1. A polishing pad comprising abrasive grains (5), a solvent (4), and a base material (2) having a fibrous structure (3); the abrasive particles (5) are uniformly suspended in the solvent (4); the solvent (4) and the abrasive particles (5) are filled in the voids of the base material (2), and the solvent (4) comprises a material having dilatant fluid properties.

2. The polishing pad according to claim 1, wherein the base (2) comprises a nonwoven fabric and/or a polyurethane resin.

3. The polishing pad according to claim 1, wherein the density of the base material (2) is less than 0.4g/cm³And the thickness is less than or equal to 10 mm.

4. The polishing pad of claim 1, wherein: the abrasive particles (4) comprise any one of diamond, silicon carbide, aluminum oxide and boron nitride, the Mohs hardness is more than or equal to 8, and the diameter is 0.5-3 mu m.

5. The polishing pad of claim 1, wherein the material having dilatant fluid characteristics comprises at least one of a silicon-based polymer material, an organic polymer material, and an organosilicone material.

6. The polishing pad of claim 1, wherein the material having dilatant fluid characteristics comprises any one of a hydroxyl terminated silicone resin, a phenyl hydrogen silicone oil, a methyldimethoxysilane resin, an isoflavone gel, and a polyurethane resin.

7. The polishing pad according to claim 1, wherein the solvent (4) additive comprises at least one of an active agent, an oxidizing agent, a dispersing agent;

preferably, the additive is 0.1-1% by weight of the solvent;

preferably, the additive comprises at least one of an acid, a base, a salt metal oxide, a non-metal oxide.

8. A method for preparing a polishing pad, comprising:

uniformly suspending the abrasive grains (5) in the solvent (4) by mixing;

filling the abrasive particles (5) and the solvent (4) into the interior of the base material (2) having a fibrous structure to fill the voids of the base material (2);

increasing the viscosity of the solvent (4) in a heating mode or a vibration friction mode to enable the solvent (4) to be semi-fixed in the base material (2);

wherein the solvent (4) is composed of a material having dilatant fluid properties.

9. The method for producing a polishing pad according to claim 8, wherein the abrasive grains (5) and the solvent (4) are filled into the voids of the base material (2) having a fibrous structure by infiltration.

10. The method as claimed in claim 8, wherein the heating is performed at a constant temperature of 100-400 ℃.

Background

The SiC, GaN, sapphire, GaAs (gallium arsenide) and other semiconductor substrate materials can be widely applied to the advanced scientific and technological fields of new energy automobiles, high-power electric appliances, 5G communication networks, aerospace and the like. Due to the excellent electronic characteristics of the material, the electronic device prepared from the material has the characteristics of small volume and low loss, and can realize high-power output; the loss of the switching current is saved by more than 75%; is expected to comprehensively replace silicon-based semiconductors in the fields of high power and high frequency.

However, while the requirements for high efficiency, miniaturization and low loss of semiconductor electronic devices are increasing, the requirements for processing and manufacturing of the devices are also increasing, and particularly, the grinding and polishing of the surface of a semiconductor substrate requires high quality and no damage on the surface; on the other hand, high efficiency and low cost are required. However, the existing semiconductor material has extremely high hardness and extremely stable physical and chemical property liquid, and belongs to hard and brittle difficult-to-process materials (hereinafter, difficult-to-process materials), so that the efficiency of grinding and polishing is extremely low. The current adopted process mainly comprises strong oxidant synergistic grinding, diamond sand disc grinding, plasma erosion grinding and the like. The strong oxidant synergistic grinding belongs to the corrosion effect of the strong oxidant added on the basis of the traditional grinding, has better processing efficiency and surface quality, but the strong oxidant can damage equipment to a certain extent; the grinding of the diamond abrasive disc greatly improves the processing efficiency, but the quality of a damaged layer and the surface is poor, so that the subsequent polishing process is greatly burdened; the plasma erosion grinding has good processing efficiency and surface quality, but the equipment is expensive and complex to operate, harmful gas is generated, and the large-scale industrial production is not facilitated.

Therefore, achieving high-quality, high-efficiency, low-cost polishing of semiconductor materials difficult to process has become an important issue in the field of ultra-precision processing, and is a major research focus in the global semiconductor industry. In summary, there are some places where the existing polishing technology for semiconductor materials difficult to process needs to be updated and improved, and the market demand cannot be met. A novel grinding process method which can realize higher processing efficiency and processing quality and has low cost and environmental protection is urgently needed.

Disclosure of Invention

The invention aims to provide a grinding pad which can improve the grinding efficiency of hard and brittle materials and reduce the surface damage of the materials; meanwhile, the method has the advantages of low cost and no pollution.

In order to achieve the above object, a first aspect of the present invention provides a polishing pad comprising abrasive grains, a solvent, and a base material having a fibrous structure; the abrasive particles are uniformly suspended in the solvent; the solvent and the abrasive particles are filled in the voids of the base material, and the solvent is composed of a material having dilatant fluid characteristics.

The solvent is made of a material with the characteristic of dilatancy fluid, the abrasive particles can be uniformly suspended in the solvent, and when the solvent is subjected to a changing external force, surface molecules of the solvent are condensed, the damping coefficient is increased, and clamping force is generated on the abrasive particles on a stress surface, so that the friction force and the cutting capability of the abrasive particles are greatly improved; when the external force applied to the solvent disappears, the surface molecules are removed from condensation, the fluidity is recovered, the clamping force applied to the abrasive particles disappears immediately, and the abrasive particles can be instantly recovered to a suspension state.

Compared with the prior art, the technical scheme of the invention can control the increase and decrease of the clamping force of the abrasive particles by enabling the solvent to respond to the shearing force in the grinding process, combines the advantages of fixed abrasive particle grinding and free abrasive particle grinding, improves the processing efficiency and simultaneously reduces the damage to the surface of the workpiece.

Further, the base material includes a non-woven fabric and/or a polyurethane resin.

Further, the density of the substrate is less than 0.4g/cm3, and the thickness is less than or equal to 10 mm.

Further, the abrasive particles comprise any one of diamond, silicon carbide, aluminum oxide and boron nitride, the Mohs hardness is more than or equal to 8, and the diameter is 0.5-3 mu m.

Further, the material with the dilatancy fluid characteristic at least comprises one of a silicon-based polymer material, an organic polymer material and an organosilicone resin material.

Further, the material having the dilatant fluid characteristic includes any one of hydroxyl-terminated siloxane resin, phenyl hydrogen-containing silicone oil, methyldimethoxysilane resin, isoflavone gel, and urethane resin.

Further, the solvent additive, the additive comprising at least one of an active agent, an oxidizing agent, a dispersing agent.

Preferably, the additive comprises at least one of an acid, a base, a salt metal oxide, a non-metal oxide;

preferably, the additive is present in an amount of 0.1 to 1% by weight of the solvent.

The second invention provides a method for preparing a polishing pad, comprising the following steps:

uniformly suspending abrasive particles in a solvent by mixing;

filling the abrasive particles and the solvent into the interior of a substrate having a fibrous structure to fill voids of the substrate;

increasing the viscosity of the solvent in a heating mode or a vibration friction mode to semi-fix the solvent in the base material;

wherein the solvent is comprised of a material having dilatant fluid properties.

According to the grinding pad prepared by the method, the abrasive particles can be uniformly suspended in the solvent, and when the solvent is subjected to a change external force, surface molecules of the solvent are condensed, the damping coefficient is increased, and clamping force is generated on the abrasive particles on a stress surface, so that the friction force and the cutting capacity of the abrasive particles are greatly improved; when the external force applied to the solvent disappears, the surface molecules are removed from condensation, the fluidity is recovered, the clamping force applied to the abrasive particles disappears immediately, and the abrasive particles can be instantly recovered to a suspension state. Compared with the prior art, the technical scheme of the invention can control the increase and decrease of the clamping force of the abrasive particles by enabling the solvent to respond to the shearing force in the grinding process, integrates the advantages of fixed abrasive particle grinding and free abrasive particle grinding, improves the grinding efficiency of hard and brittle materials, reduces the surface damage of the materials, and has the advantages of low cost and no pollution.

Further, the abrasive grains and the solvent are filled into the voids of the base material having a fibrous structure by means of infiltration.

Further, the heating mode is constant temperature heating, and the heating temperature is 100-400 ℃.

Additional features and advantages of the invention will be set forth in the detailed description which follows.

