JPS62165937A - Treatment method - Google Patents

Abstract

PURPOSE:To improve wettability with a treating liquid of the whole material to be treated, and to prevent the nonuniformity of treatment by exposing the material to be treated in a liquefied or gassy substance having compatibility with the treating liquid prior to the treatment of the material to be treated. CONSTITUTION:A wafer type treating liquid is used for etching and rinsing an Si substrate, the surface thereof has fine irregularities. A substance, which has small adsorptivity to Si, is easy to be replaced with the water type treating system and has a hydrophilic group and a hydrophobic group in a molecule thereof, methanol acetic acid, acetone, etc., their mixture and a mixture with water are employed as a liquid or a gas having compatibility with the water group treating liquid. When the Si substrate is dipped or brought into contact to the liquid, the hydrophilic groups and hydrophobic groups selectively deposit on the surface, and the Si substrate is easy to be wetted by hydrophilic and hydrophobic treating liquids as a whole. Since a deposit has compatibility with the water group treating liquid and is dissolved during treatment and has small surface tension, bubbles are easy to be desorbed, and the Si substrate can be treated uniformly. Lastly, the adhering treating liquid is washed away by a pure water.

Description

[Detailed description of the invention] Industrial application field BRBIt Tr1 and Lily; April 1:1 Hi 埒n1
n i 1 shi te do i mute sanda ;chi! 7. Cleaning, etching, degreasing, resist peeling, etc. using various liquid chemicals (hereinafter referred to as treatment liquids) for plate-shaped objects with fine irregularities on the surface, such as lids and electrodes for liquid crystal displays, etc. The present invention relates to a treatment method that enables uniform surface treatment.

In the detailed explanation below, we will discuss IC manufacturing substrates (hereinafter referred to as S
This section describes the etching and cleaning of the i-wafer.

Conventional technology Conventional Si wafer processing and etching methods include: ■ Immersion in an etching solution (hereinafter referred to as the first method); ■ Spraying an etching solution from a nozzle while rotating the Si wafer. method, (JP-A-63-8577, JP-A-54-7874.

JP-A-56-27931, JP-A-58-1227
Publication No. 32, JP-A-58-58-196O24-, 4S
rAFJn 59 No. 103344 + Report, 't'5
(Patent Publication No. 59-204238) (hereinafter referred to as the second method) ■ Method of etching under reduced pressure (Patent Publication No. 60-73)
No. 82) (hereinafter referred to as the third method), etc. are known.

In addition, the current method of cleaning Si wafers is mostly to immerse them in a cleaning solution and shake the Si wafer, or to use auxiliary methods such as applying ultrasonic waves. .

Problems to be Solved by the Invention In the above-mentioned cleaning and etching, the conventional techniques
In the method described above, air adheres to some of the corners and small depressions of the pattern formed on the surface of the Si wafer, preventing contact between the St 2 wafer and the processing solution, resulting in uneven processing. In particular, on the surface of a Si wafer, a hydrophilic part such as a 5iO2 film and a Si
When hydrophobic parts such as the like are present, air bubbles adhere to the boundaries, resulting in a lot of uneven processing.

In order to minimize this problem, the above-mentioned second method and third method are used in the prior art, but in the second method, the processing liquid is scattered, causing problems in work safety and the work environment. In addition to having negative effects, air bubbles attached to the Si wafer cannot be completely removed. Furthermore, the third method requires a pressure reducing device, which makes the entire multi-processing device large-scale, and the processing section is sealed, making continuous processing of Si wafers impossible. Furthermore, since the pressure is reduced after the Si wafer is immersed in the processing solution, air bubbles attached to the Si wafer expand as the degree of vacuum increases, increasing the area of non-contact between the Si wafer and the processing solution and increasing processing unevenness. There is a point.

In view of the above-mentioned problems, the present invention has been developed to provide a plate-like material that can be processed uniformly regardless of the surface properties of the workpiece, such as Si sea urchins, etc., can be processed in large quantities, and can be easily automated. The present invention provides a processing method for

Means for Solving the Problems In order to solve the above problems, the present invention involves exposing the object to be treated to a liquid or gas of a substance that is compatible with the treatment liquid, and then immersing it in the treatment liquid to perform the treatment. The present invention provides a processing method characterized in that the processing liquid adhering to the plate-shaped object is then removed.

Function The present invention enables uniform treatment by the above-described treatment method, regardless of the nature of the surface of the object, such as an uneven surface or a mixture of hydrophilic and hydrophobic portions.

