CN100511592C - Plasma doping method - Google Patents
Plasma doping method Download PDFInfo
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- CN100511592C CN100511592C CNB2007101119963A CN200710111996A CN100511592C CN 100511592 C CN100511592 C CN 100511592C CN B2007101119963 A CNB2007101119963 A CN B2007101119963A CN 200710111996 A CN200710111996 A CN 200710111996A CN 100511592 C CN100511592 C CN 100511592C
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Abstract
The invention provides a plasma doping method capable of carrying out low-concentration doping stably, which adds impurities into samples or the film on the surface of the samples. The method includes three stages: the first stage, placing a sample on a sample electrode in a vacuum vessel; the second stage, supplying a gas without containing doping material into the vacuum vessel and exhausting the gas synchronously, controlling the pressure of the vacuum vessel at the first pressure and supplying high frequency power to a plasma source so as to generate plasma in the vacuum vessel; the third stage, retaining the state of generating plasma, supplying the gas containing doping material into the vacuum vessel and exhausting the gas synchronously, controlling the pressure of the vacuum vessel at the second pressure which is different from the first pressure.
Description
The application is to be the Chinese application number on September 30th, 2003 the dividing an application for the Chinese patent application of " plasma doping and plasma doping apparatus " that be 03127235.5 title the applying date.
Technical field
The present invention relates at the plasma doping of surface doping (interpolation) impurity of solid samples such as semiconductor substrate and implement the device of this method.
Background technology
In the technology of the surface doping impurity of solid sample, for example have that the U.S patent discloses for No. 4912065 with foreign ionization with the plasma doping of low energy dopant in the solid.
Below, with reference to Figure 14 explanation plasma doping in the past as the method for doping impurity.
Figure 14 is the basic structure of the plasma doping apparatus that adopted of plasma doping method in the past.Among Figure 14, in vacuum tank 100, be provided with the specimen electrode 106 that is used to place samples 109 such as silicon substrate.Be used to supply with in the outer setting of vacuum tank 100 and contain the doped raw material gas of wanting element to some extent, for example B
2H
6Feeder 102 and with the pump 103 of the inner pressure relief in the vacuum tank 100, vacuum tank 100 inside can be remained on the pressure of regulation.Irradiate microwaves in the vacuum tank 100 through quartz plate 107 by microwave plumbing 119 as medium window.The interaction of the D.C. magnetic field that forms by this microwave with by electromagnet 114, the zone shown in the dotted line 120 in vacuum tank 100 forms the electron cyclotron resonance plasma.High frequency electric source 110 is connected the current potential of control specimen electrode 106 by capacitor 121 with specimen electrode 106.
In the plasma doping apparatus of this structure, from the doped raw material gas of feeder 102 inputs, for example B
2H
6, the plasma producing apparatus that constitutes by microwave plumbing 119 and electromagnet 114 is by plasmaization, and the current potential that the boron ion in the plasma 120 is produced owing to high frequency electric source 110 is doped to the surface of sample 109.
After forming metallic wiring layer on the sample of the above-mentioned impurity that mixed machined objects (work) such as () semiconductor substrates 109, in the oxygen atmosphere of regulation, on metallic wiring layer, form thin oxide-film by other operation.Thereafter, employing CVD device etc. forms gate electrode on sample 109, for example can obtain MOS transistor.
Contain the gas that in being doped to samples such as silicon substrate, shows electroactive impurity, as B
2H
6Etc. the doped raw material gas ubiquity problem high to the harmfulness of human body.
In the plasma doping method, the contained all substances of doped raw material gas all are doped in the sample.With by B
2H
6The doped raw material gas that constitutes is that example explains, and in the time of in being doped to sample, having only boron is effective impurity, but hydrogen also has been doped in the sample simultaneously.If hydrogen doping is in sample, the problem of lattice defect will appear producing in sample when epitaxial growth etc. is heat-treated continuously.
Prevent that this problem from having a kind of method, that is, will contain the impurity solid that in being doped to sample such as silicon substrate, shows electroactive impurity and be placed in the vacuum tank, in vacuum tank, produce the method for the plasma of inert gas simultaneously.This method is passed through the ion sputtering impurity solid by the plasma of inert gas, and impurity is separated from the impurity solid.This method is recorded in Japanese patent laid-open 09-115851 number.The structure of the plasma doping apparatus that mixes with this method is seen Figure 15.Among Figure 15, in vacuum tank 100, be provided with the specimen electrode 106 that is used to place the sample 109 that constitutes by silicon substrate.In the outer setting of vacuum tank 100 pump 103 that is used to supply with the feeder 102 of inert gas and makes the inner pressure relief of vacuum tank 100, vacuum tank 100 inside can be remained on the pressure of regulation.Irradiate microwaves in the vacuum tank 100 through quartz plate 107 by microwave plumbing 119 as medium window.Zone shown in the dotted line 120 of interaction in vacuum tank 100 of the D.C. magnetic field that forms by this microwave with by electromagnet 114 forms the electron cyclotron resonance plasma.High frequency electric source 110 is connected 106 current potential of control specimen electrode by capacitor 121 with specimen electrode 106.With impure element for example the impurity solid 122 of boron be placed on solid and keep on the platform 123, solid keeps the current potential of platform 123 by high frequency electric source 125 controls that connect by capacitor 124.
In the plasma doping apparatus of above-mentioned structure shown in Figure 15, inert gas from feeder 102 inputs, for example argon gas (Ar) passes through the plasma producing apparatus of microwave plumbing 119 and electromagnet 114 formations by plasmaization, utilize sputter to be ionized, be doped to the surface of sample 109 from the part that the impurity solid is splashed to the impurity element the plasma.
But, all exist low concentration doping can not stablize the problem of the poor reproducibility of carrying out, handling in above-mentioned Figure 14 and the dual mode in the past shown in Figure 15.To carry out low concentration doping with doped raw material gas, just must reduce the pressure in the vacuum tank, and reduce the dividing potential drop of doped raw material gas.In this case, generally with inert gas helium dilution doped raw material gas.This is because the following advantage of helium is promptly little because the helium ion spills rate, and is therefore little to the ionizing radiation damage of sample.But, therefore just be difficult under the desirable low concentration doping condition and handle owing to also exist helium under low pressure to be difficult to the difficult point that begins to discharge.
When adopting the impurity solid to carry out low concentration doping, also must reduce the pressure in the vacuum tank not adopting doped raw material gas.When inert gas uses argon gas, under low pressure begin discharge easily, still be difficult under desirable low concentration doping condition, handle though compare with helium.Identical with the situation that adopts doped raw material gas in this.
Open 2000-309868 number the Japan Patent spy and announced a kind of method, that is,,, can light a fire exactly by improving the pressure in the vacuum tank of plasma igniting stage (generating step) at the sputter equipment that has adopted argon gas.But this method, owing to improve the technical process that therefore pressure can not be applicable to fully that this class of plasma doping is extremely responsive to impurity.
Improve ignition quality, need to improve the pressure in the vacuum tank of ignition phase, form the condition of the discharge that is suitable for ignition phase, reduce pressure etc. in the doping stage and can effectively change discharging condition.But if conditions such as change pressure, then the variation of impedance discharge is big.Exist the action of the match circuit of the impedance matching be used to carry out high frequency power can not make corresponding variation thus, thereby produce the problem of bigger reflection power with the variation of impedance.That is, general match circuit adopts the variable capacitor (being short-term when using microwave) of the moving part that has motor driven as 2 variable-impedance device.Thus, motor makes the moving part rotation, and the change impedance needs the time more than 1 second.The reappearance that the generation of reflection power causes handling descends.Also have, also can produce noise under some situation, cause the misoperation of equipment.Sometimes, the rotation (motion) of variable capacitor (perhaps short-term) does not stop at assigned position but has surpassed, and plasma will disappear like this.
