CN105984838A - MEMS device and preparation method thereof and electronic device - Google Patents

Abstract

The invention relates to an MEMS device and a preparation method thereof and an electronic device. The method comprises the steps that 1, a bottom wafer is provided, and the MEMS device is formed on the bottom wafer, wherein a detection area and a protection layer covering the detection area are formed on the bottom wafer; 2, a top wafer is provided and connected with the bottom wafer into a whole to wrap the protection layer in a sealing mode; 3, dicing cutting is conducted on the top of the top wafer to form an opening, and part of the protection layer is exposed; 4, the protection layer is removed to expose the detection area. The preparation method has the advantage that the defects generated after dicing are reduced, and particles are reduced; occurrence of probe card damage is avoided, and the preparation cost is reduced.

Description

A kind of MEMS device and its preparation method, electronic device

technical field

The invention relates to the field of semiconductors, in particular, the invention relates to a MEMS device, a preparation method thereof, and an electronic device.

Background technique

With the continuous development of semiconductor technology, in the market of various sensor (motion sensor) products, smart phones, integrated CMOS and micro-electromechanical system (MEMS) devices have increasingly become the most mainstream and advanced technology, and with the development of technology Newer, the development direction of this type of product is smaller size, high-quality electrical performance and lower loss.

In the field of MEMS, reliability testing, such as WAT/CP test, etc. is required after wafer bonding (Bonding Wafer), so dicing (Dicing) is usually performed after wafer bonding, and only the top wafer is usually cut off in this step (Top Wafer) The device that exposes the bottom wafer (Bottom Wafer) can be tested for WAT/CP, etc. When the top wafer is cut, some particles (Particle) usually fall on the bottom wafer, resulting in The probe (Probe Card) is damaged after contact with the particles.

Therefore, it is necessary to further improve the current manufacturing method and/or detection method of semiconductor devices in order to eliminate the above-mentioned problems.

Contents of the invention

A series of concepts in simplified form are introduced in the Summary of the Invention, which will be further detailed in the Detailed Description. The summary of the invention in the present invention does not mean to limit the key features and essential technical features of the claimed technical solution, nor does it mean to try to determine the protection scope of the claimed technical solution.

The present invention provides a kind of preparation method of MEMS device in order to overcome existing problem at present, comprising:

Step S1: providing a bottom wafer on which MEMS devices are formed, wherein a detection area and a protective layer covering the detection area are also formed on the bottom wafer;

Step S2: providing a top wafer and bonding it with the bottom wafer to seal and wrap the protective layer;

Step S3: Scribing and cutting the top of the top wafer to form an opening to expose part of the protective layer;

Step S4: removing the protection layer to expose the detection area.

Optionally, the step S1 includes:

Step S11: providing a bottom wafer and depositing a protective material layer on the bottom wafer to cover the MEMS device;

Step S12 : patterning the protection material layer to form the protection layer in the detection area and expose the MEMS device outside the detection area.

Optionally, in the step S2, several functional patterns are formed in the top wafer, wherein the cavity formed between two adjacent functional patterns matches the shape of the protective layer, so as to The protective layer is sealed after the bonding.

Optionally, in the step S1, polyimide is selected as the protective layer.

Optionally, in the step S1, the protective layer has a thickness of 25-35um.

Optionally, a step of grinding and thinning the top wafer is further included between the step S2 and the step S3.

Optionally, in the step S4, the protection layer is removed by ashing and stripping.

Optionally, after the step S4, the method further includes the step of detecting the detection area.

The present invention also provides a MEMS device prepared based on the above method.

The present invention also provides an electronic device, including the above-mentioned MEMS device.

In order to solve the problems in the prior art, the present invention provides a MEMS device and its manufacturing method. In the method, a protective layer is formed on the detection area before bonding, so as to avoid opening the top wafer Particles generated during the process fall on the bottom wafer, and by changing the process of MEMS products, the particles on the bottom wafer are effectively reduced, and the problem of damage to the detection probes is suppressed.

The advantages of the present invention are:

1. Reduce the defects after dicing (Dicing), and reduce the particles.

2. The detection probe damage (Probe Card damage) is avoided, and the manufacturing cost is reduced.

Description of drawings

The following drawings of the invention are hereby included as part of the invention for understanding the invention. Embodiments of the present invention and their descriptions are shown in the drawings to explain the device and principle of the present invention. In the attached picture,

1a-1d are schematic diagrams of the preparation process of MEMS devices described in the prior art;

2a-2g are schematic diagrams of the preparation process of the MEMS device described in the prior art;

Fig. 3 is a flow chart of the manufacturing process of the MEMS device in a specific embodiment of the present invention.

detailed description

In the following description, numerous specific details are given in order to provide a more thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without one or more of these details. In other examples, some technical features known in the art are not described in order to avoid confusion with the present invention.

It should be understood that the invention can be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity. Like reference numerals refer to like elements throughout.

It will be understood that when an element or layer is referred to as being "on," "adjacent," "connected to" or "coupled to" another element or layer, it can be directly on the other element or layer. A layer may be on, adjacent to, connected to, or coupled to other elements or layers, or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" another element or layer, there are no intervening elements or layers present. layer. It will be understood that, although the terms first, second, third etc. may be used to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention.

Spatial terms such as "below", "below", "below", "under", "on", "above", etc., in This may be used for convenience of description to describe the relationship of one element or feature to other elements or features shown in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use and operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements or features described as "below" or "beneath" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary terms "below" and "beneath" can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatial descriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the/the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. It should also be understood that the terms "consists of" and/or "comprising", when used in this specification, identify the presence of stated features, integers, steps, operations, elements and/or parts, but do not exclude one or more other Presence or addition of features, integers, steps, operations, elements, parts and/or groups. As used herein, the term "and/or" includes any and all combinations of the associated listed items.

The manufacturing method of the MEMS device described in the prior art is shown in Figures 1a-1d, at first, as shown in Figure 1, a bottom wafer 101 and a top wafer 102 are provided, and then the bottom wafer 101 and the top wafer 102 is bonded together, as shown in Figure 1b, and then the back grinding process is performed to reduce the thickness of the top wafer 102, as shown in Figure 1c, and finally the top wafer (Top Wafer) is cut off to expose the bottom wafer (Bottom Wafer). The device of Wafer) carries out WAT/CP test, and some particles (Particle) usually appear on the bottom wafer when cutting the top wafer, causing the probe (Probe Card) to be damaged after contacting the particle during detection, as shown in the figure 1d shown on the right.

Therefore, it is necessary to further improve the current manufacturing method and/or detection method of semiconductor devices in order to eliminate the above-mentioned problems.

Example 1

In order to solve the problems existing in the current MEMS device preparation process, the present invention provides a preparation of a MEMS device. The method will be further described below in conjunction with accompanying drawings 2a-2g, wherein, Fig. 2a-2g is the method described in the present invention Schematic diagram of the fabrication process of the MEMS device.

Firstly, step 201 is performed to provide a bottom wafer 201 on which MEMS devices are formed, wherein the bottom wafer 201 includes a detection area.

Specifically, as shown in FIG. 2a, in this step, the bottom wafer 201 may be at least one of the materials mentioned below: silicon, silicon-on-insulator (SOI), silicon-on-insulator (SSOI) , Silicon germanium on insulator (S-SiGeOI), silicon germanium on insulator (SiGeOI) and germanium on insulator (GeOI), etc.

A MEMS device is formed on the front surface of the bottom wafer 201 , wherein the MEMS device can be selected according to the type of MEMS device, for example, it can be a diaphragm, a back plate, an electrode, etc., and is not limited to a certain one.

Wherein, in order to test the prepared device, a region for testing reliability and other related properties is also formed in the bottom wafer. The MEMS device is formed on the detection area and the area around the detection area.

Step 202 is executed to deposit a protective material layer on the bottom wafer to cover the MEMS device.

Specifically, as shown in FIG. 2a, a protective material layer is deposited to cover the bottom wafer and the MEMS devices.

Wherein, the protective material layer is selected from polyimide, and the thickness of the protective material layer is 25-35um.

Step 203 is executed to pattern the protection material layer to form the protection layer 202 in the detection area and expose the MEMS device outside the detection area.

