TWI619932B - Thermal pile sensing structure integrated with capacitor - Google Patents

Abstract

The invention provides a thermopile sensing structure with integrated capacitors. The thermopile sensing structure of the integrated capacitor includes a substrate, an infrared sensing unit, and a partition structure. The infrared sensing unit is located on the substrate. The infrared sensing unit has a first sensing structure and a second sensing structure. One end of the first sensing structure and the second sensing structure that are close to each other is a hot junction. The partition structure surrounds the infrared sensing unit, wherein one end of the partition structure and the first sensing structure that is close to each other is a cold junction, and one end of the partition structure and the second sensing structure that is close to each other is a cold end. The temperature difference between the hot end and the cold end generates a voltage difference signal, and a part of the separation structure constitutes at least one capacitor.

Description

Thermopile sensing structure with integrated capacitor

The invention relates to a thermopile sensing structure with integrated capacitors, in particular to a thermopile sensing structure with integrated capacitors that integrates MIM capacitors and / or PIP capacitors to save chip area and reduce noise.

Please refer to Figure 1 and compare with Figure 2. FIG. 1 is a functional block diagram of a prior art thermopile sensing structure applied to a temperature sensing module. Figure 2 shows a cross-sectional view of a prior art thermopile sensing structure. The prior art temperature sensing module 100 includes a conventional thermopile sensing structure 10, a noise filter 81, a noise filter 82, a differential amplifier Amp, an analog-to-digital converter ADC, and a temperature sensor.器 80。 80. The thermopile sensing structure 10 generates a voltage difference signal VDS through a change in temperature difference, thereby sensing temperature. After the voltage difference signal generated by the thermopile sensing structure 10 is output, it is processed by the noise filter 81 and the noise filter 82 and input to the differential amplifier Amp. The differential amplifier Amp processes the signal and inputs it to the analog-to-digital converter ADC. The analog-to-digital converter ADC also receives a temperature signal TS output from the temperature sensor 80. The noise filter 81 and the noise filter 82 have a capacitor C1 and a capacitor C2, respectively. In addition, the temperature sensing module 100 further includes a capacitor C3. In this prior art, the capacitor C1, the capacitor C2, and the thermopile sensing structure 10 are three separate and separately packaged parts.

Please refer to Figure 2. The conventional thermopile sensing structure 10 includes: a substrate 11; an infrared sensing unit 16 on the substrate 11; the infrared sensing unit 16 has a first sensing structure 161 and a second sensing structure 162, of which the first sensing structure 161 One end of the second sensing structure 162 that is close to each other is a hot junction; and a partition structure 15 that surrounds the infrared sensing unit 16, wherein one end of the partitioning structure 15 and the first sensing structure 161 that is close to each other is a hot junction. Cold junction C. One end of the separation structure 15 and the second sensing structure 162 that is close to each other is the other cold junction C. The temperature difference between the hot junction H and the cold junction C generates a voltage difference signal VDS. In order to make the infrared sensing unit 16 more accurately sense signals, the prior art further provided a filter layer 14 connected to the body of the thermopile sensing structure 10 through a bonding layer 13.

When the conventional thermopile sensing structure 10 is manufactured by a CMOS process, the separation structure 15 usually includes a polycrystalline silicon layer poly1, multiple metal layers M1-M4 (shown as four layers for example, but the number is not limited to four), and multi-layered Channel layer V. The first sensing structure 161 and the second sensing structure 162 are composed of a metal layer M1 and a polycrystalline silicon layer poly1. The electrical structures are insulated by a dielectric layer 12. The transmission of the voltage difference signal VDS is achieved by the transistor circuit 17.

In this prior art, as mentioned earlier, capacitors C1 and C2 are provided on the path from the thermopile sensing structure 10 to the circuit to filter noise, and the three capacitors C1, C2, and thermopile sensing structure 10 are: Three separate, individually packaged parts. The disadvantage of this prior art is that the overall circuit is relatively area-consuming and costly.

In view of this, the present invention addresses the shortcomings of the foregoing prior art, and proposes a thermopile sensing structure with integrated capacitors that integrates MIM capacitors and / or PIP capacitors to save chip area and reduce noise.

In one aspect, the present invention provides a thermopile sensing structure with integrated capacitors, including: a substrate; an infrared sensing unit located on the substrate; viewed from a cross-sectional view of the substrate cut vertically, the infrared sensing The unit has a first sensing structure and a second sensing structure, wherein one end of the first sensing structure and the second sensing structure being close to each other is a hot junction; and a partition structure surrounds the infrared ray. A sensing unit, wherein one end of the partition structure and the first sensing structure that is close to each other is a cold junction, one end of the partition structure and the second sensing structure that is close to each other is another cold end, and the hot end is connected to the The temperature difference between the cold junctions generates a voltage difference signal, and a part of the separation structure constitutes at least one capacitor.

In a preferred embodiment, the capacitor is a metal-insulator-metal (MIM) capacitor or a polysilicon-insulator-polysilicon (PIP) capacitor.

In the above-mentioned preferred embodiment, the separation structure includes a plurality of metal layers and a plurality of channel layers that are stacked, and the MIM capacitor includes upper and lower electrode plates composed of a metal layer.

In the above-mentioned preferred embodiment, the separation structure includes a plurality of metal layers, a plurality of channel layers, and a plurality of polycrystalline silicon layers that are stacked, and the PIP capacitor includes upper and lower electrode plates composed of a polycrystalline silicon layer.

In a preferred embodiment, the thermopile sensing structure of the integrated capacitor further includes: a dielectric layer on the substrate, wherein the infrared sensing unit and the separation structure are formed in the dielectric layer. .

In the above preferred embodiment, the thermopile sensing structure of the integrated capacitor further includes: a bonding layer on the dielectric layer; and a filter layer for filtering signals other than infrared, the filter The optical layer is connected to the dielectric layer through the bonding layer.

In a preferred embodiment, the temperature difference between the hot end and the cold end is processed by a transistor circuit to generate the voltage difference signal, and the transistor circuit is formed on the substrate.

In another aspect, the present invention provides a thermopile sensing structure with integrated capacitors, including: a substrate having a cavity; an infrared sensing unit located on the substrate; the infrared sensing unit having a first semiconductor stack structure Wherein one end of the first semiconductor stack structure located at the cavity is a hot end; and a partition structure located at the periphery of the infrared sensing unit, wherein one end of the partition structure and the first semiconductor stack structure that is close to each other is a cold end. The temperature difference between the hot end and the cold end generates a voltage difference signal, and a part of the separation structure constitutes at least one capacitor.

In a preferred embodiment, the film layer of at least a part of the separation structure is the same film layer as the film layer of the first semiconductor stack structure.

In a preferred embodiment, the at least one capacitor is a metal-insulator-metal (MIM) capacitor or a polysilicon-insulator-polysilicon (PIP) capacitor.

In a preferred embodiment, the first semiconductor stack structure includes two layers of thermally conductive material connected to each other, wherein a Seebeck coefficient of one of the thermally conductive materials is different from a Seebeck coefficient of the other thermally conductive material.

In a preferred embodiment, the thermopile sensing structure of the integrated capacitor further includes a second semiconductor stack structure, wherein one end of the first semiconductor stack structure and the second semiconductor stack structure that is close to each other is the hot end. One end of the partition structure and the first semiconductor stack structure that is close to each other is the cold end, and one end of the partition structure and the second semiconductor stack structure that is close to each other is the other cold end.

In a preferred embodiment, the film layer of at least a part of the separation structure is the same film layer as the film layer of the second semiconductor stack structure.

Detailed descriptions will be provided below through specific embodiments to make it easier to understand the purpose, technical content, features and effects of the present invention.

The foregoing and other technical contents, features, and effects of the present invention will be clearly presented in the following detailed description of a preferred embodiment with reference to the accompanying drawings. The drawings in the present invention are schematic, and are mainly intended to represent the functional relationship between each device and each component. As for the shape, thickness, and width, they are not drawn to scale.

