JPH0235715A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To form an impurity layer in the deep part of a substrate without decreasing the threshold value of impurity concentration, and eliminate electric adverse influence caused by secondary defects, by arranging an ion-implated layer of atom whose conductivity type is not determined, at a position shallower than an ion implanted layer of desired impurity, and making said layer reach a damage layer in a substrate and the substrate surface. CONSTITUTION:By ion-implanting impurity of desired conductivity type in a silicon substrate 1, a desired impurity layer 12 is formed. By using implantation energy wherein impurity peak position in an impurity implanted region is shallower than ion implantation peak, and a layer without post-implantation damage does not remain between the ion-implanted layer 12 and an ion implanted layer 14 of atom whose conductivity type is not determined, ion implantation of atom whose conductivity type is not determined, e.g., Si, Ge, N, Ar, etc., is performed, and newly a damage layer 14 is formed by ion implantation. The ion implantation of these atoms is executed until the damage layer caused by ion implantation reaches the substrate surface. Next, heat treatment is applied, and the damage caused by the activation of impurity of desired conductivity type and ion implantation is recovered by solid growth, only from the substrate side.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention can be applied to a semiconductor substrate without causing defects in the deep part of the semiconductor substrate (
, relates to a method for manufacturing a semiconductor device in which an impurity layer is formed.

BACKGROUND OF THE INVENTION Conventionally, when ions are implanted deep into a semiconductor substrate with high energy, secondary defects occur if the ion implantation amount has an impurity concentration above a certain threshold, and complete recovery is difficult even with heat treatment. Defects that occur when ion implantation is performed at high energy include, for example, [Nuclear Instruments & Methods Inphysics]
Research (Nucl, In5t, and Mater
ials Phys, Res, B21 P438~
P446 (1987))). FIG. 3a shows a method for manufacturing a semiconductor device using this conventional ion implantation method, in which an impurity layer 32 is formed in a silicon substrate 31.
was formed. When the impurity layer 32 is formed in this way, a layer 33 with implantation damage is formed at almost the same position as the impurity layer 32, as shown in FIG. 34 and 3
5 is known to be formed. Furthermore, the substrate 31
Heat treatment is performed to activate the implanted impurities and recover the implantation damage. The implantation damage in the substrate crystal caused by this heat treatment process is recovered by a solid phase growth reaction from the surface side perfect crystal layer 34 and the substrate side perfect crystal layer 35. As a result, damage caused by ion implantation is confined within the impurity phase and a secondary defect layer 36 is generated (Fig. 3c).
).

As mentioned above, when ion implantation is performed at high energy to form an impurity layer deep into the semiconductor substrate, unlike when ion implantation is performed at low energy, in-phase growth occurs from both the surface side and the substrate side, which causes defects. It gets trapped inside.

Problems to be Solved by the Invention However, in the ion implantation and heat treatment method described above, recovery from implantation damage caused by heat treatment after ion implantation is due to solid phase growth from a completely crystalline phase without damage on the substrate side and surface side. The problem is that the damage is confined within the substrate, and the threshold of impurity concentration at which secondary defects are recovered is lowered when compared with ion implantation at low energy. Further, since secondary defects occur near the impurity concentration peak position of the desired impurity phase, there is a problem that they have an adverse electrical effect.

In view of this, the present invention provides a semiconductor device in which an impurity layer is formed deep in a substrate by performing ion implantation at high energy without lowering the threshold of impurity concentration at which secondary defects are recovered. It is an object of the present invention to provide a semiconductor device in which a desired impurity layer is formed in which the electrical adverse effects caused by secondary defects are eliminated by making the position where the secondary defects occur deeper than the desired impurity layer.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention includes a step of ion-implanting desired impurities deep into a semiconductor substrate, and a step of ion-implanting atoms that do not determine the conductivity type to a depth shallower than the depth of the ion-implanted region. The heat treatment is performed after the steps are performed.

Function The present invention provides an ion-implanted layer of atoms that do not determine the conductivity type at a shallower position than the ion-implanted layer of the desired impurity, and allows the ion-implanted layer of atoms that do not determine the conductivity type to reach the damaged layer in the substrate and the substrate surface. Since defect recovery by solid phase crystal growth is performed only from the substrate side and defects are not confined, it is possible to prevent the impurity concentration from decreasing to a threshold value at which secondary defects occur.

Embodiment FIG. 1 is a diagram showing a method of manufacturing a semiconductor device according to an embodiment of the present invention in which ions of atoms whose conductivity type is not determined are implanted to a depth shallower than a desired impurity layer. A desired impurity layer 12 is obtained by implanting ions of an impurity of a desired conductivity type into a silicon substrate 11. Immediately after the ion implantation, a perfectly crystalline layer 13 that has not been damaged by the ion implantation remains near the surface of the silicon substrate. (Figure 1a))
.

Thereafter, a layer in which the impurity peak position in the ion implantation region is shallower than the ion implantation peak (and is not damaged after implantation) is formed between the ion implantation layer 12 and the ion implantation layer 14 of atoms whose conductivity type is not determined. Atoms whose conductivity type is not determined by the implantation energy such that they do not remain in the
Ge, N, A.

A new damaged layer 14 is formed by ion implantation (FIG. 1b)) Ion implantation of atoms whose conductivity type is not determined is performed until the damaged layer by ion implantation reaches the substrate surface. Therefore, it goes without saying that ion implantation may be performed multiple times. Next, heat treatment is performed to activate impurities of a desired conductivity type and to recover damage caused by ion implantation only from the substrate side through in-phase growth (FIG. 1c)).

FIG. 2 is a diagram illustrating a method for manufacturing a semiconductor device according to an embodiment of the present invention in which ion implantation of atoms that do not determine the conductivity type is performed deeper than the desired impurity phase. A desired impurity layer 22 is obtained by performing ion implantation.

Even in this case, the perfect crystal layer 23, which has not been damaged by the ion implantation, remains near the surface of the silicon substrate (FIG. 2b).

Further, the impurity peak position in the ion implantation region becomes deeper than the ion implantation peak, and the ion implantation layer 22
The ion implantation layer 24 of atoms that do not determine the conductivity type is ion-implanted with an implantation energy such that no layer without damage due to ion implantation remains between the ion implantation layer 24 of atoms that do not determine the conductivity type, and a new damaged layer 24 due to ion implantation is performed. (Fig. 2b)). Ion implantation of atoms that do not determine the conductivity type is performed so that the damage layer reaches a depth that prevents secondary defects generated after heat treatment from entering the desired impurity layer.

In this case, it does not matter which order the desired impurity is implanted or the ion implantation of atoms whose conductivity type is not determined can be performed first. It goes without saying that ion implantation may be performed multiple times in this case as well. Next, heat treatment is performed to activate impurities of a desired conductivity type and to recover damage caused by ion implantation by in-phase growth. Although the occurrence of secondary defects is observed after the heat treatment, since the secondary defect generation region 25 is located deeper than the desired impurity layer 22, there is no electrical adverse effect on the elements formed on the silicon substrate surface (Fig. 2c). )).

As described in detail, according to the present invention, in order to introduce impurities of a desired conductivity type deep into a semiconductor substrate, the introduction of impurities of a desired conductivity type into a semiconductor substrate and the ion implantation of atoms that do not determine the conductivity type are carried out by ion implantation. It is also desirable to prevent a drop in the impurity concentration threshold at which secondary defects occur because the damaged layer reaches the substrate surface and allows in-phase growth to grow only in one direction from the substrate side in solid phase growth by post-implantation heat treatment. The conductivity type is determined deeper than the conductivity type impurity layer.

By performing ion implantation of non-containing atoms, it is possible to form a secondary defect generation region deeper than the impurity layer, thereby making it possible to form an impurity layer that does not have an electrically harmful effect on the elements on the substrate surface, making it practical. The effect is great.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views of the manufacturing process of an embodiment of the method of manufacturing a semiconductor device according to the present invention, and FIG. 3 is a cross-sectional view of the manufacturing process of a conventional method of manufacturing a semiconductor device. 11...Silicon substrate, 12...Impurity layer, 13...Surface side perfect crystal layer, 14...
...Ion-implanted layer of atoms that do not determine the conductivity type, 15.
...Solid phase growth layer, 16...Damaged layer. Name of agent: Patent attorney Shigetaka Awano and one other person Figure 1 Atsushizu Figure 1

Claims (2)

[Claims] (1) A semiconductor device comprising the steps of ion-implanting impurities of a desired conductivity type deep into a semiconductor substrate, and implanting ions of atoms whose conductivity type is not determined shallower than the depth of the ion-implanted region. Production method. (2) A semiconductor device characterized by comprising the steps of ion-implanting impurities of a desired conductivity type deep into the semiconductor substrate and implanting ions of atoms whose conductivity type is not determined deeper than the depth of the ion-implanted region. Production method.