JPH1197401A - Semiconductor substrate cleaning method and semiconductor device manufacturing method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively clean and dry a substrate, by supplying a cleaning solution previously deaerated into a cleaning chamber and cleaning the substrate. SOLUTION: Even when a high aspect ratio structure like a miniaturization process groove 11 is formed on the surface of a semiconductor water (a) by deaerating a cleaning solution and depressurizing a cleaning chamber, the air 12 in the groove melts into the cleaning solution while the groove is immersed in the cleaning solution 3, infiltration of the cleaning solution 3 into the groove 11 is promoted (b), and the cleaning solution 3 is sufficiently infiltrated to the bottom of the groove 11. After removing the cleaning solution from the semiconductor wafer by taking up the semiconductor wafer from the cleaning solution 3 or ejecting the cleaning solution from a cleaning bath, etc., (e), the drying chamber is depressurized for drying the substrate (t) Drying can be more efficiently performed by heating the water from the rear surface simultaneously with depressurization.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning method applied to a manufacturing process of many electronic parts such as electronic materials, magnetic materials, optical materials, and ceramics (hereinafter, general cleaning methods, surface treatment methods, etc.). In particular, the present invention relates to a semiconductor substrate cleaning method suitable for a semiconductor device manufacturing process and a semiconductor device manufacturing method using the same.

[0002]

2. Description of the Related Art Conventional cleaning and drying of a semiconductor wafer is performed by immersing the wafer in a cleaning solution such as diluted hydrofluoric acid or a mixed solution of ammonia and hydrogen peroxide solution for a predetermined time, and then cleaning the wafer with pure water. The wafer is washed with water, followed by spin drying or I
It is performed by a method of drying a wafer by PA (isopropyl alcohol) vapor drying or the like.

As another cleaning method, there has been known a method in which a semiconductor wafer is immersed in a cleaning liquid in a cleaning tank and the cleaning liquid is vibrated by an ultrasonic generator (for example, JP-A-63-14434). It is described in).

In this prior art, a plurality of ultrasonic generators are arranged so as to surround a semiconductor wafer immersed in a cleaning liquid, and an ultrasonic energy beam is irradiated on a main surface of the wafer to process the wafer surface. The ultrasonic energy is applied to each surface in the fine and deep groove.

[0005]

In recent years, in order to increase the density of an integrated circuit, a fine deep groove (width 1 μm or less, depth 5 μm or more) almost perpendicular to a main surface of a semiconductor wafer is dry-dried. Attempts have been made to process by etching or the like, to form element isolation using this groove, or to increase the capacitance of the capacitor.

[0006] In a cleaning method in which a semiconductor wafer on which a high-density semiconductor integrated circuit having a highly uneven surface and a complicated surface shape is formed is simply immersed in a chemical solution and pure water, the chemical solution and pure water are formed in a deep groove portion on the surface. It is difficult to replace, and the cleaning effect is significantly reduced.

On the other hand, a method of washing a semiconductor wafer by immersing the semiconductor wafer in a cleaning liquid in a cleaning tank and vibrating the cleaning liquid by an ultrasonic generator has been known (Japanese Patent Application Laid-Open No. 63-14434). No.). In this conventional technique, a plurality of ultrasonic generators are arranged so as to surround a semiconductor wafer immersed in a cleaning liquid, and an ultrasonic energy beam is irradiated on a main surface of the wafer, and ultrasonic waves are applied to each surface in the groove. It is intended to provide energy.

However, in such a cleaning technique, the grooves of the semiconductor wafer described above are sufficiently cleaned.
In addition to the necessity of a large number of ultrasonic generators, the ultrasonic irradiation may cause damage such as cracks to the semiconductor element.

In addition, contaminants adhering to the inner surface of the processing groove together with the sacrificial oxide film by removing the semiconductor wafer having the sacrificial oxide film formed on the inner surface of the processing groove formed by dry etching by wet etching. The removal has been done. However, as described above, since the opening of the groove is fine and deep as described above, the etching liquid and the cleaning liquid after the etching did not sufficiently penetrate into the groove, and a satisfactory groove surface treatment could not be performed. .

