TWI749775B - Oxide layer removal method and semiconductor processing equipment - Google Patents

Abstract

The embodiment of the present invention provides an oxide layer removal method and semiconductor processing equipment. The oxide layer removal method includes the following steps: S1, oxidizing a layer to be processed to form a specified oxide layer; S2, performing a process on the layer to be processed with the specified oxide layer Etching; step S1 and step S2 are performed in a loop until the preset total etching thickness is reached; wherein, by adjusting the thickness of the specified oxide layer obtained in step S1, the etching selection ratio of the specified oxide layer and the layer to be processed in step S2 Reach the preset ratio. In the method for removing the oxide layer and the technical solution of the semiconductor processing equipment provided by the embodiments of the present invention, the etching selection ratio of the specified oxide layer and the layer to be processed can reach a preset ratio, which meets the requirements of the etching selection ratio in the manufacturing process.

Description

Oxide layer removal method and semiconductor processing equipment

The present invention relates to the field of cleaning technology, in particular to a method for removing an oxide layer and semiconductor processing equipment.

With more and more applications of template cleaning and multiple pattern exposure cleaning, there are more and more cleaning requirements, and the requirements for cleaning are getting higher and higher, especially for the etching options of thermally grown silicon dioxide and various film layers. The requirements are getting stricter. For example, when removing _{the natural oxide layer on Si 3} N ₄ , it is necessary to ensure that the etching selection ratio of _{SiO 2} and Si ₃ N _{4 is 1:1.} When performing a high etching amount of the oxide layer etch-back process, while ensuring that _{the etching selection ratio of SiO 2} and Si ₃ N ₄ is 1:1, it is also necessary to etch the topography to meet the requirements, that is, to reduce the bowl-shaped effect (footing). ) And the difference effect (loading).

The existing oxide layer removal method is to directly etch the oxide layer. The reaction gas usually includes HF and NH ₃ (catalyst). The solid product produced by the reaction is (NH ₄ ) ₂ SiF _6. When the thickness of the solid product reaches a certain level, The etching rate will reach saturation, and high-temperature heating treatment is required at this time to enable the solid product to be sublimated and decomposed.

The reaction principle of the above removal method is as follows:

In practical applications, the above-mentioned oxide layer removal method inevitably has the following problems: First, for the removal of the natural oxide layer with low etching amount, _{the etching selection ratio of SiO 2} and Si ₃ N ₄ cannot reach 1:1.

Second, for the high etching amount of the oxide layer etch process, in order to reduce the bowl effect and the difference effect, it is necessary to increase the number of cycles of the oxide layer removal method, but this will lead to the etching selection ratio of _{SiO 2} and Si ₃ N ₄ Much greater than 1.

The embodiment of the present invention aims to solve at least one of the technical problems existing in the prior art, and proposes an oxide layer removal method and semiconductor processing equipment, which can make the etching selection ratio of the specified oxide layer and the layer to be processed reach a preset ratio, which satisfies Process requirements for etching selection ratio.

To achieve the foregoing objective, an embodiment of the present invention provides a method for removing an oxide layer, which includes the following steps: S1, oxidize the layer to be processed to form a specified oxide layer; S2, etching the to-be-processed layer with the designated oxide layer; Perform the steps S1 and S2 in a loop until the preset total etching thickness is reached; Wherein, by adjusting the thickness of the designated oxide layer obtained in the step S1, the etching selection ratio of the designated oxide layer and the layer to be processed in the step S2 reaches a preset ratio.

Optionally, the layer to be processed includes Si ₃ N ₄ ; the designated oxide layer includes SiO ₂ ; and the preset ratio is 1:1.

Optionally, by adjusting the number of loops in step S1 and step S2, the obtained etching profile meets the requirements.

Optionally, the thickness of the designated oxide layer is set according to the number of loops and the preset etching thickness in step S2, and the etching thickness in step S2 is higher than a preset critical value, and there are requirements for etching topography In this case, the thickness of the designated oxide layer ranges from 1 nm to 10 nm.

Optionally, the thickness of the designated oxide layer is set according to the number of cycles and the etching thickness of step S2, and when the etching thickness of step S2 is higher than a preset critical value and there is no requirement for etching topography, The thickness of the specified oxide layer ranges from 1nm-50nm.

Optionally, for the removal of the natural oxide layer, the thickness of the specified oxide layer ranges from 1 nm to 3 nm.

Optionally, this step S1 specifically includes using an oxidizing gas to oxidize the layer to be processed to form a specified oxide layer; Wherein, the oxidizing gas includes at least one of oxygen and water vapor.

Optionally, the flow rate of the oxidizing gas ranges from 10 sccm to 2000 sccm.

Optionally, after completing this step S2 each time and before performing the next step S1, the following steps are further included: S3, performing an annealing process on the to-be-processed layer to remove solid products and adsorption products.

As another technical solution, an embodiment of the present invention also provides a semiconductor processing equipment for performing the above-mentioned oxide layer removal method provided by the present invention. The semiconductor processing equipment includes: At least one process chamber for etching the to-be-processed layer with the designated oxide layer; The oxidation chamber is used to oxidize the layer to be processed.

Optionally, the semiconductor processing equipment further includes an annealing chamber for performing an annealing process on the layer to be processed.

Optionally, the process chamber is integrated into a dual-function chamber with both annealing and etching.

Optionally, the etching step and the annealing step of the dual-function chamber use the same process temperature; wherein, the process gas used in the etching step includes NH ₃ , HF, and carrier gas; wherein, the flow rate of _{the NH 3 is selected} The value range is 100 sccm-600 sccm; the value range of the HF flow rate is 100 sccm-600 sccm; the value range of the carrier gas flow rate is 10 sccm-6000 sccm.

Optionally, the oxidation chamber is integrated into a dual-function chamber with both annealing and oxidation.

The beneficial effects of the embodiments of the present invention: In the method for removing the oxide layer and the technical solution of the semiconductor processing equipment provided by the embodiments of the present invention, by adding an oxidation step before the step of etching the oxide layer, that is, the layer to be processed is oxidized to form a specified oxide layer, which can be achieved by The thickness of the specified oxide layer is adjusted so that the etching selection ratio of the specified oxide layer and the layer to be processed in the subsequent etching step reaches a preset ratio, so as to meet the requirements of the etching selection ratio in the manufacturing process.

In order to enable those skilled in the art to better understand the technical solutions of the present invention, the oxide layer removal method and semiconductor processing equipment provided by the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The first embodiment

Please refer to FIG. 1. The oxide layer removal method provided in this embodiment includes the following steps: S1, oxidize the layer to be processed to form a specified oxide layer; S2, etching the to-be-processed layer with the above-mentioned specified oxide layer.

Perform the above steps S1 and S2 in a loop until the preset total etching thickness is reached; Wherein, by adjusting the thickness of the designated oxide layer obtained in step S1, the etching selection ratio of the designated oxide layer and the layer to be processed in step S2 can reach a preset ratio. In practical applications, the thickness of the specified oxide layer can be adjusted by adjusting the reaction temperature and/or oxidation time.

The oxide layer removal method provided in this embodiment adds an oxidation step S1 before the etching step S2. By adjusting the thickness of the specified oxide layer, the etching options for the oxide layer and the layer to be processed can be selected in the subsequent step S2. The ratio reaches the preset ratio, so as to meet the requirement of the etching selection ratio in the manufacturing process.

The so-called designated oxide layer refers to an oxide layer additionally formed on the original oxide layer to be removed of the layer to be processed to adjust the etching selection ratio of subsequent etching steps.

The oxide layer removal method provided in this embodiment can be applied to remove the oxide layer formed by Si ₃ N ₄ after FCVD (Flowable CVD, fluid chemical vapor deposition) process or thermal oxidation. Specifically, the layer to be processed is Si ₃ N ₄ , and the designated oxide layer is SiO _{2 , and the etching selection ratio of SiO 2} and Si ₃ N ₄ is generally required to be 1:1. In this case, by step S1, _{an additional layer of SiO 2} can be formed on the oxide layer of _{Si 3} N ₄ to be removed. By adjusting the _{thickness of the SiO 2 layer, the SiO 2} and Si ₃ in step S2 can be adjusted. The etching selection ratio of N ₄ makes the ratio reach 1:1, which can meet the requirement of the etching selection ratio of the manufacturing process.

In some embodiments, for a high-etching thickness oxide layer etch-back process, the etching thickness of step S2 in a single process is higher than a preset critical value (for example, 100-1000 angstroms), and the process also requires etching topography. Specific requirements but not limited to reducing the bowling effect (footing) and the difference effect (loading), in this case, you can adjust the number of loops in step S1 and step S2 to adjust the processing to be processed each time step S1 is performed The oxidized thickness of the layer, that is, the thickness of the oxidized layer is specified, so as to meet the requirements of etching selection ratio and etching topography at the same time.

