JPS639143A - Semiconductor device - Google Patents

Abstract

PURPOSE:To prevent the generation of an erroneous operation even when alpha-rays intrude a semiconductor chip by a method wherein the diffusion layer part which constitutes a transistor is divided into a plurality of parts. CONSTITUTION:The diffusion layer part of a transistor, constituting a semicon ductor device may be erroneously operated by the electric charge generated when alpha-rays 6 are injected into a semiconductor chip, is divided into a plurality of parts 131 and 132. For example, an MOSFET is constituted by providing diffusion layers 131 and 132 (a drain electrode and a source electrode are consti tuted respectively) formed by dividing a diffusion layer into two parts, a gate electrode 12, an oxide film 14 and the like on the surface of a semiconductor substrate 15. As a result, the area of each of the diffusion layers 131 and 132 is made smaller than the area of the diffusion layer of the device heretofore in use, and the distance l2 where the alpha-rays 6 passes a depletion layer 162 can be made short when compared with the device heretofore in use. According ly, the quantity of charge catching is reduced from that of the conventional device, the potential fall of the diffusion layer is small, and an erroneous opera tion of the semiconductor device can be prevented.

Description

Detailed Description of the Invention (Summary) The present invention provides a method for preventing malfunctions in semiconductor devices such as MOSFETs due to a large amount of captured charge generated when α rays emitted from electrode materials, package materials, etc. enter the semiconductor device. In order to solve the problem that occurs, the diffusion layer that makes up one transistor is divided into multiple parts to reduce the amount of charge captured by each diffusion layer, thereby preventing malfunction even if α rays enter. It is designed to prevent this from happening.

[Industrial application field]

The present invention relates to semiconductor devices, and particularly to semiconductor devices such as MOSFETs. When a MOSFET is used, for example, as a sense amplifier for a D-RAM (dynamic RAM), malfunctions occur if the amount of charge trapped 1ffi is large. Therefore,
There is a need for a semiconductor device that captures a small amount of charge and can always operate normally.

[Conventional technology]

FIGS. 4(A) and 4(B) respectively show a plan view of an example of a conventional semiconductor device and a new view taken along the line BB. In the figure, 1 is a gate electrode, 2 is a diffusion layer (constituting a drain electrode and a source electrode), 3 is an oxide film, 4 is a substrate, and 5 is a depletion layer. When the potential is the same as that of light, a depletion layer 5 is formed, and when α rays enter there, holes and electrons are generated. By the way, in general, electrode materials that constitute semiconductor devices! ! i! Wire rod, continuous covering material.

α rays are emitted from coating materials, packaging materials, sealing materials, etc., but as shown in FIG. 4 (8), when these α rays 6 enter the semiconductor chip, the holes generated in the depletion layer 5 are Electrons generated in the depletion layer 5 are drawn to the diffusion layer 2 while being emitted to the substrate along the electric field.

The potential of the diffusion layer 2 decreases due to the capture of this charge in the diffusion layer 2. In this case, the longer the distance 21 that the α ray 6 passes through the depletion layer 5, the more the trapped charge hangs, and the potential drop of the diffusion layer 2 decreases. growing.

[Problem that the invention seeks to solve]

5(A) and 5(B) show a circuit diagram and a plan view thereof when the conventional semiconductor device shown in FIG. 4 is applied to a sense amplifier of a D-RAM. In the figure, 7+, 72, and 73 are sense amplifiers; for example, the sense amplifier 71 is an N-channel transistor 3a.

8b and P channel transistors 8c and 8d. 9+, 92.93 are cell arrays, which are composed of a transistor 1o and a capacitor 11.

Here, an example of a conventional circuit in a normal state (Fig. 5)
Explain the operation. As shown in FIG. 3, the transistor 10 of the cell array 91 is activated by the control signal from the word aWL.
is turned on at time t1, and the information stored in the capacitor 11 appears on the bit line 8L. Figure 3 shows the conde
This is an example where a high level of charge was stored in the sensor 11.
The level of the bit line BL is rising. Next, the control line P
The sense amplifier 7I is controlled by control signals from SA and NSA.
starts sensing operation at time t2, and the levels of bit line BL and bit line 8L are amplified to output H level and L level information, respectively.

Next, the operation shown in FIG. 5 when α rays enter and cause malfunction will be explained. When α rays enter, for example, the diffusion M2 of the drain electrode between times t1 and t3, electrons are captured and the potential of the diffusion layer 2 is lowered as described above. Then, as shown in FIG. 6, before the Ili control signal is supplied from the control lines PSA and NSA, from time t3 the output levels of the bit line 8L and bit line -Go become the opposite level from the normal state.
There was a problem in that information was output at a level opposite to the original level. This is not a particular problem if the number of electrons generated by the alpha rays is captured is small, but if the number of electrons is large, the above-mentioned malfunction occurs.

[Means for solving problems]

As shown in FIG. 1, the semiconductor device according to the present invention has α-ray 6
A plurality of diffusion layer portions (131) of one transistor that constitute a circuit cause malfunction due to charges generated when particles enter a semiconductor chip.