Drawings

FIG. 1 is a schematic diagram of a polishing pad according to one embodiment of the present invention;

FIG. 2 shows example 1 of the present invention;

FIG. 3 is example 2 of the present invention;

FIG. 4 shows example 3 of the present invention;

FIG. 5 shows example 4 of the present invention;

FIG. 6 shows example 5 of the present invention.

Description of the reference numerals

1-a workpiece to be ground; 2-a substrate; 3-a fibrous structure; 4-a solvent; 5-abrasive grains.

Detailed Description

The following describes in detail specific embodiments of the present invention. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

In the present invention, the use of the terms of orientation such as "upper and lower" in the case where no description is made to the contrary generally means the orientation in the assembled and used state. "inner and outer" refer to the inner and outer contours of the respective component itself.

It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged under appropriate circumstances in order to facilitate the description of the embodiments of the invention herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

In a first aspect, the present invention provides a polishing pad, as shown in fig. 1, comprising abrasive particles 5, a solvent 4, and a base material 2 having a fibrous structure 3; the abrasive particles 5 can be uniformly suspended in the solvent 4; the solvent 4 and the abrasive grains 5 are filled in the voids of the base material 2, and the solvent 4 is made of a material having dilatant fluid properties.

Since the abrasive particles 5 are suspended in a solvent, the solvent 4 is composed of a material having dilatant fluid properties. When the solvent 4 is subjected to a changing external force, surface molecules of the solvent are condensed, the damping coefficient is increased, and a clamping force is generated on the abrasive particles 5 on the stress surface, so that the friction force and the cutting capacity of the abrasive particles 5 are greatly improved; when the external force applied to the solvent 4 disappears, the surface molecules are not condensed, the fluidity is recovered, the clamping force applied to the abrasive particles 5 disappears immediately, and the abrasive particles can be instantly recovered to a suspension state.

Compared with the prior art, the technical scheme of the invention can control the increase and decrease of the clamping force of the abrasive particles 5 by enabling the solvent 4 to respond to the shearing force in the grinding process, combines the advantages of fixed abrasive particle grinding and free abrasive particle grinding, improves the grinding efficiency of hard and brittle materials, reduces the surface damage of the materials, and has the advantages of low cost and no pollution.

The abrasive particles 5 are made of high-hardness micro-nano particles. Preferably, any one or a mixture of more of diamond, cubic boron nitride, boron carbide, silicon carbide, aluminum oxide, cerium oxide and manganese oxide is selected, and further preferably, any one or a mixture of more of diamond, carborundum, corundum and aluminum oxide is selected; the diameter range of the abrasive particles 5 is 0.5-3 mu m, and the Mohs hardness is more than or equal to 8.

Because non-woven fabrics and polyurethane resin have certain grinding ability, can improve grinding efficiency, non-woven fabrics and/or polyurethane resin are chooseed for use to substrate 2. Further, the density of the substrate 2 is less than 0.4g/cm3, and the thickness is less than or equal to 10 mm.

In order to enhance the chemical action generated on the surface of the grinded material, the generation of surface damage layer and scratch is reduced. Adding additives such as an active agent, an oxidizing agent or a dispersing agent and the like into the solvent 4; further, the additive can be acid, alkali, salt metal oxide, non-metal oxide or a mixture of the above materials; preferably, the additive is present in an amount of 0.1 to 1% by weight of the solvent.

In an alternative embodiment, the material with dilatant fluid characteristics comprises at least one of a silicon-based polymeric material, an organic polymeric material, and an organosilicone material. Preferably, any one of hydroxyl-terminated siloxane resin, phenyl hydrogen-containing silicone oil, methyldimethoxysilane resin, isoflavone gel and polyurethane resin is selected.

In another alternative embodiment, the solvent 4 comprises at least one of a resin having swelling properties, a starch composition having swelling properties, and inorganic particles having swelling properties.

The second invention provides a method for preparing a polishing pad, comprising the following steps:

mixing the abrasive particles 5 with the solvent 4; uniformly suspending abrasive grains 5 in a solvent 4 by mixing; preferably, the mixing ratio of the abrasive grains 5 and the solvent 4 is 1: 9-1: 4;

filling the abrasive particles 5 and the solvent 4 into the inside of the base material 2 having a fibrous structure to fill the voids of the base material 2; the fibrous structure 3 forms the skeleton of the foundation. The abrasive particles 5 and the solvent 4 can be filled into the gaps of the substrate 2 with the fibrous structure 3 in a penetration manner;

increasing the viscosity of the solvent 4 by a heating mode or a vibration friction mode, so that the solvent 4 is semi-fixed in the base material 2; wherein the heating mode is constant temperature heating, and the heating temperature is 100-400 ℃.

