CN101494160B - Technology end-point control method and device - Google Patents
Technology end-point control method and device Download PDFInfo
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- CN101494160B CN101494160B CN2008100565995A CN200810056599A CN101494160B CN 101494160 B CN101494160 B CN 101494160B CN 2008100565995 A CN2008100565995 A CN 2008100565995A CN 200810056599 A CN200810056599 A CN 200810056599A CN 101494160 B CN101494160 B CN 101494160B
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- 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
- H01L22/26—Acting in response to an ongoing measurement without interruption of processing, e.g. endpoint detection, in-situ thickness measurement
Abstract
The embodiment of the invention discloses a control method for the technology end-point. The wave crest or flat in the spectrum signals is searched and the searched wave crest or flat is taken as the inflection point; the wave crest refers to a spectrum signal with the intensity of more than one continuous spectrum signals on both left and right sides of the spectrum signal being lower than the intensity thereof; the flat refers to a spectrum signal with the intensity of more than one continuous spectrum signal on the left side of the spectrum signal being lower than the intensity thereof and the intensity of more than one continuous spectrum signals on the right side of the spectrum signal only fluctuating by a small margin which meets the demand; the technology end-point time is determined in accordance with the searched reflection point. The embodiment of the invention discloses a control device for technology end-point. The Low Open Area can be correctly and conveniently determined by using the method and the device provided by the embodiment of the invention.
Description
Technical field
The present invention relates to the process endpoint control technology, end-point control method and device in particularly a kind of less exposed area (Low OpenArea) technology.
Background technology
In the semiconductor technology processing procedure, need on silicon chip (Wafer), process the figure of superfine micro-dimension.And the generation type of these figures adopts photoetching technique the circuitous pattern on the mask plate to be transferred on the photoresist that is covered in silicon chip surface exactly, adopts lithographic technique again, does not have the zone of photoresist (circuitous pattern) protection to stay permanent figure on silicon chip.
In etching process, for etching depth strict requirement is arranged, if etching depth is not enough or excessive, all can cause to have a strong impact on to process results.And etching depth is relevant with the time that processing step carries out, so will control etching depth, will control the terminal time of each step, promptly will carry out the terminal point control (EPD, End Point Detection) of technology.
Terminal point control is a key technology during semiconductor technology is produced.In recent years, along with the fast development of semiconductor design and manufacturing technology, it is important further that this technology also becomes.The basic principle of terminal point control is: the element in etching material and the etching gas can produce emission spectrum in etching process, different elements has the emission spectrum of different wave length (frequency), in etching process, the emission spectrum of each element correspondence changes with the amount of reactant that comprises this element or product.The amount of reactant or product is many more, and the intensity of the emission spectrum of element is strong more, otherwise the intensity of the emission spectrum of element is just weak more.When technology is carried out the step switching, when promptly stopping a step and beginning a new step, because the difference of employed etching gas and etching material, obvious variation can take place such as the emission spectrum of silicon, carbon, fluorine, chlorine etc. in some essential elements in the etching process.The terminal point Control Software can be found out the process endpoint time exactly by the one or more spectral signal in these elements is carried out mathematical analysis.
The existing method that is used for terminal point control mainly comprises: threshold value (Threshold) method and difference/slope (Slope) method.
The basic thought of Threshold method is: an activation threshold value (Trigger Percent) and satisfied time (Satisfaction Time) Δ t are set, if the variable quantity of a certain moment t1 spectral signal is less than the TriggerPercent that is provided with, and the variable quantity of the spectral signal of all time point correspondences determines then that all less than Trigger Percent the terminal time of technology is t1+ Δ t in the Satisfaction Time after the t1.Fig. 1 is the realization schematic diagram of existing Threshold method, and concrete steps are as follows:
Step 1: the technology spectral signal is carried out filtering and time-delay (Delay) processing, for this spectral signal is provided with the standard time (Normalize Time), the mean intensity E of spectral signal that calculating is positioned at each time point correspondence of Normalize Time promptly carries out the phase adduction to the spectral signal intensity of each time point correspondence and asks average.
Because it is bigger to be positioned at the spectral signal fluctuation at time point initial stage, so in actual applications, can carry out Delay to spectral signal earlier and handle, carry out subsequent treatment again after waiting signal steadily.The concrete value of NormalizeTime in this step can be provided with according to actual needs or rule of thumb.
Step 2: the time point after Normalize Time, first signaling point S of Trigger Percent is satisfied in search.
Trigger Percent in this step is for setting in advance, and its concrete value can be provided with according to actual needs or rule of thumb.First signaling point S of Trigger Percent is satisfied in search, promptly refer to first time point after Normalize Time, the difference of judging spectral signal intensity on which time point and E is less than the Trigger Percent that sets in advance, if determine that then this spectral signal is required signaling point S.