132).

[Effect]

Since the diffusion layer part constituting one transistor is divided into a plurality of parts, the area for each of the diffusion layers 131 and 132 is smaller than that of the conventional one, and the distance 22 that the α ray 6 passes through the depletion layer 162 is It is shorter than the conventional one and has a charge trapping capacity of 1f.
Since fi is smaller than that of the conventional type, malfunction does not occur.

〔Example〕

FIGS. 1(A) and 1(B) respectively show a plan view and a sectional view taken along the line B--B of an embodiment of the semiconductor device of the present invention.

In the figure, 12 is a gate electrode, 131° and 132 are diffusion layers (
Each of them constitutes a drain lff1 and a source electrode), which are obtained by dividing the original one diffusion layer 2 shown in FIG. 4 into two, for example, and form the main part of the present invention. 14 is an oxide film, 1
5 is a substrate, and 161° and 162 are depletion layers.

In this way, since the expanded rl1 layer portion constituting one transistor is divided into 'a' parts, the area for each of the diffusion layers 131 and 132 is the same as that of the conventional device shown in FIG.
This is the distance that α rays 6 pass through the depletion layer 162! ! , 2 is the distance of the conventional device 2+
It is shorter than . Therefore, there are fewer charge trapping recesses than in conventional devices, and the potential drop in the diffusion layer is small, so malfunctions do not occur.

2(A) and 2(B) show a circuit diagram and a plan view thereof when the semiconductor device according to the present invention shown in FIG. 1 is applied to a D-LRAM sense amplifier; The same components are given the same numbers.

In the same figure, 171', 172, and 173 are sense amplifiers,
For example, the sense amplifier 171 includes an N-channel transistor 18 consisting of transistor sections 18a (diffusion layer 131) and 18b<diffusion layer 132), an N-channel transistor 19 consisting of transistor sections 19a (diffusion layer 131) and 19b (diffusion ff113z), and a transistor section. 20a
, 20b, and a P-channel transistor 21 including transistor parts 21a and 21b.

Here, as shown in FIG. 3, substantially similar to the conventional device, the transistors of the cell array 91 are turned on at time t1' by a control signal from the word line WL, and then
, the sense amplifier 17+ starts sensing operation at time t2 in response to a control signal from the NSA, and the levels of the bit lines BL and BL are amplified to output H level and L level information, respectively. Here, as mentioned above, even if alpha rays enter, the potential drop in the diffusion layer is smaller than in conventional devices, so information at a level opposite to the original level is output as in conventional devices. No malfunction will occur.

In this case, it is generally considered that one alpha ray is emitted every several tens of hours, so even if two diffusion layers (131, 132) are provided as in this example, the charge trapping for one of them is If the amount is small, the above-described 7A operation can be prevented when applied to a D-RAM that operates in a very short time compared to the emission interval of α rays.

Note that, as in the embodiment shown in FIGS. 1A and 1B, both the source electrode S and the drain electrode are covered with a diffusion layer
However, in particular, only the diffusion layer (train electrode) that causes malfunction of the circuit due to the charge generated by the injection of α rays 6 is provided as the diffusion layer 131.1.
32 may be provided independently, and the other diffusion layer (source electrode) may be provided not independently.

〔Effect of the invention〕

According to the present invention, since the diffusion layer portion constituting one transistor is divided into a plurality of parts, the distance that α rays pass through the depletion layer is shorter than that of the conventional method, and thus α When a line enters a semiconductor chip, charge trapping 1ffi is smaller than in the conventional case, and the potential drop in the diffusion layer is small. It has the advantage of not causing serious malfunctions and improving operational reliability.

[Brief explanation of the drawing]

FIG. 1 is a plan view and a sectional view of an embodiment of the device of the present invention, FIG. 2 is a circuit diagram and a plan view of the device of the present invention applied to a D-RAM sense amplifier, and FIG. 3 is a D-RAM sense amplifier. Fig. 4 is a plan view and a cross-sectional view of an example of a conventional device; Fig. 5 is a circuit diagram and plan view when the conventional device is applied to a D-RAM sense amplifier; The figure is an operational characteristic diagram when the D-RAM malfunctions. In the figure, 6 is the alpha ray, 9+, 92.93 is the cell array, 12 is the gate electrode, 131.132 is the diffusion layer, 14 is the oxide film, 15 is the substrate, 161.162 is the depletion layer, 17+, 172.173 is sense amplifier, 18.19
, 20.21 are transistors, 18a, 18b, 19a
, 19b, 20a. 20b, 21a, and 21b are transistor parts, D is a drain electrode, and S is a source electrode. Figure 1 (A) Figure 2 Figure 4 Figure 5 (A)

Claims (1)

[Claims] In a semiconductor device where the electric charge generated when α-ray (6) particles are injected into a semiconductor chip may cause malfunction, the diffusion layer portion of one transistor constituting the semiconductor device is divided into multiple pieces (13_1, 13_2). What is claimed is: 1. A semiconductor device comprising: