JP2010139376A - Pressure detecting element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pressure detecting element using a Si semiconductor substrate equipped with a pressure-sensitive resistor and a temperature-sensitive resistor wherein the resistor and a wiring layer are properly connected through a contact hole and a reliable wiring layer is formed. <P>SOLUTION: The pressure detecting element 100 has the Si semiconductor substrate including the pressure-sensing resistor 113 and the temperature-sensitive resistor 114, an insulating layer in which contact holes 115C, 115D are bored, and a wiring layer 116 connected to upper surfaces 113U, 114U of the resistors. The insulating layer has a multi-step shape wherein the wiring layer forming part 115CW has a plurality of slope sections 115CS1, 115CS2 and a planar section 115CP positioned between the two adjacent slope sections. The thickness Th of the wiring layer is smaller than 1.2 times the total step height Dz, of the insulating layer and greater than 1.2 times the step heights Ds1, Ds2 formed in the respective slope sections 115CS1, 115CS2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pressure detection element capable of detecting a pressure such as an in-cylinder pressure of an internal combustion engine, and more particularly to a pressure detection element including a Si semiconductor substrate having a pressure-sensitive resistor having pressure-sensitive characteristics.

  2. Description of the Related Art Conventionally, as a pressure detection element capable of detecting a pressure such as an in-cylinder pressure of an internal combustion engine, a pressure detection element having a Si semiconductor substrate that detects a change in stress caused by the pressure using a piezoresistance effect is known. Yes. For example, Patent Document 1 discloses such a pressure detection element.

  The force conversion element (pressure detection element) of Patent Document 1 is provided with a piezoresistor (23: pressure sensitive resistor) and insulation on a plate-like Si semiconductor substrate (support substrate (17), etc.) that detects the pressure to be detected. A piezoresistive negative electrode (21: wiring layer) and a piezoresistive positive electrode (22: wiring layer) are provided through contact holes (36a, 36b) drilled in the insulating film (18). And piezoresistor (23) (see FIGS. 4 and 9 of Patent Document 1).

JP 2003-136494 A

As can be easily understood with reference to FIG. 4 and FIG. 9 of Patent Document 1, the inner walls of the contact holes (36a, 36b) formed in the force conversion element (pressure detection element) described in Patent Document 1 have an inner wall. It has a cylindrical shape extending along a direction orthogonal to the upper surface of the piezoresistor (23).
Therefore, in order to securely connect the piezoresistive negative electrode (21) and the piezoresistive positive electrode (22) to the piezoresistor (23) exposed at the bottom of the contact hole (36a, 36b), the piezoresistive negative electrode (21) and the piezoresistive positive electrode (22) must be formed thick. For example, in Patent Document 1, the contact holes (36a, 36b) are filled, and the piezoresistive negative electrode (21) and the piezoresistive positive electrode (22) are formed so as to protrude from the contact holes (36a, 36b).

  However, forming the piezoresistive negative electrode (21) and the piezoresistive positive electrode (22) thickly by sputtering takes man-hours and time. Therefore, disconnection is likely to occur near the corners of the upper edges of the contact holes (36a, 36b).

  Therefore, it is conceivable that the contact hole has a tapered shape with a diameter increasing toward the upper side from the upper surface of the piezoresistor. Even in this case, the piezoresistive negative electrode (21) and the piezoresistive positive electrode (22) are thickened. Then, disconnection is likely to occur near the corners of the upper edges of the contact holes (36a, 36b) due to their own stress. On the other hand, if these are made thin, the thickness in the direction perpendicular to the slope becomes thin, and there is a risk of causing problems such as disconnection.

  The present invention has been made in view of the current situation, and in a pressure detection element using a Si semiconductor substrate including a pressure-sensitive resistor using a piezoresistance effect, the piezoresistor and a wiring layer via a contact hole are provided. And a pressure detecting element in which a highly reliable wiring layer is formed.

  The solution includes a pressure-sensitive resistor, a temperature-sensitive resistor, and at least a part of the pressure-sensitive resistor and the temperature-sensitive resistor, and at least the pressure-sensitive resistor and the temperature-sensitive resistor. An insulating layer having a contact hole reaching any one of the upper surfaces, and a wiring layer formed on the insulating layer and connected to the upper surface of the pressure-sensitive resistor or the temperature-sensitive resistor through the contact hole And at least one of the contact holes formed of the insulating layer, at least a wiring layer forming portion formed in contact with the wiring layer is the pressure detecting element including the Si semiconductor substrate having The further away from the top surface in the first direction perpendicular to the top surface of the resistor to which the wiring layer is connected, the more exposed the contact hole in the top surface in the second direction parallel to the top surface. A plurality of sloped portions separated from the connecting surface to be formed, and a plurality of sloped portions located between two adjacent sloped portions and parallel to the top surface of the resistor. The dimension in the first direction of the wiring layer formed in the wiring layer forming portion of the contact hole is the thickness of the wiring layer, and from the upper surface of the resistor in the insulating layer, When the dimension in the first direction to the top surface around the contact hole is the total step of the insulating layer, the thickness of the wiring layer is smaller than 1.2 times the total step of the insulating layer, The pressure detecting element is configured to be larger than 1.2 times the step in the first direction formed by the slope portion.

As described above, when it is attempted to increase the thickness of the wiring layer, man-hours and costs are increased, and stress is likely to remain in the formed insulating layer, which may cause disconnection or peeling. Therefore, a thin wiring layer is desired.
On the other hand, the wiring layer needs to secure a certain thickness in consideration of current resistance and disconnection due to being too thin.
Further, in the connection between the resistor (pressure-sensitive resistor, temperature-sensitive resistor) and the wiring layer in the Si semiconductor substrate, the inner wall surface of the contact hole formed in the insulating layer has a cylindrical shape orthogonal to the upper surface of the resistor. Of course, even when it is formed with a slope (tapered surface) that increases in diameter with increasing distance from the upper surface, if the thickness of the insulating film is large (the step is large) and the wiring layer is relatively thin, At the slope portion, the film thickness in the direction orthogonal to the slope portion of the wiring layer becomes thin, and there is a possibility that problems such as disconnection occur in the wiring layer.
For this reason, the thickness of the wiring layer in the contact hole is increased to be 1.2 times as large as the step.

  On the other hand, in the pressure detection element of the present invention, at least the wiring layer forming portion in the insulating layer forming the contact hole has a multi-stage shape. In addition, while the thickness Th of the wiring layer is smaller than 1.2 times the total step Dz (thin: Th <1.2Dz), it is thicker than 1.2 times each step (for example, Ds1, Ds2). (Th> 1.2Ds1, Ds2). For this reason, with respect to each step, the thickness of the wiring layer is ensured, and in relation to all the steps, the thickness can be reduced as compared with the conventional case. Thus, the connection between the upper surface of the resistor and the wiring layer in this contact hole can be reliably performed, and the thickness of the wiring layer can be reduced, thereby reducing the man-hours and costs and reducing the stress generated in the wiring layer. In addition, problems such as disconnection due to residual stress can be reduced.

Of the contact holes, at least the wiring layer forming portion formed in contact with the wiring layer may have a multi-stage shape. Therefore, in the contact hole, only the wiring layer forming part may be formed in a plurality of steps, and the other part may be formed in a cylindrical shape or a one-step inclined shape. It may be.
Further, the insulating layer of the pressure detection element may have a contact hole reaching the upper surface of the pressure sensitive resistor and a contact hole reaching the upper surface of the temperature sensitive resistor, or one of them may be perforated. good.

  Furthermore, in the above-described pressure detection element, the dimension L in the direction away from the connection surface in the second direction in the planar portion is greater than or equal to each step formed by the upper and lower slope portions connected to itself. It is preferable that the pressure inspection element has a size of.

If the dimension L of the flat portion of the contact hole is small, the effect of providing a flat portion between the slope portions to form a plurality of steps tends to be low. That is, when the dimension L of the flat surface portion is small, the slope portion is close to a continuous shape (for example, one-stage shape), and the advantage of providing a plurality of slope portions tends to be small.
On the other hand, in the pressure detection element of the present invention, the dimension L of the plane portion is set larger than each step (for example, Ds1, Ds2) (for example, L> Ds1, Ds2). It is possible to prevent the film thickness in the direction orthogonal to the slope portion from being reduced, and to prevent problems such as disconnection of the wiring layer.

  In addition, it is preferable that the dimension L of the plane portion is not less than five times (for example, L ≧ 5Ds1, L ≧ 5Ds2) with respect to the step (for example, Ds1, Ds2). This is because the mutual influence between the steps can be reduced with respect to the stress applied to the wiring layer.

  Furthermore, the pressure detection element according to any one of the above, wherein the angle between the inclined surface and the upper surface of the resistor is 45 degrees or less.

When forming the wiring layer, it is formed by depositing in the first direction by sputtering or the like. Therefore, when the angle formed by the slope portion (for example, α1, α2) is large, if a thin wiring layer is formed, it is orthogonal to the slope portion. The film thickness when viewed in the direction may become too thin.
On the other hand, in the pressure detection element of the present invention, the angle of the slope portion is set to 45 degrees or less (for example, α1, α2 ≦ 45 deg), so that the thickness of the wiring layer becomes too thin in the direction orthogonal to the slope portion. Can be prevented.

  Furthermore, in the pressure detection element according to any one of the above, the wiring layer has conductivity between at least the connection surface of the resistor, and a component in the wiring layer is A pressure detection element including a diffusion preventing layer that suppresses diffusion into the resistor is preferable.

