Preparation method of MEMS thermosensitive chip

Abstract

The invention discloses a preparation method of an MEMS thermosensitive chip, and relates to the technical field of MEMS sensing. The preparation method comprises the following steps: depositing a metal aluminum layer on the surface of a substrate, wherein the deposition temperature of the metal aluminum layer is any one value in the range of 300-500 DEG C; the surface of the metal aluminum layer is pretreated to remove the oxidation film layer, and a dielectric film layer is deposited on the metal aluminum layer within the preset time after pretreatment; wherein metal bonding between the metal aluminum layer and the substrate is canceled. According to the preparation method disclosed by the invention, the MEMS thermosensitive chip with relatively high product yield and relatively high reliability is prepared by combining the preparation methods of high-temperature deposition of the metal aluminum layer, pretreatment of the metal aluminum layer and deposition of the dielectric film layer within the preset time; the problem that in the prior art, impedance is increased due to the fact that the anti-migration rate of a metal aluminum layer is improved by depositing a Ti-containing layer can be solved.

Description

Technical Field

[0001] The invention relates to the field of MEMS sensing technology, and in particular to a method for preparing a MEMS thermal sensitive chip. Background Art

[0002] As large cavity thin film layer structure MEMS (Micro-Electro-Mechanical System) thermistor chips are widely used in gas flow, temperature measurement, and gas detection, the demand for high-reliability MEMS thermistor chips is increasing. Al / Si contact thermistor structure relies on a mature semiconductor micromachining system, has high processing accuracy, production efficiency, and low preparation cost, and is widely used in the field of semiconductor micromachining technology. As an important component of Al / Si contact, the improvement of Al metal wire's anti-migration performance is crucial to the reliability of MEMS thermistor chips.

[0003] In the prior art, a sputtering deposition process of a metal aluminum layer is usually performed under low temperature conditions and a metal bonding process of the metal aluminum layer and a substrate is performed under high temperature conditions, or a MEMS thermistor chip is directly prepared using a single-layer metal aluminum layer structure. Although the anti-migration ability of the MEMS thermistor chip can be improved to a certain extent, when there are alternating changes in temperature, humidity, and charge in the environment where the MEMS thermistor chip is located, thermal migration or electromigration will still occur, thereby affecting the reliability of the product. Summary of the invention

[0004] An object of the present invention is to provide a method for preparing a MEMS thermistor chip, so as to solve the technical problem in the prior art that the MEMS thermistor chip is prone to thermal migration or electromigration when the temperature, humidity or charge changes alternately.

[0005] Another object of the present invention is to further improve the product reliability of the MEMS thermal chip.

[0006] According to the purpose of the present invention, the present invention provides a method for preparing a MEMS thermal chip, comprising:

[0007] Depositing a metal aluminum layer on the surface of the substrate, wherein the deposition temperature of the metal aluminum layer is any value in the range of 300° C. to 500° C.;

[0008] The surface of the metal aluminum layer is pretreated to remove the oxide film layer, and a dielectric film layer is deposited on the metal layer within a preset time after the pretreatment; wherein,

[0009] The metal bonding between the metal aluminum layer and the substrate is eliminated.

[0010] Optionally, the pretreatment is performed by dry etching.

[0011] Optionally, the pre-treatment etching depth is in the range of Any value in .

[0012] Optionally, the step of depositing a metal aluminum layer on the surface of the substrate further includes:

[0013] Depositing a first migration layer on the surface of the substrate;

[0014] Depositing the metal aluminum layer on the surface of the first migration layer;

[0015] A second migration layer is deposited on the surface of the metal aluminum layer, and the second anti-migration layer is partially etched to form a PAD window, wherein:

[0016] The first anti-migration layer and the second anti-migration layer both include a Ti layer and a TiN layer in sequence from bottom to top, and the ratio of the thickness of the first anti-migration layer and the second anti-migration layer to the thickness of the metal aluminum layer is in a range of 0.05-0.10.

[0017] Optionally, the metal aluminum layer is made of any one of aluminum, aluminum-copper alloy or aluminum-silicon-copper alloy.

[0018] Optionally, the material of the dielectric film layer is any one of silicon oxide and silicon nitride, and the thickness of the dielectric film layer is in the range of Any value in .

[0019] Optionally, the thickness of the Ti layer is in the range of The thickness of the TiN layer is in the range of Any value in .

[0020] Optionally, before the step of depositing the first anti-migration layer on the substrate surface, the method further comprises:

[0021] The dielectric film layer is deposited on the substrate.

[0022] Optionally, the preparation method further comprises:

[0023] The metal aluminum layer and the substrate are metal bonded at a temperature ranging from 300° C. to 400° C.

[0024] The present invention directly deposits a metal aluminum layer at high temperature on the surface of a substrate, pre-treats the surface of the metal aluminum layer to remove an oxide film layer on the surface of the metal aluminum layer, and deposits a dielectric film layer on the surface of the metal aluminum layer within a preset time after the pre-treatment. Since the grains of the metal aluminum become coarse under high temperature conditions, the electromigration of the metal aluminum layer is reduced to a certain extent. Moreover, the oxide film layer on the surface of the metal aluminum layer is removed by pre-treatment and the deposition of the dielectric film layer is started within a preset time, so that the formation of the oxide film layer of the metal aluminum layer can be further reduced, thereby reducing the phenomenon that the oxide film layer causes electromigration of the metal aluminum layer, thereby enhancing the anti-migration ability of the metal aluminum layer and improving the reliability of the MEMS thermal sensitive chip.

[0025] Furthermore, the etching depth of the pretreatment of the present invention is in the range of When the etching depth of the TiN layer surface of the second anti-migration layer is within the above range, not only can the oxide film layer on the surface of the TiN layer be completely removed, but also the thickness of the TiN layer can be ensured to be used as a stop layer for subsequent etching processes, thereby ensuring the product reliability of the MEMS thermistor chip.

[0026] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Hereinafter, some specific embodiments of the present invention will be described in detail in an exemplary and non-limiting manner with reference to the accompanying drawings. The same reference numerals in the accompanying drawings indicate the same or similar components or parts. It should be understood by those skilled in the art that these drawings are not necessarily drawn to scale. In the accompanying drawings:

[0028] Figure 1 is a schematic flow chart of a method for preparing a MEMS thermal-sensitive chip according to an embodiment of the present invention;

[0029] Figure 2 is a test result of the thermal shock defect rate of a MEMS thermal-sensitive chip according to an embodiment of the present invention;

[0030] Figure 3 is a linear correlation diagram between polysilicon thickness and total impedance in a MEMS thermal-sensitive chip according to an embodiment of the present invention;

[0031] Figure 4 It is a schematic bar chart of the yield test of the MEMS thermal sensitive chip in Example 1 and Comparative Examples 1-4 according to the present invention. DETAILED DESCRIPTION

[0032] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0033] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. It is to be understood that the specific embodiments described herein are only used to explain the present application, rather than to limit the present application. It should also be noted that, for ease of description, only some structures related to the present application are shown in the accompanying drawings, rather than all structures. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0034] The terms "including" and "having" and any variations thereof in this application are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products or devices.

[0035] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0036] Figure 1 It is a schematic flow chart of a method for preparing a MEMS thermal-sensitive chip according to an embodiment of the present invention.

[0037] like Figure 1 As shown, the present invention provides a method for preparing a MEMS thermal chip, comprising:

[0038] Step S100: depositing a metal aluminum layer on the surface of the substrate, wherein the deposition temperature of the metal aluminum layer is any value in the range of 300° C.-500° C.;

[0039] Step S200: pre-treating the surface of the second anti-migration layer to remove the oxide film layer, and depositing a dielectric film layer on the metal aluminum layer within a preset time after the pre-treatment, wherein the metal bonding between the metal aluminum layer and the substrate is cancelled.

[0040] In this embodiment, in the method for preparing the MEMS thermistor chip, a metal aluminum layer is first deposited on the surface of the substrate, and the deposition temperature of the metal aluminum layer is any value in the range of 300°C-500°C, and then the surface of the metal aluminum layer is pretreated to remove the oxide film layer, and a dielectric film layer is deposited on the metal aluminum layer within a preset time after the pretreatment, thereby preparing the MEMS thermistor chip. Here, the thickness of the metal aluminum layer is in the range of 4000 Any value in the range, that is, the thickness of the metal aluminum layer can be or It can also be The deposition temperature of the metal aluminum layer is any value in the range of 300°C-500°C, that is, the deposition temperature of the metal aluminum layer can be 300°C, 350°C, 400°C, 450°C or 500°C, or can be any value in the range of 300°C-500°C.

[0041] In the present embodiment, a metal aluminum layer is directly deposited on the surface of the substrate at a high temperature, and the surface of the metal aluminum layer is pretreated to remove the oxide film layer on the surface of the metal aluminum layer, and a dielectric film layer is deposited on the surface of the metal aluminum layer within a preset time after the pretreatment. Since the grains of the metal aluminum become coarse under high temperature conditions, the electromigration of the metal aluminum layer will be reduced to a certain extent. Moreover, the oxide film layer on the surface of the metal aluminum layer is removed by pretreatment and the deposition of the dielectric film layer is started within a preset time, so that the formation of the oxide film layer of the metal aluminum layer can be further reduced, thereby reducing the phenomenon that the oxide film layer causes electromigration of the metal aluminum layer, thereby enhancing the anti-migration ability of the metal aluminum layer and improving the reliability of the MEMS thermal sensitive chip.

[0042] In this embodiment, the preset time is any value between 30min and 120min, that is, the interval time for dielectric film deposition after pretreatment can be 30min, 60min, 90min or 120min, or any value between 30min and 120min. That is, when the surface of the metal aluminum layer is pretreated, the equipment parameters and state for dielectric film deposition are adjusted to a ready state, and dielectric film deposition is started within the preset time after the pretreatment is completed, so as to reduce the contact time between the metal aluminum layer and the air, thereby reducing the oxidation time of the metal aluminum layer, preventing the formation of an oxide film layer, and further improving the anti-migration rate of the metal aluminum layer.

[0043] Figure 2 1 is a test result of the thermal shock defect rate of a MEMS thermal-sensitive chip according to an embodiment of the present invention.

[0044] In this embodiment, stress adjustment is used to re-match the stress of the film layer, reduce the risk of stress mismatch and thermal shock failure caused by changes in metal deposition temperature and cancellation of metal bonding, thereby solving the problem of aggravated metal migration caused by high-temperature metal bonding, and re-matching the stress between film layers to ensure the structural stability and thermal shock yield of the MEMS thermal chip. Specifically, stress adjustment is achieved by adjusting the power, gas flow or temperature during film deposition, that is, by adjusting the above parameters, the initial stress between film layers is adjusted to stress one to stress four, wherein the initial stress is a positive stress, stress one is -500%, stress two is -300%, stress three is -100%, and stress four is +300%.

[0045] As shown in the figure, when the stress of the MEMS thermistor chip is adjusted to stress one or stress two, the thermal shock defect rate of the corresponding MEMS thermistor chip is the lowest, that is, the thermal shock yield rate of the MEMS thermistor chip is the highest.

[0046] In a preferred embodiment, step S100 further includes:

[0047] Depositing a first migration layer on the substrate surface;

[0048] Depositing a metal aluminum layer on the surface of the first migration layer;

[0049] A second migration layer is deposited on the surface of the metal aluminum layer, and the second anti-migration layer is partially etched to form a PAD window, wherein the first anti-migration layer and the second anti-migration layer both include a Ti layer and a TiN layer sequentially arranged from bottom to top, and the ratio of the thickness of the first anti-migration layer and the second anti-migration layer to the thickness of the metal aluminum layer is in a range of 0.05-0.10.

[0050] In this embodiment, a first anti-migration layer, a metal aluminum layer, and a second anti-migration layer are sequentially deposited on the surface of the substrate, and the second anti-migration layer is partially etched to form a PAD window to expose the pad position, thereby preventing the second anti-migration layer from affecting the distribution of the pad lead after being deposited on the surface of the metal aluminum layer, thereby reducing the deposition effect of the second anti-migration layer. Here, the ratio of the thickness of the first anti-migration layer and the second anti-migration layer to the thickness of the metal aluminum layer can be 0.05, 0.06, 0.07, 0.08, 0.09 or 0.10, or any value in the range of 0.05-0.10.

