers comprising: ion source means for directing a beam of ions to an implant station; semiconductor wafer support means comprising a disk mounted for rotation having a support surface defining multiple implantation sites for rotating one or more semiconductor wafers through the ion beam to treat said wafers said support surface defining at least one opening to intercept said beam of ions at periodic intervals to define at least one beam dose determining position; calorimeter means fixed to the disk between two of the implantation sites having a beam facing surface positioned to periodically intercept said beam as said at least one opening intercepts said beam, said calorimeter means including thermal path means for conducting heat away from said surface as the heat is generated by beam impingement on the beam facing surface of the calorimeter; heat sink means in thermal contact with said thermal path for maintaining a part of the thermal path means at a reference temperature; temperature sensing means for measuring a temperature gradient along said thermal path; and means for converting said temperature gradient to a beam dose.

Claim 12

The apparatus of claim 8 where the disk defines a multiple number of openings spaced at different distances from an axis of disk rotation and the calorimeter means comprises multiple calorimeter surfaces positioned to monitor beam dose as the beam intercepts the openings at different distances from the axis of disc rotation to sample different portions of the beam of ions and the means for converting includes means for determining ion beam dose at said multiple number of opening.

Claim 13

The apparatus of claim 8 where the means to convert additionally comprises control means to adjust beam dose to a desired level.