CN1213469C - Apparatus and method for contact failure inspection in semiconductor devices - Google Patents

Abstract

There is provided a contact failure inspection system and method for semiconductor devices and a method of manufacturing semiconductor devices. Using digitized values for electron signals detected using a scanning electron microscope, contacts can be inspected to identify failures such as non-open contact holes. The contact failure inspection is performed by comparing the electron signal value detected from a unit area including at least one contact hole with values representative of the electron signal corresponding to a normal contact.

Description

The apparatus and method that are used for the contact fault detection of semiconductor device

The present invention relates to the detection range of semiconductor device.Particularly, the present invention relates to use scanning electron microscopy to detect contact fault, for example do not open (not-open) contact hole.

Integrated circuit is made by at first form discrete-semiconductor device in silicon wafer.In device, form the multiple layer metal interference networks then, make their active element contact and they are linked together, to make desired circuit.Interconnection layer is by deposition insulating layer on discrete component, composition and at this layer corrosion contact openings, what depositing conductive material formed in opening then.On insulating barrier, generally apply conductive layer then.This conductive layer of composition and corrosion interconnect to form between device contacts then, thereby form the first order of Circuits System.Repeat the formation of formation, conductive material layer of deposit, contact hole or the through hole of insulating barrier and composition etc., to form the multi-level pmultistage circuit system.

According to the complexity of whole integrated circuit, the general multilayer that requires to form metal, for example two to four layers, forming required interconnection, and these interconnection are connected to contact pad, this contact pad allows that the outside is connected to the finished product circuit.The high density that is designed into the integrated circuit of submicron-scale requires extremely accurate dimensions control and super-sensitive detection method to detect the figure of interconnection and/or contact hole, to guarantee the yardstick and the structural intergrity of design configuration.The more and more tightr and miniaturization along with circuit, it is strict more that these requirements have become, and for example passes through the batch process such as the semiconductor storage unit of 64M DRAM or 256MDRAM, generally requires the circuit yardstick of 0.25-0.30 μ m at present.

For example be used for not that the contact hole status detection of open mode and so on becomes more and more important, because the aspect ratio of contact hole (A/R), i.e. the ratio of its degree of depth and its diameter is along with to the increase of the highdensity requirement in the semiconductor device and increased.But, use the common optical microscopy of 488nm wavelength visible light restricted on the internal feature that detects contact hole, because it does not have the internal feature that sufficiently high resolution detects contact hole, these internal features are the magnitudes at 200nm or smaller szie.Optical microscopy can not provide 1 μ m or littler beam spot size.

The purpose of this invention is to provide the contact fault detection method and the device that are used for semiconductor device, it provides by means of digitlization rather than by naked eyes or microscope and has carried out the accurate contact fault detection of contact image, has avoided basically because the restriction of correlation technique and one or more problems that defective causes.

Another object of the present invention provides the contact fault detection method that is used for semiconductor device and is used for contacting the contact fault detection system of the existence that detects contact fault, and wherein contact has high aspect ratio, i.e. the ratio of the degree of depth of contact hole and its diameter.

Another object of the present invention provides the contact fault detection method that is used for semiconductor device and is used to detect the contact fault detection system of the contact fault on wafer surface, and wherein this detection is being provided with so that be applicable to produce in batches of carrying out at short notice.

Another object of the present invention provides the method for using contact fault detection method and contact fault detection system to make semiconductor device.

Another object of the present invention provides the position that is used for fast detecting contact fault contact fault detection method and the system with the productivity ratio that improves semiconductor device.

Another object of the present invention provides detection method and the detection system that is used for detecting after development treatment at photo-etching technological process the existence of figure fault in the semiconductor device and photoresist figure fault.

For realizing these and other purpose, the present invention relates to be used for detecting the method and apparatus of semiconductor wafer at least a portion.In the present invention, scanning electron microscopy (SEM) view data that is used for the part of semiconductor wafer is read out.In the SEM view data, the view data that is used for the feature on the wafer is identified.Calculating relates to the parameter of this feature and compares with the acceptable value scope of this parameter.On the basis of the comparison between this parameter and the acceptable value scope, with this tagsort.

In one embodiment, parameters calculated is the yardstick or the size of this feature.For example, under this feature was contact hole situation in the integrated circuit, this parameter can be the diameter in the hole measured in the view data pixel.For example, it is wide that contact hole can be defined as 20 pixels.In another embodiment, this parameter can be the average pixel brightness for the pixel in this feature.For example, be under the situation of contact hole in this feature, this parameter can be the mean value for the pixel brightness of the pixel that relates to this contact hole.Under the situation in the acceptable value scope of parameter in this parameter of measuring, this feature is classified as acceptable.Under situation beyond the scope of this parameter at the acceptable value of this parameter, this feature is classified as fault.For example, be characterized as under the contact hole situation, this contact hole can be judged as fault, and for example it is an opening not.

In one embodiment of the invention, two of calculated characteristics parameters.The characteristic size of for example contact hole and so on that these two parameters can be measured with the pixel that relates to this feature.Second parameter can be the mean value for the pixel brightness of the pixel that relates to this feature.Two parameters are all compared with the preset range of the acceptable value of this parameter.In one embodiment, under the situation of two parameters while in their tolerance intervals separately, this feature, promptly contact hole can be classified as acceptable.For example, contact hole under these conditions can be classified as and open and suitable dimensions and shape.Relation between the scope separately of parameter and they can be used for tagsort for belonging to one of several types or category.For example, each parameter can be used for according to parameter whether under its scope of acceptable value, within or on and with tagsort.

In one embodiment, secondary electron from scanning electron microscopy and more high-octane back scattered electron produce the SEM view data.This data value is digitized, and can be the form of digitized gray scale (grey scale) pixel grade or color coding pixel value.

In one embodiment of the present of invention, use grid or network so that for example determine the position of detected feature and/or size and detected feature characterization.Grid or network generally comprise a pair of mutually perpendicular axle on the image of the part that is superimposed upon analyzed wafer.Perhaps, the grid axle can form any suitable geometrical relationship, triangle for example, trapezoidal (trapezoidal) etc.In one embodiment, the grid position program is by analyzing position, shape and/or the cycle graph of determining feature along the pixel value of the straight line that is parallel to one of orthogonal axle, and wherein one of this orthogonal axle is positioned at the pixel location along another vertical axis continuously.For example, grid method can be included in a plurality of horizontal pixels position vertical line is set, and adds vertical pixel brightness value at each horizontal level.Summation brightness can be at each horizontal level relatively, and with the increase in the identification brightness, this can be used for for example existence of contact hole of representation feature.This road technology can repeat a plurality of pixel locations along the one dimension direction.Repeat in vertical direction then, thereby can determine figure, the shape and size of all features.

This method also can be used for determining to contain the sub-grid of analyzed feature or the optimum size of grid cell.For example the grid program can be used for selecting to contain the optimum size of the grid cell in the pixel of 100 once analyzed contact holes.This method makes the present invention be the more effective part of the processing of detected characteristics, and unnecessary processing can be eliminated by optimizing each detected regional area.

In one embodiment, SEM image pixel data can be used for being each detected feature, and for example contact hole calculates Luminance Distribution figure (profile).In one embodiment, the Luminance Distribution figure will be at first by adding up generation along the pixel brightness value of a vertical axis of each position of a plurality of pixel locations of vertical rectangular coordinates axle setting to a feature.For example, in each horizontal pixel position, pixel brightness value in vertical direction adds up, and averages and draws with respect to the trunnion axis pixel location.The pixel brightness distribution pattern is used for this tagsort according to the present invention then.

In one embodiment, for the Luminance Distribution figure normalization to all features, subtracting background brightness value in all brightness values from each grid cell.This has and the background value of each Luminance Distribution figure is reduced to zero effect.Then, can in the normalization figure, threshold value be set, so that the above pixel brightness of this threshold value is predicated relevant with this detected feature.Then, can from distribution pattern, calculate first and second parameters of above-mentioned identification.For example, the yardstick of feature can calculate by calculating along first quantity of tieing up the pixel location of direction, and wherein these pixel locations have the total brightness value that surpasses threshold value in vertical direction.Because it is relevant with feature that hypothesis surpasses the pixel brightness summation of threshold value, has the measured value that is given in the one dimension direction of feature measured in the pixel above the quantity of the pixel location of the summation of threshold value so.Second parameter can be calculated by the mean value that calculates the brightness value that surpasses threshold value.For will this concrete tagsort for belonging to one of predetermined characteristic type classification, these two parameters are compared with the preset range of their acceptable values separately.

Detection method of the present invention and system have a plurality of advantages that are better than art methods.For example, a certain art methods is used optical means, and for example light microscope or visual inspection are to detect contact fault.These systems can not solve little irregularly shaped in the feature, and the result produces faulty circuit.The scanning electron microscopy of use related to the present invention provides very high resolution so that littler irregularly shaped also can be detected.Therefore the present invention is applicable to the circuit feature of present size in sub-micrometer range.And because grid method of the present invention, pixel data of the present invention is handled very effective.Can be very effectively and handle apace and Fault Identification, so that detection method of the present invention and system height are applicable to wafer and circuit batch production setting.

On the other hand, the present invention relates to be used for the contact fault detection method of semiconductor device, it may further comprise the steps: the handle box that an installation has the wafer that is formed on its lip-deep a plurality of contact holes is set; From handle box, take out a concrete wafer and it is loaded on the objective table in the reference chamber of SEM; The wafer of aiming at this loading is to carry out electron beam scanning; The objective table that wafer is installed is moved to the ad-hoc location relevant with the electron beam incident direction of SEM; Open shutter, be used for the ad-hoc location of electron beam scanning to wafer; Be formed on pre-composition reference picture on the wafer by identification, be the detection automatic addressing of detection position; The electron beam scanning of SEM to the detection position; By repeating electron beam scanning, automatic focus is used to obtain further distinct image; Close shutter, be used for automatic focus wafer and electron beam are kept apart; By will be after containing scanning beam the electronic signal numerical value that detects of the cell surface of at least one contact hole compare detection contact fault with definite normal contacting electronic signal value; By moving stage lay equal stress on to another position complex phase with step, in the another location of wafer, further detect contact fault; The wafer of finishing by unloading and other wafer be loaded into lay equal stress in the reference chamber complex phase with step, all wafers in the handle box is further detected contact fault.

According to a further aspect in the invention, the method for manufacturing semiconductor device may further comprise the steps: the specific insulation material layer that is formed on the Semiconductor substrate is formed contact hole; By the electronic signal value that will detect from the surface that comprises at least one contact hole with compare corresponding to the normal electronic signal value of contact hole, detect the contact of each contact hole; After inserting conductive material layer in the contact hole after detecting, carry out the processing of the back of process for fabrication of semiconductor device.

Contact fault detects step can carry out the specific-assignment sampling position on the Semiconductor substrate, for example, production line of batch is carried out contact fault detect step.Finish after the development treatment of photoresist figure moulding, can carry out further failure detection steps the bottom of photoresist figure of contact hole forming.

According on the other hand, the present invention includes the method for making semiconductor device, this method may further comprise the steps: for the insulation material layer that forms on Semiconductor substrate forms contact hole, form the photoresist contact hole graph; By the electronic signal value that will detect from the unit area that comprises at least one contact hole graph with compare corresponding to the normal electronic signal value of contact hole graph, detect the contact of each contact hole.

By the reference accompanying drawing detailed description of the preferred embodiments of the present invention is made of the present invention aforementionedly and other purpose, characteristics and advantage are more obvious, identical fixed reference feature has adopted identical parts to represent in different figure in the accompanying drawing.Accompanying drawing is not pro rata, focuses on representing principle of the present invention.

Fig. 1 is the schematic block diagram of the operation of expression scanning electron microscopy (SEM);

Fig. 2 is when being illustrated in reference point and being shone by electron beam, the curve chart of the power spectrum of the electronics of being launched in SEM, comprise secondary electron and back scattered electron;

Fig. 3 is the block diagram of the configuration of expression online (in-line) SEM;

Fig. 4 is the block diagram of an embodiment of the expression contact fault detection system that is used for semiconductor device according to the present invention;

Fig. 5 is expression is used for another embodiment of contact fault detection system of semiconductor device according to the present invention a block diagram;

Fig. 6 is expression is used for another embodiment of contact fault detection system of semiconductor device according to the present invention a block diagram;

Fig. 7 is expression is used for the another embodiment of contact fault detection system of semiconductor device according to the present invention a block diagram;

Fig. 8 is the functional-block diagram according to an embodiment of contact fault detection method of the present invention and system;

Fig. 9 is the functional-block diagram according to another embodiment of contact fault detection method of the present invention and system;

Figure 10 is the functional-block diagram according to another embodiment of contact fault detection method of the present invention and system;

Figure 11 represents to be used for according to the present invention the flow chart of logic flow of an embodiment of the contact fault detection method of semiconductor device;

Figure 12 represents to be used for according to the present invention the flow chart of logic flow of another embodiment of the contact fault detection method of semiconductor device;

Figure 13 represents to be used for according to the present invention the flow chart of logic flow of another embodiment of the contact fault detection method of semiconductor device;

Figure 14 represents to be used for according to the present invention the flow chart of logic flow of another embodiment of the contact fault detection method of semiconductor device;

To be expression be used for the schematic diagram of the figure of the chip sampled position on the wafer that contact fault detects according to the embodiment of the invention to Figure 15;

Figure 16 is the detailed schematic that is illustrated in the resample area in the chip sampled position of Figure 15;

Figure 17 is the sectional view of representing wherein to have the semiconductor device of the contact hole that is used for contact fault detection according to an embodiment of the invention;

Figure 18 represents to be provided with by the contact position recognition methods according to one embodiment of present invention the SEM view data of grid contact hole afterwards;

Figure 19 represents that grid setting according to an embodiment of the invention is to contact the schematic diagram of recognition methods;

Figure 20 represents that grid setting in accordance with another embodiment of the present invention is to contact the schematic diagram of recognition methods;

Figure 21 concerns schematic diagram according to one embodiment of present invention between osculating element and level and vertical pixel unit;

Figure 22 represents the Luminance Distribution figure of osculating element before background value removes according to one embodiment of present invention;

Figure 23 is illustrated in background value and removes the Luminance Distribution figure of the osculating element of Figure 22 afterwards;

Figure 24 is illustrated in background value and removes the Luminance Distribution figure of the SEM image of osculating element afterwards;

Figure 25 represents the chart of the code recognition result of contact fault detection according to one embodiment of present invention;

Figure 26 represents a part of result's of contact fault detection chart according to one embodiment of present invention;

Figure 27 represents the flow chart of the logic flow of semiconductor device treatment process according to one embodiment of present invention;

Figure 28 is the block diagram of the embodiment logic flow of contact detecting method according to the present invention;

Figure 29 is the logic flow of scanning electron microscope image data is read in expression according to the method for Figure 28 a flow chart;

Figure 30 A-30D represents the flow chart according to the logic flow of the method identification contact hole position of Figure 28;

Figure 31 A-31D represents to calculate according to the method for Figure 28 the flow chart of the logic flow of contact hole distribution pattern;

Figure 32 A-32B represents to detect according to the method for Figure 28 the flow chart of the logic flow of contact hole.

