JP3334489B2 - Semiconductor device manufacturing method and manufacturing apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bonding electrode forming method and an electrode forming apparatus used for bare chip mounting of a semiconductor device.

[0002]

2. Description of the Related Art In recent years, in an electrode forming method for forming a bonding electrode on an Al electrode of a semiconductor element by an electroless plating method, all of the forming steps are performed by a wet process.

[0003] An example of an electrode forming method using the above-described conventional electroless plating method will be described below with reference to the drawings.

FIG. 5 is a cross-sectional view of a semiconductor device in the vicinity of an Al electrode before an electrode is formed by electroless plating. FIG. 6 is a cross-sectional view of the semiconductor device shown in FIG. FIG. 4 is a cross-sectional view showing a step of forming an electrode by an electrolytic plating method. 5 and 6, 1 is an Al electrode of a semiconductor device, 2 is a natural oxide film, 6 is a semiconductor device, 2
8 is a protective film, 33 is a silicon oxide film, 3 is a Zn particle film,
4 is a Ni film and 5 is an Au film.

Next, a conventional method for forming electrodes on a semiconductor element by electroless plating will be described with reference to FIG.

First, FIG. 6A shows a wet etching step of the Al electrode 1 formed on the semiconductor element 6. In this step, the natural oxide film 2 formed on the surface of the Al electrode 1 is removed by immersion in an aqueous solution of phosphoric acid or sodium hydroxide. Next, FIG.
A Zn particle film is formed on the Al electrode 1 as shown in FIG. Although the natural oxide film was removed by the above-described process of FIG. 6A, if the natural oxide film was left as it was, the natural oxide film would be disregarded on the Al electrode 1 again. In order to prevent the formation, the semiconductor element is immersed for 30 seconds in an alkaline (pH 13 to 14) solution containing Zn, which is kept at room temperature, so that the Al and the Zn ions in the solution are used for the substitution reaction. A Zn particle film 3 having a thickness of about 300 to 500 ° is formed on the surface of the electrode 1.

Next, as shown in FIG. 6C, Ni plating is formed on the Al electrode 1 by an electroless plating method. By dissolving the Zn particle film 3 formed in the step of FIG. 6B in the electroless Ni plating solution, Zn and the electroless N
After the deposition of Ni by the substitution reaction of Ni ions in the i-plating solution, Ni is reduced by the self-reduction reaction of the electroless Ni plating solution.
Ni is self-precipitated on the top, and a Ni film 4 is formed. Further, as shown in FIG. 6D, an Au film is formed on the formed Ni film 4 by an electroless plating method. This is the Ni film 4
This is a step performed solely to improve the poor electrical connection due to the presence of the Ni oxide film. In order to enhance the electrical connectivity, the Au film 5 is mixed with Ni in the electroless Au plating solution. It is formed by a substitution reaction with Au ions.

The electrodes shown in FIGS. 6A to 6D are usually formed in the atmosphere.

[0009]

As described above, in order to form a metal film on an Al electrode of a semiconductor device by an electroless plating method utilizing a chemical reaction, a strong natural oxide film exists on the surface of the Al electrode. In order to cause a reaction of electroless plating on the surface of the Al electrode,
l Removal of the natural oxide film on the electrode surface is essential.

However, in the electrode formation using the conventional electroless plating method as described above, since the natural oxide film is removed by wet etching, the etching state is not constant depending on the thickness and density of the natural oxide film. In addition, since the oxygen in the air or the dissolved oxygen in the solution or the cleaning water causes a re-formation of the natural oxide film on the surface of the Al electrode from which the natural oxide film has been removed, a processing step of forming the Zn particle film 3 is required. It will be indispensable. Further, the Zn particle film 3 has a problem that the adhesion between the Al electrode and the metal film formed by electroless plating is deteriorated.

[0011]

In order to solve the above-mentioned problems, the method of forming an electrode on a semiconductor device according to the present invention comprises removing a natural oxide film on an Al electrode of the semiconductor device by dry etching and controlling the atmosphere to an inert atmosphere. The method includes a step of transporting a semiconductor element under an environment and forming a metal film by an electroless plating method.

