JPH06302825A - Semiconductor device - Google Patents

Abstract

(57) [Abstract] [Purpose] To obtain a semiconductor device having a structure that realizes high integration by scale down. A groove 7 is formed on the surface of a semiconductor substrate 1, and a charge transfer channel region 5 having a charge transfer channel length corresponding to the depth of the groove 7 is formed on a sidewall inside the groove 7 via an insulating film 2.
In addition to forming a, a gate electrode 3a as an upper electrode was formed on the charge transfer channel region 5a via the gate insulating film 4 inside the groove 7 and on the surface of the semiconductor substrate 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly to a thin film transistor device applicable to a scaled down integrated circuit.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram showing a conventional thin film transistor device having a lower electrode as a gate electrode. In the figure, 1 is a semiconductor substrate, and 2 is a C on the surface of the semiconductor substrate 1.
An insulating film 3 deposited by a VD process or the like is a lower electrode formed of polysilicon or the like and serving as a gate electrode. Polysilicon or the like is formed on the lower electrode 3 via a gate insulating film 4 such as a thermal oxide film. The upper electrode is formed by. That is, as the upper electrode, the charge transfer channel region 5 is formed by a mask or the like, and the source and drain regions 6 are formed.
Is formed.

Next, the operating principle of the thin film transistor structure shown in FIG. 3 will be described. Source and drain region 6
The drain voltage V _D is applied to one of the two, and the other source and drain region 6 is kept grounded. Here, when a gate voltage V _G equal to or higher than the threshold voltage is applied to the gate electrode 3, minority carriers flow in the charge transfer channel region 5,
The thin film transistor has a switching function.

[0004]

By the way, in order to reduce the scale of the thin film transistor device, it is required to shorten the channel.
Because of the planar structure as shown in (1), in an integrated circuit which is being scaled down, the deterioration of transistor characteristics and the deterioration of reliability due to the shortening of channel are major problems.

The present invention has been made in order to solve the above-mentioned problems, and does not deteriorate the transistor characteristics and reliability even when adopted in a scale-down super-integrated circuit and reduces the size of the thin film transistor. An object is to obtain a semiconductor device that can be manufactured.

[0006]

According to a first aspect of the present invention, there is provided a semiconductor device having an upper electrode formed on a substrate as a gate electrode and a lower electrode as a charge transfer channel region and source and drain regions. In the above step, a groove is formed on the surface of the substrate, a charge transfer channel region having a charge transfer channel length corresponding to the depth of the groove is formed on a sidewall inside the groove through an insulating film, and the charge transfer is performed. It is characterized in that the above-mentioned gate electrode is formed inside the groove and on the substrate surface via the gate insulating film on the channel region.

A semiconductor device according to a second aspect is a semiconductor device in which a lower electrode formed on a substrate is a gate electrode, and an upper electrode is a charge transfer channel region and source and drain regions, and the substrate surface is covered. The gate electrode is formed vertically on the insulating film, and the charge transfer channel region and the source and drain regions are formed on the surface of the insulating film and the gate electrode via the gate insulating film. It is a thing.

[0008]

In the semiconductor device according to the first aspect of the present invention, the charge transfer channel region having the charge transfer channel length according to the depth of the groove is formed on the side wall inside the groove formed on the surface of the substrate through the insulating film. And forming a gate electrode inside the groove on the charge transfer channel region through the gate insulating film and on the surface of the substrate to form the charge transfer channel in a concave structure, thereby reducing the size of the thin film transistor. However, since the charge transfer channel is not shortened,
It is possible to reduce deterioration of transistor characteristics and reliability.

According to another aspect of the semiconductor device of the present invention, the gate electrode is formed vertically on the insulating film covering the surface of the substrate, and the gate insulating film is formed on the surface of the insulating film and the gate electrode. By forming the charge transfer channel region and the source and drain regions and forming the charge transfer channel into a convex structure, the charge transfer channel is not shortened even if the size of the thin film transistor is reduced. It becomes possible to reduce deterioration.

[0010]

【Example】

Example 1. Hereinafter, a first embodiment corresponding to claim 1 of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram illustrating a thin film transistor device having a concave electrode cross-sectional structure according to a first embodiment. In FIG. 1, the same parts as those in FIG.
1 is a semiconductor substrate, 2 is a CVD on the surface of the semiconductor substrate 1.
It is an insulating film deposited by a process or the like. Further, 7 is a new component, which is a groove formed on the surface of the semiconductor substrate 1 by anisotropic etching or the like.

After the insulating film 2 is formed on the surface of the semiconductor substrate 1 provided with the groove 7 by a CVD process or the like, a lower electrode portion is formed by polysilicon or the like on the inside of the groove and on the surface of the substrate. A charge transfer channel region 5a is formed in the lower electrode portion on the inner wall of the groove by ion implantation or the like. Then, the gate electrode 3a as an upper electrode is formed inside and on the surface of the groove through the gate insulating film 4. Further, thereafter, the source and drain regions 6a as the lower electrodes are formed in the lower electrode portion on the surface of the substrate by ion implantation or the like, whereby a thin film transistor device having a concave shape can be manufactured.

Therefore, as described above, according to the first embodiment, by forming the thin film transistor structure in which the charge transfer channel region 5a is provided inside the concave groove 7, the charge transfer channel is formed by a value corresponding to the depth of the concave groove 7. Since the length is secured, it is possible to reduce the thin film transistor size without shortening the charge transfer channel length, and therefore, it is possible to scale down without reducing the thin film transistor characteristics and reliability, This is extremely effective for high integration.

Moreover, since the upper electrode is the gate electrode 3a, the source and drain regions 6a can be formed by self-alignment. Further, when forming the lower electrode, since the grains of polysilicon have a characteristic of growing vertically, as described above, by forming the charge transfer channel region 5a in a concave shape, the adverse effect of charge transfer due to the grains is also reduced. be able to.

Example 2. Next, a second embodiment corresponding to claim 2 of the present invention will be described with reference to the drawings. Second Embodiment
FIG. 3 is a configuration diagram showing a thin film transistor device having a convex electrode cross-sectional structure according to FIG. 2, the same parts as those in FIG. 3 are designated by the same reference numerals, 1 is a semiconductor substrate, and 2 is an insulating film deposited on the surface of the semiconductor substrate 1 by a CVD process or the like.

As a new component, 3a is a gate electrode 3b as a lower electrode vertically formed on the insulating film 2 covering the surface of the semiconductor substrate 1, and the gate electrode 3b is the insulating layer. It can be formed by further forming a thick insulating film (not shown) on the film 2, forming a hole at a position corresponding to an electrode, forming an electrode portion here, and then removing the thick insulating film (not shown). Is.

Further, an upper electrode made of polysilicon or the like is formed on the surfaces of the insulating film 2 and the gate electrode 3b via the gate insulating film 4, and a charge transfer channel region 5b as an upper electrode is formed by ion implantation or the like. By forming the source and drain regions 6b, a convex thin film transistor device can be manufactured.

Therefore, as described above, according to the second embodiment, the charge transfer channel region is formed so as to cover the gate electrode 3b as a lower electrode vertically formed on the insulating film 2 covering the surface of the semiconductor substrate 1. By forming 5b in a convex shape to form a convex thin film transistor structure, the charge transfer channel length is ensured by a value corresponding to the length of the convex portion.
It is possible to reduce the size of the thin film transistor without shortening the charge transfer channel length. Therefore, it is possible to scale down without lowering the thin film transistor characteristics and reliability, which is extremely effective for high integration. Will be things.

Further, when forming the upper electrode, since the grains of polysilicon have a characteristic of growing vertically, as described above, by forming the charge transfer channel region 5a in a convex shape, the charge transfer by the grains can be performed. Adverse effects can also be reduced.

[0019]

As described above, according to the first aspect of the present invention, the charge transfer channel length corresponding to the depth of the concave groove is provided on the side wall inside the concave groove formed on the substrate surface through the insulating film. By forming the charge transfer channel region and forming a gate electrode inside the groove and the substrate surface on the charge transfer channel region through the gate insulating film to form the charge transfer channel in a concave structure, the size of the thin film transistor can be reduced. Since the charge transfer channel is not shortened even if is reduced, it is possible to avoid deterioration of transistor characteristics and reliability, which is extremely effective for realizing a highly integrated circuit. Further, by making the charge transfer channel concave, the effect of reducing the adverse effect of charge transfer due to grains can be obtained.

According to the semiconductor device of the second aspect, the gate electrode is formed vertically on the insulating film covering the surface of the substrate, and the gate insulating film is formed on the surface of the insulating film and the gate electrode. The charge transfer channel region and the source and drain regions are formed by forming the charge transfer channel into a convex structure to prevent the charge transfer channel from shortening even if the thin film transistor size is reduced. Can be avoided, which is extremely effective in realizing a highly integrated circuit. Further, by making the charge transfer channel convex, an effect of reducing the adverse effect of charge transfer due to grains can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a concave thin film transistor structure according to Example 1 corresponding to claim 1 of the present invention.

FIG. 2 is a sectional view showing an example of a convex thin film transistor structure according to Example 2 corresponding to claim 2 of the present invention.

FIG. 3 is a cross-sectional view showing a conventional thin film transistor structure.

[Explanation of symbols]

 3a gate electrode (upper electrode) 5a charge transfer channel region (lower electrode) 6a source and drain region (lower electrode) 7 groove 3b gate electrode (lower electrode) 5b charge transfer channel region (upper electrode) 6b source and drain region ( (Upper electrode)

Claims (2)

[Claims] 1. A semiconductor device having an upper electrode formed on a substrate as a gate electrode and a lower electrode formed as a charge transfer channel region and source and drain regions, wherein a groove is formed on the surface of the substrate, and the inside of the groove is formed. A charge transfer channel region having a charge transfer channel length corresponding to the depth of the groove is formed on the side wall of the groove, and the inside of the groove and the substrate surface are formed on the charge transfer channel region via the gate insulating film. A semiconductor device having the above-mentioned gate electrode formed thereon. 2. In a semiconductor device having a lower electrode formed on a substrate as a gate electrode and an upper electrode as a charge transfer channel region and source and drain regions, the gate is vertically elongated on an insulating film covering the surface of the substrate. A semiconductor device, wherein an electrode is formed, and the charge transfer channel region and the source and drain regions are formed on the surfaces of the insulating film and the gate electrode via a gate insulating film.