If in plasma doping apparatus input microwave and high frequency power, the match circuit that then is arranged between high frequency electric source and plasma producing apparatus or specimen electrode is just started working.But match circuit is started working to complete inhibitory reflex wavefront, generally needs hundreds of msec to number sec.And because this time is all different in each reprocessing, therefore controlled and poor reproducibility is difficult to stably obtain desirable doping content.
Particularly carrying out doping content is 1 * 10
11Atm/cm
2～1 * 10
15Atm/cm
2Low concentration doping the time because the processing time is shorter, from number sec～ten number sec, so the discrete influence of reflected wave is bigger.
In the process that plasma doping is handled, keeping producing under the state of plasma, when changing at least 1 Control Parameter in the Control Parameter such as kind, gas flow, pressure, high frequency power of gas, the time point that changes in Control Parameter easily produces reflected wave greatly.Because this transmitted wave is discrete big, so the controlled and reappearance variation of doping content.
Summary of the invention
The purpose of this invention is to provide a kind of device that the method for low concentration doping can stably be carried out and implement this method.
Plasma doping of the present invention is the plasma doping that adds (doping) impurity in the film of sample or specimen surface.The feature of this method is to comprise following 3 stages, and the 1st stage was that the specimen electrode in vacuum tank is placed sample; The 2nd stage was to discharge gas on one side in vacuum tank by on one side gas being imported in the vacuum tank, made to plasma source supply high frequency power when the pressure in the vacuum tank is controlled at the 1st pressure to produce plasma in the vacuum tank; The 3rd stage was under the state that keeps the generation plasma, and the pressure in the vacuum tank is controlled at 2nd pressure lower than the 1st pressure.
Adopt plasma doping of the present invention, on one side from vacuum tank in discharge gas by gas being inputed in the vacuum tank on one side, produce plasma to plasma source supply high frequency power when the pressure in the vacuum tank is controlled at the 1st pressure.In this state, the pressure in the vacuum tank is controlled at 2nd pressure lower than the 1st pressure, can realizes stable low concentration doping thus.
Another plasma doping of the present invention also is the plasma doping that adds impurity in the film of sample or specimen surface, and the feature of this method is to comprise following 3 stages, and the 1st stage was that the specimen electrode in vacuum tank is placed sample; The 2nd stage was to input in the vacuum tank by the gas that will contain on one side the inert gas beyond the helium to discharge gas on one side in vacuum tank, made to plasma source supply high frequency power when the pressure in the vacuum tank is controlled at the 1st pressure to produce plasma in the vacuum tank; The 3rd stage was keep to produce under the state of plasma, on one side will contain helium gas input in the vacuum tank and in vacuum tank, discharge gas on one side, the pressure in the vacuum tank is controlled at the 2nd pressure.
Adopt this plasma doping of the present invention, input in the vacuum tank by the gas that will contain on one side the inert gas beyond the helium and in vacuum tank, to discharge gas on one side, produce plasma to plasma source supply high frequency power when the pressure in the vacuum tank is controlled at the 1st pressure.In this state, on one side will contain helium gas input in the vacuum tank and in vacuum tank, discharge gas on one side, the pressure in the vacuum tank is controlled at the 2nd pressure, can realize stable low concentration doping thus.
Another plasma doping of the present invention also is the plasma doping that adds impurity in the film of sample or specimen surface, and the feature of this method is to comprise following 3 stages, and the 1st stage was that the specimen electrode in vacuum tank is placed sample; The 2nd stage was to discharge gas on one side in vacuum tank by on one side gas being inputed in the vacuum tank, made to plasma source supply high frequency power when the pressure in the vacuum tank is controlled at the 1st pressure to produce plasma in the vacuum tank; The 3rd stage was to keep producing under the state of plasma, on one side the pressure in the vacuum tank is controlled at the 2nd pressure on one side to the high frequency power big high frequency power of plasma source supply than the 2nd stage.
Adopt this plasma doping of the present invention, in vacuum tank, discharge gas on one side on one side, the vacuum tank inner control is produced plasma to plasma source supply high frequency power in the 1st pressure by gas being inputed in the vacuum tank.In this state, the pressure in the vacuum tank is controlled at the 2nd pressure, the big high frequency power of high frequency power when plasma source is supplied with than plasma generation can realize stable low concentration doping thus.
Another plasma doping of the present invention also is the plasma doping that adds impurity in the film of sample or specimen surface, and the feature of this method is to comprise following 3 stages, and the 1st stage was that the specimen electrode in vacuum tank is placed sample; The 2nd stage was to input in the vacuum tank by the gas that will not contain on one side doped raw material gas to discharge gas on one side in vacuum tank, made to plasma source supply high frequency power when the pressure in the vacuum tank is controlled at the 1st pressure to produce plasma in the vacuum tank; The 3rd stage was keep to produce under the state of plasma, on one side will contain doped raw material gas gas input in the vacuum tank and in vacuum tank, discharge gas on one side, the pressure in the vacuum tank is controlled at 2nd pressure different with the 1st pressure.
Adopt this plasma doping of the present invention, the gas that will not contain doped raw material gas on one side inputs in the vacuum tank discharges gas on one side in vacuum tank, the vacuum tank inner control is produced plasma to plasma source supply high frequency power in the 1st pressure.In this state, on one side will contain doped raw material gas gas input in the vacuum tank and in vacuum tank, discharge gas on one side, the pressure in the vacuum tank is controlled at the 2nd pressure, can realize stable low concentration doping thus.
Another plasma doping of the present invention is on one side gas to be input in the vacuum tank that plasma producing apparatus is housed, in vacuum tank, discharge gas on one side, by be equipped with as 2 variable-impedance device not with the plasma producing apparatus match circuit of the toroidal core of moving part, high frequency power supplied with plasma producing apparatus and make produce plasma in the vacuum tank, impurity is added to the plasma doping in the film of the sample that is positioned over the specimen electrode in the vacuum tank or specimen surface.The feature of this method is, produces under the state of plasma keeping, and at least 1 Control Parameter in the kind, gas flow, pressure, these Control Parameter of high frequency power of gas is changed.
Adopt this plasma doping of the present invention,, high frequency power is supplied with plasma producing apparatus and make and produce plasma in the vacuum tank by the plasma producing apparatus match circuit as the toroidal core of 2 impedance devices is housed.In this state, at least 1 Control Parameter in the kind, gas flow, pressure, high frequency power of gas is changed.Can realize stable low concentration doping thus, carry out the good plasma doping of reappearance.
Another plasma doping of the present invention is on one side gas to be input in the vacuum tank that plasma producing apparatus is housed, in vacuum tank, discharge gas on one side, with match circuit high frequency power is supplied with plasma producing apparatus by plasma producing apparatus and make and produce plasma in the vacuum tank, impurity is added to the plasma doping in the film of the sample that is positioned over the specimen electrode in the vacuum tank or specimen surface.The feature of this method is, keeping producing under the state of plasma, and at least 1 Control Parameter in the kind, gas flow, pressure, these Control Parameter of high frequency power of gas is changed.
Adopt this plasma doping of the present invention, with match circuit high frequency power is supplied with plasma producing apparatus by plasma producing apparatus and make and produce plasma in the vacuum tank, add impurity to specimen surface.Keep to produce under the state of plasma, with 1 second～5 seconds the time chien shih gas kind, gas flow, pressure, high frequency power at least 1 Control Parameter change.Can realize stable low concentration doping thus, carry out the good plasma doping of reappearance.
Plasma doping of the present invention is in the process that plasma doping is handled, keep to produce under the state of plasma, effective especially when at least 1 Control Parameter in the kind, gas flow, pressure, these Control Parameter of high frequency power of gas is changed.
Another plasma doping of the present invention is by on one side gas being input in the vacuum tank that plasma producing apparatus is housed, in vacuum tank, discharge gas on one side, high frequency power supplied with plasma producing apparatus and make produce plasma in the vacuum tank, high frequency power is supplied with specimen electrode in the vacuum tank, in the film of sample that is positioned over specimen electrode or specimen surface, add the plasma doping of impurity.The feature of this method is, the traveling wave power (forward power) of supplying with the high frequency power of plasma producing apparatus or specimen electrode is Pf, reflected wave power (reflected power) is when being Pr, value so that difference power Pf-Pr of traveling wave power P f and reflected wave power P r is gathered at the interval of 1msec～100msec stops supply high frequency power at difference power Pf-Pr by the time point that the time principal value of integral reaches predefined value.
Adopt this plasma doping of the present invention, the traveling wave power of supplying with the high frequency power of plasma producing apparatus or specimen electrode is Pf, when reflected wave power is Pr, value so that difference power Pf-Pr is gathered at the interval of 1msec～100msec stops supply high frequency power at the difference power Pf-Pr that gathers by the time point that the time principal value of integral reaches predefined value.Can realize controlled, the plasma doping that reappearance is good of doping content thus.
The feature of plasma doping apparatus of the present invention is to possess vacuum tank, be used for gas is imported feeder in the vacuum tank, be used in vacuum tank, discharging the exhaust apparatus of gas, be used for the pressure in the vacuum tank is controlled at the pressure regulating valve of authorized pressure, be used in vacuum tank, placing the specimen electrode of sample, plasma generating device, be equipped with as 2 variable-impedance device not with the plasma producing apparatus match circuit of the toroidal core of moving part, with match circuit high frequency power is supplied with the high frequency electric source of plasma producing apparatus by plasma producing apparatus.
Adopt the plasma doping apparatus of the invention described above, owing to possess by the high frequency electric source of not supplying with plasma producing apparatus with the plasma producing apparatus of the toroidal core of moving part with match circuit, with high frequency power as 2 variable-impedance device is housed, therefore stable low concentration doping can be realized, the good plasma doping of reappearance can be carried out simultaneously.
Another plasma doping apparatus of the present invention possess vacuum tank, with gas import feeder in the vacuum tank, discharge in the vacuum tank gas exhaust apparatus, with the pressure in the vacuum tank be controlled at the pressure regulating valve of authorized pressure, in vacuum tank, place sample specimen electrode, plasma generating device, high frequency power is supplied with the high frequency electric source of plasma producing apparatus and the high frequency electric source of high frequency power being supplied with specimen electrode.The traveling wave power that this plasma doper also possesses the high frequency power of supplying with plasma producing apparatus or specimen electrode is Pf, when reflected wave power is Pr, gather the sampler of the value of difference power Pf-Pr with the interval of 1msec～100msec, and the control device that stops supply high frequency power at the time point that difference power Pf-Pr reaches predefined value by the time principal value of integral.
Adopt the plasma doping apparatus of the invention described above, gather the value of difference power Pf-Pr with the interval of 1msec～100msec, stop supply high frequency power at difference power Pf-Pr by the time point that the time principal value of integral reaches predefined value, controlled, the plasma doping apparatus that reappearance is good of doping content can be provided thus.
Description of drawings
Fig. 1 adopts the mix profile of employed plasma doping apparatus of the plasma doping of embodiments of the invention 1～4.
Fig. 2 is the profile that the plasma doping of employing embodiments of the invention 1～4 carries out another example of the employed plasma doping apparatus of plasma doping.
Fig. 3 is the profile that the plasma doping of employing embodiments of the invention 1～4 carries out another example of the employed plasma doping apparatus of plasma doping.
Fig. 4 is the profile that the plasma doping of employing embodiments of the invention 1～4 carries out another example of the employed plasma doping apparatus of plasma doping.
Fig. 5 is the profile that the plasma doping of employing embodiments of the invention 1～4 carries out another example of the employed plasma doping apparatus of plasma doping.
Fig. 6 adopts the mix profile of employed plasma doping apparatus of the plasma doping of embodiments of the invention 5.
Fig. 7 is the circuit diagram that embodiments of the invention 5 used plasma producing apparatus are used match circuit.
Fig. 8 is the time diagram of the action of expression embodiments of the invention 5.
Fig. 9 is the time diagram of the action of expression embodiments of the invention 6.
Figure 10 adopts the mix profile of employed plasma doping apparatus of the plasma doping of embodiments of the invention 7.
Figure 11 is the time diagram of the action of expression embodiments of the invention 7.
Figure 12 represents the sampling interval of embodiments of the invention 7 and the discrete relation of doping content.
Figure 13 is the profile of another example of embodiments of the invention 7 employed plasma doping apparatus.
Figure 14 is a profile of implementing the plasma doping apparatus of plasma doping in the past.
Figure 15 is a profile of implementing the plasma doping apparatus of other plasma doping in the past.
Embodiment
Describe the preferred embodiment of plasma doping of the present invention in detail with reference to Fig. 1～Figure 13.
＜＜embodiment 1〉〉
Below, the plasma doping of embodiments of the invention 1 is described with reference to Fig. 1.
Fig. 1 adopts the mix profile of employed plasma doping apparatus of the plasma doping of embodiments of the invention 1.Among Fig. 1, at the inner space of vacuum tank 1 1a, the gas from feeder 2 input regulations carries out exhaust by the turbomolecular air pump 3 as exhaust apparatus.By pressure regulating valve 4 the inner space 1a of vacuum tank 1 is remained on the pressure of regulation, simultaneously from high frequency electric source 5 to be arranged on specimen electrode 6 opposed medium windows 7 near spiral coil 8 supply with the high frequency power of 13.56MHz.Thus, produce inductance coupling high type plasma, can handle carrying out plasma doping as the silicon substrate 9 that is placed on the sample (machined object) on the specimen electrode 6 at the inner space of vacuum tank 1 1a.By being provided for high frequency electric source 10 supply high frequency power to specimen electrode 6 supply high frequency power, can control the current potential of specimen electrode 6, make substrate 9 relative plasmas have negative current potential.Turbomolecular air pump 3 and exhaust outlet 11 be configured in specimen electrode 6 under.Pressure regulating valve 4 under the specimen electrode 6 and be positioned at turbomolecular air pump 3 directly over the buck valve.Specimen electrode 6 is fixed in the vacuum tank 1 by 4 supporting masses 12.The principal component of medium window 7 is quartz glasss.
After will being placed on specimen electrode 6 as the silicon substrate 9 of machined object, the temperature of specimen electrode 6 remained on 10 ℃ one side with 50sccm (standard cc/min) to vacuum tank 1 in import helium reach with 3sccm import diborane (B as doped raw material gas on one side
2H
6) gas.Pressure in the vacuum tank 1 is controlled at the 1st pressure 3Pa), to the high frequency power of supplying with the above-mentioned 13.56MHz of 800W as the coil 8 of plasma source, in vacuum tank 1, produce plasma simultaneously.Produce plasma after 1 second,, the pressure in the vacuum tank 1 is controlled at 2nd pressure (0.3Pa) lower than above-mentioned the 1st pressure (3Pa) keeping producing under the state of plasma.After the plasma stability, supply with the high frequency power of the above-mentioned 13.56MHz of 200W, lasted for 7 seconds to specimen electrode 6.By above technological process, boron can be doped to the near surface of substrate 9.Can mix at the film of being located at as the surface of the substrate 9 of sample too.Doping content is 2.5 * 10
13Atm/cm
2
As mentioned above, by carrying out the igniting of plasma under than the high pressure (3Pa) of the pressure (0.3Pa) of doping process, can realize more stable igniting.In above-mentioned technological process, owing to use with ionizing radiation to the plasma of the little helium of the damage of sample, so can stably carry out low concentration doping as main body.
Another kind method is in the stage that makes plasma igniting, the inert gas beyond the input helium, and effect is better like this.The igniting threshold pression of the inert gas beyond the helium is lower than helium, therefore, uses helium inert gas in addition, has the advantage that can carry out plasma igniting with lower pressure.