Fig. 1 represents the block diagram of scanning electron microscopy used according to the invention 100, in order to detect the contact hole in the semiconductor device.

With reference to Fig. 1, electron gun 102 divergent bundles are by collector lens 104.Electron beam passes the diaphragm 106 and the shutter 124 of deflecting coil 122, object lens 108.Focused beam be transmitted into reference to or sample surfaces 110 and scanning, this surface can be the surface of detected semiconductor wafer.Detected signal detector 112 from the secondary electron and the back scattered electron of reference surface emission, produce the signal that expression receives electronics.Detected electronic signal is amplified in signal amplifier 114.The signal that is exaggerated can scan on the fluorescent surface of cathode ray tube (CRT) 118 inside, to form the visual image of reference surface.

The scanning of CRT118 is by deflecting coil 116 controls relevant with the scanning of the reference surface that is deflected coil 122 controls.In SEM, the scanning of a surface of reference surface is divided into meticulous pixel, is transmitted by up time ground by the electronic signal that each pixel element detects, so that form the SEM image.So far, the electronic signal of passing signal amplifier 114 is transferred in the scanning circuit 120, thereby the deflection angle of electron beam is controlled in second deflecting coil 122.

In addition, can transfer to processing unit for the electronic signal that each pixel is exaggerated, it can realize the various functions that signal met the requirements and handle.Processing unit 115 can be converted to discrete gray scale or color coding value to the electronic signal of each pixel, is used to produce image.Gray value can be thought by one of possible rank 256 of the coding of the binary system value between 0 to 255 individual.Memory can be used to store the gray value of each pixel.Computer as the part of processing unit can be handled required view data.In a configuration, computer is programmed analyzing gradation data, in order to carry out the contact detection of the present invention as the detailed description here.

Fig. 3 represents the block diagram of the feature of online SEM system, and contact detection can onlinely be carried out.In prior art processes, the SEM view data is a Collection and analysis beyond production line, promptly breaks away from manufacturing process.Because of the present inventionly improved efficient greatly at line method, thus the SEM view data can be in process for making Collection and analysis.Like this, can eliminate the extra detection step of using in the art methods.Online SEM system comprises the electron optics part, reference section, vacuum section and electronic section.Electron optics partly comprises electron beam generator 14, beam deflector 15 and signal detector 16.Reference section comprises and being used for reference substance, i.e. wafer is sent to the reference substance translator unit 12 and the reference substance alignment portion 13 of reference chamber from handle box.Vacuum section comprises that being used to keep in the reference chamber is the vacuum formation part 11 of vacuum.Electric part comprises master computer 10, and it has the master controller 21 that is used to control electron optics part, reference chamber, vacuum section and other system unit.Electric part also comprises the basic display unit 19 that can store from the memory cell or the memory 22 of the detection signal data of signal detector 16 and be used to show the image that produces from institute's detected electrons signal.Autofocus controller 18 carries out automatic focus so that distinct image to be provided.

In general scanning electron microscopy, electron beam shines reference surface, produces secondary electron and launches from reference surface.Electronics from electron beam also can be from this surface scattering.Fig. 2 is illustrated in irradiation power spectrum from the electronics of reference surface emission and scattering during reference surface.As shown in Figure 2, the maximum quantity of finding secondary electron (SE) finds that most of back scattered electron (BSE) is in high energy band more in the electron energy band less than 50eV.Extensively available online SEM uses the secondary electron (SE) that produces in the low-energy zone of about 20eV, so that the image at surface and edge is more clear.But, having in the detected characteristics of for example contact hole and so under the situation of the degree of depth that high aspect ratio is the hole and its diameter ratio, the inner secondary electron that produces of contact hole may disperse when they pass contact hole, thus the not fogging Chu of contact hole.Because the generally eye test with the naked eye of these features detects for contact fault, distinct image is necessary.

Fig. 4-7 expression is used for the block diagram of various embodiment of the contact fault detection system of semiconductor device according to the present invention.The system of Fig. 4 comprises the some parts identical with the parts of the online SEM shown in Fig. 3.But it also is included in the contact fault detection module 60 in the master computer 20.As mentioned above, the structure of online SEM comprises: the electron optics part, it comprises electron beam generator 14, beam deflector 15 and signal detector part 16.Signal detector preferably uses and can detect the secondary electron (SE) launched and the detector of back scattered electron (BSE) after with electron beam irradiation reference surface.This system also comprises reference chamber, and it comprises with reference to alignment portion 13, is used to rotate and tilts and place the objective table of detected reference wafer on it, moves along X, Y and Z axle simultaneously.Vacuum forms part 11 and keeps reference chamber to be in other vacuum state of level that requires.Reference substance translator unit 12 is sent to reference substance in the reference chamber.Electric part comprises master computer 20, and it has the master controller 21 that is used to control electron optics part, reference chamber, vacuum formation part and other subsystem.Main memory unit or memory 22 store the signal that detects from signal detector 16.Basic display unit 19 shows the image that derives from the detected electrons signal.Autofocus controller 18 is used for the focusing operation that the clear display image shows automatically.Present embodiment also comprises contact fault detection module 60, is used for according to the present invention analysis package and is contained in information that transmit from signal detector 16 and the electronic signal that master computer 20 stores, to detect contact hole.

Fig. 5 represents to be used for according to the present invention another embodiment of the contact fault detection system of semiconductor device.The system of Fig. 5 also comprises the part parts identical with the online SEM of Fig. 3.Different parts are, it also comprise contact fault detection module 60 be positioned at master computer 20 contact evaluation size (CD) measurement module 70.The evaluation size is the size of detected special characteristic.For example under the situation of circular contact hole, the evaluation size can be the diameter in hole.In one embodiment, contact evaluation size (CD) measurement module 70 is measured by comparing with the standard value of pre-storage from the contact diameter of the contact image that is produced by SEM.

Fig. 6 represents to be used for according to the present invention another embodiment of the contact fault on-line detecting system of semiconductor device.The system of Fig. 6 also comprises the part parts identical with the online SEM of Fig. 3.Different is that it also comprises and the sub-computer 80 of master computer 10 interfaces and the contact fault detection module 60 in the sub-computer 80.Sub-computer 80 can use personal computer general on the normal business, and can comprise sub-display and sub-memory cell or memory.The existence of contact fault can be analyzed by the contact fault detection module in the sub-computer 80 60 and detect from the data that are stored in the contact electronic signal in the main memory unit 22.

Fig. 7 represents to be used for according to the present invention another embodiment of the contact fault detection system of semiconductor device.The system of Fig. 7 also comprises the part parts identical with the online SEM of Fig. 6, has the sub-computer 80 that is connected with master computer 40.It also has and contacts CD measurement module 70 in contact fault detection module 60 and the master computer 40 in sub-computer 80.

Fig. 8-the 10th, expression is according to the functional-block diagram of the various embodiment of contact fault detection module 60 of the present invention.Referring to Fig. 8, contact fault detection module 60 can comprise SEM signal reading module 60a, the SEM signal of the electronics that receives from wafer when its reception is illustrated in and is shone by electron beam.Contact position identification module 60d analyzes the SEM signal, with the definite contact hole that will detect and/or the position of further feature.Contact pattern calculates and background removal module 60e uses the SEM signal data to produce the Luminance Distribution figure of contact hole.The Luminance Distribution figure generally carries out normalization by removing the data that produced by the background luminance effect, detects thereby Luminance Distribution figure shape can be independent of background effect.Contact fault detection module 60f analyzes the Luminance Distribution figure of contact hole with identification contact fault.In one embodiment, as following detailed, the average brightness value of contact is compared with predetermined threshold with the identification fault.Display module 60g can show the result of accident analysis as a result.

