Chemical vapor deposition furnace structure

Abstract

The utility model discloses a chemical vapor deposition furnace structure, including the reaction cavity, the heating tray of setting in the reaction cavity, the uniform gas tray of setting in the reaction cavity is located the heating tray top, the conductive cover of cover the uniform gas tray with in the interior formation buffer gas cavity, the cover has the gas inlet, still include with radio frequency generating device of the gas inlet electricity is connected, the reaction cavity side portion has the reaction cavity door, the top of reaction cavity still is provided with the mixing chamber, the mixing chamber has the gas inlet and the gas outlet, the first gas pipe is connected on the gas inlet of mixing chamber, the second gas pipe is still connected on the first gas pipe and is close to the position of gas inlet, the gas outlet of mixing chamber is connected with the gas inlet.

Description

Technical Field

[0001] This utility model belongs to the field of semiconductor manufacturing equipment technology, and in particular relates to a chemical vapor deposition furnace structure for depositing thin films on wafers. Background Technology

[0002] Currently, plasma-enhanced chemical vapor deposition (PECVD) is a commonly used process in semiconductor manufacturing to deposit film structures on wafer surfaces. Existing PECVD furnace structures include a reaction chamber containing a heating plate for placing the wafer, an RF source, etc. Process gases are introduced into the reaction chamber through gas pipes, and a thin film structure is formed on the wafer surface under the action of the RF source.

[0003] Furthermore, process gases are mixtures of various gases, and the types of mixed gases vary depending on the product and the process conditions. Currently, a single gas delivery pipe is used to transport the process gases into the reaction chamber. However, some process gases (such as mixtures containing SiH4 and O2) can react rapidly under specific conditions to generate solid byproducts (such as SiO2 particles). If such process gases are transported within a single pipe for an extended period, the gases may pre-react within the pipe, and the resulting particles will deposit on the pipe wall, gradually causing blockages. Over time, this will reduce equipment efficiency and affect the quality of thin film deposition on the wafer surface. Utility Model Content

[0004] The technical problem to be solved by this utility model is to provide a chemical vapor deposition furnace structure that avoids or reduces gas pipeline blockage, so as to overcome the shortcomings of the existing technology.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A chemical vapor deposition furnace structure includes a reaction chamber, a heating plate disposed within the reaction chamber, a gas equalization plate disposed within the reaction chamber above the heating plate, a conductive cover covering the gas equalization plate to form a buffer gas chamber inside, the cover having an air inlet, and a radio frequency generator electrically connected to the air inlet. The structure is characterized in that: a mixing chamber is further disposed above the reaction chamber, the mixing chamber having an air inlet and an air outlet, a first gas supply pipe connected to the air inlet of the mixing chamber, a second gas supply pipe connected to the first gas supply pipe near the air inlet, and the air outlet of the mixing chamber connected to the air inlet.

[0006] Using the above technical solution, the two pre-reacted gases are respectively transported to the mixing chamber through the first gas supply pipe and the second gas supply pipe, and finally mixed in the mixing chamber. In this way, there will be no problem of clogging the gas supply pipe before mixing. Although there will be a short section of mixed gas near the gas inlet in the first gas supply pipe, the distance is very short and the mixing time before entering the mixing chamber is extremely short, so there is no time to react and form accumulations, and no clogging will occur.

[0007] In a specific embodiment of this invention, the air inlet is connected upward to a conductive lower pipe extending out of the reaction chamber, and the air outlet is connected downward to an insulated upper pipe connected to the lower pipe. The radio frequency generator is connected to the lower pipe via a wire. The insulation of the upper pipe ensures that the radio frequency generator can only apply the radio frequency electric field to the conductive cover and the gas equalization plate to form plasma, but the radio frequency electric field will not be conducted to the mixing chamber, the first gas delivery pipe, or the second gas delivery pipe.

[0008] In a specific embodiment of this utility model, a pin is provided on the heating plate that can extend upward from inside the heating plate.

[0009] In a specific embodiment of this utility model, a shielding cover is also included to cover the reaction chamber and the mixing chamber, and the first gas supply pipe and the second gas supply pipe extend out from the shielding cover.

[0010] In a specific embodiment of this utility model, the material of the connecting pipe is PFA.

[0011] In summary, the chemical vapor deposition furnace structure of this invention has the advantage of avoiding or reducing gas pipeline blockage. Attached Figure Description

[0012] Figure 1 This is a three-dimensional structural diagram of the present invention; Figure 2 This is a partial three-dimensional structural diagram of the present invention after the shielding cover has been removed; Figure 3 This is a schematic diagram of the external structure of the reaction chamber; Figure 4 This is a schematic diagram showing the inside of the reaction chamber after it has been cut open. Figure 5 This is a schematic diagram of the gas distribution disk. Detailed Implementation

[0013] like Figure 1 and Figure 2 As shown, the chemical vapor deposition furnace structure of this invention includes a reaction chamber 100 and a mixing chamber 200. The reaction chamber 100 is fixed to the top of the cabinet 400, and the mixing chamber 200 is located above the reaction chamber 100.

