JPS6022494B2 - PN junction formation method - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for forming a PN junction.

A liquid phase epitaxial method is known as an effective method for forming a PN junction.

That is, in this method, a first semiconductor crystal made of a first conductivity type semiconductor crystal is used.
A second layer made of a semiconductor crystal of a second conductivity type is formed on the first layer by depositing a melt containing impurities of a second conductivity type on the layer. However, according to such a liquid phase epitaxial method, when forming the second layer, impurities in the grown layer diffuse into the first layer, changing the substantial impurity concentration in the first layer, or There are drawbacks such as changing the PN junction form from a stepped type to an inclined type.

This drawback is particularly noticeable when the impurity used to form the second layer has a large diffusion constant. The present invention has been made in view of this point, and uses a melt containing an impurity with a large diffusion constant on a first layer made of a semiconductor crystal of a first conductivity type to form a semiconductor crystal of a second conductivity type. When the second layer is grown by liquid phase epitaxial growth to form a PN junction, the first layer is characterized in that the same amount of the same impurity as above is included in advance.

That is, according to the present invention, when the second layer is grown, since the same and the same amount of impurities are present in the first layer, the impurities in the second layer cannot migrate into the first layer. do not have. An embodiment of the present invention will now be described in the production of a Gap red light emitting PNPN diode. FIG. 1 shows the structure of a diode 1 manufactured in this embodiment.

The diode 1 consists of adjacent regions P, , N2, P3, and N4, and junctions J, J23, and J23 are connected to the adjacent portions of each region, respectively.
It has a J cell, and when a positive potential and a negative potential are applied to each of the P and N4 regions, respectively, the device is turned on and light is emitted in the P3 region. In this example, when manufacturing the above diode, an N4 region is formed on an N-type Gap substrate formed in advance by a pulling method, etc., and P3 and N2 regions are sequentially formed on this substrate.
, P, are grown by liquid phase epitaxial growth.

FIG. 2 shows a manufacturing device for this purpose, in which 2 is a support made of carbon, 3 is a recess provided in the flat surface of the support,
4 is an N-type Gap crystal substrate layered in the recess, {51
A slide plate made of carbon and having through holes 6, 7, and 8 at appropriate intervals is freely mounted on the surface of the support base 2.
9, 10, and 11 are first, second, &a-th melts arranged in the through holes 6, 7, and 8, respectively. The substrate 4 contains Te as an N-type impurity and Zn as a p-type impurity.
6 x 1 and 7 enemies - 3 are combined.

The first, second, and a melts 9, 10, and 11 are each made of GaP.
Contains Zn as a polycrystalline and P-type impurity, and further contains IG
The a-th melt 9 contains O as an N-type impurity, and the a-th melt 10 contains Te as an N-type impurity. The content of each of these impurities is determined according to the impurity concentration distribution shown in FIG. 3, which will be described later.
The melt 10 exhibits N type. With this arrangement, the slide plate 5
, first deposit the No. IGa insect solution 9 on the substrate 4,
A P-type region P3 is formed by cooling, and then N2,
N-type and P-type regions of P, are formed.

Figure 3 shows the impurity concentration distribution of the PNPN diode manufactured in this way. 7 arc-3 is included, and the P3 area is 3×1
and 7-3, N2 contains 7×1 and 7-3 Te.

Therefore, due to the mutual compensation effect between the P-type and N-type impurities, the substantial impurity concentration in each region becomes as shown by the dotted line, and a PN junction is formed between each region. What should be noted here is that
Since the same amount of Zn is contained in each region, even though Zn has a very large diffusion constant, there is no diffusion movement of Zn between crystal layers during crystal growth, and therefore impurities do not form as designed. A concentration distribution is obtained, and the PN junction becomes more step-like.

Incidentally, in the P3 region, a bare circle of Zn and ◯, which is the center of red light emission, is formed, and red light is emitted in this region.

Thus, according to the present invention, a semiconductor crystal layer of a second conductivity type is grown liquid-phase epitaxially on a semiconductor crystal layer of a first conductivity type using a melt containing an impurity having a large diffusion constant.
When forming a junction, undesired diffusion and movement of the impurity having a large diffusion constant is suppressed, and it is possible to obtain a designed impurity concentration distribution and a PN junction closer to a conventional step type.

[Brief explanation of the drawing]

FIG. 1 is a structural diagram of a PNPN diode manufactured according to an embodiment of the present invention, FIG. 2 is a cross-sectional view showing the manufacturing apparatus thereof, and FIG. 3 is an impurity concentration distribution diagram of the revised PNPN diode. 4...Substrate, 9, 10, 11...1st
, 2nd, about a kudzu worm liquid. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. When forming a PN junction by liquid phase epitaxial growth of a semiconductor crystal layer of a second conductivity type using a melt containing an impurity with a large diffusion constant on a semiconductor crystal layer of a first conductivity type, P characterized in that the same amount of the same impurity as above is uniformly included in the conductive type semiconductor crystal layer in advance.
N-junction formation method.