JPH04106945A - Semiconductor device - Google Patents

Abstract

PURPOSE:To make it possible to obtain a device with minimum characteristic variations and enhance the yield by installing an evaluation device, electrically evaluating the presence of a thin oxide film, and carrying out process control. CONSTITUTION:A first electrode 9 is formed as an evaluation device in the lower part of a semiconductor substrate 1. After the formation of a thin oxide film on the electrode 9, this oxide film is etched and processed. During etching removal of this oxide film, a thin oxide film 8, which can not be completely eliminated, is sandwiched and formed on the electrode 9 as an upper part electrode 10 whose area is smaller than that of the electrode 9. The application of this evaluation device makes it possible to detect the presence of the film 8 and accordingly carry out process control either during process or after the formation of products by applying constant voltage between the electrode 9 and the electrode 10 and measuring the current flowing between the electrode 9 and 10. This construction makes it possible to evaluate the presence of a thin oxide film, which is an etching remainder, obtain a device with minimum characteristic variations by controlling the etching process, and enhance the yield.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor device, and particularly to the structure of a semiconductor device having an evaluation element formed on a semiconductor substrate.

[Conventional technology]

Among conventional semiconductor devices, especially MO3 type semiconductors, LDD structures are often adopted as speeds have increased in recent years. Said L
One feature of the MO3 type semiconductor having the DD structure is that it has a sidewall on the sidewall of the gate electrode. Below, the manufacturing process for forming the sidewall will be explained in the third step.
This will be explained based on FIG. 3(a) to FIG. 3(c).

(2) FIG. 3(a) is a cross-sectional view of the manufacturing process of an MO3 type semiconductor device, in which a gate oxide film 3, an impurity diffusion layer 4, and a gate electrode 5 are formed on a semiconductor substrate 1. Note that 2 in the figure is a pre-element film.

(2) An oxide film 6 is formed on the semiconductor substrate 1 as shown in FIG. 3(b).

(2) The oxide film 6 is anisotropically etched using a reactive ion etching method to form a sidewall 7 on the sidewall of the gate electrode 5.

At this time, as shown in FIG. 3(C), due to variations in the reactive ion etching conditions, a thin oxide layer is formed on the gate electrode 5 and the impurity diffusion layer 4. II8 may remain.

However, when the thin oxide film 8 becomes an ion permeable film during the next ion implantation process, resistance values and the like become a factor of variation. Therefore, in order to obtain an element with little variation, it is necessary to control the presence or absence of the thin oxide film 8.

[Problem to be solved by the invention]

However, in conventional semiconductor devices, there was no method for controlling the presence or absence of the thin oxide film 8.

Therefore, the present invention attempts to solve such problems, and its purpose is to electrically evaluate the presence or absence of the thin oxidation #8 and perform process control.
The goal is to obtain an element with less variation in characteristics.

[Means to solve the problem]

In the semiconductor device of the present invention, a conductive layer is disposed as a first electrode on a semiconductor substrate, an insulating film is formed on the first electrode, and then the insulating film is etched, and further on the upper part: The present invention is characterized in that it has an evaluation element in which a conductive layer having a smaller area than the first electrode is disposed as a second electrode, and that process control of a semiconductor element on the same substrate as the evaluation element can be performed.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a structural sectional view of an evaluation element according to the present invention. A first electrode 9 is formed on the semiconductor substrate 1 at the bottom. After forming an oxide film on the first electrode 9, the oxide film is etched, and the thin oxide film 8 that was not completely removed during the etching removal of the oxide film is sandwiched between the thin oxide films 8 to form the upper electrode. A second electrode 10 having a smaller area than the first electrode is formed on the electrode.

By using the above-mentioned evaluation element, the above-mentioned thin oxide film 8
By applying a constant voltage between the first electrode 9 and the second electrode 10 and measuring the current flowing between the first electrode 9 and the second electrode 10, the presence or absence of But it can be managed.

Next, the evaluation element of the present invention was prepared using MO3 having an LDD structure.
When applied to a type semiconductor device, Fig. 2(a) to
This will be explained based on FIG. 2(d).

FIGS. 2(a) to 2(d) show M having an LDD structure.
O3 type transistor 12 and evaluation element 1 according to the present invention
1 is formed on the same semiconductor substrate 1, and the LD
This figure shows a cross-sectional view of the manufacturing process for forming the sidewall 7, which is one of the features of the D structure.

As shown in FIG. 2(a), the MO3 type transistor 12 is composed of a gate oxide film 3, an impurity diffusion layer 4, and a gate electrode 5 formed on a semiconductor substrate 1. Note that 2 in the figure is an element isolation film. In the same way as when forming the gate electrode 5 on the portion of the evaluation element 11 on the semiconductor substrate l,
A first electrode 9 is formed as a lower electrode on the top of the element isolation film 2 using polycrystalline silicon.

Next, as shown in FIG. 2(b), an oxide film 6 of approximately 3000 to 8000 Å is formed on the top by high temperature vapor phase growth.

Further, by anisotropically etching the oxide film 6 using a reactive ion etching method, a sidewall 7 is formed on the side wall of the gate electrode 5.

Here, since the amount of anisotropic etching is non-uniform, the oxide film 6
may remain on the semiconductor substrate 1 as a thin oxide film 8.

Furthermore, by patterning a thin aluminum film on the thin oxide film 8, a second electrode 10 having a smaller area than the first electrode is formed on the first electrode 9. The structure of the element can be obtained.

By using the evaluation element 11, a constant voltage is applied between the first electrode 9 and the second electrode 10, and the current flowing between the first electrode 9 and the second electrode 10 is measured. The presence or absence of the thin oxide film 8 can be evaluated.

In the above embodiment, the thin oxide film 8 is the etching residue left after forming the sidewall 7 in an MO3 transistor. However, instead of this, only a part of the oxide film is dry-etched or wet-etched. It can also be applied as an element for evaluation when the oxide film remains after processing.

Furthermore, the present invention can also be applied when the oxide film to be etched is an insulating film other than an oxide film.

〔Effect of the invention〕

As described above, by using the evaluation element of the present invention in which a thin oxide film is sandwiched between the upper electrode and the lower electrode, the presence or absence of a thin oxide film remaining after etching can be evaluated. Furthermore, by controlling the etching process described above, it is possible to obtain a semiconductor device with less variation in characteristics, thereby making it possible to obtain a semiconductor device with a high yield.

[Brief explanation of drawings]

FIG. 1 is a structural sectional view of an evaluation element according to the present invention. FIGS. 2(a) to 2(d) are manufacturing cross-sectional views showing the structure of an example in which the evaluation element of the present invention is applied to an MO3 strike transistor having an LDD structure. FIGS. 3(a) to 3(c) are manufacturing cross-sectional views showing the structure of a conventional semiconductor device. 1...Semiconductor substrate 2...Element M film 3...Gate oxide film 4...Impurity diffusion layer 5...Gate electrode 6...Oxide film 7...Side wall 8...Thin oxide Membrane 9...First electrode 10...Second electrode 11...Evaluation element 12...MO3 type transistor or above Applicant: Seiko Epson Corporation Agent Patent attorney: Kizobe Suzuki and one other person Sumire 1 palm of the hand 21e

Claims (1)

[Claims] A conductive layer is disposed as a first electrode on a semiconductor substrate, an insulating film is formed on the first electrode, and then the insulating film is etched, and a second electrode is formed on the semiconductor substrate from the first electrode. 1. A semiconductor device comprising an evaluation element provided with a conductive layer having a small area, and capable of performing process control of a semiconductor element on the same substrate as the evaluation element.