Summary of the invention
The main object of the present invention is intended to provide the modeling method and based on this model of a kind of film thickness and gas flow
Film thickness method for on-line optimization.
To reach above-mentioned purpose, the present invention provides a kind of modeling of film thickness and gas flow applied to CVD film-forming process
Method, the CVD film-forming process are to form film, the modeling on the surface of multiple semi-conductor silicon chips by introducing technology gas
Method the following steps are included:
S1: the benchmark film thickness of test silicon wafer in the multiple semi-conductor silicon chip is obtained under the conditions of fundamental technology;
S2: it carries out multiple groups film thickness and adjusts experiment to obtain the film thickness of the test silicon wafer under different experimental conditions, wherein often
It is the gas flow for only changing the process gas of the fundamental technology condition that the group film thickness, which adjusts the experiment condition of experiment,;And
S3: multiple Thickness Variations according to the film thickness of obtained multiple test silicon wafers relative to the benchmark film thickness
Gas flow of the gas flow relative to the fundamental technology condition corresponding to the film thickness of value and multiple test silicon wafers
Multiple flow volume change values, linear film thickness changes in flow rate relational model is calculated.
Preferably, the linear film thickness changes in flow rate relational model expression established in step S3 are as follows: Δ TK=Δ
FLC, wherein Δ TK is Thickness Variation value, and Δ FL is the flow volume change values of process gas, and C is Thickness Variation value and gas flow
The relational matrix of changing value.
Preferably, it is n that the film thickness, which adjusts the quantity of experiment, then the relational matrix expression are as follows:Wherein Δ TKiIt is adjusted for film thickness described in i-th group and tests film thickness change obtained
Change value, Δ FLiThe flow volume change values of process gas used by testing are adjusted for film thickness described in i-th group, n is positive integer.
Preferably, the quantity of the test silicon wafer is n, and the process gas is partly led by the way that air inlet importing in the road n is the multiple
The surface of body silicon wafer;Film thickness described in i-th group adjusts the flow volume change values Δ FL of experimentiExpression are as follows: Δ FLi=[Δ flowi,1,Δ
flowi,2.....Δflowi,n];I-th group of the film thickness adjusts the Thickness Variation value for testing the test silicon wafer obtained
ΔTKiExpression are as follows: Δ TKi=[Δ thki,1,Δthki,2.....Δthki,n]。
Preferably, the film thickness difference of the target film thickness of the benchmark film thickness and the CVD film-forming process is the target film thickness
5%~10%.
Preferably, the linear film thickness changes in flow rate relational model is equipped with restrictive condition, and the restrictive condition is described
Film thickness corresponding to Thickness Variation value is in the region D centered on the target film thickness.
Preferably, the radius of the region D is less than or equal to the 5% of the target film thickness of the CVD film-forming process.
The present invention also provides a kind of film thickness method for on-line optimization applied to CVD film-forming process, the CVD film-forming process
To form film on the surface of multiple semi-conductor silicon chips by introducing technology gas, the method for on-line optimization includes following step
It is rapid:
S11: the benchmark film thickness of test silicon wafer in the multiple semi-conductor silicon chip is obtained under the conditions of fundamental technology;
S12: it carries out multiple groups film thickness and adjusts experiment to obtain the film thickness of the test silicon wafer under different experimental conditions, wherein often
It is the gas flow for only changing the process gas of the fundamental technology condition that the group film thickness, which adjusts the experiment condition of experiment,;
S13: multiple Thickness Variations according to the film thickness of obtained multiple test silicon wafers relative to the benchmark film thickness
Gas flow of the gas flow relative to the fundamental technology condition corresponding to the film thickness of value and multiple test silicon wafers
Multiple flow volume change values, linear film thickness changes in flow rate relational model is calculated;
S14: the restrictive condition of the film thickness changes in flow rate relational model is set, and according to the restrictive condition, the CVD
Target film thickness changing value and the film thickness changes in flow rate relationship of the target film thickness of film-forming process relative to the benchmark film thickness
The optimal flux changing value of the gas flow relative to the fundamental technology condition is calculated in model.
