CN100545999C - Charged particle beam application system - Google Patents

Abstract

A kind of charged particle beam application system is provided.Dynamically detect the current potential of wafer when describing,, seek to improve the positional precision of the circuitous pattern of on wafer, describing by revising this current potential.Measured wafer (101, sample) and ground lead (107, contact terminal) behind the contact resistance of Xing Chenging, mensuration is from wafer (101, sample) via ground lead (107, contact terminal) flows to the electric current of earthing potential, potential difference is given between wafer (101, sample) and the earthing potential according to measurement result.

Description

Charged particle beam application system

Technical field

Semiconductor-fabricating device that the present invention relates to use in the semiconductor technology and semiconductor checking device particularly relate at a high speed and high-precision charged particle beam application system.

Background technology

As one of master operation that on Semiconductor substrate, forms the LSI figure, can enumerate by electron beam being radiated on the wafer that has applied photosensitive material, form the electron beam drawing of circuitous pattern.In this electron beam lithography system, in order to carry out the maintenance and the rectification of wafer in a vacuum, and use electrostatic adsorption device.

The profile of the typical electrode for electrostatic attraction of using in the existing electron beam lithography system has been shown among Fig. 1.The 101st, as the semiconductor wafer (to call wafer in the following text) of sample, the 102nd, be the dielectric of main material with the aluminium oxide, the 103rd, be embedded in the adsorption electrode in the dielectric 102.Adsorption electrode 103 is connected with (+) side of DC power supply 105 by switch 104.Wafer 101 utilizes and compresses its surface come-up of apparatus 106 inhibition.On the other hand, have sharp keen needle-like contact terminal (to call ground lead in the following text) 107 and withstand on the back side, wafer is connected on the earthing potential by it.Substrate 108 also is connected on the earthing potential.

That is, as pair of electrodes, the direct voltage that Electrostatic Absorption is used is added on the dielectric 102 between this pair of electrodes, by the electric charge that takes place in the dielectric to be produced by dielectric polarization, guarantees Electrostatic Absorption power with wafer 101, adsorption electrode 103.This electrostatic adsorption device does not depart from the function of position of regulation except keeping sample, also has to correct function for smooth adsorption plane with being through technology such as film forming along the warpage of the wafer of the punch of tens of mm or recessed shape of touching.

In addition, though in Fig. 1 the back side of ground lead contact wafer, under the situation of surface contact, also have same function.Though adsorption electrode is connected power supply (+) side in addition, even minus side, adsorption function too.

Here, wafer 101 utilizes ground lead 107 to be connected on the earthing potential., strictly speaking, flow through the contact resistance that on the contact site of wafer 101 and ground lead 107, forms owing to flow into the electric current of wafer, so between wafer 101 and earthing potential, produce potential difference.What is called flows through the electric current of wafer, is the electron beam current that flows through the leakage current of wafer 101 and describe usefulness via dielectric 102 from adsorption electrode 103.For example, the electric current of supposing to flow through wafer 101 is 50mA, and the contact resistances in the middle of ground lead 107 and the wafer 101 are 200kW, and then wafer 101 has the 1V current potential.

Do not keep under the situation of earthing potential at wafer 101 like this,, describe precise decreasing as the track confusion of the electronics of charged particle.At M.Miyazaki, J.Phys.E:Sci.Instrum.14, in 194 (1981), the amount of deflection that discloses the electronics of irradiation changes along with the variation of wafer potential, so the offset of generating writing pattern takes place.In addition, do not keep at wafer 101 under the situation of earthing potential, and keep producing potential difference between the base stage plate 108 of earthing potential, so near the wafer end, the electric field that the track of the electron beam of irradiate wafer is distorted.Thus, we can say in electron beam lithography system and in electrostatic adsorption device, to be necessary to make wafer 101 to remain on earthing potential in order to obtain the higher precision of describing.

Among Fig. 4 in Japanese Patent Application Laid-Open 2001-257158 communique, disclose a kind of adsorption electrode and be divided into two electrostatic adsorption device, DC power supply is connected on each, and galvanometer is connected in series in the electrostatic adsorption device of the structure between this DC power supply and the earthing potential.There is one to be variable DC power supply in the DC power supply.Voltage is added on the adsorption electrode of having cut apart, regulates the voltage that applies of variable DC power supply, two galvanometric indicated values are equated, two electrodes constitute closed circuits.Its purpose is to reduce the leakage current that takes place between two adsorption electrodes and the sample flows to earthing potential via ground lead the magnitude of current.

On the other hand, in the spy opens Fig. 1 and Fig. 3 in the flat 11-111599 communique, disclose and a kind ofly decide the current potential of wafer surface with the surface potential instrumentation, decision is added in ground lead or absorbs the invention of the value of the correction usefulness voltage on the electrode.In the method, owing to directly measure the current potential of wafer, so on principle, can detect not only by the leakage current of dielectric inside but also by the current potential of the wafer of electron beam current generation.

In addition, open among Fig. 2 of flat 11-111599, disclose and measured the current value that flows through adsorption electrode, be added in the invention of the value of the correction voltage on the ground lead according to this measured value decision the spy.In addition, open among Fig. 4 of flat 11-111599 the spy, disclose two ground leads are configured on the wafer, measure the potential difference between a ground lead and the earthing potential, according to measurement result, decision is added in the technology of the value of the correction voltage on another ground lead.If adopt the spy to open the invention of putting down in writing in the flat 11-111599 communique, then on principle, can reduce wafer potential.

[patent documentation 1] spy opens the 2001-257158 communique

[patent documentation 2] spy opens flat 11-111599 communique

[non-patent literature 1] J.Phys.E:Sci.Instrum.14,194 (1981)

Open 2001-257158 communique and special opening in the invention of putting down in writing among Fig. 2 of flat 11-111599 communique the spy, between DC power supply and adsorption electrode and even DC power supply and earthing potential, be provided with galvanometer.That is, measure from wafer and flow to current value the adsorption electrode via dielectric.On the other hand, the resistance between wafer and the adsorption electrode can keep high resistance by dielectric, and different therewith, the contact resistance between wafer and the ground lead is much smaller, and the intrafascicular major part of charged particle that is radiated on the wafer flows in the ground lead.In above-mentioned invention, do not flow to electric current the ground lead owing to do not measure, so, can not obtain to be worth accurately even calculate according to the current value of measuring and to revise voltage from this wafer.

On the other hand, open shown in Fig. 1,3 in the flat 11-111599 communique,, then can directly measure the surface potential of wafer if measure with the surface potential meter as the spy., the variation in the describing of high-precision surface potential meter and electron beam current is compared, and low-response is so be difficult to calculate at high speed correction voltage.That is, in describing, dynamically revise the high speed correction of wafer potential, can not realize by the abutment surface potentiometer.

Open shown in Figure 4 in the flat 11-111599 communique as the spy, even one in two ground leads that will contact with wafer is used for potential measurement, the power supply of revising usefulness is connected on another, though on principle, can revise the surface potential of wafer, but it is prerequisite that this method is all hanged down with the resistance of two ground leads, and on the other hand, the contact resistance machine error between ground lead and the wafer is very big, reproducibility can not guarantee, so also be difficult to often revise exactly with this method the current potential of wafer.

In recent years, owing to follow the large tracts of landization of wafer, leakage current also increases, in order to improve production capacity, and reasons such as electron beam current increase, the charged possibility of wafer has increased.On the other hand, in order to improve precision, further require to reduce wafer potential.

The objective of the invention is to realize a kind of electrostatic adsorption device that can reduce the current potential of wafer compared with the past, the charged particle beam application system of this electrostatic adsorption device has been installed.

Summary of the invention

In order to solve above-mentioned problem, electrostatic adsorption device of the present invention is characterised in that, has: the absorption electrode; Direct voltage is added in this absorption with the power supply on the electrode; The contact terminal of contact sample; Between this contact terminal and earthing potential, measure the unit that flows through the electric current of earthing potential from sample via contact terminal; And will revise with voltage and be added in wafer potential correction power supply on above-mentioned adsorption electrode and even the contact terminal.The shape of adsorption electrode has mensuration and gets final product via the unit that contact terminal flows into the electric current of earthing potential no matter be one pole type or ambipolar.Thus, compared with the past can mensuration more accurately by electron beam current and leakage current both sides causes and the current value from wafer that takes place.Therefore, compared with the past can calculating more accurately revised the value of using voltage.

The wafer potential correction is connected on the ground lead under the situation of one pole type with power supply.Under ambipolar situation, can be connected on adsorption electrode any one among both of a ground lead or an ambipolar side.

In the electrostatic adsorption device of charged particle application apparatus, in sample is handled,, also can improve the irradiation position precision of charged particle line by revising the current potential of sample.

Description of drawings

Fig. 1 is the ideograph of existing electrostatic adsorption device.

Fig. 2 is the overall construction drawing of electron beam lithography system.

Fig. 3 is the ideograph of the electrostatic adsorption device of explanation embodiments of the invention 1 usefulness.

Fig. 4 (a) is that expression has near the potential image the wafer end of 1V current potential, (b) is the figure of the current potential of the expression wafer electron-beam position skew of wafer end when being 1V.

Fig. 5 (a) is the ideograph of the electrostatic adsorption device of explanation embodiments of the invention 2 usefulness, (b) is the sequential chart of explanation embodiments of the invention 2 usefulness.

Fig. 6 is the ideograph of the electrostatic adsorption device of explanation embodiments of the invention 3 usefulness.

Fig. 7 is the ideograph of the electrostatic adsorption device of explanation embodiments of the invention 4 usefulness.

Fig. 8 (a) is the ideograph of the electrostatic adsorption device of explanation embodiments of the invention 5 usefulness, (b) is equivalent circuit diagram, (c) is the ideograph of the electrostatic adsorption device of explanation embodiments of the invention 5 usefulness.

Fig. 9 (a) is the ideograph of the electrostatic adsorption device of explanation embodiments of the invention 6 usefulness, (b) is the ideograph of the electrostatic adsorption device of explanation embodiments of the invention 6 usefulness.

Figure 10 (a) is the flow chart of explanation embodiments of the invention 6 usefulness, (b) is the flow chart of explanation embodiments of the invention 6 usefulness.

(Reference numeral)

101: wafer 102: dielectric 103: adsorption electrode 104: switch

105: DC power supply 106: compress apparatus 107: ground lead

108: the base stage plate

201: thermionic electron guns 202: 203: the first masks of anode electrode

204: molded lens 205: be shaped with 206: the second masks of deflector

207: reducing glass 208: object lens 209: deflector 210: wafer

211: plate 212: objective table 213: control circuit

301: adsorption electrode 302: adsorption electrode 303: the absorption power supply

304: absorption power supply 305: galvanometer 306: feedback circuit

503: absorption power supply 504: absorption power supply 505: galvanometer

506: wafer potential correction power supply 507: feedback circuit

601: ground lead 602: ground lead 603: galvanometer

604: galvanometer 605: wafer potential correction power supply

606: wafer potential correction power supply 607: feedback circuit

608: feedback circuit 609: switch

701: ground lead 702: ground lead 703: ground lead

704: switch 705: galvanometer 706: wafer potential correction power supply

707: feedback circuit

801: surface potential meter 802: feedback circuit

803: wafer potential correction power supply 804: variable resistor

805: variable capacitance 806: resistance

901: electron beam 902: reflection electronic 903: the reflection electronic detector

904: computer 905: wafer potential correction power supply

906: reference mark

Embodiment

Below embodiments of the present invention will be described with reference to the accompanying drawings.

