Voltage divider circuit and semiconductor device using same

Abstract

The invention provides a voltage division circuit and a semiconductor device using the same. The voltage division circuit and the semiconductor device using the same give consideration to reduction of change of divided output voltage caused by time-dependent change of resistance value generated in a resistance element and suppression of area increase of a voltage division circuit region. The voltage division circuit includes: a first terminal; a second terminal; a partial voltage output terminal; a first resistor group in which a plurality of resistor elements are connected between the first terminal and the partial voltage output terminal; a second resistor group in which a plurality of resistor elements are connected between the second terminal and the partial voltage output terminal; a first metal film connected to the first terminal and covering a region including at least a part of the first resistor group in plan view; and a second metal film connected to the second terminal and covering a region including at least a portion of the second resistor group in plan view, the second metal film further covering a portion of the first resistor group in the voltage division circuit.

Description

Technical Field

[0001] The present invention relates to a voltage divider circuit and a semiconductor device using the same. Background Art

[0002] Secondary batteries used in portable devices deteriorate when overcharged or over-discharged, so in most cases, a semiconductor device is connected between the positive and negative terminals to monitor the battery voltage to protect the battery. For such semiconductor devices, the detection accuracy of about 10mV or less is required, and sometimes the deviation of the detection accuracy of each semiconductor device cannot be ignored.

[0003] As a technique for detecting a predetermined voltage, there is a technique for detecting by dividing a reference voltage or a voltage to be measured by a voltage dividing circuit and comparing the voltages. Various voltage dividing circuits have been proposed to improve the detection accuracy.

[0004] In semiconductor devices, a voltage divider circuit is sometimes used in which a plurality of resistance elements formed of polysilicon are connected in series. It is known that the resistance value of the polysilicon resistance element changes depending on the hydrogen content.

[0005] In the manufacturing process of semiconductor devices, a process containing hydrogen, such as a process for forming a silicon nitride film for passivation or an alloying process, is generally used. Therefore, hydrogen may enter the polysilicon resistor during the manufacturing process of the polysilicon resistor, causing a concern that the resistance value of each resistor may vary.

[0006] In order to suppress the intrusion of hydrogen, for example, in the invention described in Patent Document 1, a metal film is formed to entirely cover a plurality of resistor elements, thereby suppressing the intrusion of hydrogen into the resistor elements.

[0007] [Prior art literature]

[0008] [Patent Document]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 2008-211115 Summary of the invention

[0010] [Problems to be solved by the invention]

[0011] In one aspect of the present invention, an object is to provide a voltage divider circuit that achieves both reduction in variation in a divided output voltage caused by temporal variation in resistance value of a resistor and suppression of an increase in the area of ​​the voltage divider circuit region.

[0012] [Technical means to solve the problem]

[0013] A voltage divider circuit according to an embodiment of the present invention includes:

[0014] First terminal;

[0015] Second terminal;

[0016] Divider output terminal;

[0017] First resistor group, with a plurality of resistor elements connected between the first terminal and the divider output terminal;

[0018] Second resistor group, with a plurality of resistor elements connected between the second terminal and the divider output terminal;

[0019] First metal film, connected to the first terminal and covering at least a part of the region including the first resistor group in a top view; and

[0020] Second metal film, connected to the second terminal and covering at least a part of the region including the second resistor group in a top view. In the divider circuit,

[0021] the second metal film further covers a part of the first resistor group.

[0022] [Advantages of the Invention]

[0023] According to one aspect of the present invention, a divider circuit can be provided that takes into account both a reduction in the change in the divider output voltage caused by the temporal change in the resistance value generated in the resistor elements and an inhibition of an increase in the area of the divider circuit region. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a circuit diagram of the divider circuit according to an embodiment of the present invention.

[0025] Figure 2 is Figure 1 a schematic top view (perspective view) of the divider circuit shown.

[0026] Figure 3 is Figure 2 a schematic cross-sectional view taken along line III-III shown in

[0027] Figure 4 is Figure 2 a schematic cross-sectional view taken along line IV-IV shown in

[0028] Figure 5 is a graph showing the relationship between the change rate of the sheet resistance of a polysilicon resistor element and the voltage application time.

[0029] [Description of Reference Numerals]

[0030] 1: First terminal

[0031] 2: Second terminal

[0032] 100: Voltage dividing circuit

[0033] 101: Semiconductor substrate

[0034] 102: Field insulating film

[0035] 103: Polysilicon resistance element (resistance element)

[0036] 103a: High resistance part

[0037] 103b: Low resistance part

[0038] 104: Insulating film

[0039] 105: Contact hole

[0040] 106: First metal film

[0041] 107: Second metal film

[0042] 108: Metal wiring

[0043] 109: Second insulating film

[0044] 110: Silicon nitride film

[0045] L1: Length of resistance element

[0046] L11: Length of high resistance part

[0047] L12: Length of low resistance part

[0048] Q: Voltage dividing output terminal

[0049] R1n, R2m: Resistance elements

[0050] S1: First resistor group

[0051] S2: Second resistor group

[0052] W1: Width of resistance element Detailed implementation manners

[0053] The voltage dividing circuit according to an embodiment of the present invention is based on the following insights. The resistance element described in Patent Document 1 can suppress the intrusion of hydrogen to a certain extent. However, there is a concern that the resistance value changes over time according to the potential difference between the resistance element and the upper metal film.

[0054] On the other hand, the metal film disposed on the upper layer of the resistance element can be divided for each resistance element and connected to each resistance element covered by each divided metal film, thereby reducing the potential difference between the metal film and the resistance element. However, in the above structure, it is necessary to ensure the distance between adjacent metal films, and the area of the region where the metal film is not formed also increases as the number of divisions of the metal film increases. Therefore, the area of the voltage dividing circuit region formed by the resistance element and the metal film also increases.

[0055] Figure 5 It is a graph showing the relationship between the change rate of the sheet resistance of the polysilicon resistance element and the voltage application time.

[0056] Figure 5 The graph shown by the solid line in the figure is the characteristic when the potential of the polysilicon resistance element is higher than the potential of the upper metal film, and the sheet resistance of the polysilicon resistance element changes over time in the increasing direction. Figure 5 The graph shown by the dashed line in the figure is the characteristic when the potential of the polysilicon resistance element is lower than the potential of the upper metal film, and the sheet resistance of the polysilicon resistance element changes over time in the decreasing direction. In either case, the greater the potential difference between the upper metal film and the polysilicon resistance element, the greater the temporal change in the sheet resistance of the polysilicon resistance element. The inventors found that when the potential difference between the metal film and the resistance element reaches 40 V or more, such a change becomes obvious. It is considered that the reason is that due to the long-term application of the potential, unstable molecules between the resistance element and the insulating film will be polarized.

[0057] Therefore, the voltage dividing circuit according to an embodiment of the present invention is configured such that the first metal film covering a part of the first resistor group is connected to the first terminal, and the second metal film covering a part of the first resistor group and the second resistor group is connected to the second terminal.

[0058] Thereby, a voltage dividing circuit can be provided that takes into account both the reduction of the change in the voltage dividing output voltage caused by the temporal change in the resistance value generated in the resistance element and the suppression of the increase in the area of the voltage dividing circuit region.

[0059] Hereinafter, embodiments for implementing the present invention will be described in detail with reference to the accompanying drawings.

[0060] In addition, in the drawings, the same reference numerals are sometimes assigned to the same structural parts and repeated descriptions are omitted.

[0061] In addition, the X-axis, Y-axis, and Z-axis shown in the drawings are orthogonal to each other. Sometimes the Z-axis direction is referred to as the "height direction" or "thickness direction". Sometimes the surface on the +Z direction side of each member is referred to as the "front surface" or "upper surface", and the surface on the -Z direction side is referred to as the "back surface" or "lower surface". The so-called "top view" means observing each member from the +Z direction side toward the -Z direction side.