In one embodiment, SEM signal reading module 60a reads the digitalized electron signal message of contact hole, and this information storage is in the main memory unit or memory 22 of master computer 20.The electronic signal digitlization that online SEM will detect by electron beam scanning, and store as gray scale or other brightness of color coding level.In a system, the gray value of distributing to each pixel is of 256 probable values in from 0 to 255 the scope.Maximum brightness is defined as 255, and minimum brightness is defined as 0.The digitlization brightness value is encoded by each colors of pixel elements, i.e. gray scale.By with the gray value that reads each pixel continuous time and on cathode ray tube, monitor and/or printer the display element image, produce contact image.Gray scale can convert to and be used for the colored colour that shows.

Referring to Fig. 9, the embodiment of the contact fault detection module of wherein describing comprises the remodeling of the embodiment of Fig. 8.In Fig. 9, contact pattern computing module 60e (1) and background value are removed module 60e (2) and are provided as separate modules, with relative with composite module 60e among Fig. 8.

Figure 10 is the functional-block diagram of expression according to another embodiment of contact fault detection module 60 of the present invention.Referring to Figure 10, contact fault detection module 60 comprises graphic file transmission network module 60b, and graphic file is to SEM signal conversion module 60c, contact position identification module 60d, the combination contact pattern calculates and background value removal module 60e, contact fault detection module 60f and display module 60g as a result.

Referring to Fig. 6, graphic file transmission network module 60b is a kind of device of the signal transmission between master computer 10,40 and the sub-computer 80.The information translation that module 60b will be stored in the digitalized electron signal of the contact in the main memory unit 22 of master computer 10,40 becomes graphic file, then it is sent to sub-computer 80.

Graphic file reads the color coding of the graphic file that is sent to sub-computer 80 to SEM signal conversion module 60c, i.e. gray scale, and convert thereof into digitalized S EM signal.Contact position identification module 60d, contact pattern calculate and background value removal module 60e, contact fault detection module 60f and the explanation of display module 60g as a result referring to top to Fig. 8 and Fig. 9 explanation.

The flow chart of the various embodiment that the online detection of contact fault of the semiconductor device of Figure 11-14 expression contact fault detection system used according to the invention is handled.Referring to Figure 11, the contact fault test section of Fig. 4 60 uses the online SEM that is installed in the master computer 40 to carry out contact fault on the wafer of a plurality of contact holes and detect having.At first, really on the allocation, the handle box (S10) that the wafer with a plurality of contact holes is installed is set at online SEM.Then, after taking out the wafer that will detect from handle box, it is loaded on the objective table in the reference chamber of SEM (S12).Then, the plane of alignment wafer.Then, the wafer aligned electron beam scanning (S14) of loading, and the objective table that wafer is installed on it moves a certain position (S16) with the incident direction that is placed on the electron beam that is used for SEM.

Open the shutter that is placed on below the object lens, so that automatic addressing (S20) is carried out in irradiating electron beam on a certain position of wafer.Automatic addressing is discerned a certain position by apply pre-composition standard picture on this position, thereby can detect with respect to standard picture.

Then, the position that detect uses the electron beam from SEM to shine (S22), and partly repeats electron beam scanning (S24) by the auto focus control that is used for clear contact image.Then, in order to finish the electron beam scanning of wafer, close shutter.

Then, detect from the Luminance Distribution figure (S28) of each contacting electronic signal of electron beam scanning detection according to the present invention.Determine whether that then carrying out contact fault in the another location of wafer detects (S30).If then flow process is got back to S16, and objective table moves to the another location of wafer, repeats above-mentioned steps.When finishing the contact fault detection, unload lower wafer (34).If like this, another wafer in the handle box is loaded in the reference chamber, and repeats above-mentioned steps, thus the wafer in the handle box is carried out contact fault and detects.If all wafers has been finished the contact fault detection, handle box is removed (S36), finishes technology thus.

Referring to the embodiment of Figure 12, represent by the online SEM that use has contact fault test section 60 wherein and the Figure 15 that contacts the master computer 30 that CD measure portion 70 is formed together with the contact fault detection method of the wafer that has a plurality of contact holes thereon.Contact fault detects as described above that Figure 11 carries out like that, but different with the embodiment of Figure 11 is, shutter is closed (S26), determines that contact fault detects (S27), and measures (S29) not carrying out contacting CD when contact fault detects (S28).

Figure 13 represents to be used to have by the online SEM that uses Fig. 6 the contact fault detection method of the wafer of a plurality of contact holes, and contact fault test section 60 is arranged in sub-computer 80 among Fig. 6, rather than in master computer 10.As shown in figure 13, after closing shutter (S26), the SEM signal that is stored in the main memory of master computer is transferred to sub-computer, determines that need carry out contact fault to the another location of wafer detects (S31).Sub-computer receives this transmission signals, detects (S37) so that carry out contact fault.

In the embodiment of Figure 14, be installed in the sub-computer in contact fault test section 60, rather than be installed in the sub-computer among Fig. 6 under the situation the mutual exchange sequence of sub-computer and master computer.By the identical step shown in Figure 11, close shutter (S26), the SEM signal of determining to be stored in the main storage compartment of master computer is transferred to sub-computer (S31-1), carries out contact fault by sub-computer and detects (S31-2).Determine whether on other position, to carry out contact detection (S31-3, S31-4).

The numbering area (#2-#37) of test on the wafer 110 under the contact fault of the present invention that is illustrated in Figure 15 detects.Be expressed as a region representation alignment point of " AP ", " #1 " expression chip is focal position not.

In each digital coverage territory of Figure 15, can define several sample position.For example, for chip or the regional #2 of Figure 15, Figure 16 represents five sample position, i.e. the upper left corner (2,1), the upper right corner (2,2), the lower right corner (2,3), the lower left corner (2,4), and center (2,5).Sample position or sampling numeral can be selected in a sample chip unit in every way.In embodiment shown in the present, 175 positions of sampling from 35 chips or resample area, five sample position of test in each chip.In an embodiment of the 12.5k magnification ratio that uses online SEM, can in 480 * 480 pixel images of each sample position, have 98 contacts.For in 35 zones each five sample position are arranged, detect 17,150 contacts.

Figure 17 is expression has the semiconductor device of the contact hole that will detect according to the present invention a sectional view.Figure 17 represents that 64M DRAM buries the formation technology of contact.Field oxide 131 has defined the active area that is formed on the Semiconductor substrate 130.Grid 132 is formed on the active area and with separator 133 and covers.On this surface, form after first insulating barrier 134 of high temperature oxide film, form first contact hole 137, as the direct contact that is used for bit line 135.Form after the bit line 135, on this surface, form second insulating barrier 136,, and be formed for second contact hole 138 of word line as BPSG.

An example as the present invention detects detects the contact of burying that is used to form word line in 64M DRAM process for making.As shown in figure 17, detection can also be carried out direct contact 137, or carries out after the developing process of the photoresist figure that is used to form these contact holes.

In contact fault detection method of the present invention, at first on the size basis of detected feature, the diameter of circular contact hole for example is to each choice of location optimized image size that will detect.In one embodiment, general SEM image comprises 480 * 480 pixels.Can obtain this image for each numeral number position of Figure 16.According to size between the contact hole and distance, determine the optimized image size of the contact hole that each is independent.Figure 18 represents to be used for the example of contact image of online SEM of 12.5K magnification ratio of a sample position of semiconductor device.It is to be made of 480 * 480 pixels, and the numeral of the contact of describing in the image is 98, promptly in a horizontal direction 14 and in vertical direction 7.

