WO2009021364A1

WO2009021364A1 - The method of controlling scratching of the polished surface of silicon wafer

Info

Publication number: WO2009021364A1
Application number: PCT/CN2007/002754
Authority: WO
Inventors: Jihe Zhong
Original assignee: Jiangsu Haixun Industry & Commerce Group Co., Ltd.
Priority date: 2007-08-15
Filing date: 2007-09-18
Publication date: 2009-02-19
Also published as: CN101367189A

Abstract

The present invention provides a method of controlling scratching of the polished surfaces of silicon wafers, which comprises adhering silicon wafers onto the polishing discs of a polisher, then holding the polishing discs onto the polishing heads of the polisher, controlling the pressure, the rotation speed of the upper and lower discs of the polisher, and injecting a polishing liquid between the polishing discs and the silicon wafer. The improvement is that:the polishing liquid comprises abradant, penetrant, lubricant, pH regulator, surfactant, chelating agent and deionized water; the pressure of the polisher is controlled below 50kPa, therotation speed of the upper polishing discs is controlled below 60rpm, the rotation speed of the lower polishing discs is controlled below 60rpm. It can reduce the scratching of the polished surfaces of silicon wafers, and can ensure the polishing of silicon wafer to have higher removal rate, and the cost is low, suitable for the industrial scale demand.

Description

Silicon wafer polishing surface scratching control method

The invention relates to a silicon wafer processing method, in particular to a method for controlling the scratching of a silicon wafer polishing surface for processing and polishing a single crystal silicon wafer for an integrated circuit substrate and reducing the degree of surface scratching.

Background technique -

Silicon is a hard and brittle material with a diamond crystal structure and covalently bonded between atoms. It is a good semiconductor material. At present, more than 90% of the integrated circuit semiconductor chips are silicon wafers (silicon wafers). In order to print integrated circuits on silicon wafers and to integrate them with other components, the surface of the silicon wafer must be straight, especially as the integration level of the integrated circuits continues to increase, and the requirements for the flatness and roughness of the silicon wafers are proposed. Strict requirements.

Polishing is the second mechanical processing of the surface after the silicon wafer is sliced, which is also a necessary basic process in the wafer processing technology. The purpose of polishing is to reduce the damage of the damage layer and surface of the surface of the silicon wafer during the grinding process, to achieve uniformity of the surface damage layer and to control the length of the scratch surface, so that the surface corrosion rate is uniform during chemical corrosion. Consistent. Wafer polishing includes light throwing, medium throwing, heavy throwing and water polishing. Generally, when polishing, the silicon wafer to be polished is first attached to the polishing machine polishing disc, and then the polishing disc is fixed on the polishing machine polishing head, and then adjusted. And control the appropriate pressure of the polishing machine, the appropriate rotation speed of the upper and lower polishing discs, and a reasonable flow of polishing liquid between the polishing disc and the silicon wafer, and then polish the silicon wafer.

In the preparation of very large scale integrated circuits, the surface polish of silicon wafers is one of the most important factors affecting the quality and reliability of electronic components. It is important to improve the pass rate of silicon wafer polishing products and control the scratching of polished surfaces. . At present, most practitioners often use a polishing fluid prepared by selecting a larger abrasive material in order to pursue the removal rate during the polishing process, resulting in an increase in the polishing damage layer and an increase in the number of surface scratches. An aluminum oxide polishing liquid having a specific particle size distribution is disclosed in Japanese Laid-Open Patent Publication No. 2001-323254. The polishing liquid uses nearly monodisperse colloidal boron carbide as an abrasive, and a large amount of scratches are formed on the surface of the 3⁄4 after polishing. U.S. Patent No. 6,143,662 discloses a polishing method using a small particle and a large particle mixed slurry, which also causes a large amount of scratch on the surface of the silicon wafer after polishing.

In order to improve the polishing quality of the silicon wafer and reduce the scratch on the surface of the silicon wafer, various control solutions for the polishing liquid and the surface scratch after polishing have appeared in recent years. As in Patent No. 03155318. 4, a smaller polishing scratch is achieved by controlling the abrasive particle size than the above two polishing liquids, but the removal rate of the polished silicon wafer is lowered due to the change in the abrasive particle size. In Patent 200510055710. 5, proposed a polishing method using spherical silica abrasive, although the effect of less polishing scratch is achieved, but this method requires higher abrasive performance, increases production cost, and is in mass production. Not easy to achieve.