The solvent 4 is made of a material having dilatant fluid properties.

According to the grinding pad prepared by the method, the abrasive particles 5 can be uniformly suspended in the solvent 4, and when the solvent 4 is subjected to a changing external force, surface molecules of the solvent are condensed, the damping coefficient is increased, clamping force is generated on the abrasive particles 5 on a stress surface, and the friction force and the cutting capacity of the abrasive particles 5 are greatly improved; when the external force applied to the solvent 4 disappears, the surface molecules are not condensed, the fluidity is recovered, the clamping force applied to the abrasive particles 5 disappears immediately, and the abrasive particles can be instantly recovered to a suspension state.

Compared with the prior art, the technical scheme of the invention can control the increase and decrease of the clamping force of the abrasive particles 5 by enabling the solvent 4 to respond to the shearing force in the grinding process, combines the advantages of fixed abrasive particle grinding and free abrasive particle grinding, improves the processing efficiency and simultaneously reduces the damage to the surface of the workpiece.

In actual polishing, the relative motion mode between the material 1 to be polished and the polishing pad may be circular rotation motion, linear reciprocating motion or a composite motion of the two motions, and may be selected according to the requirements of the polishing material characteristics, shape characteristics, surface characteristic polishing rate, polishing quality, etc.

The technical solutions of the present invention will be described in further detail below with reference to examples, but it should be noted that the present invention is not limited to these examples.

Example 1

As shown in fig. 2, a solvent 4 was used as hydroxypropyl-terminated polydimethylsiloxane, diamond abrasive grains having a grain size of 1 μm were added as abrasive grains 5, and after uniform mixing, the mixture was infiltrated into a nonwoven fabric polishing pad, and the nonwoven fabric polishing pad was heated at 300 ℃ for 2 hours to prepare a polishing pad. The material to be polished was a 2-inch SiC substrate. The milling conditions are listed in table 1 below:

TABLE 1 grinding conditions

Ground material	SiC substrate (2 inch)
		Grinding pressure	180g/cm2
Polishing pad	The invention provides a polishing pad
		Abrasive grain	20 wt% Diamond (1 micron)
Dilatant fluid material	Hydroxypropyl terminated polydimethylsiloxanes

By using the grinding pad, the SiC substrate is ground for 1 hour under different rotating speed conditions, and the efficiency of removing the material is greatly improved when the rotating speed of the grinding disc is continuously improved. It can be seen that the increase in the speed causes an increase in the shearing force, which promotes the condensation of the molecules on the surface of the solvent 4, increases the damping coefficient, increases the holding force of the abrasive grains, and thus increases the number of revolutions, which can satisfy the high-efficiency polishing of the SiC substrate.

Example 2

As shown in fig. 3, a solvent 4 was used as hydroxypropyl-terminated polydimethylsiloxane, diamond abrasive grains having a grain size of 1 μm were added as abrasive grains 5, and after uniform mixing, the mixture was infiltrated into a nonwoven fabric polishing pad, and the nonwoven fabric polishing pad was heated at 300 ℃ for 2 hours to prepare a polishing pad. The material to be polished was a 2-inch SiC substrate. The following table 2 lists the milling conditions:

TABLE 2 grinding conditions

Ground material	SiC substrate (2 inch)
		Grinding speed	120r/min
Polishing pad	The invention provides a polishing pad
		Abrasive grain	20 wt% Diamond (1 micron)
Dilatant fluid material	Hydroxypropyl terminated polydimethylsiloxanes

By using the polishing pad, the SiC substrate was polished for 1 hour under different pressure conditions, and it was found that the material removal efficiency was greatly improved when the processing pressure was continuously increased. As a result, the shearing force increases due to the increase in pressure, the surface molecules of the solvent 4 are promoted to condense, the damping coefficient increases, and the holding force of the abrasive grains increases, so that the SiC substrate can be efficiently polished at an increased rotation speed.

