CN108549003A - A kind of preprocess method measuring semiconductor grade monocrystalline silicon minority carrier life time suitable for the high frequency method of photoconductivity decay measurement - Google Patents

A kind of preprocess method measuring semiconductor grade monocrystalline silicon minority carrier life time suitable for the high frequency method of photoconductivity decay measurement Download PDF

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Publication number
CN108549003A
CN108549003A CN201810365224.0A CN201810365224A CN108549003A CN 108549003 A CN108549003 A CN 108549003A CN 201810365224 A CN201810365224 A CN 201810365224A CN 108549003 A CN108549003 A CN 108549003A
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single crystal
silicon
silicon single
crystal rod
minority carrier
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CN201810365224.0A
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Inventor
高召帅
张天雨
姜浩
李福中
于跃
吴锋
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Jiangsu Xinhua Semiconductor Mstar Technology Ltd
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Jiangsu Xinhua Semiconductor Mstar Technology Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/26—Testing of individual semiconductor devices
    • G01R31/2644—Adaptations of individual semiconductor devices to facilitate the testing thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B37/00—Lapping machines or devices; Accessories
    • B24B37/02—Lapping machines or devices; Accessories designed for working surfaces of revolution
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B33/00—After-treatment of single crystals or homogeneous polycrystalline material with defined structure
    • C30B33/08—Etching
    • C30B33/10—Etching in solutions or melts

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)

Abstract

The invention discloses a kind of preprocess methods measuring semiconductor grade monocrystalline silicon minority carrier life time suitable for the high frequency method of photoconductivity decay measurement, include the following steps：(1) silicon single crystal rod is processed into cylinder；(2) silicon single crystal rod for obtaining step (1) carries out chemical polishing；(3) silicon single crystal rod for completing chemical polishing is rinsed, it is dry.Preprocess method provided by the invention can effectively eliminate the measurement error of the minority carrier life time caused by the boundary effect of silicon rod and Surface combination effect, and the actual conditions of silicon single crystal rod crystal structure and deep level metal content can really be reflected by making measurement result more.

Description

One kind being suitable for the high frequency method of photoconductivity decay measurement and measures semiconductor grade monocrystalline silicon minority carrier life time Preprocess method
Technical field
The present invention relates to a kind of preprocess methods of silicon single crystal rod, more particularly to a kind of to be suitable for the high frequency method of photoconductivity decay measurement Measure the preprocess method of semiconductor grade monocrystalline silicon minority carrier life time.
Background technology
The mean survival time of non-equilibrium minority carrier is known as minority carrier lifetime, abbreviation minority carrier life time.Semiconductor Minority carrier life time be weigh its Crystalline Quality and deep level metal content important physical parameter.It photovoltaic industry and partly leads The detection method that body industry is usually taken is：Polycrystalline silicon material is drawn into zone melting single-crystal silicon rod, is surveyed using the high frequency method of photoconductivity decay measurement The minority carrier life time for measuring silicon single crystal rod, the quality of polycrystalline silicon material is evaluated with this.But the measured value of this method is by several factors Interference, for semiconductor grade industry, minority carrier life time be downstream producer concern an important indicator, how accurately to measure few son Service life makes it precisely reflect that the real quality of silicon material is a very stubborn problem.
Invention content
Goal of the invention：In order to exclude influence of the foeign element to measurement result, it is ensured that measured value can accurately reflect monocrystalline The crystal structure and deep level metal content of silicon rod being suitable for the measurement of the high frequency method of photoconductivity decay measurement the present invention provides one kind and partly lead The preprocess method of body grade monocrystalline silicon minority carrier life time, this method can effectively eliminate the fault of construction of monocrystalline silicon silicon rod and surface is answered Close the influence of effect.
Technical solution：The high frequency method of photoconductivity decay measurement of the present invention that is suitable for measures semiconductor grade monocrystalline silicon minority carrier life time Preprocess method, include the following steps：
(1) silicon single crystal rod is processed into cylinder；
(2) silicon single crystal rod for obtaining step (1) carries out chemical polishing；
(3) silicon single crystal rod for completing chemical polishing is rinsed, it is dry.
In step (1), silicon single crystal rod is processed into cylinder using grinder.The grinder is preferably surface grinding Machine.
In step (1), the silicon single crystal rod is the silicon single crystal rod for completing the molten processing in area.Qu Rong processing is specific processed Cheng Wei：Polycrystalline silicon rod is processed into silicon single crystal rod by zone-melting process, completes the later silicon single crystal rod substantially cylindrical of the molten processing in area, But mach mode can be used to handle as optimum shape so in order to accurately measure in the presence of some corner angle, it is cylindrical.
In step (2), the chemical polishing is to utilize HF/HNO3Mixed system carries out chemical polishing.
Preferably, the HF/HNO3In mixed system, HF and HNO3Volume ratio is 1: (2-4).
Preferably, the time of chemical polishing is 5-8min.
In step (3), the silicon single crystal rod for completing chemical polishing is rinsed using ultra-high purity water.
In step (3), the drying is to dry up the moisture on silicon rod surface.
In step (3), the moisture on silicon rod surface is dried up using high pure nitrogen.
Operation principle：
1. the geometry of silicon single crystal rod
When detecting minority carrier life time by the high frequency method of photoconductivity decay measurement, detection sample is placed on monitor station, high frequency electric source carries The electric current of confession can obtain the conductivity of sample by detecting sample.When infrared light supply is irradiated to detection sample surfaces, detection Sample can be inspired photo-generate electron-hole pair, and the nonequilibrium carrier inspired can make detection sample generate additional photoconduction. After illumination disappears, additional photoconduction can continuously decrease until disappearing, and adding photoconductive extinction time by test can obtain To the mean survival time of non-equilibrium minority carrier, i.e. minority carrier life time.
Ideally, infinitely great silicon single crystal body has the periodic structure of long-range order, but silicon single crystal in practice Body must have boundary, and in boundary, the Periodic Potential of silicon single crystal silicon body occurs to interrupt suddenly or significantly distort, will Generate crystal defect.These faults of construction make occur structural distortion, thus surface state bigger at faceted pebble angle, surface at faceted pebble angle Charge density bigger, i.e., electronics is easy to accumulate at faceted pebble angle.The increase of electron density directly results in the increase of surface recombination probability, The mean survival time of photo-generate electron-hole pair is reduced, and macro manifestations reduce for minority carrier life time.In order to reduce silicon single crystal rod surface Because of the influence measured minority carrier life time caused by boundary effect, burnishing part is carried out to silicon rod first when silicon rod pre-processes Reason makes silicon rod shape that the cylinder of rule be presented.
2. silicon single crystal rod Surface Chemical Polishing liquid matches
Minority carrier life time can evaluate polycrystalline silicon material quality and control technical process in study on floating zone silicon barred body, however reality is examined The minority carrier life time of survey is the compound of body minority carrier life time and surface minority carrier life time.To reduce surface recombination effect, the few son in surface is reduced Interference of the service life to test result, it is necessary to which silicon single crystal rod is surface-treated.With HF-HNO3Mix acid system to silicon single crystal rod into Row chemical polishing, HF and HNO3Volume ratio is 1: n (n=2-4), it is ensured that the good chemical polishing effect in silicon rod surface disappears Except surface recombination center.Silicon is in HF-HNO3Reaction in system is broadly divided into two parts, the oxidation (equation 1) of silicon and dioxy The dissolving of SiClx (equation 2), reaction equation are as follows：
3Si+4HNO3→3SiO2+4NO+2H2O (1)
SiO2+6HF→H2SiF6+2H2O (2)
In the reaction, the oxidation of silicon and the dissolving of silica are to occur simultaneously.Work as HNO3When concentration increases, silicon is in HF- HNO3Reaction in system is more and more violent, and the NO amounts released are also more and more.These NO bubbles can be enriched in silicon face, and one Aspect hinders etchings of the HF to silica.On the other hand, also counteract the silica that is etched away from silicon face to molten It is transmitted in liquid.HF and HNO3There is polishing action to the corrosion of silicon, with the progress of reaction, silicon face higher point can be corroded, Surface roughness reduces.
