CN100382272C - Semiconductor device tester - Google Patents

Abstract

Current produced in a sample 5 by irradiating the sample with parallel electron beam 2 is measured by an ammeter 9. The measurement is repeated while changing acceleration voltage of electron beam 2. An information related to a structure of the sample 5 in a depth direction thereof is obtained by a data processor 10, on the basis or a difference in transmittivity of electron beam 2 into the sample 5 due to the difference of acceleration voltage.

Description

Device for checking semiconductor device

Technical field

The present invention relates to a kind of inspection of having used the semiconductor device of electron beam, particularly relate to based on measuring because of the irradiation of electron beam inspection at the semiconductor device that is examined the electric current that produces on the sample.

Background technology

In general, be used for the contact hole and the intercommunicating pore that between the wiring layer on the active element of bottom and top, connect being formed with on the semiconductor device of memory etc.Contact hole is film formed by means of insulation such as reactive ion etching oxide-films, is the through hole from the surface to the underlay substrate.For the optimization etching condition, must detect face shaping and the interior shape of contact hole or the state of contact hole bottom of contact hole.

The size of contact aperture is below the micron dimension, and therefore, visible light can't incide the bottom of contact hole, is difficult to detect its quality with method of optics.Therefore, be used for the scanning electron microscopy (SEM:Scanning Electron Microscope) that fine structure analyzes and be used as main testing fixture.In SEM, make the electron beam hits that is accelerated to tens keV and is focused several m to the contact hole zone, detect the secondary electron that on the zone of having been collided, produces and form image by the secondary electron checkout gear.The sample of illuminated electron beam produces the secondary electron of respective amount according to its constituting atom, but the secondary electron checkout gear generally is provided on the specific direction in SEM, does not detect all secondary electrons.Therefore, when on sample, existing when concavo-convex,, thereby produce contrast even if same material also can produce situation that secondary electron is detected and the situation that is not detected.The inspection object that Here it is is made up of same substance produces the reason of contrast, and this is the feature of SEM.

On the other hand, in contact hole or through hole, the conduction contact realizes that in the contact hole bottom therefore, the peristome of contact hole is no doubt important, and the shape and the surface state thereof of contact hole bottom are also extremely important.Because of in recent years high integration and multiple stratification, in being used to form the etching process that depth-width ratio surpasses 10 contact hole, even if under the situation that identical peristome diameter is arranged, also may cause the inside diameter difference because of the difference of treatment conditions.The irregular meeting of contact hole inside dimension like this has big influence to Devices Characteristics, therefore, handles the necessary control and treatment process of owner, makes all contact holes have identical size.Also have, in the goods of reality, can not have these inside dimensions irregular, therefore, must be goods as checking object, and the technology that can nondestructively detect the two (inside dimension of contact hole and discrete) is extremely important.

Fig. 4 and Fig. 5 have represented to use the example of SEM, separately the example of expression (a) inspection method, (b) check result.Fig. 4 is the inspection example of columned contact hole, and Fig. 5 is the inspection example of the contact hole of taper.In inspection based on SEM, make electron beam 31 being examined scan edge limit irradiation on the sample, detect from being examined the secondary electron 32 that sample produces by secondary electron detector 33.

Shown in Fig. 4 (a), suppose to be examined sample be configured on underlay substrate 42, be provided with dielectric films 41 such as oxide-film and on this dielectric film 41, be carried out vertical etching and to form columned contact hole 43 with peristome diameter much at one from peristome.In the case, because of the energy of secondary electron is little, be not difficult to arrive detector if it is open on every side, the measured value of secondary electron amount is such shown in Fig. 4 (b).That is to say that resulting secondary electron resembles in the rapid deepening in the peristome corresponding position of contact hole 46.Hence one can see that has contact hole at this place.

On the other hand, shown in Fig. 5 (a), the shape of contact hole 44 is assumed to be taper, and its diameter of the depths in past more hole is more little, and is different with the peristome diameter.In the case, though might observe secondary electron according to the position of detector from the tapering, the depth-width ratio value height of contact hole 44 in fact, shown in Fig. 5 (c), in fact the electronics from the hole inwall does not observe basically.Therefore, the information of the shape of contact hole 44 or its bottom is not reflected to secondary electron and resembles.

Fig. 5 (a) even if shown in such its peristome of taper contact hole good, but front, past more bottom is narrow more, it is different with design object that the aperture becomes, contact resistance increases, therefore, it is defective that contact hole also might become.But no matter the shape of contact hole is cylindric or taper, resulting detection resembles all in the rapid deepening of peristome part in the inspection based on SEM, and the information of bottom is not formed same resembling by reflection.Therefore, in common SEM, in fact can't distinguish both.

The method that the central part of the contact hole by the slit shearing sample assigns to observe section is used as the method for checking inner or its bottom of contact hole.The method need accurately be divided into contact hole the high-caliber technology of positive two halves at the center of contact hole, considers that present contact aperture is the magnitude of several thousand dusts, in fact can not cut the contact hole central part with the precision of qualification determination necessary 10%.Also have, this is to diminish observation, and goods can not be directly in sight, and are very bothersome and time-consuming in addition.

As the mechanism that solves such problem, open to disclose in the flat 10-281746 communique the spy and detect by passing position and the size that contact hole arrives the electric current that electron beam produced of substrate and detects the bottom of contact hole.Open to disclose in the flat 4-62857 communique the spy and observe the method for secondary electron elephant and put down in writing the method for measuring because of the substrate current that irradiation produced of ion beam by irradiation ion beam rather than electron beam.

Also have,, open the spy and to disclose the method that the substrate current that is formed for measuring the mask position deviation of the alignment and produces during according to irradiating electron beam is obtained the position alignment departure in the flat 11-026343 communique as similar techniques.Open the spy and to disclose the method that electron beam is radiated on the zone that comprises a plurality of contact holes and checks the ratio of the normal contact hole on this zone according to the current value that passes these holes in the 2000-174077 communique.

Also have, also may learn thickness, open substrate current when disclosing the electron beam of obtaining the radiation pulses shape in advance in the clear 62-19707 communique in the accelerating voltage and the relation between the thickness of waveform on the time shaft and electron beam and try to achieve the method for thickness from the current waveform of measuring with the electron beam of certain accelerating voltage the spy by measuring substrate current.The spy open disclose in the 2000-124276 communique measure electron beam is radiated at be penetrated into after being examined on the sample electric current at the back side, promptly be not electric current over time but the method for current value itself.Open to disclose in the 2000-180143 communique to measure the spy and pass that film arrives the electric current of substrate and by the value of the electric current of this mensuration and standard sample is compared the method for trying to achieve thickness, open the spy and disclose the standard sample that is applicable to the method in the 2000-164715 communique.

Summary of the invention

The objective of the invention is to further improve the technology that detects the substrate current that the irradiation by electron beam produces, a device for checking semiconductor device that can carry out nondestructive inspection (NDI) to the internal state of the detail shape of contact hole and semiconductor device is provided.

Device for checking semiconductor device of the present invention, possessing to have makes electron beam in the electron beam irradiation means that is examined scan edge limit irradiation on the semiconductor device of sample, be determined at and be examined on the sample because of the amperometric determination mechanism of the electric current that irradiation produced of electron beam and the measurement result of this amperometric determination mechanism carried out the DPA data processing activity of data processing, it is characterized in that in this device for checking semiconductor device, above-mentioned electron beam irradiation means comprises the mechanism of the accelerating voltage that makes the parallel collimation mechanism of electron beam and change electron beam, and above-mentioned DPA data processing activity comprises that from different accelerating voltage scanning beam time electron beam obtains the mechanism of the information relevant with the structure of the depth direction that is examined sample to the difference of the penetrance that is examined sample.

Adopt parallel electron beam to be in the present invention because in the pack electron beam, must measure on the height in place the information that make the electron beam pack, be unfavorable for obtaining being examined the depth direction of sample.If the employing parallel electron beam, then the degree of depth of focus is unlimited, also can not carry out focal adjustments.

Can check whether contact hole penetrates though open in the flat 10-281746 communique disclosed technology, can not get the details of the shape etc. of contact hole above-mentioned spy.Open the technology described in the flat 4-62857 communique too the spy who uses ion beam.Though open the spy and to record the content that the magnitude of current that makes electron beam or accelerating voltage change among the 2000-124276, this is used to reduce noise, be not the structure that is used to study the depth direction that is examined sample.Though open the content that records the use parallel beam in the 2000-174077 communique the spy, but this parallel beam is to be used to be radiated on the zone that comprises a plurality of contact holes, is not the structure that is used to study each contact hole or other the depth direction that is examined sample.

Above-mentioned electron beam irradiation means comprises electron gun, above-mentioned collimation mechanism comprises to be made the electron beam that is penetrated by above-mentioned electron gun become parallel condenser lens and to get to the beam spot size that is examined on the semiconductor device and at above-mentioned condenser lens be examined the electron beam that can make that is inserted between the sample and get to the limit bundle circle of peristome in order limiting, and preferably possesses to have to make for scanning beam to be examined the mechanism that sample moves with respect to electron beam.

Also have, above-mentioned electron beam irradiation means comprises electron gun, above-mentioned collimation mechanism comprises makes the electron beam that is penetrated by above-mentioned electron gun become the first parallel condenser lens, be configured to constitute second condenser lens, the object lens of afocal system and being used to of being inserted between above-mentioned first condenser lens and above-mentioned second condenser lens limits the limit bundle circle of the size of beam spot, can also possess to have to make for scanning beam to be examined the mechanism that sample moves with respect to electron beam.

Above-mentioned electron beam irradiation means comprises makes bundle spot size than measuring the little electron beam of region area along vertically shining the mechanism that is examined on the sample by the line segment of measuring district center, and above-mentioned DPA data processing activity can comprise the mechanism that obtains the distance from bottom of measuring the district from the interval of the rising edge of the electric current of measuring along above-mentioned line segment and trailing edge.

Above-mentioned DPA data processing activity can comprise that value of current flowing obtains when removing the unknown electron beam of certain condition of having measured area illumination with value of current flowing when the known standard sample of area of measuring the zone has been shone the electron beam of certain condition value obtains the above-mentioned area of measuring district's area of seeking knowledge and calculate mechanism.In the case, above-mentioned DPA data processing activity can also comprise with circumference ratio remove by

Above-mentioned area is calculated the resulting area of mechanism and the square root of the value that obtains is calculated mechanism as the above-mentioned unknown distance of measuring the distance at the two ends of distinguishing.

Above-mentioned electron beam irradiation means comprises the mechanism that the beam spot size is set at the size that makes it to comprise simultaneously whole mensuration zone, above-mentioned DPA data processing activity can comprise calculate the current value that on the known standard sample of the area of measuring the zone, produces during irradiating electron beam with the beam spot size of above-mentioned size and with the mensuration zone of beam spot size at unknown sample of above-mentioned size between the current value that produces during irradiating electron beam size mechanism and calculate the mechanism of the mensuration region area of unknown sample by this ratio.

The current value that above-mentioned DPA data processing activity produces in the time of can comprising the known electron beam of irradiation beam spot size on standard sample is as the mechanism of the average magnitude of current of standard sample unit are.

Above-mentioned DPA data processing activity can also comprise the kind that the current value of measuring corresponding to the position coordinates of the determination object wafer that is shone by electron beam and the current value measured at this position coordinates is compared and set according to this comparative result the operation of then carrying out under the situation of qualified wafer.

The present invention can be used in combination with SEM.That is to say, possess the secondary electron detector that detects the secondary electron that penetrates from the surface that is examined processing is arranged, above-mentioned DPA data processing activity can comprise makes the mechanism that the detected secondary electron amount of secondary electron detector thus is corresponding with the measurement result of above-mentioned amperometric determination mechanism and handle.Specifically, can make bundle spot size by means of above-mentioned electron beam irradiation means is examined on the sample along vertically shining by the line segment of measuring district center than measuring the little electron beam of region area, can obtain the distance from bottom of measuring the district from the rising edge of the electric current measured along above-mentioned line segment and the interval of trailing edge by means of the above-mentioned mechanism that carries out alignment processing, can obtain the top distance of measuring the district from the rising edge of the secondary electron amount that is detected and the interval of trailing edge by means of above-mentioned secondary electron detector.The above-mentioned mechanism that carries out alignment processing can comprise distance from bottom from the mensuration district that is measured, top distance and thickness information to respectively distance from bottom, top distance and thickness being carried out the mechanisms that 3 dimensions show as the cylinder or the circular cone of base diameter, upper diameter and height.

Possess to have to make and adorning the mechanism that the sample stage that is examined sample tilts, above-mentioned DPA data processing activity can comprise being examined the mechanism that sample is taken into account and handled with respect to the inclination angle of the electron beam that this leaning device produced.

Current value that above-mentioned DPA data processing activity also can comprise the mechanism of the storage current value corresponding with the electron beam irradiation position that obtains in the free from dust place that is examined sample, storing this storing mechanism and the mechanism that compares with the corresponding current value of the electron beam irradiation position on same general layout position of unknown sample and define free from dust and definite its big or small mechanism from the difference of the position of the rising edge of this more resulting current value and trailing edge.

It is the mechanism of linearity that above-mentioned electron beam irradiation means comprises that the section shape of setting electron beam makes it can TBI whole mensuration zone and make the one end at least, and above-mentioned DPA data processing activity can comprise according to the mechanism of trying to achieve the distance of measuring the zone from the rising edge of current value to peaked interval.

It is the mechanism of linearity that above-mentioned electron beam irradiation means comprises that the section shape of setting electron beam makes it can TBI whole mensuration zone and make the one end at least, and above-mentioned DPA data processing activity also can comprise calculates current value with respect to the mechanism of the differential curve of distance with according to the mechanism of trying to achieve the radius of measuring the zone from the rising edge of this differential curve to the interval of the position on expression summit.

Above-mentioned DPA data processing activity also can comprise the current value of being measured is presented at and the corresponding map that locates on mechanism.

Above-mentioned DPA data processing activity can comprise two zones on the wafer respectively as be examined sample and be fiducial value in the resulting measured value in first district with in comparison mechanism that the resulting measured value in second district compares with when mechanism that this comparative result is extracted this position coordinates out during above pre-specified certain difference.

In the case, above-mentioned electron beam irradiation means can comprise makes length and the wiring width that is examined sample wire electron beam much at one along the scanning direction vertical with the length direction of line and make the only mechanism of the distance of mobile wiring width of the scanning position edge direction vertical with the scanning direction scan 1 line after, and above-mentioned comparison mechanism can comprise the mechanism that the current waveform of being measured on each above-mentioned 2 zone of leisure as the variation of the current value of phase antithetical phrase electron beam irradiation position is compared.

Above-mentioned electron beam irradiation means comprise makes size than the also little electron beam of the minimum wiring width of the wiring that is examined sample in scanning on the first direction and whenever scan 1 line after, make the only mechanism of the distance of mobile wiring width of the scanning position edge direction vertical with the scanning direction, the above-mentioned mechanism that compares can comprise the conduct measured from each above-mentioned 2 zone of leisure and is positioned at the transient current amount at center of rising edge corresponding with same general layout position and trailing edge and the mechanism that compares with respect to the current waveform extraction of the variation of the current value of electron beam irradiation position.

Above-mentioned electron beam irradiation means comprises makes the wire electron beam that can shine many wirings that are examined sample simultaneously along the scanning direction vertical with the length direction of line and make the mechanism of the distance of the scanning position edge direction only mobile irradiating electron beam width vertical with the scanning direction whenever scan 1 line after, and above-mentioned comparison mechanism can comprise the mechanism that compares with respect to the current waveform of the variation of electron beam irradiation position as current value that is measured on each above-mentioned 2 zone of leisure.In the case, the mechanism of above-mentioned relatively current waveform can comprise current waveform is carried out the integration and the mechanism of this integrated value relatively.

Above-mentioned relatively mechanism also can comprise to measured as current value with respect to the electric current that from the rising edge to the trailing edge, is flowed of a pulse of the current waveform of the variation of electron beam irradiation position carry out the mechanism of integration, resulting integrated value divided by the division mechanism of the width from the rising edge to the trailing edge of this pulse with to above-mentioned 2 regional mechanisms of the average current value of the resulting unit length of division mechanism more thus.

Above-mentioned relatively mechanism both can comprise that comparison measures as the mechanism of current value with respect to the position of the rising edge of the current waveform pulse of the variation of electron beam irradiation position and trailing edge, also can comprise the mechanism of its center of comparison.

Above-mentioned electron beam irradiation means can comprise make be examined main scanning mechanism that sample moves with respect to electron beam with based on the main scanning stack of this main scanning mechanism and on the direction different, make the subscan mechanism of the electron beam deflecting repeatedly with the direction of main scanning.

Above-mentioned electron beam irradiation mechanism can switch to be made electron beam irradiation at the first mode in each wiring that is examined sample and is radiated at simultaneously the second pattern in a plurality of above-mentioned wirings that are examined sample, and above-mentioned DPA data processing activity can be included in the above-mentioned first mode and to continue the mechanism of the position during certain and to suppose a plurality ofly to be routed in detected position and to be adapted to array-like and also the pattern of above-mentioned electron beam irradiation mechanism to be set as the mechanism that defective ratio is obtained in above-mentioned the second pattern and concentrated area carrying out spatial-frequency analysis between every certain lane place and detect the interval with the same space frequency with respect to the current waveform of the variation of electron beam irradiation position as current value to what measure.

The above-mentioned mechanism that obtains the information relevant with the structure of depth direction preferably include to be located on the dielectric film the hole from by means of electron beam along with the raising of accelerating voltage pass this hole around the current value measured of dielectric film obtain the mechanism of the 3D shape in this hole.

In order to obtain the 3D shape in hole, must know the thickness of dielectric film.For this reason, can use the spy to open clear 62-19707 communique, spy opens the 2000-124276 communique or specially opens the technology described in the 2000-180143 communique.

Possess to have to make and adorning the mechanism that the sample stage that is examined sample tilts, the above-mentioned mechanism that obtains 3D shape preferably includes measured value when making electron beam and electron beam with respect to the incident angle that is examined sample and change, and to distinguish the shape in hole be the mechanism that upwards enlarges or enlarge downwards.

The above-mentioned mechanism that obtains the information relevant with the structure of depth direction can comprise from pass the mechanism that measured value that insulating barrier obtains detects the deviation of the circuit layout in this insulating barrier by means of electron beam.

Open the spy and to disclose the method for measuring the mask position deviation of the alignment in the flat 11-026343 communique, but be to utilize a kind of object that the mensuration that just produces through hole is on time passed the electron beam of insulating barrier with the object rather than the utilization of pattern at mask position as determination object.

The above-mentioned mechanism that detects the deviation of circuit layout can comprise the mechanism of deviation that estimates the circuit layout of each layer according to the measured value when changing accelerating voltage and change the arrival degree of depth of electron beam.In order in insulating barrier, to obtain the overlapping position of circuit layout, preferably to possess the mechanism that is taken into the information relevant with this circuit layout from cad data is arranged.

In above formation, obtaining by means of electron beam scanning of current waveform carried out, in the electric current that is observed, comprise because of its irradiation frequency or scanning frequency cause flowing through sample with the electric current of electric capacity.Therefore, originally direct current should there be the sample of electric current as there being electric current determined.For fear of this problem, above-mentioned DPA data processing activity preferably include to cause flowing through because of the irradiation frequency of electron beam or scanning frequency be examined sample with the mechanism revised of the electric current composition of electric capacity.Specifically, under the situation of the formation of the electron beam that produces pulse type repeatedly, above-mentioned electron beam irradiation means possesses the mechanism of the repetition period of this electron beam that changes, above-mentioned correction mechanism preferably comprise from different repetition period irradiating electron beam the time according to above-mentioned amperometric determination mechanism the current value extrapolation electron beam measured separately during by Continuous irradiation current value and obtain the mechanism of flip-flop.Possess the mechanism of switching based on the beam scan velocity of above-mentioned electron beam irradiation means arranged, above-mentioned correction mechanism also can comprise from the time with different sweep speed scanning beam according to above-mentioned amperometric determination mechanism the current value measured separately obtain the mechanism of the current value when sweep speed is extrapolated to zero.

Description of drawings

Below accompanying drawing is carried out simple declaration.

Fig. 1 is the square frame pie graph of the expression embodiment of the invention 1.

Fig. 2 is the square frame pie graph of the expression embodiment of the invention 2.

Fig. 3 restraints the figure of circle configuration example for the expression limit, and (a) expression is used to make the cross sectional shape of bundle to be circular limit bundle circle, and (b) representing to be used to make the cross sectional shape of bundle is foursquare limit bundle circle.

Fig. 4 is the figure that is used to illustrate the inspection example of the columned contact hole that has used SEM, (a) example of the example of expression inspection method, (b) expression check result.

Fig. 5 is the figure that is used to illustrate the inspection example of the cone shape contact hole that has used SEM, (a) example of the example of expression inspection method, (b) expression check result.

Fig. 6 is the figure of explanation assay method, and (a) expression is as the example of the structure of the contact hole of object and mensuration system thereof, (b) expression measurement result.

Fig. 7 is the figure that is used to illustrate to the mensuration of taper contact hole, and (a) expression is as the example of the structure of the contact hole of object and mensuration system thereof, (b) expression measurement result.

Fig. 8 represents the variation of offset current amount with the contact hole floor space.

Fig. 9 represents the diameter variation at the bottom of the offset current amount is with contact hole.

Figure 10 is the key diagram that has used the mensuration of the electron beam with size cross sectional shape bigger than hole peristome, and (a) expression is as the example of the structure of the contact hole of object and mensuration system thereof, (b) expression measurement result.

Figure 11 is the key diagram that has used the mensuration of the electron beam with size cross sectional shape bigger than hole peristome, and (a) expression is as the example of the structure of the contact hole of object and mensuration system thereof, (b) expression measurement result.

Figure 12 is the key diagram that has used the same mensuration of the diameter bundle littler than contact hole diameter, and (a) expression is as the example of the structure of the contact hole of object and mensuration system thereof, (b) expression measurement result.

Whether qualified Figure 13 be illustrated in the flow chart of the situation of producing the mensuration of utilizing the contact hole base diameter in the factory in batches and judgement example.

Figure 14 is used to illustrate to having columned contact hole and figure SEM simultaneous determination example, and what (a) relation, (c) expression of the irradiation position of the secondary electron amount measured along the contact hole center line as the structure of the contact hole of object and mensuration system thereof, (b) expression of expression and offset current and electron beam had recovered 3 ties up display graphics.

Figure 15 is the figure that is used to illustrate to the same mensuration with the cone shape contact hole of forward.

Figure 16 is the figure that is used to illustrate to based on the same mensuration of the columned contact hole of inclination electron beam.

Figure 17 is the figure that is used to illustrate to the same mensuration of the cone shape contact hole of forward.

Figure 18 is the figure that is used to illustrate to the same mensuration of the contact hole of inverted cone-shaped.

Figure 19 is used to illustrate the figure that detects in the specific method of the inner foreign matter that produces of contact hole, and (a) relation of the irradiation position of the structure of object and mensuration system, secondary electron amount that (b) expression is measured and offset current and electron beam is checked in expression.

Figure 20 is used to illustrate the same figure that detects in the specific method of the inner foreign matter that produces of contact hole.

Figure 21 is used to illustrate the same figure that detects in the specific method of the inner foreign matter that produces of contact hole.

Figure 22 is the figure that expression has utilized the mensuration example of the big electron beam of cross sectional shape, and (a) vertical view, (b) for the relation of the position between expression contact hole and the electron beam is that cutaway view, (c) represent with respect to resulting offset current of the scanning position of electron beam and differential value thereof.

Figure 23 represents to survey the flow chart of long pattern and the assay method of the combination of overall mode determination.

Figure 24 represents a survey long pattern subject area on the wafer and an example of the position relation between the overall mode determination subject area.

Figure 25 represents in order to utilize 2 to be examined the device configuration example that sample compares inspection.

Figure 26 represents to check flow process.

Figure 27 is the figure of the principle of explanation audit by comparison.

Figure 28 is an enlarged drawing.

Figure 29 checks routine figure for expression, (a) the mensuration example of the mensuration example of expression qualified chip, the defective chip of (b) expression.

Figure 30 is the figure that is used to illustrate the audit by comparison example of having used thin electron beam, (a) the mensuration example of the mensuration example of expression qualified chip, the defective chip of (b) expression.

Figure 31 is used to illustrate the figure that simultaneously the wire electron beam is radiated at the audit by comparison example in a plurality of wirings that set at random, (a) the mensuration example of the mensuration example of expression qualified chip, the defective chip of (b) expression.

Figure 32 is used to illustrate the figure that is routed in the inspection example that vertically has identical shaped situation, (a) the mensuration example of the mensuration example of expression qualified chip, the defective chip of (b) expression.

Figure 33 is the figure that is used to illustrate the inspection example of the situation that has the different wiring of wiring width axisymmetrically, (a) the mensuration example of the mensuration example of expression qualified product, (b) expression defective item.

The figure of the inspection example of the situation that Figure 34 exists brokenly for expression width different wiring, (a) the mensuration example of the mensuration example of expression qualified product, (b) expression defective item.

Figure 35 represents the configuration example of testing fixture that current waveform is compared by its integrated value.

Figure 36 represents to check flow process.

Figure 37 represents to compare by the current value of average unit are the configuration example of the testing fixture of inspection.

Figure 38 represents to check flow process.

Figure 39 is used to illustrate electron beam to the coverage rate of wiring and the figure of the relation between the current waveform, (a) example of the example of expression coverage rate 100%, figure (b) expression coverage rate 50%.

Figure 40 represents in order to use a plurality of chips on same substrate to compare the configuration example of the testing fixture of inspection.

Figure 41 represents to check flow process.

Figure 42 represents to judge the inspection flow process that wiring is whether qualified according to the rising edge of current waveform and trailing edge.

Figure 43 checks routine figure for expression, and (a) expression qualified product, figure (b) represent defective item.

Figure 44 represents that the center by the rising edge of current waveform and trailing edge judges the inspection flow process that wiring is whether qualified.

Figure 45 represents to carry out the configuration example of device of the subscan of electron beam.

Figure 46 represents an example of track while scan.

Figure 47 represents to make the inspection flow process of the inspection high speed of array area.

Figure 48 represents an example of the power spectrum that obtains by frequency analysis.

Figure 49 is the figure of mensuration that is used to illustrate the 3 dimension shapes in hole.

Figure 50 is the figure of mensuration that is used to illustrate the 3 dimension shapes in hole.

Figure 51 is the figure of mensuration that is used to illustrate the 3 dimension shapes in hole.

Figure 52 is the figure of mensuration that is used to illustrate the 3 dimension shapes in hole.

Figure 53 is the figure of mensuration that is used to illustrate the 3 dimension shapes in hole.

Figure 54 is the figure of mensuration that is used to illustrate the 3 dimension shapes in hole.

Figure 55 represents to be used for obtaining by the method for successive approximation handling process of 3 dimension shapes.

The figure that Figure 56 handles for explanation.

The figure that Figure 57 handles for explanation.

The figure that Figure 58 handles for explanation.

The example that Figure 59 represents to misplace and estimates, (a) profile, (b) of expression device represent measurement result.

Another example that Figure 60 represents to misplace and estimates, (a) device cutaway view, (b) of the situation of expression dislocation-free represent measurement result.

Figure 61 be illustrated in the same element of Figure 60 on the example of the situation that has dislocation, (a) cutaway view, (b) of expression device represent measurement result.

Other other examples that Figure 62 represents to misplace and estimates, (a) cutaway view, (b) of expression device represent measurement result.

Figure 63 represents the mensuration flow process when main insulating layer has only a kind of material.

Figure 64 represents the example to the offset current of thickness.

Figure 65 represents the example to the offset current of accelerating voltage.

Mensuration flow process when Figure 66 represents many insulating barriers are arranged.

Figure 67 is illustrated in the dislocation determination flow after the image that obtains every layer.

Figure 68 represents to be used for once obtaining the mensuration flow process of multi-layer information.

Figure 69 represents the handling process of an example of background correction.

Figure 70 represents another routine handling process of background correction.

Among the figure, 1: electron gun, 2,12: electron beam, 3,13,15: convergent lens, 4,14: limit bundle circle, 5: sample, 6: movable sample stage, 7: electrode, 8: the moving distance measuring device, 9: galvanometer, 10: data processing equipment, 11: line control part, 16: the thing lens.

Inventive embodiment

Followingly embodiments of the invention are elaborated with reference to accompanying drawing.Also have, in the drawings, same key element is enclosed identical symbol and omitted its explanation.

(generation of parallel electron beam)

Fig. 1 is the square frame pie graph of the expression embodiment of the invention 1.This device possesses the electron gun 1 that produces electron beam 2 is arranged, the convergent lens 3 of collimated electron beam and limit bundle circle 4, move and the removable sample stage 6 of the irradiation position of scanning beam 2 by the sample 5 that makes inspected object, the electrode 7 and the galvanometer 9 of the electric current that mensuration produces on sample 5 because of the irradiation of electron beam 2, measure the moving distance measuring device 8 of the displacement of removable sample stage 6, the line control part 11 that the measurement result of galvanometer 9 is carried out the data processing equipments such as computer 10 of data processing and carried out controls such as the change of accelerating voltage of electron beam and the change of exposure period.

The electron beam 2 that is penetrated by electron gun 1 is converted to parallel electron beam, is irradiated on the limit bundle circle 4 that is provided with very little hole then by convergent lens 3 earlier.Limit bundle circle 4 is made by metal etc., and the electronics that shines on the limit bundle circle 4 can not be accumulated in the limit bundle and encloses on 4 because of being grounded.Passed through to limit the electron beam 2 of bundle circle 4 to become size and limit the bundle circle 4 very thin bundles about the same that limited and be irradiated onto on the sample 5.In order to prevent that limit bundle loop diameter from changing because of heating, can make the formation of cooling limit bundle circle.

Fig. 3 represents to limit the configuration example of restrainting circle, and (a) representing to be used to make the cross sectional shape of bundle is foursquare limit bundle circle for circular limit bundle circle, (b) represent to be used to make the cross sectional shape of bundle.These limit bundle circles have peristome 21 at about central part, are shielding part 22 around it.Can be difficult for producing the material that the material of gas such as tungsten, molybdenum, silicon, polysilicon, gold, palladium, titanium etc. are used as shielding part 22 when being shone by electron beam.The diameter of limit bundle circle is inner and obtain and be made as hundreds of  under the situation of distance and be made as several microns size to 1000 , under the situation of a contact hole of once electron beam irradiation at the scanning contact hole.The shape of limit bundle circle not only can be with square or circular, also can be with rectangle or oval or other polygons.

Little bundle is all no problem no matter electron beam is big bundle of usefulness sectional area proportional limit bundle circle peristome or sectional area proportional limit bundle circle peristome.Under the little situation of the area of the sectional area proportional limit bundle circle peristome of electron beam, can obtain identical result with the big Shu Jinhang irradiation of sectional area ratio peristome the time by scanning limit(s) bundle circle peristome.

Sample 5 is placed on the electrode 7 that electric current collection uses and this electrode 7 is placed on the removable sample stage 6.Near removable sample stage 6, be provided with the moving distance measuring device 8 of accurately measuring the displacement of removable sample stage 6 according to the principle of interferometer etc. with the magnitude of dust.Be generally the device of optical profile type as moving distance measuring device 8, but also can use based on detect with the device of the principle of the physical quantity of variable in distance as the device that used electromagnetic wave, resistance or electric capacity, utilized the device of quantum mechanical effects etc.

Can set according to contacting on the direct current meaning with electrode 7 sample 5, shine electron beam on the sample 5 by situation with high frequency modulated under, can measure electric current by capacitive coupling, therefore, electrode 7 is abutted against on the sample 5.In general, in semiconductor manufacturing process, be formed for the partial oxidation film that element separates at substrate back usually, therefore, on chip back surface, be formed with dielectric film usually.Under the situation of such wafer as sample 5, in order to realize the contact between sample 5 and the sample stage 6, it also is effective using the capacitive coupling sample stage.Also can utilize the side of wafer to connect.

The size of the contact hole that cause will be measured is very little, and sample 5 very level land is placed on the sample stage 6.For this reason, the periphery of for example pushing down sample 5 with the anchor clamps of ring-type also is effective.

Electric current collected on the electrode is determined by galvanometer 9.Measurement result is converted into digital signal and is output to data processing equipment 10.In order to improve noise tolerance, the formation of galvanometer 9 being got differential amplifier also is effective.

Data processing equipment 10 carries out various data processing, particularly with different accelerating voltage scanning beam the time, electron beam is to being examined the transmissivity difference of sample, therefore, can obtain the information relevant with the structure of the depth direction that is examined sample.

Fig. 2 is the square frame pie graph of the expression embodiment of the invention 2.Particularly expression utilizes the formation of the situation of the following thin electron beam of micron dimension.This device forms focusing system as the generation system of electron beam by second convergent lens 15 and object lens 16, has the incident parallel beam is converted to diameter than the electron-optical system by the littler parallel beam of limit bundle circle 14 scopes that limited.

That is to say that the electron beam 12 that is penetrated by electron gun 1 is converted into parallel beam, passes limit bundle circle 14 and be converted into thin parallel beam then by first convergent lens 13 earlier.Then, line is focused and incides on the object lens 16 by second convergent lens 15.In this electron beam generating device, limit bundle circle is not used to be irradiated to the shaping of the final line on the sample 5, therefore, can be implemented in the very thin line of the 100  magnitudes that are difficult to realize in the direct microfabrication easily.Such pencil stream also can obtain and the thick identical effect of situation of restrainting of TBI by the scanning large tracts of land.

By secondary electron detector is set, Fig. 1 or device shown in Figure 2 also can be used on the SEM such shown in Fig. 4 (a), Fig. 5 (a).

Here in advance the contact hole as main inspection object of the present invention is described.Contact hole is for from being arranged on oxide-film on the underlay substrate such as silicon substrate or the dielectric surface through hole till the underlay substrate.In the excellent contact hole, underlay substrate surface or the wiring layer surface that becomes substrate are in exposes state.

Contact hole is to be that poroid oxide-film is partly gone up and formed by fluoro-gas is applied in by the etchant resist opening as the reactive ion etching of etchant.The contact hole that now mainly is utilized has very elongated structure, is that several microns apertures are 0.15 micron with respect to the oxide thickness that constitutes the contact hole wall, and aspect ratio surpasses 10.Reactive ion etching is the physical chemistry etching.Etched actual speed is by the formation speed decision of the fluorohydrocarbon polymeric membrane that produces with respect to the speed of the vertical fluoro-gas ion(ic) etching oxide-film of irradiation at a high speed of substrate surface with by this etching reaction.Generally speaking, carried out the etched reaction of oxide-film, and the fluorohydrocarbon polymeric membrane is deposited on by on the formed contact hole sidewall of etching reaction by the contact hole inside that the fluoro-gas ion shines at a high speed.Sidewall is avoided etching because of this mechanism, therefore, can form very dark vertical hole.On the other hand, carrying out and contact hole when arriving on the underlay substrate when etching, because of there not being oxygen on the substrate, etching reaction becomes the reaction that polymeric membrane generates main body from the oxide-film etching reaction, carries out among automatically preventing to be etched in underlay substrate.

But these molecular balances are comparatively delicate, the delicate condition of manufacturing installation change may cause being etched in arrive stop suddenly before the substrate or etching substrate.These can produce underproof contact hole or through hole, therefore, must detect these problems.

(mensuration of the base diameter of contact hole)

Technology to the base diameter of measuring such contact hole describes below.Fig. 6 is the figure of explanation assay method, and (a) expression is as the example of the structure of the contact hole of object and mensuration system thereof, (b) expression measurement result.The contact hole 43 of determination object runs through the dielectric film 41 that is arranged on the underlay substrate 42 and is formed.Oxide-film or nitride film etc. can be used as dielectric film 41.In the excellent contact hole, the surface of underlay substrate 42 or the wiring layer surface that becomes substrate are in exposes state.Being that the electron beam 31 of 100  degree is with respect to the samples vertical incident that is provided with such contact hole 43 by Fig. 1 or the resulting beam diameter of device shown in Figure 2.The accelerating voltage of supposing electron beam 31 is that 0.5kV arrives a few kV degree, and the magnitude of current is a few nA degree.When electron beam 31 passes contact hole 43 and reaches underlay substrate 42, on underlay substrate 42, produce electric current.This electric current is called " offset current ".The corresponding relation of the offset current that produces when expression scans electron beam along about the center line of contact hole 43 in Fig. 6 (b) and the irradiation position of electron beam.

Shown in Fig. 6 (b), it is long-pending that electron beam has limited area of beam, and therefore, offset current began to rise from the moment that line crosses the dielectric film end, and when line reached the bottom of contact hole fully, compensation current reached capacity.When line was left by the bottom of contact hole, electric current was reduced gradually by saturation current too, when line leaves the bottom of touching the hole fully, and the offset current vanishing.

It is circular that contact hole is essentially, and therefore, the distance of sign contact hole feature is diameter of a circle or the radius at the bottom of the regulation contact hole.For asking these, instrumentation must carry out along the center line of contact hole.The position of irradiating electron beam is from resembling as secondary electron or the cad data of design information is calculated correct position, with motor or electron beam, makes the center line of scanning by contact hole with the Position Control of deflector control wafer platform thus.

Be shown in that offset current on Fig. 6 (b) longitudinal axis has the thickness of the oxide-film that depends on the contact hole bottom and the character that changes.That is to say, resemble contact the hole wall on the thick oxide-film zone offset current almost nil, on the other hand, on the zone of exposing, observe big offset current as the silicon or the wiring of substrate.Therefore, can obtain such curve, promptly the offset current that observes along center line is being zero outside the contact hole zone, has certain value in the zone that silicon exposes.The non-vanishing zone of offset current with expose at the bottom of the contact hole regional corresponding, therefore, by measuring the width that this distance can obtain the reality that silicon exposes, and can regard it as at the bottom of the contact hole diameter.

Fig. 7 is the figure that is used to illustrate to the mensuration of taper contact hole, and (a) expression is as the example of the structure of the contact hole of object and mensuration system thereof, (b) expression measurement result.Littler than contact hole peristome at the bottom of contact hole 44 its contact holes as determination object, its contact hole wall is coniform.Though can be described as coniformly, its inclination is precipitous, as long as the irradiation position of electron beam departs from the bottom of the contact hole a little, the thickness of dielectric film 41 just surpasses 1000  at once.On thick like this zone, do not produce offset current basically.The region generating offset current that at the bottom of contact hole, exposes, offset current is almost nil in zone in addition, and therefore, the distance of observing offset current is corresponding with diameter at the bottom of the contact hole.Like this, even if contact hole is the coniform distance that also can measure at the bottom of the contact hole.

Also have, the diameter of electron beam is limited, and offset current has rising edge and trailing edge.In the case, can obtain the diameter of contact hole from the rising edge of offset current and trailing edge or electric current zero all places information such as position of getting back to from saturated fully position to electric current.

Also have, can make electron beam pass dielectric film, under the mild situation in the inclination angle of forward circular cone, also do not produce offset current even if do not shine at electron beam under the state of contact hole bottom by means of the accelerating voltage of electron beam.Utilize this character, measure the three-dimensional structure that to obtain contact hole repeatedly by changing accelerating voltage.To be elaborated to this in the back.

Fig. 8 is illustrated in the variation of viewed contact hole offset current amount when changing the contact hole floor space under the condition on the whole bottom of uniform electron beam incident to a contact hole.Thus shown in the figure as can be known, offset current is directly proportional with the contact hole floor space.

Fig. 9 represents the variation of offset current amount with respect to the diameter (contact hole of conversion at the bottom of footpath) of hypothesis under the situation that at the bottom of the contact hole is circle.Because of square being directly proportional of area and diameter at the bottom of the contact hole, therefore, square being directly proportional of offset current and diameter at the bottom of the contact hole.

Figure 10, Figure 11 are the key diagram that has used the mensuration of the electron beam with size cross sectional shape bigger than contact hole peristome, and in figure separately, (a) expression is as the example of the structure of the contact hole of object and mensuration system thereof, (b) expression measurement result.In measuring, this uses the electron beam generating device of Fig. 1 or Fig. 2, the thickness of getting electron beam is the value more much bigger than contact hole (for example several microns square), determination object is carried out the vertical TBI of electron beam, make electron beam can shine on the whole bottom of a contact hole, measure offset current under these conditions.As electron beam source, the variation of its electron beam intensity profile is preferably in 1% in beam diameter.

When electron beam 51 was arrived the bottom of contact hole 43 or 44 by TBI, the offset current that produces on the exposed portions serve of underlay substrate 42 was all added up the back by galvanometer 9 instrumentations.The emission effciency of secondary electron is the intrinsic value of material, and therefore, under the identical situation of electron beam illuminate condition, the offset current amount in the zone that the expression substrate of average unit are exposes is certain.Therefore, make electron beam 51 TBIs under the situation of the whole bottom of contact hole 43 or 44, shown in Figure 10 (b), Figure 11 (b), like that, during irradiating electron beam, observing the offset current that is directly proportional with the floor space of contact hole 43 or 44.

(utilization of standard sample)

The compensation current that obtains like this may change knifeedge because of condition determination.So utilization standard value of resulting offset current under the situation that sample state is understood fully is converted to the contact hole area.That is to say, under the electron beam illuminate condition that certain provides, measured the offset current amount of the unit are of the known standard sample of contact hole floor space in advance, then, unknown sample is carried out same electron beam irradiation and obtains the offset current amount.The current value that obtains is tried to achieve ratio with respect to standard contact hole area divided by the offset current amount of standard sample, can obtain the contact hole floor space thus.The hypothesis that this offset current amount that is based on the unit are of standard sample equates with the offset current amount of the unit are of unknown sample.

Figure 12 is the key diagram that has used the same mensuration of the diameter bundle littler than contact hole diameter, and (a) expression is as the example of the structure of the contact hole of object and mensuration system thereof, (b) expression measurement result.Beam diameter than the little situation of the diameter of contact hole under, only on the position of being shone by electron beam, be compensated electric current.So, by the final current value integration that produces in the whole zone in the hole of scanography object and use and repay the same gimmick of the situation of electric current summation with above-mentioned supplement and can obtain contact aperture.Under the big situation of the time constant of current-flow test set, integrated value is roughly proportional with average current value, and therefore, the average current value that shows with galvanometer can estimate the aperture.

When the angle of the circular cone sidewall of forward hour, even if electron beam is under the state that is not irradiated to the contact hole bottom, the film thickness attenuation because of dielectric film also can produce offset current certainly.The condition that said method can be suitable for fully can be by the thickness of dielectric film, the intensity of electron beam, the decisions such as angle of circular cone.

The offset current amount of unit are is that material bottom exposing or accelerating voltage, the injection current amount of injecting electron beam change, therefore, under material or condition situation about measuring with other, to carry out necessary preliminary experiment in advance, obtain the relation of offset current and area and convert table or function to.

(directly measuring example at the bottom of the contact hole)

Present inventors have verified the reckoning in footpath at the bottom of the contact hole with the sample of actual trial-production.In this experiment, at first, made cylindric contact hole such shown in Figure 10 (a) in advance as standard sample.Peristome diameter, end diameter are 0.1 micron respectively, and the material that exposes at the bottom of the hole is a silicon, and the dielectric film that becomes the wall of contact hole is a silicon oxide layer.When the sub-beam accelerating voltage of power taking is 1kv and when electron beam injected contact hole, observed the offset current of 100pA.Secondly, split under the same condition that bore is identical, at the bottom of the contact hole the unknown contact hole in footpath promptly shown in Figure 11 (a) such contact hole measure.Detected the current value of about 50pA in unknown sample, hence one can see that, and the contact hole floor space of unknown sample is 0.5 times of standard state.

On the other hand, can observe the shape that (diminishing inspection) checks actual contact hole by the cross sectional shape of SEM.Diameter by the resulting standard sample of this cross-section is corresponding with compensation current can obtain the contact hole floor space from detected compensation current unknown sample by making in advance.Also have, if no matter its diameter of shape at the bottom of the hypothesis contact hole all is similar, the diameter of then determined contact hole can be tried to achieve according to the square root of area.

In above-mentioned experiment, obtained that diameter is 0.07 micron at the bottom of the determined contact hole.

Line can have only 1 time the scanning of the contact hole of mensuration, but in order to improve the mensuration precision, also can repeatedly scan the same area.In this case, the mean value of the offset current that can be observed when repeatedly scanning certain inspection area is calculated the contact hole diameter.

(determining of the offset current amount of the unit are of the situation of floor space the unknown)

Determine that the method for the offset current amount of unit are describes below with reference to Figure 12 to can't prepare the known standard sample of contact hole floor space the time.In the method, much thinner as and restraint the known electron beam 52 of spot size and impinge perpendicularly on the sample than the contact hole opening thickness.The beam spot size that method produced by Fig. 1 or Fig. 2 is located at the restriction that limit is restrainted the peristome size on the circle, therefore, can obtain the size of electron beam by calculating.In order further to improve accuracy, directly obtain beam diameter and as beam diameter with knife-edge method etc.When this electron beam was injected the standard contact hole, instrumentation was to such offset current shown in Figure 12 (b).By obtaining the offset current that obtains divided by the beam spot size offset current of the unit are of standard sample.

(application in producing factory in batches)

Whether qualified Figure 13 be illustrated in the flow chart of the situation of producing the mensuration of utilizing contact hole base diameter discussed above in the factory in batches and judgement example.

One of factor of the size of the contact hole magnitude of current that to be decision produce by contact hole.In high-speed memory or logical device, very Gao Su pulse signal with very delicate sequential working.The inconsistent meeting of contact hole size influences the time constant of circuit by contact resistance, and therefore, the burst transmissions time becomes different with design load, thereby causes circuit working undesired.Therefore, when contact hole size inhomogeneous surpasses certain limit, no matter do how conducting also will cause undesired on the circuit.So undesired in order to prevent, the footpath, the end of contact hole that must strict restriction manufacturing in producing factory in batches inhomogeneous.

For example, consider that it is the situation that target is made that manufacturing permissible error with 0.01 micron (± 10%) obtains at the bottom of the contact hole of 0.1 micron of diameter.10% permissible error of diameter converts with area and is equivalent to ± 20% area permissible error.Shown in the flow chart of Figure 13, like that, carry out restriction at the bottom of the contact hole with this benchmark.

At first, be radiated at electron beam on the contact hole that is present in the determined object on the wafer and measure offset current on each contact hole.This outcome record on memory or disk.So long as the medium that can write down, even if be not that memory or disk are also out of question.Secondly, the compensation current of the compensation current of measuring record and the qualified contact hole of expression is compared.Then, compare represented offset current and the fiducial value in each hole with comparator.If the difference of size is qualified and is this contact hole of expression that qualified information is recorded on the storage device with contact hole interior then that judge instrumentation ± 20% with respect to fiducial value.The value of the contact aperture that obtains for scanning on " 1 " to the position of " 5 " for " 1 " Y coordinate at the X coordinate and whether qualified result of determination example in Figure 13, have been write down.When the number of the defective contact hole on the entire wafer is put into the wafer apparatus of transport that is used to be transported to subsequent processing when certain fiducial value is following.On the other hand, when surpassing the fiducial value scope, the wafer of inspection object is judged as defective, and stops follow-up operation processing, and the wafer branch is put into the apparatus of transport that is used to adorn waste product, sends the indications such as adjustment of carrying out Etaching device simultaneously.

Because of obtaining the measured value in footpath at the bottom of each contact hole, therefore, can be by calculating statistic such as its deviation and mean value and the statistical value when no abnormal compares.Can before the actual generation of contact hole conduction problem, relatively analyze, therefore, can at length hold the fluctuation and the variation tendency of processing procedure this.Also have, in order to find substandard product early, can be by verifying underproof reason and handling the underproof generation that prevents subsequent product.

Its circuit scale of nearest semiconductor integrated circuit becomes huge, and the number of contact hole also increases with geometric progression thereupon.Under these circumstances, all contact holes are difficult on the mensuration wafer.On the other hand, a plurality of same elements (chip) are arranged on the wafer regularly.So, can judge from a chip to next chip scanning across chip whether each chip is qualified by the same position that will measure each chip.In the case, can once measure a plurality of contact holes on the scanning position of each chip and obtain the mean value in its footpath, end.Under the situation of the end of asking a plurality of contact holes mean value directly, both can enclose the single electron beam that is shaped by the limit bundle by TBI, also can scan thin electron beam.Under the situation of TBI electron beam, can repeatedly shine and get its mean value.Equally, under the situation of scanning beam, its scanning times both can be also can be repeatedly for 1 time.

(map demonstration)

Also have, also can with locate accordingly the mapable as a result that obtains by mensuration to the offset current of wafer or the diameter of contact hole etc.For example, by the diameter map of offset current or contact hole is turned to the distribution that the contour shape can be known the contact hole diameter in the wafer.This contour shows the value that can store the offset current that obtains earlier and positional information and is undertaken by showing on image display apparatus or record-paper etc.

Under situation about showing on the image display apparatus, if be that benchmark shows on picture with compensation current, opening diameter etc., then might be because of brightness too high or low excessively the becoming of brightness be difficult to see clearly.So, must revise and make display frame always to be in to this and be easy to discernible state.For example can consider being that benchmark is regulated brightness etc. as modification method with the central value.Also have, in semiconductor manufacturing process, being regarded as of substandard product is more important than qualified products, and therefore, the information relevant with substandard product preferably will make and be easy to see clearly.

(whether qualified judgement and the operation evaluation that shows based on map)

Whether qualified judgement can be classified according to the diameter of offset current, contact hole or the shape of contact hole.By to each wafer every a plurality of wafer is identical at etching condition, processing unit is identical or the processing unit phase equal conditions of prime operation under these types are classified can obtain various information.The most handy and contour shows that same method shows these grouped datas.Thus, can judge not only whether wafer is qualified, can also know the etch profile of etching machine and other treatment situation, can make the early detection of fault of processing unit and the optimization of treatment conditions become easy to the averaging such as etch quantity of etching machine etc.

For example, contact hole normally forms with the dryness etching method, its device be adjusted to etching speed on the whole surface of device for constant speed, still, however, also still keep away and unavoidably can produce fast place of etching speed and slow place.When comparison that the contour that a plurality of wafers is carried out to the measurement result of contact hole shows, can know the trend of the comprehensive distribution of this device, the device adjustment is carried out in inclination by for example changing electrode etc., make that these uneven distributions obtain revising, thereby can improve the uniformity of etching speed.

Can consider to have the various methods of obtaining the distribution of a plurality of wafers, for example, can only be collected in the distribution of carrying out etched wafer under the same operating condition, or wafer by the standardization different condition carries out.

As the reason that etching speed produce is distributed, the influence of thickness distribution of the dielectric film of operation is before this arranged also.The thickness distribution of dielectric film is that the state by the CVD device causes.Under these circumstances, carry out the reason that the data of the wafer of prime manufacturing process and etching work procedure can investigate a matter by collecting with same machine.By obtaining such data, can come the problem of the prime operation of specific this operation from the mensuration of judging the contact hole diameter that etching is whether qualified.

Also have, under the situation of the trend of knowing device, be not by checking wafer whole surface but by only the emphasis inspection is carried out in the place that is easy to generate problem can shorten minute.For example, can check by the part that only is determined at the place of distribute going up etching speed fast (compensation current height, opening diameter big) or etching speed slow (compensation current is low, opening diameter is little).

Except above-mentioned information, can also obtain useful information, the upward essential data of operations such as setting, adjustment be made that finishing these work at short notice becomes possibility by providing by these information in the adjustment after carrying out the new setting of device, maintenance, the exchanges such as affirmation after the repairing, distribution from contact aperture when repairing.The distribution of contact aperture also is useful as the maintenance information of device.For example, the increase by the underproof distribution of statistical ground monitoring and with the departing from and utilize inspection of foreign substance described later accurately to estimate of common distribution to the time of maintenance.Also had before problem produces can sniffer unusual effect.

Whether qualified in common operation, wafer is to be put to 1 group (claiming that this is " criticizing ") during semiconductor makes with multi-disc, therefore, for wafer judgement, also can only check first wafer and last wafer that is put to this batch in this operation.Under the situation of the state of learning first wafer check result in the hole, both can complete inspection be put to the follow-up wafer in this operation and when producing defective wafer, adjusted the machine of this operation, also can adjust the machine of this operation according to the result of first wafer.

(combining) with SEM

Contact hole is a D structure, therefore, if can access the open-and-shut check result of stereoscopic features then very convenient.Will be described later about the correct method of asking D structure, but the method for asking for structure is roughly described here fairly simplely.

Here in Shuo Ming the method, contact hole or through hole have circular cross section usually.Therefore, the particular bore peristome diameter α and end footpath β and depth d thereof can be represented the shape of the contact hole of determination object basically.That is to say, shape or the material information and synthetic measured by offset current at the bottom of the resulting contact hole by the resulting contact hole opening shape of common scanning.Material information is to utilize the offset current amount to be estimated from the offset current amount of measuring with several accelerating voltages because of the different character of the difference of backing material.The degree of depth about contact hole is measured and can be obtained by means of electron beam described later, but also can use the measured value of the thickness of being measured when the dielectric film that forms this contact hole forms.

Figure 14 and Figure 15 are the figure of explanation assay method, and Figure 14 represents to have the mensuration example of columned contact hole, and Figure 15 represents to have the mensuration example of the cone shape contact hole of forward.In each figure, what (a) relation, (c) expression of the irradiation position of the secondary electron amount measured along the contact hole center line as the structure of the contact hole of object and mensuration system thereof, (b) expression of expression and offset current and electron beam had recovered 3 ties up display graphics.For simplicity, only suppose along contact hole center line run-down here.

The parallel electron beam that obtains by Fig. 1 or device shown in Figure 2 as scanning contact hole around or its inner electron beam.When using the convergence electron beam,, must make electron-beam convergence on height separately under the situation of the peripheral region that scans contact hole and under the situation of its bottom of scanning.Relative therewith, if use parallel electron beam then the depth of focus is infinite, also can not carry out focal adjustments.

The size of its openings footpath of contact hole 43 shown in Figure 14 (a) α is big or small the same with footpath, end β basically.In the case, shown in Figure 14 (b), its rising of these 2 curves of secondary electron amount and offset current is consistent with down position.The depth d of measurement result and the contact hole that obtained by deal with data can obtain 3 dimension display graphics of cylindric contact hole such shown in Figure 14 (c) thus.Also have, make it the center by contact hole and measure a plurality of cross sectional shapes, then can obtain 3 dimension display graphics of more accurate contact hole if change the scanning direction.Can be the various methods of in the 3 dimension computer graphical worlds, using as the method that cross sectional shape is reduced to 3 dimension images.

The big or small ratio open footpath α of footpath β is little at the bottom of contact hole 44 contact holes shown in Figure 15 (a).In the case, shown in Figure 15 (b), between the rising of the rising of the curve that obtains by the secondary electron amount and decline shape and the curve that obtains by offset current and decline shape, produced difference.The width of rectangle region that expression is equivalent to the width of rectangle region of curve of secondary electron amount of the opening footpath α offset current more corresponding with footpath, end β than expression is big, and hence one can see that, and opening directly and at the bottom of the contact hole directly has difference.Show if add the depth d of the contact hole that obtains by deal with data and carry out 3 dimensions, check that then the shape of the contact hole of object is shown as inverted triangle taper such shown in Figure 15 (c).

Also have, under the situation of taper contact hole such shown in Figure 15 (a), according to the shape and the relation of the position between the secondary electron detector of this awl, the secondary electron that is penetrated by the tapering also may be detected.But the depth-width ratio of actual contact hole is very high, therefore, in fact, does not observe basically from the secondary electron of hole inwall.Among the figure below Figure 15 (b) reaches, if not special statement will be ignored such secondary electron.

The oblique incidence of line (combine and) with SEM

Under the situation of the contact hole of the big inverted cone-shaped of the width of the big or small ratio open portion of contact hole bottom, only can't distinguish with opening footpath with same diameter and end contact hole directly by vertical injection electron beam.So, tilt to make on peripheral part at the bottom of electron beam can arrive contact hole and the shape at the bottom of the instrumentation contact hole with respect to the incidence angle that is examined sample by making electron beam.In order to make the electron beam small angle inclination, the deflector that utilizes electron lens or electron beam scanning to use.In order to make the electron beam wide-angle tilt, be that sloping shaft makes wafer support platform to tilt with the center wafer axle.Support platform to tilt if make, the inclinations of ± tens degree can easily realize, therefore, can make electron beam to inject with the almost equal angle of the cone angle of contact hole.

Figure 16, Figure 17 and Figure 18 represent the electron beam that has tilted shine respectively cylindric, forward is coniform and the contact hole of inverted cone-shaped on the mensuration example.Among each figure, (a) relation of the irradiation position of the secondary electron amount measured along the contact hole center line as the structure of the contact hole of object and mensuration system thereof, (b) expression of expression and offset current and electron beam.To the secondary electron amount that inclination caused of electron beam locate and the locating of offset current between dislocation revise and make it corresponding with the position of contact hole.Also have 3 dimension display graphics that Figure 18 (c) expression has recovered.

When the electron beam 61 that has made moves and shines on the columned contact hole 43 along the contact hole central shaft, electron beam 61 be irradiated to contact hole 43 around the zone of dielectric film 41 on during, observe strong secondary electron 32.When electron beam 61 arrived the fringe region of contact hole 43, the intensity of secondary electron sharply reduced.Be irradiated at electron beam 61 contact hole 43 the bottom during, do not observe secondary electron basically.When electron beam 53 will be mapped on the dielectric film 41 of offside once more, secondary electron was detected again.On the other hand, electron beam 61 be irradiated on the dielectric film 41 during do not observe offset current, when electron beam 61 arrives the edge of contact holes 43, just begin and can detect.When electron beam 61 was irradiated on the bottom of contact hole 43, offset current sharply increased, and the magnitude of current sharply reduces again when electron beam 61 is irradiated on the dielectric film 41 once more.

In pyramid type contact hole 44, when being irradiated on the dielectric film 41, electron beam 61 observes strong secondary electron, and when electron beam 61 arrived the edge of contact hole 44, the secondary electron amount sharply reduced.Be irradiated at electron beam 61 contact hole 44 the bottom during, detect less than secondary electron basically.When electron beam 61 was irradiated on the dielectric film 41 in the outside of contact hole 44 once more, secondary electron was observed again.On the other hand, electron beam 61 be irradiated to contact hole 44 around dielectric film 41 on during detect less than offset current, be irradiated at electron beam 61 contact hole 44 the bottom during detect big offset current.Offset current sharply reduces again when electron beam 61 is irradiated to conus portion once more.

In the contact hole 45 of inverted cone-shaped shown in Figure 180, electron beam 61 be irradiated to contact hole 45 around dielectric film 41 on during observe strong secondary electron, when electron beam 61 arrived the edge of contact holes 45, the secondary electron amount sharply reduced.Be irradiated at electron beam 61 contact hole 45 the bottom during, detect less than secondary electron basically.Secondary electron is detected again when electron beam 61 begins to be irradiated on the surface of offside of contact hole 45.On the other hand, when electron beam 61 irradiation dielectric films 41 surperficial, detect less than offset current, offset current only electron beam 61 be irradiated to contact hole 45 the bottom during be detected, when electron beam 61 begins to be irradiated on dielectric film 41 or the rounding tapering once more offset current detect again less than.

When the circular cone of contact hole tilts when consistent with the inclination of incident beam, the minimizing of the increase of secondary electron amount or minimizing and offset current or be increased on the same line irradiation position produces.Therefore, for the footpath, the end of the contact hole of obtaining inverted cone-shaped, experimentize with the incidence angle of various electron beams, searching can detect the outermost angle of offset current.Because the depth d in hole is known, therefore, can obtain from the distance of the outside most peripheral at the bottom of the contact hole of peristome from the incident angle of electron beam and the degree of depth, by this value is added to peristome directly go up can calculate contact hole the end directly.When adding these information and carrying out to obtain 3 of the contact hole shown in Figure 18 (c) when 3 dimensions show and tie up figures.

(foreign matter detection)

Figure 19 is to be used to illustrate the figure that detects in the specific method of the inner foreign matter that produces of contact hole to Figure 21.In figure separately, (a) relation of the irradiation position of the structure of object and mensuration system, secondary electron amount that (b) expression is measured and offset current and electron beam is checked in expression.

On at the bottom of the contact hole, may have resist bits, particulate that produces when carrying out etching or the various foreign matters such as dust that in other processing procedures, produce.If these foreign matters exist, filled out tungsten in contact hole in order to conduct as plug or the filling of aluminium, polysilicon etc. becomes insufficient, cause poor electric contact.Therefore, in semiconductor processing process, must before forming, plug detect these foreign matters.

Because of though its thickness of debatable foreign matter is relevant with its material but generally more than 500 , this will influence irradiating electron beam and arrive the contact hole bottom.Therefore, if foreign matter is present at the bottom of the contact hole, its value of then observed offset current is littler than the offset current that produces on normal contact hole.

In the example of Figure 19 (a) and (b), have little dust 71 in the outside of columned contact hole 43.When make by the thin electron beam 31 that method produced of Fig. 1 or Fig. 2 from the left side of Figure 19 (a) when contact hole 43 vertically scans sample, electron beam 31 be irradiated to contact hole 43 around dielectric film 41 on during detect less than offset current, offset current just begins to be detected when electron beam 31 arrives the edge of contact holes 43.Be irradiated at electron beam 31 on the bottom of contact hole 43 during, offset current is detected, if but electron beam 31 be irradiated on the dust 71, then become and detect less than offset current.In the example of Figure 19 (a), dust 71 concentrates on an end at the end of contact hole 43, if but be present in central area, then when electron beam 31 was crossed the dust district, offset current can be observed again.The irradiation position of corresponding electron beam 31 is measured the variation of offset current, obtains the such result of Figure 19 (b).Measurement result by this result and free from dust the time compares the size that can obtain dust 71.Like this, at the bottom of can learning contact hole, offset current whether have dust maybe can obtain the size of dust by measuring.

Figure 20 (a) and (b) are illustrated in the example that deposits the situation of dust 72 at the end of cone shape contact hole 44.Begin under the scan condition of electron beam 31 in left side from Figure 20 (a), electron beam 31 be irradiated to contact hole 44 around dielectric film 41 on during detect less than offset current.Because of the thickness of insulator is thick, therefore, be irradiated on the tapering during also detect less than offset current.On the other hand, when electron beam 31 will be irradiated to the bottom of contact hole 44, offset current was detected.During coming out, can detect the offset current of size from the bottom, but when electron beam 31 be irradiated on the zone that dust 72 exists during detect less than offset current.Whether compare to investigate by the curve with the sample of free from dust has dust to exist maybe can to learn its size.

The central part that Figure 21 (a) and (b) are illustrated in the contact hole 45 of inverted cone-shaped has the situation of dust 73.When scanning beam 31, electron beam 31 be irradiated to contact hole 44 around dielectric film 41 on during detect less than offset current.When electron beam 31 arrived the edge of contact holes 45, offset current just began to be observed, be irradiated at electron beam 31 on the bottom of contact hole 45 during, big offset current is detected.When irradiation shines dust 73, detect less than offset current.When electron beam 31 shone the end of contact hole 45 once more by dust 73, offset current was detected again.When electron beam 31 arrives the offside edge of contact hole 45, detect less than offset current again.Offset current detect less than position and dust 73 exist regional corresponding, the size of width estimation dust 73 thus.

In above dust detection method, it is different because of material that secondary electron penetrates ratio, and its size is different because of the atom sequence number to the interdependence of the energy of irradiating electron beam.Therefore, after whether dust being arranged at the bottom of the specific contact hole, irradiation has the electron beam of various acceleration energies and observes the variation of offset current.In advance imaginary foreign matter is carried out same experiment and determines the interdependence of good offset current to acceleration energy in advance, can the particular assay object by utilizing technology such as neural net to obtain the degree of approximation of this interdependence.

(based on the mensuration of the big electron beam of cross sectional shape)

Figure 22 is the figure that expression has utilized the mensuration example of the big electron beam of cross sectional shape, and (a) vertical view, (b) for the relation of the position between expression contact hole 81 and the electron beam 82 is that cutaway view, (c) represent with respect to resulting offset current of the scanning position of electron beam and differential value thereof.

In this example, cross sectional shape is a rectangle, and usable floor area incides electron beam 82 on the sample greatly and vertically than the size of a contact hole.Shown in Figure 22 (a) and (b), scan such electron beam 82 from the side in the zone that comprises a contact hole 81 towards the opposing party and keep irradiation axis perpendicular to sample and the line axle is not rotated.This scanning both can be scanning beam 82 self, also can fix the irradiation axis of electron beam 82 and make wafer-level to move at a certain angle with respect to sample.Here used electron beam 82 is a parallel beam, even if but such parallel beam also can make parallel the moving of line scan line by utilizing 2 deflectors.This moment, the size of detected offset current was directly proportional with the electron beam area at the end that is irradiated to contact hole 81.Therefore, be illustrated in will be by near the locational offset current the line edge 83 of rectangular electron beam 82 irradiations for its differential value.

Shown in Figure 22 (a) and (b), in this example, make electron beam 82 begin to shine at leisure the enterprising line scanning in the end of contact hole 81 from the zone around the contact hole 81.During the zone around the electron beam 82 irradiation contact holes 81, detect less than offset current.When electron beam 82 was irradiated to position at the end of contact hole 81, offset current sharply increased.Electron beam 82 by the process at the end of contact hole 81 in offset current become gradually greatly, reach maximum all comprising contact hole 81 parts.When electron beam 82 was come contact hole 81 by the line edge of contact hole 81 and opposite side, offset current began to reduce, and had just detected less than offset current in the time of on electron beam 82 shines less than the zone of contact hole 81.

Distance between the peaked summit of the lifting position of determined offset current and expression offset current is corresponding with the distance from the end to end at the end of contact hole 81.Therefore the distance measured of method, can accurately not measure diameter of a circle even if do not make electron beam 82 accurately aim at contact hole 81 with clamp the resulting distance of bowlder with 2 parallel lines suitable yet thus.

Also have, if hypothesis contact hole 81 is circular, then Yuan area increment rate is maximum in the centerline of circle, and therefore, the position that becomes offset current increment rate maximum is suitable with the position of the center line of circle.Thus, even if all do not scan contact hole 81, also can be by the position that becomes offset current increment rate maximum being measured the footpath, the end of obtaining contact hole 81.Promptly just can measure footpath at the bottom of the contact hole with the only about half of time.Also have, differential value clearly illustrates the position on summit, therefore, can accurately obtain distance.

Compare with the situation of using thin electron beam, the advantage of using thick electron beam is that the formation of electron beam system of testing fixture is simpler.

(making up the mensuration of thin electron beam and thick electron beam)

Figure 23 and Figure 24 are used to illustrate that combination is based on the high survey long pattern of the mensuration precision of thin electron beam with obtain the figure of the assay method of the overall mode determination in footpath at the bottom of the contact hole at short notice with thick electron beam, Figure 23 represents flow chart, and Figure 24 represents a survey long pattern target area 92 on the wafer 91 and an example of the position relation between the overall mode determination target area 93.

Footpath at the bottom of in the manufacturing of semiconductor device, must measuring contact hole quickly and accurately.In general, a contact hole is being carried out accurate thin electron beam scanning and at the bottom of the measuring space contact hole of its offset current quantitative change position the survey long pattern in footpath, because of the relative variation of using compensation electric current, the delicate uneven influence on the substrate is little, the mensuration precision height of contact aperture.But,, therefore, just need long time and lot of data to handle for a lot of contact holes are checked owing to will carry out accurate thin electron beam scanning and obtain a lot of information to a contact hole.

So, measure the overall mode determination of contact aperture and make up the survey long pattern of measuring the high thin electron beam of scanning of precision with by flow through offset current at the bottom of the whole contact hole with thick electron beam mensuration.Thus, can keep high inspection precision, and make inspection speed rapid.

Below with reference to Figure 23 and Figure 24 concrete example is described.At first, to carrying out accurately directly measuring at the bottom of the contact hole with the survey long pattern as 1 among the contact hole of determined object or less (surveying long pattern target area 92) contact hole.Secondly, overall mode determination is applied to same contact hole, and obtains at the bottom of the offset current that flows through at the bottom of the contact hole and the contact hole relation directly, and carry out the standardization of the area in the overall mode determination.Measure the contact aperture to determine in the determination object and the relation of offset current thus.Then, overall mode determination is applied to the contact hole in other (body measurement schema object districts 93) and measures offset current, the offset current that records is converted to contact hole floor space or diameter according to the relation in footpath at the bottom of offset current of obtaining previously and the contact hole with respect to each contact hole.Thus, can measure footpath at the bottom of the contact hole apace with the high assay precision.

(audits by comparison in two zones)

Figure 25 represents in order to utilize 2 to be examined the device configuration example that sample compares inspection.Figure 26 represents this inspection flow process.Also have, Figure 27 is the figure of the principle of explanation audit by comparison.Figure 28 is its enlarged drawing.

The circuit apperance of semiconductor LSI is to utilize a kind of exposure device that is called stepper to make, and therefore, the interval of adjacent chips or the layout of chip internal are accurately identical.Describe such as reference Figure 27 and Figure 28, first what be examined sample 101 is initial point (0 with the angle, 0) and the layout of the chip internal of representing with relative coordinate with on same chip second what be examined sample 102 is that the layout of the represented chip internal of initial point (0,0) is accurately consistent with the angle.Both are compared, if conclude that difference surpasses certain benchmark then can think that this zone contains malformation.By using such inspection, no matter the configuration status of wiring needn't learn that the layout information of sample for reference also can the abnormal position of specific wiring from cad data.Also have, first, second be examined sample 101,102 for be formed on the same substrate finally will be as a zone that chip is cut.

As shown in figure 25, the device that is used to compare inspection possesses to have and makes electron beam vertically shine electron gun 112 on the sample for reference on the wafer 111, be adapted to the offset current that is connected with the end of wafer 111 and measure the electrode 113 of usefulness, the XY that determines to be contained in wafer 111 on this electrode 113 and the position between irradiating electron beam relation supports platform 114, accurately measure the electron beam irradiation position checkout gear 115 of the position of being shone by electron beam, be used for electron beam irradiation position control device 116 according to the generation control signal of the irradiation position of the testing result controlling electron beam of this electron beam irradiation position checkout gear 115, control the electron gun control device 117 of electron gun 112 according to the control signal of these electron beam irradiation position control device 116 outputs, support the support platform controller 118 of platform 114 according to the control signal control XY of these electron beam irradiation position control device 116 outputs, the current amplifier 119 of the electric current of magnifying electrode 113, the output of current amplifier 119 is converted to the D/A converter 120 of digital signal, digital signal first and second storage device 121 and 122 as the current waveform storage corresponding with position coordinates, the waveform comparison means 123 of more stored current waveform, judge the defective judgment means 124 of the quality of wiring according to comparative result, record the judgement database 125 of the information that is used to judge, be used for the defective locations storage device 126 of storage defect position and show or print this defective locations or this defective locations is outputed to defective locations output device 127 on other processing unit on the network.Can be used as electron beam irradiation position checkout gear 125 to for example optical profile type Precise Distance determinator.

Storage device 121 and 122 is stored the current waveform corresponding with each chip respectively, though be expressed as other memory in Figure 25, these can be used as public storage device.Also have,, in Figure 25, be expressed as other device, but can use other storage area with storage device 121 and 122 same devices for defective locations storage device 126.

Defective locations storage device 126 can be as required to defect system and be with the classification record position information.

The scanning of electron beam can be undertaken by being fixed on electron gun 112 on the certain location in advance and making XY support platform 114 to move with respect to the position of electron gun 112.Support the position of platform 114 accurately to measure the position of being shone by electron beam by measuring XY with the precision of 100  by electron beam irradiation position checkout gear 115.Be examined sample 101 at electron beam with respect to first of wafer 111 and be carried out wire scan period, by means of current amplifier 119 and D/A converter 120 measuring as first current waveform at the electric current that produces on this sample, forming 1 group record to first storage device 121 with the first electron beam irradiation position coordinate of calculating from the position of XY support platform 114.Second of same apperance formation place that is in other chip is examined sample 102 also carries out same mensuration, obtain second current waveform, and form 1 group record to second storage device 122 with the second electron beam irradiation position coordinate.Judge the apperance defective and record on the defective locations storage device 125 from the difference that is stored in the current waveform on first and second storage device 121,122 by defective judgment means 124.When needed, can from defective locations output device 127 output on the network other the device on, make it to be used for display, printer or other analyses.

Different with the situation of using secondary electron, under the situation of the mensuration of having used offset current, the electron beam that is irradiated to outside the wiring region does not produce effective electric current, therefore, compare with the situation with secondary electron, the noise that is included in the signal that is detected is littler.

When qualified chip and defective chip being compared can be different because of the capacity of the storage device that is used for waveform storage device 121,122.Under the situation about qualified and defective chip being compared in every provisional capital, as long as it is just enough to write down the memory capacity of waveform of 1 row.After having measured 1 qualified chip, measure again under the situation of defective chip, only need be able to store the memory capacity of all information of 1 chip share.In order there to be between the chip of distance physically mobile electron bundle irradiation position need spend for a long time, therefore, in order to improve inspection speed, be preferably in the mensuration that 1 mensuration is finished to carry out afterwards again next chip, therefore, the most handy capacity big storage device of trying one's best.

Figure 29 checks routine figure for expression, (a) the mensuration example of the mensuration example of expression qualified chip, the defective chip of (b) expression.The row of the numeral stripscan electron beam in the left side of figure number, the W on right side are represented the width of the electron beam of 1 scanning.Also has the offset current that when the downside of Figure 29 (a) and (b) is illustrated in the electron beam scanning that carries out 4th row related with the apperance defective, observes.In this example, as on common semiconductor device, seeing, suppose that the size of checking the object wiring is certain (for example 0.15 μ m).In general, semiconductor device is subjected to the restriction of exposure technology and etching technique etc., and the interval of wiring and wiring is bigger than the diameter of wiring.In this example, wiring is a random alignment, does not have certain cycle.

Chip shown in Figure 29 (a) and (b) has with reference to Figure 27,28 illustrated character, selects arbitrarily from be formed at a plurality of chips on the semiconductor wafer simultaneously.Different the object which chip is measured as a comparison because of situation, but in general adjacent chips or the specific chip of getting qualified product easily be appointed as first and be examined sample, substitute second then successively and be examined sample inspection.The check result of the chip more than 3 relatively, can identical check result many be judged as qualified product.

Having utilized electron beam is to utilize the variation of the size of current that produces when the irradiating electron beam or polarity to the judgement of the quality of wiring.For the sake of simplicity, hypothesis is owing to exist the apperance defective in underproof wiring here, compares with the situation of qualified wiring, and the electric current that underproof wiring observes is wanted much less.

Below concrete inspection method is described.At first, the position coordinates that makes the chip that becomes sample for reference is consistent with the position coordinates that is used to carry out the electron beam irradiation.Therefore the wiring size of most advanced device that becomes sample for reference, aim at the higher positional precision of ratio 1000  that is enough to reproduce this position coordinates below 0.2 μ m.For this reason, need to utilize the alignment mark that is formed on the wafer.

Utilize the method for alignment mark to have several.One of them is a method of utilizing the alignment mark that is used for mask alignment that is used usually in semiconductor technology.This alignment mark is made by oxide-film, metal film etc., is formed on the surface of substrate, therefore, can utilize the flying-spot microscope that is located at testing fixture inside to be converted to secondary electron image.The position of seeing on the image is by the position of the correct irradiation of electron beam, therefore, and be the position of alignment mark as initial point and make it consistent with the position coordinates of electron-beam scanning system.

Other method as not using flying-spot microscope has the method that is determined at the electric current on the alignment mark.Make in addition with the same wiring shape sample of sample for reference as alignment mark.The size of wiring can be with the wiring of sample for reference big or small the same, in order to improve the mensuration precision, also can use littler.The same with the measuring principle of wiring, during the place that electron beam irradiation wiring is thought, the electric current that observes is little, and when electron beam was irradiated on the position of wiring, electric current increased.When the electron beam irradiation position was consistent with alignment mark, it is maximum that the electric current that observes reaches, and therefore, can utilize this position as aligned position.

After aim at finishing,, make the size wire electron beam 131 suitable follow " 1 " and vertically from left to right scan on the sample for reference surface with wiring width for forming first zone that is examined sample 132.When scanning the end of inspection area, on the direction vertical, make the irradiation position of electron beam 131 move width W, and then follow the scanning that " 2 " carry out electron beam 131 with the scanning direction.The direction of scanning can be s font or meander shape, also can get back to from left to right scanning again behind the initial position.The mobile width W of vertical direction roughly gets the width of wiring.Follow " 3 ", " 4 ", " 5 ", " 6 " equally, " 7 " are scanned, and make scanning spread all over whole sample for reference.

Shown in Figure 29 (a) and (b), along in the scanning of the 4th row, coming when the electron beam scanning position has electric current to be observed when being equivalent to connect up 132 position in the qualified product, but does not observe electric current in the wiring 133 of defective item.That is to say that qualified product and defective item produce the difference of current waveform on the position of apperance defective 134, hence one can see that exists defective.

In above inspection method, even if the cloth line position of sample for reference is unknown, position that also can specific defective wiring.

(based on the audit by comparison of thin electron beam)

Thin electron beam example has been used in other example expressions that Figure 30 checks as a comparison, (a) the mensuration example of the mensuration example of expression qualified chip, the defective chip of (b) expression.The row of the numeral electron beam in the left side of figure number.Also has the offset current that the downside of Figure 30 observes when being illustrated in the electron beam scanning that carries out the 4th row related with the apperance defective.

Measuring under the situation of offset current, when the material of wiring is even, having such character, promptly no matter electron beam be irradiated to wiring which partly go up the electric current that can obtain identical unit are.Therefore, for wiring being carried out quality inspection, not necessarily leave no choice but the electron beam irradiation is all carried out in whole wirings.Also have, the apperance defective produces from apperance peripheral part, and therefore, if the set positions of electron beam irradiation peripheral part in wiring, then flaw detection sensitivity will improve.On the contrary, if electron beam is set to the center that is radiated at wiring, then flaw detection sensitivity reduces.In the example of Figure 30, use than wiring width thin the point-like parallel electron beam 141 of Duoing, scan with the sweep spacing suitable with wiring width.

This checks also the same with the inspection shown in Figure 29 device shown in Figure 25 that uses, and can check according to inspection flow process shown in Figure 26.Here, suppose electron gun 112 can produce width than wiring width thin the point-like parallel electron beam of Duoing.

In this checks, inspection the same aim at illustrated with reference Figure 29, for be formed with first zone that is examined sample 142, make have size than wiring width much smaller electron beam 141 follow " 1 " and vertically incide the line scanning of going forward side by side on the sample for reference surface.As mentioned above, the electron beam irradiation position is influential to flaw detection sensitivity, therefore, under the situation that will improve sensitivity, can set scanning beam and make it marginal portion, under the situation of desensitization, can set scanning beam and make it core by wiring by line.When scanning the end of inspection area, on the direction vertical, make the irradiation position of the electron beam sweep spacing L that staggers, and then follow the scanning that " 2 " carry out electron beam with the scanning direction.The direction of scanning can be the s font, scans in the same direction after also can getting back to initial position again.Sweep spacing L roughly gets the size of the width of wiring.Follow " 3 ", " 4 ", " 5 ", " 6 " equally, " 7 " are scanned, and make scanning spread all over whole sample for reference.Second sample for reference to same apperance formation place that is in other chip also carries out above mensuration, and stores separately current waveform accordingly with the irradiation position coordinate of electron beam.

In the example of Figure 28 (a) and (b), in the scanning of the 4th row, when scanning, electron beam 141 have offset current to be observed when being equivalent to connect up 142 position in the qualified product, but when the wiring 143 of scanned defective item, do not observe offset current, can detect the pattern defective 143 of wiring by detecting this difference.

(based on the audit by comparison of wire electron beam)

Figure 31 is radiated at figure in a plurality of wirings that set at random, (a) the mensuration example of the mensuration example of expression qualified chip, the defective chip of (b) expression to the wire electron beam for being used to illustrate simultaneously of other examples of checking as a comparison.Here it is shaped as wire used electron beam, and is very thin on the scanning direction, such as 100 , has several microns long on the direction vertical with the scanning direction, can comprise a plurality of wirings.The irradiation magnitude of current of electron beam 165 is pacified to several peaces of receiving from several micromicros, accelerating voltage from hundreds of to several kilovolts.

In the qualified samples shown in Figure 31 (a), when electron beam 151 when position a wants inswept wiring 152, electric current begins to produce.Also have, when electron beam 151 in-position b, the scope of the wiring 152 of being shone by electron beam 151 increases, and therefore, produces bigger electric current.When electron beam 151 in-position c, the scope of the wiring 152 of being shone by electron beam 151 reduces, and electric current also reduces.When electron beam 151 in-position d, do not connect up and shone by electron beam 151, therefore, electric current is zero.On the other hand, in the failed test sample shown in Figure 31 (b), 154 current values that obtain are little from connecting up, by relatively qualified product and defective item being formed with 2 current waveforms obtaining on the position of same pattern as can be known, because of pattern defective 156 causes the waveform difference.On the other hand, on the position e, the f that are formed with qualified cloth 153,155, g, h, qualified product and defective item both sides' chip obtains identical current waveform.

Like this, under the situation of a plurality of wirings being carried out the electron beam irradiation, when the wiring location dislocation, each electric current of being produced of wiring is determined independently with respect to locating, produce big difference on the current waveform of qualified chip and defective chip, can detect the problem of wiring by current waveform relatively.

This inspection and Figure 29, inspection shown in Figure 30 be the same can be used device shown in Figure 25 and check according to inspection flow process shown in Figure 26.Here, suppose that electron gun 112 can produce the wire electron beam.

Figure 32 is used to illustrate the figure that is routed in the inspection example that vertically has identical shaped situation, (a) the mensuration example of the mensuration example of expression qualified chip, the defective chip of (b) expression.The electron beam of irradiation is the wire electron beam, and size has 100  degree on the scanning direction, at the width that laterally has several microns.

The value of the summation of the electric current that each wiring that the current value that is recorded by the galvanometry as measuring principle of the present invention is shone is simultaneously produced.That is to say that the total electricity of the current value that is produced is determined by the wire electron beam under thin electron beam is irradiated to situation on each wiring portion.

In the example of Figure 32 (a) and (b), when electron beam 161 arrived position b by position a, no matter be qualified product or defective item, the identical electric currents that produced by wiring 162,164 were observed respectively.Relative therewith, when electron beam 161 arrived position d by position c, with being compared by wiring 163 electric currents that produced of observing in qualified product, what observe in defective item was less by wiring 165 electric currents that produced.Therefore, produce the difference of big current waveform, detect the existence of pattern defective 166.That is to say, even if the position of wiring with respect to the overlapping situation of the scanning of electron beam under, also can carry out the specific of the detection of defective and defective locations with the inspection flow process of the device of Figure 25 and Figure 26.

Figure 33 is the figure that is used to illustrate the inspection example of the situation that has the different wiring of wiring width axisymmetrically, (a) the mensuration example of the mensuration example of expression qualified product, (b) expression defective item.Check at this and to use in example and the same wire electron beam of inspection shown in Figure 32 example, be determined at the total electricity that thin electron beam is shone the current value that is produced under the situation on each wiring portion.

In the qualified samples shown in Figure 33 (a), when wanting inswept position a, electron beam 171 obtains the electric currents that produce by wiring 172, relative therewith, in the defective item shown in Figure 33 (b), there is pattern defective 174 because of connecting up on 173, even if electron beam 171 wants inswept position a also not observe electric current, on current waveform, create a difference.On the b of position also because the current waveform that exists pattern defective 174 to cause in defective item to be observed is littler than the situation of qualified product.Like this, under the situation that has the different wiring of wiring width axisymmetrically, because of between qualified chip and defective chip, producing the difference of waveform, can detect defective even if these wirings are checked also simultaneously.

The figure of the inspection example of the situation that Figure 34 exists brokenly for expression width different wiring, (a) the mensuration example of the mensuration example of expression qualified product, (b) expression defective item.When scanning, in the wiring 183 of the wiring 182 of qualified chip and defective chip, the current change quantity difference on the position b of pattern defective 184 is arranged with wire electron beam 181.Can detect defective by detecting this difference.

(based on the comparison of the current waveform of integration)

In the above description, be the situation that electron beam is radiated at resulting current waveform on the sample that example is illustrated with direct comparison.In order to compare current waveform, it is also conceivable that various methods in addition.

Figure 35 represents the configuration example of testing fixture that current waveform is compared by its integrated value, and Figure 36 represents that it checks flow process.This testing fixture possesses the waveform comparison means 123 that has pip integrator 191,192 and integrated value comparison means 193 to replace device shown in Figure 25, obtain the integrated value of the current value that pulse produced of 1 current waveform obtaining corresponding to the cloth ray examination by pip integrator 191,192, and on integrated value comparison means 193, these integrated values are compared.

(based on the comparison of the current value of unit are)

In audit by comparison,, check that the electron beam that is utilized needn't leave no choice but be irradiated onto in the wiring fully because of not utilizing the position coordinates of CAD etc.So, can be benchmark with the current value of unit are.

Figure 37 represents to compare by the current value of average unit are the configuration example of the testing fixture of inspection, and Figure 38 represents its inspection flow process.This testing fixture possesses storage device 201 is arranged, pip integrator 202, pulse-width detector 202, devision device 204 and storage device 205 replace in the formation shown in Figure 25 storage device 121,122 and waveform comparison means 123.The current waveform of being measured is stored on the storage device 201,202 pairs of pip integrators belong to stored current waveform a pulse from the rising edge to the trailing edge till the magnitude of current that flows through carry out integration, obtain the total electricity that 1 impulse duration flows through.Pulse-width detector 203 is obtained the cross-section distance of wiring from the pulse duration that is stored in the current waveform on the storage device 201.204 total electricity of being tried to achieve by pip integrator 202 of devision device are divided by the cross-section distance of the wiring of being tried to achieve by pulse-width detector 203.The current value that flows through on the unit are that can obtain haveing nothing to do with wiring width according to this division.Defective judgment means 124 is by comparing and according to its big or small difference judgement qualified product and defective item being judged by devision device 204 resulting values and being stored in of trying to achieve in advance with the fiducial value on the database 125.

Figure 39 is used to illustrate electron beam to the coverage rate of wiring and the figure of the relation between the current waveform, and (a) the expression electron beam passes through the example of the coverage rate 100% of a wiring, the example that half regional coverage rate 50% is passed through in figure (b) expression fully.In the time of in wiring 212 is completely contained in as the electron beam scanning band 211 of electron beam scanning scope, each scanning can both obtain same current waveform.Relative therewith, when electron beam scanning band 211 is staggered in wiring 212, in the scanning that has, may obtain current waveform by wiring 212, in other scanning, may can not get.But the magnitude of current that flows through the unit are of qualified contact layout is certain, can judge quality by this magnitude of current relatively.

Here the used fiducial value that is used for determining defects is the magnitude of current of the unit are of the qualified wiring of expression.Therefore, can utilize the represented value of the chip wiring of other wafers that passed through same operation or by the resulting data of test pattern or the value of back supposition such as simulating as this fiducial value.Effective when being used to that qualification rate from fiducial value wafer inside at the beginning of process exploitation of other wafer is very low.

(the comparison in producing factory in batches) based on the current value of unit are

Figure 40 represents in order to use a plurality of chips on same substrate to compare the configuration example of the testing fixture of inspection.Figure 41 represents its inspection flow process.This testing fixture possesses the dual system that has with the same circuit of storage device shown in Figure 37 201, pip integrator 202, pulse-width detector 203, devision device 204 and storage device 205, promptly possess storage device 221,231 arranged, pip integrator 222,232, pulse-width detector 223,233, devision device 224,234 and storage device 225,235, also possess to have and carry out the division arithmetic device 236 of division arithmetic to being stored in value on the storage device 225,235, this point is different with device formation shown in Figure 37.

The device of this device for utilizing in producing more stable batch process factory compares inspection with a plurality of chips on the same substrate.Promptly, electron beam is radiated at first is examined that resulting current waveform is stored on the storage device 221 on the sample, belong to by 222 pairs of pip integrators the current waveform of being measured a pulse from the rising edge to the trailing edge till the magnitude of current that flows through carry out integration and obtain the total electricity that 1 impulse duration flows through.Obtain and the cross-section equidistant rising edge from impulse waveform that connects up width till the trailing edge by pulse-width detector 223, the total electricity of trying to achieve by pip integrator 222 divided by the pulse duration of trying to achieve by pulse-width detector 223 obtain with the irrelevant unit are of wiring width on the magnitude of current that flows through.This magnitude of current is stored on the storage device 225.Be examined sample to second and also carry out same inspection, and the magnitude of current of the unit are that obtains is stored on the storage device 235.Value with 236 pairs of storage devices of division arithmetic device 225,235 is carried out division arithmetic, with defective judgment means 124 be recorded in advance to be stored in and judge and to compare with the fiducial value on the database 125.This fiducial value has defined the difference degree that allows between the chip.If comparative result is big, then illustrate on this position to have defective.

(rising edge of current waveform and the comparison of trailing edge)

Figure 42 represents to judge the inspection flow process that wiring is whether qualified according to the rising edge of obtained current waveform and trailing edge.In this checks, the quality of utilizing the corresponding property determination in edge of rising edge in the current waveform and trailing edge and wiring pattern to connect up.That is to say, scan the cloth line position that first sample for reference is obtained current waveform and determined first sample for reference.Then, scan the cloth line position that second sample for reference is obtained current waveform and determined second sample for reference.The rising edge by two waveforms relatively and the difference of trailing edge are learnt the deviation of cloth line position.When this position deviation surpasses certain value, judge this wiring defective and this location storage on storage device.

Figure 43 checks routine figure for expression, and (a) expression qualified product, figure (b) represent defective item.Wiring 241 periodically is formed in qualified product, and is corresponding, periodically records the rising edge and the trailing edge of current waveform on electron beam irradiation position T1～T8.Relative therewith, in defective item, the rising edge position of T3 and the position of departing from the qualified product.

Figure 44 represents that the center by the rising edge of current waveform and trailing edge judges the inspection flow process that wiring is whether qualified.In this checks, scan first sample for reference and obtain current waveform, calculate rising edge and the centre coordinate of trailing edge position coordinates and the center of specific wiring of the pulse in this current waveform.Equally, scan second sample for reference and obtain current waveform, calculate rising edge and the centre coordinate of trailing edge position coordinates and the center of specific wiring of the pulse in this current waveform.Both wiring centers relatively if poor more than the certain value occur on this result, then are stored in a side wiring center wherein on the storage device at least.

(subscan of electron beam)

Figure 45 is illustrated in the device configuration example that under the situation of utilizing thin electron beam to check inspection speed is improved tremendously.In this configuration example, possessing has the subscan that makes the electron beam deflecting with arrangement for deflecting 251, makes the main scanning that wafer position moves except support platform 114 by XY, also carries out simultaneously based on the subscan of subscan with arrangement for deflecting 251.

Main scanning is to support the mobile of platform 114 to carry out by XY, with present technology be difficult to the velocity-stabilization that surpasses 1m/ second move.Therefore, even if the processing speed of galvanometric system is very high, also cause the upper limit of the speed of checking to determine at last by beam scan velocity.So, when carrying out main scanning, on the direction vertical, carry out the high speed subscan with main scanning direction, make sweep speed substantially be improved.Subscan is undertaken by the electron beam deflecting, therefore, supports fast several ten thousand times of the translational speed of platform 114 than XY.

Under the situation of little subscan distance, the incidence angle of electron beam is actually vertical, to checking not influence, therefore, utilizes common beam deflector.Under the situation of the subscan of carrying out large amplitude, utilize to make the parallel mobile line phase shifter of line.

Figure 46 represents an example of track while scan.When main scanning 262 be traveling in lentamente with respect to wiring 251 on certain direction during, simultaneously carry out the subscan 263 that comes and goes at a high speed with certain width.Subscan 263 scans with the spaced and parallel ground suitable with the width of determination object.Like this, just with the speed that the speed of subscan is combined in main scanning on the same speed of speed scan, inspection speed is improved tremendously.

(high speed of the inspection of array region)

Figure 47 represents to make the inspection flow process of the inspection high speed of array area.In SOC device etc., have random logic district and array area, in this zone, uniformly-spaced be equipped with to long distance the contact layout of memory etc.Need not from sample for reference, to extract such array area automatically out, and check this part with the distinctive other high speed gimmick of array from the array information of CAD etc.For this reason, at first check initial chip and obtain the current waveform of complete inspection subject area.Secondly, detect the position that appears at the wiring on the scanning direction and store from the rising edge of current waveform and trailing edge.Then, in every specific interval (for example tens to the hundreds of micron) spatial distribution of the position of wiring is carried out spectrum analysis.

Figure 48 represents an example of the power spectrum that obtains by spectrum analysis.The position interdependence is arranged on this power spectrum.The correlation that high-power zone is equivalent to current waveform is strong, detects on this zone to have array.On the contrary, the zone that correlation is little is considered to the random logic district.

For detected like this array part, electron beam is radiated at simultaneously totally obtains defective ratio in a plurality of wirings.Make the inspection high speed thus.

(mensuration of 3D shape)

According to the present invention, not only can measure the diameter at the bottom of the hole, can also measure the 3D shape in hole.That is to say, utilize because of the accelerating voltage that changes electron beam and change the electron beam intensity that the inclination angle caused on being irradiated onto at the bottom of the hole of wafer and the variation of distribution.Be explained with reference to Figure 49, Figure 50.Under the low situation of the accelerating voltage of 510 electron beam at the bottom of the irradiation hole, as shown in figure 49, electronics is worn only dielectric film 512 basically, except the bottom in hole 510 is the part exposed of wafer 511, to measuring not contribution of electric current.If improve the accelerating voltage of irradiating electron beam, as shown in figure 50, electronics can pass the dielectric film 512 on every side at the end in hole 510, and the current value of being measured can change.Can measure the thickness of bore edges or dielectric film by utilizing this character.

The shape in Figure 49 and hole shown in Figure 50 is upwards to enlarge, but also can obtain same measurement result under such downward condition of enlarged shown in Figure 51 and Figure 52.In the case, the shape that only can't distinguish the hole by this mensuration be upwards enlarge or enlarge downwards.So shown in Figure 53 and Figure 54, the inclination angle that changes wafer is also measured repeatedly.The shape that can distinguish the hole with the variation of angle from the current strength distribution of detected wafer is that upwards enlarge or downward expansion.

In order to obtain the 3D shape in hole, to obtain the electron beam absorption coefficient in advance to each material that constitutes determined sample and keep with respect to the interdependence of the accelerating voltage of electron beam and as database.

Can consider with Fourier transformation method, the method for successive approximation and overlapping integration method as from the current value measured with the image reconstruction 3D shape.With reference to Figure 55 to Figure 58 wherein the method for successive approximation is described.Figure 55 represents handling process, and Figure 56 to Figure 58 is each figure that handles of explanation.

1) at first, shown in Figure 56, the two dimensional image of determined sample is decomposed into (pixel of M * N), and an absorption coefficient uniformly composed to each pixel with suitable initial value.

2) secondly, obtain the absorption coefficient C of the unit on the track of irradiating electron beam _MnSummation.Here suppose the relation of the substrate current value that total value and reality are surveyed

I＝I ₀·exp[-∑C _mn](1)

Set up.Change the absorption coefficient C of corresponding units _Mn, formula (1) is set up.

3) change the irradiating angle Θ of electron beam successively, and carry out 2 successively) operation.That is to say,, all change the absorption coefficient C of each unit successively no matter under which type of condition determination (irradiating angle Θ, accelerating voltage E) _Mn, make formula 1) and total maintenance establishment.

4) change successively the accelerating voltage E of electron beam and repeat 2), 3) operation, shown in Figure 57, by approaching the absorption coefficient map of obtaining under each accelerating voltage (distribution).

5) shown in Figure 58, each unit is compared absorption coefficient to the interdependence of accelerating voltage and the data on the database.

6) obtain the qualitative 3-D view of determined sample thus.

In above image construction method, image resolution ratio be by electron-beam probe diameter, beam spot at interval and the size of the unit in the method for successive approximation determined.Also have, the precision of qualitative analysis is that the sensitivity by the interval variation scope of beam voltage, amplitude and substrate current meter is determined.

(the lattice dislocation is checked)

In the present invention, utilize electron beam to penetrate insulating barrier and can nondestructively detect the dislocation (lattice dislocation) that produces at interlayer.That is to say, along with the progressively raising of accelerating voltage, by make electron beam pass dielectric film and shine diffusion layer and wiring etc. on can obtain the structure of lower floor, also obtain the information of the diffusion layer on upper strata and wiring etc. simultaneously.Dislocation between hole site and the lower-layer structure can be detected from the information of the different layers that obtains simultaneously, and the lattice dislocation can be estimated.Also have, by change the arrival degree of depth that accelerating voltage changes electron beam also can to such as between from the surface to the layers 2 and 3, between the 3rd layer and the 4th layer or the dislocation between the 2nd layer and the 4th layer estimate.Under the situation that improves accelerating voltage mensuration lower floor, the information on upper strata is comprised in the information of lower floor, but can separate these information by image processing.Also have, be not provided under the situation on upper strata with being connected, when carrying out the mensuration of lower floor, can be used as reversed image and detect with substrate conducting at conductive layers such as wirings.

Figure 59 represents the example that the lattice dislocation is estimated, and (a) electric current of the profile of expression device, (b) expression measurement result resembles.In this example, be provided with insulating barrier being provided with on the wafer of diffusion layer, the part of diffusion layer is exposed by the hole that is located in this insulation.When the low and electron beam of accelerating voltage can not pass dielectric film, can learn the position in hole from the measured value of the irradiation position of electron beam and substrate current.When accelerating voltage is brought up to can pass dielectric film the time, can know the position of diffusion layer integral body equally according to the difference of the impurity of semiconductor substrate.Center by estimating hole and diffusion layer depart from or the periphery distance of hole and diffusion layer can be estimated this dislocation.

Figure 60 and Figure 61 are the figure of another example of expression lattice dislocation evaluation, and Figure 60 is the situation that does not have the lattice dislocation, and Figure 61 is the situation that the lattice dislocation is arranged, and among each figure, (a) electric current of device cutaway view, (b) expression measurement result resembles.In this example, wiring is arranged on the surface of wafer, is provided with insulating barrier on this, is provided with the hole in this insulating barrier.Just was departing from originally the position of wiring and the position in hole, but in the example of Figure 61, it is big that this departs from change.Also routine the same with shown in Figure 59 in the case learnt by the electron beam of low accelerating voltage and the position in hole by the position that the electron beam of high accelerating voltage is learnt wiring, can be estimated this dislocation by measuring these spacings.

In the example of Figure 62, on the surface of wafer, be provided with diffusion layer, on this, clip first dielectric film and be provided with lower-layer wiring, then, on this, clip second dielectric film and be provided with the upper strata wiring.On this, be provided with the 3rd dielectric film again.Accelerating voltage sequentially determining substrate current value by changing electron beam is the position of each layer as can be known.

In order to detect offscale dislocation, must adjust accelerating voltage and measure, make electron beam can arrive desirable layer.Figure 63 represents the mensuration flow process when main insulating layer has only a kind of material.At first, wiring or the nonoverlapping place of diffusion layer according to selected each layer of cad data then, determine needed multiplication factor.Can't observe in the place that overlaps, also can't see structure, might check the place that does not have wiring or diffusion layer if multiplication factor is too high in vain, therefore, preferably can determine the optimum position from the data of prior design if multiplication factor is crossed to hang down.Thus, determination processing also becomes easy.Then, read in the deal with data of each layer, calculate the thickness of the insulating barrier till the lower end of each layer, read in the accelerating voltage corresponding, measure offset current with this accelerating voltage with the thickness of this insulating barrier from database.The number of times that this mensuration need be carried out is identical with the number of plies.

If the material of insulating barrier is a kind, then the response for electron beam is the same.Also have,,, then can be used as the identical materials processing if secondary electron exit dose etc. are the same with respect to the response physically of electron beam even if under the situation of multiple insulating barrier.To carry out data base system by prior mensuration to each material, when reading in deal with data, judge automatically.

As the data that before the accelerating voltage adjustment, should prepare, have with respect to the offset current of the kind of insulating barrier and thickness or detected current value in the wiring, with the corresponding offset current of the kind of every kind of insulating barrier and thickness or in wiring detected current value.These data will measured in advance, and are recorded in the database.Figure 64 represents the example with respect to the offset current of thickness, and Figure 65 represents the example with respect to the offset current of accelerating voltage.

Mensuration flow process when Figure 66 represents many insulating barriers are arranged.In the case, at first,, guarantee to be suitable for the multiplication factor of this mensuration district scope according to the wiring or the nonoverlapping place of diffusion layer of selected each layer of cad data.Then, calculate the thickness of the multiple insulating barrier till each layer respectively according to deal with data, whether retrieval has the setting consistent with these combinations in database.Having under the consistent situation about setting, read in the accelerating voltage corresponding from database, and under this accelerating voltage, measure offset current with total thickness of insulating layer of multiple insulating barrier.Do not having under the consistent situation about setting, calculating total thickness of insulating layer according to deal with data, and the most difficult material of passing of wherein a kind of electron beam of hypothesis, obtain in this case and also can penetrate into undermost accelerating voltage.Then, measure offset current with the low accelerating voltage of 500V degree, and make it imageization.If the low accelerating voltage of this degree can only be seen the top layer.Then, can penetrate into undermost accelerating voltage to what try to achieve above divided by " number of plies * n ", under each accelerating voltage that obtains, measure offset current, and make it imageization.Can be with the only value in 1～9 about the value of n.The information that includes the upper strata in the lower floor's image that obtains at this moment.The image that relatively obtains under the situation that consistent image is arranged, changes accelerating voltage thinlyyer measure before and after it.Under the consistent situation of the 2nd, the 3rd image, with the intermediate voltage of getting the 1st, the 2nd accelerating voltage when visual with get the 3rd, the 4th intermediate voltage when visual and measure, repeatable operation is until obtaining different images.Then, behind the different images of the number of plies that obtains obtaining, finish to measure by deal with data.

Figure 67 is illustrated in the lattice dislocation determination flow after the image that obtains every layer.The relatively image (apperance of electric current elephant) of each layer and the layout information of cad data, determine each image whether with cad data on what is corresponding, that is, and such as which wiring, which diffusion layer etc.Appointed coordinate position also calculated from upper surface the distance to projection image when then, resulting pattern was with the cad data Investigation and Design.The ideal value that calculates thus and compare by the measured value that image obtains.The deviation part dative dislocation of this moment quite.

Also can not to obtain hierarchical information, but integrally obtain information by the accelerating voltage that changes electron beam.Figure 68 represents the mensuration flow process of this situation.Measure in the flow process at this, at first the same with the flow process shown in Figure 65 and Figure 66, according to the wiring or the nonoverlapping place of diffusion layer of selected each layer of cad data, and definite multiplication factor that needs.Then, calculate total thickness of insulating layer according to deal with data, and the most difficult material of passing of wherein a kind of electronics line of hypothesis, obtain in this case and also can penetrate into undermost accelerating voltage, obtain electric current with this accelerating voltage and resemble.Obtain to think electric current resembled the pattern of contributive each layer and resemble with the electric current of being measured from cad data and compare.At this moment, use the information that obtains from cad data that electric current is resembled and respectively belong to which layer and separate, the position coordinates that electric current is resembled and compare and obtain deviation from the perfect condition that cad data obtains.It is necessary according to cad data electric current being resembled the work of classifying, but can therefore, can think that precision has improved with single image evaluation dislocation.

(background correction)

In above inspection, make electron beam scanning shine that compressing surface is gone up and the electric current that produces on substrate is carried out record as the function of electron beam scanning position, show as image with this luminance signal of usefulness to form the electric current image corresponding thus with real estate.Also having, image is being used under the situation that contact hole checks, serves as the benchmark that quality is judged with the size of the direct current that flows through in contact hole.But in fact, irradiating electron beam may be periodic pulsed electron beam, because of scanning beam, therefore, can produce alternating component.Therefore, in the electric current of being surveyed, except crossing the flip-flop of compressing, actual flow also comprises the composition that produces on the electric capacity.When such composition, the brightness of image and the correspondence physically of object are false, and the quality of contact hole is judged the inaccuracy that becomes, the reduction of the 3D shape difficulty that becomes.

So preferably irradiation frequency by changing electron beam or scanning frequency are measured electric current and the electric current composition that flows through the electric capacity that is examined sample itself are revised.Each expression of Figure 69 and Figure 70 is used to carry out the example of 2 handling processes of such correction.

In the handling process shown in Figure 69, under the situation of the electron beam of reirradiation pulse type, change this repetition period to measure repeatedly, outside the current waveform that obtains, be inserted in electron beam by the value of the situation of Continuous irradiation and obtain flip-flop.If constituting example with device shown in Figure 1 describes, electron gun 1 formation of the electron beam that reproduces living pulse type of attaching most importance to then, transmitted beam flow control part 11 changes the repetition period of these electron beams, is inserted in electron beam outside the current value of measuring separately from difference repetition period irradiating electron beam the time with data processing equipment 10 by the value of the situation of Continuous irradiation and obtain flip-flop.

In the flow process shown in Figure 70, the sweep speed of switching electron beam is measured repeatedly, obtains value when sweep speed is extrapolated to zero from the current waveform that obtains.If constituting example with device shown in Figure 45 describes, then electron beam irradiation position control device 116 can switch the sweep speed of electron beam by subscan with arrangement for deflecting 251, in the data processing equipment (for example square frame 10 of Fig. 1) of the output of accepting D/A converter 120, obtain value when sweep speed is extrapolated to zero from the current value of with different sweep speed scanning beam the time, being measured separately.

Such as above detailed description, device for checking semiconductor device of the present invention can nondestructively obtain the information relevant with the structure of the depth direction that is examined sample, in the quality of the semiconductor device that is used to judge manufacturing with check that whether best manufacturing process effective especially in the when of.

Also have, for can only cutting sample and the range information in the contact hole cross section observed with SEM at section in the past, the information that resembles the contact hole peristome that obtains from secondary electron by combination not only can obtain up and down range information of contact hole, can also obtain more accurate information in conjunction with the relevant information of the structure with the depth direction that is examined sample that obtains with different accelerating voltages in conjunction with the contact hole bottom shape.

Using under the situation of rectangular electron beam, the position at the edge of this electron beam can be easily specific, can be easily and the area in the zone measuring electron beam accurately and passed.Application to contact hole only has been described in an embodiment, has differentiated on inspection and the measuring shape but also can be applied in the opening that has with the same through hole of constructing of contact hole, etchant resist, wiring, groove.Equally, can also carry out shape inspection or bottom state inspection after the various etch processes or after cleaning processing.

Because the present invention is nondestructive inspection (NDI), even if also can obtain the information of contact hole depth direction need not resembling in the past with SEM observation sample cross section, therefore, can directly measure product, does not need monitoring wafer, process cost reduces.

Also have, can be determined at area, diameter or its 3D shape at the bottom of the contact hole in the processing procedure fast, therefore, can carry out process modification then and there with analog form.For example, under the situation of carrying out the etching condition proposition, if the shape at the bottom of needs control opening shape and the contact hole is but the distribution that just can work as the contact hole floor space on the field recognition entire wafer with this method.

Also have, only the defective of contact hole was judged that astomous digital form inspection was arranged in the past, therefore, when not having opening, just detect unusual, relative therewith, according to the present invention, can monitor the diameter of the depth direction of made contact hole always, therefore, in fact before taking place, the contact hole flaws can find to resemble variation unusual of the such analog quantity of the information of the footpath, the end of contact hole or depth direction.Therefore, can be than in the past earlier to taking measures unusually.Particularly with based on the contact hole of overall electric current method at the bottom of the footpath mensuration combination and detected under the unusual situation by the overall electric current method and to have carried out more high-precision mensuration.Make it to get on the hole because of needing only the adjusting electron-beam position, therefore, the overall electric current method can be measured with low aligning accuracy.

Under the situation of amperometric determination, have only the electric current of the wiring of flowing into just measured value to be had contribution, therefore, in inspection technique in the past, needing need not to carry out the equalization of the check result of carrying out etc., can improve inspection speed.

Mensuration flow through the electric current of alignment mark and the situation of aiming under, can not want the secondary electron image deriving means that only is used to the high price of aiming at.

During current waveform is in the present invention measured, can obtain checking effective information, may not leave no choice but make electron beam to shine on the ad-hoc location of wiring no matter the position that electron beam passes is which part that connects up.On the contrary, can regulate the sensitivity of defective pattern detection by changing the electron beam irradiation position.Also have, the connect up inspection of quality of the rising edge of the current waveform that utilization is produced by electron beam irradiation and the marginal position information of the wiring that trailing edge obtains, therefore, even if under the situation that only can't draw check result clearly, also can check by the size that obtains current waveform.

In general, compare, more can realize high speed to the inspection of the wiring of arranging, but both are blended in the same chip with array-like with inspection to the wiring that sets at random.In the case, can in initial inspection, investigate the arrangement of wiring in advance, estimate the position of the wiring of arranging from the frequency distribution of the electric current measured with array-like, and the inspection method the most suitable according to this Information Selection, therefore, can make the inspection high speed.

Current waveform among the present invention is measured not only irradiating electron beam continuously, can also be carried out discontinuously.Also have, can improve actual sweep speed, the effect that improves inspection speed is arranged by the subscan of carrying out electron beam.The electron beam that is scanned may not leave no choice but scan different positions, also can be overlapping a little the marginal portion in scanography district.Can suitably select optimal accelerating voltage, injection current per sample and utilize.Even if in the pattern defective is under the situation of part, be detected with the proportional electric current of defect area, therefore, if the electric current that defect area produces changes the SN that surpasses testing fixture then is detected as defective.

Current waveform among the present invention is determined under the situation that certain connection is arranged between the wiring of checking object and the substrate effectively, but the situation that wiring is had a big drainage area with also can check to the big situation of leakage current or by the situation that big electric capacity is connected with substrate conducting.Can check a plurality of wirings simultaneously, therefore, compare and to check faster with method in the past.Also have, can be from the cross-sectional configuration of surperficial Direct observation device.

Claims (25)

1. system that is used to obtain about the information in hole, described hole be arranged in the semiconductor wafer on described semiconductor wafer or above in the set layer, described system comprises:

The electron gun of divergent bundle;

The current-flow test set of metrophia compensation electric current, wherein said offset current produces in response to being transmitted into the electron beam on the described hole; And

Data processor is coupled to described current-flow test set, determines information with all long correlation of the end diameter or the end in described hole to use by the amount of the measured offset current of described current-flow test set.

2. the system as claimed in claim 1 further comprises electrode, and it is coupled to described current-flow test set, to gather described offset current.

3. system as claimed in claim 2 is coupled to described semiconductor wafer wherein said electrode capacitance, to gather described offset current.

4. the system as claimed in claim 1, wherein:

Described electron gun comes divergent bundle with a plurality of electron beam acceleration; And

Described current-flow test set is measured the amount of the offset current that produces in response to each electron beam, and described electron beam has one of described a plurality of electron beam acceleration.

5. system as claimed in claim 4, wherein said data processor is coupled to described electron gun, to control the accelerating voltage of described electron beam.

6. system as claimed in claim 4, wherein said data processor at a plurality of accelerating voltages of described electron beam use measured offset current determine with in the relevant information in the described hole of depth direction.

7. system as claimed in claim 4, wherein said data processor uses the amount of measured offset current to determine the information relevant with the vertically profiling in described hole at a plurality of accelerating voltages of described electron beam.

8. system as claimed in claim 4, wherein said data processor based on determine at the amount of the measured offset current of a plurality of accelerating voltages of described electron beam with in the relevant information in the described hole of depth direction, it is caused by the penetration depth at the described electron beam of a plurality of accelerating voltages.

9. the system as claimed in claim 1, wherein said data processor is coupled to the time period that described electron gun shines described hole with the accelerating voltage of controlling described electron beam and described electron gun, and wherein said data processor uses measured offset current to determine the information relevant with the vertically profiling in described hole at a plurality of accelerating voltages of described electron beam.

10. the system as claimed in claim 1 also comprises translational table, and it is suitable for moving described semiconductor wafer on respect at least one direction of electron beam, and wherein:

Described electron gun is along bundle axle divergent bundle; And

Described translational table in response to the control signal from described data processor, tilts described semiconductor wafer with respect to described bundle axle.

11. system as claimed in claim 10, wherein said data processor uses measured offset current to determine the information relevant with described hole at a plurality of incidence angles of described electron beam on described semiconductor wafer.

12. the system as claimed in claim 1, wherein said data processor uses the amount of described offset current and the existence that reference value is determined residual film in the described hole, and wherein said reference value use test zone determines, described test zone have with described wafer on the pattern in the similar hole of pattern in hole.

13. the system as claimed in claim 1, wherein said hole are contact hole or through hole.

14. the system as claimed in claim 1 also comprises translational table, it is suitable for moving described semiconductor wafer on respect at least one direction of described electron beam.

15. the system as claimed in claim 1, wherein said data processor is coupled to described electron gun, to control the time period that described electron gun shines described hole.

16. system as claimed in claim 15, wherein said data processor uses the amount of described offset current to detect the existence of residual film in the described hole.

17. the system as claimed in claim 1, wherein said data processor use described offset current amount and reference value to determine the existence of residual film in the described hole.

18. the system as claimed in claim 1, wherein said electron beam comprise less than the diameter in described hole or the cross section in aperture.

19. the system as claimed in claim 1, wherein said electron beam comprise greater than the diameter in described hole or the cross section in aperture.

20. the system as claimed in claim 1, wherein said data processor use are determined by the amount of the measured offset current of described current-flow test set and the information of all long correlation of the end diameter or the end in described hole, described hole has circular basically cross section.

21. the system as claimed in claim 1 also comprises translational table, it is suitable for receiving described semiconductor wafer, and moves described wafer with respect to described electron gun, and described electron beam shines described hole simultaneously.

22. the system as claimed in claim 1, wherein said electron gun comprises beam deflector, with respect to described wafer and stride across described hole and move described electron beam.

23. the system as claimed in claim 1 also comprises limit bundle circle, to collimate the cross section of described electron beam.

24. the system as claimed in claim 1, the beam cross section of wherein said electron beam are rectangle, circle or square.

25. the system as claimed in claim 1 also comprises condenser lens, so that form parallel beam from described electron gun institute electrons emitted bundle.

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