CN115332065A - Wafer uniformity optimization method for ICP (inductively coupled plasma) chamber - Google Patents

Wafer uniformity optimization method for ICP (inductively coupled plasma) chamber Download PDF

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CN115332065A
CN115332065A CN202210835710.0A CN202210835710A CN115332065A CN 115332065 A CN115332065 A CN 115332065A CN 202210835710 A CN202210835710 A CN 202210835710A CN 115332065 A CN115332065 A CN 115332065A
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radio frequency
wafer
value
uniformity
coil
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尹格华
刘海洋
杨宇新
郭磊
李�浩
刘小波
胡冬冬
许开东
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Jiangsu Leuven Instruments 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
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
    • H01J37/32082—Radio frequency generated discharge
    • H01J37/321—Radio frequency generated discharge the radio frequency energy being inductively coupled to the plasma
    • H01J37/3211—Antennas, e.g. particular shapes of coils
    • 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
    • H01J37/32431—Constructional details of the reactor
    • H01J37/32623—Mechanical discharge control means
    • H01J37/32642—Focus rings
    • 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
    • H01L21/67011—Apparatus for manufacture or treatment
    • H01L21/67017—Apparatus for fluid treatment
    • H01L21/67063—Apparatus for fluid treatment for etching
    • H01L21/67069—Apparatus for fluid treatment for etching for drying etching
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L22/00—Testing or measuring during manufacture or treatment; Reliability measurements, i.e. testing of parts without further processing to modify the parts as such; Structural arrangements therefor
    • H01L22/10—Measuring as part of the manufacturing process
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L22/00—Testing or measuring during manufacture or treatment; Reliability measurements, i.e. testing of parts without further processing to modify the parts as such; Structural arrangements therefor
    • H01L22/20—Sequence of activities consisting of a plurality of measurements, corrections, marking or sorting steps

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Abstract

The invention discloses a wafer uniformity optimization method for an ICP (inductively coupled plasma) chamber, which comprises the following steps: s1, continuously monitoring accumulated radio frequency time, and judging the consumption of a focusing ring through the accumulated radio frequency time; when the accumulated radio frequency time exceeds a preset radio frequency time threshold, the step S2 is entered; and S2, aiming at different etching process parameters, changing the power of an outer coil and an inner coil of the inductive coupling coil by adjusting the power distribution of source radio frequency, so that different plasma density distributions are obtained in the edge area and the central area of the wafer, and the change of a plasma sheath layer in the edge area of the wafer caused by the consumption of the focusing ring is compensated. The invention can automatically adjust the I/O power distribution set by the process menu, compensate the change of the distribution and the shape of the plasma sheath layer in the edge area of the wafer caused by the consumption of the focusing ring and maintain the uniformity and stability.

Description

Wafer uniformity optimization method for ICP (inductively coupled plasma) chamber
Technical Field
The invention belongs to the technical field of ICP (inductively coupled plasma) etching, and particularly relates to a wafer uniformity optimization method for an ICP (inductively coupled plasma) chamber.
Background
In the semiconductor integrated circuit manufacturing process, etching is one of the most important processes, and plasma etching is one of the commonly used etching methods. The plasma etching device for processing/treating the semiconductor device mainly comprises a Capacitance Coupling Plasma (CCP) etching device, an Inductance Coupling Plasma (ICP) etching device, an electron cyclotron resonance plasma (ECR) etching device and the like. The ICP etching assembly can be used for processing/treating various metal or nonmetal film layer structures by etching and the like, and is particularly suitable for processing/treating 300mm large-size wafers.
An ICP setup is schematically illustrated in fig. 1. Usually, etching occurs in a vacuum reaction chamber, an electrostatic chuck is placed on a susceptor in the middle of the vacuum reaction chamber, and a wafer is placed on the upper surface of the electrostatic chuck. A source radio frequency is generally connected to an air inlet device at the top of the equipment, and the high-frequency radio frequency power output by a source radio frequency power supply is used for igniting and providing plasma density; a bias radio frequency is connected to the electrostatic adsorption chuck and a base arranged on the electrostatic adsorption chuck, and low-frequency radio frequency power output by a bias radio frequency power supply is used for providing energy and an incident angle of plasma. A focus ring (focus ring) is usually installed at the periphery of the wafer to change the distribution and shape of the plasma sheath (plasma sheath) in the edge region of the wafer.
However, since the focus ring remains in the plasma filled with the etching gas for a long period of time, the material of the upper surface of the focus ring is consumed after the plasma treatment is performed for a certain period of time, and the height is lowered. The decrease in the height of the focus ring may seriously affect the distribution and shape of the plasma sheath in the edge region of the wafer, and an edge tilting phenomenon (as shown in fig. 2) may occur, so that the etching rate and etching direction of the edge region of the wafer may be different from those of the center region, which may reduce the uniformity of the wafer and seriously affect the yield of the chip.
In the prior art, the edge tilting can be solved only by lifting up the focus ring or replacing a new focus ring, so that the uniformity of the wafer is improved. However, the lifting structure of the focus ring is relatively complex, and the arrangement added in the limited lower electrode space has high design difficulty and high manufacturing cost, and only few manufacturers select to use the arrangement. Moreover, the focus ring is usually made of SiC, which is expensive, and frequent replacement of the focus ring will greatly increase the cost of the etching apparatus, not for a long time.
The invention with the publication number of CN102800547A discloses a modulatable focus ring and a method for adjusting a plasma processor by using the focus ring, wherein the focus ring is connected with a temperature adjusting device, a conductive or non-conductive impedance adjusting material is doped in the focus ring, the temperature of the focus ring is adjusted by the temperature adjusting device, the impedance of the focus ring is changed along with the temperature change by utilizing the characteristic that the impedance of the impedance adjusting material changes along with the temperature, and the impedance of the focus ring is adjusted, so that the density distribution of plasmas on the edge of a wafer and the focus ring is adjusted, the density distribution of the plasmas on the surface of the wafer is uniformized, and the process quality of wafer etching is improved. The invention needs to add impedance adjusting material in the focusing ring and must install a temperature adjusting device, and the design difficulty is high.
The invention with the publication number of CN113838730A discloses a gas shielding ring, a plasma processing device and a method for regulating and controlling polymer distribution, wherein the gas shielding ring is adopted to guide reaction gas to flow to an outer ring exhaust area of a plasma confinement ring, so that the difference of polymers generated at the center and the edge of a cavity can be balanced, and the difference of the overall appearance and the absolute diameter of an etched sample is reduced. The invention needs to combine with a gas shielding ring to guide the reaction gas and has a complex structure.
The invention with the publication number of CN113496862A discloses a plasma reactor and a radio frequency power distribution adjusting method thereof, and a coupling ring is adopted to enable the radio frequency of the plasma reactor to be adjustable and reduce arc discharge. The invention dynamically and precisely adjusts the radio frequency power distribution of the low frequency radio frequency power in the center of the substrate and the edge area of the substrate through the coupling ring, so that more low frequency radio frequency power is transmitted to the focusing ring at the edge of the substrate, and further the height of a sheath layer at the focusing ring is changed, thereby improving the uniformity of the substrate processing technology and reducing the arc discharge phenomenon. The invention requires that the focusing ring is made of conductor material or semiconductor material, and the bottom is coated with a conducting layer, and the structure can not be used in ICP etching systems such as metal, poly and the like. The invention is similar to the power distribution design of bias radio frequency (bias), has influence on structures such as an electrostatic chuck, a fault, a filter, HV, a coil and the like, and has complex structure.
In view of the above problems, it is necessary to develop a new adjusting method to more effectively solve the edge tilting phenomenon caused by the consumption of the upper surface of the focus ring and improve the uniformity of the wafer.
Disclosure of Invention
The technical problem to be solved is as follows: aiming at the technical problem that the wafer uniformity is poor due to the edge tilting phenomenon generated by the consumption of the upper surface of the focusing ring, the invention provides a wafer uniformity optimization method for an ICP chamber.
The technical scheme is as follows:
a wafer uniformity optimization method for an ICP (inductively coupled plasma) chamber is characterized in that a coupling window is arranged at the top of the ICP chamber, an inductive coupling coil is placed on the upper portion of the coupling window and comprises an outer coil and an inner coil, the outer coil and the inner coil are connected with a source radio frequency matcher through a power distribution box, and a source radio frequency power supply provides energy;
the optimization method comprises the following steps:
s1, continuously monitoring accumulated radio frequency time, and judging the consumption of a focusing ring through the accumulated radio frequency time; when the accumulated radio frequency time exceeds a preset radio frequency time threshold, the step S2 is entered;
and S2, aiming at different etching process parameters, changing the power of an outer coil and an inner coil of the inductive coupling coil by adjusting the power distribution of source radio frequency, so that different plasma density distributions are obtained in the edge area and the central area of the wafer, and the change of a plasma sheath layer in the edge area of the wafer caused by the consumption of the focusing ring is compensated.
Further, in step S1, the calculation process of the radio frequency time threshold includes the following steps:
s11, constructing a mathematical model between the accumulated radio frequency time and the consumption of the focusing ring:
FR＝RFH×k 1 +a；
wherein FR is the consumption of the focus ring; RFH is the accumulated radio frequency time; k is a radical of 1 And a is a parameter factor, and is obtained by fitting according to the collected historical production data;
s12, carrying out numerical value and normalization processing on the wafer uniformity expression to obtain a wafer uniformity value, and constructing a mathematical model between the wafer uniformity value and the consumption of the focusing ring;
NU＝FR×k 2 +b；
wherein NU is a wafer uniformity value; k is a radical of 2 B is a parameter factor, and is obtained by fitting according to the collected historical production data;
s13, integrating two mathematical models to obtain:
RFH＝[(NU-b)/k 2 -a]/k 1 ；
s14, according to the limit value NU of the wafer uniformity * Calculating to obtain a radio frequency time threshold RFH * 。
Further, in step S2, for different etching process parameters, the power distribution of the source rf is adjusted to change the power of the outer coil and the power of the inner coil of the inductive coupling coil, so that the edge region and the central region of the wafer obtain different plasma density distributions, and the process of compensating for the change of the plasma sheath in the edge region of the wafer caused by the consumption of the focus ring includes the following steps:
s21, setting power distribution setting values of source radio frequency to be X and Y, wherein X, Y are positive integers, X represents a capacitance value of an inner coil, Y represents a capacitance value of an outer coil, and the sum of X and Y is a certain value;
s22, constructing a mathematical model between the accumulated radio frequency time and the wafer uniformity:
NU 1 ＝(RFH×k 1 +a)×k 2 +b
in the formula, NU 1 Is the uniformity of the wafer under the same power allocation setting value, and RFH is the accumulated radio frequency time; k is a radical of 1 、k 2 A and b are parameter factors and are obtained by fitting according to the collected historical production data;
s23, constructing a mathematical model between the power distribution set value of the source radio frequency and the wafer uniformity:
NU 2 ＝X 2 ×c-X×d+e
in the formula, NU 2 Is the uniform value of the wafer within a close radio frequency time; x is the source radio frequency power allocation setting; c. d and e are parameter factors and are obtained by fitting according to the collected historical production data;
s24, calculating to obtain NU according to a preset period delta RFH 1 Variation amount of (a) NU 1 ：
ΔNU 1 ＝(ΔRFH×k 1 +a)×k 2 +b
Make NU in the same period 2 Has a variation of Δ NU 2 Construction of Δ NU 1 And delta NU 2 Mathematical model in between:
ΔNU 2 -(ΔNU 1 ×k 3 +f)＝0
the transformation gives:
ΔNU 2 ＝ΔNU 1 ×k 3 +f
in the formula, k 3 F is a parameter factor and is obtained by fitting according to the collected historical production data;
s25, convertingObtained DELTA NU 2 Substituting the power distribution setting value of the source radio frequency into a mathematical model between the wafer uniformity to obtain:
Figure BDA0003748006350000041
in the formula (I), the compound is shown in the specification,
Figure BDA0003748006350000042
is an expression value of wafer uniformity before compensation;
two solutions are calculated: x 1 And X 2 Rounding it to obtain: [ X ] 1 ]、[X 2 ](ii) a The system automatically selects and uses X for different etching processes 1 ]Or [ X ] 2 ]。
Further, the constant value is 180.
Further, the optimization method comprises the following steps:
and monitoring the uniformity of the wafer regularly, drawing a curve graph of the uniformity along with the change of time, and evaluating the optimization effect.
The invention also provides an ICP cavity, which comprises a vacuum reaction cavity, an electrostatic adsorption chuck, a protection ring, a focusing ring, a coupling window, an inductive coupling coil, a power distribution box, a source radio frequency matcher, a source radio frequency power supply and a processor;
the electrostatic adsorption chuck is placed on a middle base of the vacuum reaction chamber, the protection ring is arranged on the side edge of the electrostatic adsorption chuck, and the focusing ring is placed on the edge of the electrostatic adsorption chuck;
the top of the vacuum reaction chamber is provided with a coupling window, the upper part of the coupling window is provided with an inductive coupling coil, the inductive coupling coil is divided into an outer coil and an inner coil, the outer coil and the inner coil are both connected with a source radio frequency matcher through a power distribution box, and a source radio frequency power supply provides energy;
the processor continuously monitors the accumulated radio frequency time and judges the consumption of the focusing ring according to the accumulated radio frequency time; when the accumulated radio frequency time exceeds a preset radio frequency time threshold, the processor changes the power of the outer coil and the power of the inner coil of the inductive coupling coil by adjusting the power distribution of source radio frequency according to different etching process parameters, so that different plasma density distributions are obtained in the edge area and the central area of the wafer, and the change of the plasma sheath layer in the edge area of the wafer caused by the consumption of the focusing ring is compensated.
Further, the calculation process of the radio frequency time threshold value comprises the following steps:
s11, constructing a mathematical model between the accumulated radio frequency time and the consumption of the focusing ring:
FR＝RFH×k 1 +a；
wherein FR is the consumption of the focus ring; RFH is the accumulated radio frequency time; k is a radical of 1 And a is a parameter factor, and is obtained by fitting according to the collected historical production data;
s12, carrying out numerical value and normalization processing on the wafer uniformity expression to obtain a wafer uniformity value, and constructing a mathematical model between the wafer uniformity value and the consumption of the focusing ring;
NU＝FR×k 2 +b；
wherein NU is a wafer uniformity value; k is a radical of 2 B is a parameter factor, and is obtained by fitting according to the collected historical production data;
s13, integrating two mathematical models to obtain:
RFH＝[(NU-b)/k 2 -a]/k 1 ；
s14, according to the limit value NU of the wafer uniformity * Calculating to obtain a radio frequency time threshold RFH * 。
Further, aiming at different etching process parameters, the power distribution of source radio frequency is adjusted, the power of an outer coil and an inner coil of the inductive coupling coil is changed, so that different plasma density distributions are obtained in the edge area and the central area of the wafer, and the process of compensating the change of the plasma sheath layer in the edge area of the wafer caused by the consumption of the focusing ring comprises the following steps:
s21, setting power distribution setting values of source radio frequency to be X and Y, wherein X, Y are positive integers, X represents a capacitance value of an inner coil, Y represents a capacitance value of an outer coil, and the sum of X and Y is a certain value;
s22, constructing a mathematical model between the accumulated radio frequency time and the wafer uniformity:
NU 1 ＝(RFH×k 1 +a)×k 2 +b
in the formula, NU 1 Is the uniformity of the wafer under the same power allocation setting value, and RFH is the accumulated radio frequency time; k is a radical of 1 、k 2 A and b are parameter factors, and are obtained by fitting according to the collected historical production data;
s23, constructing a mathematical model between the power distribution set value of the source radio frequency and the wafer uniformity:
NU 2 ＝X 2 ×c-X×d+e
in the formula, NU 2 Is the uniform value of the wafer within a close radio frequency time; x is the source radio frequency power allocation setting; c. d and e are parameter factors and are obtained by fitting according to the collected historical production data;
s24, calculating to obtain NU according to a preset period delta RFH 1 Variation amount of (a) NU 1 ：
ΔNU 1 ＝(ΔRFH×k 1 +a)×k 2 +b
Make NU in the same period 2 Has a variation of Δ NU 2 Construction of Δ NU 1 And delta NU 2 Mathematical model in between:
ΔNU 2 -(ΔNU 1 ×k 3 +f)＝0
the transformation gives:
ΔNU 2 ＝ΔNU 1 ×k 3 +f
in the formula, k 3 F is a parameter factor and is obtained by fitting according to the collected historical production data;
s25, converting the obtained delta NU 2 Substituting the power distribution setting value of the source radio frequency into a mathematical model between the wafer uniformity to obtain:
Figure BDA0003748006350000051
in the formula (I), the compound is shown in the specification,
Figure BDA0003748006350000061
is an expression value of wafer uniformity before compensation;
two solutions are calculated: x 1 And X 2 And rounding to obtain: [ X ] 1 ]、[X 2 ](ii) a The system automatically selects and uses X for different etching processes 1 ]Or [ X ] 2 ].
Further, the constant value is 180.
The present invention also refers to an ICP apparatus comprising an ICP chamber as described above.
Has the advantages that:
according to the wafer uniformity optimization method for the ICP chamber, when the RFH is found to exceed the preset threshold, the I/O power distribution set by the process menu is automatically adjusted according to the existing RFH time length, the plasma density of the center and the edge of the wafer is changed, the distribution and the form change of the plasma sheath (plasma sheath) of the edge area of the wafer caused by the consumption of the focusing ring are compensated, and finally the uniformity is maintained to be stable.
Drawings
FIG. 1 is a schematic diagram of a prior art ICP apparatus;
FIG. 2 is a schematic diagram illustrating an edge tilting phenomenon;
FIG. 3 is a simplified structural diagram of an inductive coupling coil in accordance with an embodiment of the present invention;
FIG. 4 is a schematic diagram of the Process I/O Tuning logic;
FIG. 5 is a graph showing the relationship between RF time and the consumption of the focus ring;
FIG. 6 is a graph showing the relationship between the consumption of the focus ring and the uniformity;
FIG. 7 is a schematic diagram of power distribution and uniformity of inner and outer coils;
FIG. 8 is a graph showing the comparison of uniformity before and after application of the Process I/O Tuning.
Detailed Description
The following examples are presented to enable one of ordinary skill in the art to more fully understand the present invention and are not intended to limit the invention in any way.
The embodiment of the invention provides a wafer uniformity optimization method for an ICP (inductively coupled plasma) chamber, wherein a coupling window is arranged at the top of the chamber of the ICP chamber, an inductive coupling coil is arranged at the upper part of the coupling window and comprises an outer coil and an inner coil, the outer coil and the inner coil are connected with a source radio frequency matcher through a power distribution box, and energy is provided by a source radio frequency power supply.
The optimization method comprises the following steps:
s1, continuously monitoring accumulated radio frequency time, and judging the consumption of a focusing ring through the accumulated radio frequency time; and when the accumulated radio frequency time exceeds a preset radio frequency time threshold, the step S2 is entered.
And S2, aiming at different etching process parameters, changing the power of an outer coil and an inner coil of the inductive coupling coil by adjusting the power distribution of source radio frequency, so that different plasma density distributions are obtained in the edge area and the central area of the wafer, and the change of a plasma sheath layer in the edge area of the wafer caused by the consumption of the focusing ring is compensated.
In the embodiment, the power distribution of the source radio frequency is adjusted, the power of the inner induction coil and the power of the outer induction coil are changed, so that the edge and the center obtain different plasma densities, the change of a plasma sheath layer in the edge area of the wafer caused by the consumption of the focusing ring is compensated, the edge tilting phenomenon is improved, and the integral uniformity is further improved. The adjustment amount of the power distribution of the source radio frequency is determined according to the radio frequency time (RFH) length of the focusing ring in the chamber, and the uniformity for a long time is maintained to be stable by dynamic adjustment and compensation.
A schematic diagram of the ICP apparatus with an inductive coupling coil of the present invention is shown in fig. 3. An electrostatic chuck 20 is placed on a middle base of a vacuum reaction chamber 10, a protection ring 30 is arranged on the side of the electrostatic chuck 20, a focusing ring 40 is placed on the edge of the electrostatic chuck 20, a coupling window 50 is arranged on the top of the chamber, an inductive coupling coil 100 is placed on the upper portion of the coupling window 50, the inductive coupling coil 100 is divided into an outer coil 110 and an inner coil 120, the inner and outer coils are connected with a source radio frequency matcher 220 through a power distribution box 230, and energy is provided by a source radio frequency power supply 210. The wafer uniformity optimization method for the ICP chamber disclosed by the invention can be integrated into a function (Process I/O Tuning), and is operated in the background through software. The logic for the operation of this function is shown in fig. 4.
The invention discloses a function (Process I/O Tuning) for improving uniformity, which judges the degree of consumption of a focus ring by continuously monitoring a radio frequency time (RFH), and the degree serves as a starting condition for enabling the function. This function starts to be enabled when RFH is found to exceed a pre-set threshold. According to the existing RFH duration, the I/O power distribution set by a process menu is automatically adjusted according to a preset algorithm, the plasma density of the center and the edge of the wafer is changed, the change of the distribution and the shape of a plasma sheath (plasma sheath) in the edge area of the wafer caused by the consumption of a focusing ring is compensated, and finally, the uniformity is maintained to be stable.
The present invention discloses a Process I/O Tuning function, the algorithm behind which is supported by a large amount of experimental data. According to the following three rules, the method can be automatically adjusted according to actual conditions, and the optimal uniformity performance is kept.
(1) The rf time is proportional to the consumption of the focus ring, and the rule is summarized as shown in fig. 5.
(2) The consumption of the focus ring is proportional to the uniformity, and the uniformity is continuously deteriorated while the focus ring is consumed, as shown in fig. 6.
(3) The power distribution and uniformity of the inner and outer inductively coupled coils are distributed in a V shape, and the power distribution and uniformity are optimized under the optimal power distribution parameters, as shown in fig. 7.
Exemplarily, in step S1, the calculation process of the radio frequency time threshold includes the following steps:
s11, constructing a mathematical model between the accumulated radio frequency time and the consumption of the focusing ring:
FR＝RFH×k 1 +a；
wherein FR is the consumption of the focus ring; RFH is the accumulated radio frequency time; k is a radical of 1 And a is a parameter factor, and is obtained by fitting according to the collected historical production data.
S12, performing numerical and normalization processing on the wafer uniformity expression to obtain a uniform value of the wafer, and constructing a mathematical model between the uniform value of the wafer and the consumption of the focus ring:
NU＝FR×k 2 +b；
wherein NU is a wafer uniformity value; k is a radical of 2 And b is a parameter factor, and is obtained by fitting according to the collected historical production data.
S13, integrating two mathematical models to obtain:
RFH＝[(NU-b)/k 2 -a]/k 1 ；
s14, according to the limit value NU of the wafer uniformity * Calculating to obtain a radio frequency time threshold RFH * 。
In step S2, for different etching process parameters, the power distribution of the source rf is adjusted to change the power of the outer coil and the power of the inner coil of the inductive coupling coil, so that the edge region and the central region of the wafer obtain different plasma density distributions, and the process of compensating for the change of the plasma sheath in the edge region of the wafer caused by the consumption of the focus ring includes the following steps:
s21, setting power distribution setting values of the source radio frequency to be X and Y, wherein X, Y are positive integers, X represents a capacitance value of the inner coil, Y represents a capacitance value of the outer coil, and the sum of X and Y is constant because the total capacitance value of the source radio frequency is unchanged. For example, this fixed value is 180, i.e., X + Y =180. At this time, the power allocation setting value of the source radio frequency can also be written as: X/(180-X).
S22, constructing a mathematical model between the accumulated radio frequency time and the wafer uniformity:
NU 1 ＝(RFH×k 1 +a)×k 2 +b
in the formula, NU 1 Is the uniformity of the wafer under the same power allocation setting value, and RFH is the accumulated radio frequency time; k is a radical of 1 、k 2 A and b are parameter factors and are obtained by fitting according to the collected historical production data;
s23, constructing a mathematical model between the power distribution set value of the source radio frequency and the wafer uniformity:
NU 2 ＝X 2 ×c-X×d+e
in the formula, NU 2 Is the uniform value of the wafer within a close radio frequency time; x is the source radio frequency power allocation setting; c. d and e are parameter factors and are obtained by fitting according to the collected historical production data;
and S24, compensating the uniformity of the wafer once according to the preset period delta RFH. The compensation process is as follows:
calculating to obtain NU 1 Variation amount of (a) NU 1 ：
ΔNU 1 ＝(ΔRFH×k 1 +a)×k 2 +b。
Make NU in the same period 2 Has a variation of Δ NU 2 To compensate for Δ NU 1 Require NU 2 Following the changes, Δ NU is constructed 1 And delta NU 2 Mathematical model in between:
ΔNU 2 -(ΔNU 1 ×k 3 +f)＝0。
the transformation gives:
ΔNU 2 ＝ΔNU 1 ×k 3 +f；
in the formula, k 3 F is a parameter factor and is obtained by fitting according to the collected historical production data;
s25, converting the obtained delta NU 2 Substituting the power distribution setting value of the source radio frequency into a mathematical model between the wafer uniformity to obtain:
Figure BDA0003748006350000081
in the formula (I), the compound is shown in the specification,
Figure BDA0003748006350000082
the performance value of the wafer uniformity before compensation is recorded by a system, and related personnel can check and correct the performance value;
two solutions are calculated: x 1 And X 2 Rounding it to obtain: [ X ] 1 ]、[X 2 ](ii) a The system automatically selects and uses X for different etching processes 1 ]Or [ X ] 2 ]The related personnel can carry out the inspectionAnd (6) checking and correcting.
The uniformity was tested to improve by 0.5% in one application example, as shown in FIG. 8.
The optimization method used in this embodiment is continuously optimized according to the continuous expansion of the collected data. The invention can be applied to various metal or nonmetal film etching processes within the protection scope of the patent, and each process corresponds to different adjustment parameters and algorithms, and the detailed description is omitted.

Claims (10)

1. A wafer uniformity optimization method for an ICP (inductively coupled plasma) chamber is characterized in that a coupling window is arranged at the top of the ICP chamber, an inductive coupling coil is placed at the upper part of the coupling window, the inductive coupling coil comprises an outer coil and an inner coil, the outer coil and the inner coil are connected with a source radio frequency matcher through a power distribution box, and energy is provided by a source radio frequency power supply;
the optimization method comprises the following steps:
s1, continuously monitoring accumulated radio frequency time, and judging the consumption of a focusing ring through the accumulated radio frequency time; when the accumulated radio frequency time exceeds a preset radio frequency time threshold, the step S2 is entered;
and S2, aiming at different etching process parameters, changing the power of an outer coil and an inner coil of the inductive coupling coil by adjusting the power distribution of source radio frequency, so that different plasma density distributions are obtained in the edge area and the central area of the wafer, and the change of a plasma sheath layer in the edge area of the wafer caused by the consumption of the focusing ring is compensated.
2. The wafer uniformity optimization method for the ICP chamber as recited in claim 1, wherein the calculation of the RF time threshold in the step S1 comprises the following steps:
s11, constructing a mathematical model between the accumulated radio frequency time and the consumption of the focusing ring:
FR＝RFH×k 1 +a；
wherein FR is the consumption of the focus ring; RFH is cumulative emissionFrequency-time; k is a radical of 1 And a is a parameter factor, and is obtained by fitting according to the collected historical production data;
s12, carrying out numerical value and normalization processing on the wafer uniformity expression to obtain a wafer uniformity value, and constructing a mathematical model between the wafer uniformity value and the consumption of the focusing ring;
NU＝FR×k 2 +b；
wherein NU is a wafer uniformity value; k is a radical of 2 B is a parameter factor, and is obtained by fitting according to the collected historical production data;
s13, integrating two mathematical models to obtain:
RFH＝[(NU-b)/k 2 -a]/k 1 ；
s14, according to the limit value NU of the wafer uniformity * Calculating to obtain a radio frequency time threshold RFH * 。
3. The method as claimed in claim 1, wherein in the step S2, the power distribution of the source rf is adjusted to change the power of the outer coil and the inner coil of the inductive coupling coil according to different etching process parameters, so as to obtain different plasma density distributions in the edge region and the central region of the wafer, and the process of compensating the change of the plasma sheath in the edge region of the wafer caused by the consumption of the focus ring comprises the following steps:
s21, setting power distribution setting values of source radio frequency to be X and Y, wherein X, Y are positive integers, X represents a capacitance value of an inner coil, Y represents a capacitance value of an outer coil, and the sum of X and Y is a certain value;
s22, constructing a mathematical model between the accumulated radio frequency time and the wafer uniformity:
NU 1 ＝(RFH×k 1 +a)×k 2 +b
in the formula, NU 1 Is the uniformity of the wafer under the same power allocation setting value, and RFH is the accumulated radio frequency time; k is a radical of 1 、k 2 A and b are parameter factors and are obtained by fitting according to the collected historical production data;
s23, constructing a mathematical model between the power distribution set value of the source radio frequency and the wafer uniformity:
NU 2 ＝X 2 ×c-X×d+e
in the formula, NU 2 Is the uniform value of the wafer within a close radio frequency time; x is the source radio frequency power allocation setting; c. d and e are parameter factors, and are obtained by fitting according to the collected historical production data;
s24, calculating to obtain NU according to a preset period delta RFH 1 Variation amount of (a) NU 1 ：
ΔNU 1 ＝(ΔRFH×k 1 +a)×k 2 +b
Make NU in the same period 2 Has a variation of Δ NU 2 Construction of Δ NU 1 And delta NU 2 A mathematical model therebetween:
ΔNU 2 -(ΔNU 1 ×k 3 +f)＝0
the transformation gives:
ΔNU 2 ＝ΔNU 1 ×k 3 +f
in the formula, k 3 F is a parameter factor and is obtained by fitting according to the collected historical production data;
s25, converting the obtained delta NU 2 Substituting the power distribution setting value of the source radio frequency into a mathematical model between the wafer uniformity to obtain:
Figure FDA0003748006340000021
in the formula (I), the compound is shown in the specification,
Figure FDA0003748006340000022
is an expression value of wafer uniformity before compensation;
two solutions are calculated: x 1 And X 2 Rounding it to obtain: [ X ] 1 ]、[X 2 ](ii) a The system automatically selects and uses X for different etching processes 1 ]Or [ X ] 2 ]。
4. The wafer uniformity optimization method for an ICP chamber of claim 3, wherein the constant value is 180.
5. The wafer uniformity optimization method for an ICP chamber according to claim 1, wherein the optimization method comprises the steps of:
and monitoring the uniformity of the wafer regularly, drawing a curve graph of the uniformity along with the change of time, and evaluating the optimization effect.
6. An ICP chamber is characterized by comprising a vacuum reaction chamber, an electrostatic adsorption chuck, a protection ring, a focusing ring, a coupling window, an inductive coupling coil, a power distribution box, a source radio frequency matcher, a source radio frequency power supply and a processor;
the electrostatic adsorption chuck is placed on a middle base of the vacuum reaction chamber, the protection ring is arranged on the side edge of the electrostatic adsorption chuck, and the focusing ring is placed on the edge of the electrostatic adsorption chuck;
the top of the vacuum reaction chamber is provided with a coupling window, the upper part of the coupling window is provided with an inductive coupling coil, the inductive coupling coil is divided into an outer coil and an inner coil, the outer coil and the inner coil are both connected with a source radio frequency matcher through a power distribution box, and a source radio frequency power supply provides energy;
the processor continuously monitors the accumulated radio frequency time and judges the consumption of the focusing ring according to the accumulated radio frequency time; when the accumulated radio frequency time exceeds a preset radio frequency time threshold, the processor changes the power of the outer coil and the power of the inner coil of the inductive coupling coil by adjusting the power distribution of source radio frequency according to different etching process parameters, so that different plasma density distributions are obtained in the edge area and the central area of the wafer, and the change of the plasma sheath layer in the edge area of the wafer caused by the consumption of the focusing ring is compensated.