[embodiment 1]

The ideograph of the general structure of electron beam wafer drawing apparatus has been shown among Fig. 2.After 202 acceleration of thermionic source 201 electrons emitted Shu Chaoxiang anode electrodes, direct irradiation first mask 203.On first mask, be provided with single rectangular aperture, utilize the electron beam that is shone to obtain the opening picture.On second mask 206, form the opening picture of first mask by molded lens 204.On second mask, be provided with and carry out the rectangular aperture that variable shaping irradiation uses and carry out the shaping opening that figure irradiation is in the lump used.Be shaped with the image space on deflector 205 controls second mask by electron beam, determine the shape and the area of electron beam thus.The electron beam of opening that has passed through second mask is projected on the wafer 210 as sample by reducing glass 207 and object lens 208.In object lens, be provided with deflector 209, by the image space of the electron beam on this deflector decision sample.

The wafer 210 as rendered object of present embodiment, middle across plate 211, be set on the objective table 212.Plate 211 double as electrostatic adsorption device usefulness utilize electrostatic force that wafer 210 is fixed on the plate 211.Owing to again plate 211 is fixed on the objective table 212, thus in describing process wafer 210 can with objective table 212 high accuracy and moving at high speed together.According to the circuitous pattern that should describe, be shaped with whole electronic components, detector (not shown) and the objective table 212 of deflector 205 based on molded lens 204 and electron beam by control circuit 213 controls.Though not shown among the figure, in control circuit 213, have input units such as display units such as monitoring image and keyboard, device users can pass through input unit, and the necessary various information of the control of drawing apparatus are inputed to device.

Secondly, the electrostatic adsorption device of present embodiment is described with ideograph shown in Figure 3.The electrostatic adsorption device of present embodiment is that adsorption electrode is divided into two so-called ambipolar.Dielectric 102 is configured in the framework inside of electrostatic adsorption device, and the surface of dielectric 102 becomes the placed side of wafer.Be provided with through hole on the outer edge of framework, configuration makes the earthy ground lead of wafer 107.DC power supply 303 and 304 by switch 104 conductivity be connected on the adsorption electrode 301 and 302 that is embedded in the dielectric 102, and given potential difference V1 and V2 respectively between the earthing potential.DC power supply 304 is type variable DC power supply.In addition, in Fig. 3, though DC power supply 303 represent as the type variable DC power supply, also can be fixed DC power supply.

If do not consider electron beam current, only consider leakage current, the electric current sum that flows through wafer 101 from two adsorption electrodes 301 and 302 via ground lead 107, flows to earthing potential from wafer 101 so.At this moment, between wafer 101 and ground lead 107, form contact resistance, so wafer 101 has potential difference with respect to earthing potential.

Fig. 4 (a) is near expression wafer 101 distribution map of the electric field the wafer end when having potential difference with respect to earthing potential.Since the effect of the potential difference of wafer and plate, equipotential line distortion that originally should be parallel with respect to wafer face, and thus, electric field intensity has the component vertical with respect to the direct of travel of electron beam.Therefore the curved in tracks of electron beam has departed from desirable track.In other words, occurrence positions skew in the generating writing pattern of wafer end.Illustrated when the 1V current potential has taken place on the wafer among Fig. 4 (b), calculated the electron beam that arrives on the wafer and departed from what analog result.Transverse axis represents that from as the center of the wafer of the irradiation position of the electron beam distance along radial direction, the longitudinal axis is represented the position offset of electron beam.The amount that the longitudinal axis among Fig. 4 (b) will be offset to the outside of wafer will be represented as bearing to the amount of the inboard of wafer skew as just.Wafer diameter is envisioned for diameter 200mm.Conclude that by Fig. 4 (b) the closer to the wafer end, side-play amount is big more.

Therefore, so far, open shown in Fig. 4 or special Fig. 1,3 that opens flat 11-111599 communique in the 2001-257158 communique, DC power supply is connected on the both sides of bipolar electrode as the spy, between two electrodes, make closed circuit, seek to reduce from adsorption electrode flowing to current value the wafer 101., in existing method, be difficult to measure exactly wafer potential, therefore, can not supply with to revise accurately and use voltage, often can not reduce leakage current fully.

In the present embodiment, between ground lead 107 and earthing potential, be provided with current measuring units such as galvanometer 305.Feedback circuit 306 is subjected to the control of the overall control circuit of drawing apparatus 213, adjusts the output of DC power supply 304, so that the absolute value of the electric current of measuring with galvanometer 305 is a minimum.Owing to directly measure from wafer 101 and flow to the electric current of earthing potential, can between both sides' adsorption electrode, can form and compare in the past closed circuit more completely than measured wafer potential more accurately in the past via ground lead 107.In addition, in the spy opens method shown in Figure 4 in the 2001-257158 communique, need gain and two consistent galvanometer of skew, different therewith, in the present embodiment, needed galvanometer is one, even how much weaker the precision of the gain of galvanometer 305 is in addition, as long as adjust skew, also can survey the electric current sum that flows to the wafer 101 from two adsorption electrodes 301 and be minimum condition.Therefore, can use all lower galvanometer of price, precision.

According to present embodiment, by carrying out the correction of wafer potential, can make the electric current sum that flows to the wafer from adsorption electrode be minimum before describing.Thus, in the chip of wafer end, also can guarantee good positional precision, obtain quantity so can improve the chip of a Waffer edge.

Adopt present embodiment, can be than reducing the summation that flows to the electric current the wafer from adsorption electrode in the past, so can make the current potential correction of the crystal that carries out before describing more effective.In addition, the electron beam lithography system of the electrostatic adsorption device of present embodiment has been installed,, also can have been guaranteed good positional precision, obtained quantity so can improve the chip of a Waffer edge even in the chip of wafer end by use.

[embodiment 2]

In embodiment 1, DC power supply is connected on the both sides of bipolar electrode, between two electrodes, make closed circuit, seek to reduce from adsorption electrode flowing to current value the wafer.In fact, except leakage current, also has the electron beam current of irradiation in the wafer from adsorption electrode.The major part of this electron beam flows into earthing potential via ground lead.This be because, the resistance between wafer and the adsorption electrode utilizes dielectric can keep high resistance, different therewith, the contact resistance between wafer and the ground lead is much smaller.

Therefore, adopt the method for embodiment 1 before describing, even reduce the summation that flows to the leakage current the wafer from adsorption electrode, but the irradiation of electron beam current Once you begin just produces potential difference between wafer and earthing potential.Therefore, in the present embodiment,, the DC power supply on being connected adsorption electrode, also use to revise and use power supply in order to revise the wafer potential that in describing process, produces by electron beam current.In addition, in the following description, suppose that the electrostatic adsorption device of present embodiment is installed in the electron beam lithography system shown in Figure 2.

Electrostatic adsorption device with the explanation of the ideograph shown in Fig. 5 (a) present embodiment.The electrostatic adsorption device of present embodiment is that adsorption electrode is divided into two so-called ambipolar. DC power supply 503 and 504 is connected on the adsorption electrode 301 and 302 that is embedded in the dielectric 102 by switch 104, and is given potential difference V1 and V2 respectively between the earthing potential.

, be connected on the earthing potential by galvanometer 505 and wafer potential correction power supply 506 by the ground lead on the back side that is pressed in wafer 101 107.Here wafer potential correction is given DC potential difference V3 between earthing potential and the ground lead 107 with power supply 506, and galvanometer 505 is measured the electric current that flows into earthing potential from wafer 101 via ground lead 107.

In case export the indication that begins to describe from the control program of device users or drawing apparatus, the installation of present embodiment the charged particle beam application system of electrostatic adsorption device just according to following program, carry out the mensuration of the contact resistance between ground lead 107 and the wafer 101.

(1) make the wafer potential correction be output as 0V with power supply after, the overall control circuit 213 of drawing apparatus utilizes galvanometer 505, measure on one side from wafer 101 and flow into the electric current I 3 of earthing potentials via ground lead 107, adjust and be added in voltage V1 adsorption electrode 301 on and be added in voltage V2 adsorption electrode 302 on both among at least one make I3 be 0 on one side.Thus, make flow to the electric current the wafer from adsorption electrode summation for minimum.

(2) secondly with power supply 506 DC potential difference V3 is given between earthing potential and the ground lead 107 by the wafer potential correction.At this moment, galvanometer 505 is measured from wafer 101 and is flowed into the electric current I 3 of earthing potentials via ground lead 107, can utilize following formula to try to achieve contact resistance R3 between ground lead 107 and the wafer 101.

R3＝V3/I3

After having obtained contact resistance R3 between ground lead 107 and the wafer 101 according to above program, begin to describe.The value of the R3 that is tried to achieve is stored in the memory cell such as memory in the control device 213 or external memory.

Fig. 5 (b) is electron beam current after expression is described to begin and the sequential chart of revising the relation of using power source voltage V3 and wafer potential.

After describing beginning, the amount of deflection of electron beam and shape change according to the figure that should describe.The electron beam current that accompanies with it changes.So far, be directly connected on the earthing potential,, following the variation of electron beam current at leisure and change so the current potential of wafer is shown in dotted line in Fig. 5 (b) from the electric current of wafer via ground lead.This is because by at electrostatic capacitance that forms between wafer and the adsorption electrode and the contact resistance that produces, form the RC circuit between wafer and ground lead.Thus, the situation that needs the wafer potential higher limit of describing of precision for realization appears surpassing.

On the other hand, in the present embodiment, monitor from the electric current I 3 of wafer 101, with the current potential of wafer potential correction with power supply 506 correction wafers 101 via ground lead 107 inflow earthing potentials with galvanometer 505.That is, feedback circuit 507 is subjected to the control of the overall control circuit of drawing apparatus 213, and following setting is added in the voltage V3 on the wafer potential correction usefulness power supply 506.

V3＝-I3×R3

Here, R3 is the ground lead 107 measured in advance before describing and the contact resistance between the wafer 101.

In fact shown in Fig. 5 (b), the voltage V3 that is added on the wafer potential correction usefulness power supply 506 is changed every a certain certain time interval.Wafer potential is revised at the interval of setting and galvanometric response time same degree.Thus, shown in Fig. 5 (b), on one side can guarantee that the variation of wafer potential is littler than in the past, Yi Bian proceed to describe.

In addition, desire reduces under the situation of the frequency of revising, and can pre-determine the permissible value of wafer potential according to the current potential of the wafer shown in Fig. 2 (b) and the relation of offset, only revises when I3 * R3 has surpassed permissible value.In the case, the higher limit of wafer potential is stored in the memory cell in the control device 213.Perhaps the temporal information of the frequency that also expression can be revised is stored in the control device 213, revises according to the frequency based on canned data.

Utilize present embodiment, in describing process, carry out the correction of wafer potential, can reduce the wafer potential that produces by the electron beam current that flows in the wafer.In addition, in the electrostatic adsorption device of present embodiment, compare with the situation that only reduces the leakage current from adsorption electrode inflow wafer that embodiment 1 carries out, can describe with big electron beam current, so can shorten describing the time of a limit of wafer, improve production capacity.

In addition, in the present embodiment, only one of the bar number of necessary ground lead.Consider and follow contacting of wafer and ground lead may produce foreign matter, this is an advantage.Even under the situation of using the ground lead more than two, use the same method obtained contact resistance between each bar ground lead and the wafer after, if similarly use with a ground lead after having obtained combined resistance, then can obtain the effect same with present embodiment.In addition, the electrostatic adsorption device of present embodiment can not only be installed in the drawing apparatus shown in Figure 2, and can be installed in other charged particle beam application systems such as surveying long SEM.

[embodiment 3]

Electrostatic adsorption device with the explanation of the ideograph among Fig. 6 present embodiment.In addition, the electrostatic adsorption device of present embodiment is also identical with embodiment 1, supposes to be installed in the electron beam lithography system shown in Figure 2.

Present embodiment has been to use the embodiment of many ground leads.DC power supply 105 is connected on the adsorption electrode 103 that is embedded in the dielectric 102 by switch 104, and is endowed potential difference V1 between the earthing potential.Two ground leads 601 and 602 are pressed against on the back side of wafer 101 in the present embodiment.The wafer potential correction is connected on each bar ground lead by galvanometer 603,604 respectively with power supply 605,606.The wafer potential correction is given DC potential difference V3, V4 respectively between earthing potential and the ground lead with power supply 605 and 606, and galvanometer 603 and 604 is measured the electric current that flows into earthing potential from wafer 101 via ground lead 601 or 602.

Feedback circuit 607 is subjected to the control of the overall control circuit of drawing apparatus 213, adjusts the wafer potential correction with power supply 605, so that the current value of being measured by galvanometer 603 is predefined value.Same feedback circuit 608 is subjected to the control of the overall control circuit of drawing apparatus 213, adjusts the wafer potential correction with power supply 606, so that the current value of being measured by galvanometer 604 is predefined value.In addition, though not shown, in fact switch 104 and 609 on-off action are also by control circuit 213 controls.

In case export the indication that begins to describe from the control program of device users or drawing apparatus, the charged particle beam application system of electrostatic adsorption device that present embodiment has been installed is just according to following program, carry out ground lead 601 and 602 and wafer 101 between the mensuration of contact resistance.

The overall control circuit 213 of drawing apparatus will become 0 voltage from the electric current I 4 that wafer 101 flows into earthing potentials via ground lead 602 and give the wafer potential correction and export to feedback circuit 608 with the indication of power supply 606.Feedback circuit 608 calculates and is added in the wafer potential correction with the voltage on the power supply 605 according to the current value I of being measured by galvanometer 604 4, adjusts the voltage V4 of wafer potential correction with power supply 606.

At this moment, wafer potential is V4, the electric current that flows into wafer in addition all flows into earthing potential via ground lead 601, so according to the voltage V3 that uses power supply 605 by the electric current I 3 and the current potential correction of galvanometer 603 measurements, can the following contact resistance R3 that tries to achieve between ground lead 601 and the wafer 101.The contact resistance R3 that is tried to achieve is stored in the interior storage device of drawing apparatus.

R3＝(V4-V3)/I3

After having tried to achieve contact resistance R3 between ground lead 601 and the wafer 101 according to above program, begin to describe.In addition, when describing, the ground lead used of current potential of decision wafer 101 have one just enough, so switch 609 is opened.Also can make ground lead 602 leave wafer 101.In the case, need to drive the driver element of ground lead 602 usefulness.

The current potential that carries out wafer 101 with method similarly to Example 2 monitors and correction.That is, monitor from the electric current I 3 of wafer 101, with the current potential of wafer potential correction with power supply 605 correction wafers 101 via ground lead 601 inflow earthing potentials with galvanometer 603.That is, feedback circuit 607 is subjected to the control of the overall control circuit of drawing apparatus 213, the following setting wafer potential correction output voltage V 3 of power supply 605.

V3＝-I3×R3

Adopt present embodiment,, carry out the correction of wafer potential, can obtain effect similarly to Example 2 by describing.

Present embodiment is different with embodiment 2, and adsorption electrode is that the situation or the bipolar situation of one pole can both be implemented.

In addition, though only used in two ground leads when describing in the present embodiment, but reduce as much as possible under the situation of the contact resistance between wafer and the ground lead desiring, also can make the common contact of two ground leads after on the wafer, to connect galvanometer 603 in parallel.In addition, the electrostatic adsorption device of present embodiment can not only be installed in the drawing apparatus shown in Figure 2, and can be installed in other charged particle beam application systems such as surveying long SEM.

[embodiment 4]

Electrostatic adsorption device with the explanation of the ideograph among Fig. 7 present embodiment.The electrostatic adsorption device of present embodiment is also identical with embodiment 1, supposes to be installed in the electron beam lithography system shown in Figure 2.

DC power supply 105 is connected on the adsorption electrode 103 that is embedded in the dielectric 102 by switch 104, and is endowed potential difference V1 between the earthing potential.Three ground leads 701,702 and 703 are pressed against on the surface of wafer 101 in the present embodiment.

In case export the indication that begins to describe from the control program of device users or drawing apparatus, the charged particle beam application system of electrostatic adsorption device that present embodiment has been installed is just according to following program, carry out ground lead 701,702 and 703 and wafer 101 between the mensuration of contact resistance.

At first, be connected the terminal 708 on the ground lead 701 with multitester measuring and be connected resistance R 12 between the terminal 709 on the ground lead 702.Equally, be connected the terminal 709 on the ground lead 702 with multitester measuring and be connected the resistance R 23 between the terminal 710 on the ground lead 703 and be connected the terminal 710 on the ground lead 703 and be connected resistance R 31 between the terminal 708 on the ground lead 701.

At this moment, suppose that contact resistance between ground lead 701 and the wafer 101 is that contact resistance between R1, ground lead 702 and the wafer 101 is that contact resistance between R2, ground lead 703 and the wafer 101 is R3, following formula is set up.

R12＝R1+R2

R23＝R2+R3

R31＝R3+R1

That is,, just can try to achieve R1, R2, R3 from following formula if try to achieve R12, R23, R31 by mensuration.

In general, if the ground lead of contact wafer is more than 3, then, just can try to achieve the contact resistance between each bar ground lead and the wafer independently as long as liken to each the bar ground lead and the contact resistance number between the wafer of unknown number are many by the number of measuring the parameter that obtains.

After having tried to achieve contact resistance R1, R2 between ground lead 701,702,703 and the wafer 101, R3 independently according to above program, begin to describe.When describing, the ground lead used of current potential of decision wafer 101 have one just enough, so switch 704 is subjected to the control of the overall control circuit of drawing apparatus 213, from terminal 708 to 710, select one.Reduce as much as possible under the situation of the contact resistance between wafer and the ground lead desiring, also can select more than two, to calculate from the wafer to the switch 704 combined resistance and get final product.

