CN105470155A - Epitaxial device and epitaxial layer measuring method in epitaxial process - Google Patents
Epitaxial device and epitaxial layer measuring method in epitaxial process Download PDFInfo
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Abstract
The invention provides an epitaxial device and an epitaxial layer measuring method in an epitaxial process. The device comprises a reaction chamber; an observation window arranged in the reaction chamber; a tray arranged inside the reaction chamber, wherein the tray is carried with wafers; and an optical fiber type Fourier infrared spectrum analyzer, which has an optical fiber. One end of the optical fiber is corresponding to the observation window; the optical fiber is used for emitting infrared light rays, and the infrared light rays are irradiated to the wafers through the observation window; reflected light reflected by the wafers is received by the observation window; and the optical fiber type Fourier infrared spectrum analyzer is used for detecting the thickness of an epitaxial layer of each wafer according to the reflected light. The epitaxial device can carry out real-time guidance on the epitaxial process, so that the epitaxial process is allowed to be more controllable, qualified rate of a product produced in the epitaxial process is greatly improved, waste product due to inappropriate process parameter selection is effectively prevented, and meanwhile, utilization rate of raw materials in the epitaxial process and output of the epitaxial device are improved favorably.
Description
Technical field
The present invention relates to technical field of semiconductors, particularly relate to the method for measurement of a kind of epitaxial apparatus and epitaxial process epitaxial layers.
Background technology
Along with the progress of microelectric technique, the integrated level of integrated circuit improves constantly, and the complexity of its technique is also improving constantly.Therefore, in production technology, strict requirement is proposed to various parameters such as temperature, pressure, growth rate, doping content and airflow field uniformities.
In silicon homoepitaxy, the thickness of epitaxial loayer, uniformity and surface smoothness are very crucial parameters.These parameters have direct and vital impact to follow-up semiconductor device technology and device performance.In the preparation process of silicon planar transistor and integrated circuit, the quality of epitaxial loayer uniformity directly affects completing of rear step operation.Epitaxial loayer in uneven thickness brings serious problems can to subsequent technique process.First, epitaxial loayer in uneven thickness brings very large difficulty to isolation diffusion, makes under normal process conditions, and the place isolation that epitaxial loayer is thicker is obstructed, causes the device in this region to scrap.Even if isolation diffusion can expand the epitaxial loayer of logical uneven distribution, also electrical property off-design index can be made due to the collector region thickness difference of each device.The blocked up meeting of epitaxial loayer causes collector region resistance increase and reduce maximum diffipation power and frequency characteristic.Epitaxial loayer is crossed thin meeting and is caused collector region thin and too early break-through, and the reverse breakdown voltage of device is declined.In addition, if epitaxial loayer center and peripheral area thickness difference huge, also can affect in photoetching to the technique such as plate and exposure, cause device to be scrapped.Can find out thus, the variable thickness of epitaxial loayer causes the preparation that drastically influence device.
In view of thickness and the importance of its uniformity in research and production of epitaxial loayer, people have carried out extensive research to its method of measurement.At present, the thickness measuring epitaxial loayer has following two kinds of methods usually:
1. ftir analysis (FTIR) method is a kind of method measuring silicon homoepitaxy layer thickness that industry extensively adopts.This method mainly measures epitaxy layer thickness based on substrate and the optical qualitative difference of epitaxial loayer.
2., in the outer Yanzhong of nitrided metal organic chemical vapor, the surface topography of method to the GaN base materials and devices grown on a sapphire substrate of interfering through conventional visible ray carries out Real-Time Monitoring in place.
But all there is different shortcomings in above-mentioned two kinds of methods:
1. ftir analysis method can only be used for the finished product externally delayed and measures, and cannot measure the parameter such as thickness at growth course epitaxial layers.
2., because silicon materials can absorb the energy of whole limit of visible spectrum, the interference therefore in visible-range, cannot be used for the measurement of silicon epitaxy.In addition, the interference spectrum that what this method utilizing visible ray to interfere obtained is with varied in thickness, thickness value needs to draw according to Time Calculation accurately, directly cannot obtain thickness value.
Summary of the invention
The present invention is intended to solve one of technical problem in correlation technique at least to a certain extent.
For this reason, first object of the present invention is to propose a kind of epitaxial apparatus, this epitaxial apparatus can carry out real-time instruction to epitaxial process, epitaxial process is made to become more controlled, significantly improve in epitaxial process the yields of producing product, effectively prevent because technological parameter selects the improper waste product brought, be conducive to the output improving raw-material utilance and epitaxial apparatus in epitaxial process simultaneously.
Second object of the present invention is the method for measurement proposing a kind of epitaxial process epitaxial layers.
For reaching above-mentioned purpose, first aspect present invention embodiment proposes a kind of epitaxial apparatus, comprising: reaction chamber; Be arranged on the observation window on described reaction chamber; Be arranged on the pallet in described reaction chamber, described pallet carries wafer; Optical fiber type FTIR spectrum analyzer, described optical fiber type FTIR spectrum analyzer has optical fiber, one end of described optical fiber is corresponding with described observation window, described optical fiber is for launching Infrared, and by described observation window, described Infrared is exposed to described wafer, and the reverberation of described wafer reflection is received by described observation window, described optical fiber type FTIR spectrum analyzer is used for the epitaxy layer thickness detecting described wafer according to described reverberation.
