JPS6189670A - Manufacturing method of semiconductor device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a method of manufacturing a semiconductor device including a process step of reducing the resistance of a contact portion between a silicon thin film and a metal electrode wiring.

Conventional configurations and their problems Many technologies have been developed to reduce the contact resistance between semiconductors and metal electrode wiring, but in particular metal electrode wiring for thin film silicon transistors, which has recently been put into practical use. There were various difficult problems regarding the connection. FIG. 2 shows a process diagram of a typical conventional thin film transistor manufacturing method. In Figure 2, ■ is the substrate, 2 is the gate electrode, 3 is the gate insulating film, 4 is the silicon thin film, 5 is the silicon thin film containing impurities, 6 and 7 are the silicon thin film left as the transistor region and the silicon containing impurities. Thin film, 7a
, 7b are source and drain regions, 8 is a region from which a silicon thin film containing impurities has been removed to form the source and drain, and 9a and 9b are metal electrode wirings connected to the source and drain, respectively.

A conventional example will be explained along with FIG. As shown in FIG. 2(A), a gate electrode 2 made of a chromium vapor-deposited film is formed on a substrate l. Next, as shown in FIG. 2(B), the substrate 1
The insulating film 3. Silicon thin film 4. A silicon thin film 5 containing n-type impurities is formed in the same apparatus. These thin films are formed by plasma CVD. First, a silicon nitride film is formed as the insulating film 3, then an intrinsic silicon thin film 4 is formed, and finally a silicon-containing thin film 5 containing phosphorus is formed. Next, as shown in FIG. 2C, the silicon thin film 4.5 outside the transistor region is removed, leaving the silicon thin films 6 and 7. Next, in order to form a source and a drain, a portion of the silicon thin film containing phosphorus is removed in region 8, as shown in FIG. 2(D). Finally, as shown in Fig. 2 (E'), the electrode wiring 9a,
Form 9b.

In the above conventional method, the metal electrode wiring 9a.

9b is connected to the source and train regions 7a and 7b of the silicon thin film containing phosphorus, and this portion is in ohmic contact. Further, since the silicon thin film 7 containing phosphorus and the silicon thin film 6 forming the active region are formed continuously in the same device, extremely good contact is achieved.

However, in the conventional example, it is extremely difficult to form region 8 in FIG. 2(D). That is, the second
After the process shown in Figure (C), a photosensitive resin film is formed on the entire surface, and the silicon thin film is exposed only in the region 80 and etched. There is no difference in etching rate between the silicon thin film 7 containing the active region and the silicon thin film 6 forming the active region, and it is extremely difficult to accurately etch only the silicon thin film 7. If the etching is insufficient, a current leak will occur between the source and drain regions 7a and 7b, while if the etching is excessive, the active region will become thinner and the transistor characteristics will deteriorate.

In addition, from the point of view of the manufacturing equipment, if the silicon thin film 4 containing no impurities and the silicon thin film 5 containing impurities are grown consecutively in the same equipment, the inside of the equipment will be contaminated with impurities, and the transistor characteristics will deteriorate in this respect as well. This causes problems in terms of livelihood.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a method for manufacturing a semiconductor device that allows metal electrode wiring to be connected to a silicon thin film with low resistance without deteriorating the characteristics of the semiconductor element.

It is to provide.

Structure of the Invention The present invention relates to a method of doping impurities into a silicon thin film, particularly amorphous silicon, in which the surface of the silicon thin film is converted to n-type or P-type at a low temperature by treating the substrate in a plasma gas containing impurity gas. It is an attempt to change the shape. That is, the method for manufacturing a semiconductor device of the present invention includes the steps of forming a silicon thin film on a substrate, forming an insulating film on the silicon thin film, and selectively forming a photosensitive resin film on the insulating film. a step of etching the insulating film using the photosensitive resin film as a mask; a step of doping the impurity into the silicon thin film through an opening in the insulating film; and removing the photosensitive resin 1). and a step of forming a metal electrode wiring in the impurity doped region of the silicon thin film and a selected region on the insulating film, the contact resistance between the silicon thin film and the metal electrode wiring can be made low and ohmic Moreover, the characteristics of thin film semiconductor devices can be stabilized.In addition, since the film forming process and the impurity introduction process are performed separately, contamination in the film forming process can be reduced. do not have.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiment S of the present invention will be described in detail with reference to the drawings. In FIG. 1, 1 to 4 are the same as those with the same reference numerals in FIG. 20 is an insulating film (protective film), 21 is a photosensitive resin film, and 22, 3.degree. 22b is an opening in the photosensitive resin film 21 for forming a source and a drain. 23a, 23b are openings in the insulating film, 24a, 2
4b is an impurity doped region in which impurities are introduced into the silicon thin film, and 25a and 25b are metal electrode wirings.

First, as shown in FIG. 1(A), a gate electrode 2, a gate insulating film 3. Silicon thin film 4. A photosensitive resin film 21 is formed on a glass substrate l on which an insulating film 20 is formed. Note that the silicon thin film 4 is generated by decomposing silane gas in plasma.

Next, as shown in FIG. 1(B), the photosensitive resin film 21
Openings 22a and 22b are provided in the openings 22a and 22b. When this state is placed in a plasma etching apparatus and etched with Freon gas plasma, an opening 23a is formed in the insulating film (nitride film) 20 as shown in FIG. 1(C).

23b is formed. In etching using Freon gas, the etching rates of the insulating film (nitride film) 20 and the silicon thin film 4 are different from each other, so control is extremely easy. After forming the openings 2'3a and 23b, the first
As shown in Figure (D), an n layer 24a is formed in the silicon thin film 4.
, 24b are formed. In this case as well, there is no need for control in the depth direction.

Next, the photosensitive resin film 21 is removed and aluminum electrodes 25a and 25b are formed.

In this way, a layer containing a high concentration of impurities can be interposed between the silicon thin film 4 and the aluminum electrodes 25a and 25b, so that ohmic contact can be easily achieved. Note that in order to form the P layer, the steps shown in FIGS. 1(C) to (D) must be performed in a plasma gas containing boron.
All you have to do is follow the process.

The above process is particularly effective when the silicon thin film is amorphous silicon and contains hydrogen.

From the above, according to the above-described implementation method, the contact resistance between the silicon thin film and the metal electrode storage can be reduced, and the thin film transistor can be stabilized due to the ohmic structure. Also, from the perspective of the process and manufacturing equipment, the film forming process (the process of forming the gate insulating film 3, silicon thin film 4, and insulating film 20 in the same chamber) and the openings 23a, 2 of the insulating film 20
Since the steps of forming 3b and forming the impurity-introduced layer are performed separately, there is no contamination in the film forming process. Furthermore, since the photosensitive resin film 21 is provided with openings, impurities are not introduced into unnecessary parts. It has the above-mentioned effects and is an industrially extremely effective manufacturing method.

Effects of the Invention According to the method for fabricating a semiconductor device of the present invention, an impurity layer is formed by impurity doping from an opening in an insulating film to make the contact resistance between a silicon thin film and a metal electrode wiring low and ohmic. Therefore, the characteristics of the semiconductor device can be stabilized, and since the film formation and impurity doping are performed separately, there is no contamination in the film formation process, which also stabilizes the characteristics of the W film semiconductor device. can be done.

[Brief explanation of drawings]

FIG. 1 is a process diagram for explaining one embodiment of this invention,
FIG. 2 is a process diagram for explaining a conventional example. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Gate electrode, 3... Gate insulating film, 4... Silicon thin film, 5... Insulating film (protective film), 21... Photosensitive resin film, 22a, 22b...Opening in photosensitive resin film, 23a, 23b-Opening in insulating film, 24a. 24b... Impurity doping region, 25a, 25b metal electrode wiring

Claims (3)

[Claims] (1) A step of forming a silicon thin film on a substrate, a step of forming an insulating film on the silicon thin film, a step of selectively forming a photosensitive resin film on the insulating film, and a step of forming the photosensitive resin film on the insulating film. etching the insulating film using as a mask; doping the impurity into the silicon thin film through the opening of the insulating film; removing the photosensitive resin film; forming a metal electrode wiring in a selected region on the insulating film. (2) The method for manufacturing a semiconductor device according to claim (1), wherein the silicon thin film is generated by decomposing silane gas in plasma. (3) The insulating film is etched by plasma etching, and the impurity is doped into the silicon thin film through the opening of the insulating film by processing in a gas plasma containing the impurity, and the insulating film The method of manufacturing a semiconductor device according to claim 1, wherein the etching and doping of the impurity are performed in the same chamber.