CN100461362C - Method for improving ultrathin plasma silicon oxy nitride electrical test accurancy - Google Patents
Method for improving ultrathin plasma silicon oxy nitride electrical test accurancy Download PDFInfo
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- CN100461362C CN100461362C CNB2005100299993A CN200510029999A CN100461362C CN 100461362 C CN100461362 C CN 100461362C CN B2005100299993 A CNB2005100299993 A CN B2005100299993A CN 200510029999 A CN200510029999 A CN 200510029999A CN 100461362 C CN100461362 C CN 100461362C
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Abstract
In technique of semiconductor device manufacture, measurement of equivalent oxide thickness (EOT), and voltage of soft breakdown is a very important key for oxide of gate in 90 Nano manufacturing procedure. When conventional quasi C-V method is applied to azotized oxide, there are lots of noises caused by unstable charges in oxide. Especially, it is takes long time for positive charges brought from nitridation of plasma to be discharged and stabilized. Otherwise, unstable state of charges makes measured result contain lots of noises. Usually, it needs to take round the day to make charges stable before formal measurement. The disclosed method makes charges in testing sample stable rapidly, and prevents issue of noise.
Description
Technical field
The present invention relates to a kind of method that improves ultrathin plasma silicon oxy nitride electrical test accurancy, relate in particular to a kind of method of testing that can avoid the data that record because of the electric charge that oxide ionic medium body nitridation process stays and produce noise.
Background technology
In semiconductor fabrication process, for the gate oxide of 90 nanometer processing procedures, the measurement of equivalent oxide thickness EOT (Equivalent Oxide Thickness) and soft breakdown voltage is very crucial.Conventional oxide or thick-oxide can be measured with accurate C-V method at an easy rate, for example measure in silicon wafer surface deposit corona charge (Corona Charge).But the Q-V method of measurement of this corona charge has many noises when being applied to the pecvd nitride oxide, because the electric charge in oxide is unsettled, and can be to outdiffusion and loss in time.The positive charge of being integrated by pecvd nitride particularly will take a long time to make its discharge and settle out, otherwise will make measurement result that a lot of noises are arranged owing to the labile state of electric charge, become inaccurate.Usually before formal the measurement, need when daylong under the chien shih charge stable.
For the gate oxide of 90 nanometer processing procedures, be main flow with the gate oxide that divides coupling formula pecvd nitride.Usually hope can detect the nitrogen content in the gate oxide, and this parameter is very crucial to the performance of semiconductor device, if nitrogen content can not be controlled well, the performance of device can be unstable, and the electrical thickness of gate oxide will the value of departing from objectives.Measure nitrogen content and can use X-ray photoelectric wave spectrum (XPS, X-ray Photoelectrons Spectrum), it adopts x-ray irradiation to make the target excitation photon obtain wave spectrum, and then analyzes the nitrogen content that obtains in the gate oxide.This is a kind of effective method, but the cost of equipment tool is very high.And XPS only can check nitrogen content, but can not reflect the problem of nitrogen content and oxide thickness.
Use electric charge C-V method can measure the electricity oxide thickness at present, it can reflect the character of bulk oxide more realistically, and is not only its nitrogen content of reflection.This method is widely used in traditional mixes nitrogen with by the use of thermal means, does not wherein contain the furnace oxidation thing of excessive charge.In more advanced nitrogen dopping process to oxide, employing be pecvd nitride, this method can obtain more nitrogen and top and distribute.It is electrically charged that but pecvd nitride can make object, and the electric charge instability that produces, meeting discharge process for some time, and object institute is electrically charged during this is in the variable condition in time always.
The problem of running at present is, because above-mentioned electric charge changes in time always, the measured value that will produce data-bias when adopting electric charge C-V method to measure and can not get being consistent with legitimate reading, performance intuitively are that measured value can be different in time and produce skew.In Fig. 1, breakdown voltage value should be able to be higher under low DPN power, and is linear but actual curve is not, and is exactly the influence owing to Measuring Time, and the EOT data also will more not conform in addition, and it is measured time effects very much.
Summary of the invention
Because the oxide strip electric charge of pecvd nitride, and electric charge instability makes and adopts the actual data shortcoming of skew easily that records when for example the such method of electric charge C-V is measured, and proposes the present invention in order to overcome.
The object of the present invention is to provide a kind of method that deposits comprehensive reversed charge with measurement ultrathin plasma silicon oxynitride, by lay the electrical opposite electric charge of formed electric charge in one deck and the pecvd nitride process on the measuring samples surface, make it obtain neutralization, thereby when for example electric charge C-V method is measured, be unlikely to because the time dependent labile state of electric charge has influence on measurement result in following adopted.
Generally, the step of the inventive method is as follows:
1, wait other accuracy metering methods to calculate the concentration of nitrogen additive by XPS or secondary ion mass spectroscopy analysis (SIMS), calculate the quantity of electric charge that needs deposit with following formula according to the concentration that records:
N
2Dosage/2 * correction coefficient (wherein correction coefficient is between 1/300 to 1/500);
2, deposit saturated comprehensive anti-property electric charge with the inert gas that is ionized to sample surfaces by the electric weight that calculates;
3, wait 10 to 30 minutes, make above-mentioned anti-property electric charge diffuse and penetrate into the gate oxide layers of sample, the electric charge that neutralization comes owing to the pecvd nitride processing procedure of DPN;
4, the breakdown voltage value of measuring samples is drawn the curve chart of puncture voltage and Measuring Time;
If the trend of 5 curves changes still too greatly, just carry out step 2,3,4 again, tend to be steady up to the curve of puncture voltage and Measuring Time, meet the desired degree.
The invention has the advantages that on the one hand, it can solve the unstable electric charge that pecvd nitride brings well makes the sample of accepting test can not get the problem of accurate result when carrying out testing electrical property; On the other hand, method of the present invention can make the electric charge in the sample that needs to test settle out at short notice, and general needs 10～30 fens clock times, and the time that settles out than charge discharge in the normal wait sample shortens a lot, can raise the efficiency.
Description of drawings
The accompanying drawing that comprises among the application is a component part of specification, and accompanying drawing and specification and claims one are used from explanation flesh and blood of the present invention, are used for understanding better the present invention.In the accompanying drawing:
Fig. 1 is when not using the inventive method, tests the electrical thickness that obtains and the curve chart of puncture voltage to carrying out branch coupling formula pecvd nitride oxide sample under the different capacity;
Fig. 2 is by method selection-8E of the present invention
-6Coulomb/cm
2As saturated comprehensive positive charge, the quantity of electric charge of calibration deposition and to after the sample treatment like this, puncture voltage that records and electrical one-tenth-value thickness 1/10 and handle the curve synoptic diagram of the corresponding data contrast that obtains according to the method described above;
Fig. 3 does not use the inventive method and uses the inventive method in a period of time, electrical thickness and puncture voltage to sample under different situations are monitored the curve synoptic diagram that obtains;
Fig. 4 is a curve chart of the electrical thickness of the oxide of sample and puncture voltage being tested gained according to method of the present invention in a period of time.
Embodiment
In order to understand content of the present invention better, the invention will be further described below in conjunction with embodiment, but these embodiment are not construed as limiting the present invention.
Obtain pecvd nitride oxide sample and etc. in blanking time to be measured, before also promptly it formally being measured, earlier deposit anti-property electric charge comprehensively, wait a period of time, make the electric charge that is deposited penetrate in the sull and other charging neutrality to sample surfaces.Can carry out the corona charge test to sample with for example Q-V method then, be unlikely to make test result to be subjected to unnecessary unstable charge affects in the sample.
Wherein, described anti-property electric charge can deposit by such mode, with for example argon gas ionization of inert gas, make it have in the sull with specimen electrically opposite electric charge of electric charge, the surface of specimen is covered in this ionized gas atmosphere comprehensively, the deposition of this anti-property electric charge and the control of the quantity of electric charge can be adopted present existing instrument, for example the Quantox instrument that provides of US business's KLA-Tencor company (KLA) and and the supporting method of operation of instrument.
After handling through said method, the test curve of puncture voltage and electrical thickness is tended to be steady, as shown in Figure 2, use the inventive method after, puncture voltage and electrically the curve expanded range of thickness be respectively 0.015V and
0.07V when being better than not using the inventive method and
Above-mentioned anti-property electric charge generally is lower than the concentration of nitrogen additive when depositing, concrete operation method is, wait other accurate measures to calculate the nitrogen additive concentration of sull by XPS analysis or secondary ion mass spectroscopy analysis (SIMS) earlier, calculate the quantities of charge that needs deposition with this.For example, obtaining nitrogen additive by XPS analysis is 4.2E
15/ cm
2, so maximum positive charge amount will be less than: 4.2E15 * 1.6E
-19=6.72E
-4(coulomb), if enter sull guarantee it is N
2 +, then should be 6.72E
-4/ 2=3.61E
-4But be not to have only a kind of (nitrogen) to enter in the gate oxide under some situation, preferably do different comprehensive saturated positive charge tests in addition, select the positive charge electric weight of the closing to reality an of the best with a positive charge.In the present invention, the electric weight of electric charge in the oxide being selected the correction coefficient of an optimization is 1/361.In addition, inventor selection-8E
-6Coulomb/cm
2As saturated comprehensive positive charge, the quantity of electric charge of calibration deposition and to after the sample treatment like this, as shown in Figure 3, in puncture voltage test to sample, puncture voltage no longer includes in time obviously trend of rising, that is to say that it is not easy the influence of tested person time, originally the excursion of puncture voltage is 0.07V, and electrically the varied in thickness scope is
Behind the adopting said method excursion be respectively 0.015V and
The practical operation step is as follows:
1, measure the concentration of calculating nitrogen additive by the XPS analysis method, the concentration that records is calculated the quantity of electric charge that needs deposition with following formula:
N2 dosage/2 * 1/361;
2, deposit saturated comprehensive anti-property electric charge by the electric weight that calculates to sample surfaces;
3, wait 10 minutes, make above-mentioned anti-property electric charge diffuse and penetrate into the gate oxide layers of sample, the electric charge that neutralization comes owing to the pecvd nitride processing procedure of DPN;
4, the breakdown voltage value of measuring samples is drawn the curve chart of puncture voltage and Measuring Time;
If the trend of 5 curves changes still too greatly, just carry out step 2,3,4 again, curve up to puncture voltage and Measuring Time tends to be steady, and meets the desired degree, the data that record is unlikely to because the charge generation noise that oxide ionic medium body nitridation process stays.
The effect of practical application the inventive method is seen Fig. 4, this is a curve chart of the electrical thickness of the oxide of sample and puncture voltage being tested in a period of time gained, among the figure January 8 left side vertical dotted line be the line of demarcation of using the inventive method, bring into use method of the present invention from dotted line the right, as can be seen from the figure, after adopting method of the present invention, the data that record are not easy the noise effect of the charge generation that oxide ionic medium body nitridation process stays, remain in the stable scope, can see the method for the present invention of using very intuitively, the influence of noise has reduced 4 times, and the nitrogen dose concentration at circle sign place is when having skew, and the data that record also can correctly reflect and not be subjected to noise effect.
More than show and described basic principle of the present invention and principal character and advantage of the present invention.The technical staff of the industry should understand; the present invention is not restricted to the described embodiments; that describes in the foregoing description and the specification just illustrates principle of the present invention; the present invention also has various changes and modifications without departing from the spirit and scope of the present invention, and these changes and improvements all fall in the claimed scope of the present invention.The scope of protection of present invention is defined by appending claims and equivalent thereof.
Claims (5)
1. method that improves ultrathin plasma silicon oxy nitride electrical test accurancy is characterized in that this method comprises:
-according to the electric weight that calculates with the inert gas that is ionized to the anti-property of the comprehensive deposition of sample surfaces electric charge, make in the anti-property charging neutrality sample of deposition electric charges contained.
