JPS6147630A - Adjustment of n type carrier concentration distribution in gallium arsenic semiconductor - Google Patents

Abstract

PURPOSE:To adjust carrier concentration distribution of N type layer after ion implantation by selecting a fused composition ratio of gallium and arsenic on the occasion of manufacturing a semi-insulating gallium arsenic substrate. CONSTITUTION:A semi-insulating gallium arsenic single crystal substrate is manufactured with the liquid sealing lifting method by selecting a fused composition rate of gallium and arsenic in the range of 0.500-0.505 and it is then subjected to the heat processing by ion implantation to such substrate. For example, a substrate is cut away from an ingot by lifting a crystal using fused solution having the fused composition ratio in said range and the Si ion is implanted to such crystal substrate under the condition of 150keV and 3X10<12>cm<-2>. Thereafter, the heat processing is carried out under the ambient of 850 deg.C, 30min, As pressure (PA84-100Torr). Thereby, the N type carrier concentration distribution depends on the fused composition ratio, and moreover an electrical conductive layer having less fluctuation, excellent uniformity and controlability can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for adjusting n-type chiaria concentration distribution in a gallium arsenide semiconductor.

<Conventional technology> Among the ■-■ group compound semiconductors, gallium arsenide (Ga, A
s) is high-quality GaA with high electron mobility, high insulating properties with a resistivity of 10"Q-α or more, few defects in the crystal, and a fine distribution. Because of its high availability and ease of manufacturing large wafers, it is becoming widely used as a crystal substrate for elements of ultrahigh-speed integrated circuits and opto-electronic integrated circuits.

As a method for producing a GcLAs single crystal that satisfies such requirements, a high-pressure liquid seal pulling method in which raw materials are directly synthesized is known, and high-quality single crystals are produced.

On the other hand, when this single crystal is used as a crystal substrate for an integrated circuit, it is cut into wafers, impurities such as Si ions are added by ion implantation, and the Si atoms are electrically activated. Therefore, heat treatment is performed at 800 to 900°C to form an n-type electrically conductive layer.

<Problems to be solved by the invention> By suppressing thermal transformation and forming an electrically conductive layer with uniform electrical properties in the above manufacturing method, it is possible to produce various high-performance devices by fractionation and with good reproducibility. This is an essential requirement, but when forming a pn-type layer by ion implantation using a crystal substrate grown by liquid sealing as described above, it is necessary to form a pn-type layer with good controllability and uniformity. It was extremely difficult to form an electrically conductive layer.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for adjusting the n-type carrier concentration distribution in a gallium arsenide semiconductor, which causes little thermal denaturation and forms electrical conductivity with uniform electrical characteristics.

<Means to Solve the Problem> According to experiments conducted by the inventors of the present application, the carrier concentration distribution in the n-type layer formed by the ion implantation method is not limited to carriers formed by implanted ion atoms, but also to the semi-insulating layer before ion implantation. In other words, implanted atoms such as s5 atoms need to occupy Gαα vacancies and M vacancies, but the chiaria concentration distribution in this case depends on the manufacturing process of the gallium arsenide substrate. It was found that defects in the crystal substrate also affected the effect.

Specifically, it has been found that by selecting the composition ratio of gallium and arsenic melt when manufacturing a semi-insulating gallium arsenide substrate, the chiaria concentration distribution in the n-type layer after ion implantation can be adjusted. Therefore, in this invention, the melt composition ratio of gallium and arsenic is selected within the range of 0-500 to 0.505, and the semi-insulating potassium arsenide single crystal substrate is fabricated by the liquid sealing method. After manufacturing, the wafer of the false substrate is ion-implanted and heat treated according to the conventional method J】1! It is something to do.

<Effects of the Invention> When a gallium arsenide n-type semiconductor is formed by selecting the melt composition ratio of gallium and arsenic within the above range, the n-type carrier concentration distribution depends on the melt composition ratio, and there is also no variation. A uniform Ml electrically conductive layer with a small amount and good controllability can be obtained.

<Example> Example 1 In order to investigate the dependence of the melt composition ratio when manufacturing a GaAs single crystal by the liquid-sealed pulling method and the chiaria concentration distribution of the n-type layer formed by ion implantation, five types of A crystal ingot was prepared.

Here, each crystal ingot was manufactured by pulling crystals under the same conditions using a melt having a melt composition ratio in the range of 0.488 to 0.509. Thereafter, a substrate was cut out from each ingot, and Si ions were implanted into each crystal substrate under the conditions of 150 KeV 5 × 1012 (m-'') at 850° C. for 30 min and A8 pressure (
PA! The heat treatment was performed in an atmosphere of 14 to 1'00 TOrγ).

Thereafter, Schottky electrodes having a diameter of 500 μm were formed on the substrate surface at 21 intervals, and the Schottky electrode concentration distribution was measured by the CV method.

Since the obtained Chiaria concentration distribution differs at each position on the substrate surface, the average Chiaria concentration at each position of the distribution shifted to the top and bottom was calculated, and a new average Chiaria concentration distribution was calculated. I asked for it. FIG. 1 shows the chiaria concentration distribution of the substrate cut out from the center of the crystal ingot when the melt composition ratio is 0.48B, 0.502.0°509. Although the results of 0.500 and 0.505 are not shown in the figure, the distribution is similar to that of 0.502.

As is clear from FIG. 1, the Chiaria concentration distribution differs depending on the above-mentioned melt composition ratio, and there is a dependence on the melt composition ratio.

Example 2 Furthermore, in order to understand the detailed dependence on the melt composition ratio, the degree of variation in the carrier concentration distribution measured within the substrate plane was expressed as the peak value of the carrier concentration distribution (Np).
The definitions of Np and Δx are shown in FIG. 2, where the evaluation was performed based on the deviation (Δx) from the L8B theoretical distribution. FIG. 3 shows the average value of NP and Δ× and its standard deviation with respect to the melt composition ratio as the length of the error bar. -1 As is clear from this figure, the composition ratio. , 500 to 0.505, where the crystals were grown with a slight excess of As, a steeper distribution with less variation was obtained.

From these results, it is clear that the chiaria concentration distribution is influenced not only by chiaria produced by Si atoms but also by other factors related to the melt composition.
The steep concentration distribution of n-type carriers in the substrate made with a composition ratio of ~0.505 was close to the Si atom concentration distribution obtained by ion implantation, and a uniform electrically conductive layer with good controllability was formed.

[Brief explanation of the drawing]

Figure 1 shows the relationship between the Ga and As melt composition ratio and Gearia concentration distribution, and Figure 2 shows the relationship between Gearia concentration distribution and L8
Figure 6 shows the relationship between the B theoretical distribution and the peak value of the Gearia concentration distribution (Np
) is a diagram showing the relationship between the average value of the deviation (Δ×) from the Ls8 theoretical distribution and its standard deviation. Patent Applicant Director of the Agency of Industrial Science and Technology Kawa [] 1st interval 00.5 Omuka IX et Φ Yu Riko (μm) 2nd YM Surface force 1 Yunotsuka 2 31st! ! As/(Go+As)

Claims (1)

[Claims] The melt composition ratio of gallium and arsenic is 0.500 to 0.505.
n-type carrier concentration distribution in a gallium arsenide semiconductor, which is characterized by manufacturing a semi-insulating gallium arsenide single crystal substrate by a liquid seal pulling method by selecting within the range of adjustment method.