JP3210840B2 - Semiconductor liquid phase epitaxial equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid phase epitaxial device for a III-V compound semiconductor, and more particularly to a vertical semiconductor epitaxial device for a substrate.

[0002]

2. Description of the Related Art FIG. 6 is a diagram for explaining a conventional substrate vertical semiconductor liquid phase epitaxial apparatus and its operation. FIG. 6A is a longitudinal sectional view showing a state before the start of crystal growth. (b) is a longitudinal sectional view showing a state during crystal growth.

[0003] A conventional vertical semiconductor liquid-phase epitaxial device (hereinafter, simply referred to as "epitaxial device") is a growth type in which a growth chamber 2 is formed on a bottom plate 1 serving as a base for supporting the whole. A boat 3 is provided so as to be able to reciprocate in a fixed direction (left-right direction in the figure).
The upper member 6 in which the melt reservoir 5 for storing the melt 4 of the crystal raw material is formed is disposed on the upper portion. These systems are housed in a quartz tube in an electric furnace (not shown) and are controlled in temperature.

[0004] An operating rod 7 is formed at one end of the growth boat 3.
The growth boat 3 is moved in the horizontal direction. A fixing jig 9 in which a plurality of grooves 8 are formed at predetermined intervals in the moving direction of the growth boat 3 is arranged on the bottom surface in the growth chamber 2 of the growth boat 3. A substrate 10 on which a crystal surface is grown on the front side, and a back plate 11 which is in close contact with the back surface of the substrate 10 and prevents crystal growth on the back surface, are held vertically. In FIG.
0 and a state in which the back plate 11 is held vertically.

The melt reservoir 5 formed in the upper member 6 has a melt drop port 12 formed therein. Melt drop port 1
2 is a state shown in FIG. 6A (a state before the start of crystal growth).
Thus, the upper surface of the growth boat 3 is closed. When the growth boat 3 is moved to the position shown in FIG. 6B, the melt drop port 12 and the growth chamber 2 communicate with each other. At this point, the melt 4 in the melt reservoir 5 grows. Drop into chamber 2 for crystal growth (epitaxial growth)
Is performed.

Next, the procedure of crystal growth using the epitaxial device having the above-described structure will be described with reference to the example of crystal growth of GaAs. Here, for example, a gallium arsenide (GaAs) substrate is used as the substrate 10.

First, a fixing jig 9, a substrate 10, and a back plate 11 are arranged in the growth chamber 2 of the growth boat 3. Here, one end of one back plate 11 sandwiched between the back surfaces of two substrates 10 is fitted and held in each groove 8 of the fixing jig 9.

Before starting the crystal growth, the position of the growth boat 3 is as shown in FIG. In this state, the crystal raw material (G) to be grown in the melt reservoir 5 of the upper member 6
a, GaAs polycrystal, dopants such as Si, etc.), and these systems are heated to a specific temperature (90 degrees Celsius) in an H ₂ atmosphere.
(0 to 1000 ° C.) to sufficiently melt the crystal raw material contained in the melt reservoir 5.

Next, the growth boat 3 is moved by the operating rod 7 to the state shown in FIG. 6B, and a melt (Ga, GaAs polycrystal, Si) obtained by melting the crystal raw material in the melt reservoir 5 is obtained.
, Etc.) is dropped into the growth chamber 2 from the melt drop port 12, and then the temperature is gradually lowered to make GaAs.
Is grown on the surface of the substrate 10.

[0010]

However, as shown in FIG. 8, the epitaxial growth wafer manufactured by the above-described epitaxial apparatus, that is, the substrate 10 having the epitaxial growth layer 13 formed on the surface, A protruding abnormal growth portion 13a occurred near the contact portion 14 (see FIG. 7) on the surface of the substrate 10, and an ungrown portion 10a occurred in a portion of the fixing jig 9 held by the groove 8. .

The reason for the occurrence of the abnormal growth portion 13a is as follows.
The fixing jig 9 is in contact with the surface of the substrate 10 during the crystal growth by the slow cooling method.

The material of the substrate 10 and the fixing jig 9 (substrate: gallium phosphide, gallium arsenide, fixing jig: graphite) are different from each other.
The cooling rate during crystal growth is slightly different due to such a large difference in thermal conductivity. That is, since the thermal conductivity of the fixing jig 9 is higher than the thermal conductivity of the substrate 10, the fixing jig 9 is
With respect to 0, it acts as a cooling medium, and the crystal growth of the substrate portion near the contact portion 14 is faster than other portions (the substrate portion where normal crystal growth is performed). As a result, abnormal growth occurs in a protruding manner.

The fixing jig 9 also acts as a cooling medium for the molten liquid (mainly gallium Ga) 4, and the molten liquid 4 is cooled at a contact portion thereof, thereby causing a partial temperature difference.
As a result, the crystal growth of the substrate portion near the contact portion 14 becomes faster than that of the other substrate portions, which causes abnormal growth to form a projection. FIG. 9 shows the thermal conductivity characteristics of gallium and graphite.

The reason why the ungrown portion 10a occurs is that the substrate 10 is placed in the groove 8 of the fixing jig 9 during crystal growth. Therefore, the crystal portion is grown without immersing the substrate portion in the groove 8 in the melt 4.

That is, the portion where the substrate 10 is held is masked by the groove 8 of the fixing jig 9, so that the crystal cannot be grown and the ungrown portion 10a is formed.

The abnormally grown portion 13a and the ungrown portion 10a cause problems such as wafer cracking, cracking, and cracking in a later process.

That is, the surface (epitaxially grown layer side) of the epitaxially grown wafer is polished by a polishing step in a later step, and as shown in FIG. When the wafer surface is polished by applying a pressure 15 from above through the polishing plate 17, the pressure applied to the epitaxially grown wafer by the abnormally grown portion 13a becomes non-uniform (pressure is applied to the abnormally grown portion 13a), causing the wafer to crack. It became.

Further, since the thickness of the epitaxial growth layer 13b of the ungrown portion 10a is thinner than the portion where other normal epitaxial growth layer thickness is formed, it does not contact the normal plate 16 in the polishing step, and It became extremely weak, causing cracks and cracking of the wafer. These cracks and cracks may cause cracks in the wafer during further post-process operations.

The above-described wafer cracking is one of the troublesome factors in the work of the wafer processing step, and lowers the work efficiency. That is, one piece becomes two pieces or three pieces by breaking the wafer,
The number of times of processing increases.

In view of the above problems, an object of the present invention is to provide an epitaxial growth apparatus capable of manufacturing an epitaxially grown wafer having no abnormally grown portion and an ungrown portion which cause a wafer crack.

[0021]

According to a first aspect of the present invention, there is provided a semiconductor liquid phase epitaxial apparatus comprising: an upper member having a melt reservoir for storing a melt of a crystal raw material; and a growth chamber for accommodating a substrate. A formed growth boat, a back plate disposed in the growth chamber and in close contact with the back surface of the substrate to prevent crystal growth on the back surface, and a groove for vertically holding the back plate and having a thermal conductivity of the substrate. A jig having a larger thermal conductivity, and in an electric furnace heated to a constant temperature, the melt stored in the melt reservoir is dropped into the growth chamber, and then cooled. A semiconductor liquid phase epitaxy apparatus for growing crystals on a substrate surface, wherein the back plate includes a fitting portion that fits into a groove of the jig, and a holding portion that holds the substrate. It is.

According to a second aspect of the present invention, in the semiconductor liquid phase epitaxy apparatus, the jig has a thermal conductivity larger than a thermal conductivity of the melt, and the holding portion is connected to the fitting portion. Are arranged at a position apart from the surface of the jig in a state of being fitted into a groove of the jig.

Further, in the semiconductor liquid phase epitaxy apparatus according to a third aspect of the present invention, the holding portion holds a corner of a substrate surface and / or a side surface of the substrate.

According to the above configuration, the semiconductor liquid phase epitaxial apparatus according to the first aspect of the present invention includes the fitting portion in which the back plate fits into the groove of the jig, and the holding portion for holding the substrate. With this configuration, the substrate does not come into direct contact with the jig, and the substrate is cooled by the jig during crystal growth due to the difference in thermal conductivity, thereby preventing abnormal growth.

According to a second aspect of the present invention, in the semiconductor liquid phase epitaxy apparatus, the jig has a thermal conductivity greater than a thermal conductivity of the melt, and the holding portion is connected to the fitting portion. Is fitted to the groove of the jig and is arranged so as to be located at a position away from the jig surface, so that crystal growth is caused by the melt cooled on the jig surface due to the difference in thermal conductivity. Can be prevented, and abnormal growth can be prevented.

Furthermore, in the semiconductor liquid phase epitaxy apparatus according to the third aspect of the present invention, the holding portion holds the corner portion of the substrate surface and / or the side surface of the substrate, so that the entire substrate surface is not masked. The crystal can be grown, and the formation of an ungrown portion on the surface of the substrate on which the crystal is grown can be prevented.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a view for explaining a semiconductor liquid-phase epitaxial apparatus of a vertical substrate type according to the present invention and its operation. FIG. 1 (a) is a longitudinal sectional view showing a state before the start of crystal growth. FIG. 2B is a longitudinal sectional view showing a state during crystal growth.