Please refer to Figure 3 and compare with Figure 4. FIG. 3 shows a functional block diagram of the thermopile sensing structure of the present invention applied to a temperature sensing module. FIG. 4 is a cross-sectional view of a first embodiment of a thermopile sensing structure with integrated capacitors according to the present invention. The temperature sensing module 200 of this embodiment includes a thermopile sensing structure 20 with integrated capacitors, a differential amplifier Amp, an analog-to-digital converter ADC, and a temperature sensor 80. The difference from the prior art temperature sensing module 100 is that the prior art temperature sensing module 100 is in addition to the conventional thermopile sensing structure 10, and additionally has a noise filter 13 and a noise filter 14 ( That is, the thermopile sensing structure 10, the capacitor C1, and the capacitor C2 are three separately manufactured and independently packaged components). However, the thermopile sensing structure 20 with integrated capacitors in this embodiment integrates the noise filter 13 and the noise filter 14 into the thermopile sensing structure 20. The noise filter 13 and the noise filter 14 have a capacitor C1 and a capacitor C2, respectively. In other words, the thermopile sensing structure 20 of this embodiment integrates the capacitors C1 and C2 in a single package (about how the capacitors C1 and C2 are integrated into the semiconductor structure characteristics and details of the thermopile sensing structure 20, Details later).

The design principle of the thermopile sensing structure 20 is to use the Seebeck effect. The principle is that if there are different temperature differences inside the conductive material, different thermoelectromotive forces will be generated. Therefore, if the two ends of the material (that is, the hot end H and the cold end C shown in Figure 4) are given different temperatures, they will A voltage difference is generated, and the temperature difference signal can be amplified by using different conductive materials for temperature sensing. In short, the thermopile sensing structure 20 of the integrated capacitor in this embodiment generates a voltage difference signal VDS (as shown in FIG. 3) through a change in the temperature difference between the hot end H and the cold end C (as shown in FIG. 4). (Shown) to sense temperature in this way.

The voltage difference signal VDS generated by the thermopile sensing structure 20 is processed by the internally integrated noise filter 13 and the noise filter 14 and then output. The output voltage difference signal VDS is input to the differential amplifier Amp. The differential amplifier Amp processes the signal and inputs it to the analog-to-digital converter ADC. In order to stabilize the signal, a capacitor C3 may be provided between the two input terminals of the differential amplifier Amp. In addition, the analog-to-digital converter ADC can receive, for example, but not limited to, a temperature signal TS output by the temperature sensor 80 as a reference. The circuit operation mode of the temperature sensing module is known and will not be described in detail here.

Please refer to Figure 4. The thermopile sensing structure 20 with integrated capacitors in this embodiment includes a substrate 11, an infrared sensing unit 16, a partition structure 25, a bonding layer 13, and a filter layer 14. The substrate 11 is, for example, but not limited to, a silicon substrate. The substrate 11 has a cavity 11A. The infrared sensing unit 16 is located on the substrate 11 and can be used to sense infrared rays. In one embodiment, the infrared sensing unit 16 is used to sense far infrared rays.

In an embodiment, viewed from a cross-sectional view (eg, FIG. 4) of the substrate cut vertically, the infrared sensing unit 16 may have at least one first sensing structure 161 and a second sensing structure 162. As shown in FIG. 4, the first sensing structure 161 may be, for example, but not limited to, a first semiconductor stack structure. In one embodiment, it has at least two layers of thermally conductive material, and the Seebeck coefficients of the two layers of thermally conductive material are different from each other. . In one embodiment, the first sensing structure 161 includes, from top to bottom, for example, but not limited to, a metal layer M1 and a polycrystalline silicon layer Poly1. As shown in FIG. 4, the second sensing structure 162 may be, for example, but not limited to, a second semiconductor stack structure. In one embodiment, it has at least two layers of thermally conductive material, and the Seebeck coefficients of the two layers of thermally conductive material are different from each other. . In one embodiment, the first sensing structure 161 includes, from top to bottom, for example, but not limited to, a metal layer M1 and a polycrystalline silicon layer Poly1. The material of the metal layer M1 and the polycrystalline silicon layer Poly1 are both thermally conductive materials, but it is worth noting that the Seebeck coefficient of the metal layer M1 is different from the Seebeck coefficient of the polycrystalline silicon layer Poly1. In this embodiment, the first sensing structure 161 and the second sensing structure 162 are symmetrically disposed with each other. In such an arrangement, one end (the end near the cavity 11A) of the first sensing structure 161 and the second sensing structure 162 that is close to each other is a hot junction H. The partition structure 15 is located around the infrared sensing unit 16 and surrounds the infrared sensing unit 16. The partition structure 25 and the first sensing structure 161 are close to each other at a cold junction C. The partition structure 25 and the second sensing structure One end of 162 which is close to each other is the other cold end C. As described above, the thermopile sensing structure 20 of the integrated capacitor in this embodiment generates a voltage difference signal VDS through the temperature difference between the hot end H and the cold end C, thereby sensing the temperature.

It is worth noting that the infrared sensing unit 16 does not necessarily have to have two symmetrically arranged sensing structures (i.e., 161 and 162). In another embodiment, the infrared sensing unit 16 may have only one sensing structure (such as, but not limited to, the above-mentioned first semiconductor stack structure, that is, the first sensing structure 161). In such an arrangement, the first sensing structure 161 is located at one end of the cavity 11A as a hot junction H. One end of the partition structure 15 and the first sensing structure 161 which is close to each other is a cold junction C. Similarly, in such a setting, as described above, the thermopile sensing structure 20 of the integrated capacitor of this embodiment generates a voltage difference signal VDS through the temperature difference between the hot end H and the cold end C, and thus senses the temperature . More specifically, in one of the embodiments, the infrared sensing unit 16 may have only one sensing structure and an asymmetric shape as viewed from a cross-sectional view. Or, in another embodiment, viewed from a top view, the sensing structure is a sector or circle formed by the aforementioned semiconductor stack structure, with the hot end H extending as the center and the cold end C as the circumference. In this case, viewed from a cross-sectional view (for example, FIG. 4), the infrared sensing unit 16 has two symmetrical sensing structures, but the two sensing structures actually belong to different positions of the same semiconductor stack structure. All the above are within the scope of this case. In addition, this embodiment has a dielectric layer 12 which is located on the substrate 11. In one embodiment, the dielectric layer 12 is, for example, but not limited to, silicon dioxide (SiO2), which is used as a material for absorbing infrared signals in this embodiment. The infrared sensing unit 16 and the separation structure 25 in this embodiment are formed in the dielectric layer 12.

The bonding layer 13 is located on the dielectric layer 12. The filter layer 14 is connected to the dielectric layer 12 through a bonding layer 13. The filter layer 14 can help the integrated thermopile sensing structure 20 to filter signals other than infrared.

The filter layer 14 allows infrared temperature signals from an object to be measured (not shown) to pass through. In an embodiment, the thickness of the filter layer 14 may be, for example, but not limited to, 5 to 15 μm. In an embodiment, the material of the filter layer 14 may be, for example, but not limited to, polyethylene (PE), polypropylene (Polypropylene / Polypropene, PP), or polyethylene terephthalate. , Referred to as PET). In addition to filtering, the filter layer 14 can prevent dirt from entering the thermopile sensing structure 20.

The voltage difference generated by the infrared sensing unit 16 can be processed by an external circuit to generate the aforementioned voltage difference signal VDS; this external circuit is, for example but not limited to, a transistor circuit 17 (as shown in FIG. 4), which is formed in In the substrate 11.

In a preferred embodiment, the thermopile sensing structure 20 of this embodiment can be fabricated using a semiconductor CMOS standard process. Among them, the polycrystalline silicon, metal, and silicon dioxide can be deposited and etched on the silicon substrate 11 to form a transistor circuit 17, an infrared sensing unit 16, a separation structure 15, and a dielectric layer 12, and then used in a later process. For example, but not limited to, the silicon substrate 11 is etched on the back surface to etch the silicon substrate 11 to form the shape of the substrate 11 as shown in FIG. 4.

This embodiment is characterized in that a part of the separation structure 25 constitutes at least one capacitor. As shown in FIG. 4, in one embodiment, the separation structure may include four metal layers (for example, aluminum) M1 to M4 and a plurality of channel layers V (for example, tungsten), and may include one or more layers. Multi-layered polycrystalline silicon layer (shown as Poly1 in this embodiment). However, the present invention is not limited to the number, material, order, and layout pattern of the lamination shown in this embodiment, and may be a lamination of metal layers and channel layers of different numbers and materials. Different changes (for example, the uppermost layer may be the channel layer V). As shown in FIG. 4, in an embodiment, the metal layer M1 of the separation structure 25 and the metal layer M1 of the first sensing structure 161 (the first semiconductor stack structure described above) are the same film layer, and the polycrystalline silicon of the separation structure 25 is The layer Poly1 is the same film layer as the polycrystalline silicon layer Poly1 of the first sensing structure 161. In one embodiment, the metal layer M1 of the separation structure 25 and the metal layer M1 of the second sensing structure 162 (the second semiconductor stack structure described above) are the same film layer, and the polycrystalline silicon layer Poly1 of the separation structure 25 and the second sensing structure Poly1 of 162 has the same film layer.

The above-mentioned metal layers M1 to M4 and the channel layer V are described using the concept of a general CMOS process, which corresponds to the order of the metal layers in the interconnection of a semiconductor structure of a microelectronic circuit. It is worth noting that, in this embodiment, a metal layer M3A is included between the metal layers M3 and M4. The metal layer M4, the insulating layer (that is, a part of the dielectric layer 12), and the metal layer M3A form a metal-insulator-metal (MIM) capacitor 25A. The metal layer M4 constitutes the upper electrode plate and The metal layer M3A constitutes a lower electrode plate. This MIM capacitor 25A can be used as the aforementioned capacitor C1 or C2. Therefore, the present invention can integrate the capacitor C1 and / or C2 in the thermopile sensing structure 20, and greatly reduce the area and manufacturing of the overall temperature sensing module. cost.

Please refer to FIG. 5, which is a cross-sectional view of a second embodiment of a thermopile sensing structure with integrated capacitors according to the present invention. The thermopile sensing structure 30 of the integrated capacitor in this embodiment is similar to the thermopile sensing structure 20 of the integrated capacitor in the first embodiment, the difference is that in the thermopile sensing structure 30 of the integrated capacitor in this embodiment, As shown in FIG. 5, the separation structure includes two polycrystalline silicon layers, Poly1 and Poly2, in addition to four metal layers (eg, aluminum) M1 to M4 and a plurality of channel layers V (eg, tungsten). The metal layers M1 to M4, the channel layer V, and the polycrystalline silicon layers Poly1 and Poly2 can be completed by a general CMOS process. Similar to the previous embodiment, the present invention is not limited to the number, material, order, and layout of the stacks shown in this embodiment. pattern. In the embodiment shown in FIG. 5, the two polycrystalline silicon layers Poly1 and Poly2 constitute a polysilicon-insulator-polysilicon (PIP) capacitor 26B. The polycrystalline silicon layer Poly2 constitutes the upper plate and the polycrystalline silicon layer Poly1. Form the lower plate. The PIP capacitor 26B can be used as the aforementioned capacitor C1 or C2. Therefore, the present invention can integrate the capacitor C1 and / or C2 in the thermopile sensing structure 30, which can greatly reduce the area and manufacturing of the overall temperature sensing module. cost.

Please refer to FIG. 6, which is a cross-sectional view of a third embodiment of a thermopile sensing structure with an integrated capacitor according to the present invention. The thermopile sensing structure 40 of the integrated capacitor in this embodiment is similar to the thermopile sensing structures 20 and 30 of the integrated capacitor in the previous embodiment. The difference is that the separation structure 27 of the thermopile sensing structure 40 includes a MIM capacitor 25A and PIP capacitor 26B. That is, the thermopile sensing structure 40 of this embodiment has both a MIM capacitor 25A and a PIP capacitor 26B. The structure of this embodiment can make a larger capacitor in a smaller area.

Compared with the prior art, the thermopile sensing structures 20, 30, and 40 of the integrated capacitor in this embodiment can eliminate the need for hanging capacitors and effectively reduce the module area. In addition, changing the capacitors from external to built-in also reduces The effect of transmitting noise is better than the prior art.

The present invention has been described above with reference to the preferred embodiments, but the above is only for making those skilled in the art easily understand the content of the present invention, and is not intended to limit the scope of rights of the present invention. In the same spirit of the invention, those skilled in the art can think of various equivalent changes. For example, the numbers of the metal layer and the channel layer of the present invention are not limited to those shown in the embodiment, and may be other numbers. All these can be deduced by analogy according to the teachings of the present invention. Therefore, the scope of the present invention should cover the above and all other equivalent changes. In addition, any embodiment of the present invention does not have to achieve all the objectives or advantages. Therefore, any one of the scope of the claimed patent should not be limited to this.

[Learning]

100‧‧‧Temperature Sensing Module

10‧‧‧ Thermopile sensing structure

11‧‧‧ substrate

11A‧‧‧ Cavity

12‧‧‧ Dielectric layer

13‧‧‧Combination layer

14‧‧‧ Filter

15‧‧‧ partition structure

16‧‧‧ Infrared sensor unit

161‧‧‧First induction structure

162‧‧‧Second induction structure

17‧‧‧Transistor circuit

C‧‧‧ cold end

M1 ~ M4‧‧‧metal layer

Poly1‧‧‧ polycrystalline silicon layer

H‧‧‧ hot end

V‧‧‧Channel layer

80‧‧‧Temperature sensor

81‧‧‧Noise Filter

82‧‧‧Noise Filter

C1 ~ C3‧‧‧Capacitor

Amp‧‧‧ Differential Amplifier

ADC‧‧‧ Analog Digital Converter

TS‧‧‧Temperature signal

VDS‧‧‧Voltage difference signal

〔this invention〕

200‧‧‧Temperature Sensing Module

20, 30, 40‧‧‧‧Integrated capacitor thermopile sensing structure

11‧‧‧ substrate

11A‧‧‧ Cavity

12‧‧‧ Dielectric layer

13‧‧‧Combination layer

14‧‧‧ Filter

25‧‧‧ divider structure

25A‧‧‧MIM capacitor

26‧‧‧ Separation Structure

26B‧‧‧PIP capacitor

27‧‧‧ divider structure

16‧‧‧ Infrared sensor unit

161‧‧‧First induction structure

162‧‧‧Second induction structure

17‧‧‧Transistor circuit

C‧‧‧ cold end

M1 ~ M4‧‧‧metal layer

M3A‧‧‧metal layer

Poly1‧‧‧ polycrystalline silicon layer

Poly2‧‧‧ polycrystalline silicon layer

H‧‧‧ hot end

V‧‧‧Channel layer

71‧‧‧Noise Filter

72‧‧‧ Noise Filter

80‧‧‧Temperature sensor

C1 ~ C3‧‧‧Capacitor

Amp‧‧‧ Differential Amplifier

ADC‧‧‧ Analog Digital Converter

TS‧‧‧Temperature signal

VDS‧‧‧Voltage difference signal

FIG. 1 is a functional block diagram of a prior art thermopile sensing structure applied to a temperature sensing module. Figure 2 shows a cross-sectional view of a prior art thermopile sensing structure. FIG. 3 shows a functional block diagram of the thermopile sensing structure of the present invention applied to a temperature sensing module. FIG. 4 is a cross-sectional view of a first embodiment of a thermopile sensing structure with integrated capacitors according to the present invention. FIG. 5 is a cross-sectional view of a second embodiment of a thermopile sensing structure with integrated capacitors according to the present invention. FIG. 6 is a cross-sectional view of a third embodiment of a thermopile sensing structure with integrated capacitors according to the present invention.

Claims (2)

A thermopile sensing structure with integrated capacitors includes: a substrate having a cavity; and an infrared sensing unit on the substrate. The infrared sensing unit has a first semiconductor stacking structure, and the first semiconductor stacking structure is located in the substrate. One end of the cavity is a hot end; and a partition structure is located around the infrared sensing unit, wherein the partition structure and the first semiconductor stack structure are close to each other at one end is a cold end, between the hot end and the cold end. The temperature difference generates a voltage difference signal, wherein the first semiconductor stack structure includes two layers of thermally conductive material indirectly connected to each other, the two layers of thermally conductive material indirectly connected to each other do not directly contact each other, and the separation structure is higher than the semiconductor stack structure to A function of separating the semiconductor stack structure from other parts is achieved, and one part of the separation structure constitutes at least one capacitor. The thermopile sensing structure of an integrated capacitor according to item 1 of the scope of the patent application, wherein the at least one capacitor is a metal-insulator-metal (MIM) capacitor or a polysilicon-insulation-polysilicon -Insulator-Polysilicon (PIP) capacitor.