阅读说明：本技术 可靠性改进的气密性金属化通孔 (Gas-tight metallized through-hole with improved reliability ) 是由 M·卡努勾 P·马宗达 C·A·欧克洛 朴娥英 S·C·波拉德 R·瓦迪 于 2020-01-20 设计创作，主要内容包括：根据本文所述的各个实施方式,一种制品包括玻璃或玻璃陶瓷基材,其具有第一主表面以及与第一主表面相对的第二主表面；以及在轴向方向上穿过基材而从第一主表面延伸轴向长度到达第二主表面的通孔。所述制品还包括设置在内表面上的氦气气密性粘附层；以及设置在通孔内的金属连接件,其中,所述金属连接件粘附于氦气气密性粘附层。所述金属连接件沿着通孔的轴向长度涂覆通孔的内表面,以限定从第一主表面到第一腔体长度的第一腔体,所述金属连接件在第一主表面处包括小于12μm的涂层厚度。另外,所述金属连接件沿着通孔的轴向长度涂覆通孔的内表面,以限定从第二主表面到第二腔体长度的第二腔体,所述金属连接件在第二主表面处包括小于12μm的涂层厚度,并且完全填充第一腔体与第二腔体之间的通孔。(According to various embodiments described herein, an article includes a glass or glass-ceramic substrate having a first major surface and a second major surface opposite the first major surface; and a through hole extending an axial length in an axial direction through the substrate from the first major surface to the second major surface. The article further comprises a helium gas-tight adhesion layer disposed on the inner surface; and a metal connector disposed within the through hole, wherein the metal connector is adhered to the helium gas-tight adhesion layer. The metal connector coats an inner surface of the through-hole along an axial length of the through-hole to define a first cavity from the first major surface to a first cavity length, the metal connector including a coating thickness of less than 12 μm at the first major surface. In addition, the metal connector coats an inner surface of the through-hole along an axial length of the through-hole to define a second cavity from the second major surface to the second cavity length, the metal connector including a coating thickness of less than 12 μm at the second major surface and completely filling the through-hole between the first cavity and the second cavity.)

1. An article of manufacture, comprising:

a glass or glass-ceramic substrate having a first major surface and a second major surface opposite the first major surface; and a through hole extending in an axial direction through the substrate from the first major surface to the second major surface for an axial length, the through hole defining:

an inner surface; and

a first axial portion, a third axial portion, and a second axial portion disposed between the first axial portion and the third axial portion along the axial direction;

a helium gas-tight adhesion layer disposed on the inner surface; and

a metal connection member disposed within the through hole, wherein the metal connection member is adhered to the helium gas-tight adhesion layer,

wherein:

the metal connector coating an inner surface of the through-hole along an axial length of the through-hole to define a first cavity from the first major surface to a first cavity length, the metal connector comprising a coating thickness of less than 12 μm at the first major surface;

the metal connector coating an inner surface of the through-hole along an axial length of the through-hole to define a second cavity from the second major surface to a second cavity length, the metal connector comprising a coating thickness of less than 12 μm at the second major surface; and is

The metal connecting piece completely fills the through hole between the first cavity and the second cavity.

2. The article of claim 1, wherein the metallic joint comprises an average coating thickness of less than 12 μ ι η in the first and third axial portions.

3. The article of claim 1 or claim 2, wherein the coating thickness within the through-hole at the first major surface and the coating thickness within the through-hole at the second major surface are each less than the coating thickness in the second axial portion.

4. The article of any one of the preceding claims, wherein the through-hole has a first diameter at the first major surface, a second diameter at the second major surface, and a third diameter in the second axial portion, and wherein the third diameter is less than the first diameter and the second diameter.

5. The article of claim 4, wherein the first diameter and the second diameter are each greater than or equal to 30 μ ι η and less than or equal to 80 μ ι η.

6. The article of claim 4 or claim 5, wherein the third diameter is greater than or equal to 10 μ ι η and less than or equal to 40 μ ι η.

7. The article of any of claims 4-6, wherein the coating thickness within the via at the first major surface and the coating thickness within the via at the second major surface are each less than half the third diameter.

8. The article of any one of the preceding claims, wherein a helium gas tight adhesive layer is disposed on the inner surface in the first and third axial portions, and wherein a helium gas tight adhesive layer is not disposed on the inner surface in the second axial portion.

9. The article of claim 8, wherein a helium gas tight adhesion layer is disposed along an entire perimeter of at least one of the first axial portion and the third axial portion.

10. The article of any one of the preceding claims, wherein helium gas tight adhesion layer comprises one or more of: ti, Cr, TiN, Ni, Ta, W and metal oxides.

11. The article of any one of the preceding claims, wherein the metal connector consists essentially of copper.

12. The article of any one of the preceding claims, wherein at least one of the first and second cavities is filled with one or more materials other than copper.

13. The article of any one of the preceding claims, wherein,the article is crack-free and has less than 10 ℃ before and after heating to a temperature of 450 ℃ and cooling to a temperature of 23 ℃^-5Helium permeability of atm cc/s.

14. The article of any one of the preceding claims, wherein the substrate comprises at least 90 wt.% silica.

15. A method of making a glass article, the method comprising:

depositing a helium gas-tight adhesion layer on a portion of an inner surface of a through-hole extending through a glass or glass-ceramic substrate, the substrate having a first major surface and a second major surface opposite the first major surface, and the through-hole extending through the substrate in an axial direction from the first major surface to the second major surface, the through-hole comprising a first axial portion, a third axial portion, and a second axial portion disposed between the first axial portion and the third axial portion, wherein the helium gas-tight adhesion layer is deposited on the inner surface of the through-hole;

depositing a metal connection on the first, second and third axial portions of the through-hole using an electroplating bath comprising a metal salt and a metal deposition inhibitor, wherein:

the metal connecting piece is adhered to the helium gas-tight adhesion layer;

the metal connector coating an inner surface of the through-hole along an axial length of the through-hole to define a first cavity from the first major surface to a first cavity length, and a coating thickness at the first major surface of less than 12 μm;

the metal connector coating an inner surface of the through-hole along an axial length of the through-hole to define a second cavity from the second major surface to a second cavity length, and a coating thickness at the second major surface of less than 12 μm; and is

The metal connecting piece completely fills the through hole between the first cavity and the second cavity.

16. The method of claim 15, wherein a plating rate of the metal connection in the second axial portion is higher than a plating rate in the first and third axial portions.

17. The method of claim 15 or claim 16, wherein the metal salt comprises a copper salt.

18. The method of any of claims 15-17, wherein depositing a metal connection comprises: at a rate of 1.5mA/cm or more²And less than or equal to 5mA/cm²The current density of (3) applies a current.

19. The method of any one of claims 15-18, wherein the metal deposition inhibitor comprises nitroblue tetrazolium chloride (NTBC), Methylthiazoltetrazolium (MTT), or tetranitroblue tetrazolium chloride (TNBT).

20. The method of any of claims 15-19, wherein a helium gas tight adhesion layer is deposited on the inner surface of the through hole in the first and third axial portions, and the helium gas tight adhesion layer is not disposed on the inner surface of the through hole in the second axial portion.

Technical Field

The present description relates generally to vias in glass and glass-ceramic substrates, and more particularly to hermetically sealed metallized vias in glass and glass-ceramic substrates.

Background

Glass and glass ceramic substrates with vias are desirable for many applications, including use in interposers, as electrical interfaces, RF filters, and RF switches. Glass substrates have become an attractive alternative to silicon and fiber reinforced polymers for these applications.

It is desirable to fill such vias with a conductor. Currently, copper is the most desirable material for such conductors. However, copper does not adhere well to glass. In particular, for some applications, a hermetic seal between copper and glass is desired. Such seals are difficult to obtain because copper does not adhere well to glass and has a large mismatch due to the coefficient of thermal expansion of many conductive materials (e.g., copper and many desirable glass and glass ceramic substrate compositions). Furthermore, when copper adheres to glass, the large thermal expansion coefficient mismatch of copper and glass causes radial and/or circumferential cracking of the glass when the glass article is subjected to high temperature processing. Specifically, when the glass article is cooled from high temperatures, copper shrinks faster than the glass and pulls the glass to which it is adhered, causing stress buildup and the formation of circumferential cracks due to the high stress buildup.

Therefore, there is a need for alternative methods for metallizing hermetically sealed through-glass vias.

Disclosure of Invention

According to a first aspect, an article includes a glass or glass-ceramic substrate having a first major surface and a second major surface opposite the first major surface; and a through hole extending in an axial direction through the substrate from the first major surface to the second major surface for an axial length, the through hole defining an inner surface; and a first axial portion, a third axial portion, and a second axial portion disposed between the first axial portion and the third axial portion along the axial direction. The article further comprises a helium gas-tight adhesion layer disposed on the inner surface; and a metal connector disposed within the through hole, wherein the metal connector is adhered to the helium gas-tight adhesion layer, wherein: the metal connector coating an inner surface of the through-hole along an axial length of the through-hole to define a first cavity from the first major surface to a first cavity length, the metal connector comprising a coating thickness of less than 12 μm at the first major surface; the metal connector coating an inner surface of the through-hole along an axial length of the through-hole to define a second cavity from the second major surface to a second cavity length, the metal connector comprising a coating thickness of less than 12 μm at the second major surface; and the metal connecting piece completely fills the through hole between the first cavity and the second cavity.

According to a 2 nd aspect, the glass article comprises the glass article of the 1 st aspect, wherein the metal connection comprises an average coating thickness of less than 12 μm in the first and third axial portions.

According to aspect 3, the glass article includes the glass article of aspect 1 or 2, wherein the coating thickness in the through-hole at the first major surface and the coating thickness in the through-hole at the second major surface are each less than the coating thickness in the second axial portion.

According to a 4 th aspect, the glass article comprises the glass article of any of the preceding aspects, wherein the first cavity length and the second cavity length are each greater than or equal to 3% and less than or equal to 97% of the axial length of the through hole.

According to a 5 th aspect, the glass article comprises the glass article of any of the preceding aspects, wherein the through hole has a first diameter at the first major surface, a second diameter at the second major surface, and a third diameter in the second axial portion, and wherein the third diameter is less than the first diameter and the second diameter.

According to a 6 th aspect, the glass article includes the glass article of the 5 th aspect, wherein the first diameter and the second diameter are each greater than or equal to 30 μm and less than or equal to 80 μm.

According to a 7 th aspect, the glass article includes the glass article of the 6 th aspect, wherein the first diameter and the second diameter are each greater than or equal to 40 μm and less than or equal to 60 μm.

According to an 8 th aspect, the glass article includes the glass article of the 7 th aspect, wherein the first diameter and the second diameter are each greater than or equal to 45 μm and less than or equal to 55 μm.

According to a 9 th aspect, the glass article comprises the glass article of any one of the 5 th to 8 th aspects, wherein the third diameter is greater than or equal to 10 μm and less than or equal to 40 μm.

According to a 10 th aspect, the glass article comprises the glass article of the 9 th aspect, wherein the third diameter is greater than or equal to 20 μm and less than or equal to 30 μm.

According to an 11 th aspect, the glass article includes the glass article of the 10 th aspect, wherein the third diameter is greater than or equal to 22 μm and less than or equal to 27 μm.

According to a 12 th aspect, the glass article comprises the glass article of any of the 5 th to 11 th aspects, wherein a ratio of the third diameter to the first diameter and a ratio of the third diameter to the second diameter is less than or equal to 1: 6.

According to a 13 th aspect, the glass article comprises the glass article of any of aspects 5-12, wherein the coating thickness within the through-hole at the first major surface and the coating thickness within the through-hole at the second major surface are each less than half the third diameter.

According to a 14 th aspect, the glass article comprises the glass article of any of the preceding aspects, wherein the helium gas-tight adhesion layer is disposed on the inner surface in the first axial portion and the third axial portion, and wherein the helium gas-tight adhesion layer is not disposed on the inner surface in the second axial portion.

According to a 15 th aspect, the glass article comprises the glass article of the 15 th aspect, wherein the helium gas tight adhesion layer is disposed along an entire perimeter of at least one of the first axial portion and the third axial portion.

According to a 16 th aspect, the glass article comprises the glass article of any preceding aspect, wherein the helium gas tight adhesion layer comprises one or more of: ti, Cr, TiN, Ni, Ta, W and metal oxides.

According to a 17 th aspect, the glass article comprises the glass article of any of the preceding aspects, wherein the helium gas tight adhesion layer has a thickness greater than or equal to 1nm and less than or equal to 500 nm.

According to a 18 th aspect, the glass article comprises the glass article of any preceding aspect, wherein the metal connector consists essentially of copper.

According to a 19 th aspect, the glass article comprises the glass article of any preceding aspect, wherein the metal connector hermetically seals the through hole.

According to a 20 th aspect, the glass article comprises the glass article of any of the preceding aspects, wherein at least one of the first cavity and the second cavity is filled with one or more materials other than copper.

According to a 21 st aspect, the glass article comprises the glass article of any preceding aspect, wherein the article is crack-free and has less than 10 ℃ before and after heating to a temperature of 450 ℃ and cooling to a temperature of 23 ℃^-5Helium permeability of atm cc/s.

According to a 22 nd aspect, the glass article comprises the glass article of any preceding aspect, wherein the substrate comprises at least 90 wt.% silica.

According to a 23 th aspect, a method of making a glass article comprises: depositing a helium gas-tight adhesion layer on a portion of an inner surface of a through-hole extending through a glass or glass-ceramic substrate, the substrate having a first major surface and a second major surface opposite the first major surface, and the through-hole extending through the substrate in an axial direction from the first major surface to the second major surface, the through-hole comprising a first axial portion, a third axial portion, and a second axial portion disposed between the first axial portion and the third axial portion, wherein the helium gas-tight adhesion layer is deposited on the inner surface of the through-hole; depositing a metal connection on the first, second and third axial portions of the through-hole using an electroplating bath comprising a metal salt and a metal deposition inhibitor, wherein: the metal connecting piece is adhered to the helium gas-tight adhesion layer; the metal connector coating an inner surface of the through-hole along an axial length of the through-hole to define a first cavity from the first major surface to a first cavity length, and a coating thickness at the first major surface of less than 12 μm; the metal connector coating an inner surface of the through-hole along an axial length of the through-hole to define a second cavity from the second major surface to a second cavity length, and a coating thickness at the second major surface of less than 12 μm; and the metal connecting piece completely fills the through hole between the first cavity and the second cavity.

According to a 24 th aspect, the method comprises the method of the 23 th aspect, wherein the plating rate of the metal connection in the second axial portion is higher than the plating rate in the first and third axial portions.

According to a 25 th aspect, the method comprises the method of the 23 th or 24 th aspect, wherein the metal salt comprises a copper salt.

According to a 26 th aspect, the method comprises the method of any one of the 23 th to 25 th aspects, wherein depositing the metal connection comprises: at a rate of 1.5mA/cm or more²And less than or equal to 5mA/cm²The current density of (3) applies a current.

According to an 27 th aspect, the method comprises the method of any one of the 23 th to 26 th aspects, wherein the metal deposition inhibitor comprises nitroblue tetrazolium chloride (NTBC), methylthiazoltetrazolium chloride (MTT) or tetranitroblue tetrazolium chloride (TNBT).

According to a 28 th aspect, the method comprises the method of any one of the 23 th to 27 th aspects, further comprising filling at least one of the first cavity and the second cavity with one or more materials other than copper.

According to a 29 th aspect, the method includes the method of any one of the 23 th to 28 th aspects, wherein the helium gas-tight adhesive layer is provided on the inner surface of the through hole in the first axial portion and the third axial portion, and the helium gas-tight adhesive layer is not provided on the inner surface of the through hole in the second axial portion.

Drawings

FIG. 1 shows a perspective view of a substrate having a through-hole;

FIG. 2 shows a cross-sectional view of the via taken along line 2-2' of FIG. 1;

FIG. 3 shows the through hole of FIG. 2 with emphasis on features of the metal connector;

FIG. 4 shows a flow chart of a process of manufacturing a via;

FIG. 5A shows the stress-strain relationship of an elastic perfect plasticity model used for modeling;

FIG. 5B shows the temperature dependent copper yield stress for modeling;

FIG. 6 shows a plot of modeled first maximum principal stress and modeled maximum radial stress (y-axis) for various copper coating thicknesses (x-axis);

FIG. 7 shows a graph of the percentage of through holes with cracks (y-axis) as a function of the copper coating thickness (x-axis);

FIG. 8A illustrates an exemplary via having a copper coating thickness of less than 12 μm and no microcracks;

FIG. 8B illustrates an exemplary via having a copper coating thickness of greater than or equal to 12 μm and exhibiting circumferential microcracking;

FIG. 9 is an X-ray CT scan of an exemplary metallized TGV; and is

FIG. 10A shows an SEM image of the exemplary metallized TGV of FIG. 9 to verify a copper coating thickness distribution curve;

FIG. 10B shows an SEM image of the waist of the exemplary metallized TGV of FIG. 9 to verify a copper coating thickness distribution curve; and is

Fig. 10C shows an SEM image of the entrance of the exemplary metalized TGV of fig. 9 to verify the copper coating thickness profile.

Detailed Description

Unless specifically stated otherwise, any methods described herein should not be construed as requiring that their steps be performed in a particular order, or that any apparatus be specifically oriented. Accordingly, if a method claim does not actually recite an order to be followed by its steps, or any apparatus claim does not actually recite an order or orientation to individual components, or no further limitation to a specific order is explicitly stated in the claims or specification, or a specific order or orientation is recited to components of an apparatus, then no order or orientation should be inferred, in any respect. This applies to any possible non-expressive basis for interpretation, including: a logical problem related to the arrangement of steps, a flow of operations, an order of components, or an orientation of components; obvious meaning derived from grammatical organization or punctuation, and quantity or type of implementation described in the specification.

As used herein, the singular forms "a", "an" and "the" include plural references unless the context clearly dictates otherwise. Thus, for example, reference to "a" or "an" element includes aspects having two or more such elements, unless the context clearly indicates otherwise. Also, the word "or" should be construed as inclusive (e.g., "x or y" means one or both of x or y) when used without "either" following the word "or" (or other similar language indicating that "or" is expressly intended as exclusive, e.g., only one of x or y, etc.).

The term "and/or" should also be construed as inclusive (e.g., "x and/or y" means one or both of x or y). Where "and/or" is used as a connection of a group of three or more items, the group should be interpreted as including only one item, all items together, or any combination or number of items. Also, terms used in the specification and claims, such as having, including, containing, and comprising, are to be understood as being synonymous with the terms including and comprising.

As used herein, the term "about" means that amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but may be approximate and/or larger or smaller as desired, such as to reflect tolerances, conversion factors, rounding off, measurement error and the like, and other factors known to those of skill in the art. When the term "about" is used to describe a numerical value or an end-point of a range, the disclosure should be understood to include the specific numerical value or end-point referred to. Whether or not the numerical values or endpoints of ranges in the specification are listed as "about," the numerical values or endpoints of ranges are intended to include both embodiments: one modified with "about" and the other not modified with "about". It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

The disclosed ranges are to be understood to encompass any and all subranges or individual values encompassed within each range and support is provided for claims that recite those subranges or individual values. For example, a stated range of 1 to 10 should be understood as any and all subranges between the minimum value of 1 and the maximum value of 10 or individual values therebetween (including and/or excluding endpoints), and support is provided for claims describing these subranges or individual values; that is, all subranges beginning with a minimum value of 1 or more and ending with a maximum value of 10 or less (e.g., 5.5 to 10, 2.34 to 3.56, etc.) or any value from 1 to 10 (e.g., 3, 5.8, 9.9994, etc.).

Glass and glass ceramic substrate with through-holes

Glass and glass ceramic substrates with through-holes are desirable for a variety of applications. For example, a 3D interposer with Through Package (TPV) interconnects that connect logic devices on one side of the interposer and memory on the other side of the interposer is desirable for high bandwidth devices. The substrates currently selected are organic or silicon. Organic interposers have problems with poor dimensional stability, while silicon wafers are expensive and have problems with high dielectric loss. Glass and glass-ceramics can be excellent substrate materials due to their relatively low dielectric constants, their thermal stability, and low cost. Glass or glass ceramic substrates with Through Glass Vias (TGVs) have some applications. These vias typically need to be completely filled or conformally filled with a conductive metal (e.g., copper) to form a metal connection to provide an electrical pathway. Copper is a particularly desirable conductive metal.

Fig. 1 shows an article comprising a substrate 100, schematically depicted in partial perspective view. The substrate 100 includes a first major surface 102 and a second major surface 104 opposite the first major surface 102. A plurality of through-holes 110 extend through the body of the substrate 100 from the first major surface 102 to the second major surface 104. The metal connector 150 fills the through-hole 110. It is understood that any number of vias 110 may extend through the substrate 100 in any arrangement. The coordinate mark 101 shows the direction of the axial dimension z, which is perpendicular to the plane of the first main surface 102 and the second main surface 104. Unless otherwise specified, the "length" of the through-hole or metal connection is in the axial dimension z. The thickness t of the substrate 100 is in the axial dimension and can be any suitable thickness depending on the application.

In various embodiments, substrate 100 may comprise any suitable glass or glass-ceramic substrate. In some embodiments, high silica glass or glass ceramic substrates are desirable for certain applications due to their dielectric properties. For example, glass or glass-ceramic materials having a silica content of 50 mole%, 55 mole%, 60 mole%, 65 mole%, 70 mole%, 75 mole%, 80 mole%, 85 mole%, 90 mole%, 95 mole%, or 100 mole%, or any range having any two of these values as endpoints, can be used. Glass or glass-ceramic materials having a silica content of 50 to 100 mole%, or 75 to 100 mole%, may be used. In some embodiments, the substrate comprises at least 90% by weight silica.

For substrates having the dimensions described herein, it is particularly difficult to obtain a hermetically sealed via in high silica glass with a copper metal connector for at least two reasons. First, copper does not adhere well to glass. Second, the CTE mismatch between copper and high silica glass is particularly large. Despite these reasons, the articles and methods described herein achieve a hermetic seal by providing an excellent stress relief mechanism.

Fig. 2 shows an article comprising a substrate 100, schematically depicted as a cross-sectional view of fig. 1 along line 2-2'. Fig. 2 shows the substrate 100, the coordinate mark 101, the first main surface 102, the second main surface 104, the through-hole 110 and the metal connector 150 of fig. 1. The inner surface 114 of the through bore 110 is divided into a first axial portion 116, a second axial portion 118, and a third axial portion 120. In the first and third axial portions 116, 120, a helium gas tight adhesion layer 122 is provided on the inner surface 114 of the through hole 110. In an embodiment, a helium gas tight adhesive layer 122 is provided on the inner surface 114 of the through hole 110 along the entire perimeter of at least one of the first and third axial portions 116, 120. The helium gas tight adhesion layer 122 is not present in the second axial portion 118.

The phrase "helium gas tight adhesion layer" as used herein means less than 10^-5atm cc/s, or even less than 10^-8a permeability of atm cc/s, which provides a hermetic adhesion layer to helium gas, measured using a vacuum-based helium leak detection test system by connecting the metal connections 150 to the inner surface 114 of the vias 110. Suitable helium gas tight adhesion layer materials include metals such as titanium (Ti), chromium (Cr), tantalum (Ta), vanadium (V), nickel (Ni), tungsten (W), or metal oxides such as titanium oxide, tungsten oxide, and manganese oxide, or nitrides such as titanium nitride (TiN) and tantalum nitride (TaN). In various embodiments, the helium gas-tight adhesion layer comprises titanium (Ti). The helium gas-tight adhesion layer has a thickness of 1nm or more and 500nm or less. For example, in some embodiments, the helium gas tight adhesion layer has a thickness of about 100 nm.

In some embodiments, for example, in partially bonded embodiments, the axial length of the first axial portion 116 or the third axial portion 120 may be referred to as the "adhesion length" because this length is the length of the through-hole 110 along which the metal connector 150 adheres securely to the substrate 100. In some such embodiments, the adhesion length is greater than or equal to 5 μm and less than or equal to 148 μm. The adhesion length may be greater than or equal to 10 μm and less than or equal to 135 μm, greater than or equal to 10 μm and less than or equal to 130 μm, greater than or equal to 10 μm and less than or equal to 125 μm, greater than or equal to 10 μm and less than or equal to 120 μm, greater than or equal to 10 μm and less than or equal to 115 μm, greater than or equal to 15 μm and less than or equal to 140 μm, greater than or equal to 15 μm and less than or equal to 135 μm, greater than or equal to 15 μm and less than or equal to 130 μm, greater than or equal to 15 μm and less than or equal to 125 μm, greater than or equal to 15 μm and less than or equal to 120 μm, greater than or equal to 20 μm and less than or equal to 140 μm, greater than or equal to 20 μm and less than or equal to 135 μm, greater than or equal to 20 μm and less than or equal to 130 μm, greater than or equal to 20 μm and less than or equal to 125 μm, greater than or equal to 25 μm and less than or equal to 140 μm, greater than or equal to 25 μm and less than or equal to 135 μm, greater than or equal to 25 μm and less than or equal to 130 μm, greater than or equal to 130 μm and less than or equal to 140 μm, greater than or equal to 30 μm and less than or equal to 35 μm, or greater than or equal to 35 μm and less than or equal to 140 μm. In some embodiments, the adhesion length is greater than or equal to 40 μm and less than or equal to 140 μm, greater than or equal to 40 μm and less than or equal to 130 μm, greater than or equal to 40 μm and less than or equal to 120 μm, greater than or equal to 40 μm and less than or equal to 110 μm, greater than or equal to 40 μm and less than or equal to 100 μm, greater than or equal to 40 μm and less than or equal to 90 μm, greater than or equal to 40 μm and less than or equal to 80 μm, greater than or equal to 40 μm and less than or equal to 70 μm, or greater than or equal to 40 μm and less than or equal to 60 μm. For example, the adhesion length may be about 40 μm, 50 μm, 60 μm, or 70 μm. It is contemplated that other attachment lengths may be used in various embodiments.

The helium gas tight adhesion layer 122 is not present in the second axial portion 118 and therefore the metal connection 150 is less strongly bonded to the inner surface 114 along the second axial portion 118. The through-hole 110 has a through-hole length 130 in the axial direction. The through-hole 110 has a first diameter 132a at the first major surface 102, a second diameter 132b at the second major surface 104, and a third diameter 132c in the second axial portion 118.

Shape of through hole

In the embodiments described herein, the through-hole 110 has a tapered inner surface 114 that tapers or narrows from a first diameter 132a at the first major surface 102 and a second diameter 132b at the second major surface 104 to a waist 125, the waist 125 having a waist diameter equal to the third diameter 132 c. As used herein, the "waist" of a through-hole refers to the portion of the through-hole of variable diameter having the smallest diameter. The diameter of the through-hole 110 varies depending on the axial position. The overall "diameter" of the through-hole 110 is the maximum diameter. Unless otherwise specified, "through hole diameter" refers to the maximum diameter. When the through-hole 110 is not circular, the "diameter" of the through-hole 110 is the diameter of a circle having the same sectional area as the through-hole 110 in a plane perpendicular to the axial direction.

The through bore waist 125 has a minimum diameter along the axial length of the through bore. As a percentage of the first diameter, the diameter of the through-hole waist may be 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, or any range having two of these values as endpoints, inclusive. As a percentage of the second diameter, the diameter of the through-hole waist may be 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, or any range having any two of these values as endpoints, inclusive. The diameter of the through-hole waist may be 75% or less of the first diameter, and the diameter of the through-hole waist may be 75% or less of the second diameter. The diameter of the through-hole waist may be 20% to 50% or less of the first diameter, and the diameter of the through-hole waist may be 20% to 50% or less of the second diameter. In various embodiments, the third diameter 132c, or via waist, is greater than or equal to 10 μm and less than or equal to 40 μm. The third diameter 132c may be greater than or equal to 20 μm and less than or equal to 30 μm, or greater than or equal to 22 μm and less than or equal to 27 μm. For example, the third diameter 132c may be 10 μm, 15 μm, 20 μm, 22 μm, 25 μm, 27 μm, 30 μm, 35 μm, or 40 μm. In various embodiments, the ratio of the third diameter 132c to the first diameter 132a is less than or equal to 1:6, less than or equal to 1:5, less than or equal to 1:4, less than or equal to 1:3, or less than or equal to 1:2, and/or the ratio of the third diameter 132c to the second diameter 132b is less than or equal to 1:6, less than or equal to 1:5, less than or equal to 1:4, less than or equal to 1:3, or less than or equal to 1: 2.

The vias 110 may have any suitable via length 130. By way of non-limiting example, the thickness of the substrate 100 (and the via length 130) may be 10 μm, 60 μm, 120 μm, 180 μm, 240 μm, 300 μm, 360 μm, 420 μm, 480 μm, 540 μm, 600 μm, 720 μm, 840 μm, 960 μm, 1080 μm, 1500 μm, 2000 μm, or any range having any two of these values as endpoints, including endpoints. In some embodiments, the thickness t and via length are 10 μm to 2000 μm, 200 μm to 400 μm, or 240 μm to 360 μm.

The through-hole 110 may have any suitable first and second diameters 132a, 132 b. As non-limiting examples, these diameters may be 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, or any range having any two of these values as endpoints, inclusive. In some embodiments, the via diameter can be greater than or equal to 30 μm and less than or equal to 80 μm, greater than or equal to 40 μm and less than or equal to 60 μm, or greater than or equal to 45 μm and less than or equal to 55 μm. The first diameter 132a may be the same as or different from the second diameter 132 b. As described above, the first diameter 132a and the second diameter 132b are each larger than the third diameter 132 c.

The axial lengths of the first, second and third axial portions may have any suitable length. In various embodiments, the length is selected to achieve a combination of low maximum principal stress and helium gas tightness. In some embodiments, the lengths of the first and third axial portions are independently selected from 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, and 40% of the length of the through-hole, or any range having any two of these values as endpoints, including endpoints. The length of the second axial portion is 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, or 98% of the length of the through-hole, or any range having any two of these values as endpoints, including endpoints. The length of the first and third axial portions may be 2% to 40% of the length of the through hole, while the length of the second axial portion is 20% to 96% of the length of the through hole.

In various embodiments the via is a high aspect ratio via, wherein the via length is 240 μm to 360 μm and the via diameter is 40 μm to 60 μm. As used herein, "aspect ratio" refers to the ratio of the average thickness of the glass substrate to the average diameter of the through-hole. By "high aspect ratio" is meant an aspect ratio greater than 3. Without being bound by theory, for such vias, first and third axial portions having lengths of 20 μm, 25 μm, 30 μm, 35 μm, and 40 μm, or any range of any two of these values as endpoints (including endpoints), may be expected to achieve reduced stress, although other lengths are also contemplated. The length of the second axial portion constitutes the remainder of the length of the through hole.

In some embodiments, the first axial portion includes an intersection of the through-hole with the first major surface and the second axial portion includes an intersection of the through-hole with the second major surface.

The through-holes 110 optionally have rounded corners 124 at the inner edges to reduce stress concentrations, including at the through-hole waist 125. As used herein, "rounded corners" refer to rounded corners along the interior corners of the via 110. Such rounded corners may be used at any edge of the via shape. Rounded fillet 124 may have any suitable diameter, e.g., 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, or any range having any two of these values as endpoints, inclusive. Other diameters may be used.

The through-hole 110 has an inner surface 114, the inner surface 114 having two different slopes, and a slope variation at the rounded corner 124. The through-hole 110 may have a single bevel, two bevels as shown in fig. 2, or a more complex shape from each of the first and second major surfaces 102, 104 to the waist 125. One or more of the bevels may be perpendicular to the first and second major surfaces 102, 104, as shown in fig. 2.

Metal connecting piece

Fig. 3 shows the same through-hole 110 as fig. 2, but it is labeled to illustrate a portion of the metal connector 150. The metal connector 150 defines a first cavity 152 within the first axial portion 116 and a second cavity 154 within the third axial portion 120. The first cavity 152 is separated from the second cavity 154 by a fill portion 156 within the second axial portion 118. The first cavity 152 has a first cavity length 153 in the axial dimension and the second cavity 154 has a second cavity length 155 in the axial dimension. At each location in the axial dimension along first cavity length 153 and second cavity length 155, metal connector 150 coats inner surface 114 but does not completely fill through-hole 110. The fill portion 156 has a fill length 157 in the axial dimension. The metal connector 150 has a coating thickness 158 along a first cavity length 153 and a second cavity length 155. Although illustrated as a constant thickness (conformal layer), the coating thickness 158 can vary with axial position and distance from the first major surface and/or the second major surface.

In various embodiments, the metallic interconnect 150 has a coating thickness 158 of less than 12 μm at the first and second major surfaces 102 and 104. For example, the metal connector 150 has a coating thickness 158 of 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, or 11 μm at the first major surface 102 and at the second major surface 104. In some embodiments, the metallic interconnect 150 has an average coating thickness of less than 12 μm in the first and second axial portions. In some embodiments, the metal connection 150 has an average coating thickness of less than 12 μm over the length from the first major surface 102 to the adjacent rounded corner 124 and over the length from the second major surface 104 to the adjacent rounded corner 124.

The use of the through-hole 110 having a tapered shape, i.e., the through-hole 110 having the waist 125 with a diameter narrower than the first diameter 132a and the second diameter 132b, enables the manufacture of the metal connecting member 150 having the unique geometry shown in fig. 2 and 3. Specifically, the shape has a first cavity 152 and a second cavity 154 extending from the first major surface 102 and the second major surface 104, respectively. Meanwhile, the metal connector 150 includes a filling portion 156 near the waist 125. The geometry of the metal connector 150 allows for a hermetic seal to the substrate 100 and has stress relief freedom not available with other geometries. In particular, the helium gas-tight adhesion layer 122 forms a gas-tight seal between the metal connector 150 and the substrate 100 at the first and second major surfaces 102 and 104, respectively, for the axial lengths of the first and third axial portions 116 and 120. The fill portion 156 completes the hermetic seal such that gases and liquids cannot pass through the through-hole 110 between the first and second major surfaces 102, 104. The lack of adhesion in the second axial portion 118 provides an additional degree of freedom for the metal connection 150 to relieve stress during thermal cycling. Additionally, the first cavity 152 and the second cavity 154 provide another degree of freedom for stress relief. These freedom of stress relief allows the metal connection to withstand thermal cycling without causing the substrate to fail due to differences in the thermal expansion coefficients of the metal connection and the substrate.

In some embodiments, the first and second cavities 152, 154 extend far enough into the through-hole 110 so that they overlap the second axial portion 118. This overlap allows the axial portion of the metal connector 150 to be neither bonded to the substrate 100 nor filled. This geometry provides a further mechanism for stress relief.

The first cavity length can be 3%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 60%, 70%, 80%, 90%, 95%, or 97% of the axial length of the through-hole 110, or any range of any two of these values as endpoints, including endpoints. The second cavity length 155 may be 3%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 60%, 70%, 80%, 90%, 95%, or 97% of the axial length of the through-hole 110, or any range of any two of these values as endpoints, including endpoints. The second cavity length 155 may be the same or different than the first cavity length 153. In various embodiments, first cavity length 153 and second cavity length 155 are each greater than or equal to 10 μm and less than or equal to 150 μm. For example, first cavity length 153 and second cavity length 155 may each be 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, or any range having any two of these values as endpoints, including endpoints.

The filling portion 156 has an axial length that constitutes the difference between the through-hole axial length 130 (on the one hand) and the first cavity length 153 and the second cavity length 155 (on the other hand). In some embodiments, the metal conductor completely fills the via within at least 10% of the axial length of the via 110.

Along the axial length of the through-hole where the first and second cavities 152, 154 are present, the coating thickness 158 is less than 50% of the through-hole diameter at each point along the axial length. In various embodiments herein, the coating thickness 158 is measured as the thickness of the metal connection and does not include the thickness of the helium gas tight adhesion layer. Therefore, the coating thickness does not extend to the center of the through-hole 110, so that the first and second cavities 152 and 154 may be formed. At each point along the axial length, the coating thickness 158 can be 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 49% of the through-hole diameter, or any range having any two of these values as endpoints, inclusive. Coating thickness 158 may be constant with axial position or may vary with axial position. Along the axial length of the through-holes where the first and second cavities 152, 154 are present, the coating thickness 158 may be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 8 μm, 10 μm, or less than 12 μm, or any range having any two of these values as endpoints, including endpoints, so long as the coating thickness 158 is sufficiently small so as not to completely fill the through-holes where the first and second cavities 152, 154 are present. However, as will be described in more detail below, the coating thickness 158 of various embodiments is less than 12 μm. In various embodiments, the coating thickness 158 within the via at the first major surface and the coating thickness 158 within the via at the second major surface are each less than the coating thickness in the second axial portion. In some embodiments, the coating thickness 158 is less than half the diameter of the third diameter 153c in the through-hole at each of the first and second major surfaces 102, 104.

Although shown as empty or unfilled in fig. 2 and 3, in some embodiments, the first cavity 152 and/or the second cavity 154 may be filled with one or more materials other than copper. Such filling of the first cavity 152 and/or the second cavity 154 may reduce or eliminate contamination or degradation of the metal connector 150 due to corrosive materials used in glass processing. In embodiments, the material may have a CTE lower than that of the metal connector 150, be plastic, and/or have one or more degrees of freedom that exceed the degrees of freedom of the metal connector 150. In particular embodiments, the material may further reduce the stress of the glass article, or even bring the net stress of the glass article to zero. In some embodiments, the material is not covalently bound to the metal linker 150.

Suitable materials that may be used to fill the first cavity 152 and/or the second cavity 154 may include, for example, but are not limited to, materials that do not degrade at temperatures greater than or equal to 400 ℃ or even 500 ℃. For example, sol-gel silica, sol-gel metal oxides, polymers, composites, alloys, or other types of inorganic materials may be used, depending on the particular implementation. The first cavity 152 and/or the second cavity 154 may be filled using any of a variety of methods known and used in the art, including but not limited to inkjet printing, spraying, or another deposition method. It is contemplated that the particular method used to fill first cavity 152 and/or second cavity 154 may depend on the particular material to be used.

Manufacturing method

The through-glass vias having a tapered shape may be fabricated by any suitable method. One method is to form a damage trace in the substrate 100 using a laser and then perform etching. Exemplary methods are described in U.S. patent No. 9,656,909 and U.S. patent application serial No. 62/588,615, which are incorporated herein by reference in their entirety. Another method is to modify the photosensitive glass with a laser and then etch it.

Fig. 4 shows a flow chart illustrating a process for metallizing through-glass vias. In step 410, a helium gas tight adhesion layer is deposited on the inner surface of the through hole in the first axial portion and the third axial portion, but not in the second axial portion. In a subsequent step 420, a metal connection is deposited within the through hole such that the metal connection adheres to the helium gas-tight adhesion layer in the first axial portion and the third axial portion.

A helium gas tight adhesion layer may be deposited by any suitable method on the inner surfaces in the first and third axial sections, but not in the second axial section. For example, the length of the first and third axial portions in the z-dimension can be easily controlled using line of sight deposition (e.g., sputtering) methods and adjusting the deposition angle. The substrate may be rotated during deposition to ensure that in the first axial portion and the third axial portion, the length of the first and third axial portions is constant around the entire perimeter of the inner surface of the through-hole.

Helium gas tight adhesion layers in the form of films formed of metals, metal oxides or metal nitrides can be applied to glass surfaces using many different methods such as sputtering, electron beam deposition, ion beam deposition, atomic layer deposition, chemical vapor deposition and solution coating.

The metal connector may be made of any suitable metal. In some embodiments, copper may be a desirable metal due to its particularly high electrical conductivity. Gold, silver and other conductive metals, as well as alloys of conductive metals, may also be used. In an embodiment, the metal connection comprises copper. In some embodiments, the metal connector consists essentially of copper.

The metal connections may be deposited by any suitable means. One suitable method for depositing copper (and other metals) is to deposit a catalyst (e.g., Pd) on a helium gas-tight adhesion layer, then electrolessly deposit copper, followed by electroplating copper. In various embodiments, the electroplating process comprises: using a catalyst comprising a metal salt and goldAn electroplating bath containing a deposition inhibitor, and applying a current density of 1.5mA/cm or more²And less than or equal to 5mA/cm²Or greater than or equal to 1.5mA/cm²And less than or equal to 2.5mA/cm²The current of (2). The metal salt may be a salt of a metal forming the metal connector, e.g., CuSO₄. The metal deposition inhibitor may be selected to specifically inhibit or slow the plating rate of the metal at or near the first and second major surfaces to enable formation of a metal bond, and the thickness of the coating within the via at the first and second major surfaces is thinner than at the waist of the via.

An example of a metal deposition inhibitor is nitroblue tetrazolium chloride (NTBC). Without being bound by theory, it is believed that NTBC preferentially adsorbs on copper ions near the via inlet, which results in suppression of copper deposition in the region where NTBC is adsorbed. Preferential adsorption of NTBC also causes the adsorbed NTBC to have a concentration gradient along the axial length of the through-hole with more NTBC near the first and second major surfaces and little NTBC near the waist of the through-hole. Thus, copper may be deposited faster near the waist of the via than near and on the first and second major surfaces. Thus, by maintaining differential plating rates, the center of the via can be plugged while the coating thickness at the first and second major surfaces is less than half the waist diameter.

Although various embodiments described herein include NTBC as a metal deposition inhibitor, other metal deposition inhibitors and methods are contemplated to achieve and maintain differential plating rates. For example, Ni-B (NTB), Methylthiazoltetrazolium (MTT), and/or tetranitroblue tetrazolium chloride (TNBT) can be used as metal deposition inhibitors.

Other suitable methods for depositing the metal connections include filling the vias with a metal paste, and sintering or Chemical Vapor Deposition (CVD). Suitable methods for depositing copper are further described in U.S. patent publication US2017-0287728 (see, e.g., paragraphs [0004] - [0005], which is incorporated herein by reference in its entirety.

Thermal cycling

Glass and glass ceramic substrates having filled vias are often subjected to thermal cycling. Such thermal cycling may occur during device operation, or during manufacturing steps subsequent to via filling. In some embodiments, for example, the glass substrate may be subjected to thermal cycling for annealing.

As noted above, there is a large mismatch between the Coefficient of Thermal Expansion (CTE) of copper and other metals and the CTE of many glass and glass-ceramic materials. Due to CTE mismatch, the metal bond expands more rapidly upon heating than the surrounding glass or glass-ceramic substrate. Similarly, upon cooling, the metal connector shrinks faster than the surrounding substrate. This difference in expansion and contraction creates stresses that can lead to various failure mechanisms, such as delamination or cracking. These failure mechanisms can cause loss of hermeticity and other problems.

Delamination is a failure mechanism. Delamination occurs when a conductive metal (e.g., copper) is desorbed from the interior of the via. When there is a weak bond between the conductor and the substrate, the stresses caused by thermal cycling can lead to delamination. Delamination can lead to loss of gas tightness because gases and liquids can penetrate the substrate along the interface between the delaminated metal connection and the inner surface of the via.

By forming a sufficiently strong bond between the substrate and the metal connection, delamination may be reduced or eliminated. A helium gas tight adhesion layer disposed between the substrate and the metal connector, and on the inner surface of the through hole, may be used to form this bond. As used herein, "adhesion layer" refers to any layer or surface treatment that allows the bond between the metal connector and the substrate to be strong enough to withstand thermal cycling from 25 ℃ to 450 ℃.

While delamination may be prevented by forming a strong bond between the metal connector and the substrate, this stronger bond prevents the metal connector from moving relative to the substrate during thermal cycling. As a result, thermal cycling causes stresses in the substrate that result in cracking and loss of gas tightness.

The two-dimensional (2D) plane strain solution of the elastic classical Lame problem for predicting stress fields in glass centers is as follows:

wherein σ_rAnd σ_θAre radial and circumferential stress, respectively, and ε_T＝(α_f-α_m) Δ T is the misfit strain due to the thermal load Δ T. Material properties α, E and v are CTE, young's modulus and poisson's ratio, and subscripts f and m represent via (fiber) and glass (matrix), respectively.

Failure can occur due to both heating and cooling in the thermal cycle. During heating, the maximum expansion mismatch is at the hottest temperature. Most of the stress in the substrate is compressive at higher temperatures because the metal connectors expand more than the substrate. Circumferential stresses around the metal connection are dominant during heating, which can lead to radial cracks that can propagate to adjacent through holes. During cooling, the maximum shrinkage mismatch is at the lowest temperature. Most of the stress in the substrate is tensile stress at lower temperatures because the metal connector contracts more than the substrate. The radial stresses that predominate during cooling can lead to cracking. Radial stress is tensile stress in the glass near the surface, which can cause the glass to crack circumferentially. For heating and cooling, the presence of shear stress along the interface can induce interfacial failure by delamination.

Towards the end of the cooling portion of the thermal cycle, the metal connector 150 contracts more than the substrate 100 due to the difference in CTE. Since the metal link 150 adheres to the substrate 100, the contraction of the metal link 150 pulls on the substrate 100, thereby placing the substrate 100 in tensile stress. Without sufficient freedom to supply force relief, the tensile stress would cause microcracks in the substrate 100, which in turn may cause loss of hermeticity.

Various embodiments described herein may exhibit helium gas tightness and not crack after being subjected to thermal cycling. In particular, in the various embodiments described herein, the presence of a copper conformal coating having a limited coating thickness at a major surface of the substrate and having a fully filled intermediate portion, and the helium gas-tight adhesion layer not being present along the second axial portion of the through-hole, provides helium gas tightness while enabling the substrate and the metal connection to shrink at different rates without generating an amount of tensile stress sufficient to create microcracks.

Modeling

The geometry of fig. 2 and 3 was used for modeling, where the inner surface of the through-hole was conformally coated with copper everywhere, but not with an axial length of 75 μm — 37.5 μm on each side of the waist 125, where the through-hole was always filled. The via length 130 is 300 μm. The first diameter 132a and the second diameter 132b are each 50 μm. Starting from both surfaces, a diameter of 50 μm is maintained along the axial length by a distance of 50 μm. Starting at 50 μm from each surface, the through-hole tapers inwardly to a diameter of 25 μm at the waist 125, which waist 125 is half the length along the axial direction. On the top and bottom surfaces, a 20 μm thick flat copper cap 151 (shown in fig. 2 and 3) is included. It is expected that the modeling results will extend to other via and metal connector shapes that have cavities in the metal connector and have a second axial portion of weak bonding between the metal connector and the substrate.

In one process flow for fabricating a real device, the geometry of fig. 2 and 3, including the copper cap 151, exists when the most severe thermal cycling occurs. Thereafter, the copper cap is removed and further processing may occur. The geometries of fig. 2 and 3 are related to the thermal cycle modeled herein.

The modeling is based on the following parameters from Ryu SK, Lu KH, Zhang X, Im JH, Ho PS, Huang R.Impact of near-surface thermal stresses on interfacial Reliability for 3-D interconnects, IEEE Transactions on Device and Materials Reliability, 3 months 2011; 11(1):35- ("Ryu") theory of acquisition. From Ryu, when a via is provided in a wafer, there is an analytical solution for predicting the stress of the via and the wafer surface. However, there is no closed-loop solution to predict the stress through the thickness. Therefore, modeling is required. For modeling, a single isolated hole in a finite plate is modeled. Assume 2D axial symmetry and use a sufficiently small grid size of 0.5 um.

For modeling, it was assumed that the glass was elastic and that the properties of fused silica were as follows: e (Young's modulus) is 73 GPa; v (poisson's ratio) 0.17 and α (coefficient of thermal expansion) 0.55 ppm/deg.c. Copper is assumed to have elastic perfect plastic properties and to have a temperature dependent yield stress. Fig. 5A shows a graph 500 illustrating the stress-strain relationship for an elastic perfect plastic. Fig. 5B shows a graph 510 illustrating temperature dependent copper yield stress. The elastic properties of the copper used for modeling were: e (Young's modulus) 121 GPa; v (poisson's ratio) 0.35 and α (coefficient of thermal expansion) 17 ppm/deg.c. It is also assumed that the system comprising copper vias and fused silica is in a stress-free state at 25 ℃. The modeling calculates the stress after thermal cycling from 25 ℃ to 400 ℃ and back down to 25 ℃.

If the glass cracks, it will first crack where the first principal stress is greatest (i.e., "maximum first principal stress"). Referring to fig. 3, the modeling shows the highest first principal stress at two points. First, along line 190, a short distance from the interface between the helium gas-tight adhesion layer 122 and the substrate 100, there is a high maximum principal stress on the surface of the substrate 100. The first point of this high stress corresponds to the failure mechanism observed in the sample-microcracks in the surface.

Second, there is a maximum principal stress at point 192 where the helium gas tight adhesion layer 122 terminates. This point is the principal stress component that induces crack initiation and propagation. Fig. 6 shows a plot of modeled first maximum principal stress and maximum radial stress along line 190 for different copper wall thicknesses. As shown in fig. 6, at a coating thickness of 12 μm, the first maximum principal stress and the maximum radial stress intersect or exceed a threshold (for the configuration shown in fig. 2 and 3, the threshold for the first maximum principal stress is 140MPa and the threshold for the maximum radial stress is 80 MPa).

Fig. 7 shows the percentage of vias with cracks after annealing the wafer to a maximum temperature of 400 c for different copper coating thicknesses, where the dashed line represents the 95% confidence boundary of the regression fit. The coating thickness is measured at the first or second major surface and groups are formed based on integers of the coating thickness measurements. In other words, the group "8 μm" includes coating thicknesses of 8.00 μm to 8.99 μm, the group "9 μm" includes coating thicknesses of 9.00 μm to 9.99 μm, and so on. As shown in fig. 7, cracks did not occur in the through-holes until the coating thickness was greater than or equal to 12 μm. Modeling allows one skilled in the art to make an informed choice of the metal joint parameter, which in this case is the coating thickness 158. The coating thickness should not be reduced too much because a certain coating thickness is required to form a gas-tight seal, and to achieve the desired electrical conductivity through the metal connector 150.

Fig. 8A and 8B are cross-sectional views of metalized through-glass vias with different copper coating thicknesses. As shown in fig. 8A, if the coating thickness of copper is less than 12 μm, there are no cracks, while fig. 8B shows circumferential microcracks, where the coating thickness of copper is greater than or equal to 12 μm.

Examples

As one example, Ti/Cu is first deposited as an encapsulant layer using sputtering. Next, electroless deposition of Cu is performed to build up a continuous seed layer. The TGV samples were subjected to SC1 cleaning process followed by application of silane as an adhesion layer. Electroless deposition of copper was carried out in a commercially available "uyemua electroless" bath using Pd/Sn colloids as catalyst and formaldehyde as reducing agent. The thickness of the seed layer was about 400 nm.

After the seed layer was deposited, the TGV substrate was electroplated with copper. First, conformal plating of copper was performed using a commercially available Cupracid TP bath to ensure excellent and uniform conductivity within the via. The thickness of the conformal plating layer is about 3 μm. Next, metallization was performed using an NTBC additive bath. Bath composition 0.88M CuSO₄，45ppm NTBC，0.56M H₂SO₄And 45ppm Cl^-Ions. Plating at 1.5mA/cm²Is completed at a constant current density. Fig. 9 shows an X-ray CT scan of the metallized TGV obtained with this procedure. All TGVs are metallized and the structure is similar to the schematic of the inventive article in fig. 2. SEM images demonstrating the plating thickness profile are provided in fig. 10A-10C. As shown in fig. 10A and 10B, this is a proving tongThe center of the pores was completely blocked with Cu while the coating thickness was about 8 μm (fig. 10C).

Conclusion

As used herein, the phrase "consisting essentially of … …" limits the scope of the claims to the specified materials or steps, as well as "those that do not materially affect the basic and novel characteristics of the claimed invention".

Those skilled in the relevant art will recognize and appreciate that many changes can be made to the various embodiments described herein, while still obtaining the beneficial results. It will also be apparent that some of the desired benefits of this embodiment can be obtained by selecting some of the features without utilizing other features. Accordingly, those who work in the art will recognize that many modifications and adaptations are possible and can even be desirable in certain circumstances and are a part of the present disclosure. Accordingly, it is to be understood that this disclosure is not limited to the particular compositions, articles, devices, and methods disclosed unless otherwise specified. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting. The features illustrated in the drawings are exemplary of selected embodiments of the present description and are not necessarily depicted to scale. These drawing features are examples and are not intended to be limiting.

Unless otherwise stated, it is not intended that any method described herein be construed as requiring that its steps be performed in a particular order. Thus, where a method claim does not actually recite an order to be followed by its steps or it does not otherwise specifically imply that the steps are to be limited to a specific order in the claims or specification, it is not intended that any particular order be implied.