A gas injection device for epitaxial growth system

Abstract

The present invention belongs to the field of crystal epitaxial growth equipment, and specifically relates to a gas injection device for an epitaxial growth system. It includes a reaction chamber, which includes a front cavity and a rear cavity. A horizontal base is provided in the rear cavity. The upper end surface of the base is used to place a substrate, and the lower end is connected to a rotating shaft. The gas injection device is arranged at the front end of the reaction chamber through a front flange. The main body is an air inlet flange, and a second cavity is arranged in the middle. The rear end of the second cavity is connected to the reaction chamber, and the first cavity is connected to the second cavity through a manifold component; the front end of the gas injection device is connected to a sealing plate, and a horizontal protrusion is provided at the rear end of the sealing plate, and the upper surface of the protrusion is a circular arc surface. The exhaust device is arranged at the rear end of the reaction chamber through the rear flange. The present invention improves the growth quality of the epitaxial layer, not only improves the thickness uniformity of the epitaxial layer, but also reduces the generation of crystal defects, so as to meet the market's increasingly stringent requirements for the quality of the epitaxial layer.

Description

Technical Field

[0001] The invention belongs to the field of crystal epitaxial growth equipment, and in particular relates to a gas injection device for an epitaxial growth system. Background Art

[0002] The principle of chemical vapor deposition (CVD) is that chemical gases react chemically under high temperature conditions to grow a layer of crystals on the surface of a wafer substrate. A general chemical vapor deposition silicon epitaxial growth system usually includes the following basic components: a reaction chamber for carrying a wafer substrate, a gas control unit, a time frequency control unit, a heating device, and a wafer handling device.

[0003] The reaction chamber is designed to provide a controllable and safe epitaxial growth environment and is a key component of the silicon epitaxial growth system. The frame material of the chamber can be quartz, stainless steel, aluminum, or even an inert gas atmosphere that does not participate in the reaction. There are three types of conventional epitaxial growth reaction chambers, which are distinguished by the different ways in which the process gas enters. In the horizontal silicon epitaxial growth furnace, the substrate is placed horizontally in the reaction chamber, and the carrier gas carrying the process gas flows into the reaction chamber from one end, passes through the substrate surface horizontally, and is discharged from the other end of the reaction chamber.

[0004] At present, silicon epitaxial growth systems generally use a quartz reaction chamber, and the heating method adopts radiation heating, including infrared heating and ultraviolet heating. The radiation energy is absorbed by the substrate and the base supporting the substrate through the quartz chamber wall, thereby heating the substrate to the desired temperature. The temperature of the quartz reaction chamber is much lower than that of the substrate, so it is called a cold wall epitaxy system. When the cold wall epitaxy system is processed, a carrier gas is usually used to carry the process gas required for the chemical reaction into the reaction chamber. The process gas includes silicon source gas, etching gas, and various doping gases. The most commonly used carrier gas is hydrogen, and helium is sometimes used. The silicon source gas is usually silane or silane chlorinated hydrocarbons. The etching gas is usually used to clean the surface of the substrate at the beginning of the process, usually using hydrogen chloride (HCl). The doping gas is usually one of arsine, phosphine or borane.

[0005] In existing epitaxial growth systems, a series of problems often occur due to the poor quality of the airflow into the reaction chamber. These problems include uneven growth of the epitaxial layer on the substrate surface, the presence of impurity particles on the substrate surface, the formation of a deposition layer on the inner wall of the reaction chamber and the surface of other components in the chamber, which affects normal heating, low gas utilization, slow process reaction speed, etc. These problems are particularly prominent in the single-wafer silicon epitaxial growth system. Compared with multi-wafer epitaxial systems, since only one substrate is processed at a time, if excessive gas is introduced into the reaction chamber, it will inevitably cause great waste. Insufficient gas will lead to a longer reaction time, which will significantly reduce the processing efficiency for single-wafer processing.

[0006] The monolithic silicon epitaxial growth system requires a faster reaction process to shorten the processing cycle of each substrate, and at the same time requires to minimize the deposits on the inner wall of the reaction chamber and other component surfaces other than the substrate, and to be able to remove these deposits in a controlled cleaning manner. Summary of the invention

[0007] The technical problem to be solved by the present invention is to overcome the deficiencies in the prior art and provide a gas injection device for an epitaxial growth system.

[0008] In order to solve the above technical problems, the solution adopted by the present invention is:

[0009] A gas injection device for an epitaxial growth system, comprising a reaction chamber, a gas injection device and an exhaust device;

[0010] The reaction chamber includes a front cavity and a rear cavity. A horizontal base is arranged in the rear cavity. The upper end surface of the base is used to place the substrate. The lower end is connected to a rotating shaft. The rotating shaft extends outside the reaction chamber and is connected to an external driving device.

[0011] The gas injection device is arranged at the front end of the reaction chamber through the front flange; the main body of the gas injection device is an air inlet flange, a second cavity is arranged in the middle, the rear end of the second cavity is connected with the reaction chamber, and the front end surface of the second cavity is a curved surface in the shape of a 1 / 4 arc; a first air inlet is opened at the top of the air inlet flange, a first cavity is arranged above the second cavity, and the first air inlet is connected to the first cavity through a channel; the first cavity includes two parts, namely, a gas buffer cavity A on the right and a gas distribution chamber B on the left; the first cavity is connected to the second cavity through a manifold component; the front end of the gas injection device is connected to a sealing plate, and a horizontal protrusion is arranged at the rear end of the sealing plate, and the upper surface of the protrusion is a circular arc surface, and the shape is adapted to the shape of the front end of the second cavity;

[0012] The exhaust device is arranged at the rear end of the reaction chamber through a rear flange.

[0013] As an improvement, an O-ring or other sealing member is provided between the mating surfaces where the gas injection device contacts the front flange.

[0014] As an improvement, an O-ring or other sealing member is provided between the mating surfaces where the exhaust device contacts the rear flange.

[0015] As an improvement, the manifold component includes a base plate, and a plurality of hole groups are arranged in a straight line in the horizontal direction of the base plate, and each hole group includes a plurality of vertical through holes with a certain interval and the same hole diameter; the hole group located in the middle position has the largest diameter, and the hole groups on both sides are symmetrical about the middle hole group, and the hole diameter of the hole group decreases from the middle to both sides.

[0016] As an improvement, the height of the right end point of the arc surface at the front end of the second cavity is equal to the lower bottom surface of the second cavity, that is, the arc surface at the front side of the second cavity and the lower bottom surface are smoothly transitioned.

[0017] As an improvement, the through-holes on the manifold member are in the shape of a circle, a square or a regular hexagon.

[0018] Compared with the prior art, the technical effects of the present invention are:

[0019] Through unique gas path control and flow rate distribution, the uniformity of the process mixed gas is ensured while achieving uniform contact between the process gas and the substrate deposition area, thereby improving the growth quality of the epitaxial layer. It not only improves the thickness uniformity of the epitaxial layer, but also reduces the generation of crystal defects to meet the market's increasingly stringent requirements for epitaxial layer quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the working principle of the present invention;

[0021] Figure 2 It is a side partial cross-sectional view of the present invention;

[0022] Figure 3 It is a side partial cross-sectional view of the present invention;

[0023] Figure 4 A top view of a manifold component in the present invention;

[0024] Figure 5 The figure is a schematic diagram of a pipeline for providing process gas according to the present invention.

[0025] The accompanying drawings are marked as follows: 1-gas injection device; 11, 12, 13, 14, 15, 35-process gas flow; 2-reaction chamber; 3-exhaust device; 31-front flange; 32-rotation axis; 33-rear flange; 34-matching surface; 35-process gas flow; 4-base; 40-inlet flange; 41-sealing plate; 42-manifold component; 43-protrusion; 45-first gas inlet; 5-substrate; 51, 52, 53, 54, 55, 56, 57, 58, 59-hole group; 6-front cavity; 61, 62, 63, 64, 65-through hole; 7-rear cavity; 71-gas tank; 72, 74-pipeline; 73-valve. Implementation

[0026] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. The one-way straight arrows in the accompanying drawings indicate the gas flow direction.

[0027] like Figure 2 As shown, a gas injection device for an epitaxial growth system provided by the present invention comprises a reaction chamber 2, a gas injection device 1 and an exhaust device 3.

[0028] The reaction chamber 2 includes a front cavity and a rear cavity. A horizontal base 4 is provided in the rear cavity. The upper end surface of the base 4 is used to place a substrate 5. The lower end is connected to a rotating shaft 32. The rotating shaft 32 extends outside the reaction chamber 2 and is connected to an external driving device. The base 4 is driven by the external driving device to rotate or lift. During the process reaction, the base 4 drives the substrate 5 to rotate at a constant speed, so that the substrate 5 is more fully in contact with the process gas flow, which can effectively speed up the reaction speed and improve the system production efficiency while improving the process gas utilization rate and deposition uniformity.

[0029] The gas injection device 1 is disposed at the front end of the reaction chamber 2 through the front flange 31. The exhaust device 3 is disposed at the rear end of the reaction chamber 2 through the rear flange 33. An O-ring or other sealing member is disposed between the mating surfaces where the exhaust device 3 and the rear flange 33 contact each other.

[0030] An O-ring or other sealing member is provided between the mating surface 34 where the gas injection device 1 contacts the front flange 31 to ensure that the gas does not leak between the mating surface and the front flange 31. The sealing member is not shown in the figure.

[0031] The main body of the gas injection device 1 is an air inlet flange 40, with a second cavity in the middle. The rear end of the second cavity is connected to the reaction chamber 2, and the front end surface of the second cavity is a curved surface in the shape of a quarter arc. A first air inlet 45 is provided on the top of the air inlet flange 40, and a first cavity is provided above the second cavity. The first air inlet 45 is connected to the first cavity through a channel, and the first cavity includes two parts, namely, a gas buffer cavity A on the right and a gas distribution chamber B on the left. The first cavity is connected to the second cavity through a manifold component 42. The front end of the gas injection device 1 is connected to a sealing plate 41, and a horizontal protrusion 43 is provided at the rear end of the sealing plate 41. The upper surface of the protrusion 43 is a circular arc surface, and its shape is adapted to the shape of the front end of the second cavity.

[0032] The height of the right end point of the arc surface at the front end of the second cavity is equal to the lower bottom surface of the second cavity, that is, the arc surface at the front side of the second cavity and the lower bottom surface are smoothly transitioned.

[0033] like Figure 3As shown, when the process gas enters the gas injection device 1 from the first gas inlet 45, it first enters the second gas inlet from top to bottom at a certain incident angle through a narrow and long channel. As the channel becomes narrower, the process gas is pressurized before entering the second gas inlet, thereby quickly entering the gas buffer chamber A. After being reflected by the wall of the gas buffer chamber A, the decelerated gas refluxes and mixes with the pressurized gas flow to enter the gas distribution chamber B. Since the process gas is composed of a carrier gas (usually hydrogen) carrying a silicon source gas or other doping gas, when entering the pipeline before the process reaction chamber 2, due to the narrow pipeline and the fast flow rate, the various gases do not have time to fully mix. In view of this, the improved gas injection device 1 is provided with a buffer chamber, and the process gas is further mixed in the gas buffer chamber A to achieve a more uniform state.

[0034] like Figure 4 As shown, the material of the manifold component 42 is stainless steel. The upper part of the manifold component 42 is the lower bottom plate of the gas distribution chamber. There are several groups of holes distributed on the lower bottom plate, namely, hole groups 51 to 59. Hole group 51 is located in the center, and the other hole groups are symmetrically distributed, that is, hole group 52 is symmetrical with hole group 53, hole group 54 is symmetrical with hole group 55, hole group 56 is symmetrical with hole group 57, and hole group 58 is symmetrical with hole group 59. The diameter of each through hole in hole group 51 is the largest, followed by hole groups 52 and 53. The closer to the two ends, the smaller the hole diameter, that is, through hole 61> hole 62> hole 63> hole 64> hole 65. In this embodiment, each through hole is a circular hole. The gas pressure of the process gas in the gas distribution chamber B is uniform. When the process gas passes through hole group 44, in the cross section of the same size, the gas flow through the middle of the hole group, that is, hole group 51, is the largest. According to the formula: flow rate = flow per unit time / cross-sectional area. Similarly, after the airflow enters the second cavity, it presents an airflow distribution with a fast flow velocity in the middle and slow flow velocity at both ends.

[0035] like Figure 5 As shown, the gas tank 71 is the source of process gas supply, and the process gas reaches the valve 73 through the pipeline 72. The valve 73 controls the on-off of the process gas. When the valve 73 is opened, the process gas enters the first gas inlet 45 of the gas injection device 21 through the pipeline 74. The process gas is not limited to the silicon source gas, but can also be hydrogen, nitrogen and other gases used as cleaning or carrier gas, and can also be various doping gases such as phosphine (PH3) and borane (B2H6).