Further, even during drying, moisture present in a complex-shaped portion such as a deep groove-shaped portion such as a crown shape or a stack structure represented by a fin-shaped shape such as a fin is removed by the spin drying described above. It is difficult to remove sufficiently by a drying method such as drying or IPA drying. If cleaning and drying are insufficient, various inconveniences such as deterioration of the film quality occur in the subsequent processes such as the formation of a thin film, and have a serious adverse effect on the reliability of the integrated circuit.

SUMMARY OF THE INVENTION The present invention has been made in view of such conventional problems, and has been made in consideration of the above-described problems, and has been made in consideration of the above-described problems. A method and a method for manufacturing a semiconductor device using the same.

[0012]

The above object is achieved as follows. That is, the cleaning method of the present invention is characterized in that a cleaning liquid degassed in advance is supplied into a cleaning processing chamber to clean a target substrate such as a semiconductor substrate.
Preferably, the pressure in the processing chamber in which the semiconductor substrate is accommodated is reduced, and the semiconductor substrate is cleaned by supplying a degassed cleaning liquid into the processing chamber.

[0013] Further, such a cleaning method comprises a process chamber capable of containing a semiconductor substrate, a means for degassing the cleaning liquid in advance, and a means for supplying the pre-degassed cleaning liquid into the processing chamber. And, by using a cleaning device having a decompression means for adjusting the decompression state in the processing chamber,
It can be easily implemented.

As the supplied cleaning liquid, water or a chemical is used. For example, an organic acid containing hydrofluoric acid, hydrochloric acid, sulfuric acid, nitric acid, and acetic acid (acetic acid alone may be used).
An acidic solution containing at least one acid of the above, an acidic solution containing the acidic solution and at least one of aqueous hydrogen peroxide and ammonium fluoride, an alkaline solution containing aqueous ammonia and at least one of an amine, and the alkaline solution , An alkaline solution containing hydrogen peroxide and at least one of ammonium fluoride, a mixed solution containing the above-mentioned acidic solution and the above-mentioned alkaline solution, or a neutral solution containing water (or water alone) And commercially available well-known washing liquids.

Furthermore, commercially available surfactants such as cationic surfactants, anionic surfactants and amphoteric surfactants, organic solvents, or mixtures of these surfactants and organic solvents are added to the washing liquid. Agents can be used in combination.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The outline of the present invention will be described with reference to the basic conceptual diagram shown in FIG. First, the pressure in the cleaning chamber 2 is reduced in advance by the pressure reducing device 1 shown in FIG. 1A, and then the cleaning liquid 3 is supplied to the cleaning liquid deaerator 4 to deaerate the cleaning liquid.
To the cleaning tank 6 via Thereafter, as shown in FIG. 1B, the semiconductor wafer 8 accommodated in the wafer carrier 7 is
Is immersed in the washing tank 6 for washing. Next, the semiconductor wafer is transferred to the drying chamber 10 by the wafer transfer device 9 and dried under reduced pressure in the drying chamber. The drying chamber 10 is depressurized to a predetermined pressure by the depressurization adjusting device 1.

FIG. 2 shows another cleaning method of the present invention.
As shown in the conceptual diagram of FIG. 1A, the cleaning chamber 2 is depressurized in advance by the depressurization adjusting device 1, and then the cleaning liquid 3 is supplied to the cleaning liquid deaerator 4 to be degassed. 3 is supplied to the washing room. As shown in FIG. 2B, the semiconductor wafer 8 stored in the wafer carrier 7 is immersed in the cleaning tank 6 for cleaning. After that, after the cleaning liquid is drained, there is also a method in which the pressure in the cleaning chamber 2 is reduced again by the pressure-reducing device 1 and drying is performed as shown in FIG.

FIGS. 1 and 2 show only an example of the present invention and are not shown. However, it is needless to say that the present invention can be applied to a single-wafer cleaning apparatus for cleaning one wafer at a time.