The epitaxial apparatus of the embodiment of the present invention, by arranging observation window on reaction chamber, and utilize optical fiber to carry out Fourier transform infrared spectroscopy measurement to the epitaxial loayer of wafer in epitaxial process, and carry out Real-time Collection by the data of host computer to measurement and analyze the epitaxy layer thickness obtaining wafer, thus, real-time instruction can be carried out to epitaxial process, epitaxial process is made to become more controlled, significantly improve in epitaxial process the yields of producing product, effectively prevent because technological parameter selects the improper waste product brought, be conducive to the output improving raw-material utilance and epitaxial apparatus in epitaxial process simultaneously.
For reaching above-mentioned purpose, second aspect present invention embodiment proposes a kind of method of measurement of epitaxial process epitaxial layers, comprise: described fibre optical transmission Infrared, and by described observation window described Infrared exposed to the wafer that the pallet that is arranged in described reaction chamber carries; And described optical fiber receives the reverberation of described wafer reflection by described observation window, with the epitaxy layer thickness making described optical fiber type FTIR spectrum analyzer detect described wafer according to described reverberation.
The method of measurement of the epitaxial process epitaxial layers of the embodiment of the present invention, by arranging observation window on reaction chamber, and utilize optical fiber to carry out Fourier transform infrared spectroscopy measurement to the epitaxial loayer of wafer in epitaxial process, and carry out Real-time Collection by the data of host computer to measurement and analyze the epitaxy layer thickness obtaining wafer, thus, real-time instruction can be carried out to epitaxial process, epitaxial process is made to become more controlled, significantly improve in epitaxial process the yields of producing product, effectively prevent because technological parameter selects the improper waste product brought, be conducive to the output improving raw-material utilance and epitaxial apparatus in epitaxial process simultaneously.
The aspect that the present invention adds and advantage will part provide in the following description, and part will become obvious from the following description, or be recognized by practice of the present invention.
Accompanying drawing explanation
The present invention above-mentioned and/or additional aspect and advantage will become obvious and easy understand from the following description of the accompanying drawings of embodiments, wherein:
Fig. 1 is the structural representation of the epitaxial apparatus of one embodiment of the invention;
Fig. 2 is the schematic diagram of the epitaxial apparatus of one embodiment of the invention;
Fig. 3 is the schematic diagram of the Michelson interference device of one embodiment of the invention;
Fig. 4 is the structural representation of the epitaxial apparatus of another embodiment of the present invention;
Fig. 5 is the schematic diagram of the epitaxial apparatus of another embodiment of the present invention;
Fig. 6 is the flow chart of the method for measurement of the epitaxial process epitaxial layers of one embodiment of the invention;
Fig. 7 is the flow chart of the method for measurement of the epitaxial process epitaxial layers of another embodiment of the present invention; And
Fig. 8 is the flow chart of the method for measurement of the epitaxial process epitaxial layers of another embodiment of the present invention.
Embodiment
Be described below in detail embodiments of the invention, the example of described embodiment is shown in the drawings, and wherein same or similar label represents same or similar element or has element that is identical or similar functions from start to finish.Be exemplary below by the embodiment be described with reference to the drawings, be intended to for explaining the present invention, and can not limitation of the present invention be interpreted as.
In addition, term " first ", " second " only for describing object, and can not be interpreted as instruction or hint relative importance or imply the quantity indicating indicated technical characteristic.Thus, be limited with " first ", the feature of " second " can express or impliedly comprise one or more these features.In describing the invention, the implication of " multiple " is two or more, unless otherwise expressly limited specifically.
Describe and can be understood in flow chart or in this any process otherwise described or method, represent and comprise one or more for realizing the module of the code of the executable instruction of the step of specific logical function or process, fragment or part, and the scope of the preferred embodiment of the present invention comprises other realization, wherein can not according to order that is shown or that discuss, comprise according to involved function by the mode while of basic or by contrary order, carry out n-back test, this should understand by embodiments of the invention person of ordinary skill in the field.
In recent years, along with the wafer size of growing epitaxial silicon constantly increases, excessive from 6-8 cun to 12 cun of current main flow, epitaxial device and technology also development.At present, the epitaxial apparatus for 6-8 cun of wafer adopts the reaction chamber of horizontal air inlet multiple plates, revolving type to design usually.But, when multiple wafer grows simultaneously, the uniformity of the epitaxial loayer of wafer is had higher requirement, for this reason, the present invention proposes a kind of epitaxial device.Fig. 1 is the structural representation of the epitaxial apparatus of one embodiment of the invention.
As shown in Figure 1, epitaxial apparatus comprises reaction chamber 10, observation window 20, pallet 30, optical fiber type FTIR spectrum analyzer 40 and host computer 50, and wherein, optical fiber type FTIR spectrum analyzer 40 comprises optical fiber 41.
