JP3274834B2 - Surface treatment method and treatment agent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a surface treatment agent for improving the cleaning of semiconductor and LCD surfaces. Specifically, silicon, germanium, Ga-As, Ga-P, which are commonly used in the manufacture of semiconductors, integrated circuits, LCDs, etc.
Used for cleaning treatment such as removal of organic substances, fine particles, and metal contamination on at least one surface of the surface of a compound semiconductor such as a semiconductor and a film surface or a glass substrate in contact with the semiconductor to improve surface cleaning and improve product yield. And an improved surface treatment agent.

[0002]

2. Description of the Related Art At present, most semiconductor devices such as LSIs, ICs, diodes, rectifiers, etc. are silicon devices, and these are vapor phase growth, oxide film formation, impurity diffusion, electrode metal film deposition on a silicon wafer. It is manufactured by adding such steps.

[0003] Since contamination by impurities significantly affects the electrical characteristics of a semiconductor, it is necessary to sufficiently clean the surface of a silicon wafer to remove the contamination before each of the above steps. The industrial methods vary widely depending on the type of chemical solution used, the processing temperature, etc.
A series of processes called A cleaning (RCA Review, P187-206, June (1970), etc.) is widely used, and is the backbone of wet cleaning.

That is, organic contamination and some metals such as Cu and
[Ammonia + Hydrogen peroxide + Water] treatment (SC
-1 treatment), a dilute HF treatment for removing a natural oxide film, and a [hydrochloric acid + hydrogen peroxide + water] treatment (SC-2 treatment) with a remarkable metal contamination removing effect.

The RCA cleaning schedule that has been generally used is SC-1 processing → dilute HF processing → SC-2 processing.
In the process, the wafer is susceptible to particle contamination, and in the SC-2 process, the ability to remove particles is weak. With ultra-high integration of LSIs, device patterns have rapidly become finer, and the size of fine particles that make devices defective have also become extremely finer. The smaller the particles, the greater the adhesion to the wafer and therefore the more difficult it is to remove, and the manufacturing yield is strongly dependent on the ability to remove particulate contamination during cleaning. Thus, attempts have been made to make SC-1 processing the last in the cleaning schedule. However, it is known that the wafer subjected to such cleaning has a problem in electrical characteristics such as a decrease in recombination lifetime and a decrease in oxide film breakdown voltage.

[0006] When metal impurities contaminate the silicon wafer surface, these electrical characteristics deteriorate. Metals detected on the wafer surface after SC-1 processing are Fe, Al, Ca, M
g and Zn. Such contaminant elements were contaminated from the equipment in the process before entering the cleaning, or were contaminated from the environment and could not be removed with the cleaning ability of SC-1,
What is present in the chemical liquid in the processing liquid is the amount adsorbed on the wafer.

[0007] Elements that are difficult to clean are generally elements that are easily adsorbed to the wafer. In SC-1, Fe and Al have a remarkable tendency as compared with other elements. At mass production factories, the cleaning equipment emphasizes productivity, so a tact method is used in which wafers in carriers are sequentially sent to the cleaning tank.However, in the SC-1 processing tank, contaminant elements eluted during cleaning gradually accumulate. Influences adsorption contamination on subsequent wafers. Also, unless very high purity ammonia or hydrogen peroxide is used, adsorption contamination due to impurities in the chemical solution occurs. In particular, metal such as Al is used for production and storage of hydrogen peroxide, and therefore requires precise purification for semiconductors. Furthermore, these high-purity chemicals have a risk of contamination even in a chemical supply system for a transport container or a cleaning tank, and it is not easy to maintain a high-purity chemical in the cleaning tank.

[0008] In a normal SC-1 treatment after wafer Fe 10 ¹¹ -
10 ¹² atoms / cm ² approximately, Al is ^{1011 1 3} atoms / cm ² approximately, C
For a, Mg, Zn, etc., contamination of about 10 ¹⁰ to 10 ¹¹ atoms / cm ² is observed. It has been found that the effect of these metal contaminations on the electrical characteristics can be ignored at an oxide film withstand voltage and a lifetime at such a concentration except for Fe. Therefore, the element that significantly impairs the electrical characteristics in the SC-1 treatment is Fe. Although the influence of Fe on the lifetime is remarkable in the P-type region, the decrease in the lifetime is negligible at 10 ¹⁰ atoms / cm ² or less.
In addition, the time-dependent destruction test (TDDB characteristic) of the oxide film also requires that Fe be 10 ¹⁰ atoms / cm to reach the intrinsic destruction time of a non-contaminated wafer.
^It is necessary to reduce the concentration to about ² . It was extremely difficult to obtain such a high degree of cleanliness by SC-1 treatment alone.

As a cleaning method similar to SC-1, a method using an organic alkali + hydrogen peroxide is known. Tetramethylammonium hydroxide (TMAH) + hydrogen peroxide (JP-A-50-147284), trialkyl (hydroxyalkyl) ammonium hydroxide + hydrogen peroxide
No. 53-43012), all of which are excellent in the ability to remove fine particles, which is a feature of [alkali + hydrogen peroxide] treatment, like SC-1, but have high adsorption of Fe, Al, etc. from the treatment liquid, Therefore, the cleaning power for a wafer contaminated with Fe, Al or the like is not sufficient. The method of capturing metal impurities as a stable water-soluble complex salt and inactivating it against the object to be cleaned is a common practice in formulating general cleaning agents, and there is an example in which a complexing agent is added to TMAH + hydrogen peroxide. JP-A-50-158281 discloses an example in which trialkyl (hydroxyalkyl) ammonium hydroxide is added to hydrogen peroxide.
No. 377. In all cases, the addition amount of the complexing agent is required to be 0.01% by weight or more, but the addition of a cyanide complexing agent is dangerous, and 100 ppm of organic substances such as EDTA (ethylenediaminetetraacetic acid) and triethanolamine are added. Then, harmful carbon contamination occurs on the silicon surface, causing a problem in electrical characteristics. It is known that Al contamination on the silicon surface affects the growth rate of the oxide film during thermal oxidation, which is not preferable in terms of precise control of the process.

As described above, [alkali + hydrogen peroxide] cleaning, which is very effective for particulate contamination, has an insufficient cleaning effect on harmful metals such as Fe and Al and is an effective means for solving the problem. Has not been found yet.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the conventional alkaline surface treating agents, to suppress metal contamination due to adsorption from a treating solution, and to provide an improved surface treatment having a high cleaning effect. An object of the present invention is to provide an agent and a surface treatment method.

[0012]

According to the present invention, a semiconductor surface is washed with a semiconductor surface treating agent containing inorganic or organic alkali, hydrogen peroxide and water as main components, and the semiconductor is rinsed with ultrapure water after the washing. A condensed phosphoric acid or a salt thereof in at least one of the semiconductor surface treating agent and the ultrapure water for rinsing.
Is an invention of a method for performing the method.

Further, the present invention is an invention of a semiconductor surface treating agent comprising an inorganic or organic alkali, hydrogen peroxide, water and condensed phosphoric acid or a salt thereof .

Further, the present invention relates to a method of mixing condensed phosphoric acid or a salt thereof in one or more of the components constituting the semiconductor surface treating agent and then mixing the components or mixing the components constituting the semiconductor surface treating agent. The invention is a method for preparing the above-mentioned semiconductor surface treating agent, which is prepared by mixing and then adding a condensed phosphoric acid or a salt thereof .

Further, the present invention is an invention of an alkaline aqueous solution for a semiconductor surface treating agent containing condensed phosphoric acid or a salt thereof . Still further, the present invention is an invention of a hydrogen peroxide solution for a semiconductor surface treating agent, which comprises condensed phosphoric acid or a salt thereof after a purification treatment by distillation and further removal of metal impurities.

Further, the present invention provides a method for treating a semiconductor surface, wherein a semiconductor surface treatment is carried out by using a hydrogen peroxide solution containing condensed phosphoric acid or a salt thereof as a component of a semiconductor surface treating agent. It is an invention.

The present invention also relates to a method for treating a semiconductor surface, wherein an alkaline aqueous solution containing condensed phosphoric acid or a salt thereof is used as a constituent of a semiconductor surface treating agent to carry out a semiconductor surface treatment. is there.

The present invention also provides a method for treating a semiconductor surface, characterized in that a semiconductor surface treatment is carried out by using water containing condensed phosphoric acid or a salt thereof as a component of a semiconductor surface treating agent. .

[Alkaline + Hydrogen Peroxide] Fe plays a major role in the case where the electrical properties are reduced by cleaning, but the adsorption contamination and the lack of cleaning power are sufficiently solved by the present invention. As can be seen from Comparative Example 1 below, in order to reduce the Fe concentration on the silicon surface required for electrical characteristics after SC-1 cleaning to 10 ¹⁰ atoms / cm ² or less, the Fe concentration in the SC-1 treatment solution is 0.01 ppb. Must be kept below. However, cleaning originally means that dirty wafers sequentially enter the cleaning solution,
In the actual example, the surface Fe concentration after the SC-1 treatment was 10 as described above.
^{11-10 12} atom are common. That is, it can be inferred from FIG. 1 that the actual Fe concentration in the SC-1 cleaning tank is about 0.1 to 1 ppb. Here, even if a complexing agent such as triethanolamine described in the above-mentioned complexing agent-added patent was added to the SC-1 treatment solution containing 1 ppb of Fe, the concentration of Fe was only 10% and Fe adsorption was only 10 ^11. Atoms / cm ² or less. Even with a typical chelating agent such as EDTA, about 10 ¹⁰ atoms / cm ² can be finally obtained at 10 ^-2 % by weight.

According to experience, organic substances in the [alkali + hydrogen peroxide] treating agent that are not easily decomposed into low-boiling substances affect the device yield unless the carbon concentration is at most 10 ^-4 % by weight or less. Therefore, the amount of Fe adsorbed on the silicon surface was compared by adding 10 ^-4 wt% of various chelating agents to the SC-1 treatment solution containing 1 ppb of Fe. 1,2-cyclohexanediaminetetraacetic acid (CyDT
A), triethylenetetramine hexaacetic acid (TTHA), and nitrilotriacetic acid (NTA) all reduced the adsorption only to about 1/2 to 1/3 of the case where no chelating agent was added. In the present invention, the purpose is achieved by the addition of a specific complexing agent, but the effect is strengthened to obtain a sufficient effect by adding as little as possible.

That is, the present inventors have conducted intensive studies on the metal adsorption mechanism on the wafer surface in order to achieve the above object, and as a result, the adsorption was found to be due to the OH group coordinated to the metal and the OH group existing on the wafer surface. Reduced contamination due to adsorption by incorporating a complexing agent that suppresses the coordination of the OH group to the metal in the semiconductor surface treatment agent or rinsing liquid, due to the hydrogen bond acting with the H group We have reached the conclusion that we can do it and have completed the present invention.

The complexing reaction is a competitive reaction between the metal ion and the H group for the complexing agent in the acidic region, but is a competitive reaction between the complexing agent and the OH group for the metal ion in the alkaline region. That is, the reaction of the complexing agent with the metal ion (complex formation reaction) is faster than the reaction of the OH group with the metal ion (hydroxide formation reaction), and the complex compound formed by the reaction is stable and water-soluble. If so, the complexing agent can suppress the formation of hydroxide of metal ions coexisting in the alkaline solution. Furthermore, since a complexing agent having a strong complexing ability can also dissolve a hydroxide, it is possible to suppress the coordination of the OH group to the metal by utilizing the complexing reaction, and to reduce the adsorbed metal. The inventors thought that they could be dissolved.

As a strong complexing agent for suppressing the coordination of the OH group, the present inventors have conducted intensive studies and have selected phosphonic acid chelating agents and condensed phosphoric acids. That is, any of these complexing agents according to the present invention has a complex formation constant for metal ions such as Fe, Al, and Zn that is large enough to sufficiently suppress the coordination of the OH group, and the complex formation reaction is easy and rapid. And that the resulting complex compound is stable and water-soluble. Further, the oxidized form of the phosphonic acid chelating agent was also confirmed for its complexing ability and the like. The present inventors have found that the present invention has a remarkable effect on suppressing the adsorption of water, and have reached the present invention.

Examples of the phosphonic acid chelating agent according to the present invention include methyldiphosphonic acid, aminotris (methylenephosphonic acid), ethylidene diphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid and 1-hydroxypropyl acid. Den-1,1-diphosphonic acid, 1-hydroxybutylidene-1,1-diphosphonic acid, ethylaminobis (methylenephosphonic acid), dodecylaminobis (methylenephosphonic acid), nitrilotris (methylenephosphonic acid), ethylenediaminebis (methylene Phosphonic acid), ethylenediaminetetrakis (methylenephosphonic acid), hexenediaminetetrakis (methylenephosphonic acid), diethylenetriaminepenta (methylenephosphonic acid), or their ammonium salts, alkali metal salts (excluding Na salts) Phosphon Chelating agents having one or more groups or salts thereof are mentioned. As the oxidized form thereof, among these phosphonic acid-based chelating agents, those having a nitrogen atom in the molecule are oxidized into N-oxide forms. Are included. Further, as the condensed phosphoric acids according to the present invention,
Examples thereof include metaphosphoric acid, tetrametaphosphoric acid, hexametaphosphoric acid, and tripolyphosphoric acid, or ammonium salts and alkali metal salts (excluding Na salts) thereof.

For example, ethylidene diphosphonic acid (EDP)
If was added to SC-1 treating solution containing a Fe1ppb so as to be ^10-4% by weight, the adsorption of Fe becomes an object of 10 ¹⁰ atoms / cm ² or less, clearly out differences in adsorption and conventional chelating agents Was. Similar effects can be obtained with other complexing agents according to the present invention, and Fe
The residual rate after cleaning of contaminated silicon is about 1/10 of that of the conventional complexing agent, and the cleaning effect is significantly improved.

These complexing agents according to the present invention may be used alone or as a mixture of two or more. Its content is usually in the range of 10 ^-7 to 10 ^-3 % by weight, preferably in the range of 10 ^-6 to 10 ^-4 % by weight in the whole solution. In addition, if it is contained more than this concentration range, harmful carbon contamination of the surface is caused. If the concentration is below this range, the cleaning effect cannot be expected much.

The semiconductor surface treating agent according to the present invention generally comprises
Inorganic or organic alkali, hydrogen peroxide and water are the main constituent components. Examples of the inorganic alkali used in the present invention include ammonia, which is usually used as a 20 to 30% aqueous solution. The organic alkali used in the present invention includes quaternary ammonium hydroxide, which is usually used as a 0.5 to 10% by weight aqueous solution. 4th
Specific examples of the quaternary ammonium hydroxide include, for example, trimethyl-2-hydroxyethylammonium hydroxide, tetramethylammonium hydroxide (TMAH)
And the like are typical examples, but are not limited thereto. The organic alkali used in the present invention is not limited to quaternary ammonium hydroxide. For example, guanidine carbonate can be used at similar concentrations.
These inorganic or organic alkalis are used so that the concentration in the whole solution of the semiconductor surface treating agent is usually 0.01 to 30% by weight, preferably 0.01 to 20% by weight.

Hydrogen peroxide is usually used as an aqueous solution of 20 to 40% by weight, and is usually used so that the concentration of hydrogen peroxide in the whole solution of the semiconductor surface treating agent is in the range of 0.01 to 30% by weight. Even outside the range, the cleaning effect is not particularly affected.

The complexing agent according to the present invention is dissolved in any one of the above-mentioned alkali, hydrogen peroxide solution or water, or any two or all of the components constituting the semiconductor surface treating agent. Usually, the mixture is used, but after mixing an alkali, a hydrogen peroxide solution and water, the mixture may be dissolved and used in the mixture. That is, the method for causing the complexing agent according to the present invention to be present in the semiconductor surface treating agent is not particularly limited.

Further, the same effect can be obtained by adding the complexing agent according to the present invention to rinsing water (usually using ultrapure water).

Some of the complexing agents according to the present invention have so far been used as stabilizers for hydrogen peroxide in many cases (JP-B-43-11656, JP-B-55-45484). JP, JP-B-59-45601, JP-Sho 60-239305 Patent Publication No.
Distribution, JP-B 62-57566, JP-Sho 62-57567 Patent Publication), object example used as in the present invention are quite than ever, thus adding to the hydrogen peroxide in such an object of the present invention There are no examples done. That is, there has been no example in which a hydrogen peroxide solution containing the complexing agent according to the present invention has been used as a semiconductor surface treatment agent. -1 When used for the treatment, this is purified by distillation, and further purified by ion exchange, etc.
All of these stabilizers had been removed in advance because they had been used. ).

In the present invention, when the complexing agent according to the present invention is used by adding it to aqueous hydrogen peroxide, the complexing agent is purified by distillation and then subjected to a treatment for removing metal impurities. It is preferable to use it by adding it to water. However, even if it is used by adding it to an untreated purified hydrogen peroxide solution, sufficient effects are recognized with respect to Fe, Al, Zn, and the like. This has not been confirmed at all, and is the first finding of the present inventors.

Since the surface treating agent of the present invention exhibits an excellent adsorption inhibiting effect and a high cleaning effect even at room temperature, it is not necessary to heat it at all. Needless to say, the effect remains unchanged even under moderate heating. The semiconductor surface treating agent according to the present invention includes, in addition to alkali, hydrogen peroxide, water and the chelating agent according to the present invention, various auxiliary components (for example, a surfactant) within a range not to impair the effects of the present invention. May be included.

Examples and comparative examples are shown below, but the present invention is not limited to these examples.

In this example, the metal concentration on the wafer surface was determined by eluting the metal into a cleaned Teflon sheet and a trace amount of ultra-high purity dilute hydrofluoric acid sandwiched between the wafer surfaces, and quantifying the metal by flameless atomic absorption spectrometry. did.

Unless otherwise specified, aqueous ammonia was 28%,
35% of hydrogen peroxide was used. Hereafter,% representing the concentration
ppm and ppb all indicate the weight ratio. Unless otherwise noted, these chemicals are ultra-high purity products, that is, Fe 0.1pp
b, Al was confirmed to be 0.1 ppb or less by flameless atomic absorption spectrometry and used. All water is Fe 0.01ppb, Al
Ultrapure water, which was also confirmed by analysis to be about 0.01 ppb, was used.

[0037]

【Example】

Example 1 Ethylidene diphosphonic acid (EDP) was added to a mixture of 1 volume of ammonia water, 1 volume of hydrogen peroxide solution and 5 volumes of water (hereinafter abbreviated as SC-1 treatment solution) at 10 ^-4 % and 1.5 × 10 ^-5 %.
Fe was added at 10 ppb, 1 ppb,
After immersing a wafer with a crystal orientation (100) of 5 inch P type several Ωcm and crystal orientation (100) in each of which 0.1 ppb was added, treating at 70 ° C. for 10 minutes, rinsing with ultrapure water for 10 minutes (hereinafter wafer and SC-1) Is the same as in this case.), And the concentration of Fe adsorbed on the wafer surface was quantified. The results of these adsorption experiments are shown by dotted lines in FIG. 1 as Freundlich plots. Further
The relationship between the addition of 10 ^-3 % EDP and the adsorption of Fe from 10 ppb from the solution is indicated by a triangle.

Comparative Example 1. SC-1 treatment solution using the hydrogen peroxide solution (without EDP) used in Example 1 and hydrogen peroxide solution (without complexing agent, commercial product A and commercial product B) of two other commercial companies An experiment of Fe adsorption from the processing solution was performed on the three series in the same manner as in Example 1. The result of the Freundlich plot is shown by a solid line in FIG.

There is almost no difference depending on the manufacturer of the hydrogen peroxide solution. If Fe in the SC-1 treatment solution is 1 ppb, the adsorption can be reduced to approximately 10 ¹² atoms / cm ² and the adsorption amount can be reduced to 10 ¹⁰ atoms / cm ² or less. It can be seen that the Fe concentration of the SC-1 treatment solution must be controlled to 0.01 ppb or less.

The surface treating agent of Example 1 shows a remarkable adsorption-preventing effect as compared with Comparative Example 1. When the control level of Fe in the SC-1 treatment solution is 0.1 ppb, the surface treatment agent is 1.5 × 10 ^-5 % of EDP. , 10 for 1ppb
^{At -4} % and 10 ppb, the adsorption of Fe can be suppressed to 10 ¹⁰ atoms / cm ² or less at 10 ^-3 %. That is, the purpose can be achieved with a trace amount of complexing agent that can ignore carbon contamination.

Comparative Example 2 An adsorption experiment similar to Comparative Example 1 was performed.
The analysis was also performed on Al, but the Freundlich plot almost coincided with Fe in FIG.

Embodiment 2 The same adsorption experiment as in Example 1 was performed.
For Al, the EDP was performed at 10 ^-3 %, but the Freundlich plot decreased only by about one digit as compared with the case where no additive was added (Comparative Example 2), but had an adsorption reducing effect, but was considerably weaker than Fe. Therefore, when adding the chelating agent according to the present invention, it is desirable to sufficiently purify hydrogen peroxide and reduce the Al concentration as much as possible before adding to minimize the chemical-induced Al contamination.

Embodiment 3 Triethanolamine and EDTA, which are said to have a strong masking effect on Fe, and diethylenetriaminepenta (methylenephosphonic acid) according to the present invention
The relationship between the concentration of the complexing agent in the SC-1 treatment solution containing 1 ppb of Fe and the amount of Fe adsorbed on the silicon surface was determined by comparison with (ETPPO), and is shown in FIG. The effect of the chelating agent according to the present invention is observed from 10 ^-7 %, and the amount of Fe adsorption can be suppressed to 10 ¹⁰ atoms / cm ² or less at 10 ^-4 %. On the other hand, triethanolamine is only 10% at 1% at 10 ¹¹ atoms / cm ² , and 10 ¹⁰ atoms / cm ² if EDTA is not 10 ^-2 %.
Does not reach the adsorption level.

Comparative Example 3 The amount of adsorption to the wafer when 3 × 10 ⁻⁴ % of various complexing agents were added in the SC-1 treatment solution containing 1 ppb of Fe was determined and compared. Table 1 shows the results.

[0045]

[Table 1]

Embodiment 4 Methyl diphosphonic acid (MDP)
Using ammonia water (28%) pre-added with ^10-4 %
An SC-1 treatment liquid was prepared in the same manner as in the above examples. MDP of processing solution
The concentration becomes 1.5 × 10 ⁻⁵ %. After the cleaning treatment of the solution obtained by adding 1 ppb of Fe to this solution, the adsorption to the wafer was examined. Adsorption was 6 × 10 ¹⁰ atoms / cm ² .

Also, a silicon wafer which was previously contaminated with Fe at 10 ¹² atoms / cm ² on its surface was washed at 70 ° C. for 10 minutes with this SC-1 treatment solution to which 1 ppb of Fe was not added, and then rinsed with pure water for 10 minutes (hereinafter referred to as “rinsing”). The cleaning conditions are the same as those for the Fe-contaminated wafer used in the SC-1 cleaning experiment of
At 10 ⁹ atoms / cm ² , the residual ratio (percentage of the residual amount to the initial contamination amount) was 0.6%, and the cleaning effect of Fe by the SC-1 treatment solution was improved by one digit.

Comparative Example 4 The same adsorption experiment and washing experiment were performed using various chelating agents similar to EDTA having a large chelate stability constant at the same concentration in place of the MDP of Example 4. The results are shown in Table 2 in comparison with the results of Example 4.

[0049]

[Table 2]

It can be seen that when these chelating agents are ^contained at 10 ^-5 %, the effect of suppressing the adsorption of Fe and the improvement of the cleaning effect are hardly observed.

Embodiment 5 FIG. Hexametaphosphoric acid (HP), 1-hydroxyethylidene-1,1-diphosphonic acid (HDP), nitrilotris (methylenephosphonic acid) (NTPO), ethylenediaminetetrakis (methylenephosphone) Acid) (EDTPO) or ETPPO
^Was contained at 10 ^-4 % to prepare surface treatment solutions according to the present invention. Using the SC-1 treatment liquid, a 10 ¹² atom / cm ² Fe-contaminated silicon wafer was washed, and the remaining amount after the washing was quantified.
The residual rate was determined. Further, an Al-contaminated silicon wafer of 5 × 10 ¹² atoms / cm ² was washed under the same conditions, and the residual ratio was determined in the same manner. Further, the same procedure was performed on a Zn-contaminated silicon wafer of 10 ¹² atoms / cm ² , and the residual ratios are shown in Table 3.

Comparative Example 5 The SC-1 treatment solution to which ^10-4 % of EDTA or acetylacetone, which is a general-purpose and typical chelating agent, was added instead of the chelating agent according to the present invention, and the SC-1 treatment solution to which no chelating agent was added, respectively. The same washing experiment as in Example 5 was performed. The obtained residual ratio is also shown in Table 3.

[0053]

[Table 3]

As is clear from Table 3, the semiconductor surface treating agent according to the present invention can be added to Fe and Zn with a very small addition of 10-4%.
Shows a remarkable improvement in the cleaning effect, and Al also has a considerable improvement. On the other hand, in the region where such a trace amount is added, even if EDTA or acetylacetone capable of forming a cyclic chelate is added similarly to the phosphonic acid-based chelating agent according to the present invention, the effect as in the present invention is hardly obtained.

Embodiment 6 FIG. A chelating agent according to the present invention in the same manner as in Example 1 except that the treatment liquid [organic alkali + hydrogen peroxide] in which 28% aqueous ammonia of Example 1 was replaced with 1% aqueous solution of trimethyl (2-hydroxy) ethylammonium hydroxide was used. EDP was added, and the adsorption experiment of Fe to the silicon wafer from the cleaning solution (70 ° C, 10 ° C) was performed in the same manner as in Example 1.
), A Freundlich plot substantially matching the dotted line in FIG. 1 was obtained.

Embodiment 7 FIG. The treatment solution [28% ammonia water of Example 1 was replaced with 1% TMAH aqueous solution [organic alkali +
[Hydrogen peroxide] and the same adsorption experiment as in Example 6 was performed. As a result, a Freundlich plot almost coincident with the dotted line in FIG. 1 was obtained.

From the results of Examples 6 and 7, it can be seen that the chelating agent according to the present invention has a strong Fe adsorption suppressing effect in the treatment solution of [alkali + hydrogen peroxide] regardless of whether it is inorganic or organic.

Example 8 Adsorption and washing experiments on Fe were carried out using a treating solution obtained by adding HDP or ETPPO instead of EDP to the treating solution of Example 6. The addition amount of the chelate is 10 ^-4 %
It is. A silicon wafer contaminated with Fe10 ¹² atoms / cm ^{2 was} washed with each liquid at 70 ° C. for 10 minutes, rinsed with pure water for 10 minutes, and then the residual ratio of Fe was determined. Further, when a clean silicon wafer was similarly treated with a treatment solution obtained by adding 1 ppb of Fe to each solution, the amount of Fe adsorbed on the wafer was determined. Table 4 shows the results.

[0059]

[Table 4]

From these results, it can be seen that the effect of the chelating agent according to the present invention is not limited to inorganic or organic alkali.

Embodiment 9 FIG. Semiconductor surface treatment agents consisting of 28% ammonia water: 35% hydrogen peroxide solution: water = 1 volume: 1 volume: 5 volume were prepared using the three formulations shown in the following AC. A: EDP was added and dissolved in 28% aqueous ammonia, and then mixed with aqueous hydrogen peroxide and water. B = Add EDP to hydrogen peroxide solution and dissolve it.
Prepared by mixing with ammonia water and water. C = EDP was added to water and dissolved, and then mixed with 28% aqueous ammonia and 35% aqueous hydrogen peroxide. After adding 1 ppb of Fe to each of these three treatment agents, the silicon wafer was washed and rinsed in the same manner as in Example 1, and the amount of Fe adsorbed on the surface was measured. Table 5 shows the results.

[0062]

[Table 5]

As is clear from Table 5, the chelating agent according to the present invention is added to any component of aqueous ammonia, hydrogen peroxide or water constituting the surface treating agent and dissolved.
The complex formation effect is similarly exhibited, and does not give a significant difference in the effectiveness of adsorption suppression and washing. Further, as shown in Examples 1 and 3 to 5, each component may be used after being added and dissolved after mixing,
It turns out that the method of preparing the surface treatment agent is not particularly limited.

Embodiment 10 FIG. After acid cleaning, 5 × Fe
Using a P-type (100) clean wafer confirmed to be about 10 ⁹ atoms / cm ² , a SC-1 treatment solution with 1 ppb Fe contamination and a treatment solution with 10 ^-4 % EDP added to it At 70 ℃, 1
After washing for 0 minutes, it was rinsed with ultrapure water and dried. The cleaned wafers were thermally oxidized and the recombination lifetimes were compared by photodetection with microwave detection. Table 6 shows the results.

[0065]

[Table 6]

As shown in Table 6, 1 ppb of Fe-contaminated SC-1
Even if the chelating agent according to the present invention is present in a very small amount even when treated with the treatment solution, the recombination lifetime is at the same level as that of the clean wafer before the SC-1 treatment. It is known that the lifetime of P-type wafers is sensitively affected by Fe contamination,
As can be seen from Example 1, the presence of the chelating agent according to the present invention does not reduce the lifetime, so that the F is reduced to 10 ¹⁰ atoms / cm ² or less.
e This is because pollution is suppressed.

Embodiment 11 FIG. Fe in ultrapure water of 0.01ppb.
When 1 ppb of Fe was added and the silicon wafer was immersed in water adjusted to pH 8.5 with ammonia water for 10 minutes, 1.1 × 10 ¹¹
Atomic atoms / cm ² of Fe adsorption occurred. 1.5 × 10 ^-6 % ED in this water
When TPO was added and the pH was adjusted to 8.5 with aqueous ammonia and the same immersion was performed, the amount of adsorption to the wafer was <10 ¹⁰
Atoms / cm ² or less.

Embodiment 12 FIG. EDTPO and NTPO were added to hydrogen peroxide to produce their N-oxides (oxidants). These N-oxides (oxidized) are 3 × 10 ^-4 %
The wafer was treated in the same manner as in Example 1 with the SC-1 treatment solution containing 1 ppb of Fe added so as to obtain the Fe adsorption amount.

An aqueous hydrogen peroxide solution containing 2 × 10 ⁻³ % of N-oxide (oxidized form) was stored at 20 ° C. for 30 days. An SC-1 treatment solution containing 1 ppb of Fe was prepared using these hydrogen peroxide solutions, and the wafer was treated in the same manner as in Example 1 to determine the amount of Fe adsorbed. The results are shown in Table 7.

[0070]

[Table 7]

As can be seen from Table 7, the EDTPO-oxidized product and the NTPO-oxidized product effectively act to suppress the adsorption of Fe similarly to EDTPO and NTPO, and the effect does not change even after 30 days. It was stable without.

[0072]

[Effect of the Invention] [Alkali + hydrogen peroxide] which has an excellent effect of removing fine particles and is also effective in removing oil and fat contamination.
Cleaning did not provide a silicon wafer with satisfactory electrical properties. However, by adding the complexing agent according to the present invention to the treating agent or rinsing solution in the semiconductor surface treatment step in a trace amount that does not harm organic substances, it is possible to reduce the recombination lifetime and the oxide film breakdown voltage. Adsorption of harmful impurities can be suppressed to a surface impurity concentration that does not cause a problem in electrical characteristics, and the ability to clean harmful impurities can be improved. The effect of the present invention is not limited only to the composition of [alkali + hydrogen peroxide]. It is known that the adhesion of fine particles to a silicon wafer is weakened as the pH increases. However, when the pH is higher than 3, Fe in water tends to be a colloid, and the risk of Fe contamination increases. Ultrapure water used for rinsing often has an increased Fe concentration of about 0.1 ppb, and the complexing agent according to the present invention also prevents such adsorption contamination.

The effects of the processing method and the processing agent according to the present invention are of course effective not only on the surface of a single crystal silicon but also on the surface of a polycrystalline film. Therefore, LCD using such a film
It is also effective for cleaning glass substrates, and can be applied to compound semiconductors that dislike contamination such as Fe and Zn. Further, it can be widely used as a process from a stage of manufacturing as a material of a wafer to a stage of manufacturing a patterned device. Since the ripple effect is enormous, the surface treating agent of the present invention is industrially very useful.

[0074]

[Brief description of the drawings]

FIG. 1 shows the relationship between the Fe concentration (ppb) in the SC-1 treatment solution obtained in Example 1 and Comparative Example 1 and the amount of Fe adsorbed on the silicon wafer surface (atoms / cm ² ). It is a curve figure (Freundlich plot). However, the dotted line is the same as in Example 1 (however,... は is ethylidene diphosphonic acid (EDP) 10 ⁻⁴ ).
... Show the results of the treatment solutions to which 1.5 × 10 ⁻⁵ % of EDP was added. ), The solid line is Comparative Example 1 (however,
: No EDP added,-◎-: Commercial product A,-●-: Commercial product B
Are shown below. ). In addition, △ indicates ED in the first embodiment.
The results when P was added at 10 ^-3 % are shown.

FIG. 2 shows SC-1 containing 1 ppb of Fe obtained in Example 3.
Complexing agent concentration (wt%) in processing solution and Fe on silicon surface
FIG. 4 is a curve diagram showing a relationship between adsorption amounts (atoms / cm ² ). However,-□-shows the result when ETPPO which is the chelating agent according to the present invention was added,-△-shows the result when triethanolamine was added, and-○-shows the result when EDTA was added as a complexing agent. .

Continuing from the front page (72) Inventor Hiromi Nawa 1633, Oji, Kawagoe-shi, Saitama Wako Pure Chemical Industries, Ltd. Tokyo Research Laboratory (72) Inventor Hisashi Muraoka 3-15 Miigaoka, Midori-ku, Yokohama-shi, Kanagawa Pref. Government Mitsuru Suzuki (56) References JP-A-62-252141 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/304

Claims (18)

(57) [Claims] 1. A step of cleaning a surface of a semiconductor with a semiconductor surface treating agent containing inorganic or organic alkali, hydrogen peroxide and water as main components, and a step of rinsing the semiconductor surface with ultrapure water after the cleaning. A method for treating a semiconductor surface, wherein condensed phosphoric acid or a salt thereof is present in at least one of a semiconductor surface treating agent and ultrapure water for rinsing to carry out the treatment. 2. The method for treating a semiconductor surface according to claim 1, wherein the cleaning is carried out using a semiconductor surface treating agent containing condensed phosphoric acid or a salt thereof. 3. The method according to claim 1, wherein the rinsing is performed using ultrapure water containing condensed phosphoric acid or a salt thereof. 4. An inorganic or organic alkali, hydrogen peroxide,
A semiconductor surface treatment agent comprising water and condensed phosphoric acid or a salt thereof . 5. The semiconductor surface treating agent according to claim 4, comprising 10 ^-7 to 10 ^-3 % by weight of condensed phosphoric acid or a salt thereof. 6. The semiconductor surface treating agent according to claim 4, wherein the inorganic or organic alkali is ammonia or quaternary ammonium hydroxide. 7. The semiconductor surface treating agent according to claim 4, wherein the concentration of the inorganic or organic alkali is 0.01 to 20% by weight in the whole solution. 8. The semiconductor surface treating agent according to claim 4, wherein the concentration of hydrogen peroxide is 0.01 to 30% by weight in the whole solution. 9. A method in which condensed phosphoric acid or a salt thereof is contained in at least one of the components constituting the semiconductor surface treating agent and then the components are mixed, or the components constituting the semiconductor surface treating agent are mixed and then mixed. 5. The method for preparing a semiconductor surface treatment agent according to claim 4, wherein the preparation is carried out by adding condensed phosphoric acid or a salt thereof to the mixture. 10. An aqueous alkaline solution for a semiconductor surface treating agent, comprising condensed phosphoric acid or a salt thereof . 11. The aqueous alkali solution for a semiconductor surface treating agent according to claim 10, wherein the alkali is ammonia or quaternary ammonium hydroxide. 12. After passing through the removal process after purification by distillation further metal impurities, the semiconductor surface treating agent for hydrogen peroxide formed by incorporating a Chijimigori phosphate or a salt thereof. 13. The semiconductor surface treating agent according to claim 4, wherein the condensed phosphoric acid or a salt thereof is hexametaphosphoric acid or ammonium hexametaphosphate. 14. A semiconductor surface treatment method, wherein a semiconductor surface treatment is carried out using a hydrogen peroxide solution containing condensed phosphoric acid or a salt thereof as a component of a semiconductor surface treatment agent. 15. The treatment method according to claim 14, wherein after the purification by distillation, a treatment for removing metal impurities is carried out, and then a hydrogen peroxide solution containing condensed phosphoric acid or a salt thereof is used. 16. A semiconductor surface treatment method, wherein a semiconductor surface treatment is performed using an aqueous alkaline solution containing condensed phosphoric acid or a salt thereof as a component of a semiconductor surface treatment agent. 17. The method according to claim 16, wherein the alkali is ammonia or quaternary ammonium hydroxide. 18. A method for treating a semiconductor surface, wherein water containing a condensed phosphoric acid or a salt thereof is used as a component of a semiconductor surface treating agent to carry out a semiconductor surface treatment.