[0062] Furthermore, the accompanying drawings are schematic, and the ratios of width, depth, thickness, etc. are not as shown. The number, position, shape, structure, size, etc. of each component are not limited to the embodiments shown below, and may be set to the number, position, shape, structure, size, etc. that are preferred in terms of implementing the present invention.

[0063] (An example of an embodiment)

[0064] Figure 1 It is a circuit diagram of a voltage dividing circuit of an embodiment of the present invention.

[0065] As Figure 1 shown, the voltage dividing circuit 100 includes a first terminal 1, a second terminal 2, a voltage dividing output terminal Q, a first resistor group S1, a second resistor group S2, a first metal film 106, and a second metal film 107.

[0066] The first resistor group S1 has a plurality of resistor elements R1n (n is a natural number) connected in series. One end of the first resistor group S1 is connected to the first terminal, and the other end is connected to the second resistor group S2. The second resistor group S2 has a plurality of resistor elements R2m (m is a natural number) connected in series. One end of the second resistor group S2 is connected to the other end of the first resistor group S1, and the other end of the second resistor group S2 is connected to the second terminal 2. The connection portion of the first resistor group S1 and the second resistor group S2 is connected to the voltage dividing output terminal Q.

[0067] The voltage dividing circuit 100 outputs an output voltage Vout obtained by dividing the potential difference between the first terminal 1 and the second terminal 2 from the voltage dividing output terminal Q according to the ratio of the overall resistance value of the first resistor group S1 to the overall resistance value of the second resistor group S2. In the present embodiment, the first terminal is connected to the power supply voltage (VoltageDrain Drain, VDD) terminal of the semiconductor device having the voltage dividing circuit 100. In the present embodiment, the second terminal is connected to the ground (Ground, GND) terminal.

[0068] The first metal film 106 is formed on the upper layer of the resistor elements R11 to R1n - 1 of the first resistor group S1. The first metal film 106 is electrically connected to the first terminal 1 through the metal wiring 108.

[0069] The second metal film 107 is formed on the upper layer of the resistor element R1n of the first resistor group S1 and the resistor element R2m of the second resistor group S2. The second metal film 107 is electrically connected to the second terminal 2 through the metal wiring 108.

[0070] Figure 2 is Figure 1 a schematic top view (perspective view) of the voltage dividing circuit shown.

[0071] Each of the resistance elements R1n and R2m is a polysilicon resistance element 103 formed of a polysilicon film. The polysilicon resistance element 103 is formed with a length L1 and a width W1. Each polysilicon resistance element 103 has a high-resistance portion 103a and a low-resistance portion 103b. The low-resistance portion 103b of the polysilicon resistance element 103 is connected to the metal wiring 108 through a contact hole 105 and is also connected to the low-resistance portion 103b of an adjacent polysilicon resistance element 103. The low-resistance portion 103b is formed with a length L12 at both ends in the length direction of the polysilicon resistance element 103, and the high-resistance portion 103a is formed with a length L11 between the low-resistance portions 103b. Regarding the high-resistance portion 103a, the P-type or N-type impurity concentration is adjusted so as to achieve a desired resistance value.

[0072] On the upper layer of the resistance elements R11 to R1n-1 of the first resistance group S1, a first metal film 106 is formed so as to entirely cover the high-resistance portions 103a of the resistance elements R11 to R1n-1. The first metal film 106 is electrically connected to the first terminal 1 through the metal wiring 108. As a result, the resistance values of the resistance elements R11 to R1n-1 of the first resistance group S1 change over time in a decreasing direction.

[0073] On the upper layer of the resistance element R1n of the first resistance group S1 and the resistance elements R21 to R2m of the second resistance group S2, a second metal film 107 is formed so as to entirely cover the high-resistance portions 103a. The second metal film 107 is electrically connected to the second terminal 2 through the metal wiring 108. As a result, the resistance values of the resistance elements R21 to R2m of the second resistance group S2 and the resistance element R1n of the first resistance group S1 change over time in an increasing direction.

[0074] At this time, among the resistance elements covered by the second metal film 107, the potential difference between the resistance element R1n and the second metal film 107 is the largest, and the change over time of the resistance value of the resistance element R1n is the largest. Therefore, the resistance value of the entire first resistance group S1 changes over time in an increasing direction. Therefore, the resistance values of both the entire first resistance group S1 and the entire second resistance group S2 change over time in an increasing direction, and thus the change in the ratio of the resistance values can be reduced.

[0075] As a result, the change in the divided voltage output voltage caused by the change over time of the resistance value generated in the resistance element can be reduced. In addition, since the metal film covering the upper layer of the polysilicon resistance element is formed as two, i.e., the first metal film and the second metal film, and a gap of a single metal film can be formed, an increase in the area of the divided voltage circuit region can be suppressed.

[0076] Figure 3 is Figure 2 a schematic cross-sectional view taken along line III-III shown in Figure 4 is Figure 2 a schematic cross-sectional view taken along line IV-IV shown in

[0077] As Figure 3 and Figure 4 shown, the voltage dividing circuit 100 is formed on the upper layer of the field insulating film 102 formed on the surface of the semiconductor substrate 101. Each of the resistance elements R1n and R2m is a polysilicon resistance element 103 formed of a polysilicon film.

[0078] An insulating film 104 is formed on the upper layer of the polysilicon resistance element 103, and a first metal film 106, a second metal film 107, and a metal wiring 108 are formed on the upper layer of the insulating film 104. The low resistance portion 103b of the polysilicon resistance element 103 is connected to the metal wiring 108 through a contact hole 105. The first metal film 106, the second metal film 107, and the metal wiring 108 are formed of, for example, a stacked film of Al—Si—Cu, a stacked film of Al—Cu, or the like.

[0079] A second insulating film 109 is formed on the upper layers of the first metal film 106 and the second metal film 107, and a silicon nitride film 110 is formed on the upper layer of the second insulating film 109.

[0080] Here, the first metal film 106 covering the upper layers of the high resistance portions 103a of the resistance elements R11 to R1n−1 of the first resistance group S1, the second metal film 107 covering the upper layers of the high resistance portions 103a of the resistance element R1n of the first resistance group S1 and the resistance elements R2m of the second resistance group S2, and the metal wiring 108 are formed in the same layer. By forming the first metal film 106, the second metal film 107, and the metal wiring 108 in the same layer in this way, it is possible to reduce the deviation of the resistance value generated in the resistance element and the temporal change of the resistance value without increasing the manufacturing process.

[0081] As described above, the embodiments of the present invention have been described, but the present invention is not limited to these embodiments, and also includes designs and the like within the scope not departing from the gist of the invention.

[0082] For example, in the present embodiment, although a plurality of resistance elements R1n (n is a natural number) and R2m (m is a natural number) of the voltage dividing circuit are connected in series, they may also be connected in parallel in whole or in part. A circuit for adjusting the resistance value of a fuse element or a Metal Oxide Semiconductor (MOS) transistor or the like may also be connected to the resistance element. In addition, the regions covered by the first metal film are set as the resistance elements R11 to R1n-1, and the regions covered by the second metal film are set as the resistance elements R1n and R2m, but the positions of any resistance elements in the region of the first resistance group S1 may also be changed.

Claims

1. A voltage divider circuit, comprising: First terminal; Second terminal; Voltage divider output terminal; A first resistor group, wherein a plurality of resistor elements are connected between the first terminal and the voltage-dividing output terminal; A second resistor group, wherein a plurality of resistor elements are connected between the second terminal and the voltage-dividing output terminal; a first metal film connected to the first terminal and covering a region including at least a portion of the first resistor group in a plan view; as well as The second metal film is connected to the second terminal and covers a region including at least a portion of the second resistor group when viewed from above. The voltage divider circuit is characterized in that: The second metal film further covers a portion of the first resistor group.

2. The voltage divider circuit according to claim 1, wherein: The first metal film and the second metal film are formed in the same layer.

3. A semiconductor device comprising the voltage dividing circuit according to claim 1 or 2.

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