Particularly, observation window 20 is arranged on reaction chamber 10, and pallet 30 is arranged in reaction chamber 10, and pallet carries wafer.Specifically, the epitaxial apparatus in the N-shaped silicon epitaxy layer explanation embodiment of the present invention of phosphorus (P) element is mixed for extension on silicon (Si) substrate of heavily doped arsenic (As).Adopt horizontal air inlet quartz reaction chamber 10 to grow n-Si epitaxial loayer on n+ wafer, wherein, brilliant diameter of a circle is approximately 8 inches, namely 200 millimeters.As shown in Figure 2, observation window 20 is arranged on the roof of reaction chamber 10, graphite pallet 30 is in reaction chamber 10, and the graphite pallet 30 of SiC parcel is placed the wafer of 58 inches, and the angle between the center of circle of adjacent 2 wafer and the center of circle of graphite pallet 30 is 72 degree.In epitaxial process, graphite pallet 30 is rotated in a clockwise direction, and occurs uniformly on each wafer to impel chemical reaction.Preferably, reaction pressure is-1.5mbar, and growth temperature is 1070 DEG C, and reaction source is SiHCL3, and carrier gas is H2.
Optical fiber type FTIR spectrum analyzer 40 has optical fiber 41, one end of optical fiber is corresponding with observation window 20, optical fiber 41 is for launching Infrared, and by observation window 20, Infrared is exposed to wafer, and the reverberation of wafer reflection is received by observation window 20, optical fiber type FTIR spectrum analyzer 40 is for detecting the epitaxy layer thickness of wafer according to reverberation.Specifically, as shown in Figure 2, optical fiber 41 one end of optical fiber type FTIR spectrum analyzer 40 is positioned over the observation station position above the observation window 20 on reaction chamber 10 upper surface, launches Infrared by optical fiber 41.
In an embodiment of the present invention, the Infrared that FTIR spectrum analyzer 40 is launched by optical fiber 41 carries out converging to form hot spot, and hot spot is exposed to wafer.Specifically, the parallel Infrared emitted from FTIR spectrum analyzer 40 is pooled the hot spot being less than 1 millimeter by optical fiber 41, and is irradiated in the epi-layer surface to be measured of wafer by observation window 20 by the hot spot obtained after this focusing.
Furthermore, as shown in Figure 2, in the process that chemical gas phase reaction carries out, graphite pallet 30 is rotated in a clockwise direction, when a certain wafer rotates past the observation window 20 of reaction chamber 10 upper surface by graphite pallet 30, the Infrared that FTIR spectrum analyzer 40 is launched is irradiated in the epi-layer surface of this wafer after optical fiber 41 converges.Infrared, after the reflection of epitaxial loayer and wafer, is received the Infrared be reflected back, then injects FTIR spectrum analyzer 40 along optical fiber 41 by optical fiber 41.
In an embodiment of the present invention, epitaxial apparatus also comprises host computer 50.As shown in Figure 3, the reflective infrared light injecting FTIR spectrum analyzer 40 interferes after Michelson interference device, after index glass scanning, obtain interference spectrum.The interference spectrum produced due to reality generally has distortion, therefore, needs the Fourier transform process through software to carry out mathematics correction, calculates the epitaxy layer thickness of wafer, and export to host computer 50 in real time after revising.Host computer 50 has memory and display, the epitaxy layer thickness of this moment wafer can be stored in memory, show the epitaxy layer thickness of this wafer simultaneously in the display.
In an embodiment of the present invention, host computer 50 is also for the average growth rate of the epitaxy layer thickness calculating wafer of the wafer according to the different observation time point collection of optical fiber type FTIR spectrum 40 analyzer.Specifically, along with graphite pallet 30 continues to be rotated in a clockwise direction, when same wafer rotates past the observation window 20 of reaction chamber 10 upper surface again, again can measure the epitaxy layer thickness of this wafer that have passed through after a swing circle, the method when method of measurement and above-mentioned wafer first time rotate past the observation window 20 of reaction chamber 10 upper surface is identical.Thus, in conjunction with the epitaxy layer thickness to twice measurement of different time on same wafer, the growth rate of the epitaxial loayer of this wafer can be calculated, that is,
V＝Δd/Δt
Wherein, V represents growth rate, and Δ d represents the epitaxy layer thickness change between twice measurement of same wafer, and Δ t represents the time interval between twice measurement of same wafer.Host computer 50 can by growth rate, and the data such as the time dependent curve of growth rate store in memory, are presented on the display of host computer 50 with the form of curvilinear figure simultaneously.
The epitaxial apparatus of the embodiment of the present invention, by arranging observation window on reaction chamber, and utilize optical fiber to carry out Fourier transform infrared spectroscopy measurement to the epitaxial loayer of wafer in epitaxial process, and carry out Real-time Collection by the data of host computer to measurement and analyze the epitaxy layer thickness obtaining wafer, thus, real-time instruction can be carried out to epitaxial process, epitaxial process is made to become more controlled, significantly improve in epitaxial process the yields of producing product, effectively prevent because technological parameter selects the improper waste product brought, be conducive to the output improving raw-material utilance and epitaxial apparatus in epitaxial process simultaneously.
Fig. 4 is the structural representation of the epitaxial apparatus of another embodiment of the present invention.
As shown in Figure 4, epitaxial apparatus comprises reaction chamber 10, observation window 20, pallet 30, optical fiber type FTIR spectrum analyzer 40, host computer 50, guide rail 60 and drive unit 70, and wherein, optical fiber type FTIR spectrum analyzer 40 comprises optical fiber 41.
