JPH11219966A - Manufacture of solder bump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a solder bump, which can realize a reproducible stable plasma operation prior to film formation of barrier metal to attain an improved manufacturing yield when the solder bump is formed to be connected to an electrode pad via the barrier metal film. SOLUTION: A product wafer has a photoresist film 38 having an opening 40 facing an Al-based electrode pad 32 and also has a semiconductor substrate 30 having the film 38 formed thereon. Just prior to a plasma operation of the product wafer before film formation of ball limiting metal(BLM), a dummy wafer having a thermal oxidation film formed on a semiconductor substrate is subjected to a plasma operation. This plasma operation causes a silicon oxide film removed by sputtering to be deposited on an inner wall of a plasma processing chamber to thereby improve its insulation. As a result the plasma operation prior to the BLM film formation can be carried out under stable plasma discharge, and edges of the film 38 at the opening 40 can be stably made into a desired overhang form with a good reproducibility.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a solder bump, and more particularly to a method of forming a barrier metal film interposed between a solder ball and an electrode pad by using a lift-off method. The present invention relates to a plasma processing method.

[0002]

2. Description of the Related Art In order to further reduce the size of electronic equipment, it is important to improve the component mounting density. For semiconductor ICs (integrated circuits),
As an alternative to conventional package mounting, high-density mounting technology that directly mounts a bare chip on a printed wiring board has been actively researched, for example, flip chip mounting as a typical example.
Is being developed.

[0003] In this flip chip mounting method, Au is used.
There are several methods such as a (gold) stud bump method and a solder ball bump method. In any case, between the Al (aluminum) -based electrode pad of the semiconductor IC and the bump, the adhesion between the two can be improved. A barrier metal film for preventing mutual diffusion or the like is used. In particular, in the case of the solder ball bump method, since the barrier metal film affects the finished shape of the bump, the BLM (Ball Lim
It is called an itting metal film. The structure of the BLM film used for the solder bump is Cr (chrome).
The three-layer structure of film / Cu (copper) film / Au film is most common. In this three-layer structure, the lower Cr film serves as an adhesion layer for securing good adhesion with the Al electrode pad.
The middle Cu film serves as a barrier layer to prevent the diffusion of solder from the solder bumps, and the upper Au film
Each of them mainly acts as an oxidation preventing film for preventing the oxidation of the Cu film.

A conventional method of manufacturing a solder bump using such a BLM film will be described below with reference to FIGS. First, for example, at the junction of a flip-chip IC (not shown) formed on the surface of the semiconductor substrate 80, for example, A
1 or Al-based electrode pad 82 made of Al-Cu alloy or the like
To form Subsequently, a passivation film (surface protection film) 84 made of, for example, a polyimide film, a silicon nitride film, or the like.
After covering the entire surface of the substrate, the passivation film 84
A BLM film 86 connected to the Al-based electrode pad 82 through a connection hole opened at the bottom is formed (see FIG. 10).

Next, after a sufficiently thick photoresist film 88 is applied to the entire surface of the substrate, the photoresist film 88 is patterned by using a photolithography technique.
Thus, an opening 90 having a diameter large enough to expose the BLM film 86 and the surrounding passivation film 84 is formed (see FIG. 11).

Next, a solder vapor deposition film 92 made of Pb (lead) and Sn (tin) is formed on the entire surface of the substrate by using, for example, a vapor deposition technique. At this time, the solder deposition film 92
Due to the large step at the end of the photoresist film 88 in the opening 90, the BLM film 86 in the opening 90 and the solder deposition film 92 on the passivation film 84 and the solder deposition film 92 on the photoresist film 88 are separated. (See FIG. 12).

Next, the wafer is immersed in a resist stripper using a lift-off technique, and then subjected to a heating swinging process to remove the photoresist film 88 and the solder deposition film 92 on the photoresist film 88. Thus, B
Only the solder deposition film 92 covering the LM film 86 and the passivation film 84 around the LM film 86 is left (see FIG. 13).

Next, after applying a flux to the solder deposited film 92 by a wet back method, the solder deposited film 92 is melted by a heat treatment to finally form a solder ball bump 94 connected to the BLM film 86. Form. The BLM is thus formed on the Al-based electrode pad 82 at the junction of the flip chip IC formed on the surface of the semiconductor substrate 80.
A semiconductor device in which the solder ball bumps 94 are formed via the film 86 is manufactured (see FIG. 14).

Next, as shown in FIG. 10, a process flow until the BLM film 86 connected to the Al-based electrode pad 82 at the junction of the flip chip IC formed on the surface of the semiconductor substrate 80 is formed. Will be described in detail with reference to FIGS. First, a bonding portion of a flip-chip IC (not shown) formed on the surface of the semiconductor substrate 80 is formed with Al by using, for example, a sputtering technique and an etching technique.
A system electrode pad 82 is formed. Subsequently, after covering the entire surface of the base with the passivation film 84, a connection hole 96 having a predetermined size is opened on the Al-based electrode pad 82 by using a photolithography technique (see FIG. 15).

Next, a photoresist film 98 is formed on the entire surface of the substrate.
Is applied, the photoresist film 98 is patterned using a photolithography technique. Thus,
An opening 100 having a diameter larger than that of the connection hole 96 is formed on the Al-based electrode pad 82 and the surrounding passivation film 84.
Is formed (see FIG. 16).

Next, the wafer in this state is set in a sputtering apparatus, and plasma processing before BLM film formation using RF (high frequency) plasma is performed. This plasma processing before BLM film formation is generally called reverse sputtering processing. Thus, the shape of the end portion of the photoresist film 98 in the opening 100 is deformed into an overhang shape (see FIG. 17).

Next, a Cr film, a Cu film, an Au film, and the like are continuously formed on the entire surface of the substrate by, for example, a sputtering method using the sputtering apparatus used for the plasma processing before the BLM film formation. Thus, a BLM film 86 composed of a metal multilayer film in which a Cr film, a Cu film, an Au film, and the like are sequentially stacked is formed. At this time, since the end portion of the photoresist film 98 in the opening 100 has been overhanged by the plasma processing before the BLM film formation, no BLM film is formed on the side wall surface of the overhanged photoresist film 98. . For this purpose, the BLM film 86 formed on the entire surface of the substrate is used.
Is divided into an Al-based electrode pad 82 in the opening 100 and a BLM film 86 on the passivation film 84 and a BLM film 86 on the photoresist film 98 (FIG. 1).
8).

Next, using a lift-off technique, the wafer is immersed in a resist stripper and subjected to a heating swinging process to remove the photoresist film 98 and the BLM film 86 on the photoresist film 98 while removing the Al film. Only the BLM film 86 on the system electrode pad 82 and the surrounding passivation film 84 is left. In this manner, as shown in FIG. 10, the Al-based electrode pad 82 at the junction of the flip-chip IC formed on the surface of the semiconductor substrate 80 is formed.
Is formed (see FIG. 19).

[0014]

However, as shown in FIGS. 15 to 19, when the BLM film 86 connected to the Al-based electrode pad 82 is formed by using the lift-off technique, it is commonly called reverse sputtering. In the current method of manufacturing a solder bump, which requires a process of deforming the end portion of the photoresist film 98 in the opening 100 into an overhang shape by the plasma treatment before forming the BLM, the photoresist film 98 is formed. As the number of processed product wafers is increased, organic substances composed of resist decomposed products sputtered from the photoresist film 98 are gradually accumulated in the plasma processing chamber of the sputtering apparatus for performing plasma processing before BLM film formation, The state in the plasma processing chamber where the plasma is formed slightly changes every processing.

That is, since the organic matter decomposed from the photoresist film 98 is not a perfect insulator but has a certain degree of conductivity, the conductive organic matter must accumulate every time the plasma processing is performed before the BLM film formation. As a result, the impedance inside the plasma processing chamber changes, and the discharge state of the plasma is greatly affected.

If the accumulation of the organic substances progresses to a certain extent, the amount of the organic substances exceeds the range that can be covered by the auto-tuning function of the sputtering apparatus, and matching cannot be achieved. Therefore, the plasma discharge itself for the plasma processing before the BLM film formation cannot be smoothly started or maintained.

