CN114121642A - Etching method for adjusting etching morphology of through hole in real time and semiconductor etching equipment - Google Patents

Etching method for adjusting etching morphology of through hole in real time and semiconductor etching equipment Download PDF

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CN114121642A
CN114121642A CN202111258274.7A CN202111258274A CN114121642A CN 114121642 A CN114121642 A CN 114121642A CN 202111258274 A CN202111258274 A CN 202111258274A CN 114121642 A CN114121642 A CN 114121642A
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etching
slope
hole
specific
adjusting
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国唯唯
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Beijing Naura Microelectronics Equipment Co Ltd
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Beijing Naura Microelectronics Equipment Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
    • H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
    • H01L21/306—Chemical or electrical treatment, e.g. electrolytic etching
    • H01L21/3065—Plasma etching; Reactive-ion etching
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/30—Electron-beam or ion-beam tubes for localised treatment of objects
    • H01J37/305—Electron-beam or ion-beam tubes for localised treatment of objects for casting, melting, evaporating or etching
    • H01J37/3053—Electron-beam or ion-beam tubes for localised treatment of objects for casting, melting, evaporating or etching for evaporating or etching
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/32917—Plasma diagnostics
    • H01J37/32935—Monitoring and controlling tubes by information coming from the object and/or discharge
    • H01J37/32972—Spectral analysis
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/32917—Plasma diagnostics
    • H01J37/3299—Feedback systems
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
    • H01L21/67005—Apparatus not specifically provided for elsewhere
    • H01L21/67242—Apparatus for monitoring, sorting or marking
    • H01L21/67253—Process monitoring, e.g. flow or thickness monitoring
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
    • H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
    • H01L21/768—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics
    • H01L21/76898—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics formed through a semiconductor substrate

Abstract

The invention discloses an etching method for adjusting the etching morphology of a through hole in real time and a semiconductor etching device, wherein the method comprises the following steps: step 1: carrying out through hole etching process on the wafer in the process chamber based on a preset process formula; step 2: collecting an OES spectrum generated by glow discharge of reaction gas plasma in a process chamber, acquiring the spectrum signal intensity corresponding to the luminescence wavelength of a specific element in the OES spectrum in real time, and calculating the slope of the spectrum signal intensity; and step 3: if the slope of the current moment is within the corresponding reference slope range, continuing the etching process, and if the slope of the current moment is outside the corresponding reference slope range, adjusting specific process parameters to enable the slope of the spectrum signal intensity corresponding to the luminous wavelength of the specific element at the next moment to be within the reference slope range corresponding to the next moment; and 4, step 4: and repeating the step 2-3 until the through hole etching process is completed. The consistency of the appearance of the continuously etched through holes is improved.

Description

Etching method for adjusting etching morphology of through hole in real time and semiconductor etching equipment
Technical Field
The invention relates to the technical field of semiconductor through hole etching, in particular to an etching method for adjusting through hole etching morphology in real time and semiconductor etching equipment.
Background
The GaAs material has the characteristics of wide forbidden band, high frequency, high voltage, radiation resistance, high temperature resistance, high luminous efficiency and the like, and the downstream application fields comprise: the working frequency of the system is mainly within 8GHz, and the system is suitable for medium and low power devices such as micro base stations, mobile phone radio frequency materials and the like. Although GaAs materials have excellent electrical characteristics, their thermal conductivity is poor, making it difficult to effectively remove heat generated from devices. The general solution is to form through holes from the back side to the front side of the wafer, thereby forming good heat dissipation channels.
The back hole process is one of the last stages in the device manufacturing process, after the front face process is completed, a wafer is bonded to a slide and the GaAs substrate is thinned to about 100 μm, then photoetching and patterning and plasma etching are carried out until the front face metal layer is cut off, metal interconnection is carried out after the photoresist is removed, fig. 1 shows a schematic diagram of back hole etching of the GaAs substrate, and as shown in fig. 1, the back hole process structure comprises a back metal 1, a GaAs substrate 2, a GaAs device front face structure 3 (comprising a metal layer) and a metal electrode 4.
