Plasma Doping Method and Apparatus

Abstract

It is intended to provide a plasma doping method and apparatus which are superior in the controllability of the concentration of an impurity that is introduced into a surface layer of a sample. A prescribed gas is introduced into a vacuum container 1 from a gas supply apparatus 2 while being exhausted by a turbomolecular pump 3 as an exhaust apparatus. The pressure in the vacuum container 1 is kept at a prescribed value by a pressure regulating valve 4 . High-frequency electric power of 13.56 MHz is supplied from a high-frequency power source 5 to a coil 8 disposed close to a dielectric window 7 which is opposed to a sample electrode 6 , whereby induction-coupled plasma is generated in the vacuum container 1 . A high-frequency power source 10 for supplying high-frequency electric power to the sample electrode 6 is provided. Every time a prescribed number of samples have been processed, a dummy sample is subjected to plasma doping and then to heating. The conditions for processing of a sample are controlled so that the measurement value of the surface sheet resistance becomes equal to a prescribed value, whereby the controllability of the impurity concentration can be increased.

1 . A plasma doping method for generating plasma in a vacuum container and introducing impurity ions into a surface layer of a sample by causing impurity ions in the plasma to collide with a surface of the sample, comprising the steps of:
 introducing impurity ions into a prescribed number of samples and a dummy sample by plasma doping;   establishing a state that a physical quantity corresponding an amount of impurity ions in the dummy sample by applying necessary energy to the impurity-ions-introduced dummy sample can be measured; and   controlling sample processing conditions so that the physical quantity becomes equal to a predetermined, prescribed value.   
     
     
         2 . The plasma doping method according to  claim 1 , wherein:
 the plasma doping method is such that a sample is placed on a sample electrode provided in the vacuum container, a gas is supplied to inside the vacuum container from a gas supply apparatus while the vacuum container is exhausted, plasma is generated in the vacuum container by supplying electric power to the sample electrode while pressure in the vacuum container is controlled to a prescribed value, and impurity ions are introduced into a surface layer of the sample by causing impurity ions in the plasma to be accelerated toward and collide with a surface of the sample; and   the controlling step comprises the substeps of heating the impurity-ions-supplied dummy sample, measuring a sheet resistance of the heated dummy sample, and controlling plasma doping conditions for the sample so that the measured sheet resistance of the dummy sample becomes equal to a prescribed value.   
     
     
         3 . The plasma doping method according to  claim 1 , wherein the controlling step comprises the substeps of irradiating the impurity-ions-implanted dummy sample with a low-energy electron beam, detecting an X-ray radiated from the dummy sample, and controlling plasma doping conditions for the sample so that a detected dose of the X-ray having a prescribed wavelength or a dose calculated from the detected X-ray dose becomes equal to a prescribed value. 
     
     
         4 . The plasma doping method according to  claim 2  or  3 , wherein the plasma doping is processing in which plasma is generated in the vacuum container by supplying high-frequency electric power to a plasma source. 
     
     
         5 . The plasma doping method according to  claim 2  or  3 , wherein the plasma doping conditions controlling step comprises the substep of changing the electric power that is supplied to the sample electrode. 
     
     
         6 . The plasma doping method according to  claim 2  or  3 , wherein the plasma doping conditions controlling step comprises the substep of changing a flow rate of a gas including an impurity element. 
     
     
         7 . The plasma doping method according to  claim 4 , wherein the plasma doping conditions controlling step comprises the substep of changing the high-frequency electric power that is supplied to the plasma source. 
     
     
         8 . The plasma doping method according to  claim 1 , comprising the step of changing a processing time in controlling sample processing conditions so that a sheet resistance becomes a prescribed value. 
     
     
         9 . The plasma doping method according to  claim 1 , wherein the sample is a silicon semiconductor wafer. 
     
     
         10 . The plasma doping method according to  claim 1 , wherein the impurity is one of arsenic, phosphorus, boron, aluminum, and antimony. 
     
     
         11 . The plasma doping method according to  claim 2 , comprising the step of putting the entire dummy sample into a high-temperature furnace in heating the dummy sample. 
     
     
         12 . The plasma doping method according to  claim 2 , comprising the step of irradiating a surface of the dummy sample with laser light in heating the dummy sample. 
     
     
         13 . The plasma doping method according to  claim 2 , comprising the step of irradiating a surface of the dummy sample with lamp radiation light in heating the dummy sample. 
     
     
         14 . The plasma doping method according to  claim 2 , comprising the step of heating the dummy sample in an inert gas atmosphere. 
     
     
         15 . The plasma doping method according to  claim 1 , wherein the dummy sample is a portion of a sample that is not necessary for devices to be formed on the sample. 
     
     
         16 . The plasma doping method according to  claim 3 , wherein energy of the electron beam is in a range of 200 eV to 9 keV. 
     
     
         17 . A plasma doping apparatus comprising:
 a plasma doping chamber provided with a vacuum container, a sample electrode, gas supply means for supplying a gas to inside the vacuum container, exhausting means for exhausting the vacuum container, pressure control means for controlling pressure in the vacuum container, and plasma supply means for supplying plasma to a sample, and a sample electrode power source for supplying electric power to the sample electrode;   energy supplying means for applying energy to the sample; and   physical quantity measuring means for measuring a physical quantity of the sample.   
     
     
         18 . The plasma doping apparatus according to  claim 17 , wherein the plasma supplying means comprises a plasma source and a plasma high-frequency power source for supplying high-frequency electric power to the plasma source. 
     
     
         19 . The plasma doping apparatus according to  claim 17  or  18 , wherein the energy supplying means is heating means and the physical quantity measuring means is sheet resistance measuring means. 
     
     
         20 . The plasma doping apparatus according to  claim 17  or  18 , wherein the energy supplying means is an electron beam source for supplying an electron beam to the sample and the physical quantity measuring means is X-ray analyzing means comprising an X-ray detector. 
     
     
         21 . The plasma doping apparatus according to  claim 19 , wherein the heating means is a high-temperature furnace. 
     
     
         22 . The plasma doping apparatus according to  claim 19 , wherein the heating means is a laser annealing device which radiates laser light. 
     
     
         23 . The plasma doping apparatus according to  claim 19 , wherein the heating means is a laser annealing device which irradiates only a portion of the sample with laser light. 
     
     
         24 . The plasma doping apparatus according to  claim 19 , wherein the heating means is a lamp annealing device which radiates lamp radiation light. 
     
     
         25 . The plasma doping apparatus according to  claim 24 , wherein the heating means is a lamp annealing device which irradiates only a portion of the sample with lamp radiation light. 
     
     
         26 . The plasma doping apparatus according to  claim 19 , wherein the heating means comprises gas supplying means for supplying an inert gas to inside a heating chamber.