KR20190096785A - High selectivity Etchant composition for Nitride etching - Google Patents

Abstract

The present invention relates to a high selection ratio etching composition for etching a silicon nitride film, which is used to etch and remove the silicon nitride film in a semiconductor process, and is for producing a semiconductor in which the etching rate of the silicon nitride film is higher than that of a silicon oxide film in a high temperature etching process. According to the present invention, the high selection ratio etching composition selectively etches the silicon nitride film of the laminated silicon nitride film and the laminated silicon oxide film, that is, the damage and the etching rate to the silicon oxide film are minimized and the collapse phenomenon of a laminated structure according to the process time does not occur, while etching the same at a select ratio of 2000 : 1 or more.

Description

High selectivity Etchant composition for Nitride etching for silicon nitride film etching

The present invention relates to an etching composition for a silicon nitride film, which is used to etch away and remove a silicon nitride film in a semiconductor process, and in the high temperature etching process, the silicon nitride film etching for semiconductor manufacturing, which has a higher etching rate than the silicon oxide film in a high temperature etching process. It relates to a high selectivity etching composition for.

The semiconductor manufacturing process requires a laminated structure formation technology that can continuously increase the degree of integration through the introduction of a three-dimensional structure. In the semiconductor manufacturing process, the silicon oxide film (SiO 2) and the silicon nitride film (SiNx) are representative insulating films, respectively, or one or more layers are alternately stacked, and the oxide film and the nitride film form conductive patterns such as metal wirings. It is also used as a hard mask for forming. The silicon nitride film and the silicon oxide film are main insulating films forming a stacked structure for forming a three-dimensional NAND flash memory gate.

In order to form the stacked structure, the silicon nitride layer may be removed by, for example, a wet etching process using an etchant containing phosphoric acid or an etching composition. In addition, according to the needs of forming various patterns included in the semiconductor device, a selective etching process of the silicon nitride film may be required. Therefore, there is a need for a highly selective etching composition for selectively etching the silicon nitride film with respect to the silicon oxide film.

In patent document 1, the nitride film etching liquid of the semiconductor element containing phosphoric acid and hydrofluoric acid is disclosed. However, when the hydrofluoric acid is included in the etching solution, the silicon oxide film is also removed, so that a sufficient etching selectivity of the nitride film is not obtained from the oxide film. There is a problem.

In addition, in the wet etching process for removing the nitride film, a mixture of phosphoric acid and deionized water is generally used. The deionized water is added to prevent the decrease of the etching rate and the change of the etching selectivity to the oxide film, but there is a problem in that the nitride film etching process is defective even in the slight change of the amount of deionized water supplied. In order to solve this problem, a technique of removing a nitride film using a etching composition including hydrofluoric acid or nitric acid in phosphoric acid has been known in the related art, but has resulted in inhibiting the etching selectivity of the nitride film and the oxide film.

In patent document 2, the composition for silicon nitride film etching which contains oxime silane in phosphoric acid is disclosed. However, the composition has a low solubility, there is a problem that the particles are adsorbed, generated on the semiconductor substrate or silicon oxide film.

In order to solve this problem, a conventional technique of increasing the selective etching rate by using an additive which inhibits the etching of the silicon oxide film, that is, a silicon oxide film etch inhibitor or a silicon nitride film etch increasing agent such as silicate, fluorosilicate or fluorosilicate, has been studied. In 3, an etching composition including phosphoric acid, a silicon-fluorine compound including a silicon-fluorine bond, a sulfonylimide-based adsorption inhibitor, a polymer-based adsorption inhibitor, and water as a nitride film etching composition is disclosed. However, there is a problem that the silicon concentration in the composition is increased by the additive, and the silicon oxide film is regrown over time.

1. Republic of Korea Patent Publication 10-2005-0003163 2. Korean Patent Publication No. 10-2011-0037741 3. Korean Patent Publication No. 10-2013-0068952

In order to solve the above problems, the present invention is to etch the silicon nitride film of the silicon nitride film and the silicon oxide film laminated at a selectivity of 2000: 1 or more, to minimize the damage and etching speed to the silicon oxide film and collapse of the laminated structure according to the process time To provide a high selectivity etching composition for the silicon nitride film etching does not occur.

