Method for manufacturing a microelectromechanical component and microelectromechanical component
The method of filling trenches with silicon oxide and polysilicon addresses incomplete filling issues, enhancing the stability of microelectromechanical components against mechanical stress by ensuring complete trench sealing and structural integrity.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- ROBERT BOSCH GMBH
- Filing Date
- 2025-12-03
- Publication Date
- 2026-07-23
AI Technical Summary
Existing methods for manufacturing microelectromechanical components often result in incomplete filling of trenches with dielectric fluid, leading to mechanical weak points that can cause component failure under mechanical stress.
A method involving partial filling of trenches with silicon oxide and complete filling with polysilicon using low-pressure chemical vapor deposition, ensuring no internal voids, and designing trenches to accommodate high bending stresses.
Results in a more stable microelectromechanical component capable of withstanding mechanical forces by eliminating internal voids and enhancing structural integrity.
Smart Images
Figure EP2025085210_23072026_PF_FP_ABST
Abstract
Description
[0001] R.416728
[0002] - 1 -
[0003] Description
[0004] Method for manufacturing a microelectromechanical component and microelectromechanical component
[0005] The invention relates to a method for manufacturing a microelectromechanical component. The invention also relates to a microelectromechanical component.
[0006] State of the art
[0007] It is known to fill a trench in a component of a microelectromechanical device with a dielectric fluid. However, during the process, this trench often cannot be completely filled with the dielectric fluid; instead, a narrow gap remains from approximately halfway up the trench to just below the inlet at the top. This gap thus represents a mechanical weak point in the component, which can lead to component failure under appropriate mechanical stress.
[0008] Based on this, it is an object of the present invention to develop a method for manufacturing a microelectromechanical component which enables a more stable microelectromechanical component in the face of occurring mechanical forces.
[0009] Disclosure of the invention
[0010] To solve the problem, a method for manufacturing a microelectromechanical component according to claim 1 is proposed. Furthermore, a microelectromechanical component according to claim 14 is proposed.
[0011] In the method for manufacturing a microelectromechanical component, a first section of a, in particular plate-shaped, first component of the microelectromechanical component is first separated from a second section R.416728
[0012] - 2 -
[0013] The first component is separated, particularly locally, by means of a first trench. Subsequently, the first trench is partially filled with a dielectric material, specifically silicon oxide. The first trench is then completely filled with polysilicon, primarily using low-pressure chemical vapor deposition. This filling process offers the advantage of completely filling the first trench without any internal voids. This results in a more stable first component of the microelectromechanical device against mechanical forces.
[0014] Preferably, the first trench is created at a location on the first component where a high, and in particular a very high, bending stress occurs during the application of the microelectromechanical component. At such a location on the first component, it is therefore very important to have a point that is stable under high bending stresses.
[0015] Preferably, the first component, especially a single piece, is made of polysilicon or monocrystalline silicon. Trenches can be produced very effectively in such a material.
[0016] Preferably, in further process steps, at least one first comb electrode, in particular a first drive electrode, is produced in a first region below or above the first section of the first component. Furthermore, in a second region below or above the second section of the first component, a second comb electrode, in particular a first measuring electrode, and also, in particular adjacent to the second region, a suspension of the first component, together with the first and second comb electrodes, are produced. The first comb electrode and the second comb electrode are produced, in particular, on the same side relative to the first component. Both the first comb electrode and the second comb electrode, as well as the suspension, are made, in particular, of polysilicon or single-crystal silicon.In particular, the first comb electrode, the second comb electrode, the suspension, and the first component of the microelectromechanical component are formed in one piece. R.416728.
[0017] - 3 -
[0018] Preferably, at least one second trench is created in the first section of the first component, particularly simultaneously with the separation of the first section from the second section. Alternatively or additionally, at least one third trench is created in the second section of the first component, particularly simultaneously with the separation of the first section from the second section. Furthermore, the second and / or third trench is completely filled with the dielectric, particularly simultaneously with the filling of the first trench. Complete filling in this context refers specifically to the complete sealing of an entrance side of the second trench with the dielectric. However, cavities within the second and / or third trench may still be present.At the locations of the second and / or third trench, such cavities are harmless, particularly with regard to the presence of bending forces. Preferably, at least two adjacent second trenches are created such that a first functional structure is formed within the first component, located between the second trenches. The first functional structure serves to create an electrical and / or thermal connection between the first component and a further second component of the microelectromechanical device. Alternatively or additionally, at least two adjacent third trenches are created such that a second functional structure is formed within the first component, located between the third trenches.The second functional structure also serves to create an electrical and / or thermal connection between the first component and the second component of the microelectromechanical device. Preferably, the first trench is formed with a first diameter, particularly a maximum diameter, that is greater than the sum of the second diameter, particularly a maximum diameter, of the second or third trench and the dielectric filling thickness. With such a thickness of the first trench, complete filling of the first trench is made possible, while the inlet side of the second and / or third trench is already closed by the dielectric alone. In this context, it is further provided that the dielectric filling thickness is greater than half the second diameter of the second or third trench. R.416728.
[0019] - 4 -
[0020] Preferably, when partially filling the first trench with the dielectric, the side surfaces and one bottom surface of the trench, particularly the downward-tapering section, are filled first. Then, when completely filling the first trench with polysilicon, one entrance side of the trench is completely sealed with the polysilicon. In this context, "completely filling the first trench" means filling it without any remaining void within the trench.
[0021] Preferably, the first section of the first component is contacted such that a first potential, in particular an electrical one, is present. Furthermore, the second section is contacted such that a second potential, in particular an electrical one, is present. If different electrical potentials are present within the first component, separation, in particular circumferential separation, of the two sections by means of a first trench as an isolation trench is necessary.
[0022] Preferably, in a further process step, excess polysilicon is removed from a surface of the first component, particularly one located towards the inlet side of the first trench. Specifically, the excess polysilicon is removed by a polishing process, an etching process, or wet chemical treatment.
[0023] Preferably, the first trench is created in such a way that it extends to an etch stop layer, in particular made of silicon dioxide, on an underside of the first component.
[0024] Preferably, in further process steps, at least one micromirror is produced as a microelectromechanical component. Here, the first component particularly fulfills a holding function for the first comb electrode and the second comb electrode of the micromirror. The micromirror is particularly part of a micromirror array. R.416728
[0025] - 5 -
[0026] Another object of the present invention is a microelectromechanical component, in particular manufactured according to the method described above. The microelectromechanical component comprises a first component, in particular a plate-shaped one. A first section of the first component is separated from a second section of the first component by means of a first trench. The first trench is completely filled with a dielectric, in particular with silicon oxide, and with polysilicon. The complete filling of the first trench without a cavity within the first trench results in a first component that is stable against external mechanical loads, in particular bending forces. Preferably, the microelectromechanical component is designed as a micromirror. The micromirror has at least one first comb electrode and one second comb electrode.In this context, the first component is configured to hold the first comb electrode and the second comb electrode. The first comb electrode is specifically configured as a first drive electrode of the micromirror and is furthermore specifically made of polysilicon or single-crystal silicon. The second comb electrode is specifically configured as a first measuring electrode and is further specifically made of polysilicon or single-crystal silicon. The micromirror is in particular part of a micromirror array.
[0027] Description of the drawings
[0028] Figures 1a to 1e schematically show process steps for manufacturing a microelectromechanical component.
[0029] Figure 2 schematically shows a part of a microelectromechanical component.
[0030] Description of the exemplary implementations
[0031] Figure 1a schematically shows how, in a first process step 10 of an embodiment of a method for manufacturing a microelectromechanical component, a first section 11a of a plate-shaped, first component 1 of the microelectromechanical component was separated from a second section 11b of the first component 1 by means of a first trench 15. Further R.416728
[0032] - 6 -
[0033] In this embodiment, two second trenches 7a and 7b were simultaneously created in the first section 11a of the first component 1 to separate the first section 11a from the second section 11b. The two second trenches 7a and 7b are arranged circumferentially and adjacent to each other and are created such that a first functional structure 16a is formed within the first component 1 between the second trenches 7a and 7b. The first functional structure 16a serves to create an electrical and / or thermal connection between the first component 1 and a further second component of the microelectromechanical device, which is not shown here for the sake of simplicity. Furthermore, in this embodiment of the method, two third trenches 8a and 8b were simultaneously created to separate the first section 11a from the second section 11b.The two third trenches 8a and 8b are arranged circumferentially and adjacent to each other and are generated in such a way that a second functional structure 16b is formed within the first component 1, located between the third trenches 8a and 8b. The second functional structure 16b also serves to create an electrical and / or thermal connection between the first component 1 and a further second component of the microelectromechanical device, which is not shown here for the sake of simplicity.
[0034] The first component 1 is formed in one piece from polysilicon. The first trench 15 extends to an etch stop layer 3 made of silicon oxide on the underside of the first component 1.
[0035] Figure 1b schematically shows a further process step 20 in which the first trench 15 is partially filled with silicon oxide as a dielectric 13. Simultaneously with the filling of the first trench 15 with the dielectric 13, the second trenches 7a and 7b, as well as the third trenches 8a and 8b, are completely filled with the dielectric 13. Complete filling here means that one entrance side of the second trenches 7a and 7b, as well as the third trenches 8a and 8b, is completely sealed with the dielectric 13. However, a small cavity 21 remains within the second trenches 7a and 7b and the third trenches 8a and 8b. During the partial filling of the first trench 15 with the dielectric 13, the side surfaces 18 and a bottom surface 17 of the trench 15 are initially sealed with the dielectric 13.
[0036] - 7 -
[0037] The first trench 15, which converges at the bottom, is filled with the dielectric fluid 13. To prevent the dielectric fluid 13 from completely filling the first trench 15, it is wider than the second trenches 7a and 7b and the third trenches 8a and 8b. The first trench 15 has a first diameter 6 (in particular, its maximum diameter) that is greater than the sum of the second diameter 5 (in particular, its maximum diameter) of the second trenches 7a and 7b or the third trench 8a and 8b and a filling thickness 12a of the dielectric fluid 13. To ensure that the second and third trenches are completely sealed, the filling thickness 12a of the dielectric fluid 13 is greater than half the second diameter 5 of the second trenches 7a and 7b or the third trench 8a and 8b.
[0038] Figure 1c schematically shows a further process step 30 in which the first trench 15 is completely, and in particular partially, sealed by means of polysilicon 19. Specifically, an entrance side of the first trench 15 is completely sealed by means of polysilicon 19 using low-pressure chemical vapor deposition. No cavity remains within the first trench 15.
[0039] Figure 1d schematically shows a further process step 40 in which excess polysilicon 19 was removed from a surface 23 of the first component located towards the entrance side of the first trench 15. For this purpose, a polishing process or an etching process was used in particular.
[0040] Figure 1 e schematically shows a further process step 50 in which silicon oxide as dielectric 13 was partially removed and thus structured on the surface 23 arranged towards the entrance side of the first trench 15.
[0041] In further process steps, not shown for the sake of simplicity, at least one micromirror, in particular one micromirror array, is produced as a microelectromechanical component. The first component fulfills, in particular, a holding function for the first comb electrode and the second comb electrode. R.416728
[0042] - 8 -
[0043] Figure 2 schematically shows a microelectromechanical component 60 in the form of a micromirror. For simplicity, only a portion of the microelectromechanical component 60 is shown. The microelectromechanical component was partially fabricated, in particular according to the previously described method. The microelectromechanical component 60 has the plate-shaped first component 1. The first section 11a of the first component 1 is separated from the second section 11b of the first component 1 by the first trench 15. The first trench 15 is completely filled with the dielectric 13 and with polysilicon 19.
[0044] In a first region below the first section 11a of the first component 1, a first comb electrode 61a is additionally arranged as a first drive electrode. This is also made of polysilicon. In a second region below the second section 11b of the first component 1, a second comb electrode 61b is arranged on the same side of the first comb electrode 61a below the first component 1 as a first measuring electrode. This is also made of polysilicon. The first component 1 is configured to hold the first comb electrode 61a and the second comb electrode 61b. Furthermore, a suspension 62 of the first component 1, together with the first comb electrode 61a and the second comb electrode 61b, is arranged adjacent to the second comb electrode 61b.
[0045] The first section 11a of the first component 1 was contacted such that a first potential, in particular an electrical one, is present, and the second section 11b was contacted such that a second potential, in particular an electrical one, is present. In this context, the first component 1 also serves for rewiring to enable separation of the drive potential from the measuring potential of the micromirror.
[0046] The first trench 15 was created at a point in the first component 1 where a high, in particular a very high, bending stress occurs when using the microelectromechanical component 60.
Claims
R.416728 - 9 - Claims 1. Method for manufacturing a microelectromechanical component (60), wherein the method comprises the following process steps: - Separating (10) a first section (11a) of a, in particular plate-shaped, first component (1) of the microelectromechanical component (60) from a second section (11b) of the first component (1) by means of a first trench (15), and - partial filling (20) of the first trench (15) by means of a dielectric (13), in particular by means of silicon oxide, and - Complete, especially remaining, filling (30), especially by means of Low Pressure Chemical Vapor Deposition, of the first trench (15) using polysilicon (19).
2. Method for manufacturing a microelectromechanical component (60) according to claim 1, characterized in that the first trench (15) is produced at a location of the first component (1) where a high, in particular a very high, bending stress occurs during the application of the microelectromechanical component (60).
3. Method according to one of claims 1 or 2, characterized in that the first component (1), in particular in one piece, is formed from polysilicon (19) or single-crystal silicon.
4. Method according to one of claims 1 to 3, characterized in that in further method steps, in a first region below or above the first section (11a) of the first component (1) at least one first comb electrode (61a), in particular a first drive electrode, furthermore in particular made of polysilicon (19), and in a second region below or above the second section (11b) of the first component (1), in particular on the same side of the first comb electrode (61a), a second comb electrode (61b), in particular a first measuring electrode, furthermore in particular made of polysilicon (19), and furthermore, in particular adjacent to the second region, a suspension (62) of the R.416728 - 10 - first component (1), together with the first (61a) and second comb electrode (61b) is produced.
5. Method according to any one of claims 1 to 4, characterized in that at least one second trench (7a, 7b) and / or at least one third trench (8a, 8b) is produced in the first section (11a) of the first component (1), in particular simultaneously with separating the first section (11a) from the second section (11b), and the second (7a, 7b) and / or third trench (8a, 8b) is completely filled with the dielectric (13), in particular simultaneously with filling the first trench (15) with the dielectric (13), in particular an inlet side of the second (7a, 7b) or third trench (8a, 8b) is completely closed with the dielectric (13).
6. Method according to claim 5, characterized in that at least two adjacently arranged second (7a, 7b) and / or third trenches (8a, 8b) are generated such that a first (16a) and / or second functional structure (16b) arranged between the second (7a, 7b) and / or third trenches (8a, 8b) is formed within the first component (1), wherein the first (16a) and / or second functional structure (16b) serves to generate an electrical and / or thermal connection of the first component (1) to a further second component of the microelectromechanical component (60).
7. Method according to one of claims 5 or 6, characterized in that the first trench (15) is produced with a first diameter (6), in particular a maximum diameter, which is greater than the sum of the second diameter (5), in particular a maximum diameter, of the second (7a, 7b) or third trench (8a, 7b) and a backfill thickness (12a) of the dielectric (13). R.416728 - 11 - 8. Method according to claim 7, characterized in that the backfill thickness (12a) of the dielectric (13) is greater than half of the second diameter (5) of the second (7a, 7b) or third trench (8a, 8b).
9. Method according to one of claims 1 to 8, characterized in that when partially filling (20) the first trench (15) by means of the dielectric (13), the side surfaces (18) and a bottom surface (17) of the first trench (15), in particular the downwardly converging one, are filled first, and when completely, in particular the remaining, filling (30) of the first trench (15) by means of polysilicon (19) an entrance side of the first trench (15) is completely closed by means of polysilicon (19).
10. Method according to one of claims 1 to 9, characterized in that the first section (11a) of the first component (1) is contacted such that a first, in particular electrical, potential is present, and the second section (11b) is contacted such that a second, in particular electrical, potential is present.
11. Method according to one of claims 1 to 10, characterized in that in a further process step excess polysilicon (19) is removed (40) from a surface (23) of the first component (1), in particular arranged in the direction of the inlet side of the first trench (15), in particular by means of a polishing process or an etching process.
12. Method according to one of claims 1 to 11, characterized in that the first trench (15) extends to an etch stop layer (3), in particular made of silicon oxide (13), on an underside of the first component (1).
13. Method according to one of claims 1 to 12, characterized in that in further method steps at least one micromirror, in particular one micromirror array, is produced as a microelectromechanical component (60), wherein in particular the first component (1) is a holding radio-R.416728 - 12 - tion for the first comb electrode (61a) and the second comb electrode (61b) is fulfilled.
14. Microelectromechanical component (60), in particular manufactured according to a method of claims 1 to 13, wherein the microelectromechanical component (60) has a first component (1), in particular a plate-shaped component, wherein a first section (11a) of the first component (1) is separated from a second section (11b) of the first component (1) by means of a first trench (15), characterized in that the first trench (15) is completely filled with a dielectric (13), in particular with silicon oxide, and with polysilicon (19).
15. Microelectromechanical component (60) according to claim 14, characterized in that the microelectromechanical component (60) is designed as a micromirror, in particular a micromirror array, wherein the micromirror has at least a first comb electrode (61a), in particular a first drive electrode, further in particular made of polysilicon (19), and a second comb electrode (61b), in particular a first measuring electrode, further in particular made of polysilicon (19), wherein the first component (1) is configured to hold the first comb electrode (61a) and the second comb electrode (61b).