According to the present invention, even if a high aspect ratio structure such as the fine processing groove 11 is formed on the surface of the semiconductor wafer shown in FIG.
By reducing the pressure to about 0 to 200 Torr, the air 12 in the fine processing groove on the substrate surface is dissolved in the cleaning liquid while being immersed in the cleaning liquid 3 as shown in FIG.
The penetration of the cleaning liquid 3 into the inside is promoted, and as shown in FIG. 3D, the cleaning liquid 3 sufficiently penetrates to the bottom in the micro-machining groove 11. Then, as shown in FIG. 3 (e), after removing the cleaning liquid from the semiconductor wafer, for example, by pulling up the semiconductor wafer from the cleaning liquid 3 or discharging the cleaning liquid from the cleaning tank, as shown in FIG. 3 (f). Then, the drying chamber is evacuated to about 10 mTorr and dried.
Note that by performing heating from the back surface of the wafer simultaneously with the pressure reduction, drying can be performed more efficiently.

According to the present invention, foreign substances adhering to the inside of the fine processing groove can be more reliably removed, and as described in "Problems to be Solved by the Invention", removal of an oxide film at the time of forming a capacitor becomes easier. Therefore, it is possible to provide a semiconductor wafer cleaning method capable of improving the quality and yield of a semiconductor wafer and a method of manufacturing a semiconductor device using such a cleaning method.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A typical embodiment of the present invention will be described below with reference to the drawings. <Embodiment 1> FIG. 4 (a) is a schematic diagram of a cleaning evaluation sample, and FIG. 4 (b) is a schematic diagram of a cross section thereof. The cleaning effect on Fe adsorbed inside the microfabricated groove provided in the semiconductor wafer was confirmed by the following procedure. The cleaning evaluation sample (wafer) 13 is formed by forming a poly-Si film 15 on a Si substrate 14 and forming a micro-machined groove 11 having a hole diameter of 0.5 μm and a depth of 2 μm in the poly-Si.

The following was performed to adsorb Fe ions on the cleaning evaluation wafer. A mixed solution of ammonia, hydrogen peroxide and ultrapure water (provided that the solution has a pH of 11
Fe ion was dropped into
Heated to 0 degrees. Next, the cleaning evaluation wafer was immersed in the mixed solution for 24 hours and washed with water for 20 minutes. Then I
The sample was dried for 20 minutes with a PA vapor drying apparatus to prepare a sample for cleaning evaluation in which Fe ions were adsorbed.

Then, F adsorbed on the cleaning evaluation sample
In order to measure e-ion, 10 samples for cleaning evaluation were
The sample was immersed in 0 degree hot water for 30 minutes, and the hot water was collected and the amount of Fe adsorption remaining in the sample for evaluation was measured by an atomic absorption spectrometer.

The wafer 13 was cleaned by the cleaning method according to the present invention shown in FIG. 2 and the conventional cleaning method disclosed in, for example, JP-A-63-14434. As the cleaning liquid, a mixed cleaning solution of hydrofluoric acid, hydrogen peroxide solution and ultrapure water (however, the mixing ratio was adjusted so that the solution had a pH of 3) was prepared.

Each of the samples 2 washed by the present invention and the conventional washing method
Table 1 shows the measurement results of the residual amounts of Fe adsorption in the five cleaning evaluation samples. In the present invention, any sample is equal to or less than the lower limit of Fe ion detection of the measuring device (at most 0.4 ppb).
It became. However, in the conventional cleaning method, Fe ions were detected, indicating the superiority of the cleaning effect of the present invention.

[0026]

[Table 1]

Embodiment 2 In a semiconductor manufacturing process, a general wiring forming process using Al (for example,
No. 255) describes an example in which the present invention is implemented.

FIG. 5 is a schematic cross-sectional view of a semiconductor substrate. In FIG. 5A, reference numeral 14 denotes a Si substrate, and 16 denotes S
An oxide film formed on the surface of the i-substrate 14, 17 is an Al electrode, and 18 to 20 are interlayer insulating layers.
SiO ₂ formed by CVD (chemical vapor deposition) method
The film 18 (thickness 2000), the SOG film 19 (thickness 600)
To 1200 °), and a three-layer structure of a SiO ₂ film 20 (film thickness 2000 °) formed by the CVD method.

As shown in FIG. 5A, a through hole 21 having a hole diameter of 1.2 μm is formed in the interlayer insulating film layer by dry etching using fluorocarbon CF ₃ , C ₂ F ₆ or the like. Then, the Al electrode 17 on the semiconductor substrate is exposed.

Next, according to the present invention, the semiconductor substrate is washed for 15 minutes with a processing solution comprising, for example, an organic alkali solution at 80 ° C. to remove by-products 22 generated during dry etching shown in FIG. 5B. did. Next, water washing was performed for 20 minutes.

Next, since moisture has penetrated into the through-hole 21, it was dried in an atmosphere of about 10 mTorr according to the present invention. In this state, on the Al electrode 17 exposed from the through hole 21, no generation of an insulator such as thin alumina Al ₂ O ₃ generated by the conventional cleaning method performed in Example 1 was observed. Next, an Ar sputtering process or the like is performed.

Further, as shown in FIG. 5C, an Al wiring layer 17 'is formed on the surface of the substrate including the Al electrode 17 for multilayering, and this is patterned to form a wiring connected to the Al electrode 17. In the case of formation, the same procedure as described above may be followed.

After the wiring was formed in the above steps, the connection status of each wiring layer was examined. As a result, the contact resistance of the wiring layer was extremely small as compared with the conventional connection, and the defect rate was reduced by 5% as compared with the conventional method. Therefore,
According to the present invention, semiconductors can be manufactured with high quality and high yield.

<Embodiment 3> In the manufacturing process of the semiconductor device,
The present invention was implemented in a general wiring forming process using Cu (for example, described in JP-A-6-326101).
FIG. 6 is a cross-sectional view illustrating an example of a manufacturing process of the semiconductor device at that time.

As shown in FIG. 6A, on a semiconductor substrate 23 having a diffusion layer and the like (not shown), an insulating film (for example, B
PSG film 24 (boron phosphorus silicate glass)
It is formed by the VD method. Subsequently, a Ti film 25 is formed thereon by sputtering, and a TiN film 26 is formed thereon,
Further, a Cu film 27 is deposited thereon.

Next, as shown in FIG. 6B, a resist 28 is applied on the structure, and a well-known photolithography is performed.
Patterning is performed by etching technology. Subsequently, FIG.
As shown in (c), the Cu film, TiN film and Ti film are patterned using the resist 28 as a mask. That is, the portions other than the portions that become the wirings are removed by etching.

Next, as shown in FIG. 6D, after the resist 28 is removed, a mixed cleaning solution of hydrofluoric acid, hydrogen peroxide and ultrapure water (however, the mixing ratio is adjusted so that the solution has pH = 3). Was degassed according to the cleaning method of the present invention described in Example 1 and supplied to a reduced-pressure cleaning chamber for cleaning.

Next, the wiring portion having a three-layer structure of the Ti film, the TiN film, and the Cu film remaining in the above step is covered with the W film 29 by the CVD method shown in FIG. Next, as shown in FIG. 6F, the whole is formed with a passivation film 30 (for example, TiN
A film) was formed by a CVD method to complete a structure mainly including a wiring portion.

Conventional cleaning apparatus (method described in Embodiment 2)
As compared with the case of the method for manufacturing a semiconductor device to which the cleaning method of the present invention was applied, the defect rate was reduced by 5%, and the semiconductor device could be manufactured with high quality and high yield.

[0040]

As described in detail above, the present invention has achieved the intended purpose. In other words, by supplying the degassed cleaning liquid to the depressurized cleaning chamber, the cleaning liquid easily penetrates into the semiconductor wafer having a complicated surface shape with severe irregularities, and cleaning and drying can be performed effectively. Further, the present invention is not limited to cleaning of a semiconductor wafer,
Needless to say, the present invention can be applied to cleaning of substrates such as thin film devices and disks.

[Brief description of the drawings]

FIG. 1 is a block diagram of a cleaning method illustrating a basic concept of the present invention.

FIG. 2 is a block diagram of another cleaning method showing an example of the basic concept of the present invention.

FIG. 3 is a schematic view schematically showing infiltration and drying of a cleaning solution into the inside of a fine processing groove.

