Gas phase etching system and process based on mixed gas of HF and ethanol

Abstract

The invention discloses a gas-phase etching system and process based on HF and ethanol mixed gas, the gas-phase etching system comprises a gas-phase etching device, an ethanol gas holder, an HF gas holder and a vacuum transmission module, the ethanol gas holder and the HF gas holder are respectively communicated with a gas inlet of the gas-phase etching device through pipelines, and the vacuum transmission module is communicated with a gas outlet of the gas-phase etching device through pipelines. The gas outlet of the gas phase etching equipment is also communicated with a first dry vacuum pump, the sample inlet of the gas phase etching equipment is communicated with the vacuum transmission module, and the gas outlet of the vacuum transmission module is communicated with a second dry vacuum pump. The method has the advantages that multiple metals and typical MEMS materials can be compatible, the etching rate is high, meanwhile, the good etching rate can be achieved in a compact oxide or a narrow space, and the etching uniformity is good.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of semiconductors, in particular to a gas phase etching system based on HF and ethanol mixed gas and a process thereof. BACKGROUND

[0002] In the prior art, HF and water are used for gas phase etching, which causes the following problems:

[0003] Water molecules cause capillary force, leading to adhesion of a MEMS cantilever structure, and the adhesion rate of the microstructure after release is greater than 60%.

[0004] Liquid HF etching: serious lateral drilling, and uniformity degradation is greater than 20% when the aspect ratio is greater than 5.

[0005] The etching rate is disturbed by the environment humidity and is between plus or minus 15%.

[0006] Sensitive materials such as metal / AlN cannot be compatible. SUMMARY

[0007] The application aims to provide a gas phase etching system based on HF and ethanol mixed gas and a process thereof, so as to solve the above technical problems.

[0008] The above technical purpose of the application is achieved by the following technical scheme:

[0009] A gas phase etching system based on HF and ethanol mixed gas comprises a gas phase etching device, an ethanol gas tank, an HF gas tank and a vacuum transmission module, the ethanol gas tank and the HF gas tank are communicated with the gas inlet of the gas phase etching device through pipelines, the gas outlet of the gas phase etching device is also provided with a first dry vacuum pump in communication, the sample inlet of the gas phase etching device is communicated with the vacuum transmission module, and the gas outlet of the vacuum transmission module is provided with a second dry vacuum pump in communication.

[0010] Preferably, the tail gas treatment equipment is communicated with the first dry vacuum pump and the second dry vacuum pump through pipelines.

[0011] Preferably, a gate valve is further arranged between the sample inlet of the gas phase etching device and the vacuum transmission module, one side of the vacuum transmission module is provided with a feeding cavity, and the vacuum transmission module is further communicated with a vacuum interconnection pipeline through a plug valve.

[0012] Preferably, the control cabinet and the upper operating machine are further included, the control cabinet and the upper operating machine are electrically connected, and the control cabinet controls all component devices in the gas phase etching system.

[0013] A gas phase etching process based on HF and ethanol mixed gas comprises the following steps:

[0014] S1, the gas phase etching equipment and the vacuum transmission module are evacuated by the first dry vacuum pump and the second dry vacuum pump respectively;

[0015] S2, the vacuum transmission module takes samples from the vacuum interconnection pipeline, and uses the internal module of the vacuum transmission module to adjust the position of the samples;

[0016] S3, open the door valve to send the samples into the gas phase etching equipment under the same vacuum level;

[0017] S4, pre-baking treatment is performed on the samples;

[0018] S5, the process temperature and the vacuum degree inside the gas phase etching equipment are adjusted to the working state;

[0019] S6, nitrogen is introduced, after the pressure is stabilized, ethanol and HF are introduced from the ethanol gas cabinet and the HF gas cabinet respectively, mixed uniformly with nitrogen, and then introduced into the gas phase etching equipment for etching;

[0020] S7, after the preliminary etching is completed, all gas inlets are stopped, and the first dry vacuum pump is used to maintain vacuum and exhaust the remaining by-products to the tail gas treatment equipment;

[0021] S8, repeat the above steps S5 to S7 until the etching target is completed;

[0022] S9, the process cavity inside the gas phase etching equipment is vacuumed and filled with nitrogen for multiple times;

[0023] S10, open the door valve, and use the mechanical arm to transfer the samples back to the vacuum transmission module;

[0024] S11, transfer the samples back to the vacuum interconnection pipeline or put them into the loading cavity to wait for sampling;

[0025] S12, close the HF gas cabinet, purge and exhaust the HF in the pipeline.

[0026] Preferably, the temperature of the sample pre-baking treatment is 200°C, and the baking time is 2 min.

[0027] Preferably, the process temperature under the working state inside the gas phase etching equipment is 40-60°C, and the vacuum degree is 75-160 torr.

