JPH06244182A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To provide a semiconductor device manufacturing method by which exposed wiring can be sufficiently cleaned by suppressing the occurrence of pits in the exposed wiring at the time of cleaning the wiring in a method of manufacturing a semiconductor device provided with the wiring made of an Al alloy containing Cu. CONSTITUTION:After forming a hydrophobic protective film 9 on the exposed surfaces of lower wiring layers (Cu-Al alloy layer 5, TiN film 4, Ti film 3) composed of an Al alloy containing Cu by performing hydrophobic treatment of the surface, the film 9 is washed with water. Alternatively, after forming an oxide film on the exposed surface of lower wiring layers, the hydrophobic protective film 9 is formed on the oxide film and the film 9 is washed with water.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to aluminum (A) containing copper (Cu).
l) A method of cleaning exposed wiring in a process of manufacturing a semiconductor device having wiring made of an alloy.

[0002]

2. Description of the Related Art Conventionally, Al and Al alloys, which have low resistance and excellent workability, have been widely and commonly used as wiring materials for wiring of semiconductor devices. For example, in a semiconductor device having a multi-layer wiring structure, generally, a lower layer wiring made of Al or Al alloy is formed on a semiconductor substrate through an oxide film, and then an interlayer insulating film is formed on the lower layer wiring. , A via hole is formed in this interlayer insulating film for making a connection with an upper layer wiring to be formed later to expose a part of the lower layer wiring, and then Al or Al alloy is formed on the interlayer insulating film by the sputtering method. A layer is formed, and an upper layer wiring connected to the lower layer wiring via the via hole is formed.

In the step of opening the via hole, a resist pattern is formed on the interlayer insulating film as a mask for opening the via hole, and anisotropic etching is performed using the resist pattern as a mask. At this time, the resist and etching gas are used. Further, the substance sputtered from the lower layer wiring is the main component, and a polymer-like deposit is formed on the sidewall of the via hole. This adhered substance cannot be removed by the ashing process performed for removing the resist, and remains on the side wall thereof. When this polymer-like deposit remains, a normal interface is formed between the lower layer wiring and the upper layer wiring in the via hole during the sputtering of the Al alloy for forming the upper layer wiring following the opening of the via hole. There is a problem in that it prevents the formation and causes poor conduction.

Therefore, conventionally, in order to remove the polymer-like deposits, a cleaning process called organic cleaning is performed after forming an interlayer insulating film on the lower layer wiring.
In this organic cleaning step, first, the semiconductor substrate is dipped in a heated stripping solution to remove the deposits and the resist remaining on the sidewalls of the via holes. As the stripping solution used in this washing step, one containing amine as a main component is widely used because the effect of removing the deposits is improved.

However, if the stripping solution containing the amine is mixed with water, it becomes strongly alkaline and the metal is corroded. Therefore, after the stripping treatment with the stripping solution, the stripping solution is removed from the semiconductor substrate using a rinse solution such as IPA (isopropyl alcohol),
Washed and dried. QDR
(Quick Dump Rinse), overflow rinse or the like is used, and the drying is performed by a spin dryer or the like.

In recent years, with the miniaturization and high integration of elements, disconnection of wiring due to electromigration and stress migration has become a problem. Therefore, an Al alloy containing Cu, which has a higher migration resistance, has been used as a wiring material.
Furthermore, wiring having a laminated structure in which a barrier metal such as titanium nitride (TiN) or titanium tungsten (TiW) is combined with the Al alloy containing Cu has come to be used.

[0007]

However, when the above-mentioned organic cleaning method is applied to a wiring made of an Al alloy containing Cu, when the water is washed after the stripping solution treatment and the rinse treatment,
There is a problem that Al is eluted from the exposed portion of the wiring due to the cell effect due to the deposition of Al ₂ Cu, and pits (dents) are generated in the wiring. The occurrence of the pits largely depends on the washing method, the washing time, the drying method, etc., and can be suppressed to some extent by performing the washing in a short time.

However, if the water washing time is shortened, it becomes difficult to obtain a sufficient washing effect, and organic substances may remain on the semiconductor substrate, or particles may not be removed to reduce the yield in the subsequent process. There was a problem. In addition, in order to prevent the precipitation of Al ₂ Cu, it is conceivable to reduce the Cu content in the Al alloy containing Cu that is the material for forming the wiring, but if the Cu concentration is reduced, sufficient migration resistance cannot be obtained. However, there is a problem that it is difficult to use it as a wiring material for forming fine wiring.

Further, as disclosed in JP-A-64-80045, silicon (S
A method of laminating a refractory metal silicide layer having a molar ratio of i) of 0 or more and less than 2 is also introduced. However, in this method, since it is necessary to form the refractory metal silicide layer by a sputtering apparatus, the process is complicated, the manufacturing cost is high, and the silicide film formed between the lower wiring and the upper wiring is complicated. There is a problem that the via resistance easily fluctuates.

An object of the present invention is to solve such a conventional problem, and an Al containing Cu.
In a step of manufacturing a semiconductor device having wirings made of an alloy, when cleaning exposed wirings, it is possible to suppress the formation of pits in the wirings and to perform sufficient washing with water. It is intended to provide a manufacturing method.

[0011]

In order to achieve this object, the invention according to claim 1 is a method of manufacturing a semiconductor device provided with a wiring made of an aluminum alloy containing copper.
A semiconductor device comprising: a step of exposing at least a part of the wiring; a step of performing a hydrophobic treatment on the surface of the exposed wiring; and a step of performing a washing treatment after the hydrophobic treatment. The present invention provides a method for manufacturing the same.

The invention of claim 2 is the same as that of claim 1.
Hydrophobic treatment according to, tetramethyldisilazane (hereinafter,
"TMDS"), hexamethyldisilazane (hereinafter referred to as "HMDS"), or trimethylsilyldiethylamine (hereinafter referred to as "TMSEDA"). Further, the invention according to claim 3 is to perform the hydrophobic treatment according to claim 1 by using a gas containing fluorine.

Further, the invention according to claim 4 is to perform the hydrophobic treatment according to any one of claims 1 to 3 after forming an oxide film on the surface of the exposed wiring. is there. The invention according to claim 5 forms the oxide film according to claim 4 by a heat treatment using oxygen or a plasma treatment using oxygen.

[0014]

According to the invention of claim 1, Al containing Cu
By performing the hydrophobic treatment on the exposed surface of the wiring made of an alloy, a hydrophobic protective film is formed on the exposed surface of the wiring. Then, after the hydrophobic treatment is performed, a water washing treatment is performed, so that the hydrophobic protective film serves as a barrier for protecting the wiring during the water washing treatment. Therefore, it is possible to prevent Al from being eluted from the surface of the wiring during the washing process.

According to the second aspect of the invention, the TM
Using any of DS, HMDS, TMSEDA,
By performing the hydrophobic treatment, a hydrophobic protective film having a further improved barrier effect against washing treatment is formed on the surface of the wiring. According to the invention of claim 3,
By performing the hydrophobic treatment using a gas containing fluorine, a hydrophobic protective film having a further improved barrier effect against washing treatment is formed on the exposed surface of the wiring.

Further, according to the invention of claim 4, after forming an oxide film on the surface of the exposed wiring,
By performing the hydrophobic treatment, an oxide film and a hydrophobic protective film are formed on the exposed wiring. Therefore, the barrier effect against the washing treatment is further improved. Therefore, Al is more effectively prevented from being eluted from the surface of the wiring.

Furthermore, according to the invention of claim 5, the oxide film according to claim 4 is obtained by a heat treatment using oxygen or a plasma treatment using oxygen, whereby the barrier effect against the washing treatment is further improved. Oxide film is formed. Therefore, the elution of Al from the surface of the wiring is more effectively prevented.

[0018]

Embodiments of the present invention will now be described with reference to the drawings. (Embodiment 1) FIGS. 1 to 3 are partial sectional views showing a part of a manufacturing process of a semiconductor device according to Embodiment 1 of the present invention.

In the process shown in FIG. 1, on the semiconductor substrate 1,
An oxide film 2 having a film thickness of about 6000Å is formed. Next, a Ti film 3 having a film thickness of about 500Å is formed on the oxide film 2,
A TiN film 4 having a film thickness of about 1000 Å is laminated thereon. Then, on the TiN film 4, Al containing 0.5% Cu
An alloy is deposited by a sputtering method, and an Al alloy containing Cu having a film thickness of about 6500Å (hereinafter, in the present embodiment, "Cu-
A layer 5).

Next, the Cu-Al alloy layer 5, the TiN film 4 and the Ti film 3 are subjected to desired patterning to form the lower wiring 11 having a three-layer structure. Next, on the oxide film 2 and the surface of the lower layer wiring 11, an interlayer insulating film 6 including a plasma oxide film, an SOG (Spin on Glass) film and a plasma oxide film is formed in order from the semiconductor substrate 1 side with a film thickness of about 10000Å. Form.

Next, a photoresist film is applied on the interlayer insulating film 6, and a portion corresponding to a via hole (a connection hole between the lower layer wiring 11 and an upper layer wiring formed in a later step) opening of the photoresist film. Are selectively removed. Then, using the obtained photoresist pattern as a mask, the interlayer insulating film 6 is anisotropically etched to form the lower layer wiring 1 in this portion.
1 is exposed to form a via hole 7.

Then, ashing using oxygen (O ₂ ) as a source gas is performed to remove the photoresist pattern. At this time, the polymer deposit 8 remained on the sidewall of the via hole 7. Next, in the step shown in FIG. 2, an organic cleaning step for removing the polymer-like deposit 8 remaining in the step shown in FIG. 1 is performed. This organic cleaning
Amine-based stripping solution at 100 ° C (MS2001 (trade name); manufactured by Fuji Hunt Electronics Technology Co., Ltd.)
2 tanks were prepared, and the semiconductor device obtained in the step shown in FIG. 1 was immersed in each tank for 5 minutes, and then immersed in 2 tanks filled with IPA as a rinse solution for 5 minutes each. .

Next, this semiconductor device is placed in a closed container heated to 80 ° C. and brought into contact with HMDS vapor for 2 minutes to form a hydrophobic protective film 9 on the exposed lower layer wiring 11.
To form. Next, in the step shown in FIG. 3, the semiconductor device obtained in the step shown in FIG. 2 is washed with water by a combination of QDR and overflow to remove residual organic substances, particles and the like.

In this water washing step, the hydrophobic protective film 9 formed on the exposed lower layer wiring 11 repels the aqueous solution (water) used for washing and prevents the aqueous solution from coming into contact with the lower layer wiring 11. Therefore, in this water washing process,
Al does not elute from the lower layer wiring 11. Next, after the semiconductor device is dried by using a spin dryer, the hydrophobic protective film 9 is removed by reverse sputtering.

Thereafter, desired steps such as formation of upper layer wiring are performed to complete the semiconductor device. Next, the relationship between the rinsing time (minutes) in the rinsing process performed in Example 1 and the number of pits (number) generated in the exposed lower layer wiring 11 was investigated. The result is shown in FIG. Second Embodiment Next, a second embodiment according to the present invention will be described with reference to the drawings.

FIG. 4 is a partial sectional view showing a part of the manufacturing process of the semiconductor device according to the second embodiment of the present invention. In the second embodiment, the same elements as those in the first embodiment are designated by the same reference numerals, and detailed description of the same steps will be omitted. In the step shown in FIG. 4, the polymer-like deposits 8 remaining on the sidewalls of the via holes 7 in the step shown in FIG. 1 of Example 1 are removed by the organic cleaning treatment performed in the step shown in FIG.

Next, the semiconductor device after the organic cleaning treatment is loaded into a single-wafer type asher, and the O ₂ flow rate = 65 sccc.
m, pressure = 0.6 Torr, microwave power = 800
O ₂ plasma treatment is performed for 60 seconds under the condition of W to form the oxide film 10 on the exposed lower layer wiring 11. Next, the semiconductor device having the oxide film 10 formed therein is placed in a closed container heated to 80 ° C. and brought into contact with HMDS vapor for 2 minutes to form the hydrophobic protective film 9 on the oxide film 10.

