JPS6184065A - Manufacturing method of thin film transistor - 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) The present invention relates to a method for manufacturing a thin film transistor (hereinafter abbreviated as TPT).

(Prior Art) TPT generally has a structure in which a gate electrode is formed directly on a substrate, as shown in, for example, Japanese Patent Laid-Open No. 58-32468. When manufacturing such TPT, usually, first, on a glass substrate or alumina substrate,
A gate electrode metal layer made of nichrome (NiCr), tungsten (W), molybdenum (Mo), chromium (Cr), etc. is deposited by electron beam evaporation or sputtering, and processed into a predetermined pattern. Form a second electrode. Next, a silicon oxide (5inX) film or a silicon nitride (5inX) film is formed on it to become a gate insulating layer.
) membranes, respectively, N20 and 5iH4r NH5 and S I
H4 is deposited as a main component gas by a glow discharge method, and an amorphous 7-licon semiconductor layer, which will become a channel layer (active layer), is further deposited by a SIH4 glow discharge method.

Furthermore, the r-layer, which will become a low-resistance amorphous/recon layer, is immersed into the main component gas SIH4. ]~1.0% of PH3 is mixed and deposited by glow discharge method.

Next, the portion other than the portion that will become the TPT is processed and removed and patterned into an island shape to form a gate insulating layer and a channel layer.

Next, aluminum (At) will be used as the source and drain electrodes.
The layer is formed by vacuum deposition and processing.

(Problem to be solved by the invention) However, in this manufacturing method, leakage easily occurs between the gate electrode and the north electrode or between the gate electrode and the drain electrode due to the step difference caused by the gate electrode, so the gate insulating film is made thicker. I needed to.

An object of the present invention is to manufacture a highly reliable TFT with a high yield of 9 by eliminating the step difference in the gate electrode. □ (Means for solving the problem) The present invention first deposits a metal as a gate electrode material on the entire surface of the main part of the substrate, and then oxidizes the metal layer except for the area where the gate electrode is planned. forming a gate electrode;
After that, a gate oxide film and a semiconductor thin film layer are deposited, and a source electrode and a drain electrode are formed.

(Function) In this way, since the gate electrode is selectively formed by oxidizing the part other than the part that will become the gate electrode, a structure with no steps is created, and a relatively thin gate oxide film is used to form the gate electrode and the source. Leakage current between electrodes can be suppressed, and reliability can be improved.

(Example) 1. First, a mental (T
a) Depositing a film with a thickness of 100 to 1000λ.

After that, a patterning process is performed to cover only the part that will become the gate electrode using Lennost, etc., and then it is placed in a solution of distilled water and acid added, and a DC voltage of several tens to hundreds of volts is applied with the mental side as the anode. is applied to perform anodic oxidation (chemical conversion), and the entire exposed tantalum portion is converted into tantalum pentoxide (Ta205) to form the insulating layer 2.

Thereafter, the r-) electrode 3 formed in a predetermined pattern is formed by removing unnecessary renost and the like.

Thereafter, according to the usual method, a gate insulating layer 3, a channel layer 4, a low resistance amorphous silicon film 5, a north electrode 6,
The TPT is completed by forming the drain electrode 7.

In addition to the positive oxidation method, gate metal oxidation methods include
□The same thing can be done using a plasma oxidation method using plasma.

In addition, although tantalum was used as the gate electrode metal 7, titanium (Ti), aluminum (At), or oxide/gesten (W) was used as the gate electrode material, and the unnecessary portions were anodic oxidized. TPT is similarly completed by plasma oxidation to form a titanium oxide layer (TlO2), an aluminum oxide layer (At203), and a tungsten oxide layer (TlO2), respectively.

(Effects of the Invention) As described above, according to the present invention, by performing anodic oxidation or plasma oxidation at the time of forming the gate electrode to oxidize the unnecessary C-V electrode portion and make it an insulator, the step difference due to the film thickness of the gate electrode can be reduced. It is now possible to form a flat gate electrode without any cracks. Therefore, it has become possible to suppress leakage current between the gate electrode and the north electrode, and between the gate electrode and the drain electrode to a minimum.

Furthermore, this manufacturing method does not require expensive equipment and can be manufactured using normal processes, resulting in low cost.

In addition, high reliability is expected as there are no problems with the steering or mechanical systems.

[Brief explanation of drawings]

The figure is a sectional view showing an example of TPT obtained by the present invention. DESCRIPTION OF SYMBOLS 1... Insulator substrate, 2... Insulating layer, 3... Date insulating layer, 4... Channel layer, 5... Low resistance amorphous silicon layer, 6... North electrode, 7...・Drain electrode. Patent applicant Oki Electric Industry Co., Ltd. Procedural amendment (voluntary) l Indication of the case 1982 Patent No. 204113 2 Name of the invention Method for manufacturing thin film transnostar 3 Relationship with the case by the person making the amendment Patent application Life Place (
105) 1-7-12-5 Toranomon, Minato-ku, Tokyo
Subject of amendment: “Detailed description of the invention” column in the specification;
6 Contents of amendment 14 The text “[Kate isolation layer 3, channel layer 4, . . . drain electrode 7]” in lines 15 to 17 of page 4 of the specification has been changed as follows. to correct. "Gate insulating layer 4, channel layer 5, low resistance amorphous/licon film 6, source electrode 7, drain electrode 874J 2," in the same book, page 6, lines 5 to 7, "3...gate disconnection" , edge 7...drain electrode.'' should be corrected as follows. 3. Kate electrode layer, 4...ke8-
Insulating layer, 5...Channel layer, 6...Low resistance amorphous 7977 layer, 7...Source electrode, 8...Drain electrode. ”3 Correct the figure as shown in the attached sheet.

Claims (1)

[Claims] 1. A method for manufacturing a thin film transistor, comprising forming a metal layer to serve as a gate electrode on the surface of a substrate, and then selectively forming a gate electrode by oxidizing a portion other than the portion to become the gate electrode.