Radio frequency power distribution adjusting device and application thereof in PECVD (Plasma Enhanced Chemical Vapor Deposition) thin film deposition
The ceramic capacitor array is controlled through electronic switches and the RF power distribution is dynamically adjusted, which solves the process uniformity problem in PECVD equipment, and achieves the effects of cost reduction, reliability improvement and space saving, meeting the needs of efficient and precise film deposition.
Patent Information
- Application Number
- CN202510701122.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-28
- Publication Date
- 2025-08-19
AI Technical Summary
Existing PECVD equipment has process uniformity problems in multi-station design. Traditional RF power distribution adjustment devices are costly, have poor reliability, slow adjustment speed and large volume, making it difficult to meet the needs of efficient precision film deposition.
The ceramic capacitor array is controlled by electronic switches, and the impedance values of each branch are dynamically adjusted to achieve accurate distribution of radio frequency power and optimize the uniformity of plasma distribution.
Significantly reduce costs, improve reliability, improve adjustment speed, save space, and improve uniformity of multi-station thin film deposition process.
Smart Images
Figure CN120505608A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of PECVD equipment on a chip manufacturing production line, and in particular to a radio frequency power distribution and adjustment device and its application in PECVD thin film deposition. Background Art
[0002] To increase production capacity, PECVD equipment in chip production lines typically utilizes multiple stations within a single unit to process wafers in parallel. However, this multi-station design can lead to issues with process uniformity between stations. Process uniformity is primarily affected by temperature distribution, airflow distribution, and plasma distribution across the stations and wafers. While temperature and airflow distribution can be improved by optimizing the mechanical structure, plasma distribution is more complex and difficult to achieve with mechanical adjustments alone. Effective uniformity improvement requires integration with electrical control methods, such as RF power distribution adjustment.
[0003] The RF power distribution adjustment device can dynamically adjust the RF power distribution of each station according to the actual working conditions of the equipment, the characteristics of the airflow distribution and the specific process requirements, thereby optimizing the plasma distribution uniformity between different stations, and ultimately achieving an overall improvement in the uniformity of the multi-station thin film deposition process. Currently, there are two configurations of PECVD equipment: some equipment is not equipped with an RF power distribution adjustment device, resulting in limited equipment performance, affecting its application in advanced chip processes and precision thin film deposition processes; although the other part of the equipment is equipped with an adjustment device, it uses a traditional solution based on variable vacuum capacitors and motors, that is, the capacitance value is adjusted by driving the rotating parts of the variable vacuum capacitor by a motor. This traditional solution has significant defects:
[0004] 1. In terms of cost, the core component, the variable vacuum capacitor, costs up to RMB 10,000 per unit, significantly increasing the cost of the equipment;
[0005] 2. In terms of reliability, the capacitance value is adjusted by relying on motor-driven mechanical moving parts, which not only causes serious mechanical wear problems, but also has a mean time between failures (MTBF) of only about 100,000 hours for high-end motors, indicating poor reliability.
[0006] 3. In terms of adjustment speed, due to the limitation of motor movement speed, the capacitor adjustment response time is as long as seconds, which is difficult to meet the needs of fast adjustment;
[0007] 4. In terms of volume, the combination of the motor and the variable vacuum capacitor still has a structural defect of being bulky and cannot be integrated on a single PCB circuit board. Summary of the Invention
[0008] The purpose of the present invention is to provide a radio frequency power distribution and adjustment device and its application in PECVD thin film deposition, which controls the connection and disconnection of ceramic capacitors through electronic switches and dynamically adjusts the impedance value of each branch, thereby accurately adjusting the distribution ratio of radio frequency power in different branches and achieving uniform control of film thickness between wafers.
[0009] To achieve the above-mentioned purpose, the technical solution of the present application is: a radio frequency power distribution and adjustment device, comprising a plurality of parallel adjustment branches arranged between the radio frequency power supply RF and the ground GND, each adjustment branch including a branch filter and a branch load and a branch impedance adjustment mechanism arranged in parallel, the branch impedance adjustment mechanism including an inductor and a ceramic capacitor array arranged in parallel, and a corresponding electronic switch is arranged in front of each ceramic capacitor.
[0010] As a preferred solution of the present invention, the electronic switch is connected to the control system of the PECVD equipment.