Certainly, spectral signal intensity in this step on which time point of judgement and the difference of E are less than the Trigger Percent that sets in advance, be whether a kind of available spectral signal of judging satisfies the mode of Trigger Percent, in actual applications, can also adopt alternate manner, such as, the absolute difference of judging spectral signal intensity on which time point and E is less than the Trigger Percent that sets in advance; Judge that spectral signal intensity on which time point and E ask the ratio of result after the difference and E less than the TriggerPercent that sets in advance; Judge that spectral signal intensity on which time point and E ask the ratio of result after the absolute difference and E less than Trigger Percent that sets in advance etc.
Step 3: after the first signaling point S time corresponding point of determining, and then a Satisfaction Time is set, if the spectral signal in the Satisfaction Time on all time points all satisfies TriggerPercent, determine that then first signaling point S time corresponding point adds that the time point that obtains after the Satisfaction Time is the terminal time of technology.
Satisfaction Time in this step is for setting in advance, and its concrete value can be provided with according to actual needs or rule of thumb.Here the spectral signal in the Satisfaction Time that is mentioned on all time points all satisfies Trigger Percent, be meant the spectral signal intensity on all time points and the difference of E in the Satisfaction Time, or absolute difference, or the ratio of described difference or absolute difference and E is all less than the Trigger Percent that sets in advance.
If the spectral signal in the Satisfaction Time on all time points not exclusively satisfies TriggerPercent, promptly have at least a spectral signal not satisfy Trigger Percent, then put S again search time, promptly repeated execution of steps 2, repeat no more.
For general technology, as, for the Open Area of silicon chip greater than 50% technology, because the Open Area of silicon chip is bigger, in etching process, the reactant of some essential elements or the amount of product are many, and the intensity of the emission spectrum of each essential element is all bigger, so the variation of spectral signal is apparent in view, the size and the trend that can change by spectral signal at an easy rate in the terminal point control procedure are determined the process endpoint time.Wherein, but Open Area is meant the ratio of the gross area of etch areas area and silicon chip.But, complicated technology for some Low Open Area, because the amount of the reactant of some essential elements or product is all very little in the technical process, correspondingly, the signal strength signal intensity of each element emission spectrum is also all smaller, and signal changes also not obvious, so, if still adopt the Threshold method to carry out terminal point control, can be difficult to accurately determine terminal time.
Another end-point control method also is provided in the prior art, and the Slope method is implemented as follows:
Step 1: the technology spectral signal is carried out filtering and Delay processing, for this spectral signal is provided with a difference threshold value (S
C, Slope Count) and a difference time (S
T, Slope Time).
The concrete value of Slope Count and Slope Time can be provided with according to actual needs or rule of thumb.
Step 2: calculate the difference of i point spectral signal, concrete account form is:
D
S(i)＝E
S(i)-E
S(i-1)＝Slope
S(i)×ΔT。
Wherein, D
S(i) difference of expression i point spectral signal; E
S(i) expression i point spectral signal intensity; E
S(i-1) expression i-1 point, i.e. spectral signal intensity on the time point before the i point; Slope
S(i) slope of expression i point spectral signal; Δ T represents the sampling period.
In principle, when calculating the difference of spectral signal, the value of i is from the original position of time point, but in actual applications, because rule of thumb the original position of time point can not be the terminal time of technology as can be known, so the initial value of i is set to about 30 usually.
Step 3: if D
S(i)≤S
C, then i point spectral signal is called triggering signal (Trigger Signal), in the ensuing Slope Time time, if all spectral signals all satisfy D
S(k ∈ S
T)≤S
C, then the terminal time of technology equals Trigger Signal time corresponding point and adds time corresponding point after the Slope Time time; Otherwise, if having spectral signal not satisfy D in the Slope Time time
S(k ∈ S
T)≤S
C, then need search for Trigger Signal again, promptly repeated execution of steps 2, repeat no more.
The same with the Threshold method, the Slope method also only is applicable to the bigger technology of Open Area of silicon chip, for the complicated technology of some Low Open Area, adopts the Slope method to be difficult to accurately determine terminal time.
Summary of the invention
The embodiment of the invention provides a kind of technology end-point control method, can determine the terminal time in the LowOpen Area technology accurately and easily.
The embodiment of the invention provides a kind of process endpoint control device, can determine the terminal time in the LowOpen Area technology accurately and easily.
The technical scheme of the embodiment of the invention is achieved in that
A kind of technology end-point control method, this method comprises:
Crest or the level land of search in the spectral signal, with the described crest that searches out or level land as flex point;
Described crest is meant that in its left and right sides continuous more than one spectral signal intensity is all less than the spectral signal of himself intensity; Described level land is meant that in its continuous more than one spectral signal intensity in left side all less than himself intensity, and the continuous more than one spectral signal intensity in its right side is only made the spectral signal of satisfactory fuctuation within a narrow range;
According to the described flex point that searches, obtain the process endpoint time of described spectral signal, comprising:
When the described flex point that searches is crest, is close to described flex point time corresponding point one satisfied time was set afterwards;
Whether the spectral signal intensity of judging each time point correspondence in the described satisfied time is all less than the intensity of described flex point, if then described flex point time corresponding point is added after the above satisfied time the time corresponding point as the process endpoint time of described spectral signal;
When the described flex point that searches when being the level land, is set after being close to described flex point time corresponding point the satisfied time;
Judge whether the spectral signal intensity of each time point correspondence in the described satisfied time all makes satisfactory fuctuation within a narrow range, if then described flex point time corresponding point is added after the above satisfied time the time corresponding point as the process endpoint time of described spectral signal.
Before the crest or level land in the described search spectral signal, further comprise:
Described spectral signal is carried out filtering and delay process.
A kind of process endpoint control device comprises: search unit and determining unit;
Described search unit is used for searching for the crest or the level land of spectral signal, with the described crest that searches or level land as flex point; Described crest is meant that in its left and right sides continuous more than one spectral signal intensity is all less than the spectral signal of himself intensity; Described level land is meant that in its continuous more than one spectral signal intensity in left side all less than himself intensity, and the continuous more than one spectral signal intensity in its right side is only made the spectral signal of satisfactory fuctuation within a narrow range;
Described determining unit is used for the flex point that searches according to described search unit, obtains the process endpoint time of described spectral signal;
Wherein, further comprise in the described determining unit: subelement and judgment sub-unit are set;
The described subelement that is provided with is used for being provided with the satisfied time after the described flex point time corresponding point of next-door neighbour;
Described judgment sub-unit, whether the spectral signal intensity that is used to judge each time point correspondence in the described satisfied time is all less than the intensity of described flex point, if then described flex point time corresponding point is added after the above satisfied time the time corresponding point as the process endpoint time of described spectral signal; Perhaps, judge whether the spectral signal intensity of each time point correspondence in the described satisfied time all makes satisfactory fuctuation within a narrow range, if then described flex point time corresponding point is added after the above satisfied time the time corresponding point as the process endpoint time of described spectral signal.
Further comprise in this device:
Processing unit is used for described spectral signal is carried out filtering and delay process, and described spectral signal after filtering and delay process is sent to described search unit.
Further comprise in the described search unit: peak search subelement and level land search subelement;
Described peak search subelement is used for searching for the crest of spectral signal, with the described crest that searches as flex point;
Search subelement in described level land is used for searching for the level land of spectral signal, with the described level land that searches as flex point.
Compared with prior art, the described scheme of the embodiment of the invention is at the spectral signal characteristics in the Low Open Area technology, obtain flex point by crest or level land in the search spectral signal, and and then determine terminal time according to the flex point that gets access to, thereby realized determining accurately and easily the terminal time in the Low Open Area technology.
Fig. 1 is the realization schematic diagram of existing Threshold method.
Fig. 2 is two spectral signal curve synoptic diagrams commonly used in the existing Low Open Area technology.
Fig. 3 is the flow chart of technology end-point control method embodiment of the present invention.
Fig. 4 is the composition structural representation of process endpoint control device embodiment of the present invention.
Fig. 5 is two curve of spectrum schematic diagrames in a certain Low Open Area technology in the embodiment of the invention.
Fig. 6 is for carrying out carrying out the curve of spectrum schematic diagram that obtains after the signal transformation by the described scheme of the embodiment of the invention to the curve of spectrum shown in Figure 5 in the embodiment of the invention.
For making purpose of the present invention, technical scheme and advantage clearer, below with reference to the accompanying drawing embodiment that develops simultaneously, the present invention is described in further detail.
Fig. 2 is two spectral signal curve synoptic diagrams (being designated hereinafter simply as the curve of spectrum) commonly used in the existing Low Open Area technology.Wherein, top figure is the curve of spectrum of the element correspondence of OES220 (wavelength is 220nm); Following figure is the curve of spectrum of the element correspondence of OES251 (wavelength is 251nm).As can be seen from Figure 2, by near process endpoint time T=108 determined of experiment repeatedly second, article two, the curve of spectrum does not all have as having the corresponding curve of spectrum under the bigger technology of Open Area now, " normally " trend that spectral signal intensity significantly reduces appears near terminal time, but variation tendency is different and it is very not obvious to change, and this also existing just Threshold and Slope method can not accurately be determined the reason of the terminal time in the Low Open Area technology.But, two curves of spectrum shown in Figure 2 have also formed certain trend respectively near terminal time: for the curve of spectrum of OES220, near terminal time, the variation tendency of spectral signal intensity is to rise earlier afterwards to descend, and has formed a little crest before terminal time; And for the curve of spectrum of OES251, near terminal time, the variation tendency of spectral signal intensity is to rise earlier to remake fuctuation within a narrow range then, has formed smooth before terminal time.Because two curves of spectrum shown in Figure 2 are for two curves of spectrum commonly used in the existing Low Open Area technology, so spectral signal variation trends shown in Figure 2 can be extended to the variation tendency of the curve of spectrum in all LowOpen Area technologies.
By above-mentioned analysis as can be known, in actual applications, can realize that the terminal time in the Low Open Area technology is determined by crest or the level land in the search spectral signal.Based on above-mentioned thought, a kind of new technology end-point control method has been proposed in the embodiment of the invention, that is, and crest or the level land of search in the spectral signal, with the crest that searches out or level land as flex point; Wherein, crest is meant that in its left and right sides continuous more than one spectral signal intensity is all less than the spectral signal of himself intensity; The level land is meant that in its continuous more than one spectral signal intensity in left side all less than himself intensity, and the continuous more than one spectral signal intensity in its right side is only made the spectral signal of satisfactory fuctuation within a narrow range; According to the flex point that searches, determine the terminal time of spectral signal.
Below by specific embodiment, scheme of the present invention is described in further detail:
Fig. 3 is the flow chart of technology end-point control method embodiment of the present invention.As shown in Figure 3, may further comprise the steps:
Step 301: the spectral signal that gets access to is carried out Filtering Processing and Delay processing.
In this step, can adopt existing various filtering modes commonly used,, the spectral signal that gets access to be carried out filtering, to reduce the noise in the spectral signal as medium filtering, arithmetic filtering and first-order lag filtering etc.In addition,, so in actual applications, can carry out Delay to spectral signal and handle, carry out subsequent treatment again after waiting signal steadily because it is bigger to be positioned at the spectral signal fluctuation at time point initial stage.
Step 302: crest or the level land of search in the spectral signal, with the crest that searches out or level land as flex point.
Based on before introduction as can be known, the variation of spectral signal intensity generally can present two kinds of trend under the Low Open Area technology, that is, rising earlier afterwards descends, crest of formation before terminal time; And the back fuctuation within a narrow range that rises earlier, before terminal time, form smooth.That is to say that crest just is meant that the continuous a plurality of spectral signal intensity in its left and right sides are all less than the spectral signal of peak intensity; The level land is meant that in its continuous a plurality of spectral signal intensity in left side all less than level land intensity, and the continuous a plurality of spectral signal intensity in its right side are only made the spectral signal of satisfactory fuctuation within a narrow range.Wherein, which kind of fuctuation within a narrow range meets the requirements at last can set in advance, such as, the scope of fluctuating is no more than threshold value that sets in advance etc.
In this step, can carry out concrete definition pacifically to crest, when carrying out the search on crest or level land, carry out corresponding search according to do definition and get final product according to the characteristics on above-mentioned crest and level land.Such as:
Definition 1: if a certain spectral signal i satisfies simultaneously
Description of drawings
E(i)-E(i-1)≥0，E(i)-E(i-2)≥0，---，E(i)-E(i-k)≥0；
E(i)-E(i+1)≥0，E(i)-E(i+2)≥0，---，E(i)-E(i+k)≥0
Can determine that then this spectral signal i is a crest.
Perhaps, if a certain spectral signal i satisfies simultaneously
E(i)-E(i-1)≥0，E(i-1)-E(i-2)≥0，---，E(i-k+1)-E(i-k)≥0；
E(i)-E(i+1)≥0，E(i+1)-E(i+2)≥0，---，E(i+k-1)-E(i+k)≥0；
Embodiment
Can determine that then this spectral signal i is a crest.
Wherein, the intensity of E (i) expression spectral signal i; E (i-1) expression is positioned at the spectral signal intensity on the last time point of spectral signal i; Undetermined parameter k is a crest signal judgment conditional number, is one greater than 0 integer, and k is big more, and the crest that searches is accurate more, its be worth big I according to actual needs or experience be provided with, advise that it is set to a value in (8,10), promptly 8,9 or 10.Need to prove that the value of the spectral signal i pairing k in the left and right sides also can be unequal in the above-mentioned definition, but generally be set to same value as shown in this embodiment.
As can be seen, in two kinds of definition modes of above-mentioned definition 1, a kind of definition mode in back is compared with preceding a kind of definition mode, requires strictly more, not only requires the spectral signal intensity at crest two ends all to be less than the intensity at crest place; And each spectral signal intensity in crest left side must be followed strict incremental order, and each spectral signal intensity on crest right side must be followed the strict order of successively decreasing.
For the level land, can adopt following definition mode:
Definition 2: if a certain spectral signal i satisfies simultaneously
E(i)-E(i-1)≥0，E(i)-E(i-2)≥0，---，E(i)-E(i-k)≥0；
|E(i+1)-E
M|≤E
S，|E(i+2)-E
M|≤E
S，---，|E(i+k)-E
M|≤E
S；
Determine that then this spectral signal i is the level land.
Perhaps, if a certain spectral signal i satisfies simultaneously
E(i)-E(i-1)≥0，E(i-1)-E(i-2)≥0，---，E(i-k+1)-E(i-k)≥0；
|E(i+1)-E
M|≤nE
S，|E(i+2)-E
M|≤nE
S，---，|E(i+k)-E
M|≤nE
S；
Determine that then this spectral signal i is the level land.
Wherein, the intensity of E (i) expression spectral signal i; E
M, E
SRepresent respectively spectral signal intensity array E (i+1), E (i+2),---, mean value and the standard deviation of E (i+k), the i.e. square root of variance; Undetermined parameter k is a level land signal judgment conditional number, is one greater than 0 integer, and k is big more, and the level land signal that searches is accurate more, its be worth big I according to actual needs or experience be provided with, advise that it is set to a value in (8,10), promptly 8,9 or 10; N is E
SCoefficient, its concrete value also can be according to actual needs or experience set in advance.
Certainly, above-mentioned definition 1 and definition 2 only are used to illustrate, and are not limited to technical scheme of the present invention, if adopt other definition mode, as long as meet the described thought of the embodiment of the invention, can finish the described function of the embodiment of the invention, also are fine.Other possible concrete definition mode is enumerated no longer one by one.
According to above-mentioned definition mode to crest and level land, carry out the search on crest and level land in the spectral signal after handling through step 301, i.e. search is satisfied definition 1 or is defined the spectral signal of 2 described conditions.In principle, the described search procedure of this step need be by the order of each spectral signal time corresponding point, begin to search for from the original position of time point, but rule of thumb as can be known, the process endpoint time can not be positioned at the start time point place, so in actual applications, can be from point sometime, begin to search for about locating such as 30 seconds.In case after searching crest or level land, then finish search procedure.Crest that searches or level land are flex point required in the embodiment of the invention.
Step 303:, determine the terminal time of spectral signal according to the flex point that searches.
In this step, can adopt dual mode to determine the terminal time of spectral signal: mode one, determine terminal time by Satisfaction Time is set, wherein the spectral signal of each time point correspondence all needs to satisfy definition 1 or defines defined flex point right side characteristic requirement in 2 in the Satisfaction Time time.Mode two, by adopt different signal transformation modes in the flex point rear and front end, make near the spectral signal variation the terminal time have obvious characteristics and rule, such as, by different signal processing modes, make the spectral signal intensity of flex point front end make satisfactory fuctuation within a narrow range, the spectral signal intensity of flex point rear end is obvious downward trend.Then, determine the terminal time of spectral signal again according to existing Threshold or slope method.Below this dual mode is specifically introduced respectively:
Mode one:
When the flex point that searches is crest, after this flex point time corresponding point of next-door neighbour, a Satisfaction Time is set; Whether the spectral signal intensity of judging each time point correspondence in the Satisfaction Time is all less than the intensity at flex point place, if, then add Satisfaction Time, the time point that calculates is defined as the terminal time of spectral signal with flex point time corresponding point.
When searching flex point when being the level land, after next-door neighbour's flex point time corresponding point, a Satisfaction Time is set; Judge whether the spectral signal intensity of each time point correspondence in the Satisfaction Time all makes satisfactory fuctuation within a narrow range, if, then add Satisfaction Time, the time point that calculates is defined as the terminal time of spectral signal with flex point time corresponding point.
Mode two:
Propose a kind of new signal transformation mode in the embodiment of the invention, that is, handle in such a way for each spectral signal i of flex point front end:
The difference of the minimum value of all spectral signal intensity before the maximum of asking for all spectral signal intensity before the flex point and the flex point, and the difference of the minimum value of the intensity of spectral signal i and preceding all the spectral signal intensity of flex point before the conversion; The merchant of the difference of the minimum value of the maximum of the difference of the minimum value of all spectral signal intensity and preceding all the spectral signal intensity of flex point and preceding all the spectral signal intensity of flex point before the intensity of asking for spectral signal i before the conversion and the flex point; Ask the standard deviation of preceding all the spectral signal intensity of this merchant and flex point and the product of predefined Coefficient m; The mean value of asking for all spectral signal intensity before the flex point and described product with.
Each spectral signal j to the flex point rear end handles in such a way:
Ask for the difference of the minimum value of all spectral signal intensity after the maximum of all spectral signal intensity after the flex point and the flex point, and the difference of the intensity of spectral signal j before the maximum of all spectral signal intensity and the conversion after the flex point; Ask for the merchant of the difference of the minimum value of all spectral signal intensity after the maximum of all spectral signal intensity after the difference of the intensity of spectral signal j before the maximum of all spectral signal intensity after the flex point and the conversion and the flex point and the flex point; Ask the standard deviation of all spectral signal intensity after this merchant and the flex point and the product of predefined coefficient n; Ask for the poor of the mean value of all spectral signal intensity after the flex point and described product.
Shown in being implemented as follows:
With each spectral signal of flex point front end according to E
A(i)=Mean (Q)+m*Std (Q) * [(E
B(i)-Min (Q))/(Max (Q)-Min (Q))] mode carries out conversion.
Wherein, E
A(i) intensity of the spectral signal after the expression conversion; E
B(i) intensity of the spectral signal before the expression conversion; The mean value of all spectral signal intensity before Mena (Q) the expression flex point; The standard deviation of all spectral signal intensity before Std (Q) the expression flex point; The minimum value of all spectral signal intensity before Min (Q) the expression flex point; The maximum of all spectral signal intensity before Max (Q) the expression flex point.
With each spectral signal of flex point rear end according to E
A(j)=Mean (H)-n*Std (H) * [(Max (H)-E
B(j))/(Max (H)-Min (H))] mode is carried out conversion.
Wherein, E
A(j) intensity of the spectral signal after the expression conversion; E
B(j) intensity of the spectral signal before the expression conversion; The mean value of all spectral signal intensity after Mena (H) the expression flex point; The standard deviation of all spectral signal intensity after Std (H) the expression flex point; The minimum value of all spectral signal intensity after Min (H) the expression flex point; The maximum of all spectral signal intensity after Max (H) the expression flex point.
M, n are respectively the coefficient of Std (Q) and Std (H), and concrete value is for preestablishing according to actual needs or rule of thumb.
After the spectral signal of flex point rear and front end handled respectively in the manner described above, can make near the spectral signal variation the terminal time have obvious characteristics and rule, like this, follow-up according to existing Threshold or slope method, can determine the terminal time of spectral signal.Such as, can adopt the Threshold method, after the flex point that in step 302, searches a Satisfaction Time is set, and a Trigger Percent is set; If the difference of the spectral signal intensity of all the time point correspondences in the Satisfaction Time and the intensity at flex point place, then adds flex point place time corresponding point that the time corresponding point is as the terminal time of determined spectral signal behind the Satisfaction Time all less than set Trigger Percent.Slope method and Threshold method are similar, repeat no more.
Certainly, except that mode two, can also adopt other signal transformation mode, spectral signal to the flex point rear and front end is handled, so that changing, near the spectral signal the terminal time has obvious characteristics and rule, such as, power function variation, exponential transform, logarithmic transformation and other known mapping mode etc.
The concrete value of Satisfaction Time in aforesaid way one and the mode two can be provided with according to actual needs.Generally, adopt flex point that the described scheme of the embodiment of the invention determines and terminal time to be determined from very near.Terminal time to be determined is usually located on flex point time corresponding point about one or two second the time point afterwards.
Based on said method, Fig. 4 is the composition structural representation of process endpoint control device embodiment of the present invention.As shown in Figure 4, this device comprises: search unit 401 and determining unit 402;
Search unit 401 is used for searching for the crest or the level land of spectral signal, with the crest that searches out or level land as flex point; Wherein, crest is meant that in its left and right sides continuous more than one spectral signal intensity is all less than the spectral signal of himself intensity; The level land is meant that in its continuous more than one spectral signal intensity in left side all less than himself intensity, and the continuous more than one spectral signal intensity in its right side is only made the spectral signal of satisfactory fuctuation within a narrow range;
Determining unit 402 is used for the flex point that searches according to search unit 401, determines the terminal time of spectral signal.
In addition, also can further comprise in the device: processing unit 403 is used for spectral signal is carried out filtering and Delay processing, and will sends to search unit 401 through the spectral signal after filtering and the Delay processing.
Further comprise in the above-mentioned search unit 401: peak search subelement 4011 and level land search subelement 4012;
Peak search subelement 4011 is used for searching for the crest of spectral signal, with the crest that searches as flex point; Specific implementation can be: judge successively in chronological order whether spectral signal i satisfies simultaneously
E(i)-E(i-1)≥0，E(i)-E(i-2)≥0，---，E(i)-E(i-k)≥0；
E(i)-E(i+1)≥0，E(i)-E(i+2)≥0，---，E(i)-E(i+k)≥0；
If determine that then spectral signal i is a crest;
Perhaps, judge successively in chronological order whether spectral signal i satisfies simultaneously
E(i)-E(i-1)≥0，E(i-1)-E(i-2)≥0，---，E(i-k+1)-E(i-k)≥0；
E(i)-E(i+1)≥0，E(i+1)-E(i+2)≥0，---，E(i+k-1)-E(i+k)≥0；
If determine that then this spectral signal i is a crest; Wherein, the intensity of E (i) expression spectral signal i; E (i-1) expression is positioned at the spectral signal intensity on the last time point of spectral signal i; K is the integer greater than 0, and value is for preestablishing.
Search subelement 4012 in level land is used for searching for the level land of spectral signal, with the level land that searches as flex point; Specific implementation can be: judge successively in chronological order whether spectral signal i satisfies simultaneously
E(i)-E(i-1)≥0，E(i)-E(i-2)≥0，---，E(i)-E(i-k)≥0；
|E(i+1)-E
M|≤E
S，|E(i+2)-E
M|≤E
S，---，|E(i+k)-E
M|≤E
S；
If determine that then this spectral signal i is the level land;
Perhaps, judge successively in chronological order whether spectral signal i satisfies simultaneously
E(i)-E(i-1)≥0，E(i-1)-E(i-2)≥0，---，E(i-k+1)-E(i-k)≥0；
|E(i+1)-E
M|≤nE
S，|E(i+2)-E
M|≤nE
S，---，|E(i+k)-E
M|≤nE
S；
If determine that then this spectral signal i is the level land;
Wherein, the intensity of E (i) expression spectral signal i; E (i-1) expression is positioned at the spectral signal intensity on the last time point of spectral signal i; E
M, E
SRepresent respectively spectral signal intensity array E (i+1), E (i+2),---, mean value and the standard deviation of E (i+k); K is the integer greater than 0, and value is for preestablishing; N is E
SCoefficient, value is for preestablishing.
Further comprise in the above-mentioned determining unit 402: subelement 4021 and judgment sub-unit 4022 are set;
Subelement 4021 is set, is used for after the described flex point time corresponding point of next-door neighbour, a Satisfaction Time being set;
Judgment sub-unit 4022, whether the spectral signal intensity that is used to judge each time point correspondence in the Satisfaction Time is all less than the intensity of flex point, if then flex point time corresponding point is added that time corresponding point behind the Satisfaction Time is defined as the terminal time of spectral signal; Perhaps, judge whether the spectral signal intensity of each time point correspondence in the Satisfaction Time all makes satisfactory fuctuation within a narrow range, if then flex point time corresponding point is added that time corresponding point behind the Satisfaction Time is defined as the terminal time of spectral signal.
Perhaps, further comprise in the above-mentioned determining unit 402: signal transformation subelement 4023 and definite subelement 4024;
Signal transformation subelement 4023, be used to adopt different signal transformation modes, respectively the spectral signal of flex point rear and front end is handled, made the spectral signal intensity of flex point front end make satisfactory fuctuation within a narrow range, the spectral signal intensity of flex point rear end is obvious downward trend;
Determine subelement 4024, be used for determining the terminal time of spectral signal according to Threshold or slope method.
Wherein, signal transformation subelement 4023 specifically is used for, to each spectral signal of flex point front end according to E
A(i)=Mean (Q)+m*Std (Q) * [(E
B(i)-Min (Q))/(Max (Q)-Min (Q))] mode handles; E
A(i) intensity of spectral signal after the expression conversion; E
B(i) intensity of spectral signal before the expression conversion; The mean value of all spectral signal intensity before Mena (Q) the expression flex point; The standard deviation of all spectral signal intensity before Std (Q) the expression flex point; The minimum value of all spectral signal intensity before Min (Q) the expression flex point; The maximum of all spectral signal intensity before Max (Q) the expression flex point;
To each spectral signal of flex point rear end according to E
A(j)=Mean (H)-n*Std (H) * [(Max (H)-E
B(j))/(Max (H)-Min (H))] mode is handled; E
A(j) intensity of spectral signal after the expression conversion; E
B(j) intensity of spectral signal before the expression conversion; The mean value of all spectral signal intensity after Mena (H) the expression flex point; The standard deviation of all spectral signal intensity after Std (H) the expression flex point; The minimum value of all spectral signal intensity after Min (H) the expression flex point; The maximum of all spectral signal intensity after Max (H) the expression flex point; The coefficient of m, n difference Std (Q) and Std (H), value is for preestablishing.
As seen, compared with prior art, the maximum characteristics of the described scheme of the embodiment of the invention are exactly to have introduced the thought of crest and level land two flex points, and a kind of novel signal transformation method proposed, make near the spectral signal variation the terminal time have obvious characteristics and rule, thereby determine terminal time according to described flex point better.Accuracy and reliability when determining terminal time in order to show the described scheme of the embodiment of the invention better in Low Open Area technology are further described below by concrete simulation example:
Fig. 5 is two curve of spectrum schematic diagrames in a certain Low Open Area technology in the embodiment of the invention.As shown in Figure 5, last figure wherein is the curve of spectrum of OES220; Figure below is the curve of spectrum of OES251.Because actual OES220 and OES251 curve of spectrum data volume are excessive, so only shown near the part curve of spectrum the terminal time among two width of cloth figure shown in Figure 5 respectively.The process endpoint time of two curve of spectrum correspondences is greatly about T=108 about second.This value is for determining or a known in advance exact value by repeatedly testing.
According to the inventive method shown in Figure 3 spectral signal in two curves of spectrum shown in Figure 5 is handled, supposed that the Delay time is set to 30 seconds, parameter k is set to 8.So, the flex point that can obtain two curves of spectrum is respectively T=107.2 second and T=106.6 second.Afterwards, to the spectral signal of flex point rear and front end, handle according to the described signal transformation method of the embodiment of the invention, wherein parameter n and m are set to 3 and 9 respectively, obtain two curve of spectrum schematic diagrames after the conversion shown in Figure 6.As can be seen from Figure 6, after treatment, the spectral signal variation trends of terminal time rear and front end is obvious.Follow-uply can determine terminal time, repeat no more according to the spectral signal strength information after the conversion shown in Figure 6.
