Implementable semiconductor device and method for manufacturing the same

Abstract

The present invention relates to an implementable semiconductor device and a method for manufacturing the implementable semiconductor device, wherein the implementable semiconductor device comprises: an electrode (209) configured to contact biological tissue; and at least one capacitor (200), wherein the capacitor comprises a capacitor electrode (201) having a first surface, the first surface facing and contacting the electrode configured to contact the biological tissue.

Description

Technical Field

[0001] The present invention relates to the field of integration, and more particularly, to implantable semiconductor devices.

[0002] The present invention more precisely relates to implantable electronic devices having electrodes arranged to contact biological tissue. Background Art

[0003] Semiconductor devices can be inserted into a human or animal body to make contact with biological tissue (a part of a human or animal body). Typically, these devices include electrodes that provide electrical contact between the device and the biological tissue. The size and geometry of the electrodes can be selected to optimize the quality of the sensed signal when the signal is sensed.

[0004] The electrodes can then be used to sense electrical signals in biological tissue or also to stimulate biological tissue. Typically, the electrodes receive signals processed by electronic circuits, or transmit signals generated by electronic circuits. These electronic circuits may include, for example, a processor.

[0005] As will be appreciated by those skilled in the art, these implantable electronic devices must be biocompatible, and this requirement extends to the electronic circuits and electrodes. This means that there are restrictions on the materials that may be used, as well as the electrical functions of the device. It is often necessary to prevent the presence of continuous voltage in the body where the semiconductor device is implemented.

[0006] For example, it has been proposed to use a DC block connected between the electrode and the electronic circuit. This DC block is usually implemented using a capacitor. In order to perform the intended function, the capacitor is required to have a large capacitance value. Even if an electrical fault occurs, the capacitor must be able to ensure electrical isolation. Typically, the capacitance value of these capacitors is about tens of nanofarads, which makes it difficult to integrate bulky capacitors.

[0007] In order to accommodate the large volume, the capacitors are placed together with the electrodes and electronic circuits on a printed circuit board, on which components such as the capacitors and electrodes are connected using metal wires and placed next to each other.

[0008] This solution is not satisfactory since there is still the risk of a continuous voltage coming from the environment external to the device and appearing at the level of the capacitor.

[0009] The present invention has been accomplished in view of the above problems. Summary of the invention

[0010] The present invention provides an implementable semiconductor device comprising an electrode configured to contact biological tissue and at least one capacitor,

[0011] Therein, the capacitor comprises a capacitor electrode having a first surface, the first surface facing and (electrically) contacting an electrode configured to contact biological tissue.

[0012] Therefore, the electrode configured to contact the biological tissue contacts the capacitor electrode and is connected without using a metal wire extending on the printed circuit board. The electrode configured to contact the biological tissue is formed on the first surface of the capacitor electrode.

[0013] The electrode configured to contact the biological tissue is arranged to face the first surface of the capacitor electrode, so the distance between the two is minimized. This reduces the possibility of continuous voltage generated in the external environment contacting the electrode configured to contact the biological tissue.

[0014] It should be noted that "facing" means that the electrode configured to contact the biological tissue includes a surface facing and contacting the first surface of the capacitor electrode. The contact between the capacitor electrode and the electrode configured to contact the biological tissue can then be direct or indirect (for example, if there is a material layer between the two).

[0015] The first surface of the capacitor electrode is also substantially in the shape of an electrode configured to contact biological tissue.

[0016] The devices defined above are particularly suitable for deep brain stimulation, cardiac stimulation and spinal cord stimulation. For deep brain stimulation, miniaturization and high density are required to obtain higher accuracy in neuronal stimulation with less unwanted side effects. For cardiac stimulation, large areas and customized shapes are required. For spinal cord stimulation, miniaturization is required to avoid sensitive areas.

[0017] According to a particular embodiment, the electrode configured to be in contact with biological tissue comprises a layer of biocompatible conductive material facing said first surface of the capacitor electrode.

[0018] The layer of biocompatible conductive material may be deposited on the first surface of the capacitor electrode.

[0019] According to a particular embodiment, the capacitor electrode comprises a semiconductor region.

[0020] For example, the capacitor electrode can be a silicon substrate, preferably a doped silicon substrate. The remaining elements of the capacitor, the insulating layer and the second electrode can be formed on the substrate on the side opposite to the side having the first surface, the first surface facing and contacting the electrode configured to contact the biological tissue.