Example 3

As shown in fig. 4, a solvent 4 was used as hydroxypropyl-terminated polydimethylsiloxane, diamond abrasive grains having particle diameters of 0.5 micrometers, 1 micrometer, 3 micrometers, and 5 micrometers were added as abrasive grains 5, and after uniform mixing, the abrasive grains were infiltrated into a nonwoven fabric polishing pad, and the nonwoven fabric polishing pad was heated at 300 degrees celsius and held for 2 hours to prepare a polishing pad. The material to be polished was a 2-inch SiC substrate. The following table 3 lists the milling conditions:

TABLE 3 grinding conditions

Ground material	SiC substrate (2 inch)
		Grinding speed	120r/min
Grinding pressure	180g/cm2
		Polishing pad	The invention provides a polishing pad
Abrasive grain	20 wt% diamond
		Dilatant fluid material	Hydroxypropyl terminated polydimethylsiloxanes

By using the grinding pad, the SiC substrate is ground for 1 hour under the conditions of different grain diameters of the abrasive particles, and the improvement range of the material removal efficiency is not obvious when the grain diameters of the abrasive particles are continuously improved. Therefore, when the solvent 4 is not subjected to the shearing force, the solvent is in a liquid state, the gravity and the buoyancy of the abrasive particles suspended in the solvent are balanced, and the height of the particle size of the exposed liquid surface is not changed greatly, so that the influence of the particle size of the abrasive particles on the grinding efficiency of the SiC substrate is small, larger abrasive particles can be selected, and the processing cost is reduced.

Example 4

As shown in fig. 5, a solvent 4 was used as hydroxypropyl-terminated polydimethylsiloxane, diamond abrasive grains having a grain size of 1 μm were added as abrasive grains 5, and the concentrations were adjusted to 5 wt%, 10 wt%, 20 wt%, and 30 wt%, respectively, and after kneading uniformly, the abrasive grains were infiltrated into a nonwoven fabric polishing pad, and the nonwoven fabric polishing pad was heated at 300 ℃ and maintained at the temperature for 2 hours to prepare a polishing pad. The material to be polished was a 2-inch SiC substrate. The milling conditions are listed in table 4 below:

TABLE 4 grinding conditions

Ground material	SiC substrate (2 inch)
		Grinding speed	120r/min
Grinding pressure	180g/cm2
		Polishing pad	The invention provides a polishing pad
Abrasive grain	Diamond (1 micron)
		Dilatant fluid material	Hydroxypropyl terminated polydimethylsiloxanes

By using the grinding pad, the SiC substrate is ground for 1 hour under the conditions of different concentrations of the abrasive particles 5, and the material removal efficiency is obviously improved when the abrasive particle concentration is continuously improved. It can be seen that the concentration of abrasive particles 5 in solvent 4 increases, and the abrasive particles participating in the grinding action also increases accordingly, thereby improving the material removal efficiency. Therefore, the abrasive grain concentration has a significant influence on the polishing efficiency of the SiC substrate, and a higher concentration of abrasive grains can be selected.

Example 5

As shown in fig. 6, a solvent 4 was used as hydroxypropyl-terminated polydimethylsiloxane, diamond abrasive grains having a grain size of 1 μm were added as abrasive grains 5, and after uniform mixing, the mixture was infiltrated into a nonwoven fabric polishing pad, and the nonwoven fabric polishing pad was heated at 300 ℃ for 2 hours to prepare a polishing pad. The material to be polished was a 2-inch sapphire, GaN, GaAs substrate. The following table 5 lists the milling conditions:

TABLE 5 grinding conditions

Ground material	Sapphire, GaN
		Grinding pressure	180g/cm2
Polishing pad	The invention provides a polishing pad
		Abrasive grain	20 wt% Diamond (1 micron)
Dilatant fluid material	Hydroxypropyl terminated polydimethylsiloxanes

When the sapphire substrate and the GaN substrate were polished for 1 hour using the polishing pad, it was found that the material removal efficiency was high.

As can be seen from the above embodiments, the polishing pad can satisfy the demand for high-efficiency processing of difficult-to-process materials such as sapphire, SiC, GaN, and the like.

The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.

It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. The invention is not described in detail in order to avoid unnecessary repetition.

In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.