JPH01183146A - 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] The present invention relates to a semiconductor device having a capacitor.

[Conventional technology]

FIG. 5 is a plan view of a conventional capacitor, and FIG. 6 is a sectional view of FIG. 5. In the figure, a gate oxide film (2) is formed on a part of a semiconductor substrate (1), and a gate electrode (31) is formed on this gate oxide film (21).

Next, ion implantation is performed along the direction of arrow (4). Thereafter, the implanted ions are driven, and since the conventional capacitor was constructed as described above, no diffusion layer is formed under the gate electrode, resulting in an MO8 capacitor. Therefore, the conventional capacitor operates as a capacitor when the gate electrode potential is above the threshold voltage TH, but does not operate as a capacitor when it is below the threshold voltage.

This invention was made to solve the above problems, and the capacitor according to the invention is a capacitor that can operate even when the potential of the gate electrode is lower than the threshold voltage VTR. are arranged at appropriate intervals, and ions can be implanted into the semiconductor substrate through the gap between the gate electrodes.

[Effect]

In the capacitor of this invention, ions implanted through gaps between narrow gate electrodes formed at appropriate intervals are driven and expanded, connecting adjacent diffusion layers and diffusing to the lower surface of the gate electrode. It becomes a capacitor with layers.

〔Example〕

FIG. 1 is a plan view of a capacitor which is an embodiment of the present invention, and FIG. 2 is a sectional view of FIG. 1. In the figure, a gate oxide film (21) is formed on a part of the semiconductor substrate (11,
A narrow gate electrode (61) is placed on this gate oxide film (21).
is formed by folding back at appropriate intervals.

Next, ion implantation is performed along the direction of arrow (41).Then, the implanted ions are driven to the second
A diffusion layer (7) is formed under the gate electrode (61), which spreads in the left and right directions in the figure.

Here, it is preferable that the width of the gate electrode (6) is at most twice the width of the diffusion layer that occurs when driving the implanted ions, but it does not matter if it is wider than that as the same effect can be achieved.

In the above embodiment, the gate electrode (61) was formed in a folded shape, but it may be formed in a comb shape (81) as shown in FIG. are equivalent and produce similar effects. FIG. 4 shows a sectional view of FIG. 3.

〔Effect of the invention〕

As described above, according to the present invention, narrow gate electrodes are formed at appropriate intervals, so ions implanted through the gap between the gate electrodes are driven and spread, and adjacent diffusion layers are connected. Since a capacitor having a diffusion layer is formed on the lower surface of the gate electrode, it can operate as a capacitor even when the potential of the gate electrode is lower than the threshold voltage VTM.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a capacitor according to an embodiment of the present invention, FIG. 2 is a sectional view of FIG. 1, FIG. 3 is a plan view of a capacitor showing another embodiment of the invention, and FIG. FIG. 3 is a sectional view, FIG. 5 is a plan view of a conventional capacitor, and FIG. 6 is a sectional view of FIG. In the figure, (1) is the semiconductor substrate, (2) is the gate oxide film, (41 is the ion implantation), 161 and 161 are the gate electrodes, and (7) is the diffusion layer. In the figure, the same reference numerals are the same. , or a significant portion.

Claims (1)

[Claims] A capacitor with a structure in which a gate oxide film is formed on a part of the semiconductor substrate, a gate electrode is placed on the gate oxide film, ions are implanted, and a diffusion layer is formed by driving the implanted ions. 1. A semiconductor device comprising narrow gate electrodes arranged at intervals and a diffusion layer provided below the gate electrodes.