With the above structure, the present invention completely prevents the re-formation of the native oxide film of the Al electrode by performing the plating process in an inert atmosphere, and prevents the formation of the native oxide film. The processing steps such as the formation of the Zn particle film 3 can be omitted. As a result, it is possible to form an electrode by electroless plating having good adhesion and high connectivity.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for forming a bonding electrode on a semiconductor device according to an embodiment of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a sectional view of a semiconductor device having a bonding electrode according to Embodiment 1 of the present invention, and FIG. 2 is a schematic view of an apparatus for forming a bonding electrode according to the present embodiment. 3 is a sectional view showing a step of forming a bonding electrode for a semiconductor element. 1 to 3, 1 is an Al electrode, 6 is a semiconductor element, and 7 is Ni
Reference numeral 8 denotes an Au film.

Therefore, the bonding electrode in the semiconductor device shown in FIG. 1 will be described below. A Ni film is formed on an Al electrode 1, which is an external electrode of a semiconductor element, by electroless plating, and an Au film is electrolessly deposited on the Ni film to form a connection protruding electrode. When the semiconductor element shown in FIG. 1 is mounted on a bare chip, the above-mentioned bonding protruding electrodes are directly connected to a circuit board by flip-chip mounting or packaged on a TCP.

As described above, a semiconductor element usually has external electrodes for making an electrical connection with the outside.
When packaging in a resin package or the like, a metal wire is connected to this external electrode. As the external electrode, Al used for wiring of a semiconductor element is used. recent years,
In response to the demand for smaller and more sophisticated electronic devices, conventional resin packages have been replaced by TCP (Tape Carrier).
A high-density mounting technology such as PKG) or a flip chip method in which a bare chip is directly mounted on a circuit board is required. The external electrodes of the semiconductor element used in these mounting techniques require a bonding protruding electrode as shown in FIG.

Next, a method of manufacturing a semiconductor device according to an embodiment of the present invention will be described in the order of steps with reference to FIGS.

FIG. 3A shows a dry etching step of the Al electrode 1 formed on the semiconductor element. The step of FIG. 3A is performed in the dry etching apparatus 12 of FIG. The dry etching apparatus 12 includes a vacuum pump 17, a power supply 18, a high frequency generator 19, and a suction valve 20 for sucking a sputtering gas 29 of Ar or Freon.

Specifically, the semiconductor element 6 is placed on the electrode 27 of the dry etching apparatus 12, the inside of the dry etching apparatus 12 is evacuated by the vacuum pump 17, and the Ar or Freon sputter gas 29 is dried by the suction valve 20. Filling the inside of the etching apparatus 12, increasing the voltage of the power supply 18 and applying high frequency by the high frequency generator 19,
Etching is performed until the natural oxide film 2 on the Al electrode 1 completely disappears by using the sputter gas 29 of Freon or Freon to expose the Al surface 11 having no oxide film.

Next, in the state shown in FIG.
Is carried. In this step, the sheet is transported in the transport path 14 shown in FIG. The transfer path 14 is provided with 23 vacuum pumps and a dry etching apparatus 1 for drawing a vacuum in the transfer path 14.
The first load lock of 24 is provided at the connection between the transfer path 2 and the transport path 14, and the second load lock is provided at the connection of the electroless plating apparatus 13 and the transport path 14
The load lock and the transfer path 14 have 26 leak valves for converting the vacuum state to an inert atmosphere 9 of nitrogen or Ar gas.

More specifically, when the semiconductor element 6 is transferred from the dry etching apparatus 12, the inside of the transfer path 14 is maintained in a vacuum state by the vacuum pump 23, the first load lock is opened, and the semiconductor element 6 is transferred from the dry etching apparatus 12. Transport. When the semiconductor element 6 is transported into the transport path 14, the first load lock is closed, the leak valve 26 is opened, and the interior of the transport path 14 is filled with nitrogen or Ar gas. With no pressure difference, the second load lock is opened and the semiconductor element 6 is transported to the electroless plating apparatus 13. That is, in this step, the semiconductor element 6 is moved to the next step without passing through the oxidizing atmosphere in an environment controlled to an inert atmosphere 9 of 1 atm with nitrogen or Ar gas.

Further, as shown in FIG. 3C, a Ni film is formed by an electroless plating method. This step is performed in the electroless plating apparatus 13 shown in FIG. And electroless plating equipment 1
Reference numeral 3 denotes a management device 21 for controlling the gas pressure and temperature of nitrogen or Ar gas to make the inert atmosphere 9 constant, and a plating chamber 22.

More specifically, in an electroless Ni plating bath 10 at 90 ° C., which is installed in an environment where the inside of the electroless plating apparatus 13 is controlled to an inert atmosphere 9 of 1 atm with nitrogen gas, 2 to 5
The Ni film 8 having a thickness of 0.7 to 1.2 μm is formed on the Al surface 6 of the semiconductor element 6 without the oxide film by immersion for a minute. That is, in this step, immediately after the semiconductor element is immersed in the electroless Ni
There is a precipitation reaction of Ni due to a substitution reaction between the surface 11 and the Ni ions in the electroless Ni plating solution, and Ni is deposited on the deposited Ni surface by the action of the reducing agent in the electroless Ni plating solution.
Causes a self-deposition reaction to grow the Ni film 7. The above steps are performed in the apparatus shown in FIG.

Next, as shown in FIG. 2D, an Au film 8 is formed by electroless plating. In this step, A
Since the Ni film 7 is formed on the l electrode 1, the re-formation of the natural oxide film on the Al electrode 1 is completely prevented.
Processing in air is also possible. In order to prevent the Ni film 7 from being deteriorated in connectivity due to oxidation in the air, the electroless A
In the u plating bath 34, the Au film 8 is formed on the Ni film 7 in a thickness of 0.1 to 0.1.
Form 2 μm.

As described above, according to this embodiment, the natural oxide film on the Al electrode is removed by dry etching, and the metal film is formed by electroless plating in an environment controlled to an inert atmosphere. Can be prevented, so that a highly adhesive metal film can be formed on the surface of the Al electrode very easily.

(Embodiment 2) Hereinafter, Embodiment 2 of the present invention.
Will be described with reference to the drawings.

FIG. 4 is a sectional view showing a manufacturing process of the semiconductor device according to the present embodiment based on an apparatus.

First, as shown in FIG. 4A, dry etching of an Al electrode formed on a semiconductor element is performed.
This dry etching apparatus has 17 vacuum pumps, 18
, A high-frequency generator 19, and a suction valve 20 for sucking a sputtering gas 29 of Ar or Freon.

Specifically, the electrode 2 of the dry etching apparatus
7, the vacuum pump 17 evacuates the inside of the dry etching apparatus 12, and the suction valve 20
The natural oxide film 2 on the Al electrode 1 is completely eliminated by the Ar or freon sputtering gas 29 while the dry etching apparatus 12 is filled with Ar or freon gas, the voltage of the power supply 18 is increased, and a high frequency is applied by the high frequency generator 19. Etching is performed until the Al surface 11 having no oxide film is exposed. Note that a transfer container 30 for transferring the semiconductor element is provided in the dry etching apparatus.

Next, FIG. 4B shows a step of moving the semiconductor element 6 to the transfer container 30. After the dry etching is completed, the inside of the dry etching apparatus and the transfer container 30 are set to an inert atmosphere 9 of 1 atm with nitrogen or Ar gas, the semiconductor element 6 is moved to the transfer container 30, the first gate is closed, and the inside of the transfer container 30 is closed. Seal tightly.

Subsequently, as shown in FIG.
A plating step is performed. After transporting the transport container 30 from the dry etching apparatus to the electroless Ni plating bath 10 installed in the atmosphere, the transport container 3 is transported in the electroless Ni plating bath 10.
The first and second gates 31 and 32 are opened, and the transfer container 30 is filled with an electroless Ni plating solution. Since the transfer container 30 is released in the electroless Ni plating bath 10, the oxide-free Al surface 11 of the semiconductor element 6 is not oxidized by oxygen in the atmosphere, and the electroless Ni plating bath 1 at 90 ° C.
By immersion for 2 to 5 minutes in O.sub.2, 0.7 to 1.2 .mu.m N
An i film 7 is formed.

Then, as shown in FIG.
A plating step is performed. In this step, since the Ni film 7 is formed on the Al electrode 1, there is no re-formation of the natural oxide film on the Al electrode 1, so that the treatment in the air is possible. Therefore, in order to prevent the Ni film 7 from being deteriorated in connectivity due to oxidation in the atmosphere, the Ni film 7 is formed in the electroless Au plating bath 34.
An Au film 8 is formed on the film 7 in a thickness of 0.1 to 0.2 μm.

From the above, Al is obtained by dry etching.
After removing the natural oxide film on the electrode and transporting it to the electroless plating solution in a container controlled to an inert atmosphere, the metal film is formed by electroless plating, so that it can be used in an electroless plating bath installed in the atmosphere. In addition, a metal film having high adhesion can be formed on the surface of the Al electrode.

Further, according to the present embodiment, since the semiconductor device subjected to dry etching is transported by using the transport container, a conventional plating apparatus can be used. Unlike the first embodiment, there is no need to create a new apparatus in which the dry etching apparatus and the plating apparatus are integrated.

In the first and second embodiments, the Ni film 7 is formed on the Al electrode 1 in the electroless plating step.
Was formed, but the Ni film 7 may be a Cu film, a Pd film, or an Au film.

[0036]

According to the present invention, Al is formed by dry etching.
By removing the native oxide film on the electrode uniformly and treating the plating process after dry etching in an inert atmosphere,
This completely prevents the re-formation of the natural oxide film of the l-electrode, and eliminates the need for processing such as formation of the Zn particle film 3 for preventing the formation of the natural oxide film. As a result, it is possible to form an electrode by electroless plating having good adhesion and high connectivity.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a schematic view of an apparatus for manufacturing a semiconductor device according to an embodiment of the present invention.

FIG. 3 is a sectional view showing a manufacturing process of the semiconductor device according to the embodiment of the present invention;

FIG. 4 is a sectional view showing a manufacturing process of the semiconductor device according to the embodiment of the present invention;

FIG. 5 is a sectional view of a conventional semiconductor device.

FIG. 6 is a cross-sectional view of a manufacturing process of a semiconductor device by a conventional electroless plating method.

[Explanation of symbols]

 Reference Signs List 1 Al electrode 2 Natural oxide film 3 Zn particle film 4 Ni film 5 Au film 6 Semiconductor element 7 Ni film 8 Au film 9 Inert atmosphere 10 Electroless Ni plating bath 11 Al surface without oxide film 12 Dry etching device 13 Electroless Plating device 14 Transport path 17 Vacuum pump 18 Power supply 19 High frequency generator 20 Suction valve 21 Management device 22 Plating chamber 23 Vacuum pump 24 First load lock 25 Second load lock 26 Leak valve 27 Electrode 28 Protective film 29 Sputter gas 30 Transport container 31 first gate 32 second gate 33 silicon oxide film 34 electroless Au plating bath

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁷ Identification code FI H01L 21/92 604D 604Z 604E (56) References JP-A-5-82524 (JP, A) JP-A-5-6880 (JP, A) JP-A-4-146624 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/288 H01L 21/28 301 H01L 21/3065 H01L 21/3205 H01L 21/321 H01L 21/68

Claims (2)

(57) [Claims] 1. A dry etching step for removing a natural oxide film present on the surface of an Al electrode formed on a semiconductor element by dry etching using a dry etching apparatus, and forming a vacuum on a transfer path connected to the dry etching apparatus. And opening the first load lock of the transport path communicating with the dry etching apparatus, transporting the semiconductor element to the transport path, closing the first load lock, and then closing the transport path. Opening a second load lock of the transport path communicating with the electroless plating apparatus under an environment controlled to an inert atmosphere and a first transporting step to make the semiconductor element in the electroless plating apparatus. A second transfer step of transferring a metal film to the Al electrode surface of the semiconductor element by an electroless plating method under an inert atmosphere environment The method of manufacturing a semiconductor device having and. 2. A dry etching apparatus for removing a natural oxide film present on a surface of an Al electrode formed on a semiconductor device, and the Al electrode from which the natural oxide film has been removed in the semiconductor device under an inert atmosphere environment. An electroless plating apparatus for depositing a metal film on the surface by an electroless plating method, and a transport path for transporting the semiconductor element from the dry etching apparatus to the electroless plating apparatus under an inert atmosphere environment, A first load lock on the side of the dry etching apparatus, a second load lock on the side of the electroless plating apparatus, a vacuum pump for evacuating the inside of the transfer path, and setting the inside of the transfer path to an inert atmosphere. And a device for manufacturing a semiconductor device comprising a leak valve.