[0051] In this embodiment, the first anti-migration layer includes a Ti layer and a TiN layer stacked from bottom to top, and the second anti-migration layer includes a Ti layer and a TiN layer stacked from bottom to top. By arranging the first anti-migration layer and the second anti-migration layer on the upper and lower surfaces of the metal aluminum layer, and the TiN layer of the first anti-migration layer and the Ti layer of the second anti-migration layer are respectively arranged on the bottom surface and the top surface of the metal aluminum layer, not only can thermal migration or electromigration between the metal aluminum layer and the substrate be prevented, but also the electrical conductivity and thermal conductivity of the MEMS thermal chip can be guaranteed.

[0052] Figure 3 4 is a linear correlation diagram between polysilicon thickness and total impedance in a MEMS thermal-sensitive chip according to an embodiment of the present invention.

[0053] In this embodiment, the material of the substrate is polysilicon, that is, the thickness of the polysilicon substrate is determined according to the increment of the total impedance generated by the first anti-migration layer. In other words, the existence of the first anti-migration layer will increase the total impedance of the MEMS thermistor chip, thereby reducing the sensitivity of the MEMS thermistor chip. In order to avoid the above situation, the total impedance of the MEMS thermistor chip is usually reduced by increasing the thickness of the polysilicon substrate to ensure the detection sensitivity of the MEMS thermistor chip.

[0054] like Figure 3 As shown, with the increase of polysilicon thickness, the total impedance of the MEMS thermistor gradually decreases, that is, the problem of increased total impedance caused by the first anti-migration layer is solved by increasing the thickness of the substrate, thereby meeting the impedance requirements of the MEMS thermistor chip.

[0055] In a further embodiment, the pretreatment method is dry etching. In this embodiment, dry etching can very accurately remove the oxide film on the surface of the TiN layer, so as to remove the oxide layer while retaining the integrity and surface quality of the TiN layer to the greatest extent. In addition, dry etching does not involve liquid chemical reagents when removing the oxide film, avoids the use of liquid chemicals, reduces potential pollution or corrosion problems, ensures a cleaner surface, facilitates the subsequent deposition process, and enhances the adhesion of the TiN layer. Here, after the pretreatment starts, a post-process dielectric film deposition process machine is reserved to achieve dielectric film coverage within a preset time, and the preset time can be within 120 minutes.

[0056] In a further embodiment, the pre-treatment etching depth is in the range of Any value in the range, that is, the depth of etching the surface of the metal aluminum layer can be or It can also be In this embodiment, the pre-treatment etching depth is in the range of When the etching depth of the metal aluminum layer is within the above range, the oxide film on the surface of the metal aluminum layer can be completely removed to prevent oxidation friction from affecting the anti-migration ability of the metal aluminum layer, thereby ensuring the product reliability of the MEMS thermistor chip.

[0057] In a further embodiment, the material of the metal aluminum layer is any one of aluminum, aluminum-copper alloy or aluminum-silicon-copper alloy. In this embodiment, when the material of the metal aluminum layer is aluminum, since aluminum has the characteristics of low cost, excellent electrical conductivity and high thermal conductivity, the MEMS thermistor chip has high electrical conductivity and thermal conductivity, and the production cost is low. When the material of the metal aluminum material is aluminum-copper alloy, the anti-thermal migration performance of aluminum in the aluminum-copper alloy is improved, and since copper has a high melting point and a low thermal diffusion rate, it can effectively inhibit the migration of aluminum elements at high temperatures, enhance the stability and durability of the metal aluminum layer, improve the anti-migration characteristics of the metal aluminum layer, and further improve the product reliability of the MEMS thermistor chip. When the material of the metal aluminum material is aluminum-silicon-copper alloy, the MEMS thermistor chip has stronger anti-migration, higher wear resistance and corrosion resistance, good mechanical properties, and excellent electrical conductivity and thermal conductivity.

[0058] In this embodiment, when the material of the metal aluminum layer is aluminum-copper alloy, the copper content in the aluminum-copper alloy is any value in the range of 0.5%-1.0%, that is, the copper content in the aluminum-copper alloy can be 0.5%, 0.6%, 0.7%, 0.8%, 0.9% or 1.0%, or any value in the range of 0.5%-1.0%. In this embodiment, the addition of copper elements within the above range can improve the thermal sensitivity of the metal aluminum layer in the MEMS thermistor chip, making the metal aluminum layer more sensitive to temperature changes, thereby improving the temperature measurement accuracy and sensitivity of the MEMS thermistor chip.

[0059] In this embodiment, when the material of the metal aluminum layer is aluminum-silicon-copper alloy, the copper content in the aluminum-silicon-copper alloy is any value in the range of 0.5%-1.0%, and the silicon content is any value in the range of 0.5%-1.0%, that is, the copper content in the aluminum-silicon-copper alloy can be 0.5%, 0.6%, 0.7%, 0.8%, 0.9% or 1.0%, or any value in the range of 0.5%-1.0%, that is, the silicon content in the aluminum-silicon-copper alloy can be 0.5%, 0.6%, 0.7%, 0.8%, 0.9% or 1.0%, or any value in the range of 0.5%-1.0%. In this embodiment, the copper and silicon elements in the aluminum-silicon-copper alloy can form a solid solution or other compounds with aluminum, thereby inhibiting the migration of aluminum atoms, and the addition of copper and silicon elements improves the thermal stability of the aluminum-silicon-copper alloy, so that the MEMS thermal chip maintains a stronger structural integrity at high temperatures, thereby reducing the occurrence of thermal migration and further improving the anti-migration characteristics of the MEMS thermal chip. In addition, the addition of copper and silicon will improve the mechanical properties of the aluminum-silicon-copper alloy, increase the strength and hardness of the aluminum-silicon-copper alloy, and increase the wear resistance and corrosion resistance of the MEMS thermal chip.

[0060] In this embodiment, when the material of the metal aluminum layer is aluminum-silicon-copper alloy, when the content of copper and silicon in the aluminum-silicon-copper alloy is within the above range, the sensitivity of the MEMS thermistor chip to temperature changes can be maintained while improving its stability and durability.

[0061] In a further embodiment, the material of the dielectric film layer is any one of silicon oxide or silicon nitride, and the thickness of the dielectric film layer is in the range of Any value in the range, that is, the dielectric film layer can be a silicon oxide layer or a silicon nitride layer, and the thickness of the dielectric film layer can be or It can also be In this embodiment, silicon oxide and silicon nitride are used as the material of the dielectric film layer, which can effectively isolate the first anti-migration layer, the metal aluminum layer and the substrate, prevent current leakage or short circuit, and ensure the electrical performance of the MEMS thermistor chip is stable. In addition, both silicon oxide and silicon nitride have good thermal stability and low thermal expansion coefficient, and can effectively inhibit the migration of metal atoms. As a dielectric film layer, they can effectively reduce the thermal expansion mismatch caused by temperature changes, avoid the stress caused by the difference in thermal expansion between the substrate and the metal layer, and thus improve the mechanical stability and thermal reliability of the chip. In addition, the thickness of the dielectric film layer is Within the range of , it can provide sufficient mechanical strength to protect the MEMS thermal chip from external physical damage, thereby enhancing the wear resistance of the MEMS thermal chip.

[0062] In a further embodiment, the thickness of the Ti layer in the first anti-migration layer and the second anti-migration layer is in the range of For any value in the range of Any value, that is, the thickness of the Ti layer of the first anti-migration layer and the second anti-migration layer is the same, the thickness of the TiN layer is also the same, the thickness of the Ti layer can be or It can also be For any value of , the thickness of the TiN layer can be or It can also be in the range In this embodiment, the Ti layer of the first anti-migration layer is arranged at the bottom of the metal aluminum layer, and the second anti-migration layer is arranged on the top of the metal aluminum layer, that is, the thickness of the Ti layer located on the upper and lower surfaces of the metal aluminum layer is within the above range, which can not only prevent the metal aluminum layer from electromigration or thermal migration, but also ensure the functional characteristics of the MEMS thermal chip.

[0063] In a further embodiment, before step S100, the following steps are further included:

[0064] A dielectric film layer is deposited on the substrate.

[0065] In this embodiment, before depositing the first anti-migration layer on the substrate surface, a dielectric film layer is first deposited on the substrate surface, that is, a dielectric film layer is deposited between the substrate of the MEMS thermal chip and the first anti-migration layer. The dielectric film layer serves as an isolation layer, which can prevent the metal aluminum layer from directly contacting the substrate, and helps to reduce the electrochemical reaction between the metal aluminum layer and the substrate, metal corrosion or adverse reactions between materials, and avoid chemical reactions and electromigration problems between the substrate and the metal aluminum layer. Here, the dielectric film layer can be a silicon oxide layer or a silicon nitride layer, and the MEMS thermal chip includes a substrate, a dielectric film layer, a Ti layer, a TiN layer, a metal aluminum layer, a Ti layer, a TiN layer, and a dielectric film layer, which are sequentially distributed from bottom to top.

[0066] In another embodiment, the preparation method further comprises:

[0067] The metal aluminum layer and the substrate are metal bonded at a temperature ranging from 300° C. to 400° C.

[0068] In this embodiment, the temperature for metal bonding of the metal aluminum layer and the substrate can be 300°C, 310°C, 320°C, 330°C, 340°C, 350°C, 360°C, 370°C, 380°C, 390°C or 400°C, or any value between 300°C and 400°C. In this embodiment, by metal bonding the metal aluminum layer and the substrate under the above temperature conditions, it is helpful to form a good metal-metal bonding interface between the metal aluminum layer and the substrate surface to form an ohmic contact. Moreover, under the above temperature conditions, aluminum atoms can effectively diffuse to the substrate surface, enhance bonding strength and reliability, and reduce the risk of falling off or bonding failure. At the same time, it avoids thermal damage to the substrate or other sensitive materials due to excessively high temperatures, and it can also avoid stress accumulation at the interface due to excessively rapid thermal diffusion, thereby preventing the performance or structural stability of the chip from being affected.

[0069] In this embodiment, the metal bonding step between the metal aluminum layer and the substrate can be placed before or after the deposition of the dielectric film layer above the metal aluminum layer, or after the PAD window is opened. That is, the metal bonding performed at different stages of the MEMS thermal chip preparation process will affect the overall stress matching of the MEMS thermal chip, and then affect the chip's thermal shock resistance reliability. Therefore, the metal bonding at different stages needs to be matched with a stress combination that matches the overall stress. Here, the stress matching of the MEMS thermal chip can be adjusted by adjusting the power, gas flow, and temperature of the deposition process.

[0070] The present application will be further described in detail below with reference to specific embodiments.

[0071] In some embodiments, a metal aluminum layer is first deposited on the surface of the substrate. The deposition temperature of the metal aluminum layer is any value in the range of 300° C. to 500° C., and the thickness of the metal aluminum layer is in the range of The upper surface of the metal aluminum layer is then dry-etched to remove the oxide film layer. The etching depth of the dry etching is in the range of Any value in the range of , and within 30min-120min after dry etching, a dielectric film layer made of silicon oxide is deposited on the surface of the metal aluminum layer, and the thickness of the dielectric film layer is in the range of Any value in the range is used to prepare a MEMS thermistor chip.

[0072] Example 1

[0073] First, a dielectric film layer made of silicon oxide is deposited on the surface of the substrate. The thickness of the dielectric film layer is A metal aluminum layer is deposited on the surface of the dielectric film layer. The deposition temperature of the metal aluminum layer is 400°C and the thickness of the metal aluminum layer is in the range of Then, the upper surface of the metal aluminum layer is dry-etched to remove the oxide film layer. The etching depth of the dry-etching is After dry etching, a dielectric film layer made of silicon oxide is deposited on the surface of the metal aluminum layer within 60 minutes. The thickness of the dielectric film layer is Thus, a MEMS thermal-sensitive chip with film layer stress matching, chip yield approaching 100%, and thermal shock defect rate approaching 0 is prepared.

[0074] Comparative Example 1

[0075] The only difference between Comparative Example 1 and Example 1 is that the deposition temperature of the metal aluminum layer is 100° C., the metal bonding temperature between the metal aluminum layer and the substrate is 400° C., and the dielectric film layer is covered after metal etching for 24 hours.

[0076] Comparative Example 2

[0077] The only difference between Comparative Example 2 and Example 1 is that the deposition temperature of the metal aluminum layer is 400° C. and the metal bonding temperature of the covering dielectric film layer, the metal aluminum layer and the substrate after metal etching for 24 hours is 400° C.

[0078] Comparative Example 3

[0079] The only difference between Comparative Example 3 and Example 1 is that the deposition temperature of the metal aluminum layer is 100° C. and the metal bonding temperature of the covering dielectric film layer, the metal aluminum layer and the substrate within 120 minutes of metal etching is 400° C.

[0080] Comparative Example 4

[0081] The only difference between Comparative Example 4 and Example 1 is that the deposition temperature of the metal aluminum layer is 400° C. and the metal bonding temperature of the covering dielectric film layer, the metal aluminum layer and the substrate within 120 minutes of metal etching is 400° C.

[0082] First, the yield of the MEMS thermal-sensitive chips in Example 1 and Comparative Examples 1-4 was tested. Figure 4 It is a schematic bar chart of the yield test of the MEMS thermal sensitive chip in Example 1 and Comparative Examples 1-4 according to the present invention.

[0083] like Figure 4 As shown, the deposition temperature of the metal aluminum layer of the MEMS thermistor chip prepared in Example 1 is high-temperature deposition, the surface of the metal aluminum layer is pretreated, and the dielectric film layer is deposited within a preset time after the pretreatment, and the metal bonding is cancelled. The MEMS thermistor chip prepared by the above preparation method has a high product yield.

[0084] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0085] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a MEMS thermal chip, characterized in that: include: Depositing a metal aluminum layer on the surface of the substrate, wherein the deposition temperature of the metal aluminum layer is any value in the range of 300° C. to 500° C.; The surface of the metal aluminum layer is pretreated to remove the oxide film layer, and a dielectric film layer is deposited on the metal aluminum layer within a preset time after the pretreatment; wherein, The metal bonding between the metal aluminum layer and the substrate is eliminated.

2. The preparation method according to claim 1, characterized in that: The pretreatment method is dry etching.

3. The preparation method according to claim 2, characterized in that: The etching depth of the pretreatment is in the range of Any value in .

4. The preparation method according to claim 3, characterized in that: The step of depositing a metal aluminum layer on the substrate surface also includes: Depositing a first migration layer on the surface of the substrate; Depositing the metal aluminum layer on the surface of the first migration layer; A second migration layer is deposited on the surface of the metal aluminum layer, and the second anti-migration layer is partially etched to form a PAD window, wherein: The first anti-migration layer and the second anti-migration layer both include a Ti layer and a TiN layer in sequence from bottom to top, and the ratio of the thickness of the first anti-migration layer and the second anti-migration layer to the thickness of the metal aluminum layer is in a range of 0.05-0.

10.

5. The preparation method according to claim 4, characterized in that: The material of the metal aluminum layer is any one of aluminum, aluminum-copper alloy or aluminum-silicon-copper alloy.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The material of the dielectric film layer is any one of silicon oxide and silicon nitride, and the thickness of the dielectric film layer is in the range of Any value in .

7. The preparation method according to claim 6, characterized in that: The thickness of the Ti layer is in the range of The thickness of the TiN layer is in the range of Any value in .

8. The preparation method according to claim 7, characterized in that: Before the step of depositing the first anti-migration layer on the substrate surface, the method further comprises: The dielectric film layer is deposited on the substrate.

9. The preparation method according to claim 1, characterized in that: Also includes: The metal aluminum layer and the substrate are metal bonded at a temperature ranging from 300° C. to 400° C.

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