CN101673668B - Method for polishing gallium nitride crystals - Google Patents
Method for polishing gallium nitride crystals Download PDFInfo
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- CN101673668B CN101673668B CN2009101805295A CN200910180529A CN101673668B CN 101673668 B CN101673668 B CN 101673668B CN 2009101805295 A CN2009101805295 A CN 2009101805295A CN 200910180529 A CN200910180529 A CN 200910180529A CN 101673668 B CN101673668 B CN 101673668B
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Abstract
The invention discloses a method for polishing gallium nitride crystals, comprising the following steps: sticking gallium nitride wafers on a quartz plate; grinding the gallium nitride wafers stuck on the quartz plate by a grinder; heating up the polishing solution, irradiating the polished gallium nitride wafers by ultraviolet light and carrying out chemical mechanical polishing on the ground gallium nitride wafers by a polisher. In the method, based on the chemical mechanical polishing of the traditional gallium nitride wafers, the ultraviolet light is used for irradiating the wafers and a self-made water-bath heating system is simultaneously used for heating up the polishing solution, thus increasing the chemical reaction rate in the process of chemical mechanical polishing, and by adjusting the weight of the heavy objects, the physical removing effect and the chemical effect are balanced, thus not only solving the problem that the gallium nitride wafers are difficult to polish and increasing the removal rates of N surface and Ga surface, but also obtaining satisfactory shiny surfaces. The method features obviously lower cost and simple process implementation and effectively increases the polishing efficiency.
Description
Technical field
The present invention relates to the polished semiconductor field, particularly relate to a kind of method of polishing gallium nitride crystals.
Background technology
Third generation semi-conducting material gallium nitride has that energy gap is big, breakdown electric field is high, thermal conductivity is big, the electronics saturation drift velocity is high, particular performances such as dielectric constant is little, capability of resistance to radiation is strong, chemical stability height, and it has wide application prospect at opto-electronic device such as light demonstration, optical storage, optical detection and field of microelectronic devices such as high temperature, high-frequency high-power electronics.The GaN base device has not only obtained widely applying aspect civilian, has huge market potential, and militarily the major application prospect is arranged also, receives the very big attention of the various countries military.
In mid-term at the beginning of the nineties in last century, GaN base blue, purple light, the particularly breakthrough of P type doping techniques for all solid state panchromatic demonstration and white-light illuminating technology rapid development, lay the foundation.At present, high brightness GaN base is blue, green diode (LED) has formed high-tech industry, and the world market of GaN base LED in 2002 has reached 1,800,000,000 dollars, and with the speed increment in year 50%, market potential is huge.The breakthrough of the basic indigo plant of high-power, super brightness GaN, purple LED manufacturing technology, the revolution with triggering lighting source receives the attention of countries in the world, and research work is advanced by leaps and bounds, and makes rapid progress.In addition, the GaN material is also by wide LD (Laser disc, laser disc), UV (ultraviolet ray) detector, the HEMT aspects such as (High ElectronMobility Transistor, HEMTs) of being applied to.
The key issue that restriction GaN base device performance and reliability improve is the backing material that lacks high-flatness and high surface flatness.The growing method of GaN material mainly is MOCVD (Metal OrganicChemical Vapor Deposition, metal organic chemical vapor deposition) method and HVPE (Hydride vaporphase epitaxy, hydride gas-phase epitaxy) method at present.Gallium nitride film surface smoothness and roughness ratio with MOVCVD method growth are better, can aspect fabricate devices, directly use, but the mocvd method speed of growth are too slow, can only be used for growing film; And the HVPE method carries out gallium nitride single crystal and grows into more than the 200 μ m, and required growth time is long, and thickness is big; Situation in uneven thickness often occurs, and surface smoothness and roughness are all very big, can not directly be used to make device; Must polish, improve the evenness and the roughness on surface.So it is vital selecting a kind of good finishing method for use.