7. An ICP chamber as in claim 6, wherein the RF time threshold calculation process comprises the steps of:
s11, constructing a mathematical model between the accumulated radio frequency time and the consumption of the focusing ring:
FR＝RFH×k 1 +a；
wherein FR is the consumption of the focus ring; RFH is the accumulated radio frequency time; k is a radical of 1 And a is a parameter factor, and is obtained by fitting according to the collected historical production data;
s12, carrying out numerical value and normalization processing on the wafer uniformity expression to obtain a wafer uniformity value, and constructing a mathematical model between the wafer uniformity value and the consumption of the focusing ring;
NU＝FR×k 2 +b；
wherein NU is a wafer uniformity value; k is a radical of 2 B is a parameter factor, and is obtained by fitting according to the collected historical production data;
s13, two mathematical models are integrated to obtain:
RFH＝[(NU-b)/k 2 -a]/k 1 ；
s14, according to the limit value NU of the wafer uniformity * Calculating to obtain a radio frequency time threshold RFH * 。
8. The ICP chamber of claim 6, wherein the power distribution of the source radio frequency is adjusted for different etching process parameters, the power of the outer coil and the power of the inner coil of the inductive coupling coil are changed, different plasma density distributions are obtained in the edge area and the central area of the wafer, and the process of compensating the change of the plasma sheath layer in the edge area of the wafer caused by the consumption of the focusing ring comprises the following steps:
s21, setting power distribution setting values of source radio frequency to be X and Y, wherein X, Y are positive integers, X represents a capacitance value of an inner coil, Y represents a capacitance value of an outer coil, and the sum of X and Y is a certain value;
s22, constructing a mathematical model between the accumulated radio frequency time and the wafer uniformity:
NU 1 ＝(RFH×k 1 +a)×k 2 +b
in the formula, NU 1 Is the uniformity of the wafer under the same power allocation setting value, and RFH is the accumulated radio frequency time; k is a radical of 1 、k 2 A and b are parameter factors and are obtained by fitting according to the collected historical production data;
s23, constructing a mathematical model between the power distribution set value of the source radio frequency and the wafer uniformity:
NU 2 ＝X 2 ×c-X×d+e
in the formula, NU 2 Is the uniform value of the wafer within a close radio frequency time; x is the source radio frequency power allocation setting; c. d and e are parameter factors and are obtained by fitting according to the collected historical production data;
s24, calculating to obtain NU according to a preset period delta RFH 1 Variation amount of (a) NU 1 ：
ΔNU 1 ＝(ΔRFH×k 1 +a)×k 2 +b
Make NU in the same period 2 Has a variation of Δ NU 2 Construction of Δ NU 1 And delta NU 2 Mathematical model in between:
ΔNU 2 -(ΔNU 1 ×k 3 +f)＝0
the transformation gives:
ΔNU 2 ＝ΔNU 1 ×k 3 +f
in the formula, k 3 F is a parameter factor and is obtained by fitting according to the collected historical production data;
s25, converting the obtained delta NU 2 Substituting the power distribution setting value of the source radio frequency into a mathematical model between the wafer uniformity to obtain:
Figure FDA0003748006340000041
in the formula (I), the compound is shown in the specification,
Figure FDA0003748006340000042
is an expression value of wafer uniformity before compensation;
two solutions are calculated: x 1 And X 2 Rounding it to obtain: [ X ] 1 ]、[X 2 ](ii) a Aiming at different etching processes, the system automatically selects and usesX 1 ]Or [ X ] 2 ]。
9. An ICP chamber as claimed in claim 8, wherein the fixed value is 180.
10. An ICP apparatus, comprising the ICP chamber of claim 6.
CN202210835710.0A 2022-07-15 2022-07-15 Wafer uniformity optimization method for ICP (inductively coupled plasma) chamber Pending CN115332065A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117410215A (en) * 2023-12-15 2024-01-16 合肥晶合集成电路股份有限公司 Method for determining machine parameters, control method, control system and device thereof

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117410215A (en) * 2023-12-15 2024-01-16 合肥晶合集成电路股份有限公司 Method for determining machine parameters, control method, control system and device thereof
CN117410215B (en) * 2023-12-15 2024-04-09 合肥晶合集成电路股份有限公司 Method for determining machine parameters, control method, control system and device thereof

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