JPS6347941A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE: To be able to stop the unnecessary etching of a solder-plated layer to the minimum limit when removing by etching an aluminum layer by thinly covering a second base electrode with the aluminum layer to form a plating electrode together with the second electrode. CONSTITUTION:After a semiconductor substrate 1 is covered with a surface protecting film 3 except a first base electrode 2 provided with a salient electrode, and a second base electrode 8 is formed on a first part 6 provided with the salient electrode and a second part 7 made mostly of the substrate 1 separated from a first part 6. Then, after a thin aluminum layer 10 is deposited on the whole substrate 1, the part 6 of the electrode 8 is exposed, the whole substrate 1 is covered with a photoresist layer 11, and a solder-plated layer 12 is electrolytically plated on the part 6 of the electrode 8 to form a salient electrode. Subsequently, with the layer 12 as a mask the layer 10 is removed, and the whole substrate 1 is then heated to melt the layer 12, thereby forming a spherical salient electrode 13.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor device in which a protruding electrode used for face-down bonding to a semiconductor element is formed.

(Example) Conventional technology Conventionally, there are two ways to take out the electrodes of semiconductor devices: a method using bonding wires and a method using face-down bonding using protruding electrodes.The latter allows the protruding electrodes to be soldered to the same electrodes at once. Therefore, it has the advantage that the assembly process can be reduced to a large extent.

A method for forming protruding electrodes used in the conventional face-down bonding method is disclosed in Japanese Patent Application Laid-Open No. 15253/1983 (H
OIL 21/92) etc. A conventional method for forming protruding electrodes will be described below with reference to FIGS. 2A to 2F.

First, as shown in FIG. 2A, a silicon semiconductor substrate (21
) A first base electrode (23) is formed by sputtering aluminum on the silicon oxide film (22) deposited on the silicon oxide film (22). This first base electrode (23) is connected to the semiconductor substrate (2
1) is connected to the semiconductor element formed within the chip and extends to the periphery of the chip. A surface protection film (24) made of a phosphor glass layer (280 layers) or the like is deposited on the first base electrode (23), and an opening (25) for forming a protruding electrode is formed.

Next, as shown in FIG. 2B, an aluminum layer (26) is deposited on the entire surface of the semiconductor substrate (21) by sputtering. Aluminum/W (26) is formed to have a thick film thickness of 2 to 3 μm to ensure sufficient current capacity as a plating electrode during subsequent plating of the protruding electrodes. Furthermore, this aluminum layer (2
6) The top of the first base electrode 1 (23) on which the protruding electrode is formed is exposed and covered with a photoresist layer (27), and the entire surface is coated with Cr.
- A second base electrode (28) made of a Cu layer is vaporized. Then photoresist! By removing (27), the first
Only the second base electrode (28) on the base electrode (23) remains;
The other second base electrode (28) is lifted off. The second base electrode (28) can plate the solder of the protruding electrode, and
It is preferable to use a metal that is compatible with aluminum, which is the base electrode layer 23).

Next, as shown in FIG. 2C, the second base electrode (28) is exposed and the other parts are covered with a photoresist layer (29) for solder plating.

Next, as shown in the second diagram, solder plating is applied on the second base electrode (28) to a thickness of several tens of μm.
0) is selectively formed. In this step, the aforementioned aluminum ff (26) is used as a plating electrode, and the second base electrode (28) is all used as one electrode for electrolytic plating. For this reason, the aluminum layer (26) needs to have a sufficient thickness because current for electrolytic plating flows therethrough.

Next, as shown in FIG. 2E, the photoresist layer (29) is removed, and the solder plating layer (30) is used as a mask to remove the aluminum! (26) is removed. Aluminum layer (2
6> was removed with sodium hydroxide NaOH solution, solder plated,
5 (30) Aluminum J outside the bottom edge? IN (26) is completely removed, and an electrically isolated solder plating layer <30) is formed on the second base electrode (28).

Furthermore, as shown in FIG. 2F, the entire semiconductor substrate (21) is heated to melt the solder plating N (30) and form spherical protruding electrodes (31). In this process, the solder plating layer (30) is melted after the flux has been applied to the entire surface, so that a clean protruding electrode layer 31) can be formed.

(c) Problems to be Solved by the Invention However, in the conventional semiconductor device manufacturing method described above, since the aluminum layer (26) is used as an electrode for electrolytic plating, it is deposited thickly.
As shown in FIG. 2E, when removing the second base electrode (2
8) There was a problem in that the underlying aluminum layer (26) was also side-etched and removed, resulting in an overhang of the second base electrode (28). Furthermore, if the first base electrode (23) is over-etched, there is a problem that the protruding electrode becomes electrically exposed to the internal wiring. Furthermore, N of force soda
Impurities such as a+ ions and flux are absorbed by the second base electrode (2
There was also the problem that the particles invaded through the over-etched parts of 8) and adversely affected the characteristics of the semiconductor element.

(d) Means for solving the problems In view of the above-mentioned various problems, the present invention has been developed by depositing a thin aluminum layer on the second base electrode, and working together with the second base electrode. The present invention provides a method for manufacturing a semiconductor device that solves various conventional problems by forming plating electrodes.

(*) Function According to the present invention, since the aluminum layer is formed thinly on the second base electrode, etching of the solder plating layer can be minimized when the aluminum layer is etched away. Further, since the aluminum layer and the second base electrode are used together as a plating electrode, a sufficient current capacity of the plating electrode can be ensured.

(F) Embodiment An embodiment of the present invention will be described in detail with reference to FIGS. 1A to 1F.

As shown in FIG. 1A, the first step of the present invention is to form a first base electrode (2) on which a protruding electrode is formed on a semiconductor substrate (1).
The main purpose is to cover the remaining parts with a surface protective film (3).

In this step, a first base electrode (2) is formed by sputtering aluminum on a silicon oxide film (4) deposited on a silicon substrate (1). This first base electrode (2) is connected to the semiconductor element formed in the semiconductor substrate (1) and extends to the periphery of the chip. This first
The upper part of the base electrode (2) is covered with a surface protective film (3) made of a phosphor glass layer (PSG layer) or the like, and an opening (5) for forming a protruding electrode is formed.

The second step of the present invention, as shown in FIG.
A second base electrode (8) is formed on a second portion (7) consisting of a large portion of the semiconductor substrate spaced apart from the semiconductor substrate.

In this step, a photoresist layer (9) used for lift-off is deposited on the surface protection film (3). Photoresist depression (9)
) is the part where the second base electrode (8>) is not provided, that is, the first part (6) on the first base electrode (2) where the protruding electrode is formed.
and the first portion (6) and a second portion <7) that is spaced apart and occupies most of the semiconductor substrate (1). The second base electrode (8) is formed by depositing Cr-cuJW over the entire surface of the semiconductor substrate (1) from above the photoresist Jffl (9). Thereafter, the photoresist layer (9) is removed to leave the second base electrode (8) on the first portion (6) on the first base electrode (2) and on the aforementioned second portion (7); Only the second base electrode (8) between the first part (6) and the second part (7) is lifted off.

The third step of the present invention, as shown in FIG. 1C, consists in depositing a thin aluminum J-shaped recess (10) on the entire surface of the semiconductor substrate (1).

This process is characterized in that aluminum 9 (10) is deposited by sputtering to form a thin film of 5000 Å or less.

In the fourth step of the present invention, as shown in the first diagram, the first portion (6) of the second base electrode (8) is exposed and the semiconductor substrate (
1) Covering the entire surface with a photoresist layer (11).

In this process, aluminum! (10) The first part (6) of the second base electrode (8) is exposed on top and covered with a photoresist layer (11), and the aluminum layer (10) is selected using this photoresist layer (11) as a mask. etching,
The first base electrode (2) is exposed.

Similarly, as shown in the first diagram, the fifth step of the present invention is to electrolytically plate a solder plating layer (12) on the first portion (6) of the second base electrode (8) to form a protruding electrode. It's about doing.

In this process, approximately 10 μm (7) of copper is plated on the first portion 6) of the second base electrode <8), and then several tens of μm is plated on top of that.
A solder plating layer (12) is selectively electrolytically plated to a thickness of m. In this electrolytic plating, a thin aluminum layer (10)
and the second portion 7) of the second base electrode (8) are jointly used as a plating electrode to ensure the current capacity necessary for electrolytic plating.

The sixth step of the present invention is solder plating J'!, as shown in FIG. 1E. Using (12) as a mask, the aluminum layer (1
0).

In this step, first, the photoresist ff1 (11) is removed, and then the exposed aluminum N (10) is removed using the solder plating 1 (12) as a mask. Aluminum M (10
) is removed with hydric soda NaOH solution or the like. Therefore, the second
In this step, the first portion (6) and the second portion (7) of the base electrode (8) are electrically separated.

In the seventh step of the present invention, as shown in FIG. 1F, the entire semiconductor substrate (1) is heated to melt the solder plating ffi (12) to form spherical protruding electrodes (13).

In this process, after the blank is attached to the entire surface, it is solder plated! (12) is melted, so the protruding electrode (13) is clean.
) can be formed.

(G) Effects of the Invention According to the present invention, since the aluminum layer (10) is deposited thinner than before, the aluminum FO(to) can be etched away in a short time, eliminating the need for solder plating (12). It has the advantage of minimizing etching.

Further, according to the present invention, since the aluminum layer (1o) and the second base electrode (8) jointly constitute one plating electrode for electrolytic plating, even though the aluminum layer (10) is thin, This method has the advantage that a sufficient plating current can be secured and a uniform solder plating layer (12) can be formed.

Furthermore, according to the present invention, substantially the entire surface of the semiconductor substrate (1) is covered with a second layer.
Since it is coated with a base electrode (<8), it has the advantage of good surface protection and improved reliability.

Further, according to the present invention, since the first base electrode (2) is completely covered with the second base electrode (8), the first base electrode (2) is completely covered with the second base electrode (8) when etching the aluminum layer (10). There is no risk of etching and the protruding electrode (1
3).

[Brief explanation of the drawing]

1A to 1F are cross-sectional views illustrating a method of manufacturing a semiconductor device according to the present invention, and FIGS. 2A to 2F are sectional views illustrating a conventional method of manufacturing a semiconductor device. (1) is a semiconductor substrate, (2) is a first base electrode, (3)
is a surface protective film, (8) is a second base electrode, (10) is an aluminum layer, (11) is a photoresist layer, (12)
is a solder plating layer, and (13) is a protruding electrode. Applicant Sanyo 1! Ki Co., Ltd. and 1 other agent Patent attorney Takuji Nishino 1 other person Figure 1 △ Figure 1 B Figure 1 C Figure 2 E Figure 2 A Figure 2 B Figure 2 C

Claims (1)

[Claims] (1) A step of covering the semiconductor substrate with a surface protective film except for the first base electrode on which the protruding electrode is formed, and a first portion on the first base electrode where the protruding electrode is formed and the first forming a second base electrode on a second portion of the semiconductor substrate that is spaced apart from the second base electrode; depositing a thin aluminum layer over the entire surface of the semiconductor substrate; exposing a first portion and covering the entire surface of the semiconductor substrate with a photoresist layer; electroplating a solder plating layer on a second base electrode of the first portion to form the protruding electrode; and removing the aluminum layer using the protruding electrode as a mask.