CN102830048A - Wafer grain detecting method - Google Patents
Wafer grain detecting method Download PDFInfo
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- CN102830048A CN102830048A CN2011101624475A CN201110162447A CN102830048A CN 102830048 A CN102830048 A CN 102830048A CN 2011101624475 A CN2011101624475 A CN 2011101624475A CN 201110162447 A CN201110162447 A CN 201110162447A CN 102830048 A CN102830048 A CN 102830048A
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- wafer
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Abstract
The invention discloses a wafer grain detecting method, wherein a metal film is formed on the surface of a tested wafer to be tested, and at the same time a metal film shell which surrounds the grains on the surface of the tested wafer; the tested wafer is detected; in the detection, the size and spatial distribution information of the grains on the tested wafer are obtained based on scattered light signals formed through the scattering of the grains to measuring light on the tested wafer; and the metal film on the tested wafer is eliminated after the detection is accomplished. With the wafer grain detecting method, the detection precision of the wafer grains is improved.
Description
Technical field
The present invention relates to technical field of semiconductors, relate in particular to a kind of wafer particle detection method.
Background technology
In semiconductor technology, the cleanliness of crystal column surface are one of key factors that influences semiconductor device reliability.How to remove the pollution of crystal column surface and the research focus that the foreign substances particle is technical field of semiconductors always, and after cleaning, how the cleanliness of crystal column surface are detected the problem that also becomes semiconductor bulk technician care.
Optical detecting method because have the cleanliness of not destroying crystal column surface, the advantage that can detect in real time etc. becomes one of the most frequently used wafer detection method.Said optical detecting method uses optical scattering ionization meter technology to survey the having or not of crystal column surface particle, particle in the space distribution of crystal column surface etc.
With reference to figure 1, show the synoptic diagram of optics wafer grain testing apparatus one embodiment in the prior art.As shown in the figure, said wafer grain testing apparatus mainly comprises input path, wafer to be measured 13 and detection light path, wherein; Input path comprises laser instrument 10, convex lens 11; Said laser instrument 10 is used to send measuring light, and convex lens 11 are used for said measuring light is assembled, and also can use sphere or non-spherical reflector to focus on measuring light in other embodiments; Said measuring light is projected on the wafer 13 to be measured through the glancing incidence mode, forms on wafer to be measured 13 surfaces and surveys hot spot.When those skilled in the art found incident angle more than or equal to 70 °, the particle scattered signal was strong, and measurement effect is preferable.
Said wafer to be measured 13 is positioned on the wafer chuck 12, and said wafer chuck 12 can move and rotate, and said wafer chuck 12 drives wafer 13 to be measured moves and rotates, and makes and surveys the spiral scan of hot spot completion to wafer 13 to be measured.In scanning process, if measuring beam projects on the particle, can be by the particle scattering, the light beam that is scattered has certain space multistory angle.
Survey light path and comprise reflector group 14 and detector 15; Said reflector group 14 is used for scattered light is reflexed to the test surface of detector 15; Said detector 15 is used for scattered light is surveyed, and obtains the space multistory angle distribution situation of scattered beam, the light intensity of scattered beam, thereby obtains the distribution situation of particle on the wafer 13 to be measured; Particularly, said detector 15 is a photomultiplier.
Yet; The characteristic dimension of integrated circuit is being followed Moore's Law and is being reduced gradually, according to ITRS (International Technology Roadmap for Semiconductors, prediction ITRS); In 2012; The semiperiod length of integrated circuit is estimated to get into the 22nm technology generation, on no figure crystal column surface, needs the diameter of detected contamination particle will reach 11nm, and such smallest particles detection size is less than the detection limit of current device.
Be the SiO of 14nm below with the diameter
2Particle is that example describes.In the prior art, laser instrument sends the measuring light that wavelength is 355nm, is incident to glancing angle on the surface of wafer to be measured, and the detection spot size of formation is generally 5 * 15 microns.Diameter is that to make scattered light scatter to the azimuthal light intensity of whole 2 π be 1.174 * 10 to the particle of 14nm
-3Ppm that is to say, is that to scatter to the azimuthal light intensity of whole 2 π be 1.174 * 10 of measuring light light intensity for the particle of 14nm by diameter
-12
Particle size is less; The scattering cross-section area of particle can be less so; And owing to scattering strength is directly proportional with the scattering cross-section of particle; Therefore the formed scattered light signal of particle of reduced size is very little, and so little scattered light signal can be submerged in the noise of detector, thereby can't be detected.
And in practical application, existing checkout equipment can't accurately detect the SiO of diameter 30nm
2Particle.
This shows that the wafer detection method of prior art has run into detection limit, can't satisfy the detection requirement of current and following integrated circuit contamination particle.
Summary of the invention
The technical matters that the present invention solves provides a kind of wafer particle detection method, to improve the detection limit of particle on the wafer.
For solving the problems of the technologies described above, the present invention provides a kind of wafer particle detection method, comprising: the test wafer surface to be measured forms metallic film, forms the metallic film shell that surrounds the test wafer surface particles simultaneously; Said test wafer is detected, in said detection, to measuring the formed scattered light signal of scattering of light, obtain the size and the space distribution information of particle on the test wafer based on particle on the said test wafer; Detect the metallic film on the removal test wafer after accomplishing.Said particle comprises silica dioxide granule, nitrogen dioxide particle.
The material of said metallic film is gold, silver, platinum, titanium or aluminium.
The thickness of said metallic film is in the scope of 0.5～10nm.
The material of said metallic film is an aluminium, and the thickness of said metallic film is more than or equal to 2nm.
The thickness of said metallic film is 2nm.
The step of the metallic film on the said removal wafer to be measured comprises: through the said metallic film of chemical solution cleans.
The material of said metallic film is an aluminium, through the said metallic film of hydrofluoric acid clean.
Compared with prior art, the present invention has the following advantages:
Through on wafer to be measured, forming metallic film, thereby on the particle on the wafer to be measured, form the metallic film shell, said metallic film shell can strengthen scattered light signal, has improved the accuracy of detection of particle on the wafer.
Description of drawings
Fig. 1 is the synoptic diagram of prior art wafer pick-up unit one embodiment;
Fig. 2 is the schematic flow sheet of wafer detection method one embodiment of the present invention;
Fig. 3 is the light path synoptic diagram of wafer detection method one embodiment of the present invention;
Fig. 4 be in the wafer detection method of the present invention metal coating thickness and scattered signal intensity concern synoptic diagram.
Embodiment
A lot of details have been set forth in the following description so that make much of the present invention.But the present invention can implement much to be different from alternate manner described here, and those skilled in the art can do similar popularization under the situation of intension of the present invention, so the present invention does not receive the restriction of following disclosed practical implementation.
Secondly, the present invention utilizes synoptic diagram to be described in detail, and when the embodiment of the invention was detailed, for ease of explanation, said synoptic diagram was an instance, and it should not limit the scope of the present invention's protection at this.
Do detailed explanation below in conjunction with the accompanying drawing specific embodiments of the invention.
The present invention provides a kind of wafer detection method, shows the schematic flow sheet of wafer detection method one embodiment of the present invention with reference to figure 2.Said wafer detection method roughly may further comprise the steps:
Step S1 forms metallic film on test wafer surface to be measured, forms the metallic film shell that surrounds the test wafer surface particles simultaneously;
Step S2 detects said test wafer, in said detection, to measuring the formed scattered light signal of scattering of light, obtains the size and the space distribution information of particle on the wafer to be measured based on particle on the said test wafer;
Step S3 detects the metallic film on the removal test wafer after accomplishing.
Be described in detail in the face of each step down.
Execution in step S1; Test wafer to be measured is carried out metal coating, and through after the metal coating, the surface of test wafer can be covered by metallic film; Meanwhile; For the situation that particle is arranged on the test wafer, being positioned at the lip-deep particle of test wafer also can covering metal film, thereby forms the particle with metallic film shell.
The particle on test wafer surface is generally organism, insulating material etc., and wherein, the particle of earth silicon material, nitrogen dioxide material is the most common, wherein, the detection signal that silica dioxide granule forms a little less than, be the maximum material of detection difficulty.
Through forming the metallic film shell at particle surface, enhanced granule forms stronger scattered light signal, thereby has increased accuracy of detection measuring scattering of light greatly.Even the size of particle is less, because it is stronger to form scattered light signal, still can detect by detector, therefore can improve the detection limit of optical profile type wafer pick-up unit.
Reason in the face of metallic film shell enhancing scattered light signal describes down.
The metallic film shell of particle surface has higher reflectivity, can increase scattered signal, in addition; When measuring light projects on the particle that comprises the metallic film shell; Can produce the surface plasma wave phenomenon, measure scattering of light, and then strengthen scattered signal thereby strengthen greatly.
Below in conjunction with accompanying drawing, the principle that the metallic film shell strengthens scattered light signal is described from the angle of surface plasma wave.
With reference to figure 3, show the light path synoptic diagram of wafer detection method one embodiment of the present invention.As shown in Figure 3, after step S1, on wafer 100 to be measured, formed metallic film 101, on particle 102, formed metallic film shell 103.As everyone knows, light is a kind of electromagnetic wave, when measuring light 104 is throwed to particle 102 with grazing angle, can inspire the surface wave transmission at the outside surface and the inside surface place of metallic film shell 103, thereby in metallic film shell 103, produce surface plasma wave.The outside surface of metallic film shell 103 contacts with air; Its inside surface contacts with particle (insulating material) simultaneously; Two surface waves that are positioned at metallic film shell 103 outside surfaces and inside surface have different oscillation frequency; But after the coupling of two surface waves, has stronger scattered signal from the scattered light 105 of particle 102 outgoing.
In addition, can explain also that from the angle of scattering cross-section the metallic film shell can strengthen the principle of scattered light signal, for particle, when it is positioned in the electromagnetic wave field, relation below its scattering cross-section satisfies:
Wherein, S is a scattering cross-section, and a is the diameter of particle, ε
pBe the specific inductive capacity of particle, ε is the specific inductive capacity of air ambient, and k is a constant.
For metal, ε
pSpecific inductive capacity be generally negative, and for the insulating material of silicon dioxide, nitrogen dioxide etc., ε
pSpecific inductive capacity be generally on the occasion of.Therefore; For metallic particles under the same terms and insulated particle (for example silica dioxide granule, nitrogen dioxide particle); The scattering cross-section of metallic particles is greater than the scattering cross-section of insulated particle; Again since the intensity of scattered signal be directly proportional with the scattering cross-section of particle, so measuring light to be projected to the formed scattered light signal of metallic particles bigger.
Therefore form the metallic film shell at particle surface, can increase the scattering cross-section of particle, thereby strengthen scattered light signal, and then increase accuracy of detection, improve detection limit.
In the present embodiment, the material of said metallic film can be gold (Au), silver (Ag), platinum (Pt), titanium (Ti) or aluminium (Al), but the present invention is not restricted to this.
Preferably, said metallic film material is Ti or Al, because Ti, Al are the metal material that generally uses in the middle rear end in semiconductor fabrication process, and technologies such as the plated film of Ti, Al, etching and cleaning are very ripe in semiconductor production.
In the present embodiment, the method through sputter (sputtering), hot vapor deposition etc. forms said metallic film, but the present invention is not restricted to this.
For the different metallic material, the thickness of metallic film is different, and still, the thickness of said metallic film is usually located at the magnitude of several nanometers.
Execution in step S2; On test wafer, form after the metallic film, test wafer is positioned in the optical profile type wafer pick-up unit, measuring light is projected on the test wafer when detecting; Particle on the test wafer is owing to have the metallic film shell; Therefore the scattered light signal of its generation is stronger, and detector is surveyed said scattered light signal, the information of the size of particle and space distribution etc. on the acquisition test wafer.
Since identical with prior art through optics wafer pick-up unit to the method that test wafer detects, repeat no more at this.
With reference to figure 4, show the synoptic diagram of scattered light signal one embodiment that wafer detection method of the present invention detects.In the present embodiment, be that the silica dioxide granule of 30nm and the metallic film of aluminum are example with the diameter.
As shown in Figure 4, horizontal ordinate is the thickness of aluminium film, and ordinate is a scattered light intensity, and can be known by curve among the figure: when the aluminium film thickness was 0 (not forming the situation of metallic film on corresponding to particle), scattered light intensity was very little, less than 1ppm; And when the aluminium film thickness was increased to 0.6nm, scattered light intensity began to have obvious enhancing along with the increase of aluminium film thickness; When the aluminium film thickness increased to 2nm, scattered light intensity was enhanced to 400ppm, compared with the particle that does not comprise the metallic film shell, and this moment, scattered light intensity had the enhancing of 3 one magnitude.When the aluminium film thickness when 2nm continue to increase, scattered light intensity not have to change basically, keeps stablizing.
Therefore, in order to strengthen scattered light intensity, improve accuracy of detection and detection limit, the thickness of said aluminium film needs more than or equal to 2nm.
Meanwhile and since the aluminium film thickness greater than 2nm after, the effect that increases scattered light signal is not obvious, therefore, for fear of the waste of metal material, preferably, the aluminium foil film thickness is 2nm.Can strengthen scattered light signal so on the one hand, can reduce material cost on the other hand, practice thrift the process time.
For other metal materials, all corresponding to the preferred version of different-thickness.In the practical application, can obtain the preferred thickness corresponding through computer simulation or test of many times with different metal material.
Need to prove; Usually, the thickness of metallic film can produce the phenomenon of surface plasma wave in the metallic film shell when 0.5～0.6nm; But; When the thickness of metallic film during greater than 10nm, the surface plasma wave phenomenon can weaken, and this moment is to the enhancing of the scattered light signal obviously effect that do not recur.
Form the metallic film shell at particle surface, can strengthen scattered light signal.For same characteristic dimension, can increase the measuring accuracy of optical profile type wafer pick-up unit like this.Even characteristic dimension reduces gradually,, still can detect, and then can improve the detection limit of optics wafer pick-up unit by detector because scattered light signal is stronger.
Execution in step S3 after the detection of accomplishing test wafer, removes the metallic film on the test wafer, thereby recycles this test wafer.
In the present embodiment,, when selecting chemical solution, need to select and to react with metal material cleaning solution that simultaneously again can damage test wafer to be measured through the chemical solution cleans metallic film.
For example, metallic film is an aluminium, and chemical solution is a hydrofluoric acid solution.
Through test wafer is cleaned, remove the metallic film on it, test wafer is restored to the original state, thereby test wafer is recycled, improved the utilization factor of test wafer, save cost.
To sum up, the present invention provides a kind of wafer particle detection method, has improved wafer accuracy of detection, wafer detection limit.
Though the present invention discloses as above with preferred embodiment, the present invention is defined in this.Any those skilled in the art are not breaking away 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 (8)
1. a wafer particle detection method is characterized in that, comprising: the test wafer surface to be measured forms metallic film, forms the metallic film shell that surrounds the test wafer surface particles simultaneously; Said test wafer is detected, in said detection, to measuring the formed scattered light signal of scattering of light, obtain the size and the space distribution information of particle on the test wafer based on particle on the said test wafer; Detect the metallic film on the removal test wafer after accomplishing.
2. wafer particle detection method as claimed in claim 1 is characterized in that said particle comprises silica dioxide granule, nitrogen dioxide particle.
3. according to claim 1 or claim 2 wafer particle detection method is characterized in that the material of said metallic film is gold, silver, platinum, titanium or aluminium.
4. according to claim 1 or claim 2 wafer particle detection method is characterized in that the thickness of said metallic film is in the scope of 0.5～10nm.
5. wafer particle detection method as claimed in claim 4 is characterized in that the material of said metallic film is an aluminium, and the thickness of said metallic film is more than or equal to 2nm.
6. wafer particle detection method as claimed in claim 5 is characterized in that the thickness of said metallic film is 2nm.
7. wafer particle detection method as claimed in claim 1 is characterized in that, the step of the metallic film on the said removal test wafer comprises: through the said metallic film of chemical solution cleans.
8. wafer particle detection method as claimed in claim 7 is characterized in that the material of said metallic film is an aluminium, through the said metallic film of hydrofluoric acid clean.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106323916A (en) * | 2016-08-18 | 2017-01-11 | 中国科学院嘉兴微电子仪器与设备工程中心 | Wafer scanning detection location method |
| CN108802182A (en) * | 2018-06-14 | 2018-11-13 | 国网宁夏电力有限公司电力科学研究院 | The generator guard ring detection method of inner surface wave is encouraged based on graze |
| CN109473370A (en) * | 2018-11-16 | 2019-03-15 | 上海华力微电子有限公司 | A kind of off line detection method of crystal column surface particle |
| TWI686602B (en) * | 2013-03-15 | 2020-03-01 | 美商克萊譚克公司 | Computer-based method and apparatus for inspecting a wafer, computer-based method and apparatus for adjusting an auto-focus in a wafer inspection system, and phase filter and method of forming the same |
| TWI689722B (en) * | 2018-12-04 | 2020-04-01 | 台灣積體電路製造股份有限公司 | Method for identifying dust particles on wafer, electronic device and computer readable recording media |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| TWI686602B (en) * | 2013-03-15 | 2020-03-01 | 美商克萊譚克公司 | Computer-based method and apparatus for inspecting a wafer, computer-based method and apparatus for adjusting an auto-focus in a wafer inspection system, and phase filter and method of forming the same |
| CN106323916A (en) * | 2016-08-18 | 2017-01-11 | 中国科学院嘉兴微电子仪器与设备工程中心 | Wafer scanning detection location method |
| CN108802182A (en) * | 2018-06-14 | 2018-11-13 | 国网宁夏电力有限公司电力科学研究院 | The generator guard ring detection method of inner surface wave is encouraged based on graze |
| CN109473370A (en) * | 2018-11-16 | 2019-03-15 | 上海华力微电子有限公司 | A kind of off line detection method of crystal column surface particle |
| TWI689722B (en) * | 2018-12-04 | 2020-04-01 | 台灣積體電路製造股份有限公司 | Method for identifying dust particles on wafer, electronic device and computer readable recording media |
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Application publication date: 20121219 |