Therefore, how to design a method for reducing the polishing scratch of a single crystal silicon wafer while maintaining a high removal rate and a low production cost is an urgent problem to be solved.

Summary of the invention

The main purpose of the present invention is to overcome the above-mentioned shortcomings of existing products, and to provide a control method for scratching a silicon wafer polishing surface, which improves the processing conditions of the silicon wafer polishing, and can effectively reduce the scratch on the surface of the polished silicon wafer. 'At the same time, it can guarantee the high removal rate of wafer polishing, and the production cost is low, which is suitable for scale production.

The object of the present invention is achieved by the following technical solutions. The method for controlling the scratching of the polished surface of the silicon wafer comprises: attaching the silicon wafer to the polishing machine polishing disc, and then fixing the polishing disc on the polishing machine polishing head to control the pressure of the polishing machine and the rotation speed of the upper and lower polishing discs. And injecting a polishing liquid between the polishing disk and the silicon wafer; wherein the polishing liquid comprises an abrasive, a penetrating agent, a lubricant, a pH adjusting agent, a surfactant, a chelating agent, and deionized water; and the pressure of the polishing machine The control is below 50 kPa, the rotational speed of the upper polishing disk is controlled below 60 rp _m , and the rotational speed of the lower polishing disk is controlled below 60 rpm.

The 5% by weight of the osmotic agent is 5% to 5%, and the osmotic agent is 3% to 5%. 5%至1. 0%, the pH of the modifier is 10% to 20%, the surfactant is 0.1% to 1. 0%, the chelating agent is 1% to 3%, deionized Water is the balance; at room temperature, abrasive, penetrant, lubricant, pH adjuster, surfactant and chelating agent are sequentially added to the deionized water, and stirred uniformly to prepare a polishing liquid.

The foregoing method for controlling scratching of a silicon wafer polishing surface, characterized in that the abrasive is silicon dioxide (SiO ₂ ) having a particle diameter of 70 to 90 nm, and aluminum oxide having a particle diameter of 150 to 200 nm (Α1Λ) ), a particle size of 100-150 nm ceria (Ce0 _2), a particle size of 100 to 150 nm titanium oxide (Ti0 ₂₎ or a particle diameter of 150 to 200 nanometers boron carbide; the penetrant is poly An oxyethylene ether (JFC) or a phosphate; the pH adjuster is an inorganic base or an organic base; and the chelating agent is one of ethylenediaminetetraacetic acid (EDTA), disodium edetate, hydroxylamine and amine Or a combination thereof; the lubricant is glycerin; the surfactant is a nonionic surfactant. '

The foregoing method for controlling scratching of a polished surface of a silicon wafer, characterized in that the hydroxylamine is triethanolamine, tetrahydroxyethylethylenediamine or hexahydroxypropylpropanediamine; the amine is ethylenediamine or tetramethyl Barium hydroxide. ·

The foregoing method for controlling scratching of a polished surface of a silicon wafer, characterized in that the nonionic surfactant is a fatty alcohol a polyoxyethylene ether, an alkanoyl alcohol amide or a mixture of the two; the fatty alcohol polyoxyethylene ether is a nonylphenol ethoxylate having a degree of polymerization of 15, and an octylphenol ethoxylate having a degree of polymerization of 20. (0-20), an octylphenol ethoxylate (0-25) having a degree of polymerization of 25 or an octylphenol ethoxylate having a degree of polymerization of 40 (0-40); the decyl alcohol amide is a laurel Acyl monoethanolamine, dihydroxyethyltridecylamide or dodecyl alcohol amide.

The foregoing method for controlling scratching of a polished surface of a silicon wafer, characterized in that the inorganic base is potassium hydroxide, sodium hydroxide or ammonia; the organic base is hydroxyethylenediamine, benzylamine, ethanolamine or tetramethylhydrogen. Ammonium oxide.

The foregoing method for controlling scratching of a silicon wafer polishing surface is characterized in that the pressure of the polishing machine is preferably 25 kPa or less, and the pressure application process is performed by a constant pressure of 0 to a desired pressure _r and polishing at a stable pressure.