A resistor (pressure-sensitive resistor, temperature-sensitive resistor) is formed by doping impurities such as phosphorus in silicon. For example, a wiring layer is formed of Au, Pt, etc., and this wiring layer is used as a resistor. When exposed to high temperatures in contact, these atoms diffuse, changing the resistance of the resistor, forming a brittle silicon compound at the connection between the two, and breaking at the connection. There is a risk of causing it.
In contrast, the pressure detection element of the present invention includes a diffusion prevention layer in the wiring layer. For this reason, it is possible to prevent the components in the wiring layer from diffusing into the resistor, and it is possible to prevent a resistance change of the resistor and a breakage at a connection portion between the wiring layer and the resistor.

The diffusion prevention layer has conductivity and has a property of suppressing the diffusion of components in the wiring layer into the resistor. For example, a layer made of Au or Pt is used as the wiring layer. When it is provided, a layer made of TiN provided on the resistor side than this is mentioned. Moreover, the layer which consists of WN and HfN is also mentioned.
In addition, the diffusion prevention layer may be provided in a portion of the wiring layer that is in contact with the resistor, specifically, at least between the connection surface on the upper surface of the resistor. Therefore, a diffusion prevention layer made of TiN or the like may be provided only in a portion of the wiring layer located on the connection surface on the upper surface of the resistor, or the entire wiring layer to be formed includes a diffusion prevention layer. Also good.

  Further, in the pressure detection element according to any one of the above, the Si semiconductor substrate is an SOI substrate including a silicon oxide insulating layer, and the resistor is formed immediately above the silicon oxide insulating layer. It is preferable to use a pressure detecting element.

In the pressure detection element of the present invention, an SOI substrate is used, and the resistor is formed immediately above the silicon oxide insulating layer. For this reason, it is prevented that the insulation resistance of a resistor and another circuit falls under high temperature, and it can operate | move under high temperature.
Therefore, in particular, coupled with the fact that the wiring layer can be made thin, it is possible to prevent peeling and cracking of the wiring layer due to stress under high temperature, and to provide a highly reliable pressure detecting element.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows the structure of a pressure detection element 100 according to this embodiment. FIG. 2 shows a longitudinal section of the Si semiconductor substrate 110 used for the pressure detection element 100.

  The pressure detection element 100 of this embodiment includes a Si semiconductor substrate 110, a support substrate 130, and bumps 140. Among these, the support substrate 130 includes a ceramic substrate 131 made of alumina and connection pads 132 formed thereon. On the other hand, the Si semiconductor substrate 110 is an SOI substrate (Silicon On Insulator), and is arranged so that the circuit forming surface 110C on which the pressure sensitive resistor 113 and the like are formed faces the ceramic substrate 131, and the pads 116P and 117P are The connection pads 132 are flip-chip connected electrically and mechanically via bumps 140 made of Au.

  When the pressure detecting element 100 receives a pressing force PP as shown by an arrow in FIG. 1, the Si semiconductor substrate 110 is distorted and the resistance value of the pressure sensitive resistor 113 changes. Accordingly, when a constant current is passed through the pressure-sensitive resistor 113, the voltage generated at both ends of the pressure-sensitive resistor 113 changes, and when a constant voltage is applied to the pressure-sensitive resistor 113. The current flowing through the pressure sensitive resistor 113 changes. By detecting this, the magnitude of the pressing force PP can be detected.

Next, the Si semiconductor substrate 110 will be described in detail with reference to FIG. As described above, this Si semiconductor substrate 110 is an SOI substrate, and an intermediate oxide film layer 112 made of silicon oxide and having a thickness of 0.4 μm is formed on a Si support layer 111 made of Si and having a thickness of 525 μm. . A pressure sensitive resistor 113 and a temperature sensitive resistor 114 having a thickness of 0.4 to 1.0 μm are formed immediately above the intermediate oxide film layer 112. These are P-type semiconductors in which Si is doped with phosphorus or the like. As will be described later, an Si active layer having a (110) plane or equivalent plane orientation is etched into a trapezoidal cross section. It is.
Thus, in the pressure detection element 100 of the present embodiment, an SOI substrate is used as the Si semiconductor substrate 110, and the pressure sensitive resistor 113 and the temperature sensitive resistor 114 are directly above the intermediate oxide film layer 112 (silicon oxide insulating layer). Is formed. For this reason, the insulation resistance between these resistors 113 and 114 and other circuits is prevented from decreasing at a high temperature and can operate at a high temperature.
Further, as will be described later, coupled with the fact that the wiring layer 116 can be thinned, the peeling and cracking of the wiring layer 116 due to stress under high temperature can be prevented, and a highly reliable pressure detecting element 100 can be obtained. be able to.