The existing oxide layer removal method is to directly etch the oxide layer (hereinafter referred to as step 1). When the thickness of the solid product reaches a certain level, the etching rate will reach saturation. At this time, high temperature heating treatment is required (hereinafter referred to as step 2). ), so that the solid product can be sublimated and decomposed.

In Table 1, the number of loops in step 1 and step 2 is 1, the etching thickness and etching selection ratio of _{SiO 2} and Si ₃ N _4. Etching thickness of SiO _{2 (Angstrom)} Si ₃ N ₄ etching thickness (Angstrom) Etching selection ratio of SiO ₂ and Si ₃ N ₄ 53.07 10.33 5.14 97.07 27.69 3.51 143.82 65.00 2.21 178.37 121.40 1.47 288.15 302.05 0.95 373.06 485.82 0.77

It can be seen from Table 1 above that, taking the layer to be processed is Si ₃ N ₄ and the designated oxide layer is SiO ₂ as an example, if the existing oxide layer removal method is used to directly etch the oxide layer, if the steps 1 and 2 are returned The number of laps is 1, _{and the etching options of SiO 2} and Si ₃ N ₄ are relatively low. Specifically, _{the etching selection ratio of SiO 2} and Si ₃ N ₄ is in the range of 0.7-5.2, and increases with the etching thickness of _{SiO 2} Cumulatively, the etching selection ratio is getting lower and lower. When the cumulative etching thickness of _{SiO 2 reaches 288.15 angstroms, the etching selection ratio of SiO 2} and Si ₃ N ₄ reaches 0.95, which is approximately 1, although the etching selection ratio of the process can be satisfied. The ratio can reach the requirement of 1:1, but through experiments, it is found that when the number of loops in step 1 and step 2 is 1, the etched morphology obtained has a serious bowl effect (footing) and a difference effect (loading) , So it is not suitable for situations that require etching topography.

Table 2. The number of loops in step 1 and step 2 is multiple times, the etching thickness and etching selection ratio of _{SiO 2} and Si ₃ N _4. Etching thickness of SiO _{2 (Angstrom)} Si ₃ N ₄ etching thickness (Angstrom) Etching selection ratio of SiO ₂ and Si ₃ N ₄ 53.07 10.33 5.14 113.19 10.22 11.08 230.85 11.96 19.31 351.54 14.94 23.53 470.19 15.54 30.26 594.95 16.09 36.97

It can be seen from the above Table 2 and Figure 3 that when the existing oxide layer removal method is used to directly etch the oxide layer, if the number of loops in step 1 and step 2 is multiple, the etching thickness of _{SiO 2 can be increased linearly} , And _{the etching thickness of Si 3} N ₄ basically does not increase. Although this can reduce the bowl effect and the difference effect, _{the etching selection ratio of SiO 2} and Si ₃ N ₄ is greatly increased, far greater than 1, making SiO ₂ The etching selection ratio with Si ₃ N ₄ cannot reach the requirement of 1:1.

In order to solve the above problems, the oxide layer removal method provided by this embodiment adds an oxidation step S1 before the etching step S2, and an additional oxide layer can be formed on the layer to be processed, and by adjusting the oxidation step S1 and the etching step S2 The number of laps can be adjusted each time step S1 is performed, the oxidized thickness of the layer to be processed, that is, the thickness of the oxidized layer is specified, so that not only the etching selection ratio can reach 1:1, but also the bowl-shaped effect can be reduced. (Footing) and difference effect (loading).

In some embodiments, for a high etching amount of the oxide layer etch-back process, the etching thickness of step S2 in a single process is higher than a preset threshold (for example, 100-1000 angstroms), and the process also has requirements on the etching morphology. Specific requirements but not limited to reducing the bowling effect (footing) and the difference effect (loading), in this case, it can be based on the number of loops (set on the premise that the etching topography requirements are met) and the preset step S2 For the etching thickness of, set the thickness of the specified oxide layer, specifically, the value range of the thickness of the specified oxide layer is 1nm-10nm. Within this thickness range, it is easy to simultaneously meet the requirements of etching selection ratio and etching morphology.

In some embodiments, for a process with a high etching amount (that is, the etching thickness in a single step S2 is higher than a preset critical value) and there is no etching topography requirement, the number of cycles can be based on the number of cycles (which can be a specific requirement Any value) and the preset etching thickness of step S2, set the thickness of the designated oxide layer, specifically, the value range of the thickness of the designated oxide layer is 1 nm-50 nm.

In some embodiments, for the removal of the natural oxide layer with a low etching amount, since the etching thickness is small, and there is no need to consider the etching topography, in this case, it is only necessary to meet the requirements of the etching selection ratio. Specifically, the value range of the thickness of the designated oxide layer is 1nm-3nm.

In some embodiments, step S1 specifically includes using an oxidizing gas to oxidize the layer to be processed to form a specified oxide layer; Wherein, the above-mentioned oxidizing gas includes at least one of oxygen and water vapor.

In some embodiments, the value of the flow rate of the oxidizing gas ranges from 100 sccm to 2000 sccm.

In some embodiments, in step S1, the oxidizing gas is introduced into the oxidation chamber by a carrier gas. Of course, in practical applications, the oxidizing gas can also be introduced in a self-evaporating manner through a flow controller (MFC). Oxidation chamber. Wherein, the carrier gas can be _{at least one of PN 2} , argon and nitrogen. The flow rate of the carrier gas ranges from 10 sccm to 6000 sccm. The value range of the chamber pressure used in step S1 is 10mTorr-20Torr; the value range of the process temperature used in step S1 is 100°C-1200°C.

In some embodiments, in step S2, the process gas includes NH ₃ , HF and carrier gas; wherein _{the flow rate of NH 3} ranges from 100 sccm to 600 sccm; the flow rate of HF ranges from 100 sccm to 600 sccm; The range of gas flow rate is 10sccm-6000sccm. The chamber pressure used in step S2 ranges from 10 mTorr to 20 Torr; the process temperature used in step S2 ranges from 25° C. to 200° C. Second embodiment

Referring to FIG. 2, the oxide layer removal method provided in this embodiment includes the following steps: S1, oxidize the layer to be processed to form a specified oxide layer; S2, etching the to-be-processed layer with the above-mentioned designated oxide layer; S3, an annealing process is performed on the layer to be processed to remove solid products and adsorption products; S4, it is judged whether the total etching thickness is reached, if it is, the process is ended; if not, it returns to step S1.

By performing step S3 once after each step S2 is completed, that is, an annealing process, the solid products and adsorption products on the layer to be processed can be removed, so that the cleaning effect can be further improved. The third embodiment

Please refer to FIG. 4, the semiconductor processing equipment provided in this embodiment is used to perform the oxide layer removal methods provided in the foregoing embodiments of the present invention. The semiconductor processing equipment includes at least one process chamber 1, an oxidation chamber 2 and an annealing chamber 3, wherein the process chamber 1 is used to etch a layer to be processed with a specified oxide layer. FIG. 4 shows four process chambers 1. By providing a plurality of process chambers 1, multiple etching steps can be performed at the same time, so that the productivity can be improved. The oxidation chamber 2 is used to oxidize the layer to be processed. The annealing chamber is used to perform an annealing process on the layer to be processed.

In the semiconductor processing equipment provided in this embodiment, by adding an oxidation chamber 2, an oxidation step can be added before the step of etching the oxide layer in the process chamber 1, and the thickness of the specified oxide layer can be adjusted to make the subsequent steps In the etching step, the etching selection ratio of the specified oxide layer and the layer to be processed reaches the preset ratio, so as to meet the requirements of the etching selection ratio in the process.

In some embodiments, in practical applications, the annealing chamber 3 and the process chamber 1 can be integrated into a dual-function chamber with both annealing and etching. In this case, the dual-function chamber can be made to use different process temperatures for the etching step and the annealing step, that is, the etching step S2 is performed at a lower temperature first, and then the annealing step S3 is performed at a higher temperature. Alternatively, the process temperature used in the etching step and the annealing step in the dual-function chamber may be the same. In this case, it is necessary to appropriately increase the flow rate of the process gas used in the etching step S3. Specifically, the process gas used in the etching step S3 includes NH ₃ , HF and carrier gas; wherein _{the flow rate of NH 3} ranges from 100 sccm to 600 sccm; the flow rate of HF ranges from 100 sccm to 600 sccm; the flow rate of carrier gas The value range of is 10sccm-6000sccm. Of course, the annealing chamber 3 and the process chamber 1 can also be configured separately.

In some embodiments, the annealing chamber 3 and the oxidation chamber 2 are integrated into a dual-function chamber that combines annealing and oxidation. Of course, the annealing chamber 3 and the oxidation chamber 2 can also be configured separately.

In summary, in the method for removing the oxide layer and the technical solution of the semiconductor processing equipment provided by the foregoing embodiments of the present invention, an oxidation step is added before the step of etching the oxide layer, that is, the layer to be processed is oxidized to form For the specified oxide layer, the thickness of the specified oxide layer can be adjusted so that the etching selection ratio of the specified oxide layer and the layer to be processed in the subsequent etching step can reach the preset ratio, so as to meet the requirements of the etching selection ratio in the process.

It can be understood that the above implementations are merely exemplary implementations used to illustrate the principle of the present invention, but the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also deemed to be within the protection scope of the present invention.

1: Process chamber 2: Oxidation chamber 3: Annealing chamber S1, S2, S3, S4: steps

FIG. 1 is a flowchart of a method for removing an oxide layer according to a first embodiment of the present invention; 2 is a flow chart of a method for removing an oxide layer provided by a second embodiment of the present invention; Figure 3 is a graph of the number of loops and etching thickness of different oxide layers; FIG. 4 is a structural diagram of a semiconductor processing equipment provided by a third embodiment of the present invention.

S1, S2: steps

Claims (14)

A method for removing an oxide layer includes the following steps: S1, oxidize a layer to be processed to form a specified oxide layer; S2, etching the to-be-processed layer with the designated oxide layer; Perform the steps S1 and S2 in a loop until the preset total etching thickness is reached; Wherein, by adjusting the thickness of the designated oxide layer obtained in the step S1, the etching selection ratio of the designated oxide layer and the layer to be processed in the step S2 reaches a preset ratio. The method for removing an oxide layer according to claim 1, wherein the layer to be processed includes Si ₃ N ₄ ; the designated oxide layer includes SiO ₂ ; and the preset ratio is 1:1. The method for removing the oxide layer according to claim 1 or claim 2, wherein by adjusting the number of cycles of step S1 and step S2, the obtained etching topography meets the requirements. The oxide layer removal method according to claim 3, wherein the thickness of the specified oxide layer is set according to the number of cycles and the preset etching thickness in step S2, and the etching thickness in step S2 is higher than the preset etching thickness In the case of a critical value and an etching topography requirement, the thickness of the specified oxide layer ranges from 1 nm to 10 nm. The oxide layer removal method according to claim 1 or claim 2, wherein the thickness of the specified oxide layer is set according to the number of cycles and the etching thickness of the step S2, and the etching thickness of the step S2 is higher than the predetermined thickness. If a critical value is set and there is no requirement for etching topography, the thickness of the specified oxide layer ranges from 1 nm to 50 nm. The oxide layer removal method according to claim 5, wherein, for the removal of the natural oxide layer, the thickness of the specified oxide layer ranges from 1 nm to 3 nm. The method for removing an oxide layer according to claim 1 or claim 2, wherein the step S1 specifically includes using an oxidizing gas to oxidize the layer to be processed to form a specified oxide layer; Wherein, the oxidizing gas includes at least one of oxygen and water vapor. The method for removing the oxide layer according to claim 7, wherein the flow rate of the oxidizing gas ranges from 10 sccm to 2000 sccm. The method for removing an oxide layer according to claim 1 or claim 2, wherein after each step S2 is completed, and before the next step S1 is performed, the method further includes the following steps: S3, performing an annealing process on the to-be-processed layer to remove solid products and adsorption products. A semiconductor processing equipment, wherein, for performing the oxide layer removal method according to any one of claim 1 to claim 9, the semiconductor processing equipment includes: At least one process chamber for etching the to-be-processed layer with the designated oxide layer; An oxidation chamber is used to oxidize the layer to be processed. The semiconductor processing equipment according to claim 10, wherein the semiconductor processing equipment further includes an annealing chamber for performing an annealing process on the layer to be processed. The semiconductor processing equipment according to claim 10, wherein the process chamber is integrated into a dual-function chamber that combines annealing and etching. The semiconductor processing equipment according to claim 12, wherein the dual-function chamber respectively performs an etching step and an annealing step at the same process temperature; wherein, the process gas used in the etching step includes NH ₃ , HF and carrier Wherein, the _{flow rate of the NH 3} ranges from 100 sccm to 600 sccm; the flow rate of the HF ranges from 100 sccm to 600 sccm; the flow rate of the carrier gas ranges from 10 sccm to 6000 sccm. The semiconductor processing equipment according to claim 10, wherein the oxidation chamber is integrated into a dual-function chamber that combines annealing and oxidation.

Images