The hardness of gallium nitride material is big, and chemical stability is high, and any polishing fluid is all very little to its chemical corrosion effect, and mechanical polishing is generally adopted in the polishing of gallium nitride in the past, adopts the diamond polishing liquid of different model repeatedly to polish.Though use very thin diamond to carry out the surface that mechanical polishing can obtain light; Evenness and roughness are fine, but still have darker mechanical damage layer, draw the road even if wafer surface can't see; Through after the corrosion of extension furnace high-temperature, can find that much drawing appears again in the surface.There is human reactive ion etching method (RIE) that the Ga face of gallium nitride is handled recently,, obtains more even curface to remove surface damage.Yet such RIE technology is unsatisfactory, because because new damage has been introduced in ion bombardment again, and the surface is more irregular, and with contamination, this also must increase the oxygen plasma cleaning, makes technology more complicated.
Chemico-mechanical polishing (CMP, Chemical Mechanical Polishing) is that chemistry is removed and the coefficient result of mechanical lapping, is one of best approach that realizes at present various semi-conducting material global planarization; So the chemical-mechanical polishing mathing reason of research GaN material is absolutely necessary, but gallium nitride wafer tow sides different in kind, and the N surface chemistry is active high; KOH or the polishing of NaOH base polishing fluid; Be easy to remove surface damage and draw the road, obtain highly smooth polished surface, and the Ga face; With KOH or the polishing of NaOH base polishing fluid, basic not variation.Must manage to remove surface damage, obtain the Ga face of excellent polishing.Therefore, how improving the polishing efficiency of Ga face, obtain good polished surface, is problem demanding prompt solution.
Summary of the invention
The present invention provides a kind of effective surface quality of improving wafer, obtains the method for the polishing gallium nitride crystals of bright minute surface, has the not good problem of polishing gallium nitride crystals in order to solve in the prior art.
For reaching the foregoing invention purpose, the present invention provides a kind of method of polishing gallium nitride crystals, said method comprising the steps of:
Gallium nitride wafer is sticked on the quartz plate;
With grinder the gallium nitride wafer that sticks on the quartz plate is ground;
Be attached to polishing pad on the polishing disk, be pressed in the quartz plate that posts gallium nitride wafer on the polishing pad, ultraviolet light is seen through from the annular weight top, impinge upon on the gallium nitride wafer, polishing fluid is heated with ring-like weight; Start polishing machine, abrasive disk rotation and then drive gallium nitride wafer and the rotation of ring-like weight are polished; Wherein, the pressure of ring-like weight is 100-500g/cm
2
Wherein, gallium nitride wafer is sticked on the quartz plate, is specially:
Quartz plate is heated on heater, smears wax uniformly on it, be bonded at gallium nitride wafer on the wax by reality again, stop heating, treat that wax solidifies after, unnecessary wax is disposed, accomplish paster.
Wherein, said gallium nitride wafer is sticked on the central authorities of said quartz plate.
Wherein, with said gallium nitride wafer evenly stick on said quartz plate around, and keep the distance of 2mm at least with said quartz plate edge.
Wherein, said gallium nitride wafer being carried out abrasive method is: adopt the abrasive material of different-grain diameter that said gallium nitride wafer is repeatedly ground.
Wherein, said abrasive material cubic boron, carborundum, schmigel.
Wherein, saidly be finished to thick throwing, slightly throwing polishing fluid is that particle diameter is the Al of 80nm
2O
3Polishing fluid wherein adds 5% TCCA.
Wherein, after thick the throwing, also comprise thin throwing, it is the SiO of 25-26nm that the thin polishing fluid of throwing adopts particle diameter
2Polishing fluid wherein adds 5% H
2O
2
Wherein, the temperature of said polishing fluid is 30-90 ℃.
Beneficial effect of the present invention is following:
The present invention has used ultraviolet light that its wafer is shone on the basis of traditional gallium nitride wafer chemico-mechanical polishing, has used self-control water-bath heating system that polishing fluid is heated up simultaneously; Improved the chemical reaction rate in the CMP process; Through the adjusting of weight weight, make physical removal effect and chemical action reach balance again, not only solved the problem of the difficult polishing of gallium nitride; Improve N face and Ga face and removed speed, also obtained gratifying glossy surface.The inventive method cost is obviously lower, and process implementing is simple, and effectively raises polishing efficiency.
Description of drawings
Fig. 1 is the gallium nitride chemico-mechanical polishing sketch map of the embodiment of the invention;
Fig. 2 is that embodiment of the invention large scale gallium nitride wafer is pasted sketch map;
Fig. 3 is that embodiment of the invention small size gallium nitride wafer is pasted sketch map;
Fig. 4 is an embodiment of the invention water-bath heating system structural representation.
Wherein, 11: uviol lamp, 12: polishing fluid; 13: polishing pad; 14: polishing disk; 15: ring-like weight; 16: quartz plate; 17: gallium nitride wafer; 21: quartz plate; 22: large stretch of gallium nitride wafer; 31: the gallium nitride wafer of small pieces; 32: quartz plate; 41: heating tube; 42: the water-bath heating container; 43: polishing fluid; 44: thermocouple.
Embodiment
Below in conjunction with accompanying drawing and embodiment, the present invention is further elaborated.Should be appreciated that specific embodiment described herein only in order to explain the present invention, does not limit the present invention.
The method of the polishing gallium nitride crystals of present embodiment comprises the steps:
Steps A: gallium nitride wafer is sticked on the quartz plate with high temperature wax.
Step B: the gallium nitride wafer that sticks on the quartz plate is ground with grinder.
Step C: through the water-bath heating polishing fluid is heated up,, the gallium nitride wafer after grinding is carried out chemico-mechanical polishing with polishing machine with the wafer of UV-irradiation polishing.
Paster mode described in the steps A comprises large stretch of the stickup and the small pieces stickup.As shown in Figure 2, large stretch of GaN wafer 22 (>=2 inches) directly sticks on the central authorities of quartz plate 21; As shown in Figure 3, the gallium nitride wafer 31 of small pieces (as 10 * 10mm) stick on uniformly quartz plate 32 around, keep the distance of 2mm at least with the edge.
Ginding process described in the step B is to adopt the abrasive material (like a cube BC, SiC, schmigel etc.) of high rigidity different-grain diameter that gallium nitride wafer is repeatedly ground, and reduces the damage layer thickness of wafer surface.
Polishing described in the step C is divided into thick throwing to be carried out with smart two steps of throwing, and thick the throwing is to adopt the high rigidity polish, and essence is thrown and used the soft abrasive material.The temperature of heating polishing fluid is 30～90 ℃.
Be that example describes with 2 inches gallium nitride wafer single-sided polishings below.Shown in Figure 1 is the polishing gallium nitride crystals sketch map.Carry out the gallium nitride polishing and at first will carry out paster, exactly gallium nitride wafer is sticked on the quartz plate, quartz plate is heated on heater; Smear high temperature wax uniformly above that, be bonded at 2 inches wafers on the wax by real (stressed even for making in the follow-up work wafer, as to stick on wafer in the quartz plate in the heart) again; Stop the heating treating that wax solidifies after; Unnecessary wax is disposed, accomplished paster, shown in accompanying drawing 2.The purpose of unnecessary wax of going out is that wax unnecessary in follow-up grinding technics process may adsorb the bigger abrasive grain of particle diameter, so that produces unnecessary cut, reduces quality of finish.
After paster is accomplished, grind it, purpose is in order to remove big concavo-convex of plane of crystal in the tool marks that produce in the slicing processes or the crystal growing process, to improve the evenness of wafer.The present invention adopts high rigidity abrasive material schmigel to grind; Use granularity repeatedly to grind successively as the schmigel of w10, w7, w3.5, w1.5; Purpose is in the evenness that improves wafer, reduces the thickness of wafer surface affected layer, for follow-up glossing lays the first stone as far as possible.
As shown in Figure 1 wafer is polished.Carry out rough polishing earlier, polishing fluid 12 is the Al of 80nm for particle diameter
2O
3Polishing fluid wherein adds 5% oxidant TCCA.Be attached to polishing pad 13 on the polishing disk 14; Be pressed in the quartz plate 16 that posts gallium nitride wafer 17 on the polishing pad 13 with ring-like weight 15; Ultraviolet light 11 is seen through from the annular weight top, impinge upon on the gallium nitride wafer 17, heat polishing fluid with the water-bath heating system; Water-bath heating system structure is as shown in Figure 4, and heating tube 41 is with the liquid heat in the water-bath heating container 42; And then heating polishing fluid 43; Temperature through thermocouple 44 monitoring polishing fluids 43.Open the polishing machine power supply, abrasive disk rotation and then drive gallium nitride wafer 17 and 15 rotations of ring-like weight are polished.In this polishing process, can change removal speed through the quality of regulating ring-like weight 15, the contract polishing pad of ratio, high rigidity of our preferred lower pressure is if polishing pad is crossed and softly possibly caused the polished wafer limit of collapsing; Preferred pressure is 100-500g/cm
2, pressure is too for a short time to be made and removes speed and reduce, and pressure is excessive also can to make the polishing pad modification, causes that wafer produces the limit phenomenon of collapsing in the polishing process; The temperature of preferred polishing fluid is 30-90 ℃, the chemical action that temperature is too low to make oxidant too a little less than and pressure produce physical removal and can't reach balance; Polishing effect is bad; And the reduction polishing speed, the polishing fluid temperature is too high, and polishing pad and polishing machine are damaged; Among the present invention, but use the chemical reaction rate on UV-irradiation accelerated oxidation agent and gallium nitride wafer surface, the wafer surface roughness is reduced, and can improve polishing speed.