Particularly, as shown in Figure 4, guide rail 60 is installed on observation window 20, and one end of optical fiber 41 is installed on guide rail 60.Drive unit 70 slides on guide rail 60 for controlling optical fiber 41 under the control of host computer 50, with the epitaxy layer thickness making optical fiber type FTIR spectrum analyzer 40 gather multiple observation station on wafer, wherein, host computer 50 also for accessory drive 70, and calculates the thickness evenness of wafer according to the epitaxy layer thickness of multiple observation station.Specifically, the guide rail 60 that can slide is installed above the observation window 20 on reaction chamber 10 upper surface, one end of the optical fiber 41 of optical fiber type FTIR spectrum analyzer 40 is positioned on guide rail 60, launches Infrared by optical fiber 41 and receive the reflective infrared light be reflected back from wafer.Wherein, in advance several observation stations can be set on guide rail 60, such as, 4 observation stations as shown in Figure 5.
In an embodiment of the present invention, the Infrared that FTIR spectrum analyzer 40 is launched by optical fiber 41 carries out converging to form hot spot, and hot spot is exposed to wafer.Specifically, the parallel Infrared emitted from FTIR spectrum analyzer 40 is pooled the hot spot being less than 1 millimeter by optical fiber 41, and is irradiated in the epi-layer surface to be measured of wafer by observation window 20 by the hot spot obtained after this focusing.
Furthermore, as shown in Figure 2, in the process that chemical gas phase reaction carries out, graphite pallet 30 is rotated in a clockwise direction, when a certain wafer rotates past the observation window 20 of reaction chamber 10 upper surface by graphite pallet 30, the Infrared that FTIR spectrum analyzer 40 is launched is irradiated in the epi-layer surface of this wafer in the position of the first observation station after optical fiber 41 converges.Infrared, after the reflection of epitaxial loayer and wafer, is received the Infrared be reflected back, then injects FTIR spectrum analyzer 40 along optical fiber 41 by optical fiber 41.
In an embodiment of the present invention, epitaxial apparatus also comprises host computer 50.As shown in Figure 3, the reflective infrared light injecting FTIR spectrum analyzer 40 interferes after Michelson interference device, after index glass scanning, obtain interference spectrum.The interference spectrum produced due to reality generally has distortion, therefore, needs the Fourier transform process through software to carry out mathematics correction, calculates the epitaxy layer thickness of wafer, and export to host computer 50 in real time after revising.Host computer 50 has memory and display, the epitaxy layer thickness that the first observation station position is measured the wafer obtained can be stored in memory, show the epitaxy layer thickness of wafer simultaneously in the display.
In an embodiment of the present invention, after the measurement in the first observation station completes, by rail plate 60, the position of optical fiber 41 is moved in the second observation station, repeat the measurement in the first observation station, and after the measurement in the second observation station completes, continue through rail plate 60 position of optical fiber 41 is moved in the 3rd observation station, proceed to measure, until complete the measurement in an in the end observation station.Host computer 50 is by the epitaxy layer thickness of the wafer in each observation station of acquisition in real time, and in conjunction with the positional information that each observation station is residing on wafer, the epitaxy layer thickness of the wafer in different observation station can be analyzed, thus obtain the uniformity of the epitaxy layer thickness of wafer.
The epitaxial apparatus of the embodiment of the present invention, by arranging guide rail on the observation window of reaction chamber, and multiple observation station is set on guide rail, utilize optical fiber in each observation station to epitaxial process in the epitaxial loayer of wafer carry out Fourier transform infrared spectroscopy measurement, and carry out Real-time Collection by the data of host computer to measurement and analyze the uniformity obtaining the epitaxy layer thickness of wafer, thus, the uniformity of the epitaxy layer thickness of wafer can be accurately measured, real-time instruction is carried out to epitaxial process, makes epitaxial process become more controlled.
As shown in Figure 4, in one embodiment of the invention, host computer 50 is also for the surface smoothness of the epi-layer surface of the Strength co-mputation wafer according to interference peaks in the interference spectrum of reverberation, and surface smoothness location distribution information.Specifically, the Infrared be reflected back is received at optical fiber 41, then along after FTIR spectrum analyzer 40 injected by optical fiber 41, the reflects infrared light of input FTIR spectrum analyzer 40 interferes after Michelson interference device, after index glass scanning, obtain interference spectrum.Because the intensity of interference peaks in interference spectrum is relevant with the evenness of wafer epitaxial loayer upper and lower surface, and the evenness of the lower surface of wafer epitaxial loayer (i.e. crystal column surface) is constant, so can represent the evenness of wafer epi-layer surface by interference peaks intensity.If specify that a certain interference peaks intensity is 100%, the surface smoothness of whole wafer epitaxial loayer in epitaxial process change curve and location distribution information in time can be obtained.Such as, if specify that a certain interference peaks intensity is I
0, the interference peaks intensity I of crystal column surface diverse location can be recorded in the observation of different observation station by pallet 30
1, I
2in, by interfering strong kurtosis and film thickness relation:
dn＝λasin(In/I
0)
1/2/(2m)，
Wherein, λ is infrared light wavelength, and m is the refractive index of infrared light.