The GaAs back hole process usually adopts a photoresist mask, and the etching morphology comprises vertical holes, Y-shaped holes, V-shaped holes and the like, wherein the mask angle of the vertical holes is about 75-90 degrees, the mask angles of the Y-shaped holes and the V-shaped holes are about 30-45 degrees, and the required etching morphology is realized by optimizing process parameters. High speed and high selectivity are required for etching, and because of slight difference of the thinned thickness of GaAs, Optical Emission Spectroscopy (OES) is generally adopted for etching endpoint detection.
OES (atomic spectrometer) is a device commonly used in semiconductor devices to determine the state of the interior of a chamber. The principle is that each gas or element has corresponding luminous wavelength by distinguishing the spectrum generated by plasma glow discharge in the process through a grating, and when the content of a certain gas or element is increased or reduced, the intensity of the corresponding luminous line is increased or reduced. The status of the process proceeding is confirmed from the change of the spectra of different wavelengths over time and is often used for endpoint detection. In different film layer structures, the elements corresponding to different layers are different, and further, the detected spectrum after etching is also different. The OES common detecting elements and corresponding wavelengths are shown in Table 1.
TABLE 1-1 wavelength table corresponding to different detecting elements
Element(s) Ga Al In Si SiN CO
Wavelength (nm) 417.2 396.1 451.1 288.2 440.7 519.8
In general, the GaAs back hole process only detects the decrease of the spectrum intensity of the Ga-417 nm element (namely, the GaAs film layer is etched completely) to judge the end point.
The GaAs back hole side wall appearance is greatly influenced by an etching selection ratio (the selection ratio is GaAs etching rate/PR etching rate), when the selection ratio is low, the side wall is inclined, and when the selection ratio is high, the side wall is close to vertical. Process parameters such as pressure, upper rf power, lower rf power, total gas flow and ratio, and wafer surface temperature all have an effect on the selectivity ratio. The existing inductively coupled plasma etching process adopts constant process parameters to operate, and is influenced by factors such as light-sensitive strip part difference, temperature parameter difference between different Run times of equipment, chamber environment difference and the like, so that the appearance of the side wall after continuous operation is different, and the performance of a device is further influenced.
Disclosure of Invention
The invention aims to provide an etching method for adjusting the etching morphology of a through hole in real time and semiconductor etching equipment, which are used for improving the consistency of the morphology of the side wall of the through hole in continuous through hole etching.
In order to achieve the purpose, the invention provides an etching method for adjusting the etching morphology of a through hole in real time, which comprises the following steps:
step 1: carrying out through hole etching process on the wafer in the process chamber based on a preset process formula;
step 2: collecting an OES spectrum generated by glow discharge of reaction gas plasma in the process chamber, acquiring the intensity of a spectrum signal corresponding to the luminescence wavelength of a specific element in the OES spectrum in real time, and calculating the slope of the intensity of the spectrum signal, wherein the slope is the intensity change of the spectrum signal in unit time and is used for representing the ratio of the vertical etching rate to the horizontal etching rate at the current moment;
and step 3: if the slope of the spectrum signal intensity corresponding to the specific element light-emitting wavelength at the current moment is within the corresponding reference slope range, continuing the etching process, and if the slope of the spectrum signal intensity corresponding to the specific element light-emitting wavelength at the current moment is outside the corresponding reference slope range, adjusting specific process parameters to enable the slope of the spectrum signal intensity corresponding to the specific element light-emitting wavelength at the next moment to be within the reference slope range corresponding to the next moment, wherein a functional relationship is formed between the specific process parameters and the slope of the spectrum signal intensity corresponding to the specific element light-emitting wavelength;
and 4, step 4: and repeating the step 2-3 until the through hole etching process is completed.
