KR100737820B1 - Method of forming p-type compound semiconductor layer - Google Patents

Abstract

A method for forming a P-type compound semiconductor layer is provided to properly interrupt combination of P-type impurity and hydrogen, so that it is no necessary to carry out an additional annealing process. A substrate loaded in a process chamber is raised by a first temperature(S101), and a source gas of group-III elements, a source gas of P-type impurity, and a source gas of nitrogen containing hydrogen are added in the process chamber to grow a P-type compound semiconductor layer(S103). After growth of the P-type compound semiconductor layer is completed, supply of the source gas of group-III elements and the source gas of P-type impurity is stopped(S105), and the substrate is cooled by a second temperature. Then, supply of the source gas of nitrogen is stopped(S109). The substrate is cooled by room temperature(S113).

Description

P-type compound semiconductor layer formation method {METHOD OF FORMING P-TYPE COMPOUND SEMICONDUCTOR LAYER}

1 is a schematic longitudinal cross-sectional view of a conventional (Al, Ga, In) N-based compound semiconductor.

FIG. 2 is a flowchart for explaining a P layer manufacturing method of a conventional (Al, Ga, In) N compound semiconductor.

3 is a flowchart illustrating a method of forming a P-type compound semiconductor layer according to a preferred embodiment of the present invention.

4 is a graph schematically illustrating a method of forming a P-type compound semiconductor layer according to a preferred embodiment of the present invention.

5 is a schematic longitudinal cross-sectional view of a (Al, Ga, In) N-based compound semiconductor having a P-type compound semiconductor layer prepared according to a preferred embodiment of the present invention.

6A and 6B are views for explaining effects of the method of forming a P-type compound semiconductor layer according to a preferred embodiment of the present invention.

The present invention relates to a method for forming a P-type compound semiconductor layer, and more particularly, to form a (Al, Ga, In) N-based compound semiconductor layer (P layer) containing a P-type impurity that can simplify the semiconductor manufacturing process. It is about a method.

The (Al, Ga, In) N-based compound semiconductors are applied to compound semiconductor devices such as, for example, light emitting diodes (LEDs) or laser diodes (LDs). 1 is a longitudinal sectional view schematically showing a conventional (Al, Ga, In) N-based compound semiconductor device.

Referring to FIG. 1, an (Al, Ga, In) N compound semiconductor layer (N layer, 13) containing an N-type impurity on the substrate 11 (N layer, 13), an active layer 15 and an (Al) containing a P-type impurity , Ga, In) N compound semiconductor layer (P layer, 17) is formed sequentially.

The conventional (Al, Ga, In) N-based compound semiconductor layer is grown through a process such as metalorganic chemical vapor deposition (MOCVD).

According to the metal organic chemical vapor deposition method, in the (Al, Ga, In) N compound semiconductor layer, a source gas of a group III element such as Al, Ga, or In, ammonia (NH3) gas containing hydrogen and nitrogen is a reaction chamber. N layer 13, active layer 15, and P layer 17 are sequentially grown on the substrate 11 at 900-1200 ° C. When the P layer 17 is formed by doping with magnesium (Mg), the inflow of the source gas of the group III element is stopped and the inflow of ammonia is maintained while the temperature of the reaction chamber is lowered to cool the substrate 11.

On the other hand, in the conventional (Al, Ga, In) N-based compound semiconductor device 10, conductivity is usually secured to the P layer 17 by, for example, magnesium (Mg) doping. However, P-type impurities such as magnesium (Mg) are easily combined with hydrogen (H) contained in ammonia during the temperature drop process of the reaction chamber as described above, thereby providing free holes of P-type impurities. There is a problem that the function as an electron acceptor is reduced and the resistance value of the P-type compound semiconductor layer is increased.

Therefore, in the P-layer manufacturing process of the (Al, Ga, In) N-based compound semiconductor, a separate annealing process is performed to separate the bond between the P-type impurity and hydrogen.

2 is a flowchart for explaining a P layer manufacturing method of a conventional (Al, Ga, In) N-based compound semiconductor.

Referring to FIG. 2, the temperature of the substrate is raised to 900 to 1200 ° C. in the reaction chamber, and the P layer of the compound semiconductor is grown on the substrate by supplying P-type impurities, group III elements, and ammonia (S1). When the P layer is grown, supply of source gas of P-type impurities and group III elements is stopped, but source gas of nitrogen is continuously supplied, and the temperature of the reaction chamber is lowered to cool the substrate to room temperature (S2). When the substrate is cooled to room temperature, the substrate on which the P layer is grown is withdrawn from the reaction chamber (S3), and an annealing process is performed to lower the resistance value of the P layer grown on the extracted substrate (S4). Referring to US Pat. No. 5,306,662, a P layer of a compound semiconductor is grown with P-type impurities, group III elements and ammonia, and then annealing of the P layer is performed at a temperature of 400 ° C. or higher. As a result, hydrogen bonded to the P-type impurity present in the P layer is removed, thereby producing a P-type (Al, Ga, In) N-based compound semiconductor having a low resistance value.

As described above, in the conventional (Al, Ga, In) N compound semiconductor device, at least one annealing process should be added to lower the resistance value of the P layer. However, this additional annealing process has a problem of complicated and cumbersome manufacturing process of the compound semiconductor device.

In addition, the time required for manufacturing the product increases with the addition of the annealing process, and in particular, the investment cost for the manufacturing equipment is increased by purchasing expensive equipment for the annealing process and requiring space for equipment installation. It is a factor that raises the unit price of.

An object of the present invention is to provide a method for forming a P-type compound semiconductor layer that blocks the bonding of P-type impurities and hydrogen when the P-type compound semiconductor layer is formed.

Another object of the present invention is to provide a method for forming a P-type compound semiconductor layer that does not require an annealing process by blocking the bonding of P-type impurities and hydrogen when forming the P-type compound semiconductor layer.

In order to achieve the above technical problem, the present invention discloses a method for forming a P-type compound semiconductor layer. A method of forming a P-type compound semiconductor layer according to an aspect of the present invention includes raising a substrate loaded in a reaction chamber to a first temperature. Subsequently, a source gas of a group III element, a source gas of a P-type impurity, and a source gas of nitrogen containing hydrogen are supplied into the reaction chamber to grow a P-type compound semiconductor layer. In addition, after the growth of the P-type compound semiconductor layer is completed, supply of the source gas of the group III element and the source gas of the P-type impurity is stopped, and the temperature of the substrate is cooled to the second temperature.

Then, the supply of the source gas of nitrogen containing hydrogen is stopped at the second temperature, and nitrogen gas is added to cool the substrate temperature to room temperature. Therefore, the hydrogen is not bonded to the P-type impurity contained in the P-type compound semiconductor layer in the process of cooling the substrate temperature to room temperature by stopping supply of the source gas of nitrogen containing hydrogen in the state cooled to the second temperature. You can prevent it.

Here, the source gas of nitrogen containing hydrogen may be ammonia.

In addition, the second temperature may be 400 to 850 ° C.

The P-type impurity may be magnesium (Mg).

On the other hand, the method for forming a P-type compound semiconductor layer according to an aspect of the present invention, the hydrogen containing nitrogen remaining in the reaction chamber after the supply of the source gas of nitrogen containing hydrogen at the second temperature is stopped The method may further include exhausting the source gas.

Hereinafter, with reference to the accompanying drawings will be described embodiments of the present invention; The following embodiments are provided as examples to sufficiently convey the spirit of the present invention to those skilled in the art. Accordingly, the invention is not limited to the embodiments described below and may be embodied in other forms. In the drawings, widths, lengths, thicknesses, and the like of components may be exaggerated for convenience. Like numbers refer to like elements throughout.

3 is a flowchart illustrating a method of manufacturing a P-type semiconductor according to a preferred embodiment of the present invention, and FIG. 4 is a graph illustrating a method of manufacturing a P-type semiconductor according to a preferred embodiment of the present invention.

According to a preferred embodiment of the present invention, a substrate is loaded into a reaction chamber to produce a nitride semiconductor of group III element, and the temperature of the substrate is raised to a temperature T ₁ for growing a nitride semiconductor layer of group III element. (S101). The temperature T ₁ of the substrate is heated to 1050 ° C., for example, to grow a nitride semiconductor layer of group III element.

As the substrate, sapphire or silicon carbide (SiC) made of an insulating material may be used, but a conductive or semiconductor substrate may also be used. In addition, a buffer layer is formed on the substrate to mitigate lattice mismatch between the dissimilar substrate and the nitride semiconductor layer of the group III element, and the nitride semiconductor layer of the group III element doped with N-type impurities on the resulting buffer layer, that is, the N-type semiconductor. The layer and the active layer are formed sequentially. The buffer layer may be formed of AlN, InGaN, GaN, AlGaN, or the like. The N-type semiconductor layer may be formed without doping impurities, but is preferably formed by doping with impurities such as Si, Ge, Se, S, or Te.