Next, the same washing treatment as in the step shown in FIG. 3 of Example 1 is performed to remove residual organic substances, particles and the like, and the semiconductor device is dried using a spin dryer. In this washing step, the exposed lower layer wiring 1
The oxide film 10 and the hydrophobic protective film 9 formed on 1 repel the aqueous solution (water) used for washing and prevent the aqueous solution from coming into contact with the lower layer wiring 11. Therefore, Al is not eluted from the lower layer wiring 11 in this water washing step.

Next, after removing the hydrophobic protective film 9 and the oxide film 10 by reverse sputtering, desired steps are performed to complete the semiconductor device. Next, the relationship between the rinsing time (minutes) in the rinsing process performed in this Example 2 and the number of pits (pieces) generated in the exposed lower layer wiring 11 was investigated. The result is shown in FIG. (Third Embodiment) Next, a third embodiment according to the present invention will be described with reference to the drawings.

In the third embodiment, the same elements as those in the first embodiment are designated by the same reference numerals, and detailed description of the same steps will be omitted. First, the polymer-like deposit 8 remaining on the sidewall of the via hole 7 is removed by the organic cleaning process using IPA performed in the process shown in FIG. 2 in the process shown in FIG.

Next, this semiconductor device is set to 40 at atmospheric pressure.
The film is exposed to a CHF ₃ gas atmosphere at 0 ° C. for 1 minute to form the hydrophobic protective film 9 on the exposed lower layer wiring 11. Then, the same washing treatment as in the step shown in FIG. 3 of Example 1 is performed to remove residual organic substances, particles and the like. In this water washing step, the hydrophobic protective film 9 formed on the exposed lower layer wiring 11 repels the aqueous solution (water) used for washing and prevents the lower layer wiring 11 from being contacted with the aqueous solution. Therefore, Al is not eluted from the lower layer wiring 11 in this water washing step.

Next, the semiconductor device is dried using a spin dryer, and then the hydrophobic protective film 9 and the oxide film 10 are removed by reverse sputtering. Then, desired steps are performed to complete the semiconductor device. Next, the washing time (minutes) in the washing treatment performed in this Example 3 and the exposed lower layer wiring 1
The relationship with the number of pits (number) generated in 1 was investigated.

The results are shown in FIG. (Fourth Embodiment) Next, a fourth embodiment according to the present invention will be described with reference to the drawings. In the fourth embodiment, the same elements as those in the first embodiment are designated by the same reference numerals, and detailed description of the same steps will be omitted.

First, according to the process shown in FIG.
Polymer-like deposit 8 remaining on the sidewall of the via hole 7
Is an organic cleaning process using IPA performed in the step shown in FIG.
Remove by reason. Then, the semi-conductor after this organic cleaning treatment
Insert the body device into the single-wafer type asher, and ₂Flow rate = 65
sccm, pressure = 0.6 Torr, microwave power =
O for 60 seconds under the condition of 800W₂Plasma processing
Forming an oxide film 10 on the exposed lower wiring 11
To do.

Next, this semiconductor device is subjected to 40 at atmospheric pressure.
The film is exposed to a CHF ₃ gas atmosphere at 0 ° C. for 1 minute to form the hydrophobic protective film 9 on the exposed lower layer wiring 11. Then, the same washing treatment as in the step shown in FIG. 3 of Example 1 is performed to remove residual organic substances, particles and the like. In this rinsing step, the oxide film 10 and the hydrophobic protective film 9 formed on the exposed lower layer wiring 11 repel the aqueous solution (water) used for rinsing to prevent the aqueous solution from contacting the lower layer wiring 11. . Therefore, Al is not eluted from the lower layer wiring 11 in this water washing step.

Next, the semiconductor device is dried by using a spin dryer, and then the hydrophobic protective film 9 and the oxide film 10 are removed by reverse sputtering. Then, desired steps are performed to complete the semiconductor device. Next, the washing time (minutes) in the washing treatment performed in this Example 4 and the exposed lower layer wiring 1
The relationship with the number of pits (number) generated in 1 was investigated.