The invention also provides semiconductor etching equipment which comprises a process chamber, a reaction gas supply system connected with the process chamber, a radio frequency power source, an OES spectrometer and a lower computer;
the reaction gas supply system is used for introducing reaction gas into the process chamber;
the radio frequency power source is used for generating radio frequency power to ionize the reaction gas so as to generate plasma;
the OES spectrometer is used for collecting an OES spectrum generated by the plasma glow discharge in the process chamber and acquiring the spectrum signal intensity corresponding to the luminescence wavelength of a specific element in the OES spectrum in real time;
the lower computer is used for executing the etching method for adjusting the etching morphology of the through hole in real time.
The invention has the beneficial effects that:
the method comprises the steps of collecting an OES spectrum generated by glow discharge of reaction gas plasma in a process chamber, acquiring slope change of spectral signal intensity corresponding to specific element luminous wavelength in the OES spectrum in real time, continuing an etching process if the slope of the current moment is within a corresponding reference slope range, adjusting specific process parameters if the slope of the current moment is outside the corresponding reference slope range, enabling the slope of the spectral signal intensity corresponding to the specific element luminous wavelength of the next moment to be within the reference slope range corresponding to the next moment, and realizing improvement of consistency of side wall morphology of the through hole in the continuous etching process of the through hole based on matching regulation of the real-time slope and the corresponding reference slope range.
The method and apparatus of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings and the following detailed description, which are incorporated herein, and which together serve to explain certain principles of the invention.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent by describing in more detail exemplary embodiments thereof with reference to the attached drawings, in which like reference numerals generally represent like parts.
Fig. 1 shows a schematic diagram of a back hole etching of a conventional GaAs substrate.
FIG. 2 is a step diagram of an etching method for adjusting the etching profile of a via in real time according to the present invention.
FIG. 3 shows a flowchart of an etching method for adjusting the etching profile of a via in real time according to an embodiment of the invention.
Fig. 4 shows OES spectral lines corresponding to vertical hole etching in an etching method for adjusting a via etching profile in real time according to an embodiment of the present invention.
Fig. 5 shows OES spectral lines corresponding to the inclined hole etching in an etching method for adjusting the via etching profile in real time according to an embodiment of the invention.
Fig. 6 shows a schematic structural diagram of a semiconductor etching apparatus according to an embodiment of the present invention.
Detailed Description
In the prior art, in order to solve the problems that the etching rate of the gallium arsenide back hole etching process of the inductively coupled plasma is low, and a micron-sized strut is generated due to the large influence of the surface cleaning degree and the residual residues, the inductively coupled plasma dry etching gallium arsenide back hole process capable of effectively improving the etching back hole quality and greatly improving the etching rate so as to rapidly improve the productivity is provided. The process mainly comprises the following steps:
(1) and adhering the gallium arsenide semiconductor substrate which is processed by the front device process to the sapphire carrier with the front face downward for mechanical thinning and chemical wet etching.
(2) And photoresist is formed on the gallium arsenide semiconductor substrate, and curing heat treatment is carried out to form a photoresist mask.
(3) And developing after exposure on a photoresist photoetching instrument, and transferring and copying the designed back hole pattern on a photoresist mask on the back of the gallium arsenide.
(4) And etching the back hole by using an inductively coupled plasma dry etching machine, and then removing the photoresist and performing surface cleaning treatment. Wherein the dry etching process parameters are as follows: reaction gas Ar/Cl2/BCl3Wherein Cl is2The volume percentage of the air-conditioning agent is 20-80%, and the air pressure is as follows: 8-25 mTorr, total flow of reaction gas: 100-450 sccm, inductive coupling power: 600-1300W, RF bias power: 50-150W. The aim of optimizing the gallium arsenide semiconductor back hole etching process is achieved by regulating and controlling various adjustable parameters of the inductively coupled plasma dry etching process.
