Method for improving seed layer coverage uniformity

Abstract

The invention belongs to the technical field of integrated circuits, and provides a method for improving the coverage uniformity of a seed layer. The method comprises the following steps: firstly, taking a substrate containing a through hole, then forming more than or equal to 1 groove in an area, without the through hole, of the surface of the substrate, the groove penetrates through the length direction or the width direction of the surface of the substrate, and then depositing a seed layer on one surface, with the groove, of the substrate, so that a film layer deposited on the substrate is discontinuous on a plane due to the existence of the groove; the stress of the whole TiCu seed layer can be released, warping is reduced, and the coverage uniformity of the seed layer is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated circuits, and more particularly to a method for improving the coverage uniformity of a seed layer. Background Art

[0002] The key to the development and integration of chiplet heterogeneous integration technology lies in the integration of multi-scale and multi-dimensional chip interconnection, thereby improving power efficiency and reducing latency, providing smaller and higher-performance chips for high-performance computing, artificial intelligence, and smart terminals.

[0003] The vertical interconnection of the chip relies on technologies such as through silicon via (TSV) or through glass via (TGV), and the horizontal interconnection is carried out through the redistribution system (RDL) technology. In the process of TGV or TSV seed layer deposition, as the thickness of the deposited film increases, the substrate is prone to warping under the action of the intrinsic stress of the film. Generally, TGV Ti and TGV Cu films are characterized by tensile stress, and the substrate is warped on all four sides. There is an angle offset between the through hole in the warped area of ​​the substrate and the direction of the electric field. In this way, it is difficult for the sputtered Cu atoms or Cu ions to be deposited inside the through hole, and the metal film inside and outside the through hole cannot form an effective connection, thus affecting the yield of TGV or TSV products.

[0004] Therefore, it is urgent to develop a deposition method suitable for the seed layer that can reduce the warpage, so as to improve the yield of TGV and TSV products. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention proposes a method for improving the uniformity of seed layer coverage. The present invention sets grooves on the surface of the substrate so that the stress of the entire TiCu seed layer can be released, the warping is reduced (the substrate warping is not higher than 0.5mm), and the uniformity of seed layer coverage is significantly improved (such as the seed layer coverage rate of the middle area of ​​the substrate is 4.5%, and the seed layer coverage rate of the corner area of ​​the substrate is 4.1%), which is conducive to the subsequent complete filling of the through-hole metal and improves the yield of TGV and TSV products.

[0006] A first aspect of the present invention provides a method for improving seed layer coverage uniformity.

[0007] Specifically, a method for improving the uniformity of seed layer coverage includes the following steps:

[0008] (1) taking a substrate having through holes, the substrate having a front surface and a back surface, and providing grooves in an area of ​​the surface of the substrate without through holes to obtain a substrate having grooves, wherein the number of the grooves is ≥ 1, and all the grooves extend through the length direction of the substrate surface or all the grooves extend through the width direction of the substrate surface;

[0009] (2) depositing a seed layer on the surface of the substrate having the grooves.

[0010] The present invention opens grooves on the surface of a substrate with through holes, and all the grooves need to run through the entire length direction or width direction of the substrate. Without affecting the arrangement of the through holes, the film layer deposited on the substrate is discontinuous on the plane, which can release the stress of the entire TiCu seed layer and reduce warping, thereby significantly improving the coverage uniformity of the seed layer.

[0011] Preferably, in step (1), the through hole is a through silicon via (TSV) or a through glass via (TGV).

[0012] Preferably, in step (1), the through hole is a V-shaped hole.

[0013] Preferably, the number of the grooves is ≥ 2, and the grooves are arranged in parallel with adjacent grooves. All the grooves are arranged in parallel, and all the grooves penetrate along the length direction or width direction of the substrate surface.

[0014] Preferably, in step (1), the aspect ratio of the through hole is (5-10):1.

[0015] Further preferably, in step (1), the aspect ratio of the through hole is (5-8):1.

[0016] More preferably, in step (1), the aspect ratio of the through hole is (6-7):1.

[0017] Preferably, in step (1), the through hole has a size of 2-200 μm, and / or the distance between the through holes is 2-200 μm.

[0018] Preferably, in step (1), the size of the substrate is (450-600) mm×(450-600) mm×(0.1-3) mm.

[0019] Further preferably, in step (1), the size of the substrate is (500-550) mm×(500-550) mm×(0.1-2) mm.

[0020] More preferably, in step (1), the size of the substrate is (510-530) mm×(510-520) mm×(0.1-1) mm.

[0021] Preferably, in step (1), the width of the groove is 50-500 μm, and / or the depth of the groove is 10-50 μm. The groove needs to run through the entire length or width of the substrate, and the width of the groove is not required to be high. It can be set at 50-500 μm without affecting the arrangement of the TGV through holes.

[0022] Further preferably, in step (1), the width of the groove is 50-80 μm, and / or the depth of the groove is 10-30 μm.

[0023] Preferably, in step (2), the seed layer includes a Ti layer and a Cu layer.

[0024] Further preferably, in step (2), a Ti layer and a Cu layer are sequentially deposited on the surface of the substrate having the grooves.

[0025] Preferably, in step (2), the thickness of the Ti layer is 150-250 nm, and / or the thickness of the Cu layer is 1100-1300 nm.

[0026] Further preferably, in step (2), the thickness of the Ti layer is 200-220 nm, and / or the thickness of the Cu layer is 1200-1250 nm.

[0027] Preferably, in step (2), the deposition method is magnetron sputtering deposition.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] The present invention first takes a substrate with through holes, and then opens grooves in the area without through holes on the surface of the substrate, the grooves run through the length direction or width direction of the substrate surface without affecting the arrangement of the through holes, and the number of grooves is ≥1, and then a seed layer is deposited on the side of the substrate with the grooves, the seed layer is deposited in the area without through holes on the surface of the substrate and in the through holes, the presence of the grooves can make the film layer deposited on the substrate discontinuous on the plane, can release the stress of the entire TiCu seed layer, reduce warping, and significantly improve the coverage uniformity of the seed layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The cross-sectional view and top view of the glass substrate having TGV through holes and grooves formed thereon in step (1) of Example 1 of the present invention;

[0031] Figure 2 This is a cross-sectional view of a glass substrate after the TiCu seed layer deposition is completed in step (2) of Example 1 of the present invention. DETAILED DESCRIPTION

[0032] In order to make the technical scheme of the present invention more clearly understood by those skilled in the art, the following embodiments are listed for illustration. It should be pointed out that the following embodiments do not limit the protection scope of the present invention.

[0033] Unless otherwise specified, the raw materials, reagents or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods.

[0034] Example 1

[0035] A method for improving the uniformity of seed layer coverage comprises the following steps:

[0036] (1) A TGV through hole was opened on the surface of a glass substrate (width 510 mm × length 515 mm × height 0.5 mm) (the cross-sectional view and top view are shown in Fig. Figure 1 A and Figure 1 B), the TGV through hole is a V-shaped hole, and the aspect ratio of the TGV through hole is 6:1; then grooves are set in the substrate surface area without TGV through holes, and all the grooves run through the length direction of the substrate surface. The width of each groove is 50μm, the depth is 10μm, the number of grooves is 500, the grooves are arranged parallel to adjacent grooves, the grooves and the through holes are arranged alternately, and are distributed in the area between the through holes, that is, groove-through hole-groove, and the grooves do not affect the arrangement of the TGV through holes;

[0037] (2) A 200 nm Ti layer and a 1200 nm Cu layer were sequentially deposited on the substrate surface by magnetron sputtering. The results are shown in Figure 2. Figure 2 As shown, the Ti layer and the Cu layer are combined to be called a seed layer or a TiCu seed layer or a TGV seed layer. During the magnetron sputtering process, the target material is a cathode and a bias voltage is applied to the substrate stage so that the sputtered metal ions can easily enter the side wall of the through hole.

[0038] Example 2

[0039] A method for improving the uniformity of seed layer coverage is different from Example 1 in that the aspect ratio of the TGV through hole is replaced with 5:1.

[0040] Example 3

[0041] A method for improving the uniformity of seed layer coverage, which is different from Example 1 in that the width of each groove is 80 μm and the depth is 30 μm.

[0042] Comparative Example 1

[0043] A method for depositing a TGV seed layer is different from Example 1 in that, in step (1), no groove is provided on the surface of the substrate with the TGV through hole, and the remaining steps are the same as Example 1.

[0044] Product effect testing

[0045] Test the substrate warpage and seed layer thickness and calculate the seed layer coverage on the substrate surface according to the following formula (1):

[0046] Seed layer coverage = film thickness at the bottom of the V-shaped hole / film thickness on the plane outside the through hole × 100% formula (1).

[0047] The results show that in comparative example 1, during the deposition of the seed layer, the substrate warped due to the stress of the TiCu film, with the warping as high as 1.5 mm. The seed layer coverage in the middle area of ​​the substrate is 4.5%, while the seed layer coverage in the corner position is 2.1%, which indicates that the seed layer coverage in various areas of the substrate surface is uneven, which will cause the seed layer thickness in the deep through-holes in the corner area of ​​the substrate to be thinner and unable to form effective connectivity. Among them, the middle area: the area <80 mm away from the center point of the substrate; the corner area: the area <80 mm away from the edge of the substrate.

[0048] During the TiCu seed layer deposition process of Example 1, the substrate warpage is only 0.5 mm, the substrate warpage is relatively small, the seed layer coverage in the middle area of ​​the substrate is 4.5%, and the seed layer coverage in the corner area of ​​the substrate is 4.1%, which shows that the seed layer coverage uniformity of each area of ​​the TGV substrate prepared in Example 1 is significantly improved, which is conducive to the subsequent complete filling of the TGV through-hole metal. This is because before depositing the seed layer, a groove is set on the surface of the substrate in advance, which not only does not affect the arrangement of the TGV through-holes, but also makes the film layer deposited on the substrate discontinuous on the plane, which can release the stress of the entire TiCu seed layer and reduce the warpage.

[0049] The seed layer coverage uniformity of Example 2 and Example 3 is comparable to that of Example 1, and both can provide uniform coverage.

Claims

1. A method for improving the uniformity of seed layer coverage, characterized in that: The steps include: (1) taking a substrate having through holes, the substrate having a front surface and a back surface, and providing grooves in an area of ​​the surface of the substrate without through holes to obtain a substrate having grooves, wherein the number of the grooves is ≥ 1, and all the grooves extend through the length direction of the substrate surface or all the grooves extend through the width direction of the substrate surface; (2) depositing a seed layer on the surface of the substrate having the grooves.

2. The method according to claim 1, characterized in that In step (1), the through hole is a V-shaped hole.

3. The method according to claim 1, characterized in that In step (1), the number of the grooves is ≥2, and the grooves are arranged in parallel with adjacent grooves.

4. The method according to claim 1, characterized in that: In step (1), the aspect ratio of the through hole is (5-10):

1.

5. The method according to claim 4, characterized in that In step (1), the aspect ratio of the through hole is (5-8):

1.

6. The method according to claim 1, characterized in that In step (1), the size of the substrate is (450-600) mm×(450-600) mm×(0.1-3) mm.

7. The method according to claim 1, characterized in that In step (1), the width of the groove is 50-500 μm, and / or the depth of the groove is 10-50 μm.

8. The method according to claim 1, characterized in that In step (2), the seed layer includes a Ti layer and a Cu layer.

9. The method according to claim 8, characterized in that In step (2), the thickness of the Ti layer is 150-250 nm, and / or the thickness of the Cu layer is 1100-1300 nm.

10. The method according to claim 9, characterized in that In step (2), the thickness of the Ti layer is 200-220 nm, and / or the thickness of the Cu layer is 1200-1250 nm.

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