JPH0750748B2 - Semiconductor device having protective film and manufacturing method thereof - Google Patents

Description

The present invention relates to a semiconductor device having a protective film and a method for manufacturing the same, and more particularly to improving heat dissipation of a circuit element of a semiconductor integrated circuit. The present invention relates to improvement of a method for forming a protective film having radiation resistance on a circuit.

(Prior Art) Conventionally, when an integrated circuit is formed on a semiconductor substrate,
A protective film is formed on the uppermost layer of the integrated circuit in order to avoid external influences such as radiation (alpha rays).

FIG. 4 is a sectional view showing the structure of an integrated circuit having the protective film formed on a semiconductor substrate.

That is, the integrated circuit formed on the semiconductor substrate 1 of FIG. 4 is composed of the logic circuit element region 2 and the memory circuit element region 3. Further, the wiring protection film 4 is formed on the second layer on each region, and the radiation protection film 5 is formed on the uppermost layer.
Are formed.

The memory circuit element A in the memory circuit element region 3 is
It has a static random access memory (SRAM) structure, on which wiring 6 is provided, and a wiring protective film 4 made of an insulating material is formed to protect this.

Since the memory circuit element A has an SRAM structure, it is required to have radiation resistance that does not cause an error in its operation even when exposed to a predetermined amount of radiation. Therefore, a protective film for radiation resistance is also required, and the protective film of the memory circuit element A shown in FIG.
A radiation protective film 5 having a thickness of about 50 μm is formed.

Similarly, in the logic circuit element region 2, the wiring 6 is provided on the logic circuit element B, and the wiring protection film 4 made of an insulating material for protecting the wiring 6 is formed.

Furthermore, when the protective film 5 for the radiation resistance of the memory circuit element A is formed, the protective film 5 serves as the wiring protective film 4.
It is also formed on the top.

(Problems to be Solved by the Invention) As described above, in the logic circuit element region 2 and the memory circuit element region 3 formed on the semiconductor substrate 1, the protective film 5 for radiation resistance is formed on the uppermost layer. Has been done.

However, since the logic circuit element B has good radiation resistance in terms of the element structure, the protective film 5 as described above is essentially unnecessary. On the contrary, since the protective film 5 is a thick film, the heat generated by the operation of the circuit element becomes difficult to dissipate.

That is, since it is difficult to radiate heat as compared with an integrated circuit which is composed of only logic circuit elements and in which the protective film 5 is not formed as described above, malfunction of the circuit elements and damage due to heat are likely to occur.

Therefore, the present invention is a circuit in which an integrated circuit formed on the same semiconductor substrate has both a logic circuit element region and a memory circuit element region, particularly in an integrated circuit requiring a protective film for radiation resistance, The purpose is to improve the reliability of logic circuit elements in the integrated circuit.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the problems of the prior art, the present invention relates to storage in a semiconductor integrated circuit including a logic circuit element and a storage circuit element formed on a semiconductor substrate. A radiation-resistant first protective film formed on the uppermost layer of the circuit element region, and an upper layer of the first protective film and the logic circuit element region, which are formed above the first protective film. Radiation resistance formed in the uppermost layer of a semiconductor device having a sufficiently thin second protective film or a memory circuit element region in a semiconductor integrated circuit including a logic circuit element and a memory circuit element formed on a semiconductor substrate A semiconductor device including a first protective film having: is used.

In these semiconductor devices, a step of forming an integrated circuit having both a logic circuit element and a memory circuit element on the same surface of a semiconductor substrate, and a wiring protective film made of an insulating material on an upper layer of the integrated circuit. At least, a step of forming the first protective film for radiation protection on an upper layer of the wiring protective film, a step of completely removing the first protective film other than on the memory circuit element region, It is manufactured by a manufacturing method including a step of forming the sufficiently thin second protective film for radiation protection on the upper layer of the first protective film.

Alternatively, a step of forming an integrated circuit having both a logic circuit element and a memory circuit element on the same surface of a semiconductor substrate, a step of forming a wiring protective film made of an insulating material on the upper layer of the integrated circuit, and the wiring And a step of completely removing the first protective film other than on the memory circuit element region, the method further comprising: The aforementioned problems are solved by using a method for manufacturing a semiconductor device.

(Operation) By forming a protective film for radiation resistance by the manufacturing method and structure as described above, radiation is improved, and malfunction of circuit elements and damage due to heat are less likely to occur, and reliability of integrated circuits is improved. Can be improved.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

1 (a) to 1 (c) show, as a first embodiment of the present invention, a process of manufacturing a protective film for radiation resistance (alpha rays, etc.) provided in an integrated circuit formed on a semiconductor substrate. It is a thing.

That is, as shown in FIG. 1A, an integrated circuit composed of a logic circuit element region 2 and a memory circuit element region 3 having an SRAM structure C is formed on a semiconductor substrate 1 by a well-known process. A wiring protective film 9 made of an insulating material for protecting the wiring 8 on the circuit element region is formed. Furthermore, a protective film 10 is formed on the uppermost layer as a protective film for radiation.

This protective film 10 is formed by coating polyimide with a coating device or the like.
It is formed to about 45 μm.

Then, as shown in FIG. 1B, a resist pattern is provided on the protective film 10 by using a photolithography method, and a portion on the logic circuit element region 2 and an electrode portion such as a bonding pad are formed by etching or the like. The protective film (not shown) is removed.

Further, as shown in FIG. 1C, the protective film of FIG.
On the semiconductor substrate 1 from which 10 has been removed, polyimide is formed again as a protective film 11 to a film thickness of about 5 μm by a coating device or the like. On this semiconductor substrate 1, the protective film 11 such as an electrode portion (not shown) such as a bonding pad is removed by using a photo-etching method.

A second embodiment is shown in FIGS. 2 (a) and 2 (b).
That is, in FIG. 2A, an integrated circuit including a logic circuit element region 2 and a storage circuit element region 3 is formed on the semiconductor substrate 1 in the same manner as in FIG. 1A described above.
A wiring protective film 13 made of an insulating material for protecting the wirings 12 on both circuit element regions is formed on the layer. Further, there is a protective film 14 formed of polyimide with a film thickness of about 45 μm as a radiation protective film on the uppermost layer.

Then, as shown in FIG. 2 (b), the protective film 14 is formed by etching or the like as in FIG. 2 (b) by using a portion on the logic circuit element region 2 or a connecting electrode portion (bonding pad or the like). The protective film (not shown) is removed.

A third embodiment as an example in which the present invention is applied to a semiconductor integrated circuit including a memory circuit element having a dynamic random access memory (DRAM) structure is shown in FIGS. 3 (a) to 3 (c). Show. That is, FIG. 3A shows a logic circuit element region formed on the semiconductor substrate 1 by a known process.
15 and a memory circuit element region 16 having a DRAM structure D are formed, and a wiring protection film 18 made of an insulating material for protecting the wiring 17 on both circuit element regions is formed on the second layer. . Furthermore, the topmost layer is a protective film as a protective film for radiation.
19 are formed. The protective film 19 is formed of polyimide with a film thickness of about 45 μm by a coating device or the like.

And in FIG. 3 (b), the above-mentioned FIG. 1 (b) is shown.
A resist pattern is formed on the protective film 19 by using a photo-etching method in the same manner as in the manufacturing process of, and dry etching or the like is used to form a portion on the logic circuit element region 15 or an electrode portion such as a bonding pad ( The protective film (not shown) is removed.

Further, in FIG. 3 (c), FIG.
In the same manner as in the manufacturing process of, the semiconductor substrate 1 from which the protective film 19 of FIG. 3B has been removed is again formed with a film thickness of about 5 μm as a protective film 20 of polyimide by a coating device or the like. In this semiconductor substrate 1, the protective film 20 such as an electrode portion (not shown) such as a bonding pad is removed by dry etching or the like as in FIG. 3B.

In each of the first and third embodiments of the present invention, the radiation protective film provided on the upper layer of the memory circuit element region has a film thickness of 20 to 50 calculated from the predicted radiation dose.
The thickness of the protective film for radiation formed on the upper layer of the logic circuit element region does not require consideration of the radiation dose, so that the film thickness is about 5 to 10 μm.

Further, the storage circuit element is a storage circuit element having a DRAM structure having a storage capacity of 16 Kbytes or more, or a storage circuit element having an SRAM structure having a storage capacity of 8 Kbytes or more.

Further, the present invention is not limited to such embodiments, and it goes without saying that various modifications and applications can be made without departing from the scope of the invention.

[Effect of the Invention] According to the present invention, the protection film for radiation resistance on the logic circuit element can be thinned or removed by forming the protection film for radiation resistance by the manufacturing method and the structure as described above. Therefore, the heat generated by the operation of the circuit element is easily dissipated, the malfunction of the circuit element and the damage due to the heat are less likely to occur, and the reliability of the semiconductor integrated circuit can be improved.

[Brief description of drawings]

1 (a) to 1 (c) are sectional views showing the structure of an integrated circuit formed on a semiconductor substrate as a first embodiment of the present invention in the order of manufacturing steps, and FIGS. 2 (a) and 2 (b). 3A) is a cross-sectional view showing the configuration of an integrated circuit formed on a semiconductor substrate as a second embodiment of the present invention in the order of manufacturing steps, and FIGS. 3A to 3C are respectively third views.
4 is a cross-sectional view showing the configuration of an integrated circuit formed on a semiconductor substrate as an example of the above, in the order of manufacturing steps, and FIG. 4 is a cross-sectional view showing the configuration of an integrated circuit formed on a semiconductor substrate as a conventional example. 2 ... Logic circuit element region, 3 ... Memory circuit element region, 9 ... Wiring protective film, 10 ... First protective film, 11 ... Second protective film.

Claims (2)

[Claims] 1. A first protective film having radiation resistance is formed on the uppermost layer of the memory circuit element region in a circuit composed of a logic circuit element and a memory circuit element formed on the same semiconductor substrate, and the first protective film is formed. A semiconductor device, wherein a second protective film, which is sufficiently thinner than the first protective film, is formed on the first protective film and the upper layer of the logic circuit element region. 2. A first step of forming an integrated circuit including a logic circuit element and a memory circuit element on the same surface of a semiconductor substrate, and an insulator on an upper layer of the integrated circuit formed by the first step. And a third step of forming the first protective film for radiation protection on an upper layer of the wiring protective film formed by the second step, A fourth step of completely removing the first protective film other than on the memory circuit element region formed by the third step; and the first protective film and the logic circuit formed by the fourth step. The method of manufacturing a semiconductor device according to claim 1, further comprising the step of forming the second protective film that is sufficiently thin for radiation protection on the element region and the upper layer.