JPH1050647A - Cleaning soln. and cleaning method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the re-deposition of contaminant particles by using a cleaning soln. contg. hydrogen fluoride, alcohol and ioneliminated water in specified vol.% ranges to hold a good profile after cleaning. SOLUTION: Hydrogen fluoride of 0.01-20vol.%, alcohol of 50-99.98vol.% and ion-eliminated water of 0.01-49.9vol.% are used. Alcohol mixes well with water and does not leave residues on the wafer surface. When alcohol is used for cleaning the surface of a polysilicon layer, a very thin alcohol film is formed on the wafer surface to thereby prevent an abrupt growth of an oxide fiber on the polysilicon layer surface and also suppress the re-deposition of contaminants in the air.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning solution used for manufacturing a semiconductor device or a liquid crystal display device (LCD) and a cleaning method using the same. More specifically,
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning solution for removing contaminants such as polymers, metal substances, and etching residues, and natural oxide films generated during the manufacture of a general semiconductor device or a liquid crystal display device, and a cleaning method using the same.

[0002]

2. Description of the Related Art Semiconductor devices are formed by sequentially laminating various thin films for semiconductor on a silicon wafer, and performing various chemical and mechanical processes such as ion preparation, etching process or chemical mechanical polishing process (CMP). It is manufactured by processing the thin film using a process.

A liquid crystal display device is a typical display device manufactured using a liquid crystal having an intermediate property between a liquid and a solid, which has both the fluidity of the liquid crystal and the optical properties of the crystal. The manufacturing process is similar to the semiconductor device manufacturing process.

However, when manufacturing the semiconductor device or the liquid crystal display device, various contaminants such as metal particles and polymers and a natural oxide film are generated at each manufacturing stage. Alternatively, not only may the liquid crystal display element malfunction, but also the yield may decrease.

[0005] Furthermore, as the speed, performance, and miniaturization of electronic equipment increase, the degree of integration increases, and this contamination source becomes a very serious problem in forming a fine pattern in which various multilayer thin films are stacked. .

[0006] Therefore, a cleaning process for removing various contaminants and a natural oxide film that may cause a decrease in the performance and yield of a semiconductor device or a liquid crystal display device is one of very important processes.

[0007] Examples of the steps where such a cleaning step is essentially required include (1) a step of forming a contact hole for exposing a conductive layer by dry etching, and (2) a diffusion step, particularly a thermal oxide film. Before (3) a photolithography process for forming a photosensitive film pattern, or (4) after a polishing process for planarizing a semiconductor substrate.

For example, a description will be given of a cleaning process after the step of forming a contact hole for exposing a conductive film by dry etching.

In manufacturing a semiconductor device, in order to connect different conductive films, a contact hole is formed by etching an oxide film formed on the lower conductive film to expose a portion of the lower conductive film. An upper conductive film is laminated thereon.

When forming the contact hole, the etching process of the lower conductive film may be performed by a wet etching method having isotropic characteristics, but this wet etching method is not suitable for forming a fine contact hole. Accordingly, at present, a method of forming a contact hole by etching the lower conductive film by dry etching having anisotropic etching characteristics is used.

However, when the contact hole is exposed to the atmosphere after the formation of the contact hole, a natural oxide film is formed on the bottom surface of the contact hole, and etching residues and metal are formed on the side wall and the bottom surface of the contact hole. Contaminants, such as materials, can have a fatal impact on product yield and reliability. Among them, the etching residue is a polymer substance formed by the mutual reaction of an etching gas, a photoresist component, an oxidizing substance, etc., and removes some contaminated metal from the etching chamber. May include.

When such a natural oxide film and / or contaminants are generated, the contact resistance increases and the performance of the semiconductor device is reduced, or a fatal defect occurs in the performance. Therefore, in order to improve the performance of the semiconductor device, it is necessary to lower the contact resistance by cleaning the contact hole to remove a natural oxide film and contaminants.

However, recently, as the aspect ratio of a contact hole has increased,
It is becoming more difficult to remove various contaminants such as metallic contaminants, particle phase contaminants, and etching residues remaining on the bottom surface of the contact holes.

Usually, hydrofluoric acid diluted in deionized water is mainly used as a contact hole cleaning solution.