2. the method for claim 1 is characterized in that, comprises the steps:
(1) calculate the concentration of nitrogen additive by the method that can accurately measure, calculate the electric weight that needs deposit with following formula according to the concentration that records:
N
2Dosage/2 * correction coefficient;
(2) deposit saturated comprehensive anti-property electric charge with the inert gas that is ionized to sample surfaces according to the electric weight that calculates;
(3) leave standstill sample, make above-mentioned anti-property electric charge diffuse and penetrate into the gate oxide layers of sample, the electric charge that neutralization comes owing to the pecvd nitride processing procedure;
(4) the electrical data of measuring samples are drawn the curve chart of electrical data and Measuring Time;
(5) still do not meet actual demand if the trend of curve changes,, tend to be steady, satisfy the concrete degree of using expectation up to the curve that records data and Measuring Time with regard to carrying out step 2,3,4 again.
3. method as claimed in claim 2, wherein accurately the method for metric calculation nitrogen additive concentration comprises Spectrum Analysis of X-ray photoelectric or secondary ion mass spectroscopy analysis.
4. method as claimed in claim 2, wherein correction coefficient is between 1/300 to 1/500.
5. method as claimed in claim 2 wherein leaves standstill sample, and making the time of the electric charge that anti-property electric charge scattering and permeating and neutralization come owing to the pecvd nitride processing procedure is 10～30 minutes.
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| CNB2005100299993A CN100461362C (en) | 2005-09-23 | 2005-09-23 | Method for improving ultrathin plasma silicon oxy nitride electrical test accurancy |
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| CN100461362C true CN100461362C (en) | 2009-02-11 |
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| CN101197300B (en) * | 2007-12-25 | 2011-11-09 | 上海宏力半导体制造有限公司 | PPID monitoring method in integrated circuit production process |
| CN106290544B (en) * | 2015-05-22 | 2019-04-16 | 中芯国际集成电路制造(上海)有限公司 | A kind of SIMS analysis method |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5500607A (en) * | 1993-12-22 | 1996-03-19 | International Business Machines Corporation | Probe-oxide-semiconductor method and apparatus for measuring oxide charge on a semiconductor wafer |
| US6278267B1 (en) * | 1997-08-20 | 2001-08-21 | Dainippon Screen Mfg. Co., Ltd. | Method of determining impurity content and apparatus for the same |
| US6472233B1 (en) * | 1999-08-02 | 2002-10-29 | Advanced Micro Devices, Inc. | MOSFET test structure for capacitance-voltage measurements |
| CN1581464A (en) * | 2003-08-06 | 2005-02-16 | 中芯国际集成电路制造(上海)有限公司 | Semiconductor element manufacturing method by detecting nitride content of gage silicon oxide layer |
-
2005
- 2005-09-23 CN CNB2005100299993A patent/CN100461362C/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5500607A (en) * | 1993-12-22 | 1996-03-19 | International Business Machines Corporation | Probe-oxide-semiconductor method and apparatus for measuring oxide charge on a semiconductor wafer |
| US6278267B1 (en) * | 1997-08-20 | 2001-08-21 | Dainippon Screen Mfg. Co., Ltd. | Method of determining impurity content and apparatus for the same |
| US6472233B1 (en) * | 1999-08-02 | 2002-10-29 | Advanced Micro Devices, Inc. | MOSFET test structure for capacitance-voltage measurements |
| CN1581464A (en) * | 2003-08-06 | 2005-02-16 | 中芯国际集成电路制造(上海)有限公司 | Semiconductor element manufacturing method by detecting nitride content of gage silicon oxide layer |
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Effective date of registration: 20111129 Address after: 201203 Shanghai Zhangjiang Road, Zhangjiang High Tech Park of Pudong New Area No. 18 Co-patentee after: Semiconductor Manufacturing International (Beijing) Corporation Patentee after: Semiconductor Manufacturing International (Shanghai) Corporation Address before: 201203 Shanghai Zhangjiang Road, Zhangjiang High Tech Park of Pudong New Area No. 18 Patentee before: Semiconductor Manufacturing International (Shanghai) Corporation |
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