Boron trifluoride mixed gas and use method thereof

Abstract

According to the boron trifluoride mixed gas, a fluid supply container is filled with the mixed gas in sequence, a fluid supply container is filled with the mixed gas in sequence, the mixed gas comprises doping gas and auxiliary gas, the doping gas is boron trifluoride, and the volume percent of the boron trifluoride is 80%-92%; the auxiliary gas is hydrogen sulfide, and the volume percent of the hydrogen sulfide is 1%-10%; the auxiliary gas can also comprise hydrogen; according to the mixed gas system based on boron trifluoride, hydrogen sulfide is introduced or hydrogen and hydrogen are jointly used as auxiliary gas, and the ratio is optimized, so that the working environment of the ion source is accurately regulated and controlled, metal material loss and redeposition caused by halogen circulation are remarkably reduced, and the corrosion rate of an electrode and generation of granular byproducts are reduced.

Description

Technical Field

[0001] This invention relates to a mixed gas, and more particularly to a boron trifluoride mixed gas and its method of use. Background Technology

[0002] Ion implantation is a key technology for doping substrates in semiconductor manufacturing. It involves ionizing a dopant gas using an ion source, followed by extraction, sieving, and focusing to form a stable beam that alters the electrical properties of the material. The continuous and stable operation of the ion source is crucial for equipment utilization, but its lifespan is often limited by problems such as cathode breakdown and accumulation of deposits on the cavity walls. These failures mainly stem from the sputtering erosion of internal materials by plasma and the halogen cycle triggered by reactive free radicals (such as fluorine) released from the ionization of halide gases. This process easily generates non-volatile byproducts that deposit within the cavity.

[0003] Existing technologies typically require the introduction of specific reactive or protective gaseous media into the ion source to attempt to mitigate corrosion and inhibit deposition. For example, when hydrogen is mixed with fluoride, the hydrogen will decompose into hydrogen atoms in the plasma and react with a large number of fluorine radicals to generate stable hydrogen fluoride, which is then removed from the ion source equipment via a vacuum system. However, in practical applications, increasing the hydrogen ratio to extend the equipment's lifespan will lead to a decrease in the final beam current, thus affecting product performance. Conversely, decreasing the hydrogen ratio to pursue a better beam current will shorten the equipment's lifespan. Therefore, even within the currently optimal hydrogen ratio range, tungsten deposits will still form in the ion source chamber, requiring equipment shutdown for maintenance. Conventional mixed gas schemes often struggle to achieve an effective balance between multiple key requirements such as inhibiting halogen corrosion, reducing sputtering erosion, maintaining plasma stability, and controlling byproduct deposition. This results in limited protective effects, a narrow process window, and the potential introduction of new instabilities or contamination risks due to improper gas compatibility, thus restricting further improvements in ion source lifespan and process consistency. Summary of the Invention

[0004] In view of this, in order to overcome the above problems, the present invention provides a boron trifluoride mixed gas and a method for using the same, which solves the pollution problem in the application of ion implantation systems by optimizing the ratio parameters of the mixed gas.

[0005] A boron trifluoride mixed gas, characterized in that the mixed gas is sequentially filled into a fluid supply container, the mixed gas comprising a dopant gas and an auxiliary gas, wherein the dopant gas is boron trifluoride with a volume percentage of 80% to 92%; and the auxiliary gas is at least one or more of hydrogen sulfide and hydrogen.

[0006] Furthermore, the volume percentage of the hydrogen sulfide is 1% to 10%.

[0007] Furthermore, the hydrogen volume percentage is 5% to 15%.

[0008] Furthermore, the total volume percentage of the auxiliary gas used in the blending of hydrogen sulfide and hydrogen is controlled to be ≤15%.

[0009] Furthermore, the volume percentage of hydrogen sulfide is controlled at 2% to 4%.

[0010] Furthermore, the mixed gas also contains an inert gas, which includes at least one of argon, krypton, neon, nitrogen, xenon, or deuterium.

[0011] Furthermore, the mixed gas is filled into a fluid supply container. The filling sequence is as follows: first, boron trifluoride gas is filled into the container, followed by auxiliary gas. After filling, the container is removed and rotated to ensure thorough mixing.

[0012] The method of using boron trifluoride mixed gas involves delivering the mixed gas to the arc chamber of an ion source device, ionizing the mixed gas in the arc chamber to form an ion beam, and directional embedding of impurities by collisions between the ion beam and lattice atoms to form a pre-amorphous layer.

[0013] Furthermore, the change in cathode weight before and after the 10H test in the arc chamber is -0.030g to -0.005g, and more preferably -0.015g to -0.005g.