[0028] Preferably, the ethanol is introduced by bubbling, the nitrogen inlet flow is 900 sccm, the ethanol inlet flow is 900 sccm, and the HF inlet flow is 700 sccm.

[0029] Preferably, the sample etching rate is 100 nm / min.

[0030] In summary, the present invention has the following beneficial effects:

[0031] 1. This invention uses ethanol instead of water as the reaction medium and catalyst to participate in the reaction. Ethanol molecules adsorb onto the SiO2 surface to form a monolayer, which inhibits microstructure adhesion caused by capillary forces and improves etching uniformity.

[0032] 2. The vapor phase etching system and process of this invention are compatible with multi-metal and typical MEMS materials (Al).

[0033] 3. The vapor phase etching system and process of the present invention have an etching rate much greater than 1 μm / min, and can also achieve an etching rate of 0.15 μm / min in dense oxides or confined spaces.

[0034] 4. The vapor phase etching system and process of the present invention have good etching uniformity, with intra-wafer non-uniformity ≤5% and inter-wafer non-uniformity ≤5%. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the system structure of the present invention. Detailed Implementation

[0036] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. These embodiments do not constitute a limitation on the present invention.

[0037] like Figure 1 The illustrated vapor phase etching system based on a mixture of HF and ethanol includes a vapor phase etching device 1, an ethanol gas holder 2, an HF gas holder 3, and a vacuum transfer module 4. The ethanol gas holder 2 and the HF gas holder 3 are respectively connected to the gas inlet of the vapor phase etching device 1 through pipelines. The gas outlet of the vapor phase etching device 1 is also connected to a first dry vacuum pump 5. The sample inlet of the vapor phase etching device 1 is connected to the vacuum transfer module 4, and the gas outlet of the vacuum transfer module 4 is connected to a second dry vacuum pump 6.

[0038] It also includes an exhaust gas treatment device 7, which is connected to a first dry vacuum pump 5 and a second dry vacuum pump 6 via pipelines.

[0039] A gate valve 8 is also provided between the sample inlet of the vapor phase etching equipment 1 and the vacuum transfer module 4. A feeding chamber 9 is provided on one side of the vacuum transfer module 4. The vacuum transfer module 4 is also connected to a vacuum interconnection pipe 11 through a gate valve 10. In order to reduce the risk of HF leakage and ensure the cleanliness of the sample surface, the equipment adopts a vacuum interconnection mode, which allows the sample to be directly transferred from the previous process to the reaction chamber of the vapor phase etching equipment 1 through the vacuum interconnection pipe 11 using a robotic arm.

[0040] The control cabinet 12 and the upper operating machine 13 are electrically connected, and the control cabinet 12 controls each component device in the gas phase etching system.

[0041] A gas phase etching process based on HF and ethanol mixed gas, comprising the following steps:

[0042] S1, the gas phase etching equipment 1 and the vacuum transmission module 4 are vacuumized through the first dry vacuum pump 5 and the second dry vacuum pump 6.

[0043] S2, the vacuum transmission module 4 samples from the vacuum interconnection pipeline 11, and uses the internal module of the vacuum transmission module 4 to adjust the position of the sample.

[0044] S3, under the same vacuum level, open the door valve 8 to send the sample into the gas phase etching equipment 1.

[0045] S4, the sample is pre-baked at a temperature of 200℃ for 2min.

[0046] S5, adjust the process temperature and vacuum degree in the gas phase etching equipment 1 to working state, the process temperature is 40-60℃, and the vacuum degree is 75-160torr.

[0047] S6, nitrogen is introduced, after the pressure is stable, ethanol and HF are introduced from the ethanol gas cabinet 2 and the HF gas cabinet 3 respectively, mixed with nitrogen uniformly, and then enter the gas phase etching equipment 1 for etching, the ethanol is bubbled, the nitrogen gas flow is 900sccm, the ethanol gas flow is 900sccm, and the HF gas flow is 700sccm.

[0048] S7, after the preliminary etching is completed, stop all gas inlet and keep vacuumizing by the first dry vacuum pump 5, and exhaust the residual by-products to the tail gas treatment equipment 7.

[0049] S8, repeat the above steps S5 to S7, the sample etching rate is 100nm / min, until the etching target is completed.

[0050] S9, the process cavity in the gas phase etching equipment 1 is vacuumized and filled with nitrogen for multiple times.

[0051] S10, open the door valve 8, and transfer the sample back to the vacuum transmission module 4 through the mechanical arm.

[0052] S11, the sample is transferred back to the vacuum interconnection pipeline 11 or placed in the feeding cavity 9 to wait for sampling.

[0053] S12, close the HF gas cabinet 3, purge and exhaust the HF in the pipeline.

[0054] The application adopts ethanol instead of water as a reaction medium and a catalyst to participate in the reaction, ethanol molecules are adsorbed on the surface of SiO2 to form a monolayer, the microstructure adhesion caused by capillary force is inhibited, and the etching uniformity is improved, and the reaction principle formula is:

[0055]

[0056] The gas phase etching system and process thereof can be compatible with multiple metals and typical MEMS materials (Al).

[0057] The etching rate of the gas phase etching system and process thereof is far greater than 1 um / min, and meanwhile, the etching rate of 0.15 um / min can be realized in dense oxides or narrow spaces.

[0058] The etching uniformity of the gas phase etching system and process thereof is good, the within-chip non-uniformity is less than or equal to 5%, and the between-chip non-uniformity is less than or equal to 5%.

[0059] The above is only a preferred embodiment of the application and is not used to limit the application, and those skilled in the art can make various modifications or equivalent replacements to the application within the spirit and protection scope of the application, and the modification or equivalent replacement should also be regarded as falling within the protection scope of the technical scheme of the application.

Claims

1. A gas phase etching system based on a mixture of HF and ethanol gas, characterized in that, The device includes a vapor phase etching apparatus, an ethanol gas holder, an HF gas holder, and a vacuum transfer module. The ethanol gas holder and the HF gas holder are connected to the gas inlet of the vapor phase etching apparatus via pipelines. The gas outlet of the vapor phase etching apparatus is also connected to a first dry vacuum pump. The sample inlet of the vapor phase etching apparatus is connected to the vacuum transfer module, and the gas outlet of the vacuum transfer module is connected to a second dry vacuum pump.

2. The vapor phase etching system based on a mixture of HF and ethanol gas according to claim 1, characterized in that: It also includes exhaust gas treatment equipment, which is connected to a first dry vacuum pump and a second dry vacuum pump via pipelines.

3. The vapor phase etching system based on a mixture of HF and ethanol gas according to claim 1, characterized in that: A gate valve is also provided between the sample inlet of the vapor phase etching equipment and the vacuum transmission module. A feeding chamber is provided on one side of the vacuum transmission module. The vacuum transmission module is also connected to a vacuum interconnection pipeline through a gate valve.

4. The vapor phase etching system based on a mixture of HF and ethanol gas according to claim 1, characterized in that: It also includes a control cabinet and a host computer, the control cabinet and the host computer being electrically connected, the control cabinet controlling the various components and devices within the vapor phase etching system.

5. A vapor phase etching process based on a mixture of HF and ethanol gas according to any one of claims 1 to 4, characterized in that: Includes the following steps: S1, the vapor phase etching equipment and the vacuum transfer module are evacuated by their respective first dry vacuum pump and second dry vacuum pump; S2, the vacuum transmission module takes a sample from the vacuum interconnection pipeline and uses the internal module of the vacuum transmission module to adjust the position of the sample by edge-checking. S3, under the same vacuum level, open the gate valve to send the sample into the vapor phase etching equipment; S4, Pre-baking treatment of the sample; S5, adjust the process temperature and vacuum level inside the vapor phase etching equipment to the working state; S6. Nitrogen gas is introduced. After the pressure stabilizes, ethanol and HF are drawn out through the ethanol gas holder and HF gas holder respectively. After being mixed evenly with nitrogen gas, they are introduced into the vapor phase etching equipment for etching. S7. After the initial etching is completed, all gas intake is stopped and the first dry vacuum pump is used to maintain vacuum, and the residual by-products are discharged to the exhaust gas treatment equipment. S8. Repeat steps S5 to S7 until the etching target is completed. S9, the internal process cavity of the vapor phase etching equipment is evacuated and filled with nitrogen multiple times; S10, open the valve and transfer the sample back to the vacuum transfer module via the robotic arm; S11, then transfer the sample back to the vacuum interconnected pipeline or place it in the loading chamber to wait for sampling; S12, shut down the HF gas holder, purge and drain the HF from the pipeline.

6. The vapor phase etching process based on a mixture of HF and ethanol gas according to claim 5, characterized in that: The sample pre-baking treatment was carried out at a temperature of 200℃ for 2 minutes.

7. The vapor phase etching process based on a mixture of HF and ethanol gas according to claim 5, characterized in that: The process temperature inside the vapor phase etching equipment is 40–60°C, and the vacuum degree is 75–160 torr.

8. The vapor phase etching process based on a mixture of HF and ethanol gas according to claim 5, characterized in that: The ethanol is emitted by bubbling, the nitrogen inlet flow rate is 900 sccm, the ethanol inlet flow rate is 900 sccm, and the HF inlet flow rate is 700 sccm.

9. The vapor phase etching process based on a mixture of HF and ethanol gas according to claim 5, characterized in that: The etching rate of the sample was 100 nm / min.

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