JPH0652743B2 - Method for manufacturing semiconductor device - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for manufacturing a semiconductor device, and in particular, it is possible to freely select the potential of a back surface electrode of a semiconductor element that comes into contact with a heat sink. As a result, the present invention relates to an improvement in a method for manufacturing a semiconductor device in which a signal for operating a semiconductor element can be input from either the front surface electrode or the rear surface electrode of the element.

(2) Background of the technology When mounting an element on a heat sink for the purpose of preventing heat generation of a semiconductor element, particularly a light emitting diode or a diode having a back surface electrode, one of the electrodes of the element, that is, the back surface electrode is one surface of the heat sink. It is common to make direct contact with. However, it is desirable that the potential of the back electrode can be freely selected, except when the back electrode is simply a ground terminal. This is because the degree of freedom of the signal input method is increased. That is, for example, in a light emitting diode or the like, it is possible to operate with either the positive electrode or the negative electrode.

(3) Conventional Technology and Problems Conventionally, as heat sink materials, metal materials such as iron (Fe) and copper (Cu) having large thermal conductivity have been mainly used. However, in recent years, in order to meet the demand for miniaturization of heat sinks accompanying the miniaturization of elements, in place of the above-mentioned metal materials, a material having a large thermal conductivity such as diamond and capable of fine processing, or silicon ( Semiconductor materials such as Si) that can be easily micromachined are used.

When a heat sink is manufactured by using an insulator such as diamond or a semiconductor material described above, it is common to metallize the heat sink surface for various purposes such as adhesion of elements mounted on the heat sink. .

However, in this metallizing step and further in the element bonding step, the side surface of the heat sink is metallized, or the bonding flux for bonding the element is attached to the side surface of the heat sink.
There is a drawback in that the potential of the back surface electrode of the device cannot be separated from the potential of the side surface or the back surface of the heat sink.

(4) Object of the invention The object of the present invention is to eliminate this drawback, and in the state where the side surface of the heat sink is insulated, the electrode of the element that contacts the heat sink, that is, the potential of the back electrode is freely selected. Accordingly, it is an object of the present invention to provide a method for manufacturing a semiconductor device in which a signal for operating a semiconductor element can be input from either the front surface electrode or the back surface electrode of the element.

(5) Structure of the invention An object of the present invention is to form a conductive layer on the front and back surfaces and side surfaces of a wafer having high resistance, and selectively bond to a region corresponding to a fixed region of a semiconductor element on the surface of the conductive layer. An electrode of a semiconductor element is formed by depositing a fusion material, dividing the wafer including the adhered portions of the bonding fusion material, and excluding the peripheral portion of the wafer to form a heat sink. Is fixed on the heat sink.

The present invention uses a semiconductor wafer such as silicon (Si) based on the idea that the above-mentioned drawbacks can be solved by manufacturing a heat sink by selecting a material having a shape as large as possible rather than a block-shaped material. Then, first, the surface of the wafer is metallized in the state of a wafer, and subsequently, a region where a bonding flux is attached, that is, a mask having an opening formed in a region where an element is mounted is formed, and then, Using this mask, a bonding flux is attached to a semiconductor element mounting region which is an opening region of the mask, and further, at least one semiconductor element mounting region to which the bonding flux is adhered in an island shape is included. The wafer is diced into individual pieces to form a heat sink, and the elements are fixed to the heat sink via the island-shaped bonding melt.

Using a silicon (Si) wafer as a material for a heat sink is advantageous because fine processing is easy. For the purpose of the present invention, it is desirable to use a material having a relatively high resistance, and a material having a specific resistance of 100 [Ωcm] or more. Further, in the above metallizing step to the wafer, in the bonding flux adhering step, it is inevitable that the metal material used for metallizing also adheres to the side surface of the wafer, but the portion including these side surfaces is a dicing step that follows. There is no problem because it will be excluded by.

Further, in the above structure, as a material for metalizing the wafer, a semiconductor wafer, for example, a silicon (Si) wafer and a bonding flux, for example, gold
It is desirable to use a material that has good adhesion to both tin (Au and Sn) alloys, such as titanium / platinum / gold (Ti
/ Pt / Au) triple layers are practical.

According to the above configuration, the side surface is insulated, and a heat sink that can freely select the potential of the back electrode of the element can be manufactured without complicating the process. It is economically advantageous because there is no need to use expensive materials.

(6) Embodiments of the Invention Hereinafter, a method for manufacturing a semiconductor device according to an embodiment of the present invention will be described with reference to the drawings to clarify the configuration and specific effects of the present invention.

As an example, a case where a silicon (Si) wafer is used will be described.

See Fig. 1. The diameter is 3 to 5 inches and the thickness is about 300 μm.
Silicon (Si) wafer with a specific resistance of about 1 [kΩcm] 1
The conductive layers 2 and 2'are metallized on both surfaces of. In this process, first, a layer made of titanium (Ti) and platinum (Pt) is 600 [Å] and 1000 [Å], respectively, using a vacuum deposition method.
It can be performed by forming a gold (Au) plating layer to a thickness of about 2 [μm] by electroplating. In this process, the side surface of the wafer is also metallized at the same time, but when it is finally individualized into the heat sink, the one including the metallized side surface is eliminated, so that there is no problem.

See FIG. 2. Bonding flux is adhered to the semiconductor element formation-scheduled region 3 on the wafer 1 in an island shape as shown by hatching in the figure. In this step, a 1 [μm] square opening is formed in the resist formed on the conductive layer 2 by using the photolithography method, and the resist pattern is used as a mask to use the vacuum deposition method to form gold. The island-shaped region 3 made of the bonding flux is formed by depositing a bonding flux made of a tin (Au / Sn) alloy or the like and removing the resist.
Can be formed. At this time, the thickness of the bonding flux is 2
[Μm] is suitable.

See FIG. 3. Wafer 1 is diced along line 4 into individual heat sinks and divided into respective heat sinks as shown in the perspective view of FIG.
At this time, the island-shaped regions 3 made of the bonding melt are formed on the respective heat sinks.

See FIG. 5. The element 5 having the back surface electrode 5 ′ and the surface electrode 5 ″ is fixed to the heat sink 1 in which the island-shaped region 3 made of the bonding fusion material is formed via the island-shaped region 3. The fixed heat sink is mounted on the support member 6.
Incidentally, in this example, the back surface electrode 5'is a positive electrode,
The surface electrode 5 ″ is a negative electrode. As is clear from the figure,
Since the side surface 1'of this block-shaped heat sink is not metallized, the upper and lower conductive layers 2 and 2'are insulated from each other, and the potential of the electrode 5'contacting the heat sink can be freely selected. You can input a signal to. Since silicon (Si) wafers are easily available, they are very advantageous from an economical point of view.
The conductive layer 2 ′ serves as a bonding melt when it is fixed to the support member 6.

(7) Effects of the Invention As described above, according to the present invention, the side surface of the heat sink is insulated, and the potential of the electrode of the element in contact with the heat sink, that is, the back surface electrode can be freely selected. As a result, it is possible to provide a method for manufacturing a semiconductor device in which a signal for operating a semiconductor element can be input from either the front surface electrode or the back surface electrode of the element.

[Brief description of drawings]

FIG. 1 is a perspective view of a cross section of a wafer in a metallized state in a method for manufacturing a semiconductor device according to an embodiment of the present invention, and FIGS. 2 and 3 show the completion of main steps of the present invention. FIG. 4 is a plan view of a subsequent wafer, FIG. 4 is a perspective view of a completed heat sink, and FIG. 5 is a heat sink manufactured by using a manufacturing method according to an embodiment of the present invention. FIG. 6 is a side view showing a state in which the heat sink is fixed and the heat sink is attached to a support member. 1 ... Silicon (Si) wafer, 2, 2 '... Conductive layer,
3 ... Bonding melt adhering region, 4 ... Dicing line, 5 ... Semiconductor element, 5 ′, 5 ″ ... Semiconductor element back surface and front surface electrode, 6 ... Support member.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenichiro Takanatsu 3-9-11 Midoricho, Musashino-shi, Tokyo Inside the Nippon Telegraph and Telephone Public Corporation Musashino Telecommunications Research Institute (56) Reference JP-A-56-40251 (JP, A) ) JP-A-54-57957 (JP, A) JP-A-56-124248 (JP, A)

Claims (1)

[Claims] 1. A conductive layer is formed on the front and back surfaces and side surfaces of a wafer having high resistance, and a bonding melt is selectively applied to a region corresponding to a fixed region of a semiconductor element on the surface of the conductive layer. Dividing the wafer to include the adhered portions of the bonding flux and excluding the peripheral edge of the wafer to form a heat sink, and fixing the electrodes of the semiconductor element on the heat sink via the bonding flux. A method for manufacturing a semiconductor device, comprising: