CN110044249A - A kind of film thickness measuring method, system and chemical mechanical polishing apparatus - Google Patents
A kind of film thickness measuring method, system and chemical mechanical polishing apparatus Download PDFInfo
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- CN110044249A CN110044249A CN201910365388.8A CN201910365388A CN110044249A CN 110044249 A CN110044249 A CN 110044249A CN 201910365388 A CN201910365388 A CN 201910365388A CN 110044249 A CN110044249 A CN 110044249A
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- film thickness
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- pattern
- polishing
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B37/00—Lapping machines or devices; Accessories
- B24B37/005—Control means for lapping machines or devices
- B24B37/0053—Control means for lapping machines or devices detecting loss or breakage of a workpiece during lapping
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B37/00—Lapping machines or devices; Accessories
- B24B37/04—Lapping machines or devices; Accessories designed for working plane surfaces
- B24B37/042—Lapping machines or devices; Accessories designed for working plane surfaces operating processes therefor
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
- G01B7/02—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness
- G01B7/06—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness for measuring thickness
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
- G01B7/02—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness
- G01B7/06—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness for measuring thickness
- G01B7/10—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness for measuring thickness using magnetic means, e.g. by measuring change of reluctance
- G01B7/105—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness for measuring thickness using magnetic means, e.g. by measuring change of reluctance for measuring thickness of coating
Abstract
The present invention is suitable for chemical Mechanical Polishing Technique field, provides a kind of film thickness measuring method, system and chemical mechanical polishing apparatus, and wherein method includes: the output signal for obtaining film thickness sensor and the mapping relations of wafer film thickness；Using the mapping relations, the signal value exported when by the film thickness sensor on-line measurement is converted to film thickness value.It realizes quickly and accurately online film thickness measuring.
Description
Technical field
The invention belongs to chemical Mechanical Polishing Technique field more particularly to a kind of film thickness measuring methods, system and chemical machine
Tool burnishing device.
Background technique
Integrated circuit is generally formed by sequential deposition conductive layer, semiconductor layer or insulating layer on Silicon Wafer.To
Crystal column surface is set to be deposited with the film of packing layer formation.In manufacturing process, need to continue planarization packing layer until exposing pattern
The top surface of change, to form conductive path between raised design.
Chemically-mechanicapolish polishing (Chemical Mechanical Planarization, CMP) is obtained in IC manufacturing
Obtain a kind of means of global planarizartion.As shown in Figure 1, chemically mechanical polishing unit includes rubbing head 10, polishing disk 20, feed flow mould
Block 30 and deposit piece module (Loadcup) 40.Wafer is stored at piece module 40 before polishing starts, and rubbing head 10 is from depositing piece mould
Block 40 loads moving radially to the top of polishing disk 20 along polishing disk 20 after wafer.During polishing, rubbing head 10 is by wafer
Pressing is on the polishing pad that 20 surface of polishing disk covers, and rubbing head 10 makes rotating motion and yearns for along the diameter of polishing disk 20
It is multiple mobile, while polishing disk 20 rotates, feed flow module 30 sprays polishing fluid to pad interface.In the chemical action of polishing fluid
Under, make wafer with polishing pad friction to be polished by the relative motion of rubbing head 10 and polishing disk 20.
During CMP planarization, the Thickness Variation and film thickness value of real-time monitoring wafer are needed, to take corresponding polishing
Technique, avoided the occurrence of throwing or polishing is incomplete.Film thickness detection method can use eddy current detection, the original of eddy current detection
Reason is sensor in inswept wafer, and the metallic diaphragm of crystal column surface, which can induct, to be vortexed and become the magnetic field of sensor generation
Change, so that sensor measurement vortex variation is when removing the metallic diaphragm by polishing to survey the film thickness of metallic diaphragm
Amount.However due to the thickness very little of film layer, the order of magnitude is even more small in the micron-scale, causes measurement accuracy not high, accuracy is low.
Summary of the invention
In view of this, the embodiment of the invention provides a kind of film thickness measuring method, system and chemical mechanical polishing apparatus, purport
At least solving one of the technical problems existing in the prior art.
The first aspect of the embodiment of the present invention provides a kind of film thickness measuring method, comprising:
Obtain the output signal of film thickness sensor and the mapping relations of wafer film thickness；
Using the mapping relations, the signal value exported when by the film thickness sensor on-line measurement is converted to film thickness value.
The second aspect of the embodiment of the present invention provides a kind of membrane thickness measuring system, comprising:
Demarcating module, for obtaining the output signal of film thickness sensor and the mapping relations of wafer film thickness；
Output module, for utilizing the mapping relations, the signal value exported when by the film thickness sensor on-line measurement
Be converted to film thickness value.
The third aspect of the embodiment of the present invention provides a kind of chemical mechanical polishing apparatus, comprising:
Polishing disk is covered with the polishing pad for being polished to wafer；
Rubbing head, for keeping wafer and pressing wafer in the polishing pad；
Film thickness sensor, for measuring wafer film thickness and output signal value during polishing；
Controller, for obtaining the output signal of film thickness sensor and the mapping relations of wafer film thickness；And it is reflected described in utilizing
Relationship is penetrated, the signal value exported when by the film thickness sensor on-line measurement is converted to film thickness value.
The fourth aspect of the embodiment of the present invention provides a kind of control equipment, including memory, processor and is stored in
In the memory and the computer program that can run on the processor, when the processor executes the computer program
The step of realizing film thickness measuring method as described above.
5th aspect of the embodiment of the present invention provides a kind of computer readable storage medium, the computer-readable storage
Media storage has computer program, and the computer program realizes the step of film thickness measuring method as described above when being executed by processor
Suddenly.
The beneficial effects of the present invention are: realizing quickly and accurately online film thickness measuring, measurement accuracy is improved.
Detailed description of the invention
It will be apparent and be easier to understand by made detailed description, advantages of the present invention in conjunction with the following drawings,
But these attached drawings are only schematical, are not intended to limit protection scope of the present invention, in which:
Fig. 1 is a kind of top view for chemically-mechanicapolish polishing unit；
Fig. 2 is the sectional view for the chemical mechanical polishing apparatus that one embodiment of the invention provides；
Fig. 3 is the schematic diagram of the sampling process of film thickness sensor；
Fig. 4 is the schematic diagram of the output signal of film thickness sensor；
Fig. 5 is the flow diagram for the film thickness measuring method that one embodiment of the invention provides；
Fig. 6 is the schematic diagram for the crystal column surface subregion that one embodiment of the invention provides；
Fig. 7 is the film thickness shape appearance figure that one embodiment of the invention provides；
Fig. 8 is the signal shape appearance figure that one embodiment of the invention provides；
Fig. 9 is the controller connection figure that one embodiment of the invention provides；
Figure 10 is that the distance that one embodiment of the invention provides calculates schematic diagram；
Figure 11 is the mapping relations figure that one embodiment of the invention provides；
Figure 12 is the flow diagram for the film thickness measuring method that one embodiment of the invention provides；
Figure 13 is the structural schematic diagram for the membrane thickness measuring system that one embodiment of the invention provides；
Figure 14 is the schematic diagram for the control equipment that one embodiment of the invention provides.
Specific embodiment
Combined with specific embodiments below and its attached drawing, technical solution of the present invention is described in detail.It records herein
Embodiment be specific specific embodiment of the invention, for illustrating design of the invention；These explanations are explanatory
With it is illustrative, should not be construed as the limitation to embodiment of the present invention and the scope of the present invention.Except the implementation recorded herein
Exception, those skilled in the art can also be based on the claim of this application books and its specification disclosure of that using aobvious and easy
The other technical solutions seen, these technical solutions include any obviously replacing using to making for the embodiment recorded herein
The technical solution changed and modified.
In order to illustrate technical solutions according to the invention, the following is a description of specific embodiments.
One embodiment of the invention provides a kind of film thickness measuring method for chemically mechanical polishing, and this method is suitable for making
Wafer film thickness is measured with electric vortex type film thickness sensor, and crystal column surface film layer is metal material, such as copper, tungsten, aluminium, tantalum, titanium
Deng.Crystal column surface thicknesses of layers can be 0.01 μm to 50 μm.
Eddy current detection can measure polishing as contactless measurement while not destroying crystal column surface film layer
Film thickness value in the process.Electric vortex type film thickness sensor can induced magnetic field variation, and export with film thickness have specific corresponding relationship
Voltage signal.
As shown in Fig. 2, wafer w can be polished or planarize on the polishing disk 20 of chemical mechanical polishing apparatus.Chemistry
Mechanical polishing apparatus includes rubbing head 10 for keeping wafer and wafer being driven to rotate, is covered with the polishing disk of polishing pad 21
20, for providing the feed flow module 30 of polishing fluid and for the film thickness sensor 50 of on-line measurement wafer film thickness.Film thickness sensing
Device 50 is arranged in below the disk of polishing disk 20, and the rotation of polishing disk 20 is followed to be surveyed online while polishing to realize
Amount.
As shown in Figure 2, during polishing wafer, rubbing head 10 presses wafer w on polishing pad 21 and rubbing head 10
Radial along polishing disk 20 moves back and forth (as shown in four-headed arrow in figure), and film thickness sensor 50 follows polishing disk 20 to rotate,
Therefore the position of sampled point that film thickness sensor 50 measures on wafer w constantly changes.