[0014] Among them, such as Figure 3 and Figure 4 As shown, the reaction chamber 100 is equipped with a heating plate 110, a gas distribution plate 120, and a cover 130. The gas distribution plate 120 is positioned above the heating plate 110, with gaps between them. Figure 5 As shown, the gas equalization disk 120 has numerous uniformly distributed gas equalization nozzles 121. A cover 130 covers the gas equalization disk 120 to form a buffer gas chamber 140 inside. The reaction chamber 100, the gas equalization disk 120, and the cover 130 are all made of aluminum. An air inlet 131 is located in the center of the cover 130. A circular baffle 141 is fixed below the air inlet 131 inside the buffer gas chamber 140. This baffle 141 diffuses the incoming process gas to the surrounding area of ​​the chamber. The air inlet 131 extends upwards out of the reaction chamber 100 through a conductive lower pipe 132. A programmable reaction chamber door 101 is also provided on the side of the reaction chamber 100. In this embodiment, the reaction chamber door 101 is a pneumatic door, but it could also be an electric door.

[0015] The bottom of the reaction chamber 100 has a first vacuum port 150, which is connected to a vacuum pump (not shown) via a first extraction pipe 151 located inside the cabinet 400. A first control valve is installed on the first extraction pipe 151. A first vacuum gauge is installed inside the reaction chamber 100 to monitor the vacuum level within the chamber in real time.

[0016] Furthermore, the heating plate 110 is equipped with multiple programmable ejector pins 111 that can extend upwards from inside the heating plate 110. In this embodiment, the ejector pins 111 are pneumatic ejector pins, but they can also be driven in other ways, such as electric ejector pins. Specifically, the cylinder of the pneumatic ejector pin is fixed below the reaction chamber 100, and the piston rod of the pneumatic ejector pin passes through the bottom plate of the reaction chamber in a sealed manner and is connected to each ejector pin 111 through the bracket 111a.

[0017] For example Figure 2 and combined Figure 4As shown, the mixing chamber 200 is made of aluminum and is located above the reaction chamber 100. The mixing chamber 200 has an inlet at the top and an outlet at the bottom. A first gas supply pipe 211 is connected to the inlet, and an upper supply pipe 213, connected to the lower supply pipe 132, is installed downwards from the outlet. A second gas supply pipe 212 is connected to the first gas supply pipe 211 near the inlet. With this structure, the two gases to be pre-reacted are respectively transported to the mixing chamber 200 through the first gas supply pipe 211 and the second gas supply pipe 212. Finally, they are mixed within the mixing chamber 200 to form the process gas. This avoids clogging the gas supply pipes before mixing. Although there is a short section of mixed gas near the inlet on the first gas supply pipe 211, the distance is very short, and the mixing time before entering the mixing chamber is extremely short, insufficient to react and form accumulations, thus preventing clogging. For example, the first gas supply pipe 211 can deliver oxygen alone or a mixture containing oxygen (other gases in the mixture will not react with oxygen), and the second gas supply pipe can deliver SiH4 alone or a mixture containing SiH4 (other gases in the mixture will not react with SiH4).

[0018] In this embodiment, the first gas supply pipe 211, the second gas supply pipe 212, and the lower pipe 132 are all made of 316L stainless steel. The upper pipe 213 is an insulating pipe. In this embodiment, the upper pipe 213 is made of PFA, which, in addition to its insulating properties, also has corrosion resistance.

[0019] In this embodiment, the top of the reaction chamber 100 is provided with a mounting port, which is sealed with a mounting plate 160. The mounting plate 160 is also made of aluminum. The mounting plate 160 has a central hole, on which an insulating flange 161 is sealed and mounted. In this embodiment, the flange 161 is a ceramic disc, which has the characteristics of high temperature resistance and insulation, and prevents electrical conduction to the reaction chamber 100. Three stepped holes 170 are evenly distributed around the central hole along a circular axis on the mounting plate 160. Each of the three stepped holes 170 is provided with an adjusting bolt 171. The head of the adjusting bolt 171 is located above the step, and the screw passes downward through the mounting plate 160. The end face of the head is provided with a hexagonal countersunk hole or a slotted groove for easy insertion of a special tool for turning. The cover 130 is provided with threaded through holes 131 below the positions corresponding to the three stepped holes 170. The screw end of the adjusting bolt 171 is threadedly connected to the threaded through hole 131. In this embodiment, the adjusting bolt 171 is made of ceramic, providing high-temperature insulation and preventing electrical conduction to the reaction chamber 100. A sealing nut 172 is also provided in the stepped hole 170. The sealing nut 172 seals the stepped hole 170, preventing gas leakage from the gap between the adjusting bolt 171 and the stepped hole 170. The sealing nut 172 is also made of aluminum. As is well known, the sealing between the above-mentioned parts can be achieved using high-temperature resistant sealing rings.

[0020] With this structure, the height and level of the gas distribution plate 120 relative to the heating plate 110 can be easily adjusted by turning the adjusting bolts in each stepped hole 170. This ensures that the plasma is effectively deposited on the wafer and that the plasma deposition is uniform, thus helping to ensure the quality of wafer deposition.