Another kind method is in the stage that makes plasma igniting, reduces to supply with the high frequency power of plasma source, and effect is also better like this.In this case, have and to reduce in the dysgenic advantage of ignition phase to substrate 9.
Another kind method is in the stage that makes plasma igniting, does not import doped raw material gas in vacuum tank, and effect is also better like this.In this case, have and to reduce in the dysgenic advantage of ignition phase to substrate 9.
＜＜embodiment 2〉〉
Then, with the embodiment 1 identical plasma doping that embodiments of the invention 2 are described with reference to Fig. 1.The item that illustrated at embodiment 1 among Fig. 1 refers to embodiment 2 too.
The structure of the plasma doping apparatus of Fig. 1 and elemental motion have been done detailed explanation in the above embodiment of the present invention 1, and therefore the repetitive description thereof will be omitted.
Among Fig. 1, silicon substrate 9 is placed on specimen electrode 6 after, on one side the temperature of specimen electrode 6 is remained on 10 ℃ of one side to vacuum tank 1 in, import argon gas with 50sccm and reaches with 3sccm and import diborane (B as doped raw material gas
2H
6) gas.Pressure in the vacuum tank 1 is controlled at the 1st pressure 0.8Pa, to the high frequency power of supplying with 800W as the coil 8 of plasma source, in vacuum tank 1, produces plasma simultaneously.Produce plasma after 1 second,, in vacuum tank 1, import helium with 50sccm keeping producing under the state of plasma.Stop to import argon gas in addition.After the plasma stability,, lasted for 7 seconds to the high frequency power of specimen electrode 6 supply 200W.Boron can be doped to the near surface of substrate 9 thus.Doping content is 4.2 * 10
13Atm/cm
2
As mentioned above, by carrying out the igniting of plasma, can realize more stable igniting with the gas that contains helium inert gas in addition.In above-mentioned technological process, owing to use with ionizing radiation to the plasma of the little helium of the damage of sample, so can stably carry out low concentration doping as main body.
In the embodiments of the invention 2, the pressure in making the stage increase vacuum tank of plasma igniting, effect is better like this.Has the advantage that more stably to carry out plasma igniting thus.
In the stage that makes plasma igniting, be preferably the high frequency power that reduces to supply with plasma source.In this case, have and to reduce in the dysgenic advantage of ignition phase to substrate 9.
In the stage that makes plasma igniting, be preferably not input doped raw material gas in vacuum tank.In this case, have and to reduce in the dysgenic advantage of ignition phase to substrate 9.
＜＜embodiment 3〉〉
Then, with the embodiment 1 identical plasma doping that embodiments of the invention 3 are described with reference to Fig. 1.The item that illustrated at embodiment 1 among Fig. 1 refers to embodiment 3 too.
The structure of the plasma doping apparatus of Fig. 1 and elemental motion have been done detailed explanation in the above embodiment of the present invention 1, and therefore the repetitive description thereof will be omitted.
Among Fig. 1, silicon substrate 9 is placed on specimen electrode 6 after, on one side the temperature of specimen electrode 6 is remained on 10 ℃, to vacuum tank 1 in, import helium with 50sccm on one side and reaches with 3sccm and import diborane (B as doped raw material gas
2H
6) gas.Pressure in the vacuum tank 1 is controlled at the 1st pressure 3Pa, to the high frequency power of supplying with 100W as the coil 8 of plasma source, in vacuum tank 1, produces plasma simultaneously.Behind the plasma igniting 1 second,, the pressure in the vacuum tank 1 is controlled at 2nd pressure (0.3Pa) lower than above-mentioned the 1st pressure (3Pa), the high frequency power of supplying with coil is increased to 800W keeping producing under the state of plasma.After the plasma stability,, lasted for 7 seconds, boron can be doped to the near surface of substrate 9 like this to the high frequency power of specimen electrode supply 200W.Doping content is 2.4 * 10
13Atm/cm
2
As mentioned above, when carrying out the igniting of plasma,, then can reduce in the harmful effect of ignition phase to sample if reduce to supply with the power of plasma source.Like this, use with ionizing radiation, can stably carry out low concentration doping the plasma of the little helium of the damage of sample as main body.
In the embodiments of the invention 3, the 2nd pressure and the 1st pressure same effect are better.In this case, also can reduce in the harmful effect of ignition phase sample.
In the stage that makes plasma igniting, the inert gas effect beyond the input helium is better.The threshold pression of the general igniting of the inert gas beyond the helium is lower than helium.Therefore, use helium inert gas in addition, have the advantage that to carry out plasma igniting with lower pressure.
In the stage that makes plasma igniting, input doped raw material gas effect is not better yet in vacuum tank.In this case, have and to reduce in the dysgenic advantage of ignition phase to sample.
＜＜embodiment 4〉〉
Then, with the embodiment 1 identical plasma doping that embodiments of the invention 4 are described with reference to Fig. 1.The item that illustrated at embodiment 1 among Fig. 1 refers to embodiment 4 too.
The structure of the plasma doping apparatus of Fig. 1 and elemental motion have been done detailed explanation in the above embodiment of the present invention 1, and therefore the repetitive description thereof will be omitted.
Among Fig. 1, silicon substrate 9 is placed on specimen electrode 6 after, on one side the temperature of specimen electrode 6 is remained on 10 ℃, in vacuum tank 1, import helium with 50sccm on one side.Pressure in the vacuum tank 1 is controlled at the 1st pressure 3Pa, to the high frequency power of supplying with 800W as the coil 8 of plasma source, makes and produce plasma in the vacuum tank 1 simultaneously.Behind the plasma igniting 1 second,, the pressure in the vacuum tank 1 is controlled at 2nd pressure (0.3Pa) lower than above-mentioned the 1st pressure (3Pa), with the diborane (B of 3sccm input as doped raw material gas keeping producing under the state of plasma
2H
6) gas.After the plasma stability,, lasted for 7 seconds to the high frequency power of specimen electrode supply 200W.Boron can be doped to the near surface of substrate 9 thus.Doping content is 2.4 * 10
13Atm/cm
2
As mentioned above, at the ignition phase that carries out plasma, use the gas that does not contain doped raw material gas, reduce thus in the harmful effect of ignition phase sample, use simultaneously with ionizing radiation the plasma of the little helium of the damage of sample, can stably carry out low concentration doping as main body.
Among the embodiment 4, the 2nd pressure and the 1st pressure same effect are better.Can reduce like this in the harmful effect of ignition phase sample.
In the stage that makes plasma igniting, the inert gas effect beyond the input helium is better.Inert gas beyond the helium threshold pression of generally lighting a fire is lower than helium.Therefore has the advantage that to carry out plasma igniting with lower pressure.
In the stage that makes plasma igniting, the high frequency power effect that reduces to supply with plasma source is better.Have thus and can reduce in the dysgenic advantage of ignition phase to sample.
The range of application of the plasma doping of above-described embodiments of the invention 1～embodiment 4 is not limited to the employed device shown in Figure 1 of the various embodiments described above.Fig. 1 has only exemplified the part in the various variations of aspects such as the mode of shape at vacuum tank, plasma source and configuration.Plasma doping of the present invention certainly can also be applied to the various device that to some extent change except that illustrational here.
For example, plasma doping of the present invention can be applicable to the device of structure shown in Figure 2, and coil 8 is the helical form on plane in this device.
Plasma doping of the present invention can also be applicable to device shown in Figure 3, replaces coil 8 with antenna 13 in this device, uses electromagnet 14 as magnetic field generation device.In this case, can in vacuum tank 1, form Helicon wave plasma, produce the highdensity plasma higher than inductance coupling high type plasma density.By the electric current of control flows, can in vacuum tank 1, apply D.C. magnetic field or the low frequency magnetic field below the frequency 1kHz to electromagnet 14.