[0011] As a preferred embodiment of the present invention, the ceramic capacitor includes a ceramic capacitor C1, a ceramic capacitor C2, a ceramic capacitor C3, ..., and a ceramic capacitor Cm, and the electronic switch includes an electronic switch M1, an electronic switch M2, an electronic switch M3, ..., and an electronic switch Mm. When the electronic switch M1 is turned on and the electronic switch M2, the electronic switch M3, ..., and the electronic switch Mm are all turned off, the adjusted impedance is jωL+1 / jωC1; when the electronic switch M1 and the electronic switch M2 are turned on and the electronic switches M3, ..., and the electronic switch Mm are all turned off, the adjusted impedance is jωL+1 / jω(C1+C2). Similarly, when the electronic switch M1, the electronic switch M2, the electronic switch M3, ..., and the electronic switch Mm are all turned on, the adjusted impedance is
[0012] As a preferred solution of the present invention, the capacitance values of the ceramic capacitors C1, C2, C3, ..., and Cm are distributed in binary multiples, that is, C2 = 2C1, C3 = 2C2 ... C m =2C m-1 .
[0013] As a preferred solution of the present invention, the total parallel capacitance of the ceramic capacitor C1, the ceramic capacitor C2, the ceramic capacitor C3, ..., and the ceramic capacitor Cm is:
[0014] The electronic switch M1 is turned on, and the electronic switches M2, M3, ..., M m When disconnected: the total parallel capacitance value is C1;
[0015] The electronic switch M2 is turned on, and the electronic switches M1, M3, ..., M m When disconnected: the total parallel capacitance is 2C1;
[0016] Electronic switches M1 and M2 are turned on, and electronic switches M3, ...M m When disconnected: the total parallel capacitance is 3C1;
[0017] The electronic switch M3 is turned on, and the electronic switches M1, M2, M4, ... m When disconnected: the total parallel capacitance is 4C1;
[0018] …
[0019] Electronic switches M1, M2, M3, ...M m When conducting: the total parallel capacitance is (2 m -1)C1.
[0020] As a preferred solution of the present invention, the proportional relationship between the capacitance adjustment step and the maximum total parallel capacitance value is shown in the following formula:
[0021]
[0022] Where d is the capacitance adjustment step size. The smaller the step size, the higher the adjustment accuracy of the RF power distribution.
[0023] As a preferred solution of the present invention, the electronic switch is a MOSFET device, an IGBT, or a vacuum relay.
[0024] The present invention also provides an application of the above-mentioned RF power distribution and adjustment device in PECVD thin film deposition, specifically comprising:
[0025] Get the deposition process menu RECIPE and read the Ki value of each adjustment branch of the current STEP;
[0026] Based on each Ki value, the corresponding electronic switch state value M is obtained;
[0027] The electronic switch state value M is converted into binary form. The binary bit corresponds to the on-off state of the electronic switches M1, M2, M3, ..., Mm. If the value of a certain bit in the binary is 1, the corresponding electronic switch is set to the on state. If the value of the bit is 0, the corresponding electronic switch is set to the off state.
[0028] As a preferred solution of the present invention, the method for obtaining the corresponding electronic switch state value M based on each Ki value is as follows:
[0029]
[0030] where K i is the K value corresponding to the i-th adjustment branch in the deposition process menu RECIPE, C sum is the total parallel capacitance value of the regulating branch, and C1 is the minimum capacitance value.
[0031] As a preferred solution of the present invention, the uniformity of the deposition film is optimized by setting the Ki value of each regulating branch or by setting the Ki value of each STEP.
[0032] By adopting the above technical solution, the present invention can achieve the following technical effects:
[0033] 1. The design adopts electronic switches and ceramic capacitor arrays, and the cost is only one tenth of the traditional variable vacuum capacitor solution, which greatly reduces the price.
[0034] 2. Based on electronic switches such as MOSFET devices, mechanical moving parts are completely eliminated, and the device's mean time between failures (MTBF) can reach 1 billion hours, which is 10% more reliable than traditional solutions. 4 times.
[0035] 3. The response time of the electronic switch reaches microseconds, which is 10% higher than the traditional mechanical solution with a speed of seconds. 6 times, enabling instantaneous and precise adjustment.
[0036] 4. This device can be integrated on a single PCB circuit board. Under the same area conditions, the thickness is only 1 / 3-1 / 5 of the traditional solution, which greatly saves installation space.
[0037] 5. Electronic switches avoid the wear and tear of traditional mechanical components, basically achieve maintenance-free operation, and significantly reduce operating costs. BRIEF DESCRIPTION OF THE DRAWINGS
[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.
[0039] Figure 1 This is a schematic diagram of the structure of the radio frequency power distribution and adjustment device;
[0040] Figure 2 This is the structural principle diagram of the branch impedance adjustment mechanism;
[0041] Figure 3 This is a flow chart for the application of RF power distribution and adjustment device in PECVD thin film deposition. DETAILED DESCRIPTION
[0042] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, this application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.
[0043] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, or electrical connections; direct connections, or indirect connections through an intermediate medium; and can refer to internal communication between two components or the interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.
[0044] Example 1
[0045] See also Figure 1 This embodiment provides a radio frequency power distribution and adjustment device, comprising a plurality of parallel adjustment branches arranged between a radio frequency power supply RF and a ground GND, each adjustment branch comprising a branch filter and a branch load and a branch impedance adjustment mechanism arranged in parallel. Figure 2 As shown, the branch impedance adjustment mechanism includes an inductor and a ceramic capacitor array arranged in parallel, and a corresponding electronic switch is set in front of each ceramic capacitor; the ceramic capacitor array includes ceramic capacitors C1, C2, C3, ..., and Cm, and the corresponding electronic switches are electronic switches M1, M2, M3, ..., and Mm.
[0046] As a preferred implementation provided in this embodiment, the electronic switch is connected to the control system of the PECVD equipment (such as PLC, industrial computer board, etc.), and the control system can control the on and off of each electronic switch by issuing instructions.
[0047] Specifically, when the electronic switch M1 is turned on and the electronic switches M2, M3, ..., and Mm are all turned off, the regulated impedance is jωL+1 / jωC1; when the electronic switches M1 and M2 are turned on and the electronic switches M3, ..., and Mm are all turned off, the regulated impedance is jωL+1 / jω(C1+C2). Similarly, when the electronic switches M1, M2, M3, ..., and Mm are all turned on, the regulated impedance is With the adjustment impedance Z d1 ,Z d2 ,Z d3 ...Z dn Changes in branch load Z l1 ,Zl2 ,Z l3 ...Z ln The RF power applied above will change, for example, the RF power supply RF output voltage V rf Under the condition of no change, the branch load Z l1 The RF voltage V zl1 As shown in the following formula:
[0048]
[0049] RF voltage V Zl1 The change of the branch impedance Z l1 The RF power P Zl1 :
[0050]
[0051] By dynamically adjusting the RF power of each workstation, the plasma distribution uniformity between different workstations is optimized, and ultimately the overall uniformity of the multi-workstation thin film deposition process is improved.
[0052] In this embodiment, the capacitance values of the ceramic capacitors C1, C2, C3, ..., and Cm can be freely selected according to the requirements of the equipment and process. However, in order to obtain a smoother capacitance distribution, it is preferred that the capacitance values of the above capacitors present a binary multiple distribution, that is, C2 = 2C1, C3 = 2C2 ... C m =2C m-1 The above capacitance distribution can be combined to produce the following total parallel capacitance value:
[0053] The electronic switch M1 is turned on, and the electronic switches M2, M3, ..., M m When disconnected: the total parallel capacitance value is C1;
[0054] The electronic switch M2 is turned on, and the electronic switches M1, M3, ..., M m When disconnected: the total parallel capacitance is 2C1;
[0055] Electronic switches M1 and M2 are turned on, and electronic switches M3, ...M m When disconnected: the total parallel capacitance is 3C1;
[0056] The electronic switch M3 is turned on, and the electronic switches M1, M2, M4, ... m When disconnected: the total parallel capacitance is 4C1;
[0057] …
[0058] Electronic switches M1, M2, M3, ...M m When conducting: the total parallel capacitance is (2 m-1) C1. The larger the number of parallel capacitors m, the more parallel capacitor combinations can be achieved. If a maximum total parallel capacitance value is selected, the larger m is, the smaller C1 is, which means the capacitance adjustment step is smaller. This is reflected in the PECVD equipment, the more precise the RF power distribution adjustment is, and the better the uniformity of the thin film deposition process between wafers is, as shown in Table 1. The proportional relationship between the capacitance adjustment step and the maximum total parallel capacitance value is shown in the following formula:
[0059]
[0060] Table 1 Relationship between the number of parallel paths and regulation accuracy
[0061] Number of parallel paths m The proportional relationship between the adjustment step and the maximum capacitance d 3 14.3％ 4 6.7％ 5 3.2％ 6 1.6％ 7 0.8％ ……
[0062] On PECVD equipment, electronic switches M1, M2, M3...Mm are usually MOSFETs, which can also be replaced by IGBTs, vacuum relays, etc. depending on parameters such as withstand voltage and power.
[0063] This embodiment uses ceramic capacitors to form a parallel array, and uses electronic switches to switch the capacitors in and out, thereby changing the branch impedance value and adjusting the distribution of RF power in different branches; the capacitance values in the capacitor parallel array are C1, 2C1, 4C1, 8C1...2 m The multiple distribution of C1, combined with the electronic switch, can achieve the total capacitance value of the branch parallel connection to be C1, 2C1, 3C1, 4C1... (2 m+1 -1) The smooth distribution of C1 is conducive to more precise setting of the RF allocation of each regulation branch.
[0064] This device is used in Dalian Haoyu's 12-inch PECVD equipment. The equipment has two RF sources, 13.56MHz and 400kHz. Each RF source is equipped with a dedicated RF power distribution adjustment device. The adjustment device impedance Z of the 13.56MHz RF source is f =13.45+j41.34, L=1.6uH, C1=2pF, C2=4pF, C3=8pF, C4=16pF, C5=32pF, the electronic switches are all Infineon MOSFETs; the impedance of the regulating device of the 400kHz RF source is Z f =10.73+j188.66, L = 24uH, C1 = 20pF, C2 = 40pF, C3 = 80pF, C4 = 160pF, C5 = 320pF, and the electronic switches M are all Infineon MOSFETs. Practical verification shows that this system significantly outperforms traditional solutions in terms of cost, reliability, regulation speed, and size.
[0065] Example 2
[0066] See also Figure 3This embodiment provides an application of the RF power distribution adjustment device described in Example 1 in PECVD thin film deposition, specifically including:
[0067] S1. Get the deposition process menu RECIPE;
[0068] S2. Read the Ki value of each adjustment branch of the current step (set according to the difference in film thickness of each station during the experiment);
[0069] S3. Obtain the corresponding electronic switch state value M based on each Ki value;
[0070] For example, the K value corresponding to a certain regulation branch in the RECIPE parameter is set to 60. The K value represents a percentage. The impedance adjustment mechanism of this branch contains 7 parallel capacitors with capacitances of 2.5pF, 5pF, 10pF, 20pF, 40pF, 80pF, and 160pF. The M value can be calculated as follows:
[0071]
[0072] Ignore the number of digits after the decimal point and keep only the integer part, then the value of M is 76;
[0073] S4. Convert the electronic switch state value M into binary form. The binary bits correspond to the on / off states of the electronic switches M1, M2, M3, ..., Mm. If a binary bit value is 1, the corresponding electronic switch is set to the on state. If the binary bit value is 0, the corresponding electronic switch is set to the off state.
[0074] Specifically, the M value is 76, which is represented by 1001100 in binary. Counting from the least significant bit (bit 1), the values of the 3rd, 4th, and 7th bits of the binary number are 1, so the corresponding electronic switches should be set to the on state; while the values of the 1st, 2nd, 5th, and 6th bits are 0, and the corresponding electronic switches should be set to the off state. The parallel capacitances corresponding to the electronic switches set to the on state are 10pF, 20pF, and 160pF, respectively. The current capacitance of the regulation branch is 190pF, which is 59.8% of the total capacitance of 317.5pF, which is basically consistent with the K value (60%) preset by the RECIPE parameter.
[0075] S5. Set other RECIPE parameters such as airflow, pressure, total RF power, time, temperature, etc.
[0076] Repeat steps S2-S5 until all STEP settings are completed.