The wafer surface flatness TTV value characterizing wafer surface flatness can be obtained, by calculating as follows:
TTV＝max(d
0、d
1、d
2…dn)-min(d
0、d
1、d
2…dn)。
The normalization surface smoothness that host computer 50 obtains by analysis, can also with the form of time history plot or location map by the surface smoothness of the epi-layer surface of wafer, and surface smoothness location distribution information is presented on the display of host computer 50 in real time, stores in memory simultaneously.
In an embodiment of the present invention, host computer 50 also adjusts for the one or more process conditions to epitaxial apparatus in the surface smoothness of the epi-layer surface of the average growth rate according to wafer, thickness evenness, wafer and surface smoothness location distribution information.Such as, host computer 50 can be regulated and controled growth rate by the flow controlling chemical reaction source, is divided adjust etc. thickness evenness by the flow and flow field adjusting carrier gas.
The epitaxial apparatus of the embodiment of the present invention, by calculating the surface smoothness of the epi-layer surface of wafer, and surface smoothness location distribution information, can feed back epitaxial process by these data and instruct, technologist can carry out real-time adjustment according to these data to process conditions, further increases production efficiency.Meanwhile, these data measured can expand the degree of freedom of research, enrich experimental data, improve conventional efficient, reduce development cost.
In order to realize above-described embodiment, the present invention also proposes a kind of method of measurement of epitaxial process epitaxial layers.
Fig. 6 is the flow chart of the method for measurement of the epitaxial process epitaxial layers of one embodiment of the invention.
As shown in Figure 6, the method for measurement of epitaxial process epitaxial layers comprises:
S601, fibre optical transmission Infrared, and by observation window Infrared exposed to the wafer that the pallet that is arranged in reaction chamber carries.
Particularly, observation window is arranged on the roof of reaction chamber, and pallet is arranged in reaction chamber, and pallet carries wafer.Specifically, the method for measurement of the epitaxial process epitaxial layers in the N-shaped silicon epitaxy layer explanation embodiment of the present invention of phosphorus (P) element is mixed for extension on silicon (Si) substrate of heavily doped arsenic (As).Adopt horizontal air inlet quartz reaction chamber to grow n-Si epitaxial loayer on n+ wafer, wherein, brilliant diameter of a circle is approximately 8 inches, namely 200 millimeters.As shown in Figure 2, graphite pallet is in reaction chamber, and the graphite pallet of SiC parcel is placed the wafer of 58 inches, and the angle between the center of circle of adjacent 2 wafer and the center of circle of graphite pallet is 72 degree.In epitaxial process, graphite support dish is rotated in a clockwise direction, and occurs uniformly on each wafer to impel chemical reaction.Preferably, reaction pressure is-1.5mbar, and growth temperature is 1070 DEG C, and reaction source is SiHCL3, and carrier gas is H2.
S602, optical fiber receives the reverberation of wafer reflection by observation window, detects the epitaxy layer thickness of wafer to make optical fiber type FTIR spectrum analyzer according to reverberation.
Particularly, as shown in Figure 2, optical fiber one end of optical fiber type FTIR spectrum analyzer is positioned over the observation station position above the observation window on reaction chamber upper surface, by fibre optical transmission Infrared.
In an embodiment of the present invention, the Infrared that FTIR spectrum analyzer is launched carries out converging to form hot spot by optical fiber, and hot spot is exposed to wafer.Specifically, the parallel Infrared emitted from FTIR spectrum analyzer is pooled the hot spot being less than 1 millimeter by optical fiber, and is irradiated in the epi-layer surface to be measured of wafer by observation window by the hot spot obtained after this focusing.
Furthermore, as shown in Figure 2, in the process that chemical gas phase reaction carries out, graphite support dish is rotated in a clockwise direction, when a certain wafer is by the observation window of graphite support disc spins through reaction chamber upper surface, the Infrared that FTIR spectrum analyzer is launched is irradiated in the epi-layer surface of this wafer after optical fiber converges.Infrared, after the reflection of epitaxial loayer and wafer, is received the Infrared be reflected back, then injects FTIR spectrum analyzer along optical fiber by optical fiber.
In an embodiment of the present invention, as shown in Figure 3, the reflective infrared light injecting FTIR spectrum analyzer interferes after Michelson interference device, after index glass scanning, obtain interference spectrum.The interference spectrum produced due to reality generally has distortion, therefore, needs the Fourier transform process through software to carry out mathematics correction, calculates the epitaxy layer thickness of wafer, and export to host computer in real time after revising.Host computer has memory and display, the epitaxy layer thickness of this moment wafer can be stored in memory, show the epitaxy layer thickness of this wafer simultaneously in the display.
In an embodiment of the present invention, host computer calculates the average growth rate of wafer according to the epitaxy layer thickness of the wafer of the different observation time point collection of optical fiber type FTIR spectrum analyzer.Specifically, along with graphite pallet continues to be rotated in a clockwise direction, when same wafer rotates past the observation window of reaction chamber upper surface again, again can measure the epitaxy layer thickness of this wafer that have passed through after a swing circle, the method when method of measurement and above-mentioned wafer first time rotate past the observation window of reaction chamber upper surface is identical.Thus, in conjunction with the epitaxy layer thickness to twice measurement of different time on same wafer, the growth rate of the epitaxial loayer of this wafer can be calculated, that is,
V＝Δd/Δt
Wherein, V represents growth rate, and Δ d represents the epitaxy layer thickness change between twice measurement of same wafer, and Δ t represents the time interval between twice measurement of same wafer.Host computer can by growth rate, and the data such as the time dependent curve of growth rate store in memory, are presented on the display of host computer with the form of curvilinear figure simultaneously.
