JP2002093835A - Connection member and method of forming the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a connection member which enables high-density and stable connections with reduced extention in the laterial direction when connecting electrical circuit components, and to provide a method of forming the connection member using simple processes. SOLUTION: The method of forming the connection member comprises a process of forming a first resist layer 15, having a first opening on en electroe 13 of a member 11 to be connected; a process of forming a second resist layer 16, having a second opening which is larger than the first, on the first resist layer 15; a process of forming an electrolytic plating section 17 in the first and second openings through electrolytic plating; a process of removing the first and second resist layers. Preferably, a cathode-polarizing additive is added to the plating liquid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connection member used for connecting electric circuit components and a method of forming the same, and more particularly to a connection member capable of high-density connection and a method of forming the same.

[0002]

2. Description of the Related Art With the recent increase in the degree of integration of electronic devices, higher-density connections are also required for connections between electric circuit components constituting these devices. Specific examples include a case where a semiconductor chip is connected on a wiring board, a case where a semiconductor chip is further connected on a semiconductor chip, and a case where a wiring board is connected to a wiring board serving as a parent board or an electric circuit of a peripheral device. Is raised. Forming a connection member on a semiconductor chip is the most typical example, but as another example, a connection member made of a solder ball or the like of about 500 μm is formed on a wiring board or a semiconductor chip in a grid pattern, for example. CSP (Chip Size Packa) connected to parent board etc.
ge) and BGA (Ball GridAlley).

For example, a semiconductor chip serving as a driver IC for driving high-definition pixels is connected to an electrode substrate of a liquid crystal display device in order to realize a high-quality display with a display element such as a liquid crystal display device. May be. Or T
AB (Tape Automated Bondin)
g) etc. in some cases. These connections are made, for example, via plated bumps formed on the semiconductor chip. In some cases, the TAB electrode is connected to an electrode substrate of a liquid crystal display device.
It may be performed via a plating bump formed on the AB electrode. These connections require high density connection technology. In order to enable such high-density connection, various other connection members and methods for forming the same have been proposed.

As a typical method for forming such a connection member, there are a method of forming the connection member by electrolytic plating and a method of forming the connection member by printing. The method of forming by printing has a limit in miniaturization due to bleeding or the like during printing. On the other hand, the method of forming the connection member by electrolytic plating can be formed in a short time,
In addition, since the ions dissolved in the aqueous solution are reduced as a metal, a connection member can be formed even in a narrow gap as long as the plating solution can enter, which is suitable for miniaturization. Although an electroless plating method is also known as a plating method, it is not preferable because it is inferior in forming speed.

[0005] As a method of forming a connection member by electrolytic plating, a mushroom type bump is known. This is to form mushroom-shaped bumps by plating. However, as a drawback of the mushroom type,
It was pointed out that the spread in the lateral direction was large. Therefore, with the demand for the high-density connection technology as described above, the shape has been changed to a so-called straight wall type using a thick film photoresist as a fine and tall shape. This is, for example, the technique shown in FIG.
A connection member is formed on a semiconductor chip. First, an electrode 103 made of aluminum, an aluminum alloy, or the like is formed on a semiconductor substrate 101 on which a semiconductor circuit is formed. Then, the semiconductor substrate 101 and the electrode 1
03, a protective film 102 made of SiO2 or the like
Is coated. Barrier metal 104 over the entire upper surface
Are formed (FIG. 4A).

Then, a resist material is spin-coated thereon,
A resist layer 106 having an opening 105 is formed by photolithography (FIG. 4B). Thereafter, electrolytic plating is performed using the barrier metal as a plating electrode to form an electrolytic plated portion 107 (FIG. 4C). Then, the resist layer 106 is peeled off (FIG. 4D). Next, etching is performed using the electrolytic plating portion 107 as a resist to remove unnecessary portions of the barrier metal 104 (FIG. 4E). In this case, since the protective film 102 is formed on the periphery of the electrode 103, the step difference between the protective film 102 and the electrode 103 is increased, and the step difference between the protective film and the electrode is increased when electrolytic plating is performed. Inherited, the peripheral portion of the connection member has a raised shape.

