CN101780662A - Soft abrasive grinding wheel of ultra-precision and low-damage ground silicon wafer - Google Patents

Abstract

The invention belongs to the ultra precision processing field of hard and brittle crystal materials and relates to a soft abrasive grinding wheel of an ultra-precision and low-damage ground silicon wafer. The soft abrasive grinding wheel comprises abase body and an abrasive layer. A grinding layer consists of abrasives, additive, binder and an air hole, wherein the abrasives are MgO abrasives which has the hardness lower than single crystal silicon and can generate chemical reaction with the single crystal silicon, the additive consists of CaO, Na2CO3 and NaHCO3 which can directly generate the chemical reaction with the single crystal silicon or supply promotion environment to the chemical reaction of the MgO abrasives and the single crystal silicon, and the grinding wheel abrasive layer is integrally hot pressed or adhered in a blocking way to the base body. The soft abrasive grinding wheel has stable grinding performance without usually trimming the grinding wheel and high material removal rate, the surface layer quality of the ground silicon wafer can achieve the effect of CMP processing silicon wafer, and the silicon wafer surface can not have the phenomenon of grinding burn.

Description

The soft abrasive grinding wheel of ultra-precise low-damage grinding silicon chip

Technical field

The invention belongs to hard and brittle crystal materials ultraprecise manufacture field, relate to a kind of soft abrasive grinding wheel of ultra-precise low-damage grinding silicon chip.

Background technology

Silicon chip is the semiconductor substrate materials of extensive use in the ic manufacturing process, and the superficial layer quality of silicon chip directly has influence on performance, yield rate and the service life of semiconductor devices.Along with the development of integrated circuit technique, the superficial layer quality requirement of silicon chip is improved day by day.In the integrated circuit fabrication process process, superfine grinding is one of important technological method for processing of large-sized silicon wafers leveling processing and graph silicon chip thinning back side.Yet the challenge of the maximum that method for grinding faces is exactly the damage of surface layer problem of silicon chip after the grinding, needs to increase subsequent technique and eliminates damage.How reducing as much as possible even eliminating the damage of silicon chip grinding skin layer is the target that the researcher constantly explores in this field always.At present, mainly contain two technological approaches: the one, reduce the granularity of skive, can reduce grinding damage layer depth and surface roughness effectively.But, adopt the material removing rate of ultra-fine granularity diamond wheel grinding silicon chip low, also exist the emery wheel self-sharpening poor, be easy to produce the grinding burn problem.Secondly, by reducing the cutting depth of skive abrasive particle, make the cutting depth of abrasive particle be reduced to the critical cutting depth of silicon chip ductility territory grinding, can avoid grinding silicon chip surface/surface, Asia to form crackle, reduce grinding damage effectively, but the silicon chip surface of ductility territory grinding still exists dislocation, amorphous equivalent damage form.

In exploring the process that reduces silicon chip grinding damage method, the chemical machinery grinding new method of soft abrasive grinding wheel has appearred adopting in recent years, and the method is considered to take into account the advantage of superfine grinding and chemically mechanical polishing, is very potential technological method for processing.Although confirmed at present to utilize silicon chip surface after the grinding of soft abrasive grinding wheel chemical machinery can reach the processing effect of CMP, soft abrasive grinding wheel mainly adopts CeO at present ₂, SiO ₂Abrasive material, grinding performance instability in the grinding silicon chip process, material removing rate is low, and silicon chip surface often produces grinding burn and cut.Therefore, studying novel soft abrasive grinding wheel, is the key that realizes the grinding of silicon chip ultra-precise low-damage, and the soft abrasive grinding wheel grinding technique is significant in the application of silicon chip ultraprecise manufacture field for promoting.

Summary of the invention

The technical problem to be solved in the present invention provides a kind of soft abrasive grinding wheel of the ultra-precise low-damage grinding silicon chip based on novel structural constituent prescription, solves the diamond wheel grinding silicon chip and has surface/sub-surface damage and defective, and adopt CeO at present ₂, SiO ₂There is the grinding performance instability in soft abrasive grinding wheel in abrasive material, and material removing rate is low, and grinding burn often appears in silicon chip surface, and the time problems such as grinding cut appearance are arranged.

The technical solution used in the present invention is a kind of soft abrasive grinding wheel of ultra-precise low-damage grinding silicon chip, and this emery wheel is made up of grinding wheel base body and abrasive material, and the material of matrix is an aluminium alloy, and abrasive material adopts integral heat pressure or resin glue to be bonded on the grinding wheel base body.It is characterized in that: the abrasive material of emery wheel is made up of abrasive material, additive, bond and pore.Wherein, the hardness ratio monocrystalline silicon of abrasive material is low, and can be in grinding process and silicon chip surface generation chemical action; Additive not only can improve the particular characteristic of soft abrasive grinding wheel, as emery wheel hardness, and heat resistance, the curing performance and the porosity etc. can also be directly and monocrystalline silicon generation chemical reaction or processing environment can be provided for the chemical reaction of abrasive material and monocrystalline silicon; The shared percent by volume of each composition is in the abrasive material: abrasive material is 40-45%; Additive is 30-35%; Bond is 15-20%; Pore is 5-10%; Each raw material percent by volume sum is 100%; Wherein, it is MgO abrasive material more than 98% that abrasive material is selected purity for use, and size distribution is 2-7 μ m; Additive is by CaO, Na ₂CO ₃And NaHCO ₃Form; Bond is a hear resistance resinoid bond preferably.

