A kind of cleaning method of high-cleanness, high monocrystalline silicon abrasive sheet
Technical field
The present invention relates to monocrystalline silicon piece processing and manufacturing field, particularly a kind of cleaning method of high-cleanness, high monocrystalline silicon abrasive sheet.
Background technology
As everyone knows, the semiconductor monocrystal silicon chip is mainly used in making IC integrated circuit and discrete device, because the cleanliness factor that IC makes and device fabrication processes is all had relatively high expectations, therefore the silicon chip cleanliness factor as substrate requires also very high.The monocrystalline silicon growing process is to come out in vacuum low-pressure direct growth from melt.The crystal that quality is qualified forms silicon chip through cutting, and silicon chip carries out surface clean behind Overheating Treatment, chamfering, grinding step.Cleaning link quality has a direct impact finished product silicon chip surface quality.
Silicon chip grinding adopts cast iron plate to carry out two-way grinding in addition, make silicon chip reach unified thickness, in process of lapping, inevitably form the broken grain layer at silicon chip surface, metallic iron, abrasive material, silica flour even organic matter when some grind can be embedded in the broken grain layer, conventional clean generally adopts ultrasonic wave to clean, and can't reach the surface of good Impurity removal.In the technologies such as diffusion of element manufacturing, introduce impurity easily, cause device performance to descend.Do not carry out the organic removal of active surface in the cleaning method that relates in the patent 200910154751.8 " cleaning method of monocrystalline/polycrystalline silicon chips ", increased the inhomogeneities of later stage clean surface, silicon chip inorganic base concentration is bigger simultaneously, be about 30~50%, the alkali lye of so big concentration is volatilization easily in actual production, and is unfavorable to operating personnel, and site environment is relatively poor, also for the later stage surface clean has increased difficulty, cause surperficial alkali metal residual easily simultaneously, influence the silicon chip surface quality.Simultaneously, in the inorganic base reaction, ultrasonic processing is arranged, ultrasonic easily in silicon chip surface formation cavitation, so can cause the silicon chip surface reaction inhomogeneous, can there be aberration.Relate to a large amount of absolute ethyl alcohol dehydrations in the patent 200910035260.1 " a kind of silicon wafer cleaning method ", well-known absolute ethanol volatilizes is strong, and it is inflammable, this is to forbid the goods and materials controlled in producing, this cleaning method also relates to inflammable articles such as kerosene simultaneously, and potential safety hazard is bigger in actual production.
Summary of the invention
Technical problem to be solved by this invention just provides a kind of cleaning method of high-cleanness, high monocrystalline silicon abrasive sheet, uses the low alkaline concentration reactant liquor to carry out silicon chip surface broken grain layer and insert removal, guarantees the cleanliness factor of silicon chip surface, reaches clean purpose of cleaning.
For solving the problems of the technologies described above, the present invention adopts following technical scheme: a kind of cleaning method of high-cleanness, high monocrystalline silicon abrasive sheet is characterized in that comprising the steps:
(1) ground silicon chip is inserted horse;
(2) horse and silicon chip are put into the 1# dipper immersion that is loaded with industrial organic washing agent;
(3) horse and silicon chip are transferred to the ultrasonic overflow launder groove cleaning of 1#, scavenging period 5~15min: ultrasound intensity 30~100KHZ;
(4) horse and silicon chip are transferred to the ultrasonic overflow launder groove cleaning of 2#, scavenging period 5~15min, ultrasound intensity 30~100KHZ;
(5) horse and silicon chip are transferred to the 2# dipper that is loaded with inorganic alkali solution and additive, inorganic base concentration is 2~10%, and the additive volume ratio is 0.2%, and it is 2~5 μ m that silicon wafer thickness is removed;
(6) horse and silicon chip are transferred to the ultrasonic overflow launder groove cleaning of 3#, scavenging period 5~15min, ultrasound intensity 30~100KHZ;
(7) horse and silicon chip are transferred to the ultrasonic overflow launder groove cleaning of 4#, scavenging period 5~15min, ultrasound intensity 30~100KHZ;
(8) horse and silicon chip are transferred to the ultrasonic overflow launder groove cleaning of 5#, scavenging period 5~15min, ultrasound intensity 30~100KHZ;
(9) horse and silicon chip are rotated drying, and put into packing box;
(10) silicon chip is tested and and the packing.
Preferably, industrial organic washing agent concentration is 1~5% in the described step (2), and temperature is 50~70 ℃, and soak time is 10~15min.
Preferably, inorganic alkali solution is NaOH or KOH solution in the described step (5), and temperature is 60-90 ℃, scavenging period 2~10min.
Preferably, the additive volume ratio is 0.2% in the described step (5), and composition is fructose: 0.1~6%; Natrium citricum: 0.1~3%; Isopropyl alcohol: 2~3%; Cyclohexandiol: 1~2%; Sodium metasilicate 1~7%; All the other are high purity water.
Preferably, cleaning is waved in employing automatically in the described step (5), and wobble frequency is 20-100 time/min.
Preferably, the water that relates in described step (3), (4), (6), (7), (8) is high purity water, and resistivity is more than 10 megaohms, and the high purity water flow is 3~15L/min.
Preferably, adopt hot blast to advertise and rotating centrifugal drying method in the described step (9), centrifugation rate 600-1200rpm dries time 5-10min, 45 ℃ of blast temperatures.
Preferably, described horse adopts the PFA material.
The present invention tentatively cleans silicon chip earlier, adopt the inorganic alkali solution of low concentration that silicon chip surface is carried out trace then and go thick cleaning, silicon chip top layer broken grain layer is reacted 2~5 microns of removals, and surperficial insert is peeled off, so both guaranteed the cleanliness factor of silicon chip surface, keep the outer gettering function of silicon chip again, reached clean purpose of cleaning.
The specific embodiment
Below in conjunction with a concrete embodiment the present invention is made and to specify:
Embodiment 1,
A collection of ground N-type<111〉4 a cun single-chip is carried out high-cleanness, high clean, silicon chip original thickness 285-288 micron, resistivity 30~35 ohmcms:
(1) ground silicon chip is inserted PFA horse to be cleaned, and place the pure water groove to shift, prepare to clean;
(2) horse and silicon chip are put into the 1# dipper, carry out surperficial organic immersion, 60 ℃, fully soak 10min;
(3) soaked horse and silicon chip are put into transferred to the ultrasonic overflow launder of 1# and clean, scavenging period 10min, pure water flow 5L/min, ultrasound intensity 60KHZ is mainly used in removing the organic contamination of surface through fully soaking into, and removes surperficial larger particles simultaneously;
(4) behind the 10min, horse and silicon chip put into transfer to the ultrasonic overflow launder of 2# and clean, scavenging period 10min, pure water flow 5L/min, ultrasound intensity 30KHZ, the main surface of removing is than small particle, and the particle of silicon chip surface absorption is removed before guaranteeing to react;
(5) behind the 10min horse and silicon chip put into and transfer to the 2# dipper and react 90 ℃ of reaction temperatures, inorganic base concentration 5%, additive volume ratio 0.2%, scavenging period 5min, 50 times/min of wobble frequency;
(6) behind the 5min, horse and silicon chip are transferred to the ultrasonic overflow launder cleaning of 3#, scavenging period 5min, spillway discharge: 15L/min, ultrasound intensity 60KHZ fast;
(7) horse and silicon chip are put into transferred to the ultrasonic overflow launder of 4# and clean scavenging period 10min, spillway discharge: 8L/min ultrasound intensity 30KHZ;
(8) horse and silicon chip are put into transferred to the ultrasonic overflow launder of 5# and clean scavenging period 10min, spillway discharge: 8L/min, ultrasound intensity 30KHZ;
(9) cleaned horse and silicon chip are rotated drying, rotating centrifugal speed 850rpm, 45 ℃ of blast temperatures
(10) silicon chip is tested and and the packing.
Through check, the silicon wafer thickness that cleans through the method is 282-285, and the surface color homogeneous is slightly shinny, and the following 300 times of silicon chip surface observations of light microscope do not have the insert of grinding or foreign material.
Embodiment 2:
A collection of ground N-type<111〉5 a cun single-chip is carried out high-cleanness, high cleans silicon chip original thickness 525-527 micron:
(1) ground silicon chip is inserted PFA horse to be cleaned, and place the pure water groove to shift, prepare to clean;
(2) horse and silicon chip are put into the 1# dipper, carry out surperficial organic immersion, 60 ℃, fully soak 15min;
(3) soaked horse and silicon chip are put into transferred to the ultrasonic overflow launder of 1# and clean, scavenging period 15min, pure water flow 10L/min, ultrasound intensity 65KHZ is mainly used in removing the organic contamination of surface through fully soaking into, and removes surperficial larger particles simultaneously;
(4) behind the 15min, horse and silicon chip put into transfer to the ultrasonic overflow launder of 2# and clean, scavenging period 15min, pure water flow 10L/min, ultrasound intensity 28KHZ, the main surface of removing is than small particle, and the particle of silicon chip surface absorption is removed before guaranteeing to react;
(5) behind the 15min horse and silicon chip put into and transfer to the 2# dipper and react, 70 ℃ of reaction temperatures, inorganic base concentration are 3%, additive volume ratio 0.2%, scavenging period 10min, 80 times/min of wobble frequency;
(6) behind the 10min, horse and silicon chip are transferred to the ultrasonic overflow launder cleaning of 3#, scavenging period 10min, spillway discharge: 15L/min, ultrasound intensity 65KHZ fast;
(7) behind the 10min horse and silicon chip put into and transfer to the ultrasonic overflow launder of 4# and clean scavenging period 10min, spillway discharge: 12L/min ultrasound intensity 28KHZ;
(8) behind the 10min horse and silicon chip put into and transfer to the ultrasonic overflow launder of 5# and clean scavenging period 10min, spillway discharge: 12L/min, ultrasound intensity 28KHZ;
(9) cleaned horse and silicon chip are rotated drying, rotating centrifugal speed 950rpm, 45 ℃ of blast temperatures
(10) silicon chip is tested and and the packing.
Through check, the silicon wafer thickness that cleans through the method is 521-523, and the surface color homogeneous is slightly shinny, and the following 300 times of silicon chip surface observations of light microscope do not have the insert of grinding or foreign material.