TWI465556B - Abrasive composition for rough polishing wafers - Google Patents

Description

Abrasive composition for rough polishing wafers

This invention relates to an abrasive composition for rough polishing wafers, and more particularly to an abrasive composition for rough polishing wafers that slows polishing degradation.

In the semiconductor industry, germanium wafer substrates must be processed into a flat surface before they can be fabricated as IC devices. In general, the polishing method for planarizing the surface of a tantalum wafer is to place the wafer on a rotary polishing machine equipped with a polishing pad (Pad), and apply a polishing slurry containing submicron particles on the surface of the wafer to Achieve flattening effect.

The chemical mechanical polishing (CMP) program is the final procedure in the fabrication of wafers to reduce the micro-roughness of the wafer surface to planarize the wafer surface and remove physical surface defects such as micro-scratches and dent marks. After the wafer is polished, they have a mirror surface with low surface defects. The CMP process used to polish the wafer is typically performed in two or more steps. The rough polishing wafer step is a polishing step that requires a high polishing speed to remove deep scratches on the wafer surface. However, by-products generated during polishing may cause the abrasive particles such as cerium oxide to lose their suspending ability, and the instantaneous gelation adheres to the surface of the polishing pad, so that the polishing ability is lowered, and the above problem is more serious when the polishing speed is increased.

In addition, U.S. Patent No. 7,253,111 discloses a polishing solution for polishing a barrier which slows the yellowing of the polishing solution using EDTA or citric acid. In addition, U.S. Patent No. 6,509,269 discloses a polishing solution containing a nonionic surfactant to slow the glazing of the polishing pad, whereas the polishing solution is used for the planarization of aluminum or aluminum alloy. Not used for rough throwing of wafers.

Therefore, how to develop a polishing composition for rough polishing wafers, reduce the degradation of the polishing pad polishing speed, maintain the polishing quality, and improve the life of the polishing pad is a problem that is currently being solved.

To achieve the above and other objects, the present invention provides an abrasive composition for a rough-wafer wafer comprising: (A) abrasive particles having an average particle diameter of 5 to 150 nanometers; and (B) a pH stabilizer. The pKa value is between 9 and 10, and the pH stabilizer is present in an amount of from 7 to 28% by weight of the abrasive particles; (C) a grinding accelerator; and (D) water.

The abrasive particles of the present invention are selected from one or more of the group consisting of cerium oxide, aluminum oxide, titanium dioxide, cerium oxide and zirconium dioxide, and the use of abrasive particles having a small average particle size distribution is advantageous for lifting polishing. speed.

In the abrasive composition for rough polishing wafer of the present invention, the pH stabilizer may be selected from one or more of the group consisting of alkanolamines, inorganic acids, and organic acids. The alkanolamine may be selected from one or more of the group consisting of monoethanolamine, diethanolamine, and triethanolamine, and the mineral acid may be boric acid.

In addition, in order to effectively provide a faster polishing speed, the polishing composition for rough polishing wafer of the present invention comprises a polishing accelerator, which may be selected from the group consisting of (piperazine), piperazine One or more of the group consisting of salt, tetramethylammonium hydroxide and tetramethylammonium hydroxide, and the grinding accelerator is contained in an amount of 11 to 35 wt% of the abrasive particles. The polishing composition for rough polishing wafer of the present invention may further comprise a pH adjusting agent selected from the group consisting of sodium hydroxide, potassium hydroxide, sulfuric acid, hydrochloric acid or phosphoric acid, and the pH adjusting agent added as needed is mainly The pH of the composition was adjusted to around 10.

In another aspect, the polishing composition for rough polishing wafer of the present invention may further comprise a chelating agent and a surfactant, wherein the chelating agent is present in an amount of 5.9 to 20% by weight of the abrasive particles, and the surfactant is The content is from 0.16 to 0.18 wt% of the abrasive particles.

The polishing composition of the invention is used for rough polishing wafers, can effectively reduce the gelation of by-products in the polishing particles and the polishing process, and adheres to the polishing pad, and can maintain the polishing quality while maintaining the polishing speed, and delays the polishing quality. The polishing pad is discolored to improve the performance and life of the polishing pad.

