JPS5855323A - Etching solution for silicon and silicon oxide film - Google Patents

Abstract

PURPOSE:To enable patterning of high accuracy by preparing a mixed soln. contg. hydrofluoric acid and a surfactant and by optionally adding acetic acid or nitric acid. CONSTITUTION:This etching soln. for silicon and silicon oxide films contains, by volume, 0.1-65%, especially 2-50% hydrofluoric acid and 0.01-5% surfactant. As the surfactant an anionic surfactant, a cationic surfactant, an amphoteric surfactant or a nonionic surfactant is used. To further increase the etching effect 0.05-95vol% acetic acid and/or nitric acid may be added to the etching soln.

Description

[Detailed description of the invention] Non-explosion is V9;n and S9=yy Oxide film O corrosion 11E
Regarding K.

Conventionally, as a corrosive solution for the F9 film/oxide film, heptahydrofluoric acid alone has been used, or a so-called buffer solution in which ammonium heptathide is mixed with heptahydrofuric acid has been used. The corrosive liquid made of hydrosulfuric acid is %49X1! ! (used in the diluted form with deionized water) or diluted with deionized water. Such corrosion ta, oxidation treatment and diffusion treatment in the manufacturing process of semiconductor devices! It is used in the IO pre-process. When the silicon substrate is removed from the corrosive solution during these treatments, the surface of the clean substrate is directly exposed to air due to its water-repellent nature. Tsutshi, Silicoy
The group 1[0 surface is in a solid/liquid phase 1! within a short time after being lifted from the corrosive liquid. Changes from l (silicon substrate, corrosive liquid) to solid/vapor phase (silicon substrate, atmosphere). The rounded gas and liquid phase (atmosphere/corrosive liquid) trapped in the dust and other contaminants easily adhere to the surface of the clean substrate. Moreover, once attached, these contaminants are
7. Adheres to the surface of the substrate with a large adhesive force due to OI class reaction. As a result, contaminants, etc. can be easily removed even if a nine-ilK cleaning machine is installed after removing the corrosive liquid.
was there.

The basic arrangement is to prevent O contaminants such as dust from adhering to the object to be treated with the above point K11l, and to create a clear putter with high shape accuracy. It is also O to provide an etchant of silicon and PI oxides that meet each other.

Hereinafter, it will be explained in detail.

The silico/and silico oxide film O etchant of the present invention is a mixed solution containing at least hydrochloric acid and a surfactant, and optionally one of acetic acid and nitric acid. It is also O when both of them are added.

The target objects to be processed are a substrate made of silicon and a silicon substrate.
'': = Yll film and p1 When the object to be processed is a silicon substrate, the above-mentioned mixed solution containing nitric acid is used.

For hydroaralic acid, α1~*SXO chain degree O is also used, and the sidetone in the mixed solution is preferably set in the range of -2~0% by volume to obtain a sufficient etching rate. .

Surfactants are used to sufficiently lower the surface tension of a corrosive liquid to exhibit lyophilic properties, and are used as additives in the mixed solution.
, αO is desirably set in the range of 1 to 5% by volume.

In addition, as a surfactant, carganic acid (R-C00H
), sulfuric acid ester (R-080,) (), sulfonic acid (R-80,H), phosphoric acid ester, 7c, ($-0P
OsH), Go's anionic surfactant, primary amine salt (R-NH1*HcJ), secondary amine salt (R-N
HCHfMal), tertiary amine salt (RN(CHs
) m Hc Emperor), quaternary ammonium salt (R-N (
CHs) * -CHm 4d'''') Cape's cationic surfactant, amino acid 11 (R-NHCH, CM, C0O
H), hein type (R-N(CHs)*-aH,co
Amphoteric surfactants such as "O") and borietheacetic acid have a synergistic effect with the surface tension lowering effect of surfactants.
Although it has the effect of separating fine particles such as ㅅ2 generated in 110ml from the object to be treated, the sidetone in the mixed solution is θ ~ 77 volume XO [O set by m desirable. Nitric acid exhibits an etch 71 effect when the object to be processed is a silicon substrate, and O
It is desirable to set the opening in the range of α05 to 95% by volume.