In the present embodiment, the vertical growth type semiconductor liquid phase epitaxial apparatus (hereinafter simply referred to as "epitaxial apparatus") has a growth chamber 22 formed on a bottom plate 21 serving as a base for supporting the whole. An upper member 26 in which a growth boat 23 is provided so as to be reciprocally movable in a fixed direction (left-right direction in the figure), and a melt reservoir 25 for storing a melt 24 of a crystal raw material is formed above the growth boat 23. Are arranged. These systems are housed in a quartz tube in an electric furnace (not shown) and are controlled in temperature.

An operation rod 27 is formed on one end of the growth boat 23, and the operation of the operation rod 27 causes the growth boat 23 to move in the horizontal direction.

A fixing jig 29 in which a plurality of grooves 28 are formed at predetermined intervals in the moving direction of the growth boat 23 is disposed on the inner bottom surface of the growth chamber 22 of the growth boat 23. The groove 28 has a back plate (substrate) provided with a fitting portion 31a fitted and held in the groove 28 and a holding portion 31b for holding the back surface of the substrate 30 on which the front surface is crystal-grown in close contact. The holding plate 31 is vertically held. FIG. 2 shows a state in which the fitting portion 31a of the back plate 31 is fitted and held in the groove 28, and the back plate 31 is vertically placed and held. It should be noted that the fixing jig 29 is, as in the prior art,
4 and a graphite having a thermal conductivity larger than that of the substrate 30.

The holding portion 31b is formed, for example, on the front and back surfaces of the back plate 31, forms an acute angle with the surface which is in close contact with the back surface of the substrate 30, and holds a slope of the surface of the substrate 30 located on the bottom side of the growth chamber 22. And the fitting portion 31a
Are provided above the surface of the fixing jig 29 in a state of being fitted and held in the groove 28. The holding portion 31b may be of any configuration as long as it does not hold the surface of the substrate 30. However, it is desirable to hold the corners of the surface of the substrate 30 as a measure against the substrate falling.

The melt reservoir 25 formed on the upper member 26
Has a melt drop port 32 formed therein. The melt drop port 32 is closed by the upper surface of the growth boat 23 in the state shown in FIG. 1A (before the start of crystal growth). Then, the growth boat 23 is
When it is moved to the position shown in (b), the melt drop port 32 and the growth chamber 22 communicate with each other.
The melt 24 in 5 falls into the growth chamber 22, and crystal growth (epitaxial growth) is performed.

Next, the procedure of crystal growth using the epitaxial device having the above-described configuration will be described with reference to an example of crystal growth of GaAs. Here, as the substrate 30, for example, a gallium arsenide (GaAs) substrate or the like is used.

First, the fixing jig 29, the substrate 30, and the back plate 31 are arranged in the growth chamber 22 of the growth boat 23.

Before the start of crystal growth, the position of the growth boat 23 is as shown in FIG. In this state, crystal raw materials (such as dopants such as Ga, GaAs polycrystal, and Si) to be grown are accommodated in the melt reservoir 25 of the upper member 26, and these systems are placed in a H ₂ atmosphere at a specific temperature (900 ° C. (1000 ° C.) to sufficiently melt the crystal raw material contained in the melt reservoir 25.

Next, the growth boat 3 is operated by the operation rod 27.
Is moved to the state shown in FIG. 1B, and the melt (Ga, GaAs polycrystal,
A melt (mixed melt of a dopant such as Si) 24 is supplied to the melt drop port 3
2 is dropped into the growth chamber 22, and then the temperature is gradually lowered to grow a GaAs crystal on the surface of the substrate 30.

FIG. 3 shows an epitaxial growth wafer formed by crystal growth using the semiconductor epitaxial device of this embodiment. In the figure, 30 is a substrate, and 33 is an epitaxial growth layer.

As described above, in the semiconductor liquid phase epitaxy apparatus of this embodiment, the fitting portion 31 a in which the back plate 31 fits into the groove 28 of the fixing jig 29, and the holding portion 3 for holding the substrate 30.
1b, the substrate 30 is fixed to the fixing jig 2
Thus, the substrate 30 is cooled by the fixing jig 29 during crystal growth due to the difference in thermal conductivity, thereby preventing abnormal growth. Therefore, it is possible to provide an epitaxial growth wafer having no abnormal growth portion due to substrate cooling. Further, since the holding portion 31b is arranged so as to be located away from the surface of the fixing jig 29 in a state where the fitting portion 31a is fitted in the groove 28 of the fixing jig 29, the fixing jig is fixed. Crystal growth can be prevented from being performed in the melt 24 cooled on the surface of the tool 29, and thereby abnormal growth can be prevented. Therefore, it is possible to provide an epitaxially grown wafer having no abnormally grown portion by cooling the melt.

Further, since the holding portion 31b is formed of an inclined surface which forms an acute angle with a surface which is in close contact with the back surface of the substrate 30 and which holds a corner portion of the surface of the substrate 30, crystal growth is performed without masking the entire surface of the substrate 30. As a result, the formation of an ungrown portion on the surface of the substrate on which the crystal is grown can be prevented. Therefore, it is possible to provide an epitaxial growth wafer having no ungrown portion.

As a result, the wafer cracking in the subsequent process caused by the abnormally grown portion and the ungrown portion is eliminated, and the work efficiency in the subsequent process can be improved.

In the above embodiment, there is a concern that the substrate 30 may fall forward from the back plate 31, as shown in FIG. However, since these are immersed in the melt during crystal growth, as shown in FIG.
0 is pushed to the back plate 31 side, and the substrate 30 is
Fixed to 1. Thereby, it can be applied to a rotary epitaxial device.

[0042]

As described above, according to the first aspect of the present invention,
According to the described semiconductor liquid phase epitaxial apparatus, the substrate on which the crystal is grown is arranged without directly contacting the jig,
The jig prevents the substrate from being abnormally grown during the crystal growth due to the difference in thermal conductivity. Therefore, it is possible to provide an epitaxial growth wafer having no abnormal growth portion due to substrate cooling.

According to a second aspect of the present invention, in the semiconductor liquid phase epitaxy apparatus, the holding portion is located away from the jig surface in a state where the fitting portion is fitted into the groove of the jig. Therefore, abnormal growth due to the melt cooled on the jig surface is prevented. Therefore, it is possible to provide an epitaxially grown wafer having no abnormally grown portion by cooling the melt.

Furthermore, in the semiconductor liquid phase epitaxy apparatus according to claim 3 of the present invention, since the holding portion holds the corners of the substrate surface and / or the side surfaces of the substrate, the entire substrate surface is not masked. The crystal is grown. Therefore, it is possible to provide an epitaxial growth wafer having no ungrown portion. As a result, a wafer crack in a post-process caused by the abnormally grown portion and the ungrown portion is eliminated, and work efficiency in the post-process is improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view for explaining a semiconductor liquid phase epitaxial device and an operation thereof according to an embodiment of the present invention, wherein (a) is a diagram showing a state before the start of crystal growth;
(B) is a diagram showing a state during crystal growth.

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is a sectional view showing an epitaxial growth wafer formed by crystal growth using the semiconductor liquid phase epitaxial apparatus shown in FIG. 1;

FIG. 4 is a cross-sectional view showing a state in which the substrate has fallen forward.

FIG. 5 is a cross-sectional view showing a state of a substrate during crystal growth.

FIGS. 6A and 6B are longitudinal sectional views for explaining a conventional semiconductor liquid phase epitaxial apparatus and its operation, wherein FIG. 6A is a view showing a state before the start of crystal growth, and FIG. FIG.

FIG. 7 is an enlarged view of a main part of FIG. 6;

8 is a sectional view showing an epitaxial growth wafer formed by crystal growth using the semiconductor liquid phase epitaxial apparatus shown in FIG. 6;

FIG. 9 is a diagram showing thermal conductivity characteristics of gallium and graphite.

FIG. 10 is a cross-sectional view for explaining a polishing step.

[Explanation of symbols]

 Reference Signs List 21 bottom plate 22 growth chamber 23 growth boat 24 melt 25 melt reservoir 26 upper member 28 groove 29 fixing jig 30 substrate 31 back plate 31a fitting portion 31b holding portion (inclined surface)

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Claims (3)

(57) [Claims] An upper member in which a melt reservoir for storing a melt of a crystal raw material is formed; a growth boat in which a growth chamber for accommodating a substrate is formed; and a growth boat disposed in the growth chamber and in close contact with the back surface of the substrate. A back plate for preventing crystal growth on the back surface, and a jig provided with a groove for vertically holding the back plate and having a thermal conductivity larger than that of the substrate, and the temperature is raised to a constant temperature. In a heated electric furnace, in a semiconductor liquid phase epitaxy apparatus in which a melt stored in the melt pool is dropped into the growth chamber and then cooled to grow crystals on a substrate surface, A semiconductor liquid phase epitaxial apparatus comprising: a fitting portion that fits into a groove of the jig; and a holding portion that holds the substrate. 2. The jig has a thermal conductivity larger than the thermal conductivity of the melt, and the holding portion is configured such that the fitting portion is fitted in a groove of the jig. 2. The semiconductor liquid phase epitaxial apparatus according to claim 1, wherein the semiconductor liquid phase epitaxial apparatus is arranged at a position apart from the surface. 3. The semiconductor liquid phase epitaxial apparatus according to claim 1, wherein the holding portion holds a corner of a substrate surface and / or a side surface of the substrate.