In order to achieve the above object, the present invention does not cause regrowth of silicon oxide film and damage of silicon oxide film even after process time, and has developed a high selectivity etching composition of silicon nitride film capable of etching silicon nitride film at a constant rate. The present invention provides a composition for high selectivity etching of a silicon nitride film comprising a compound represented by the following formula (1), phosphoric acid, a silicon compound, an amino acid compound and water.

[Formula 1]

In addition, the present invention is a silicon nitride film containing 60 to 85% by weight of phosphoric acid, 0.05 to 5% by weight of the compound, 0.001 to 5% by weight of the amino acid compound, 0.005 to 1% by weight of the silicon compound and the residual amount of water relative to the total weight Provided is a composition for etching selectivity.

The etching composition is characterized by selectively etching the silicon nitride film with respect to the silicon oxide film.

In addition, according to an embodiment of the present invention, the selectivity of the silicon nitride film etching rate with respect to the silicon oxide film etching rate provides a high selectivity etching composition for silicon nitride film etching of more than 2000: 1.

According to the present invention, the high selectivity etching composition is a silicon nitride film etch rate compared to the silicon oxide film etch rate of the silicon nitride film and the silicon oxide layer is etched at a select ratio of 2000: 1 or more, and minimizes damage and etching rate to the silicon oxide film The stack structure collapse does not occur according to the process time, so that the silicon nitride film may be effectively etched in a process requiring selective etching.

Hereinafter, the etching composition of the silicon nitride film with respect to the silicon oxide film according to a specific embodiment of the present invention will be described in more detail with respect to the etching composition for manufacturing a semiconductor. However, this is presented as an example of the invention, whereby the scope of the invention is not limited, it is apparent to those skilled in the art that various modifications to the embodiments are possible within the scope of the invention. In the following Examples and Comparative Examples, unless otherwise indicated, the component ratio of the composition is calculated by weight ratio. The etching rate expressed in the embodiments and drawings of the present invention is not a numerical value proportional to the etching composition evaluation time, and the etching rate and the selectivity may be expressed differently in an environment other than the evaluation conditions presented.

Preparation of Etching Composition

Each embodiment for achieving the object of the present invention includes phosphoric acid and water as a compound, a silicon compound, an amino acid and a solvent represented by the formula (1).

[Formula 1]

According to each embodiment the etching composition is a solvent based on 60 to 85% by weight of the total composition, 0.05 to 5% by weight of the compound, 0.001 to 5% by weight of the amino acid compound, 0.005 to 1% by weight of the silicon compound and the remaining content Contains with water.

In the following examples and comparative examples, unless otherwise stated, the remaining weight of the composition is calculated by adding water. For example, in the preparation and performance evaluation of the etching composition, the content of the total composition reference phosphoric acid should be kept constant at all times in order to compare the performance evaluation of the remaining composition except for the phosphoric acid content in the etching composition.

Phosphoric acid serves as the main etching component for the nitride film etching, 60 to 85% by weight of phosphoric acid based on the total composition. When phosphoric acid is included in less than 60% by weight, the removal of the silicon nitride film is insufficient, the overall etching rate may be lowered. There is also a risk of particle generation. On the other hand, when phosphoric acid is included in excess of 85% by weight, it is difficult to expect any further increase in effect as the content increases.

When the etching composition further includes the compound of Chemical Formula 1, the etching rate of the silicon nitride film is lowered even after using the etching composition for a long time, thereby maintaining the structure of the silicon oxide film forming a laminated structure even after using for a long time. In addition, as a result of the long-term etching evaluation, the selectivity of the silicon nitride film according to the silicon oxide film continues to increase.

Preferably, the compound is contained in an amount of 0.05 to 5% by weight, and when the compound is added in an amount of less than 0.05% by weight, the effect of increasing the selectivity over long periods of use decreases, and the compound exceeds 5% by weight. In the case of addition, the etching rate of the silicon nitride film and the silicon oxide film is changed, so that the selectivity may be changed. More preferably, the compound is contained in 0.25 to 5% by weight.

The silicon compound may be hexafluorosilicate, aluminum silicate, calcium silicate, tetraethylorthosilicate, tetraethyl orthosilicate, tetramethyl orthosilicate, silicate, Sodium fluorosilicate, Sodium hexafluorosilicate, 3-aminoproply trimethoxysilan, Aminoethylaminotrimethoxysilan, Dichlorosilane (Dichlorosilan). Since the silicon compound is contained in 0.005 to 1% by weight, when the silicon compound is added in an amount less than 0.005% by weight, a high etching selectivity with respect to the silicon nitride film cannot be obtained, and the silicon compound is added in excess of 1% by weight. In this case, it is difficult to expect a further effect increase according to the increase in content, rather there is a problem that particles are generated. More preferably, the silicone compound is added at 0.005 to 0.5% by weight.

The amino acid compound may be Arginine, Histidine, Lysine, Serine, Serine, Threonine, Asparagine, Glutamine, Alanine, Valine, Valine, etc. Isoleucine, Leucine, Methionine, Phenylalanine, Tyrosine, Tryptophan, Cysteine, Selenocysteine, Glycine, Proline Proline), Aspartic Acid (Aspartic Acid), Glutamic Acid, 3-Trifluoroalanine (3-Trifluoroalanine) is selected from, and serves to protect the silicon nitride film which is an insulating film laminated with a silicon oxide film. The use of a corrosion inhibitor generally used significantly lowers the selective etching characteristics of the silicon nitride film of the ammonium compound ,, and conversely, protection of the silicon oxide film is not achieved unless the etching characteristics of the silicon nitride film are lowered. However, in the case of using the amino acid compound, re-growth of the silicon oxide film can be suppressed by capturing cyclic ions by etching the silicon nitride film, thereby improving the surface state of the silicon oxide film.

Amino acid compound is preferably used in 0.001 to 5% by weight relative to 100% by weight of the total composition. If the amino acid compound is used in an amount less than 0.001% by weight, the protection performance of the silicon oxide film is lowered, and when the amino acid compound is added in an amount of more than 5% by weight, not only the improvement effect on the protection performance is insufficient but also the silicon. The etching performance of the nitride film can be reduced. More preferably the amino acid compound contains 2 to 5% by weight.

The high selectivity etching composition of the silicon nitride film is to selectively etch the silicon nitride film with respect to the silicon oxide film, the selectivity ratio of the silicon nitride film etching rate to the silicon oxide film etching rate is more than 2000: 1, silicon nitride film without damaging the silicon oxide film Etch selectively. The excess water included in the etching composition includes, for example, distilled water or deionized water (DIW), and may be included as a residual amount of the composition.

Evaluation of Etching Speed and Laminated Structure of Etching Composition

Each embodiment according to the present invention evaluates the etching rate using a composition for etching, including phosphoric acid, the compound of Formula 1, silicon compound, amino acid and water as a solvent.

The amount of the composition for etching is added to 300g and the temperature is increased to 157 ° C, and then the content of the phosphoric acid is maintained to be constant. The silicon nitride film wafer for etching rate is manufactured with a specimen having a thickness of 5000 제조 and a specimen having a width of 1 cm and a length of 4 cm for evaluation, and measures the thickness before and after etching. The silicon oxide wafer for etching rate measurement is a wafer having a thickness of 10,000 제조 and manufactured with specimens having a width of 1 cm and a length of 4 cm for evaluation, and measures the thickness before and after the etch evaluation time of 30, 300 and 1000 minutes. The etching rate is measured by adding a silicon nitride film and a silicon oxide film to the etching composition that reaches a steady state. The etching rate of the silicon nitride film and the silicon oxide film is calculated as the etching rate per minute, and the selection ratio is calculated as the ratio of the silicon nitride film etching rate to the silicon oxide film etching rate.

[A: etching rate of silicon nitride film, B: etching rate of silicon oxide film, C: selectivity]

In the following Examples and Comparative Examples, the evaluation of the laminated structure morphology is performed by etching the self-provided laminated structure wafer and using a scanning electron microscope to give a state average score from 1 to 10 step by step. The evaluation criteria of the laminated structure morphology are given a step score based on the slope and shape of the laminated structure and the thickness of the silicon oxide film. In the following step score, 1 indicates the state in which the state of the silicon nitride film is thin and the laminated structure is collapsed, and 10 indicates the state in which the laminated structure is best maintained.

Comparative Example 1

The etching rate was measured using an etching composition having 83 wt% phosphoric acid, and the reduction rate of the silicon oxide film etching rate was 5.25, 4.92, 3.88 Å / min at 124 Å / min and 30, 300 and 1000 minutes, respectively. In addition, the selectivity was low, the thickness of the silicon oxide film of the laminated structure was thin, and the structure was inclined.

Example 1

An etching composition having a composition of 83% by weight phosphoric acid, 0.13% by weight compound of formula 1, 1% by weight alanine, 0.1% by weight silicone compound was prepared. As a result of etching rate measurement using the composition according to Example 1, the silicon oxide film etch rate was 2.08, 0.88, 0.36 Å / min at 129 Å / min and 30, 300 and 1000 minutes for silicon nitride, respectively. Although it was reduced, the selectivity was low, the thickness of the silicon oxide film of the laminated structure was slightly thinner, and the structure was inclined.

Example 2

An etching composition having a composition of 83% by weight of phosphoric acid, 0.13% by weight of a compound of Formula 1, 1% by weight of alanine, and 0.3% by weight of a silicon compound was prepared. As a result of etching rate measurement using the composition according to Example 2, the silicon oxide film compared to Comparative Example 1 and Comparative Example 2 was 1.12, 0.71, 0.21 Å / min at 119 Å / min and 30, 300 and 1000 minutes of silicon nitride. Although the etching speed was reduced, the selectivity was low (100-600) and the state of the laminated structure was partially improved.

Example 3

An etching composition having a composition of 83% by weight phosphoric acid, 0.13% by weight compound of formula 1, 1% by weight alanine, 0.5% by weight silicone compound was prepared. As a result of etching rate measurement using the composition according to Example 3, the silicon oxide film etch rate was 0.21, 0.15, 0.07 Å / min at the silicon nitride film 124 Å / min and the silicon oxide film 30, 300 and 1000 minutes, respectively. As a result of 1000 minutes evaluation, the silicon nitride etching rate was higher than that of silicon oxide (1700: 1). However, although there was no collapse of the laminated structure, regrown particles were found on the surface of the silicon oxide film.

Example 4

An etching composition having a composition of 83% by weight of phosphoric acid, 0.25% by weight of a compound of Formula 1, 1% by weight of alanine, and 0.1% by weight of a silicon compound was prepared. As a result of etching rate measurement using the composition according to Example 4, the silicon oxide film etch rate was 0.16, 0.09, 0.03 Å / min at the silicon nitride film 127 Å / min and the silicon oxide film 30, 300 and 1000 minutes, respectively. Significantly reduced. As a result of 1000 minutes evaluation, the etch rate selection ratio of silicon nitride to silicon oxide was very high at 4233: 1, and there was almost no inclination of the stacked structure than Examples 1, 2, and 3, and the thickness of silicon oxide film was appropriate. The step score was low due to the silicon oxide surface condition. Comparing Example 1 and Example 4, it can be proved that the increase of the compound significantly lowers the etching rate of the silicon oxide film.

Example 5

An etching composition having a composition of 83% by weight of phosphoric acid, 0.25% by weight of a compound of Formula 1, 1% by weight of alanine, and 0.3% by weight of a silicon compound was prepared. As a result of etching rate measurement using the composition according to Example 5, the silicon oxide film etch rate was 0.09, 0.04, 0.02 Å / min at the silicon nitride film 128 Å / min and the silicon oxide film 30, 300 and 1000 minutes, respectively. The etch rate selection ratio of silicon nitride to silicon oxide was increased to 6400 to 1 as a result of 1000 minutes evaluation. In addition, as a result of evaluating the laminated structure, compared with Examples 1, 2, and 3, there was little inclination and the thickness of the silicon oxide film was also appropriate. Compared to Example 2, Example 3 and Example 5, the surface state of the silicon oxide film is better than Example 2, compared to Example 3, and Example 5 is good, so that the compound and alanine increase are effective in improving the silicon oxide film surface state. You can prove that there is.

Example 6

An etching composition having a composition of 83% by weight of phosphoric acid, 0.25% by weight of a compound of Formula 1, 1% by weight of alanine, and 0.5% by weight of a silicon compound was prepared. The etching rate of the composition according to Example 6 was 0.11, 0.05, 0.03 Å / min in silicon nitride film 112 Å / min, silicon oxide film 30, 300, and 1000 minutes, respectively. Although the etching rate of oxide was significantly reduced, the etching rate of silicon nitride film was also dropped by about 10 ~ 20Å / min. Nevertheless, due to the significantly lower silicon oxide etching rate, the selection ratio of 1000 minutes was 3700: 1 or higher. Compared with Examples 1, 2, and 3, the stacking structure has almost no inclination, and the effect is improved. Compared with Example 5, regrown particles or uneven surfaces are identified on the surface of the silicon oxide film. Could.

Table 1 shows the etch rate and the stacked structure state of the silicon nitride film, silicon oxide film of the Examples and Comparative Examples according to the present invention.

When a certain amount of phosphoric acid, a compound of Formula 1, alanine, and a silicon compound are included in the content ratio according to the present invention, a low level of silicon oxide film may be realized in comparison with Comparative Examples 1 and 2. The etching rate of the silicon oxide film is inversely proportional to the content of the silicon compound, which may lead to a high selectivity of the silicon nitride film etching rate. In each embodiment, as the silicon oxide film etch rate with time is shown, as the evaluation time increases, the etching rate of the silicon oxide film is significantly reduced, which leads to high selectivity of the high silicon nitride film etch rate. In addition, despite the long evaluation time, the laminated structure does not collapse or the thickness of the silicon oxide film is kept thin and maintains its shape. As shown in the comparison between Example 1 and Example 4, Example 2 and Example 5, Example 3 and Example 6, the increase of the alanine content of the compound and the amino acid compound inhibits silicon oxide film surface regrowth and stacks The state of the structure can be protected more reliably.

According to the present invention, the etching composition including phosphoric acid, a compound of Formula 1, a silicon compound, an amino acid compound, and a solvent water may be formed in a process to realize a selectivity ratio of silicon nitride film etching rate to silicon oxide film etching rate over 2000: 1. Ideally, the shape of the stacked structure to be produced can be realized.

Claims (5)

A composition for etching a silicon nitride film comprising a compound represented by the following Chemical Formula 1, phosphoric acid, a silicon compound, an amino acid compound, and water, and selectively etching the silicon nitride film with respect to the silicon oxide film.
[Formula 1]

The method of claim 1,
For etching the silicon nitride film, which comprises 60 to 85% by weight of phosphoric acid, 0.05 to 5% by weight of the compound, 0.001 to 5% by weight of the amino acid compound, 0.005 to 1% by weight of the silicon compound and the remaining amount of water. Composition.
The method of claim 1,
The silicon compound may be hexafluorosilicate, aluminum silicate, calcium silicate, tetraethylorthosilicate, tetraethyl orthosilicate, tetramethyl orthosilicate, silicate, Sodium fluorosilicate, Sodium hexafluorosilicate, 3-aminoproply trimethoxysilan, Aminoethylaminotrimethoxysilan, Dichlorosilane (Dichlorosilan) The composition for etching silicon nitride film, characterized in that selected from.
The method of claim 1,
The amino acid compound may be Arginine, Histidine, Lysine, Serine, Serine, Threonine, Asparagine, Glutamine, Alanine, Valine, Valine, etc. Isoleucine, Leucine, Methionine, Phenylalanine, Tyrosine, Tryptophan, Cysteine, Selenocysteine, Glycine, Proline Proline), aspartic acid (Aspartic Acid), glutamic acid (Glutamic acid), 3-trifluoroalanine (3-Trifluoroalanine), the composition for etching silicon nitride film.
The method of claim 1,
The composition of claim 1, wherein the selectivity ratio of the silicon nitride film etching rate to the silicon oxide film etching rate is 2000: 1 or more.