JPS58182273A - Manufacture of thin film semiconductor device - Google Patents

Abstract

PURPOSE:To improve the characteristics of a thin film semiconductor device without increasing the number of processes by a method wherein the photo etching of a semiconductor thin film serving as the substrate of an MOS type transistor and the photo etching to form contact holes on an insulation film on the thin film are performed in the same process. CONSTITUTION:A P doped polycrystalline Si layer is grown on the transparent insulation substrate, and a gate wiring 10, a source region 11, and a drain region 12 are formed by photoetching. Next, a gate oxide film 13 is adhered on the wiring 10 while filling the clearance between the regions 11 and 12, then a polycrystalline Si film 14 is adhered over the entire surface including it, and then the entire surface is covered with a wiring insulation film 15. Thereafter, the formation of the contact holes 16 for the regions 11 and 12 and the etching of the Si film 14 are performed in the same process, thus a gate electrode is adhered on the exposed Si film 14, and Al wiring 18 are mounted on the exposed regions 11 and 12.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a method of manufacturing a thin film semiconductor device, particularly a thin film semiconductor device using polycrystalline silicon.

An object of the present invention is to improve the characteristic sound of a thin film semiconductor device without increasing the number of steps in manufacturing the thin film semiconductor device.

In recent years, liquid crystal display devices having switching transistor arrays using thin-film semiconductor devices have attracted much attention as display devices for consumer electronics because they are capable of graphical display and have low power consumption. Semiconductor thin films include single crystal silicon, polycrystalline silicon, amol 7 anusilicon,
Although selenium, tellurium, and silicon are used, the method using polycrystalline silicon is the closest to practical use, judging from ease of manufacture and long-term reliability.

This will be explained in more detail below with reference to the figures.

FIG. 1 is a sectional view of a thin metal semiconductor device using polycrystalline silicon manufactured by a conventional manufacturing method. In the conventional manufacturing method, polycrystalline silicon, which is the base of the semiconductor device, is photo-etched onto a transparent insulating substrate 2 in order to minimize the number of photo-etching steps required to make a semiconductor device. Form an island shape by etching SK, and thermally oxidize the same length crystal silicon lIt to oxidize the gate M3.
form. Thereafter, a goo F wiring 4 is formed using polycrystalline silicon, and is self-aligned with the gate wiring 4 to form a source region 5 and a dosi region 6. In the conventional manufacturing method, four photo-etching steps are required to form the inter-wiring insulation 117, to form the contact hole 80 for the insulation expansion 7, and to form the aluminum ridge @9. However, it is not doped with phosphorus.
It is a well-known fact that a silicon oxide film formed by oxidizing polycrystalline silicon has poor insulation properties, so the thickness of the gate oxide film must be increased, which deteriorates the characteristics of the semiconductor device. The above-mentioned drawbacks can be overcome by turning the semiconductor device 9 upside down and doping the semiconductor device 9 with phosphorus and oxidizing the gate wiring made of polycrystalline silicon to form a gate oxide film. Since a photo-etching process is required to form the source and drain region tubes that are self-aligned with the wiring, it requires 5 photo-etching processes to form the aluminum wiring, which is 91 times more than the conventional method. Manufacturing costs will increase.

The present invention eliminates the above-mentioned drawbacks by etching the polycrystalline silicon film serving as the base of the semiconductor device and forming Q contact holes in the same photoetching process, thereby eliminating the need to increase the number of photoetching processes. This is a thin film semiconductor device and manufacturing method that enables a structure in which a gate interconnect II is oxidized to form a gate oxide film. jll! The method for manufacturing a '1IIiW11 semiconductor device of less than zero is shown in MIi diagrams in FIG. 2 and below. After doping the phosphorus and photoetching the polycrystalline silicon to form the gate wiring 10, the source region 11 and the drain region 12f, a dirt oxide film 13 is formed to connect the source region, the drain region and the gate wiring with the Al2 interconnection. When the oxide film at the contact portion is removed, the shape shown in FIG. 2 is obtained. A flattened fist can also be created using selective oxidation. In the step of the third factor, a polycrystalline silicon group 14 is formed, and inter-wiring insulation l1Iis is formed without photoetching. In the process shown in FIG. 4, the formation of the contact hole 16 and the etching of the polycrystalline silicon 1114 are performed in the same photoetching process. Etch the crystalline silicon group with Creon Goodsma.

Polycrystalline silicon doped with phosphorus has a low etching rate (polycrystalline silicon, which is not doped with phosphorus), and polycrystalline silicon doped with 3-tact IIO phosphorus is not damaged by the above etching.

The end portion 17#i of the polycrystalline silicon film 411 shown in FIG. [By etching method] The oxide film is uniformly etched over the entire surface. The source and drain regions are expanded by heat treatment (DM) (1! An I-type semiconductor device is formed. After that, if Arun wiring is formed, the photo-etching process is repeated four times as in the conventional method. Since oxide II is much softer than the conventional one and is greatly improved, it can be formed relatively thin, and the characteristics of the MOEI type semiconductor device are improved.

As described above, by using the manufacturing method of the present invention, the characteristics of a thin film semiconductor device can be improved without increasing the number of manufacturing steps.

When using a semiconductor device manufactured by the manufacturing method of the present invention in a liquid crystal display panel, at least the gate wiring is At the intersection of the gate wiring and the aluminum wiring, the oxide film on the gate wiring is removed, and the gate wiring and the polycrystalline silicon are brought into close contact with each other, leaving a wiring gap 5iia without leaving any floating polycrystalline silicon.

Although the case where polycrystalline silicon M is used as the semiconductor substrate has been described above, the same thing can be done using single crystal silicon or other semiconductor material tubes.

Since the thin film semiconductor device manufactured by the manufacturing method of the present invention has excellent Fi characteristics, it can be highly expected to be used as a switching transistor array for a liquid crystal display device.

[Brief explanation of drawings]

The agi figure is a cross-sectional view of a -ks, III semiconductor device using polycrystalline silicon manufactured by a conventional manufacturing method. FIG. 2 is a cross-sectional view showing a method for manufacturing a vAo*m semiconductor device produced by fg5 Acupuncture. 1.14... Polycrystalline silicon 3.13... Gate oxide film 4.10... Dirt wiring 5, 11... Source region 6.12. φ drain region 7.15. Self-registered line insulating film 8, 16.・Contact hole 9.18... Aluminum wiring or above Applicant: Hoseikosha Co., Ltd. Figure 5

Claims (1)

[Claims] A method for manufacturing a thin film semiconductor device, characterized in that photo etching of a semiconductor thin film serving as a base of a MOB type transistor and photo etching for forming a contact hole in an insulating film on a conductive thin film are performed in the same photo etching process.