The current potential of the wafer 101 in describing with method similarly to Example 2 monitors and revises.That is, monitor from the electric current I 3 of wafer 101, revise the current potential of wafers 101 with the wafer potential correction with power supply 706 via selecteed ground lead inflow earthing potential with galvanometer 705.That is, feedback circuit 707 is subjected to the control of the overall control circuit of drawing apparatus 213, and following setting is added in the voltage V3 on the wafer potential correction usefulness power supply 706.

V3＝-I3×R3

Adopt present embodiment,, carry out the correction of wafer potential, can obtain effect similarly to Example 2 by describing.

Present embodiment is also identical with embodiment 3, and adsorption electrode is that the situation or the bipolar situation of one pole can both be implemented.

In addition, in the present embodiment because the direct contact resistance between mensuration ground lead and the wafer,, often can obtain higher precision so compare with embodiment 2 and 3 such indirect mensuration.

In addition, in embodiment 2 to 4, though monitor the exposure of electron beam with galvanometer, carried out the correction of wafer potential, even but according to the graph data that should describe, calculate the exposure of electron beam one by one, according to these data, carry out the correction of wafer potential, also can obtain same effect.

In addition, the electrostatic adsorption device of present embodiment can not only be installed in the drawing apparatus shown in Figure 2, and can be installed in other charged particle beam application systems such as surveying long SEM.

[embodiment 5]

In embodiment 1 to 4, though flow through the current value of ground lead, calculated correction voltage by measurement, also can directly measure the surface potential of wafer with the surface potential meter, calculate and give the correction power source voltage., because surface potential meter low-response, so there is the problem that can not revise at a high speed.Therefore, in the present embodiment, the method that realizes practical electrostatic adsorption device with the surface potential meter is described.

Electrostatic adsorption device with the explanation of the ideograph among Fig. 8 (a) present embodiment.The electrostatic adsorption device of present embodiment is also identical with embodiment 1, supposes to be installed in the electron beam lithography system shown in Figure 2.DC power supply 105 is connected on the adsorption electrode 103 that is embedded in the dielectric 102 by switch 104, and is endowed potential difference V1 between the earthing potential.Ground lead 107 is pressed against on the back side of wafer 101 in the present embodiment.The wafer potential correction is connected on the ground lead 107 with power supply 803, and is endowed potential difference V3 between the earthing potential.Monitor the current potential of wafer 101 with surface potential meter 801.Feedback circuit 802 is adjusted the output of wafer potential correction with power supply 803, so that the measured value of surface potential meter 801 is in allowed band.The 804th, the variable resistor that the potential response speed of adjustment wafer is used.

Here, the Fig. 8 (b) that is used as the electrical equivalent circuit of Fig. 8 (a) illustrates the effect of variable resistor 804.C1 is the electrostatic capacitance of electrostatic adsorption device, and R1 is the bleeder resistance of electrostatic adsorption device, and Re is the contact resistance between ground lead 107 and the wafer 101.R3 means the resistance of variable resistor 804.In addition, Ib means electron beam current, and Vw means the current potential of wafer 101, and GND means earthing potential.

In such circuit, when the value of Ib, V1, V3 had changed, the response speed T of Vw represented with following formula.

T＝R0×C1

In the formula, R0 is the combined resistance of R1, Re, R3, can define with following formula.

1/R0＝1/R1+1/(Re+R3)

Here, R1 depends on the material and the shape of electrostatic adsorption device, is the order of magnitude of 10 8 power Ω, and C1 is the order of magnitude of 100nF.On the other hand, Re is the contact resistance of ground lead and wafer, is the parameter that is difficult to obtain reproducibility, is the order of magnitude of 10 4 power Ω.Therefore, under the situation that variable resistor 804 is not set, promptly during R3=0, response speed T is the order of magnitude of 1msec.On the other hand, the response speed of surface potential meter 801 depends on the mensuration precision, is the order of magnitude of 100msec.Promptly, in describing process, electron beam current changes repeatedly with MHz or bigger frequency, wafer potential is followed the tracks of it with the order of magnitude of 1msec, different therewith, the current potential correction cycle of wafer is 100msec at the soonest, means to be difficult in describing process guarantee that the current potential of wafer is desirable value.

On the other hand, R3 is selected suitable resistance value, can adjust the response speed T of Vw.That is, to the resistance about 6 power Ω of R3 selection 10, the response speed T of Vw is the order of magnitude of 100msec, equates with the response speed of surface potential meter 801.In other words, it is slow fully that the potential change of wafer becomes, even the mensuration that the surface potential meter carries out also can be followed the tracks of.

On the other hand, another parameter of the time constant that Adjustment System is overall is an electrostatic capacitance, so for example, shown in Fig. 8 (c), suitable variable capacitance 805 is connected in series on the Electrostatic Absorption power supply gets final product.In order to obtain the potential difference between adsorption electrode and the wafer, be necessary and be arranged in parallel with respect to variable capacitance 805 than the abundant little resistance 806 of the internal resistance R1 of adsorbent equipment.

In addition, in the present embodiment,, shown in embodiment 1 to 3, in the mensuration of the wafer potential of carrying out, also can adopt and use the same method with galvanometer though utilize the surface potential meter to carry out the mensuration of wafer potential.Because it is galvanometric response speed is the order of magnitude of 1 μ sec to 100msec, slower than the response speed of wafer potential sometimes.Under these circumstances, identical with present embodiment, by variable resistor 804 is selected suitable resistance value, the response speed that makes the response speed of wafer potential and analyzer about equally, the current potential that can guarantee wafer when describing is desirable value.

In addition, though in the correction of wafer potential, used the wafer potential correction,, can obtain same effect even, adjust with power source voltage with an absorption with for example ambipolar electrostatic adsorption device with power supply 803.In addition, though carried out the adjustment of the response speed of wafer potential in the present embodiment with variable resistor, because the response speed of analyzer is certain under the most situation, so, also can obtain same effect with the resistance that is fixed to desirable resistance value.