The surface tension of the etchant for silicon and silicon oxide films constructed in this way was investigated while changing the concentration of the etchant, and the results shown in the characteristic diagram (1) to button in FIG. 1 were obtained. In the same figure, the characteristic line (1) has a density of 60. %'O7 to 98 volumes of hydroturic acid and 2% by volume of nonionic surfactants.
The characteristic line of a corrosive liquid consisting of (the phantom line is 98 volume X of hydroheptatonic acid with a concentration of 49X and 2 volume % of a nonionic surfactant)
A corrosive liquid consisting of 'Characteristics [@] is 7-hydrogen water XI with a concentration of 60%! This figure shows the change in the o*ii* force of a corrosive liquid consisting of 80% by volume of 1, 1% by volume of anionic surfactant, and 19% by volume of acetic acid. Further, the characteristic (MQV) was investigated for comparison with the above-mentioned corrosive liquid and shows the change in surface tension of a conventional corrosive liquid consisting of 7-hydrofluoric acid with a concentration of 49N.

The liquid is the conventional corrosion shown by the characteristic line (5)! It can be seen that the material has a surface tension that is slightly smaller than that of the material, and can quickly remove contaminants such as dust that adhere to the surface of the object to be processed when it is etched. In particular, the characteristic line containing acetic acid (the corrosive liquid represented by Shu is 47 dYn
It can be seen that it has a surface tension of an extremely small value of e/an or less and exhibits lyophilic properties, making it extremely easy to remove contaminants and the like.

Next, an example of a single base will be explained. A silicon substrate having a silicon oxide film as an object to be treated is immersed for about 10 seconds in a 10% diluted solution of a silicon and silicon oxide film etchant according to the present invention having the following composition, and then removed from the etchant. Wash the surface with pure water, dry it in a dryer, and check the number of dust particles present on the surface of the silicon oxide layer, which is the object to be treated.
The results shown in (Example 1) and (1) (Example 2) were obtained. Further, the surface of the silicon oxide film O, which was the object to be processed, was patterned into a predetermined O pattern with extremely sharp clarity and high precision.

For comparison, 49X concentration of hydrochloric acid 09
A conventional corrosive solution consisting of 8% by volume and 2 volumes of acetic acid (Comparative Example 1) and a conventional corrosive solution consisting of 7-hydrofluoric acid with a concentration of 49N (Comparative Example 2) were used to oxidize the object to be treated. The film was subjected to an etching treatment and the number of dust particles remaining after the treatment was examined, and the results shown by the characteristic line (Zl)-(Zm) in the same figure were obtained. After treatment O silicon W)/Oxide film O
* wa, adhesion of O contaminants such as garbage, 〇〇〇〇〇), and the prescribed 0Ap-yFcAfi-1y/〇〇〇.

It is clear from the figure that Example 1. ! J61 with 0 corrosion wave
On the other hand, almost no dust particles of all sizes from O to 40 or more remained on the surface of the treated footwear body treated with the corrosive solution of Comparative Example 1.2. It can be seen that many dust particles of 5μ or less remain on the surface.

Composition of etchant in Example 1 Composition of etchant in Example 2 As explained above, the etchant for silicon and silicon oxide films of the present invention prevents contaminants such as dust from adhering to the surface of the object to be treated. It is possible to prevent this from occurring and perform a clear butter-aging process with extremely high shape accuracy.

[Brief explanation of drawings]

Fig. 1 is a characteristic diagram showing the relationship between the quality and surface tension of silicon and V9 oxidized corrosive liquids, and Fig. 2 is a graph showing the relationship between the size of Z particles remaining after treatment and the number of G particles. It is a characteristic diagram showing a relationship.

Claims (1)

[Claims] (1) A silicon oxide film corrosive solution comprising a mixed solution containing at least 7 hydrofluoric acid and a surfactant. (Salmon: Either acetic acid or nitric acid - St9 is a corrosion wave of silicon and silylan oxide film described in claim 1, in which both are contained in the mixed solution. False) The field active agent is an anion. % of surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants
Claim 1, which is any of /-&, refers to the silicon and V oxide film O etchant described in Claim 2.