Plasma doping of the present invention also goes for device shown in Figure 4, replaces coils 8 with antenna 13 and as 2 electromagnet 14a, 14b of magnetic field generation device in this device.In this case, flow through 2 electromagnet 14a, 14b, can in vacuum tank, form magnetic neutral loop plasma by making reverse each other electric current.Magnetic neutral loop plasma can produce the highdensity plasma higher than inductance coupling high type plasma density.Flow in the electric current of electromagnet 14a, 14b by control, can in vacuum tank 1, apply D.C. magnetic field or the low frequency magnetic field below the frequency 1kHz.
Fig. 5 is the profile of another example of plasma doping apparatus.Among Fig. 5, the gas of in vacuum tank 1, stipulating from feeder 2 inputs on one side, by turbomolecular air pump 3 as exhaust apparatus carry out exhaust on one side.By pressure regulating valve 4 pressure in the vacuum tank 1 is remained on the pressure of regulation, simultaneously by high frequency electric source 5 to be arranged on specimen electrode 6 opposed medium windows 7 near coil 8 supply with the high frequency power of 13.56MHz.In vacuum tank 1, produce inductance coupling high type plasma thus, the silicon substrate 9 as sample (machined object) that is placed on the specimen electrode 6 is carried out the plasma doping processing.Be provided for high frequency electric source 10 to specimen electrode 6 supply high frequency power.From high frequency electric source 10 supply high frequency power, can control the current potential of specimen electrode 6, make substrate 9 relative plasmas have negative current potential.Turbomolecular air pump 3 and exhaust outlet 11 be configured in specimen electrode 6 under.Pressure regulating valve 4 under the specimen electrode 6 and be positioned at turbomolecular air pump 3 directly over the buck valve.Specimen electrode 6 is fixed in the vacuum tank 1 by 4 supporting masses 12.The principal component of medium window 7 is quartz glasss, makes the boron that contains in the quartz glass as impurity.
Be provided for high frequency electric source 16 to the high frequency power that is disposed at the bias electrode 15 supply frequency 500kHz between coil 8 and the medium window 7.Bias electrode 15 is to be configured to a plurality of known band electrodes radial and to form.The state configuration that vertically intersects vertically with band shape by conductor with spiral helicine coil 8.Adopt this configuration, bias electrode 15 can not influenced from the electromagnetic field of high frequency that coil 8 sends substantially be radiated in the vacuum tank 1.Bias electrode 15 is the whole zone of overwrite media window 7 almost, during sputter medium window 7, can control as the boron diffusion of the quartz glass impurities amount in the plasma.The reflected wave testing circuit 20 that constitutes by band pass filter 17 and reflected wave meter 18 in the output setting of high frequency electric source 5.Band pass filter 17 be set be the circuit of detection of reflected wave of high frequency power of the frequency 13.56MHz of the modulation effects high frequency electric source 5 that causes as the high frequency power that is used to prevent from the frequency 500kHz of high frequency electric source 16.Band pass filter 17 can be eliminated owing to supply with the high frequency power of frequency 500kHz, the influence that the cladding thickness on the surface of medium window 7 changes and produced at frequency 500kHz.Band pass filter 17 is the reflected waves that are used in the high frequency power of frequency 13.56MHz, only extracts the composition of 13.56MHz, by reflected wave meter 18 detected devices.In this structure, by the reflected wave of the high frequency power of reflected wave meter 18 monitoring frequency 13.56MHzs on one side handle on one side.Can detect the fault of the high frequency electric source of matching status and frequency 13.56MHz thus in real time.
By adopting this structure, can in vacuum tank 1, not import doped raw material gas, and the doped raw material that produces by the medium window 7 of the impurity that contains solid, shaped, with doping impurity in the film of sample or specimen surface.
In the above-described various embodiments of the present invention, when the 2nd pressure ratio the 1st pressure is low, to light a fire conscientiously and realize low concentration doping, more satisfactory is that the 1st pressure is 1Pa～10Pa, the 2nd pressure is 0.01Pa～1Pa, better scope is that the 1st pressure is 2Pa～5Pa, and the 2nd pressure is 0.01Pa～0.5Pa.
When using the inert gas beyond the helium, preferably use at least a kind of gas in neon, argon, krypton or the xenon.These inert gases have compares other gas advantage little to the harmful effect of sample.
At ignition phase, reduce to supply with under the situation of high frequency power of plasma source, to lighting a fire effectively, and be suppressed at the harmful effect of ignition phase to sample, realize that the low concentration doping effect is preferable.For this reason, the high frequency power of supplying with plasma source at ignition phase be to supply with 1/100～1/2 ideal comparatively of the high frequency power of plasma source in the doping stage.The high frequency power of supplying with plasma source at ignition phase be that 1/20～1/5 in the high frequency power of doping stage supply plasma source is better.
During input doped raw material gas, realize low concentration doping in vacuum tank, the dividing potential drop of doped raw material gas be 1/1000～1/5 ideal comparatively of the pressure in the vacuum tank in the stage of doping.The dividing potential drop of doped raw material gas is that 1/100～1/10 of pressure in the vacuum tank in stage that mixes is better.
In the various embodiments described above, exemplified the situation of sample, but when handling the sample of other various materials, also can use plasma doping of the present invention for the semiconductor substrate that constitutes by silicon.
In the various embodiments described above, having exemplified impurity is the situation of boron, and under the situation of sample for the semiconductor substrate that is made of silicon, the present invention is effective especially when impurity is arsenic, phosphorus, boron, aluminium or antimony.This is because can form more shallow joint in transistor part.
Method of the present invention is effective when doping content is low concentration, as with 1 * 10
11Atm/cm
2～1 * 10
17Atm/cm
2Very effective during for the plasma doping of target.As with 1 * 10
11Atm/cm
2～1 * 10
14Atm/cm
2Effective especially during for the plasma doping of target.
The present invention also is effectively to the situation of using electron cyclotron resonance (ECR) plasma, but effective especially when not using ecr plasma.Ecr plasma has the also advantage of igniting easily of plasma under low pressure.But, because near the D.C. magnetic field the sample is big, the separation of charge of electronics and ion easily takes place, there is the shortcoming of the homogeneity difference of doping.That is to say, do not use ecr plasma to use the plasma doping of other high-density plasma source, can realize the low concentration doping that homogeneity is better by the present invention is applied to.
＜＜embodiment 5〉〉
With reference to Fig. 6～Fig. 8, the plasma doping of embodiments of the invention 5 is described.
The profile of the employed plasma doping apparatus of plasma doping of embodiments of the invention 5 is seen Fig. 6.Among Fig. 6, will be placed on as the silicon substrate 9 of sample (machined object) on the specimen electrode 6 that is arranged in the vacuum tank 1.The gas of in vacuum tank 1, stipulating from feeder 2 inputs on one side, by turbomolecular air pump 3 as exhaust apparatus carry out exhaust on one side.By pressure regulating valve 4 pressure in the vacuum tank 1 is remained on the pressure of regulation, simultaneously by high frequency electric source 5 to be arranged on specimen electrode 6 opposed medium windows 7 near supply with the high frequency power of 13.56MHz as the coil 8 of plasma producing apparatus.In vacuum tank 1, produce inductance coupling high type plasma thus, can carry out the plasma doping processing the silicon substrate 9 that is placed on the specimen electrode 6.Control to the current potential of 10 pairs of specimen electrodes 6 of high frequency electric source of specimen electrode 6 supply high frequency power by being provided for, make substrate 9 relative plasmas have negative current potential.Turbomolecular air pump 3 and exhaust outlet 11 be configured in specimen electrode 6 under.Pressure regulating valve 4 under the specimen electrode 6 and be positioned at turbomolecular air pump 3 directly over the buck valve.Specimen electrode 6 is fixed in the vacuum tank 1 by 4 supporting masses 12.The principal component of medium window 7 is quartz glasss.At high frequency electric source 5 and 8 of coils plasma producing apparatus match circuit 33 is set.
Plasma producing apparatus is known commercially available products with match circuit 33, simply describes with reference to the block diagram of Fig. 7.If by high frequency electric source 5 supply high frequency power, then according to the signal from transducer 14, computing circuit 15 will be controlled voltage and output to toroidal core 16a, 16b at the input 33a of the match circuit 33 of output 33b connecting coil 8.Like this, because the permeability of toroidal core 16a, 16b changes, the inductance of high frequency also changes, can be to desirable matching status conversion.Plasma producing apparatus does not have moving part with match circuit 33, owing to only use toroidal core 16a, the 16b that can change impedance at the known signal of telecommunication, therefore mates the needed time below 1msec.
After silicon substrate 9 is placed on specimen electrode 6, on one side the temperature of specimen electrode 6 is remained on 10 ℃, to vacuum tank 1 in, import helium with 50sccm on one side and reach with 3sccm and import diborane (B as doped raw material gas
2H
6) gas.Pressure in the vacuum tank 1 is controlled at the 1st pressure 2Pa, to the high frequency power of supplying with 150W as the coil 8 of plasma source, in vacuum tank 1, produces plasma thus simultaneously.
The following technological process that present embodiment is described with reference to the time diagram of Fig. 8.At time t
1The high frequency power (high frequency power) of 150W is supplied with in beginning to coil 8.Beginning supply high frequency power is after 0.1 second, and under the state that keeps the generation plasma, the regulating and controlling valve makes and is in the 2nd pressure 1Pa lower than the 1st pressure (2Pa) in the vacuum tank 1.After 0.07 second, high frequency power is brought up to 800W, and supply with the high frequency power of 200W to specimen electrode.Thus can be with the near surface of doping impurity to substrate 9.Carry out above-mentioned processing 100 times continuously, the mean value of doping content is 2.5 * 10
13Atm/cm
2, its dispersion is ± 1.4%.
In order to compare to some extent, use the match circuit of use variable capacitor in the past to carry out the processing under the same terms.Consequently, produced bigger reflected wave having changed the pressure in the Control Parameter and the time point of high frequency power.Because this reflected wave is discrete, the mean value of the doping content when having carried out handling continuously for 100 times is 2.4 * 10
13Atm/cm
2, its dispersion is bigger, reach ± 2.8%.Present embodiment and in the past the waveform of reflected wave of example see Fig. 8.
As mentioned above, by carrying out the igniting of plasma under than the high pressure of the pressure in the stage of mixing, can realize stable igniting.Therefore, use with ionizing radiation, can stably carry out low concentration doping the plasma of the little helium of the damage of sample as main body.In the stage that makes plasma igniting,, can reduce in the harmful effect of ignition phase to sample by reducing to supply with the high frequency power of plasma source.Present embodiment adopted be equipped with as 2 variable-impedance device known not with the plasma producing apparatus of toroidal core 16a, the 16b of moving part with match circuit 33.Therefore, big reflected wave can be do not produced yet, the good processing of reappearance can be carried out even change Control Parameter.
Among the embodiment 5,, can import helium inert gas in addition in the stage that makes plasma igniting.In this case,, therefore use helium inert gas in addition, have the advantage that to carry out plasma igniting with lower pressure because the threshold pression of the igniting of the inert gas beyond the helium is lower than helium.
In the stage that makes plasma igniting, can in vacuum tank, not import doped raw material gas.In this case, also have and to reduce in the dysgenic advantage of ignition phase to sample.
＜＜embodiment 6〉〉
The plasma doping of embodiments of the invention 6 then, is described with reference to Fig. 9.
Identical in the plasma doping apparatus that plasma doping adopted of embodiment 6 and Figure 6 and Figure 7, therefore the repetitive description thereof will be omitted.
After being placed on silicon substrate 9 on the specimen electrode 6, on one side the temperature of specimen electrode 6 is remained on 10 ℃, to vacuum tank 1 in, import helium 5 with 50sccm on one side and reach with 3sccm and import diborane (B as doped raw material gas
2H
6) gas.Pressure in the vacuum tank 1 is controlled at the 1st pressure 2Pa, to the high frequency power of supplying with 200W as the coil 8 of plasma source, makes thus and produce plasma in the vacuum tank 1 simultaneously.
The technological process of present embodiment is described with reference to the time diagram of Fig. 9.At time t
1The high frequency power of 200W is supplied with in beginning to coil 8.Beginning supply high frequency power under the state that keeps the generation plasma, slowly increased the aperture of pressure regulating valve 4 after 0.5 second, made to be in 2nd pressure (1Pa) lower than the 1st pressure (2Pa) in the vacuum tank 1.Simultaneously in 2 seconds, slowly the high frequency power of coil 8 is brought up to 800W.With the time in 2.0 seconds, slowly change pressure and high frequency power as Control Parameter after, supply with the high frequency power of 200W to specimen electrode 6.Boron can be doped to the near surface of substrate 9 thus.Carry out such processing 100 times continuously, the mean value of doping content is 2.5 * 10
13Atm/cm
2, its dispersion is ± 0.9%.
As mentioned above, by carrying out the igniting of plasma under than the high pressure of the pressure in the stage of mixing, can realize stable igniting.Also have,, can stably carry out low concentration doping by using with ionizing radiation to the plasma of the little helium of the damage of sample as main body.In the stage that makes plasma igniting,, can reduce in the harmful effect of ignition phase to sample by reducing to supply with the high frequency power of plasma source.Adopted in the present embodiment be equipped with as 2 variable-impedance device not with the plasma producing apparatus of the known toroidal core shown in Figure 7 of moving part with match circuit 33.Therefore, big reflected wave can be do not produced yet, the good processing of reappearance can be carried out even change Control Parameter.Owing to slowly change pressure and high frequency power with time in 2 seconds, so the variation of impedance mitigation as Control Parameter, can further reduce the reflected wave that produces than embodiment shown in Figure 85, improve reappearance.
In the embodiments of the invention 6,, can import helium inert gas in addition in the stage that makes plasma igniting.In this case, because the threshold pression of the general igniting of the inert gas beyond the helium is lower than helium, so uses the inert gas beyond the helium, has the advantage that to carry out plasma igniting with lower pressure.
In the stage that makes plasma igniting, can in vacuum tank, not import doped raw material gas.In this case, also have and to reduce in the dysgenic advantage of ignition phase to sample.
In the present embodiment, exemplified the example that changes Control Parameter with the time in 2 seconds.The change of Control Parameter can 1 time in second～5 seconds carry out, this is because when using the plasma producing apparatus with variable capacitor to use match circuit, carries out the change of Control Parameter if use less than 1 second time, then can produce bigger reflected wave.Carry out the change of Control Parameter if use greater than 5 seconds time, then the processing time prolongs, and production efficiency reduces.
Embodiments of the invention 5 and embodiment 6, the only for example part in the range of application of clear plasma doping of the present invention.Plasma doping of the present invention can also be applied to the various devices that aspects such as the mode of shape, plasma source of vacuum tank and configuration change to some extent certainly.
For example, can make coil 8 plane as shown in Figure 2.In addition, can use Helicon wave plasma, also can adopt magnetic neutral loop plasma.
Can in vacuum tank 1, not import doped raw material gas, and the doped raw material that produces by solid, shaped impurity with doping impurity in the film of sample or specimen surface.
The present invention is keeping under the state of plasma generation, and the Control Parameter of change is effective especially when being at least 1 Control Parameter in the kind of gas, gas flow, pressure, these Control Parameter of high frequency power.
Keeping under the state of plasma generation, during from the 1st pressure change to the 2 pressure, it is the lowest that the 2nd pressure cans be compared to the 1st pressure most with pressure.Will light a fire effectively, and realize low concentration doping, the 1st pressure is 1Pa～10Pa, and the 2nd pressure is that 0.01Pa～1Pa is comparatively desirable, and the 1st pressure is 2Pa～5Pa, and the 2nd pressure is that 0.01Pa～0.5Pa is even more ideal.
When using the inert gas beyond the helium, preferably use at least a kind of gas in neon, argon, krypton or the xenon.These inert gases have compares other gas advantage little to the harmful effect of sample.
Reduce to supply with under the situation of high frequency power of plasma source, to lighting a fire effectively, and be suppressed at the harmful effect of ignition phase, realize that the low concentration doping effect is preferable sample at ignition phase.For this reason, the high frequency power of supplying with plasma source at ignition phase be to supply with 1/100～1/2 ideal comparatively of the high frequency power of plasma source in the doping stage.The high frequency power of supplying with plasma source at ignition phase be that 1/20～1/5 in the high frequency power of doping stage supply plasma source is better.
During input doped raw material gas, realize low concentration doping in vacuum tank, the dividing potential drop of doped raw material gas be 1/1000～1/5 ideal comparatively of the pressure in the vacuum tank in the stage of doping.The dividing potential drop of doped raw material gas is that 1/100～1/10 of pressure in the vacuum tank in stage that mixes is better.
In the foregoing description 1～6, exemplified sample and be the situation of the semiconductor substrate that constitutes by silicon, when handling the sample of other various materials, also can use plasma doping of the present invention.
In the foregoing description 1～6, having exemplified impurity is the situation of boron, and when sample was the semiconductor substrate that is made of silicon, the present invention was effective especially when impurity is arsenic, phosphorus, boron, aluminium or antimony.This is because can form more shallow joint in transistor part.
The plasma doping of the foregoing description 1～6 is that the situation of low concentration is effective to doping content.In the desired value as concentration is 1 * 10
11Atm/cm
2～1 * 10
17Atm/cm
2Plasma doping the time very effective.In the desired value as concentration is 1 * 10
11Atm/cm
2～1 * 10
14Atm/cm
2Plasma doping the time effective especially.
The plasma doping of the foregoing description 1～6 also is effectively to the situation of using electron cyclotron resonance (ECR) plasma, but effective especially when not using ecr plasma.Ecr plasma has the also advantage of igniting easily of plasma under low pressure.But, because near the D.C. magnetic field the sample is big, the separation of charge of electronics and ion easily takes place, so there is the shortcoming of the homogeneity difference of doping.That is to say, do not use ecr plasma and used the plasma doping of other high-density plasma source, can realize the low concentration doping that homogeneity is better.
＜＜embodiment 7〉〉
Below, the plasma doping of embodiments of the invention 7 is described with reference to Figure 10～Figure 12.
The profile of the employed plasma doping apparatus of plasma doping of embodiments of the invention 7 is seen Figure 10.In the plasma doping apparatus of Figure 10, the output of high frequency electric source 10 is supplied with specimen electrode 6 through sampler 37.Sampler 37 is by control device 44 control inputs.The output of control device 44 is supplied with by high frequency electric source 10, and controls it.In vacuum tank 1, from feeder 2 import the gas stipulated on one side, carry out exhaust by turbomolecular air pump 3 on one side as exhaust apparatus.By pressure regulating valve 4 pressure in the vacuum tank 1 is remained on the pressure of regulation, simultaneously by high frequency electric source 5 to be arranged on specimen electrode 6 opposed medium windows 7 near supply with the high frequency power of 13.56MHz as the coil 8 of plasma producing apparatus.In vacuum tank 1, produce inductance coupling high type plasma thus, the silicon substrate 9 as sample that is placed on the specimen electrode 6 is carried out the plasma doping processing.
Be used for to control the current potential of specimen electrode 6, make substrate 9 relative plasmas have negative current potential to the high frequency electric source 10 of specimen electrode 6 supply high frequency power.Turbomolecular air pump 3 and exhaust outlet 11 be configured in specimen electrode 6 under.Pressure regulating valve 4 under the specimen electrode 6 and be positioned at turbomolecular air pump 3 directly over the buck valve.Specimen electrode 6 is fixed in the vacuum tank 1 by 4 supporting masses 12.The principal component of medium window 7 is quartz glasss.
After silicon substrate 9 is placed on specimen electrode 6, on one side the temperature of specimen electrode 6 is remained on 10 ℃, to vacuum tank 1 in, import helium with 50sccm on one side and reach with 3sccm and import diborane (B as doped raw material gas
2H
6) gas.Pressure in the vacuum tank 1 is controlled at the 1st pressure 2Pa, to the high frequency power of supplying with 150W as the coil 8 of plasma source, makes and produce plasma in the vacuum tank 1 simultaneously.The technological process of present embodiment is described with reference to the time diagram of Figure 11.
At time t
1Beginning is to coil 8 supply high frequency power.Beginning supply high frequency power kept producing under the state of plasma after 1.0 seconds, and control pressure regulating valve 4 makes the pressure in the vacuum tank 1 be in 2nd pressure (1Pa) lower than the 1st pressure (2Pa).After pressure regulating valve 4 begins to control 0.8 second, high frequency power is brought up to 800W, and supply with the high frequency power of 200W, boron can be doped to the near surface of substrate 9 thus to specimen electrode.The traveling wave power of supplying with the high frequency power of specimen electrode 6 is Pf, when reflected wave power is Pr, is gathered the value of difference power Pf-Pr with the interval of 80msec by sampler 37.Stop supply high frequency power at the difference power Pf-Pr that gathers by the time point that the time principal value of integral reaches predefined value.Promptly in the chart bottom of Figure 11, reach the time point of 1400Wsec, stop to plasma producing apparatus 8 and specimen electrode 6 supply high frequency power with the value of region representation shown in the oblique line.
Carry out above-mentioned processing 100 times continuously, the mean value of doping content is 3.5 * 10
13Atm/cm
2, its dispersion is ± 1.2%.
Change the sampling interval of the value of difference power Pf-Pr, investigated the discrete of doping content.It is discrete that Figure 12 is illustrated in the concentration of each sampling interval when continuously handling 100 times.As can be seen from Figure 12, the sampling interval discrete sharply reduces below 100msec, can be reduced to the degree less than ± 1.5%.Sampling interval, dispersing further reduced, and is reduced to the degree less than ± 0.5% below 10msec.
As mentioned above, can carry out the good processing of reappearance is because utilized the relation that under gas of the same race, same flow, same pressure doping content and high frequency power that puts on specimen electrode 6 and processing time be ratio respectively.That is, reach the time point of predefined value at difference power Pf-Pr by the time principal value of integral, doping content reaches setting.At this time point, stop supply high frequency power and can make doping content be in setting.Even occur discretely under the situation of reflected wave producing, can detect the actual power of supplying with specimen electrode 6 by the value of gathering difference power Pf-Pr, thereby the integrated value of the difference power Pf-Pr that can obtain according to sampling is grasped doping accurately.
At present embodiment, the traveling wave power that has exemplified the high frequency power of supply specimen electrode 6 is Pf, when reflected wave power is Pr, gathers the situation of the value of difference power Pf-Pr.As other example, also can be Pf, when reflected wave power is Pr, gather the value of difference power Pf-Pr at the traveling wave power of the high frequency power of the coil 8 of supplying with plasma producing apparatus.The structure of plasma doping apparatus is in this case seen Figure 13.
Among Figure 13, in vacuum tank 1, from feeder 2 import the gas stipulated on one side, carry out exhaust by turbomolecular air pump 3 on one side as exhaust apparatus.By pressure regulating valve 4 pressure in the vacuum tank 1 is remained on the pressure of regulation, simultaneously by high frequency electric source 5 to be arranged on specimen electrode 6 opposed medium windows 7 near supply with the high frequency power of 13.56MHz as the coil 8 of plasma producing apparatus.Can in vacuum tank 1, produce inductance coupling high type plasma thus, the silicon substrate 9 as sample (machined object) that is placed on the specimen electrode 6 is carried out the plasma doping processing.Be used for to control the current potential of specimen electrode 6, make substrate 9 relative plasmas have negative current potential to the high frequency electric source 10 of specimen electrode 6 supply high frequency power.Turbomolecular air pump 3 and exhaust outlet 11 be configured in specimen electrode 6 under.Pressure regulating valve 4 under the specimen electrode 6 and be positioned at turbomolecular air pump 3 directly over the buck valve.Specimen electrode 6 is fixed in the vacuum tank 1 by 4 supporting masses 12.The principal component of medium window 7 is quartz glasss.In addition, also possess sampler 37, its effect is to be Pf, when reflected wave power is Pr, to gather the value of difference power Pf-Pr with the interval of 1msec～100msec at the traveling wave power of supply as the high frequency power of the coil of plasma producing apparatus.Control device 44 reaches the time point of predefined value at difference power Pf-Pr by the time principal value of integral, stops supply high frequency power.Utilization doping content under gas of the same race, same flow, same pressure is this point of ratio respectively with the high frequency power and the processing time that put on plasma producing apparatus, reach the time point of predefined value at difference power Pf-Pr by the time principal value of integral, stop supply high frequency power.Even the generation situation at reflected wave occurs also accessing doping more accurately under the discrete situation like this.
At embodiments of the invention 7, only exemplified the part in the various devices that aspects such as the mode of shape, plasma source of the vacuum tank in the range of application of plasma doping of the present invention and configuration change to some extent.When using plasma doping of the present invention, the various variations beyond can certainly considering here to be exemplified.
As shown in Figure 2, can make coil 8 plane.Can use Helicon wave plasma in addition, perhaps can adopt magnetic neutral loop plasma.
Also have, can in vacuum tank 1, not import doped raw material gas, the doped raw material that produces by solid, shaped impurity with doping impurity in the film of sample or specimen surface.
Present embodiment is keeping producing under the state of plasma in the process that plasma doping is handled, and is effective especially when changing at least 1 Control Parameter in the kind, gas flow, pressure, these Control Parameter of high frequency power of gas.This is because the time point that changes in Control Parameter easily produces reflected wave.
Here exemplified the situation of sample, when handling the sample of other various materials, also can use present embodiment for the semiconductor substrate that constitutes by silicon.
In the present embodiment, having exemplified impurity is the situation of boron, and under the situation of sample for the semiconductor substrate that is made of silicon, present embodiment is effective especially when impurity is arsenic, phosphorus, boron, aluminium or antimony.This is because can form more shallow joint in transistor part.
Present embodiment is that the situation of low concentration is effective to doping content.In the desired value as concentration is 1 * 10
11Atm/cm
2～1 * 10
17Atm/cm
2Plasma doping the time very effective.In the desired value as concentration is 1 * 10
11Atm/cm
2～1 * 10
14Atm/cm
2Plasma doping the time effective especially.This is owing to counting sec because of the processing time from number sec～ten, and is shorter, so the discrete influence increase of reflected wave.
The traveling wave power of supplying with the high frequency power of plasma producing apparatus or specimen electrode is Pf, and when reflected wave power was Pr, the interval of gathering the value of difference power Pf-Pr was preferably 1msec～100msec.Its reason is, make the sampling interval less than 1msec, and the sampler of very high performance must be arranged, and requires control device to have very strong operational capability, therefore can cause the raising of installation cost.If the sampling interval greater than 100msec, then can not obtain sufficient reappearance.
The traveling wave power of supplying with the high frequency power of plasma producing apparatus or specimen electrode is Pf, when reflected wave power is Pr, gather difference power Pf-Pr value to be spaced apart 1msec～10msec effect better.Its reason is if below 1msec, must there be the sampler of very high performance in the sampling interval as mentioned above, so just to cause the raising of cost.If below 10msec, then can obtain good reappearance.
When gathering the value of difference power Pf-Pr, the value that can gather Pf and Pr is respectively calculated its difference, perhaps can carry out the computing on circuit.In addition, can suppose that traveling wave power P f equals set point, only gather reflected wave power P r, the value of rated output difference Pf-Pr.
Also have, the value of difference power Pf-Pr can be inserted between sampled value and sampled value with straight line by time during integration, also can be by the mode calculating integral value of stepped variation.
Claims (1)
1, plasma doping, it is the plasma doping that adds impurity in the film of sample or specimen surface, it is characterized in that, comprises following 3 stages, the 1st stage was that the specimen electrode in vacuum tank is placed sample; The 2nd stage was to discharge gas on one side in vacuum tank by on one side the inert gas beyond the helium being inputed in the above-mentioned vacuum tank, made to plasma source supply high frequency power when the pressure in the above-mentioned vacuum tank is controlled at the 1st pressure to produce plasma in the above-mentioned vacuum tank; The 3rd stage was to keep producing under the state of plasma, the gas that will contain helium and doped raw material gas on one side inputs in the above-mentioned vacuum tank discharges gas on one side in vacuum tank, pressure in the above-mentioned vacuum tank is controlled at 2nd pressure lower than the 1st pressure, and in the 3rd stage to the plasma source supply high frequency power bigger than the high frequency power in the 2nd stage.
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| KR100835355B1 (en) * | 2006-07-25 | 2008-06-04 | 삼성전자주식회사 | PLASMA Based ION IMPLANTATION APPARATUS |
| US8383496B2 (en) | 2008-08-15 | 2013-02-26 | Kazuhiko Tonari | Plasma doping method and manufacturing method of semiconductor device |
| WO2011007580A1 (en) | 2009-07-17 | 2011-01-20 | 株式会社アルバック | Substrate processing method |
| JP2013165254A (en) * | 2012-01-13 | 2013-08-22 | Tokyo Electron Ltd | Plasma doping apparatus, plasma doping method, method for manufacturing semiconductor element, and semiconductor element |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1154569A (en) * | 1995-10-23 | 1997-07-16 | 松下电器产业株式会社 | Method and device for introducing foreign substance, and method for mfg. semiconductor device |
| CN1260842A (en) * | 1997-05-22 | 2000-07-19 | 东京电子有限公司 | Method and apparatus for low pressure sputtering |
| JP3090458B2 (en) * | 1990-01-24 | 2000-09-18 | 株式会社日立製作所 | Plasma processing equipment |
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| US6287435B1 (en) * | 1998-05-06 | 2001-09-11 | Tokyo Electron Limited | Method and apparatus for ionized physical vapor deposition |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3090458B2 (en) * | 1990-01-24 | 2000-09-18 | 株式会社日立製作所 | Plasma processing equipment |
| CN1154569A (en) * | 1995-10-23 | 1997-07-16 | 松下电器产业株式会社 | Method and device for introducing foreign substance, and method for mfg. semiconductor device |
| CN1260842A (en) * | 1997-05-22 | 2000-07-19 | 东京电子有限公司 | Method and apparatus for low pressure sputtering |
Also Published As
| Publication number | Publication date |
|---|---|
| CN100479101C (en) | 2009-04-15 |
| CN101276748B (en) | 2010-12-29 |
| JP2004128210A (en) | 2004-04-22 |
| CN100514563C (en) | 2009-07-15 |
| CN101090068A (en) | 2007-12-19 |
| CN100543937C (en) | 2009-09-23 |
| CN101090069A (en) | 2007-12-19 |
| CN101276748A (en) | 2008-10-01 |
| CN101086964A (en) | 2007-12-12 |
| CN101090070A (en) | 2007-12-19 |
| JP4443819B2 (en) | 2010-03-31 |
| CN101093801A (en) | 2007-12-26 |
| CN101090071A (en) | 2007-12-19 |
| CN100561670C (en) | 2009-11-18 |
| CN100511591C (en) | 2009-07-08 |
| CN100511593C (en) | 2009-07-08 |
| CN101286448A (en) | 2008-10-15 |
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