The manner is different with embodiment 1 to 4, directly measures wafer potential with the surface potential meter.Therefore, can and ground lead and wafer between contact resistance irrespectively implement the manner.The bar number of ground lead have one just much of that.In addition, the electrostatic adsorption device of present embodiment can not only be installed in the drawing apparatus shown in Figure 2, and can be installed in other charged particle beam application systems such as surveying long SEM.

[embodiment 6]

In embodiment 2 to 5, carried out the supervision of wafer potential with galvanometer or surface potential meter.

Different therewith, do not carry out the mensuration of electricity in the present embodiment, but, carry out the supervision of wafer potential on wafer by the correction sign that observation forms.

Electrostatic adsorption device with the explanation of the ideograph among Fig. 9 (a) present embodiment.In addition, in the following description, the charged particle beam application system as the electrostatic adsorption device that present embodiment is installed adopts electron beam lithography system shown in Figure 2.If utilize the deflector (not shown) on wafer 101, to scan from thermionic source emission post acceleration and the electron beam 901 assembled, then corresponding to the electron reflection rate of the correction that on wafer, forms with sign, generation reflection electronic 902.Reflection electronic detector 903 detects and amplifies this reflection electronic, is transferred to computer 904 as the reflection electronic signal.Computer 904 is according to the reflection electronic signal, and calculation correction is used the position of the reflection electronic picture of sign.

Shown in Fig. 4 (a), can not guarantee at wafer under the situation of earthing potential that because the effect of the potential difference of wafer and plate should be parallel to the equipotential line distortion of wafer surface originally, thus, electric field intensity has the component perpendicular to the electron beam traffic direction.Therefore the curved in tracks of electron beam has departed from desirable track.Under such state, if the correction that forms on wafer then can observe reflection electronic picture and original position deviation with the enterprising line scanning of sign.Shown in Fig. 4 (b), its side-play amount depends on the irradiation position of electron beam.

In the present embodiment, with the position of the correction that indicates (to call sign A in the following text), on the wafer end, forms, carry out the correction of wafer potential according to the correction that forms in center wafer portion with the reflection electronic picture of sign (to call sign B in the following text).The distance L 1 of sign A and sign B is necessary to measure accurately in advance.

The flow chart that drawing apparatus carries out work when among Figure 10 (a) the wafer potential correction being shown.The order of this work is as follows.

(1) voltage is added on the absorption power supply 105 of electrostatic adsorption device.

(2) set the voltage of wafer potential correction with power supply 905.

(3) moving stage 211, make electron beam irradiation sign A.

(4) obtain the reflection electronic picture of sign A, try to achieve at this moment relative position (X1) corresponding to the sign at electron beam center.This value is stored in the memory in the control circuit 213.

(5) moving stage 211, make electron beam irradiation sign B.The amount of movement of at this moment objective table as L2, is stored in this value in the memory in the control circuit 213.

(6) obtain the reflection electronic picture of sign B, try to achieve at this moment relative position (X2) corresponding to the sign B at electron beam center.This value is stored in the memory in the control circuit 213.

(7), calculate sign A of measuring with electron beam and the distance L 3 that indicates B according to L3=L2+ (X2-X1).

(8) poor (dL) of calculating L3 and L1.

(9) judge whether dL has surpassed permissible value.

(10) if smaller or equal to permissible value, just begin to describe.

(11) under situation, change the set point of wafer potential correction with power supply 905 greater than permissible value.

By with above method, adjust the voltage of wafer potential correction with power supply 905, revise wafer potential, so that can see the reflection electronic picture in original due position.In addition, the step of above-mentioned (1)～(11) is all carried out by control circuit 213.

Present embodiment is different with embodiment 1～5, the special measuring appliance that does not need mensuration wafer surface current potentials such as galvanometer or surface potential meter to use.Proofread and correct with sign or electron beam and be used in the electron beam lithography system so far.Therefore, need not carry out very big change, just can implement the manner the structure of existing electron beam lithography system.

In addition, in the present embodiment, though till seeing the reflection electronic picture in original due position, change the magnitude of voltage of wafer potential correction with power supply 905, but shown in Fig. 4 (b), if obtain the relation of position offset and wafer potential in advance, set suitable wafer potential correction power source voltage, can reduce the number of times that repeats.

In addition, do not use the correction that on wafer, forms, shown in Fig. 9 (b), near reference mark 906 settings wafer onboard, observe this sign, can obtain same effect yet with sign.In the case, obtaining at the reflection electronic of reference mark 906 does not need to adsorb wafer in the process, so according to the order of following (1)～(9), just can carry out the correction of wafer potential.Figure 10 (b) is the flow chart of this order of expression.

(1) sets the voltage of wafer potential correction with power supply 905.

(2) to the abundant little voltage of absorption power settings.

(3) obtain the reflection electronic picture of reference mark, try to achieve at this moment relative position (X1) corresponding to the reference mark at electron beam center.This value is stored in the memory in the control circuit 213.

The voltage of necessity when (4) the absorption power settings being described.

(5) obtain the reflection electronic picture of reference mark, try to achieve at this moment relative position (X2) corresponding to the reference mark at electron beam center.This value is stored in the memory in the control circuit 213.

(6) poor (dX) of calculating X1 and X2.

(7) judge whether dX has surpassed permissible value.

(8) if smaller or equal to permissible value, just begin to describe.

(9) under situation, change the set point of wafer potential correction with power supply 905 greater than permissible value.

Owing in describing process, can implement this method,, under the possibility situation greatly that wafer potential changes, can adjust the wafer potential correction once more with power supply 905 so electron beam current is had greatly changed etc.In addition, the electrostatic adsorption device of present embodiment can not only be installed in the drawing apparatus shown in Figure 2, and can be installed in other charged particle beam application systems such as surveying long SEM.

