JPS627142A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To flatten the surface of a semiconductor after melting and solidifying by forming a film capable of melting, emitting an energy beam to the film to once melt the film, and utilizing the fluidity of the melted film material. CONSTITUTION:When an energy beam 4 is emitted to a polysilicon film 3 having an irregular surface, the film 3 of the emitted portion is melted to form a melted region 5, the region 5 is moved by scanning the beam 4, and fluidized to resultantly flatten the surface. The film 3 may be formed of a material which is melted by emitting the energy beam, fluidized and resolidified such as preferably polysilicon used in an SOI technique. The beam 4 is preferably Ar<+> ion laser frequently used in a semiconductor manufacturing process, and can use an electron beam.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an improvement in a method for manufacturing a semiconductor device, and more specifically, to planarize the surface of a semiconductor fabricated with an integrated circuit element, and flatten the surface of a semiconductor fabricated with an integrated circuit element. The present invention relates to a method for manufacturing a semiconductor device suitable for manufacturing a semiconductor device having a stacked structure in which mutual interference between the two layers is prevented.

<Prior art> Generally, the surface of a semiconductor substrate on which an integrated circuit is fabricated has unevenness due to the oxide film during circuit fabrication and conductors such as wiring and electrodes that electrically connect circuit elements. There is. Such surface irregularities are not preferable when manufacturing a semiconductor device having a structure in which wiring is stacked in multiple layers, or a stacked semiconductor device which is being developed to achieve higher density and higher functionality. Especially in stacked semiconductor devices,
Since single-crystal layers serving as active layers are stacked with an insulating film interposed therebetween, surface steps and unevenness have a negative effect on the crystal growth process and its crystallinity.

For this reason, various methods for flattening the surface shape of the semiconductor layer 0 have been developed and proposed.

Typical flattening treatments include: ■ Etch pack flattening method using an organic coating film and constant-speed etching, ■ Method of forming an inorganic coating film and flattening it, ■ Film deposition method using bias putter method, is proposed.

The above method (■) forms an organic coating film by applying an organic coating film material so that the surface is flat on an insulating film whose surface has irregularities that roughly correspond to the irregularities occurring on the substrate surface. After that, isokinetic etching is performed from the surface of the organic coating film,
The flat surface of the original organic coating film is transferred to the insulating film to make the insulating film almost flat.

In addition, in the method (2) above, an inorganic coating film material is applied as an insulating material on an insulating film with an uneven surface, and the unevenness on the surface of the insulating film is smoothed by this inorganic coating film. Etching is performed from the surface of the coating film to make the insulating film substantially flat.

<Problems to be Solved by the Invention> However, in the method (i) and (a) above, when the uneven pattern of the base is complex and there are several types of unevenness, it is difficult to flatten the unevenness of the base. The process is complicated, such as setting the thickness of the organic film and forming dummy patterns.

In addition, in the method (2) above, it is difficult to form a thick film with an inorganic film compared to an organic film, and in order to obtain a desired thick film, the film shape problem must be solved several times. Yes, and the setup process is complicated.

Furthermore, in order to achieve complete planarization, none of the above methods can be said to be satisfactory, as the throughput does not increase, and the development of a new planarization method is desired. Ta.

The present invention has been devised in view of the above points, and is a method for manufacturing a semiconductor device that can perform planarization processing with a simple process and can prevent mutual interference between upper layer devices and lower layer devices. is intended to provide.

<Means for Solving the Problems> In order to achieve the above object, the method for manufacturing a semiconductor device of the present invention provides a method for manufacturing a semiconductor device in which a semiconductor substrate is coated on the surface in order to flatten unevenness on the surface after device formation. Forming a film (for example, a polysilicon film, etc.) that can be selectively melted by irradiation with an energy beam such as a laser or an electron beam, and then irradiating the above film with the energy beam,
The method is configured to include a step of melting the film and flattening the semiconductor surface after melting and solidifying by utilizing the fluidity of the melted film material.

Further, according to the embodiments of the present invention to be described later, a semiconductor device implementing the present invention can be selectively manufactured by forming a base insulating film that serves as an insulating layer between layers and by irradiating an energy beam such as a laser or an electron beam. The process involves forming a conductive film (for example, a double polysilicon film) that can be melted automatically, and then irradiating this conductive film with an energy beam to melt it once, and using its fluidity to melt and solidify the semiconductor surface. The structure includes a planarization step and a step of forming an insulating film for insulating and separating this conductive film from the upper layer device.

Function> In addition to the above-described structure, the present invention deposits a film that can be selectively melted by an energy beam such as a laser or an electron beam on a semiconductor surface having irregularities, and then applies the energy beam to the film. By irradiating the film to melt the film and utilizing the fluidity of the melted film material, the semiconductor surface is flattened after melting and solidification.

Further, this planarization layer functions to prevent mutual interference between the upper layer device and the lower layer device, and also serves as a heat sink during formation of the upper layer device.

To further explain the flattening process in the present invention, its principle operation is as follows.

In general, when an energy beam such as a laser beam or an electron beam is irradiated onto a sample surface, for example, in the case of a laser beam, interference can be caused by absorption depending on the material constants of the sample, reflection at an interface, and even by adjusting the film thickness. The effects of the above are also combined to heat the sample. At this time, if the sample is heated above its melting point, only the beam irradiated part becomes molten. If the beam is scanned at this time, the liquid phase will move at the same speed as the beam scanning speed, and the liquid phase will quickly cool and solidify after the beam has moved. become.

FIG. 1 is a diagram for explaining the principle of the planarization process in the present invention. In the figure, 1 is a silicon substrate, and 2 is an insulating film (Si02) having an uneven surface.

Reference numeral 3 denotes a polysilicon film deposited on a surface having unevenness, and when the polysilicon film having unevenness is irradiated with an energy beam 4, the polysilicon film 3 in the irradiated part melts and a melted region 5 is formed. The melted region 5 moves and flows with the scanning of the energy beam 4, and as a result, the surface is flattened.

The film 3 may be made of any material that melts and re-solidifies when irradiated with an energy beam; for example, Sodium
I (Siljcon On In5ulator)
The preferred size is polysilicon used in the technology.

Further, as the energy beam 4, it is preferable to use an Ar ion laser, which is often used in semiconductor manufacturing processes, but the present invention is not limited to this, and it is also possible to use, for example, an electron beam.

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

FIGS. 2(a) to 2(e) are sectional views of a semiconductor device, respectively, for explaining one embodiment of the present invention.

First, as shown in FIG. 2(a), MO is applied to the semiconductor substrate 11.
S) Inserting circuit elements such as transistors, electrically connecting each circuit element with a conductor (wiring layer of high melting point metal, etc.) 14, and covering the surface with an insulating film 15. In addition, 12
is an insulating film. In this state, the surface of the underlying semiconductor substrate 110 has irregularities due to the conductor 14 and the like, so the surface of the insulating film 150 has corresponding irregularities.

Next, as shown in FIG. 2(b), a film for melting and planarizing, for example, a doped polysilicon conductive film (planarizing film) 16, is deposited on the insulating film 15.

Next, as shown in FIG. 2(c), the entire surface is scanned with an energy beam 17 such as a laser beam.

The polysilicon conductive film 16 is melted and re-solidified in a fluidized manner to planarize it as shown in FIG. 2(d).

Finally, as shown in FIG. 2(e), an interlayer insulating film 25 is formed on the planarization film 16, and a second layer of devices 20 is formed on it.
to complete the process.

Further, when a semiconductor device is formed to have a three-layer structure, a similar planarization process is performed at the 2Nth layer.

Hereinafter, the same process will be repeated for the four-layer and five-layer structures.

The planarization film (polysilicon conductive film) 16 located between the first layer element 10 and the second layer element 200 serves as a buffer layer, and prevents electrical interference between the devices 10 and 20 in the upper and lower layers. It plays the role of a heat sink when forming the upper layer device 29.

By manufacturing a semiconductor device through a process including the steps described above, (1) the surface is formed flat, improving processing accuracy;

■ Because the surface is flat, cracks in wiring and insulating films,
Disconnection, etc. will not occur.

(2) Problems such as inhibition of crystal growth due to steps that occurred during the formation of the second and subsequent active layers are solved, and a uniform and high-quality single crystal layer can be obtained.

(2) Electrical interference between active layers is prevented by inserting a flattened conductive film between each active layer.

■ The conductive film inserted for planarization acts as a buffer layer and serves as a heat sink when forming upper layer devices.

■ Reduces strain in laminated films, including single crystal layers.

■ Simplification of the process can be expected.

Benefits such as:

<Effects of the Invention> As described above, according to the present invention, it is possible to simplify the planarization process, which has conventionally been complicated.

Further, the element manufactured according to the present invention has the advantage of having a structure of a laminated device that prevents mutual interference between the laminated devices.

Further, since the planarization process requires only irradiation with an energy beam such as a laser, no additional manufacturer is required in the semiconductor device manufacturing process, and the manufacturing process is simplified. Furthermore, since it utilizes surface heating by beam irradiation, it is suitable for low-temperature processes, and as a result, it becomes possible to manufacture devices with a high-quality multilayer structure.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the operating principle of planarization processing in the present invention, and FIG. 2 is a cross-sectional view of a semiconductor device for explaining the steps of an embodiment of the present invention. . 1... Silicon substrate, 2... Insulating film, 3...
Poly V') 1-4, 4...Energy beam, '11
... Semiconductor substrate, 12.13 ... Insulating film,
14... Wiring layer, 15... Interlayer insulating film, 16
... Flattening film (buffer film), 17 ... Laser, 25 ... Interlayer insulating film, 10 ... First layer element, 20 ... Second layer element. Agent Patent attorney Aihiko Fukushi (and 2 others) Figure 1

Claims (1)

[Claims] 1. Forming a film that can be selectively melted by irradiating an energy beam on an uneven surface of a semiconductor substrate after device formation; irradiating the film with an energy beam to melt it; A method for manufacturing a semiconductor device, comprising the steps of: planarizing a semiconductor surface after melting and solidifying the film due to fluidity caused by melting the film; and forming an upper layer device. 2. The film is composed of a conductive film, and is formed after the formation of a base insulating film that serves as an interlayer insulating film, and an insulating film for insulating and separating the upper layer devices is further formed on the film after planarization. A method for manufacturing a semiconductor device according to claim 1, characterized in that: 3. The method of manufacturing a semiconductor device according to claim 1, wherein the film is composed of a polysilicon conductive film.