Of these, the pressure-sensitive resistor 113 is mainly configured to extend in the <110> direction. Specifically, it is a pressure-sensitive resistor in which a plurality of portions extending in the <110> direction are arranged and these end portions are connected by a short connecting portion to form a single zigzag shape. In addition, it is good also as a pressure-sensitive resistor which has one long site | part extended in <110> direction. When the pressure sensitive resistor 113 is subjected to stress that expands and contracts in the <110> direction, the resistance value of the pressure sensitive resistor 113 changes due to the piezoresistive effect.
On the other hand, since the temperature sensitive resistor 114 is mainly configured to have a portion extending in the <100> direction, even if stress is applied to the temperature sensitive resistor 114, the piezoresistive effect hardly occurs. The resistance value is configured to hardly change. However, the resistance value of the temperature sensitive resistor 114 changes depending on the temperature of itself (Si semiconductor substrate 110). For this reason, the temperature of the temperature sensitive resistor 114 itself and further the temperature of the Si semiconductor substrate 110 can be known from the resistance value. The temperature-sensitive resistor 114 has a single zigzag shape in which a plurality of portions extending in the <100> direction are arranged and these end portions are connected by a short connection portion. It is a temperature resistor. In addition, it is good also as a temperature sensitive resistor which has one long site | part extended in <100> direction.

Further, an insulating layer 115 made of SiO 2 is formed on the intermediate oxide film layer 112, the pressure sensitive resistor 113, and the temperature sensitive resistor 114 to cover them.
However, a first contact hole 115 </ b> C is formed in a predetermined portion of the insulating layer 115. Therefore, a predetermined portion near the end of the pressure-sensitive resistor 113 in the upper surface 113U of the pressure-sensitive resistor 113, specifically, a wiring layer 116 described later in the upper surface 113U of the pressure-sensitive resistor 113 is used. The connection surface 113Ua that connects to is exposed in the first contact hole 115C.
Similarly, a second contact hole 115 </ b> D is drilled at a predetermined position of the insulating layer 115. Therefore, a predetermined portion of the upper surface 114U of the temperature sensitive resistor 114 near the end of the temperature sensitive resistor 114 is specifically connected to the wiring layer 117 of the upper surface 114U of the temperature sensitive resistor 114. The connecting surface 114Ua to be exposed is exposed in the second contact hole 115D.

The first contact hole 115C has a generally tapered shape (conical frustum shape) that is recessed toward the connection surface 113Ua. Specifically, a two-stage shape (two-stage truncated cone shape) including a ring-shaped flat surface portion 115CP parallel to the upper surface 113U of the pressure-sensitive resistor 113 and two inclined surface portions 115CS1 and 115CS2 sandwiching the ring-shaped flat surface portion 115CP. It is said that.
As shown in FIGS. 2 and 7, a part of the inner peripheral surface of the first contact hole 115C in the circumferential direction extends from the first contact hole 115C to the first contact hole 115C in the insulating layer 115. A wiring layer 116 made of Pt or the like extending over the insulating layer 115 beyond the surrounding top surface 115T1 is formed.
Therefore, in this embodiment, the insulating layer 115 has the entire inner peripheral surface including the wiring layer forming portion 115CW in contact with the wiring layer 116 in the first contact hole 115C and the two inclined portions 115CS1 and 115CS2. The two-step shape having one plane portion 115CP which is located between the two slope portions 115CS1 and 115CS2 and which is parallel to the upper surface 113U of the pressure-sensitive resistor 113 is formed. Moreover, the two slope portions 115CS1 and 115CS2 are separated from the top surface 113U in the first direction DD1 orthogonal to the top surface 113U of the pressure sensitive resistor 113, that is, in the second direction DD2 parallel to the top surface 113 in the upper direction in FIG. The upper surface 113 is separated from the connection surface 113Ua exposed to the first contact hole 115C.

The first contact hole 115C of the insulating layer 115 and the wiring layer 116 will be described in more detail with reference to FIG.
The dimension of the wiring layer 116 formed in the wiring layer forming portion 115CW of the first contact hole 115C in the first direction DD1 (vertical direction in the figure) is the thickness Th of the wiring layer 116 (Th = 0.0 in this embodiment). 4 μm). Further, the dimension in the first direction DD1 from the upper surface 113U of the pressure-sensitive resistor 113 to the top surface 115T1 around the first contact hole 115C is the total step Dz of the insulating layer 115 (Dz = 0.0 in this embodiment). 6 μm).

  In this case, in the present embodiment, the thickness Th of the wiring layer 116 is smaller than 1.2 times the total step Dz of the insulating layer 115 (Th <1.2Dz). That is, the thickness of the wiring layer 116 is made thinner than before. In other words, the conventional contact hole is thin enough to cause disconnection.

  On the other hand, when the steps in the first direction DD1 formed by the inclined portions 115CS1 and 115CS2 are the steps Ds1 and Ds2 (Ds1 = 0.3 μm, Ds2 = 0.3 μm in this embodiment), the wiring layer 116 is used. The thickness Th of each is larger than these 1.2 times (Th> 1.2Ds1, Th> 1.2Ds2). That is, regarding the steps Ds1 and Ds2, the thickness Th of the wiring layer 116 is set to a thickness that hardly causes disconnection.