FIG. 4 is a schematic view of a cleaning evaluation sample.

FIG. 5 is a sectional process view of the semiconductor device when the present invention is applied to a wiring process using Al in a manufacturing process of the semiconductor device.

FIG. 6 is a sectional process view of the semiconductor device when the present invention is applied to a wiring process using Cu in a manufacturing process of the semiconductor device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Pressure reduction apparatus, 2 ... Cleaning room, 3 ... Cleaning solution, 4 ... Cleaning solution deaerator, 5 ... Cleaning solution supply device, 6 ... Cleaning tank, 7 ... Wafer carrier, 8 ... Semiconductor wafer, 9 ... Wafer transfer device, 10 ... Drying room, 11 ... Fine processing groove,
12 ... air, 13 ... sample for cleaning evaluation, 14 ...
Si substrate, 15: poly Si, 16: oxide film, 17: Al electrode, 17 ': Al wiring layer,
18 ... SiO ₂ film, 19 ... SOG film, 20 ...
SiO ₂ film, 21 through-hole, 22 by-product, 23 semiconductor substrate, 24 BPS
G film, 25 ... Ti film, 26 ... TiN film,
27: Cu film, 28: resist,
29: W film, 30: Passivation film.

Claims (10)

[Claims] 1. A method for cleaning a semiconductor substrate, comprising: supplying a cleaning liquid degassed in advance to a processing chamber when cleaning the semiconductor substrate with the cleaning liquid. A step of degassing the cleaning liquid in advance, a step of depressurizing the processing chamber in a state where the substrate to be processed is stored in advance, and a step of supplying the degassed cleaning liquid into the processing chamber in the depressurized state. Cleaning the substrate to be processed. 3. The method for cleaning a semiconductor substrate according to claim 1, wherein the cleaning liquid comprises water or a chemical solution. 4. A cleaning solution comprising hydrofluoric acid, hydrochloric acid, sulfuric acid,
An acidic solution containing at least one acid of an organic acid including nitric acid and acetic acid, an acidic solution containing the acidic solution and at least one of aqueous hydrogen peroxide and ammonium fluoride,
An alkaline solution containing ammonia water and at least one amine, an alkaline solution containing the alkaline solution and at least one of hydrogen peroxide solution and ammonium fluoride, and a mixture containing the acidic solution and / or the alkaline solution The method for cleaning a semiconductor substrate according to any one of claims 1 to 3, comprising a liquid or a neutral solution containing water. 5. The method for cleaning a semiconductor substrate according to claim 1, wherein the cleaning liquid comprises an organic solvent. 6. The method for cleaning a semiconductor substrate according to claim 4, wherein the cleaning liquid contains at least one of a surfactant and an organic solvent as an additive. 7. The method according to claim 6, wherein the surfactant comprises at least one of a cationic surfactant, an anionic surfactant, and an amphoteric surfactant. 8. A method for manufacturing a semiconductor device having at least a semiconductor substrate cleaning step, wherein the cleaning step is constituted by the method for cleaning a semiconductor substrate according to claim 1 or 2. 9. A process chamber capable of containing a semiconductor substrate, a means for degassing a cleaning liquid in advance, a means for supplying the pre-degassed cleaning liquid into the processing chamber, and a pressure reduction in the processing chamber. 9. The method of manufacturing a semiconductor device according to claim 8, wherein the cleaning apparatus is provided with a pressure reducing means for adjusting a state of the semiconductor device, wherein the semiconductor substrate housed in the processing chamber is cleaned. 10. A cleaning solution comprising: an acidic solution containing at least one kind of organic acids including hydrofluoric acid, hydrochloric acid, sulfuric acid, nitric acid, and acetic acid; An acidic solution containing at least one kind thereof; an alkaline solution containing ammonia water and at least one kind of amine; an alkaline solution containing the above-mentioned alkaline solution and at least one kind of aqueous hydrogen peroxide and ammonium fluoride; 10. The method of manufacturing a semiconductor device according to claim 9, comprising a mixed solution containing the above or an alkaline solution or a neutral solution containing water.