The active layer is preferably formed in a single quantum well (SQW, Single Quantum Well) or multi-quantum well (MQW, Multi Quntum Well) structure.

Subsequently, a source gas of a group III element, a source gas of a P-type impurity, and a source gas of nitrogen containing hydrogen such as ammonia is supplied into the reaction chamber to grow a P-type compound semiconductor layer (S103). As a source gas of Group III element, for example, Tri-Methyl Gallium (TGM) and a source gas of nitrogen (N) are used, for example, a gas containing hydrogen such as ammonia, and a carrier gas (H ₂ or Supplied with N ₂ ). As the source gas of the P-type impurity, for example, Cp ₂ Mg is used when Mg is used as the impurity. As the P-type impurity, Be, Sr, Ba, Zn, etc. may be used in addition to Mg. Meanwhile, although the active layer is formed on the N-type semiconductor layer and the P-type compound semiconductor layer is grown on the active layer, the order may be changed.

When the growth of the P-type compound semiconductor layer is completed, the supply of the source gas of the group III element and the source gas of the P-type impurity is stopped (S105). The substrate on which the P-type compound semiconductor layer is grown is cooled to a predetermined temperature (T ₂ ) (S107). Here, the step of stopping supply of the source gas of the group III element and the P-type impurity source gas may be performed after the cooling step of the P-type compound semiconductor layer is started, or may be performed simultaneously with the start of the cooling step.

On the other hand, since the supply of source gas of nitrogen containing hydrogen is not stopped in the gas supply stop step, the temperature T _{2 at} which the P-type compound semiconductor layer is cooled is P-type impurities and hydrogen in the P-type compound semiconductor layer in the present invention. In the P-type compound semiconductor layer formed is a high temperature is not set, so that the bonding of P-type impurities and hydrogen contained in the source gas of nitrogen is prevented during the cooling step of the P-type compound semiconductor layer There is no need to perform a separate annealing process to remove hydrogen. Here, the cooling temperature T ₂ of the P-type compound semiconductor layer is set in a temperature range of 400 to 850 ° C, for example. It is not preferable to stop the source gas of nitrogen containing hydrogen, such as ammonia, at 400 degrees C or less, since the coupling | bonding of hydrogen and magnesium may occur at the temperature below 400 degrees C.

When the temperature of the substrate on which the P-type compound semiconductor layer is grown is cooled to a predetermined temperature (T ₂ ), the supply of nitrogen source gas containing hydrogen is stopped (S109).

Then, the source gas of nitrogen remaining in the reaction chamber is discharged to the outside (S111). Referring to FIG. 4, the step of discharging the nitrogen source gas is performed for a predetermined time interval P ₂ to P ₃ , and the temperature T ₂ of the substrate remains the same during this time interval P ₂ to P ₃ . . This is to maintain the temperature of the substrate at a temperature that can at least prevent the coupling reaction between hydrogen contained in the nitrogen source gas remaining in the reaction chamber and the P-type impurities of the P-type compound semiconductor layer, and must be maintained at the same temperature. It is not.

To the extent it can be taken out within When stop the supply of the nitrogen source gas containing hydrogen and nitrogen source gas containing hydrogen remaining in the reaction chamber is discharged to the outside (P ₃ point), and the reaction temperature of the substrate chambers, For example, it is cooled to room temperature (S113).

Here, the cooling of the substrate may be performed by stopping the heating and leaving it as it is to be performed by natural convection, or by cooling the reaction chamber by air or water cooling to cool the temperature of the substrate. For example, the gas remaining in the reaction chamber is completely discharged, and a cooling gas, for example, nitrogen (N ₂ ) gas of a component that does not bind with P-type impurities may be injected to cool the substrate.

5 is a schematic longitudinal cross-sectional view of a (Al, Ga, In) N-based compound semiconductor having a P-type semiconductor manufactured according to a preferred embodiment of the present invention.

In the (Al, Ga, In) N compound semiconductor 200 according to the present embodiment, the N layer 230, the active layer 250, and the P layer 270 are formed on the substrate 210. The substrate 210 may be formed of a conductive or semiconductive metal, Si, SiC, GaN, or the like, and may itself function as an N-type electrode. Substrate 210 may also be formed of sapphire or spinel. As described above, a buffer layer (not shown) may be formed between the N layer 230 and the substrate 210.

In this embodiment, the P layer 270, which is a P-type compound semiconductor layer, is formed without an annealing process as described above with reference to FIG. To this end, when the growth of the P layer 270 is completed in the reaction chamber, the supply of the source gas of the group III element and the source gas of the P-type impurity is stopped, and the substrate on which the P-type compound semiconductor layer is grown has a predetermined temperature ( After cooling to T ₂ ), the supply of nitrogen source gas is stopped. Here, the cooling temperature T ₂ of the P-type compound semiconductor layer is set in a temperature range of 400 to 850 ° C, for example. Subsequently, when the nitrogen source gas remaining in the reaction chamber is released to the outside, the P-type compound semiconductor layer 270 is formed by cooling the substrate temperature to the extent that it can be drawn out in the reaction chamber. The P-type compound semiconductor layer formed as described above includes P-type impurities not bonded to hydrogen, and thus, there is no need to perform a separate annealing process for removing hydrogen.

Meanwhile, although the embodiment in which the substrate 210 is disposed adjacent to the N layer 230 has been described with reference to FIG. 5, the present invention is not limited thereto, and the present invention is applicable to a configuration in which the substrate is disposed adjacent to the P layer. Even in such a configuration, the same functions and effects as in the above-described and illustrated embodiments are provided.

And, which it is described in the former part (Al, Ga, In) N-based compound semiconductor, Al _x In _y Ga _{1 -x- y} N (0≤x, y, x + y≤1) in accordance with the present invention; Of course, the compound semiconductor may include, for example, a light emitting diode (LED), a laser diode (LD), a heterojunction bipolar transistor, a field effect transistor, or a photodetector. In addition, it is applicable to various fields.

6A and 6B are views for explaining the effect of the method of forming a P-type compound semiconductor layer according to a preferred embodiment of the present invention, and show an atomic force microscope (AFM) image.

If the supply of ammonia gas is stopped immediately after the formation of the P-type semiconductor layer, Ga evaporates due to rapid cooling, thereby damaging the surface of the P-type semiconductor layer. 6A illustrates surface damage of a light emitting diode wafer due to such Ga evaporation.

However, according to the method of forming a P-type semiconductor layer according to the preferred embodiment of the present invention, after the P-type semiconductor layer is formed, the substrate is cooled to a predetermined temperature (T ₂ ) and then the supply of nitrogen source gas containing hydrogen is stopped. In addition, since the temperature T ₂ is maintained for a predetermined time interval, rapid cooling of the substrate can be prevented and damage to crystals can be prevented.

FIG. 6B is an atomic microscope image of the surface of a light emitting diode wafer formed by the method of forming a P-type semiconductor layer according to the present invention, and unlike the wafer surface of FIG. 6A, it can be seen that there is no damage to the wafer surface.

According to the exemplary embodiments of the present invention, the formation of the P-type compound semiconductor layer may appropriately block the bonding of the P-type impurity and hydrogen, and thus, there is no need to perform a separate annealing process, and P-type having low resistance even without the annealing process. It is possible to provide a P-type semiconductor manufacturing method capable of manufacturing a compound semiconductor.

In the present invention, the annealing process performed in the conventional P-type semiconductor manufacturing method can be omitted, thereby simplifying the manufacturing process of the compound semiconductor device and reducing the time required for manufacturing.

In addition, after the P-type semiconductor layer is formed, the substrate is cooled to a predetermined temperature, and then the supply of hydrogen-containing nitrogen source gas is stopped and the temperature is maintained for a predetermined time to prevent damage to the crystals.

Claims (5)

Raising the substrate loaded in the reaction chamber to a first temperature; Growing a P-type compound semiconductor layer by supplying a source gas of group III element, a source gas of P-type impurity, and a source gas of nitrogen containing hydrogen into the reaction chamber; After the growth of the P-type compound semiconductor layer is completed, stopping supply of the source gas of the group III element and the source gas of the P-type impurity, and cooling the temperature of the substrate to a second temperature; Stopping supply of the source gas of nitrogen containing hydrogen at the second temperature; And Cooling the substrate temperature to room temperature; forming a P-type compound semiconductor layer. The method for forming a P-type compound semiconductor layer according to claim 1, wherein the source gas of nitrogen containing hydrogen is ammonia. The method of claim 1, wherein the second temperature is 400 to 850 ° C. The method of claim 1, wherein the P-type impurity is magnesium (Mg). The method of claim 1, further comprising discharging the source gas of nitrogen containing hydrogen remaining in the reaction chamber after stopping supply of the source gas of nitrogen containing hydrogen at the second temperature. Compound semiconductor layer formation method.

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