MEMS chip and electrical packaging method for MEMS chip
11242243 · 2022-02-08
Assignee
Inventors
Cpc classification
B81B2207/097
PERFORMING OPERATIONS; TRANSPORTING
B81C2203/0109
PERFORMING OPERATIONS; TRANSPORTING
B81B7/007
PERFORMING OPERATIONS; TRANSPORTING
B81B7/04
PERFORMING OPERATIONS; TRANSPORTING
B81B2207/092
PERFORMING OPERATIONS; TRANSPORTING
B81B7/02
PERFORMING OPERATIONS; TRANSPORTING
B81C1/00261
PERFORMING OPERATIONS; TRANSPORTING
B81B2201/042
PERFORMING OPERATIONS; TRANSPORTING
B81C1/00
PERFORMING OPERATIONS; TRANSPORTING
B81C1/00301
PERFORMING OPERATIONS; TRANSPORTING
International classification
B81B7/02
PERFORMING OPERATIONS; TRANSPORTING
B81C1/00
PERFORMING OPERATIONS; TRANSPORTING
Abstract
Embodiments of the application provide a MEMS chip and an electrical packaging method for a MEMS chip. The MEMS chip includes a MEMS device layer, a first isolating layer located under the MEMS device layer, and a first conducting layer located under the first isolating layer. At the first isolating layer, there are a corresponding quantity of first conductive through holes in locations corresponding to conductive structures in a first region and in locations corresponding to electrodes in a second region. At the first conducting layer, there are M electrodes spaced apart from one another, and the M electrodes are respectively connected to M of the first conductive through holes. At the first conducting layer, electrodes in locations corresponding to at least some of the conductive structures in the first region are electrically connected in a one-to-one correspondence to electrodes in locations corresponding to at least some of the electrodes in the second region.
Claims
1. A MEMS chip, comprising a MEMS device layer, a first isolating layer, and a first conducting layer, wherein the MEMS device layer comprises a first region and at least one second region, the first region comprising MEMS movable structures and conductive structures, the conductive structures being distributed among the MEMS movable structures, the second region being an electrode arrangement region, and on an upper surface of the MEMS chip, the conductive structures in the first region being electrically isolated from electrodes in the second region; the first isolating layer is located under the MEMS device layer, and at the first isolating layer, a corresponding quantity of first conductive through holes are disposed in locations corresponding to the conductive structures in the first region and in locations corresponding to the electrodes in the second region; the first conducting layer is located under the first isolating layer, and the first conducting layer comprises M electrodes spaced apart from one another, the M electrodes being respectively connected to M of the first conductive through holes, M being a positive integer, and M being set based on a quantity of the conductive structures in the first region and a quantity of the electrodes in the second region; and at the first conducting layer, electrodes in locations corresponding to at least some of the conductive structures in the first region are electrically connected in a one-to-one correspondence to electrodes in locations corresponding to at least some of the electrodes in the second region.
2. The MEMS chip according to claim 1, wherein M is less than or equal to a sum of the quantity of the conductive structures in the first region and the quantity of the electrodes in the second region.
3. The MEMS chip according to claim 1, further comprising: a second isolating layer located under the first conducting layer and a second conducting layer located under the second isolating layer, wherein second conductive through holes are disposed at the first conducting layer, in a region excluding the M electrodes, the second conductive through holes being connected to the first conductive through holes in a one-to-one correspondence, M being less than a sum of the quantity of the conductive structures in the first region and the quantity of the electrodes in the second region; third conductive through holes are disposed at the second isolating layer, in locations corresponding to the second conductive through holes, the third conductive through holes being connected to the second conductive through holes in a one-to-one correspondence; the second conducting layer comprises Q electrodes that are spaced apart from one another and connected to Q of the third conductive through holes, Q being less than or equal to a quantity of the third conductive through holes; and at the second conducting layer, electrodes in locations corresponding to at least some of the conductive structures in the first region are electrically connected in a one-to-one correspondence to electrodes in locations corresponding to at least some of the electrodes in the second region.
