Gas cracking source based on pressurized diversion

Abstract

The invention relates to a gas cracking source based on pressurized diversion, which belongs to the technical field of semiconductors, and comprises a pressurized diversion unit, the pressurized diversion unit is arranged at the front end of a cracking source furnace, and a diversion cavity is formed between the pressurized diversion unit and the cracking source furnace; the supporting part extends into the cracking source furnace through the pressurized flow guide unit, and the hot wire is fixed with the supporting part; and a source furnace rear end beam plate with beam holes is arranged at the tail end of the cracking source furnace. The pressurized flow guide unit comprises a flow guide outer pipe and a flow guide inner pipe, and the flow guide outer pipe is arranged outside the supporting part and connected with the cracking source furnace; one end of the flow guide inner pipe is arranged in the flow guide outer pipe, and the other end extends into the cracking furnace; and the tail end of the flow guide inner pipe is provided with a source furnace internal flow guide hole. A pressurizing and flow guiding structure is arranged, the pressure entering the local area of the front end of the cracking source cavity is increased, and the purposes of guaranteeing the coating stability and improving the coating quality are achieved in cooperation with the flow guiding hole structure and the optimized cracking source furnace.

Description

Technical Field

[0001] The invention belongs to the field of semiconductor technology, and in particular relates to a gas cracking source based on pressurized flow diversion. Background Art

[0002] The internal cavity of the current hot wire gas cracking source is basically a cylindrical cavity with a hot wire inserted in the middle or a hot wire wrapped around the outside of a very thin cylindrical cavity to thermally crack the gas inside the cavity, thereby obtaining an extremely pure atomic flow. The first cracking form has many invalid collisions and low cracking efficiency due to structural limitations. Specifically, the existing gas cracking sources are basically Figure 1 As shown, the gas enters the cracking source cavity from the narrow gas path. Under high vacuum environment, the sudden expansion of space increases the Knudsen number by multiples, and the gas molecules expand with high freedom inside the cavity. The intermolecular collision is almost zero, and the collision basically occurs between the gas molecules and the wall. At this time, since there is no certain constraint and guidance on the direction of molecular flow movement, the collision inside the cavity is chaotic, which will reduce the probability of collision between molecules and hot wires and increase the time it takes for molecules to run to the surface of the hot wire. The second cracking method has high cracking efficiency, but the cylindrical cavity is too thin, and the overall cracking speed is not high.

[0003] In addition, the interior of the cracking source furnace is currently a high vacuum environment, and the gas pressure in the section of the pipeline from the flow valve to the inside of the cracking source cavity is gradually reduced. As the pressure decreases, the fluid movement gradually changes from a continuous flow to a free molecular flow. After the gas enters the source furnace, it is a free molecular flow, and each molecule moves irregularly and is basically in a diffuse reflection state after colliding with the inner wall of the source furnace. The cracking efficiency is low, the cracking is uneven, and the energy utilization rate is low, resulting in unstable product quality. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a gas cracking source based on pressurized diversion, and a pressurized diversion structure is set up to increase the pressure of a local area at the front end of the cracking source cavity, so that the pressure in this area can be increased and the fluid state in this area can be kept in a transitional flow state as much as possible. The diversion hole structure at the rear end is used to better guide the fluid entering the cracking source cavity, and the optimized internal structure of the cracking source furnace is used to achieve the maximum cracking efficiency, thereby achieving the purpose of ensuring the stability of the coating and improving the coating quality.

[0005] A gas cracking source based on pressurized flow diversion comprises a pressurized flow diversion unit, which is arranged at the front end of a cracking source furnace, and a flow diversion cavity is formed between the pressurized flow diversion unit and the cracking source furnace; a support part extends into the cracking source furnace through the pressurized flow diversion unit, and a hot wire is fixed to the support part; a source furnace rear end beam plate is arranged at the end of the cracking source furnace, and a beam hole is opened on the source furnace rear end beam plate.

[0006] The pressurized flow guiding unit comprises an outer flow guiding tube and an inner flow guiding tube. The outer flow guiding tube is arranged outside the supporting part and connected to the cracking source furnace. One end of the inner flow guiding tube is arranged inside the outer flow guiding tube, and the other end of the inner flow guiding tube extends into the cracking furnace and is arranged outside the supporting part. A source furnace internal flow guiding hole is opened at the end of the inner flow guiding tube.

[0007] The flow guide holes inside the source furnace are evenly distributed along the circumference of the flow guide inner plate and are inclinedly arranged.

[0008] The number of the flow guide holes inside the source furnace and the angle between the central axis of the flow guide holes inside the source furnace and the central axis of the flow guide outer tube are changed accordingly according to the diameter and length of the reaction chamber of the cracking source. The basis for the change is to minimize the ineffective collision between the molecules and the inner wall of the shell and the supporting parts.

[0009] A spiral flow guide channel is provided inside the front end of the flow guide outer tube, so that the molecular flow entering through the flow valve forms a swirl flow.

[0010] The beam hole on the beam plate at the rear end of the source furnace is an oblique cone hole, the side facing the cracking source furnace is the large diameter end, and the side facing the coating cavity is the small diameter end.

[0011] The front end of the pressurized flow guiding unit is in an inverted cone shape.

[0012] By means of the above technical solution, the present invention has at least the following beneficial effects:

[0013] The present invention is provided with a pressurized flow guiding unit with a swirl structure, which increases the fluid velocity and spirality after the valve, and then increases the gas pressure in the local area after the valve, so as to facilitate the front end flow guiding cavity inside the cracking source furnace to play a better flow guiding role. The inclination angle of the flow guiding hole inside the source furnace is to reduce the number of invalid collisions between molecules and the wall surface, so that they can effectively collide with the hot wire after fewer collisions to produce thermal cracking, thereby improving the cracking rate and cracking efficiency inside the entire cracking source furnace. At the same time, a source furnace rear end beam plate with an oblique cone hole is set at the rear end of the cracking source furnace, and the atomic flow after cracking is rectified to a certain extent before entering the coating area, thereby ensuring the uniformity of the coating to a certain extent.

[0014] Compared with the prior art, the present invention adds a pressurized guide structure to increase the probability of collision between gas molecules and hot wires and improve the overall efficiency of thermal cracking; reduce the number of invalid collisions and shorten the time for the fluid to react with the hot wire after entering the cavity; add a beam plate at the tail of the cracking source to guide the post-reaction flow to a certain extent, add a beam plate for rectification, and improve the uniformity of coating; it serves as a reference for the forward design of the gas cracking source furnace. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic diagram of an existing gas cracking source;

[0016] Figure 2 A schematic diagram of a gas cracking source based on pressurized flow diversion provided by the present invention;

[0017] Figure 3 It is a schematic diagram of the outer guide tube of the pressurized guide unit in the present invention;

[0018] Figure 4 A schematic diagram of mixed reflection formed by the working state of the gas cracking source of the present invention;

[0019] Figure 5 It is a schematic diagram of the dimensions of the gas cracking source of the present invention;

[0020] Figure 6 Schematic diagram of the beam plate at the rear end of the source furnace in the present invention Figure 1 ;

[0021] Figure 7 Schematic diagram of the beam plate at the rear end of the source furnace in the present invention Figure 2 ;

[0022] in,

[0023] 1- spiral flow guide, 2- pressurized flow guide unit, 21- flow guide outer tube, 22- flow guide inner tube, 3- axial seal, 4- fastening bolt hole, 5- annular seal, 6- flow guide hole inside the source furnace, 7- supporting part, 8- hot wire, 9- beam plate at the rear end of the source furnace, 10- beam hole, 11- swirl, 12- mixed reflection area. DETAILED DESCRIPTION

[0024] In order to better explain the present invention and facilitate understanding, the technical solutions and effects of the present invention are described in detail below through specific implementation modes in conjunction with the accompanying drawings.

[0025] like Figure 1-Figure 7As shown, a gas cracking source based on pressurized flow diversion is installed at the outlet end of the flow valve, including a pressurized flow diversion unit 2, which is arranged at the front end of the cracking source furnace, and a flow diversion cavity is formed between the pressurized flow diversion unit 2 and the cracking source furnace, and a support part 7 extends into the cracking source furnace through the pressurized flow diversion unit 2, and a hot wire 8 is fixed to the support part 7; a source furnace rear end beam plate 9 is arranged at the end of the cracking source furnace, and a beam hole 10 is opened on the source furnace rear end beam plate 9. The pressurized flow diversion unit 2 includes a flow diversion outer tube 21 and a flow diversion inner tube 22, and the flow diversion outer tube 21 is arranged outside the support part 7 and connected to the cracking source furnace, and a spiral flow diversion channel 1 is opened inside the front end of the flow diversion outer tube 21, so that the molecular flow entering from the flow valve forms a swirl 11. One end of the inner flow guide tube 22 is connected to the inner flow guide tube 21 through an annular axial seal 3, and the outer flow guide tube 21 and the inner flow guide tube 22 are mutually clamped and sealed by a sealing ring; the other end of the inner flow guide tube 22 extends into the cracking furnace and is arranged outside the support part 7. The inner flow guide tube 22 and the shell of the cracking source furnace are fastened by an annular sealing ring 5 and bolts through the fastening bolt hole 4. The end of the inner flow guide tube 22 is provided with a source furnace internal flow guide hole 6, and the source furnace internal flow guide holes 6 are uniformly distributed along the circumference of the inner flow guide plate and are tilted, that is, the angle between the centerline axis of the source furnace internal flow guide hole 6 and the central axis of the inner flow guide tube 22 is an acute angle, so as to rectify the airflow to a suitable direction, so as to minimize the number of collisions with the inner wall of the shell and the support part 7, and reach the surface of the hot wire 8 as soon as possible to effectively collide with it and produce catalytic thermal cracking. The internal flow guide hole 6 of the source furnace forms a molecular flow guide part at the end of the flow guide inner tube 22, and the total flow inside the flow guide cavity is corrected and distributed through a plurality of inclined internal flow guide holes 6 of the source furnace. After rectification and distribution, the flow of each branch enters the reaction chamber of the cracking source furnace in a fixed direction. The initial velocity direction of the molecular flow in the reaction chamber is the outflow direction from the internal flow guide hole 6 of the source furnace. After one or more rounds of collision with the support part 7 and the inner wall of the shell (the mixed reflection area 12 includes specular reflection and diffuse reflection), it reaches the surface of the hot wire 8 and undergoes thermal cracking, and the molecules are cracked into atoms and enter the coating chamber after rectification through the beam plate 9 at the rear end of the source furnace.

[0026] The number of the internal flow guide holes 6 of the source furnace and the angle between the central axis of the internal flow guide holes 6 of the source furnace and the central axis of the flow guide outer tube 21 are changed accordingly according to the diameter and length of the reaction chamber of the cracking source, and the basis for the change is to minimize the ineffective collision between the molecules and the inner wall surface and the supporting parts of the shell. The distribution form and angle inclination of the internal flow guide holes 6 of the source furnace in the flow guide inner tube 22 should be based on the existing spatial layout to minimize the pressure loss and the reflux area in the tube, so as to improve the air intake efficiency and improve the overall cracking rate of the cracking source. The specific structural design requirements are as follows:

[0027] The function of the flow guide hole 6 inside the source furnace is to constrain the direction of the molecular flow so that it will collide with the inner wall of the cracking source furnace after flowing in a fixed direction and perform specular reflection or diffuse reflection on it. Figure 4 The mixed reflection area 12 is shown, in which different dotted line patterns represent the specular reflection or diffuse reflection that occurs. The design principle of the structural form of the source furnace internal guide hole 6 is to make the first collision position of the molecular flow with the cracking source furnace inner wall just beyond the projection point A on the cracking source furnace inner wall at the junction of the support and the hot wire 8 or beyond point A. The axial distance from the center of the first row of source furnace internal guide holes 6 in the guide cavity, that is, the row of source furnace internal guide holes 6 farthest from the end of the cracking source furnace, to point A is L, as shown in FIG. Figure 5 As shown, the design criteria follow the following formula:

[0028]

[0029] Wherein, D1 is the inner diameter of the cracking source furnace, D2 is the diameter of the hot wire 8, and the initial guide angle between the molecular flow and the cracking source furnace, that is, the angle between the molecular flow flowing out of the first row of guide holes 6 inside the source furnace and the axial direction of the guide inner tube 22 is α.

[0030] The beam hole 10 on the beam plate 9 at the rear end of the source furnace is an oblique cone hole, with the side facing the cracking source furnace as the large diameter end and the side facing the coating chamber as the small diameter end, and its inclination angle is set according to the size and distance of the rear coating substrate. The beam plate 9 at the rear end of the source furnace has one function: to reflect some molecules that have not collided with the hot wire 8 back to the surface of the hot wire 8 to cause thermal cracking; another function is to rectify the fluid after the reaction so that it can expand in the corresponding direction after entering the coating area to ensure the uniformity of the coating to a certain extent.

[0031] The front end of the pressurized flow guiding unit 2, i.e., the front end of the flow guiding outer tube 21, is inverted cone shape, and the conical area is simultaneously added with the swirl 11 channel, so as to accelerate the gas after passing through the flow valve, increase the amount of gas entering the narrow slit path, i.e., the flow guiding cavity, and then pressurize the local gas in the narrow slit path. The process of gas flowing out from the flow valve to the cracking source chamber and then to the coating chamber is a process in which the pressure is gradually reduced to a high vacuum state. The higher the vacuum degree, the more difficult it is to control the flow state of the gas molecules. In order to enable the gas molecules inside the cracking source furnace to collide with the hot wire 8 more quickly, the gas should be kept in the transition flow state as much as possible before entering the cracking source furnace, and the pressurized flow guiding unit 2 is set at the front end, so that the gas flow direction can be better controlled.

Claims

1. A gas cracking source based on pressurized flow diversion, characterized in that: The invention comprises a pressurized flow guide unit (2), the pressurized flow guide unit (2) is arranged at the front end of the cracking source furnace, and a flow guide cavity is formed between the pressurized flow guide unit (2) and the cracking source furnace; a support part (7) extends into the cracking source furnace through the pressurized flow guide unit (2), and a hot wire (8) is fixed to the support part (7); a source furnace rear end beam plate (9) is arranged at the end of the cracking source furnace, and a beam hole (10) is opened on the source furnace rear end beam plate (9).

2. A gas cracking source based on pressurized flow diversion according to claim 1, characterized in that: The pressurized flow guiding unit (2) comprises an outer flow guiding tube (21) and an inner flow guiding tube (22); the outer flow guiding tube (21) is arranged outside the support part (7) and connected to the cracking source furnace; one end of the inner flow guiding tube (22) is arranged inside the outer flow guiding tube (21), and the other end of the inner flow guiding tube (22) extends into the cracking furnace and is arranged outside the support part (7); and a source furnace internal flow guiding hole (6) is opened at the end of the inner flow guiding tube (22).

3. A gas cracking source based on pressurized flow diversion according to claim 2, characterized in that: The flow guide holes (6) inside the source furnace are evenly distributed along the circumference of the flow guide inner plate and are arranged obliquely.

4. A gas cracking source based on pressurized flow diversion according to claim 3, characterized in that: The number of the flow guide holes (6) inside the source furnace and the angle between the central axis of the flow guide holes (6) inside the source furnace and the central axis of the flow guide outer tube (21) are changed accordingly according to the diameter and length of the reaction chamber of the cracking source, and the basis for the change is to minimize the ineffective collision between the molecules and the inner wall surface of the shell and the supporting parts.

5. A gas cracking source based on pressurized flow diversion according to claim 2, characterized in that: A spiral flow guide channel (1) is provided inside the front end of the flow guide outer tube (21), so that the molecular flow entering through the flow valve forms a swirl flow (11).

6. A gas cracking source based on pressurized flow diversion according to claim 1, characterized in that: The beam hole (10) on the beam plate (9) at the rear end of the source furnace is an oblique cone hole, the side facing the cracking source furnace is a large diameter end, and the side facing the coating chamber is a small diameter end.

7. A gas cracking source based on pressurized flow diversion according to claim 1, characterized in that: The front end of the pressurized flow guiding unit (2) is in an inverted cone shape.

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