CN1951635A - Superfine grinding wheel for hard and crisp crystal substrate - Google Patents

Abstract

The invention discloses an ultra-precision grinding wheel for hard and brittle crystal substrates, belonging to the technical field of ultra-precision processing of hard and brittle crystal substrates, and relates to an ultra-precision grinding wheel for hard and brittle crystal substrates. The ultra-precision grinding wheel is made of a mating ring, a base ring, and a grinding layer. The grinding layer of the grinding wheel is composed of abrasives, binders, fillers and pores, and the fillers are pH regulators, oxidants and throwing aids. It consists of three parts. The base ring of the grinding wheel is assembled on the mating ring, and is fastened into one body by six uniformly distributed hexagon socket bolts. The material of the mating ring and the base ring is forged aluminum alloy; the grinding layer of the grinding wheel is hot-pressed or bonded on the base ring. The grinding removal rate of the grinding wheel is high; the grinding surface roughness is low; the hard and brittle crystal substrate has no surface/subsurface damage such as scratches, pits, micro-defects, micro-cracks, and dislocations; the cost of the grinding wheel is low.

Description

A kind of ultra-precision grinding wheel for hard and brittle crystal substrate

technical field

The invention belongs to the technical field of ultra-precision processing of hard and brittle crystal substrates, and relates to an ultra-precision grinding wheel for hard and brittle crystal substrates.

Background technique

With the rapid development of microelectronics and optoelectronics technology, the processing requirements for hard and brittle crystal substrates such as single crystal silicon, gallium arsenide, and sapphire are becoming more and more stringent. On the one hand, the processed substrates are required to have extremely high geometric precision such as parallelism and flatness; Micro-scratches, micro-defects, micro-cracks, dislocations and other defects and damage.

At present, the processing technology of crystal substrate mainly includes lapping, grinding, chemical etching and chemical mechanical polishing (CMP). Generally, the surface roughness of the crystal substrate is relatively high (Ra0.1-0.2 μm) after grinding with 6-8 μm abrasive grains, and the depth of the surface damage layer is more than 8 μm. Corrosion is mainly used to remove the damage of the grinding surface layer. Since the corrosion rate is difficult to control stably, it will inevitably affect the geometric accuracy and surface quality of the crystal substrate. In the end, chemical mechanical polishing (CMP) is mainly used to obtain a non-damaged surface with sub-nanometer roughness. However, chemical mechanical polishing has disadvantages such as difficult control of surface accuracy, high processing cost, low productivity, and difficult substrate cleaning. The method of ultra-precision grinding with fine-grained diamond (grain size 6-8 μm) grinding wheel has significant advantages such as high processing efficiency, high processing accuracy, low processing cost, and high degree of automation. It gradually replaces grinding in ultra-precision processing of hard and brittle crystals. And corrosion process, is considered to be the most potential processing technology. However, the use of fine-grained diamond grinding wheels will also produce scratches, microcracks, lattice distortions, dislocations and other damage on the surface of the crystal substrate, and the depth of the damaged layer can reach 1-2 μm. In order to eliminate the grinding damage layer, it is necessary to obtain an ultra-smooth and damage-free surface through subsequent CMP, which will undoubtedly increase the processing time and cost. Especially in the ultra-precision grinding process of ultra-thin crystal substrates (such as the back grinding and thinning of silicon wafers), the damage of the grinding surface layer can easily cause the chipping of the substrate. Therefore, reducing and eliminating the damage of the grinding surface layer is an urgent problem to be solved in the ultra-precision grinding of hard and brittle substrates. In the ultra-precision grinding process of hard and brittle substrates, the characteristic parameters of the grinding wheel are the main factors affecting the damage of the grinding surface layer. The study of ultra-precision grinding wheels with new structures and formulas is the key to achieving ultra-precision and low-cost grinding of hard and brittle crystal substrates with low damage and no damage. The application in the field of ultra-precision machining is of great significance.

Contents of the invention

The purpose of the present invention is to utilize existing fine-grained diamond grinding wheel to grind hard and brittle crystal substrate surface/subsurface damage and defect, and the problem such as high cost, thereby provides a kind of for hard and brittle crystal substrate grinding damage layer is small , The low-cost grinding wheel makes the hard and brittle crystal substrate free of scratches, pits, and micro-cracks, reduces the chipping of the grinding surface of the substrate, and improves the quality.

The technical scheme adopted in the present invention is as follows: a kind of hard and brittle crystal substrate ultra-precision grinding wheel, the grinding layer IV of emery wheel is made up of abrasive material 1, binding agent 2, filling material 3 and air hole 4; Ultra-precision grinding wheel is made up of It is made of matching ring I, matrix ring II and grinding layer IV; the matrix ring II of the grinding wheel is assembled on the mating ring I, and is fastened into one body by six uniformly distributed hexagon socket head bolts III, and the mating ring I and matrix ring II The material is forged aluminum alloy; the grinding layer IV of the grinding wheel is hot-pressed or bonded on the base ring II, and the hardness of the abrasive material 1 is lower than or equivalent to that of the hard and brittle crystal substrate, and it can be produced with the surface of the crystal substrate during the grinding process. Physical and chemical effects, the particle size of the abrasive 1 is selected as 1-3 μm, and the material is selected from ceria, silicon dioxide, barium carbonate or calcium carbonate; the filler 3 in the grinding layer IV of the grinding wheel consists of a pH regulator, an oxidant and a throwing aid It consists of three parts; the ingredients in the grinding layer IV are distributed by weight percentage: the weight of the abrasive material 1 accounts for 35-40%; The throwing agent accounts for 5-10% by weight, and the rest is binder 2.

The PH value adjusting agent in the filler 3 in the grinding wheel grinding layer IV is selected from strong acid and weak base salts or strong base and weak salt compounds: sodium carbonate, potassium carbonate or sodium bicarbonate; the oxidant in it is selected from sodium peroxide and sodium hypochlorite , potassium permanganate or calcium peroxide; among them, graphite powder or talcum powder is used as the throwing aid.

The invention has the following obvious effects: the grinding removal rate of the grinding wheel is high; the grinding surface roughness is low; the hard and brittle crystal substrate has no surface/subsurface damage such as scratches, pits, micro-defects, micro-cracks, and dislocations; the cost of the grinding wheel Low.

Description of drawings

Fig. 1 is a sectional view of the grinding wheel, wherein: I-cooperating ring, II-substrate ring, III-hexagon socket bolt, IV-grinding layer. Figure 2 is the left view of the grinding wheel, and Figure 3 is a schematic diagram of the composition of the grinding layer, in which: 1-abrasive, 2-bonding agent, 3-filler, 4-pore

Detailed ways

The specific implementation of the present invention will be described in detail in conjunction with the accompanying drawings. Configure the batching of 100g emery wheel grinding layer IV: take weight and be 40g cerium oxide abrasive, the particle diameter of abrasive grain is 3 μm; Take weight and be 20g sodium carbonate as pH regulator; Take weight and be that 10g sodium peroxide is as oxidant; Weigh 10g of talcum powder as a throwing aid; weigh 20g of phenolic resin as a binder; the PH value regulator in the grinding wheel filler 3 can provide an acidic or alkaline processing environment during the grinding process. Sodium carbonate. The oxidizing agent in the grinding wheel filler 3 can oxidize the surface of the crystal substrate during the grinding process to improve the material removal rate, and sodium peroxide is selected as the oxidizing agent. In the grinding process, in order to increase the polishing performance of the grinding wheel, reduce the friction between the grinding wheel and the crystal substrate, reduce the surface scratches of the crystal substrate, and promote the formation of an ultra-smooth surface, talc powder is selected as the throwing aid. After mixing the above ingredients evenly, hot press the grinding layer IV onto the base ring II by means of hot pressing, then assemble the base ring II onto the mating ring I, and fasten them with six evenly distributed hexagon socket head bolts III Assembled into one. Then carry out the dynamic balance of the grinding wheel, and adjust the end face of the base ring II to increase or decrease the weight; after the grinding layer IV of the grinding wheel is worn out, only the base ring II needs to be replaced, while the high-precision, high-cost base ring I can be reused . After adjusting the dynamic balance on the end face of the base ring, the single crystal silicon wafer was used as a sample for grinding test.

No surface damage such as micro-scratches, pits, and micro-defects was found in the SEM observation of the surface of the single-crystal silicon substrate after grinding. The surface roughness Ra measured by a three-dimensional surface profiler is less than 0.8nm. No micro-cracks and dislocations were found on the sub-surface detected by the cross-sectional transmission electron microscope, the quality of the processed surface/sub-surface is better than that of the existing grinding wheel grinding, and the chemical mechanical polishing processing effect is achieved. The material removal rate of grinding single crystal silicon substrate is more than 1 μm/min, which is higher than the removal rate of chemical mechanical polishing of 0.1-0.2 μm/min.

Claims (2)

1. An ultra-precision grinding wheel for hard and brittle crystal substrates, the grinding layer [IV] of the grinding wheel is composed of abrasive [1], bonding agent [2], filler [3] and pores [4], its characteristics Yes, the ultra-precision grinding wheel consists of a mating ring [I], a base ring [II] and a grinding layer [IV]; the base ring [II] of the grinding wheel is assembled on the mating ring [I], and consists of six evenly distributed The inner hexagon bolt [III] is fastened into one body, the material of the mating ring [I] and the base ring [II] is forged aluminum alloy; the grinding layer [IV] of the grinding wheel is hot-pressed or bonded on the base ring [II], and the abrasive [1] The particle size is selected as 1-3 μm, the hardness of the abrasive [1] is lower than or equal to that of the hard and brittle crystal substrate, and it can produce physical and chemical interactions with the surface of the crystal substrate during the grinding process. Silicon oxide, barium carbonate or calcium carbonate; the filler [3] in the grinding layer [IV] of the grinding wheel is composed of three parts: pH regulator, oxidizer and throwing aid; each component is by weight in the grinding layer [IV] The percentage distribution is: abrasive [1] 35-40%; PH regulator 15-20% in filler [3], oxidant 5-10% and throwing aid 5-10%, and the rest is binder [2] . 2. a kind of hard and brittle crystal substrate ultra-precision grinding wheel as claimed in claim 1, it is characterized in that, the pH value regulator in the filler [3] in the emery wheel grinding layer [IV], selects strong acid weak Alkali salt or strong base and weak salt compound: sodium carbonate, potassium carbonate or sodium bicarbonate; oxidizing agent is sodium peroxide, sodium hypochlorite, potassium permanganate or calcium peroxide; throwing aid is graphite powder or talcum powder.