[0021] A radio frequency generator 220 is also provided next to the mixing chamber 200. The output terminal of the radio frequency generator 200 is electrically connected to the lower pipe 132.

[0022] In addition, a shielding cover 230 is fixed to the top of the mixing chamber 200, covering the mixing chamber 200 and the radio frequency generator 220. The first gas supply pipe 211 and the second gas supply pipe 212 extend out from the shielding cover. The shielding cover 230 can shield the electromagnetic radiation generated when the equipment is working, avoiding pollution to the environment.

[0023] The above describes the structure of the chemical vapor deposition furnace of this utility model, and its working principle is as follows: The reaction chamber 100 is in a vacuum state during operation. The gases delivered by the first gas supply pipe 211 and the second gas supply pipe 212 are mixed in the mixing chamber 200 to form the process gas, which is then introduced into the buffer chamber 140. The radio frequency generator 220 provides a set power radio frequency power to the gas equalization plate 120 and the cover 130, causing the process gas in the buffer chamber 140 to form plasma. The plasma is sprayed onto the wafer heated by the heating plate 100 below through the gas equalization nozzles 121 on the gas equalization plate 120, thereby depositing a thin film on the wafer surface. The vacuum state in the reaction chamber 100 is formed and closed by computer-controlled opening and closing of the first control valve.

[0024] In this invention, when placing or removing a wafer from the heating plate 110 using the electric fork 310, the ejector pin 111 needs to be controlled to lift it. Specifically, when placing a wafer onto the heating plate 110, the electric fork 310 is first controlled to move the wafer above the heating plate 110. Then, the ejector pin 111 lifts the wafer from below until it is lifted off the electric fork 310. Next, the electric fork 310 retracts out of the reaction chamber. After the fork 313 of the electric fork 310 leaves the heating plate 110, the ejector pin 111 is controlled to fall until the wafer completely rests on the surface of the heating plate 110. When it is necessary to remove the wafer from the heating plate, firstly, control the ejector pin 111 to lift the wafer away from the surface of the heating plate 110. Then, control the electric fork 310 to enter the reaction chamber and position the fork 310 below the wafer. Next, control the ejector pin 111 to fall so that the wafer falls onto the fork 310. Finally, control the electric fork 310 to retract and exit the reaction chamber with the wafer, transferring the wafer into the transfer chamber 300.

[0025] In this invention, the two gases that have been reacted beforehand are transported to the mixing chamber through the first gas supply pipe and the second gas supply pipe, respectively, and the mixing is finally completed in the mixing chamber. In this way, there will be no problem of clogging the gas supply pipe before mixing. Although there will be a short section of mixed gas near the inlet of the first gas supply pipe, the distance is very short and the mixing time before entering the mixing chamber is extremely short, so there is no time to react and form accumulations, and no clogging will occur.

[0026] Therefore, the chemical vapor deposition furnace structure of this invention has the advantage of avoiding or reducing gas pipeline blockage.

Claims

1. A chemical vapor deposition furnace structure, comprising a reaction chamber, a heating plate disposed within the reaction chamber, a gas equalization plate disposed within the reaction chamber above the heating plate, a conductive cover covering the gas equalization plate to form a buffer gas cavity inside, the cover having a gas inlet interface, and further comprising a radio frequency generator electrically connected to the gas inlet interface, characterized in that: A mixing chamber is also provided above the reaction chamber. The mixing chamber has an air inlet and an air outlet. A first air supply pipe is connected to the air inlet of the mixing chamber. A second air supply pipe is also connected to the first air supply pipe near the air inlet. The air outlet of the mixing chamber is connected to the air inlet.

2. The chemical vapor deposition furnace structure according to claim 1, characterized in that: The air inlet is connected upward to a conductive lower pipe that extends out of the reaction chamber, and the air outlet is connected downward to an upper pipe that is connected to and insulated from the lower pipe. The radio frequency generator is connected to the lower pipe via a wire.

3. The chemical vapor deposition furnace structure according to claim 1, characterized in that: The heating plate is equipped with a pin that can extend upward from inside the heating plate.

4. The chemical vapor deposition furnace structure according to claim 1, characterized in that: It also includes a shielding cover that covers the reaction chamber and the mixing chamber, with the first gas supply pipe and the second gas supply pipe extending out from inside the shielding cover.

5. The chemical vapor deposition furnace structure according to claim 2, characterized in that: The material of the upper pipe is PFA.

6. The chemical vapor deposition furnace structure according to claim 1, characterized in that: A baffle is fixed inside the buffer air chamber below the air inlet.

7. The chemical vapor deposition furnace structure according to claim 6, characterized in that: The baffle is a circular baffle.

8. The chemical vapor deposition furnace structure according to claim 1, characterized in that: The reaction chamber is provided with a reaction chamber door on its side.

9. The chemical vapor deposition furnace structure according to claim 3, characterized in that: The ejector pin is a pneumatic ejector pin, the cylinder of which is fixed to the lower part of the reaction chamber, and the piston rod of which passes through the bottom plate of the reaction chamber in a sealed manner and is connected to the ejector pin through a bracket.

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