JP2011220696A - Thermal sensor element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal sensor element having little resistance value difference between the center and the end portions of a substrate to overcome a previous problem that a heat-sensitive resistance film has different resistance values at the center and the end of a substrate thereby preventing from obtaining a homogeneous element.SOLUTION: A thermal sensor element includes: a silicon base material 2 having a cavity 6 formed on a part thereof; a supporting film 3 formed on the silicon base material 2; resistance elements 4a, 4b made from a heat-sensitive resistance film 4 formed on the supporting film 3 on the top of a cavity 6; lead patterns 4c-4f and an electrode 4g made from the same materials as the resistance elements 4a, 4b and connected to the resistance elements; and means 11 for adjusting a resistance value which compensates reduction of the resistance value due to film thickness shortage of the resistance elements.

Description

The present invention relates to a thermal sensor element obtained by using a semiconductor or MEMS (Micro-Electro-Mechanical Systems) technology.
This type of thermal sensor element is used, for example, to place a fluid (gas) for measuring a flow rate in a heating resistor, and to measure the flow of the fluid by capturing a change in the resistance value. .

Hereinafter, the thermal sensor element will be described.
FIG. 7 is a structural diagram of a thermal sensor element having a general structure. FIG. 7A is a plan view showing a structure in which a thermal resistance film in which the protective film formation and the electrode opening process are omitted is exposed, and FIG. 7B is a plan view of FIG. 7A. It is sectional drawing which cut | disconnected the AA 'part shown to).

In FIG. 7, reference numeral 1 denotes a thermal sensor element. For this thermal sensor element 1, for example, a silicon substrate 2 used in a semiconductor, MEMS, or the like is used. In addition, the base material to be used has a front and back. For example, when the surface through which the fluid passes is a circuit surface, the support film 3 and the heat-sensitive resistance film 4 are formed on this surface. By patterning the heat sensitive resistive film 4, two resistors 4a, 4b, lead patterns 4c, 4d, 4e, 4f and an electrode portion 4g are formed.
Hereinafter, of the resistors, a resistor for measurement use is referred to as a fluid temperature measuring resistor 4a, and a reference resistor is referred to as a heating resistor 4b. A cavity 6 having an opening is disposed below each resistor, and a diaphragm 7 is formed inside the cavity 6. Note that the surface opposite to the circuit surface on which the cavity 6 and the diaphragm 7 are provided is referred to as a diaphragm surface. The thermal sensor element 1 described here is a device characterized by a double-sided process in which a circuit surface is provided on one side and a cavity 6 is provided on the back side. Hereinafter, description will be given in the order of FIGS.

  In this type of thermal sensor element 1, as shown in FIG. 7 (a), a support film 3 formed with the same surface area as that on the silicon substrate 2 and a patterned heat-sensitive resistance film 4 are formed on the circuit surface. In the example of FIG. 7, the fluid temperature measuring resistor portion 4 a and the heat generating resistor portion 4 b are independently configured by each resistor using the heat sensitive resistive film 4. Further, the respective lead patterns 4c, 4d, 4e, and 4f are connected to both ends of each of the resistors 4a and 4b, and heat is generated with the lead patterns 4c and 4f that are connected to the left and right of the fluid temperature measurement resistor 4a. It is distinguished by lead patterns 4d and 4e connected to the left and right of the resistor portion 4b.

  Further, a region indicated by a dotted line in the drawing shows the cavity 6 and the diaphragm 7. Two cavities 6 are provided so as to surround the heating resistor 4b and the fluid temperature measuring unit 4a. The diaphragm 7 can be obtained together with the cavity 6 by etching the diaphragm surface of the silicon substrate 2. The diaphragm 7 maintains its shape while maintaining a constant tension by controlling the stress of the film that constitutes the diaphragm 7. In addition, the dashed-dotted line which shows the A-A 'part in Fig.7 (a) has illustrated that the intermediate position of the diaphragm 6 and the cavity 7 in which the fluid temperature measurement resistance part 4a was provided is cut | disconnected.

  A trapezoidal cavity shown in FIG. 7B is a cavity 6, and a diaphragm 7 exists beyond the cavity 6. As shown in the figure, the opening of the cavity 6 on the diaphragm surface is widely provided and becomes tapered as the etching progresses. Therefore, the opening area of the diaphragm 7 is smaller than the opening area of the cavity 6. Further, the heat capacity is reduced by providing the cavity 6 below the fluid temperature measuring resistor 4a, and the heat generated in the fluid temperature measuring resistor 4a is prevented from escaping through the silicon substrate 2, thereby reducing the fluid temperature detection error. The effect to reduce can be acquired.

Next, a process flow for obtaining the thermal sensor element 1 shown in FIG. 7 will be described with reference to FIG. FIG. 8A is a plan view showing a state in which the thermal sensor element 1 is completed. In the figure, reference numeral 5 denotes a protective film, and a portion indicated by a dotted line is located below the protective film 5.
The dotted lines represent the resistors 4a and 4b made of the heat-sensitive resistive film 4, the lead patterns 4c, 4d, 4e, and 4f connected to both ends thereof and the electrode portion 4g. 4 g is exposed. The electrode portion 4g is provided for external connection with the thermal sensor element 1, and is connected to the thermal sensor element 1 by bonding a wire or the like.

  8A is illustrated so as to cut the fluid temperature measurement resistor 4a, and the alternate long and short dash line in FIG. 8A includes the electrode 4g and the electrode opening. The process flow will be sequentially described with reference to the cross-sectional structure diagram of FIG.

  Such a thermal sensor element 1 uses a planar substrate 2 that is mass-produced, easily processed, and stably supplied. For example, bare silicon normally used in a semiconductor factory or the like is used. The silicon substrate 2 used here has, for example, a wafer size of 6 inches φ, a thickness of 0.5 μm, a crystal orientation of <1,0,0>, a TTV (Total Thickness Variation) of 10 μm or less, and a resistivity of 0. The thing of the specification which is comparatively easily available with 1-100 ohm-cm is used (FIG.8 (b)-(1)). Since the thermal sensor element is a double-sided process, a silicon substrate 2 having a double-side mirror polished is used.

  A silicon nitride film which is an insulating material provided with a thickness of 1 μm, for example, is supported on the circuit surface on the silicon substrate 2 by using a method such as chemical vapor deposition (hereinafter referred to as CVD). A film 3 is formed on the entire surface of the silicon substrate 2 (FIGS. 8B to 8). Next, for example, a rare-earth platinum film having a thickness of 0.2 μm is provided on the support film 3 as a heat-sensitive resistance film 4 by a sputtering method or the like generally used in a semiconductor factory or the like. Next, resist coating, exposure, and development are sequentially performed on a necessary region of the thermal resistance film 4 by a photoengraving technique used in a semiconductor process to form a resist mask 13a (FIGS. 8B to 8C). For the heat-sensitive resistance film 4, a temperature-dependent material whose film resistance value varies with temperature is selected.

Next, an unnecessary region of the heat-sensitive resistive film 4 is removed and patterned by using a dry process or a wet process used in a semiconductor process, so that the fluid temperature measuring resistor unit 4a or B of the AA ′ cross section shown in the figure is obtained. A pattern of the heat-sensitive resistive film 4 in which the electrode part 4g of the -B 'cross section is simultaneously formed can be obtained (FIGS. 8B to 8).
At this stage, the support film 3 is exposed outside the region of the patterned thermal resistance film 4. That is, the platinum film is removed by etching, leaving the necessary shape. After patterning the heat-sensitive resistive film 4, an ashing process using a resist stripping solution or oxygen plasma is performed to remove the resist mask 13a. Further, for the purpose of improving the temperature characteristics of the heat sensitive resistance film 4, a heat treatment is performed for several hours in a high temperature environment of about 700 ° C.

Subsequently, a silicon nitride film, which is an insulating material having a thickness of 1 μm, is formed as the protective film 5 by using, for example, a CVD method in order to cover the patterned thermal resistance film 4. The patterned thermal resistance film 4 is passivated in such a manner as to be sandwiched between the protective film 5 and the support film 3 (FIGS. 8B to 8).
After the formation of the protective film 5, the portions other than the electrode portions 4g at the tips of the lead patterns 4c, 4d, 4e, and 4f are covered with a resist mask 13b. Next, the protective film 5 on the electrode portion 4g is removed by performing an etching process such as a wet or dry process, and the electrode opening 10 is provided. Further, the heat-sensitive resistive film 4 is exposed in the electrode opening 10 (FIGS. 8B to 6). Next, the resist mask 13b that has become unnecessary is subjected to an ashing process using a resist stripping solution or oxygen plasma, and then removed, thereby completing the process on the circuit surface side.

Next, a process performed on the diaphragm surface side of the silicon base material 2 will be described.
First, in order to provide the cavity 6 below the fluid temperature measuring resistor 4a, the back surface protective film 9 is formed using, for example, a silicon oxide film made of DVD having a thickness of about 0.5 μm, and the like on the back surface protective film 9 A resist mask 13c is provided in a necessary region (FIGS. 8B to 7). Next, the silicon substrate 2 is exposed by removing the back surface protective film 9 of the etched portion that hits the lower portion of the fluid temperature measurement resistance portion 4a by a wet or dry process. Further, the resist mask 13c that has become unnecessary is removed by ashing using a resist stripping solution or oxygen plasma. At this stage, the diaphragm surface under the electrode portion 4g in the BB ′ cross section is entirely covered with the back surface protective film 9 (FIGS. 8B to 8).

  Finally, the cavity 6 and the diaphragm 7 are formed using, for example, a wet process. First, the silicon substrate 2 is immersed in a bath filled with a chemical solution using an aqueous solution such as KOH (potassium hydroxide) or TMAH (tetramethylammonium hydroxide: hereinafter referred to as TMAH) or a sodium hydroxide solution. To perform anisotropic etching. This wet etching is performed by adjusting the temperature and managing the time, and by proceeding while taking measures such as removing bubbles, the silicon base material 2 has 54.74 shown in the cross section AA ′ in FIG. A cavity 6 having an inclination angle of ° is formed. The support film 3 constituting the diaphragm 7 is exposed at the end of the cavity 6, and the support film 3 functions as an etching stop, so that the diaphragm 7 having a finally required area is formed. Finally, the back surface protective film is removed by a wet or dry process to complete the process of the diaphragm surface (FIGS. 8B to 9).

  When the process of FIG. 8B is completed, a plurality of thermal sensor elements 1 are formed on the silicon substrate 2 in a regularly arranged state. In addition, a dicing cutting line having a width of, for example, 0.1 mm is provided between the thermal sensor elements 1 on the silicon base material 2 together like a partition. Hereinafter, the manufacturing process of the thermal sensor element 1 which is separated and cut from the silicon base material 2 to be the final form will be described.

  By performing separation processing by laser irradiation, such as dicer cutting using a diamond blade or stealth dicing, along the dicing cutting line of each thermal sensor element 1, the thermal sensor element 1 is as shown in FIG. It is cut out into a simple strip shape.

  The cut thermal sensor element 1 is incorporated into a holder made of, for example, resin, and fixed with an adhesive. Next, after the electrode part 4g of the thermal sensor element and the lead wire on the holder side are electrically connected using, for example, a gold wire line, the electrode part bonded with a gel coin agent or the like is covered. By completing the above steps, the thermal sensor in which the thermal sensor element 1 is mounted in the holder is completed.

Next, the detection principle of the thermal sensor will be described.
The heating resistor 4b provided in the thermal sensor element 1 is heated by passing a current through the electrode 4g and the lead patterns 4c, 4d, 4e, and 4f. When the thermal sensor element 1 is arranged on the heat generating resistor 4b so that a fluid (gas) for measuring a flow flows, the amount of heat taken away tends to increase as the flow rate increases. The thermal sensor element 2 detects this flow rate as a change in resistance value, and obtains the strength against the fluid flow. In the example of FIG. 7, the heating resistor 4b and the fluid temperature measuring resistor 4a are configured by separate resistors. Further, the heat generated by the heat generating resistor 4b is not affected by heat from the heat generating resistor 4b so that the heat generated in the heat generating resistor 4b is not adversely affected by being conducted to the fluid temperature measuring resistor 4a via the support film 3 or the silicon substrate 2. It is provided at a distance.
And since the lower part of the heating resistor 4b has a diaphragm 7 structure provided with an air space composed of the cavity 6, the silicon base material 2 is left as in the cavity 6 provided in the fluid temperature measuring resistor 4a. The advantage that the heat capacity is smaller than that in the state is obtained.

  As described above, the cavities 6 are provided at the lower portions of the heat generating resistor 4b and the fluid temperature measuring resistor 4a of the thermal sensor element, respectively. Further, the heating resistor portion 4b is arranged inside the fluid temperature measuring resistor portion 4a as shown, and the lead patterns 4c and 4f of the fluid temperature measuring resistor portion 4a are formed narrower than the lead patterns 4d and 4e of the heating resistor portion 4b. Has been. Further, since the lead patterns 4c and 4f are provided on the silicon substrate 2 having a large heat capacity, when the lead patterns 4c and 4f are narrowed, the resistance value is increased and the heat generation amount is increased. Further, if the width is narrowed, if the heat is transmitted from the outside to the lead patterns 4c and 4f, the resistance value fluctuation may increase. Therefore, the width of the lead patterns 4c and 4f may be widened or the thickness of the heat-sensitive resistive film 4 may be increased. Increase to adjust the membrane resistance.

  FIG. 9 shows an example in which the thermal sensor elements 1 are arranged and provided on the silicon substrate 2. Each frame in the silicon substrate 2 represents the thermal sensor element 1. In FIG. 9, a total of 269 thermal sensor elements 1 are designed to be collectively provided on the silicon substrate 2. In addition, the dotted line part in the silicon | silicone base material 2 edge part has shown the area | region interfered with the clamp, chuck | zipper, etc. which are used with process equipment etc. This shows an exclusion area on the premise that the thermal sensor element 1 is not disposed because it is seriously affected by damage, foreign matter adhesion, etc., and corresponds to an area of about 5 to 10 mm from the wafer edge. In addition, the numerical value shown in the frame of a figure has shown the measurement position for the resistance value investigation of the thermal type sensor element 1. FIG.

  FIG. 10 is a graph showing the in-plane film thickness and resistance value distribution of platinum, which is the heat-sensitive resistive film 4, without providing the cavity 6 on the surface of the silicon substrate 2 diaphragm. Both the platinum film thickness and the platinum resistance value shown on the Y-axis are normalized with the value of the thermal sensor element 1 (measurement positions 4 and 11 in FIG. 9) located at the center of the silicon substrate 2 being 1.0. The platinum film provided on the silicon substrate 2 is formed by sputtering, and the silicon substrate 1 provided with the support film 3 has a thickness of about 0.2 μm. Moreover, the measurement of the platinum film thickness described here is calculating | requiring a film thickness, for example using a stylus-type level difference meter. Further, the platinum resistance value in the figure is measured using a prober, and two probe needles are brought into contact with the electrode portions 4g of the lead patterns 4c and 4f shown in FIG. Seeking.

  From the measurement results, the platinum film thickness obtained by sputtering shows a tendency to become thinner from the center of the silicon substrate 2 toward the edge, and a sharp film reduction occurs particularly near the edge. In agreement with this, the resistance value of the platinum pattern near the end of the silicon substrate 2 is high, and the film thickness is in inverse proportion to the film thickness. As described above, the thermal sensor element 1 is obtained in which the resistance value of the platinum film as the heat-sensitive resistance film 4 is different even though the silicon base material 2 is the same at the center and the end and within the surface of the silicon base material 2. End up.

  Next, the sputtering principle of platinum used for the thermosensitive resistance film 4 of the thermal sensor element 1 and the cause of the film thickness distribution in the silicon substrate 2 will be described below. Sputtering is a technique in which a metal thin film is formed by colliding ionized argon atoms with a metal material called a target, and depositing the target particles ejected by the impact on the silicon substrate 2 on the opposite side. . For example, in the case of sputtering platinum, a platinum target is disposed so as to face the silicon substrate 2 in a space space called a chamber held in a vacuum. A magnet is attached to the back of the target. Next, when a set pressure is reached after introducing argon gas into the chamber, a voltage is applied between the target and the silicon substrate 2 to cause discharge. The argon gas in the chamber is ionized and collides with the target on the negative electrode side. The magnet is provided so that the plasma is confined by the lines of magnetic force so that argon ions are efficiently generated in the vicinity of the target. The argon ions colliding with platinum are given kinetic energy and are ejected from the target into the vacuum. The sputtered platinum particles leaving the target collide and scatter with argon atoms and finally deposit on the silicon substrate 2 to form a thin film.

  Advantages of this sputtering include, for example, that the film formation rate is faster than that of other film formation methods such as vapor deposition, and that the film is attached to the side wall of the concave shape such as an opening. If it mentions a fault, the sputtered particles are not selectively deposited only on the silicon substrate 2, and a corresponding film is deposited in a space other than the silicon substrate 2. End up. Furthermore, since this film is deposited and remains in the space, it becomes a dust generation source.

  Next, it is said that the film thickness distribution of the sputtered film is influenced by 1) the size of the target, 2) the distance between the silicon substrate 2 and the target, 3) the distribution of magnetic field lines, and the like. To solve this problem, for example, the position of the silicon substrate 2 immediately above the target is moved to either one so that the center of the silicon substrate 2 comes to the end of the target. That is, the silicon substrate 2 is arranged at the stage before film formation so that the semicircle side of the silicon substrate 2 overlaps the target. Next, by forming the film while rotating the silicon substrate 1, the center of the silicon substrate 1 can be made thin and the end side can be made thick. However, when the silicon substrate 1 is disposed directly under the target, the target particles can be deposited (film formation) efficiently, but this method is wasteful and causes a problem that the film formation rate cannot be increased due to the above-described reasons. End up.

  Other methods for forming the heat-sensitive resistance film 4 include, for example, a plating method and a vapor deposition method. A direct drawing method using a metal fine particle dispersion is also applicable. The metal fine particle dispersion is mainly composed of the metal fine particles 14, and is reported in detail in the literature of the Surface Technology Association Vol 59 (2008) No11, p732 (Non-patent Document 1).

  Japanese Patent Laid-Open No. 6-249693 (Patent Document 1) shows a structure in which a plurality of thermal sensor elements are provided on a silicon base material. In the manufacturing method thereof, the diaphragm surface side of the silicon base material is shown. The structure which can respond rapidly to the temperature change of the fluid is shown by the cavity effect provided.

  Further, in WO2003 / 060434 (Patent Document 2), in a thermal type sensor, wiring to a heating element and a sensor arranged on the surface of a flat substrate is performed via wiring penetrating from the front surface to the back surface of the substrate. Thus, a technique for miniaturizing a sensor is shown.

JP-A-6-249693 WO2003 / 060434

Surface Technology Association Vol 59 (2008) No11, p732

  Patent Document 1 discloses a structure in which a silicon substrate is provided with a plurality of thermal sensor elements, and a structure capable of quickly responding to a temperature change of a fluid by a cavity effect provided from the diaphragm surface side of the silicon substrate. However, there is no description regarding the film thickness distribution, resistance value distribution, film forming method, material, and the like of the thermosensitive resistance film in the silicon substrate. Further, the lead pattern dimensions and the cavity size are not described since they are not described.

  Further, in Patent Document 2, since it is a structure formed by bonding different kinds of wiring materials, it is difficult to control and manage the wiring resistance of the thermal sensor element. In addition, although the thermal sensor element can be reduced in size, the manufacturing process is increased as compared with the conventional thermal sensor element, so that the manufacturing cost is increased, the structure is complicated, and the number of assembly steps is large.

In general, a platinum film is used as the heat-sensitive resistance film of the thermal sensor element. One means for providing this platinum thin film is sputtering. However, in this method, since the film is formed on the entire surface of the silicon substrate 2, patterning for obtaining a necessary shape is performed, and thereby unnecessary regions are removed, and recovery is difficult.
The present invention has been made to solve this type of problem with a simple structure.

  Resistor consisting of a silicon substrate partially formed with a cavity, a support film formed on the silicon substrate, a heat-sensitive resistance film formed on the support film above the cavity, and the same material as the resistor Film resistance value required as a heat-sensitive resistance film, comprising a lead pattern and an electrode portion formed in the above and a resistance value adjusting means for compensating for a decrease in resistance value due to insufficient film thickness of the resistor It is characterized by having obtained.

  According to the present invention, a silicon base material partially formed with a cavity, a support film formed on the silicon base material, a resistor composed of a heat-sensitive resistance film formed on the support film above the cavity, A heat sensitive resistive film comprising a lead pattern and an electrode portion formed of the same material as the resistor and connected to the resistor, and a resistance value adjusting means for compensating for a decrease in resistance value due to insufficient film thickness of the resistor As a result, the reliability of the thermal sensor element is improved. In particular, with respect to the thermal sensor element at the end of the silicon base material 2, the resistance distribution of the thermosensitive resistance film provided in the silicon base material is improved by compensating for the insufficient film thickness. It is possible to eliminate variations in the silicon substrate due to temperature characteristics.

FIG. 1A is a structural plan view of a thermal sensor element in which a resistance adjustment film is provided on the lead pattern under the protective film in the first embodiment of the present invention, and FIG. 1B is a diagram of A in FIG. It is the cross-section figure which cut | disconnected -A 'part. It is a process flowchart which shows an example of the drawing patterned by the inkjet method using a metal fine particle dispersion. FIG. 3A is a structural plan view of a thermal sensor element in which an opening reaching the lead pattern is provided on the protective film in the second embodiment of the present invention, and a resistance adjusting film is formed in the opening. FIG. 3B is a cross-sectional structure diagram taken along the line AA ′ of FIG. FIG. 4 is a cross-sectional structure process flow diagram of a thermal sensor element obtained by cutting a B-B ′ portion in FIG. FIG. 5 is a structural cross-sectional view of a thermal sensor element taken along the line B-B ′ of FIG. 3A showing the structure in Embodiment 3 of the present invention in which metal fine particles are applied to a resistance adjusting film. In the second embodiment of the present invention, an opening reaching the lead pattern is provided on the protective film, and the resistance value change in the silicon substrate including the thermal sensor element in which the resistance adjusting film is applied to the opening is measured. FIG. FIG. 7A is a structural plan view of a general thermal sensor element, and FIG. 7B is a cross-sectional structural view taken along the line A-A ′ of FIG. 8A is a structural plan view of a general thermal sensor element shown with a part cut away, and FIG. 8B is a cross-sectional view taken along lines AA ′ and BB ′ of FIG. 8A. It is a process flow figure of a thermal type sensor element sectional structure shown. It is a top view of the silicon base material which shows the layout of a thermal sensor element, and the measurement position of the thermal sensor element by which resistance value measurement is carried out. It is a graph which shows the film thickness distribution and resistance value distribution in the silicon base material of a general thermal type sensor element.

Embodiment 1 FIG.
The first embodiment of the present invention will be described below with reference to the thermal sensor element plan view of FIG.
First, FIG. 1A is a plan view showing the structure of the thermal sensor element 1 cut out from the silicon substrate 2. The thermal sensor element 1 has a quadrangular shape as shown in the figure, and the long side is cut into a strip shape having a length twice or more than the short side. For example, in Embodiment 1 of the present invention, a thermal sensor element having a long side of 12 mm and a short side of 3 mm is obtained using a bare silicon wafer having a thickness of 0.4 μm.

  Hereinafter, the thermal sensor element 1 shown in FIG. The protective film 5 is made of a silicon nitride film having a thickness of 1 μm, and is provided so as to cover the entire thermal sensor element 1 excluding the electrode portion 4 g and the electrode opening 10. In the figure, everything provided below the protective film 5 is indicated by a dotted line. The thermosensitive resistance film 4 forms each resistor of the fluid temperature measuring unit 4a and the heating resistor unit 4b. Lead patterns 4c, 4d, 4e, 4f, and an electrode portion 4g are formed of the same material as the heat-sensitive resistive film 4, and the electrode portion 4g is connected to the outside through the electrode opening 10. . A resistance adjusting film 11 is provided on each of the lead patterns 4c, 4d, 4e, and 4f.

  As shown in FIG. 1B, a support film 3 made of a silicon nitride film is formed below the heat-sensitive resistance film 4. A cavity 6 is provided below the support film 3. The cavity 6 is processed from the diaphragm surface side of the silicon substrate 2 to obtain a rectangular space as shown in the figure. A diaphragm 7 is provided in the cavity 6. The diaphragm 7 includes a support film 3, resistors 4 a and 4 b of the thermosensitive resistance film 4, and a protective film 5.

  The difference from FIG. 7A shown as a general structure in FIG. 1A is that a resistance adjusting film 11 is newly provided on the lead patterns 4c, 4d, 4e, and 4f. . The resistance adjusting film 11 is formed for the purpose of compensating for the insufficient film thickness of the heat sensitive resistance film 4, thereby improving the resistance value of the heat sensitive resistance film 4.

  FIG. 1B is a sectional structural view obtained by cutting the A-A ′ portion shown in FIG. In order to obtain this cross-sectional structure, first, a support film 3 having a thickness of 1 μm is provided on the circuit surface on the silicon substrate 2. Note that a silicon nitride film was used as the support film 3. Subsequently, after forming the heat-sensitive resistance film 4 on the support film 3, a resist mask 13 is formed. Next, the extra region is removed by physical etching, and the resist mask 13 is removed by an ashing apparatus into which oxygen has been introduced. Next, a resistance adjusting film 11 is provided on the patterned heat-sensitive resistance film 4. A protective film 5 is formed to passivate the heat-sensitive resistance film 4 including the resistance adjusting film 11. After the formation of the protective film 5, all regions except the electrode portion 4 g are covered with a resist mask 13, and the protective film 5 is removed by physical etching at an angle of 30 degrees to form an electrode opening 10. After the electrode opening 10 is formed, the resist mask 13 is ashed and removed to complete the process on the circuit surface side.

  Next, the process on the diaphragm surface side will be described. In order to form the cavity 6 below the resistors 4a and 4b of the heat-sensitive resistive film 4 on the circuit surface side, a back surface protective film 9 is formed. A silicon oxide film having a thickness of 0.5 μm is used for the back surface protective film 9 by sputtering. Next, a resist mask 13 for forming openings under the resistors 4a and 4b is formed. Next, the back surface protective film 9 is removed at room temperature by immersing the silicon substrate 2 together in a bath containing a BHF (buffered hydrofluoric acid) solution. In order to prevent the circuit surface from being damaged in this BHF processing, it is preferable to proceed the processing after protecting the circuit surface with a chemical-resistant tape or the like so that the chemical solution does not enter the circuit surface.

  In the region where the back surface protective film 9 is etched, silicon is exposed, and the resist mask 13 that is no longer needed is removed by ashing. Next, the process of providing the cavity 6 is performed by wet etching using a TMAH aqueous solution. The back surface protective film 9 must be a material resistant to the TMAH aqueous solution. In addition, it is desirable to proceed the process after protecting the chemical from entering the circuit surface as in the case of the BHF process. Since wet etching is performed with anisotropy with respect to the silicon surface, an inclination is provided as in the shape of the cavity 6 in FIG. The plane orientation of the inclined portion side wall is <1,1,1>, and the obtained inclination is formed at an angle of 54.75. In addition, wet etching is performed in a bath in which an aqueous solution is heated, and the support film 3 appears on the bottom surface of the cavity 6 provided on the diaphragm surface at a bath temperature of 75 ° C. for about 8 to 10 hours.

  Next, when the required size of the diaphragm 7 is obtained, the silicon base material 2 is taken out from the bath containing the chemical solution, and washed and dried. Finally, the thermal protection sensor element according to the first embodiment of the present invention is obtained by removing the back surface protective film 9 which is no longer necessary due to BHF.

Next, a method for providing the resistance adjusting film 11 will be described in detail.
First, a silicon nitride film having a thickness of about 0.5 μm as a protective film 5 is formed on the patterned heat-sensitive resistance film 4 by a plasma CVD method. Next, the resist mask 13 covers the regions other than the region where the resistance adjusting film 11 of the lead patterns 4c, 4d, 4e, and 4f is formed. A dry etching process is performed in a vacuum chamber in which the silicon nitride films of the exposed lead patterns 4c, 4d, 4e, and 4f are discharged with a mixed gas of carbon tetrafluoride (CF ₄ ) and oxygen, and lead patterns 4c, 4d, 4e, An opening 8 for providing the resistance adjusting film 11 is formed on 4f.

  The resist mask 13 that is no longer needed is removed by ashing and stripping solution, and a metal fine particle dispersion liquid of platinum metal fine particles is discharged into the opening of the resistance adjusting film 11. The metal fine particle dispersion is a solution containing the metal fine particles 14 that are independently dispersed without being aggregated in a solvent by covering the surface of the metal fine particles 14 having a diameter of the order of several nanometers with an organic substance. Next, the organic substance is volatilized by heating at about 300 ° C. in a baking furnace or the like, and then a silicon nitride film having a thickness of 0.5 μm as the protective film 5 is provided to cover the metal fine particles 14, thereby adjusting the resistance adjusting film 11. The process up to the protective film 5 including is completed. In this method, it is necessary to divide the protective film 5 into two parts.

  As another method of providing the resistance adjusting film 11 with the metal fine particles 14, there is a forming method by an ink jet method. In this method, the inkjet nozzle 15 containing the platinum metal fine particles 14 is moved onto the lead patterns 4c, 4d, 4e, and 4f and discharged directly to a necessary region. For example, a silicon substrate on which the thermal resistance film 4 is patterned is used. The material 2 is fixed on a stage or the like, and the inkjet nozzle 15 is moved to a position where it is desired to be discharged. Next, a required amount of the metal fine particle dispersion is discharged onto the lead patterns 4c, 4d, 4e, and 4f, and heat treatment is performed at 200 to 300 degrees to volatilize the organic matter. If the lead patterns 4c, 4d, 4e, and 4f provided with the resistance adjusting film 11 are covered with the protective film 5, the resistance adjusting film 11 can be formed without stacking the protective films 5 in two layers. .

  In addition, a thickness corresponding to the resistance adjustment film 11 is provided in advance on the thermal resistance film 4, and the lead patterns 4c, 4d, 4e, and 4f provided on the thermal sensor element 1 are covered with the resist mask 13 and then physically. A method of removing the excess thermal resistance film 4 by etching is also conceivable, but in this case, there is a problem in the controllability of the film thickness of the thermal resistance film 4 remaining after the etching because the etching rate and the etching distribution of the physical etching are large. Not suitable for.

  In Embodiment 1 of the present invention, a thermal sensor element having a long side of 12 mm and a short side of 3 mm is obtained using a bare silicon wafer having a thickness of 0.4 μm. However, the present invention is not limited to this. You may use what was thinned by grinding | polishing etc. to thickness of 0.2 micrometer. Further, regarding the base material 2, it is desirable to use a silicon wafer because it is more stably supplied, and it is possible to use a thermal oxide film provided on both sides or one side.

In addition, physical etching is used for etching the protective film 5, but dry etching treated with a mixed gas of carbon tetrafluoride (CF ₄ ) or trifluoromethane (CHF ₃ ) and oxygen may be used. Further, although the BHF treatment is used for removing the back surface protective film 9, it may be removed by the physical etching or the dry process.

  In the first embodiment of the present invention, a silicon nitride film made of plasma CVD is used for the support film 3 and the protective film 5, but the present invention is not limited to this, and other materials such as SOG (Spin on Glass) are used. An insulating material containing silicon in a composition ratio such as an oxide film, silicon oxide containing TEOS (tetraethoxysilane), aluminum oxide, or SiON may be selected, or a combination of these may be provided. In addition to plasma CVD, the film forming method may be reduced pressure, normal pressure CVD, or reactive sputtering. Also in the case of film thickness, the support film 3 may be provided to be thinner than 1 μm, and the protective film 5 only needs to have a necessary film thickness for passivating the thermal resistor 4. However, when the diaphragm 7 is formed, it is necessary to control the stress with a balance with the film quality so as not to be distorted or bent.

  Since the back surface protection film 9 needs to protect the diaphragm surface from being attacked by a chemical solution such as a TMAH aqueous solution, a certain thickness is required. In the first embodiment of the present invention, a silicon oxide film having a thickness of 0.5 μm is used, but the same effect can be obtained even if the silicon oxide film is further thickened by about 0.5 μm. Further, as the film type, the materials described in the support film 3 and the protective film 5 may be selected.

  Moreover, although the TMAH aqueous solution was used in the diaphragm 7 forming step, an additive may be mixed with the TMAH aqueous solution to improve the etching rate. The temperature and processing time are not limited to these, and the required diaphragm 7 size may be provided in the cavity 6, and the KOH (potassium hydroxide) aqueous solution may be selected as the chemical solution.

  Next, as an example of using the metal fine particles 14, a drawing process on the silicon substrate 2 by an ink jet method is shown in FIG. For example, as shown in (A), a regularly arranged frame is provided on the silicon substrate 2. On the other hand, for example, a metal fine particle dispersion 14 containing platinum nano metal fine particles 14 is filled in the inkjet nozzle 15 for each frame. Next, the metal fine particle dispersion 14 is discharged while moving the inkjet nozzle 15 (B). Next, an unnecessary organic solvent is removed by drying at 100 ° C. in an oven or the like. Further, the firing step is performed at 200 to 300 ° C. As a result, the required metal thin film pattern can be easily formed without a step such as photolithography (C).

  Furthermore, since there is no need to provide the resistance adjusting film 11 until the surface of the protective film 5, there is no fear of disconnection. Further, since there is no need to pattern and etch the thermosensitive resistive film 4 with a resist mask as in the prior art, a rare metal material or the like can be used effectively. In sputtering, the film is attached to every area in the space where the target particles are held in vacuum, which is wasteful. However, in the case of the ink jet method, an extra film is attached only by discharging the required amount to the opening 8. Thus, it is possible to reduce the number of processes and to reduce the number of facilities used for patterning the heat-sensitive resistive film 4.

  In the first embodiment of the present invention, the resistance value for compensating for the decrease in resistance value caused by the insufficient film thickness of the thermal resistance film 4 in the region where the lead patterns 4c, 4d, 4e, and 4f are formed as compared with the conventional example. The adjustment means includes a resistance adjusting film 11, the lead patterns 4c, 4d, 4e, and 4f and the resistance adjusting film 11 are collectively passivated, and the protective film 5 is divided and formed. It has become.

Embodiment 2. FIG.
FIG. 3 is a diagram showing a thermal sensor obtained in Embodiment 2 of the present invention. FIG. 3 (a) is a structural plan view showing a state of being cut out from the silicon substrate 2, and FIG. The cross-section figure at the time of cutting out the site | part of AA 'of Fig.3 (a) is shown.
FIG. 3A shows a structure obtained by cutting and separating the thermal sensor element 1 provided on the silicon substrate 2 with a dicer, and using a bare silicon wafer having a thickness of 0.4 μm. A thermal sensor element 1 having a long side of 12 mm and a short side of 3 mm is obtained.

  A silicon nitride film obtained by plasma CVD with a thickness of 1 μm for passivating the heat-sensitive resistive film 4, lead patterns 4 c, 4 d, 4 e, 4 f, and electrode part 4 g is provided on the outermost layer of the circuit part surface of the thermal sensor element 1. The protective film 5 is provided. The dotted line portion in the figure indicates the lead patterns 4c, 4d, 4e, and 4f provided under the protective film 5, the heat-sensitive resistance film 4, and the cavity 6 and the diaphragm 7 below the support film 3. This protective film 5 is provided with two types of openings.

  First, the first opening 8 is an opening provided on the lead patterns 4c, 4d, 4e, and 4f. The opening 8 is provided in the area of the lead patterns 4c, 4d, 4e, and 4f excluding the diaphragm 7 area where the cavity 6 is formed. Further, it is rectangular as shown in the figure, and one side is formed with a dimension shorter than the length from the end of the cavity 6 to the electrode opening 10, and the other side does not interfere with the lead patterns 4c, 4d, 4e, and 4f. Provided in the region. In the second embodiment of the present invention, the lead patterns 4c, 4d, 4e, and 4f are provided with dimensions smaller than the width.

  A thermal resistance film 4 made of platinum having a thickness of 0.2 μm appears on the bottom surface of the opening 8 by sputtering, and a resistance adjusting film 11 is formed in a state of being connected thereto. Further, the opening 8 and the resistance adjusting film 11 are provided at both the input / output of the fluid temperature measuring resistor 4a and the input / output of the heating resistor 4b in the thermal sensor element 1, and a total of four openings are provided.

  In addition, the electrode opening 10 at the tip of the lead pattern 4c, 4d, 4e, 4f, which is the other opening, is provided in a quadrilateral shape of 400 × 400 μm square, for example, for connection to the outside by wire bonding or the like. ing. The electrode opening 10 is designed to be opened in advance so as to be able to cope with, for example, a positional deviation caused by wire bonding.

Next, the cross-sectional structure of the alternate long and short dash line portion between AA ′ in FIG. 3A will be described with reference to FIG. As shown in the drawing, cavities 6 are respectively provided on the diaphragm surface of the silicon base material 2 which is the base material of the thermal sensor element 1 in order to reduce the heat capacity of the fluid temperature measurement resistor 4a and the heating resistor 4b. A diaphragm 7 is formed on the bottom surface.
A support film 3 made of a silicon nitride film formed by a plasma CVD method is provided on the circuit portion side of the silicon base 2 with a thickness of 1 μm. This film is used to play a role of giving a certain tension to the diaphragm by stress control and a stopper layer for providing the two cavities 6. On top of this, there is a heat-sensitive resistance film 4 made of platinum obtained by patterning. A protective film 5 is provided on the heat-sensitive resistance film 4, and the diaphragm 7 is formed by stress control obtained by combining three layers of the heat-sensitive resistance film 4 sandwiched between the support film 3 and the protective film 5.

  Among the openings provided in the protective film 5, the electrode portion 4 g is provided on the bottom surface of the electrode opening 10, and the lead patterns 4 c, 4 d, 4 e, and 4 f are exposed on the bottom surface of the opening 8. The openings 8 on the lead patterns 4c, 4d, 4e, and 4f are formed on the premise that the resistance adjustment film 11 is provided on the protective film 5, and therefore, the resistance adjustment film 11 is inclined so as not to be disconnected. It is necessary to provide it.

  Next, the opening 8 and the resistance adjusting film 11 obtained in the second embodiment of the present invention will be described with reference to the manufacturing process flow chart of FIG. FIG. 4 is an example of a cross-sectional structure of the thermal sensor element 1 obtained by cutting the B-B ′ portion shown in FIG. In addition, since the formation method of the support film 3, the thermosensitive resistance film 4, and the protective film 5 provided on the silicon substrate 2 is the same as the process flow described in the example of FIGS. 7 and 8, the description thereof is omitted here. (FIG. 4 (1)-(5)).

  FIG. 4 (6) shows a structural cross-sectional view in which an opening 8 is provided after the lead patterns 4 c, 4 d, 4 e, and 4 f made of the thermosensitive resistance film 4 are covered with the protective film 5. Hereinafter, the process flow will be described. In order to obtain this structure, first, a resist mask 13 is provided on the protective film 5, and dry etching is performed by physical etching to form the opening 8. The physical etching used here is an etching technique capable of giving an opening an arbitrary inclination angle, and the inclination angle refers to an angle based on the bottom surface of the opening 8. In the second embodiment of the present invention, the inclination obtained on the side wall of the opening 8 is processed at 45 degrees. Next, by removing the resist mask 13 that is no longer needed, the cross-sectional structure of FIG.

  Next, FIG. 4 (7) is a cross-sectional structure diagram in which the film of the resistance adjusting film 11 is formed on the entire surface of the silicon substrate 2 provided with the openings 8. In the second embodiment of the present invention, a platinum film having a thickness of 50 nm is formed as the resistance adjusting film 11 by sputtering.

  In FIG. 4 (8), a resist mask 13 is formed so as to cover the periphery of the required resistance adjustment film 11 around the opening 8 on the lead patterns 4c, 4d, 4e, and 4f. For example, the resist mask 13 is applied to the entire surface of the silicon substrate 2 and then processed using a full-surface irradiation exposure facility including a mask aligner, and then development is performed to form a pattern having a cross-sectional shape as illustrated. The resist mask 13 has a thickness of about 2 μm.

  Next, in FIG. 4 (9), the unnecessary thermal sensitive film 4 is removed and patterned by physical etching, and the resist mask 13 that is no longer needed is removed to form the lead patterns 4c, 4d, 4e, and 4f. The thermal sensor element 1 including the opening 8 and the resistance adjusting film 11 can be obtained.

  In the second embodiment of the present invention, in order to obtain an inclination in the opening 8, the electrode opening 10 is also provided with an inclination of the same angle. This is because the openings 8 and the electrode openings 10 of the lead patterns 4c, 4d, 4e, and 4f are collectively processed, and the function itself is not provided. As far as the inclination is concerned, it may be processed in a state close to vertical. However, the process reduction effect can be obtained by batch processing. Further, although the thickness of the resistance adjustment film 11 is 50 nm, the resistance adjustment film 11 is provided as a resistance value adjusting means, and therefore it is necessary to determine the film thickness in accordance with a required resistance value. .

  Further, although a bare silicon wafer having a thickness of 0.4 μm is used for the silicon substrate 2, a silicon wafer with a thermal oxide film may be used in addition to bare silicon. Further, the thickness of the silicon base material is not limited to this, and it is premised that the strength of the base material 2 is not lowered. However, by reducing the thickness of the silicon base material, it is possible to shorten the cavity formation time of the diaphragm surface.

The opening 8 is provided in the region of the lead patterns 4c, 4d, 4e, and 4f excluding the region where the cavity 6 is formed. Specifically, in the case of the heating resistor 4b, the region from the end of the cavity 6 to the electrode opening 10 of the illustrated heating resistor 4b is desirable. In the fluid temperature measuring resistor 4a, the fluid temperature measuring resistor 4a It is desirable to form in a region from the end of the cavity 6 to the electrode opening 10.
If the opening 8 is provided directly above the diaphragm 7 or straddling the diaphragm 7, the strength problem of the diaphragm 7 or the stress balance may be lost, and components such as bending may be added, making stress control difficult. Therefore, the portions of the lead patterns 4c, 4d, 4e, and 4f where the silicon base material 2 remains are suitable.

  The opening 8 has a quadrangular shape as shown in the figure, and one side is provided shorter than the length reaching the end electrode opening 10 of the diaphragm 6, and the other side is the lead pattern 4c, 4d, 4e, 4f. It is desirable that the length is formed so as not to interfere with each other.

Further, there is an empty space in which the support film 3 is exposed between 4c and 4d and between 4e and 4f shown in FIG. 3A, and the resistance adjusting film 11 may be provided so as to overlap therewith. There are also empty spaces (left and right empty spaces where the cavities 7 of the fluid temperature resistance measuring unit 4a are located) between 4c and 4f and the cavity 6 of the fluid temperature resistance measuring unit 4a, and the resistance adjusting film 11 overlaps with this. May be provided. Further, the empty space in the cavity 7 between the cavity 7 of the fluid temperature resistance measuring unit 4a and the heating resistor 4b is the same.
In FIG. 3A, the size of the opening 8 is different between the lead patterns 4c and 4f and the lead patterns 4d and 4e. However, the size is not limited to this, and the section (cutting) of the thermal sensor element 1 is not limited thereto. Surface 8) and diaphragm 7 may be provided with the same shape so as not to overlap.

  Further, the resistance adjusting film 11 is provided in a state of remaining on the protective film 5 as shown in FIG. This is because it is difficult to provide the resist mask 13 on the inclined portion of the side wall of the opening 8, so that a V shape having a ridge as shown in FIG. 3B is obtained. Note that it is necessary to dispose the opening 8 so that the wrinkles of the resistance adjusting films 11 do not overlap each other as a precaution when providing the wrinkles. Moreover, it is necessary to prevent the cavity 6 from being wrinkled.

As another example of the etching for forming the opening 8, for example, a method of performing dry etching with a mixed gas of trifluoromethane (CHF ₃ ) or CF ₄ (carbon tetrafluoride) and O ₂ (oxygen) may be used. Although it is good, the finish of the inclined portion on the side wall of the opening 8 becomes steep compared to the method described above.

Further, the inclined portion provided on the side wall of the opening 8 is provided with an inclination such that the opening surface expands toward the upper portion with the bottom surface of the opening 8 as a reference. This is determined by physical etching for forming the opening 8 on the protective film 5, and can be processed, for example, perpendicularly (90 degrees) to the bottom surface of the opening 8. However, there is a risk that the wrinkles of the resistance adjusting film 11 may be disconnected. In addition, when the inclination of the opening 8 is 60 degrees or more, the resistance adjustment film 11 is not properly attached to the inclination.
Furthermore, when the inclination of the opening 8 is inclined from 0 to 29 degrees, the resist mask 13 on the protective film 5 becomes an obstacle, and the finished cross-sectional shape is affected.

  Therefore, it is desirable that the side wall portion of the opening 8 provided in Embodiment 2 of the present invention is formed with an inclination of 30 to 60 degrees. Furthermore, since re-adhesion due to physical etching remains at the tip of the opening 8, as a method for removing this, for example, physical etching at a tilt angle of 0 degrees, removal by BHF treatment or ultrasonic cleaning, etc. Is desirable.

  Further, in Embodiment 2 of the present invention, platinum is used for the resistance adjusting film 11, but is not limited thereto, and any one of platinum, nickel, an alloy containing nickel, cobalt, gold, silver, and copper is used. The resistance value of the heat-sensitive resistive film 4 may be adjusted using one kind.

Embodiment 3 FIG.
FIG. 5 is a cross-sectional view showing a structure according to Embodiment 3 of the present invention. In the third embodiment, the thermal sensor element 1 in which the resistance adjusting film 11 is formed by discharging and baking the metal fine particles 14 into the openings 8 on the lead patterns 4c, 4d, 4e, and 4f is obtained. First, the metal fine particle dispersion is formed by an ink jet method using a printer. The organic solvent is evaporated and dried after being discharged into the opening 8 by the ink jet nozzle 15, and the resistance adjusting film 11 is provided by completing the heat treatment process at 250 degrees. Since the process flow up to the formation of the opening 8 is the same as that of the second embodiment, the description thereof is omitted.

  This cross-sectional structure is necessary by moving the ink jet nozzle 15 filled with the metal fine particle dispersion to the openings 8 on the lead patterns 4c, 4d, 4e, and 4f shown in FIG. It is characterized in that the resistance adjusting film 11 is obtained.

Further, the resistance adjusting film 11 which is the metal fine particle 14 is in direct contact with the heat-sensitive resistance film 4 and the same material selection as that of the heat-sensitive resistance film 4 is preferable, but another metal fine particle dispersion 15 such as gold or copper. May be used to control the resistance of the heat-sensitive resistive film 4. Further, the opening 8 on the resistance adjusting film 11 may be protected by using SOG, a silicon oxide film, a silicon nitride film, or the like.
Further, the thermal sensor element is bonded with a gold wire wire through the electrode portion 9 and is electrically connected. The gel coin used for covering the electrode portion 9 is made of the opening portion 8 and the resistance adjusting film. 11 may be applied so as to surround them.

  In the third embodiment of the present invention, the opening 8 is provided in the lead patterns 4c, 4d, 4e, and 4f, and the resistance value adjustment for compensating for the decrease in the resistance value due to the insufficient film thickness of the thermal resistance film 4 is provided thereon. As a means, the film thickness of the heat-sensitive resistance film 4 required by the thermal sensor element 1 of the silicon substrate 2 can be reduced with the metal fine particles 14 because the resistance adjusting film 11 is provided or the opening 8 is exposed. The feature is that it can be adjusted freely.

  In the first embodiment of the present invention, the resistance adjusting film 11 on the lead patterns 4c, 4d, 4e, and 4f is covered with the protective film 5. However, the opening 8 is provided so that the resistance adjusting film 11 is provided. In the structure of the second embodiment or the third embodiment to be formed, even if the resistance values of the lead patterns 4c, 4d, 4e, and 4f provided with the resistance adjusting film 11 do not reach the specified value, additional resistance adjustment is performed. It is also possible to provide a film thickness that is insufficient for the film 11.

  Next, FIG. 6 shows an in-plane distribution result of the thermal resistance film thickness and the resistance value on the silicon substrate 2 experimentally manufactured using the second embodiment of the present invention. In addition, since the measurement position in the figure is the same as the position shown in FIG. 9, description here is abbreviate | omitted. FIG. 6 is a graph of the thermal resistance 4 film thickness in the silicon substrate 2 and the resistance value of the patterned thermal resistance film 4 at each measurement position. The solid line in the figure shows the initial value in which the resistance adjusting film 11 is not provided in the opening 8, and the dotted line of the silicon substrate 2 in which the thermal sensor elements in which the opening 8 is provided to form the resistance adjusting film 11 are arranged. It is a resistance measurement result.

  In addition, the platinum film which is the same material was provided in the heat sensitive resistive film 4 and the resistance adjustment film | membrane 11 by sputtering. The resistance adjusting film 11 was applied to the thermal sensor element 1 at the measurement position (1, 7, 8, 14). As shown in FIG. 9, a thermal sensor element having a resistance adjusting film 11 (in FIG. 9) provided with a resistance adjusting film 11 with respect to a general structure having no resistance adjusting film 11 (shown by a solid line in FIG. 9). (Indicated by a broken line in Fig. 5), there was little variation in the resistance value, and the resistance value was improved. Thereby, it was confirmed that the resistance adjusting film 11 contributed to the resistance value of the entire thermosensitive resistance film.

  Further, when platinum metal fine particles 14 are used for the resistance adjusting film 11 of FIG. 5, several cc of the metal fine particle dispersion of the ink jet nozzle 15 is discharged to the opening 8 and dried on a hot plate at 100 ° C. To remove organic matter. Next, even when heat treatment was further performed at a temperature of 250 ° C. for about 30 minutes and the finished resistance adjusting film 11 having a thickness equivalent to 100 nm was applied, the resistance value of the thermosensitive resistance film 4 was improved.

  As described above, according to the present invention, the region where the lead pattern is formed is provided with the resistance value adjusting means for compensating for the decrease in the resistance value due to the insufficient film thickness of the resistor, and is necessary as a heat-sensitive resistance film. By obtaining an appropriate film resistance value, the reliability of the thermal sensor element is improved. In particular, for the thermal sensor element at the edge of the silicon substrate, the temperature distribution of the thermal sensor element is improved by compensating for the insufficient film thickness and improving the resistance distribution of the thermal resistance film provided in the silicon substrate. It becomes possible to eliminate variations in the silicon substrate due to the characteristics.

Further, a protective film formed on the support film and protecting the resistor and the lead pattern is further provided, and the resistance value adjusting means provides an opening reaching the lead pattern on the protective film, and the resistance adjustment is performed on the opening. As the opening is exposed without being covered with the protective film, the width of resistance adjustment including redo is widened, and the resistance value of the thermal resistance film is adjusted. The effect which becomes easy is acquired.

  Furthermore, the opening has a quadrangular shape, one side of which is shorter than the length from the end of the cavity to the opening of the electrode, and the other side has a length that does not interfere with each other on the lead pattern. By being provided on the lead pattern excluding the region where the cavity is formed, there is no influence of film stress on the diaphragm, and the effect of easily adjusting the resistance of the thermosensitive resistance film can be obtained.

  Also. The side wall of the opening is inclined so that the opening surface expands from the bottom of the opening toward the top, and is inclined at an angle of 30 to 60 degrees with respect to the bottom of the opening. Thus, the effect of preventing disconnection of the resistance adjusting film 11 can be obtained, so that the reliability of the thermal sensor element can be improved.

  In addition, by using metal fine particles contained in a metal fine particle dispersion or the like for the resistance adjustment film, compared to a technique in which an unnecessary film is removed by etching or the like as in conventional sputtering to obtain a heat-sensitive resistance film, Equipment such as photoengraving, physical etching, and ashing using a resist mask is not necessary. Further, rare metal material can be used effectively because physical etching for obtaining a necessary shape like platinum sputtering is unnecessary. In addition, since the metal fine particle dispersion is directly discharged to a necessary area in the ink jet method, it is not necessary to perform evacuation or rate check that is performed at the time of sputtering, thereby improving the processing capability.

  DESCRIPTION OF SYMBOLS 1 Thermal type sensor element, 2 Silicon base material, 3 Support film, 4 Thermal resistance film, 4a Fluid temperature measurement resistance part, 4b Heat generation resistance part, 4c, 4d, 4e, 4f Lead pattern, 4g Electrode part, 5 Protective film, 6 Cavity, 7 Diaphragm, 8 Opening, 9 Back Protective Film, 10 Electrode Opening, 11 Resistance Adjusting Film, 13 Resist Mask, 14 Metal Fine Particles, 15 Inkjet Nozzle.

Claims (10)

  A silicon substrate having a cavity formed in part, a support film formed on the silicon substrate, a resistor composed of a heat-sensitive resistance film formed on the support film above the cavity, and the resistor A heat pattern comprising lead patterns and electrode portions formed of the same material and connected to the resistor, and resistance value adjusting means for compensating for a decrease in resistance value due to insufficient film thickness of the resistor. Type sensor element.   The protective film further includes a protective film that is formed on the support film and protects the resistor and the lead pattern, and the resistance value adjusting unit includes an opening that reaches the lead pattern in the protective film. The thermal sensor element according to claim 1, wherein a resistance adjusting film is formed.   The thermal sensor element according to claim 1, wherein the opening is provided in an area of the lead pattern excluding an area where the cavity is formed.   The opening has a quadrangular shape, one side is shorter than the length from the end of the cavity to the opening of the electrode part, and the other side has a length that does not interfere with each other on the lead pattern. The thermal sensor element according to claim 2 or 3.   The side wall of the opening is provided with an inclination so that the opening surface expands from the bottom surface to the top of the opening. Thermal sensor element.   6. The thermal sensor element according to claim 5, wherein the side wall of the opening is inclined at an angle of 30 to 60 degrees with respect to the bottom surface of the opening.   The thermal sensor element according to any one of claims 2 to 6, wherein the resistance adjusting film is made of any one of platinum, nickel, an alloy containing nickel, cobalt, gold, silver, and copper.   8. The thermal sensor element according to claim 7, wherein the resistance adjusting film is provided with metal fine particles contained in a metal fine particle dispersion or the like.   The thermal sensor element according to any one of claims 2 to 8, wherein the resistor and the resistance adjusting film are made of the same material.   The resistor is heated by passing a current through the electrode part and the lead pattern, and the flow rate of the fluid to be measured is measured based on an amount of heat released from the resistor by the fluid to be measured. The thermal sensor element according to any one of claims 1 to 9.

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