The results are shown in FIG. (Comparative Example) Next, as a comparison, the hydrophobic protective film 9 according to the present invention, or the semiconductor device on which the oxide film 10 and the hydrophobic protective film 9 are not formed, is subjected to the same washing treatment as in the first embodiment. Then, a semiconductor device (conventional product) was manufactured.

Next, the relationship between the rinsing time (minutes) in the rinsing process performed in this comparative example and the number of pits (pieces) generated in the exposed lower layer wiring 11 was investigated. The result is shown in FIG. From FIG. 5, it was proved that the semiconductor devices (invention products) obtained in Examples 1 to 4 had a significantly smaller number of pits than the conventional products. And, in particular,
It can be seen that the number of pits generated is extremely reduced in the semiconductor devices manufactured in Examples 2 and 4 and in which both the oxide film 10 and the hydrophobic protective film 9 are formed.

This is because the hydrophobic protective film 9 formed on the exposed lower wiring 11 or the oxide film 10 and the hydrophobic protective film 9 serve as a barrier during the washing process.
This is because Al could be prevented from being eluted from the surface of the lower layer wiring 11. In addition, in the first to fourth embodiments, the case of cleaning the semiconductor device in which a part of the lower layer wiring 11 is exposed has been described, but the present invention is not limited to this. As a matter of course, the cleaning method can be applied to a wiring cleaning method performed in various steps such as a pad hole forming step and a wiring forming step as long as it is a semiconductor device in which wiring made of an Al alloy containing Cu is exposed. Is.

In the first and second embodiments, the HMD is applied to the semiconductor device after the stripping solution treatment and the rinse solution treatment.
Performs a hydrophobic treatment with S vapor, has formed the hydrophobic protective film 9, not limited to this, for example, a HMDS vapor vaporized in N ₂ by N ₂ bubbling, contact with heated said semiconductor device You may let me. Further, TMDS or TMSEDA may be used instead of HMDS. And
The heating temperature, time, etc. when forming the hydrophobic protective film 9 may be determined as desired.

Further, in the third and fourth embodiments,
For semiconductor devices that have been stripped and rinsed,
Hydrophobic treatment using CHF ₃ gas was performed to form the hydrophobic protective film 9. However, the present invention is not limited to this, and other gases such as CF ₄ , CH ₂ F ₂ and SF ₆ can be used as long as the gas contains fluorine. You may form the hydrophobic protective film 9 using. Further, in Examples 2 and 4, the semiconductor device before the formation of the hydrophobic protective film 9 was subjected to O ₂ plasma treatment to form the oxide film 10 on the exposed lower layer wiring 11. Not limited to this, the oxide film 10 may be formed by a desired oxidation process such as performing a heat treatment using O ₂ on the exposed lower layer wiring 11.

Further, in the second and fourth embodiments,
Although the oxide film 10 is formed on the lower layer wiring 11 of the semiconductor device after the stripping solution treatment and the rinse solution treatment, the present invention is not limited to this, and the oxide film 10 is formed on the exposed lower layer wiring 11 before the stripping solution treatment. You may. Further, in Examples 1 to 4, the hydrophobic protective film 9 and the oxide film 10 were removed after the water washing treatment, but the present invention is not limited to this, and the hydrophobic protective film 9 and the oxide film 1 are not limited thereto.
0 may not necessarily be removed if desired.

Further, the stripping solution treatment and the rinsing solution treatment carried out in the first to fourth embodiments are only examples, and the stripping solution treatment and the rinsing solution treatment carried out by the semiconductor device cleaning method according to the present invention are usually performed. It may be performed according to the known method. And as the above-mentioned stripping solution, for example, one containing alkylpyrrolidone and triethanolamine as main components, one containing diethylene glycol monobutyl ether and monoethanolamine as main components, and N-methyl-2
-Pyrrolidone (NMP) and those containing dimethyl sulfoxide as a main component, and the like.

As the rinse liquid, for example, I
Examples include PA, methanol, ethanol and the like. Then, in Examples 1 to 4, the semiconductor device having the hydrophobic protective film 9 formed thereon was washed with water by a combination of QDR and overflow. However, the present invention is not limited to this.
Washing with various washing methods and combinations thereof, such as washing with R only, washing with overflow rinse, and washing with pure water at 25 ° C. can be performed.