Fig. 3 shows a motion profile of the film thickness sensor 50 relative to wafer w during polishing.With polishing disk 20
It is rotated according to direction shown in arrow ab in figure, film thickness sensor 50 is inswept below wafer w according to direction shown in arrow cd in figure
And sampled with substantially invariable sample frequency, obtain multiple sampled points (as shown in solid dot in Fig. 3).It is polished by combining
Sample frequency appropriate can be set in the spatial resolution that the speed of rotation of disk 20 and expectation measure, can be for 50Hz extremely
2kHz, preferably 1kHz.For example, the sample frequency of 1kHz, i.e., every millisecond generates one in the speed of rotation of about 60-100rpm
A sampled point is capable of providing the spatial resolution of about 1mm.Bigger sample frequency or the smaller speed of rotation can increase space
Resolution ratio.
It is understood that during polishing, the meeting of film thickness sensor 50 inswept many motion profiles on wafer w, this
A little motion profile some pass through the wafer center of circle, and some is without the wafer center of circle.
Fig. 4 shows the voltage signal of electric vortex type film thickness sensor output.As it can be seen that the probe when film thickness sensor is mobile
When below to wafer, there is peak value in voltage signal.When the probe of film thickness sensor removes below wafer, there is paddy in voltage signal
Value.
Voltage signal occurs in Fig. 4 with periodic formation, occurs a peak value and a valley in a cycle, represents polishing disk
Rotation is turned around, and film thickness sensor is inswept primary below wafer.Shown in Fig. 4, start inswept crystalline substance at t1, t2 and t3 moment respectively
Circle.
As shown in figure 5, a kind of film thickness measuring method provided by the embodiment of the present invention, comprising:
Step S1 obtains the output signal of film thickness sensor and the mapping relations of wafer film thickness.
Step S2, using the mapping relations, the signal value exported when by the film thickness sensor on-line measurement is converted to
Film thickness value.
In the present embodiment, the signal value and actual wafer film that film thickness sensor is exported when measuring to film thickness are obtained
Mapping relations between thickness, wherein mapping relations can be expressed as signal-film thickness calibration scale, can also be expressed as signal and film
Thick relation curve.Then in polishing wafer, on-line measurement is carried out to wafer using this film thickness sensor, and reflect using this
It penetrates relationship and the signal value that film thickness sensor exports is converted directly into film thickness value, to realize quickly and accurate online film thickness
Measurement.
In one embodiment of the invention, step S1 includes:
Step S11 obtains the film thickness pattern of different moments off-line measurement.
Off-line measurement is will to remove in wafer chemically mechanical polishing apparatus, is placed in off-line measurement equipment and is surveyed
Amount, such as four-point probe, profilograph, resistivity measuring instrument etc..
Preferably, can use four-point probe off-line measurement film thickness pattern, respectively two different moments obtain from
The the first film thickness pattern and the second film thickness pattern of line measurement.The first film thickness pattern is obtained before polishing wafer for operating easily,
With the second film thickness pattern is obtained after polishing wafer.
Wherein, film thickness pattern is away from film thickness curve composed by corresponding film thickness in the different radial distances of the wafer center of circle, such as
Curve shown in Fig. 7.
As shown in fig. 7, illustrate diameter be 300mm crystal column surface, the radial distance away from the wafer center of circle be-
Film thickness pattern on 150mm to the section 150mm.Abscissa is radial distance, and unit is millimeter, and ordinate is film thickness, and unit is
Angstrom.Curve L1 indicates that the first film thickness pattern, curve L2 indicate the second film thickness pattern.
Step S12, during polishing wafer, the signal value of online acquisition film thickness sensor output simultaneously carries out real-time shape to it
Looks are fitted to obtain signal pattern.
By taking electric vortex type film thickness sensor as an example, the signal of output is voltage signal, and signal value is voltage value, signal shape
Looks are voltage pattern.The signal value for the sampled point (as shown in solid dot in Fig. 3) for detecting film thickness sensor in the present embodiment
It is associated with the sampled point away from (distance of the solid dot away from the center of circle wafer w in Fig. 3) at a distance from the wafer center of circle and just obtains signal pattern,
With coordinate representation, as shown in Figure 8.Abscissa is radial distance in Fig. 8, and unit is millimeter, and ordinate is voltage value, and unit is
Volt.
Step S13 establishes the mapping relations according to the film thickness pattern and the signal pattern.
As an embodiment, the first film thickness pattern, the second film thickness pattern and signal pattern be can use, obtained
Same time point corresponding film thickness value and signal value, such as the film thickness value and signal value of time t, so that the mapping both established is closed
System, realizes to the quick of film thickness sensor and accurately demarcates.
