Brevet FR3095296A1 — publié le 20201023

Description Title of Invention: Centfipetal bumping layout Technical Field [0001] The present disclosure relates generally to the field of integrated circuit chips, and in particular to a flip chip assemhly and a substrate using humps to forrn electrical connections with the chip. Background Art [0002] A problem with existing bump layouts is that (bey can lead to short circuits. Summary of Invention [0003] According to one embodiment, there is a variable safety sizing around the bumps. [0004] According to one embodiment, there is a translation of the bumps into a 2D shape. [0005] According to one embodiment, there is a circular orientation of the bumps. [0006] According to one embodiment, the bump placement is automated. [0007] According to one aspect, there is provided a substrate comprising a contact surface having bumps tbrmed thereon, each bump being rotationally asymmetric in the plane of the contact surface, the bumps for example being orientated on the contact surface in a centripetal anangement, wherein the bumps in a first zone of the contact surface have a first pitch in a first axis and the bumps in a second zone of the contact surface have a second pitch in the first axis, the second pitch being different to the first pitch. 100081 According to one embodiment, a bump density in the first zone is different from a bump density in the second zone. 100091 According to one embodiment, there is an exclusion zone around each of the bumps in which no other hump is formed, wherein the exclusion zone for example bas a first width in a first axis and a second width in a second axis perpendicular to the first axis, the first and second widths being di fferent from each other. 100101 According to one embodiment, the exclusion zone is hexagonal or suhstantially hexagonal. 100111 According to one embodiment, each hump is oblong in shape, or substantially oblong in shape. 100121 According to a further aspect, there is provided a substrate comprising a contact surface having humps formed thereon, each hump being rotationally asymmetric in the plane of the contact surface, the bumps for example being orientated on the contact surface in a centripetal arrangement, wherein the centers of the humps are positioned in a first pattern in a first zone of the contact surface and in a second pattern, di fièrent to the first pattern, in a second zone of the contact surface, the first and second patterns for example defining the spacing between the centers of the bumps in the plane of the 2 contact surface. [0013] According to one cmbodiment, die first zone is a central zone of the contact surface, and the second zone is an annular zone surrounding the central zone. [0014] According to a further aspect, there is providcd a substrate comprising a contact surface having bumps forrned thercon, each bump being rotationally asymmetric in the plane of the contact surface, the bumps for example being orientated on the contact surface in a centripetal arrangement, wherein the bumps arc positioned such that the centers of the bumps in the plane of the contact surface arc not aligned. [0015] According to a further aspect, there is providcd a method of circuit conception im- plemented by a processing device under control of software instructions, the method comprising: defining dimensions of each pump in the plane of a contact surface defined by a circuit design; and automatically performing placement of bumps on the contact surface such that the bumps arc for example orientated on the contact surface in a centripetal arrangement, and/or such that the bumps in a first zone of the contact surface have a first pitch in a first axis and the bumps in a second zone of the contact surface have a second pitch in the first axis, the second pitch being different to the first pitch. [0016] According to a further aspect, there is providcd a method of circuit conception im- plemented by a processing device under control of software instructions, the method comprising: defining dimensions of each pump in the plane of a contact surface defined by a circuit design; and automatically perfoiming placement of bumps on the contact surface such that the bumps are for example orientated on the contact surface in a centripetal arrangement, and/or such that the centers of the bumps are positioned in a first pattern in a first zone of the contact surface and in a second pattern, different to the first pattern, in a second zone of the contact surface, the first and second patterns for example defining the spacing between the centers of the bumps in the plane of the contact surface. [0017] According to a further aspect, there is provided a method of circuit conception im- plemented by a processing device under control of software instructions, the method comprising: defining dimensions of each pump in the plane of a contact surface defined by a circuit design; and automatically perfoiming placement of bumps on the contact surface such that the bumps are for example orientated on the contact surface in a centripetal ar- 3 rangement, and/or such that the bumps are positioned such that the centers of the bumps in the plane of the contact surface are not aligned. Brief Description of Drawings [0018] The foregoing features and advantaees, as well as others, will be described in detail in the following description of specific embodiments given by way of illustration and not limitation with reference to the accompanying drawines, in which: [0019] [fie.11 Figure 1 illustrates an embodiment of the present disclosure; [0020] [fie.21 Figure 2 illustrates an embodiment of the present disclosure; [0021] [fie.31 Figure 3 illustrates