The first prior art has the following disadvantages:
the method realizes the purpose of optimizing the gallium arsenide back hole etching process by regulating and controlling process parameters, but adopts constant process parameters to operate, and is influenced by factors such as light-sensitive strip part difference, temperature parameter difference among different Run times of equipment, chamber environment difference and the like, so that the appearance of the side wall after continuous operation is different, and the performance of a device is influenced.
The second prior art discloses a method for detecting the over-etching amount of a metal hard mask integrated etching through hole, wherein in the process of etching the through hole by adopting a metal hard mask integrated etching technology, a spectrum EPD system is used for establishing a spectrum curve of the change of the spectrum signal intensity of an etching product along with time, the stage that the copper is partially contacted with the through hole when the slope change rate of the spectrum curve reaches a first threshold value and the stage that the copper is completely contacted with the through hole when the slope change rate of the spectrum curve reaches a second threshold value in a certain time sequence is defined, the over-etching time of the through hole is calculated from the time point that the through hole is completely contacted with the copper, and the over-etching amount of the through hole is controlled within a certain range by controlling the over-etching time. According to the scheme, the spectrum EPD system is used for non-destructive real-time monitoring, so that the process development cost can be reduced, the production monitoring is enhanced, and the risk is reduced.
The second prior art has the following disadvantages:
in the prior art, endpoint detection is performed through a spectrum EPD system, only the time corresponding to the etching endpoint is determined, and the over-etching time is controlled accordingly. Etching parameters are not adjusted in real time correspondingly through the change of the EPD spectral signals, so that the etching morphology is adjusted in real time.
The invention provides an etching method for adjusting the etching morphology of a through hole in real time, aiming at solving the problem of difference of the etching morphology in continuous etching, wherein the consistency of the morphology of the continuous etching is realized by comparing spectral intensity slope change of specific elements of OES (OES), such as Ga (417nm), with reference spectral data and by continuously adjusting the power of a lower electrode in real time to realize matching with a reference signal.
The invention will be described in more detail below with reference to the accompanying drawings. While the preferred embodiments of the present invention are shown in the drawings, it should be understood that the present invention may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
FIG. 2 is a step diagram of an etching method for adjusting the etching profile of a via in real time according to the present invention.
As shown in fig. 2, an etching method for adjusting the etching morphology of a through hole in real time includes:
step S101: carrying out through hole etching process on the wafer in the process chamber based on a preset process formula;
specifically, the through hole etching process may be a main etching process of back hole etching or a deep hole etching process, and the wafer may be a GaAs substrate or a SiC substrate.
Step S102: collecting an OES spectrum generated by glow discharge of reaction gas plasma in a process chamber, acquiring the spectral signal intensity corresponding to the luminescence wavelength of a specific element in the OES spectrum in real time, and calculating the slope of the spectral signal intensity, wherein the slope is the intensity change of the spectral signal in unit time and is used for representing the ratio of the vertical etching rate to the horizontal etching rate at the current moment;
specifically, before executing step S101, a complete through-hole etching process needs to be performed on a wafer by using process parameters meeting requirements for a specific type of the through-hole etching process, and spectral signal intensity data corresponding to a specific element emission wavelength in a cavity OES spectrum in the complete process is collected;
then, calculating a slope curve of the change of the specific element luminous wavelength corresponding to the spectral signal intensity along with time based on the spectral signal intensity data, and establishing a database based on the multiple complete spectral signal intensity data acquisition of the through hole etching process;
and then, determining the minimum value and the maximum value of the slope of the light-emitting wavelength of the specific element corresponding to the spectral signal intensity at different moments in the through hole etching process as the reference slope range at different moments.
The specific element may be an element contained in a wafer material in a chamber gas, for example, Ga element (417nm signal) in an OES spectrum of the chamber when a GaAs substrate is subjected to via etching by using a chlorine-containing plasma, or an element in a reactant of a reaction gas and a wafer material, for example, SiF element (440nm signal) in an OES spectrum when a SiC substrate is subjected to via etching by using a fluorine-containing plasma. The specific process parameter is preferably a lower radio frequency power value, and can be selected as a wafer surface temperature value.
The slope of the spectral signal intensity corresponding to the specific element luminous wavelength can be regarded as indirect reflection of the ratio of the vertical etching rate to the horizontal etching rate of the etched material, and when the vertical morphology is etched, the slope of the spectral signal intensity corresponding to the specific element luminous wavelength in the spectrum is close to the horizontal in the etching process; when the inclined morphology is etched, in addition to the vertical downward etching rate, the etching products generated by horizontal etching are increased, the intensity of the spectral signal corresponding to the luminous wavelength of the specific element is continuously improved, and the corresponding slope is also continuously increased in the etching process.
In this step, the intensity of the spectral signal corresponding to the emission wavelength of the specific element in the OES spectrum is obtained in real time, and the slope of the intensity of the spectral signal corresponding to the specific element at the current time is determined by calculating the intensity change of the spectral signal within unit time of the intensity of the spectral signal.
Step S103: if the slope of the spectrum signal intensity corresponding to the specific element light-emitting wavelength at the current moment is within the corresponding reference slope range, continuing the etching process, and if the slope of the spectrum signal intensity corresponding to the specific element light-emitting wavelength at the current moment is outside the corresponding reference slope range, adjusting specific process parameters to enable the slope of the spectrum signal intensity corresponding to the specific element light-emitting wavelength at the next moment to be within the reference slope range corresponding to the next moment, wherein the specific process parameters and the slope of the spectrum signal intensity corresponding to the specific element light-emitting wavelength have a functional relationship;
specifically, the functional relationship between the slope of the spectral signal intensity corresponding to the emission wavelength of the specific element and the specific process parameter is as follows:
kt＝nt·△A
wherein k istThe slope corresponding to the luminous wavelength spectrum signal intensity of the specific element at the time t, Delta A is the numerical variation of the specific process parameter, ntThe slope coefficient of change of the specific element spectrum signal intensity caused by the change of the unit parameter value of the specific process parameter at the time t.
In this step, adjusting the specific process parameters includes:
and calculating a parameter value corresponding to the specific process parameter at the next moment according to a functional relation between the slope of the spectrum signal intensity corresponding to the specific element light-emitting wavelength and the specific process parameter, and continuously adjusting the specific process parameter to the parameter value corresponding to the next moment while keeping other process parameters unchanged.
The calculating of the parameter value of the specific process parameter corresponding to the next moment according to the functional relationship between the slope of the spectrum signal intensity corresponding to the specific element light-emitting wavelength and the specific process parameter specifically includes:
when k ist＞k(t,max)When, Aj＝Ai-(kt-k(t,max))/nt；
When k ist＜k(t,min)When, Aj＝Ai+(kt-k(t,min))/nt；
When k ist∈[k(t,min)，k(t,max)]Then, the process is continued;
wherein k istLuminescence wave for specific element at time tSlope of long spectral signal intensity, k(t,max)The upper limit value n of the reference slope range corresponding to the luminous wavelength spectrum signal intensity of the specific element at the time ttThe slope coefficient of change of the specific element spectrum signal intensity caused by the change of the unit parameter value of the specific process parameter at the time t, AiFor a parameter value corresponding to a particular process parameter at time i, AjAnd the parameter value corresponding to the specific process parameter at the moment j.
Step S104: and repeating the steps S102-S103 until the through hole etching process is completed.
Specifically, when the through hole etching process is a main etching process of back hole etching, the spectral signal intensity corresponding to the light-emitting wavelength of the specific element is decreased to mark etching to the etching stop layer, and the main etching process is finished.
When the through hole etching process is a main etching process for back hole etching, the over-etching process is required to be continued after the main etching process is completed, the over-etching process can be continued by adopting all process parameter values at the time when the main etching is completed, and the over-etching time is 10-20% of the main etching time.
The invention is further explained below with reference to an embodiment of a back hole etching process for a GaAs substrate.