[0014] Further, beam current testing was conducted, B + The beam current remains stable at ≥5 mA.

[0015] The beneficial effects of this invention are as follows: By innovatively improving the boron trifluoride-based mixed gas system, introducing hydrogen sulfide or hydrogen as an auxiliary gas, and optimizing its ratio, the working environment of the ion source (arc chamber) is precisely controlled, thereby achieving positive effects in many aspects, significantly reducing the loss and redeposition of metal materials caused by halogen cycling, and reducing the corrosion rate of the electrode and the generation of particulate byproducts. Attached Figure Description

[0016] Figure 1 A simplified diagram of the ion implantation process.

[0017] Figure 2 The graph shows the relationship between the hydrogen mixing ratio and the beam current. Detailed Implementation

[0018] To explain in detail the possible application scenarios, technical principles, specific feasible solutions, and the objectives and effects that this application can achieve, the following detailed description is provided in conjunction with the specific embodiments listed.

[0019] The embodiments described in this invention are only used to illustrate the technical solutions of this application more clearly, and are therefore only examples and should not be used to limit the scope of protection of this application.

[0020] In this invention, the term "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment can be included in at least one embodiment of this application. The term "embodiment" appearing in various places in the specification does not necessarily refer to the same embodiment, nor does it specifically limit its independence or connection with other embodiments. In principle, in this application, as long as there is no technical contradiction or conflict, the technical features mentioned in each embodiment can be combined in any way to form a corresponding implementable technical solution.

[0021] Unless otherwise defined, the technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the use of related terms in this invention is merely for describing specific embodiments and is not intended to limit this application.

[0022] In the description of this application, the term "and / or" is used to describe the logical relationship between objects, indicating that three relationships can exist. For example, A and / or B means: A exists, B exists, and A and B exist simultaneously. Additionally, in this invention, the character " / " generally indicates that the preceding and following objects have an "or" logical relationship.

[0023] In this application, terms such as “first” and “second” are used only to distinguish one entity or operation from another, and do not necessarily require or imply any actual quantity, hierarchy or order relationship between these entities or operations.

[0024] Unless otherwise specified, the use of terms such as “comprising,” “including,” “having,” or other similar expressions in this application is intended to cover non-exclusive inclusion, which does not exclude the presence of additional elements in a process, method, or product that includes the stated elements, such that a process, method, or product that includes a list of elements may include not only those defined elements but also other elements not expressly listed, or elements inherent to such a process, method, or product.

[0025] Similar to the understanding in the Examination Guidelines, in this application, expressions such as "greater than," "less than," and "exceeding" are understood to exclude the stated number; expressions such as "above," "below," and "within" are understood to include the stated number. Furthermore, in the description of the embodiments in this application, "multiple" means two or more (including two), and similar expressions related to "multiple" are also understood in this way, such as "multiple groups" and "multiple times," unless otherwise explicitly specified.

[0026] A boron trifluoride mixed gas, characterized in that the mixed gas is sequentially filled into a fluid supply container, the mixed gas comprising a dopant gas and an auxiliary gas, wherein the dopant gas is boron trifluoride with a volume percentage of 80% to 92%; and the auxiliary gas is at least one or more of hydrogen sulfide and hydrogen.

[0027] In some implementations, doping with a certain amount of hydrogen sulfide (H2S) helps reduce the halogen reaction between fluorine radicals in the ion source and tungsten metal in the chamber.

[0028] Through extensive mixing, verification, and testing, the researchers developed this solution and discovered that introducing hydrogen sulfide (H2S) and a fluoride-containing mixed hydrogen gas into the ion source, under plasma conditions, ionizes the doped gas. Due to the high reactivity of the generated fluorine radicals, these radicals preferentially react with hydrogen sulfide (H2S) in the gas phase. This process exhibits a high reaction rate. Considering both the reaction phase and the degrees of freedom of molecular motion, both fluorine radicals and hydrogen sulfide are gaseous molecules, resulting in a high reaction probability. The uniform distribution of hydrogen sulfide (H2S) in the plasma... When the concentration of fluorine radicals (H2S) is higher than that of tungsten in solid state, they are more easily captured by hydrogen sulfide (H2S) molecules. Therefore, the introduced hydrogen sulfide (H2S) can rapidly and preferentially consume free fluorine radicals in the plasma and form inert and volatile sulfur hexafluoride (SF6) through subsequent reactions, thus effectively removing them. In addition, the introduction of hydrogen sulfide (H2S) also provides an additional hydrogen source. Hydrogen atoms (H) combine with corrosive fluorine atoms (F) to generate volatile HF, which is then removed. Therefore, the introduction of hydrogen sulfide significantly improves the cleaning efficiency of the arc chamber. However, if too much hydrogen sulfide (H2S) is introduced, the high concentration of gaseous sulfur source produced by its decomposition will react with tungsten in the ion source under certain conditions, forming tungsten sulfide deposits. These deposits contaminate the ion source, reducing electrode efficiency and requiring increased power to maintain discharge, thereby shortening cathode losses. Therefore, the volume of hydrogen sulfide is further controlled at 1%~10%, preferably 1%~8%, and even more preferably 2%~4%.

[0029] In some embodiments, the auxiliary gas further comprises 5% to 15% hydrogen, and the active hydrogen atoms (H atoms) generated in the plasma by the hydrogen further contribute to its composition. +It can effectively bind to and remove excess corrosive fluorine free radicals (F). + The hydrogen is converted into volatile hydrogen fluoride (HF) and discharged, which directly slows down the etching of tungsten, molybdenum and other electrode materials by fluorine, thereby significantly reducing the loss and redeposition of metal materials caused by halogen cycling. However, in actual tests, adding too much hydrogen will cause the gas to be diluted, the beam intensity will decrease significantly, the injection time will be greatly extended, and the production efficiency will decrease. Therefore, the hydrogen volume percentage is preferably 7% to 14%, and more preferably 8% to 10%.

[0030] In some embodiments, the mixed gas also contains an inert gas, including at least one of argon, krypton, neon, nitrogen, xenon, or deuterium.

[0031] In some embodiments, the mixed gas is filled into a fluid supply container, which is filled in sequence: first boron trifluoride gas is added into the container, then an auxiliary gas is added. After filling, the container is removed, rotated, and thoroughly mixed.

[0032] like Figure 1 As shown, the mixed gas is delivered to the arc chamber of the ion source device, where it is ionized to form ions. The extraction component extracts the ions to form a preliminary beam. Then, a magnet is used to deflect ions of different masses to select the desired ions. High pressure is applied through an accelerating tube to provide kinetic energy for the ions to collide with the lattice atoms of the wafer in the process chamber to achieve directional embedding and form a pre-amorphous layer.

[0033] The change in cathode weight before and after the 10-hour test in the arc chamber is -0.030g to -0.005g, and is further preferably -0.015g to -0.005g.

[0034] The following are specific implementation experimental examples for verification, which are only used as preferred options to illustrate and verify the process and technical effects of the above preparation process.

[0035] Group A: Calculate the required mass or partial pressure for filling pure boron trifluoride, and calibrate the relevant high-precision pressure gauges and weighing instruments; then, fill the container with boron trifluoride at a low and steady flow rate, and let it stand vertically after filling is completed.

[0036] Group B: Accurately calculate the required mass or partial pressure for filling with 75% boron trifluoride and 25% hydrogen, and calibrate the relevant high-precision pressure gauges and weighing instruments; then, first fill the container with boron trifluoride at a low and steady flow rate. After filling is complete, continue to introduce hydrogen as a buffer component until the pressure reaches the preset total filling pressure; finally, place the gas cylinder horizontally on a rolling machine or rotating frame and roll it at a low speed for at least 30 minutes to ensure uniform mixing. After mixing is complete, let it stand vertically.

[0037] Group C: Accurately calculate the required mass or partial pressure for filling 92% boron trifluoride and 8% hydrogen sulfide, and calibrate the relevant high-precision pressure gauges and weighing instruments; then, first fill the container with boron trifluoride at a low and steady flow rate. After filling is complete, continue to introduce hydrogen sulfide as a buffer component until the pressure reaches the preset total filling pressure; finally, place the gas cylinder horizontally on a rolling machine or rotating frame and roll it at a low speed for at least 30 minutes to ensure uniform mixing. After mixing is complete, let it stand vertically.

[0038] Group D: Accurately calculate the required mass or partial pressure for filling 80% boron trifluoride, 15% hydrogen, and 5% hydrogen sulfide, and calibrate the relevant high-precision pressure gauges and weighing instruments; then, first fill the container with boron trifluoride at a low and steady flow rate. After filling is complete, continuously introduce hydrogen as a buffer component, and finally introduce hydrogen sulfide until the pressure reaches the preset total filling pressure; finally, place the gas cylinder horizontally on a rolling machine or rotating frame and roll it at a low speed for at least 30 minutes to ensure uniform mixing. After mixing is complete, let it stand vertically.

[0039] Group E: Accurately calculate the required mass or partial pressure for filling 85% boron trifluoride, 10% hydrogen, and 5% hydrogen sulfide, and calibrate the relevant high-precision pressure gauges and weighing instruments; then, first fill the container with boron trifluoride at a low and steady flow rate. After filling is complete, continuously introduce hydrogen as a buffer component, and finally introduce hydrogen sulfide until the pressure reaches the preset total filling pressure; finally, place the gas cylinder horizontally on a rolling machine or rotating frame and roll it at a low speed for at least 30 minutes to ensure uniform mixing. After mixing is complete, let it stand vertically.

[0040] Group F: Accurately calculate the required mass or partial pressure for filling 85% boron trifluoride, 7% hydrogen, and 8% hydrogen sulfide, and calibrate the relevant high-precision pressure gauges and weighing instruments; then, first fill the container with boron trifluoride at a low and steady flow rate. After filling is complete, continuously introduce hydrogen as a buffer component, and finally introduce hydrogen sulfide until the pressure reaches the preset total filling pressure; finally, place the gas cylinder horizontally on a rolling machine or rotating frame and roll it at a low speed for at least 30 minutes to ensure uniform mixing. After mixing is complete, let it stand vertically.

[0041] Group G: Accurately calculate the required mass or partial pressure for filling 80% boron trifluoride, 14% hydrogen, and 6% hydrogen sulfide, and calibrate the relevant high-precision pressure gauges and weighing instruments; then, first fill the container with boron trifluoride at a low and steady flow rate. After filling is complete, continuously introduce hydrogen as a buffer component, and finally introduce hydrogen sulfide until the pressure reaches the preset total filling pressure; finally, place the gas cylinder horizontally on a rolling machine or rotating frame and roll it at a low speed for at least 30 minutes to ensure uniform mixing. After mixing is complete, let it stand vertically.

[0042] Group H: Accurately calculate the required mass or partial pressure for filling 86% boron trifluoride, 10% hydrogen, and 4% hydrogen sulfide, and calibrate the relevant high-precision pressure gauges and weighing instruments; then, first fill the container with boron trifluoride at a low and steady flow rate. After filling is complete, continuously introduce hydrogen as a buffer component, and finally introduce hydrogen sulfide until the pressure reaches the preset total filling pressure; finally, place the gas cylinder horizontally on a rolling machine or rotating frame and roll it at a low speed for at least 30 minutes to ensure uniform mixing. After mixing is complete, let it stand vertically.

[0043] Group I: Accurately calculate the required mass or partial pressure for filling 90% boron trifluoride, 8% hydrogen, and 2% hydrogen sulfide, and calibrate the relevant high-precision pressure gauges and weighing instruments; then, first fill the container with boron trifluoride at a low and steady flow rate. After filling is complete, continuously introduce hydrogen as a buffer component, and finally introduce hydrogen sulfide until the pressure reaches the preset total filling pressure; finally, place the gas cylinder horizontally on a rolling machine or rotating frame and roll it at a low speed for at least 30 minutes to ensure uniform mixing. After mixing is complete, let it stand vertically.

[0044] Group J: Accurately calculate the required mass or partial pressure for filling 85% boron trifluoride, 5% hydrogen, 5% hydrogen sulfide, and 5% deuterium, and calibrate the relevant high-precision pressure gauges and weighing instruments; then, first fill the container with boron trifluoride at a low and steady flow rate. After filling is complete, continuously introduce hydrogen and deuterium as buffer components, and finally introduce hydrogen sulfide until the pressure reaches the preset total filling pressure; finally, place the gas cylinder horizontally on a rolling machine or rotating frame and roll it at a low speed for at least 30 minutes to ensure uniform mixing. After mixing is complete, let it stand vertically.

[0045] Each of the above groups of examples will be analyzed using B. + In beam current testing, the ion beam current is measured using a Faraday cup, which is installed in the beam path. When the ion beam enters the cup, its charge is collected and converted into a current signal, thus enabling the monitoring of the beam current.

[0046] The above examples were subjected to ion implantation cathode weight change tests, with the following basic test conditions: BF3 flow rate: 1 sccm Ion source: 25 mA Arc voltage: 90V Lead-out voltage: 30 kV Suppression voltage: 3.5 kV Experimental mode: Fixed ion source Test duration: 10 hours

[0047]

[0048] As shown in the table above, Comparative Example A is pure boron trifluoride. The halogen cycle is initiated by the fluorine radicals released by the ionization of the gas. This process easily generates non-volatile byproducts and deposits them in the chamber, thus the cathode weight increases significantly before and after the test.