[0021] According to a specific embodiment, the capacitor is a three-dimensional capacitor and the capacitor electrode comprises at least one of pillars, grooves or holes on a side opposite to the side having the first surface, the first surface facing and contacting the electrode configured to contact biological tissue.

[0022] For example, if the capacitor electrode includes a semiconductor region or is in the form of a silicon substrate, the capacitor electrode can be etched to define pillars, trenches or holes. These etched structures can be filled with an insulating layer and a conductive material that forms a second electrode of the capacitor. This type of structure increases the surface area of ​​the capacitor, thereby increasing the capacitance.

[0023] The production of three-dimensional capacitors is described, for example, in document US Pat. No. 8,283,750.

[0024] It should be noted that the above three-dimensional structures (pillars, grooves, holes) can be arranged in an array. The array can substantially have the shape of an electrode configured to contact biological tissue.

[0025] According to a particular embodiment, the device comprises two stacked capacitors connected in series or in parallel, said capacitor electrodes being electrodes of two stacked capacitors.

[0026] For example, two stacked capacitors may be an arrangement designated using the acronym MIMIM (“Metal Insulator Metal”).

[0027] For example, capacitors connected in parallel can be used to increase the capacitance density in a device.

[0028] Capacitors connected in series provide greater safety because in the event of a capacitor failure, an open circuit can be maintained because a functioning capacitor is still present. Additionally, if a capacitor shorts, the electrode configured to contact biological tissue can still function, but with increased capacitance. This increased capacitance is detectable.

[0029] According to a particular embodiment, the electrode configured to be in contact with biological tissue comprises a conductive material selected from the group consisting of gold, nickel, tungsten, platinum, palladium, cobalt or an alloy of at least two materials from the group of conductive materials.

[0030] According to a particular embodiment, the device comprises an encapsulation layer comprising an insulating material selected from the group comprising aluminum oxide, parylene ((poly)p-xylene) or a combination of at least two materials from the group of insulating materials,

[0031] The encapsulation layer is arranged to at least partially (or completely) encapsulate the capacitor and leave at least the electrode configured to contact the biological tissue uncovered.

[0032] The encapsulation layer ensures that the only conductive areas of the device that may come into contact with biological tissue are electrodes configured to come into contact with biological tissue.

[0033] According to certain embodiments, the device comprises a plurality of electrodes configured to contact biological tissue,

[0034] Each electrode configured to contact the biological tissue is associated with at least one capacitor, the at least one capacitor comprising a capacitor electrode having a first surface facing and contacting the electrode configured to contact the biological tissue.

[0035] For example, a plurality of electrodes configured to contact biological tissue may be arranged in an array.

[0036] According to a particular embodiment, the device comprises a trench surrounding each electrode configured to be associated with biological tissue and its associated at least one associated capacitor.

[0037] It should be noted that if the capacitor electrode having the first surface in contact with the electrode configured to contact the biological tissue comprises a semiconductor substrate, the trench may extend over the entire thickness of the semiconductor substrate.

[0038] According to a particular embodiment, the trench is empty or comprises insulating material.

[0039] The present invention also provides a method for manufacturing an implementable semiconductor device, comprising:

[0040] forming at least one capacitor including a capacitor electrode having a first surface,

[0041] An electrode configured to contact the biological tissue is formed, the electrode facing and contacting the first surface of the capacitor electrode.

[0042] The method can be used to manufacture all embodiments of semiconductor devices that can be implemented as described above.

[0043] According to a specific embodiment, the method comprises depositing a layer of biocompatible conductive material on said first surface of the capacitor electrode.

[0044] According to a particular embodiment, the capacitor electrode comprises a semiconductor region.

[0045] According to a specific embodiment, the capacitor is a three-dimensional capacitor, and forming the capacitor includes: forming at least one of a column, a groove or a hole on a side opposite to a side having a first surface, the first surface facing and contacting an electrode configured to contact biological tissue.

[0046] According to a particular embodiment, the method comprises forming two stacked capacitors connected in series or in parallel, the capacitor electrodes being electrodes of the two stacked capacitors.

[0047] According to a specific embodiment, forming an electrode configured to contact biological tissue comprises depositing a layer of a conductive material selected from the group consisting of gold, nickel, tungsten, platinum, palladium, cobalt or an alloy of at least two materials from the group of conductive materials.