The beneficial effects of the control method for scratching the surface of the silicon wafer of the invention, using the scientifically rationally formulated polishing liquid, and adjusting and controlling the polishing machine to operate under the suitable pressure and speed conditions, effectively reducing the scratch on the surface of the silicon wafer, providing Good surface quality and faster polishing rate without increasing production costs.

detailed description

The method for controlling the scratching of the polished surface of the silicon wafer comprises: bonding the silicon wafer to the polishing machine polishing disc, and then fixing the polishing disc on the polishing machine polishing head, controlling the pressure of the polishing machine and the rotation speed of the upper and lower polishing disks, and Injecting a polishing liquid between the polishing disk and the silicon wafer; the improvement is that the polishing liquid comprises an abrasive, a penetrating agent, a lubricant, a pH adjuster, a surfactant, a chelating agent, and deionized water; The pressure is controlled below 50 kPa, the rotational speed of the upper polishing disk is controlled below 60 rpm, and the rotational speed of the lower polishing disk is controlled below 60 rpm. -

The 5% by weight of the osmotic agent is 5% to 5%, and the osmotic agent is 3% to 5%. 5%至1. 0%, a pH adjuster of 10% to 20%, a surfactant of 0.1% to 1.0%, a chelating agent of 1% to 3%, deionized water For the remainder; at room temperature, add abrasive, penetrant, lubricant, pH adjuster, surfactant and chelating agent in deionized water, stir evenly to make a polishing solution.

The method for controlling scratching of a polished surface of a silicon wafer according to the present invention is characterized in that the abrasive is silicon dioxide (SiO ₂ ) having a particle diameter of 70 to 90 nm and aluminum oxide having a particle diameter of 150 to 200 nm (A1). ₂ 0:,), cerium oxide (Ce0 ₂ ) having a particle diameter of 100 to 150 nm, titanium oxide (Ti0 ₂ ) having a particle diameter of 100 to 150 nm, or boron carbide having a particle diameter of 150 to 200 nm; The agent is polyoxyethylene ether (JFC) or phosphate; the pH adjuster is an inorganic base or an organic base; the chelating agent is ethylenediaminetetraacetic acid (EDTA), disodium edetate, hydroxylamine and amine One or a combination thereof; the lubricant is glycerin; the surfactant is a nonionic surfactant. Wherein the hydroxylamine is triethanolamine, tetrahydroxyethylethylenediamine or hexahydroxypropylpropanediamine; the amine is ethylenediamine or tetramethylphosphonium hydroxide: The nonionic surfactant is a fatty alcohol polyoxyethylene ether, a mercapto alcohol amide or a mixture of the two; the fatty alcohol polyoxyethylene ether is a nonylphenol ethoxylate having a degree of polymerization of 15, and the degree of polymerization is 20 octylphenol ethoxylates (0-20), octylphenol ethoxylates with a degree of polymerization of 25 (0-25) or octylphenol ethoxylates with a degree of polymerization of 40 (0-40) The mercapto alcohol 'amide is lauroyl monoethanolamine, dihydroxyethyltridecylamide or dodecyl alcoholamide; the inorganic base is potassium hydroxide, sodium hydroxide or ammonia; the organic base is hydroxyl Ethylenediamine, benzylamine, ethanolamine or tetramethylammonium hydroxide.

In the method for controlling the scratching of the polished surface of the silicon wafer, the pressure of the polishing machine is preferably 25 kPa or less, and the pressure application process is carried out by a constant pressure of 0 to the desired pressure, and is thrown under a stable pressure.

The method for controlling the scratching of the polished surface of the silicon wafer of the present invention mainly aims at reducing the surface scratching in the polishing process of the silicon wafer by improving the processing conditions of the silicon wafer polishing. Firstly, the formulation of the polishing liquid is improved. The abrasive selected in the polishing liquid is a nano-scale abrasive. Compared with the conventional abrasive, the abrasive has the characteristics of small particle size, high fineness, good particle stability and firm particles, so that after polishing The surface roughness is lower, and the surface scratching can be effectively reduced; the chelating agent is added to the polishing liquid to chelate the heavy metal ions which affect the subsequent processing of the silicon wafer, and the effect of adding the penetrating agent is to increase the polishing. The penetration and flowability of the liquid in the polishing cloth makes the mass exchange effect of the polishing liquid in the polishing process more favorable; the fatty alcohol polyoxygen J: oxime ether or alkyl alcohol amide is used as the nonionic surfactant in the polishing liquid of the invention. , one of the two can be used alone, or a mixture of any two of them, the two surfactants can effectively reduce the scratch on the polished surface, mainly because the two are polished During the process, it acts as a wetting particle. During the polishing process, they can adsorb on the solid surface and protect the surface of the silicon wafer. Low surface tension, such that the wafer surface during polishing in resistance to cracking, formed pieces, thereby reducing the surface scratches after polishing. Secondly, the reasonable polishing machine pressure and the rotational speed of the polishing disc are designed. At this pressure and speed, the polishing machine can achieve the most efficient use efficiency, thereby reducing scratches.

The polishing machine used in the method for controlling the scratching of the polished surface of the silicon wafer is a commercially available product, for example, a double-sided polishing machine, and the material of the polishing disk may be spherical graphite cast iron or other, so No more details are given. In addition, the method of the present invention can be applied to a light throwing, medium throwing, and heavy polishing process of a silicon wafer.

The invention has the advantages of using a scientifically rationally formulated polishing liquid and adjusting and controlling the polishing machine to operate under suitable pressure and speed conditions, thereby effectively reducing the scratch on the surface of the silicon wafer, providing better surface quality and faster polishing. Rate, and does not increase production costs.

Example 1

The Lanxin 815B double-sided polishing machine is used, and the polishing disc is made of spheroidal graphite cast iron.

Prepare 1 kg of silicon wafer polishing solution. Weigh 10% of the silica abrasive by weight of the preparation slurry. The particle size of the silica is 70 nm, 12% sodium hydroxide, 0.5% lauroyl monoethanolamine, 3. 5% phosphoric acid. Ester, 1% glycerol, 2% hexahydroxypropyl propylenediamine, balance to deionized water. The above-mentioned silica abrasive, sodium hydroxide, lauroyl monoethanolamine, phosphate, glycerin and hexahydroxypropylpropanediamine were added to the deionized water in this order at room temperature, and the mixture was stirred for use.

When polishing, the silicon wafer to be polished is pasted on the polishing disc of the polishing machine, and the polishing disc with the silicon wafer adhered is fixed on the machine throwing head, and the pressure of the polishing machine is adjusted to increase from 0 to 10 kPa, and controlled at 10 kPa. 5升/分。 Adjusting the flow rate of the polishing liquid is 2. 5 l / min.

Experimental effect 'fruit analysis: Using the above polishing solution, diluted with 1:100 with deionized water, the silicon wafer was polished at a constant rate for 15 minutes under the above conditions. By detecting the wafer surface 100 times magnification, no scratch measurements, measuring wafer thickness before and after polishing divided by the polishing time to obtain the rate of removal of size 0. 9nm / mi _n, the surface roughness is 0. 015nm.

The surface roughness value is about 0.03 nm, and the surface roughness value is about 0.03 nm.

Example 2:

Prepare a silicon wafer polishing solution 2 kg.

The arsenic trioxide abrasive having a particle size of 200 nm, 10% tetramethylammonium hydroxide, and 0.3% polymerization degree of 25 were respectively weighed. Octylphenol ethoxylate, 5% polyoxyethylene ether (JFC), 0.7% glycerol, 1.5% tetrahydroxyethylethylenediamine, balance deionized water.

The above-mentioned alumina abrasive, tetramethylphosphonium hydroxide, octylphenol ethoxylate having a degree of polymerization of 25, polyoxyethylene ether, glycerin and tetrahydroxyethyl were respectively added in deionized water at room temperature. Ethylenediamine, stir well and use

During polishing, the silicon wafer to be polished is pasted on the polishing disc, and the polishing disc with the silicon wafer adhered is fixed on the polishing machine head, and the pressure of the polishing machine is uniformly increased from 0 to 10 kPa, and controlled at about 10 kPa, and controlled. 5升/分。 The polishing liquid flow rate is also 2.5 liters / min.

Experiment 3⁄4"Fruit analysis: Using the above polishing solution, diluted with 1:100 with deionized water, the silicon wafer was polished at a constant rate for 15 minutes under the above conditions. The surface of the silicon wafer was examined by a 100-fold microscope, and the measurement results were free from scratches. The thickness of the surface roughness is 0.02 nm. The surface roughness value is 0. 02 nm.

The surface removal value is generally about 0. 5nm / _m i _n , and the surface roughness value is about 0.5 nm / _m i _n using the existing polishing process. 0. 03nra or so.

The present invention relates to a room temperature of 20-25'C.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes and modifications made to the above embodiments in accordance with the technical spirit of the present invention are still It is within the scope of the technical solution of the present invention.

Claims

Rights request

1. A method for controlling scratching of a silicon wafer polishing surface, comprising: bonding a silicon wafer to a polishing machine polishing disc, and then fixing the polishing disc on the polishing machine polishing head to control the pressure of the polishing machine and the rotation speed of the upper and lower polishing discs And injecting a polishing liquid between the polishing disk and the silicon wafer; wherein the polishing liquid comprises an abrasive, a penetrating agent, a lubricant, a pH adjusting agent, a surfactant, a chelating agent, and deionized water; The pressure is controlled below 50 kPa, the rotational speed of the upper polishing disc is controlled below 60 ri»m, and the rotational speed of the lower polishing disc is controlled below 60 rpm.

0%至2. 0%, 0%, 0%, 0%, 0%, 0%, 0%, 0%, 0%, 0%, 0%, The sulphide is 1% to 1. 0%, the chelating agent is 1%, the surfactant is 0.1% to 1.0%, the surfactant is 0.1% to 1. 0%, the chelating agent is 1 From % to 3%, deionized water is the balance; at room temperature, abrasive, penetrant, lubricant, pH adjuster, surfactant and chelating agent are sequentially added to the deionized water, and stirred uniformly to prepare a polishing liquid.

The method for controlling scratching of a silicon wafer polishing surface according to claim 1 or 2, wherein the abrasive is silicon dioxide (SiO ₂ ) having a particle diameter of 70 to 90 nm and having a particle diameter of 150 to 200 nm of aluminum oxide (Α1Λ), ceria (Ce0 ₂ ) with a particle size of 100-150 nm, titanium dioxide (Ti0 ₂ ) with a particle size of 100 to 150 nm or a particle size of 150 to '200 nm Boron; the penetrant is polyoxyethylene ether (JFC) or phosphate; the pH adjuster is an inorganic base or an organic base; the chelating agent is ethylenediaminetetraacetic acid (EDTA), ethylenediaminetetraacetic acid One or a combination of disodium, hydroxylamine and amine; the lubricant is one of glycerin, dimethicone, vinyl silicone oil or a combination thereof: the surfactant is a nonionic surfactant . -

4. The method for controlling scratching of a silicon wafer polishing surface according to claim 3, wherein the hydroxylamine is triethanolamine, tetrahydroxyethylethylenediamine or hexahydroxypropylpropanediamine; Ethylenediamine or tetramethylammonium hydroxide hinge.

The method for controlling scratching of a polished surface of a silicon wafer according to claim 3, wherein the nonionic surfactant is a fatty alcohol polyoxyethylene ether, a mercapto alcohol amide or a mixture of the two; The fatty alcohol polyoxyethylene ether is a nonylphenol ethoxylate having a degree of polymerization 15, an octylphenol ethoxylate having a degree of polymerization of 20, an octylphenol ethoxylate having a degree of polymerization of 25, or a degree of polymerization. An octylphenol ethoxylate of 40; the decyl alcohol amide is lauroyl monoethanolamine, dihydroxyethyltridecylamide or dodecyl alcohol amide.

The method for controlling scratching of a polished surface of a silicon wafer according to claim 3, wherein the inorganic base is potassium hydroxide, sodium hydroxide or ammonia; and the organic base is hydroxyethylenediamine or benzyl chloride. Amine, ethanolamine or tetramethylammonium hydroxide.

7. The method for controlling scratching of a silicon wafer polishing surface according to claim 1, wherein the pressure of the polishing machine is preferably 25 kPa or less, and the pressure application process is performed by a constant pressure of 0 to a desired pressure, and Polishing under stable pressure.