JPS58225653A - Semiconductor device - Google Patents

Abstract

PURPOSE:To reduce influence of polarization due to phosphorus and obtain a device with less fluctuation of threshold value by stacking an oxide film including phosphorus on an oxide film not including impurity. CONSTITUTION:A non-volatile memory device is formed by the conventional method, and an oxide film 10 including phosphorus in the thickness of about 2,000Angstrom is stacked on an oxide film 9 not including impurity in the thickness of about 6,000Angstrom . Therefore, in the case of a non-volatile memory device in the double electrode structure, the film 9 exists even when the phosphorus within the film 10 is poralized, electric field intensity is weakened due to film thickness and thereby influence of electric field due to poralization is reduced. Accordingly, fluctuation of threshold voltage of the element itself can be reduced almost to zero, thereby stabilizing the function and improviding performance of semiconductor device.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor device, and particularly to an improvement in an interlayer insulating film that separates an element portion from a wiring portion.

As a conventional semiconductor device, a schematic configuration of a nonvolatile memory device having a double electrode structure tube is shown in FIG. In FIG. 1, (1) C is a thick field oxide film for isolation between elements on the semiconductor substrate, (2) is a source,
a drain diffusion layer, (3) a first gate oxide film formed on the substrate between both diffusion layers, (4) a first polycrystalline silicon layer on this oxide film and serving as a floating gate, (5) it ,
A second gate oxide film (6
) is the second polycrystalline silicon layer on this oxide film and serves as a control electrode, (1) is a thin oxide film covering these, (8
) is an oxide film containing phosphorus produced by vapor phase growth as an interlayer insulating film.0 In this conventional structure, the first polycrystalline silicon layer (4)
MO as a memory element by injecting electrons into
The threshold voltage of the 8-type transistor is changed, and this difference in threshold voltage is used to store data. In this case, the oxide film (8) as an interlayer insulating film insulates the wiring portion (not shown) formed on the element, and this oxide film (8) is produced by vapor phase growth. At this stage, the surface condition is also uneven according to the undulations of the element surface on the substrate, but this phosphorous-containing oxide film (8) undergoes a high-temperature heat treatment in an Hz/Ot atmosphere, resulting in a so-called The entire surface is flattened by the drooping, thereby preventing wire breakage due to surface undulations of the wiring formed on top of the aluminum or the like.

However, when such an interlayer insulating film is applied to a nonvolatile memory device having a double electrode structure, there is a problem in that the threshold voltage of the memory element varies due to the polarization of phosphorus in the phosphorus-containing oxide film.

In view of these conventional drawbacks, the present invention provides an interlayer insulating film with a two-layer structure consisting of a lower oxide film containing no impurities and an upper oxide film containing phosphorus, thereby reducing the influence of polarization caused by phosphorus. The present invention provides a semiconductor device with no variation in voltage value.

Hereinafter, one embodiment of the semiconductor device according to the present invention will be described.
This will be explained with reference to FIG.

This embodiment is applied to a non-volatile memory device having a double electrode structure similar to the conventional example, and is shown in FIG.
The names indicate the same or equivalent parts, and in this example, instead of using the oxide film (8) as the interlayer insulating film, the first layer at the bottom is made of silane (Sic&) gas and oxygen (Oz).
) An oxide film (9) with a thickness of about 600 OA was produced by a vapor phase growth method at a temperature T = 430° C. in a gas atmosphere,
The second layer on top of the silane (5IH4) gas, oxygen (O
x) A two-layer oxide film (10) with a thickness of about 200 OA was produced in a similar manner by vapor phase growth at a temperature of T-430°C in a phosphine (PHs) gas atmosphere. be.

Therefore, in this example, the first layer oxide film (9), which does not contain impurities and has a thickness of 6000 Å, is formed by vapor phase epitaxy, and the phosphorus oxide film has a thickness of 2000 Å. This 11. When applied to a nonvolatile memory device with a double electrode structure, even if phosphorus in the second layer oxide film (10) is polarized, the first layer oxide film (9) containing no impurities
), the electric field strength is weakened because the membrane (9) is relatively Jv, which reduces the influence of the electric field due to polarization, and by working on this, the threshold voltage of the element itself is reduced. There is almost no variation at all, 1, -c, = cat -c' @ 6°a. 1. Although the above embodiment has been described for the case where it is applied to a non-volatile memory device having a double electrode structure, it goes without saying that it can also be applied to a memory device in which charge is accumulated using a floating gate or some kind of trap. In addition to memory devices that utilize such charge accumulation, the present invention can be applied to any type of semiconductor memory device, and the effect of the two-layer insulating film can be expected.

As described in detail above, the present invention provides a semiconductor device having an interlayer insulating film.
The two-layer structure consists of an oxide film that does not contain impurities, and an oxide film that contains phosphorus as the second upper layer [2] The structure is simple and easy to implement because it eliminates the influence of phosphorus polarization on the device function. Despite this, it greatly contributes to the stability of device functions and improvement of characteristics.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the general configuration of a conventional nonvolatile memory device with a double electrode structure, and FIG. 2 is an overview of an embodiment of the present invention applied to a nonvolatile memory device with a double electrode structure. FIG. 3 is a sectional view showing the configuration. (1)...Field oxide film, (2)...Source and drain diffusion layer, (3)...First gate oxide film, (4)...First polycrystalline silicon layer , (5)...
・Second gate oxide film, (6)...second polycrystalline silicon y4, (7)...oxide film, (9) and (10)・
...The first layer does not contain impurities, and the second layer contains phosphorus.
Layer oxide film (interlayer insulation film). Agent Shin Kuzuno −

Claims (1)

[Claims] In a semiconductor device having a structure in which an element part and a wiring part are separated by a glabellar insulating layer produced by vapor phase growth, the interlayer insulating layer has a two-layer structure, and the lower first layer is an oxide film containing no impurities, and an oxide film containing no impurities. A semiconductor device characterized in that the upper second layer is made of an oxide film containing phosphorus.