The film thickness calibration to wafer, use and reality in calibration process can be completed during stock removal polishing in this approach
The technological parameters such as the identical polish pressure of polishing process, polishing fluid component and flow, can be to avoid these technological parameters to calibration
As a result interference.
As an embodiment, a reference interval is chosen in crystal column surface, utilizes the film thickness pattern of this reference interval
Mapping relations are established with signal pattern, the pattern without considering wafer full surface.
Optionally, the reference interval is the default annular region of crystal column surface.
Annular pressure chamber composed by the default annular region and flexible membrane of the rubbing head lower part to wafer pressure site
Room is corresponding.
As shown in fig. 6,10 lower part of rubbing head is equipped with the flexible membrane 11 for pressing to wafer w and wafer w is maintained at soft
Property film 11 lower section and the retaining ring 12 that prevents wafer w from skidding off.Multiple concentric pressure chamber, each pressure are equipped with inside flexible membrane 11
Power chamber can correspond to a crystal column surface subregion.A subregion is chosen as the reference interval.
It is equipped with 3 annular pressure chambers in Fig. 6 with 10 lower part of rubbing head to be illustrated, respectively outward by center
The 1st pressure chamber Zone1, the 2nd pressure chamber Zone2 and the 3rd pressure chamber Zone3 being successively arranged concentrically.Correspondingly, it polishes
The surface wafer w is divided into corresponding multiple subregions by first 10 different pressure chamber, such as the 1st area Z1, the 2nd area Z2 in Fig. 6
With the 3rd area Z3.Each pressure chamber can apply different pressure to its corresponding crystal column surface subregion, by being supplied to pressure
The pressure of the fluids such as the forced air of chamber is respectively controlled, and may be implemented to apply different pressures to crystal column surface different subregions
Power.
Obviously, the quantity of pressure chamber shown in Fig. 6 and subregion is only a kind of citing, can also be actually other numbers
Amount, such as 4,5,6,7 etc..
Reference interval can be chosen according to subregion of the pressure chamber in rubbing head to crystal column surface, such as reference interval
It can be made of 1 subregion or multiple subregions.The 2nd area Z2 is chosen as a preferred implementation manner, as reference interval, i.e., the
Radius r1 is to the annular region between the second radius r2.
In the polishing process for obtaining mapping relations, the pressure in the corresponding pressure chamber of control reference interval is kept
It is constant, i.e. the 2nd pressure chamber Zone2, so that the film thickness in the section reduces according to consistent removal rate, it can convenient benefit
The film thickness of any time is calculated with the film thickness at two moment, improves the accuracy for calculating t moment film thickness.So choosing
The corresponding annular region of pressure chamber is as the available more accurate mapping relations of reference interval.
As shown in fig. 7, choosing film thickness pattern in r1 to the part between r2.As shown in figure 8, choose signal pattern r1 extremely
Part between r2.
In one embodiment, in Fig. 8 signal pattern establishment process, i.e. step S12 includes:
Step a calculates the probe of the film thickness sensor away from the radial direction in the wafer center of circle while acquiring the signal value
Distance.
Step b forms the signal pattern according to the corresponding relationship of the signal value and the radial distance.
As shown in figure 3, when obtaining the signal value of the sampled point at crystal column surface different location by film thickness sensor, meter
Radial distance of the sampled point away from the wafer center of circle is calculated, i.e. distance of each solid dot away from the center of circle wafer w in Fig. 3.
The corresponding relationship of signal value and radial distance can indicate to be vertical by abscissa of radial distance and with signal value
In the coordinate system of coordinate, as shown in Figure 8.It is to be understood that the signal value (i.e. voltage value) of t moment is obtained from Fig. 4, from Fig. 3
The middle distance of sampled point (i.e. solid dot) away from the center of circle wafer w for obtaining t moment, forms a coordinate of the sampled point, can indicate
For (signal value, radial distance), the coordinate line of many a sampled points has just obtained the curve in Fig. 8, i.e. signal pattern.
Specifically, as a kind of embodiment for calculating radial distance, step a includes:
Step a1 obtains rubbing head position and throwing at this time while measuring the signal value by film thickness sensor
CD position.
Step a2, according to installation site, the polishing disk position and the rubbing head of the film thickness sensor on polishing disk
Position calculates the radial distance.