Further, in Examples 1 to 4, drying using a spin dryer was performed after the water washing treatment, but not limited to this, drying using IPA vapor, drying by pulling warm water, and the like can be performed. The drying method can be performed.

[0046]

As described above, in the method for manufacturing a semiconductor device according to the first aspect, since the surface of the wiring made of the Al alloy containing Cu is subjected to the hydrophobic treatment, the surface of the wiring is covered with the hydrophobic protective film. Can be formed. Then, since the water washing treatment is performed after the hydrophobic treatment, the hydrophobic protective film serves as a barrier during the water washing treatment, and it is possible to prevent Al from being eluted from the surface of the wiring. . Therefore, it is possible to prevent the formation of pits in the wiring layer, and it is possible to perform sufficient water washing. As a result, it is possible to efficiently manufacture a highly accurate and highly reliable semiconductor device.

According to the second aspect of the invention, the TM
By performing the hydrophobic treatment using any one of DS, HMDS and TMSEDA, it is possible to form a good hydrophobic protective film having a higher barrier effect on the surface of the wiring. As a result, a highly accurate and highly reliable semiconductor device
It is possible to manufacture it more efficiently. Furthermore,
According to the invention of claim 3, by performing the hydrophobic treatment using a gas containing fluorine, the surface of the wiring is
A good hydrophobic protective film having a higher barrier effect can be formed. As a result, a highly accurate and highly reliable semiconductor device can be manufactured more efficiently.

According to the fourth aspect of the present invention, by further forming the oxide film on the surface of the wiring and then performing the hydrophobic treatment, the barrier effect on the surface of the wiring layer is further improved. You can Therefore, the elution of Al from the surface of the wiring layer can be prevented more effectively. As a result, a highly accurate and highly reliable semiconductor device can be manufactured more efficiently.

According to the fifth aspect of the invention, the oxide film is obtained by heat treatment using oxygen or plasma treatment using oxygen, so that an oxide film having a further improved barrier effect against water washing treatment is obtained. be able to. Therefore, the elution of Al from the surface of the wiring can be prevented more effectively. As a result, a highly accurate and highly reliable semiconductor device can be manufactured more efficiently.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing a part of a manufacturing process of a semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a partial cross-sectional view showing a part of the manufacturing process of the semiconductor device according to the first embodiment of the invention.

FIG. 3 is a partial cross-sectional view showing a part of the manufacturing process of the semiconductor device according to the first embodiment of the present invention.

FIG. 4 is a partial cross-sectional view showing a part of the manufacturing process of the semiconductor device according to the second embodiment of the invention.

FIG. 5 is a diagram showing the relationship between the washing time and the number of pits, and the relationship between the washing time and the number of pits of a conventional product in Examples 1 to 4 of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 Oxide film 3 Ti film 4 TiN film 5 Cu-Al alloy layer 6 Interlayer insulating film 7 Via hole 8 Polymer deposit 9 Hydrophobic protective film 10 Oxide film 11 Lower layer wiring

Claims (5)

[Claims] 1. A method of manufacturing a semiconductor device having a wiring made of an aluminum alloy containing copper, comprising: exposing at least a part of the wiring; and subjecting the exposed surface of the wiring to a hydrophobic treatment. A method of manufacturing a semiconductor device, comprising: a step; and a step of performing a water washing treatment after the hydrophobic treatment. 2. The method of manufacturing a semiconductor device according to claim 1, wherein the hydrophobic treatment is performed using any one of tetramethyldisilazane, hexamethyldisilazane, and trimethylsilyldiethylamine. 3. The method for manufacturing a semiconductor device according to claim 1, wherein the hydrophobic treatment is performed using a gas containing fluorine. 4. The manufacturing of the semiconductor device according to claim 1, wherein after the oxide film is formed on the surface of the exposed wiring, the hydrophobic treatment is performed. Method. 5. The method of manufacturing a semiconductor device according to claim 4, wherein the oxide film is formed by heat treatment using oxygen or plasma treatment using oxygen.