[0007]

As described above, in the case of the mushroom type and the straight wall type, the tip shape is a flat shape or a shape in which the peripheral edge is raised, and is used as it is as a connecting member. In addition, the connection member may be deformed and spread in the lateral direction due to pressure or heat at the time of connection. Therefore, when the connection members are arranged at a high density, there is a possibility that adjacent connection members may be short-circuited.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has as its object to provide a connecting member capable of reducing the lateral spread, achieving a high-density and stable connection. Another object of the present invention is to provide a method for forming such a connection member by a simple process.

[0009]

According to a first aspect of the present invention, there is provided a connecting member formed on an electrode of a member to be connected, wherein the connecting member has a lower end portion, and gradually increases from the lower end portion. A mid-abdomen having a diameter and a maximum diameter of 50 μm or less;
It is a connecting member provided with an electrolytic plating portion comprising an upper end portion having a diameter gradually decreasing from a middle portion and having a convex end.

The connecting member is formed on the electrode of the connected member, and connects the connected member to an external electric circuit component or the like. As described above, the connection member includes the electrolytic plating portion, and the electrolytic plating portion includes the lower end, the middle portion, and the upper end. Since these are continuously formed by electrolytic plating, there is no clear boundary. First, an electrolytic plating portion serving as a lower end portion is formed on an electrode of a connected member. A layer such as a barrier metal may be provided between the lower end and the electrode of the connected member.
The diameter gradually increases from the lower end, and gradually decreases through the portion having the largest diameter. The part having the largest diameter is referred to as a middle part, and the part gradually decreasing in diameter is referred to as an upper end. And the tip is convex.

Further, according to the present invention, a step of forming a first resist layer having a first opening on an electrode of a member to be connected, and a step of forming a first resist layer having a size larger than the first opening on the first resist layer. Forming a second resist layer having two openings,
A method for forming a connection member, comprising: a step of performing electrolytic plating to form an electrolytic plating portion in the first and second openings; and a step of removing the first resist layer and the second resist layer.

[0012] The invention according to claim 3 is based on claim 2.
In the method for forming a connection member described above, a method for forming a connection member in which the use of a barrier metal as a plating electrode is limited. That is, a step of forming a barrier metal on the electrode of the connected member, a step of forming a first resist layer having a first opening on the barrier metal, and a step of forming a first resist layer having a first opening on the first resist layer. Forming a second resist layer having a second opening, electrolytic plating using the barrier metal as an electrode, and forming an electrolytic plating portion in the first and second openings; A method for forming a connection member, comprising: a step of removing a layer and a second resist layer; and a step of removing an unnecessary portion of the barrier metal.

Further, the invention described in claim 4 is the same as the claim 2.
Alternatively, in the method of forming a connecting member according to claim 3, a plating solution containing an additive for cathodic polarization is used as the plating solution for the electrolytic plating.

[0014]

Embodiments of the present invention will be described below. In the present invention, examples of the member to be connected include a semiconductor chip or a wiring board such as a TAB or a printed wiring board.

(First Embodiment) A barrier metal is formed on an electrode of a connected member. The barrier metal is used as a plating electrode at the time of electrolytic plating,
Also called a seed layer. Examples of the material include copper and the like. As a specific example, there is a method in which chromium or titanium is deposited in a thickness of 1000 to 1500 angstroms, and copper is deposited in a thickness of 3000 to 5000 angstroms. Then, a plating resist is formed on the barrier metal. The resist used for the first resist layer and the second resist layer is not particularly limited as long as it does not cause peeling or the like during plating and has durability. For example, a liquid resist or a dry film can be used. The first resist layer defines the size of the plating electrode when performing electrolytic plating, and also defines the shape of the lower end of the electrolytic plating portion of the connection member. If the first opening is too small, it is not preferable because the contact area between the connection member and the connected member becomes small. Conversely, if it is too large, plating along the shape of the second resist is performed, The desired shape cannot be obtained.

The second resist layer regulates the shape of the middle part of the electrolytic plating part of the connection member and the convex shape of the upper end part in accordance with the plating conditions. Particularly, the maximum diameter of the outer shape (diameter of the middle portion) of the connection member, which is important for high-density connection, can be controlled by the second resist.

Regarding the relationship between the thickness of the first resist layer and the thickness of the second resist layer, even if the first resist layer is made thinner and the second resist layer is made thicker, the first resist layer is made thicker and the second resist layer is made thicker. Any combination may be used, even if the thickness is made thin, or the first resist layer and the second resist layer are made the same. As the solution used for the electrolytic plating, for example, a sulfuric acid-based solution can be used, and can be selected depending on a material required for the connection member. As the material of the connection member, nickel, copper, and gold are preferable, but other metals can also be used.