As shown in Fig. 2, polishing disk rotating electric machine 22 drives polishing disk 20 in polishing disk 20 during wafer w polishing
Axis rotation.Rubbing head 10 is connected to rubbing head rotating electric machine 13, so that rubbing head 10 is rotated around its central axes.Meanwhile it polishing
First 10 are suspended in support construction 14, and support construction 14 can be realized by such as rotational material frame or track, pass through transport motor 15
Control rubbing head 10 is moved horizontally along support construction 14, so that the moving radially along polishing disk 20 of rubbing head 10.
As shown in figure 9, the transport motor of polishing disk rotating electric machine, rubbing head rotating electric machine and rubbing head is respectively connected with respectively
Driving unit, driving unit connects the controller of chemical mechanical polishing apparatus, and controller can read electricity by driving unit
The information such as position, revolving speed, the pulse number of machine, so as to obtain rubbing head position and polishing disk position.
Also, it as shown in figure 9, the output end of film thickness sensor connects the controller by voltage conversion unit, realizes
Acquire the signal value and rubbing head position and polishing disk that film thickness sensor exports simultaneously in the same scan cycle of controller
Position ensure that the homology of data.
As shown in Figure 10, as an embodiment, using rectangular coordinate system as reference, the radial distance are as follows:
Wherein, the rectangular coordinate system is to polish disk center as coordinate origin and to polish disk center to rubbing head center
Direction is x-axis direction, and r is the radial distance, and d is distance of the installation site away from polishing disk center, θ be the probe and
The angle of the coordinate origin line and the x-axis forward direction, e are distance of the rubbing head center away from the polishing disk center.
In Figure 10, origin O is 20 center of polishing disk, O1Point is 10 center of rubbing head, O2Point is to deposit 40 center of piece module.Film
Installation site of the thick sensor on polishing disk is fixed and invariable, and indicates installation site with the center probe of film thickness sensor,
As shown in S point in Figure 10, it can measure to obtain the distance d of S point to O point in advance.
The position for depositing piece module 40 is fixed, and disk center O is to depositing piece module centers O for polishing2Distance OO2It can measure in advance
It arrives.The motion track of rubbing head 10 is with O2It is moved along the x-axis for starting point, the position of the transport motor output by reading rubbing head
The available distance O of information1O2, therefore e=OO2-O1O2。
As an embodiment, the process for obtaining angle theta includes:
1) zero correction obtains the arteries and veins of polishing disk rotating electric machine when the center probe S of film thickness sensor is moved to x-axis
Punching value P0.It can use whether optoelectronic switch sensor detection probe center S is moved to x-axis.
2) any time during polishing obtains the pulse value P of polishing disk rotating electric machinet.Known polishing disk turns around
Pulse number be PN(such as 1048576), then:
The radial distance r being calculated and signal value are corresponded, obtain signal pattern, as shown in Figure 8.
In one embodiment of the invention, the establishment process of mapping relations, i.e. step S13 include:
Step 1, reference interval is chosen, calculates the film thickness pattern in the film thickness mean value of the reference interval.
Step 2, the signal pattern is calculated in the signal mean value of the reference interval.
Step 3, the film thickness mean value is matched with the signal mean value, generates the mapping relations.
As shown in fig. 7, reference interval is selected as the first radius r1 to the range between the second radius r2.
As an embodiment, film thickness pattern includes the first film thickness pattern obtained before polishing wafer and in wafer
The the second film thickness pattern obtained after polishing.
Then, step 1 includes:
1) the first film thickness pattern is calculated in the first film thickness mean value of the reference interval；
2) the second film thickness pattern is calculated in the second film thickness mean value of the reference interval；
3) according to the first film thickness mean value, the second film thickness mean value and polishing total duration, the film thickness of different moments is calculated
Mean value.
As another embodiment, film thickness pattern includes in the first film thickness pattern of the first moment acquisition and second
The second film thickness pattern that moment obtains, according to the first film thickness mean value, the second film thickness mean value and the first moment and the second moment it
Between time interval, the film thickness mean value of different moments is calculated.
Step 2 includes the signal pattern acquired according to different moments, obtains the signal mean value of different moments.Such as Fig. 8
It is shown, the signal pattern of different moments is taken into mean value in reference interval.
Step 3 includes being associated the corresponding film thickness mean value of synchronization with the signal mean value, described in generation
Mapping relations.
For step 1, as shown in fig. 7, curve L1 is the first film thickness pattern, drawn dotted line L1 ' is that the first film thickness is equal thereon
Value, is set as the film thickness at 0 moment, i.e. t=0.Polishing total duration is T.Curve L2 is the second film thickness pattern, thereon drawn dotted line
L2 ' is the second film thickness mean value, is set as the film thickness at T moment, i.e. t=T.
