JPH01108764A - Formation of insulating film - Google Patents

Abstract

PURPOSE:To enable realizing increase of integration density, high speed operation, decrease of power consumption, and high reliability when transistor and the like are formed, by a method wherein the surface of an Si single crystal substrate is subjected to high concentration ion implantation of the same group element as the substrate, and an insulating layer is formed under the substrate surface, by annealing the substrate in an oxygen or nitrogen atmosphere. CONSTITUTION:In an Si single crystal substrate, Ge ions of the same group are ion-implanted, an amorphous layer of Si+Ge is formed. This ion-implanted Si substrate is subjected to annealing in a nitrogen atmosphere, and turned into a single crystal layer 4 containing Ge. An insulating film 5 is formed at a position 3 of implantation depth. Thereby simplifying the process, and forming the insulating film under the substrate surface without increasing the cost.

Description

[Detailed Description of the Invention] Industrial Application Fields> The present invention provides an S
This is related to the IL board.

<Prior art> In general, in MOS IG, transistors exist only near the surface of the substrate. ! Most of the plate is only needed to maintain mechanical strength. Furthermore, since the substrate itself is a semiconductor, leakage current flows through the substrate, consuming ineffective power.

As a means to prevent such reactive power consumption! ! Sapphire was used as a plate, and 81 was epitaxially grown on the surface of this sapphire (S08-sil
1con-on-sapphire), and this substrate increases integration density and speeds up.

It is possible to achieve low power consumption and high reliability.

In addition, the surface of the Si single crystal substrate is converted to SiO2, polycrystalline or amorphous 3i is epitaxially grown on this, one end of these polycrystalline or amorphous 9i is brought into contact with the surface of the 81 single crystal substrate, and this is used as a seed. , it is sequentially made into a single crystal using a laser beam, an electron beam, etc. (
S Ol-5i I l 1con-.

A method (SIMOX) in which a large amount of oxygen ions are directly implanted into a Sil plate to form 5i0211 is also being considered.

<Problems to be Solved by the Invention> However, in the above conventional method, SOS suffers from compressive strain due to the difference in thermal expansion coefficient between sapphire and Si, high density lattice defects, presence of a transition region at the interface between sapphire and Si, There are also problems such as autodoping of Al impurities from one plate.

SOI is not yet technically established and furthermore.

SIMOX supplies all the m element ions for the formation of 1III by ion implantation, so a large current (~
0. IA) There is a problem in that it requires an ion implantation device (the current value of which is about two orders of magnitude higher than that of a general implantation device) and is not practical.

The present invention has been made in view of the problems of the prior art described above, and uses a commonly used ion implantation device to implant ions of the same group as the substrate into aSr! Inject into 1.

The purpose is to form an insulating layer under the surface of the substrate by annealing in an oxygen (or nitrogen) atmosphere at about atmospheric pressure.

Means to solve problems〉 The structure of the present invention for solving the above problems is as follows.

It is characterized by forming an insulating layer under the surface of the substrate by ion-implanting elements of the same group as the substrate into the surface of a Si single-crystalline substrate at a high concentration, and annealing the substrate in an oxygen or nitrogen 1# atmosphere. That is.

Embodiment> Figure 1 is a cross-sectional view showing a state in which Ge group ions are implanted into an S1 single crystal substrate, where 1 is a single crystal Si substrate, 2 is a Si+
It is an amorphous layer of G, e, and 3 is the implantation depth! (as
1g1plantation)T8゜In this example, the ion acceleration energy is 200Kev, and the dose is 15X10' atm/cm2. The implantation depth is set to 0.1 μmfy degree.

FIG. 2 shows a state in which the Si substrate 1 into which ions have been implanted as shown in FIG. The single crystal 114 containing the implantation depth is a (as +g+
A state in which an insulation 115 is formed on pla is shown. This insulating film is formed when dangling bonds (unstable bonds that are not bonded to any atoms) formed at a depth of 0.1 μm combine with nitrogen or oxygen introduced during ion implantation and annealing. Ru. Also, due to the gettering effect, defects are generated on the surface of the substrate due to ion implantation, but the defects are concentrated at the dangling bond formed at a position of 0.1 μm.

It is possible to restore the substrate surface to a perfect single crystal.

Figures 3(a), (b), and (c) show the positions at a depth of 0.1 μm and 0.4 μm on the surface of the Sil plate shown in Figure 4.
S CA (electron apectrosco
py f.

The bonding state of Si atoms is measured by r chemical analysis and is shown as the relationship between the binding energy (horizontal axis) and the number of photoelectrons (vertical axis). According to the figure, at 0°1 μm there is S (SiOx as an insulating film).
*5fsNa is found to exist. Note that, without being limited to the above embodiments, for example, by forming a film containing a desired element on the surface of the substrate before ion implantation, I.
It is also possible to modify the change in I. With such SO[, the same effect as the above-mentioned SO8 can be obtained, and since there is no coefficient of thermal expansion or transition region at the interface, if a transistor etc. is formed on the surface of the I plate, It becomes more reliable.

In this example, Ge was ion-implanted at a high concentration into a 3i single crystal substrate and annealed in a nitrogen atmosphere.
The ki plate may be ion-implanted with 3i and other group elements at a high concentration, or may be annealed in an oxygen atmosphere.

Further, the acceleration energy and dose amount are not limited to those in this embodiment, and can be appropriately selected as necessary.

<Effects of the Invention> As specifically explained above in conjunction with the embodiments, according to the present invention, ions of the same group as the substrate are implanted at a high degree using a commonly used ion implantation device, and the ions are implanted at about atmospheric pressure. By annealing in an oxygen (or nitrogen) atmosphere,
It is possible to form an insulating film under the surface of the substrate without simplifying the process or increasing the price, and when forming transistors etc., it achieves increased integration density, higher speed, lower power consumption, and higher reliability. You can.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing the state in which the same group of elements is ion-implanted into the substrate, Figure 2 is a cross-sectional view showing the state in which the substrate shown in Figure 1 has been annealed, and Figure 3 is a diagram showing the bonding state of Si atoms. ,
FIG. 4 is a diagram showing the measurement target position in FIG. 3. 1... Single crystal 3i substrate, 2... Amorphous layer, 3...
Position of implantation depth, 4... 3i single crystal containing Ge, insulating film. Garden (c) 10.4J, 1m inside) Surgi

Claims (1)

[Claims] An insulator characterized by forming an insulating film under the surface of a Si single crystal substrate by ion-implanting elements of the same group as the substrate at a high concentration into the surface of the substrate and annealing the substrate in an oxygen or nitrogen atmosphere. Film formation method.