TWI797223B - Chemical mechanical polishing slurry - Google Patents

Abstract

The invention discloses a chemical mechanical polishing slurry, comprising silica abrasive particles, rate-accelerating additives, and azole compounds and their derivatives. The invention greatly enhance the polishing rate of SiN, provide a lower polishing rate of TEOS, and reduce the polishing rate of Cu, thus, repair the dishing on the mixed bonded surface.

Description

chemical mechanical polishing fluid

The invention relates to a chemical mechanical polishing liquid technology, especially a chemical mechanical polishing liquid with high silicon nitride, low silicon dioxide and low copper removal rate.

Three-dimensional integrated circuits need to realize the internal interconnection of thousands of chips while bonding two wafers, and these require conductive bonding of two wafers. Generally, conductive connections can be made through a simple metal bonding process It can be realized with the hybrid bonding process (hybrid bonding) with higher bonding strength. Since the strength achieved by the pure metal bonding process is not ideal, the hybrid bonding process is the current bonding process in the three-dimensional integrated circuit. preferred.

The hybrid bonding technology is a bonding process in which a metal and an insulator are simultaneously provided on the bonding interface of the wafer, and the metal on the bonding interface of the two wafers needs to be aligned with the metal during the bonding process. Insulators are aligned with insulators and bonded under certain temperature conditions. Usually, the material of the insulator on the bonding interface is silicon dioxide or silicon nitride, and the material of the metal is copper. The common bonding process is to form a layer of silicon nitride on the surface of the wafer, and then form a layer of silicon dioxide film on the surface of the silicon nitride, form grooves by photolithography and etching, and use metal deposition to fill the metal In the groove and covering the surface of the film, the copper and silicon dioxide film on the surface are removed by CMP to obtain an interface layer of silicon nitride and copper. There are both metal and insulating substances on the hybrid bonding surface, and the requirements for the flatness of the bonding interface surface are very high. Using a polishing solution with high silicon dioxide and low silicon nitride removal rate to remove the silicon dioxide film will cause large dish-shaped depressions and greatly reduce the flatness of the surface. In order to reduce this defect, it is necessary to provide a polishing solution with high silicon nitride, low silicon dioxide, and low copper removal rate to repair the surface and obtain a higher flatness surface in a short period of time.

In order to solve the above problems, the present invention proposes a chemical mechanical polishing liquid, by adding a pyridine compound, a piperidine compound, a pyrrolidine compound or a pyrrole compound containing one or more carboxyl groups, and adjusting the pH of the polishing liquid to the pK _a1 of the above compound 1.5 units and less than 6, the polishing speed of SiN is greatly improved and the polishing speed of TEOS is lower. At the same time, the polishing speed of copper is reduced by using azole compounds, and the hybrid bonding surface can be repaired in a short period of time. Die dent for repair.

The invention provides a chemical mechanical polishing liquid, which comprises silicon dioxide, at least one accelerator, azole compounds and derivatives thereof. The accelerator is one or more of pyridine compounds, piperidine compounds, pyrrolidine compounds or pyrrole compounds and their derivatives containing one or more carboxyl groups.

Preferably, the mass percent concentration of the silicon dioxide is 0.5% to 8%, more preferably, 1% to 5%.

Preferably, the accelerator is selected from 2-carboxypyridine, 3-carboxypyridine, 4-carboxypyridine, 2,3-dicarboxypyridine, 2,4-dicarboxypyridine, 2,6-carboxypyridine, 3 ,5-dicarboxypyridine, 2-carboxypiperidine, 3-carboxypiperidine, 4-carboxypiperidine, 2,3-dicarboxypiperidine, 2,4-dicarboxypiperidine, 2,6-dicarboxypiperidine Pyridine, 3,5-dicarboxypiperidine, 2-carboxypyrrolidine, 3-carboxypyrrolidine, 2,4-dicarboxypyrrolidine, 2,5-dicarboxypyrrolidine, 2-carboxypyrrole, 3-carboxypyrrole , 2,5-dicarboxypyrrole, 3,4-dicarboxypyridine in one or more.

Preferably, the mass percent concentration of the accelerator is 0.001% to 1%, more preferably, 0.01% to 0.5%.

Preferably, the azole compounds and their derivatives include 1,2,3-triazole, 1H-tetrazolium, 1,2,4-triazole, 1-methyl-5 aminotetrazolium, 5-methyltetrazolium, 1-amino-5-mercapto-1,2,4-tetrazole, 5-phenyltetrazolium and 1-phenyl-5-mercaptotetrazolium, benzotriazole , 5-methyl-1,2,3-benzotriazole, 5-carboxybenzotriazole, 1-hydroxy-benzotriazole, 3-amino-1,2,4-triazole , 3,5-diamino-1,2,4-triazole, 5-carboxy-3-amino-1,2,4-triazole, 3-amino-5-mercapto-1,2,4- One or more of triazole, 5-acetic acid-1H-tetrazolium, 5-methyltetrazolium and 5-amino-1H-tetrazolium.

Preferably, the mass percent concentration of the azole compound and its derivatives is 0.001% to %, more preferably, 0.01% to 1%.

Preferably, the pH value of the chemical mechanical polishing solution is greater than 1.5 units and less than 6.5 of the pK _a1 of the pyridine compound, piperidine compound, pyrrolidine compound or pyrrole compound containing one or more carboxyl groups.

Preferably, the chemical mechanical polishing fluid also contains a bactericide. More preferably, the fungicides include 5-chloro-2-methyl-4-isothiazolin-3-one (CIT), 2-methyl-4-isothiazolinone (MIT), 1,2- One or more of benzothiazolinone (BIT), iodopropynyl carbamate (IPBC), and 1,3-dimethylol-5,5-methylhydantoin (DMDMH).

Preferably, the chemical mechanical polishing solution further contains a pH regulator selected from HNO ₃ , KOH, K ₂ HPO ₄ or KH ₂ PO ₄ .

Compared with the prior art, the technical advantages of the present invention are: 1) Containing one or more of pyridine compounds, piperidine compounds, pyrrolidine compounds or pyrrole compounds containing one or more carboxyl groups, when the pH of the polishing solution is greater than When the pK _a1 of the above components is 1.5 units and less than 6, it shows a high SiN polishing speed and a low TEOS polishing speed, with a high SiN/TEOS selectivity ratio; 2) Add azoles to the polishing solution Compounds and derivatives thereof exhibit lower copper polishing speeds and can repair dish-shaped depressions on hybrid bonding surfaces in a shorter period of time; and 3) the chemical mechanical polishing solution of the present invention can be made into a concentrated solution Use, reduce costs.

The advantages of the present invention will be described in detail below in combination with comparative examples and embodiments consistent with the present invention.

According to the formula given in Table 1, all components were dissolved and mixed evenly, and the mass percentage was made up to 100% with water, and then the pH was adjusted to the desired value with a pH regulator to obtain the comparative examples and examples described in Table 1.

Then, the specific polishing conditions are: Mirra machine, IC1010pad, speed 93/87; polishing pressure: 3.0psi; polishing flow rate 150ml/min, polish 8-inch silicon nitride, silicon dioxide, and copper for 1 minute, and then clean, After drying and testing, the polishing results described in Table 1 were obtained. Then, for the bonded wafer that has been removed from the silicon dioxide film, the concave defect is repaired with the polishing solution in Table 1, the polishing time is 15 seconds, and the disc-shaped depression value before the wafer is not repaired is 120A. The dent repair results of the examples are shown in Table 1. The formula and polishing effect of table 1 comparative example and embodiment

From the results of comparative examples 1 and 2, it can be seen that only adding pyridine compounds, piperidine compounds, pyrrolidine compounds or pyrrole compounds containing carboxyl groups in the polishing composition can improve the polishing rate of silicon nitride, but reduce The polishing rate of silicon dioxide was increased, but that of copper was not changed.