Even if the plasma discharge itself can be started, the discharge state becomes unstable, so that the processed shape of the end portion of the photoresist film 98 by the plasma processing before the BLM film formation varies. The adverse effect of the occurrence of the problem occurs. Furthermore, using lift-off technology,
The photoresist film 98 together with the photoresist film 98
Even when the upper BLM film 86 is removed and only the BLM film 86 connected to the Al-based electrode pad 82 remains, for example, as shown in FIG. 20, the BLM fragment 86a and the resist fragment 98a covered therewith. The lift-off residue 102 formed on the passivation film 84 may remain.

The variation in the processing shape of the end portion of the photoresist film 98 due to the plasma treatment before the BLM film formation and the residue failure at the time of forming the BLM film 86 connected to the Al-based electrode pad 82 by the lift-off method are as follows. There has been a problem that the reproducibility of a mass production process for forming the solder ball bumps 94 on the Al-based electrode pads 82 via the BLM film 86 is degraded, which causes a reduction in the production yield of product devices.

Further, such a problem is caused by, for example, an ICP (Inductively Coupled Plasma) high-density plasma apparatus for generating high-density plasma by an induced electric field generated by a high-frequency induction magnetic field, or a high-density plasma generated by μ (micro) waves and a magnetic field. In particular, when a recent high-density plasma apparatus in which a plasma processing chamber is formed of an insulating material, such as a magnetic field μ-wave plasma apparatus, is used.

Further, apart from the instability of the plasma due to the temporal change of the state of the inside of the plasma processing chamber accompanying the repetition of the plasma processing before the BLM film formation as described above, the conventional sputtering apparatus holds and fixes the product wafer. The following problems have been caused by the clamp.

That is, in the step shown in FIG. 17, a wafer having a photoresist film 98 having an opening 100 facing an Al-based electrode pad 82 formed on a semiconductor substrate 80 is set in a plasma processing chamber of a sputtering apparatus. When performing the plasma processing before the BLM film formation by RF plasma, as shown in FIG. 21, a plurality of clamps 114 are usually used as a means for mechanically holding and fixing the wafer 112 mounted on the wafer stage 110. I have. For this reason, as shown in part A in the figure, at some points held by the plurality of clamps 114 and in the vicinity of the wafer 112 in the vicinity thereof, for example, the RF plasma 116 generated in the plasma processing chamber is used.
A phenomenon occurs in which a shadow of the clamp 114 that hinders the irradiation of Ar ⁺ (argon ions) from the clamp 114 occurs, and a local disturbance occurs in the ion sheath.

Further, a temperature variation around the wafer 112 in contact with the plurality of clamps 114 may cause a variation in the temperature distribution of the wafer. That is, although the temperature of the wafer 112 is also increased by the wafer stage 110 heated by the heater, the clamp 11
Since the heat escapes from the area 4, the temperature locally decreases around the wafer 112 held and fixed by the clamp 114. Thus, the temperature distribution in the wafer surface varies. Further, when wafer processing is performed continuously, the clamp 114 itself is also heated by radiant heat from the plasma, ion attack, heat transfer from the wafer 112, and the like, so that the clamp 114 is relatively heated by the heat storage action. However, when the interval between wafer processing is long and the standby time of the plasma processing apparatus is long, the clamp 114 is cooled, so that the temperature distribution of the wafer is small. The variation occurs both within the wafer surface and between wafer processings.

The plurality of clamps 11
Due to the local disturbance of the ion sheath and the variation of the temperature distribution in the peripheral portion of the wafer 112 held and fixed by 4, the thermal deterioration of the photoresist film 98 due to the plasma processing before the BLM film formation becomes insufficient, Since it becomes difficult to stably obtain an overhang-like processed shape at the end of the photoresist film 98, the solder ball bump 94 is formed on the Al-based electrode pad 82 via the BLM film 86.
This causes a problem of lowering the production yield of a mass production process for forming a semiconductor device.

Therefore, a BLM film 86 connected to the Al-based electrode pad 82 is formed using the lift-off technique,
In a bump mass production line for forming solder ball bumps 94 connected to the Al-based electrode pads 82 via the LM film 86, in order to improve the device manufacturing yield, the shape of the end of the photoresist film 98 in the opening 100 must be changed. There is an urgent need for a plasma process prior to BLM film formation during the overhanging deformation process to be a stable process with good reproducibility.

Accordingly, the present invention has been made in view of the above problems, and has been made in consideration of the above problem, and is intended to provide a stable and reproducible barrier metal film when forming a solder ball bump connected to an electrode pad via the barrier metal film. It is an object of the present invention to provide a method for manufacturing solder bumps that can realize a pre-plasma treatment and achieve an improvement in manufacturing yield.

[0026]

The above object is achieved by a method for manufacturing a solder bump according to the present invention described below. That is, the method for manufacturing a solder bump according to claim 1 is as follows.
A method for manufacturing a solder bump in which a barrier metal film interposed between a solder ball and an electrode pad is formed by a lift-off method, wherein plasma processing is performed before forming a barrier metal on a wafer on which a predetermined resist pattern is formed. Before the plasma processing, the plasma processing is performed using a dummy wafer in which an inorganic insulating film is formed on the surface in a processing chamber in which the plasma processing before forming the barrier metal is performed.

According to the method for manufacturing a solder bump according to the first aspect of the present invention, in a mass production line for performing a plasma process before forming a barrier metal on a product wafer on which a resist pattern is formed, a plasma before forming a barrier metal before is used. Even if the organic matter removed by sputtering from the resist film is accumulated in the processing chamber due to the repetition of the processing, and the state of the impedance or the like in the processing chamber changes with time, the plasma becomes unstable. By performing a plasma process (hereinafter, this process is appropriately referred to as "dummy plasma process") using a dummy wafer having an inorganic insulating film such as a silicon oxide film formed on the surface thereof at a certain interval, for example, An insulator such as a silicon oxide film sputtered from the inorganic insulating film of the dummy wafer is placed in the processing chamber. Adhering to the walls to improve insulation. For this reason, the impedance matching in the processing chamber can be easily achieved, and the subsequent plasma processing before forming the barrier metal on the product wafer can be performed under a stable plasma discharge throughout. As a result, in a bump mass production line for forming solder ball bumps connected to electrode pads via a barrier metal film, even when plasma processing before barrier metal deposition of a product wafer is continuously performed, mass production of the product wafer is performed. By appropriately interposing the dummy plasma process between the processes, the process is much more stabilized than before, and a high yield of non-defective products is realized.

According to a second aspect of the present invention, there is provided a method of manufacturing a solder bump, wherein a barrier metal film interposed between a solder ball and an electrode pad is formed by a lift-off method. Before performing the pre-barrier-metal-deposition plasma processing on the wafer on which the resist pattern is formed, performing the plasma processing in an atmosphere containing O ₂ (oxygen) in a processing chamber in which the barrier-metal-predeposition plasma processing is performed. It is characterized by.

According to the method for manufacturing a solder bump according to the second aspect of the present invention, in a mass production line for performing a plasma process before a barrier metal film is formed on a product wafer on which a resist pattern is formed, a plasma before the barrier metal film is formed is obtained. Due to the repetition of the process, the deposition of the organic material sputtered from the resist film in the processing chamber excessively proceeds, and even if the plasma process using the dummy wafer having the inorganic insulating film according to claim 1 is performed. Nevertheless, even in the case where the state of the impedance or the like in the processing chamber gradually changes with time and the plasma becomes unstable, a longer interval than in the case of the above-mentioned claim 1, such as every 10 lots of products, is provided. , by performing plasma treatment in an atmosphere containing O _2, organic matter accumulated in the processing chamber portion Baked to, e.g. C + 2O ^* (oxygen radical) → CO _2, CO (gas) such as organic matter combustion reactions occur, organic matter that was accumulated in the processing chamber by such oxygen plasma cleaning process is effectively removed. For this reason, the impedance matching in the processing chamber can be easily achieved, and the subsequent plasma processing before forming the barrier metal on the product wafer can be performed under a stable plasma discharge throughout. As a result, in a bump mass production line for forming solder ball bumps connected to an electrode pad via a barrier metal film, even if plasma processing before barrier metal deposition of a product wafer is continuously performed, mass production of the product wafer is performed. By appropriately interposing the oxygen plasma cleaning treatment between the treatments, the process is much more stabilized than before, and a high yield of good products is realized.