The method of measurement of the epitaxial process epitaxial layers of the embodiment of the present invention, by arranging observation window on reaction chamber, and utilize optical fiber to carry out Fourier transform infrared spectroscopy measurement to the epitaxial loayer of wafer in epitaxial process, and carry out Real-time Collection by the data of host computer to measurement and analyze the epitaxy layer thickness obtaining wafer, thus, real-time instruction can be carried out to epitaxial process, epitaxial process is made to become more controlled, significantly improve in epitaxial process the yields of producing product, effectively prevent because technological parameter selects the improper waste product brought, be conducive to the output improving raw-material utilance and epitaxial apparatus in epitaxial process simultaneously.
Fig. 7 is the flow chart of the method for measurement of the epitaxial process epitaxial layers of another embodiment of the present invention.
As shown in Figure 7, the method for measurement of epitaxial process epitaxial layers comprises:
S701, fibre optical transmission Infrared, and by observation window Infrared exposed to the wafer that the pallet that is arranged in reaction chamber carries.
S702, optical fiber receives the reverberation of wafer reflection by observation window, detects the epitaxy layer thickness of wafer to make optical fiber type FTIR spectrum analyzer according to reverberation.
S703, optical fiber type FTIR spectrum analyzer gathers the epitaxy layer thickness of multiple observation station on wafer, and wherein, host computer calculates the thickness evenness of wafer according to the epitaxy layer thickness of multiple observation station.
Particularly, as shown in Figure 5, guide rails assembling is on observation window, and one end of optical fiber is installed on guide rail.Drive unit is used for controlling optical fiber at slide on rails under the control of host computer, with the epitaxy layer thickness making optical fiber type FTIR spectrum analyzer gather multiple observation station on wafer, wherein, host computer also for accessory drive, and calculates the thickness evenness of wafer according to the epitaxy layer thickness of multiple observation station.Specifically, the guide rail that can slide is installed above the observation window on reaction chamber upper surface, one end of the optical fiber of optical fiber type FTIR spectrum analyzer is positioned on guide rail, the reflective infrared light be reflected back from wafer by fibre optical transmission Infrared and reception.Wherein, several observation stations can be set on guide rail in advance, such as, 4 observation stations as shown in Figure 5.
In an embodiment of the present invention, the Infrared that FTIR spectrum analyzer is launched carries out converging to form hot spot by optical fiber, and hot spot is exposed to wafer.Specifically, the parallel Infrared emitted from FTIR spectrum analyzer is pooled the hot spot being less than 1 millimeter by optical fiber, and is irradiated in the epi-layer surface to be measured of wafer by observation window by the hot spot obtained after this focusing.
Furthermore, as shown in Figure 2, in the process that chemical gas phase reaction carries out, graphite support dish is rotated in a clockwise direction, when a certain wafer is by the observation window of graphite support disc spins through reaction chamber upper surface, the Infrared that FTIR spectrum analyzer is launched is irradiated in the epi-layer surface of this wafer in the position of the first observation station after optical fiber converges.Infrared, after the reflection of epitaxial loayer and wafer, is received the Infrared be reflected back, then injects FTIR spectrum analyzer along optical fiber by optical fiber.
In an embodiment of the present invention, as shown in Figure 3, the reflective infrared light injecting FTIR spectrum analyzer interferes after Michelson interference device, after index glass scanning, obtain interference spectrum.The interference spectrum produced due to reality generally has distortion, therefore, needs the Fourier transform process through software to carry out mathematics correction, calculates the epitaxy layer thickness of wafer, and export to host computer in real time after revising.Host computer has memory and display, the epitaxy layer thickness that the first observation station position is measured the wafer obtained can be stored in memory, show the epitaxy layer thickness of wafer simultaneously in the display.
In an embodiment of the present invention, after the measurement in the first observation station completes, by rail plate, the position of optical fiber is moved in the second observation station, repeat the measurement in the first observation station, and after the measurement in the second observation station completes, continue through rail plate the position of optical fiber is moved in the 3rd observation station, proceed to measure, until complete the measurement in an in the end observation station.Host computer is by the epitaxy layer thickness of the wafer in each observation station of acquisition in real time, and in conjunction with the positional information that each observation station is residing on wafer, the epitaxy layer thickness of the wafer in different observation station can be analyzed, thus obtain the uniformity of the epitaxy layer thickness of wafer.
The method of measurement of the epitaxial process epitaxial layers of the embodiment of the present invention, by arranging guide rail on the observation window of reaction chamber, and multiple observation station is set on guide rail, utilize optical fiber in each observation station to epitaxial process in the epitaxial loayer of wafer carry out Fourier transform infrared spectroscopy measurement, and carry out Real-time Collection by the data of host computer to measurement and analyze the uniformity obtaining the epitaxy layer thickness of wafer, thus, the uniformity of the epitaxy layer thickness of wafer can be accurately measured, real-time instruction is carried out to epitaxial process, makes epitaxial process become more controlled
Fig. 8 is the flow chart of the method for measurement of the epitaxial process epitaxial layers of another embodiment of the present invention.