Determining optimum resolution, is to determine optimum resolution on the basis of the distance between contact hole and hole and detect in detected characteristic size.For example, in a system, each pixel can be differentiated approximate 12nm in SEM.At present, well-known, contact hole can have the diameter of 200nm magnitude.Select Cover Characteristics pixel quantity with guarantee can be in image irregularly shaped in the detected characteristics.For example, have in the grid of equispaced under 100 hole situations in detected zone, can use one group 100 the sub-grids of 48 * 48 pixels, to cover all holes, comprise the interval between the hole, wherein each sub-grid is relevant with a hole.The rectangular grid of level or vertical line or grid can be superimposed upon on 480 * 480 cell arrays, to be formed for detecting 100 48 * 48 sub-grids of pixel in each hole.

According to the present invention, definite then 48 * 48 pixel grids are enough differentiated any scrambling in the detected hole.The size in hole is compared with the amount at interval in each sub-grid, is enough to analyze the hole with the quantity of the pixel that determines whether coverage hole itself.By cut apart the evaluation size with the quantity of the pixel of coverage hole is that the diameter in hole is determined resolution.This resolution and threshold, for example whether 12nm/ pixel threshold value is enough with definite this resolution.

After determining pixel resolution, can use the size of network with location and definite contact hole.In one embodiment, the vertical and horizontal line in use grid or the lattice structure is with the location contact hole.

This contact position referring to representation module 60d is discerned the Figure 18 that handles, grid or grid are located on the contact image of aiming in the matrix, in a certain region of search, adjust trunnion axis and vertical axis spacing (pitches), thereby each contact is placed on each grid.At this moment, can control spacing by the quantity that increases or reduce the pixel that produces contact image.The region of search of grid line preferably is set to comprise the zone of the identical figure of repetition contact hole.

Referring to Figure 18, use the contact position identification of grid search to handle to determine each grid cell or sub-grid to constitute by at least 32 pixels in the horizontal scale direction and at least 62 pixels in the vertical dimension direction, the region of search is to move empty trunnion axis grid line 150 in the scope by at least 32 pixels in comprising trunnion axis and at least 62 pixels in the vertical axis and empty vertical axis grid line 152 is determined, detect the position of lowest number beam signal value thus, thereby each contact in the contact image is not subjected to the interference of grid line.

In one embodiment, can be by carrying out grid search at primary importance location vertical line or horizontal line.Accumulative total along the brightness value of this line to determine the total brightness of this line.This line moves to the next position then.For example, vertical line can move to the next position along trunnion axis.In this position, added up again along the brightness value of vertical line.In each position, total luminance value and predetermined threshold and former summation are compared.Suppose that the hole has the brightness that is higher than background, the increase of brightness can arrive the edge in hole in order to expression.In another embodiment, the hole has the brightness that is lower than background.This processing can continue to pass through whole lattice structure, with the size and dimension in location and/or definite each hole.Calculated in one direction after all summations, can repeat to handle size, shape and position that result's portrayal is portalled other direction.Can use this information in the processing procedure afterwards that is used for various purposes.By position and the shape of having determined the hole, can eliminate the unnecessary processing of the pixel that has nothing to do with the hole.And, if in processing procedure afterwards, discern fault, can be easy to determine not conform to the accurate position of checkerwork cell.

After carrying out contact position identification, the initial point of initial mesh unit as shown in Figure 18 for example, is pixel XO=13 on the trunnion axis and the pixel YO=23 on the vertical axis.Unit with same size can compare, the reason why Here it is carries out above-mentioned contact position identification.

Grid cell can be used in various the setting, that is, as shown in figure 19, wherein contact hole 153 is placed on a grid cell skipping a grid cell between two unit, or as shown in figure 20, wherein at least two contact holes 153 can be placed on the grid cell.In addition, if the figure of image repeats on each unit area, the location recognition method of above-mentioned grid method can use in various picture shapes, and for example square or degree of lip-rounding liner (pad) image are opposite with above-mentioned circular contact image.

Figure 18 represents that being used for the grid setting according to the present invention discerns the SEM image of the osculating element of handling (480 * 480 pixel) to carry out contact position.As mentioned above, in this embodiment, at present the grid cell of test is set to 32 * 62 pixels, and number (XO YO) is (13,23) to initial pixel.Determine above-mentioned grid cell settings by mobile and horizontal grid line 150 in the hunting zone of being determined by above-mentioned each grid line and vertical gridlines 152, this can be by to be approximately 60 pixels and about 30 pixel settings respectively corresponding to each spacing of grid cell.In another embodiment, analyze every line with the minimum brightness value of identification, to determine the position in hole corresponding to each grid line.

It is dissimilar that Figure 19 and the above-mentioned grid of 20 expressions are provided with, and Figure 21 has been expressed as the contact Luminance Distribution figure of explanation generation and has represented osculating element with pixel unit.Figure 22 is illustrated in and removes background luminance with before this figure of normalization, the first Luminance Distribution figure in the grid cell, and its expression is with respect to the brightness value of vertical axis.Figure 23 represents the Luminance Distribution figure of Figure 22, and it has the contact threshold value that is provided with after removing the background luminance value.In present test, threshold value electronic signal value is set to 5, and the threshold value pixel number is 20, as shown in figure 23.Detected contact hole is crossed over the pixel 20-40 along vertical axis.

Figure 24 represents to be used to remove the Luminance Distribution figure of SEM image of the contact of the Figure 18 after the background value.Figure 25 is expression contains the result that is encoded of the contact fault detection of carrying out of the present invention in the contact of Figure 18 a form.Circle contact among Figure 24 is complementary with the position that is defined as contact fault among code 4 and Figure 25.

Figure 26 is the sample position of expression with respect to each wafer, the chart of the part of the contact fault testing result of each sample position shown in Figure 15 in test has at present wherein indicated corresponding to the quantity according to all contacts of each criteria for classification of contact of the present invention.Just, corresponding to per five positions in each chip or the test zone, listed the quantity of every kind of classification in the hole of in this position, finding.For example, in the position (1,3), have 87 contact holes to be classified as type D, 3 hole sorts are type E, and 5 hole sorts are that type G and 3 hole sorts are type H.Should be noted that in each position 98 holes are classified and detect, on 35 surveyed areas, detect and add up to 17,150 holes.In one embodiment, owing to saved the processing time by the present invention, so this test can be finished in one hour.Therefore this method is applicable to batch process.

Contact pattern computing module 60e (1) is used to each grid cell of above-mentioned special grid to produce the first Luminance Distribution figure of above-mentioned detected electrons signal value.Background value is removed module 60e (2) and is used for by producing the second Luminance Distribution figure from the first Luminance Distribution figure subtracting background value from the first Luminance Distribution figure.

Calculate the first Luminance Distribution figure and the second Luminance Distribution figure by using corresponding to the digitized electronic signal value of each pixel that is included in each grid cell.But, the electronic signal value that obtains from each grid cell comprise from corresponding contacting electronic signal value with from surrounding the electronic signal value that this perimeter that contacts produces.In the present invention; for obtaining only to comprise accurate electronic signal value from the inner brightness of contact in the grid cell; from the Luminance Distribution figure, deduct background electronic signal value, promptly surround the zone of contact, to produce the normalization second Luminance Distribution figure from the contact area outside.This is referred to as " colour effect " and removes.

In one embodiment of the invention, the removal of calculating of contact Luminance Distribution figure and background value is to carry out according to following equation (1) by module 60e.

