CN101989534B - Particle automatic control method and system thereof - Google Patents

Abstract

The invention relates to a particle automatic control method and a system thereof. The particle automatic control method includes: characteristic value of particle on wafer surface or in technological environment is acquired; allowable upper limit of number of particles is set; signal value is calculated, and the signal value is related to number of particles and the allowable upper limit of the number of particles; particle control condition is analyzed according to the signal value, and the number of particles is judged to be more than the limit if two of any three continuous signal values are exceptional. 'Three-point method' of the invention can directly adopt SPC software to analyze, so as to realize automatic control of particle, and no additional software is required, so that resource can be shared.

Description

Particle autocontrol method and system

Technical field

The present invention relates to field of quality control, particularly a kind of particle autocontrol method and system.

Background technology

Along with the continuous development of semiconductor industry, semiconductor fabrication process has got into nanometer era, does littler and littler to adapt to each item electronic product, the trend that function is done stronger and stronger.Do stronger and stronger and be accompanied by chip functions, the trend that element is done littler and littler and come is increasingly high to the specification requirement of various different links in the technology.Because element is more and more littler, and internal wiring is done more complicated, makes in the technology the slight change of parameters sensitivity more; Original admissible process conditions error; After component size significantly dwindles, may cause great influence to the performance of element, therefore; For reaching good element function, must be rigorous day by day to process conditions and requirements for quality control.

It mainly is through collecting data, disposal data, find out the rule of fluctuation, normal fluctuation is controlled at bottom line, eliminating the unusual fluctuations that systemic reason causes that semiconductor element is carried out quality control.Actual mass property that records and relevant criterion are compared, and take corresponding measure to correct to the difference or the anomaly that occur, thereby make operation be in controlled state, this process just is called quality control.

For example, need constantly inspection process environments in the semiconductor production process, in the board with wafer on cleannes, promptly detect the number of microparticle.Because the distribution of particle and the situation of drift have special performance; Therefore industry is used statistical Process Control figure (Statistical Process Control Chart at present; SPCChart) form all contains WECO rule (the unusual caution criterion of west electronics corporation) automation function in the SPC software.As shown in Figure 1; It is that (wherein μ is the mean value of the quality characteristic value of said product to control limit that this criterion is set μ ± 3 σ; σ is the standard deviation of the quality characteristic value of said product), and the zone that will go up between boundary μ+3 σ and following boundary μ-3 σ is called the control area, and μ is the center line of control area; And then the zone between center line and the control area carried out trisection, be divided into regional A, area B and zone C.SPC software drops on the particle characteristics value and is designated as signal 2 in the regional A, and this moment, the signal of WECO rule was shown as "-2-2 " or " 2--2 ", and SPC software is to this type of signal alarm.Having multiplely for definite method of control limit in the control chart, is to find more contents relevant with definite control limit in 200480037968.6 the one Chinese patent application at for example application number.

Show "-2-2 " or " 2--2 " if detect the particle number signal that obtains, just think that the interior environment cleanliness of process environments or board exceeds standard, and needs downtime.If perhaps the granule number on the wafer overflows USL, just can proceed the subsequent technique flow process after then this wafer must clean.

But as shown in Figure 2, granule number has the accidental disposable high characteristic of wafing, technical being called " accidental " characteristic.Experience is told us, and this contingency height that once wafts does not represent that cleanliness factor is out of joint, it is generally acknowledged not to be abnormal phenomena.So when the phenomenon like Fig. 2 often appears in the particle control chart, should carry out cleaning in theory, but the technical staff thinks that still the whole particle number still is controlled, need not shut down or cleaning wafer.

In order to prevent the generation of above-mentioned situation, in semiconductor production process in the process environments or the impurity particle of the crystal column surface method of controlling employing be " two point method ".As shown in Figure 3, surpass USL when continuous 2, it is out of control in other words to judge that particle exceeds standard, and at this moment just takes countermeasure.

But " two point method " principle is too simply harsh, makes the mistake of " hysteresis " easily, when the situation of Fig. 4 takes place, can incur loss through delay particle detection out of control and judge, thereby delay cleaning or shutdown detection method timely, influences the quality of product.

Summary of the invention

The problem that the present invention solves provides a kind of particle autocontrol method and system, prevents to delay cleaning or shutdown detection method timely, influences the quality of product.

For addressing the above problem, the present invention provides a kind of particle autocontrol method, comprising: the characteristic value that obtains particle in crystal column surface or the process environments; The allowable upper limit value of particle number is set; The signal calculated value, the allowable upper limit value of said signal value and particle number and particle number is relevant; According to signal value analysing particulates control situation, in any three continuous signal values, there are two for exceptional value, be judged to be particle and exceed standard.

Optional, the step of said signal calculated value is divided into:

Calculate positive number $Y=\left\{\begin{array}{ccc}{\mathrm{Log}}_{\sqrt{n}}X& \mathrm{If}& X\≥1\\ 0& \mathrm{If}& X=0\end{array}\right.,$ Wherein X is the particle number, and n is the allowable upper limit value of particle number;

Optional, the signalization value $Z=\left\{\begin{array}{ccc}2& \mathrm{If}& Y\&GreaterEqual;2\\ 1& \mathrm{If}& 1\&le;Y<2\\ 0& \mathrm{If}& 0\&le;Y<1\end{array}\right.,$ Said 2 is exceptional value, and 1 and 0 is normal value.

Optional, said is to adopt WECO criterion in the SPC software according to signal value analysing particulates control situation.

Optional, it is control limit that said WECO criterion is set μ ± 3 σ, and wherein, μ is the mean value of the quality characteristic value of said product, and σ is the standard deviation of the quality characteristic value of said product.

Optional; Zone between said control limit μ ± 3 σ is divided into six subregions, and said six subregions are respectively first area C and the second area C between μ-σ and the μ between second area B, μ+σ and the μ between first area B, μ-2 σ and the μ-σ between second area A, μ+2 σ and the μ+σ between first area A, μ-3 σ and μ-2 σ between μ+3 σ and μ+2 σ.

Optional, said signal value Z=2 is positioned at first area A and second area A, and signal value Z=1 is positioned at first area B and second area B, and signal value Z=0 is positioned at first area C and second area C.

The present invention also provides a kind of particle automatic control system, comprising: acquiring unit, obtain the characteristic value of particle in crystal column surface or the process environments; The unit is set, the allowable upper limit value of particle number is set; Computing unit, the signal calculated value, the allowable upper limit value of said signal value and particle number and particle number is relevant; Analytic unit according to signal value analysing particulates control situation, has two for exceptional value in any three continuous signal values, be judged to be particle and exceed standard.

Optional, said computing unit comprises:

First computing unit calculates positive number $Y=\left\{\begin{array}{ccc}{\mathrm{Log}}_{\sqrt{n}}X& \mathrm{If}& X\&GreaterEqual;1\\ 0& \mathrm{If}& X=0\end{array}\right.,$ Wherein X is the particle number, and n is the allowable upper limit value of particle number;

First is provided with the unit, the signalization value $Z=\left\{\begin{array}{ccc}2& \mathrm{If}& Y\&GreaterEqual;2\\ 1& \mathrm{If}& 1\&le;Y<2\\ 0& \mathrm{If}& 0\&le;Y<1\end{array}\right.,$ Said 2 is exceptional value, and 1 and 0 is normal value.

Optional, said analytic unit is a WECO criterion in the SPC software.

Optional, it is control limit that said WECO criterion is set μ ± 3 σ, and wherein, μ is the mean value of the quality characteristic value of said product, and σ is the standard deviation of the quality characteristic value of said product.

Optional; Zone between said control limit μ ± 3 σ is divided into six subregions, and said six subregions are respectively first area C and the second area C between μ-σ and the μ between second area B, μ+σ and the μ between first area B, μ-2 σ and the μ-σ between second area A, μ+2 σ and the μ+σ between first area A, μ-3 σ and μ-2 σ between μ+3 σ and μ+2 σ.

Optional, said signal value Z=2 is positioned at first area A and second area A, and signal value Z=1 is positioned at first area B and second area B, and signal value Z=0 is positioned at first area C and second area C.

Compared with prior art, the present invention has the following advantages: adopting has two to be exceptional value in any three continuous signal values, be judged to be the principle that particle exceeds standard, i.e. " line-of-sight course " principle." line-of-sight course " principle has contained " two point method " principle; Not only can solve the delay problem in the control of " two point method " particle; And because particle situation out of control is judged in detection in time, can clean process environments and crystal column surface timely, improved the quality of product.

" line-of-sight course " principle can directly be used SPC software and analyze the automatic control of realization to particle, and need not to invest in addition other software, and resource can be shared.

Description of drawings

Fig. 1 contains WECO criterion figure in the existing SPC software;

Particle " accidental " property sketch map in the process of the existing crystal column surface monitor particles number of Fig. 2;

In the existing semiconductor production process of Fig. 3 the impurity particle of crystal column surface controlled the sketch map of employing " two point method ";

In Fig. 4 semiconductor production process of the present invention the impurity particle of crystal column surface controlled the sketch map of employing " line-of-sight course ";

Fig. 5 the present invention carries out the particle embodiment flow chart of control automatically;

Fig. 6 is the embodiment sketch map of particle automatic control equipment of the present invention.

Embodiment

Along with the integrated level of semiconductor device improves constantly, also increasingly high for the requirement of the cleanliness factor of crystal column surface and process environments, the microparticle number is vital in the production of wafer in control crystal column surface and the process environments.Therefore, in the manufacturing process of semiconductor device, all need carry out cleaning step after almost every step process with granule number in control crystal column surface and the process environments.The cleanliness factor of crystal column surface and process environments directly exerts an influence to device architecture, performance and life-span.Especially under the more and more littler situation of device live width; If the microparticle number exceeds standard in crystal column surface or the process environments, cause short circuit in the semiconductor device, produce impurity between the rete of device; Can not be together fully integrated, and then influence the performance and the quality of semiconductor device.

It is as shown in Figure 5 that the present invention carries out the idiographic flow of particle control, and execution in step S11 obtains the characteristic value of particle in crystal column surface or the process environments; Execution in step S12 is provided with the allowable upper limit value of particle number; Execution in step S13, the signal calculated value, the allowable upper limit value of said signal value and particle number and particle number is relevant; Execution in step S14 according to signal value analysing particulates control situation, has two for exceptional value in any three continuous signal values, be judged to be particle and exceed standard.

The present invention adopts has two to be exceptional value in any three continuous signal values, be judged to be the principle that particle exceeds standard, i.e. " line-of-sight course " principle." line-of-sight course " principle has contained " two point method " principle; Not only can solve the delay problem in the control of " two point method " particle; And because particle situation out of control is judged in detection in time, can clean process environments and crystal column surface timely, improved the quality of product.In addition, " line-of-sight course " principle can directly be used SPC software and analyze the automatic control of realization to particle, and need not to invest in addition other software, and resource can be shared.

Below in conjunction with accompanying drawing the specific embodiment of the invention is done detailed explanation.

Fig. 4 is a sketch map of in the semiconductor production process of the present invention the impurity particle of crystal column surface being controlled employing " line-of-sight course ".In conjunction with the process step S11 of Fig. 5, obtain the characteristic value of particle in crystal column surface or the process environments.In semiconductor production process, need constantly the particle number on inspection process environments, machine and the wafer to clean to guarantee crystal column surface, and amounts of particles in the process environments.Collect the control limit of characteristic value data computation control chart of the particle of crystal column surface in the production process through statistical Process Control (SPC) mode, make to analyze and use control chart.

In conjunction with Fig. 5 process step S12, the allowable upper limit value of particle number is set.As shown in Figure 4, get into the SPC monitor stages, analysis this moment is converted into control with control chart and uses control chart.The groundwork of monitor stages is to use control to monitor with control chart, and wherein, the control limit of control chart confirms according to the result of analysis phase that promptly the allowable upper limit value of particle number (USL) obtains according to the analysis result of analysis phase.

In the present embodiment, usually the allowable upper limit value (USL) of particle number opens the permissible value that the radical sign value is the particle number.For example, in the time of the allowable upper limit value (USL)=900 of particle number, the permissible value of particle number=30 then.

In conjunction with Fig. 5 process step S13, the signal calculated value, the allowable upper limit value of said signal value and particle number and particle number is relevant.The step of said signal calculated value is divided into:

At first, calculate positive number $Y=\left\{\begin{array}{ccc}{\mathrm{Log}}_{\sqrt{n}}X& \mathrm{If}& X\&GreaterEqual;1\\ 0& \mathrm{If}& X=0\end{array}\right.,$ Wherein X is the particle number, and n is the allowable upper limit value of particle number.In the present embodiment, in the time of allowable upper limit value (USL) n=900 of particle number, the permissible value of particle number then $\sqrt{n}=30.$

Then, signalization value $Z=\left\{\begin{array}{ccc}2& \mathrm{If}& Y\&GreaterEqual;2\\ 1& \mathrm{If}& 1\&le;Y<2\\ 0& \mathrm{If}& 0\&le;Y<1\end{array}\right.,$ Said 2 is exceptional value, and 1 and 0 is normal value.In the present embodiment, be as the criterion with the particle number X, when $Z=\left\{\begin{array}{ccc}2& \mathrm{If}& X\&GreaterEqual;900\\ 1& \mathrm{If}& 30\&le;X<900\\ 0& \mathrm{If}& 0\&le;X<30\end{array}\right..$

In conjunction with Fig. 5 process step S14, according to signal value analysing particulates control situation, in any three continuous signal values, there are two for exceptional value, be judged to be particle and exceed standard.As shown in Figure 1, adopt WECO criterion analysing particulates control situation in the SPC software, it is control limit that said WECO criterion is set μ ± 3 σ, and wherein, μ is the mean value of the quality characteristic value of said product, and σ is the standard deviation of the quality characteristic value of said product.

Zone between control limit μ ± 3 σ is divided into six subregions, and said six subregions are respectively first area C and the second area C between μ-σ and the μ between second area B, μ+σ and the μ between first area B, μ-2 σ and the μ-σ between second area A, μ+2 σ and the μ+σ between first area A, μ-3 σ and μ-2 σ between μ+3 σ and μ+2 σ.Wherein, said signal value Z=2 is positioned at first area A and second area A, and signal value Z=1 is positioned at first area B and second area B, and signal value Z=0 is positioned at first area C and second area C.

In the present embodiment, any two signal values are positioned at first area A that the WECO criterion sets or second area A in said three continuous signal values, represent that then particle is out of control, need clean process environments or crystal column surface, or board is shut down detection.

To be positioned at first area A or second area A that the WECO criterion sets can be that two signal values in both sides are positioned at first area A or the second area A that the WECO criterion is set to any two signal values in said three continuous signal values, and middle signal value is positioned at first area B or second area B or first area C or second area C.Can also be that first signal value is positioned at first area B or second area B or first area C or second area C, latter two continuous signal value be positioned at first area A or second area A.Can also be that preceding two continuous signal values are positioned at first area A or second area A, last signal value be positioned at first area B or second area B or first area C or second area C.

Adopt " line-of-sight course " that particle is monitored, can judge particle situation out of control more in time, and then carry out wafer in time and clean or shut down and detect or process environments is cleaned.

In addition, adopt " line-of-sight course " to carry out particle control, then particle false alarm rate out of control then is 0.0000146, and the false alarm rate 0.00000729 out of control with the particle of " two point method " is more or less the same.

Fig. 6 is the embodiment sketch map of particle automatic control equipment of the present invention.As shown in Figure 6, the particle automatic control equipment of an embodiment comprises: acquiring unit 20, obtain the characteristic value of particle in crystal column surface or the process environments.

But in process environments in the acquiring unit 20 collection semiconductor production processes, the machine and the particle data on the wafer.

After the particle characteristics data are collected, be sent to unit 21 is set.

Unit 21 is set, the allowable upper limit value of particle number is set.

Groundwork at the SPC monitor stages is to use control to monitor with control chart; Wherein, The control limit that the control chart of unit 21 is set confirms according to the result of analysis phase that promptly the allowable upper limit value of particle number (USL) obtains according to the analysis result of analysis phase.

Concrete method to set up does, with the permissible value that the radical sign value is the particle number of opening of the allowable upper limit value (USL) of particle number.For example, in the time of the allowable upper limit value (USL)=900 of particle number, the permissible value of particle number=30 then.

The allowable upper limit value of the particle number that configures is sent in the computing unit 22.

Computing unit 22, the signal calculated value, the allowable upper limit value of said signal value and particle number and particle number is relevant.

Computing unit 22 comprises:

First computing unit calculates positive number $Y=\left\{\begin{array}{ccc}{\mathrm{Log}}_{\sqrt{n}}X& \mathrm{If}& X\&GreaterEqual;1\\ 0& \mathrm{If}& X=0\end{array}\right.,$ Wherein X is the particle number, and n is the allowable upper limit value of particle number; For example n can be 900.

The positive number Y that first computing unit is calculated is sent to first the unit is set.

First is provided with the unit, the signalization value $Z=\left\{\begin{array}{ccc}2& \mathrm{If}& Y\&GreaterEqual;2\\ 1& \mathrm{If}& 1\&le;Y<2\\ 0& \mathrm{If}& 0\&le;Y<1\end{array}\right.,$ Said 2 is exceptional value, and 1 and 0 is normal value.

At last, the Z value that calculates in the computing unit 22 is sent in the analytic unit 23.

Analytic unit 23 according to signal value analysing particulates control situation, has two for exceptional value in any three continuous signal values, be judged to be particle and exceed standard.

Adopt WECO criterion analysing particulates control situation in the SPC software as shown in Figure 1, it is control limit that said WECO criterion is set μ ± 3 σ, and wherein, μ is the mean value of the quality characteristic value of said product, and σ is the standard deviation of the quality characteristic value of said product.

Zone between control limit μ ± 3 σ is divided into six subregions, and said six subregions are respectively first area C and the second area C between μ-σ and the μ between second area B, μ+σ and the μ between first area B, μ-2 σ and the μ-σ between second area A, μ+2 σ and the μ+σ between first area A, μ-3 σ and μ-2 σ between μ+3 σ and μ+2 σ.Wherein, said signal value Z=2 is positioned at first area A and second area A, and signal value Z=1 is positioned at first area B and second area B, and signal value Z=0 is positioned at first area C and second area C.

In the present embodiment, any two signal values are positioned at first area A that the WECO criterion sets or second area A in said three continuous signal values, represent that then particle is out of control, need clean process environments or crystal column surface, or board is shut down detection.

Though the present invention discloses as above with preferred embodiment, the present invention is defined in this.Any those skilled in the art without departing from the spirit and scope of the present invention, all can do various changes and modification, so protection scope of the present invention should be as the criterion with claim institute restricted portion.

Claims (5)

1. a particle autocontrol method is characterized in that, comprising:

Obtain the characteristic value of particle in crystal column surface or the process environments;

The allowable upper limit value of particle number is set;

The signal calculated value, the allowable upper limit value of said signal value and particle number and particle number is relevant, and the step of said signal calculated value is divided into:

Calculate positive number $Y=\left\{\begin{array}{ccc}{\mathrm{Log}}_{\sqrt{n}}X& \mathrm{If}& X\&GreaterEqual;1\\ 0& \mathrm{If}& X=0\end{array}\right.,$ Wherein X is the particle number, and n is the allowable upper limit value of particle number;

The signalization value $Z=\left\{\begin{array}{ccc}2& \mathrm{If}& Y\&GreaterEqual;2\\ 1& \mathrm{If}& 1\&le;Y<2\\ 0& \mathrm{If}& 0\&le;Y<1\end{array}\right.,$ Said 2 is exceptional value, and 1 and 0 is normal value;

According to signal value analysing particulates control situation, in any three continuous signal values, there are two for exceptional value, be judged to be particle and exceed standard.

2. according to the said particle autocontrol method of claim 1, it is characterized in that said is to adopt WECO criterion in the SPC software according to signal value analysing particulates control situation.

3. according to the said particle autocontrol method of claim 2, it is characterized in that it is control limit that said WECO criterion is set μ ± 3 σ, wherein, μ is the mean value of the quality characteristic value of said product, and σ is the standard deviation of the quality characteristic value of said product.

4. according to the said particle autocontrol method of claim 3; It is characterized in that; Zone between said control limit μ ± 3 σ is divided into six subregions, and said six subregions are respectively first area C and the second area C between μ-σ and the μ between second area B, μ+σ and the μ between first area B, μ-2 σ and the μ-σ between second area A, μ+2 σ and the μ+σ between first area A, μ-3 σ and μ-2 σ between μ+3 σ and μ+2 σ.

5. according to the said particle autocontrol method of claim 4; It is characterized in that; Said signal value Z=2 is positioned at first area A and second area A, and signal value Z=1 is positioned at first area B and second area B, and signal value Z=0 is positioned at first area C and second area C.

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