CN113429974A

CN113429974A - BOE etching solution for composite film

Info

Publication number: CN113429974A
Application number: CN202110709036.7A
Authority: CN
Inventors: 戈烨铭; 何珂; 汤晓春
Original assignee: JIANGYIN RUNMA ELECTRONIC MATERIAL CO Ltd
Current assignee: JIANGYIN RUNMA ELECTRONIC MATERIAL CO Ltd
Priority date: 2021-06-25
Filing date: 2021-06-25
Publication date: 2021-09-24

Abstract

The invention relates to a BOE etching solution for a composite film layer, which comprises the following components in percentage by mass: 0.5-2% of hydrofluoric acid, 25-30% of ammonium fluoride, 0.004-0.01% of additive and 67.99-74.496% of ultrapure water, wherein the additive is n-octanoic acid. The BOE etching solution for the composite film layer can be used for a single base material and can also take account of the composite base material, and the CD lose and the required angle can be simultaneously taken account of by adjusting the surface tension.

Description

BOE etching solution for composite film

Technical Field

The invention belongs to the technical field of etching solutions, and particularly relates to a BOE etching solution for a composite film layer.

Background

Wet etching is an indispensable process in semiconductor processing, and a buffered oxide etching solution (BOE) is usually composed of ammonium fluoride, hydrofluoric acid, and water, and is used to remove the portion of the oxide layer not covered by the photoresist, so as to achieve the purpose of etching, where the oxide layer is typically NSG (non-doped Silicate Glass ), BPSG (Boro-phosphate Glass), or a composite layer of the above two.

The conventional BOE etching solution can only etch one oxide layer and cannot etch the composite layer substrate; the surface tension of the common BOE etching liquid is large, the wettability of the common BOE etching liquid to an etching layer is poor, and the etching pattern is seriously deformed, the surface tension is generally reduced by adding a surfactant into the BOE etching composition, so that the etching effect is improved, but the contact angle of the BOE etching liquid containing the surfactant to a base material is large, the capability of penetrating a complex microscopic surface is poor, and the regular and uniform etching pattern cannot be ensured.

Chinese patent CN201410764798.7 discloses an etching solution for a hydrogen peroxide system copper molybdenum alloy film, which comprises hydrogen peroxide accounting for 1-35% of the total mass of the etching solution, inorganic acid accounting for 0.05-5%, hydrogen peroxide stabilizer accounting for 0.1-5%, metal chelating agent accounting for 0.1-5%, etching additive accounting for 0.1-5%, surfactant accounting for 0.1-5% and defoaming agent accounting for 0.1-5%, and deionized water accounting for the balance, wherein the surfactant added in the etching solution has a large contact angle to a base material, has poor capability of penetrating a complex microscopic surface, cannot ensure the neat and uniform etching pattern, and needs to be additionally added with a defoaming agent to improve the performance.

Disclosure of Invention

The invention aims to provide a BOE etching solution for a composite film layer, which can be used for a single base material and can simultaneously take account of a composite base material, and can simultaneously take account of CD lose and a required angle by adjusting surface tension.

The technical scheme adopted by the invention for solving the problems is as follows: the BOE etching solution for the composite film layer comprises the following components in percentage by mass:

0.5-2% of hydrofluoric acid, 25-30% of ammonium fluoride, 0.004-0.01% of additive and 67.99-74.496% of ultrapure water, wherein the additive is n-octanoic acid.

Preferably, the hydrofluoric acid has a purity grade of UPS grade.

Preferably, the purity grade of the ammonium fluoride is UP grade.

Preferably, the resistance of the ultrapure water is not lower than 15M omega cm, and the salt content in the ultrapure water is not higher than 0.2 mg/L.

Preferably, the pH value of the BOE etching solution is 3-5.

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

(1) the BOE etching solution for the composite film layer can be used for etching not only a single oxide layer (NSG or BPSG) but also the composite oxide layer (NSG or BPSG composite layer), and can etch the film layer efficiently and accurately under mild working conditions.

(2) According to the invention, by controlling the addition amount of the n-octanoic acid, not only can the pH value of the etching solution be adjusted, but also the surface tension can be adjusted, and the CD lose and the required angle can be considered at the same time, so that the etching effect is improved; and the n-caprylic acid is added to effectively inhibit bubbles, so that a large amount of foam is not generated, and the influence on the use of a production line is avoided. .

Detailed Description

The present invention will be described in further detail with reference to examples.

Example 1

The BOE etching solution for the composite film layer comprises the following components in percentage by mass:

1% of hydrofluoric acid, 25% of ammonium fluoride, 0.006% of additive n-octanoic acid and the balance of ultrapure water.

Wherein, the purity grade of the hydrofluoric acid is UPS grade, the purity grade of the ammonium fluoride is UP grade, the resistance of the ultrapure water is 18M omega cm, and the salt content in the ultrapure water is 0.15 mg/L.

Example 2

1% of hydrofluoric acid, 25% of ammonium fluoride, 0.1% of additive n-octanoic acid and the balance of ultrapure water.

Wherein, the purity grade of the hydrofluoric acid is UPS grade, the purity grade of the ammonium fluoride is UP grade, the resistance of the ultrapure water is 17M omega cm, and the salt content in the ultrapure water is 0.1 mg/L.

Comparative example 1

The only difference from example 1 is: no additive n-octanoic acid was added.

Comparative example 2

The only difference from example 1 is: the addition amount of the additive n-octanoic acid is 0.2%.

Comparative example 3

The only difference from example 1 is: the additive was changed to butyric acid.

Etching experiments are carried out on NSG, BPSG and NSG/BPSG composite layers by the etching solutions prepared according to the formulas of the components in the examples 1-2 and the comparative examples 1-3 at the temperature of 23 ℃, wherein the defoaming property test experiment is as follows: placing the etching solution in a 100mL test tube, vertically oscillating for 30s, and measuring the height of the foam after stopping 60 s; the results of the experiments are shown in the following table:

note: the angle requirement after etching of the BOE etching solution is as follows: the angle after etching is less than 50 degrees.

As can be seen from the above table, the BOE etching solution of the present invention can be used for etching not only a single oxide layer (NSG or BPSG), but also a composite oxide layer (NSG, BPSG composite layer); the n-butyric acid is added to effectively play a role in defoaming, so that the influence of the foamability of the etching solution on the etching precision and the etching precision is reduced; from the etching results of example 1 and comparative example 2, only by controlling the amount of n-octanoic acid added within the range of the present application, both CD lose and the desired angle can be achieved, and the etching effect is good.

In addition to the above embodiments, the present invention also includes other embodiments, and any technical solutions formed by equivalent transformation or equivalent replacement should fall within the scope of the claims of the present invention.

Claims

1. The BOE etching solution for the composite film layer is characterized in that: the composite material comprises the following components in percentage by mass:

2. The BOE etching solution for the composite film layer according to claim 1, wherein: the additive is 0.004%.

3. The BOE etching solution for the composite film layer according to claim 1, wherein: the purity grade of the hydrofluoric acid is UPS grade.

4. The BOE etching solution for the composite film layer according to claim 1, wherein: the purity grade of the ammonium fluoride is UP grade.

5. The BOE etching solution for the composite film layer according to claim 1, wherein: the resistance of the ultrapure water is not lower than 15M omega cm, and the salt content in the ultrapure water is not higher than 0.2 mg/L.

6. The BOE etching solution for the composite film layer according to claim 1, wherein: the pH value of the BOE etching solution is 3-5.