CN1446667A

CN1446667A - CMP fabricating methods of sapphire solid phase reaction

Info

Publication number: CN1446667A
Application number: CN 03114195
Authority: CN
Inventors: 陈宝东
Original assignee: AOPUGUANG PHOTOELECTRON Co Ltd SHENZHEN
Current assignee: AOPUGUANG PHOTOELECTRON Co Ltd SHENZHEN
Priority date: 2003-04-11
Filing date: 2003-04-11
Publication date: 2003-10-08

Abstract

A CMP method for polishing sapphire by solid-phase reaction includes choosing oxide microparticles as abrasing material whose hardness is lower than that of sapphire, making the abrasing material in contact with sapphire for solid-phase reaction to generate crystal layer, and removing the crystal layer by mechanical contact with abrasing material. Its advantages are supersmooth surface (less than 1 nm for its roughness) and short time.

Description

Solid-phase reaction CMP processing method of sapphire

[ technical field ]

The invention relates to a processing method of sapphire, in particular to a solid-phase reaction CMP processing method of sapphire.

[ background art ]

In the field of sapphire crystal processing, traditional polishing is a process of using polishing micro powder as an abrasive on a polishing wheel under mechanical grinding and extrusion, and removing a processed material by using corner cutting of the polishing micro powder so as to achieve a smooth surface. The mohs hardness of the fine polishing powder used in this mechanical polishing method must be higher than the mohs hardness of the processed material. Therefore, plastic fracture and brittle fracture are accompanied in the process of material removal, and thus a different process work-affected layer remains on the polished surface. Taking the processing of a sapphire substrate required for a blue LED as an example, the mohs hardness of a sapphire single crystal is 9. The sapphire substrate processed by the traditional mechanical polishing method only uses diamond powder as polishing powder, and the sapphire substrate obtained by polishing the diamond powder has a plurality of scratches. The two major problems of surface scratches and surface roughness greater than 5nm are difficult problems that cannot be solved by applying the conventional polishing method. Since these problems cannot be solved well, an ideal sapphire substrate cannot be obtained all the time; meanwhile, the traditional mechanical polishing method requires the use of very expensive diamond powder.

In the field of material processing, there is a mechanical chemical polishing (CMP) method, which uses an abrasive softer than the workpiece material (e.g., Cr2O3 for Si3N4 ceramics), and which is capable of performing a solid phase reaction within a short contact time due to the activity of the moving abrasive itself and the high pressure and temperature generated by the friction between the abrasive and the workpiece at the microscopic contact level, and then the reaction product is removed by the mechanical friction of the moving abrasive, and the removal amount can be as small as about 0.1 nm. Because the abrasive particles are softer than the workpiece, the material is not removed by grinding. However, due to the difference of the materials to be processed, the processing method needs to select different abrasive grains through a large number of experiments and match with proper chemical processing conditions to obtain satisfactory effects; this method has not found widespread use, particularly for sapphire processing.

[ summary of the invention ]

The invention aims to overcome the defects of the prior art and provides a solid-phase reaction CMP processing method for sapphire.

The purpose of the invention is realized as follows: a solid phase reaction CMP processing method for sapphire is constructed, and comprises the following steps: selecting oxide micro powder with hardness smaller than that of sapphire as an abrasive; the grinding material is contacted with the sapphire, and a solid phase reaction is carried out at the contact point to generate a crystallization layer; the abrasive removes the crystallized layer by mechanical contact.

Compared with diamond micropowder polishing by a conventional mechanical polishing method, the diamond polishing is easy to generate damage on the processed surface, the solid-phase reaction CMP processing technology is used for locally generating micro solid-phase reaction, and the surface is an ultra-smooth surface (the surface roughness is less than 1nm) after the solid-phase substance is removed without any damage, so that the sapphire processed by the solid-phase reaction CMP processing technology lays a foundation for the use of downstream products. The polishing time used is much shorter than that of diamond polishing, and the production cost is reduced.

[ detailed description of the invention ]

The present invention will be further described with reference to the following examples.

The solid phase reaction CMP processing technique of sapphire is illustrated by processing a sapphire substrate as an example. Using sio of lower hardness than sapphire₂、α-Fe₂o₃(α of α -Fe2O3 means that iron oxide exists in α phase, for example, alumina has α, β and gamma phases, wherein α -AL2O3 is gem and other phases are not.) or Mgo micropowder with particle size of 0.02-0.08um, which is ground and polished, because sapphire contacts with powder particles, high temperature and high pressure are generated locally at contact points due to friction energy, and solid phase reaction occurs in very short contact time₂Will produce kyanite, α -Fe₂o₃Will generate α -Fe₂o₃-Al₂o₃Mgo then forms Mg-Al spinel. Experiments show that sio with Mohs hardness of 7 is selected₂As a polishing material for a sapphire substrate, suspending in an alkaline solution to perform wet processing at a polishing speed of 45 to 75m/min and a polishing pressure of 250 to 300gf/cm²The concentration of the polishing solution is 5-8 wt%. Sio at a certain pressure and temperature₂The micro powder and the sapphire single crystal instantaneously generate 50 Å kyanite (Al)₂o₃-sio₂). The chemical reaction formula is

This high temperature and pressure means that the vickers yield point of the silica is reached during the rubbing process.

The solid phase reaction is usually generated in the protruding parts (burrs or peaks) of the sapphire substrate, and the kyanite generated under the conditions is amorphous and can be easily removed from the surface through mechanical friction, the removal amount is about 10 Å per contact, so that the surface gradually tends to be smooth, and the ultra-precise surface with the surface roughness of less than 10 Å is processed.

Claims

1. A solid-phase reaction CMP processing method of sapphire is characterized by comprising the following steps: selecting oxide micro powder with hardness smaller than that of sapphire as an abrasive; the grinding material is contacted with the sapphire, and a solid phase reaction is carried out at the contact point to generate a crystallization layer; the abrasive removes the crystallized layer by mechanical contact.

2. The method for solid-phase reaction CMP processing of sapphire according to claim 1, wherein: the oxide being sio₂。

3. The method for solid-phase reaction CMP processing of sapphire as claimed in claim 1, wherein the oxide is α -Fe₂o₃Or Mgo.

4. The method for solid-phase reaction CMP processing of sapphire according to claim 2, wherein: the solid phase reaction CMP processing method is a wet processing method, the polishing speed is 45-75 m/min, and the polishing pressure is 250-300 gf/cm²The concentration of the polishing solution is 5-8 wt%.

5. The method for solid-phase reaction CMP processing of sapphire according to claim 2, wherein: the high temperature and high pressure conditions in the solid phase reaction reach the vickers yield point of the silicon dioxide.