According to a third aspect of the present invention, there is provided a method of manufacturing a solder bump according to the first or second aspect, further comprising: By adopting a configuration in which a monitoring device that detects the insulation resistance of the surface is installed, the insulation resistance of the inner wall surface of the processing chamber is detected as necessary, and the deterioration state of the insulation of the inner wall of the processing chamber is accurately detected. It becomes possible to grasp. Therefore, the timing for performing the dummy plasma processing according to the first aspect and the oxygen plasma cleaning processing according to the second aspect is appropriately determined. As a result, the dummy plasma processing and the oxygen plasma cleaning processing necessary for stabilizing the process when the plasma processing before forming the barrier metal on the product wafer is continuously performed are efficiently operated at the optimal time.

According to a fourth aspect of the present invention, there is provided a method of manufacturing a solder bump according to any one of the first to third aspects, further comprising a step of holding and fixing the wafer on a wafer stage in a processing chamber. By adopting a configuration in which the electro-adsorption electrode is installed, it is not necessary to fix the wafer using a clamp when performing plasma processing before forming a barrier metal on a product wafer, so that ions in the peripheral portion of the wafer due to the clamp are eliminated. The occurrence of local disturbance of the sheath and variation in the wafer temperature distribution within the wafer surface and during wafer processing is prevented. As a result, in a bump mass production line for forming solder ball bumps connected to electrode pads via barrier metal films,
Since the ion sheath is formed uniformly over the entire surface of the wafer and the temperature distribution of the wafer is uniformly controlled both within the wafer surface and during the wafer processing, the edge of the resist film formed by the plasma processing before barrier metal film formation is formed. The processed shape becomes good and stable over the entire surface of the wafer, and a high yield of non-defective products is realized.

According to a fifth aspect of the present invention, there is provided a method of manufacturing a solder bump according to any one of the first to fourth aspects, wherein a maximum surface of the wafer when performing a plasma treatment before forming a barrier metal film. Ultimate temperature is 100 ° C
By setting the temperature to about 150 ° C., the heat energy required for processing the edge portion of the resist film is supplied, and the temperature is prevented from being high enough to exceed the heat resistant temperature of the resist film. As a result, in the bump mass production line that forms solder ball bumps connected to the electrode pads via the barrier metal film, the temperature of the wafer is appropriately controlled, and sufficient and sufficient thermal energy is required for processing the resist film edge. As a result, the processed shape of the resist film edge portion by the plasma processing before the barrier metal film formation is good and stable over the entire surface of the wafer, and a high yield of high-quality products is realized.

[0033]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
A preferred embodiment of the present invention will be described. (First Embodiment) A first embodiment of the present invention is a BLM.
In a bump mass production line that forms solder ball bumps that connect to electrode pads through a film, triodes (Tr
When performing plasma processing before BLM film formation using an iode) type RF plasma processing apparatus, for example, every time one lot of 25 product wafers per lot is processed using the same triode type RF plasma processing apparatus, The plasma processing is performed on a dummy wafer having a thermal oxide film formed on a semiconductor substrate.

FIG. 1 is a schematic cross-sectional view showing a triode type RF plasma processing apparatus used for forming a BLM film and performing plasma processing before the BLM film formation in the method of manufacturing a solder bump according to the present embodiment, and FIGS. It is a process sectional view for explaining the manufacturing method of the solder bump concerning this embodiment.

First, a triode-type RF plasma processing apparatus used for forming a BLM film and performing plasma processing before forming a BLM in the method for manufacturing a solder bump according to the present embodiment will be described with reference to FIG. As shown in FIG. 1, in this triode type RF plasma processing apparatus, an anode plate 12 and a wafer stage 14 serving also as a cathode plate are installed vertically in a plasma processing chamber 10, A grid electrode 16 is provided between the opposing anode plate 12 and wafer stage 14 also serving as a cathode plate.

The anode plate 12 is connected to a plasma generation power supply 20 via a coupling capacitor 18, and the other end of the plasma generation power supply 20 is grounded. Also,
The wafer stage 14 serving also as a cathode plate is connected to a substrate bias power supply 24 via a coupling capacitor 22, and the other end of the substrate bias power supply 24 is grounded. The grid electrode 16 is grounded. Thus, the wafer 26 to be processed is mounted on the wafer stage 14 serving also as the cathode plate, and the plasma 28 is generated in the space between the anode plate 12 and the grid electrode 16.

Although not shown, the wafer 26 to be processed mounted on the wafer stage 14 serving also as a cathode plate is provided.
Is mechanically held and fixed by a clamp. In addition, a wafer stage 1 also serving as a cathode plate
4 has a built-in heater for heating the mounted processing target wafer 26.

Next, a method for manufacturing a solder bump according to this embodiment will be described with reference to FIGS. First, in the same manner as in the conventional process, Al or Al is applied to the junction of, for example, a flip chip IC (not shown) formed on the surface of the semiconductor substrate 30 by using, for example, a sputtering technique and an etching technique.
Forming an Al-based electrode pad 32 made of a Cu alloy or the like; Subsequently, after covering the entire surface of the base with a passivation film 34 made of, for example, a polyimide film or a silicon nitride film, a connection hole 36 having a predetermined size is opened on the Al-based electrode pad 32 by using a photolithography technique (FIG. 2).

Next, a photoresist film 38 is formed on the entire surface of the substrate.
Is applied, the photoresist film 38 is patterned using a photolithography technique. Thus,
An opening 40 larger than the connection hole 36 is formed on the Al-based electrode pad 32 and the passivation film 34 around the electrode pad 32 (see FIG. 3).

In addition to the product wafer shown in FIG. 3, although not shown, for example, five wafers each having a thermal oxide film having a thickness of about 1 μm formed on a semiconductor substrate are prepared as dummy wafers. Then, for example, after performing plasma processing before BLM film formation of 25 product wafers per lot, immediately before performing plasma processing before BLM film formation of the next lot of product wafers, the plasma processing is performed on the five dummy wafers. That is, dummy plasma processing is performed. Specifically, a dummy wafer having a thermal oxide film formed on a semiconductor substrate is placed on a wafer stage 1 in a plasma processing chamber 10 of the triode type RF plasma processing apparatus shown in FIG.
4 and perform plasma processing under the same conditions as the following plasma processing before BLM film formation of a product wafer. Flow rate of atmospheric gas Ar: 25 sccm Pressure in plasma processing chamber: 0.7 Pa Wafer stage temperature: 90 ° C. Plasma source power: 700 W (2 MHz) Substrate bias voltage: 350 V (13.56 MHz) Processing time: 3 minutes This dummy plasma processing was performed. Repeat for 5 dummy wafers sequentially.

Next, immediately after the dummy plasma treatment, the BL of the product wafer shown in FIG.
Plasma processing before M film formation is performed. That is, the product wafer on which the photoresist film 38 having the opening 40 facing the Al-based electrode pad 32 is formed is placed on the cathode plate in the plasma processing chamber 10 of the triode type RF plasma processing apparatus shown in FIG. After being mounted as a wafer 26 to be processed on the dual-purpose wafer stage 14 and held and fixed by a clamp (not shown), plasma processing before BLM film formation under the above conditions is performed. At this time, the heater built in the wafer stage 14 also serving as the cathode plate causes
The maximum temperature reached on the surface of the product wafer is controlled to be approximately 120 ° C. The surface layer of the photoresist film 38 on the semiconductor substrate 30 is subjected to almost vertical Ar ⁺ ion irradiation from the plasma 28 through the ion sheath by the plasma treatment before the BLM film formation, and the photoresist film 38 in the opening 40 is formed. The end is worked and its shape is transformed into an overhang shape (see FIG. 4).