$Y=\frac{X}{\sqrt{(B/B_C)X_C}}---\left(1\right);$ Wherein

X is the summation of the above electronic signal value of the predetermined threshold in the grid cell;

B is the summation of the following electronic signal value of the predetermined threshold in the grid cell;

B _CBe the quantity that has the electronic signal of the value that is lower than predetermined threshold in the grid cell;

X _CBe the quantity that has the electronic signal of the value that is higher than predetermined threshold in the grid cell; With

Y is the electronic signal value that has background compensation in the grid cell.

In equation (1), above-mentioned predetermined value can be determined by removing background value and reaching accurately measurement result.In one embodiment, for example, this value is 100, but is not limited to this value.

The Y value, promptly the result of equation (1) is the summation of the electronic signal of the compensation in each grid cell.In one embodiment, can the lower limit and the upper limit be set for the Y value in the equation (1).If be the value calculated of specific contact under lower limit, then this contact is concluded it is out of order.In one embodiment, this type list below predetermined lower bound that reads is shown not opening contact hole fault.

Equation (1) generally is used to have the detection of erose contact hole.For example, equation (1) is used in the hole and forms the detection that is used to form the photoresist layer of contact hole before.

In another embodiment, contact pattern calculating and background value removal are to carry out according to following equation (2)-(4).

${\left(P_K^N\right)}^{\′}=\frac{\mathrm{\Σ}{P}_{n=h_i^{\mathrm{Nnk}}}}{(h_f^N-h_i^N)}---\left(3\right);$

(4); Wherein:

N is the trunnion axis pixel number;

K is the vertical axis pixel number;

Pnk is the digitized signal value at a pixel of trunnion axis position n and k place, vertical axis position;

N is analyzed number of grid;

h _i ^NIt is the initial pixel number in the trunnion axis in the grid cell; With

h _f ^NBe the final pixel quantity in the trunnion axis in the grid cell.

Below with reference to Figure 21 and 22 explanation equation (2)-(4).Figure 21 is the diagram of the pixel unit in the grid cell of the expression contact that is used to calculate contact Luminance Distribution figure according to the present invention.Figure 22 is the curve chart of expression for the first Luminance Distribution figure in the grid cell that calculates before the contact image subtracting background value of Figure 18.In one embodiment, the Luminance Distribution figure is by moving to discrete position along an axle and will adding up and the pixel brightness summation is produced with respect to cutting apart along pixel axle pixel number along the brightness value of vertical direction in each position.For example, the figure of Figure 22 can form by passing pixel location along the vertical axis stepping and the pixel brightness of horizontal direction being added up.In the figure of Figure 22, the result is near the Luminance Distribution figure that has peak value the median that exists of the contact hole in expression specifiable lattice unit.This contact hole extends to pixel location 44 from about pixel location 16, therefore passes about 28 pixels in vertical direction.This figure has slight decline in the center in hole in the brightness of the top of peak value, it is illustrated in the lowering of luminance of the floor detection in hole.The shape of this Luminance Distribution figure represents it is normal contact hole.

Value (P from equation (3) _K ^N) ' be the average electrical subsignal value of each pixel among the vertical axis pixel number k.This is by will be corresponding to vertical axis pixel number k line (Figure 21; The whole summation of the digitalized electron signal value of each pixel k=20), i.e. the height of the curve among Figure 22 is cut apart according to the quantity of the horizontal pixel of vertical axis position k and to be obtained, and wherein the quantity at the horizontal pixel of vertical axis position k is to pass through h _f ^N-h _i ^NProvide.Figure 22 represents from the figure as a result of equation (3) generation.P _m ^NBe (P _K ^N) ' minimum value, i.e. brightness background or baseline value.Therefore, P _k ^NEvery pixel average electrical subsignal value of expression subtracting background value.

Figure 23 is at the curve chart according to the second Luminance Distribution figure after equation (2) the subtracting background value.Figure 24 represents the normalization second Luminance Distribution figure for the contact in the contact image of Figure 18.

In one embodiment, contact fault characterization processes of the present invention is also analyzed the result of equation (2)-(4), thereby whether has fault and will contact classification according to them, if then it belongs to fault type.The second Luminance Distribution figure (Figure 24) of analyzing each hole is with the identification fault with its classification.

In one embodiment, as shown in figure 23, threshold value, for example 5, put on the second Luminance Distribution figure (the every pixel average electrical subsignal value after the subtracting background value).The evaluation size CD of contact ^NBe defined as length (or width) at threshold value place peak value.As shown in figure 23, be 5 by threshold value is set, the evaluation size CD of contact ^NBe CD ^N=40-20=20 pixel.This evaluation size CD ^N, can be the diameter of contact hole for example, can calculate from following equation (5).

Wherein:

v _i ^NIt is the initial pixel number of vertical axis in the grid cell;

v _f ^NBe the vertical axis final pixel quantity in the grid cell;

$P_k^N={\left(P_k^N\right)}^{\′}-P_m^N;$ With

w _k ^NWhether the expression pixel brightness on threshold value, is specially:

Then, according to following equation (6), calculate the average pixel brightness BSE that is higher than threshold value for all pixels ^N

${\mathrm{BSE}}^N=\frac{\underset{k=v_i^N}{\overset{K=v_F^N}{\mathrm{\Σ}}}{P}_k^N{w}_k^N}{{\mathrm{CD}}^N}---\left(6\right).$

Should be noted that equation (5) and (6) expression another detection method with respect to equation (1).Average pixel brightness BSE in the equation (6) ^NIt is the analog quantity of the value Y of calculating in equation (1).And, the value CD in equation (5) and (6) ^NReplace the value X in the equation (1) _C

To the contact calculating pixel quantity CD that detects ^NWith average pixel brightness value BSE ^NAfterwards, can use the condition of their classification contacts.In one embodiment, can be pixel number CD ^NHigher limit NOC2 and lower limit NOC1 are set.These restrictions can be used for determining the scope of the normal pixel number accepted that contacts.Can also be average pixel brightness BSE ^NRestriction is set.Higher limit NOT2 and lower limit NOT1 can be used for determining the scope of the average pixel value accepted that normally contacts.

The value CD of each contact of analyzing ^NAnd BSE ^NCompare will contact classification with their scopes separately.In one embodiment, each contact is categorized as one of nine possibility types, this value of depending on CD ^NAnd BSE ^NComparison with their scopes separately.The classification of the type of nine possible conditions and their correspondences and an example of digital code are made form such as table 1.

Classification	(BSE N)≤(NOT1)	(NOT1)≤(BSE N)≤( NOT2)	(BSE N)≤(NOT2)
				(CD N)≤(NOC1)	A-type (code 1)	B-type (code 2)	C-type (code 3)
(NOC1)≤(CD N) ≥(NOC2)	D-type (code 4)	E-type (code 5)	F-type (code 6)
				(CD N)≤(NOC2)	G-type (code 7)	H-type (code 8)	I-type (code 9)

Table 1 contact classification

Three conditions of the three row definition contact hole degree of depth of table 1.They are arranged according to reducing depth order.Just, first row definition three conditions, i.e. the type A of dark relatively contact hole, D and the G.Secondary series comprises three conditions of the normal contact degree of depth, i.e. type B, E and H.Three conditions of the contact degree of depth that the 3rd row definition is not enough, i.e. Type C, F and I.The contact hole or the non-homogeneous contact hole of these contact hole type General Definition part openings.The row of table 1 is arranged according to the depth order that increases contact hole.First row comprises type A, B and C contact hole type, has not enough minor diameter.Second classification comprises type D, E and F, the contact hole that definition has normal diameter.The 3rd classification comprises type G, H and I, and definition had large diameter contact hole.