an embodiment of the present disclosure; [0022] [fie.41 Figure 4 illustrates an embodiment of the present disclosure; [0023] [fig.5] Figure 5 illustrates an embodiment of the present disclosure; [0024] [fig.6] Figure 6 illustrates an embodiment of the present disclosure; [0025] [fig.7] Figure 7 illustrates an embodiment of the present disclosure; [0026] [fig.8] Figure 8 illustrates an embodiment of the present disclosure; [0027] [fig.9] Figure 9 illustrates an embodiment of the present disclosure; [0028] [fig.10] Figure 10 illustrates an embodiment of the present disclosure; [0029] [fig.11] Figure 11 illustrates an embodiment of the present disclosure; [0030] [fig.12] Figure 12 illustrates an embodiment of the present disclosure; [0031] [fig.13] Figure 13 illustrates an embodiment of the present disclosure; Description of Embodiments 100321 Like features have been designated by like references in the various figures. In particular, the structural and/or functional features that are common among the various embodiments may have the same references and may dispose identical structural, dimensional and material properties. 100331 For the sake of clarity, only the operations and elements that are useful for an under- standing of the embodiments described herein have been illustrated and described in detail. 100341 Unless indicated otherwise, when reference is made to two elements connected toeether, this signifies a direct connection without any intermediate elements other (han conductors, and when reference is made to two elements linked or coupled toeether, this signifies that these two elements can be connected or they can be linked or coupled via one or more other elements. 100351 In the followine disclosure, unless indicated otherwise, when reference is made to absolute positional qualifiers, such as the terrns "front", "back", "top", "bottom", "left", "right", etc., or to relative positional quali fiers, such as the ternis "above", "below", "higher", "lower", etc., or to qualifiers of orientation, such as "horizontal", "vertical", etc., reference is made to the orientation shown in the figures. [0036] Unlcss specified otherwisc, the expressions "around", "approximatcly", "substantially" and "in the order of" signify within 10%, and preferably within 5 %. [0037] Field of application Presentation of the technical demain of the invention Flip Chip Assembly Substratc Packaging for fine bump pitch. [0038] Recognized problem, Increasc the bump dcnsity and avoid short failure. Having a maximum number of bumps is key to assure good electrical performance (Power intcgrity) & thermal performance without incrcasing the die size. [0039] For some Flip Chip products, non-symmetrical bump shapc is uscd (ex. Oblong shapc). In ordcr to minimizc the stress itnplied by package! assembly proccss to the die, Bump arc following particular orientation (ex. 4 segments, 8 segments, centripetal [0040] In some cases (ex. High-end digital products, latcst wafcr nodcs), a vcry high bump density is required. Targct being to rninimize die size and to insurc Signal & Power Integrity of the die + package. [0041] => Such dense configurations may end up with High Short Circuit rate between bumps during assembly process. [0042] -EyeQ5 - Centripetal bumping matrix [0043] FC pad -Solder Mask Opening [0044] Oblong bump [0045] Risk of Short cut [0046] Known closest prior solution to the same technical problem [0047] A: Reduce Bump size [0048] Higher risk of Time zero or Reliability Failures linked to higher stress in Bump and under the bump (inside silicon) [0049] B: Increase Bump Fitch [0050] Die size increase = Die cost increase, not always affordable (especially with latest very expensive wafer nodes) [0051] C: Change Bump shape to symmetrical [0052] May increase the risk of Time zero or Reliability Failures linked to higher stress in Bump and under the bump (inside silicon). [0053] Context [0054] The introduction of new FE technology such 7FF or 16FF (TSMC) needs to develop new bumping strategy to reduce the bump pitch up to 110pm [0055] To avoid stress and short failure, bumping house has integrated the Oblong & cen- tripetal orientation as a main solution. EyeQ5 - Xray view EycQ5 - centripetal constraint. [0056] Linear (staggcred) matrix [0057] Bump short violation in the corner [0058] Linear matrix is no more the optimum matrix for centripetal oblong bump or is requiring to relax bump pitch in the corner. [0059] Algorithm to optimize the number of bumps overview Corner arca [0060] Peripheral middle arca [0061] New butnps location to be automated (slow centripetal shift not dctectable with manual placement). [0062] Clearance rulcs overview Sectors : angle in &grec Min bump to butnp pitch : 110 prn Min UBM clearance rulcs as per drawing : Rulcs appl ics only in the scctor that contains the minimum bump clearance 36pm clearance, 36m clearance, 36pm clearance 70pm clearance, 36m clearance, 36pm clearance 36pm clearance, 70m clearance [0063] Rout Kccp Out (RKO) from Clearance rues RKO Shapc 131.7x113.6 Physical Bump dimension : 62x80 FCPad RKO shape creation Global view Zoom view [0064] Prove of concept: Bump Density Checks Criteria to measure the density : To correctly count the number of bump in a zone : - Bump center should be in the Zone - We should have no RKO overlaps. - Bump should follow the centripetal algorithm. - Bump should be fully enclosed in the die size but the RKO could be outside (*). Die size is defined by 6863.679 x 6915.498 The count is donc per drawn Zone ( cf picture) dimensions [0065] Scope of the invention [0066] Short tenus is related to products using TSMC Wafers (Any 16nm and below Front End technology) [0067] Medium terni could be deployed to products using various FE technology (from ST 6 or External Foundrics) [0068] Advantagcs versus known solutions [0069] The advantagcs arc the following: [0070] Minimizc Die Size Increasc to the strict minimum (as wc arc using a kind of highly- customizcd Bump Pitch increase) [0071] No dcgradation on failurc risk (both Time zero and reliability) [0072] Minimizc dcnsity loss comparcd to staggered bump matrix [0073] Maximize the bumps count AJOUTER DES -CLUE SPECIFIC' : Ex. % UBM or % Die Size increase entre les solutions conventionnelles et celle-ci [0074] Tt is the ncw and the most optimized solution for solving the technical problem (cxisting one arc significantly lcss competitive or more risky). [0075] Today, bump rnatrix crcation arc following the staggercd rulcs. By introducing a con- tripctal algorithm, the invention can minimize dcnsity loss comparcd. [0076] Keywords [0077] Bumping technology, Fine bump pitch. [0078] Solution detectability [0079] What would be the hint to identify the product concerned? [0080] 7FF/16FF production with aggressive pitch [0081] What would it takc to provo the use of your solution? [0082] 3D- XRAY view (none destructive) [0083] Comparison between Bump count vs Die size in Datasheet [0084] Various embodiments and variants have been described. Those skilled in the art will understand that certain features of these embodiments can be combined and other variants will readily occur to those skilled in the art. [0085] Finally, REVENDICATIONS1. A substrate comprising a contact surface having humps formcd thercon, cach bump heing rotationally asymmetric in the plane of thc contact surface, thc humps for example heing orientated on the contact surface in a centripetal arrangement, wherein thc humps in a first zone of the contact surface havc a first pitch in a first axis and the humps in a sccond zone of the contact surface havc a second pitch in the first axis, thc second pitch heing diffcrent to the first pitch. 2. The substrate of claim 1, whercin a hump dcnsity in the first zone is different from a bump density in the second zone. 3. The substrate of claim 1 or 2, wherein there is an exclusion zone around each of the bumps in which no other bump is formed, wherein the exclusion zone for example has a first width in a first axis and a second width in a second axis perpendicular to the first axis, the first and second widths being different from each other. 4. The substrate of claim 3, wherein the exclusion zone is hexagonal or substantially hexagonal. 5. The substrate of any of claims 1 to 4, wherein each bump is oblong in shape, or substantially oblong in shape. 6. A substrate comprising a contact surface having bumps formed thereon, each bump being rotationally asymmetric in the plane of the contact surface, the bumps for example being orientated on the contact surface in a centripetal arrangement, wherein the centers of the bumps are positioned in a first pattern in a first zone of the contact surface and in a second pattem, different to the first pattern, in a second zone of the contact surface, the first and second patterns for example defining the spacing between the centers of the bumps in the plane of the contact surface. 7. The substrate of any of claims 1 to 6, wherein the first zone is a central zone of the contact surface, and the second zone is an annular zone surroundine the central zone. 8. A substrate comprising a contact surface having bumps formed thereon, each bump being rotationally asymmetric in the plane of the contact surface, the bumps for example being orientated on the contact surface in a centripetal arraneement, wherein the bumps are positioned such that the centers of the bumps in the plane of the contact surface are not aligned. 8 9. A method of circuit conception irnplemented by a processing &vice under control of software instructions, the method comprising: defining dimensions of cach pump in the plane of a contact surface defined by a circuit design; and autotnatically performing placement of bumps on the contact surface such that the bumps arc for example orientated on the contact surface in a centripetal arrangement, and/or such that the bumps in a first zone of the contact surface have a first pitch in a first axis and the bumps in a second zone of the contact surface have a second pitch in the first axis, the second pitch bcing differcnt to the first pitch. 10. A method of circuit conception irnplemented by a processing &vice under control of software instructions, the method comprising: defining dimensions of cach pump in the plane of a contact surface defined by a circuit design; and automatically performing placement of bumps on the contact surface such that the bumps arc for example oricntatcd on the contact surface in a centripctal arrangement, and/or such that the centers of the bumps arc positioncd in a first pattern in a first zone of the contact surface and in a second pattern, diffcrent to the first pattern, in a second zone of the contact surface, the first and second patterns for example defining the spacing between the centers of the bumps in the plane of the contact surface. 11. A method of circuit conception implemented by a processing device under control of software instructions, the method comprising: defining dimensions of each pump in the plane of a contact surface defined by a circuit design; and automatically performing placement of bumps on the contact surface such that the bumps are for example orientated on the contact surface in a centripetal arrangement, and/or such that the bumps are positioned such that the centers of the bumps in the plane of the contact surface are not aligned.