JPS61207016A - Formation of gallium arsenide conductive layer - Google Patents

Abstract

PURPOSE:To contrive improvement in crystallizability by a method wherein Si or Sn and Ga are simultaneously ion-implanted on a compound semiconductor GaAs crystal and then a heat treatment is performed thereon. CONSTITUTION:When an N-type region is going to be formed by ion-implanting IV group element which is intrinsically amphoteric impurity for GaAs, the crystallizability of GaAs can be improved without impairing the rate of activation by performing a double-implantation of Ga, double-implantation of the suitable dosage of Ga against the specific dosage of Si and Sn, and a heat treatment. When the crystallizability of GaAs conductive layer is improved, advantages such as improvement in irregularity of characteristics, improvement in controllability and the like in the manufacture of a highly efficient device such as GaAs extra high speed LSI and the like can be obtained. As a result, the GaAs conductive layer of excellent crystallizability can be formed.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method of forming a gallium arsenide conductive layer.

(Prior art and its problems) Compound semiconductors, especially gallium arsenide (GaAs), are called post-silicon materials, and the development of ultrahigh-speed LSIs is progressing rapidly. Ion implantation technology is one of the M'l elemental technologies. Ion implantation technology for compound semiconductors including GaAs.

Although ion implantation technology into silicon (81) is almost an established technology, it cannot be said to be fully established yet, and there are problems particularly related to stoichiometric composition specific to compound semiconductors.

Conventionally, as an attempt to solve this theoretical composition problem in chemistry 1, when ions of elements to be impurities were implanted.

So-called double implantation, in which constituent elements of a compound semiconductor are implanted simultaneously, has been carried out. Typical example Fi.

Radiat Effects
ionEffects) IE Volume 48, 1980, 9
As reported on page 1, this is a double implantation of GaAs 8e and Ga, and this double implantation improves the activation rate compared to when 8e is implanted alone, and the peak carrier concentration is 1.75X10 / d has been achieved. This is because a86 is a group VI element and becomes a donor by replacing As, and the Ga vacancy generated at this time becomes a donor at the As position.
It tends to combine with C to form an acceptor, but G
It is thought that this was suppressed by simultaneously injecting a. Also, during ion implantation of Ge, which becomes an amphoteric impurity in GaAs.

An implantation amount of 1XIQ"/G7! or higher normally results in n-type, but by simultaneously implanting Ga1, n-type is not formed and p-type is formed.
Vedrotti et al. reported in the Journal of Applied Physics that double injection of As does not accelerate n-type activation.
Plied Physics) Volume 51, 1980.

It is reported on page 5781. Thus, it has not been shown that controlling the stoichiometric composition during ion implantation by double implantation is effective in improving the activation rate.

However, when forming an n-type active layer of a GaAs device by ion implantation, the required dose is on the order of at most 10 diodes even in a highly doped layer; Ge, which becomes p-type in this range, is rarely used.

In order to improve device characteristics, it is necessary to reduce damage during ion implantation as much as possible, so it is desirable to use ion species with a lighter mass, and also to reduce the negative impact of the profile during implantation caused by heat treatment after ion implantation. Currently, ion species with small diffusion coefficients are desired due to the need to do so.

This means that Si is being used. Even with this ion implantation of Si, some problems with stoichiometric composition have not been pointed out. What has been particularly problematic is that SiOz is used as a protective film during heat treatment to recover from damage after Si treatment.

This means that a large amount of Ga diffuses outward from GaAs.

In general, ff, 8i becomes an n-type dopant by exchanging with Ga in GaAs, and Ga vacancies are not considered to promote activation of St, but the above external diffusion amount is s 8
t is much larger than the optimal amount of Ga vacancies to replace the Ga positions, which reduces the activation rate.
It has been pointed out that crystallinity also deteriorates. Also, regarding the GaAs substrate crystal itself.

In order to suppress the evaporation of As during crystal growth, growth is carried out under As conditions, and it has been pointed out that for this reason, the resulting substrate has an excess of As.

GaAs lf: EL-2 which is a superficial deep impurity level
It has also been pointed out that this is an aggregate of excess As.

Despite the fact that the imbalance in stoichiometric composition has been pointed out, there have not been many reports of double implantation in 81 ion implantation until now.

(Objective of the Invention) The object of the present invention is to improve the crystallinity of gallium arsenide without impairing the activation rate by doubly implanting an appropriate amount of potassium 9 when performing ion implantation of group IV elements such as silicon into gallium arsenide. An object of the present invention is to provide a method for forming a gallium arsenide conductive layer that improves the performance of the gallium arsenide conductive layer.

(Structure of the Invention) A method for forming a gallium arsenide conductive device according to the present invention includes a step of simultaneously implanting ions of silicon or tin and gallium into a compound semiconductor gallium arsenide crystal, and a step of performing heat treatment after the ion implantation step. configured.

(Principle of operation of the present invention) The present invention uses ion implantation of group IV elements, which are essentially amphoteric impurities, into GaAs, such as 8i and Sn, to form an n-type region using a novel technique in which Ga is double-implanted. The idea is that by doubly implanting an appropriate Ga dose for a constant 8i, 81 dose and heat treatment, the activation rate will not be impaired (the crystallinity of GaAs can be improved). This is based on a new experimental fact that found that.

Group ■ elements are G
As can be seen from the example of e, double implantation of As is effective in the same way as in the case of Ge, from the viewpoint of obtaining a high activation rate by occupying the Ga position and becoming a donor as an n-type dopant. It is expected that double implantation will rather suppress the activation rate, and in this way, the idea of double implantation that has been carried out in the past has led to the double implantation using the combination of group IV elements and Ga of the present invention. cannot be easily inferred.

The novel idea of the present invention is that simply 81 or 8n Ga A
This cannot be achieved by focusing only on one process, i.e., ion implantation into s. This problem arises only by taking into consideration the problems of overall crystallinity, that is, defects caused by excess As, or Ga vacancies.The main purpose of the present invention is to improve this crystallinity. It is placed in Even if it does not necessarily lead to high activation.

It is clear that improving crystallinity brings about various advantages, such as improving property variations and improving controllability, especially when manufacturing high-performance devices such as GaAs ultrahigh-speed LSIs. s S i or 8 as detailed in later examples
There is an optimal value for the dose of Ga that can improve the crystallinity without impairing the activation rate of n, but within this optimal value, 81 or within a range that does not impair the activation rate of FiS n. Recovery of defects due to Ga vacancies and excess M is best accomplished by Ga implantation followed by heat treatment.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to one drawing.

Ga ions are accelerated on a semi-insulating substrate at an energy of 100 keV and a dose of I x 10”l 3
X 10”.

I x 10”, 3 x 101311 x 10”
/m, followed by 81 ions at 47.5ke.
% Si O2 was protected for a total of 6 types: a sample double-implanted with an acceleration energy of V and a dose of 5 x 1012/cId, and a sample in which only 8i ions were implanted under the same conditions without implanting Ga ions. 850C,2 as a membrane
Raman scattering was measured after applying vinyl in a hydrogen atmosphere for 0 minutes.

FIG. 1 is a characteristic diagram showing the results of measuring the Raman scattering intensities of the six types of samples mentioned above.

The peak near 292α is a Raman scattering spectrum corresponding to the LO phonon vibration mode of GaAs, and it is considered that the larger the peak intensity of this peak, the better the seed crystallinity with a narrower half-width. As can be seen from FIG. 1, the peak intensity increases as the implantation dose of Ga ions increases up to a dose of 3X10"/c++f.
At 14y, the dose started to decrease. That is,
Peak intensity II at a dose of 3 x 10”/Cff1
'i is maximum, and it can be understood that the crystallinity is also good. Also, the dependence of Raman intensity on the dose of Si ions implanted at the same time is as follows:
It was found that there was almost no change in the range.

Figure 2 shows Pole measurement performed on the same sample.

FIG. 3 is a characteristic diagram showing the dependence of sheet carrier concentration on Ga ion implantation dose.

8i ion implantation dose is 5X10", 3xIQ" when %-, @! It can be seen that the sheet carrier concentration does not change up to a Ga ion implantation dose of 1XIQ''9 when the 81 ion implantation dose is 5X10'' grain. Kone has shown that the presence of Ga does not affect the activation of Si up to these doses. Therefore, when considered together with the results in Figure 1, the h Si ion implantation dose is 5 x 10"7c.
In the case of m, Ga ions are simultaneously implanted at a dose of 1×10”Al1, and the 81 ion implantation dose is 5×I
In the case of Q ” ”/Cl, 3X10/CI+ at the same time!
It can be seen that the crystallinity can be improved without affecting the activation rate of 81 by implanting Ga ions and then performing heat treatment.

Although this example was conducted only for SN ions, similar results were obtained for 8n ions, and simultaneous implantation of Ga ions improved crystallinity without affecting the activation rate of h8n. has been realized.

The n-type region thus obtained is a GaA3 ultrafast LS
By applying it to various devices including I, we can expect to obtain products with good characteristics.

(Effect of the invention) According to one aspect of the present invention, as described in detail above.

A gallium arsenide conductive layer with better crystallinity than conventional methods can be formed. By applying this gallium arsenide conductive layer to the manufacture of electronic devices, it is possible to improve the controllability of the manufacturing process and improve the characteristics of the product.

[Brief explanation of drawings]

Figure g1 is a characteristic diagram showing the dependence of the 277 intensity on Ga ion implantation dose of GaAs substrates manufactured by the present invention and the conventional method, and Figure 2 is a characteristic diagram of GaAs substrates manufactured by the present invention and the conventional method.
FIG. 2 is a characteristic diagram showing the relationship between the zero dose of Ga ion implantation in the s-substrate and the sheet carrier concentration. Cow [a 21y0290 3t) 0 @] skin count) (c mu-9

Claims (1)

[Claims] A method for forming a gallium arsenide conductive layer, the method comprising the steps of: simultaneously ion-injecting silicon or tin and gallium into a compound semiconductor gallium arsenide crystal; and performing heat treatment after the ion implantation step.