Preferably, the film thickness changes in flow rate relational model expression are as follows: Δ TK=Δ FL*C, wherein Δ TK is Thickness Variation
Value, Δ FL are the flow volume change values of process gas, and C is the relational matrix of Thickness Variation value and gas flow changing value.
Preferably, it is n that the film thickness, which adjusts the quantity of experiment, then the relational matrix expression are as follows:Wherein Δ TKiIt is adjusted for film thickness described in i-th group and tests film thickness change obtained
Change value, Δ FLiThe flow volume change values of process gas used by testing are adjusted for film thickness described in i-th group, n is positive integer.
Preferably, the quantity of the test silicon wafer is n, and the process gas imports multiple described partly lead by the air inlet of the road n
The surface of body silicon wafer;Film thickness described in i-th group adjusts the flow volume change values Δ FL of experimentiExpression are as follows: Δ FLi=[Δ flowi,1,Δ
flowi,2.....Δflowi,n];I-th group of the film thickness adjusts the Thickness Variation value for testing the test silicon wafer obtained
ΔTKiExpression are as follows: Δ TKi=[Δ thki,1,Δthki,2.....Δthki,n]。
Preferably, the target film thickness changing value is the 5%~10% of the target film thickness.
Preferably, the restrictive condition is film thickness corresponding to the Thickness Variation value in being with the target film thickness
In the region D of the heart.
Preferably, step S14 includes:
The objective function of the optimal flux changing value is set, wherein the optimal flux changing value Δ FLIt is optimalTo meet
The minimum discharge changing value of restrictive condition is stated, corresponding Thickness Variation value is optimal Thickness Variation value Δ TKIt is optimal, the target
Function representation are as follows: | | Δ FLIt is optimal| |=| | Δ TKIt is optimal* inv (C) | |=Min | | (Δ TKTarget+ δ TK) * inv (C) | |, wherein | |·
| | indicate norm, Δ TKTargetFor target film thickness changing value, variable δ TK is the optimal Thickness Variation value and target film thickness changing value
Difference, | | δ TK | | < r, r are the radius of the region D;And the objective function is solved to obtain the variable δ TK, institute
State optimal Thickness Variation value and the optimal flux changing value.
Preferably, the radius of the region D is less than or equal to the 5% of the target film thickness.
Preferably, the method for on-line optimization further include: adjusted with the obtained optimal flux changing value of step S14
Gas flow of the gas flow of the fundamental technology condition as the new fundamental technology condition, repeats step S12
To step S14, the film thickness changes in flow rate relational model is updated with continuous iteration, and according to the film thickness changes in flow rate of update
Relational model calculates the corresponding optimal flux changing value, to obtain the theoretical optimal flux variation of the CVD film-forming process
It is worth and realizes that the film thickness on-line optimization of the film-forming process is adjusted.
It is proposed by the invention applied to the film thickness of CVD film-forming process and the modeling method of gas flow, can be by flow
Non-linear relation between variation and Thickness Variation is converted into linear relationship and establishes linear film thickness changes in flow rate relational model.
In addition, being calculated the invention also provides the film thickness method for on-line optimization based on the linear model using non-linear restrictive condition
Optimal gas flow changing value.It in actual use, can also be according to the optimal gas flow changing value being previously calculated, no
Disconnected iteration updates relational model, is the theoretical optimal stream of Approach by inchmeal according to the new calculated process gas flow of model evaluation
Amount is, it can be achieved that the on-line optimization of technique film thickness is adjusted.Using method proposed by the present invention, experiential film thickness adjusting side is compared
Method shortens the debug time of board, improves debugging efficiency, extends the adaptability of homotype board, technique reusability.
Specific embodiment
To keep the contents of the present invention more clear and easy to understand, below in conjunction with Figure of description, the contents of the present invention are made into one
Walk explanation.Certainly the invention is not limited to the specific embodiment, general replacement known to those skilled in the art
It is included within the scope of protection of the present invention.
Please refer to Fig. 1 and Fig. 2, film formation device includes processing chamber housing, accommodate cassette in processing chamber housing, cassette for keep to
Carry out the semi-conductor silicon chip W of CVD film-forming process.In the present embodiment, multiple semi-conductor silicon chip W are in vertical direction with predetermined
Spaced mode is contained in cassette.As shown in Fig. 2, cassette has notch 1~125,125 semi-conductor silicon chips can be accommodated
W, in these semi-conductor silicon chips, the silicon wafer accommodated in notch 13,38,63,88 and 113 is test silicon wafer M.Carrying out CVD film forming
When technique, the film thickness and film quality of test silicon wafer M is to represent the processing quality of this collection of semi-conductor silicon chip in film formation device.Gas
Body supply unit is used for the introducing technology gas into processing chamber housing, to form film in multiple semiconductor silicon on pieces.In this implementation
In example, process gas is multichannel air inlet (being the air inlet of the road n in figure), such as gas supply unit may include by multiple from processing chamber housing
Bottom upwardly extends and has the feed tube of different height, these feed tubes are located at different height in cassette respectively
The semi-conductor silicon chip of degree supplies process gas;Gas supply unit may be to upwardly extend from processing chamber housing bottom, and at it
With the feed tube of multiple fumaroles on extending direction, process gas is by these fumaroles respectively to the half of different height
Conductor silicon wafer supplies process gas.
First embodiment
Fig. 3 is the process that one embodiment of the invention is applied to the film thickness of CVD film-forming process and the modeling method of gas flow
Figure, below with reference to Fig. 1~3, the present invention will be described in detail.
The modeling method of film thickness and gas flow of the invention the following steps are included:
S1: the benchmark film thickness of test silicon wafer in multiple semi-conductor silicon chips is obtained under the conditions of fundamental technology.
Specifically, in film formation device, a complete CVD film-forming technology process includes technique step different several times
Suddenly, each processing step has corresponding process conditions demand.Especially main operation stage has process conditions more stringent
Requirement, need high-precision constant temperature thermal field to control, high-precision gas flow control, high-precision pressure control etc., these
The high-precision control of process conditions is the basis for realizing silicon wafer target film thickness.Fundamental technology condition in step sl refers to
When the film thickness of semiconductor test silicon wafer M is closer to CVD film-forming process target film thickness, to be capable of forming closest target film thickness
Semiconductor test silicon wafer M film thickness process conditions (including the process conditions such as temperature, pressure, process time, gas flow)
For basic process conditions, and the film thickness of the test silicon wafer formed under the conditions of the fundamental technology is benchmark film thickness, can pass through measurement
It obtains.In the present embodiment, the film thickness difference of the target film thickness of benchmark film thickness and CVD film-forming process is the 5% to 10% of target film thickness.
In the present embodiment, the quantity of test silicon wafer M is n, and process gas is the air inlet of the road n, and n is positive integer.
S2: it carries out multiple groups film thickness and adjusts experiment to obtain the film thickness of test silicon wafer under different experimental conditions.
Specifically, it is obtaining benchmark film thickness and then is carrying out the adjusting experiment of multiple groups film thickness.It should be noted that film thickness
The quantity for adjusting experiment is identical as the quantity of the quantity of process gas air inlet pipeline and test silicon wafer, with can in subsequent calculating
Solve relational matrix.In these experiments, the gas flow for only changing the process gas in basic condition, does not change temperature, pressure
Other process conditions such as power, process time.Process gas is directed into film formation device processing by the air inlet of the road n by each group of experiment
The surface of the indoor all semi-conductor silicon chips of chamber, and obtain the film thickness value of n test silicon wafer.In addition, these film thickness adjust experiment
It should be believable, i.e., these film thickness are adjusted in experimentation, and each controller works normally in equipment, and board is sufficiently stable, then
These film thickness adjust the film thickness data and the corresponding gas stream of these film thickness data tested under different experimental conditions obtained
Amount is available.
S3: multiple Thickness Variation values according to the film thickness of obtained multiple test silicon wafers relative to benchmark film thickness, Yi Jiduo
Multiple flow volume change values of the gas flow corresponding to the film thickness of a test silicon wafer relative to the gas flow of fundamental technology condition,
Linear film thickness changes in flow rate relational model is calculated.
The projectional technique of relational model described in detail below.