Setting uses uniform polish removal rate from L1 ' to L2 ', then, utilize L1 ', L2 ' and T, it is known that polishing
Removal rate is RR=(L2 '-L1 ')/T, and the film thickness mean value that any time t then can be obtained is institute in L1 '+RR*t, such as Fig. 7
Show t1, t2 and t3 moment corresponding film thickness mean value.
Specific calculating process are as follows:
The first film thickness pattern matrix is expressed as THKa=[a1 a2 ... ak], k is the total number of sample points of film thickness；Such as
Shown in curve L1.
The second film thickness pattern matrix is expressed as THKb=[b1 b2 ... bk], as shown in curve L2.
The polishing total duration is T.Reference interval is selected as p-th of sampled point to q-th of sampled point, if r1 is between r2
Shown in range.
Then, the first film thickness mean value isAs shown in L1 '.
Second film thickness mean value isAs shown in L2 '.
Polish removal rate is
Film thickness mean value corresponding to t moment during polishing are as follows:
For step 2, as shown in figure 8, film thickness sensor is in different moments collected signal pattern.
The signal pattern of t moment is expressed as Vt=[v1 v2 ... vn], n is the total number of sample points of signal；
Reference interval is selected as p-th of sampled point to q-th of sampled point, as shown in r1 to the range between r2.
Then, the signal mean value of t moment are as follows:
For step 3, mapping relations can be expressed as dynamic calibration table or signal-film thickness performance matching curve.
As an embodiment, the film thickness mean value at multiple moment and signal mean value are stored in number according to corresponding relationship
According in library, generation dynamic calibration table is as the mapping relations, to realize that multistage is demarcated.
It is as shown in table 1 the example of dynamic calibration table, setting calibration number of segment m.Data in dynamic calibration table can in real time more
Newly.
Table 1- dynamic calibration table
When executing step S2 using table 1, if the signal value of film thickness sensor output has in the signal mean value that table 1 stores
It records, then directly extracts corresponding film thickness mean value.If the signal value of film thickness sensor output is not recorded in table 1, uses and divide
Section interpolation method, using the two signal mean value computation intermediate interpolateds closed in table 1 to obtain corresponding film thickness.
As another embodiment, the corresponding relationship of film thickness mean value and signal mean value based on multiple moment, fitting
The relation curve and functional relation of signal and film thickness, as the mapping relations.
It is as shown in figure 11 signal-film thickness performance matching curve example, can be obtained using curve fitting algorithm.
For example, using least square method, by the film thickness mean value of different momentsWith signal mean valueThe coordinate points of composition
It is fitted to curve and obtains the corresponding functional relation of curve.
Alternatively, the broken line of segmented line composition by the coordinate points line of adjacent moment, is formd using piecewise fitting method, and
Obtain functional relation.
When executing step S2 using the performance matching curve in Figure 11, the corresponding functional relation of matched curve is directly utilized
Formula calculates the corresponding film thickness value of signal value.
As shown in figure 12, it is illustrated with the complete procedure that an example measures wafer film thickness.
During polishing to wafer, film thickness pattern and signal pattern are acquired, then calculates the film of reference interval
Thick mean valueWith signal mean valueGenerate the mapping relations of signal and film thickness.Film thickness measuring is being carried out to wafer later
When, this mapping relations can be used, directly obtain film thickness using the signal of film thickness sensor output.
In the embodiment of the present invention, during wafer polishing, the signal of online acquisition film thickness sensor output, and benefit
Calculate the corresponding film thickness of the signal with the first film thickness pattern and the second film thickness pattern, thus by film thickness sensor output signal with
Actual wafer film thickness is associated, and obtains the mapping relations of signal and film thickness, while realizing the calibration to film thickness sensor.
In polishing wafer later, on-line measurement is carried out to wafer using this film thickness sensor, and utilize the mapping
The signal value that film thickness sensor exports is converted directly into film thickness value by relationship, to realize quickly and accurately online film thickness survey
Amount.
It should be understood that the size of the serial number of each step is not meant that the order of the execution order in above-described embodiment, each process
Execution sequence should be determined by its function and internal logic, the implementation process without coping with the embodiment of the present invention constitutes any limit
It is fixed.
As shown in figure 13, the membrane thickness measuring system 100 that one embodiment of the present of invention provides, for executing corresponding to Fig. 5
Embodiment in method and step comprising:
Demarcating module 110, for obtaining the output signal of film thickness sensor and the mapping relations of wafer film thickness.
Output module 120, for utilizing the mapping relations, the signal exported when by the film thickness sensor on-line measurement
Value is converted to film thickness value.
In one embodiment, membrane thickness measuring system 100 further includes other function module/unit, for realizing above-mentioned side
The method and step of each embodiment in method embodiment.