The present invention has following obvious effects: the grinding performance of MgO soft abrasive grinding wheel is stable, does not need frequent trimming wheel in the grinding silicon chip process; The surface roughness of grinding silicon chip is than CeO ₂, SiO ₂Soft abrasive grinding wheel is lower, and material removing rate is higher; The grinding silicon chip does not grind superficial layer defectives such as line, pit, orange peel, microscopic defect point, micro-crack, dislocation, can reach the level of CMP processing silicon chip; The phenomenon of grinding burn can not appear in silicon chip surface.

Description of drawings

Accompanying drawing 1 is the soft abrasive grinding wheel structure chart, wherein: 1-grinding wheel base body, 2-abrasive material.

The specific embodiment

Describe concrete enforcement of the present invention in detail with technical scheme in conjunction with the accompanying drawings.Consider the requirement of soft abrasive grinding wheel manufacturing cost, technological feasibility and emery wheel continuous grinding, abrasive material 2 is made the arc abrading block, is bonded on the grinding wheel base body 1 with certain spacing combination, forms the profile of tooth grinding wheel structure, as shown in Figure 1.The external diameter of engineered abrasives layer 2, the facewidth and tooth depth are respectively

350mm, 7.5mm and 7mm, the cumulative volume that calculates abrasive material is 56.5cm ³According to the batching of the emery wheel abrasive material volume configuration abrasive material that designs, each composition volume content is: MgO abrasive material 40%; CaO additive 10%; Na ₂CO ₃Additive 20%; NaHCO ₃Additive 5%; Modified phenolic resin binder 20%.With above batch mixes evenly after, adopt hot pressing mode that batching is pressed into the arc abrading block, use epoxy resin that the arc abrasive material is bonded in grinding wheel base body then, proofread and correct the dynamic balancing of emery wheel at last, increase weight or loss of weight is adjusted the computing ballance correction of emery wheel by end face, reach in the scope of permission until the amount of unbalance of emery wheel to grinding wheel base body.After proofreading and correct the dynamic balancing of emery wheel, emery wheel is installed on the VG MK II ultraprecise grinding machine carries out the semi-conductor silicon chip grinding test.

Embodiment: the grinding exemplar is the monocrystalline silicon piece through #600 skive corase grind, and the speed of mainshaft is 1500r/min, and rotating speed of table is 119r/min, and feed speed is 3 μ m/min, and the grinding time is 15min, and control mode is manually control.The material removing rate of MgO soft abrasive grinding wheel grinding silicon chip is 2.6 μ m/min, far above CeO ₂, SiO ₂The material removing rate of buffing material, the silicon chip surface after the grinding are not found blemish such as mill line, pit, orange peel, microscopic defect point through SEM (SEM) observation.The Newview 5022 type 3D surface profilers of employing U.S. ZYGO company detect the silicon chip surface roughness after the grinding, and area of detection is 71 * 53 μ m ², surface roughness Ra is 0.45nm, PV is 4.56nm.The sub-surface damage defective and the lesion depths of silicon chip are not found dislocation and micro-crack after employing cross section transmission electron microscopy (Cross-TEM) the detection grinding, have only the amorphous layer of 10nm, are much better than skive and existing C eO ₂, SiO ₂Soft abrasive grinding wheel has reached the processing effect of CMP.Simultaneously, in the grinding silicon chip process, the grinding performance of MgO soft abrasive grinding wheel is stable, does not need in the grinding process often emery wheel to be repaired, and the phenomenon of silicon chip surface grinding burn do not occur.

Claims (1)

1. the soft abrasive grinding wheel of a ultra-precise low-damage grinding silicon chip, the abrasive material of emery wheel is made up of abrasive material, additive, bond and pore, it is characterized in that, the emery wheel abrasive material is that hardness is lower than monocrystalline silicon and can be in grinding process and the MgO abrasive material of silicon chip surface generation chemical reaction, abrasive material purity is more than 98%, and size distribution is 2-7 μ m; The emery wheel additive is CaO, Na ₂CO ₃And NaHCO ₃Grinding wheel bond is a resinoid bond; The shared percent by volume of each composition is in the emery wheel abrasive material: abrasive material 40-45%; Additive 30-35%; Binding agent 15-20%; Pore 5-10%, each composition percent by volume sum is 100%.

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