Examples
As shown in fig. 3, the GaAs substrate back hole etching process method of this embodiment is specifically as follows:
step S201: determining the minimum value k of the slopes at different moments by using Base Recipe(t,min)And a maximum value k(t,max)。
Carrying out complete through hole etching process by adopting process parameters meeting requirements, collecting OES Ga (417nm) spectrum signals, calculating corresponding slope curve (change of Ga spectrum intensity in unit time), establishing basic database, and determining minimum value k of slopes at different times(t,min)(minimum value of gradient of Ga signal at time t) and maximum value k(t,max)(maximum value of Ga signal slope at time t), wherein the Ga signal slope can be regarded as indirect representation of the ratio of the vertical etching rate to the horizontal etching rate of the GaAs material, as shown in FIG. 4, when the vertical morphology is etched, the Ga signal intensity is close to that of water in the etching processFlattening; as shown in fig. 5, when the tilted profile is etched, in addition to the vertical etching rate, the etching products generated by the horizontal etching are increased, and the Ga signal strength is continuously increased during the etching process.
Step S202: collecting data of influence of the process parameters on the sidewall angle, and confirming the corresponding functional relation between the Ga signal slope and the different lower radio frequency powers by adjusting the different lower radio frequency powers:
kt＝nt·△P
wherein k istGa signal slope at time t, Δ P is lower RF power change, ntThe change of the Ga signal slope caused by the unit power change at the time t is a coefficient;
step S203: performing a main etching process for etching a back hole of the GaAs substrate (the back hole structure can refer to FIG. 1), and collecting an OES Ga (417nm) spectrum signal; the main etching process parameters comprise: pressure is 10-20mT, SRF is 600-1000W, BRF is 100-300W, Cl2Flow rate of 100-3The flow rate is 10-50 sccm;
step S204: the real-time OES data are compared with the reference OES data in real time, and real-time adjustment is carried out, only the radio frequency power of the lower electrode is adjusted in the real-time adjustment process, other process parameters are kept unchanged, and the real-time adjustment steps are as follows:
step S301: will ktAnd [ k ](t,min)，k(t,max)]Comparing the intervals;
step S302: when k ist∈[k(t,min)，k(t,max)]Then, the process is continued;
step S303: when k ist＞k(t,max)Continuously reducing the lower RF power to Pj＝Pi-(kt-k(t,max))/nt；
Step S304: when k ist＜k(t,min)Continuously increasing the lower RF power to Pj＝Pi+(kt-k(t,min))/nt(ii) a Wherein, Pi，PjThe lower electrode power at the moment i and j respectively;
and repeating the steps S301-S304 until the etching reaches the stop layer (the metal etching stop layer on the front surface of the GaAs substrate), and finishing the main etching process when the Ga signal is reduced when the etching reaches the stop layer.
The main etching plays a role in determining the etching morphology, so that the main etching step is mainly adjusted and controlled.
Step S205: and (3) performing an over-etching process, wherein the over-etching is generally performed by adopting the final condition of the step 204, the etching time is generally 10-20% of the main etching time, and finally the whole process step of etching the back hole of the GaAs substrate is completed.
In the embodiment, the change of the optical spectrum intensity slope of the Ga (417nm) element of the OES spectrum is compared with the reference spectrum data, the matching with the reference signal is realized by continuously adjusting the power of the lower electrode in real time, the consistency of the continuous etching morphology is improved, and the problem of the difference of the sidewall morphology in the continuous through hole etching is effectively solved.
It should be noted that, in this embodiment, since the change of the wafer temperature also causes the change of the etching selection ratio, thereby affecting the sidewall angle profile, the continuous change of the lower rf power may also be replaced by the continuous change of the wafer surface temperature. The regulation method is the same as the regulation method based on the lower radio frequency power, and the details are not repeated here for those skilled in the art to easily realize.