[embodiment 7]

Carried out in the present embodiment surveying the application of long SEM.Electrostatic chuck shown in Fig. 5 (a) is arranged in the long SEM of survey.In surveying long SEM, if the electric current of electron beam is about 10pA, will be lower than drawing apparatus.Therefore, also very little even the contact resistance of ground lead 107 is bigger to the influence of measuring, if but electrostatic chuck is big to the leakage current of ground lead, just this advantage can not be arranged.Use the galvanometer 506 that is connected on ambipolar electrostatic chuck 501,502 and the ground lead 107 in the present embodiment.By adjusting sucker voltage 503,504, make electric current smaller or equal to determined value, can seek to reduce the leakage current that flows to ground lead.Can relax the dependence of ground lead to contact resistance thus, its result can reduce ground lead by the pressure that is pressed on the wafer 101.It can suppress the side effects such as generation of dust, so become very big advantage.

This galvanometer 506 has enough precision, utilizes this electrostatic chuck, and it is 10pA that the feasible leakage current that flows to ground lead becomes smaller or equal to 1/1000000 of the absorption current 10 μ A of sucker.Surface potential also becomes below the 0.1V, and can make the measurement deviation that is produced by wafer is below the 1nm.

In addition, if adopt present embodiment, then the control of Electric potentials of wafer can not only be become earthing potential, and can be controlled to current potential arbitrarily.In the testing fixture that uses the current potential contrast etc.,, can carry out high speed and high-precision inspection by making desirable current potential on the wafer band.

Claims (12)

1, a kind of charged particle beam application system is characterized in that: have the sample objective table that keeps sample, to the unit of the irradiation of the sample on this sample objective table charged particle line and remain on electrostatic adsorption device on the said sample objective table;

This electrostatic adsorption device has:

Have the placed side of placing sample dielectric,

Be arranged on this dielectric inside electrode,

The contact terminal that contacts with said sample,

Be connected variable DC power supply on the above-mentioned electrode and DC power supply,

The current measuring unit that is connected with above-mentioned contact terminal,

According to the measurement result of this current measuring unit, the control unit of the voltage of above-mentioned variable DC power supply is given in control.

2, charged particle beam application system according to claim 1 is characterized in that:

Have a plurality of above-mentioned electrodes,

Above-mentioned variable DC power supply and DC power supply are connected on the different electrodes,

Above-mentioned a plurality of electrode, variable DC power supply and DC power supply constitute closed circuit.

3, charged particle beam application system according to claim 1 is characterized in that:

Have a plurality of above-mentioned electrodes,

Above-mentioned variable DC power supply and DC power supply are connected on the different electrodes,

Also have the feedback circuit that is configured between current measuring unit and the above-mentioned variable DC power supply.

4, charged particle beam application system according to claim 1 is characterized in that:

Have a plurality of above-mentioned electrodes,

Have a plurality of DC power supply corresponding to these a plurality of number of poles,

Above-mentioned variable DC power supply be configured between above-mentioned current measuring unit and the earthing potential or be configured in above-mentioned contact terminal and above-mentioned current measuring unit between.

5, charged particle beam application system according to claim 1 is characterized in that:

Have a plurality of above-mentioned contact terminals,

Above-mentioned DC power supply is configured between above-mentioned electrode and the earthing potential,

Above-mentioned variable DC power supply be configured between above-mentioned current measuring unit and the earthing potential or be configured in above-mentioned contact terminal and above-mentioned current measuring unit between.

6, charged particle beam application system according to claim 5 is characterized in that: have a plurality of above-mentioned electrodes and current measuring unit.

7, charged particle beam application system according to claim 4 is characterized in that:

Have 3 or more a plurality of above-mentioned contact terminal.

8, a kind of charged particle beam application system is characterized in that: have the sample objective table that keeps sample, to the unit of the irradiation of the sample on this sample objective table charged particle line and remain on electrostatic adsorption device on the said sample objective table;

This electrostatic adsorption device has:

Have the placed side of placing sample dielectric,

Be arranged on this dielectric inside electrode,

The contact terminal that makes said sample reach earthing potential to use,

Be connected to conductivity variable DC power supply on the above-mentioned electrode and DC power supply,

Control give control unit that the voltage of this variable DC power supply uses,

Measure potential measurement unit that the current potential of said sample uses and

Adjust the adjustment unit of the response speed of sample current potential;

Above-mentioned control unit calculates and gives the voltage of above-mentioned variable DC power supply according to the measurement result of this potential measurement unit.

9, charged particle beam application system according to claim 8 is characterized in that:

Above-mentioned adjustment unit is the resistance that is connected with above-mentioned contact terminal.

10, charged particle beam application system according to claim 9 is characterized in that:

Above-mentioned adjustment unit is arranged on the RC circuit between above-mentioned electrode and the earthing potential.

11, charged particle beam application system according to claim 10 is characterized in that:

The resistance of above-mentioned RC circuit and capacitor and above-mentioned variable DC power supply and electrode configuration in parallel.

12, a kind of charged particle beam application system has: the charged particle rifle; To be focused at the lens on the sample from the charged particle of above-mentioned charged particle rifle emission; The objective table that can in the sample processing procedure, move; And the electrostatic adsorption device on above-mentioned objective table, this electrostatic adsorption device has contact and is placed on the contact terminal of the sample on the holding member that is made of dielectric and above-mentioned dielectric is clipped in the middle and the opposed adsorption electrode of above-mentioned contact terminal, electrostatic force takes place between above-mentioned contact terminal and above-mentioned adsorption electrode, utilize this electrostatic force that said sample is adsorbed on the above-mentioned holding member

This charged particle beam application system is characterised in that and has:

Reference mark with the adjacent setting of said sample; Detection is to the unit of the relative position of the irradiation position of the charged particle line of said sample or said reference sign; And being used to of being connected with above-mentioned contact terminal adjust the DC power supply of the current potential of said sample.

Images