JPS621359B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid phase epitaxial apparatus for epitaxially growing crystals on an underlying semiconductor substrate from a supersaturated solution. More specifically, the present invention relates to an improvement in the upper end opening of a reactor in a vertical liquid phase epitaxial apparatus.

Conventionally, the upper opening of the reactor in this type of epitaxial apparatus was provided with no closing mechanism, or only with a single shutter or lid, other than an exhaust port to prevent the diffusion of toxic vapors. . For this reason, heat exchange through convection and radiation is actively performed between the outside air and the atmosphere inside the furnace, so a large temperature gradient occurs within the furnace, and a corresponding temperature gradient also occurs within the solution. As a result, (1) the growth from a supersaturated solution causes the solute precipitation rate to vary depending on the temperature difference within the solution, reducing the yield of uniformly grown thin films.

(2) When the steam in the furnace comes into contact with the cold semiconductor substrates brought in through the furnace mouth, they immediately solidify and adhere, leading to a decline in quality.

There were drawbacks such as: Furthermore, as semiconductor substrates have become larger due to recent advances, this trend has become even more severe. This is a particularly serious problem in liquid-phase epitaxial equipment for magnetic bubble memories, in which magnetic garnet thin films are grown from, for example, PbO--B ₂ O ₃ -based solvents.

The present invention was made to solve these drawbacks, and it reduces the heat exchange between the atmosphere inside the furnace and the outside air, equalizes the temperature inside the furnace, and transfers the newly inserted cold semiconductor substrate to the upper part of the furnace. The present invention provides an apparatus that prevents deterioration of quality by preheating and then reacting.

This will be explained in detail below with reference to the drawings. FIG. 1 is a vertical sectional view schematically showing a reactor according to an embodiment of the present invention. In the figure, the reactor has a furnace wall 8 made of a refractory material such as ceramic, and a supersaturated solution 5 of PbO-B ₂ O ₃ system, for example, is housed in a reaction chamber A at the lower part of the furnace. A crucible 4 is placed on a crucible holder 10, and an exhaust port 11 is provided in the reaction chamber A through the furnace wall 8. Above the reaction chamber A, there is a first shutter 1 that opens and closes the furnace opening at the upper end of the reactor, and a second shutter that opens and closes the entrance of the reaction chamber A.
A shutter 2 is provided. Further, an air curtain 3 is provided between the first shutter 1 and the second shutter 2. This air curtain 3 is designed to form a preheating space 12 between the air curtain 3 and the first shutter 1 for preheating the semiconductor substrate 6 inserted from the furnace mouth together with the substrate holder 7.
It is provided below the first shutter 1 at a predetermined distance from the first shutter. This interval is selected to be about 100 to 200 mm, for example, when the inner diameter of the reactor is 125 to 150 mm. In that case, the air curtain 3 and the second shutter 2 below it
The distance between the two is selected to be approximately 50 to 100 mm. A heater 9 is provided over the entire outer periphery of the furnace wall 8.

In this embodiment, the first shutter is divided into left and right halves.
It opens and closes by sliding the shutter plates left and right, respectively, and when closed, the suspension shaft 7-1 of the board holder 7
A notch is provided at a position that overlaps with the central axis of the reactor when the reactor is closed, so that a small hole 13 passing through the reactor remains. Note that a structure in which a shutter plate divided into 2 to 4 parts is rotated about a vertical shaft provided outside the furnace wall 8 to open and close may also be used. The second shutter is installed at the entrance of the reaction chamber A, and the shutter plate is divided into left and right halves, and each side is opened and closed by rotating with two rotation shafts 2-1 installed horizontally in parallel with each other. Like the shutter plate of the first shutter, it has a notch for penetrating the hanging shaft. If the horizontal cross section of the reactor is square, the above may be used, but if it is circular, as shown in Figure 2, two sections should be placed on the same horizontal plane and facing each other inside the reactor. A partition plate 2-2 is attached to the furnace wall 8, and the second shutter 2 can be rotated to open and close about the horizontal shaft 2-1 provided on each partition plate 2-2. This second shutter 2
Similarly to the first shutter 1, a notch is formed at a position that overlaps with the central axis of the reactor when closed, and a small hole is formed through which the suspension shaft 7-1 of the substrate holder 7 passes when closed. ing. 3 is an air curtain that blows air or inert gas through the gas inlet 3-1, flows along the cross section of the reactor, and is discharged outside the furnace through the outlet 3-2. The internal atmosphere is completely isolated from the outside air. The heater 9 maintains the entire reactor at a predetermined temperature and also heats the preheating space in the reactor above the air curtain to preheat the newly inserted cold semiconductor substrate to the required temperature. Exhaust port 1
No. 1 is one in which harmful gases generated during the reaction are sucked and discharged without being diffused into the atmosphere.