Adopt said method to carry out rough polishing about one hour, the wafer surface affected layer is further reduced, carry out finishing polish afterwards, it is the SiO of 25-26nm that polishing fluid adopts the soft particle diameter
2Polishing fluid wherein adds 5% H
2O
2Oxidant, the same rough polishing of other condition.Carry out finishing polish in about a hour again, can obtain the extremely low wafer surface of surface roughness.
Can find out by the foregoing description; The present invention has used ultraviolet light that its wafer is shone on the basis of traditional gallium nitride wafer chemico-mechanical polishing, has used self-control water-bath heating system that polishing fluid is heated up simultaneously; Improved the chemical reaction rate in the CMP process; Through the adjusting of weight weight, make physical removal effect and chemical action reach balance again, not only solved the problem of the difficult polishing of gallium nitride; Improve N face and Ga face and removed speed, also obtained gratifying glossy surface.The inventive method cost is obviously lower, and process implementing is simple, and effectively raises polishing efficiency.
Obviously, those skilled in the art can carry out various changes and modification to the present invention and not break away from the spirit and scope of the present invention.Like this, belong within the scope of claim of the present invention and equivalent technologies thereof if of the present invention these are revised with modification, then the present invention also is intended to comprise these changes and modification interior.
Claims (9)
1. the method for a polishing gallium nitride crystals is characterized in that, said method comprising the steps of:
Gallium nitride wafer is sticked on the quartz plate;
With grinder the gallium nitride wafer that sticks on the quartz plate is ground;
Be attached to polishing pad on the polishing disk, be pressed in the quartz plate that posts gallium nitride wafer on the polishing pad, ultraviolet light is seen through from the annular weight top, impinge upon on the gallium nitride wafer, polishing fluid is heated with ring-like weight; Start polishing machine, abrasive disk rotation and then drive gallium nitride wafer and the rotation of ring-like weight are polished; Wherein, the pressure of ring-like weight is 100-500g/cm
2
2. the method for polishing gallium nitride crystals as claimed in claim 1 is characterized in that, gallium nitride wafer is sticked on the quartz plate, is specially:
Quartz plate is heated on heater, smears wax uniformly on it, be bonded at gallium nitride wafer on the wax by reality again, stop heating, treat that wax solidifies after, unnecessary wax is disposed, accomplish paster.
3. the method for polishing gallium nitride crystals as claimed in claim 1 is characterized in that, said gallium nitride wafer is sticked on the central authorities of said quartz plate.
4. the method for polishing gallium nitride crystals as claimed in claim 1 is characterized in that, with said gallium nitride wafer evenly stick on said quartz plate around, and keep the distance of 2mm at least with said quartz plate edge.
5. the method for polishing gallium nitride crystals as claimed in claim 1 is characterized in that, said gallium nitride wafer is carried out abrasive method be:
Adopt the abrasive material of different-grain diameter that said gallium nitride wafer is repeatedly ground.
6. the method for polishing gallium nitride crystals as claimed in claim 5 is characterized in that, said abrasive material cubic boron, carborundum, schmigel.
7. the method for polishing gallium nitride crystals as claimed in claim 1 is characterized in that, saidly is finished to thick throwing, and slightly throwing polishing fluid is that particle diameter is the Al of 80nm
2O
3Polishing fluid wherein adds 5% TCCA.
8. the method for polishing gallium nitride crystals as claimed in claim 7 is characterized in that, after thick the throwing, also comprises thin throwing, and it is the SiO2 polishing fluid of 25-26nm that the thin polishing fluid of throwing adopts particle diameter, wherein adds 5% H2O2.
9. the method for polishing gallium nitride crystals as claimed in claim 1 is characterized in that, the temperature of said polishing fluid is 30-90 ℃.
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| CN2009101805295A CN101673668B (en) | 2009-10-19 | 2009-10-19 | Method for polishing gallium nitride crystals |
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| CN2009101805295A CN101673668B (en) | 2009-10-19 | 2009-10-19 | Method for polishing gallium nitride crystals |
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Families Citing this family (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102554750A (en) * | 2010-12-29 | 2012-07-11 | 北京有色金属研究总院 | Double-surface polishing method for gallium antimonide wafer |
| CN103182674A (en) * | 2011-12-30 | 2013-07-03 | 无锡华润上华科技有限公司 | WCMP (wolfram chemical mechanical polishing) grinding device and method for improving WCMP grinding rate |
| CN103639886A (en) * | 2013-11-29 | 2014-03-19 | 上海华力微电子有限公司 | Mechanical machine grinding device and method for W-CMP |
| CN106141900A (en) * | 2015-04-16 | 2016-11-23 | 东莞市中镓半导体科技有限公司 | A kind of method of high efficiency grinding and polishing GaN wafer |
| CN107263301B (en) * | 2017-06-26 | 2019-05-14 | 镓特半导体科技（上海）有限公司 | A kind of method of grinding-chemically mechanical polishing gallium nitride wafer piece |
| CN107641835B (en) * | 2017-10-23 | 2019-11-26 | 大连理工大学 | A kind of method of semiconductor wafer optical electro-chemistry mechanical polishing |
| CN107877352A (en) * | 2017-10-23 | 2018-04-06 | 大连理工大学 | Semiconductor wafer optical electro-chemistry mechanical polishing apparatus |
| CN108406451B (en) * | 2018-05-21 | 2024-05-14 | 浙江工业大学 | Spherical surface polishing and fine grinding device and method |
| WO2020119779A1 (en) * | 2018-12-14 | 2020-06-18 | 大连理工大学 | Semiconductor wafer photoelectrochemical mechanical polishing processing device and processing method |
| CN110640552B (en) * | 2019-09-12 | 2020-11-06 | 大连理工大学 | Processing method of easily-cleaved semiconductor crystal |
| CN112757150A (en) * | 2020-12-29 | 2021-05-07 | 南京航空航天大学 | Rapid polishing method of gallium nitride single crystal material for electronic device |
| CN113814887B (en) * | 2021-10-25 | 2023-01-24 | 广东省大湾区集成电路与系统应用研究院 | Chemical mechanical polishing equipment and method |
| CN114986384B (en) * | 2022-05-11 | 2024-04-12 | 宁夏盾源聚芯半导体科技股份有限公司 | Chemical mechanical polishing method for polysilicon ring |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1274949A (en) * | 1999-05-19 | 2000-11-29 | 因芬尼昂技术北美公司 | System for transfering polishing liquid when semiconductor wafer is chemimechanical polished |
| CN101081485A (en) * | 2006-05-31 | 2007-12-05 | 住友电气工业株式会社 | Surface treatment method, nitride crystal substrate, semiconductor device, and method of manufacturing and semiconductor device |
| CN101138833A (en) * | 2006-09-05 | 2008-03-12 | 住友电气工业株式会社 | Group iii nitride substrate and manufacturing method of group iii nitride substrate |
-
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- 2009-10-19 CN CN2009101805295A patent/CN101673668B/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1274949A (en) * | 1999-05-19 | 2000-11-29 | 因芬尼昂技术北美公司 | System for transfering polishing liquid when semiconductor wafer is chemimechanical polished |
| CN101081485A (en) * | 2006-05-31 | 2007-12-05 | 住友电气工业株式会社 | Surface treatment method, nitride crystal substrate, semiconductor device, and method of manufacturing and semiconductor device |
| CN101138833A (en) * | 2006-09-05 | 2008-03-12 | 住友电气工业株式会社 | Group iii nitride substrate and manufacturing method of group iii nitride substrate |
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