The embodiments of the present invention are described below by way of specific examples, and those skilled in the art can readily understand the advantages and functions of the present invention from the disclosure herein. The present invention may be embodied or applied by other different embodiments, and the various details of the present invention may be variously modified and changed without departing from the spirit and scope of the invention.

The present invention provides an abrasive composition for rough polishing wafers comprising: (A) abrasive particles having an average particle diameter of 5 to 150 nanometers; (B) a pH stabilizer having a pKa value of 9 to 10 And the pH stabilizer is present in an amount of from 7 to 28% by weight of the abrasive particles; (C) a grinding accelerator; and (D) water.

The abrasive particles of the present invention are selected from one or more of the group consisting of cerium oxide, aluminum oxide, titanium dioxide, cerium oxide and zirconium dioxide, and the use of abrasive particles having a small average particle size distribution is advantageous for lifting polishing. speed.

In the polishing composition for rough polishing wafer of the present invention, the pH stabilizer may be selected from one or more of the group consisting of alkanolamines, inorganic acids and organic acids having a pKa value of from 9 to 10. . The alkanolamine may be selected from one or more of the group consisting of monoethanolamine (pKa = 9.50), diethanolamine (pKa = 9.93) and triethanolamine (pKa = 9.8), and examples of the mineral acid such as boric acid (pKa) =9.23). In the composition of the present invention, the pH stabilizer can be added to maintain the pH of the composition of the present invention between 9 and 10.5 when the wafer is coarsely polished, and to avoid the peracid and over-base of the local pH, thereby effectively reducing the pH. The abrasive particles are gelled by the by-products in the polishing process, and adhere to the polishing pad, and the polishing quality is maintained while maintaining the polishing quality, and the polishing pad is discolored, and the performance and life of the polishing pad are improved.

In addition, in order to effectively provide a faster polishing speed, the polishing composition for rough polishing wafer of the present invention comprises a polishing accelerator, which may be selected from the group consisting of (piperazine), piperazine One or more of the group consisting of salt, tetramethylammonium hydroxide and tetramethylammonium hydroxide, and the grinding accelerator is contained in an amount of 11 to 35 wt% of the abrasive particles. The polishing composition for rough polishing wafer of the present invention further comprises a pH adjusting agent selected from the group consisting of sodium hydroxide, potassium hydroxide, sulfuric acid, hydrochloric acid or phosphoric acid, and the pH adjusting agent added as needed mainly constitutes The pH of the substance was adjusted to around 10.

In another aspect, the polishing composition for rough polishing wafer of the present invention may further comprise a chelating agent and a surfactant, wherein the chelating agent is present in an amount of 5.9 to 20% by weight of the abrasive particles, and the surfactant is The content is from 0.16 to 0.18 wt% of the abrasive particles. In a specific embodiment, the sodium salt of nitrogen triacetic acid is used as a chelating agent, and of course, nitrogen triacetic acid can also be used as a chelating agent.

The features and effects of the present invention are further illustrated by the following specific examples, but are not intended to limit the scope of the invention.

Example Preparation Example Preparation of grinding composition for rough polishing wafers

The polishing compositions of the respective examples and comparative examples in the following Table 1 were prepared according to the procedures described below.

First, a pure water or deionized water is added to the vessel, followed by the addition of a grinding accelerator, and then a pH stabilizer is added, and then the pH adjuster is added as needed to adjust the pH of the composition to about 10. In addition, a chelating agent and a surfactant may be added as needed, and finally the abrasive particles are added. Each of the above preparation steps is carried out after uniformly mixing the ingredients.