The concentration of mixing acid system directly affects the effect of chemical polishing, when mixed proportion n is too small, it is difficult to play The effect of chemical polishing；The effect that chemical polishing can be also reduced when mixed proportion n is excessive, because if mixed proportion mistake Conference causes a large amount of NO to be gathered in silicon material surface, objectively hinders the polishing effect of mixing acid system.
3. the chemical polishing time of silicon single crystal rod
The chemical polishing time is another key factor for influencing polishing, and the time of chemical polishing is too short, can not be to list Fully corrode on crystalline silicon rod surface, it is difficult to completely remove the fault of construction on its surface, silicon rod Surface combination effect still can be to measuring As a result have an impact；On the other hand, since chemical polishing is an exothermal reaction process, with the extension of polishing time, mixed acid The temperature of system gradually rises, and the reaction speed of chemical polishing is getting faster, and chemical reaction process is difficult to control, and can lead to silicon rod Surface generates new fault of construction, and then generates new Surface combination effect, and this Surface combination effect be it is uncontrolled, Measurement result to minority carrier life time is also random.Preferred polishing time is t (t=5-8min), can make the silicon rod surface be in Existing good chemical polishing effect, the measured value of minority carrier life time is also highest.
Advantageous effect：Preprocess method provided by the invention can effectively eliminate the boundary effect and surface recombination because of silicon rod The measurement error of minority carrier life time caused by effect effectively reduces influence of the silicon rod surface texture to minority carrier life time detected value, makes Measurement result more can really reflect the actual conditions of silicon single crystal rod crystal structure and deep level metal content.
Description of the drawings
Fig. 1 is geometry to silicon single crystal rod minority carrier life time influence diagram；
Fig. 2 is HF/HNO3Volume ratio is to silicon single crystal rod minority carrier life time influence diagram；
Fig. 3 is the chemical polishing time to silicon single crystal rod minority carrier life time influence diagram；
Whether Fig. 4 is to be pre-processed to silicon single crystal rod minority carrier life time influence diagram.
Specific implementation mode
Embodiment 1
(1) the zone melting single-crystal silicon rod for choosing 5 a diameter of 12mm, cylinder is processed into using grinder.
(2) shape of 5 cylindrical shaped single crystal silicon rods is processed into following shape respectively：Retain original shape, polish one side, mill Flat two sides polishes three faces, polishes four sides.
(3) HF and HNO is utilized3The HF/HNO that volume ratio is 1: 435 silicon rod chemical polishing 5min of mixed acid system pair.
(4) it is rinsed using ultra-high purity water and completes the silicon single crystal rod of chemical polishing until the acid on silicon rod surface is completely removed, Then it utilizes high pure nitrogen to dry up the moisture on silicon rod surface, completes the preprocessing process of silicon rod.
According to the regulation of national standard GB/T 1553-2009, the minority carrier life time of each sample is measured successively, specific detection knot Fruit sees Fig. 1.
As seen from Figure 1, when the shape of silicon single crystal rod is cylindrical, the detected value highest of minority carrier life time, by silicon single crystal rod Some face polish after, the detected value of minority carrier life time is decreased obviously, and the surface being smoothed is more, the detected value of minority carrier life time It is lower, show that influence of the fault of construction of silicon single crystal rod to minority carrier life time is notable.
Embodiment 2
(1) the zone melting single-crystal silicon rod for choosing 8 a diameter of 12mm, cylinder is machined to using grinding.
(2) HF and HNO are utilized respectively to 7 silicon single crystal rods therein3Volume ratio is 1: 1,1: 2,1: 3,1: 4,1: 5,1: 6,1: 7 HF/HNO3Mixed acid system carries out chemical polishing 5min, and in addition 1 is handled without chemical polishing.
(3) it is rinsed well using 8 silicon single crystal rods of ultra-high purity water pair, is then dried up silicon rod surface using high pure nitrogen.
According to the regulation of national standard GB/T 1553-2009, the minority carrier life time of each sample is measured successively, specific detection knot Fruit sees Fig. 2.
From Figure 2 it can be seen that working as HF/HNO3The volume ratio of mixed acid system is 1: when (2-4), the detected value of minority carrier life time is obviously high In the mixed acid system of other volume ratios, illustrate to work as HF/HNO3Volume ratio control 2-4 be optimal value.
Embodiment 3
(1) the zone melting single-crystal silicon rod for choosing 10 a diameter of 12mm, cylinder is machined to using grinding.
(2) HF and HNO is utilized3The HF/HNO that volume ratio is 1: 43Mixed acid system carries out chemical polishing, time to silicon single crystal rod Respectively 1min, 2min, 3min, 4min, 5min, 6min, 7min, 8min, 9min, 10min.
(3) silicon single crystal rod is rinsed well using ultra-high purity water, is then dried up silicon rod surface using high pure nitrogen.
According to the regulation of national standard GB/T 1553-2009, the specific testing result of minority carrier life time of each sample is measured successively See Fig. 3.
As seen from Figure 3, polishing time influences minority carrier life time detected value notable, upon polishing between control in 5-8min, The detected value of minority carrier life time is apparently higher than detected value when other polishing times.
Embodiment 4
(1) the zone melting single-crystal silicon rod for choosing 10 a diameter of 12mm, is divided into 5 groups, is numbered successively as 1-A, 1-B；2- A, 2-B；3-A, 3-B；4-A, 4-B；5-A, 5-B.
(2) the A samples of 5 groups of silicon rods are all pre-processed as follows：Step (1) is machined to cylinder using grinding Shape；The HF/HNO that step (2) is 1: 3 using volume ratio3System carries out chemical polishing 5min；Step (3) will using ultra-high purity water Silicon single crystal rod after chemical polishing cleans up；Step (4) is dried up silicon rod surface using high pure nitrogen.
(3) the B samples of 5 groups of silicon rods are all handled as follows：Surface is rinsed to without apparent dirty using high purity water Object is contaminated, surface is dried up using high pure nitrogen.
(4) according to the regulation of national standard GB/T 1553-2009, the minority carrier life time of each sample is measured successively, it is specific to detect As a result see Fig. 4.
As shown in Figure 4, after being handled silicon single crystal rod according to this preprocess method, the detected value of minority carrier life time is obviously high In not carrying out pretreated silicon single crystal rod.

Claims (8)

1. a kind of preprocess method measuring semiconductor grade monocrystalline silicon minority carrier life time suitable for the high frequency method of photoconductivity decay measurement, feature It is, includes the following steps：
(1) silicon single crystal rod is processed into cylinder；
(2) silicon single crystal rod for obtaining step (1) carries out chemical polishing；
(3) silicon single crystal rod for completing chemical polishing is rinsed, it is dry.
2. according to the method described in claim 1, it is characterized in that, in step (1), silicon single crystal rod is processed into using grinder It is cylindrical.
3. according to the method described in claim 1, it is characterized in that, in step (1), the silicon single crystal rod is to complete molten place of area The silicon single crystal rod of reason.
4. according to the method described in claim 1, it is characterized in that, in step (2), the chemical polishing is to utilize HF/HNO3 Mixed system carries out chemical polishing.
5. according to the method described in claim 4, it is characterized in that, the HF/HNO3In mixed system, HF and HNO3Volume Than being 1: (2-4).
6. according to the method described in claim 4, it is characterized in that, the time of chemical polishing is 5-8min.
7. according to the method described in claim 1, it is characterized in that, in step (3), is rinsed using ultra-high purity water and complete chemistry throwing The silicon single crystal rod of light.
8. according to the method described in claim 1, it is characterized in that, in step (3), the drying is by the water on silicon rod surface Divide drying.
CN201810365224.0A 2018-04-20 2018-04-20 A kind of preprocess method measuring semiconductor grade monocrystalline silicon minority carrier life time suitable for the high frequency method of photoconductivity decay measurement Pending CN108549003A (en)

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CN109904092B (en) * 2019-03-18 2021-05-18 内蒙古中环光伏材料有限公司 Method for testing minority carrier lifetime of single crystal round rod

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Application publication date: 20180918