As shown in FIG. 2b, in this step, the protective material layer is patterned to form the protective layer 202 in the detection area, as indicated by the arrow, and the protective layer is filled in the detection area. After the bottom wafer and the top wafer are combined, the protective layer is stuck between the bottom wafer and the top wafer, which can effectively prevent particles caused by dicing from falling on the bottom wafer and scratching it.

In this step, the MEMS device outside the detection area is exposed at the same time. In an embodiment of the present invention, an atmosphere of O ₂ is used to etch the protective material layer, and other small amounts of gases such as CF ₄ and CO ₂ can also be added at the same time. , N ₂ , the etching pressure can be 50-200mTorr, preferably 100-150mTorr, the power is 200-600W, the etching time in the present invention is 5-80s, and a larger gas flow rate is selected in the present invention , the flow rate of O ₂ in the present invention is 30-300 sccm.

Step 204 is executed to provide a top wafer 203 , which is integrated with the bottom wafer to fit and wrap the protection layer 202 .

Specifically, as shown in FIG. 2c, a top wafer 203 is provided in this step, wherein several functional patterns are formed in the top wafer, and there are cavities formed between two adjacent functional patterns. Matching the shape of the protective layer to seal the protective layer after the bonding.

After bonding, the top surface of the protective layer is close to the surface of the cavity formed by the functional pattern in the top wafer, and its sidewall is close to the sidewall of the functional element, so the protective layer and the The top wafer is directly sealed and bonded without any gap between the two, and the protective layer completely fills the cavity and the surface of the detection area to effectively prevent particles caused by dicing from falling on the bottom wafer Scratch on.

The top wafer 203 is then bonded to the bottom wafer 201 as shown in FIG. 2d to form a closed space between the two. The bonding method may be eutectic bonding or thermal bonding to form an integrated structure.

Before the bonding, it may also include pre-cleaning the bottom wafer 201 to improve the bonding performance of the bottom wafer 201 . Specifically, in this step, the surface of the bottom wafer 201 is pre-cleaned with diluted hydrofluoric acid DHF (including HF, H ₂ O ₂ and H ₂ O), wherein the concentration of the DHF is not Strictly limited, HF:H ₂ O ₂ :H ₂ O=0.1-1.5:1:5 is preferred in the present invention.

In addition, after the cleaning step, the method further includes drying the bottom wafer 201 .

Optionally, isopropanol (IPA) is used to dry the bottom wafer 201 .

Step 205 is executed, grinding and thinning the top wafer and dicing and cutting the top of the top wafer to form an opening to expose part of the protection layer.

Specifically, as shown in Figure 2e, in this step, the top wafer is thinned by grinding and thinning, wherein the grinding and thinning parameters can be selected from various parameters commonly used in the art, and are not limited to A certain range of values will not be repeated here.

Then use the method of laser scribing to cut the top wafer, as shown in Figure 2f, for example, select a semiconductor laser scribing machine (such as a semiconductor laser scribing machine model G3005F), and the depth accuracy is controlled to 300u+/- 5u, the maximum scribe depth is 1.2mm.

In this step, the laser wavelength used for the laser scribing: 1.06μm, the scribing line width: ≤0.03mm, the laser repetition frequency: 20KHz～100KHz, the maximum scribing speed: 230mm/s, the maximum laser power: ≤15W (The maximum power can be increased according to the choice of laser), power supply: 220V/50Hz/1KVA, cooling method: forced air cooling.

In this step, usually only the top wafer (Top Wafer) is cut off to expose part of the protective layer, so that the protective layer can be removed in subsequent steps.

In this step, since the protective layer is filled between the top wafer 203 and the bottom wafer in the detection area, the protective layer is stuck between the bottom wafer and the top wafer to effectively prevent dicing (Dicing) caused by falling particles on the bottom wafer scratches.

Step 206 is executed to remove the protection layer to expose the detection area.

Specifically, as shown in FIG. 2g, the protection layer is removed by ashing and stripping to expose the detection area and the MEMS device in the detection area.

Step 207 is executed to detect the detection area.

For example, the WAT/CP test is performed on devices on the bottom wafer (Bottom Wafer), etc., which will not be repeated here.

So far, the introduction of the relevant steps of the manufacturing method of the MEMS device according to the embodiment of the present invention is completed. After the above steps, other related steps may also be included, which will not be repeated here. Moreover, in addition to the above-mentioned steps, the manufacturing method of this embodiment may also include other steps among the above-mentioned various steps or between different steps, and these steps can be realized by various processes in the prior art, here No longer.

In order to solve the problems in the prior art, the present invention provides a MEMS device and its manufacturing method. In the method, a protective layer is formed on the detection area before bonding, so as to avoid opening the top wafer Particles generated during the process fall on the bottom wafer, and by changing the process of MEMS products, the particles on the bottom wafer are effectively reduced, and the problem of damage to the detection probes is suppressed.

The advantages of the present invention are:

1. Reduce the defects after dicing (Dicing), and reduce the particles.

2. The detection probe damage (Probe Card damage) is avoided, and the manufacturing cost is reduced.

Fig. 3 is the manufacturing process flowchart of MEMS device described in a specific embodiment of the present invention, specifically comprises the following steps:

Step S1: providing a bottom wafer on which MEMS devices are formed, wherein a detection area and a protective layer covering the detection area are also formed on the bottom wafer;

Step S2: providing a top wafer and bonding it with the bottom wafer to seal and wrap the protective layer;

Step S3: Scribing and cutting the top of the top wafer to form an opening to expose part of the protective layer;

Step S4: removing the protection layer to expose the detection area.

Example 2

The present invention also provides a MEMS device, which is prepared by the method described in Example 1. The MEMS device prepared by the method described in Example 1 of the present invention has reduced defects after dicing (Dicing), and reduced particles (particle). At the same time, the occurrence of detection probe damage (Probe Card damage) is avoided, and the manufacturing cost is reduced.

Example 3

The present invention also provides an electronic device, including the MEMS device described in Embodiment 2. Wherein, the MEMS device is the MEMS device described in Example 2, or the MEMS device obtained according to the preparation method described in Example 1.

The electronic device of this embodiment can be any electronic product or equipment such as mobile phone, tablet computer, notebook computer, netbook, game console, TV set, VCD, DVD, navigator, camera, video recorder, voice recorder, MP3, MP4, PSP, etc. , can also be any intermediate product including the MEMS device. The electronic device of the embodiment of the present invention has better performance due to the use of the above-mentioned MEMS device.

The present invention has been described through the above-mentioned embodiments, but it should be understood that the above-mentioned embodiments are only for the purpose of illustration and description, and are not intended to limit the present invention to the scope of the described embodiments. In addition, those skilled in the art can understand that the present invention is not limited to the above-mentioned embodiments, and more variations and modifications can be made according to the teachings of the present invention, and these variations and modifications all fall within the claimed scope of the present invention. within the range. The protection scope of the present invention is defined by the appended claims and their equivalent scope.

Claims (10)

1. A method for preparing a MEMS device, comprising: Step S1: providing a bottom wafer on which MEMS devices are formed, wherein a detection area and a protective layer covering the detection area are also formed on the bottom wafer; Step S2: providing a top wafer and bonding it with the bottom wafer to seal and wrap the protective layer; Step S3: Scribing and cutting the top of the top wafer to form an opening to expose part of the protective layer; Step S4: removing the protection layer to expose the detection area. 2. The method according to claim 1, wherein said step S1 comprises: Step S11: providing a bottom wafer and depositing a protective material layer on the bottom wafer to cover the MEMS device; Step S12 : patterning the protection material layer to form the protection layer in the detection area and expose the MEMS device outside the detection area. 3. The method according to claim 1, wherein in the step S2, several functional patterns are formed in the top wafer, wherein the cavities formed between two adjacent functional patterns Matching the shape of the protective layer to seal the protective layer after the bonding. 4. The method according to claim 1, characterized in that, in the step S1, polyimide is selected as the protective layer. 5. The method according to claim 1, characterized in that, in the step S1, the thickness of the protective layer is 25-35um. 6. The method according to claim 1, further comprising a step of grinding and thinning the top wafer between the step S2 and the step S3. 7. The method according to claim 1, characterized in that, in the step S4, the protective layer is removed by ashing and stripping. 8. The method according to claim 1, characterized in that, after the step S4, the method further comprises the step of detecting the detection area. 9. A MEMS device prepared based on the method according to any one of claims 1 to 8. 10. An electronic device comprising the MEMS device of claim 9.