JPH02199863A - Semiconductor device - Google Patents

Abstract

PURPOSE:To always detect a substrate potential correctly and to control a feedback without delay by a method wherein a detecting part of a substrate potential detector is installed near a maximum leakage-current source of a potential change in a semiconductor substrate. CONSTITUTION:An FET Q1 used as a maximum leakage-current source is formed in an FET substrate 1. A detecting part (detecting terminal) of an SD 2 is installed near the FET Q1. The SD 2 detects a substrate potential VSD near the FET Q1, outputs a feedback signal FB to a substrate-potential generation circuit (BBG) 3 and adjusts a potential-output capacity of the BBG 3. The BBG 3 supplies a substrate potential VBB to the FET substrate 1 on the basis of the feedback signal PB. The FET Q1 generates a substrate leakage current by means of a switching operation and changes the substrate potential near the FET Q1; however, since the SD 2 has detected the potential near the FET Q1 in advance, it can quickly change a capacity of the BBG 3, and the substrate potential is stabilized.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a semiconductor device in which a field effect transistor (hereinafter abbreviated as FET) is formed, and particularly relates to a semiconductor device equipped with means for stabilizing the substrate potential thereof. .

[Prior Art] Conventionally, in a semiconductor device using an FET, a substrate potential is supplied from a power source different from a circuit power source. However, recently, in order to meet the demand for a single power supply, a substrate potential generation circuit (hereinafter abbreviated as BBG) has been used to generate a substrate power source from a circuit power source.

FIG. 4 is a diagram showing a schematic configuration of a conventional semiconductor device of this type that uses a single power source.

The potential VSD of the FET substrate 1 is detected by a substrate potential detector (hereinafter referred to as
(abbreviated as SD) 2, and its detection output is BB
By feeding back to G3, BBG3 to F
The substrate potential VBB supplied to the ET substrate 1 is controlled.

According to this circuit, when the substrate potential fluctuates due to the influence of leakage current of the FET, for example, the potential fluctuation is controlled by feedback control, and the substrate potential can always be maintained at an appropriate substrate potential.

[Problems to be Solved by the Invention] However, the substrate potential is not necessarily -like over the entire area of the substrate.
, and potential distributions as shown by the equipotential lines in (4) are generated.

The mechanism by which substrate potential distribution occurs will be explained below.

In Fig. 4, FETQl is an N-channel MO9FET.
, and assuming that the FET substrate 1 is a P-type semiconductor, F
When E T Q 7 switches, a substrate leakage current IL flows from the channel into the substrate, changing the nearby substrate potential. However, this potential is usually immediately averaged to the surrounding substrate potential.

Like the output FET in S i LS I, for example, the gate length is 3 μm and the width is 120. As um and the FET size increase, the leakage potential also increases, and due to the layer resistance of the substrate, the substrate potential is not quickly averaged, and in the figure, Vl > V2 > V3 > V4 ＞
A potential distribution as shown by Vso≧VBB occurs.

However, in SD2, the detection section is provided near the substrate potential supply section of BBG3, and the potential is close to VBB (V5D).
Therefore, there are problems in that the detection of the above-mentioned abnormal potential is delayed, or an erroneous potential is detected, resulting in inappropriate feedback.

For this reason, the substrate potential near FETQ deviates from the desired value, and FETQ7 or the FET near it deviates from its expected value.
There was a problem that the system would malfunction.

The present invention has been made in view of such problems, and includes:
It is an object of the present invention to provide a semiconductor device that can always correctly detect a substrate potential and perform appropriate feedback control without delay.

[Means for Solving the Problems] A semiconductor device according to the present invention includes a substrate potential detector that detects the potential of a semiconductor substrate, and controls the potential of the semiconductor substrate based on a detection output from the substrate potential detector. In the semiconductor device including a substrate potential generation circuit, the substrate potential detector is characterized in that a detection section is installed at least near the largest leakage current source among the leakage current sources in the semiconductor substrate. .

[Function] In the present invention, since the detection part of the substrate potential detector is installed in the semiconductor substrate at least near the maximum leakage current source where the substrate potential changes significantly, it is possible to reliably detect changes in the substrate potential. can. Therefore, potential detection is not delayed, and a feedback signal can be transmitted quickly.

[Embodiments] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a diagram showing a schematic configuration of a semiconductor device according to a first embodiment of the present invention.

The FET board 1 has a FETQl which is the maximum leakage current source.
is formed. A detection section (detection terminal) of SD2 is installed near this FETQl. SD2 is FET
It detects the substrate potential ■sD near QI, outputs a feedback signal FB to BBG3, and adjusts the potential output capability of BBG3'. BBG3 supplies substrate potential VBB to FET substrate 1 based on feedback signal FB.

FETQ1 generates a substrate leakage current through switching and changes the substrate potential near FETQ, but SD2 detects the potential near FETQ in advance, so it quickly changes the ability of BBG3. The substrate potential can be stabilized.

Note that the position where SD2 detects the substrate potential is the general St.
- For memory devices, preferably within about 700 μm from the leak source. This is because in past general memories, malfunctions occurred in FETs within 7°0 μm from the substrate leak source, and the error was approximately 8°.

Based on the empirical rule that there was no effect on FET operation in μm.

FIG. 2 is a diagram showing a second embodiment of the present invention.

The number of FETs that serve as substrate leakage current sources is not necessarily one as in the first embodiment.In this second embodiment, when there are two such FETs, each FET is T
SD and 2a near Q 2 and Q s, respectively.

A 5D22b detection unit is installed.

In this way, when there are a plurality of FETs that can be a leak source, it is possible to enhance the effects of the present invention by arranging the same number of SD detection sections near each FET.

However, in this case, in order to prevent the chip area from increasing too much due to the installation of the SD, the installation of the SD should be done especially on F with a large leakage current.
It is preferable that the number is limited to ET and that the number is about 10.

FIG. 3 is a diagram showing a third embodiment of the present invention.

Substrate leakage current sources are not limited to transistors. That is, as shown in FIG. 3, a substrate leakage current also accompanies the charging and discharging of a large capacitance C formed by a MOSFET in the FET substrate 1. Therefore, the leak source FETQ6
In addition, FETQ4 and Q5 that constitute such an element
It is effective to install a 5DC2C detection section also near the.

In the above embodiment, capacitance was cited as a leak source, but it is clear that an element having a diffusion layer (substrate) as a component can be considered as a leak source. Therefore, it is clear that the effects of the present invention can be obtained by installing a substrate potential detector near such an element.

[Effects of the Invention] As explained above, in the present invention, substrate potential fluctuations can be quickly fed back to the substrate potential generation circuit by installing the detection part of the substrate potential detector near the substrate leakage current source. , it is possible to stabilize the substrate potential,
Stable circuit operation can be obtained.

[Brief explanation of the drawing]

1 is a schematic block diagram of a semiconductor device according to a first embodiment of the present invention, FIG. 2 is a schematic block diagram of a semiconductor device according to a second embodiment of the present invention, and FIG. 3 is a schematic block diagram of a semiconductor device according to a second embodiment of the present invention. FIG. 4 is a schematic block diagram of a conventional semiconductor device. 1, FET substrate, 2a, 2b, 2c; substrate potential detector,
3; Substrate potential generation circuit, Q1 to Q7; FF, T, C,
capacitance

Claims (1)

[Claims] (1) A substrate potential detector that detects the potential of a semiconductor substrate;
In the semiconductor device including a substrate potential generation circuit that controls the potential of the semiconductor substrate based on a detection output from the substrate potential detector, the substrate potential detector has a detection section that detects at least a leakage current in the semiconductor substrate. A semiconductor device characterized in that the semiconductor device is installed near the largest leakage current source among the sources.