Glass-based heterogeneous integrated structure containing back hole and manufacturing method thereof

Abstract

The invention provides a glass-based heterogeneous integrated structure containing a back hole and a manufacturing method. The manufacturing method comprises the following steps: designing the back hole in a heterogeneous integrated wafer; the heterogeneous integrated wafer comprises a glass-based substrate and a piezoelectric crystal layer, or at least one heterogeneous film layer is bonded between the glass-based substrate and the piezoelectric crystal layer; the back hole is a blind hole or / and a through hole, and the blind hole is etched to reach the piezoelectric crystal layer or any heterogeneous film layer; and filling metal is sputtered in the back hole. Before the front piezoelectric crystal layer is etched, a surface acoustic wave filter pattern can be manufactured on the complete surface of the glass-based heterogeneous integrated wafer containing the back hole; after the piezoelectric crystal layer is etched, the bottom of the filling metal is exposed on the surface of the glass-based heterogeneous integrated wafer, interconnection of the surface acoustic wave filter and the filling metal is realized through photoetching, evaporation or sputtering, electroplating and the like, and the blind holes can be arranged into a winding type inductor and are connected to the front device layer through the through holes. The method has the characteristics of better device heat dissipation, better packaging design mass production, higher integration level, higher device Q value and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of piezoelectric composite materials and three-dimensional packaging, and particularly relates to a glass-based heterogeneous integrated structure with back holes and a manufacturing method. BACKGROUND

[0002] At present, the development of glass substrates has driven the innovation of chip packaging field, and 2.5D and 3D packaging processes are popularized in various chips. As an important device of radio frequency module, the surface acoustic wave filter has developed from a single piezoelectric substrate in the past to a thick silicon oxide temperature-compensated surface acoustic wave filter, and then to a thin film type surface acoustic wave filter with high quality factor and low temperature drift coefficient. The single piezoelectric substrate in the past is not easy to be etched deeply, and it is difficult to etch a through hole in the substrate, which restricts the three-dimensional packaging of ordinary surface acoustic wave filters. The thickness of the piezoelectric thin film layer of the thin film type surface acoustic wave filter today can reach several hundred nanometers, and the etching process conditions of the piezoelectric thin film layer are very complete. At the same time, the glass blind hole through hole technology is also very mature, and is quickly applied to various glass-based chips to realize the 2.5D and 3D packaging of such glass-based chips, greatly improving the chip packaging integration, however, the surface acoustic wave filter packaging of the radio frequency module mainly relies on the back-dropping on the substrate, and the three-dimensional packaging technology is not mature. SUMMARY

[0003] In order to solve the above-mentioned three-dimensional packaging problem of the surface acoustic wave filter, the present application provides a glass-based heterogeneous integrated structure with back holes and a manufacturing method. The back holes are made on the heterogeneous integrated wafer and filled with metal, and the surface acoustic wave filter pattern can be made on the complete surface of the glass-based heterogeneous integrated wafer with back holes before the front piezoelectric crystal layer is etched. After etching the piezoelectric crystal layer, the bottom of the filled metal is exposed on the surface of the glass-based heterogeneous integrated wafer, and then the surface acoustic wave filter and the filled metal are interconnected by means of photolithography, evaporation or sputtering, electroplating and the like. The back surface of the wafer can be made into interconnection lines or metal signal discs to realize the back surface lead-out of signals.

[0004] The present application achieves the above-mentioned purpose by the following technical solutions: A glass-based heterogeneous integrated structure with back holes, comprising a heterogeneous integrated wafer and back holes on the heterogeneous integrated wafer; The heterogeneous integrated wafer comprises a double-layer structure and a multi-layer structure, the double-layer structure is composed of a glass-based substrate and a piezoelectric crystal layer, the piezoelectric crystal layer is bonded on the glass-based substrate, and the multi-layer structure is at least one heterogeneous thin film layer bonded between the glass-based substrate and the piezoelectric crystal layer; The back holes on the heterogeneous integrated wafer are blind holes or through holes penetrating the glass-based substrate layer to reach the piezoelectric crystal layer or any of the heterogeneous thin film layers, and the blind holes and the through holes exist simultaneously; The back holes are filled with metal.

[0005] Further, the glass substrate adopts quartz or doped glass.

[0006] Further, the piezoelectric crystal layer adopts piezoelectric materials including lithium tantalate, lithium niobate, aluminum nitride in tangential direction or crystal direction.

[0007] Further, the heterogeneous thin film layer contains silicon oxide layer, polysilicon layer, silicon carbide layer, sapphire layer, aluminum nitride layer, titanium nitride layer materials with high and low acoustic velocity.

[0008] Further, the filling metal is copper or tin, and solid filling or conformal filling is adopted.

[0009] Further, the bottom surface formed after the back hole filling metal is flush with the back surface of the glass substrate.

[0010] Further, when the back hole is a blind hole, a plurality of blind holes with the same depth are arranged in order and closely, adjacent blind holes are staggered, a winding dense blind hole pattern is formed, and a high-Q inductor is formed after the filling metal.

[0011] The application also provides a manufacturing method of the glass substrate with a back hole, comprising the following steps: S1, bonding a piezoelectric crystal layer on the surface of the glass substrate to manufacture a double-layer composite wafer, or stacking at least one heterogeneous thin film layer on the glass substrate, and then bonding a piezoelectric crystal layer on the stacked heterogeneous thin film layer to manufacture a multi-layer composite wafer; S2, manufacturing a blind hole penetrating the glass substrate on the back surface of the glass substrate, and then etching the corresponding heterogeneous thin film layer or / and piezoelectric crystal layer according to the design requirement to complete the etching of the back hole; S3, sputtering a filling metal in the back hole; S4, removing the sputtered metal on the back surface of the glass substrate by chemical mechanical grinding to realize bottom surface flattening, and then grinding the glass substrate to a specified thickness; S5, grinding the front piezoelectric crystal layer by chemical mechanical grinding to a specified thickness and polishing.

[0012] Further, when the through hole is processed, the blind hole etching is extended into the piezoelectric crystal layer, and the depth of the blind hole in the piezoelectric crystal layer is greater than the final thickness of the piezoelectric crystal layer after processing.

[0013] Compared with the prior art, the application has the beneficial effects that: The glass-based heterogeneous integrated wafer with back holes has the characteristics of better device heat dissipation, better packaging design mass production, higher integration, and higher device Q value. Before etching the front piezoelectric crystal layer, the surface acoustic wave filter pattern can be made on the complete surface of the glass-based heterogeneous integrated wafer with back holes. After etching the piezoelectric crystal layer, the bottom of the filling metal is exposed on the surface of the glass-based heterogeneous integrated wafer, and then the surface acoustic wave filter and the filling metal are interconnected through photolithography, evaporation or sputtering, and electroplating. The back of the glass-based heterogeneous integrated wafer with back holes can be made into interconnection lines or metal signal plates to realize the back lead-out of signals, thereby laying the foundation for the future three-dimensional packaging of high-performance surface acoustic wave filters. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 It is a schematic diagram of a single-layer piezoelectric film bonding wafer under a glass substrate. Figure 2 It is a schematic diagram of a glass-based heterogeneous integrated structure with back holes in Example 1. Figure 3 It is a schematic diagram of a glass-based heterogeneous integrated structure with back holes in Example 2. Figure 4 It is a schematic diagram of a glass-based heterogeneous integrated structure with back holes in Example 3. Figure 5 It is a schematic diagram of a multi-layer film bonding wafer under a glass substrate. Figure 6 It is a schematic diagram of a glass-based heterogeneous integrated structure with back holes in Example 4. Figure 7 It is a schematic diagram of a glass-based heterogeneous integrated structure with back holes in Example 5. Figure 8 It is a schematic diagram of a glass-based heterogeneous integrated structure with back holes in Example 6. Figure 9 It is a schematic diagram of a glass-based heterogeneous integrated structure with back holes in Example 7. Figure 10 It is a schematic diagram of a surface acoustic wave pattern made on the surface of a glass-based heterogeneous integrated structure with back holes. Figure 11 It is a top view of the surface of a glass-based heterogeneous integrated structure with back holes. Figure 12 It is a back view of a glass-based heterogeneous integrated structure with back holes. Figure 13 It is a zigzag line surrounding inductance made by back holes.

[0015] Reference signs in the figure: 1-glass substrate, 2-piezoelectric crystal layer, 3-first hetero thin film layer, 4-second hetero thin film layer, 5-blind hole, 6-via hole, 7-filling metal, 8-SAW metal layer, 9-filling metal connecting hole, 10-SAW filter pattern, 11-metal PAD layer, 12-RDL layer. DETAILED DESCRIPTION

[0016] Exemplary embodiments of the present application will be described in detail below with reference to the accompanying drawings. Although exemplary embodiments of the present application are shown in the drawings, it is understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that this application will be thoroughly and completely understood, and so that the scope of the present application will be completely conveyed to those skilled in the art. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0017] Reference Figures 1 to 13 The present application discloses a glass-based hetero integrated structure with back holes and a manufacturing method. Back holes are designed on a hetero integrated wafer. The hetero integrated wafer includes a glass substrate 1 and a piezoelectric crystal layer 2, or at least one hetero thin film layer is bonded between the glass substrate 1 and the piezoelectric crystal layer 2. The back holes are blind holes 5 or / and via holes 6. The blind holes 5 etch to reach the piezoelectric crystal layer 2 or any hetero thin film layer. The filling metal 7 is sputtered in the back holes. Before the piezoelectric crystal layer 2 is etched, a SAW filter pattern 10 can be manufactured on the complete surface of the glass-based hetero integrated wafer with back holes. After the piezoelectric crystal layer 2 is etched, the bottom of the filling metal 7 is exposed on the surface of the glass-based hetero integrated wafer. Then, the surface acoustic wave filter and the filling metal 7 are interconnected by means of photolithography, evaporation or sputtering, electroplating, etc. The blind holes 5 can be arranged in a folded inductor and connected to the front device layer through the via holes 6.

[0018] The hetero integrated wafer structure composed of the glass substrate 1 and the piezoelectric crystal layer 2 is shown in Figure 1 The piezoelectric crystal layer 2 is bonded on the glass substrate 1. The back holes made on the back surface are in the form of blind holes 5, both blind holes 5 and via holes 6, or all via holes 6, which are described in embodiments 1-3 respectively. The hetero integrated wafer structure with multiple hetero thin film layers is shown in Figure 5 From bottom to top, the glass substrate 1, the first hetero thin film layer 3, the second hetero thin film layer 4 and the piezoelectric crystal layer 2 are arranged in sequence. The back holes made on the back surface are in the form of blind holes 5, both blind holes 5 with different depths, both blind holes 5 and via holes 6, or all via holes 6, which are described in embodiments 4-7 respectively.

[0019] Embodiment 1:

[0020] The glass substrate 1 in this embodiment is quartz, and the piezoelectric crystal layer 2 is lithium tantalate. A blind hole 5 is etched on the glass substrate 1, the blind hole 5 penetrates the glass substrate 1 and reaches the piezoelectric crystal layer 2, and the blind hole 5 is filled with copper. The final heterogeneous integrated structure is shown in Figure 2 The final form of the back hole is shown in Figure 2 (a).

[0021] The specific manufacturing steps are as follows: S1: Take a 6-inch quartz glass sheet with a thickness of 600 um as the glass substrate 1 and clean it.

[0022] S2: Low-temperature plasma activation bonding of the piezoelectric crystal layer 2 lithium tantalate wafer on the surface of the glass substrate 1, wherein the lithium tantalate wafer has a thickness of 200 um, and the bonding surface of the lithium tantalate wafer is polished to a bonding level flatness.

[0023] S3: After the bonding is completed, the composite wafer is thinned, and the glass substrate 1 is reduced from 600 um to 250 um and then subjected to laser irradiation modification. The coordinates and size of the hole position are input into the laser equipment, and the laser irradiates the designated area according to the design, thereby changing the glass properties of the back glass substrate 1. Then, the modified composite wafer is wrapped with a corresponding pattern of fluorine-containing polymer film, and after the wrapping, it is placed in an HF acid buffer solution for glass hole etching. After completion, the fluorine-containing polymer film used for protection is removed.

[0024] S4: After etching, the glass substrate 1 has a blind hole 5 on the back, and the bottom of the blind hole 5 extends to the lithium tantalate wafer layer.

[0025] S5: Use a mature blind hole electroplating formula to electroplate copper in the blind hole. After XRD testing of the filling metal 7 in the blind hole 5 confirms that there are no bubbles and no cracks, the next step is performed.

[0026] S6: Chemical mechanical polishing of the back of the composite wafer to remove the sputtered copper on the back, and then grinding the glass substrate to 200 um after completely exposing the surface of the glass substrate 1.

[0027] S7: Polishing the front of the composite wafer to remove a certain thickness of lithium tantalate on the front, and polishing the lithium tantalate layer until the film thickness reaches 200 nm, and then cleaning, to finally present the composite wafer structure with a back metal hole shown in Figure 2 (b).

[0028] Embodiment 2:

[0029] The embodiment is based on the embodiment 1, and the partial blind hole 5 on the glass substrate 1 is further etched into a through hole 6, so that the wafer has both the blind hole 5 and the through hole 6, the blind hole 5 penetrates the glass substrate 1 and reaches the piezoelectric crystal layer 2, the through hole 6 penetrates the piezoelectric crystal layer 2, the blind hole 5 and the through hole 6 are filled with copper, and finally the heterogeneous integrated structure is as shown in Figure 3 The final form of the back hole is as shown in (a) of Figure 3 .

[0030] The embodiment is based on the embodiment 1, and the partial blind hole 5 on the glass substrate 1 is further etched into a through hole 6, so that the wafer has both the blind hole 5 and the through hole 6, the blind hole 5 penetrates the glass substrate 1 and reaches the piezoelectric crystal layer 2, the through hole 6 penetrates the piezoelectric crystal layer 2, the blind hole 5 and the through hole 6 are filled with copper, and finally the heterogeneous integrated structure is as shown in Figure 3 The final form of the back hole is as shown in (a) of

[0031] Embodiment 3:

[0032] The embodiment is based on the embodiment 1, and the partial blind hole 5 on the glass substrate 1 is further etched into a through hole 6, so that the wafer has both the blind hole 5 and the through hole 6, the blind hole 5 penetrates the glass substrate 1 and reaches the piezoelectric crystal layer 2, the through hole 6 penetrates the piezoelectric crystal layer 2, the blind hole 5 and the through hole 6 are filled with copper, and finally the heterogeneous integrated structure is as shown in Figure 4 The final form of the back hole is as shown in (a) of Figure 4

[0033] The embodiment is based on the embodiment 1, and the partial blind hole 5 on the glass substrate 1 is further etched into a through hole 6, so that the wafer has both the blind hole 5 and the through hole 6, the blind hole 5 penetrates the glass substrate 1 and reaches the piezoelectric crystal layer 2, the through hole 6 penetrates the piezoelectric crystal layer 2, the blind hole 5 and the through hole 6 are filled with copper, and finally the heterogeneous integrated structure is as shown in Figure 4 The final form of the back hole is as shown in (b) of

[0034] Embodiment 4:

[0035] The embodiment is based on the embodiment 1, and the partial blind hole 5 on the glass substrate 1 is further etched into a through hole 6, so that the wafer has both the blind hole 5 and the through hole 6, the blind hole 5 penetrates the glass substrate 1 and reaches the piezoelectric crystal layer 2, the through hole 6 penetrates the piezoelectric crystal layer 2, the blind hole 5 and the through hole 6 are filled with copper, and finally the heterogeneous integrated structure is as shown in Figure 6 ​As shown, the heterogeneous integrated wafer is sequentially composed of a glass substrate 1, a first heterogeneous thin film layer 3, a second heterogeneous thin film layer 4 and a piezoelectric crystal layer 2 from bottom to top, and the thicknesses of the layers are 200 um, 2 um, 500 nm and 600 nm respectively. The glass substrate 1 is quartz, the first heterogeneous thin film layer 3 is polysilicon, the second heterogeneous thin film layer 4 is silicon dioxide, and the piezoelectric crystal layer 2 is a piezoelectric lithium niobate wafer. The back holes of the heterogeneous integrated wafer are blind holes 5 of the same depth, the blind holes 5 penetrate through the glass substrate 1 and reach the first heterogeneous thin film layer 3, and the blind holes 5 are filled with solid copper.

[0036] The manufacturing process of the above-mentioned glass-based heterogeneous integrated structure with back holes is as follows: S1: Take a 6-inch quartz glass sheet with a thickness of 600 um as the glass substrate 1 and clean it.

[0037] S2: Place the glass substrate 1 on a sputtering machine to sputter the first heterogeneous thin film layer 3 of polysilicon. Adjust the sputtering machine parameters including substrate temperature, sputtering atmosphere, sputtering rate, direct current and radio frequency voltage, etc. to manufacture a 2 um thick polysilicon layer on the glass sheet. The thickness measurement device tests the sputtered polysilicon layer thickness to ensure that the actual measured thickness reaches 2 um.

[0038] S3: Sputter the second heterogeneous thin film layer 4 of silicon dioxide on the wafer surface containing the polysilicon layer. Adjust the sputtering machine parameters including substrate temperature, atmosphere and rate, etc. to adjust the density of the silicon dioxide film to a sputtering thickness of 500 nm. The ellipsometer measures the thickness of the silicon dioxide film to ensure accurate actual measured thickness.

[0039] S4: Low-temperature plasma activate bonding of the piezoelectric crystal layer 2 of the piezoelectric lithium niobate wafer on the surface of the composite wafer containing the silicon dioxide dielectric layer. The piezoelectric lithium niobate is relatively thick, reaching 600 um, and the bonding surface of the piezoelectric lithium niobate wafer is polished to a bonding level flatness.

[0040] S5: After the bonding of the composite wafer is completed, the glass substrate 1 is thinned from 600 um to 250 um and then laser irradiation is performed for modification. Input the punching position coordinates and size, etc. in the laser equipment according to the design, and the laser irradiates the set area to change the glass properties of the back glass substrate 1. Then, the modified composite wafer is wrapped with a corresponding pattern of fluorine-containing polymer film, and after being attached, it is placed in an HF acid buffer solution for glass hole corrosion. After completion, the protective fluorine-containing polymer film is removed.

[0041] S6: After the corrosion is completed, the glass substrate 1 has blind holes 5 on the back, and the bottom of the blind holes 5 extends to reach the polysilicon layer. The multiple blind holes 5 are arranged in order and closely arranged, and the adjacent blind holes 5 are connected to each other to form a winding pattern, completing the back inductance punching and winding manufacturing as shown in Figure 13 ​

[0042] S7: Electroplating filling of copper metal in the blind hole 5 using mature blind hole electroplating formula, the filling metal in the blind hole 5 is tested by XRD to confirm that there is no bubble and no crack before the next step.

[0043] S8: Chemical mechanical polishing of the back of the composite wafer, removing the sputtered copper metal on the back, and then polishing the glass substrate to 200um after completely exposing the surface of the glass substrate 1.

[0044] S9: Polishing the composite wafer on the front side to remove a certain thickness of lithium niobate on the front side, polishing the lithium niobate layer until the film thickness reaches 600nm, polishing and cleaning, and finally presenting the composite wafer with back metal holes shown in (b) of Figure 6 The final form of the back hole is shown in (a) of Figure 6 .

[0045] As shown in Figures 10 to 13 , a SAW filter pattern 10 is made on the surface of the composite wafer, a front side patterned photoresist is made, the front side pattern is a 50um diameter filled metal connection hole 9, the position of the filled metal connection hole 9 and part of the back hole position are opposite, the filled metal connection hole 9 required for connection is etched on the front side of the lithium niobate film, the silicon dioxide layer is etched in situ with conventional CF4, Ar gas, the through silicon via (TSV) process is used to pass in C4F8, Ar and SF6 gases for alternate etching and passivation, which can quickly penetrate the polysilicon layer and remove the polysilicon layer, silicon dioxide layer and piezoelectric crystal layer at the bottom of the hole to expose the filled metal 7. Re-etching, filling the metal connection hole 9 by evaporation or sputtering and covering the surface metal with a 3.1um thick SAW metal layer 8, connecting the filter and the back filled metal 7, and making a metal PAD layer 11 on the back of the composite wafer to connect the filled metal 7, so that the SAW filter pattern 10 is normally made on the front side of the composite wafer, the RDL layer 12 is made on the back and the flip-chip packaging is realized, realizing the three-dimensional packaging of the surface acoustic wave filter.

[0046] Example 5:

[0047] The back hole form in this embodiment is changed to two blind holes 5 with different depths, one of which extends to the piezoelectric crystal layer 2, and the other of which extends to the second hetero film layer 4, as shown in Figure 7 . In this embodiment, the glass substrate 1 in Example 4 is replaced by a doped glass-like Schott BF33 material, and the filled metal 7 is replaced by tin instead of copper.

[0048] The glass-based hetero integrated structure with back holes in this embodiment is made by the following process: S1: Take 6-inch, thickness 600um doped glass-like glass sheet Schott BF33 as glass substrate 1 material, and clean it.

[0049] S2: Put the above glass sheet on the sputtering machine to sputter 2um thick polysilicon.

[0050] S3: Sputter a 500nm thick silicon dioxide layer on the wafer containing the polysilicon layer surface.

[0051] S4: Low-temperature plasma activation bonding of 600um thick piezoelectric lithium niobate wafer on the surface of the composite wafer containing the silicon dioxide dielectric layer.

[0052] S5: After the bonding of the composite wafer is completed, it is thinned, and the glass substrate 1 is reduced from 600um to 250um, then laser irradiation modification is performed, and then glass hole etching is performed.

[0053] S6: After etching is completed, blind holes 5 are formed that penetrate the glass substrate 1 and extend to the polysilicon layer at the bottom of the hole. Through the in-situ through silicon via (TSV) process, C4F8, Ar and SF6 gases are alternately etched and passivated to penetrate the polysilicon layer to form blind holes 5 that reach the silicon dioxide layer. The silicon dioxide layer in part of the blind holes 5 is etched in-situ with conventional CF4, Ar gas until the bottom piezoelectric lithium niobate layer is exposed, forming blind holes 5 that reach the piezoelectric crystal layer 2. Back inductance punching and winding are made according to design needs.

[0054] S7: Using mature tin metal filling process, tin paste is uniformly coated on the patterned steel mesh, and a certain amount of tin paste is injected into the blind hole through professional tin filling equipment, and after reflow, a solid filled back hole is formed.

[0055] S8: Chemical mechanical polishing of the back of the composite wafer to remove uneven metal tin on the back until completely flat, and then the glass substrate 1 is polished to a thickness of 200um.

[0056] S9: Polishing the composite wafer on the front side to remove a certain thickness of lithium niobate on the front side, polishing the lithium niobate layer until the film thickness reaches 600nm, and then polishing and cleaning, finally presenting a composite wafer containing a back metal hole as shown in (b) of FIG. 10. Figure 7 Figure 7 The final form of the back hole is shown in (a) of FIG. 10.

[0057] The process of making SAW filter pattern 10 on the wafer surface to realize three-dimensional packaging of SAW filter is the same as that of embodiment 4.

[0058] Embodiment 6:

[0059] ​This embodiment is based on embodiment 5, the back hole structure is a blind hole 5 reaching the silicon dioxide layer and a through hole 6 penetrating the composite wafer, the structure is as shown in Figure 8 .

[0060] The difference between the manufacturing process and embodiment 5 is that after forming the blind hole 5 reaching the silicon dioxide layer, the lithium niobate is further etched to a depth of the piezoelectric crystal layer 2 greater than 600 nm, a blind hole 5 is formed in the lithium niobate layer with a depth greater than the thickness of the final lithium niobate layer, and then the metal tin is filled in the blind hole 5 at the two depths, and the back and front of the composite wafer are chemically mechanically polished, wherein the thickness of the lithium niobate layer on the front is polished to 600 nm to form a through hole 6 penetrating the entire wafer, and the final processed heterogeneous integrated structure is as shown in (b) of Figure 8 , and the final form of the back hole is as shown in (a) of Figure 8 .

[0061] In the process of manufacturing the SAW filter pattern 10 on the wafer surface to realize the three-dimensional packaging of the surface acoustic wave filter, the sputtering of the SAW metal layer 8 is directly performed on the front surface of the wafer to connect the filling metal 7 in the through hole 6, thereby omitting the step of etching and sputtering the filling metal connecting hole 9.

[0062] Embodiment 7:

[0063] This embodiment is based on embodiment 4, the glass substrate material is replaced by doped glass Schott AF32, the back hole is designed as a through hole, the first heterogeneous thin film layer 3 is made of silicon oxide, the second heterogeneous thin film layer 4 is made of polysilicon, the piezoelectric crystal layer 2 is made of lithium tantalate, the thickness of each layer remains unchanged, and the filling metal 7 in the through hole 6 is conformally filled, and the structure is as shown in Figure 9 .

[0064] The manufacturing process of the glass-based heterogeneous integrated structure with a back hole in this embodiment is as follows:

[0065] S1: Take a 6-inch doped glass Schott AF32, clean it, and the thickness of the glass substrate 1 is 600 um.

[0066] S2: Place the above glass sheet on a sputtering machine to sputter silicon oxide, adjust the sputtering machine parameters including substrate temperature, sputtering atmosphere, sputtering rate, direct current and radio frequency voltage, etc., to manufacture a 2 um thick silicon oxide layer on the glass sheet, and the thickness measuring device tests the sputtered silicon oxide layer thickness to ensure that the actual measured thickness reaches 2 um.

[0067] S3: Sputter a polysilicon layer on the wafer with the silicon oxide layer surface, adjust the sputtering machine parameters including substrate temperature, atmosphere and rate, etc., to adjust the density of the polysilicon thin film, the sputtering thickness reaches 500 nm, and the ellipsometer measures the thickness of the polysilicon thin film to ensure the accuracy of the actual measured thickness.

[0068] S4: Low-temperature plasma activation bonding of 600um lithium tantalate wafers is performed on the surface of a composite wafer containing a polycrystalline silicon dielectric layer. The bonding surface of the lithium tantalate wafers is polished to achieve bonding-level flatness.

[0069] S5: After bonding, the composite wafer is thinned from 600µm to 250µm, and then modified by laser irradiation. The drilling location coordinates and size are input into the laser equipment. According to the design, the laser irradiates the designated area, thereby changing the glass properties of the back glass substrate 1. The modified composite wafer is then wrapped with a fluoropolymer film of a corresponding pattern. After wrapping, it is placed in HF acid buffer solution for glass hole etching. After completion, the protective fluoropolymer film is removed.

[0070] S6: After etching, a blind hole 5 penetrating the glass substrate 1 appears on the back side of the glass substrate 1. The bottom of the blind hole 5 extends to the silicon oxide layer. In-situ etching is performed using conventional CF4 and Ar gases. The bottom of the blind hole 5 further extends to the polysilicon layer. Through in-situ through-silicon via (TSV) technology, C4F8, Ar and SF6 gases are introduced for alternating etching and passivation, which quickly penetrates the polysilicon layer until the bottom lithium tantalate layer is exposed. Then, the piezoelectric crystal layer 2 is etched, and the etching depth is greater than the designed thin film thickness of 600nm.

[0071] S7: Using a mature blind hole plating formula, copper is electroplated into blind hole 5 for conformal filling. The filled metal hole is inspected by FIB cross-section to confirm that there are no bubbles or cracks before proceeding to the next step.

[0072] S8: Chemically mechanically grind the back side of the composite wafer to remove the sputtered copper metal until the glass surface is fully exposed and grind the glass substrate 1 to the designed thickness of 200um.

[0073] S9: The composite wafer undergoes front-side grinding to remove a certain thickness of lithium tantalate. The lithium tantalate layer is ground until the film thickness reaches 600nm, followed by polishing and cleaning to finally reveal the desired surface. Figure 9 The composite wafer with a back metal hole shown in (b) has the following final shape: Figure 9 As shown in (a) of the diagram.

[0074] This essentially completed the fabrication of the composite wafer with back holes.

[0075] Finally, a SAW filter pattern 10 is fabricated on the surface of the composite wafer. This embodiment enables the filter to naturally conduct signals filled with metal 7 in the back via 6. A metal PAD layer 11 is fabricated on the back of the composite wafer, thereby fabricating a surface acoustic wave filter on the front of the composite wafer. An RDL layer 12 is fabricated on the back and inverted packaging is performed to achieve three-dimensional packaging of the surface acoustic wave filter.

[0076] The above has carried out the detailed description to the present application through the example, but the content described only is the exemplary embodiment of the present application, cannot be considered for limiting the implementation scope of the present application. The protection scope of the present application is defined by the claims. The technical scheme described in the present application is utilized, or the technical personnel in the art is inspired by the technical scheme of the present application, within the essence and protection scope of the present application, designs the similar technical scheme and reaches the above technical effect, or the equivalent change and improvement of the application scope, should still belong to the patent coverage protection scope of the present application. It should be noted that, in order to clearly express, the description of the present application omits the expression of part of the components and processing which are not directly and obviously related to the protection scope of the present application but known to the technical personnel in the art.

Claims

1. A via-containing glass-based heterogeneous integration structure, characterized in that, The heterogeneous integrated wafer comprises a glass substrate, a piezoelectric crystal layer bonded on the glass substrate, or at least one heterogeneous thin film layer bonded between the glass substrate and the piezoelectric crystal layer; The back hole is a blind hole or / and a through hole penetrating the glass substrate layer, and the blind hole reaches the piezoelectric crystal layer or any of the heterogeneous thin film layers; The back hole is filled with metal. The glass substrate is quartz or doped glass.

2. The via-containing glass-based heterogeneous integration structure of claim 1, wherein, The piezoelectric crystal layer is made of piezoelectric materials including lithium tantalate, lithium niobate, and aluminum nitride.

3. The via-containing glass-based heterogeneous integration structure of claim 1, wherein, The heterogeneous thin film layer comprises high and low acoustic velocity silicon oxide layer, polysilicon layer, silicon carbide layer, sapphire layer, aluminum nitride layer, and titanium nitride layer.

4. The via-containing glass-based heterogeneous integration structure of claim 1, wherein, The filling metal is copper or tin, and is filled in solid or conformal shape.

5. The via-containing glass-based heterogeneous integration structure of claim 1, wherein, The bottom surface of the back hole after filling the metal is flush with the back surface of the glass substrate.

6. The via-containing glass-based heterogeneous integration structure of claim 1, wherein, When the back hole is a blind hole, a plurality of blind holes with the same depth are arranged in order and closely, adjacent blind holes are staggered, a winding dense blind hole pattern is formed, and a high Q value inductor is formed after filling the metal.

7. The via-containing glass-based heterogeneous integration structure of claim 1, wherein, The method comprises the following steps:

8. A method of making a via-containing glass-based heterogeneous integrated structure as claimed in any one of claims 1 to 7, wherein, S1, bonding a piezoelectric crystal layer on the surface of a glass substrate, or stacking at least one heterogeneous thin film layer on the glass substrate, and then bonding a piezoelectric crystal layer on the stacked heterogeneous thin film layer; S2, making a blind hole penetrating the glass substrate on the back surface of the glass substrate, and then etching the corresponding heterogeneous thin film layer or / and piezoelectric crystal layer according to the design requirement to complete the etching of the back hole; S3, sputtering metal in the back hole; S4, chemical mechanical polishing to remove the sputtered metal on the back surface of the glass substrate, realize the bottom surface flattening, and then grind the glass substrate to the specified thickness; S5, chemical mechanical polishing the front piezoelectric crystal layer to the specified thickness and polishing. When processing the through hole, the blind hole etching is extended into the piezoelectric crystal layer, so that the depth of the blind hole in the piezoelectric crystal layer is greater than the final thickness of the piezoelectric crystal layer after processing.

9. The method of claim 8, wherein the glass-based heterogeneous integrated structure comprises a via. ​ ​

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