JPH04155866A - Semiconductor device - Google Patents

Abstract

PURPOSE:To enable flip chips to be bonded together in a self-aligned manner by a method wherein the electrodes of an OEIC and a photodiode are formed protrudent or recessed through a gold plating method, and these diodes are made to engage with each other to constitute a semiconductor device. CONSTITUTION:The electrodes 2 of an OEIC 5 are formed recessed (or protrudent), the electrodes 1 of a photodiode 4 are formed protrudent (or recessed), Sn solder 3 is evaporated on either the electrodes 2 or the electrode 1, and the OEIC 5 and the photodiode 4 are bonded together through a normal flip chip bonding method as usual by a double-sided aligner. At this point, the OEIC 5 and the photodiode 6 can be easily and accurately aligned with each other by engaging the protrudent and the recessed gold plated electrodes with each other, and when these chips are bonded together by thermocompression, the Sn solder 3 forms an AuSn eutectic alloy together with a gold plating layer formed on both the electrodes 1 and 2 to enable the OEIC 5 and the photodiode 6 to be firmly bonded together. At this point, an excellent electrical contact point small in contact resistance can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for assembling a hybrid semiconductor device. In particular, Si, GaAs.

This article relates to positioning and electrical connection methods when flip-chip bonding a single photodiode or semiconductor laser onto an InP or other IC or 0EIC.

[Conventional technology]

In order to perform flip-chip bonding between an IC, a photodiode, or a semiconductor laser chip, these must be turned upside down and thermocompressed using a solder material such as Sn. Because the chip is upside down, you cannot see the electrical contacts making contact.

The conventional flip chip bonding method is as shown in Figure 2.
Sn is applied on the electrode gold plating 2 formed on the EIC5.
The solder 3 is placed on top of the solder 3, and the electrode gold plating 1 formed on the photodiode 4 is placed on top of the solder 3, and the solder 3 is heated and pressed. At this time, to align the electrodes of the 0EIC and the photodiode, use the alignment marks 7 as shown in Figure 3 to determine the approximate position, and then use a double-sided aligner using a half mirror to accurately align the electrodes. Perform positioning. However, this method requires visual inspection by the operator, making it difficult to achieve highly accurate positioning. Therefore, it is necessary to use a method that allows the EIC electrode and the photodiode electrode to be positioned in a self-aligned manner.

FIG. 4 and FIG. S are examples of a conventionally well-known self-alignment method using Pb5n solder. If this solder is used, even if the position is shifted as shown in Fig. 4, when heated, the surface tension of the solder will correct it to the correct position as shown in Fig. 5.

Note that related semiconductor devices of this type include, for example, Applied Wisdom Letters (Appl, Ph.
Lett, Vol. 40, No. 7, April 1, 1982
day, P568-570, etc.

[Problem to be solved by the invention]

In the conventional self-alignment method, the effect of surface tension cannot be obtained unless the volume of Pb5n solder is sufficiently large.

On the other hand, this method cannot be used in photodiodes for ultrahigh-speed optical communication because the diameter of the electrode is as small as 30 μm or less.

An object of the present invention is to provide a method for flip-chip bonding small-sized devices such as photodiodes and lasers for ultra-high-speed optical communication to 0EICs and the like in a self-alignment manner.

[Means to solve the problem]

In order to achieve the above object, the present invention uses gold-plated electrodes to form the EIC electrode in a convex (or concave) shape, and the photodiode electrode in a concave (or convex shape), and has a structure in which these are fitted. (See Figure 1).

[Effect]

As shown in Figure 1, the 0EIC electrode is formed in a concave (or convex) shape, the photodiode electrode is formed in a convex (or concave) shape, Sn solder is vapor-deposited on one side, and the same process as normal flip chip bonding is carried out. Flip chip bonding is performed using double-sided aligners. At this time, the convex and concave gold-plated electrodes fit together to easily achieve highly accurate positioning, and when they are heated and pressed together, the Sn solder forms an AuSn alloy with the gold-plated layers of both, and the two are firmly bonded.

Further, good electrical contacts with low contact resistance can also be obtained.

〔Example〕

The steps of the embodiment shown in FIG. 1 will be explained below.

FIGS. 6 to 8 show the steps for producing concave gold plating. As shown in Fig. 6, a base electrode 6 (A u
Ge/Ni/Au, etc.) were evaporated for about 2,000 degrees at 6°.Next, a gold coating pattern was made with positive resist 11. Next, Tl/
An Au film 10 of about 200 degrees is deposited over the entire surface. A negative resist 9 is formed on this, and the manner in which this negative resist is formed determines whether a concave shape will be formed. That is, as shown in FIG.
When the negative resist 9 is formed so that the u film 1o is exposed,
Since gold plating is performed from both the bottom and side surfaces of T i / A u, a concave shape is obtained. On the other hand, if a negative resist is formed to cover the Ti/Au film on the sidewall as shown in FIG. 9, gold plating is performed only from the bottom surface, resulting in a convex shape.

Thereafter, the resist is removed by boiling in a resist stripping solution such as S-502A, and gold-plated electrodes as shown in FIGS. 8 and 11 are obtained.

FIG. 12 shows a second embodiment. This is an example in which a convex electrode is formed on the dome-shaped PIN photodiode 14, and a concave electrode is formed on the OE C5 side.

〔Effect of the invention〕

By the method of the present invention, flip-chip bonding can be performed with highly accurate positioning in a self-aligned manner even for small electrodes such as ultra-high-speed optical photodiodes with a diameter of 30 μm or less.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention, FIG. 2 is a diagram showing an example of a conventional flip chip bonding method, and FIG.
Figures 5 to 5 are diagrams showing an example of the flip chip bonding method using the self-alignment method, Figures 6 to 8 are diagrams showing the process of producing a concave electrode, and Figures 9 to 11 are convex. FIG. 12 is a process diagram for producing a shaped electrode, and is a diagram showing a second example. 1...Gold plating for photodiode electrodes, 2...0
EIC electrode gold plating, 3...Sn solder, 4...
・Photodiode, 5-OEIC56... base electrode,
7... Positioning mark, 8... Pb5n solder,
9...Negative resist, 10...T i / A u
Gold plating base layer, 11...Positive resist, 12...Gold plating electrode (concave type), 13.Gold plating electrode (convex type), 1
4...Dome-shaped foil Δ Figure 3, Figure 11~,. Great,
Elephant No. 12

Claims (1)

[Claims] 1. IC fabricated on a substrate such as Si, GaAs, InP, etc.
When manufacturing hybrid ICs by flip-chip bonding semiconductor lasers, photodiodes, etc. onto LSI, OEIC wafers or chips, high performance can be achieved by forming concave and convex electrical contacts and positioning marks using gold plating. A semiconductor device characterized by manufacturing electrical contacts that can be connected accurately and in a self-aligned manner.