TWI451089B - Optical detection method and optical mems detector, and method for making mems detector - Google Patents

Description

Optical detection method, optical micro-electromechanical detector, and preparation method thereof

The invention relates to an optical detection method and a MEMS (Micro-Electro-Mechanical System) detector, in particular to a micro-electromechanical component that uses optical detection instead of capacitive detection, which is available, for example. For the production of accelerometers. The invention also relates to a method of fabricating the optical MEMS detector.

The current method of detecting displacement by a microelectromechanical accelerometer is usually capacitive. As shown in FIG. 1, the capacitive accelerometer includes a fixed electrode 1 and a movable electrode 2. When the movable electrode 2 moves, the capacitance between the two changes, and the acceleration can be detected. The structure shown in Figure 1 can be a top view (measuring a change in capacitance in the horizontal direction) or a cross-sectional view (measuring a change in capacitance in the vertical direction).

Another prior art is shown in Figure 2, which is an optical accelerometer that uses Fabry-Perot resonance to reflect light in the two mirrors 3, 4 and only light of a specific wavelength penetrates into the optoelectronics. A photoelectric effect is produced in the photo diode 5. The structure of the optical accelerometer is very complicated. In order to achieve Fabry-Perot resonance, the distance between the two mirrors 3 and 4 must be accurate. Therefore, an adjustment mechanism must be provided, and half of the surface of the film 6 and the substrate 7 must be fabricated. The semi-reflective mirrors 3, 4 are complicated and costly.

Therefore, the present invention provides an optical MEMS detector to improve Pre-technical issues.

A first object of the present invention is to provide an optical MEMS detector.

A second object of the present invention is to provide a method of fabricating an optical MEMS detector.

A third object of the present invention is to provide an optical detection method.

To achieve the above and other objects, in one aspect, the present invention provides an optical MEMS detector comprising: a substrate; at least one photodiode in a region of the substrate; positioned above the substrate a partition wall surrounding the photodiode region; and at least one moving member above the photodiode, the at least one movable member having an opening for allowing light to pass through to the photodiode, wherein the at least one moving member As it moves, the amount of light that passes through the opening to the photodiode is changed.

The optical micro-electromechanical detector may further include a light source and an optical element to guide light into the opening of the at least one moving member.

In another aspect, the present invention provides a method for fabricating an optical MEMS detector comprising the steps of: providing a substrate; forming at least one photodiode in a region of the substrate; forming a spacer above the substrate, Surrounding the photodiode region; and forming at least one moving member above the photodiode, the at least one moving member having an opening to allow light to pass through to the photodiode, wherein when the at least one moving member moves, The amount of light that passes through the opening to the photodiode is changed.

In the above method, a light transmissive layer may be disposed on the substrate, and in the light transmissive layer The optical channel can be set. The light transmissive layer may be etched by using a timing method, or the lower first light transmissive layer, the etch stop layer, and the upper second light transmissive layer may be arranged in the light transmissive layer, and the second light transmissive layer is first etched to stop at the etch stop layer, and then The etch stop layer is etched, both of which can be used to control the thickness of the light transmissive layer. The material of the etch stop layer may comprise amorphous silicon or tantalum nitride.

In another aspect, the present invention provides an optical detection method comprising the steps of: providing a detector comprising at least one photodiode and at least one movable member positioned above the photodiode, The at least one moving member has an opening for allowing light to pass through to the photodiode; when the at least one moving member moves, changing the amount of light that passes through the opening to reach the photodiode; and receiving according to the photodiode The change in the amount of light determines whether the detector moves and the amount of movement.

In the above optical detection method, the horizontal or vertical movement of the movable member may cause a change in the amount of light received by the photodiode.

The purpose, technical content, features and effects achieved by the present invention will be more readily understood by the detailed description of the embodiments.

The illustrations in the present invention are intended to illustrate the process steps and the relationship between the layers, and the shapes, thicknesses, and widths are not drawn to scale.

Referring to Figures 3-5, an optical MEMS detector and detection method of the present invention will be described. The optical micro-electromechanical detector of the present invention is provided with a photodiode 12 on the substrate 11, and a moving member 22 is disposed above the movable member 22 It can be any shape structure, and can be singular, plural, or plural unconnected structures, and only needs to have an opening 23 between the moving element itself or the plurality of moving parts, which can allow light to pass through to the photodiode 12, When the moving member 22 moves, a part of the light above the photodiode 12 can be shielded, and the amount of light that passes through the opening 23 to reach the photodiode 12 can be changed.

When the detector moves, the horizontal or vertical movement of the movable member 22 causes a change in the sensitization of the photodiode 12. Referring to FIG. 4, when the moving member 22 moves horizontally, it will increase the area of the shielding photodiode 12 and reduce the photosensitive amount of the photodiode 12; see also FIG. 5, when the moving member 22 moves vertically and approaches the photoelectric In the case of the diode 12, the amount of light of the photodiode 12 is reduced, and when the movable member 22 is vertically moved away from the photodiode 12, the amount of light of the photodiode 12 is increased. Based on the amount of light received by the photodiode 12, it is possible to determine whether the detector is moving and its amount of movement.

3-5 shows a structure of a single pixel. In the optical MEMS detector of the present invention, a plurality of pixels may be arranged to form an array, wherein each pixel is electrically connected to each other by the isolation region 13 It is isolated and separated by a partition wall 21 to block unnecessary light. In another arrangement, the partition wall 21 may not be provided for each pixel, but a plurality of pixels may be combined into one unit, and the units are separated from each other by the partition wall 21. The size of each pixel may be the same or different. In the arrangement, for example, a pixel of a smaller area may be used as a photosensitive unit around a larger area of the pixel, or a larger area of the pixel may be disposed in the center of the entire array, and a smaller area of the pixel. Placed around the array, and so on. The space 14 between the movable member 22 and the photodiode 12 can be matched with the requirements of photographic and substrate protection, and an appropriate material or optical path is provided (described in detail later). Further, an electrical element such as a transistor or the like (not shown) may be disposed beside the photodiode 12. The optical MEMS detector and optical detection method of the present invention can be used, for example, as an accelerometer for detecting acceleration, and determining the three-dimensional movement of the detector based on the sensitization change in the overall pixel array.

The method of manufacturing the optical MEMS detector of the present invention will be described below.

First, the first embodiment of the manufacturing method will be explained, see Fig. 6-7. As shown in the figure, a substrate 11 is provided first, for example, a germanium substrate; in the substrate 11, an isolation region 13 is formed, for example, by shallow trench isolation (STI); and the isolation region 13 is separated. The photodiode 12 is formed in the region, for example, by ion implantation. Next, a pattern of a plurality of opaque material vine layers is deposited and defined over the substrate to form a partition wall 21, wherein the pattern is defined by lithography and etching. In a preferred embodiment of the present invention, in order to be compatible with the CMOS process, the material layer 21a may use a gate material constituting a CMOS transistor, such as polysilicon; the material layer 21b may be used to form an interconnect. The material of the wire metal layer is, for example, aluminum or copper; the material layer 21c may use a material constituting the interconnect channel layer, such as tungsten or copper. While the partition wall 21 is formed, the movable member 22 and the light transmitting layer 31 are also formed, and the material of the light transmitting layer 31 is, for example, an oxide.

In order to achieve a better optical effect, the thickness of the light transmissive layer 31 above the photodiode 12 is preferably controlled. In the present embodiment, as shown in FIG. 7, the light-transmitting layer 31 is etched in a time mode so that the light-transmitting layer 31 of an appropriate thickness is left above the substrate 11. When the material of the light transmissive layer 31 is an oxide, the etching method may be, for example, hydrogen fluoride vapor etching. Through the above process, the optical MEMS detector of the embodiment is completed.

For another embodiment of the present invention, please refer to FIG. 8-10. Parts of this embodiment that are similar to the previous embodiment are not described. As shown in FIG. 8, a first light transmissive layer 31 is deposited over the substrate 11, the material of which is, for example, an oxide; an etch stop layer 32 is deposited over the first light transmissive layer 31; and then deposited over the etch stop layer 32. The second light transmissive layer 33 is made of, for example, an oxide. The material selected for the etch stop layer 32 requires a higher etch selectivity for the second light transmissive layer, such as amorphous silicon or tantalum nitride. Next, as shown in FIG. 9, the second light transmissive layer 33 is etched by, for example, hydrogen fluoride vapor etching and staying over the etch stop layer 32. Referring again to FIG. 10, the etch stop layer 32 is etched away to expose the underlying first light transmissive layer 31, i.e., the optical MEMS detector of the present embodiment is completed.

In one embodiment of the present invention, the illumination source 41 may be disposed in or external to the integral optical micro-electromechanical detector, and the illumination source may be, for example, a light-emitting diode to enable the optical micro-electromechanical detector Receives stable light. In addition, the optical micro-electromechanical detector can be provided with an optical element 50 for guiding light, for example, a mirror 51 and a lens 52 can be included to guide the light into the opening 23.

In some applications, it may be desirable to remove the first light transmissive layer 31 directly above the photodiode 12 to create a light passage to increase the transmittance of light, in which case the photodiode should be retained. The first light transmissive layer 31 above the body 12 side protects an electrical component (such as a transistor, not shown) in the pixel. The process of the first embodiment is taken as an example. As shown in FIG. 12-13, after the photoresist 60 is deposited, the first light-transmissive layer 31 is etched by lithography and etching, and then fully etched to form. Light channel 34. Please note that although the illustrated light tunnel 34 completely penetrates the first light transmissive layer 31, the present invention is not limited thereto, and the bottom of the light tunnel 34 may not penetrate to the photodiode 12. In the second embodiment, if a light channel is to be formed, a photoresist may be deposited after the 10th image, and the first light-transmissive layer 31 may be etched by lithography or etching, and an optical channel may be formed, which is not shown.

Compared with the prior art, in the capacitive MEMS detector of Fig. 1, since the two electrodes 1, 2 are close to each other, a problem of stiction occurs in the process and in actual use. In the present invention, since the distance between the movable member 22 and the photodiode 12 is relatively long, this problem is not caused in the process and in actual use. In addition, the structure of the present invention can detect movement in three dimensions, while the capacitive structure of Figure 1 can only detect movement in two dimensions. Compared with the optical MEMS detector of FIG. 2, the present invention does not need to consider the Fabry-Perot resonance, and does not need to precisely control the distance between the two mirrors 3, 4, so the process is much simpler.

The present invention has been described with reference to the preferred embodiments thereof, and the present invention is not intended to limit the scope of the present invention. For those skilled in the art, various equivalent changes can be immediately considered within the spirit of the invention. For example, the materials, the number of layers, and the like in the above embodiments are all exemplified, and there are other possibilities for equivalent changes. For example, the structure of the movable member 22 is not limited to the embodiments. For example, in the pixel region, an electrical component can be fabricated using a junction transistor, so that the first light transmissive layer 31 can be completely removed without the polysilicon gate, and the isolation wall The material layer 21a is also not required in the 21st. In view of the above, it is to be understood that the changes and modifications of the present invention are intended to be included within the scope of the present invention.

1,2‧‧‧electrode

3,4‧‧‧Mirror

5‧‧‧Photoelectric diode

6‧‧‧film

7‧‧‧Substrate

11‧‧‧Substrate

12‧‧‧Photoelectric diode

13‧‧‧Isolated area

21‧‧‧ partition wall

21a‧‧‧Fused layer

21b‧‧‧metal layer

21c‧‧‧ channel layer

22‧‧‧Transaction

23‧‧‧Opening

31‧‧‧First light transmission layer

32‧‧‧etch stop layer

33‧‧‧Second light transmission layer

34‧‧‧Light channel

41‧‧‧Light source

50‧‧‧Optical components

51‧‧‧Mirror

52‧‧‧ lens

60‧‧‧Light resistance

Figure 1 illustrates prior art capacitive sensing.

Figure 2 illustrates optical detection in prior art U.S. Patent No. 6,673,718.

Figure 3 illustrates the structure of the present invention.

4 to 5 illustrate the detection method of the present invention.

6 to 7 show a first embodiment of the present invention.

8 to 10 show a second embodiment of the present invention.

Figure 11 shows a third embodiment of the present invention.

12 to 13 show a fourth embodiment of the present invention

11. . . Substrate

12. . . Photodiode

13. . . quarantine area

twenty one. . . Partition wall

twenty two. . . Moving parts

twenty three. . . Opening

31. . . First light transmission layer

32. . . Etch stop layer

41. . . Light source

50. . . Optical element

51. . . Mirror

52. . . lens

Claims (19)

An optical MEMS detector comprising: a substrate; at least one photodiode in a region of the substrate; a spacer wall positioned above the substrate surrounding the photodiode region; At least one moving member above the photodiode, the at least one moving member having an opening to allow light to pass through to the photodiode, wherein the at least one moving member changes in any dimension in the three-dimensional direction The aperture reaches the amount of light of the photodiode, wherein the spacer wall comprises a structural layer of the same level as the movable member. The optical MEMS detector of claim 1, further comprising a light transmissive layer overlying the substrate. The optical MEMS detector of claim 1, further comprising a light transmissive layer overlying the substrate, wherein the light transmissive layer has an optical channel directly above the photodiode. The optical MEMS detector of claim 1, 2, or 3, further comprising an optical component for guiding light into the opening of the at least one moving member. The optical MEMS detector of claim 1, 2, or 3, further comprising a illuminating source for receiving the stable ray of the optical MEMS detector. An optical MEMS detector as described in claim 1 of the patent application, the package thereof A plurality of photodiode regions are separated by a plurality of partition walls. The optical micro-electromechanical detector according to claim 6, wherein at least one of the plurality of partition walls surrounds the plurality of photodiode regions. An optical micro-electromechanical detector as described in claim 1 is for detecting an accelerometer. An optical MEMS detector comprising: a substrate; at least one photodiode in a region of the substrate; a spacer wall positioned above the substrate surrounding the photodiode region; At least one moving member above the photodiode, the at least one moving member having an opening for allowing light to pass through to the photodiode, wherein when the at least one moving member moves, changing through the opening to reach the photodiode The amount of light, wherein the partition wall comprises a structural layer of the same level as the movable member, and wherein the plurality of photodiode regions are not completely identical in size. An optical micro-electromechanical detector manufacturing method comprising the steps of: providing a substrate; forming at least one photodiode in a region of the substrate; forming a partition wall over the substrate to surround the photodiode region; Forming at least one moving member above the photodiode, the at least one moving member having an opening for allowing light to pass through to the photodiode, wherein at least When a moving member moves in any dimension in the three-dimensional direction, the amount of light passing through the opening to the photodiode is changed, and the moving member is simultaneously formed when the partition wall is formed. The method for fabricating an optical micro-electromechanical detector according to claim 10, wherein the step of forming the partition wall comprises: depositing and defining a plurality of layers of the opaque material to form a partition wall, wherein the partition wall is also formed. The at least one moving member. The method for fabricating an optical MEMS detector according to claim 10, further comprising: depositing a first light transmissive layer over the substrate; and etching the first light transmissive layer in a timed manner to make the substrate A portion of the first light transmissive layer is retained. The method for fabricating an optical MEMS detector according to claim 10, further comprising: depositing a first light transmissive layer over the substrate; depositing an etch stop layer over the first light transmissive layer; Depositing a second light transmissive layer over the layer; etching the second light transmissive layer; and etching the etch stop layer. The optical microelectromechanical detector according to claim 13, wherein the material of the etch stop layer comprises amorphous silicon or tantalum nitride. The method for fabricating an optical MEMS detector according to claim 12, further comprising etching an optical channel in the first light transmissive layer. An optical detection method includes the following steps: providing a detector including at least one photodiode and at least one moving member positioned above the photodiode, the at least one moving member having an opening Allowing light to pass through to the photodiode; changing the amount of light that passes through the opening to the photodiode when the at least one moving member moves in any dimension in three dimensions; and changing the amount of light received by the photodiode , to determine whether the detector is moving and its amount of movement. The optical detection method of claim 16, further comprising: providing a light source to enable the detector to receive stable light. The optical detection method of claim 16, further comprising: moving the at least one moving member vertically, and reducing the amount of light received by the photodiode when the vertical movement is close to the photodiode; When it moves vertically away from the photodiode, the amount of light received by the photodiode is increased. The optical detection method of claim 16, further comprising: moving the at least one moving member horizontally, and reducing the photodiode when the horizontal movement thereof blocks a large area of the photodiode Receive light amount.