As shown in table 1, the E-classification of type is to pass through CD ^NAnd BSE ^NBe positioned at that their preset range separately makes.Other type that is arranged in outside this scope in one or two value is sorted in one of all the other types, and this can be used for representing the intensity of variation or the type of contact fault.

Display 60g can show by the normal contact of contact fault detection module 60f classification and/or the sorting result of contact fault as a result.This result can be expressed as the digital value about each position contacting.

Figure 25 represents the form for the example of the classification of the contact hole of Figure 24 and pixel location.Each contact is normally or out of order can the expression with the digital code relevant with corresponding each position contacting of the second Luminance Distribution figure.Code " 5 " expression type E means normal contact, code " 4 " expression type D contact fault.In one embodiment, type D represents not opening contact.The initial level axle pixel number of each grid cell of X value representation of Figure 25, the initial vertical axis pixel number of Y value representation.Figure 26 is illustrated in the form of five locational testing results of the present invention in each of seven zones on the semiconductor wafer.The quantity of the contact of each classification type in this each position of table expression.

CD ^NAnd BSE ^NValue can be used in a different manner the contact classification.Just, a special contact falls within the special type that the interior classification of type of this classification can describe contact fault in detail.For example, as the BSE of a contact ^NWhen minimum value NOT1 is following, generally represents not opening contact hole, and this contact hole is categorized as among type A, D and the G one.Work as BSE ^NDuring greater than maximum NOT2, this hole is considered to open, but still can not accept for some reason.For example, this hole may have irregularly shaped, broadens or narrows down such as the bottom towards the hole.In this case, this hole will be classified as one of Type C, F and I.

Equally, work as CD ^NIn the time of under minimum value NOC1, indication window has fault, may be too narrow or has some irregular shape, and is for example oval.If CD ^NOn maximum NOC2, represent that then this hole is irregularly shaped.

Figure 27 comprises the flow chart of logic flow of treatment process that the technology of semiconductor device is made in expression according to one embodiment of present invention.At first, in the special processing step in the production process of semiconductor device process, at specific insulating barrier, deposit photoresist and carry out forming after the photoetching photoresist figure (S40) on nitride film or the oxide-film for example corresponding to contact hole.The photoresist figure is undertaken by exposure-processed and development treatment.

Then, make with photoresist figure make etching mask, the insulating barrier below the corrosion photoresist figure is to form contact hole (S42).Then, clean the inside of contact hole, and wafer is moved to according among the online SEM of the present invention, carry out aforesaid according to contact hole fault detect of the present invention.Then, with the inside of electric conducting material filling contact hole, the processing afterwards of being used for producing the semiconductor devices again.

Figure 28 represents the flow chart of logic flow of an embodiment of contact fault detection method of the present invention.In step 500, read the parameter that this technology is used.In one embodiment, the parameter of this technology use is as follows:

The Y-direction of principal axis pixel number of N=SEM image

The X-direction of principal axis pixel number of M=SEM image

Y-on the Y-direction of principal axis of VP (vertical interval)=grid is coupling and touches spacing

X-axis contactinterval on the X-direction of principal axis of HP (level interval)=grid

MX=X-axle grid search pixel coverage

MY=Y-axle grid search pixel coverage

The basic threshold value of the contact performance figure on the bse=unit grid

The lower limit of the normal contact performance figure of NO1=brightness

The higher limit of the normal contact performance figure of NO2=brightness

The lower limit of the normal contact performance pattern pixel of CD1=quantity

The higher limit of the normal contact performance pattern pixel of CD2=quantity

XN=in wafer chip or target (shot) unit in total SEM amount of images (counting) of detecting

Total SEM amount of images (counting) that YN=detects in chip or target

X=is in the SEM picture order of wafer chips or object element detection

The SEM picture order that Y=detects in wafer or target

Cdata[j] [i]=at the SEM image signal level of (whenever) unit pixel

Then, in step 502, X-axle value is initialized to zero, and in step 504, Y-axle value is initialized to zero.Detection system continues along the Y-axle in the inner ring road that is formed by step 506-520, till reaching maximum Y-axle value.Then, increase X-axle value, and repeat inner ring road by all Y-axle values.At last, when arriving last X and Y-axle value, outer ring finishes.In the inner ring road of Figure 28, in step 506 (X, Y) and cdata[j] [i] locate to read the SEM view data, as the detailed description of Figure 29.Should be noted that grid method described here has used the rectangular mesh structure that has vertical X and Y-axis.Should be understood that rectangular mesh not necessarily.Also can use other mesh shape.For example, can use triangle or trapezoidal.Select network to guarantee to detect any periodic repetitive pattern of contact.

Then, in the step 508 of Figure 28, determine the contact hole position.Step 508 has detailed expression in Figure 30 A-30D.Identification contact hole position comprises type and the figure of selecting to be used to detect the grid of contact hole.Technology shown in Figure 30 A-30D moves along first pixel of direction (level) of selecting with connecing a pixel, and is accumulated at all pixel values in second orthogonal direction (vertically).When detecting the significant variation (jump) of brightness, determined the edge in hole.Continue this technology till the remarkable decline that detects brightness is with another edge of determining the hole.Use this method till all holes are positioned.Should be noted that in the step 550 and 582 of Figure 30 A-30D, used the absolute value of luminance difference.This is that this is very important to determining contact position because it is the amplitude of luminance difference or contrast difference.This method is adapted to determine that the hole is the different conventions of high or low brightness.

In the step 514 of Figure 28, calculate contact hole graph.This technology is illustrated among Figure 31 A-31D in detail.Figure calculates by analyzing each contact hole, and discerns in conjunction with the described technology of Figure 30 A-30D according to above-mentioned.For calculating a distribution pattern in each hole.In one embodiment, produce figure by being accumulated in the direction in brightness along each position of another orthogonal direction.At the brightness value of each position by the mean deviation drafting pattern.Should be noted that and in the flow chart of Figure 31 A-31D, used general variable F and F2.According to a preferred embodiment of the invention, these variablees and the variable BSE that in above-mentioned equation (5) and (6), determines respectively ^NAnd CD ^NBe interchangeable.

In the step 516 of Figure 28, detect contact hole according to the present invention.This technology has been represented in Figure 32 A-32B in detail.As mentioned above, analyze the value determined according to Figure 31 A-31D with according to nine contact types to each hole sort.As mentioned above, in Figure 32 A-32B, variable F and F2 can use BSE ^NAnd CD ^NExchange.

Referring to Figure 28, in step 518, Y-axle value increases, and determines whether to have arrived maximum Y-axle value in step 520 again.If not, flow process turns back to the top of inner ring road.If, in step 522, increasing X-axle value, flow process process square 524 turns back to the top at the outer ring of the step 504 of initialization Y-axle value.When outer ring finished, the result of characterization processes can show in step 526.

As mentioned above, Figure 29 is the flow chart of the details that reads SEM view data step 506 among expression Figure 28.In step 528, index j is initialized to zero, and in step 530, index i is initialized to zero.Cdata[j] [i] read in step 532, and index i increases in step 534.Determine whether that in step 536 index i has reached its maximum M.If not, then flow process turns back to the step 532 of reading of data once more.If then index j increases, in step 540, determine whether that j has reached its maximum N in step 538.If then this process finishes.If not, flow process turns back to step 530, once more index i be initialized as zero and this process proceed.

In one embodiment, contact fault of the present invention detects and is forming contact hole and cleaning contact hole inside (after cleaning detects: ACI) carry out afterwards.Also can be in the development treatment of the photoresist figure that is formed for forming contact hole (develop detect after: ADI) on the insulating barrier that exposes on the wafer, carry out.

The present invention not only goes for above-mentioned contact hole, can also be applicable to be used to connect the direct through hole that contacts with conductive layer with Semiconductor substrate of all contact holes in each step.In addition, the present invention also is applicable in the figure moulding trouble shooting of the optical treatment process that is used for the contact hole moulding after development treatment.

In addition, except circular contact hole, the present invention also can be used for checking figure by all kinds of the graph image that detects regular repetition.

According to the present invention, under situation not by naked eyes or microexamination image, can be accurately and correctly detect the existence of contact fault by digital value.For contact hole with high aspect ratio, can be easily and determine contact fault exactly.In addition, carry out at short notice for the contact fault detection on entire wafer surface, and the testing result of contact fault is provided, showed high efficiency and productivity ratio for the batch production systems line.

To those skilled in the art, under the situation that does not break away from the spirit or scope of the present invention, obviously can make various remodeling and change.Therefore, of the present invention various remodeling and change and their equivalent in the scope that falls into appended claims contained in the present invention.

Claims (48)

1. detect the method for at least a portion of semiconductor wafer, comprising:

The scanning electron microscope image data of the part of read semiconductor wafer;

The view data of feature on the identification semiconductor wafer in being used for the partial data of semiconductor wafer;

Calculate the mean flow rate of the pixel relevant with this feature from the view data of this feature;

Described parameter is compared with the acceptable value scope of this parameter;

According to the acceptable value scope of this parameter relatively with this tagsort.

2. method according to claim 1, wherein said feature are the contact holes in the integrated circuit.

3. method according to claim 2, if wherein described parameter outside the acceptable value scope of this parameter, then this contact hole can be categorized as and not open.

4. method according to claim 1, if wherein described parameter outside the acceptable value scope of this parameter, then this feature can be categorized as fault.

5. method according to claim 1, if wherein described parameter within the acceptable value scope of this parameter, then this tagsort is acceptable.

6. method according to claim 1, wherein the scanning electron microscope image data produce from secondary electron and back scattered electron.

7. method according to claim 1 also comprises the image pixel Luminance Distribution figure that calculates this feature.

8. method according to claim 7, computed image pixel brightness distribution pattern comprise subtracting background brightness value in the brightness value of pixel from the zone that comprises this feature.

9. method according to claim 1 also comprises:

Calculate the size of this feature from the view data of this feature;

This second parameter is compared with the acceptable value scope of this second parameter; With

According to the acceptable value scope of this second parameter relatively with this tagsort.

10. method according to claim 9, wherein only in the acceptable value scope of first parameter in first parameter and the acceptable value scope of second parameter in second parameter in the time, then this feature is classified as acceptable.

11. method according to claim 1 also comprises and uses coordinate system to make this feature characterization, described characterization comprises: be superimposed with coordinate system on the image of the described part of semiconductor wafer; With

In a plurality of positions of first along coordinate system, analysis is along the brightness value of the pixel of second setting of coordinate system.

12. method according to claim 11, wherein said analysis comprise the brightness value of accumulative total along the pixel of second setting.

13. method according to claim 12, wherein said analysis also comprise the variation of detection along the brightness value of a plurality of positions accumulative total of first, to detect this feature.

14. method according to claim 11, wherein said analysis comprise the brightness value along the pixel of second setting is averaged.

15. method according to claim 14, wherein said analysis also comprise the variation of detection along the average brightness value of a plurality of positions of first, to detect this feature.

16. method according to claim 11, wherein said characterization comprise the size of determining this feature.

17. method according to claim 11, wherein said characterization comprise the position of determining this feature.

18. method according to claim 11, wherein said characterization comprises the figure of discerning a plurality of these features.

19. method according to claim 18, wherein said figure are periodic figures.

20. method according to claim 11, wherein coordinate system is a rectangular coordinate system.

21. method according to claim 11, wherein coordinate system is a triangular coordinate system.

22. method according to claim 11, wherein coordinate system is a trapezoid coordinate system.

23. method according to claim 1, wherein the scanning electron microscope image data are forms of digitlization pixel gray value.

24. method according to claim 1, wherein the scanning electron microscope image data are forms of digitlization coloud coding pixel value.

25. be used for detecting the device of semiconductor wafer at least a portion, comprise:

Be used to read the device of scanning electron microscope image data of the part of this semiconductor wafer;

The device that is used for the view data of the feature on the identification semiconductor wafer in the partial data of this semiconductor wafer;

Be used for calculating the device of the mean flow rate of the pixel relevant with this feature from the view data of this feature;

Be used for device that this parameter is compared with the acceptable value scope of this parameter;

Be used for according to the acceptable value scope of this feature relatively with the device of this tagsort.

26. device according to claim 25, wherein this feature is the contact hole in the integrated circuit.

27. device according to claim 26, if wherein this parameter is outside the acceptable value scope of this parameter, the device of this feature that then is used to classify can be categorized as this contact hole not to be opened.

28. device according to claim 25, if wherein this parameter is outside the acceptable value scope of this parameter, the device of this feature that then is used to classify can be categorized as fault with this feature.

29. device according to claim 25, if wherein this parameter is within the acceptable value scope of this parameter, the device of this feature that then is used to classify is acceptable with this tagsort.

30. device according to claim 25, wherein the scanning electron microscope image data produce from secondary electron and back scattered electron.

31. device according to claim 25 also comprises the device of the image pixel Luminance Distribution figure that is used for calculated characteristics.

32. device according to claim 31, the device that wherein is used for computed image pixel brightness distribution pattern comprise the device that is used for from the brightness value subtracting background brightness value of the zone pixel that comprises this feature.

33. device according to claim 25 also comprises:

Be used for calculating the device of the size of this feature from the view data of this feature;

Be used for device that second parameter is compared with the scope of the acceptable value of this second parameter;

Be used for according to comparing device this tagsort with the acceptable value scope of this second parameter.

34. device according to claim 33, wherein only in the acceptable value scope of first parameter in first parameter and in the acceptable value scope of second parameter in second parameter, then this feature just can be categorized as acceptable.

35. device according to claim 25 also comprises and uses the device of coordinate system with this feature characterization, the described device that is used for characterization comprises:

Be used on the part of semiconductor wafer, being superimposed with the device of coordinate system;

Be used for device along a plurality of position analyses of first of coordinate system along the brightness value of the pixel of second setting of coordinate system.

36. comprising, device according to claim 35, the wherein said device that is used to analyze be used for the device of accumulative total along the brightness value of the pixel of second setting.

37. device according to claim 36, the device that wherein is used to analyze also comprise the device that is used to detect along the variation of the brightness value of a plurality of positions accumulative total of first of coordinate system.

38. comprising, device according to claim 35, the wherein said device that is used to analyze be used for device that the brightness value along the pixel of second setting is averaged.

39. according to the described device of claim 38, the wherein said device that is used to analyze also comprises the device that is used to detect along the variation of the average brightness value of a plurality of positions of first.

40. device according to claim 35, the wherein said device that is used for characterization comprise the device of the size that is used for definite this feature.

41. device according to claim 35, the wherein said device that is used for characterization comprise the device that is used for determining this feature locations.

42. device according to claim 35, the wherein said device that is used for characterization comprise the device of the figure that is used to discern a plurality of features.

43. according to the described device of claim 42, wherein said figure is periodic figure.

44. device according to claim 35, wherein coordinate system is a rectangular coordinate system.

45. device according to claim 35, wherein coordinate system is a triangular coordinate system.

46. device according to claim 35, wherein coordinate system is a trapezoid coordinate system.

47. device according to claim 25, wherein the scanning electron microscope image data are forms of digitlization pixel gray value.

48. device according to claim 25, wherein the scanning electron microscope image data are forms of digitlization color coding pixel value.

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