As previously mentioned, in step S1 and step S2, using the film thickness of test silicon wafer under the conditions of fundamental technology as benchmark film thickness,
So process gas flow used by the fundamental technology condition can be used as standard flow.It adjusts in experiment and does not change in subsequent film thickness
The process conditions such as temperature, pressure, process time only change process gas flow, therefore can be by the variation of test silicon wafer film thickness
Value and gas flow changing value are approximately linear relationship, meet following formula:
Δ TK=Δ FL*C, wherein Δ TK indicates Thickness Variation value, and Δ FL indicates that flow volume change values, C are Thickness Variation value
With the relational matrix of gas flow changing value.Wherein, herein and " flow volume change values " described below be film thickness adjust experiment
Employed in process gas flow relative to fundamental technology condition gas flow (standard flow) difference, it is corresponding
" Thickness Variation value " is that the process gas flow of the use is formed by difference of the film thickness of test silicon wafer relative to benchmark film thickness.
Relational matrix C is found out by the following method.
In the present embodiment, n group film thickness has been carried out altogether and has adjusted experiment (n is positive integer), has defined i-th group of (1≤i≤n) film thickness
Adjust the flow volume change values Δ FL for testing corresponding process gasi, basis is respectively relative to for the process gas flow of the road n air inlet
The flow volume change values of the gas flow of process conditions, it may be assumed that
ΔFLi=[Δ flowi,1,Δflowi,2.....Δflowi,n] (matrix of 1 × n);
It defines i-th group of (1≤i≤n) film thickness and adjusts the Thickness Variation value Δ TK for testing corresponding test silicon waferi, for n survey
The film thickness of examination silicon wafer is respectively relative to the Thickness Variation value of benchmark film thickness, it may be assumed that
ΔTKi=[Δ thki,1,Δthki,2.....Δthki,n] (matrix of 1 × n);
Since Thickness Variation value and gas flow changing value are approximately linear relationship:
ΔTKi=Δ FLiIC, wherein C is that n × n ties up matrix, then relational matrix C is indicated are as follows:
To sum up, the film thickness of benchmark film thickness is respectively relative to according to the film thickness that n group film thickness adjusts the test silicon wafer that experiment obtains
Changing value, this n group film thickness adjust the flow volume change values that the gas flow that experiment uses is respectively relative to standard flow, it will be able to count
Calculation obtains relational matrix C, can also obtain film thickness changes in flow rate relational model.It should be noted that the present invention is by flow
Non-linear relation between variation and Thickness Variation is converted into linear relationship, for the film thickness changes in flow rate relationship mould for making this linear
Type is more accurate, and changes in flow rate range should be in the region of very little.Therefore, the film thickness discharge relation model of the present embodiment is equipped with limitation
Condition, the restrictive condition are to meet film thickness corresponding to the Thickness Variation value of the relational model and should be in be with target film thickness
In the very little region D at center, then the corresponding flow volume change values of Thickness Variation value can be as small as possible at this time.
Second embodiment
On the basis of first embodiment, the present invention also provides a kind of method for on-line optimization.Referring to FIG. 4, shown in it
For the flow diagram of the method for on-line optimization of the present embodiment comprising following steps:
S11: the benchmark film thickness of test silicon wafer in multiple semi-conductor silicon chips is obtained under the conditions of fundamental technology;
S12: it carries out multiple groups film thickness and adjusts experiment to obtain the film thickness of test silicon wafer under different experimental conditions;
S13: the film thickness for multiple test silicon wafers that experiment obtains is adjusted relative to the multiple of benchmark film thickness according to multiple groups film thickness
Gas flow of the gas flow relative to fundamental technology condition corresponding to the film thickness of Thickness Variation value and multiple test silicon wafers
Multiple flow volume change values, linear film thickness changes in flow rate relational model is calculated;
S14: the restrictive condition of setting film thickness changes in flow rate relational model, and according to the restrictive condition, CVD film-forming process
Target film thickness changing value and film thickness changes in flow rate relational model of the target film thickness relative to benchmark film thickness, be calculated relative to
The optimal flux changing value of the gas flow of fundamental technology condition.
Step S11 to step S13 is identical to step S3 as step S1 in first embodiment, and therefore not to repeat here.In step
S3 has sought relational matrixAfterwards, target film thickness relative datum film thickness has been known
Target film thickness changing value Δ TKTargetIf directlying adopt Δ FLTarget=Δ TKTarget* the gas for the realization target film thickness that inv (C) is extrapolated
Body changes in flow rate Δ FLTargetIt is disabled.As previously mentioned, being the flow so that linear film thickness changes in flow rate relational model is accurate
Variation range should be in the region of very little.Therefore, it also needs to set restrictive condition, the restrictive condition to film thickness changes in flow rate relational model
To meet the very little that film thickness corresponding to the Thickness Variation value of the linear relational model should be in centered on target film thickness
In the D of region, if the corresponding flow volume change values of Thickness Variation value are as small as possible at this time, the standard of linear film thickness changes in flow rate model
True property is also higher.
Assuming that the smallest flow volume change values are optimal flux value Δ FL when meeting above-mentioned restrictive conditionIt is optimal, the changes in flow rate
Corresponding Thickness Variation is optimal Thickness Variation value Δ TKIt is optimal, optimal Thickness Variation value Δ TKIt is optimalWith target film thickness changing value Δ
TKTargetMeet following formula: Δ TKIt is optimal=Δ TKTargetThe variable δ TK of+δ TK, introducing represent optimal Thickness Variation and target film thickness
The difference value of variation.Due to Δ FLIt is optimalWith Δ TKIt is optimalMeet the restrictive condition of linear film thickness changes in flow rate model, it is therefore, also just full
Sufficient formula Δ FLIt is optimal=Δ TKIt is optimal*inv(C)。
To acquire optimal flux Δ FLIt is optimal, it initially sets up using δ TK as the objective function of variable:
MinF (δ TK)=| | Δ FLIt is optimal| |=| | Δ TKIt is optimal* inv (C) | |=Min | | (Δ TKTarget+ δ TK) * inv (C) | |,
Wherein | | | | indicate norm, variable δ TK meets constraint condition | | δ TK | | < r, r value here are the half of region D
Diameter, r value, which is preferably less than, is equal to the 5% of the target film thickness.According to known target film thickness changing value Δ TKTarget, relational matrix
C and constraint condition | | δ TK | | < r solves objective function to obtain variable δ TK, can also obtain optimal film thickness Δ TKIt is optimal。
In conjunction with relational matrix C, optimal gas flow Δ FL is calculatedIt is optimal。
In actual use, optimal flux changing value can also be adjusted the gas flow of fundamental technology condition as
New standard flow, then carry out multiple groups film thickness and adjust the corresponding Thickness Variation value of experiment acquisition, to update relational matrix, thus more
New film thickness changes in flow rate relational model.And then corresponding optimal stream is calculated according to the film thickness changes in flow rate relational model of update
Measure changing value.It loops back and forth like this, primary calculated optimal flux changing value constantly regulate the gas of fundamental technology condition in the past
Body flow carries out multiple groups film thickness adjusting experiment, updates relational model according to experimental result iteration and commented according to new relational model
Estimate calculated new optimal flux changing value, and the new corresponding process gas flow of optimal flux changing value is Approach by inchmeal
Thus theoretical optimal flux achieves that the on-line optimization of technique film thickness is adjusted.Using method proposed by the present invention, basis is compared
The film thickness adjusting method of experience, shortens the debug time of board, improves debugging efficiency, extends the adaptation of homotype board
Property, technique reusability.
In conclusion the present invention need to only adjust the experimental result of experiment by several groups of simple film thickness, film thickness can be established
With the linear relation model of gas flow, optimal gas flow changing value, nothing can be calculated and evaluated using relational model
It need to be for statistical analysis using largely testing.In addition, the present invention can also according to the optimal gas flow changing value being previously calculated,
Continuous iteration updates relational model, is the theoretical optimal stream of Approach by inchmeal according to the new calculated process gas flow of model evaluation
Amount is, it can be achieved that the on-line optimization of technique film thickness is adjusted.
Although the present invention is disclosed as above with preferred embodiment, right many embodiments are illustrated only for the purposes of explanation
, it is not intended to limit the invention, those skilled in the art can make without departing from the spirit and scope of the present invention
Several changes and retouches, and the protection scope that the present invention is advocated should be subject to described in claims.