However, the dilute hydrofluoric acid solution is not only excellent in removing the above-mentioned various contaminants, but also exhibits different etching rates for different oxide films forming the side walls of the contact holes. Therefore, the profile of the side wall of the contact hole is severely deformed, and a problem such as formation of a void in a subsequent contact hole filling step occurs. Further, some oxide films (for example, I
If the etching rate of the LD layer is too high, it becomes difficult to secure a process margin in the cleaning process.

FIG. 1 is a view showing a problem that occurs when a contact hole is cleaned using a conventional cleaning solution, that is, a diluted solution of hydrofluoric acid. Reference numeral 10 denotes a semiconductor substrate, and reference numeral 20 denotes a plasma. An oxide film, 30 is a low pressure chemical vapor deposition film, and 40 is BPSG (Borophosphosilicate).
glass), and 50 indicates a contact hole.

However, in order to remove contaminants remaining in the contact hole, a conventional cleaning solution is used to form an oxide-based layer forming a side wall of the contact hole 50, that is, a plasma oxide film 20, a low-pressure chemical vapor deposition film. When etching the 30 and the BPSG film 40, since each oxide film has a different etching rate for hydrogen fluoride, it is not easy to adjust the etching rate. In addition, the oxide film reacts very actively with hydrogen fluoride, so that it is easily etched excessively. Therefore, the inner wall of the contact hole has an uneven profile.

When a subsequent step of filling a contact hole having a non-uniform profile with a metal or the like is performed, voids are generated inside the contact hole, thereby lowering the yield and reliability of the semiconductor device. Become.

In a contact for a storage electrode called a BC (Buried Contact), it is difficult to secure a margin between a bit line and a gate due to high integration of a semiconductor element. Therefore, if the contact hole is cleaned using a conventional cleaning solution, the bit line and the gate may be exposed inside the contact hole.

The following reaction formula 1 shows the ionization reaction of hydrofluoric acid.

[0021]

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As can be seen from this equation, HF ₂ ^- is generated as a result of the ionization reaction, which is caused by a natural oxide film and a contact formed on the bottom surface of the contact hole together with neutral HF in equilibrium in a solution state. The natural oxide film and the oxide film are removed by actively reacting with the oxide film forming the side wall of the hole to form SiF ₄ having excellent solubility and volatility. However, since the HF ₂ ^- is excessively generated, it is difficult to adjust the etching rate for each oxide film, and an excessive etching phenomenon of the oxide film is likely to occur.

In addition, since the zeta potential on the surface of the oxide film is made positive by the hydrogen ions after the etching reaction, when the semiconductor element is left in the air for a long time to perform the subsequent steps. The atmospheric contaminant particles are reattached in the contact hole. Therefore,
There is a process burden that waiting time for subsequent processes must be minimized.

Another problem associated with using conventional cleaning solutions is that watermarks or non-drying residues are generated on the surface of the wafer. That is,
If the hydrophilic oxide film and the hydrophobic polysilicon film having a step are exposed at the same time, deionized water remaining in the step region between the hydrophobic film and the hydrophilic film after the cleaning step may be removed from the silicon wafer. Reacts with atmospheric oxygen on the surface of
Water marks are generated by forming ₂ SiO ₃ . Therefore, a drying step is needed to remove residual deionized water. At this stage, I
A PA (isopropylalcolhol) vapor phase drying method is used.
However, this method has the following disadvantages. First, it is difficult to precisely maintain various conditions required during drying, second, there is a high possibility that other defects will occur on the surface of the wafer after drying, and third, the drying process The IPA vapor phase dryer used is expensive.

Accordingly, there is a strong need for a cleaning solution that overcomes many of the problems discussed above.

[0026]

SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor device and a liquid crystal having excellent solubility in organic and inorganic components, maintaining a good profile even after washing, and capable of preventing the reattachment of contaminating particles. An object of the present invention is to provide a cleaning solution for a display element.

Another object of the present invention is to provide a method for cleaning a semiconductor device or a liquid crystal display device using the cleaning solution.

[0028]

In order to achieve the above-mentioned object, the present invention provides a method for producing a liquid containing 0.01 to 20% by volume of hydrogen fluoride, 50% by volume.
９９99.8% by volume of alcohol and 0.01-49.
A cleaning solution for a semiconductor device or a liquid crystal display device, comprising 9% by volume of deionized water.

In order to achieve the other object, the present invention provides:
In the method for cleaning a semiconductor element or a liquid crystal display element,
Cleaning the surface of the semiconductor device or the liquid crystal display device with a cleaning solution containing 0.01 to 20% by volume of hydrogen fluoride, 50 to 99.8% by volume of alcohol, and 0.01 to 49% by volume of deionized water; A method of cleaning a semiconductor device or a liquid crystal display device, comprising the steps of:

In the cleaning solution for a semiconductor device or a liquid crystal display device and the cleaning method using the same, the alcohol in the cleaning solution is preferably methanol, ethanol or isopropyl alcohol, and more preferably isopropyl alcohol.

Further, the cleaning solution for the semiconductor element or the liquid crystal display element is performed after (1) a step of forming a contact hole for exposing a conductive layer by dry-etching a substrate of the semiconductor element or the liquid crystal display element. In the cleaning process, (2) a cleaning process performed before forming a thermal oxide film on a substrate surface of a semiconductor device or a liquid crystal display device, and (3) a semiconductor performed before a photolithography process of forming a photosensitive film pattern. The method is characterized in that it is used in a substrate cleaning step of an element or a liquid crystal display element, or in (4) a semiconductor element or liquid crystal display element substrate cleaning step performed after the step of exposing the polysilicon film.

[0032]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

Alcohol has good miscibility with water and does not leave any residue on the wafer surface after the cleaning process. In addition, when cleaning the surface of the polysilicon layer using alcohol, by forming an ultra-thin alcohol film on the surface of the wafer, the rapid growth of the oxide film on the surface of the polysilicon layer is prevented, and the The phenomenon of reattachment of pollutants is also suppressed. In addition, by improving the wettability, it is possible to prevent a phenomenon that a watermark is generated in the polysilicon layer.

In addition, spin drying using the cleaning solution of the present invention has the advantage that it can overcome a number of problems that may be induced when drying the normal IPA vapor phase as described above.

FIG. 2 shows a case where a contact hole is cleaned using the cleaning solution of the present invention. In FIG. 2, reference numeral 10 denotes a semiconductor substrate, 20 denotes a plasma oxide film,
0 is a low pressure chemical vapor deposition film, 40 is a BPSG film, 50
Indicates a contact hole. In the cleaning solution of the present invention, by adjusting the amounts of hydrogen fluoride, alcohol and deionized water (DIW) added, the natural oxide film on the bottom surface of the contact hole containing the contaminant and the contact hole are removed. The oxide film forming the side wall is carefully etched according to each etching rate. Therefore,
As shown in FIG. 2, a desired profile in which the side wall of the contact hole is relatively flat can be obtained.

The cleaning method using the cleaning solution according to the present invention will be described with reference to the following ionization reaction formula (2).

[0037]

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In the above formula, R is a methyl, ethyl or isopropyl group.

[0039] As shown in Reaction Scheme 2, the alcohol in the wash solution of the present invention is reacted with hydrogen fluoride HF ₂ ^-
Generates, this generation amount HF ₂ generated by the reaction of hydrogen fluoride and deionized water ^- is slightly more. However, as the content of deionized water in the washing solution increases,
HF ₂ ^- amount of generation increases. That is, when the alcohol content of the wash solution is increased, HF ₂ ^- in but generation amount etch rate is lowered for reduction to the oxide film, the amount of alcohol decreases the amount of deionized water increases, HF ₂ ^- generation amount also increases etch rate for the oxide film growing in.

Therefore, as described above, the natural oxide film formed on the bottom surface of the contact hole and the side wall of the contact hole are formed by adjusting the amounts of hydrogen fluoride, alcohol and the number of deionized ions in the cleaning solution. By controlling the etching rates for oxide films having different etching rates, not only a desired profile can be obtained, but also various pollutants in the contact holes can be removed.

In particular, as shown in Table 1 below, the cleaning solution of the present invention is generated in a larger amount after chemical vapor deposition, ion preparation, or dry etching as compared with a normal hydrofluoric acid diluted solution. Excellent for cleaning metallic contaminants.

[0042]

[Table 1]

The present invention can also be used efficiently for removing particulate contaminants remaining on the surface of the cleaned wafer. As can be seen from Table 2 below, the silicon wafer is treated with HF + IPA + DIW (volume ratio: 1 : 200: 6), when immersed in a cleaning solution for 10 minutes.
-1 shows a washing solution _{(NH 4 OH + H 2 O} 2 + DIW) and removal forces of considerable similar to levels have particle phase pollutants.

[0044]

[Table 2]

As can be seen from the results in Tables 1 and 2, the cleaning solution of the present invention exhibits excellent cleaning power against both metallic contaminants and particulate phase contaminants.
1 and 2 were performed sequentially using a hydrofluoric acid diluent.
The washing steps can be one step.

The cleaning solution and the cleaning method using the same according to the present invention can be efficiently applied even after the step of exposing the polysilicon layer in a semiconductor device or a liquid crystal display device. Particularly, in the manufacturing process of a semiconductor device or a liquid crystal display device, not only a cleaning process after forming a contact hole by dry etching, but also a cleaning process before a diffusion process, particularly before a thermal oxide film is formed and before a photo etching process. It is desirably applied to the process. Further, a good contact hole profile can be provided even after cleaning.

[0047]

The cleaning solution according to the present invention is desirably applied to the cleaning of the polysilicon layer and the cleaning when the polysilicon layer and the insulating layer coexist. However, the cleaning solution for the organic and inorganic contaminants and the cleaning after the cleaning are effective. Because of its excellent effect of preventing re-attachment, it is preferably used in a cleaning process before forming a contact hole and before a diffusion process or before a photolithography process. In particular, by providing a uniform contact hole profile even after cleaning, the performance and yield of semiconductor devices and liquid crystal display devices are improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a contact hole cleaned using a conventional cleaning solution.

FIG. 2 is a sectional view of a contact hole cleaned using a cleaning solution according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Semiconductor substrate, 20 ... Plasma oxide film, 30 ... Low pressure chemical vapor deposition film, 40 ... BPSG film, 50 ... Contact hole.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Taka Yong-Nan 1038 No.3 Dong-dong 3, Seocho-gu, Seoul, Republic of Korea

Claims (10)

[Claims] (1) 0.01 to 20% by volume of hydrogen fluoride;
0-99.8 vol% alcohol and 0.01-4
A cleaning solution for a semiconductor device or a liquid crystal display device, comprising 9.9% by volume of deionized water. 2. The cleaning solution according to claim 1, wherein the alcohol is selected from the group consisting of methanol, ethanol and isopropyl alcohol. 3. The cleaning solution for a semiconductor device or a liquid crystal display device according to claim 2, wherein the alcohol is isopropyl alcohol. 4. The method according to claim 1, wherein the semiconductor device or the liquid crystal display device is used in a cleaning process performed after a process of forming a contact hole exposing a conductive layer by dry-etching a substrate of the liquid crystal display device. Cleaning solution for semiconductor devices or liquid crystal display devices. 5. The cleaning for a semiconductor element or a liquid crystal display element according to claim 1, wherein the cleaning step is performed in a cleaning step performed before forming a thermal oxide film on a substrate surface of the semiconductor element or the liquid crystal display element. solution. 6. The semiconductor device or the liquid crystal display device according to claim 1, wherein the semiconductor device or the liquid crystal display device is used in a substrate cleaning process of a semiconductor device or a liquid crystal display device performed before a photolithography process of forming a photosensitive film pattern. Cleaning solution. 7. The cleaning method for a semiconductor device or a liquid crystal display device according to claim 1, wherein the cleaning is performed in a substrate cleaning process of the semiconductor device or the liquid crystal display device performed after the step of exposing the polysilicon film. solution. 8. A method for cleaning a semiconductor element or a liquid crystal display element, comprising: 0.01 to 20% by volume of hydrogen fluoride, 50 to 99.8% by volume of alcohol, and 0.01 to 49% by volume of deionized water. Cleaning the semiconductor element or the liquid crystal display element with a cleaning solution containing the semiconductor element or the liquid crystal display element. 9. The method according to claim 8, wherein the alcohol is selected from the group consisting of methanol, ethanol and isopropyl alcohol. 10. The method for cleaning a semiconductor device or a liquid crystal display device according to claim 9, wherein the alcohol is isopropyl alcohol.