The embodiment of the invention also provides a kind of chemical mechanical polishing apparatus, comprising:
Polishing disk is covered with the polishing pad for being polished to wafer；
Rubbing head, for keeping wafer and pressing wafer in the polishing pad；
Film thickness sensor, for measuring wafer film thickness and output signal value during polishing；
Controller, for obtaining the output signal of film thickness sensor and the mapping relations of wafer film thickness；And it is reflected described in utilizing
Relationship is penetrated, the signal value exported when by the film thickness sensor on-line measurement is converted to film thickness value.
Figure 14 is the schematic diagram for the control equipment that one embodiment of the invention provides.As shown in figure 14, the control of the embodiment
Equipment include: processor, memory and storage in the memory and the computer journey that can run on the processor
Sequence.The processor realizes the step in each embodiment as described in above method embodiment when executing the computer program
Such as step S1 to S2 shown in fig. 5 suddenly,.Alternatively, the processor realizes such as above system when executing the computer program
The function of each module/unit in each embodiment as described in the examples, such as the function of module 110 to 120 shown in Figure 13.
The control equipment refers to the terminal with data-handling capacity, including but not limited to computer, work station, service
Device, the smart phone more even haveing excellent performance, palm PC, tablet computer, personal digital assistant (PDA), smart television
(Smart TV) etc..
The control equipment may include, but be not limited only to, processor, memory.It will be understood by those skilled in the art that figure
14 be only the example for controlling equipment, does not constitute the restriction to control equipment, may include than illustrating more or fewer portions
Part perhaps combines certain components or different components, such as the control equipment can also include input-output equipment, net
Network access device, bus etc..
Alleged processor can be central processing unit (Central Processing Unit, CPU), can also be it
His general processor, digital signal processor (Digital Signal Processor, DSP), specific integrated circuit
(Application Specific Integrated Circuit, ASIC), ready-made programmable gate array (Field-
Programmable Gate Array, FPGA) either other programmable logic device, discrete gate or transistor logic,
Discrete hardware components etc..
The memory can be the internal storage unit of the control equipment, such as the hard disk or memory of control equipment.
It is hard that the memory is also possible to the plug-in type being equipped on the External memory equipment of the control equipment, such as the control equipment
Disk, intelligent memory card (Smart Media Card, SMC), secure digital (Secure Digital, SD) card, flash card
(Flash Card) etc..Further, the memory can also both include the internal storage unit of the control equipment or wrap
Include External memory equipment.The memory is for other programs needed for storing the computer program and the control equipment
And data.The memory can be also used for temporarily storing the data that has exported or will export.
The embodiment of the invention also provides a kind of computer readable storage medium, computer-readable recording medium storage has meter
Calculation machine program realizes the step in each embodiment as described in above method embodiment when computer program is executed by processor
Such as step S1 shown in fig. 5 to step S2 suddenly,.Alternatively, realizing such as above-mentioned system when the computer program is executed by processor
The function of each module/unit in each embodiment as described in the examples of uniting, such as the function of module 110 to 120 shown in Figure 13
Energy.
The computer program can be stored in a computer readable storage medium, and the computer program is by processor
When execution, it can be achieved that the step of above-mentioned each embodiment of the method.Wherein, the computer program includes computer program code,
The computer program code can be source code form, object identification code form, executable file or certain intermediate forms etc..Institute
State computer-readable medium may include: can carry the computer program code any entity or device, recording medium,
USB flash disk, mobile hard disk, magnetic disk, CD, computer storage, read-only memory (ROM, Read-Only Memory), arbitrary access
Memory (RAM, Random Access Memory), electric carrier signal, telecommunication signal and software distribution medium etc..
In the above-described embodiments, it all emphasizes particularly on different fields to the description of each embodiment, each embodiment can combine in any combination
The new embodiment formed afterwards is also within the scope of protection of this application.There is no the part for being described in detail or recording in some embodiment,
It may refer to the associated description of other embodiments.
Those of ordinary skill in the art may be aware that list described in conjunction with the examples disclosed in the embodiments of the present disclosure
Member and algorithm steps can be realized with the combination of electronic hardware or computer software and electronic hardware.These functions are actually
It is implemented in hardware or software, the specific application and design constraint depending on technical solution.Professional technician
Each specific application can be used different methods to achieve the described function, but this realization is it is not considered that exceed
The scope of the present invention.
Embodiment described above is merely illustrative of the technical solution of the present invention, rather than its limitations；Although referring to aforementioned reality
Applying example, invention is explained in detail, those skilled in the art should understand that: it still can be to aforementioned each
Technical solution documented by embodiment is modified or equivalent replacement of some of the technical features；And these are modified
Or replacement, the spirit and scope for technical solution of various embodiments of the present invention that it does not separate the essence of the corresponding technical solution should all
It is included within protection scope of the present invention.