4. The MEMS chip according to claim 3, further comprising: a third isolating layer located under the second conducting layer and a third conducting layer located under the third isolating layer, wherein fourth conductive through holes are disposed at the second conducting layer, in a region excluding the Q electrodes, the fourth conductive through holes being connected to the third conductive through holes in a one-to-one correspondence; fifth conductive through holes are disposed at the third isolating layer, in locations corresponding to the fourth conductive through holes, the fifth conductive through holes being connected to the fourth conductive through holes in a one-to-one correspondence; the third conducting layer comprises K electrodes that are spaced apart from one another and connected to K of the fifth conductive through holes, K being less than or equal to a quantity of the fifth conductive through holes; and at the third conducting layer, electrodes in locations corresponding to at least some of the conductive structures in the first region are electrically connected in a one-to-one correspondence to electrodes in locations corresponding to at least some of the electrodes in the second region.
5. The MEMS chip according to claim 1, further comprising: an N.sup.th isolating layer located under the first conducting layer and an N.sup.th conducting layer located under the N.sup.th isolating layer, wherein N is a positive integer greater than or equal to 2, wherein second conductive through holes are disposed at the first conducting layer, in a region excluding the M electrodes, the second conductive through holes being connected to the first conductive through holes in a one-to-one correspondence, M being less than a sum of the quantity of the conductive structures and the quantity of the electrodes in the second region; (2N−1).sup.th conductive through holes are disposed at the N.sup.th isolating layer, in locations corresponding to (2N−2).sup.th conductive through holes, the (2N−1).sup.th conductive through holes being connected to the (2N−2).sup.th conductive through holes in a one-to-one correspondence; the N.sup.th conducting layer comprises Q electrodes that are spaced apart from one another and connected to Q of the (2N−1).sup.th conductive through holes, Q being less than or equal to a quantity of the (2N−1).sup.th conductive through holes; and at the N.sup.th conducting layer, electrodes in locations corresponding to at least some of the conductive structures in the first region are electrically connected in a one-to-one correspondence to electrodes in locations corresponding to at least some of the electrodes in the second region.
6. The MEMS chip according to claim 5, wherein a sum of quantities of electrodes in locations, at the first conducting layer to the N.sup.th conducting layer, corresponding to the conductive structures in the first region of the MEMS device layer is greater than or equal to the quantity of the conductive structures in the first region, and a sum of quantities of electrodes in locations, at the first conducting layer to the N.sup.th conducting layer, corresponding to the electrodes in the second region is greater than or equal to the quantity of the electrodes in the second region.
7. The MEMS chip according to claim 5, wherein the first conducting layer comprises metal, polycrystalline silicon, or doped silicon, and the N.sup.th conducting layer comprises metal, polycrystalline silicon, or doped silicon.
8. The MEMS chip according to claim 1, wherein the MEMS device layer further comprises an optical input/output region, and a high-reflectivity material is disposed in a location, at the first conducting layer, corresponding to the optical input/output region.
9. The MEMS chip according to claim 1, wherein an isolating apparatus is disposed above the first region, a spacing between the electrodes in the second region is less than a first threshold, and copper pillar bumps are disposed on the conductive structures in the first region and the electrodes in the second region.
10. The MEMS chip according to claim 9, wherein the first threshold is 100 micrometers.
11. The MEMS chip according to claim 1, wherein an electrical switch chip is welded in the second region.
12. The MEMS chip according to claim 1, wherein the conductive structures in the first region of the MEMS device layer comprise drive electrodes.
13. The MEMS chip according to claim 1, wherein the number of the first conductive through holes at the first isolating layer is larger than M.
14. The MEMS chip according to claim 1, wherein, for each of the M of the first conductive through holes at the first isolating layer, an upper surface of the first conductive through hole is connected to one of the conductive structures or one of the electrodes at the MEMS device layer, and a lower surface of the first conductive through hole is connected to one of the electrodes at the first conducting layer.
Description
BRIEF DESCRIPTION OF DRAWINGS
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(11)
DESCRIPTION OF NON-LIMITING EXAMPLE EMBODIMENTS
(12) In the following description, for purpose of explanation, numerous specific details are set forth to provide a thorough understanding of the exemplary embodiments. It will be evident, however, to a person skilled in the art that the exemplary embodiments may be practiced without these specific details.
(13) An optical switch matrix based on a MEMS-SOI chip has a very low loss, and therefore MEMS-SOI chips provide a great advantage when used in an optical switch system. A MEMS-SOI chip includes an optical switch matrix and an optical input (I)/output (0) region. The following briefly describes an example scenario of the optical switch matrix in which the present technology is useful.
(14) A basic function of a communications network is to send signals from different sources to specified destinations.
(15)
(16) The optical switch unit includes upper-layer and lower-layer optical waveguides. The lower-layer optical waveguide forms a crisscross pattern, and is referred to as a bus waveguide, serving as a horizontal or vertical transmission line in the cross-bar architecture. The upper-layer optical waveguide forms a 90-degree turn, and is referred to as a shunt waveguide. An operating principle of the optical switch unit is as follows: when the optical switch unit is powered off, the upper-layer shunt waveguide does not affect the lower-layer bus waveguide in any way, an optical signal is restricted to be transmitted in the bus waveguide, and the optical switch unit is in the “bar state”; when the optical switch unit is powered on, electric potentials of the upper-layer and lower-layer optical waveguides are different, and under influence of an “electrostatic attraction force”, two arms of the upper-layer shunt waveguide are pulled down, and at this time, the optical signal in the lower-layer optical waveguide is coupled to the shunt waveguide, and the optical switch unit is in the “cross state”. Because the two arms of the optical waveguide are movable, the two arms of the optical waveguide are implemented as a MEMS movable mechanical structure.
(17) Compared with other architectures, the cross-bar architecture has a great advantage: a very low loss. Currently, loss performance has become a bottleneck that restricts development of optical switch matrices. Therefore, the advantage of the cross-bar architecture is especially impressive. However, it will be understood that the cross-bar architecture also has a disadvantage, that is, a large quantity of switches. An N×N optical switch matrix has a total of N×N optical switch units. This means that there are a large quantity of drive electrodes in the optical switch matrix, or in other words, there are a large quantity of drive electrodes in the MEMS-SOI chip. For the MEMS-SOI chip, a conventional electrical packaging method for a micromirror MEMS chip is totally unusable. How to implement electrical packaging of the MEMS-SOI chip is a concern of the embodiments of this application. The following describes example technical solutions in detail with reference to the accompanying drawings.
(18)
(19) At the first conducting layer 300, electrodes in locations corresponding to at least some of the conductive structures in the first region are electrically connected in a one-to-one correspondence to electrodes in locations corresponding to at least some of the electrodes in the second region. Electrical connection in a one-to-one correspondence means: at the first conducting layer 300, the electrodes corresponding to the first region are electrically connected in a one-to-one manner to the electrodes corresponding to the second region. Electrical connection may be implemented through electric wiring. At the first conducting layer 300, a region excluding the electrodes is filled with an electrically insulating material. The first conducting layer 300 may be made of metal, polycrystalline silicon, or doped silicon.
(20) In this example embodiment, the first isolating layer 200 is used to implement electrical connections, in a “one-to-one correspondence”, of at least some of the electrodes and the conductive structures at the MEMS device layer 100 to at least some of the electrodes at the first conducting layer 300. In addition, via electric wiring at the first conducting layer 300, at least some of the conductive structures in the first region are connected to the corresponding electrodes in the second region in a “one-to-one correspondence”. In this way, the conductive structures in the first region of the MEMS device layer are led to the second region in a “one-to-one correspondence”. The first region is isolated from the to-be-packaged electrode arrangement region (the second region). An isolating apparatus (for example, a dust cover) may be disposed above the first region to protect the MEMS movable structures from being damaged by an electrical packaging process. After the to-be-packaged electrode arrangement region is isolated from the MEMS movable structures, electrical packaging of the MEMS chip can be compatible with a standard electrical packaging process, thereby helping to reduce product costs. A standard CMOS process may be used for making the metal and electric wiring under the MEMS movable structures.
(21)
(22) According to the MEMS chip provided in this embodiment, the first isolating layer and the first conducting layer are arranged in sequence under the MEMS device layer; at the first isolating layer, there are a corresponding quantity of first conductive through holes in the locations corresponding to the conductive structures in the first region and in the locations corresponding to the electrodes in the second region; and at the first conducting layer, the M electrodes are disposed that are spaced apart from one another and respectively connected to M of the first conductive through holes, so that M of the conductive structures in the first region are electrically connected to M of the electrodes in the second region in a “one-to-one correspondence”. In this way, at the MEMS device layer, the conductive structures in the first region are led in a “one-to-one correspondence” to the second region, thereby implementing electrical packaging of a MEMS-SOI chip. In addition, the first region is isolated from the to-be-packaged electrode arrangement region, and the MEMS movable structures in the first region can be protected by adding an isolating apparatus, so that electrical packaging of the MEMS-SOI chip can be compatible with a standard electrical packaging process, thereby helping to reduce costs.
(23) Based on the foregoing embodiments, when there are quite a lot of conductive structures in the first region, one conducting layer may not be able to lead out all the conductive structures in the first region, and a second isolating layer, a second conducting layer, . . . , an N.sup.th isolating layer, and an N.sup.th conducting layer need to be disposed, where N is a positive integer greater than or equal to 2. Through combination of these isolating layers and conducting layers, all the conductive structures in the first region are finally connected to the electrodes in the second region.
(24) Based on the foregoing embodiments, further, the MEMS chip may further include an N.sup.th isolating layer and an N.sup.th conducting layer that are arranged in alternating sequence under the first conducting layer, where N is a positive integer greater than or equal to 2.
(25) Optionally, a sum of quantities of electrodes in locations, at the first conducting layer to the N.sup.th conducting layer, corresponding to the conductive structures in the first region is greater than or equal to the quantity of the conductive structures in the first region of the MEMS chip, and a sum of quantities of electrodes in locations, at the first conducting layer to the N.sup.th conducting layer, corresponding to the electrodes in the second region is greater than or equal to the quantity of the electrodes in the second region of the MEMS chip. In other words, an idle electrode is allowed to exist.
(26) In this embodiment, a plurality of isolating layers and conducting layers are disposed to implement connection of all the conductive structures in the first region to the electrodes in the second region.
(27)
(28) Further, when there are quite a lot of (for example, more than 10 thousands) conductive structures that need to be led out in the first region of the MEMS chip, even if the conductive structures are led to the multiple electrode arrangement regions, packaging is relatively difficult. There are two example non-limiting implementable manners to resolve this problem. In one implementable manner, based on the foregoing embodiments, an isolating apparatus is disposed above the first region, a spacing between the electrodes in the second region is less than a first threshold, where the first threshold is, for example, 100 micrometers, and copper pillar bumps are disposed on the conductive structures and the electrodes in the second region.
(29) In another implementable manner, based on the foregoing embodiments, an electrical switch chip is welded in the second region. For example, a 1×16 electrical switch chip is welded in the second region, and the 1×16 electrical switch chip is led to a PCB by using conventional electrical packaging technology. In this implementation, a quantity of electrodes that need to be welded to lead the MEMS chip to the PCB can be reduced, because only control signal electrodes of the welded 1×16 electrical switch chip need to be connected to the PCB. In this case, a damaged 1×16 electrical switch chip is easily replaced, and reliability of an electrical connection between the 1×16 electrical switch chip and the MEMS chip is higher.
(30)
(31) S101. Arrange the first isolating layer and the first conducting layer in sequence under the MEMS device layer.
(32) At the first isolating layer, a corresponding quantity of first conductive through holes are disposed in locations corresponding to the conductive structures in the first region and in locations corresponding to the electrodes in the second region. At the first isolating layer, a region excluding (i.e., areas other than) the first conductive through holes is made of an electrically insulating material. At the first conducting layer, there are M electrodes spaced apart from one another, and the M electrodes are respectively connected to M of the first conductive through holes. M is a positive integer, and M is set based on a quantity of the conductive structures and a quantity of the electrodes in the second region. Optionally, the first conducting layer is made of metal, polycrystalline silicon, or doped silicon.
(33) S102. Electrically connect, in a one-to-one correspondence at the first conducting layer, electrodes in locations corresponding to at least some of the conductive structures in the first region to electrodes in locations corresponding to at least some of the electrodes in the second region.
(34) At the first conducting layer, a region excluding the electrodes is filled with an electrically insulating material.
(35) Further, when M is less than a sum of the quantity of the conductive structures and the quantity of the electrodes in the second region, the method further includes the following steps.
(36) S103. Arrange an N.sup.th isolating layer and an N.sup.th conducting layer in sequence under the first conducting layer, where N is a positive integer greater than or equal to 2.
(37) At the first conducting layer, in a region excluding the M electrodes, a second conductive through holes are disposed that are connected to the first conductive through holes in a one-to-one correspondence. At the N.sup.th isolating layer, in locations corresponding to (2N−2).sup.th conductive through holes, (2N−1).sup.th conductive through holes are disposed that are connected to the (2N−2).sup.th conductive through holes in a one-to-one correspondence. At the N.sup.th conducting layer, Q electrodes are disposed that are spaced apart from one another and connected to Q of the (2N−1).sup.th conductive through holes, and Q is less than or equal to a quantity of the (2N−1).sup.th conductive through holes.
(38) S104. Electrically connect, in a one-to-one correspondence at the N.sup.th conducting layer, electrodes in locations corresponding to at least some of the conductive structures in the first region to electrodes in locations corresponding to at least some of the electrodes in the second region.
(39) Optionally, the first conducting layer is made of metal, polycrystalline silicon, or doped silicon, and the N.sup.th conducting layer is made of metal, polycrystalline silicon, or doped silicon.
(40) Further, the MEMS device layer further includes an optical input/output region, and the method in this embodiment further includes: disposing a high-reflectivity material in a location, at the first conducting layer, corresponding to the optical input/output region. Through disposition of the high-reflectivity material, a coupling loss of the optical input/output region can be reduced.
(41) An implementation principle of the method in this embodiment is similar to that of the technical solution in the foregoing apparatus embodiments, and details are not repeated herein.
(42) According to the electrical packaging method for the MEMS chip provided in this embodiment, the first isolating layer and the first conducting layer are arranged in sequence under the MEMS device layer; at the first isolating layer, there are a corresponding quantity of first conductive through holes in the locations corresponding to the conductive structures in the first region and in the locations corresponding to the electrodes in the second region; and at the first conducting layer, the M electrodes are disposed that are spaced apart from one another and respectively connected to M of the first conductive through holes, so that at least some of the conductive structures in the first region are electrically connected to the corresponding electrodes in the second region in a “one-to-one correspondence”. In this way, at the MEMS device layer, the conductive structures in the first region are led in a “one-to-one correspondence” to the second region, implementing electrical packaging of a MEMS-SOI chip. In addition, the first region is isolated from the to-be-packaged electrode arrangement region, and the MEMS movable structures in the first region can be protected by adding an isolating apparatus, so that electrical packaging of the MEMS-SOI chip can be compatible with a standard electrical packaging process, thereby helping to reduce costs.
(43) Persons of ordinary skill in the art may understand that all or some of the steps of the method embodiments may be implemented by a program instructing relevant hardware. The program may be stored in a non-transitory computer-readable storage medium. When the program runs, the steps of the method embodiments are performed. The foregoing storage medium includes any medium that can store program code, such as a ROM, a RAM, a magnetic disk, or an optical disc.
(44) While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.