CN1545143A - Method for preparing polysilicon - Google Patents
Method for preparing polysilicon Download PDFInfo
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- CN1545143A CN1545143A CNA2003101100564A CN200310110056A CN1545143A CN 1545143 A CN1545143 A CN 1545143A CN A2003101100564 A CNA2003101100564 A CN A2003101100564A CN 200310110056 A CN200310110056 A CN 200310110056A CN 1545143 A CN1545143 A CN 1545143A
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- amorphous silicon
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- polysilicon
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Abstract
The invention is a method to convert noncrystalline silicon into polycrystalline silicon. It splashes a thin layer of metallic Ni on the surface of a dehydrogenated noncrystalline, thickness of the thin layer is 0.5-2.5 nm, anneals for 2-4 hours at 400-500 deg.C in nitrogen gas to form Ni silicide NiSi, and uses a quasi-molecular laser with energy density 260-360mJ/cm2 to melt noncrystalline silicon. With the decrease of the temperature of melted noncrystalline silicon, it obtains polycrystalline growth by using NiSi2 microcrystal nucleus as seed crystal both on the top interface of the melted noncrystalline silicon and on the bottom interface, namely a solid-liquid interface. By this method, crystallization can be made on the top and bottom interfaces at the same time, largely improving crystallinity.
Description
Technical field: the invention belongs to technical field of semiconductor, relate to a kind of silicon materials, specifically a kind of method that amorphous silicon is changed into polysilicon.
Background technology: at present, preparation polysilicon membrane technology mainly is divided into following several according to growing environment, i.e. pre-deposition method (as-deposited), solid phase crystallization method (SPC), metal inducement method (MIC), pulse Rapid Thermal sintering process (PRTA) and excimer laser crystallization method (ELA).
The pre-deposition method is normally by low-pressure chemical vapor deposition (LPCVD) equipment direct growth.Under about 630 ℃ of high temperature, SiH
4Thermal decomposition deposition takes place become polysilicon.The polysilicon granularity of the method growth is less, and growth temperature is higher, is not suitable in growth on glass.
Solid phase crystallization method is that the amorphous silicon membrane of deposit is placed on ambient temperature about 650 ℃, and is common more than 10 hours by the thermal annealing of long period, and amorphous silicon is changed into polysilicon.The method also is at high temperature to carry out, and degree of crystallization is lower.
The metal inducement method is to pass through some metal or its slaine on the basis of solid phase crystallization method, induces amorphous silicon generation crystallization.Growth mechanism according to this method of bibliographical information is: metal and a-Si can reduce crystallization temperature in that diffusion reaction takes place at the interface, make the crystallization temperature of a-Si can be lower than 500 ℃.Reports such as Carmarata, Ni injects the a-Si film by ion, adds thermosetting NiSi
2Compound, NiSi
2Can generate by the a-Si migration as nucleus.The nucleus of silicon is at first at NiSi
2/ a-Si interface nucleating growth.At NiSi
2The direction of motion is because the Ni atom is at NiSi
2/ a-Si surface chemistry gesture is low, and Ni is diffused into a-Si and forms new NiSi
2/ a-Si interface.Therefore, the opposite direction silicon in the Ni diffusion obtains growth on the one hand, and Ni moves to depth on the one hand, continues to form new NiSi
2/ a-Si interface promptly forms new NiSi
2This method crystallization time is long, and the polysilicon degree of crystallization that obtains neither be very high.
Pulse Rapid Thermal sintering process and excimer laser sintering process all are the amorphous silicon heat fused, and crystallization takes place during liquid amorphous silicon cools.Wherein in the excimer laser sintering process, requirement laser energy density appropriateness, crystallization does not take place during less than crystallization threshold energy density, decrystallized or controlled micro crystallization takes place in a-Si when too high, this is owing to fail to form the solid liquid interface of recrystallization, liquify area temperature in the film is more much higher than fusing point, and cooling rate is too fast to be caused.
In addition, the Chinese patent communique discloses a kind of " thin-film transistor and manufacture method " (CN 1357925), is by to amorphous silicon film irradiating laser repeatedly, realizes being made of a plurality of crystal grain, by suppressing the border in abutting connection with crystal grain.
Summary of the invention: in order to overcome the low deficiency of degree of crystallization of above-mentioned preparation polysilicon method, the present invention adopts excimer laser, utilizes the inductivity of metallic nickel, and a kind of method for preparing polysilicon is provided.
The present invention forms small crystal nucleus in amorphous silicon surfaces earlier, and its method is the amorphous silicon surfaces sputter skim metallic nickel in dehydrogenation, and thickness of thin layer is 0.5～2.5nm, and 400～500 ℃ of temperature, nitrogen atmosphere was annealed 2～4 hours down, forms nisiloy compound N iSi
2NiSi
2The lattice structure of compound is close with the lattice structure of Si, and lattice constant only differs from 0.4%, therefore can be compound N iSi
2Regard some small crystal nucleus as.
Above-mentioned sample is placed on vacuum chamber, 200～300 ℃ of underlayer temperatures, air pressure 2～8 * 10
-4Pa melts amorphous silicon by excimer laser.The excimer laser energy density is 260～360mJ/cm
2, laser output frequency is 3～10Hz, it is 6～20 times/second that sample is subjected to the light number of times.Along with the reduction of melt amorphous silicon temperature, take place with NiSi on the surface of amorphous silicon
2Growth for the polysilicon of small crystal nucleus.Here polysilicon interface growth on amorphous silicon, it is different from the growth of metal inducement method polysilicon, with NiSi
2The migration of Ni does not take place for the polycrystalline silicon growth of small crystal nucleus.Because laser energy melts amorphous silicon, reduced the surface energy of silicon atom in the amorphous silicon, along with the reduction of temperature, silicon atom is with NiSi
2Small crystal nucleus is that central point rearranges at each lattice point place, forms polysilicon.In the amorphous silicon of fusing owing to there is solid liquid interface, at this material that also exists some can play the small crystal nucleus effect at the interface, with the reduction of the amorphous silicon temperature of fusing crystallization takes place also.Here polysilicon is the following interface growth at amorphous silicon.The crystallization principle at following interface is identical with the laser crystallization method.
By this way, crystallization takes place in two interfaces simultaneously about the amorphous silicon of fusing, makes degree of crystallization obtain further raising.Adopt the present invention to make amorphous silicon upper and lower interface crystallization simultaneously, can obtain higher degree of crystallization being arranged than interface crystallization under interface crystallization on the simple amorphous silicon such as metal inducement method or the amorphous silicon such as excimer laser crystallization method.The raising of degree of crystallization can compare with metal inducement method and excimer laser crystallization method by experiment, verifies with the XRD test result.The XRD characteristic peak intensity height of polysilicon has reflected the height of degree of crystallization relatively.
Fig. 1 is the XRD test result that the present invention prepares polysilicon, and Fig. 2 is the XRD test result that excimer laser crystallization legal system is equipped with polysilicon, and Fig. 3 is the XRD test result that the metal inducement legal system is equipped with polysilicon.For the ease of contrast, Fig. 1,2,3 sample all are to unify preparation and test under the condition in identical parameters, and all are to carry out under the good conditions relatively.For ease of the contrast test result, used initial curve, not digitized processing.
From test result as can be seen, Fig. 1 characteristic peak occurred at (111) of polysilicon face (angle of diffraction is 28.47 °), (220) face (angle of diffraction is 47.30 °), (311) face (angle of diffraction is 56.14 °); The characteristic peak of two faces (111), (220) only appears in Fig. 2, and corresponding intensity all is not so good as Fig. 1; The characteristic peak of (311) face only appears in Fig. 3, and the halfwidth broadening, illustrates that crystal grain is little, intensity is very weak, and only formed the skim microcrystal silicon on the surface of amorphous silicon this moment, mainly is NiSi
2Small crystal nucleus.By the test result contrast, confirm that further the present invention is that degree of crystallization has obtained further raising two faces while crystallization.
Description of drawings: Fig. 1 is the XRD test result that the present invention prepares polysilicon.The amorphous silicon of sample preparation condition: 50nm is at 450 ℃ of following thick nickel of sputter 1.5nm behind 3 hours dehydrogenations of annealing, 450 ℃ of annealing 3 hours down, is 330mJ/cm with excimer laser in energy density at last again
2, frequency 5Hz is subjected to 10 times/second irradiations down of light number of times.
Fig. 2 is the XRD test result that excimer laser crystallization legal system is equipped with polysilicon.The amorphous silicon of sample preparation condition: 50nm is 330mJ/cm with excimer laser in energy density behind 3 hours dehydrogenations of annealing down at 450 ℃
2, frequency 5Hz is subjected to 10 times/second irradiations down of light number of times.
Fig. 3 is the XRD test result that the metal inducement legal system is equipped with polysilicon.The amorphous silicon of sample preparation condition: 50nm is at 450 ℃ of following thick nickel of sputter 1.5nm behind 3 hours dehydrogenations of annealing, again 450 ℃ of annealing 3 hours down.
Embodiment: further specify the present invention below in conjunction with embodiment.
At the thick H:a-Si of growth 50nm on glass, then at 450 ℃, nitrogen atmosphere is 3 hours dehydrogenations of annealing down with the PECVD method, behind the thick nickel of sputter 1.5nm again at 450 ℃, nitrogen atmosphere annealing 3 hours down, at last sample being placed on vacuum degree is 8 * 10
-4Pa, the annealing chamber that underlayer temperature is 300 ℃ uses laser energy density 330mJ/cm
2, frequency 5Hz is subjected to the excimer laser irradiation sample of light number of times 10 times/second.By Japan's D/max-rAXRD instrument of science in 40KV, 100mA specimen.
Claims (2)
1, a kind of method for preparing polysilicon is characterized in that the amorphous silicon surfaces sputter skim metallic nickel in dehydrogenation, and thickness of thin layer is 0.5～2.5nmnm, and 400～500 ℃ of temperature, nitrogen atmosphere was annealed 2～4 hours down, forms nisiloy compound N iSi
2With energy density is 260～360mJ/cm
2Excimer laser amorphous silicon is melted, along with the amorphous silicon temperature of fusing reduces, grow polysilicon at the upper and lower interface place of amorphous silicon.
2, the method for preparing polysilicon according to claim 1 is characterized in that the thickness at the amorphous silicon surfaces sputter skim metallic nickel of dehydrogenation is 1.5nm, and 450 ℃ of temperature, nitrogen atmosphere annealing 3 hours down forms nisiloy compound N iSi
2Use laser energy density 330mJ/cm
2, frequency 5Hz is melted amorphous silicon by the laser of light number of times 10 times/second, along with the amorphous silicon temperature of fusing reduces, at NiSi
2The amorphous silicon interface of small crystal nucleus and fusing and liquid phase amorphous silicon and solid phase amorphous silicon interface be growing polycrystalline silicon simultaneously.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2003101100564A CN1545143A (en) | 2003-11-15 | 2003-11-15 | Method for preparing polysilicon |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2003101100564A CN1545143A (en) | 2003-11-15 | 2003-11-15 | Method for preparing polysilicon |
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| CN1545143A true CN1545143A (en) | 2004-11-10 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102651311A (en) * | 2011-12-20 | 2012-08-29 | 京东方科技集团股份有限公司 | Preparation method of low-temperature polycrystalline silicon film and low-temperature polycrystalline silicon film |
-
2003
- 2003-11-15 CN CNA2003101100564A patent/CN1545143A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102651311A (en) * | 2011-12-20 | 2012-08-29 | 京东方科技集团股份有限公司 | Preparation method of low-temperature polycrystalline silicon film and low-temperature polycrystalline silicon film |
| CN102651311B (en) * | 2011-12-20 | 2014-12-17 | 京东方科技集团股份有限公司 | Preparation method of low-temperature polycrystalline silicon film and low-temperature polycrystalline silicon film |
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