JPS6094765A - Window opening shape of external pickup metal electrode of semiconductor element - Google Patents

Abstract

PURPOSE:To prevent a pad electrode from corroding by providing a window opening shape with a smooth curved structure like arcuate at the inner wiring side and with a slender slit at the end in an acute angle at the reverse side. CONSTITUTION:Ultrafine particles of silicon bonded to a pad electrode in dicing step to drying step, wear chips of dicing saw and impurities in the atmosphere are secured to corners B, C, D farther from the corner A near the inner wirings by utilizing the surface tension of water. Even if a separation occurs between resin and the surface of a chip due to the use for a long period and a water film is produced in the boundary, acute corner and slender slit are formed at the corner, thereby securing the produced water film to the corners of B, C, D farther from the inner wirings. Thus, even if the pad electrode is corroded, it occurs at the farther portion from the inner wirings. Accordingly, the lifetime reaching the disconnection can be increased.

Description

[Detailed Description of the Invention] [Technical Field] The present invention aims to improve the reliability with respect to moisture resistance. , simple [r aperture is shape]
].

<Prior Art> The shape of a pad electrode portion 1 and aperture, which are currently most widely used, is shown in FIG.

In the figure, 1 is a pad electrode, 2 is an internal wiring, and 3 is a window opening.

However, this window opening has a shape of f (■ shown below J,
■There are weaknesses.

■ Semiconductor devices, to put it on a large scale, require repeated steps such as impurity diffusion, vapor deposition, and exposure etching to form chips on a wafer, followed by a chipping process to separate them into individual devices, and a die and wire bonding process. , the device is completed through a molding process. Currently, a dicing method (process) is mainly used in the chipping process.

The dicing process involves dicing while running water on the wafer.
This is the process of cutting grooves in the shape of the base with a saw. In this process, the entire surface of the wafer is covered with silicon chips and debris from the dicing saw due to dicing.

Next, the wafer is washed with water to remove these dusts, but some of them cannot be removed and remain on the wafer. In the next drying process, the silicon particles that could not be removed are stuck to the corners of the window opening by the following mechanism.

At the beginning of drying, a water film is formed over the entire surface of the wafer, and as the drying progresses, the water film becomes thinner, and just before complete drying, the water film becomes uneven and becomes small island-like spots. The locations where these islands form are sharp corners where the surface tension of water acts strongly. Then, when the water is completely dried,
Microscopic silicon particles are fixed to the corners.

The above mechanism also occurs at the opening of the pad electrode. In the drying process after the guising process, it is determined at which corner of the aperture shown in Figure 1 the silicon microparticles will adhere, as the shape that influences the surface tension of water is the same, so each corner is the same. Not determined. On the other hand, in the water on the wafer,
In addition to the silicon microparticles mentioned above, there are wear debris from the dicing saw and impurities mixed in from the atmosphere. This contaminant is encapsulated at the same time as the chip is encapsulated.

As a result, such semiconductor devices are left unused (stored) for long periods of time.
When used in a certain way, this mixture induces corrosion of the pad electrode. If this happens, the lifespan leading to wire breakage will be longer than the other corners (B, C).

It will be shorter than D).

■ If a resin-sealed element is used for a long period of time, the chip surface and the resin may initially be in close contact with each other, but then the resin may absorb moisture in the atmosphere or become heated due to the operation of the element. Due to stress, the adhesion between the chip and the resin deteriorates, and the chip eventually peels off and shatters. Water absorbed by the resin enters the separated interface, and when the flow increases, a water film forms at the interface. The peeling 1111 [interface occurs often at the edge of the chip, and if the interface is the pad electrode shown in Figure 1, the water film d corner A, B, C
, I can't decide which corner of D to attach A1 to by J14 angle appositive. If the place where this water film is attached is B other than Aj,
For C and D, even if corrosion occurs from there, it will take a long time for the internal wiring to corrode and become electrically disconnected01
However, if A corrodes, it will break in a short period of time, leaving one weak point.

<Purpose and Summary of the Invention> The present invention aims to improve the weaknesses described in (1) and (3) above. The opposite side (end side of the chip) is characterized by having an acute angle and a long and narrow slit at the tip.

<Example> Figures 2 (a), (b) and (C) show shapes of examples of the present invention.

” In the Nikiya diagram, 4 is the pad electrode, 5 is the internal wiring, 6
The windows are open.

The one shown in Fig. 2(a) has the corners A, B, and C shaped like arcs, and the corner D has a slit.
The one shown in FIG. 2(b) has the corners A and C shaped like an arc, and the corners B and D provided with slits.
In the case shown in FIG. 2(C), the corner of A has an arcuate shape, and the corners of B, C, and D are provided with slits.

<Effects> By shaping the aperture of the present invention as described above, it is possible to reduce the amount of silicon microscopic particles that penetrate into the pad electrode portion from the dicing process to the drying process, as described in the section ① Weaknesses of the conventional method ③. Using the surface tension of water, the wear debris of the dicing saw and impurities in the atmosphere are removed from the corners (A) near the internal wiring.
) more distant corner (n.

C, D). Therefore, even if these contaminants induce corrosion of the pad electrode, since there is a distance between the corroded part and the internal wiring 5, at least the time it takes for the corrosion to progress this distance, and the life before disconnection can be extended.

＠ As mentioned in the weak point of the conventional method (■), due to long-term use, peeling [1] occurs between the resin and the chip surface, and even if a water film forms at the interface, the corner part shown in Figure 2 By providing all the sharp corners and long and narrow slits, even if the water film that occurs is far away from the internal wiring, it will occur at a location further away from the internal wiring, so corrosion must progress to the extent of the internal wiring in order for the wire to break. As a result, the life until disconnection becomes longer than in the conventional method (compared to the case where corrosion occurs at A in FIG. 1).

In addition, in the present invention, the shape of the side opposite to the internal wiring is made into a shape with acute angles and an elongated slit, but a shape that satisfies only one of the conditions may also be used.
A similar effect will be obtained.

[Brief explanation of the drawing]

FIG. 1 and FIGS. 2(a), (b), and (c) all show the shapes of the pad electrodes and the apertures of the protective film. Explanation of symbols 4: Pad electrode, 5: Internal wiring, 6: Window opening, A,
B, C+n: Corner. Agent Patent Attorney Aihiko Fuku (and 2 others)

Claims (1)

[Claims] 1 The window opening at the corner of the metal electrode part leading to the internal active part is configured with a smooth curve such as a circular arc, and the opposite side has an acute corner with a long slit. The shape of the aperture in the external metal electrode part of the semiconductor element is characterized by: