JPS62115833A - Surface treating agent for semiconductor substrate - Google Patents

Abstract

PURPOSE:To obtain a semiconductor substrate surface treating agent which has excellent treating capacity of the surface of a semiconductor substrate at ambient temperature and no contamination by the secondary absorption of an impurity by adding a specific amount of ethylene diamine tetraacetate to an aqueous alkaline solution. CONSTITUTION:0.001-10wt% of ethylene diamine tetraacetate (EDTA) is added to an aqueous alkaline solution. EDTA is used as a cheleting agent for originally reacted with all of metal ions, alkaline ions to form a stable chelete compound. If the content of EDTA is less than 0.001, no effect is obtained, and if the content exceeds 10%, it unpreferably etches the substrate. Hydrogen peroxide water may be added as desired to a semiconductor substrate surface treating agent. The agent can clean the surface of the substrate, and has no contamination by the secondary absorption of an impurity and by absorption of component substance of the agent to the substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor substrate surface treatment agent that modifies the surface of a semiconductor substrate.

[Conventional technology]

Currently, most semiconductor devices such as ICs are silicon devices, and these silicon wafers are manufactured through processes such as a vapor phase growth process, an oxide film formation process, an impurity diffusion process, and an electrode metal film deposition process.

Since the properties of semiconductors are significantly affected by the presence of impurities, the silicon wafer surface must be cleaned and protected from contamination by impurities before each of the above steps. The basic industrial method consists of three steps: a degreasing step, an acid treatment step, a dilute hydrogen fluoride water treatment step, and a drying step. In the acid treatment step, oxidizing @
'2! Nitric acid is conventionally used as the acid treatment agent.

However, when oxidizing acid treatment such as nitric acid treatment is performed, a very thin oxide film is often formed on the silicon surface, and this oxide film has the problem of making it easy to incorporate impurities.

In addition, impurities can be removed relatively easily by treating metals with dilute hydrogen fluoride water, but light elements remaining on the silicon surface, especially alkaline components, are difficult to remove. No treatment agent has been found to remove it.

In addition, in the conventional surface treatment process for semiconductor substrates, in order to improve treatment efficiency, it is necessary to heat the treatment agent to around 100°C, and furthermore, the treatment ability does not last long due to deterioration of the treatment agent, and its oxidation The chemical effects such as adsorption and desorption and the removal efficiency of the targeted removal substances are unclear, and depending on the type of processing agent, contamination due to secondary adsorption of impurities may occur on the surface of the semiconductor substrate.

[Problem that the invention seeks to solve]

The present invention has been made to solve these problems, and provides a semiconductor substrate surface treatment agent that exhibits excellent semiconductor substrate surface ρ treatment ability at room temperature and is free from contamination due to secondary adsorption of impurities. With the goal.

[Means for solving problems]

The present invention relates to a semiconductor substrate surface treatment agent characterized in that 0.001 to 10% by weight of ethylenediaminetetraacetic acid is added to an alkaline aqueous solution.

〔Example〕

The alkaline aqueous solution used in the present invention may be one that has been conventionally used as a surface treatment agent for semiconductor substrates, such as an ammonium hydroxide aqueous solution.

The concentration of the alkaline aqueous solution varies depending on the type of semiconductor substrate used or the type of alkali, but is usually 1 to 1.
It is used in a 20% (wt%) aqueous solution.

Ethylenediaminetetravinegar used in the present invention 8! (Hereafter, ED
TA) is originally used as a chelating reagent that reacts with all metal ions and alkali ions to form stable chelate compounds. Mix and use as desired.

If the content of EDT^ is less than 0.001%, there is no effect, and if it exceeds 10%, the semiconductor substrate will be etched, which is not preferable.

The semiconductor substrate surface treatment agent of the present invention thus obtained includes:
Hydrogen peroxide solution or the like may be added if desired.

The semiconductor substrate surface treatment agent of the present invention is at air temperature (20 to 80°C).
It can be used by dipping the semiconductor substrate in it or by spraying the processing agent thereon.

Next, the semiconductor substrate surface treatment agent of the present invention will be explained based on Examples, but the present invention is not limited to these Examples.

Example 1 Using 0.6 Q of a 5% ammonium hydroxide aqueous solution as an alkaline aqueous solution, 3.5 g of EDTA was dissolved in the aqueous solution to obtain a semiconductor substrate surface treatment agent.

Metal ion removal ability of the obtained semiconductor substrate surface treatment agent,
The ability to remove alkali ions and the presence or absence of surface adsorbed substances were investigated using the following methods. The results are shown in Table 1.

(Metal ion removal ability) A very thin layer of N was deposited on the surface of a silicon semiconductor substrate, and the substrate was immersed in a semiconductor substrate surface treatment agent.

The obtained semiconductor substrate was irradiated with ultraviolet rays, the energy of the emitted photoelectrons was analyzed, the difference in work function was examined, and the ability to remove metal ions was determined according to the following criteria.

(Judgment criteria) O: work function shifts to higher side △: work function does not change ×: work function shifts to lower side (alkali ion removal ability) Na2CO3 is applied to the surface of a silicon semiconductor substrate, and was immersed in a semiconductor substrate surface treatment agent. The obtained semiconductor substrate was irradiated with ultraviolet rays, the energy of the emitted photoelectrons was analyzed, the difference in work function was examined, and the alkali ion removal ability was determined according to the following criteria.

(Judgment criteria) O: Work function shifts to lower side △: Work function does not change ×: Work function shifts to higher side (presence of surface adsorbed substance) A silicon semiconductor substrate is placed on the surface of a semiconductor substrate containing impurities. Immersed in processing agent. The resulting semiconductor substrate was irradiated with ultraviolet rays, the energy of the emitted photoelectrons was analyzed to determine the difference in work function, and the presence or absence of surface adsorbed substances was determined using the following criteria.

(Judgment criteria) ○: Shift to lower work function i ~ Δ: Work function does not change ×: Shift to higher work function Comparative example 1 N as a conventionally used semiconductor substrate surface treatment agent
Metal ion removal ability, alkali ion removal ability, and the presence or absence of surface adsorbed substances were investigated in the same manner as in Example 1 using a tliOH-H202-based product. The results are shown in Table 1.

Comparative Example 2 Using dilute hydrogen fluoride water as a conventionally used semiconductor substrate surface treatment agent, the ability to remove metal ions, the ability to remove alkali ions, and the presence or absence of surface adsorbed substances were investigated in the same manner as in Example 1. The results are shown in Table 1 [Effects of the Invention] The semiconductor substrate surface treatment agent of the present invention can purify the surface of a semiconductor capping plate at room temperature, is free from contamination due to secondary adsorption of impurities, and can be used to clean the surface of a semiconductor substrate. This has the effect of eliminating contamination due to adsorption of constituent substances of the processing agent onto the semiconductor substrate.

Claims (1)

[Claims] (1) Add 0% ethylenediaminetetraacetic acid to an alkaline aqueous solution.
．． A semiconductor substrate surface treatment agent characterized in that 0.001 to 10% by weight is added.