In a word, adopt the technical scheme of the embodiment of the invention, can determine the terminal time in the Low Open Area technology accurately and easily.
In sum, more than be preferred embodiment of the present invention only, be not to be used to limit protection scope of the present invention.Within the spirit and principles in the present invention all, any modification of being done, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (5)
1. a technology end-point control method is characterized in that, this method comprises:
Crest or the level land of search in the spectral signal, with the described crest that searches out or level land as flex point;
Described crest is meant that in its left and right sides continuous more than one spectral signal intensity is all less than the spectral signal of himself intensity; Described level land is meant that in its continuous more than one spectral signal intensity in left side all less than himself intensity, and the continuous more than one spectral signal intensity in its right side is only made the spectral signal of satisfactory fuctuation within a narrow range;
According to the described flex point that searches, obtain the process endpoint time of described spectral signal, comprising:
When the described flex point that searches is crest, is close to described flex point time corresponding point one satisfied time was set afterwards;
Whether the spectral signal intensity of judging each time point correspondence in the described satisfied time is all less than the intensity of described flex point, if then described flex point time corresponding point is added after the above satisfied time the time corresponding point as the process endpoint time of described spectral signal;
When the described flex point that searches when being the level land, is set after being close to described flex point time corresponding point the satisfied time;
Judge whether the spectral signal intensity of each time point correspondence in the described satisfied time all makes satisfactory fuctuation within a narrow range, if then described flex point time corresponding point is added after the above satisfied time the time corresponding point as the process endpoint time of described spectral signal.
2. method according to claim 1 is characterized in that, before the crest or level land in the described search spectral signal, further comprises:
Described spectral signal is carried out filtering and delay process.
3. a process endpoint control device is characterized in that, this device comprises: search unit and determining unit;
Described search unit is used for searching for the crest or the level land of spectral signal, with the described crest that searches or level land as flex point; Described crest is meant that in its left and right sides continuous more than one spectral signal intensity is all less than the spectral signal of himself intensity; Described level land is meant that in its continuous more than one spectral signal intensity in left side all less than himself intensity, and the continuous more than one spectral signal intensity in its right side is only made the spectral signal of satisfactory fuctuation within a narrow range;
Described determining unit is used for the flex point that searches according to described search unit, obtains the process endpoint time of described spectral signal;
Wherein, further comprise in the described determining unit: subelement and judgment sub-unit are set;
The described subelement that is provided with is used for being provided with the satisfied time after the described flex point time corresponding point of next-door neighbour;
Described judgment sub-unit, whether the spectral signal intensity that is used to judge each time point correspondence in the described satisfied time is all less than the intensity of described flex point, if then described flex point time corresponding point is added after the above satisfied time the time corresponding point as the process endpoint time of described spectral signal; Perhaps, judge whether the spectral signal intensity of each time point correspondence in the described satisfied time all makes satisfactory fuctuation within a narrow range, if then described flex point time corresponding point is added after the above satisfied time the time corresponding point as the process endpoint time of described spectral signal.
4. device according to claim 3 is characterized in that, further comprises in this device:
Processing unit is used for described spectral signal is carried out filtering and delay process, and described spectral signal after filtering and delay process is sent to described search unit.
5. device according to claim 3 is characterized in that, further comprises in the described search unit: peak search subelement and level land search subelement;
Described peak search subelement is used for searching for the crest of spectral signal, with the described crest that searches as flex point;
Search subelement in described level land is used for searching for the level land of spectral signal, with the described level land that searches as flex point.
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| CN2008100565995A CN101494160B (en) | 2008-01-22 | 2008-01-22 | Technology end-point control method and device |
| PCT/CN2008/073591 WO2009094884A1 (en) | 2008-01-22 | 2008-12-19 | Method and device for detecting endpoint in process |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6190927B1 (en) * | 1995-06-30 | 2001-02-20 | Lam Research Corporation | Method and apparatus for detecting optimal endpoints in plasma etch processes |
| CN1619788A (en) * | 2003-06-18 | 2005-05-25 | 应用材料有限公司 | Method and system for monitoring etch process |
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| JPS5925227A (en) * | 1982-08-02 | 1984-02-09 | Hitachi Ltd | Device for plasma etching |
| JPS6293943A (en) * | 1985-10-21 | 1987-04-30 | Hitachi Ltd | Method and device for end point detection |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6190927B1 (en) * | 1995-06-30 | 2001-02-20 | Lam Research Corporation | Method and apparatus for detecting optimal endpoints in plasma etch processes |
| CN1619788A (en) * | 2003-06-18 | 2005-05-25 | 应用材料有限公司 | Method and system for monitoring etch process |
Non-Patent Citations (2)
| Title |
|---|
| JP昭59-25227A 1984.02.09 |
| JP昭62-93943A 1987.04.30 |
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