[0049] In Comparative Example B, the gas was filled with 75% boron trifluoride and 25% hydrogen. The higher proportion of hydrogen diluted the effective boron concentration of the doped BF3, resulting in... + The ion beam current was significantly reduced, resulting in a substantial increase in the implantation time.

[0050] In Example C, the cathode was filled with 92% boron trifluoride and 8% hydrogen sulfide. The introduction of H2S served a dual purpose: firstly, it provided a hydrogen source, preferentially combining with highly reactive fluorine (F) radicals to generate hydrogen fluoride (HF); secondly, sulfur could react with excess fluorine to generate inert and volatile sulfur hexafluoride (SF6). These two mechanisms worked synergistically to effectively reduce the etching rate of the fluorine radicals on the tungsten cathode electrode, resulting in only a slight decrease in the cathode's weight after testing.

[0051] In the example, the DG group was supplemented with 80%~85% boron trifluoride, 7%~14% hydrogen, and 5%~8% hydrogen sulfide. Based on the above reaction mechanism, by optimizing the proportions of each auxiliary gas, the total amount of auxiliary gas was reduced while maintaining the fluorine etching inhibition effect. Consequently, the cathode etching rate was controlled, and the weight loss was minimal.

[0052] Examples H and I include 85%–90% boron trifluoride, 8%–10% hydrogen, and 2%–4% hydrogen sulfide as an auxiliary gas. This formulation achieves a better balance between maximizing the BF3 proportion and minimizing the total amount of auxiliary gas. Therefore, this group achieves the highest BF3 content compared to other examples. + The beam current and the lowest cathode etching rate (minimum weight change) significantly extend electrode lifespan.

[0053] In Example J, 5% more deuterium was added and the ratio of hydrogen to hydrogen sulfide was adjusted. Approximately 5% deuterium was introduced, and the ratio of H2 to H2S was fine-tuned. The mechanism of action of deuterium is similar to that of hydrogen, but due to its greater mass, it helps to further stabilize the beam. Experimental results show that this combination also achieved a lower cathode etch rate.

[0054] In summary, by controlling the total volume percentage of the auxiliary gas (hydrogen sulfide or a mixture of hydrogen and deuterium) to ≤15%, and further specifically controlling the volume percentage of hydrogen sulfide within the range of 2%~4%, a synergistic optimization effect can be achieved in the ion implantation process. On the one hand, it effectively suppresses the etching of tungsten electrodes by fluorine, significantly reducing the cathode loss rate; on the other hand, it maintains a high concentration of effective boron in the plasma, thereby enhancing the biomass of boron. +The beam current remains consistently at a high level of ≥5 mA. This invention significantly improves process efficiency and extends the lifespan of critical consumables in the equipment.

[0055] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A boron trifluoride mixed gas, characterized in that, The mixed gas is sequentially filled into a fluid supply container. The mixed gas includes a dopant gas and an auxiliary gas. The dopant gas is boron trifluoride, and the volume percentage of boron trifluoride is 80% to 92%. The auxiliary gas is at least one or more of hydrogen sulfide and hydrogen.

2. The boron trifluoride mixed gas according to claim 1, characterized in that, The volume percentage of hydrogen sulfide is 1% to 10%.

3. The boron trifluoride mixed gas according to claim 2, characterized in that, The hydrogen volume percentage is 5% to 15%.

4. The boron trifluoride mixed gas according to claim 3, characterized in that, The total volume percentage of the auxiliary gas mixed with hydrogen sulfide is controlled to be ≤15%.

5. The boron trifluoride mixed gas according to claim 4, characterized in that, The volume percentage of hydrogen sulfide is controlled between 2% and 4%.

6. The boron trifluoride mixed gas according to claim 3, characterized in that, The mixed gas also contains an inert gas, which includes at least one of argon, krypton, neon, nitrogen, xenon, or deuterium.

7. The boron trifluoride mixed gas according to claim 1, characterized in that, The mixed gas is filled into a fluid supply container. The filling sequence is as follows: first, boron trifluoride gas is added into the container, followed by auxiliary gas. After filling, the container is removed and rotated to ensure thorough mixing.

8. The method of using the boron trifluoride mixed gas according to any one of claims 1 to 7, characterized in that, The mixed gas is delivered to the arc chamber of the ion source device, where it is ionized to form an ion beam. The collision of the ion beam with lattice atoms enables the directional insertion of impurities, forming a pre-amorphous layer.

9. The method of using the boron trifluoride mixed gas according to claim 8, characterized in that, The weight change of the cathode in the arc chamber before and after the 10-hour test was -0.030g to -0.005g.

10. The method of using the boron trifluoride mixed gas according to claim 7, characterized in that, B + The beam current remains stable at ≥5 mA.

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