[0077] This application not only supports independent configuration of impedance parameters by workstation, but also enables differentiated impedance settings at the process step (STEP) level. Specifically, binary encoding is used to map the state value of the electronic switch to the switch state of the parallel capacitor array, thereby achieving a smooth impedance adjustment effect.
[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.
Claims
1. A radio frequency power distribution and adjustment device, characterized in that: It includes multiple parallel adjustment branches arranged between the radio frequency power supply RF and the ground GND. Each adjustment branch includes a branch filter, a branch load arranged in parallel, and a branch impedance adjustment mechanism. The branch impedance adjustment mechanism includes an inductor and a ceramic capacitor array arranged in parallel. A corresponding electronic switch is set in front of each ceramic capacitor.
2. The RF power distribution and adjustment device according to claim 1, characterized in that: The electronic switch is connected to the control system of the PECVD equipment.
3. The RF power distribution and adjustment device according to claim 1, characterized in that: The ceramic capacitors include ceramic capacitors C1, C2, C3, ..., and Cm, and the electronic switches include electronic switches M1, M2, M3, ..., and Mm. When the electronic switch M1 is turned on and the electronic switches M2, M3, ..., and Mm are all turned off, the adjusted impedance is jωL+1 / jωC1; when the electronic switches M1 and M2 are turned on and the electronic switches M3, ..., and Mm are all turned off, the adjusted impedance is jωL+1 / jω(C1+C2). Similarly, when the electronic switches M1, M2, M3, ..., and Mm are all turned on, the adjusted impedance is 4. The radio frequency power distribution and adjustment device according to claim 3, characterized in that: The capacitance values of the ceramic capacitors C1, C2, C3, ..., and Cm are distributed in binary multiples, that is, C2 = 2C1, C3 = 2C2 ... C m =2C m-1 .
5. The radio frequency power distribution and adjustment device according to claim 1, characterized in that: The total capacitance value of the ceramic capacitors C1, C2, C3, ..., and Cm connected in parallel is: The electronic switch M1 is turned on, and the electronic switches M2, M3, ..., M m When disconnected: the total parallel capacitance value is C1; The electronic switch M2 is turned on, and the electronic switches M1, M3, ..., M m When disconnected: the total parallel capacitance is 2C1; Electronic switches M1 and M2 are turned on, and electronic switches M3, ...M m When disconnected: the total parallel capacitance is 3C1; The electronic switch M3 is turned on, and the electronic switches M1, M2, M4, ... m When disconnected: the total parallel capacitance is 4C1; …… Electronic switches M1, M2, M3, ...M m When conducting: the total parallel capacitance is (2 m -1)C1.
6. The radio frequency power distribution and adjustment device according to claim 5, characterized in that: The proportional relationship between the capacitance adjustment step and the maximum total parallel capacitance value is shown in the following formula: Where d is the capacitance adjustment step size. The smaller the step size, the higher the adjustment accuracy of the RF power distribution.
7. The radio frequency power distribution and adjustment device according to claim 1, characterized in that: The electronic switch is a MOSFET device, an IGBT or a vacuum relay.
8. An application of the radio frequency power distribution adjustment device according to any one of claims 1 to 7 in PECVD thin film deposition, characterized in that: Specifically include: Get the deposition process menu RECIPE and read the Ki value of each adjustment branch of the current STEP; Based on each Ki value, the corresponding electronic switch state value M is obtained; The electronic switch state value M is converted into binary form. The binary bit corresponds to the on-off state of the electronic switches M1, M2, M3, ..., Mm. If the value of a certain bit in the binary is 1, the corresponding electronic switch is set to the on state. If the value of the bit is 0, the corresponding electronic switch is set to the off state.
9. The application of the RF power distribution and adjustment device in PECVD thin film deposition according to claim 8, characterized in that: The method for obtaining the corresponding electronic switch state value M based on each Ki value is: where K i is the K value corresponding to the i-th adjustment branch in the deposition process menu RECIPE, C sum is the total parallel capacitance value of the regulating branch, and C1 is the minimum capacitance value.
10. Application of the RF power distribution and adjustment device according to claim 8 in PECVD thin film deposition, characterized in that: By setting the Ki value of each regulating branch or by setting the Ki value of each step, the uniformity of the deposition film can be optimized.