CN108117840B

CN108117840B - Silicon nitride chemical mechanical polishing solution

Info

Publication number: CN108117840B
Application number: CN201611070743.1A
Authority: CN
Inventors: 周文婷
Original assignee: Anji Microelectronics Shanghai Co Ltd
Current assignee: Anji Microelectronics Shanghai Co Ltd
Priority date: 2016-11-29
Filing date: 2016-11-29
Publication date: 2021-09-21
Anticipated expiration: 2036-11-29
Also published as: TW201819587A; CN108117840A; TWI732952B; WO2018099111A1

Abstract

The invention relates to a silicon nitride chemical mechanical polishing solution, which comprises water and grinding particles, and also comprises a heterocyclic compound containing one or more carboxyl groups, a polyamine acid and an alkanolamine compound, a pH regulator and a bactericide. The polishing solution can improve the polishing speed selection ratio of silicon nitride to silicon dioxide and the polishing speed selection ratio of silicon nitride to polysilicon, can obviously improve the polishing speed of silicon nitride and reduce the polishing speed of silicon dioxide and polysilicon, and has good market application prospect.

Description

Silicon nitride chemical mechanical polishing solution

Technical Field

The invention relates to a chemical mechanical polishing solution in a semiconductor manufacturing process. In particular to a silicon nitride chemical mechanical polishing solution with high selectivity.

Background

In the production of semiconductor devices, a step of removing a silicon nitride layer is performed at various stages, for example, in a step of forming an element isolation structure, a silicon nitride layer as a barrier layer is removed.

Among them, much attention is paid to a Shallow Trench Isolation (STI) process for a method for isolating a semiconductor device. A silicon nitride layer formed on a silicon substrate, shallow trenches are formed via etching or photolithography, and a deposited dielectric layer is used to fill the trenches. Variations in the depth of trenches or lines formed in this manner typically require an excess of dielectric material to be deposited on top of the substrate to ensure that all trenches are completely filled. The excess dielectric material (e.g., oxide) then typically needs to be removed by a chemical mechanical planarization process to expose the silicon nitride layer. When the silicon nitride layer is exposed, as the largest area of the substrate of the chemical mechanical polishing system, the silicon nitride must be subsequently polished to obtain a highly planar and uniform surface. Since the overall polishing rate decreases after the silicon nitride layer is exposed, in prior practice, there has been an emphasis on oxide polishing over silicon nitride polishing. Also, a silicon nitride layer is typically used as a stop layer during the chemical mechanical planarization process. As the line width of oxide decreases with advances in etching technology, it is generally desirable that the polishing system employed be selective to polishing silicon nitride over polishing oxide so that defects in the oxide lines formed on the substrate surface are minimized.

Past device designs have focused on the chemical mechanical planarization selectivity of silicon dioxide to silicon nitride, i.e., the removal rate of silicon dioxide is higher relative to the removal rate of silicon nitride. In these device designs, the silicon nitride layer acts as a stop layer for chemical mechanical planarization.

Recently, some device designs require a combination of chemical mechanical polishing to have silicon nitride and polysilicon selectivity, i.e., a higher silicon nitride removal rate relative to polysilicon removal rate. In these device designs, the polysilicon layer acts as a stop layer for chemical mechanical planarization.

Disclosure of Invention

The invention aims to provide a chemical mechanical polishing solution which can improve the polishing speed selection ratio of silicon nitride to silicon dioxide and the polishing speed selection ratio of silicon nitride to polysilicon, and can obviously improve the polishing speed of silicon nitride and lower the polishing speed of silicon dioxide and polysilicon.

The invention provides a silicon nitride chemical mechanical polishing solution, which contains water and grinding particles, and also contains heterocyclic compounds containing one or more carboxyl groups, poly-amino acid and alkanolamine compounds, pH regulators and bactericides.

Wherein, the grinding particles are silicon dioxide particles, and the concentration thereof is preferably 0.5 to 8 percent by mass, and is preferably 1 to 5 percent by mass.

Wherein said heterocyclic compound containing one or more carboxyl groups comprises one or more of pyridine compound, piperidine compound, pyrrolidine compound or pyrrole compound and derivatives thereof, non-limiting examples of which include 2-carboxypyridine, 3-carboxypyridine, 4-carboxypyridine, 2, 3-dicarboxylpyridine, 2, 4-dicarboxylpyridine, 2, 6-dicarboxylpyridine, 3, 5-dicarboxylpyridine, 2-carboxypiperidine, 3-carboxypiperidine, 4-carboxypiperidine, 2, 3-dicarboxylpiperidine, 2, 4-dicarboxylpiperidine, 2, 6-dicarboxylpiperidine, 3, 5-dicarboxylpiperidine, 2-carboxypyrrolidine, 3-carboxypyrrolidine, 2, 4-dicarboxylpyrrolidine, 2, 5-dicarboxylpyrrolidine, 2-carboxypyrrole, 3-carboxypyrrole, 2, 5-dicarboxylpyrrole, 3, 4-dicarboxylpyridine, etc., preferably in a concentration of 0.01 to 0.5% by mass, more preferably 0.01 to 0.3% by mass.

Wherein the polyamine acid and alkanolamine compound is hydroxyalkyl ammonium salt of polycarboxylic acid polymer, such as ANTI-TERRA-250, DISPERBYK, DISPERBYK-180, DISPERBYK-181, DISPERBYK-187, etc. from BYK. The concentration thereof is preferably 0.001 to 0.5% by mass, preferably 0.01 to 0.1%.

Wherein, the bactericide can be selected from 5-chloro-2-methyl-4-isothiazolin-3-one (CIT), 2-methyl-4-isothiazolin-one (MIT), 1, 2-phenylpropanoid isothiazolin-one (BIT), iodopropynyl carbamate (IPBC), 1, 3-dimethylol-5, 5-methylhydantyl hydantoin (DMDMDMH) and the like, and the concentration is preferably 0.02 to 0.2 percent by mass.

Wherein the pH regulator comprises HNO₃、KOH、K₂HPO₄Or KH₂PO₄One or more of (a).

Wherein the pH value of the polishing solution is more than 1.5 units and less than 6.5 units of the pKa1 of the heterocyclic compound containing one or more carboxyl groups.

Compared with the prior art, the invention has the technical advantages that:

the invention adds heterocyclic compounds containing one or more carboxyl groups, and the pH value is more than 1.5 units and less than 6.5 of the pKa1 of the components. The compound has carboxyl and a nitrogen-containing structure in a molecular structure, the nitrogen-containing structure is attracted with silicon dioxide abrasive particles, so that the carboxyl structure is exposed outside, after the compound meets the silicon nitride surface, due to attraction of opposite charges, the interaction between the abrasive particles and the silicon nitride surface is greatly increased, and the polishing speed of the silicon nitride wafer is remarkably improved; meanwhile, due to mutual repulsion of charges, the interaction between the grinding particles and the silicon dioxide wafer is reduced, the polishing speed of silicon dioxide is inhibited, and the polishing speed selection ratio of silicon nitride to silicon dioxide is further remarkably improved. The polyamine acid and the alkanolamine compound are added to cover the surface of the polysilicon, so that the interaction between the grinding particles and the surface of the polysilicon is reduced, the polishing speed of the polysilicon is inhibited, the selection ratio of silicon nitride to the polysilicon is obviously improved, the polishing speed of the silicon nitride can be obviously improved, and the silicon dioxide and polysilicon polishing speed is low.

Detailed Description

The invention is further illustrated by the following examples, which are not intended to limit the invention thereto.

Comparative examples 1 to 3 and examples 1 to 10

Table 1 shows the components and the contents of comparative examples 1-3 and examples 1-10 of the polishing solution of the invention, according to the formula in the table, all the components are dissolved and mixed uniformly, water is used for complementing the mass percent to 100%, a pH regulator is used for regulating the pH value to a proper value, and the polishing solution can be prepared by standing.

TABLE 1 polishing solutions of the invention comparative examples 1-3 and examples 1-10 formulations

The polishing solutions according to the formulations in Table 1 were tested according to the following test conditions.