Claims (15)
1. a kind of film thickness measuring method characterized by comprising
Obtain the output signal of film thickness sensor and the mapping relations of wafer film thickness；
Using the mapping relations, the signal value exported when by the film thickness sensor on-line measurement is converted to film thickness value.
2. film thickness measuring method as described in claim 1, which is characterized in that the acquisition mapping relations include:
Obtain the film thickness pattern of different moments off-line measurement；
During polishing wafer, the signal value of online acquisition film thickness sensor output simultaneously carries out real-time pattern to it and is fitted to obtain letter
Number pattern；
According to the film thickness pattern and the signal pattern, the mapping relations are established.
3. film thickness measuring method as claimed in claim 2, which is characterized in that the mapping relations of establishing include:
Reference interval is chosen, calculates the film thickness pattern in the film thickness mean value of the reference interval；
The signal pattern is calculated in the signal mean value of the reference interval；
The film thickness mean value is matched with the signal mean value, generates the mapping relations.
4. film thickness measuring method as claimed in claim 3, which is characterized in that the reference interval is the default ring of crystal column surface
Shape region.
5. film thickness measuring method as claimed in claim 4, which is characterized in that the default annular region and rubbing head lower part to
Annular pressure chamber composed by the flexible membrane of wafer pressure site is corresponding.
6. film thickness measuring method as claimed in claim 3, which is characterized in that the film thickness pattern obtains before being included in polishing wafer
The the first film thickness pattern taken and the second film thickness pattern obtained after polishing wafer；
It is described to calculate the film thickness pattern in the film thickness mean value of the reference interval, comprising:
The first film thickness pattern is calculated in the first film thickness mean value of the reference interval；
The second film thickness pattern is calculated in the second film thickness mean value of the reference interval；
According to the first film thickness mean value, the second film thickness mean value and polishing total duration, the film thickness mean value of different moments is calculated.
7. film thickness measuring method as claimed in claim 6, which is characterized in that described to calculate the signal pattern in the reference
The signal mean value in section includes:
According to the signal pattern that different moments acquire, the signal mean value of different moments is obtained.
8. film thickness measuring method as claimed in claim 7, which is characterized in that the generation mapping relations include:
The corresponding film thickness mean value of synchronization is associated with the signal mean value, generates the mapping relations.
9. film thickness measuring method as claimed in claim 2, which is characterized in that the signal pattern that obtains includes:
While acquiring the signal value, the probe of the film thickness sensor is calculated away from the radial distance in the wafer center of circle；
According to the corresponding relationship of the signal value and the radial distance, the signal pattern is formed.
10. film thickness measuring method as claimed in claim 9, which is characterized in that the calculating radial distance includes:
While measuring the signal value by the film thickness sensor, rubbing head position and polishing disk position at this time is obtained
It sets；
According to installation site, the polishing disk position and the rubbing head position of the film thickness sensor on polishing disk, meter
Calculate the radial distance.
11. film thickness measuring method as claimed in claim 10, which is characterized in that using rectangular coordinate system as reference, the diameter
To distance are as follows:
Wherein, the rectangular coordinate system is to polish disk center as coordinate origin and to polish the direction of disk center to rubbing head center
For x-axis direction, r is the radial distance, and d is distance of the installation site away from polishing disk center, and θ is the probe and described
The angle of coordinate origin line and the x-axis, e are distance of the rubbing head center away from the polishing disk center.
12. a kind of membrane thickness measuring system characterized by comprising
Demarcating module, for obtaining the output signal of film thickness sensor and the mapping relations of wafer film thickness；
Output module, for utilizing the mapping relations, the signal value conversion exported when by the film thickness sensor on-line measurement
For film thickness value.
13. a kind of chemical mechanical polishing apparatus characterized by comprising
Polishing disk is covered with the polishing pad for being polished to wafer；
Rubbing head, for keeping wafer and pressing wafer in the polishing pad；
Film thickness sensor, for measuring wafer film thickness and output signal value during polishing；
Controller, for obtaining the output signal of film thickness sensor and the mapping relations of wafer film thickness；And it is closed using the mapping
System, the signal value exported when by the film thickness sensor on-line measurement are converted to film thickness value.
14. a kind of control equipment, which is characterized in that in the memory and can be including memory, processor and storage
The computer program run on the processor, the processor realized when executing the computer program as claim 1 to
The step of any one of 11 film thickness measuring method.
15. a kind of computer readable storage medium, which is characterized in that the computer-readable recording medium storage has computer journey
Sequence realizes the step of the film thickness measuring method as described in any one of claim 1 to 11 when the computer program is executed by processor
Suddenly.
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