Test Example Wafer polishing using the prepared polishing composition

In this example, a 6-inch wafer was polished using a grinder (SECULAR XJ-36) equipped with a polishing pad of the type SUBA600, which has four polishing heads, each of which can carry three sheets of 6 turns. Wafer. During the grinding process, the polishing machine has a disk surface temperature of 31 to 34 ° C, a rotational speed of 50 RPM, a polishing head pressure of 0.12 MPa, and a flow rate of the polishing composition slurry of 8 L/min. After the polishing is started, the thickness variation of the wafer is recorded every hour and the color of the polishing pad is visually observed. When the polishing pad is turned into a yellowish brown color, it is recognized as the end point of the polishing pad. In addition, the polishing composition slurry for polishing is continuously recycled until the end of the polishing pad life.

In the present invention, the percentage of deterioration of the polishing rate is obtained by dividing the difference in polishing speed between the first hour (A) and the last hour (B) by the polishing rate (A) of the first hour, as shown in the following formula.

Polishing speed decline = [(A-B/A)] * 100%

The total removal of the polishing pad is the sum of the thicknesses of all wafers removed by grinding.

TMAH: Tetramethylammonium hydroxide; tetramethylammonium hydroxide.

NTA: Nitrilotriacetate; nitrotriacetate.

DP7530: PO/EO copolymer.

SEQ7G: Anionic dispersing chelating agent (Taiwan Chemical Industry Co., Ltd.).

pH adjuster: Adding as needed mainly adjusts the pH of the composition to about 10.

In Table 1, the contents of the pH stabilizer, the polishing accelerator, the pH adjuster, the chelating agent, and the surfactant are calculated based on the cerium oxide content (100 parts by weight).

The polishing composition used in this test example was further prepared by adding water to a state containing a solid content of 1% by weight. Typically, the abrasive composition for milling has a solids content ranging from about 0.5 to 20% by weight.

As can be seen from the results in the above table, polishing the wafer with the slurry of the polishing composition without the pH stabilizer, the polishing rate is deteriorated quite seriously, and polishing the wafer using the polishing composition of the present invention containing the pH stabilizer can greatly reduce the polishing pad. The polishing rate is degraded, the polishing quality is maintained, and more wafer thickness can be removed before the polishing pad ends, which significantly increases the life of the polishing pad.

The above-described embodiments are merely illustrative of the principles of the invention and its effects, and are not intended to limit the invention. Modifications and variations of the above-described embodiments can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and scope of the invention will be covered by the appended claims.

There is no schema in this case.

Claims (8)

A polishing composition for a rough-wafer wafer comprising: (A) abrasive particles having an average particle diameter of 5 to 150 nm; (B) a pH stabilizer having a pKa value of 9 to 10, and the pH The stabilizer is present in an amount of from 7 to 28% by weight of the abrasive particles such that the pH of the abrasive composition is between 9 and 10.5; (C) a grinding accelerator; and (D) water. The polishing composition for rough polishing wafer according to claim 1, wherein the abrasive particles are selected from the group consisting of cerium oxide, aluminum oxide, titanium oxide, cerium oxide and zirconium dioxide. One or more of the groups. The polishing composition for rough polishing wafer according to claim 1, wherein the pH stabilizer is selected from the group consisting of alkanolamines, inorganic acids and organic acids having a pKa value of 9 to 10. One or more of the groups. The polishing composition for rough polishing wafer according to claim 3, wherein the alkanolamine of the pH stabilizer is selected from the group consisting of monoethanolamine, diethanolamine, and triethanolamine. One or more of the groups formed. The polishing composition for rough polishing wafers according to claim 3, wherein the inorganic acid of the pH stabilizer is boric acid. The polishing composition for rough polishing wafer according to claim 1, wherein the polishing accelerator is selected from the group consisting of piperazine, piperazine, and tetramethylammonium hydroxide. And one or more of the group consisting of tetramethylammonium hydroxide, and the grinding accelerator is contained in an amount of 11 to 35 wt% of the abrasive particles. The abrasive composition for rough-wafering of the wafer according to claim 1, wherein the chelating agent is included in an amount of 5.9 to 20% by weight of the abrasive particles. The abrasive composition for rough-wafering of the wafer according to claim 1, wherein the surfactant is included in an amount of 0.16 to 0.18 wt% of the abrasive particles.