[0048] According to a particular embodiment, the method comprises forming an encapsulation layer comprising an insulating material, the insulating material comprising an insulating material selected from the group comprising aluminum oxide, parylene or a combination of at least two materials from the group of insulating materials,

[0049] The encapsulation layer is arranged to at least partially encapsulate the capacitor and leave at least the electrode configured to contact the biological tissue uncovered.

[0050] According to certain embodiments, the method includes forming a plurality of electrodes configured to contact biological tissue,

[0051] Each electrode configured to contact the biological tissue is associated with at least one capacitor, the at least one capacitor comprising a capacitor electrode having a first surface facing and contacting the electrode configured to contact the biological tissue.

[0052] According to certain embodiments, the method includes forming a trench surrounding each electrode configured to contact biological tissue and its associated at least one associated capacitor.

[0053] According to a particular embodiment, the trench comprises insulating material or is empty. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Further features and advantages of the invention will become apparent from the following description of certain embodiments of the invention given by way of example only and not by way of limitation, with reference to the accompanying drawings, in which:

[0055] Figure 1 is a perspective view of a device according to an example,

[0056] Figure 2 is a side view of two capacitors on which electrodes according to the present invention are to be formed,

[0057] Figure 3 is a side view of two capacitors formed with electrodes,

[0058] Figure 4 is a side view of an array of capacitors and electrodes,

[0059] Figure 5 is a side view of an alternative array of capacitors and electrodes,

[0060] Figure 6 is a perspective view of an example of a capacitor and electrodes,

[0061] Figure 7 Another array of capacitors and electrodes is shown, and

[0062] Figure 8 is a perspective view of an array of capacitors and electrodes. DETAILED DESCRIPTION

[0063] Various examples of how semiconductor devices and their associated fabrication methods may be implemented will now be described.

[0064] Figure 1 is a perspective view of a semiconductor device that may be implemented. The device may be a device suitable for deep brain stimulation, cardiac stimulation, and spinal cord stimulation.

[0065] In this figure, a capacitor 100 has been shown. The capacitor comprises a bottom electrode 101 which in this example comprises a doped silicon substrate. On top of the bottom electrode 101, a dielectric layer 102 has been formed. The dielectric layer 102 may comprise silicon dioxide.

[0066] The capacitor 100 is also provided with a top electrode 103, and the top electrode 103 may be, for example, a layer of conductive material deposited on the dielectric layer 102. In this example, the capacitor 100 is a two-dimensional planar capacitor.

[0067] In order to perform the above functions, the capacitor 100 is equipped with an electrode 104, which is configured to contact biological tissue. The electrode 104 includes a conductive material layer, which is selected to be able to conduct electricity and is biocompatible. For example, the electrode 104 includes a conductive material selected from the group consisting of gold, nickel, tungsten, platinum, palladium, cobalt, or an alloy of at least two materials in the group of conductive materials.

[0068] Electrode 104 is deposited on the bottom surface of bottom electrode 101. Thus, the two electrodes are in electrical contact, and in this example the electrical contact is direct. Furthermore, the deposition results in the bottom surface of bottom electrode 101 facing electrode 104 configured to be in contact with biological tissue. In addition, the two electrodes (or at least the bottom surfaces of electrode 101 and electrode 104) have substantially the same shape (circular in the example shown).

[0069] Therefore, since the distance between the electrode 104 and the electrode 101 is minimized, the safety of the implementable device is improved.

[0070] To control the electrode 104 or to receive a signal sensed by the electrode 104 , the top electrode 103 of the capacitor 100 is connected using a wired connection 105 to an electronic circuit 106 configured to perform processing of the signal sensed or emitted by the electrode 104 .

[0071] It should be noted that in prior art implementable devices, electrodes configured to be in contact with biological tissue are connected to associated capacitors using wired connections on a printed circuit board. This is avoided in the above examples.

[0072] Figure 2 2 is a side view of two stacked capacitors 200. The capacitor 200 is a three-dimensional capacitor. In fact, the capacitor 200 is formed using a semiconductor substrate (e.g., a substrate including a semiconductor material, preferably a substrate including doped silicon), and the substrate is also the bottom electrode 201 of the stacked capacitor 200.

[0073] The bottom electrode 201 has been etched to form the pillar 202, for example using a technique known to those skilled in the art, namely deep reactive ion etching (or DRIE). This method is particularly suitable for forming high aspect ratio structures such as the pillar 202. This etching step forms the bottom electrode 201.

[0074] A dielectric layer 203 is then deposited over and between the pillars 202 in a conformal manner.

[0075] An intermediate electrode 204 is also formed by depositing a conductive material in a conformal manner over and between the pillars 202 covered by the dielectric layer 203. A first capacitor is obtained.

[0076] To form the second capacitor, a second dielectric layer 205 is deposited in a conformal manner over and between the pillars 202 covered by the intermediate electrodes 204 .

[0077] This second dielectric layer 205 is then covered by a top electrode 206 formed by depositing a conductive material to fill the trenches formed between the pillars 202. Two stacked capacitors connected in series are then obtained.

[0078] The top electrode 206 may be connected to the reference Figure 1 The electronic circuit 106 described above is similar to the electronic circuit 106. In fact, Figure 1 implementation and Figure 2 The implementation is similar except that Figure 1 The planar capacitors are Figure 2 The three-dimensional stack of two capacitors is replaced.

[0079] Additionally, it should be noted that the passivation layer 207 is deposited on top of the device while leaving the top electrode 206 at least partially uncovered.

[0080] To form an implantable semiconductor device, an electrode configured to contact a biological material will be formed on the first surface F1 of the bottom electrode 201 .

[0081] Figure 3201 after forming a trench 208 that further defines the bottom electrode 201. Figure 2 The stacked capacitor 200. In this example, trenches 208 are formed in the entire thickness of the bottom electrode 201, and these trenches can be filled with an insulating material such as silicon dioxide.

[0082] On the bottom electrode 201 , an electrode configured to be in contact with biological tissue is formed on the first surface F1 by depositing a layer of biocompatible conductive material, forming an electrode 209 .

[0083] The thickness of the electrode 209 is on the order of several micrometers, and the electrode 209 may include a conductive material selected from the group consisting of gold, nickel, tungsten, platinum, palladium, cobalt, or an alloy of at least two materials in the group of conductive materials.

[0084] In addition to the passivation layer 207 and the trench 208, an additional encapsulation layer 210 is formed to encapsulate the capacitor and leave at least the electrode 209 configured to contact the biological tissue uncovered.

[0085] It should be noted that if the device comprises separate components such as electronic circuits, the packaging may involve only the capacitors.

[0086] The thickness of the encapsulation layer 210 may be, for example, on the order of 10 micrometers.

[0087] In addition, the encapsulation layer includes an insulating material selected from the group consisting of aluminum oxide, parylene, or a combination of at least two materials in the group of insulating materials.

[0088] As can be seen from the drawings, the capacitor is in direct contact with the electrode configured to be in contact with biological tissue, which improves the safety of the device.

[0089] exist Figure 4 , a side view of an array of capacitors and electrodes is shown. The capacitors are Figure 2 and Figure 3 The stacked capacitor 200 is similar to the stacked capacitor 400 described.

[0090] In addition, capacitor 400 is connected with reference Figure 2 and Figure 3 The trenches 408 described above are separated by similar trenches 208 .

[0091] The figure shows three electrodes 409a, 409b and 409c (similar to Figure 3 It should be noted that the array may include a greater number of electrodes 409i (where i is an index distinguishing the electrodes). For example, the array may be a matrix of N×M electrodes. Thus, the array extends in a direction perpendicular to the view.

[0092] The spacing between electrodes 409i (eg, the distance between consecutive grooves) may be of the order of at least 500 micrometers to obtain a capacitor with a sufficiently large capacitance value (of the order of about nanofarads).

[0093] exist Figure 5 An alternative array is shown above. In this example, trenches 508 are formed between the stacked capacitors, and these trenches remain empty, filled with voids.

[0094] While still leaving the trench 508 empty, an encapsulation layer 510 is deposited on the bottom and walls of the trench (similar to Figure 3 In practice, the thickness of the encapsulation layer may be lower on the walls of the trench 508 to maintain the presence of the voids.

[0095] The width of the trench may be of the order of 10 microns.

[0096] Figure 5 Embodiments of the invention enable flexible arrays to be arranged on non-planar surfaces.

[0097] Figure 6 is a perspective view of an example of a capacitor and electrodes. More precisely, in this figure, a pillar array 600 of a three-dimensional capacitor is shown. The electrodes configured to come into contact with biological tissue are located underneath and are not visible in the figure.

[0098] Circular insulating trenches 601 are formed around the capacitors and electrodes, but it should be noted that this additional insulation is not necessary when gaps / empty trenches are also used between adjacent capacitors and electrodes.

[0099] Figure 7 Shown with reference Figure 6 An example of a capacitor and electrode array 700 similar to the described capacitor and electrode array. As can be seen in this figure, the capacitor and the electrode are separated: a gap is used to separate the capacitor and the electrode.

[0100] In this figure, a metal line 701 for controlling the capacitor and the electrode or for receiving a signal sensed by the electrode is shown.

[0101] Various shapes can be used, for example, Figure 8 , a rectangular matrix arrangement 800 of capacitors and electrodes is shown.

[0102] Although the invention has been described above with reference to certain specific embodiments, it should be understood that the invention is not limited to the particularities of the specific embodiments. Many changes, modifications and developments can be made in the above embodiments within the scope of the appended claims.

Claims

1. An implementable semiconductor device comprising: an electrode (104, 209) configured to contact biological tissue; and at least one capacitor (100), wherein the capacitor comprises a capacitor electrode (101, 201) having a first surface (F1), the first surface facing and contacting the electrode configured to contact biological tissue, wherein the electrode configured to contact biological tissue comprises a layer of biocompatible conductive material deposited on the first surface facing the first surface of the capacitor electrode, wherein the capacitor electrode comprises a semiconductor region, and wherein the capacitor is a three-dimensional capacitor and the capacitor electrode comprises at least one of a column (202), a groove or a hole on a side opposite to a side having the first surface, the first surface facing and contacting the electrode configured to contact biological tissue.

2. The semiconductor device according to claim 1, wherein: The electrode configured to contact biological tissue includes a conductive material selected from the group consisting of gold, nickel, tungsten, platinum, palladium, cobalt, or an alloy of at least two materials in the group of conductive materials.

3. The semiconductor device according to claim 1 or 2, comprising an encapsulation layer (210), the encapsulation layer comprising an insulating material selected from the group consisting of aluminum oxide, polyparaxylene or a combination of at least two materials in the group of insulating materials, The encapsulation layer is arranged to at least partially encapsulate the capacitor and leave at least the electrode configured to contact the biological tissue uncovered.

4. An implementable semiconductor device according to claim 1 or 2, comprising a plurality of electrodes (409i) configured to contact biological tissue; Each electrode configured to be in contact with biological tissue is associated with at least one capacitor comprising a capacitor electrode having a first surface facing and contacting the electrode configured to be in contact with biological tissue.

5. The implementable semiconductor device of claim 4, comprising a trench (208, 408, 508) surrounding each electrode configured to contact biological tissue and at least one associated capacitor associated with the electrode.

6. The semiconductor device according to claim 5, wherein: The trenches are either empty or comprise insulating material.

7. A method for manufacturing an implementable semiconductor device, comprising: forming at least one capacitor (100) comprising a capacitor electrode (101, 201) having a first surface (F1), forming an electrode (104, 209) configured to contact biological tissue, the electrode configured to contact biological tissue facing and contacting the first surface of the capacitor electrode, and depositing a layer of biocompatible conductive material on the first surface of the capacitor electrode, wherein the capacitor electrode comprises a semiconductor region, and Wherein, the capacitor is a three-dimensional capacitor, and forming the capacitor includes: forming at least one of a column (202), a groove or a hole on a side opposite to a side having the first surface, the first surface facing and contacting the electrode configured to contact biological tissue.

8. The method according to claim 7, wherein: Forming the electrode configured to contact the biological tissue comprises depositing a layer of a conductive material selected from the group consisting of gold, nickel, tungsten, platinum, palladium, cobalt or an alloy of at least two materials from the group of conductive materials.

9. The method according to claim 7 or 8, comprising forming an encapsulation layer (210), the encapsulation layer comprising an insulating material selected from the group consisting of aluminum oxide, polyparaxylene or a combination of at least two materials in the group of insulating materials, The encapsulation layer is arranged to at least partially encapsulate the capacitor and leave at least the electrode configured to contact the biological tissue uncovered.

10. The method according to claim 7 or 8, comprising forming a plurality of electrodes (409i) configured to contact biological tissue, Each electrode configured to be in contact with biological tissue is associated with at least one capacitor comprising a capacitor electrode having a first surface facing and contacting the electrode configured to be in contact with biological tissue.

11. The method of claim 10, comprising forming a groove surrounding each electrode configured to contact biological tissue and at least one associated capacitor associated with the electrode.

12. The method according to claim 11, wherein: The trench includes insulating material or is empty.

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