Next, the product wafer which has been subjected to the plasma treatment before the BLM film formation is transferred to the triode type R shown in FIG.
After being transferred from the plasma processing chamber 10 of the F plasma processing apparatus to a film forming chamber connected under a high vacuum through a gate valve, a thickness of 0.1 μm
m Cr film, 1.0 μm thick Cu film, 0.1 μm thickness
Is continuously formed. Thus, the Cr film / Cu
BLM composed of a metal multilayer film in which a film / Au film is sequentially laminated
A film 42 is formed. At this time, since the end of the photoresist film 38 in the opening 40 has been overhanged by the plasma processing before the BLM film formation, the BLM is formed on the side wall surface of the overhanged photoresist film 38.
No film is formed. Therefore, the BL formed on the entire surface of the substrate
The M film 42 is divided into the BLM film 42 on the Al-based electrode pad 32 in the opening 40 and the passivation film 34 and the BLM film 42 on the photoresist film 38 around the electrode pad 32 (see FIG. 5). .

Then, using the lift-off technique, (CH
₃ ) ₂ SO (Dimethyl sulfoxide) and CH ₃ NC ₄ H ₆
The product wafer is immersed in a resist stripping solution composed of O (N-methyl-2-pyrrolidone) and subjected to a heating swinging process. Thus, while removing the BLM film 42 on the photoresist film 38 together with the photoresist film 38, the Al film is removed through the connection hole 36 opened in the passivation film 34.
Only the BLM film 42 connected to the system electrode pad 32 remains (see FIG. 6).

Next, solder ball bumps 44 are formed on the BLM film 42 connected to the Al-based electrode pads 32 in the same manner as in the conventional process shown in FIGS. That is, after a photoresist film having a sufficient thickness is applied to the entire surface of the substrate, the photoresist film is patterned by using a photolithography technique, and an opening for exposing the BLM film 42 and the passivation film 34 around the BLM film 42 is formed. .

Subsequently, Pb: Sn =
A high-melting-point solder vapor-deposited film composed of Pb and Sn in a ratio of 97: 3 is formed on the entire surface of the substrate. At this time, the high-melting-point solder vapor-deposited film on the BLM film 42 in the opening and the passivation film 34 around it and the high-melting-point solder vapor-deposited film on the photoresist film due to a large step at the edge of the photoresist film in the opening. It is divided into a high-melting-point solder deposition film.

Subsequently, using a lift-off technique, the semiconductor substrate 30 is immersed in a resist stripping solution and subjected to a heating and oscillating process to remove the photoresist film and the high-melting-point solder deposited film on the photoresist film, and to perform BLM. Only the high-melting-point solder deposited film on the film 42 and the surrounding passivation film 34 is left.

Subsequently, a flux is applied to the high-melting-point solder vapor-deposited film using a wet back method, and then the high-melting-point solder-deposited film is melted by a heat treatment to form a BLM film 42.
Is finally formed. Thus, the BLM is placed on the Al-based electrode pad 32 at the junction of the flip chip IC formed on the surface of the semiconductor substrate 30.
A semiconductor device in which the solder ball bumps 44 are formed via the film 42 is manufactured (see FIG. 7).

Next, when the semiconductor device thus manufactured was compared with a semiconductor device manufactured by a conventional manufacturing method, the following results were obtained. That is, in the plasma processing chamber 10 of the triode type RF plasma processing apparatus for performing the plasma processing before the BLM film formation, the plasma processing before the BLM film formation is performed immediately after performing the plasma processing on the dummy wafer having the thermal oxide film formed on the semiconductor substrate. Compared with the semiconductor device manufactured by performing the plasma processing before the BLM film formation of several lots of product wafers without performing the plasma processing of the dummy wafer as in the related art, FIG. In the process shown in (1), residue defects generated when the BLM film 42 connected to the Al-based electrode pad 32 is formed by the lift-off method are significantly reduced. As a result, the device manufacturing yield was greatly improved.

As described above, according to the present embodiment, for example, after performing plasma processing before BLM film formation of 25 product wafers per lot continuously, plasma processing before BLM film formation of the next lot of product wafers is performed. Immediately before starting, this B
In the plasma processing chamber 10 of the triode type RF plasma processing apparatus for performing the plasma processing before the LM film formation, the plasma processing of the dummy wafer having the thermal oxide film formed on the semiconductor substrate is performed, so that the product wafer which has been repeated until then is processed. Even if organic substances sputter-removed from the photoresist film 38 by the plasma processing before the BLM film formation are accumulated and the state of the impedance or the like in the plasma processing chamber 10 is changed, the silicon oxide film sputter-removed from the dummy wafer remains in the plasma. Since it adheres to the inner wall of the processing chamber 10 to improve insulation, impedance matching in the plasma processing chamber 10 can be easily performed. Can be performed at

Therefore, even in the case where the plasma processing before the BLM film formation of the product wafer is repeatedly performed in the bump mass production line for forming the solder ball bumps 44 connected to the Al-based electrode pads 32 through the BLM film 42, The photoresist film 3 in the opening 40 is formed by the plasma treatment before forming the BLM under a stable plasma discharge.
The shape of the eight end portions is deformed stably into a desired overhang shape with good reproducibility and the BLM film 42 connected to the Al-based electrode pad 32 is always formed by the lift-off method under the optimum process condition. It is possible to significantly reduce residue defects that have conventionally occurred in the process and achieve a high yield of good products.

When performing plasma processing before BLM film formation of a product wafer, a wafer stage 1 serving also as a cathode plate is used.
By controlling the maximum attained temperature of the product wafer surface to be approximately 120 ° C. by the heater built in 4, sufficient and sufficient heat energy for processing the end portion of the photoresist film 38 is supplied. Therefore, the processed shape can be made good and stable over the entire surface of the wafer. Accordingly, also in this case, the BLM film 42 connected to the Al-based electrode pad 32 is formed by the lift-off method in a good process condition, so that the residue defect which has conventionally occurred in the lift-off process is further reduced. , A high yield can be realized.

(Second Embodiment) A second embodiment of the present invention relates to a method for manufacturing a solder ball bump connected to an electrode pad via a BLM film in a bump mass production line.
When performing BLM pre-film formation plasma processing using a P high-density plasma processing apparatus, for example, each time one lot of 25 product wafers per lot is processed, the same ICP high-density plasma processing apparatus is used. The plasma processing is performed on a dummy wafer having a thermal oxide film formed thereon.

FIG. 8 is a schematic sectional view showing an ICP high-density plasma processing apparatus used for forming a BLM film and performing plasma processing before the BLM film formation in the method of manufacturing a solder bump according to the present embodiment. FIG. 3 is an enlarged sectional view showing an electrostatic chucking electrode built in a wafer stage of the ICP high-density plasma processing apparatus of FIG.

The process sectional views for explaining the method for manufacturing the solder bumps according to the present embodiment are the same as those in FIGS. 2 to 7 in the first embodiment, and therefore are not shown. The reference numerals indicating the components of the semiconductor device are used as they are.

First, an ICP high-density plasma processing apparatus used for forming a BLM film and performing plasma processing before forming the BLM will be described with reference to FIGS. As shown in FIG. 8, in the ICP high-density plasma processing apparatus, an inductive coupling coil 52 is wound around a grounded plasma processing chamber 50. The inductive coupling coil 52 is connected to an IPC power supply 54. Also,
A wafer stage 56 that can move up and down is installed on the bottom surface of the plasma processing chamber 50. The wafer stage 56 is connected to a substrate bias power source 60 via a coupling capacitor 58. In this way, the processing target wafer 62 is mounted on the wafer stage 56, and the plasma processing chamber 5 above the processing target wafer 62 is mounted.
A high-density plasma 64 is generated in a space within the zero.

As shown in FIG. 9, an electrostatic chucking electrode 66 is built in the wafer stage 56, and a predetermined voltage is applied to the electrostatic chucking electrode 66 by a DC power supply 68. . Also, the wafer stage 56
A passage 70 through which the refrigerant flows is provided inside. Further, an opening 72 is provided at the center of the wafer stage 56, and Ar gas is blown out onto the wafer stage 56 through the opening 72 so as to flow between the wafer stage 56 and the wafer to be processed 62. It has become. Although not shown, the wafer stage 56 also has a built-in heater for heating the mounted processing target wafer 56. Thus, instead of using a clamp as in the first embodiment, the wafer stage 56
The wafer to be processed 62 mounted on the wafer stage 56 is held and fixed by an electrostatic suction electrode 66 built in the wafer stage 56.

Next, a method of manufacturing a solder bump according to this embodiment will be described. First, as shown in FIG. 2 of the first embodiment, an Al-based electrode pad 32 is formed at a junction of, for example, a flip-chip IC (not shown) formed on the surface of the semiconductor substrate 30. Subsequently, after covering the entire surface of the base with the passivation film 34, a connection hole 36 of a predetermined size is opened on the Al-based electrode pad 32.

Next, as shown in FIG. 3 of the first embodiment, after a photoresist film 38 is applied to the entire surface of the substrate, the photoresist film 38 is patterned,
An opening 40 larger than the connection hole 36 is formed on the Al-based electrode pad 32 and the passivation film 34 around the pad 32.

Further, apart from such a product wafer,
For example, five wafers each having a thermal oxide film having a thickness of about 1 μm formed on a semiconductor substrate are prepared as dummy wafers. For example, after performing plasma processing before BLM film formation of 25 product wafers per lot, immediately before performing plasma processing before BLM film formation of product wafers of the next lot, dummy plasma processing is performed on the five dummy wafers. Perform Specifically, a dummy wafer having a thermal oxide film formed on a semiconductor substrate is mounted on a wafer stage 56 in a plasma processing chamber 50 of the ICP high-density plasma processing apparatus shown in FIGS. Product Wafer BL
Plasma processing is performed under the same conditions as the plasma processing before the M film formation. Flow rate of atmospheric gas Ar: 30 sccm Wafer stage temperature: 90 ° C. ICP power supply: 1000 W (450 kHz) Substrate bias voltage: 100 V (13.56 MHz) Processing time: 60 seconds This dummy plasma processing is sequentially repeated for five dummy wafers.

Next, immediately after performing the plasma processing on the dummy wafer, the pre-BLM plasma processing on the product wafer of the next lot is performed. That is, the product wafer in which the photoresist film 38 in which the opening portion 40 facing the Al-based electrode pad 32 is patterned is formed is transferred to the wafer in the plasma processing chamber 50 of the ICP high-density plasma processing apparatus shown in FIGS. After being mounted on the stage 56 and held and fixed by the electrostatic chucking electrode 66 built in the wafer stage 56, plasma processing before BLM film formation under the above conditions is performed.

At this time, the maximum temperature reached on the surface of the product wafer is controlled to be approximately 120 ° C. by the heater built in the wafer stage 56. Then, as shown in FIG. 4 of the first embodiment, the surface layer of the photoresist film 38 on the semiconductor substrate 30 is almost vertically separated from the high-density plasma 64 via the ion sheath by the plasma treatment before the BLM film formation. Irradiation with Ar ⁺ ions causes the end of the photoresist film 38 in the opening 40 to be processed, and its shape is transformed into an overhang shape.

Next, as shown in FIG. 5 of the first embodiment, the product wafer that has been subjected to the plasma processing before the BLM film formation is gated from the plasma processing chamber 50 of the ICP high-density plasma processing apparatus shown in FIG. After being transferred to a connected film forming chamber under high vacuum through a valve, the Cr film / Cu film /
A BLM film 42 composed of a metal multilayer film in which Au films are sequentially stacked to a thickness of 0.1 μm / 1.0 μm / 0.1 μm is formed. At this time, since the end of the photoresist film 38 in the opening 40 is overhanged by the plasma processing before the BLM film formation, the BLM film is not formed on the side wall surface of the overhanged photoresist film 38. Therefore, the BLM film 42 formed on the entire surface of the base is divided into the BLM film 42 on the Al-based electrode pad 32 in the opening 40 and the BLM film 42 on the photoresist film 38.

Next, as shown in FIG. 6 of the first embodiment, the product wafer is immersed in a resist stripper by using a lift-off technique and subjected to a heating rocking process. B on membrane 38
While the LM film 42 is removed, only the BLM film 42 connected to the Al-based electrode pad 32 via the connection hole 42 opened in the passivation film 34 remains.

Next, as shown in FIG. 7 of the first embodiment, a high-melting-point solder deposition film for covering the BLM film 42 is formed by using a lift-off technique and a high-melting-point solder deposition technique. After applying flux to the high-melting-point solder vapor-deposited film using a wet back method, the high-melting-point solder-deposited film is melted by a heat treatment to form a BLM film 4.
2 is finally formed. Thus, the BLM is placed on the Al-based electrode pad 32 at the junction of the flip chip IC formed on the surface of the semiconductor substrate 30.
A semiconductor device in which the solder ball bumps 44 are formed via the film 42 is manufactured.

Next, when the semiconductor device thus manufactured was compared with a semiconductor device manufactured by a conventional manufacturing method, the following results were obtained. That is, in the plasma processing chamber 50 of the ICP high-density plasma processing apparatus that performs the plasma processing before the BLM film formation, the plasma processing before the BLM film formation is performed immediately after the plasma processing of the dummy wafer on which the thermal oxide film is formed on the semiconductor substrate. A semiconductor device manufactured by performing the BLM of several lots of product wafers without performing the plasma processing of the dummy wafer as in the related art.
Compared with a semiconductor device manufactured by continuously performing plasma processing before film formation, residue defects generated when the BLM film 42 connected to the Al-based electrode pad 32 is formed by the lift-off method are significantly reduced.

When the plasma processing before the BLM film formation was performed, the wafer temperature was measured between each wafer processing when processing one lot of product wafers.
It was confirmed that the number was reduced as compared with the case where the electrostatic chucking electrode was not built in as in the embodiment. And BL
Residual defects after the plasma treatment before the M film formation were further reduced as compared with the case of the first embodiment. As a result, not only the device manufacturing yield was significantly improved than in the conventional case, but also improved as compared with the case of the first embodiment.

As described above, according to the present embodiment, for example, after the plasma processing before the BLM film formation of 25 product wafers per lot is continuously performed, the plasma processing before the BLM film formation of the next lot product wafers is performed. Immediately before starting, this B
In the plasma processing chamber 50 of the ICP high-density plasma processing apparatus for performing the plasma processing before the LM film formation, the plasma processing of the dummy wafer having the thermal oxide film formed on the semiconductor substrate is performed, so that the product wafer which has been repeated until then is processed. Even if organic substances sputter-removed from the photoresist film 38 by the plasma processing before the BLM film formation are accumulated and the state of impedance or the like in the plasma processing chamber 50 is changed, the silicon oxide film sputter-removed from the dummy wafer remains in the plasma. Since it adheres to the inner wall of the processing chamber 50 to improve insulation, impedance matching in the plasma processing chamber 50 can be easily performed, and immediately after the plasma processing before the BLM film formation of the product wafer is performed under a stable plasma discharge. Can be performed at

Accordingly, even in the case where the plasma processing before the BLM film formation of the product wafer is repeatedly performed in the bump mass production line for forming the solder ball bumps 44 connected to the Al-based electrode pads 32 via the BLM film 42, The same effect as that of the first embodiment is achieved, and the residue defect which has conventionally occurred in the lift-off process of forming the BLM film 42 connected to the Al-based electrode pad 32 is greatly reduced, thereby realizing a high yield of good products. can do.

According to the present embodiment, the wafer stage 56 is used as a means for holding and fixing a product wafer mounted on the wafer stage 56 in the plasma processing chamber 50.
The use of the electrostatic chucking electrode 66 built in the wafer makes it possible to form the ion sheath uniformly over the entire surface of the product wafer, and to keep the temperature distribution of the product wafer within the wafer surface during wafer processing. Can be controlled uniformly. For this reason, in combination with the use of a high-density plasma generation source that enables plasma processing under a lower pressure atmosphere, a large amount of ion species Ar ⁺ generated in the high-density plasma 64 is diffused through the ion sheath without scattering. As a result, the edge of the photoresist film 38 by Ar ⁺ ion irradiation in the plasma processing before BLM film formation can be uniformly and quickly and efficiently realized over the entire product wafer.

Therefore, the BLM film 42 connected to the Al-based electrode pad 32 is formed by the lift-off method in the optimum process condition by the above-mentioned process, so that the residue defect which has conventionally occurred in the lift-off process is greatly reduced. In addition to the above-described embodiment, the clamp is further reduced as compared with the first embodiment in which a clamp is used as a means for holding and fixing a product wafer mounted on the wafer stage 14 in the plasma processing chamber 10. A higher yield of non-defective products than in the case can be realized.

Further, when the plasma processing before the BLM film formation of the product wafer is performed, the maximum temperature reached on the surface of the product wafer is controlled by the heater built in the wafer stage 56 to be approximately 120 ° C. ,
Since a sufficient amount of thermal energy necessary for processing the end portion of the photoresist film 38 is supplied without excess or shortage, the product wafer is held and fixed on the wafer stage 56 by using the electrostatic chucking electrode 66, so that the photoresist film It becomes possible to make the processing shape of the 38 end portions favorable and stable over the entire surface of the wafer. Therefore, this also contributes to realizing a high yield of products by greatly reducing residue defects generated in the lift-off step for forming the BLM film 42 connected to the Al-based electrode pad 32.

(Third Embodiment) A third embodiment of the present invention relates to a method of manufacturing a bump mass production line for forming a solder ball bump connected to an electrode pad via a BLM film.
When performing plasma processing before BLM film formation using the P high-density plasma processing apparatus, the same ICP high-density plasma processing is performed every time one lot of 25 product wafers is processed according to the second embodiment. After repeating the dummy plasma processing in the apparatus, the oxygen plasma cleaning in the plasma processing chamber is performed at an appropriate time by a monitor that detects the insulation resistance of the inner wall surface of the plasma processing chamber of the ICP high-density plasma processing apparatus. It performs processing.

In the method of manufacturing a solder bump according to the present embodiment, an ICP high-density plasma processing apparatus used for forming a BLM film and plasma processing before the BLM film formation and a wafer stage of the ICP high-density plasma processing apparatus are provided. 8 and 9 of the second embodiment described above, and the cross-sectional views for explaining the method of manufacturing a solder bump according to the present embodiment are the same as those of the first embodiment. Since the embodiment is the same as FIGS. 2 to 7, the illustration thereof is omitted, and the reference numerals indicating the respective components are used as they are.

First, an ICP high-density plasma processing apparatus used for forming a BLM film and performing plasma processing before forming the BLM will be described. The ICP high-density plasma processing apparatus according to the present embodiment has the same configuration as that shown in FIGS. 8 and 9 of the second embodiment. However, although not shown, a feature is that a monitor device provided with a probe for detecting a change with time in the electric resistance of the inner wall surface is provided on the inner wall of the plasma processing chamber 50 of the ICP high-density plasma processing apparatus. is there.

Next, a method of manufacturing a solder bump according to this embodiment will be described. First, as shown in FIG. 2 of the first embodiment, an Al-based electrode pad 32 is formed at a junction of, for example, a flip-chip IC (not shown) formed on the surface of the semiconductor substrate 30. Subsequently, after covering the entire surface of the base with the passivation film 34, a connection hole 36 of a predetermined size is opened on the Al-based electrode pad 32.

Next, as shown in FIG. 3 of the first embodiment, after a photoresist film 38 is applied to the entire surface of the substrate, the photoresist film 38 is patterned.
An opening 40 larger than the connection hole 36 is formed on the Al-based electrode pad 32 and the passivation film 34 around the pad 32.

Further, apart from such a product wafer,
For example, five wafers each having a thermal oxide film having a thickness of about 1 μm formed on a semiconductor substrate are prepared as dummy wafers. For example, after performing plasma processing before BLM film formation of 25 product wafers per lot, immediately before performing plasma processing before BLM film formation of product wafers of the next lot, dummy plasma processing is performed on the five dummy wafers. Perform That is, the dummy wafer having the thermal oxide film formed on the semiconductor substrate is mounted on the wafer stage 56 in the plasma processing chamber 50 of the ICP high-density plasma processing apparatus shown in FIGS. 8 and 9 of the second embodiment. Then, the plasma processing is performed under the same conditions as the plasma processing before the BLM film formation of the product wafer as described above. Then, the dummy plasma processing is sequentially repeated for the five dummy wafers.

Next, immediately after the dummy plasma processing, the pre-BLM plasma processing for the product wafer of the next lot is performed. That is, the Al-based electrode pad 32
Processing wafer 50 of an ICP high-density plasma processing apparatus in which a product wafer in which a photoresist film 38 in which an opening 40 facing the substrate is patterned is formed on a semiconductor substrate 30.
After being mounted on a wafer stage 56 and held and fixed by an electrostatic chucking electrode 66 built in the wafer stage 56, plasma processing before BLM film formation is performed.

As described above, every time the pre-BLM plasma processing of one lot of product wafers is performed, the same IC
In the plasma processing chamber 50 of the P high-density plasma processing apparatus, plasma processing is performed on a dummy wafer having a thermal oxide film formed on a semiconductor substrate, and this process is repeated for, for example, several tens of lots.

During this time, the plasma processing chamber 50 is constantly or periodically, or as appropriate, as needed, by a probe of a monitor installed on the inner wall of the plasma processing chamber 50.
By detecting a change with time in the electric resistance of the inner wall surface, the deterioration state of the insulating property of the inner wall surface of the plasma processing chamber 50 is accurately grasped. Then, a dry cleaning process using oxygen plasma is performed under the following conditions at a time when the insulating property of the inner wall surface of the plasma processing chamber 50 is deteriorated due to the repetition of the plasma processing before the BLM film formation of the product wafer. O ₂ flow rate: 100 sccm Plasma processing chamber pressure: 0.3 Pa Wafer stage temperature: 90 ° C. ICP power supply: 1000 W (450 kHz) Substrate bias voltage: 0 V (13.56 MHz) Processing time: 180 seconds

Next, after performing the dry cleaning process using the oxygen plasma, the plasma process before forming the BLM film on the product wafer of the next lot is performed. That is, A
A product wafer on which a photoresist film 38 in which an opening 40 facing the l-electrode pad 32 is patterned is formed is subjected to a plasma processing chamber 50 of an ICP high-density plasma processing apparatus.
After being mounted on a wafer stage 56 and held and fixed by an electrostatic chucking electrode 66 built in the wafer stage 56, plasma processing before BLM film formation is performed.

As shown in FIG. 4 of the first embodiment, the surface layer of the photoresist film 38 on the semiconductor substrate 30 is subjected to ICP
Nearly perpendicular Ar ⁺ ions are irradiated from the high-density plasma 64 via an ion sheath, the end of the photoresist film 38 in the opening 40 is processed, and its shape is deformed into an overhang shape.

Next, as shown in FIG. 5 of the first embodiment, the product wafer having been subjected to the plasma processing before the BLM film formation is gated from the plasma processing chamber 50 of the ICP high-density plasma processing apparatus shown in FIG. After being transferred to a connected film forming chamber under high vacuum through a valve, the Cr film / Cu film /
A BLM film 42 composed of a metal multilayer film in which Au films are sequentially laminated to a thickness of 0.1 μm / 1.0 μm / 0.1 μm is formed by combining the BLM film 42 on the Al-based electrode pad 32 in the opening 40 with the photoresist. It is formed separately from the BLM film 42 on the film 38.

Next, as shown in FIG. 6 of the first embodiment, the product wafer is immersed in a resist stripping solution by a lift-off technique and subjected to a heating and oscillating process, and the photoresist film 38 and the photoresist film are used. B on membrane 38
While the LM film 42 is removed, only the BLM film 42 connected to the Al-based electrode pad 32 via the connection hole 42 opened in the passivation film 34 remains.

Next, as shown in FIG. 7 of the first embodiment, a high-melting-point solder deposition film for covering the BLM film 42 is formed by using a lift-off technique and a high-melting-point solder deposition technique. After applying flux to the high-melting-point solder vapor-deposited film using a wet back method, the high-melting-point solder-deposited film is melted by a heat treatment to form a BLM film 4.
2 is finally formed. Thus, the BLM is placed on the Al-based electrode pad 32 at the junction of the flip chip IC formed on the surface of the semiconductor substrate 30.
A semiconductor device in which the solder ball bumps 44 are formed via the film 42 is manufactured.

Next, when the semiconductor device manufactured in this manner was compared with a semiconductor device manufactured by a conventional manufacturing method, the following results were obtained. That is, in a plasma processing chamber 50 of an ICP high-density plasma processing apparatus for performing plasma processing before BLM film formation, a semiconductor device manufactured by performing plasma processing before BLM film formation immediately after performing dry cleaning processing using oxygen plasma. Compared with a conventional semiconductor device manufactured by continuously performing plasma processing before forming a BLM film on several lots of product wafers without performing plasma processing on a dummy wafer as in the related art,
B connected to Al-based electrode pad 32 by lift-off method
Residual defects that occur when the LM film 42 is formed are significantly reduced. As a result, the device manufacturing yield was significantly improved as compared with the conventional case. Further, residue defects were further reduced as compared with a semiconductor device manufactured by performing plasma processing before BLM film formation immediately after performing dummy plasma processing immediately before performing dry cleaning processing using oxygen plasma. As a result, the device manufacturing yield also improved.

As described above, according to the present embodiment, even if the dummy plasma processing is performed every time the plasma processing before the BLM film formation is performed on 25 product wafers per lot, for example, the product wafers of 10 lots or more are processed. Is repeated, the insulating property of the inner wall surface of the plasma processing chamber 50 gradually deteriorates. However, the state of deterioration of the insulating property of the inner wall surface of the plasma processing chamber 50 is accurately grasped by a probe of a monitor device, and an appropriate state is determined. By performing a dry cleaning process using oxygen plasma at an appropriate time,
The organic matter accumulated on the inner wall of the plasma processing chamber 50 is burned and effectively removed, and the insulating property of the inner wall surface of the plasma processing chamber 50 is restored again, so that the impedance matching in the plasma processing chamber 50 can be easily achieved. For,
Immediately after that, the plasma processing before the BLM film formation of the product wafer can be performed under a stable plasma discharge.

Accordingly, in the bump mass production line for forming the solder ball bumps 44 connected to the Al-based electrode pads 32 via the BLM film 42, the dummy wafer processing according to the second embodiment is interposed between the bumps and the product wafer. Even if plasma processing before BLM film formation is repeatedly performed for a long time, residue defects in the lift-off step of forming the BLM film 42 connected to the Al-based electrode pad 32 are significantly reduced, thereby realizing a high yield of good products. Can be.

Although the present invention has been described based on the above-described first to third embodiments, the present invention is not limited to these first to third embodiments. A process apparatus for performing plasma processing before BLM film formation,
It goes without saying that the process conditions including the plasma treatment before the BLM film formation can be appropriately selected without departing from the gist of the present invention. For example, in the first to third embodiments, a process example in which a triode-type RF plasma processing apparatus and an ICP high-density plasma processing apparatus are used as the plasma processing apparatus before BLM film formation is described.
For example, an orthodox parallel plate type RF plasma processing apparatus may be used instead of the triode type RF plasma processing apparatus, or a magnetic field microwave plasma apparatus using, for example, ECR (ElectronCyclotron Resonance) instead of the ICP high-density plasma processing apparatus. It is also possible to apply the present invention to an ECR high-density plasma apparatus which generates high-density plasma by interaction of a helicon wave (Helicon) and electrons.

[0090]

As described above, according to the method of manufacturing a solder bump according to the present invention, the following effects can be obtained. In other words, according to the method for manufacturing a solder bump according to claim 1, in a mass production line for performing plasma processing before forming a barrier metal on a product wafer on which a resist pattern is formed, a dummy wafer having an inorganic insulating film formed on a surface thereof is used. By performing the plasma treatment at regular intervals, the silicon oxide film sputtered from the inorganic insulating film of the dummy wafer on the inner wall of the processing chamber where the organic substances are accumulated by the plasma treatment before the barrier metal deposition. The adhesion of the insulator improves the insulation, so that impedance matching in the processing chamber can be easily achieved, and the subsequent plasma processing before barrier metal deposition of the product wafer can be performed under stable plasma discharge. Become. Therefore, even in the case of repeatedly performing the plasma processing before forming the barrier metal on the product wafer, the process is much more stabilized than before, and a highly reproducible wafer processing with greatly reduced residue defects is realized. High non-defective product yield can be achieved.

According to the solder bump manufacturing method of the present invention, in a mass production line for performing a plasma process before forming a barrier metal on a product wafer on which a resist pattern is formed, a plasma in an atmosphere containing O ₂ is formed. By performing the treatment at a longer interval than in the case of the above-described claim 1, the organic matter accumulated in the inside of the treatment chamber by the plasma treatment before the barrier metal film formation is burned and removed effectively, Impedance matching can be easily achieved, and the subsequent plasma processing before forming a barrier metal on a product wafer can be performed under a stable plasma discharge throughout. Therefore, even in the case of repeatedly performing plasma processing before forming a barrier metal on a product wafer, the process is much more stabilized than before, and highly reproducible wafer processing with greatly reduced residue defects is realized. High non-defective product yield can be achieved.

According to a third aspect of the present invention, there is provided a method of manufacturing a solder bump according to the first or second aspect, further comprising the step of: By installing a monitoring device that detects resistance, it is possible to detect the insulation resistance of the inner wall surface of the processing chamber as needed, and to accurately grasp the state of deterioration of the insulation of the inner wall of the processing chamber. To become
The dummy plasma processing according to the first aspect and the second aspect.
The time for performing the oxygen plasma cleaning process is appropriately determined, and the operation can be efficiently performed at the optimal time.

According to a fourth aspect of the present invention, there is provided a method of manufacturing a solder bump according to any one of the first to third aspects, wherein the wafer is held and fixed on a wafer stage in a processing chamber. Since the electrostatic chucking electrode is installed, it is not necessary to fix the wafer using a clamp when performing plasma processing before forming a barrier metal on a product wafer. Local disturbance of the wafer and variations in the wafer temperature distribution within the wafer surface and during wafer processing can be prevented. Therefore, since the ion sheath can be formed uniformly over the entire surface of the wafer and the temperature distribution of the wafer can be controlled uniformly both within the wafer surface and during the wafer processing, the resist is formed by plasma processing before barrier metal film formation. The processed shape of the film edge can be made good and stable over the entire surface of the wafer, and a high yield of good products can be achieved.

According to the method of manufacturing a solder bump according to the fifth aspect, in the method of manufacturing a solder bump according to any one of the first to fourth aspects, the wafer surface when performing the plasma treatment before forming the barrier metal is formed. Temperature reached 1
When the temperature is from 00 ° C. to 150 ° C., it is possible to supply the thermal energy required for processing the edge portion of the resist film and to prevent the resist film from being heated to a temperature higher than the allowable temperature limit. Therefore, it is possible to appropriately control the temperature of the wafer and to supply a sufficient amount of thermal energy necessary for processing the edge of the resist film without excess or deficiency. The shape can be made good and stable over the entire surface of the wafer, and a high yield of good products can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a triode type RF plasma processing apparatus used for forming a BLM film and performing plasma processing before BLM formation in a method for manufacturing a solder bump according to a first embodiment of the present invention.

FIG. 2 is a process cross-sectional view (part 1) for explaining the method for manufacturing a solder bump according to the first embodiment of the present invention, in which a connection hole facing an Al-based electrode pad is formed on a passivation film on a semiconductor substrate. Indicates a state in which is opened.