In order to control the shape, it is preferable to use an additive for performing cathodic polarization. Coumarins are preferred as additives. Other usable materials include polyethylene glycol,
Propagyl alcohol can be given. When such an additive is used, deposition of plating is stabilized, and a desired shape can be obtained. The mechanism is that the above-mentioned additive, which suppresses the deposition of plating, is preferentially adsorbed to the peripheral portion of the electrode of the member to be connected by cathodic polarization. for that reason,
It is considered that the central part is preferentially precipitated as compared with the peripheral part.

By performing the electrolytic plating, a plating metal obtained by the electrolytic plating is deposited from the plating electrode. Then, since the second opening is larger than the first opening, the plating metal is deposited so as to spread from the plating electrode, gradually becoming a large diameter, and gradually becoming a small diameter again toward the upper end portion. Shape. As the plating time increases, the plating metal swells as a whole. Then, when the desired shape is obtained, the electrolytic plating is stopped, and the first resist layer and the second resist layer are removed. Then, the barrier metal is etched using the plating metal as a resist to remove unnecessary portions of the barrier metal. Through such steps, the connection member is completed.

(Second Embodiment) A first resist layer having a first opening is formed on an electrode of a member to be connected.
The resist used for the first resist layer and the second resist layer is not particularly limited as long as it does not cause peeling or the like during plating and has durability. For example, a liquid resist or a dry film can be used. For example,
There is a method of performing exposure and development after applying and drying using a liquid photoresist. The size of the plating electrode when performing the electrolytic plating is defined by the first resist layer, and the shape of the lower end portion of the electrolytic plating portion of the connection member is also defined. If the first opening is too small, it is not preferable because the contact area between the connection member and the member to be connected becomes small. Conversely, if the first opening is too large, plating along the shape of the second resist is performed. Cannot be obtained.

Then, a second resist layer having a second opening larger than the first opening is formed on the first resist layer. The method for forming the second resist layer may be the same as the method for forming the first resist layer. Then, electrolytic plating is performed using the electrode exposed from the first opening as a plating electrode. As a current supply method for plating, there is a method in which a current supply electrode electrically connected to an electrode is formed on a connected member, and the current is supplied from the electrode.

By performing the electrolytic plating, a plating metal obtained by the electrolytic plating is deposited from the plating electrode. Then, since the second opening is larger than the first opening, the plating metal is deposited so as to spread from the plating electrode, gradually becoming a large diameter, and gradually becoming a small diameter again toward the upper end portion. Shape. As the plating time increases, the plating metal swells as a whole. Then, when the desired shape is obtained, the electrolytic plating is stopped, and the first resist layer and the second resist layer are removed. Thereby, the connection member is completed.

(Embodiment) Hereinafter, an embodiment will be described in more detail with reference to FIG. First, as shown in FIG. 1A, a connected member 11 made of a silicon substrate was prepared.
An insulating film 12 made of SiO2 is formed on the connected member so as to cover a part of the electrode 13 made of aluminum. Then, chromium was formed to a thickness of 0.5 μm and copper was formed to a thickness of 0.5 μm on the entire surface of the insulating film and the electrode as the barrier metal 14 by sputtering. Next, as shown in FIG. 1B, a liquid resist was spin-coated, exposed and developed to form a first resist layer 15 having a thickness of 1 μm and an opening diameter of 20 μm. Further, as shown in FIG. 1C, a liquid resist is spin-coated, exposed and developed, and has a thickness of 20 μm and an opening diameter of 10 μm.
A 0 μm second resist layer 16 was formed.

Then, it was immersed in a nickel plating solution, and electrolytic plating was performed at a current density of 1.0 A / dm2 for 30 minutes while stirring the plating solution to form an electrolytic plating portion 17 (FIG. 1 (d)). ). The plating solution was 300 g / l of nickel sulfate, 15 g / l of NaCl, 30 g / l of boric acid, and 0.2 g / l of coumarin. The one adjusted to 5 was used. In this case, another plating such as gold can be successively performed.
FIG. 2A is a perspective view of this state.

Thereafter, the resist was peeled off and the barrier metal was etched to complete the connection member (FIG. 1).
(E)). The connection member thus obtained has a lower end portion 18 whose shape is defined by the first resist and has a diameter of 20 μm.
m, the thickness is 1 μm, and the middle part 19 is formed thereon. The maximum diameter of the middle part is defined by the second resist.
μm. Further, the diameter gradually decreased toward the upper end portion 20. Similarly, the opening diameter of the first resist layer is set to 30
The connection member was formed by changing the thickness to 40 μm and 40 μm, respectively. FIGS. 2B and 2C show the state before the resist is stripped as in the case described above.

FIG. 3 shows an embodiment of three-dimensional mounting in which semiconductors are stacked. The connection member 31 made of nickel is formed on the aluminum electrode 33 of the first semiconductor chip 32. The thickest diameter of the middle part of the connecting member is 10 μm and the height is 20 μm. It is connected to the aluminum electrode 35 of the second semiconductor chip 34 at a high density via an anisotropic conductive paste. In connection, instead of the anisotropic conductive paste, between the aluminum electrode and the connecting member,
The connection may be made via solder, a conductive paste, or an anisotropic conductive film. Alternatively, a method in which heat or ultrasonic waves are applied to the aluminum electrode by using a connection member made of gold to perform pressure bonding can be employed. In this case, it is more preferable to use a material whose coefficient of linear expansion is controlled. Further, it is desirable that the surface of the aluminum electrode and the surface of the connection member be subjected to a surface treatment so as to be compatible with each joining method. For example, in order to improve the wettability of solder, there is a method of electroless nickel plating on the surface as a surface treatment of an aluminum electrode and flash gold plating on the surface. After forming the member, a method of further plating gold thinly is used. Examples of the conductive paste include a copper paste and a silver paste. Examples of the anisotropic conductive film and the anisotropic conductive paste include an epoxy-based adhesive or the like containing conductive particles such as metal particles.
Then, the second semiconductor chip 34 is connected to the lead frame 37 with a wire 36 made of gold or the like, and is sealed with a sealing resin 38 made of an epoxy resin or the like.

Table 1 shows the results of connecting the semiconductor chip to the inner leads of the TAB tape using the electrical connection member of the present invention. The semiconductor chip as the member to be connected has 200 electrodes, and two types of semiconductor chips were prepared for performing the evaluation described later. The semiconductor chip for the continuity test has all the electrodes electrically connected to each other. All the electrodes of the semiconductor chip for insulation test are insulated. TAB
Tape inner lead width / inner lead gap,
In addition, the maximum diameter of the middle part of the connecting member was changed and prepared as shown in Table 1, and the connection was made.

A connection member made of nickel was formed on the conduction test semiconductor chip in the same manner as in the embodiment. In addition, electrolytic gold plating was performed following electrolytic nickel plating, and gold was formed to a thickness of 0.03 μm on the surface. On the other hand, T
The tin-silver (3.5%)-copper (0.5%) solder paste was placed on the inner leads of the AB tape with the amount adjusted so that adjacent leads did not contact each other. After properly aligning the positions of the inner leads and bringing the connection members into contact with each other, the connection was performed by heating in an oven at 250 ° C. for 60 seconds.

[0029]

[Table 1]

The test results are as shown in Table 1. TAB
The conduction between the outer leads of the tape was examined for all 100 pairs, and the conduction failure was defined as "continuity test failure rate (%)". The results in Table 1 show that complete electrical connection was made between the inner lead and the connection member. Subsequently, 20 inner leads were selected, and a pull test was performed as a bonding strength test to confirm the bonding strength. The pull test was performed until failure occurred. The number of failures at the joint between the inner lead and the connection member was defined as the “number of joint strength test failures”. As a result, all of the 20 leads were broken by breaking the leads. That is, the results are shown in Table 1, and it was confirmed that the strength of the joint portion was sufficient.

Next, instead of the continuity test semiconductor chip,
Using a semiconductor chip for an insulation test, a connection member was formed in the same manner as described above, and connection was performed. The conduction between the outer leads of the TAB tape was examined for all 100 pairs, and the insulation failure was defined as “insulation test failure rate (%)”. The results in Table 1 show that no short circuit has occurred between adjacent connection members.