[0036] The principle of the present invention is:

[0037] According to the Coanda Effect: when there is surface friction between the fluid and the surface of the object it flows through, as long as the curvature is not large, the fluid will leave its original flow direction and change its tendency to flow along the protruding surface of the object, that is, the wall adhesion effect. Therefore, after the process comes out from the second air inlet, the airflow that produces the wall adhesion effect on the curved surface makes a 90° turn along the curved surface, flows out of the third air inlet in a horizontal direction, and then passes through the cavity 6 to reach the upper surface of the substrate 5. The process gas flow is as follows Figure 4 As shown by the arrow 35. Due to the wall adhesion effect, the process gas flow 35 maintains the gas flow velocity distribution when it flows out from the hole group 55-59 and is in a laminar flow state.

[0038] like Figure 1 As shown, in the present invention, the process gas enters the reaction chamber 2 through the gas injection device 1, and the process gas flow is shown by arrows 11, 12, 13, 14 and 15. The flow rates of gas flows 11, 12, 13, 14 and 15 are different. The length of the arrow in the figure represents the flow rate of the gas flow. The flow rate of gas flow 13 is higher, followed by gas flow 12 and gas flow 14, and gas flow 11 and 15 are the lowest. The process gas passes through the hollow interior 6 of the reaction chamber 2 with a certain speed distribution, and then passes through the base 4 and the substrate 5 placed on the base 4. A deposition reaction occurs on the surface of the substrate 5, and finally the gas is discharged from the cavity through the exhaust device 3. Before the gas is transported to the exhaust device 3, it passes through different length paths L1, L2 and L3 on the substrate 5.

[0039] Finally, it should be noted that the above examples are only specific embodiments of the present invention. Obviously, the present invention is not limited to the above examples, and there are many variations. All variations that can be directly derived or associated with the content disclosed by a person skilled in the art should be considered as the protection scope of the present invention.

Claims

1. A gas injection device for an epitaxial growth system, characterized in that: It includes a reaction chamber, a gas injection device and an exhaust device; The reaction chamber includes a front cavity and a rear cavity, wherein a horizontal base is arranged in the rear cavity, wherein the upper end surface of the base is used for placing a substrate, and the lower end is connected to a rotating shaft, which extends outside the reaction chamber and is connected to an external driving device; The gas injection device is arranged at the front end of the reaction chamber through the front flange; the main body of the gas injection device is an air inlet flange, a second cavity is arranged in the middle, the rear end of the second cavity is connected with the reaction chamber, the front end surface of the second cavity is a 1 / 4 arc-shaped curved surface, the height of the right end point of the arc curved surface at the front end of the second cavity is the same as the lower bottom surface of the second cavity, that is, the arc curved surface on the front side of the second cavity and the lower bottom surface are smoothly transitioned; a first air inlet is opened at the top of the air inlet flange, a first cavity is arranged above the second cavity, the first cavity includes two parts, namely, a gas buffer chamber A on the right side and a gas distribution chamber B on the left side divided by a manifold component; the manifold component includes a bottom plate, a plurality of hole groups are arranged in a straight line in the horizontal direction of the bottom plate, and each hole group includes a plurality of vertical through holes with a certain interval and the same aperture; located in the middle position The hole group has the largest diameter, the hole groups on both sides are symmetrical about the central hole group, and the hole diameters of the hole groups decrease from the middle to both sides; the first air inlet is connected to the gas buffer chamber A through a channel, and the gas distribution chamber B is connected to the second cavity through a through hole on the manifold component, and the through hole on the manifold component is arranged corresponding to the front end surface of the second cavity; the front end of the gas injection device is connected to a sealing plate, and a horizontal protrusion is provided at the rear end of the sealing plate, and the upper surface of the protrusion is a circular arc surface, and the shape is adapted to the front end shape of the second cavity; wherein, when the process gas enters the gas injection device from the first air inlet, the process gas is pressurized due to the narrowing of the channel connecting the first air inlet and the gas buffer chamber A, and the pressurized gas flow enters the gas buffer chamber A, and after being reflected by the cavity wall of the gas buffer chamber A, the decelerated gas reflux is mixed with the pressurized gas flow and enters the gas distribution chamber B together; The exhaust device is arranged at the rear end of the reaction chamber through a rear flange.

2. The device according to claim 1, characterized in that An O-ring or other sealing member is arranged between the mating surfaces where the gas injection device contacts the front flange.

3. The device according to claim 1, characterized in that An O-ring or other sealing member is arranged between the matching surfaces where the exhaust device contacts the rear flange.

4. The device according to claim 1, characterized in that The through holes on the manifold component are in the shape of a circle, a square or a regular hexagon.

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