The specific polishing conditions were: mirra bench, IC1010pad, rotation speed 93/87, polishing pressure 1.5psi, polishing flow 150 ml/min. And inputting the parameters into a Mirra machine, polishing, cleaning, drying and detecting 8-inch silicon nitride and silicon dioxide for 1min, and obtaining a polishing result.

It can be seen from the results of comparative example 1 that polishing with pure silicon dioxide has a low polishing rate for silicon nitride and a relatively high polishing rate for silicon dioxide, and the selectivity of silicon nitride to silicon dioxide is reversed. From the results of comparative examples 2 and 3, in the case where the pH was 1.5 units greater than Pka1(0.99) for 2-carboxypyridine, the polishing rate of silicon nitride was high, the rate of silicon dioxide was low, and the selectivity ratio of silicon nitride to silicon dioxide was high. From the examples and comparative examples 2,3, the addition of the polyamine acid and the alkanolamine compound reduces the polishing speed of the polysilicon and obviously improves the selection ratio of silicon nitride to the polysilicon. The invention also provides high selectivity ratio of silicon nitride to silicon dioxide and silicon nitride to polysilicon.

It should be noted that the embodiments of the present invention have been described in terms of preferred embodiments, and not by way of limitation, as those skilled in the art will recognize that variations and modifications of the disclosed embodiments can be made without departing from the spirit and scope of the invention as defined by the appended claims. However, any modification, equivalent change and modification of the above embodiments according to the technical essence of the present invention are within the scope of the technical solution of the present invention without departing from the content of the technical solution of the present invention.

Claims

1. A silicon nitride chemical mechanical polishing solution consists of water, grinding particles, heterocyclic compounds containing one or more carboxyl groups, poly-amino acid and alkanolamine compounds, pH regulators and bactericides; the grinding particles are silica particles;

the heterocyclic compound containing one or more carboxyl groups accounts for 0.2 to 0.5 percent by mass and is selected from one or more of 2-carboxypyrrolidine, 3-carboxypyrrolidine, 2, 4-dicarboxylpyrrolidine, 2, 5-dicarboxylpyrrolidine, 2-carboxypyrrole, 3-carboxypyrrole and 2, 5-dicarboxylpyrrole;

the polyamine acid and alkanolamine compound is hydroxyalkyl ammonium salt of polycarboxylic acid polymer;

the pH value of the polishing solution is more than 1.5 units and less than 6.5 units of the pKa1 of the heterocyclic compound containing one or more carboxyl groups.

2. The chemical mechanical polishing solution for silicon nitride according to claim 1, wherein the abrasive grains are contained in an amount of 0.5 to 8% by mass.

3. The chemical mechanical polishing solution for silicon nitride according to claim 2, wherein the silica particles are present in an amount of 1% to 5% by mass.

4. The silicon nitride chemical mechanical polishing solution according to claim 1, wherein the heterocyclic compound containing one or more carboxyl groups is preferably contained in an amount of 0.2 to 0.3% by mass.

5. The silicon nitride chemical mechanical polishing solution according to claim 1, wherein the mass percentage of the polyamine acid and the alkanolamine compound is 0.001% -0.5%.

6. The silicon nitride chemical mechanical polishing solution according to claim 5, wherein the mass percent of the polyamino acid and the alkanolamine compound is 0.01-0.1%.

7. The silicon nitride chemical mechanical polishing solution according to claim 1, wherein the bactericide comprises one or more of 5-chloro-2-methyl-4-isothiazolin-3-one (CIT), 2-methyl-4-isothiazolin-one (MIT), 1, 2-phenylpropylisothiazolinone (BIT), iodopropynyl carbamate (IPBC), 1, 3-dimethylol-5, 5-methylhydantoine (DMDMH).

8. The chemical mechanical polishing solution for silicon nitride according to claim 1, wherein the concentration of the bactericide is 0.02 to 0.2% by mass.

9. The silicon nitride chemical mechanical polishing solution according to claim 1, wherein the pH adjusting agent comprises HNO₃、KOH、K₂HPO₄Or KH₂PO₄One or more of (a).