[0032]

According to the first aspect of the present invention, there is provided a connecting member formed on an electrode of a connected member, wherein a lower end portion,
Since it is a connecting member having an electrolytic plating portion consisting of a middle part having a gradually increasing diameter from the lower end and having a maximum diameter of 50 μm or less and an upper end having a gradually decreasing diameter from the middle part and a convex tip, Is controlled, and there is little risk of spreading in the lateral direction. Therefore, it is possible to obtain a connection member that enables high-density and stable connection without a risk of short-circuiting even when connection is performed by applying pressure or heat.

According to the second aspect of the present invention, a step of forming a first resist layer having a first opening on an electrode of a member to be connected; A step of forming a second resist layer having a large second opening, and in the first and second openings by performing electrolytic plating,
Since the method for forming a connection member includes a step of forming an electrolytic plating portion and a step of removing the first resist layer and the second resist layer, the shape is controlled, and the risk of spreading in the lateral direction is small, and thus the pressure is reduced. It is possible to form a connection member that enables high-density and stable connection without causing a short circuit or the like even when connection is performed by applying heat or heat.

According to the third aspect of the present invention, a step of forming a barrier metal on the electrode of the member to be connected, a step of forming a first resist layer having a first opening on the barrier metal, Forming a second resist layer having a second opening larger than the first opening on one resist layer, and performing electroplating using the barrier metal as an electrode; and performing electroplating in the first and second openings. Forming a connection member, a step of removing the first resist layer and the second resist layer, and a step of removing an unnecessary portion of the barrier metal, the plating current is stable. ,
In addition, the shape is controlled, the risk of spreading in the horizontal direction is small,
Therefore, it is possible to form a connection member that does not cause a short circuit or the like even when connected by applying pressure or heat and that enables stable connection with high density.

Further, according to the present invention, since a plating solution containing an additive for cathodic polarization is used as a plating solution for electrolytic plating, it is possible to control the shape as desired. It is possible to form a connection member which has a small possibility of spreading in the lateral direction and therefore has no danger of short circuiting even if connection is performed by applying pressure or heat, and which enables high-density and stable connection.

[0036]

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view showing one embodiment of a method for forming a connection member of the present invention.

FIG. 2 is a perspective view of a connecting member of the present invention.

FIG. 3 is an explanatory view showing connection using the connection member of the present invention.

FIG. 4 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

 11 ... Connected member 12 ... Insulating film 13 ... Electrode 14 ... Barrier metal 15 ... First resist layer 16 ... Second resist layer 17 ... Electroplating part 18 ... Lower end part 19 ... Middle part 20 top end 31 connection member 32 first semiconductor chip 33 aluminum electrode 34 second semiconductor chip 35 electrode 36 wire 37 lead frame 38 sealing resin 101 semiconductor substrate 102 protective film 103 electrode 104 barrier metal 105 opening 106 resist layer 107 electrolytic plating part

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05K 3/34 505 H01L 21/92 604S 602G 603Z 604B F-term (Reference) 5E051 CA04 5E319 AA03 AB05 AC01 AC16 AC17 BB04 CC12 CC22 CC61 CD26 GG01 5E343 AA02 AA11 BB09 BB16 BB23 BB24 BB44 BB71 CC61 CC78 DD43 DD44 ER11 GG08

Claims (4)

[Claims] 1. A connecting member formed on an electrode of a member to be connected, comprising: a lower end, a middle part having a diameter gradually increasing from the lower part and having a maximum diameter of 50 μm or less; A connection member including an electrolytic plating portion having a diameter and an upper end portion having a convex end. 2. A step of forming a first resist layer having a first opening on an electrode of a member to be connected, and a second resist having a second opening larger than the first opening on the first resist layer. A connection member comprising: a step of forming a layer; a step of performing electrolytic plating to form an electrolytic plating portion in the first and second openings; and a step of removing the first resist layer and the second resist layer. Formation method. 3. A step of forming a barrier metal on an electrode of a member to be connected, a step of forming a first resist layer having a first opening on the barrier metal, and a step of forming a first resist layer on the first resist layer. A step of forming a second resist layer having a second opening larger than the opening, and a step of forming an electrolytic plating portion in the first and second openings by performing electrolytic plating using the barrier metal as an electrode, A method for forming a connection member, comprising: removing a first resist layer and a second resist layer; and removing an unnecessary portion of the barrier metal. 4. The method for forming a connecting member according to claim 2, wherein a plating solution containing an additive for performing cathodic polarization is used as the plating solution for the electrolytic plating.