Vertical chemical vapor deposition furnace

Abstract

The invention discloses a vertical chemical vapor deposition furnace which comprises a base, an outer pipe and an inner pipe, the outer pipe and the inner pipe cover the base, the inner pipe is located in the outer pipe, a vertical wafer boat and a gas ejector pipe are arranged in the inner pipe, and the gas ejector pipe is located on one side of the wafer boat and extends in the axial direction of the wafer boat. The inner pipe is provided with a gas ejector pipe, the gas ejector pipe is axially provided with gas ejector holes facing the wafer boat at intervals, the side wall, opposite to the gas ejector pipe, of the inner pipe is axially provided with gas outlets at intervals, a gas outlet channel communicated with the outside is arranged between the side wall, provided with the gas outlets, of the inner pipe and the outer pipe, and the top wall of the inner pipe is provided with gas suction holes. The method has the advantages that the thickness consistency of deposited films of wafers at different positions in the furnace is promoted, and the thickness uniformity of the deposited films on each wafer is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor manufacturing equipment, and in particular relates to a vertical chemical vapor deposition furnace. Background Art

[0002] A structure of a vertical chemical vapor deposition furnace in the prior art, such as Figure 1 and Figure 2 As shown, it includes an outer tube 101 and an inner tube 102 arranged inside the outer tube 101. The inner tube 102 serves as a deposition reaction chamber, and is provided with a wafer boat 103 and a jet pipe 105 inside. Wafers are placed vertically at intervals on the wafer boat 103. The number of jet pipes 105 may be one or more depending on the requirements of the deposited film or the process requirements. The jet pipe 105 extends along the axial direction of the wafer boat 103 and is arranged on one side of the wafer boat. The jet pipe 105 has two air inlets 104. Two gases enter the jet pipe 105 at the same time and are premixed before being ejected. The jet port of the jet pipe 105 is a plurality of circular holes arranged vertically at intervals and facing the gap between the wafers. A through hole 107 is provided on the side wall of the inner tube 102 opposite to the jet pipe 105. The through hole 107 is in the shape of a plurality of circular holes or gaps arranged vertically at intervals. An exhaust port 106 is also provided at the bottom of the furnace.

[0003] During the chemical vapor deposition reaction, due to the deadweight of the gas ejected from the jet pipe 105 and the fact that the exhaust port 106 is located at the bottom of the furnace, the suction force at the bottom is relatively large, and the gas ejected from the jet pipe 105 moves slightly in an oblique downward direction (e.g. Figure 1 ), resulting in less airflow in the top area of ​​the furnace tube and more airflow at the bottom, so that the deposited film thickness of wafers at different positions above and below is inconsistent, and the deposited film thickness on each wafer is also uneven.

[0004] At the same time, since the jet ports on the jet pipe 105 and the through holes on the inner tube sidewall are arranged in a vertical direction, the gas ejected from the jet pipe 105 passes through the surface of the wafer 10 (such as Figure 2 ), combined with the fact that the wafer boat will drive the wafer to rotate during chemical vapor deposition, it will eventually cause the film thickness in the center area of ​​the wafer to be higher than that in the surrounding areas. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a vertical chemical vapor deposition furnace capable of promoting the consistent thickness of the deposited film of the wafer, so as to overcome the shortcomings of the prior art.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A vertical chemical vapor deposition furnace comprises a base, an outer tube and an inner tube covered on the base, the inner tube being located inside the outer tube, a vertical crystal boat and a jet pipe located on one side of the crystal boat and extending axially along the crystal boat being arranged inside the inner tube, jet ports facing the crystal boat being arranged at intervals along the axial direction on the jet pipe, air outlets being arranged at intervals along the axial direction on the side wall of the inner tube opposite to the jet pipe, an air outlet channel communicating with the outside being provided between the side wall of the inner tube having the air outlet and the outer tube, and air suction holes being arranged on the top wall of the inner tube.

[0008] By distributing air suction holes on the internal top wall, when gas is sprayed into through the air nozzle of the air jet pipe, an airflow moving toward the internal air outlet is formed in the inner tube, and the gas flowing through the crystal surface in the inner tube can be sucked upward through the air suction holes on the top of the inner tube, which can correct the original trend of the airflow moving slightly obliquely downward, promote the horizontal movement of the airflow in the furnace, and promote the uniform distribution of the airflow in different areas of the furnace, thereby promoting the consistency of the thickness of the deposited film on the wafers at different positions above and below the furnace and the uniformity of the deposited film thickness on each wafer.

[0009] In addition, in the present invention, the jet port and the air outlet are both transversely extending structures. The transversely extending structure may be a row of through holes or a transverse slit. For example, the jet port on the jet pipe is a row of through holes arranged transversely, and the air outlet on the inner pipe is a transverse slit.

[0010] By setting the jet nozzle and the gas outlet into a laterally extended structure, the gas ejected from the jet nozzle will diffuse horizontally across the surface of the wafer. Compared with the concentrated airflow in the prior art, the gas in the inner tube of the present invention is distributed over a wider and more uniform range, thereby making the thickness of the deposited film on the wafer more uniform and reducing the phenomenon of bulging in the center of the deposited film on the wafer.

[0011] Therefore, the vertical chemical vapor deposition furnace of the present invention has the advantages of promoting the consistency of the deposited film thickness of wafers at different positions in the furnace and improving the uniformity of the deposited film thickness on each wafer. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments:

[0013] Figure 1 It is a structural schematic diagram of a vertical chemical vapor deposition furnace in the prior art;

[0014] Figure 2 A top view of a vertical chemical vapor deposition furnace in the prior art;

[0015] Figure 3 It is a structural schematic diagram of a vertical chemical vapor deposition furnace of the present invention;

[0016] Figure 4is a side view of the inner tube of the present invention;

[0017] Figure 5 It is a side view of the injection pipe of the present invention. DETAILED DESCRIPTION

[0018] like Figures 3 to 5 As shown, the vertical chemical vapor deposition furnace of the present invention includes an outer tube 101 , an inner tube 102 , a wafer boat 103 , an air injection pipe 105 , and a base 200 .

[0019] The outer tube 101 and the inner tube 102 are both covered on the base 200. The inner tube 102 is located inside the outer tube 101. A vertical wafer boat 103 is arranged inside the inner tube 102. The base 200 has a rotating mechanism (not shown) for driving the wafer boat 103 to rotate inside the inner tube 102. An air jet 105 is arranged inside the inner tube 102 and is located on one side of the wafer boat 103 and extends along the axial direction of the wafer boat 103. One or more air jets 105 may be arranged depending on the requirements of the deposited film or the process requirements.

[0020] The lower end of the jet pipe 105 has two air inlets 104. Dozens of wafers can be placed on the wafer boat 103 at equal intervals in the axial direction. The jet pipe 105 has jet ports 201 spaced at equal intervals in the axial direction. The jet ports 201 face the gap between adjacent wafers. The inner tube 102 has air outlets 202 spaced at axial intervals on the side wall relative to the jet pipe 105. The air outlet 202 faces the jet ports 201. There is a gap between the side wall of the inner tube 102 and the side wall of the outer tube 101 to form an air outlet channel 108. There is a top channel 204 between the top wall of the inner tube 102 and the top wall of the outer tube 101, which is connected to the air outlet channel 108. An exhaust port 106 connected to the air outlet channel 108 is provided on the base 200.

[0021] In the present invention, the top wall of the inner tube 102 is provided with suction holes 205. In this way, when the vertical chemical vapor deposition furnace of the present invention performs chemical vapor deposition on the wafer, the exhaust port 106 is connected to the external negative pressure generating device. During operation, a certain negative pressure is formed in both the gas outlet channel 108 and the top channel 204. After the gas is injected into the inner tube 102 by the gas outlet on the gas injection pipe 105, the gas passes through the surface of the wafer and flows out through the gas outlet 201 under the action of negative pressure. Since the suction holes 205 are provided on the top wall of the inner tube 102, a certain upward suction force is formed on the top wall of the inner tube 102, which offsets a part of the natural downward force of the gas, corrects the tendency of the gas flow to move slightly obliquely downward, makes the gas flow closer to laminar flow in the horizontal direction to maintain horizontal movement, promotes the uniform distribution of the gas flow in different areas in the furnace, and then promotes the uniform thickness of the deposited film of the wafers at different positions above and below in the furnace and the uniform thickness of the deposited film of each wafer.

[0022] The suction force of the top wall of the inner tube 102 can be adjusted by the number and diameter of the suction holes 205 .

[0023] In other embodiments, the air suction holes 205 on the top wall of the inner tube 102 can be directly connected to another external independent negative pressure generating device through a separate channel to achieve independent control of the suction force on the top wall. For example, the top wall of the inner tube 102 and the top wall of the outer tube 103 share a top wall, so there is no top channel 204. The air suction holes 205 on the top wall of the inner tube 102 are independently connected to an external negative pressure generating device to achieve independent control of the suction force on the top wall of the inner tube 102.

[0024] Since the closer the area inside the inner tube is to the air outlet, the more serious the tendency of the air flow to move diagonally downward, in a preferred embodiment of the present invention, the air suction holes 205 are distributed more densely in the area near the air outlet on the top wall of the inner tube 102 than in the area near the air jet pipe, so that the suction force of the top wall gradually increases from the area near the air jet pipe to the area near the air outlet, so as to achieve a better effect of promoting the air flow to maintain horizontal movement.

[0025] In the present invention, both the air jet 201 and the air outlet 202 are transversely extending structures. The transversely extending structure may be a row of through holes or transverse gaps. Figure 4 As shown, the air outlet 202 on the inner tube 102 is a transverse slit. Figure 5 As shown, the upper air jet opening 201 of the air jet pipe 105 is a row of through holes arranged transversely.

[0026] By designing the jet port 201 and the gas outlet 202 as a laterally extended structure, the gas ejected from the jet port 201 will diffuse horizontally across the surface of the wafer. Compared with the concentrated airflow in the prior art, the gas in the inner tube 102 of the present invention is distributed over a wider and more uniform range, thereby making the thickness of the deposited film on the wafer more uniform and reducing the phenomenon of bulging in the center of the deposited film on the wafer.

[0027] In addition, one of the two air inlets 104 at the lower end of the air jet pipe 105 is located on a straight pipe section 104 a extending from the air jet pipe 105 , and the other is located on a curved pipe section 104 b branching out from the side of the air jet pipe 105 .

[0028] It can be seen from the above detailed description that the vertical chemical vapor deposition furnace of the present invention has the advantages of promoting the consistency of the deposited film thickness of wafers at different positions in the furnace and improving the uniformity of the deposited film thickness on each wafer.

Claims

1. A vertical chemical vapor deposition furnace, comprising a base, an outer tube and an inner tube covered on the base, the inner tube being located inside the outer tube, a vertical wafer boat and an air jet pipe located on one side of the wafer boat and extending axially along the wafer boat being arranged inside the inner tube, air jet ports facing the wafer boat being arranged at intervals along the axial direction on the air jet pipe, air outlets being arranged at intervals along the axial direction on the side wall of the inner tube opposite to the air jet pipe, an air outlet channel communicating with the outside being provided between the side wall of the inner tube having the air outlet and the outer tube, characterized in that: The top wall of the inner tube is provided with air suction holes.

2. The vertical chemical vapor deposition furnace according to claim 1, characterized in that: A top channel communicated with an air outlet channel is provided between the top wall of the inner tube and the top wall of the outer tube, and the air outlet channel is connected to a negative pressure generating device.

3. The vertical chemical vapor deposition furnace according to claim 1, characterized in that: The air jet is a transversely extending structure.

4. The vertical chemical vapor deposition furnace according to claim 1, characterized in that: The air outlet is a transversely extending structure.

5. The vertical chemical vapor deposition furnace according to claim 3 or 4, characterized in that: The transversely extending structure is a row of through holes or transverse gaps.

6. The vertical chemical vapor deposition furnace according to claim 1, characterized in that: The air suction holes are more densely distributed in the area near the air outlet on the top wall of the inner tube than in the area near the air injection pipe.

7. The vertical chemical vapor deposition furnace according to claim 1, characterized in that: The lower end of the air injection pipe is provided with two air inlets.

8. The vertical chemical vapor deposition furnace according to claim 1, characterized in that: One of the air inlets is located on a straight pipe section extending from the air jet pipe, and the other air inlet is located on a curved pipe section branching from a side of the air jet pipe.

9. The vertical chemical vapor deposition furnace according to claim 1, characterized in that: The air suction hole is separately connected to a negative pressure generating device.

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