Electronic product including a component with a triangular leg column and corresponding manufacturing method

Abstract

An electronic product comprises a component having a first electrode, the first electrode comprising a first surface (103) and a column (104) extending from the first surface in a first direction, the column comprising three protrusions (106, 107, 108), the three protrusions forming an angle of about 120 degrees with each other around a center line (105) of the column, wherein the three protrusions meet at the center line (105) of the column, and the three protrusions are bent so that the column has a triangular cross-section in a plane perpendicular to the first direction. The present invention also relates to a system comprising the electronic product and a method for manufacturing the electronic product.

Description

Technical Field

[0001] The present invention relates to the field of integration and, more particularly, to electronic products, related semiconductor products and methods of manufacturing the same.

[0002] The invention more particularly relates to electronic components, such as capacitors, comprising electrodes. Background Art

[0003] Electronic components such as capacitors can be integrated into semiconductor products in various forms. For example, a planar capacitor can be formed on a semiconductor substrate by forming two planar electrodes separated by a dielectric layer. However, planar capacitors offer low capacitance density, which means that high-value capacitance will consume a considerable area of ​​the silicon.

[0004] To overcome this problem, it has been proposed to form a three-dimensional structure to increase the capacitance of the capacitor using the same surface area of ​​the semiconductor substrate. Capacitance densities in the order of farad per square meter have been achieved using three-dimensional capacitors. The manufacture of three-dimensional capacitors is made possible by introducing manufacturing methods such as deep reactive ion etching (DRIE), which is a well-known abbreviation, to form high aspect ratio structures.

[0005] Initially, it was proposed to form a matrix of deep holes in a silicon substrate. These holes can have openings on the order of 1 micron and depths of up to 17 microns. The silicon in which the holes are formed is doped (either before the formation of the holes or after in a deposition / diffusion process) so that the walls, bottom and top of the holes form the first electrodes. A dielectric layer is deposited in a conformal manner, and a second electrode is also deposited in a conformal manner to fill the holes and form a capacitor.

[0006] Although this structure is particularly robust (in terms of mechanical robustness), it is also limited by the etch rate of the process used to form the holes. This is caused by the reduced etch hole diameter and prevents deeper holes from being formed in an economical manner.

[0007] An alternative structure has been proposed in which the bottom electrode is formed in the shape of a silicon pillar. In other words, the structure is the opposite of the structure including a hole.

[0008] The etching rate is thus increased, but it has been observed that the mechanical robustness of this structure is poor, because the pillars may bend before the deposition of the dielectric and the upper electrode. The bent pillars may contact and adhere to each other. This may cause process problems that reduce the capacitance density, increase the capacitor leakage current and even reduce the breakdown voltage due to early failure.

[0009] Prior art document US 8283750 discloses a known three-dimensional capacitor structure using pillars with improved stability to reduce adhesion between the pillars. These pillars may have three protrusions so that their cross section is in the shape of a tripod.

[0010] The solution of document US 8283750 only allows obtaining pillars with an aspect ratio (the aspect ratio can be defined as the length of the pillar divided by the dimension of the smallest cross section measured perpendicular to its length) of about 30. It has been observed that larger aspect ratios still lead to bent pillars and excessive adhesion.

[0011] Documents US 2011 / 244302 and WO 2007 / 125510 also disclose known pillar structures.

[0012] The present invention has been made in view of the above-mentioned problems. Summary of the invention

[0013] The present invention provides an electronic product comprising a component having a first electrode, the first electrode comprising a first surface and a column extending from the first surface in a first direction, the column comprising three protrusions,

[0014] The three protrusions form an angle of about 120 degrees with each other around the centerline (105) of the column, wherein the three protrusions meet at the centerline (105) of the column, and

[0015] The three protrusions are bent in the same direction so that the column has a tripod cross-section in a plane perpendicular to the first direction.

[0016] A tripod is a shape comprising three legs or branches (protrusions of the present invention) that bend in the same direction (eg, clockwise or counterclockwise) around a center (here, the centerline of the column where the three protrusions meet).

[0017] As an example, the triskelion is often used as a Celtic symbol (with spiral legs).

[0018] The inventors of the present invention have observed that by bending the projections emerging from the post, the mechanical stability of the post is improved and this prevents bending of the post.

[0019] Choosing a triskelion shape (three bends with similar orientation) offers the advantage that a compact structure is obtained, which allows maintaining the surface area of ​​the first electrode, and such structures can be arranged in a matrix without loss of space between the structures, thereby maintaining a high capacitance density.

[0020] According to a specific embodiment, the pillars have an aspect ratio greater than 60 or preferably greater than 100.

[0021] It has been observed that aspect ratios of 60 or 100 can be achieved using pillars having a triskelion-shaped cross-section, whereas prior art methods at an aspect ratio of 50 result in too much sticking.

[0022] It should be noted that the aspect ratio of the pillars according to the present invention may be mainly limited by the cost of realizing deep structures (time / dark pillar (gaz)), the uniformity of the doping step, the uniformity of the subsequent dielectric deposition, the wafer warpage (after filling the deep trenches), and the final die thickness (the final die thickness may be less than 100 microns). It should be noted that in this specification, the aspect ratio is the length of the pillar (measured in a first direction - or the depth of the trench defining the pillar) divided by the smallest cross-sectional dimension measured perpendicular to its length direction (e.g., the width of the trench between two protrusions or two pillars).

[0023] According to a specific embodiment, the protrusions each include three segments, each of which has the same length (or approximately the same length) and joins at an angle of approximately 120 degrees.

[0024] It has been observed that this arrangement facilitates the placement of the pillars in a matrix of pillars.

[0025] According to a specific embodiment, the electronic product includes a plurality of pillars, each centerline of the pillars being arranged at a vertex of a planar equilateral triangle lattice formed in a plane perpendicular to the first direction.

[0026] This arrangement of the pillars is very advantageous with respect to the surface area of ​​the first electrode.This arrangement is possible because the tripod legs have a substantially triangular shape.

[0027] It has been observed that the matrix-like arrangement of the pillars also contributes to reducing wafer warpage or limiting stress, since the structure of each pillar extends in three directions and includes a bend. This limits the amount of parallel linear grooves aligned in the same direction, which could cause significant wafer warpage.

[0028] According to a specific embodiment, each of these pillars has the same orientation.

[0029] The pillars all extend in the first direction, and the protrusions of each pillar are arranged to obtain the same orientation. This facilitates the arrangement in a matrix form and increases the surface area of ​​the electrode (eg, the first electrode).

[0030] According to a particular embodiment, the minimum distance between two parallel sections of a protrusion of adjacent posts is approximately equal to the minimum distance between two parallel sections of a protrusion of the same post.

[0031] In this embodiment, the projection of the post comprises segments.

[0032] This minimum distance (between two parallel sections of two adjacent columns or between two parallel sections of the same column) may be a distance known to a person skilled in the art as a critical dimension (eg a critical dimension of a DRIE step).

[0033] This embodiment is advantageous for the consistency of subsequent deposition of materials. For example, if a capacitor is formed, the dielectric will be deposited in a conformal manner, and the second electrode will also be deposited in a conformal manner. This means that there will be no large spaces between the pillars to be filled with filler material.

[0034] According to a particular embodiment, the projections are formed by segments each having a width equal to said minimum distance, ie the minimum distance between two parallel segments of two adjacent columns or between two parallel segments of the same column.

[0035] According to a particular embodiment, the cross section of the column is the same along the entire length of the column in the first direction.

[0036] According to a specific embodiment, the pillars have a length greater than 60 microns.

[0037] According to a specific embodiment, the first electrode is a first electrode of a capacitor of the electronic product.

[0038] In other words, the dielectric layer may be deposited on the first electrode, for example in a conformal manner, and the second electrode may be deposited on the dielectric layer.

[0039] The present invention also provides a system comprising the electronic product as defined above.

[0040] The present invention also provides a method for producing an electronic component as defined above.

[0041] As an example, the method may include a DRIE step to form the pillar (or pillars). Furthermore, a photolithography step using a mask of a triskelion shape defining the cross section of the pillar may also be performed in the method. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Other features and advantages of the invention will become apparent from the following description of certain embodiments of the invention, given by way of illustration only and not limitation, with reference to the accompanying drawings, in which:

[0043] Figure 1A and Figure 1B A semiconductor substrate is shown in which pillars are to be formed according to an example;

[0044] Figure 2A , Figure 2B , Figure 2C and Figure 2D The column is shown;

[0045] Figure 3 The formation of a dielectric is shown; and

[0046] Figure 4 The formation of the second electrode is shown. DETAILED DESCRIPTION

[0047] An electronic product having a first electrode according to an embodiment will now be described. More precisely, steps for manufacturing the electronic product according to an embodiment will be described below.

[0048] Figure 1A is a top view of a semiconductor substrate 100, and in this example, the substrate is a silicon substrate, and Figure 1B is a cross-sectional view of the substrate 100. However, the present invention is not limited to silicon substrates and is also applicable to other types of materials.

[0049] The silicon substrate 100 includes a top surface 101 and a bottom surface 102 (the terms "top" and "bottom" are of course interchangeable).

[0050] A manufacturing process will be performed from the top surface 101 to form the first electrode. More precisely, a DRIE step may be performed on the top surface 101 to define the pillars formed at the first electrode, as will be described with reference to Figure 2A and Figure 2B Described.

[0051] Figure 2A 1 shows a top view of the substrate 100 after performing this DRIE step. This step may include a previous photolithography step using a mask on which a matrix of tripellets has been formed, so that the area covered due to the photolithography step is in the shape of a tripellet. The DRIE step is performed until a selected depth has been reached outside the covered area to achieve a Figure 2A The first surface 103 is visible on the top.

[0052] A plurality of pillars 104 are thus formed, and the pillars extend from the first surface in a first direction that is perpendicular to the first surface.

[0053] The column includes a center line 105 that passes through the center of each cross section of the column in the first direction. Because the cross sections of the column are the same along the first direction, the center line is perpendicular to the first surface 103.

[0054] Each post 104 is identical and includes three protrusions 106, 107 and 108. Figure 2B The structure of the column is described in more detail.

[0055] The pillars 104 are arranged such that each center line of the pillar is arranged at a vertex of a planar equilateral triangle lattice T formed in a plane perpendicular to the first direction. Figure 2A The lattice T is indicated by dashed lines in FIG. The lattice T is an equilateral triangle lattice, the angle of each triangle corner is equal (60 degrees) and is referenced by the same reference numeral α1.

[0056] The columns all have the same orientation and this Figure 2A A top view of the grid is visible. This facilitates the arrangement of the columns on the chessboard T. The distance between each center line of the columns is marked L2 and can be chosen so that a critical dimension is observed between two parallel segments of two protrusions belonging to two adjacent columns, respectively. This critical dimension is marked L1 in the figure and it is the minimum distance between two parallel segments of adjacent columns. It should be noted that this critical dimension L1 is preferably also the minimum distance between two parallel segments of a protrusion of the same column, as shown in the figure.

[0057] It should be noted that L1 is not only the minimum distance between pillars, but also the maximum distance between pillars, so that the formation of pillars means the formation of trenches with a width of L1. This facilitates the conformal deposition of subsequent materials.

[0058] Figure 2B Shown in more detail Figure 2A As can be seen in the figure, the column 104 includes three protrusions 106, 107 and 108, which meet at the center line 105 and form an angle α2 of about 120 degrees with each other. The three protrusions are also bent so that the column 104 has a three-legged cross-section in a plane perpendicular to the first direction (i.e., the plane of the figure).

[0059] The protrusion 106 comprises three segments 106a, 106b and 106c having the same length L3 and joined at an angle α2 of about 120 degrees. It should be noted that the angle between the protrusions and the angle between the segments of the protrusions are the same angle α2 of about 120 degrees.

[0060] The protrusion 107 also includes three segments 107a, 107b and 107c arranged similarly, and the protrusion 108 also includes three segments 108a, 108b and 108b arranged similarly.

[0061] All segments of the triskelion have a width L4, which can also be chosen to comply with the reference Figure 2A Describe the critical dimension L1.

[0062] In practice, one skilled in the art may select all distances L1 to L3 and width L4 to increase the surface area of ​​the first electrode formed by the surface of pillar 104 while respecting the limitations of the photolithography and DRIE steps.

[0063] As an example, L1 may be on the order of 1 micron, L2 may be on the order of 6 microns, L3 may be on the order of 1.5 microns, and L4 may be on the order of 1 micron.

[0064] It should be noted that although the posts 104 have well-defined segments and corners in this schematic diagram, actual posts formed on a substrate may have more rounded corners.

[0065] Figure 2C Shows Figure 2A 1 , showing a cross section of a structure of FIG. 1 , in which three pillars 104 are shown. As can be seen in this figure, the DRIE step has formed pillars having a length L5 and extending from the first surface 103 to the top surface 101.

[0066] The aspect ratio of the pillars may be calculated as L1 / L5, and this aspect ratio is preferably greater than 60. For example, the length of the pillars may be greater than 60 microns and the width L1 may be of the order of 1 micron.

[0067] Figure 2D It is a perspective view of the column 104 .

[0068] It should be noted that the pillar 104 and the first surface 103 can form a first electrode of a component such as a capacitor. The formation of the capacitor will be described below. It should be noted that the pillar 104 and the first surface can include doped silicon to behave as a metal electrode. The doping of these structures can be achieved before the pillar is formed or after the pillar is formed using a process that can be selected by those skilled in the art.

[0069] exist Figure 3 The above shows that after the dielectric formation step Figure 2C A dielectric layer 120 is formed on the top surface 101 , on the first surface 103 , and on the sidewalls of the pillars 104 in a conformal manner.

[0070] exist Figure 4 , after the second electrode 130 has been formed in a conformal manner Figure 3 The second electrode 130 may include doped polysilicon. A capacitor is formed by the first electrode (pillar and first surface), the dielectric 120 and the second electrode 130.

[0071] Because the pillars have a triskelion-shaped cross section, bending of the pillars is very limited and there is no adhesion between adjacent pillars even if the aspect ratio of the pillars is greater than 60. This allows to perform a conformal deposition of the dielectric 120 and the second electrode 120, which means a greater capacitance density.

[0072] In fact, because longer pillars can be produced using the structure of the above examples, the capacitance density is also improved.

[0073] The bending of the column can be simulated. As an example, the inventors have simulated the application of a 1.10 μm bending force at the free end of a column with a tripod cross section and a length of 60 μm (e.g., a column as disclosed in document US Pat. No. 8,283,750). -5A load of the order of Newtons may result in a displacement of the free end of the pillar in the order of 1.058 microns in a direction perpendicular to the direction in which the pillar extends: this displacement is too high to form a 60 micron pillar. In this example, the width of the protrusion is 1 micron.

[0074] Applying the same simulation to a column with three curved protrusions so that the column has a tripod cross-section results in a displacement of only 0.135 microns. In this example, the width of the protrusions is 1 micron.

[0075] Thus, while the prior art pillars showed acceptable displacement at lengths of about 50 microns, lengths of 100 microns are acceptable using the present invention. This means that the capacitance density can be doubled relative to the prior art, while the mechanical stability is multiplied by 8 for the same length.

[0076] Preferably, the length of the pillars may be less than about 120 microns, as it has been observed that in this case the displacement may be approximately 1 micron.

[0077] Furthermore, it should be noted that the cross-section of the pillars allows the pillars to be arranged in a matrix, for example as shown in FIG. Figure 2A Described, where the matrix is ​​a tessellation of equilateral triangles.

[0078] Other variants

[0079] 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 details of the specific embodiments. Various variations, modifications and developments of the above embodiments are possible within the scope of the appended claims.

Claims

1. An electronic product comprising a component having a first electrode, the first electrode comprising a first surface (103) and a column (104) extending from the first surface in a first direction, the column comprising three protrusions (106, 107, 108), The three protrusions form an angle of 120 degrees with each other around the centerline (105) of the column, wherein the three protrusions meet at the centerline (105) of the column, and It is characterized in that The three protrusions are bent in the same direction so that the column has a tripod cross-section in a plane perpendicular to the first direction, wherein the three protrusions each include three segments (106a, ..., 106b, ..., 106c), each of the three segments having the same length and joined at an angle of 120 degrees (α2).

2. The electronic product according to claim 1, wherein: The pillars have an aspect ratio greater than 60 or 100, the aspect ratio being the length of the pillar divided by the smallest cross-sectional dimension measured perpendicular to the length of the pillar.

3. The electronic product according to any one of claims 1 to 2, comprising a plurality of columns, each center line (105) of the columns being arranged at a vertex of a planar equilateral triangle lattice (T) formed in the plane perpendicular to the first direction.

4. The electronic product according to claim 3, wherein: Each of the plurality of pillars has the same orientation.

5. The electronic product according to claim 4, wherein: The minimum distance (L1) between two parallel sections of a protrusion of adjacent columns is equal to the minimum distance (L1) between two parallel sections of a protrusion of the same column.

6. The electronic product according to claim 5, wherein: The projections are formed by segments each having a width equal to the minimum distance (L1).

7. The electronic product according to any one of claims 1 to 2, wherein: The cross-section of the post is the same along the entire length of the post in the first direction.

8. The electronic product according to any one of claims 1 to 2, wherein: The length of the pillars is greater than 60 microns.

9. The electronic product according to any one of claims 1 to 2, wherein: The first electrode is a first electrode of a capacitor of the electronic product.

10. A system comprising the electronic product according to any one of claims 1 to 9.

11. A method for manufacturing an electronic product according to any one of claims 1 to 9.

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