As shown in Figure 8, the method for measurement of epitaxial process epitaxial layers comprises:
S801, fibre optical transmission Infrared, and by observation window Infrared exposed to the wafer that the pallet that is arranged in reaction chamber carries.
S802, optical fiber receives the reverberation of wafer reflection by observation window, detects the epitaxy layer thickness of wafer to make optical fiber type FTIR spectrum analyzer according to reverberation.
S803, optical fiber type FTIR spectrum analyzer gathers the epitaxy layer thickness of multiple observation station on wafer, and wherein, host computer calculates the thickness evenness of wafer according to the epitaxy layer thickness of multiple observation station.
S804, host computer is according to the surface smoothness of the epi-layer surface of the Strength co-mputation wafer of interference peaks in the interference spectrum of reverberation, and surface smoothness location distribution information.
Particularly, the Infrared be reflected back is received at optical fiber, then along after FTIR spectrum analyzer injected by optical fiber, the reflects infrared light of input FTIR spectrum analyzer interferes after Michelson interference device, after index glass scanning, obtain interference spectrum.Because the intensity of interference peaks in interference spectrum is relevant with the evenness of wafer epitaxial loayer upper and lower surface, and the evenness of the lower surface of wafer epitaxial loayer (i.e. crystal column surface) is constant, so can represent the evenness of wafer epi-layer surface by interference peaks intensity.Such as, if specify that a certain interference peaks intensity is 100%, the surface smoothness of whole wafer epitaxial loayer in epitaxial process change curve and location distribution information in time can be obtained.Such as, if specify that a certain interference peaks intensity is I0, the interference peaks intensity I of crystal column surface diverse location can be recorded in the observation of different observation station by pallet 30
1, I
2in, by interfering strong kurtosis and film thickness relation:
dn＝λasin(In/I
0)
1/2/(2m)，
Wherein, λ is infrared light wavelength, and m is the refractive index of infrared light.
The wafer surface flatness TTV value characterizing wafer surface flatness can be obtained, by calculating as follows:
TTV＝max(d
0、d
1、d
2…dn)-min(d
0、d
1、d
2…dn)。
The normalization surface smoothness that host computer 50 obtains by analysis, can also with the form of time history plot or location map by the surface smoothness of the epi-layer surface of wafer, and surface smoothness location distribution information is presented on the display of host computer in real time, store in memory simultaneously.
S805, host computer adjusts according to the one or more process conditions to epitaxial apparatus in the surface smoothness of the epi-layer surface of the average growth rate of wafer, thickness evenness, wafer and surface smoothness location distribution information.
Such as, host computer can be regulated and controled growth rate by the flow controlling chemical reaction source, is divided adjust etc. thickness evenness by the flow and flow field adjusting carrier gas.
The method of measurement of the epitaxial process epitaxial layers of the embodiment of the present invention, by calculating the surface smoothness of the epi-layer surface of wafer, and surface smoothness location distribution information, can feed back epitaxial process by these data and instruct, technologist can carry out real-time adjustment according to these data to process conditions, further increases production efficiency.Meanwhile, these data measured can expand the degree of freedom of research, enrich experimental data, improve conventional efficient, reduce development cost.
Should be appreciated that each several part of the present invention can realize with hardware, software, firmware or their combination.In the above-described embodiment, multiple step or method can with to store in memory and the software performed by suitable instruction execution system or firmware realize.Such as, if realized with hardware, the same in another embodiment, can realize by any one in following technology well known in the art or their combination: the discrete logic with the logic gates for realizing logic function to data-signal, there is the application-specific integrated circuit (ASIC) of suitable combinational logic gate circuit, programmable gate array (PGA), field programmable gate array (FPGA) etc.
In the present invention, unless otherwise clearly defined and limited, term " installation ", " being connected ", " connection ", etc. term should be interpreted broadly, such as, can be fixedly connected with, also can be removably connect, or integral; Can be mechanical connection, also can be electrical connection; Can be directly be connected, also indirectly can be connected by intermediary, can be the connection of two element internals or the interaction relationship of two elements, unless otherwise clear and definite restriction.For the ordinary skill in the art, above-mentioned term concrete meaning in the present invention can be understood as the case may be.
In the description of this specification, specific features, structure, material or feature that the description of reference term " embodiment ", " some embodiments ", " example ", " concrete example " or " some examples " etc. means to describe in conjunction with this embodiment or example are contained at least one embodiment of the present invention or example.In this manual, to the schematic representation of above-mentioned term not must for be identical embodiment or example.And the specific features of description, structure, material or feature can combine in one or more embodiment in office or example in an appropriate manner.In addition, when not conflicting, the feature of the different embodiment described in this specification or example and different embodiment or example can carry out combining and combining by those skilled in the art.
Although illustrate and describe embodiments of the invention above, be understandable that, above-described embodiment is exemplary, can not be interpreted as limitation of the present invention, and those of ordinary skill in the art can change above-described embodiment within the scope of the invention, revises, replace and modification.
Claims (12)
1. an epitaxial apparatus, is characterized in that, comprising:
Reaction chamber;
Be arranged on the observation window on described reaction chamber;
Be arranged on the pallet in described reaction chamber, described pallet carries wafer;
Optical fiber type FTIR spectrum analyzer, described optical fiber type FTIR spectrum analyzer has optical fiber, one end of described optical fiber is corresponding with described observation window, described optical fiber is for launching Infrared, and by described observation window, described Infrared is exposed to described wafer, and the reverberation of described wafer reflection is received by described observation window, described optical fiber type FTIR spectrum analyzer is used for the epitaxy layer thickness detecting described wafer according to described reverberation.
2. epitaxial apparatus as claimed in claim 1, is characterized in that, the Infrared of described optical fiber also for being launched by described FTIR spectrum analyzer carries out converging to form hot spot, and described hot spot is exposed to described wafer.
3. epitaxial apparatus as claimed in claim 1, is characterized in that, also comprise:
Host computer, the epitaxy layer thickness for the described wafer according to the collection of described optical fiber type FTIR spectrum analyzer different observation time point calculates the average growth rate of described wafer.
4. epitaxial apparatus as claimed in claim 3, is characterized in that, also comprise:
Guide rail, described guide rails assembling is on described observation window, and one end of described optical fiber is installed on described guide rail;
Drive unit, described drive unit is used under the control of described host computer, controlling described optical fiber at described slide on rails, the epitaxy layer thickness of multiple observation station on described wafer is gathered to make described optical fiber type FTIR spectrum analyzer, wherein, described host computer also for controlling described drive unit, and calculates the thickness evenness of described wafer according to the epitaxy layer thickness of described multiple observation station.
5. epitaxial apparatus as claimed in claim 3, it is characterized in that, described host computer is also for the surface smoothness of the epi-layer surface of wafer according to the Strength co-mputation of interference peaks in the interference spectrum of described reverberation, and surface smoothness location distribution information.
6. the epitaxial apparatus as described in any one of claim 3-5, it is characterized in that, described host computer also adjusts for the one or more process conditions to described epitaxial apparatus in the surface smoothness of the epi-layer surface of the described average growth rate according to described wafer, described thickness evenness, described wafer and surface smoothness location distribution information.
7. a method of measurement for epitaxial process epitaxial layers, is characterized in that, optical fiber type FTIR spectrum analyzer has optical fiber, and one end of described optical fiber is corresponding with the observation window be arranged on reaction chamber, and described method comprises:
Described fibre optical transmission Infrared, and by described observation window described Infrared exposed to the wafer that the pallet that is arranged in described reaction chamber carries, described optical fiber receives the reverberation of described wafer reflection by described observation window, with the epitaxy layer thickness making described optical fiber type FTIR spectrum analyzer detect described wafer according to described reverberation.
8. the method for measurement of epitaxial process epitaxial layers as claimed in claim 7, it is characterized in that, described fibre optical transmission Infrared specifically comprises:
The Infrared that described FTIR spectrum analyzer is launched carries out converging to form hot spot by described optical fiber, and described hot spot is exposed to described wafer.
9. the method for measurement of epitaxial process epitaxial layers as claimed in claim 7, is characterized in that, after described optical fiber type FTIR spectrum analyzer to detect the epitaxy layer thickness of described wafer according to described reverberation, also comprises:
Host computer calculates the average growth rate of described wafer according to the epitaxy layer thickness of the described wafer of described optical fiber type FTIR spectrum analyzer different observation time point collection.
10. the method for measurement of epitaxial process epitaxial layers as claimed in claim 9, is characterized in that, also comprise:
Described optical fiber type FTIR spectrum analyzer gathers the epitaxy layer thickness of multiple observation station on described wafer, and wherein, described host computer calculates the thickness evenness of described wafer according to the epitaxy layer thickness of described multiple observation station.
The method of measurement of 11. epitaxial process epitaxial layers as claimed in claim 9, is characterized in that, also comprise:
The surface smoothness of described host computer epi-layer surface of wafer according to the Strength co-mputation of interference peaks in the interference spectrum of described reverberation, and surface smoothness location distribution information.
The method of measurement of 12. epitaxial process epitaxial layers as described in any one of claim 9-11, is characterized in that, also comprise:
Described host computer adjusts according to the one or more process conditions to described epitaxial apparatus in the surface smoothness of the epi-layer surface of the described average growth rate of described wafer, described thickness evenness, described wafer and surface smoothness location distribution information.
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| CN111174716A (en) * | 2019-11-13 | 2020-05-19 | 西安奕斯伟硅片技术有限公司 | Epitaxial layer thickness testing device and method |
| CN112880737A (en) * | 2021-01-14 | 2021-06-01 | 四川雅吉芯电子科技有限公司 | Integrated system for detecting monocrystalline silicon epitaxial wafer |
| CN114739300A (en) * | 2022-03-29 | 2022-07-12 | 上海优睿谱半导体设备有限公司 | Method for measuring epitaxial layer thickness of epitaxial wafer |
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| CN112880737A (en) * | 2021-01-14 | 2021-06-01 | 四川雅吉芯电子科技有限公司 | Integrated system for detecting monocrystalline silicon epitaxial wafer |
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