FIG. 3 is a process cross-sectional view (part 2) for describing the method for manufacturing a solder bump according to the first embodiment of the present invention, in which a connection is made so that an Al-based electrode pad faces a photoresist film on a passivation film. This shows a state in which an opening having a diameter larger than the hole is formed.

FIG. 4 is a process sectional view (part 3) for explaining the method for manufacturing a solder bump according to the first embodiment of the present invention, which is a plasma processing of a dummy wafer having a thermal oxide film formed on a semiconductor substrate; This shows a state in which the edge of the photoresist film in the opening is deformed into an overhang shape by the plasma processing before the BLM film formation immediately after performing the above.

FIG. 5 is a process cross-sectional view (part 4) for describing the method for manufacturing a solder bump according to the first embodiment of the present invention, which illustrates an Al-based electrode pad in an opening and a passivation film in the vicinity thereof; B separated from the photoresist film
This shows a state where the LM film is formed.

FIG. 6 is a process cross-sectional view (part 5) for describing the method for manufacturing a solder bump according to the first embodiment of the present invention. BLM connected to system electrode pad
This shows a state where a film is formed.

FIG. 7 is a process cross-sectional view (part 6) for describing the method for manufacturing a solder bump according to the first embodiment of the present invention, which illustrates a method of forming a high-melting-point solder deposition film using a lift-off technique and a wet back method. This shows a state in which solder ball bumps are formed on the Al-based electrode pad via the BLM film by heating and melting.

FIG. 8 is a schematic cross-sectional view showing a high-density plasma processing apparatus having, as a plasma generation source, an ICP used for forming a BLM film and performing plasma processing before BLM formation in a method for manufacturing a solder bump according to a second embodiment of the present invention. FIG.

FIG. 9 is an enlarged sectional view showing an electrostatic chucking electrode built in a wafer stage of the high-density plasma processing apparatus of FIG.

FIG. 10 is a process cross-sectional view for explaining a conventional method of manufacturing a solder bump, in which a BLM film connected to an Al-based electrode pad through a connection hole opened in a passivation film on a semiconductor substrate is formed. It shows the status.

FIG. 11 is a process cross-sectional view for explaining a conventional method of manufacturing a solder bump, in which an opening for exposing an Al-based electrode pad and a surrounding passivation film is formed in a sufficiently thick photoresist film. It shows.

FIG. 12 is a process cross-sectional view for explaining a conventional method for manufacturing a solder bump, which is divided into a BLM film in an opening, a passivation film around the BLM film, and a photoresist film to form a solder deposition film; FIG.

FIG. 13 is a process cross-sectional view for explaining a conventional method of manufacturing a solder bump, and is a cross-sectional view illustrating a method of manufacturing a bump using a lift-off technique.
This shows a state in which a solder vapor-deposited film covering the bottom surface in the opening including the M film is formed.

FIG. 14 is a process cross-sectional view for explaining a conventional method of manufacturing a solder bump, in which B is deposited on an Al-based electrode pad by heating and melting a solder deposition film using a wet back method.
This shows a state where solder ball bumps are formed via the LM film.

FIG. 15 is a cross-sectional view of a conventional solder bump manufacturing method,
FIG. 9 is a process cross-sectional view for explaining a process flow for forming the M film, wherein A is formed on the passivation film on the semiconductor substrate;
This shows a state in which a connection hole facing the l-system electrode pad is opened.

FIG. 16 shows a conventional method of manufacturing a solder bump by using a BL.
FIG. 4 is a process cross-sectional view for explaining a process flow of forming an M film, showing a state in which an opening having a diameter larger than a connection hole facing an Al-based electrode pad is formed in a photoresist film on a passivation film. It is.

FIG. 17 is a cross-sectional view of a conventional method for manufacturing a solder bump;
FIG. 3 is a process cross-sectional view for explaining a process flow of forming an M film, showing a state in which an end portion of the photoresist film in an opening is deformed into an overhang shape by plasma processing before BLM film formation. .

FIG. 18 illustrates a conventional method for manufacturing a solder bump by using BL.
FIG. 4 is a process cross-sectional view for explaining a process flow for forming an M film, in a state where a BLM film is formed by being divided into an Al-based electrode pad in an opening and a passivation film and a photoresist film around the electrode pad; It shows.

FIG. 19 is a cross-sectional view of a conventional method for manufacturing a solder bump;
FIG. 4 is a process cross-sectional view for explaining a process flow of forming an M film, showing a state in which a BLM film connected to an Al-based electrode pad through a connection hole opened in a passivation film is formed by a lift-off technique. It is.

FIG. 20 is a cross-sectional view of a conventional method for manufacturing a solder bump;
FIG. 11 is a cross-sectional view showing a state in which a lift-off residue including a BLM fragment and a resist fragment covered by the BLM fragment is generated on the passivation film when the M film is formed.

FIG. 21 is a schematic cross-sectional view showing a state in which a wafer mounted on a wafer stage is mechanically held and fixed using a clamp in a plasma processing chamber of a conventional sputtering apparatus to perform plasma processing before BLM film formation. .

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Plasma processing chamber, 12 ... Anode plate, 14 ... Wafer stage also serving as a cathode plate, 16 ... Grating electrode, 18 ... Coupling capacitor, 20 ... Plasma generation power supply, 22 ... Coupling capacitor, 24 ... Substrate bias power supply, 26 ... Processed wafer, 28 Plasma, 30 Semiconductor substrate, 32 Al-based electrode pad, 34 Passivation film, 36 Connection hole, 38 Photoresist film, 40 Opening, 42 B
LM film, 44: solder ball bump, 50: plasma processing chamber, 52: inductive coupling coil, 54: IPC power supply, 56
... wafer stage, 58 ... coupling capacitor, 60 ... substrate bias power supply, 62 ... wafer to be processed, 64 ... high density plasma, 66 ... electrostatic attraction electrode, 68 ... DC power supply, 70
... A passage through which a refrigerant flows, 72 ... Aperture, 80 ... Semiconductor substrate, 82 ... Al electrode pad, 84 ... Passivation film, 86 ... BLM film, 86a ... BLM fragment, 88 ... Photoresist film, 90 ... Opening, 92: Solder deposited film, 9
4 solder ball bump, 96 connection hole, 98 photoresist film, 98a resist fragment, 100 opening
102: lift-off residue, 110: wafer stage,
112: wafer, 114: clamp, 116: RF plasma, 118: heater.

Claims (5)

[Claims] 1. A method for manufacturing a solder bump, wherein a barrier metal film interposed between a solder ball and an electrode pad is formed by a lift-off method, wherein the barrier metal film is formed on a wafer having a predetermined resist pattern formed thereon. Before performing the pre-plasma processing, in a processing chamber for performing the pre-barrier metal film formation pre-plasma processing, using a dummy wafer in which an inorganic insulating film is formed on the surface in advance, performing a plasma processing, Production method. 2. A method of manufacturing a solder bump, wherein a barrier metal film interposed between a solder ball and an electrode pad is formed using a lift-off method, comprising: forming a barrier metal film on a wafer on which a predetermined resist pattern is formed; A method of manufacturing a solder bump, comprising: performing a plasma process in an atmosphere containing oxygen in a processing chamber in which the plasma process before forming a barrier metal is performed before performing the pre-plasma process. 3. The method for manufacturing a solder bump according to claim 1, wherein a monitor device for detecting an insulation resistance of an inner wall surface of the processing chamber is provided in the processing chamber. Manufacturing method of bump. 4. The method for manufacturing a solder bump according to claim 1, wherein an electrostatic chuck electrode for holding and fixing the wafer is provided on a wafer stage in the processing chamber. Manufacturing method of solder bumps. 5. The method for manufacturing a solder bump according to claim 1, wherein a maximum temperature of the wafer surface when performing the plasma treatment before forming the barrier metal is 100 ° C. to 150 ° C.
A method for manufacturing a solder bump, comprising: