Reactive gas based fully dry semiconductor surface polishing apparatus and polishing method

Abstract

The application relates to the technical field of semiconductor polishing, and particularly discloses a full-dry semiconductor surface polishing device based on reactive gas and a polishing method. The device comprises a vacuum chamber, a gas path system, a multi-hole array injection device, a polishing disc and a sample bearing mechanism. The application realizes precise modification of the surface of a sample to be polished through step-by-step action of two-way reaction gas controlled by timing, that is, first, a precursor gas one is used to act on the surface of the sample to be polished to form a molecular-level saturated adsorption layer, then, a precursor gas two is used to generate a weakly-bonded modified layer through self-limiting reaction with the molecular-level saturated adsorption layer, and the surface reconstruction without damage is completed. The modified sample to be polished is dynamically matched with the high-speed rotating polishing disc under the driving of a multi-dimensional composite motion guide rail, and the surface weakly-bonded modified layer is peeled off. The application improves the problems of liquid residue pollution, edge effect and high waste liquid treatment cost of wet chemical mechanical polishing, and overcomes defects such as poor surface roughness and uneven reaction of dry technology.

Description

Technical Field

[0001] This application relates to the field of semiconductor polishing technology, and in particular to a fully dry semiconductor surface polishing apparatus and polishing method based on reactive gas. Background Technology

[0002] In semiconductor manufacturing processes, surface polishing directly determines the global planarization accuracy of wafers and device performance. Traditional chemical mechanical polishing (CMP) has significant limitations: its reliance on liquid polishing slurries results in residual abrasive particles in nanoscale trenches after polishing, posing a risk of short circuits in devices; simultaneously, the surface tension of the liquid causes excessive etching at the edges of large wafers, leading to inhomogeneity within the wafer and severely restricting the yield of advanced processes; furthermore, the annual treatment cost of waste liquids containing fluorides and heavy metals is high, significantly increasing the manufacturing burden.

[0003] Mainstream dry alternative technologies such as plasma polishing still have key shortcomings: the static treatment mode causes fluctuations in the reaction layer thickness, leading to surface uniformity degradation; the pure physical bombardment mechanism lacks chemical modification synergy, causing surface damage to hard and brittle materials such as silicon carbide; more seriously, the lack of an integrated by-product emission system leads to the accumulation of reaction waste gas, which can easily increase the additional defect density and fail to meet the cleanliness requirements of nodes below 3nm. Summary of the Invention

[0004] To improve upon the problems of liquid residue contamination, edge effects, and high waste liquid treatment costs associated with traditional wet chemical mechanical polishing, and to overcome the defects of poor surface roughness and uneven reaction in existing dry technologies, this application provides a fully dry semiconductor surface polishing apparatus and polishing method based on reactive gases.

[0005] The all-dry semiconductor surface polishing apparatus based on reactive gas provided in this application adopts the following technical solution:

[0006] A fully dry semiconductor surface polishing apparatus based on reactive gases, comprising:

[0007] The vacuum chamber contains a gas injection area and a mechanical grinding area.

[0008] The gas path system includes a carrier gas cylinder and two polishing gas cylinders. The two polishing gas cylinders are respectively filled with precursor gas one and precursor gas two. Precursor gas one is used to interact with the surface of the sample to be polished to form a molecular-level saturated adsorption layer. Precursor gas two is used to generate a weakly bonded modified layer with the molecular-level saturated adsorption layer through a self-limiting reaction.

[0009] A multi-hole array injection device is disposed in the gas injection area of ​​the vacuum chamber. The multi-hole array injection device is connected to the gas path system and is used to carry and alternately inject precursor gas one / precursor gas two through carrier gas.

[0010] A polishing disc is rotatably disposed in the mechanical grinding area within the vacuum chamber. A polishing pad is fixed on the surface of the polishing disc for peeling off the weakly bonded modified layer on the surface of the sample to be polished.

[0011] The sample carrying mechanism drives the sample to be polished to move horizontally between the gas injection area and the mechanical grinding area, as well as to perform circular motion and rotation in the mechanical grinding area, through a multi-dimensional composite motion guide rail.

[0012] This application achieves precise surface modification of the sample to be polished through a time-controlled, dual-path reactive gas stepwise action. First, a precursor gas one reacts with the sample surface to form a molecular-level saturated adsorption layer. Then, a precursor gas two reacts with the molecular-level saturated adsorption layer to generate a weakly bonded modified layer through a self-limiting reaction, completing a non-destructive surface reconstruction. The modified sample is dynamically matched with a high-speed rotating polishing disk under the drive of a multi-dimensional composite motion guide, achieving the peeling off of the weakly bonded modified layer. This application improves upon the problems of liquid residue contamination, edge effects, and high waste liquid treatment costs of wet chemical mechanical polishing, while overcoming the defects of dry technology such as poor surface roughness and uneven reaction.

[0013] Furthermore, the multidimensional composite motion guide rail includes a linear guide rail and an annular guide rail disposed on the top wall of the vacuum chamber. The linear guide rail is connected to the annular guide rail and is located on the radial extension line of the annular guide rail. The annular guide rail is coaxial with the polishing disk.

[0014] Linear guide rails can drive the sample to be polished to move horizontally between the gas injection area and the mechanical grinding area, while annular guide rails can drive the sample to be polished to move in a circular motion within the mechanical grinding area. Combined with the rotation of the sample and the rotation of the polishing disc, this helps to achieve stable removal of the material from the surface of the sample.

[0015] Furthermore, the outlet ends of the carrier gas cylinder and the two polishing gas cylinders are each equipped with an independent solenoid valve.

[0016] The opening and closing of the carrier gas, precursor gas one, and precursor gas two gas paths can be independently controlled by the solenoid valve.

[0017] Furthermore, the porous array injection device includes a polishing gas outlet and a polishing gas inlet, the polishing gas inlet being connected to the gas outlet of the gas path system, and the polishing gas outlet including a plurality of micropores distributed in an array.

[0018] The multi-hole array injection device can achieve uniform gas injection.

[0019] Furthermore, it also includes an exhaust gas treatment system, which includes a vacuum pump and an exhaust gas treatment and collection device connected to the vacuum chamber.

[0020] Unattached precursor gases and reaction byproducts are extracted to the exhaust gas collection and treatment system to eliminate residual pollution.

[0021] Furthermore, the first precursor gas is a chlorine-containing gas, and the second precursor gas is an oxygen-containing gas.

[0022] Taking gallium nitride (GaN) wafer polishing as an example, a carrier gas carrying chlorine-containing gas is sprayed onto the surface of the GaN wafer to form a molecular-level gallium chloride adsorption layer. After the carrier gas is used to purge away the residual gas, an oxygen-containing gas carrying oxygen is sprayed onto the surface of the GaN wafer, triggering a self-limiting reaction to generate a weakly bonded chlorine-oxidation modified layer. This modified layer prevents the oxygen-containing gas from diffusing into deeper layers, and the reaction automatically terminates at the surface nanoscale modified layer. In the mechanical polishing process, the modified layer is mechanically peeled off by the polishing pad, which can reduce the surface roughness of the GaN wafer to the nanoscale without the participation of any liquid medium.

[0023] This application also provides a fully dry semiconductor surface polishing method based on reactive gases, employing a fully dry semiconductor surface polishing apparatus based on reactive gases. The polishing method includes the following steps:

[0024] Polishing preparation: Install the sample to be polished onto the sample carrier and evacuate the vacuum chamber;

[0025] Polishing gas injection: The sample to be polished is moved horizontally to the gas injection area, and precursor gas one and precursor gas two are alternately injected into the sample to be polished through a multi-hole array injection device, so that a molecular-level saturated adsorption layer and a weakly bonded modification layer are formed sequentially on the surface of the sample to be polished.

[0026] Mechanical grinding: The sample to be polished is moved horizontally to the mechanical grinding area, and pressure is applied to make the polishing pad contact the sample to be polished; the sample to be polished is simultaneously driven to rotate and rotate, while the polishing disk is driven to rotate, and the polishing pad peels off the weak bonded modified layer on the surface of the sample to be polished.

[0027] Further, the polishing gas injection step includes:

[0028] A precursor gas is sprayed onto the surface of the sample to be polished, and the precursor gas interacts with the surface of the sample to be polished to form a molecular-level saturated adsorption layer.

[0029] Carrier gas purging removes unadsorbed gases;

[0030] Precursor gas 2 is sprayed onto the surface of the sample to be polished. Precursor gas 2 reacts with the molecular-level saturated adsorption layer to generate a weakly bonded modified layer through a self-limiting reaction.

[0031] Secondary carrier gas purging removes byproducts.

[0032] Furthermore, the polishing gas injection step is performed cyclically once or multiple times.

[0033] Furthermore, it also includes the following steps: maintaining a vacuum environment in the vacuum chamber during polishing gas injection and mechanical grinding.

[0034] In summary, this application includes at least one of the following beneficial technical effects:

[0035] 1. This application adopts a fully dry polishing process, which improves the problems of liquid residue pollution and waste liquid treatment in traditional wet chemical mechanical polishing by the synergistic effect of polishing gas circulation injection and mechanical grinding in a vacuum environment. It is particularly suitable for the precision processing of large-size silicon wafers and third-generation semiconductor materials such as silicon carbide and gallium nitride, and has significant advantages such as good surface quality consistency, excellent process environmental protection, and low equipment maintenance cost.

[0036] 2. This application forms a uniform modified layer through a self-limiting reaction mechanism of precursor gas, and achieves nanoscale flatness and improves intra-sheet uniformity by combining the dynamic synergy of multidimensional composite motion of the sample and rotation of the polishing disk.

[0037] 3. This application achieves stable material removal on the sample to be polished by precisely controlling the number of injection cycles of the precursor gas, the injection time, and the mechanical motion parameters, thereby improving polishing efficiency;

[0038] 4. The multi-hole array jetting device of this application, combined with the sample guide rail motion design, is suitable for wafer-level sample polishing and can effectively suppress edge effects and improve sample polishing quality. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the overall structure of the all-dry semiconductor surface polishing device based on reactive gas according to an embodiment of this application;

[0040] Figure 2 This is a schematic diagram of the vacuum chamber structure of the all-dry semiconductor surface polishing device based on reactive gas, according to an embodiment of this application.

[0041] Figure 3 This is a schematic diagram of the gas path structure of the all-dry semiconductor surface polishing device based on reactive gas according to an embodiment of this application;

[0042] Figure 4 This is a schematic diagram of the porous array jetting device structure of the all-dry semiconductor surface polishing apparatus based on reactive gas according to an embodiment of this application;

[0043] Figure 5 This is a schematic diagram of the moving guide rail structure of the polishing head at the top of the vacuum chamber of the all-dry semiconductor surface polishing device based on reactive gas, according to an embodiment of this application.

[0044] Figure 6 This is a flowchart of a fully dry semiconductor surface polishing method based on reactive gases, according to an embodiment of this application.

[0045] Reference numerals: 1. Vacuum chamber; 2. Pipeline; 3. Carrier gas cylinder; 4. Solenoid valve; 5. Polishing gas cylinder; 6. Vacuum pump; 7. Tail gas treatment and collection device; 8. Multi-hole array spray device; 9. Polishing head; 10. Sample to be polished; 11. Polishing pad; 12. Polishing disc; 13. Multi-dimensional composite motion guide rail; 501. Precursor gas one; 502. Precursor gas two; 801. Polishing gas outlet; 802. Polishing gas inlet; 1301. Linear guide rail; 1302. Circular guide rail. Detailed Implementation

[0046] The following is in conjunction with the appendix Figure 1-6 This application will be described in further detail.

[0047] This application discloses an all-dry semiconductor surface polishing apparatus based on reactive gases. (Refer to...) Figure 1 and Figure 2 The all-dry semiconductor surface polishing apparatus based on reactive gases includes a vacuum chamber 1, which is connected to a gas path system and an exhaust gas treatment system. The vacuum chamber 1 contains a gas injection area and a mechanical polishing area. The gas injection area is equipped with a multi-hole array injection device 8, and the mechanical polishing area is equipped with a polishing disc 12 and a sample carrying mechanism.

[0048] Reference Figure 1 and Figure 3 The gas path system includes a carrier gas cylinder 3, two polishing gas cylinders 5, and a pipeline 2. The two polishing gas cylinders 5 are respectively filled with precursor gas one 501 and precursor gas two 502. Precursor gas one 501 interacts with the surface of the sample 10 to be polished to form a molecular-level saturated adsorption layer, and precursor gas two 502 reacts with the molecular-level saturated adsorption layer through a self-limiting reaction to generate a weakly bonded modified layer. In this embodiment, precursor gas one 501 is a chlorine-containing gas, such as chlorine; precursor gas two 502 is an oxygen-containing gas, such as oxygen or ozone; and the carrier gas is an inert gas, such as argon. Furthermore, the outlet ends of the carrier gas cylinder 3 and the two polishing gas cylinders 5 are each equipped with an independent solenoid valve 4 to control the independent opening and closing of the carrier gas, precursor gas one 501, and precursor gas two 502 gas paths.

[0049] Reference Figure 2 and Figure 4The multi-hole array injection device 8 is connected to the gas path system and is used to carry and alternately inject precursor gas 1 501 / precursor gas 2 502 via carrier gas. Specifically, the multi-hole array injection device 8 is disc-shaped and includes a polishing gas outlet 801 and a polishing gas inlet 802. The polishing gas inlet 802 is connected to the gas outlet of the gas path system. The polishing gas outlet 801 includes multiple micropores distributed in an array. The micropores have a uniform diameter and are no larger than 2 mm. The micropore array is uniformly distributed and the density is no less than 20 pores / cm². 2 This is to achieve uniform gas injection.

[0050] Reference Figure 2 The polishing disc 12 is rotatably disposed in the mechanical grinding area of ​​the vacuum chamber 1. A polishing pad 11 is fixed on the surface of the polishing disc 12 for peeling off the weakly bonded modified layer on the surface of the sample 10 to be polished.

[0051] Reference Figure 2 The sample carrying mechanism includes a polishing head 9 for fixing the sample 10 to be polished. Driven by a multi-dimensional composite motion guide rail 13, the polishing head 9 carries the sample 10 to be polished and moves horizontally between the gas injection area and the mechanical grinding area, as well as performing circular motion and rotation within the mechanical grinding area. Specifically, refer to... Figure 5 The multidimensional composite motion guide rail 13 includes a linear guide rail 1301 and an annular guide rail 1302 disposed on the top wall of the vacuum chamber 1. The linear guide rail 1301 is connected to the annular guide rail 1302 and is located on the radial extension line of the annular guide rail 1302. The annular guide rail 1302 is coaxial with the polishing disk 12.

[0052] Reference Figure 1 The exhaust gas treatment system includes a vacuum pump 6 connected to the vacuum chamber 1 and an exhaust gas treatment and collection device 7. Unattached precursor gases and reaction byproducts are extracted to the exhaust gas collection and treatment system to eliminate residual pollution.

[0053] Using the aforementioned all-dry semiconductor surface polishing apparatus based on reactive gas, all-dry polishing of gallium nitride wafers was performed, with reference to... Figure 6 This includes the following steps:

[0054] Step 1, Polishing Preparation:

[0055] The gallium nitride wafer is mounted on the polishing head 9, and the vacuum chamber 1 is evacuated.

[0056] Step 2, Polishing gas injection:

[0057] The horizontally moving polishing head 9 is moved to the gas injection area, where argon gas carries chlorine gas and is injected onto the surface of the gallium nitride wafer for 2 seconds through the multi-hole array injection device 8. The chlorine gas interacts with the surface of the gallium nitride wafer to form a molecular-level gallium chloride adsorption layer.

[0058] Purge with argon gas for 10 seconds to remove any unadsorbed gases;

[0059] Argon gas carrying oxygen is sprayed onto the surface of a gallium nitride wafer for 2 seconds through a porous array spraying device 8, triggering a self-limiting reaction to generate a weakly bonded chlorination-oxidation modified layer. This modified layer blocks oxygen from diffusing into deeper layers, and the reaction automatically terminates at the surface nanoscale modified layer.

[0060] Purge with argon gas for 10 seconds to remove byproducts.

[0061] The above polishing gas injection steps can be repeated once or multiple times.

[0062] Step 3, Mechanical grinding:

[0063] The polishing head 9 is moved horizontally to the mechanical grinding area, and pressure is applied to bring the polishing pad 11 into contact with the sample 10 to be polished. Simultaneously, the sample 10 is driven to rotate and rotate, while the polishing disk 12 is also driven to rotate. The polishing pad 11 peels off the weakly bonded modification layer on the surface of the gallium nitride wafer. By adjusting the pressure and rotation speed of the polishing disk 12 and the rotation speed of the polishing head 9, stable material removal is achieved, improving polishing efficiency.

[0064] During the polishing gas injection and mechanical grinding process, the vacuum environment of vacuum chamber 1 is maintained, while the unattached polishing gas and reaction byproducts are extracted to the exhaust gas collection and treatment system. In this embodiment, the exhaust gas undergoes two-stage treatment: alkaline solution absorption and conversion of solid gallium hydroxide, and calcium-based solidification of chlorine residue, achieving zero emissions of pollutants and resource recovery.

[0065] Step 4, Polishing complete:

[0066] After purging with argon gas, the vacuum chamber 1 is depressurized, and the sample is removed.

[0067] This application achieves precise surface modification of the sample 10 to be polished through a stepwise action of dual-path reactive gases under time-controlled conditions. First, precursor gas 501 interacts with the surface of the sample 10 to form a molecular-level saturated adsorption layer. Then, precursor gas 502 reacts with the molecular-level saturated adsorption layer through a self-limiting reaction to generate a weakly bonded modification layer, completing a damage-free surface reconstruction. The modified sample 10 is dynamically matched with a high-speed rotating polishing disk 12 under the drive of a multi-dimensional composite motion guide rail 13, achieving the peeling of the weakly bonded modification layer. This reduces the surface roughness of the sample 10 to the nanometer level without the involvement of a liquid medium. This application improves upon the problems of liquid residue contamination, edge effects, and high waste liquid treatment costs associated with wet chemical mechanical polishing, while overcoming the defects of dry technology such as poor surface roughness and uneven reaction. It is suitable for the precision processing of large-size silicon wafers and third-generation semiconductor materials such as silicon carbide and gallium nitride.

[0068] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A fully dry semiconductor surface polishing method based on reactive gases, characterized in that: A fully dry semiconductor surface polishing apparatus based on reactive gases is employed, the apparatus comprising: The vacuum chamber contains a gas injection area and a mechanical grinding area. The gas path system includes a carrier gas cylinder and two polishing gas cylinders, the two polishing gas cylinders being respectively filled with precursor gas one and precursor gas two; precursor gas one is a chlorine-containing gas, and precursor gas two is an oxygen-containing gas; the gas path system is configured to: through the stepwise action of the dual-path reaction gases under time-controlled conditions, firstly, precursor gas one reacts with the surface of the sample to be polished to form a molecular-level saturated adsorption layer, and then precursor gas two reacts with the molecular-level saturated adsorption layer to generate a weakly bonded modified layer through a self-limiting reaction; A multi-hole array injection device is disposed in the gas injection area of ​​the vacuum chamber. The multi-hole array injection device is connected to the gas path system and is used to carry and alternately inject precursor gas one / precursor gas two through carrier gas. A polishing disc is rotatably disposed in the mechanical grinding area within the vacuum chamber. A polishing pad is fixed on the surface of the polishing disc for peeling off the weakly bonded modified layer on the surface of the sample to be polished. The sample carrying mechanism drives the sample to be polished to move horizontally between the gas injection area and the mechanical grinding area through a multi-dimensional composite motion guide rail, and to perform circular motion and rotation in the mechanical grinding area. The method includes the following steps: Polishing preparation: Install the sample to be polished onto the sample carrier and evacuate the vacuum chamber; Polishing gas injection: The sample to be polished is moved horizontally to the gas injection area, and the following step-by-step operations are performed in a time-controlled manner on the sample through a multi-hole array injection device: A precursor gas is sprayed onto the surface of the sample to be polished, and the precursor gas interacts with the surface of the sample to be polished to form a molecular-level saturated adsorption layer. Carrier gas purging removes unadsorbed gases; Precursor gas 2 is sprayed onto the surface of the sample to be polished. Precursor gas 2 reacts with the molecular-level saturated adsorption layer to generate a weakly bonded modified layer through a self-limiting reaction. Secondary carrier gas purging removes byproducts; Mechanical grinding: The sample to be polished is moved horizontally to the mechanical grinding area, and pressure is applied to make the polishing pad contact the sample to be polished; the sample to be polished is simultaneously driven to rotate and rotate, while the polishing disk is driven to rotate, and the polishing pad peels off the weak bonded modified layer on the surface of the sample to be polished.

2. The all-dry semiconductor surface polishing method based on reactive gas according to claim 1, characterized in that: The multidimensional composite motion guide rail includes a linear guide rail and an annular guide rail disposed on the top wall of the vacuum chamber. The linear guide rail is connected to the annular guide rail and is located on the radial extension line of the annular guide rail. The annular guide rail is coaxial with the polishing disk.

3. The all-dry semiconductor surface polishing method based on reactive gas according to claim 1, characterized in that: The outlet of the carrier gas cylinder and the two polishing gas cylinders are each equipped with an independent solenoid valve.

4. The all-dry semiconductor surface polishing method based on reactive gas according to claim 1, characterized in that: The multi-hole array injection device includes a polishing gas outlet and a polishing gas inlet. The polishing gas inlet is connected to the gas outlet of the gas path system, and the polishing gas outlet includes multiple micropores distributed in an array.

5. The all-dry semiconductor surface polishing method based on reactive gas according to claim 1, characterized in that: The device also includes an exhaust gas treatment system, which includes a vacuum pump connected to the vacuum chamber and an exhaust gas treatment and collection device.

6. The all-dry semiconductor surface polishing method based on reactive gas according to claim 1, characterized in that: In the method, the polishing gas injection step is performed once or repeatedly in cycles.

7. The all-dry semiconductor surface polishing method based on reactive gas according to claim 1, characterized in that: The method further includes the following steps: maintaining the vacuum environment of the vacuum chamber during polishing gas injection and mechanical grinding.

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