Next, the operation of the apparatus of the present invention will be explained. First, a predetermined solution is put into a crucible, the first and second shutters are closed, and then the heater is energized to maintain the entire reactor at a predetermined temperature. On the other hand, a semiconductor substrate is mounted on the substrate holder. From this state, the substrate holder is inserted into the reactor. First, air is supplied to the air curtain section to operate the air curtain. This air curtain is kept in operation until all operations are completed and the temperature of the reactor is lowered. Next, the first shutter is opened, the substrate holder with the semiconductor substrate mounted thereon is lowered so that its hanging shaft 7-1 is aligned with the axis of the reactor, and the lower end of the substrate holder is stopped above the air curtain. The first shutter is closed. In this state, the semiconductor substrate and the substrate holder are preheated, and when the preheating is completed, the second shutter is opened and the substrate holder and the like are lowered. When the substrate holder has completely passed through the second shutter, this shutter is closed, and the substrate holder and the like continue to descend, stopping when the semiconductor substrate mounted on the substrate holder is completely immersed in the solution in the crucible.

Thereafter, epitaxial growth is performed in a liquid phase for a predetermined period of time, and harmful gases generated during this period are sucked through the exhaust port 11, rendered harmless by a treatment device (not shown), and then released. After epitaxial growth is complete, the operations can be performed in the reverse order of insertion.
When the substrate holder comes to the preheating space, it is preferable to stop heating this part by the heater, allow the substrate holder and the semiconductor substrate to slowly cool down, and then open the first shutter and take them out into the outside air.

As described above, by providing a multiple shutter mechanism including a preheating space in the upper part of the reactor, there is no contact between the atmosphere in the furnace below the bottom shutter and the outside air, and the atmosphere in the furnace is stabilized. Therefore, heat release from inside the furnace is blocked, so the temperature distribution inside the furnace becomes uniform, and therefore the temperature distribution in the solution also becomes uniform, making it easier to control the epitaxial growth temperature and making it easier to grow a uniform film. Become. Also, since it is possible to increase the amount of solution, it is also possible to increase the number of semiconductor substrates that can be mounted at one time.
Improves work efficiency. Furthermore, by providing an air curtain, not only can the intrusion of outside air be blocked, but also the harmful gases generated inside can be made harmless without being released into the atmosphere, so it is possible to proceed with the work safely.

As described above, the present invention not only eliminates the drawbacks of the prior art, but also realizes many advantages, and is extremely effective in practice.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view schematically showing the reactor of the present invention, and FIG. 2 is a vertical cross-sectional view of a second shutter portion of the round reactor. In the figure, 1 is a first shutter, 2 is a second shutter, 3 is an air curtain, 8 is a reactor wall, 9 is a heater, and 12 is a preheating space.

Claims (1)

[Claims] 1. A vertical liquid phase epitaxial growth apparatus configured to epitaxially grow crystals on a semiconductor substrate from a supersaturated solution contained in a container installed at the bottom of a reactor. The reactor includes a first shutter for opening and closing the reactor port at the upper end of the reactor above the reaction chamber in which the solution container is installed and an exhaust port is provided;
The first shutter is provided substantially horizontally below the first shutter, and is designed to form a preheating space between the first shutter and the first shutter for preheating the semiconductor substrate inserted through the furnace opening. An air curtain mechanism is provided at a predetermined distance from the shutter, and a second shutter is provided below the air curtain mechanism to open and close the entrance of the reaction chamber, and the entire outer periphery of the reactor is provided. 1. A vertical liquid phase epitaxial growth apparatus, characterized in that a heater is provided over the entire length of the apparatus. 2. The first shutter includes two left and right shutter plates each having a notch formed at a position overlapping the central axis of the reactor when closed,
2. The vertical liquid phase epitaxial growth apparatus according to claim 1, wherein these shutter plates are configured to slide left and right to open and close the furnace opening. 3. The first shutter includes two to four shutter plates each having a notch formed at a position overlapping with the central axis of the reactor when closed, and these shutter plates are provided on the outside of the reactor wall. or 4
2. The vertical liquid phase epitaxial growth apparatus according to claim 1, wherein the vertical liquid phase epitaxial growth apparatus is configured to open and close the furnace opening by rotating respectively about the vertical axis of the book. 4. The second shutter includes two left and right shutter plates each having a notch formed at a position overlapping the central axis of the reactor when closed,
Two shutter plates are provided inside the reactor on the same horizontal plane and facing each other.
2. The vertical liquid phase epitaxial growth apparatus according to claim 1, wherein the vertical liquid phase epitaxial growth apparatus is configured to open and close the entrance of the reaction chamber by rotating respectively about the horizontal axis of the book. 5. Two partial partition plates are provided inside the reactor on the same horizontal plane and facing each other, and the second shutter is arranged at a position that overlaps with the central axis of the reactor when closed. It is equipped with two shutter plates divided into left and right sides with notches formed therein, and these shutter plates open and close the entrance of the reaction chamber by rotating around horizontal shafts respectively provided in the partition plates. A vertical liquid phase epitaxial growth apparatus according to claim 1, characterized in that it is configured as follows.