For this reason, the thickness Th of the wiring layer 116 is secured in relation to the respective steps Ds1 and Ds2, while the thickness Th can be made thinner than in the conventional case in relation to the entire step Dz. Thus, the connection between the upper surface 113U of the pressure-sensitive resistor 113 and the wiring layer 116 in the first contact hole 115C can be reliably performed.
In addition, since the thickness Th of the wiring layer 116 can be reduced, man-hours and costs can be reduced, and the stress generated in the wiring layer 116 can be reduced, so that problems such as disconnection due to residual stress can be reduced.

In addition, in the present embodiment, the dimension Lc in the direction DD2H (left and right direction in the drawing) of the first contact hole 115C in the plane portion 115CP away from the connection surface 113Ua in the second direction DD2 is Lc = 5 μm. Yes. That is, the dimension Lc in the direction DD2H of the flat surface portion 115CP is set to be larger than the steps Ds1 and Ds2 formed by the upper and lower slope portions 115CS1 and 115CS2 connected to the plane portion 115CP.
If the dimension Lc of the flat surface portion 115CP of the first contact hole 115C is small, the effect of providing the flat surface portion 115CP between the slope portions 115CS1 and 115CS2 and making it a two-stage shape tends to be low. That is, when the dimension Lc of the plane portion 115CP is small, the slope portion is close to a continuous shape (one-stage shape), and the advantage of providing a plurality of slope portions 115CS1 and 115CS2 tends to be small.
On the other hand, in the pressure detection element 100 of the present embodiment, the dimension Lc of the planar portion 115CP is set larger than the steps Ds1 and Ds2, that is, Lc> Ds1, Lc> Ds2, and therefore the wiring layer It is possible to prevent the film thickness in the direction DD3 (upper left-lower right direction in the figure) perpendicular to the slope portions 115CS1 and 115CS2 of the 116 from being reduced, and problems such as disconnection of the wiring layer 116 can be prevented.

In the present embodiment, as shown in FIG. 7, the dimension Lc (= 5 μm) of the flat portion 115CP is about 17 times the steps Ds1 (= 0.3 μm) and Ds2 (= 0.3 μm). did.
Thus, it is preferable that the dimension Lc of the plane portion 115CP is five times or more of the steps Ds1 and Ds2, for example, Lc ≧ 5Ds1, Lc ≧ 5Ds2. This is because the mutual influence between the steps can be reduced with respect to the stress applied to the wiring layer 116.

The wiring layer 116 is formed by depositing Pt or the like in the first direction DD1 by sputtering or the like. Therefore, when the angles (eg, α1, α2) formed by the slope portions 115CS1 and 115CS2 are large, the thickness (Th When the thin wiring layer 116 is formed, the film thickness Tα when viewed in the direction DD3 perpendicular to the slope portions 115CS1 and 115CS2 may be too thin.
On the other hand, the angles α1 and α2 between the slope portions 115CS1 and 115CS2 and the upper surface 113U of the pressure-sensitive resistor 113 are set to 45 degrees or less. Specifically, α1 = 30 deg and α2 = 30 deg. Thereby, it is possible to prevent the film thickness Tα of the wiring layer 116 from becoming too thin in the direction DD3 orthogonal to the slope portions 115CS1 and 115CS2.

  In the present embodiment, as described above, in addition to the pressure sensitive resistor 113, the temperature sensitive resistor 114 is also formed. However, the second contact for connecting the temperature sensitive resistor 114 and the wiring layer 117 is used. The hole 115D is also formed in the same form as the first contact hole 115C. That is, as shown in FIG. 2, the shapes of the wiring layer 117 and the second contact hole 115D are the same as the shapes of the wiring layer 116 and the first contact hole 115C (in FIG. 2, they are drawn symmetrically). A description will be given with reference to FIG.

  The thickness Th (the dimension in the first direction DD1) of the wiring layer 117 formed in the wiring layer forming portion 115DW of the second contact hole 115D is Th = 0.4 μm, similarly to the wiring layer 116. Further, the total step Dz of the insulating layer 115 (the dimension in the first direction DD1 from the upper surface 114U of the temperature sensitive resistor 114 to the top surface 115T2 around the second contact hole 115D) is Dz = 0.6 μm described above. is there.

  In the present embodiment, the thickness Th of the wiring layer 117 is also smaller than 1.2 times the total step Dz of the insulating layer 115 (Th <1.2Dz). That is, the thickness of the wiring layer 116 is made thinner than before. In other words, the conventional contact hole is thin enough to cause disconnection.

  On the other hand, when the steps in the first direction DD1 formed by the slopes 115DS1 and 115DS2 are steps Ds3 and Ds4 (in this embodiment, Ds3 = 0.3 μm, Ds4 = 0.3 μm), the wiring layer 117 The thickness Th of each is larger than these 1.2 times (Th> 1.2Ds3, Th> 1.2Ds4). In other words, regarding each of the steps Ds3 and Ds4, the thickness Th of the wiring layer 117 is set to a thickness that hardly causes disconnection.

For this reason, the thickness Th of the wiring layer 117 is ensured in the relationship with the steps Ds3 and Ds4, while the thickness Th is reduced in the relationship with the entire step Dz as compared with the conventional case. Thus, the connection between the upper surface 114U of the temperature-sensitive resistor 114 and the wiring layer 117 in the second contact hole 115D can be reliably performed.
In addition, since the thickness Th of the wiring layer 117 can be reduced, man-hours and costs can be reduced, and stress generated in the wiring layer 117 can be reduced, so that problems such as disconnection due to residual stress can be reduced.

Moreover, in the present embodiment, the dimension L of the second contact hole 115D in the direction DD2H (the left-right direction in the drawing) away from the connection surface 114Ua in the second direction DD2 in the planar portion 115DP is Ld = 5 μm. Yes. That is, the dimension Ld in the direction DD2H of the flat portion 115DP is set to be larger than the steps Ds3 and Ds4 formed by the upper and lower slope portions 115DS1 and 115DS2 connected to the plane portion 115DP.
For this reason, it is possible to prevent the film thickness in the direction DD3 (upper left-lower right direction in the figure) perpendicular to the slopes 115DS1 and 115DS2 of the wiring layer 117 from being reduced, and problems such as disconnection of the wiring layer 117 can be prevented.

  In particular, it is preferable that the dimension L of the flat surface portion 115DP is five times as large as the steps Ds3 and Ds4, for example, Ld ≧ 5Ds3, Ld ≧ 5Ds4. This is because the mutual influence between the steps can be reduced with respect to the stress applied to the wiring layer 117.

  Further, the angles α3 and α4 formed by the slope portions 115DS1 and 115DS2 with the upper surface 114U of the temperature-sensitive resistor 114 are set to α3 = 30 deg and α4 = 30 deg that are 45 degrees or less. Thereby, it is possible to prevent the film thickness Tα of the wiring layer 117 from becoming too thin in the direction DD3 orthogonal to the slope portions 115DS1 and 115DS2.

  Next, manufacture of the pressure detection device 100 of the present embodiment will be described. In the manufacture of the Si semiconductor substrate 110, the temperature sensitive resistor 114 is formed in addition to the pressure sensitive resistor 113, but the wiring pattern (extending direction) to be formed is different, and the same manufacturing method is used. Make two differently by making different. Therefore, in the following, a method for forming the pressure sensitive resistor 113 in the Si semiconductor substrate 110 will be mainly described, and a method for manufacturing the temperature sensitive resistor 114 may be omitted.

  First, the manufacture of the Si semiconductor substrate 110 will be described with reference to FIGS. As shown in FIG. 3A, the wafer 120 is made of p-type Si via an intermediate oxide film layer 112 (thickness 0.4 μm) on a Si support layer 111 (thickness 525 μm) made of Si. A layer in which an Si active layer 121 (thickness 0.4 μm) is stacked is prepared. The surface 121S of the Si active layer 121 is the (100) plane of the crystal plane.

Therefore, as shown in FIG. 3B, a predetermined position of the Si active layer 121 is doped with an impurity (P), and the Si active layer 121 has the aforementioned zigzag predetermined pattern in the pressure sensitive resistor. 113 and temperature sensitive resistor 114 are formed. The pressure-sensitive resistor 113 has an impurity concentration of 5 × 10 ⁻¹⁷ cm ⁻¹ , and the temperature-sensitive resistor 114 has an impurity concentration of 7 × 10 ⁻¹⁹ cm ⁻¹ and is activated after doping. Therefore, annealing was performed at 1000 ° C. for 30 minutes.
Thereafter, the unnecessary Si active layer 121 is removed by RIE, leaving the pressure-sensitive resistor 113 and the temperature-sensitive resistor 114 on the intermediate oxide film layer 112 (see FIG. 3C).

Next, an insulating film 115 made of PE-SiO ₂ and having a thickness of 0.5 μm is formed on the intermediate oxide film layer 112 so as to cover the pressure sensitive resistor 113 and the temperature sensitive resistor 114 (see FIG. 3D). ).

  Thereafter, as shown in FIG. 4A, a first contact hole 115C in which the upper surface 113U (connection surface 113Ua) is exposed is formed at a predetermined position on the upper surface 113U of the pressure sensitive resistor 113 in the insulating film 115. To do. Similarly, a second contact hole 115D in which the upper surface 114U (connection surface 114Ua) is exposed is formed at a predetermined position on the upper surface 114U of the temperature sensitive resistor 114.

The formation of the first contact hole 115C will be described with reference to FIGS.
First, a first resist film R1 is formed on the surface 115S of the insulating layer 115, exposed and developed, and a first opening OR1 is opened at a position where the first and second contact holes 115C and 115D are formed. Thereafter, the insulating layer 115 exposed in the first opening OR1 is etched to form a recess 115R. At this time, the depth of the recess 115R is about half the thickness of the insulating layer 115, specifically, the depth of the steps Ds2 and Ds4 of the slopes 115CS2 and 115DS2 to be formed.
Note that the outer diameter of the recess 115R becomes larger than the first opening OR1 due to the etching solution.

  Next, the first resist film R1 is removed, and the second resist film R2 is formed again on the surface 115S of the insulating layer 115, exposed and developed, and the first and second contact holes 115C and 115D are formed. Then, the second opening OR2 is opened. The second resist film R2 covers the surface of the previously formed recess 115R, and the second opening OR2 is opened so that a part of the bottom surface 115RT of the recess 115R is exposed. Thereafter, the insulating layer 115 exposed in the second opening OR2 is connected to the connection surface 114Ua of the upper surface 113U of the pressure-sensitive resistor 113 until the connection surface 113Ua is exposed and of the upper surface 114U of the temperature-sensitive resistor 114. Etch until exposed. Thus, two-stage first and second contact holes 115C and 115D are formed (see FIG. 4A). The forms of the first and second contact holes 115C and 115D have been described above.

  Thereafter, the second resist layer is removed. Further, in order to lower the connection resistance with the wiring layers 116 and 117 described below, Pt is deposited to 100 nm by sputtering on the connection surfaces 113Ua and 114Ua exposed from the first and second contact holes 115C and 115D, and annealed. Thus, a connection layer 119 made of a PtSi compound is formed (see FIG. 4B).

  Next, wiring layers 116 and 117 are formed on the surface 115S of the insulating layer 115, predetermined positions in the first and second contact holes 115C and 115D, and the connection surfaces 113Ua and 114Ua (on the connection layer 119). . Specifically, three layers of Ti (0.02 μm), TiN (0.2 μm), and Pt (0.4 μm) are deposited in this order by sputtering to form the wiring layers 116 and 117 (see FIG. 4C). ). Among these layers, the layers made of TiN are diffusion prevention layers 116D and 117D for preventing Pt deposited thereon from diffusing into the pressure sensitive resistor 113 and the temperature sensitive resistor 114. The diffusion prevention layers 116D and 117D can prevent a change in resistance of the pressure sensitive resistor and breakage at the connection portion between the wiring layer and the pressure sensitive resistor.

  Further, a protective film 118 made of PE-SiO2 is formed on the surface 115S of the insulating layer 115 on the entire surface except the pads 116P and 117P of the wiring layers 116 and 117, thereby completing the Si semiconductor substrate 110 shown in FIG.

Thereafter, the pads 116P and 117P of the Si semiconductor substrate 110 are flip-chip connected to the connection pads 132 of the ceramic substrate 131 by the bumps 140 made of Au, thereby completing the pressure detecting element 100.
In addition, the value of the dimension of each part shown in the above description and the form described in the drawings may not match. The form described in each drawing is a reference, and does not define the actual form or dimensional relationship of each part.

In the above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention can be appropriately modified and applied without departing from the gist thereof. .
For example, in the embodiment, the pressure-sensitive resistor 113 is shown in which two slope portions 115CS1 and 115CS2 and a plane portion 115CP are formed over the entire circumference of the first contact hole 115C. The same applies to the temperature-sensitive resistor 114.
However, it is sufficient that at least a wiring layer forming portion formed in contact with the wiring layer in the contact hole has a multi-stage shape. Therefore, in the contact hole, only the wiring layer forming part may be formed in a plurality of steps, and the other part may be formed in a cylindrical shape or a one-step inclined shape. It may be.

In the embodiment, the first contact hole 115C has a two-stage shape in which two slope portions 115CS1 and 115CS2 and a plane portion 115CP are formed.
However, it may be a multi-stage shape having three or more stages.

Furthermore, in the embodiment, an example in which one pressure-sensitive resistor 113 and one temperature-sensitive resistor 114 are formed on one Si semiconductor substrate 110 is illustrated. A pressure sensitive resistor may be formed, and in that case, the extending direction of some pressure sensitive resistors may be different from other pressure sensitive resistors. In addition, a Wheatstone bridge is configured using four or more pressure-sensitive resistors of one or a plurality of pressure detecting elements (Si semiconductor substrates) so as to obtain a differential voltage corresponding to the stress applied to the Si semiconductor substrate. May be. In addition, in order to use a plurality of pressure sensitive resistors in cooperation with each other, such as a bridge circuit, a pattern such as an arrangement or a direction in which the pressure sensitive resistors extend so that each pressure sensitive resistor behaves differently with respect to stress. It is good to consider.
In the above-described embodiment, the example in which the multi-stage contact holes 115C and 115D are formed in the pressure-sensitive resistor 113 and the temperature-sensitive resistor 114 has been described. However, only the contact holes of the pressure sensitive resistor may be multi-staged, or conversely, only the contact holes of the temperature sensitive resistor may be multi-staged.

It is sectional drawing which shows the structure of the pressure detection element which concerns on embodiment. It is sectional drawing of Si semiconductor substrate among the pressure detection elements which concern on embodiment. FIG. 4 is an explanatory diagram for explaining a process up to a process of forming a Si oxide film on a resistor for an SOI substrate in the manufacturing process of a Si semiconductor substrate according to the embodiment. It is explanatory drawing which concerns on embodiment and explains the process of formation of a contact hole and formation of a wiring layer among manufacturing processes of a Si semiconductor substrate. It is explanatory drawing explaining the process of forming an upper stage among the processes of forming a two-stage contact hole among manufacturing processes of a Si semiconductor substrate according to the embodiment. It is explanatory drawing explaining the process of forming a lower step among the processes of forming a two-stage contact hole among manufacturing processes of a Si semiconductor substrate according to the embodiment. It is explanatory drawing explaining the shape and dimensional relationship of a two-stage contact hole and a wiring layer concerning embodiment.

Explanation of symbols

100 Pressure sensing element 110 Si semiconductor substrate (SOI substrate)
110C Circuit forming surface 113 Pressure sensitive resistor 113U (Pressure sensitive resistor) upper surface 113Ua (Of upper surface) Connection surface 114 Temperature sensitive resistor 114U (Temperature sensitive resistor) Upper surface 114Ua (Of upper surface) Connection surface 115 Insulation Layer 115S (insulating layer) surface 115C (with pressure sensitive resistor formed in insulating layer) first contact hole (contact hole)
115CW (first contact hole) wiring layer forming portion 115CS1, 115CS2 slope 115CP flat portion 115T1 top surface 115D (around the first contact hole of the insulating layer) first surface (with temperature sensitive resistor formed in the insulating layer) 2 Contact holes 115DS1, 115DS2 Slope portion 115DP Plane portion 115T2 Top surface 116, 117 Wiring layer 116D, 117D Diffusion prevention layer 119 Connection layer 120 Wafer 121 Si active layer 121S (Si active) Surface 131 of the layer Ceramic substrate 132 Connection pad DD1 First direction DD2 Second direction DD2H Direction away from the connection surface among the second directions DD3 Direction perpendicular to the slope Dz All steps Ds1, Ds2, Ds3, Ds4 Step Th Thickness of wiring layer Lc, Ld Dimension α1 away from part of the connecting surface opening, α2, α3, thickness when α4 slope portion is viewed in a direction slant portion perpendicular top and angle Tα wiring layer of the resistor

Claims (5)

A pressure sensitive resistor,
Temperature-sensitive resistor Insulation in which a contact hole that covers at least a part of each of the pressure-sensitive resistor and the temperature-sensitive resistor and reaches the upper surface of at least one of the pressure-sensitive resistor and the temperature-sensitive resistor is formed Layers,
A pressure detecting element comprising a Si semiconductor substrate formed on the insulating layer and having a wiring layer connected to the top surface of the pressure sensitive resistor or the temperature sensitive resistor through the contact hole,
At least one of the contact holes formed of the insulating layer is
At least the wiring layer forming portion formed in contact with the wiring layer,
As the distance from the upper surface in the first direction orthogonal to the upper surface of the resistor to which the wiring layer is connected is increased, the inclined surface is separated from the connection surface exposed to the contact hole in the upper surface in the second direction parallel to the upper surface. A plurality of sloped portions,
A plane portion located between two adjacent slope portions and parallel to the upper surface of the resistor;
A multi-stage shape having
The wiring layer formed at the wiring layer forming portion of the contact hole has a dimension in the first direction as a thickness of the wiring layer,
Among the insulating layers, when the dimension in the first direction from the upper surface of the resistor to the top surface around the contact hole is the entire step of the insulating layer,
The thickness of the wiring layer is as follows:
Less than 1.2 times the total step of the insulating layer,
A pressure detecting element, wherein the pressure detecting element is made larger than 1.2 times the step in the first direction formed by each of the slope portions. The pressure detection element according to claim 1,
The pressure inspection element in which the dimension in the direction away from the connection surface in the second direction in the plane portion is larger than each step formed by the upper and lower slope portions connected to itself. The pressure detection element according to claim 1 or 2,
The pressure detection element in which the angle between the slope and the upper surface of the resistor is 45 degrees or less. The pressure detection element according to any one of claims 1 to 3,
The wiring layer includes at least a diffusion prevention layer that has conductivity between the connection surface of the resistor and suppresses diffusion of components in the wiring layer into the resistor. element. The pressure detection element according to any one of claims 1 to 4,
The Si semiconductor substrate is an SOI substrate including a silicon oxide insulating layer,
The resistor is a pressure detecting element formed immediately above the silicon oxide insulating layer.

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