Furthermore, the method is not only suitable for GaAs back hole etching, but also suitable for adjusting the side wall angle in the deep hole etching process, for example, in the SiC substrate deep hole etching process, the spectral slope of the SiF (440nm) signal intensity in an OES spectrum can be monitored, and the method is adopted to correspondingly adjust and control the real-time specific process parameters to obtain the result that the slope corresponding to the SiF (440nm) signal intensity is consistent with the target slope.
As shown in fig. 6, an embodiment of the present invention further provides a semiconductor etching apparatus, which includes a process chamber 1, a reactive gas supply system 2 connected to the process chamber, a radio frequency power source 3, an OES spectrometer 4, and a lower computer 5;
the reaction gas supply system 2 is used for introducing reaction gas into the process chamber;
the radio frequency power source 3 is used for generating radio frequency power to ionize reaction gas so as to generate plasma;
the OES spectrometer 4 is used for collecting an OES spectrum generated by plasma glow discharge in the process chamber and acquiring the spectrum signal intensity corresponding to the luminescence wavelength of a specific element in the OES spectrum in real time;
the lower computer 5 is used for executing the etching method for adjusting the etching morphology of the through hole in real time in the steps S101 to S104 of the above embodiment.
Wherein, the rf power source 3 may include an upper rf power source and a lower rf power source, and the OES spectrometer may also be used as an endpoint monitoring device, for example, in the GaAs substrate back hole etching process, when the spectral intensity of the Ga (417nm) element is monitored to gradually decrease, the stop layer is indicated to be etched, and the main etching process is completed. Other components in the etching device of the embodiment are consistent with those of the existing etching machine, and are not described herein again.
In summary, the invention adjusts the side wall angle of the etched through hole in real time by comparing the slope of the luminescent wavelength of the specific element in the OES spectrum with the reference slope and corresponding to the adjustment of the related specific process parameter under continuous change, thereby realizing the consistency of the etching morphology in continuous etching, solving the change of the etching result caused by the changes of the photoresist condition, the chamber temperature, the chamber environment and the like, and realizing higher process result repeatability.
Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

Claims (10)

1. An etching method for adjusting the etching morphology of a through hole in real time is characterized by comprising the following steps:
step 1: carrying out through hole etching process on the wafer in the process chamber based on a preset process formula;
step 2: collecting an OES spectrum generated by glow discharge of reaction gas plasma in the process chamber, acquiring the intensity of a spectrum signal corresponding to the luminescence wavelength of a specific element in the OES spectrum in real time, and calculating the slope of the intensity of the spectrum signal, wherein the slope is the intensity change of the spectrum signal in unit time and is used for representing the ratio of the vertical etching rate to the horizontal etching rate at the current moment;
and step 3: if the slope of the spectrum signal intensity corresponding to the specific element light-emitting wavelength at the current moment is within the corresponding reference slope range, continuing the etching process, and if the slope of the spectrum signal intensity corresponding to the specific element light-emitting wavelength at the current moment is outside the corresponding reference slope range, adjusting specific process parameters to enable the slope of the spectrum signal intensity corresponding to the specific element light-emitting wavelength at the next moment to be within the reference slope range corresponding to the next moment, wherein a functional relationship is formed between the specific process parameters and the slope of the spectrum signal intensity corresponding to the specific element light-emitting wavelength;
and 4, step 4: and repeating the step 2-3 until the through hole etching process is completed.
2. The etching method for adjusting the etching morphology of the through hole in real time according to claim 1, wherein the adjusting of the specific process parameters comprises:
and calculating a parameter value corresponding to the specific process parameter at the next moment according to a functional relation between the slope of the spectrum signal intensity corresponding to the specific element light-emitting wavelength and the specific process parameter, and continuously adjusting the specific process parameter to the parameter value corresponding to the next moment while keeping other process parameters unchanged.
3. The etching method for adjusting the etching morphology of the through hole in real time according to claim 1, wherein the method for obtaining the reference slope range comprises the following steps:
before the step 3, carrying out a through hole etching process on the wafer by adopting process parameters meeting requirements, and acquiring spectral signal intensity data corresponding to the luminescence wavelength of the specific element in the OES spectrum in the process chamber in the process;
calculating a slope curve of the intensity of the spectral signal corresponding to the luminous wavelength of the specific element along with the change of time based on the intensity data of the spectral signal, and establishing a database;
and determining the minimum value and the maximum value of the slope of the spectral signal intensity corresponding to the specific element luminous wavelength at different moments in the through hole etching process as the reference slope range at different moments.
4. The etching method for adjusting the etching morphology of the through hole in real time according to claim 1 or 2, wherein the function relationship between the slope of the spectral signal intensity corresponding to the specific element light-emitting wavelength and the specific process parameter is as follows:
kt＝nt·△A
wherein k istThe slope corresponding to the luminous wavelength spectrum signal intensity of the specific element at the time t, delta A is the numerical value variation of the specific process parameter, ntThe slope coefficient of change of the specific element spectrum signal intensity caused by the change of the specific process parameter unit parameter value at the time t.
5. The etching method for adjusting the etching morphology of the through hole in real time according to claim 2, wherein the step of calculating the parameter value of the specific process parameter corresponding to the next moment according to the functional relationship between the slope of the spectral signal intensity corresponding to the specific element light-emitting wavelength and the specific process parameter comprises the following steps:
when k ist＞k(t,max)When, Aj＝Ai-(kt-k(t,max))/nt；
When k ist＜k(t,min)When, Aj＝Ai+(kt-k(t,min))/nt；
Wherein k istThe slope, k, of the luminescence wavelength spectrum signal intensity of the specific element at time t(t,max)The upper limit value n of the reference slope range corresponding to the luminous wavelength spectrum signal intensity of the specific element at the moment ttFor the time t, the unit parameter value of the specific process parameter changesCoefficient of change in slope of intensity of spectral signal of said specific element, A, caused by quantizationiIs a parameter value corresponding to the specific process parameter at the moment i, AjAnd the parameter value corresponding to the specific process parameter at the moment j.
6. The etching method for adjusting the etching morphology of the through hole in real time according to any one of claims 1 to 5, wherein the through hole etching process is a main etching process of back hole etching or a deep hole etching process.
7. The etching method for adjusting the etching morphology of the through hole in real time according to any one of claims 1 to 5, wherein the specific elements at least comprise elements contained in wafer materials;
the specific process parameter is a lower radio frequency power value or a wafer surface temperature value.
8. The etching method for adjusting the etching morphology of the through hole in real time as claimed in claim 6, wherein when the through hole etching process is a main etching process of back hole etching, the etching is performed to the etching stop layer by using a decrease mark appearing in the intensity of the spectral signal corresponding to the light-emitting wavelength of the specific element, and the main etching process is ended.
9. The etching method for adjusting the etching morphology of the through hole in real time according to claim 8, wherein when the through hole etching process is a main etching process of back hole etching, the method further comprises, after the step 4:
and continuing the over-etching process by adopting all process parameter values at the main etching finishing moment, wherein the over-etching time is 10-20% of the main etching time.
10. The semiconductor etching equipment is characterized by comprising a process chamber, a reaction gas supply system connected with the process chamber, a radio frequency power source, an OES spectrometer and a lower computer;
the reaction gas supply system is used for introducing reaction gas into the process chamber;
the radio frequency power source is used for generating radio frequency power to ionize the reaction gas so as to generate plasma;
the OES spectrometer is used for collecting an OES spectrum generated by the plasma glow discharge in the process chamber and acquiring the spectrum signal intensity corresponding to the luminescence wavelength of a specific element in the OES spectrum in real time;
the lower computer is used for executing the etching method for adjusting the etching morphology of the through hole in real time according to any one of claims 1 to 9.
CN202111258274.7A 2021-10-27 2021-10-27 Etching method for adjusting etching morphology of through hole in real time and semiconductor etching equipment Pending CN114121642A (en)

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