As can be seen from the polishing results of Comparative Example 2, Comparative Example 2 does not contain azole compounds, and the polishing solution exhibits a high copper polishing rate and a low silicon nitride polishing rate, and the disc-shaped depressions on the wafer surface are not obtained. The repair becomes larger instead. It can be seen that high copper polishing speed and low silicon nitride polishing speed are unfavorable to the repair of dishing.

However, as can be seen from the results of the examples of the present invention, the present invention adds compounds containing carboxyl groups in the polishing liquid, which increases the polishing rate of silicon nitride and reduces the polishing rate of silicon dioxide. Azole compounds reduce the polishing rate of copper, which greatly increases the selectivity ratio of silicon nitride to silicon dioxide and silicon nitride to copper, so that in the polishing process, in a short time, The dishing was repaired, and the dishing was sunken and lowered to below 30A. The present invention utilizes the compounding effect of carboxyl group compound and azole compound, and the obtained polishing liquid has high silicon nitride speed, low silicon dioxide and copper polishing speed at the same time, and repairs the dish-shaped depression of the bonded wafer , to a higher flatness of the wafer surface.

It should be noted that the embodiments of the present invention have better implementability and are not intended to limit the present invention in any form. Any person skilled in the art may use the technical content disclosed above to change or modify equivalent effective embodiments However, any modifications or equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still belong to the scope of the technical solution of the present invention.

Claims (5)

A chemical-mechanical polishing fluid, comprising silicon dioxide, at least one accelerator, and an azole compound; wherein, the accelerator is a pyridine compound, a piperidine compound, or a pyrrolidine compound containing one or more carboxyl groups or pyrrole compound; the mass percentage concentration of the silicon dioxide is 0.5% to 8%; the accelerator is selected from 2-carboxypyridine, 3-carboxypyridine, 4-carboxypyridine, 2,3-dicarboxypyridine, 2,4-dicarboxypyridine, 2,6-dicarboxypyridine, 3,5-dicarboxypyridine, 2-carboxypiperidine, 3-carboxypiperidine, 4-carboxypiperidine, 2,3-dicarboxypiperidine , 2,4-dicarboxypiperidine, 2,6-dicarboxypiperidine, 3,5-dicarboxypiperidine, 2-carboxypyrrolidine, 3-carboxypyrrolidine, 2,4-dicarboxypyrrolidine, 2 , one or more of 5-dicarboxypyrrolidine, 2-carboxypyrrole, 2,5-dicarboxypyrrole, 3,4-dicarboxypyridine; the mass percent concentration of the accelerator is 0.001% to 1%; The azole compounds and derivatives thereof include 1,2,3-triazole, 1H-tetrazolium, 1,2,4-triazole, 1-methyl-5 aminotetrazolium, 5-methyl Base tetrazolium, 1-amino-5-mercapto-1,2,4 tetrazolium, 5-phenyl tetrazolium and 1-phenyl-5-mercapto tetrazolium, benzotriazole, 5- Methyl-1,2,3-benzotriazole, 5-carboxybenzotriazole, 1-hydroxy-benzotriazole, 3-amino-1,2,4-triazole, 3, 5-diamino-1,2,4-triazole, 5-carboxy-3-amino-1,2,4-triazole, 3-amino-5-mercapto-1,2,4-triazole , 5-acetic acid-1H-tetrazolium, 5-methyltetrazolium and 5-amino-1H-tetrazolium; the mass percentage concentration of the azole compound and its derivatives is 0.001% to 3%. The chemical mechanical polishing liquid as described in claim 1, wherein the mass percent concentration of the silicon dioxide is 1% to 5%. The chemical mechanical polishing fluid according to claim 1, wherein the mass percent concentration of the accelerator is 0.01% to 0.5%. The chemical mechanical polishing fluid according to claim 1, wherein the mass percent concentration of the azole compound and its derivatives is 0.01% to 1%. The chemical mechanical polishing liquid according to claim 1, wherein the pH value of the chemical mechanical polishing liquid is greater than the pK of the pyridine compound, piperidine compound, pyrrolidine compound or pyrrole compound containing one or more carboxyl groups 1.5 units of _a1 and less than 6.5.