JPH0463153B2 - - Google Patents

Description

[Detailed Description of the Invention] [Summary] A laminar flow forming means is provided using a gas guide plate inside a gas supply device that has a function of discharging gas in a shower shape, and the introduced gas is directed from the center to the periphery. The flow of gas passing through the device is directed from a low-temperature part to a high-temperature part by forming a laminar flow inside the device and supplying it from the periphery onto a gas diffusion plate disposed on the gas outflow surface. This reduces the amount of powdery reaction products generated and deposited in the gas supply device during vapor phase growth, and prevents the surface of the substrate to be grown due to falling of the powdery reaction products. Prevent contamination.

[Industrial application field]

The present invention relates to a gas supply device used to inject a reactive gas onto a substrate to be processed in a vapor phase reaction, and particularly to a gas supply device that contributes to improving the quality of a grown film during chemical vapor deposition.

Interlayer insulating films such as silicon dioxide (SiO ₂ ) and phosphosilicate glass (PSG) used in semiconductor ICs are mainly formed by chemical vapor deposition (CVD). With higher integration, the interlayer insulating film is becoming thinner, and the wiring layer formed on the interlayer insulating film is also becoming thinner, resulting in a decrease in the quality of the interlayer insulating film. Problems include deterioration of the insulation properties of the interlayer insulating film and disconnection of the wiring layer due to protruding defects in the interlayer insulating film.

This deterioration in film quality and protruding defects in the interlayer insulating film are mostly caused by the CVD equipment that forms the interlayer insulating film, and from the perspective of improving the reliability of highly integrated ICs,
Improvements are requested.

[Conventional technology]

FIG. 2 is a schematic side sectional view of a conventional low pressure CVD apparatus often used for forming the above-mentioned interlayer insulating film.
51 is a growth chamber, 52 is a gas supply pipe, 53 is a gas supply device, 54 is a vacuum exhaust port, 55 is a substrate support with a built-in heater, and 56 is a substrate to be grown.

As shown in the schematic side sectional view shown in FIG. A top plate 58 having a gas supply pipe 52 opened and fixed in the center fixed to the upper end surface of the cylinder body 57
and a first gas diffusion plate 60 having first gas flow holes 59 fixed near the lower end surface of the cylindrical body 57 in parallel with the end surface at a low density; A second gas diffusion plate 62 has fixed second gas flow holes 61 arranged at a high density.

However, in the shower-like gas supply device of the conventional structure, a growth gas made of a mixed gas of, for example, monosilane (SiH ₄ ) and oxygen (O ₂ ) is introduced from the gas supply pipe 52 and heated to, for example, about 400°C. When attempting to grow a SiO ₂ film on the growth substrate 56, the central part of the first gas diffusion plate 60, which is heated to a high temperature by radiant heat from the substrate support 55 and the growth substrate 56, is heated to room temperature. The growth gas 63 collides at high speed to locally cool the gas diffusion plate 60,
A low temperature region 64 is formed in the vicinity thereof.

Then, from the high temperature region 65 in contact with the peripheral portion of the gas diffusion plate 60, a part of the high temperature growth gas in which reactive species are formed in a saturated state at the high temperature flows back to the low temperature region 64 as indicated by an arrow 66 indicated by a chain line. Upon cooling, the reactive species rapidly become supersaturated, forming a powdery state.
Generate SiO ₂ and transfer the SiO ₂ powder 67 to the diffusion plate 60,
62, etc.

In addition, especially when the introduction of the growth gas is stopped, the growth gas stagnant in a space defined by the cylindrical body 57 and the first gas diffusion plate 60 moves freely within the space, Since the high-temperature growth gas enters the low-temperature region and is cooled, the deposition of the SiO ₂ powder 67 becomes more significant.

These SiO ₂ powders 67 are placed on the growth gas 62 when the growth gas is passed through the growth substrate 5.
6 and adheres to the substrate, so that the substrate 5
Crack-like defects 69 in the SiO ₂ film 68 grown on 6
and protruding defects 70 are generated, which causes deterioration of the insulation properties of the interlayer insulating film by the SiO ₂ film 68 and disconnection of the metal wiring layer formed on the SiO ₂ interlayer insulating film. .

Therefore, in the past, the above defects were prevented and semiconductor IC
In order to improve the reliability of manufactured devices such as
Because the gas supply equipment was cleaned frequently,
Problems include an increase in maintenance man-hours for CVD equipment and a significant decrease in throughput.

[Problem that the invention seeks to solve]

The problems to be solved by the present invention are that, as mentioned above, in CVD equipment equipped with a conventional gas supply device, insulation deteriorates due to crack-like or protruding defects in the vapor-grown insulating film, and wiring layer Gas supply equipment requires frequent cleaning to prevent reliability degradation of manufacturing devices due to wire breakage, etc.
The maintenance man-hours for CVD equipment increased and the throughput decreased significantly.

[Means for solving problems]

The above problem consists of a cylindrical body having upper and lower end faces perpendicular to the axis, a top plate having a gas inlet in the center fixed to the upper end face of the cylinder, and a top plate fixed to the lower end face of the cylinder. The gas guide plate is configured by using a gas diffusion plate having a gap between the inside of the cylindrical body and a side wall of the cylindrical body, and directs the gas introduced from the gas inlet from the center of the cylindrical body. a laminar flow forming means for forming a laminar flow toward the peripheral portion, and the gas introduced from the gas inlet passes through the laminar flow forming means and passes through the gap between the gas guide plate and the side wall of the cylinder to the diffusion plate. This problem is solved by the gas supply device according to the present invention, which is characterized in that the gas is supplied to the top and is caused to flow out to the outside via the gas diffusion plate.

[Effect]

That is, in the shower-like gas supply device according to the present invention, each gas introduced from a single gas inlet or a plurality of concentric gas inlet openings in the center of the top plate is individually arranged inside the top plate and the device. The installed gas guide plate guides the gas from the center of the device to the periphery in a thin laminar flow, and the gas flows from the periphery through the gap formed between the inner wall of the device and the periphery of the guide plate. The gas is supplied onto the diffusion plate and flows out through the gas diffusion plate in the form of a shower.

By doing so, the gas flow inside the gas supply device is caused by radiation from the lowest temperature region where it is cooled by the collision of the introduced gas at room temperature, through the medium temperature region near the inner wall of the device that does not receive the cooling directly. Since the flow is unified in one direction from the low temperature part to the high temperature part reaching the gas diffusion plate heated to the highest temperature, the reactive species contained in the gas will not become supersaturated.

Therefore, during vapor phase growth, the amount of powdery vapor grown material generated and deposited in the gas supply device by supersaturated reactive species is greatly reduced, and the amount of powdered vapor that falls from the gas supply device onto the surface of the substrate to be grown is reduced. Since the amount of phase grown material is reduced, crack-like defects and protrusion-like defects in the vapor grown film are significantly reduced.

〔Example〕

The present invention will be specifically described below with reference to a schematic side sectional view a and a schematic plan view b shown in FIG. 1 for an embodiment having two gas inlets.

In Fig. 1, 1 is a cylindrical body made of quartz or the like and having a height of about 5 to 10 mm, with upper and lower end surfaces perpendicular to the axis, and 2 is a ceiling made of quartz or the like fixed to the upper end surface of the cylindrical body 1. plate; 3 is a first gas introduction tube made of quartz or the like that opens and is fixed in the center of the top plate 2; 4 is a second gas introduction tube made of quartz or the like that passes through approximately the center of the first gas introduction tube; An introduction pipe 5 is a second gas introduction pipe 4 which is fixed with its distal end opening in the center, and the second gas introduction pipe 4 extends from the upper end surface of the cylindrical body 2 to approximately the center position of the cylindrical body 1. A first gas guide plate 6 made of quartz or the like is supported in parallel at a distance _d1 of about 1 mm from the bottom of the first gas guide plate 5 by a support means (not shown). A second gas guide plate ₇ made of quartz or the like is supported parallel to the cylindrical body 2 with a distance _d3 of, for example, about 1 mm apart from the lower part of the second gas guide plate 6. It is made of a quartz plate etc. that is fixed to cover the opening, e.g.
A gas diffusion plate in which gas outlet holes 8 of 0.3 mmφ are arranged on a matrix at a pitch of about 3 mm, 9 indicates an arrow indicating a gas flow, and 10 indicates a gas outlet surface.

Note that the first and second gas guide plates 5 and 6 and the cylindrical body 1
The distance d ₄ from the inner surface of the groove is, for example, about 2 mm.

The gas supply device according to the present invention is placed in the reaction vessel as described above, with the gas outflow surface 10 having the gas diffusion plate 7 facing a growth substrate (not shown) heated to, for example, about 420°C. Then, O ₂ gas is introduced from the second gas introduction pipe 4 at a flow rate of, for example, 500 c.c./min, and SiH ₄ gas is introduced from the first gas introduction pipe 3 at a flow rate of 500 c.c./min.
cc/min and carrier gas nitrogen (N ₂ ) gas
A mixed gas of 3l/min flows into the reaction vessel.
A SiO ₂ film with a thickness of about 1 μm was grown on a growth substrate (not shown) under reduced pressure to about 10 Torr.

In this growth process, the third space between the gas diffusion plate 7 and the second gas guide plate 6 is heated by the radiation and conduction heat from the substrate side of the gas supply device to be the highest. The second space between the second gas guide plate 6 and the first gas guide plate ₅ is heated to a temperature T2 of about 250℃, and the first gas guide plate 6 is heated to a temperature _T3 of about 300℃. The first space between the gas guide plate 5 and the upper end surface is heated to a temperature _T1 of about 200°C. Furthermore, a temperature gradient is formed in each space in a direction opposite to the direction of the laminar flow of gas formed in the space. Also, the distance for the above gas inflow amount is
Since the height of each space indicated by d ₁ , d ₂ , and d ₃ is formed sufficiently low to about 1 mm, turbulent flow flowing back from the high temperature part to the low temperature part is prevented from occurring in the laminar flow formed in each space. There's nothing I can do about it. Therefore, the flow of the growth gas in the gas supply device is only along the temperature gradient from low temperature to high temperature, so that almost no deposition of powdered SiO ₂ due to supersaturated reactive species occurs inside the device. It disappears.

Therefore, in this gas supply device, even if the vapor phase growth of the SiO ₂ film with a thickness of 1 μm is performed 30 times or more without cleaning, protrusion defects and cracks of a size and amount that reduce the reliability of the device will occur in the grown film. No defects occurred. This value is
This is a significant improvement compared to cleaning every 10 times, and this greatly improves the throughput of the CVD equipment.

〔Effect of the invention〕

As explained above, according to the present invention, a reactive gas supersaturated with reactive species is not formed in the gas supply device, so that the gas supply device can be used for CVD.
When used in the equipment, the generation and accumulation of powdered reaction products in the gas supply device is extremely reduced, so the frequency of cleaning the gas supply device to ensure the quality of CVD films is significantly reduced. It is possible to reduce maintenance man-hours and improve throughput for CVD equipment.

[Brief explanation of drawings]

Fig. 1 is a side sectional view a and a plan view b schematically showing an embodiment of the present invention, and Fig. 2 is a conventional reduced pressure CVD.
A schematic side sectional view showing the device; FIG. 3 is a schematic side sectional view of a conventional gas supply device. In the figure, 1 is a cylindrical body, 2 is a top plate, and 3 is a first
, 4 is the second gas introduction pipe, and 5 is the first gas introduction pipe.
, 6 is a second gas guide plate, 7 is a gas diffusion plate, 8 is a gas outlet hole, 9 is an arrow indicating a gas flow, and 10 is a gas outlet surface.

Claims (1)

[Scope of Claims] 1. A cylindrical body having upper and lower end faces perpendicular to an axis, a top plate having a gas inlet in the center fixed to the upper end face of the cylindrical body, and a top plate having a gas inlet port at the center thereof, and a lower end face of the cylindrical body. A fixed gas diffusion plate and a gas guide plate having a gap inside the cylindrical body and a side wall of the cylindrical body are used to direct the gas introduced from the gas inlet into the center of the cylindrical body. and a laminar flow forming means for forming a laminar flow toward the peripheral area, and the gas introduced from the gas inlet passes through the laminar flow forming means and diffuses from the gap between the gas guide plate and the side wall of the cylindrical body. A gas supply device characterized in that the gas is supplied onto a plate and is caused to flow out through the gas diffusion plate. 2. A patent characterized in that the gas inlet is composed of a plurality of concentrically formed gas inlets, and the laminar flow forming means is provided individually for the gas introduced from each gas inlet. A gas supply device according to claim 1. 3. The gas supply device according to claim 1, wherein the gas diffusion plate is composed of one or more flat plates having a plurality of gas outflow holes.