JPS5975650A - Heat sink for semiconductor device - Google Patents

Abstract

PURPOSE:To improve the radiation efficiency of the semiconductor device, and to mount even an ultra-high density integrated circuit easily by forming a square pole-shaped projection to one side surface of an Si or Ge single crystalline substrate and fixing a surface on the reverse side onto the back of a semiconductor substrate. CONSTITUTION:Silicon nitride films 12 are deposited on both surfaces of the silicon single crystalline substrate 11 through a CVD method, a latticed resist-pattern 13 at desired intervals is formed on either one surface of the films 12 by using optical exposure technique, etc., and another surface is coated with a resist 14. The silicon nitride film 12 is etched and removed through plasma-etching using a gas such as, CF4 gas, etc. while using the resists 13, 14 as protective films to form a desired silicon nitride film pattern 12', and the resists 13, 14 are removed. The substrate 11 is etched and removed selectively up to desired depth in an anisotropic etching liquid while using the silicon nitride films 12, and 12' as protective films to form the heat sink 11'. When the heat sink 11' and the semiconductor substrate 18 are unified, heat generated in a circuit formed on the substrate 18 is discharged effectively into a coolant such as air from the projecting sections of the surface of the heat sink 11'.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat sink attached to a semiconductor device.

In recent years, as semiconductor devices have become smaller and more dense, the dissipation of heat generated from the devices has become an important issue. Conventionally, such semiconductor devices have low pattern density.

In particular, since the wiring pattern width was relatively large, at least several μm, the desired cooling effect could be obtained by forcibly dissipating heat to the outside using at least a cooling fan or the like. However, in recent years, with the increase in pattern density, the amount of heat generated per unit area of semiconductor devices has increased.
The above-mentioned methods do not provide a sufficient cooling effect, and there have been concerns that the characteristics of the semiconductor device may deteriorate due to temperature rise and the length of the semiconductor device may be shortened. The present invention improves the heat dissipation efficiency, which is a drawback of conventional semiconductor devices as described above, makes it possible to easily implement ultra-high-density integrated circuits, and significantly extends the reliability and life of the integrated circuits. It is. The details of the present invention will be explained below with reference to the drawings.

Each of the figures from FIG. 1 (al to (f)) is a schematic cross-sectional view showing the steps of manufacturing a semiconductor device equipped with a heat sink of the present invention in order. A silicon nitride film 12 is deposited on the surface of a silicon single crystal substrate 11 to a thickness of several hundred N to several thousand by conventional CVD.
I) method or plasma CVD method (Figure (a)).

Next, on one surface of the silicon nitride film 12, a resist pattern 13 in the form of a lattice or line and space with a desired spacing is formed using an optical exposure technique, and the other surface of the silicon nitride film is formed. Cover with resist 14 (Figure (b)). Thereafter, using the resists 13 and 14 as a protective film, the silicon coating #2 is etched away by plasma etching using, for example, CF4 gas to form a desired silicon coating pattern 12'.

The resists 13 and 14 are removed (FIG. (C)). Next, to silicon (chemical formula 11!; S 12 and 12' is tri
Make it into your eyes.

fUed: δi; Anisotropy of potassium hydroxide bath solution of 30 Jusaka Yu C 111 (1101 in cutting solution)
Silicon single crystal substrate lif: selectively etched away to desired depth, followed by silicon nitridation +1!412 and 12
' was removed by etching using phosphoric acid, and lll1
A peat sink 11' is formed of the - section of the silicon single crystal substrate having a protrusion surrounded by 111.11 on one side ((Fig. 111).
2't does not necessarily have to be removed. Next, is the flat iF of the heat sink 11? A 15J titanium film with a thickness of several sevens or hundreds on the surface? Above list 1-8 to several hundred thick platinum error 16
4111 selections are continuously sputter-deposited (Figure (e)).

Finally, a gold-tin alloy layer 17 with a thickness of several μm is vacuum-deposited on the surface of the platinum thin film 16, and then heated to about 350°C.
The tin alloy layer 17 is melted, and the back surface of the semiconductor substrate 18 on which an arbitrary circuit has been formed is fused to the gold-tin alloy layer 17, and tin is used for the heat sink lI' and the semiconductor layer υ. However, it is still possible to use tantalum, nickel, or chromium instead of titanium in the 150s.

In the semiconductor device formed as described above, the surface area of the semiconductor device is significantly increased due to the protrusions formed on the surface of the heat sink using an anisotropic etchant. That is,
Heat generated in a circuit formed on a semiconductor substrate is conducted to a heat sink through a good conductor, and is effectively released into a cooling medium such as nitrogen through a protrusion provided on the surface of the heat sink. . The spacing and depth of the protrusions formed on the heat sink surface can be changed depending on the expected heat generation cover of the circuit, thereby always achieving the desired heat dissipation effect.

In addition, in the above embodiment, the heat sink material and 17
1111) A Si substrate with one main surface was used, but
1111) l of Gc with the same diamond-shaped lattice
...A ≠crystalline substrate with i on the main surface is also good.

By mounting the semiconductor device provided by the present invention in the following manner, even more remarkable effects can be achieved. FIG. 2 is a diagram schematically showing an example of a method for mounting a semiconductor device provided by Honkosu 1. A four-body cow device 21 provided with a heat sink 23 is arranged three-dimensionally with a gap and is fixed by a support 22. The external leads of the semiconductor device 21 are taken out at desired positions near the outer periphery of the semiconductor device 21 and connected to interconnection terminals provided on the pillars 22 by, for example, chip carrier type mounting using metallized conductors. The semiconductor device mounted as described above has not only high cooling efficiency but also has the ability to be made smaller than conventional semiconductor devices.

The application of the present invention is not limited to semiconductor integrated circuits, but it goes without saying that it is also highly effective for semiconductor lasers and light emitting diodes.

[Brief explanation of the drawing]

An example of the manufacturing method of the half-fourth suspension device is shown in step 11. FIG. 2 is a perspective view schematically showing an example of a method for mounting a semiconductor device according to the present invention. Each number in the figure indicates the following. [1...(1101 silicon single crystal substrate, 12...
Silicon nitride film, 13.14...resist. 12'...Pattern formed from a part of the silicon nitride film 12, 11', 23...(l l (l l Heat sink formed from a part of the silicon value crystal substrate 11) 15...Titanium Hiroshi Ji Body, 1G... platinum thin j model,
17... Gold-tin piece gold pI film, 18...
semiconductor substrate. 21...Semiconductor device, 22...Supportability. Figure 1/cL) rh lC] (Figure 2)

Claims (1)

[Claims] 11101-plane Si single crystal substrate or (110)-plane Ge
A square prism-shaped protrusion having a (111) plane as a side surface is provided on one side of the single crystal substrate, and the piece 1! It's the opposite of
A heat sink for a semiconductor device IFt, in which a semiconductor device is formed on one surface of 111 and is fixed to the same surface of a semiconductor substrate.