Substances that are compatible with the processing solution used in the present invention must be appropriately selected depending on the type of processing, the properties of the object to be processed, the properties of the processing solution, etc. Because water-based treatment liquids are used exclusively, substances that are compatible with the treatment liquid that can be used include alcohols such as methanol, ethanol, n-7' lovanol, ingropanol, and RIJ col. , ketones such as acetone, carboxylic acids such as acetic acid, esters such as methyl acetate and ethyl acetate, amines such as ethylamine, and sulfonic acids and surfactants alone or in mixtures may be used without any problem, but Si It has a small adsorption capacity to the wafer, is easily replaced by the processing solution, and has a surface tension of 30
Small dyne/z or less, methanol, ethanol,
Methyl acetate monoacetate, ethyl acetate, ethyl acetate, acetone, inglobanol, n-propanol, etc. are suitable. Furthermore, mixtures of these and mixtures of the above compounds and water having a surface tension of 30 dyne/cm or less are suitable.

These substances have -〇H,,O,-COOH in their molecules.

It has hydrophilic groups such as -COO- and -503H and hydrophobic groups such as alkyl groups, and when a Si wafer is exposed to these liquids or vapors (gases), the hydrophilic groups in the hydrophilic part of the S1 wafer Hydrophobic groups are preferentially adsorbed to the hydrophobic portion of the Si wafer, and a cumulative film is formed, so that the entire Si wafer is easily wetted by both hydrophilic and lipophilic processing liquids. Furthermore, since these substances are compatible with the processing solution (aqueous), they may dissolve in the processing solution during processing or cause problems during processing.
Main obstacle + + ridge; convex A 1. - If the compound is less than /7 Mll, the bubbles will be removed immediately, and the bubbles will not remain on the surface of the S1 wafer. As a result, uniform processing is possible without air bubbles adhering to the S1 wafer, and the surface of the St coating is not contaminated.

Furthermore, methods for exposing the Si wafer to a substance that is compatible with the above processing solution include immersing the Si wafer in a liquid substance, and spraying the Si wafer held horizontally or vertically with a liquid substance from a nozzle, etc. There are various methods, such as heating a substance that is compatible with the processing liquid, or applying ultrasonic waves to make it gaseous and exposing the Si wafer to the atmosphere. The immersion method is preferable because the equipment is simple and the risk of gas explosion is low.

Further, as a method for removing the processing liquid adhering to the Si wafer, a method of immersing the Si wafer in pure water or washing the Si wafer by spraying pure water in the form of a shower is generally used. In order to improve the washing effect, functions such as shaking the Si wafer, bubbling ultrasonic waves or gas in the washing tank, or rapidly changing the washing water are added, but which method is used in the present invention? Alternatively, a combination of these methods may be used. Drying methods for Si wafers include spin drying,
The present invention may employ any method, such as steam drying or blow-off drying, or may combine all of these methods.

According to the present invention, the same processing performance can be obtained in both single wafer processing and batch processing, regardless of the number of sheets to be processed.

EXAMPLE A first example of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of the Si wafer etching apparatus used in the first embodiment of the present invention.

In Fig. 1, 1 is an improper tool as a liquid compatible with the processing solution, 2 is a processing solution (etching solution) for Si wafers, 3 is washing water, and 4 is a holding jig for Si wafers (hereinafter referred to as a hanger). ), 5 is a Si wafer as the object to be processed.

The specific contents of this example will be shown below.

Thermal SiO2 films of 3,000, 10,000, and 2o○00 were deposited on a Si wafer (6 inches in diameter) sliced with a (1, O, ○) crystal plane using a pyrogenic method for different processing times. After forming the photoresist 1.2
The film was coated to a thickness of 1.0 μm, and a large number of line-shaped patterns each having a width of 1.6 μm and a length of 0.5 mm were developed over the entire Si sea urchin 6 at a distance of 6 μm. The above Si sea urchin...7, CHF3 and 02
After dry etching the S 102 film using a mixed gas of F6 (pressure force: 00 m Torr), the photoresist was removed using an oxygen plasma resist sprayer.

When the Si wafer 5 at this time was observed under a microscope, a hydrophilic 5LO2 pattern 22 was formed in a straight line on a hydrophobic St single crystal 21, as shown in Fig. 2, regardless of the thickness of the Si wafer. .

On the other hand, the etching apparatus shown in FIG.
S 102 etching solution 2 (hydrofluoric acid:water = 1:200) was used as the processing solution, and isopropanol (surface tension 22-9 dyne) was used as a solution compatible with the etching solution.
/(7)) were placed separately in a tank. As rinsing water, pure water is constantly flowing from the top of the tank.The Si wafers 5 with the above pattern formed thereon are held one by one with a hanger 4 and gently immersed in the isoproper tool 1 for 3 minutes. It was pulled up and then immersed in etching solution 2 for 5 minutes.

While the Si wafer 5 is immersed in the etching solution 2, the S
When the surface of the i-wafer 5 was visually observed, no air bubbles were observed on the S1 wafer 6 of any thickness. The etched Si wafer 5 was sufficiently washed with pure water 3 and then spin-dried.

When the Si wafer 6 that had been subjected to the above treatment was observed under a microscope, the thickness and width of the 5102 film were etched and reduced in each pattern of the Si wafer, but there were no irregularities in the pattern.

On the other hand, the Si wafer 5 on which a pattern of S z 02 g was formed by dry etching and the resist was removed was not immersed in isoproper tool 1, but was directly immersed in etching tool 2 and placed on top of the bath. 'SV, the surface of the S1 wafer 5 is observed from the Si sea urchin... After immersing the Si wafer 5 on the surface of the 5 for 5 minutes, washing thoroughly with pure water 3, and spin drying, the surface of the Si wafer 5 is observed under a microscope. When you look at it, the linear pattern breaks down and becomes 51 as shown schematically in Figure 3.
Many patterns having convex portions 23 remaining after etching were observed on the end face of the 02 film. S102 film is 1Q○○○8,
It was particularly common on Si wafer 5 of 20,000 people. This is because air bubbles were attached when the St sea urchin .

In addition, n-glopanol (surface tension: 25, 3 d
yne 7cm), methanol (surface tension; 24.
0dyne 7m), x tanol (surface tension; 2
4, 1 dyne, /z).

Acetic acid (surface tension; 29.6 dyne/an),
Acetone (surface tension; 26,3 dyne/Ca
n), methyl acetate (surface tension; 28 dyne
/c7n), methyl ethyl ketone (surface tension; 26
, 8 dyne/Cm), but the etched remaining protrusions 23 in FIG. 3 were not observed. (All liquid mixing ratios are volume ratios.

hmm The second example will be described below.

After heating the isoproper tool to 70°C by immersing it in a water bath heated to 100°C, the isoproper tool was placed in the glass speaker.11
The mixture was placed in a desiccator with a lid, and the desiccator was filled with isopropanol vapor.

On the other hand, in the first embodiment, Si
02 S after forming the film pattern and removing the resist
A Si wafer 5 having a t○2 film thickness of 1000 was exposed to the improvator vapor by leaving it for 30 minutes in a desiccator filled with the above improvator vapor. This Si
The sea urchin 6 was held in the etching device 4 of the etching device used in the first example, and the etching solution 2 (hydrofluoric acid:water = 1
= 200) for 5 minutes, washed with pure water 3, and then spin-dried. After drying, the pattern of the St wafer 5 was examined in the same manner as in the first example, and there was no unevenness due to etching residue of the S No. 2 pattern.

However, methanol-zrv is used as a liquid that is compatible with the processing liquid.
, x An experiment similar to the one shown on the right was conducted using tanol, but the results were the same.

The third example will be described below.

A mixed solution of ethanol and acetic acid (ethanol:acetic acid = 6:4, 5:5, and 4:6) was added to the etching apparatus used in the first example as a liquid compatible with the processing solution.
, a mixture of ethanol and water (ethanol:water-8:2,
6:4, 5:5 and 4:6).

Mixture of acetic acid and water (acetic acid: water: 8:2, 6:4°5:5
and 4:6), a mixture of inopropyl alcohol and water (
Inpropyl alcohol: water = e: 4° 5: 5 and 4:
6) and 1:1 of inpropyl alcohol and ethanol
The pattern was inspected after etching, washing and drying in the same manner as in the first example using a mixed solution of the above, and no unevenness due to etching residue was observed. Before processing the processed material - 1 h
口'llTl'Aτ and 4-n, ia, 1/kM, 7.
Bakunote 1 Torokufu: 1. By exposing the material to the 4-ear substance, the entire object to be processed becomes more easily wetted by the processing solution, preventing uneven processing and improving the yield.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the etching apparatus in the first embodiment of the present invention, FIG. 2 is a perspective view of forming a 3102 line pattern on the surface of an S1 wafer by dry etching, and FIG. Si sea urchin showing the condition of the etched residue after etching with air bubbles attached to the sea urchin.
・It is a plan view of. 1,... Isopropanol (liquid compatible with the processing liquid), 2... Hydrofluoric acid solution (processing liquid), 5.
...St wafer (processed object).

Claims (3)

[Claims] (1) After exposing the plate-shaped object to a liquid or gaseous substance that is compatible with the processing liquid, the treatment is performed by immersing it in the processing liquid, and then the plate-shaped object adheres to the processing liquid. A processing method characterized by removing the processing liquid. (2) A patent claim characterized in that the liquid or gaseous substance compatible with the processing liquid contains at least one substance selected from substances having a hydrophilic group and a hydrophobic group in the molecule. The treatment method described in item 1 of the scope. (3) The processing method according to claim 1, wherein the plate-shaped object to be processed is a substrate for manufacturing a semiconductor element having fine irregularities on its surface.