Source: http://www.google.com/patents/US6369441?dq=6,360,693
Timestamp: 2017-10-22 21:52:30
Document Index: 715416152

Matched Legal Cases: ['art 9', 'art 39', 'arts 60', 'arts 60', 'arts 60', 'arts 60', 'art 58', 'arts 60', 'arts 60', 'art 60', 'art 65', 'arts 60', 'arts 60']

Patent US6369441 - Method of producing a semiconductor chip having an underplate metal layer - Google Patents
To enable readily forming the etching stop layer of a lead frame with multilayer structure by plating without using a large-scale device, enhance adhesive strength between the etching stop layer and an adjacent metal layer and prevent peeling caused by deterioration caused by the invasion of a chemical...http://www.google.com/patents/US6369441?utm_source=gb-gplus-sharePatent US6369441 - Method of producing a semiconductor chip having an underplate metal layer
Publication number US6369441 B1
Application number US 09/702,437
Also published as US6140153, US6351025, US6403402
Publication number 09702437, 702437, US 6369441 B1, US 6369441B1, US-B1-6369441, US6369441 B1, US6369441B1
Inventors Kenji Ohsawa, Hidetoshi Kusano
Patent Citations (21), Referenced by (2), Classifications (50), Legal Events (5)
Method of producing a semiconductor chip having an underplate metal layer
US 6369441 B1
a semiconductor device wherein:
plural leads are formed on an a same surface of an insulating layer as which said semiconductor device is located so that the surface of said lead and the surface of said insulating layer are located on the same plane;
plural openings for respectively exposing said plural leads are formed on the surface reverse to said surface of said insulating layer;
an external electrode is formed at each opening;
the electrode of said semiconductor device is electrically connected to said plural leads;
an outside ring composed of a thicker metal layer than said lead is provided in the periphery of a part in which said plural leads are formed via a suspending part; and
said outside ring is provided with a metal lamination in which a metal layer composed of nickel or a nickel alloy is formed on the side of said suspending part, wherein:
said semiconductor device is electrically connected to an electrode on said circuit board via said external electrode.
This application is a divisional of U.S. application Ser. No. 09/084,189 FILED May 26, 1998 now U.S. Pat. No. 6,140,153. The present and foregoing applications claim priority to Japanese application No. P09-136776 filed May 27, 1997. All of the foregoing applications are incorporated herein by reference to the extent permitted by law.
(F) Next, as shown in FIG. 11A, the inside from a part 9 to be an outside ring of the thick copper layer 2 located on the rear side of the lead frame material 1 is selectively etched from the rear side. In the above etching, etchant such as H2SO4 and H2O2 is used for example. The reason is that the above etchant erodes copper, however, it does not erode aluminum and an aluminum layer 3 a can function as an etching stopper. In this process, the aluminum layer 3 a is left except a part removed in the selective etching shown in FIG. 10C.
(G) Next, as shown in FIG. 11B, the underplate layer 4 under the leads 5 and the aluminum layer 3 a as an etching stopper are etched using the above leads 5 and the left thick copper layer 2 as a mask. Hereby, each lead 5 is separated and is released from a state in which each lead is mutually electrically short-circuited.
Therefore, according to the lead frame disclosed in claim 1, as the etching stop layer is formed by nickel or a nickel alloy, it can be formed by plating. Therefore, as a high-priced vapor deposition device or sputtering device for vapor deposition or sputtering required in a case that aluminum is used for an etching stop layer is not required, the cost of facilities can be reduced and as a result, the cost of a lead frame or a semiconductor device using it can be reduced.
The semiconductor device disclosed in claim 4 is characterized in that plural leads are formed on the surface on the side of the semiconductor device of the insulating layer so that the surface of the leads and the surface of the insulating layer are located on the same plane, the end of a part protruded from the insulating layer of each lead functions as a terminal connected to the electrode of the semiconductor device on the side of said semiconductor device, an opening for exposing each lead is formed in a part on the reverse side to the semiconductor device of the insulating layer, an electrode on the reverse side to the semiconductor device of the lead is formed at each opening, the semiconductor device is connected to the electrode via the terminal on the side of the semiconductor device, and the outside ring composed of a thicker metal layer than the lead and provided with a layer composed of nickel or a nickel alloy on the side of the surface for surrounding the semiconductor device is provided on the side of the surface outside a part in which the leads are formed.
A first lead frame according to the present invention is characterized in that an etching stop layer provided between an outer lead and an inner lead composed of a thin wiring layer is formed by nickel or a nickel alloy and a second lead frame is characterized in that an etching stop layer between a lead composed of a thin metal layer and an outside frame or an outside ring composed of thick metal is formed by nickel or a nickel alloy.
A method of manufacturing the lead frame according to the present invention is characterized in that in the method of manufacturing the lead frame at least provided with an etching process for selectively etching metal layers using the etching stop layer as an etching stopper in a state in which a thick metal layer is formed on one side of the etching stop layer as an intermediate layer and a thin metal layer is formed on the other side and a process for etching the etching stop layer using the metal layers on both sides as a mask, the etching stop layer is formed by nickel or a nickel alloy. In the etching process for selectively etching the metal layers using the etching stop layer as an etching stopper, etchant the etching speed to nickel or a nickel alloy of which is slow and the etching speed to the metal layers formed on both sides of which is remarkably fast is naturally used. Any etchant may be also used if it is provided with such a property, however, if the metal layer is composed of copper or a copper alloy, for example, the mixed solution of aqueous ammonia the chemical formula of which is NH4OH NH3 and the concentration of which is 15% or more for example and cupric chloride the chemical formula of which is CuCl2 and the density of which is 20% or more for example is suitable.
The etching stop layer 22 is composed of nickel or a nickel alloy. As nickel or a nickel alloy is metal which is not etched by etchant for the metal layers 23 and 24, for example the mixed solution of aqueous ammonia the chemical formula of which is NH4OH NH3 and the concentration of which is 15% or more for example and cupric chloride the chemical formula of which is CuCl2 and the density of which is 20% or more for example, the above metal is selected for the material of the etching stop layer 22, and the etching stop layer 22 plays a part of preventing one of the metal layers 23 and 24 from being etched by etching for the other later.
(B) Next, as shown in FIG. 1B, photo resist films 25 a and 25 b are respectively selectively formed on each surface of the metal layers 23 and 24. The photo resist film 25 a formed on the surface of the thick metal layer 23 is provided with a pattern constituting a part except the inner lead of the lead frame and the photo resist film 25 b formed on the surface of the thin metal layer 24 is provided with a pattern constituting a part to be particularly thick such as the inner lead and the vicinity of a guide hole 26. The width of an opening of the photo resist film 25 is normally set to 10 to 20 μm at the minimum, however, the width of an opening in a part to be thick such as the vicinity of the guide hole 26 is required to be set in consideration of the quantity of side etching.
(C) Next, the surface of the thick metal layer 23 of the lead frame material 1 is etched using for example the mixed solution of aqueous ammonia the chemical formula of which is NH4OH NH3 and the concentration of which is 15% or more for example and cupric chloride the chemical formula of which is CuCl2 and the density of which is 20% or more for example. Then, as shown in FIG. 1C, the metal layer 23 is selectively etched and an outer lead 27 which is the body of the lead frame is formed.
Afterward, the photo resist films 25 a and 25 b are removed by a solvent. FIG. 2A is a perspective drawing showing the state after the photo resist films 25 a and 25 b are removed.
In the above example, the peeling of the photo resist films 25 a and 25 b and the removal of the etching stop layer 22 respectively after selective etching is finished are separately done, however, they may be also simultaneously done. If an ultrasonic wave is applied when the resists are removed, the resists can be readily removed.
FIG. 3 shows a semiconductor device using a lead frame in which a bump 30 composed of an etching stop layer 22 is formed at the end of an inner lead 28 by varying a part of the method shown in FIGS. 1. The lead frame can be formed by masking a part in which the bump 30 of the etching stop layer 22 is to be formed with a photo resist film again after metal layers 23 and 24 of lead frame material 21 are selectively etched and photo resist films 25 a and 25 b are removed according to the method of manufacturing the lead frame shown in FIGS. 1 and by etching the etching stop layer 22 afterward. Needless to say, the above method is not different from the embodiment shown in FIGS. 1 as to the use of etchant. A reference number 41 in FIG. 3 denotes a semiconductor device, 41 a denotes an electrode pad and 42 denotes resin.
(A) Lead frame material 31 with three-layer structure shown in FIG. 4A is prepared. The lead frame material 31 is formed by forming a nickel film 33 to be an etching stop layer approximately 3 μm thick for example by plating on the surface of a substrate 32 approximately 50 to 200 μm thick for example composed of copper or a copper alloy and further by forming an underplate layer 34 approximately 0.1 to 2 μm thick for example composed of thin copper or nickel. The lead frame material 31 is an outside ring in a final process. The underplate layer 34 is formed to enhance the adhesiveness of leads described later and is not necessarily inevitable.
(C) Next, as shown in FIG. 4C, a lead frame in which plural film circuits are integrated by selectively etching the lead frame material 31 from both sides so that the selective etching pierces a predetermined part of the lead frame material is formed. In etching, for example, the mixed solution of aqueous ammonia the chemical formula of which is NH4OH NH3 and the concentration of which is 15% or more for example and cupric chloride the chemical formula of which is CuCl2 and the density of which is 20% or more for example is used for etchant.
(F) Next, as shown in FIG. 5A, a part inside a part 39 to be an outside ring of the thick copper layer 32 located on the rear side of the lead frame material 31 is removed by selectively etching from the rear side. In the above etching, the mixed solution of aqueous ammonia the chemical formula of which is NH4OH NH3 and the concentration of which is 15% or more for example and cupric chloride the chemical formula of which is CuCl2 and the density of which is 20% or more for example is used for etchant. The reason is that the above etchant erodes copper, however, it does not erode nickel and nickel or a nickel alloy 33 can function as an etching stopper. In this process, nickel or a nickel alloy 33 is left except the part removed in the selective etching shown in FIG. 4C.
(B) Next, as shown in FIG. 7B, leads 53 and suspending parts 60 (The suspending parts 60 are not shown in FIGS. 7. See FIG. 9.) are formed on the above underplate layer 64. Concretely, the leads and the suspending parts 60 are formed by applying resist according to the negative pattern of a pattern according to which the leads 53 and the suspending parts 60 are to be formed and plating copper or nickel so that it is 30 μm thick for example using the resist as a mask and using the layer 64 as underplate.
(C) Next, as shown in FIG. 7C, a lead frame in which plural film circuits are integrated by selectively etching the metal laminate 51 from both sides so that selective etching pierces a predetermined part of the metal laminate is formed. In the above etching, for example etchant including ferric chloride composed of the mixed solution of aqueous ammonia the chemical formula of which is NH4OH NH3 and the concentration of which is 15% or more for example and cupric chloride the chemical formula of which is CuCl2 and the density of which is 20% or more for example is used.
(D) Next, as shown in FIG. 7D, an insulating layer (an insulating film) 52 is selectively formed on the surface on the side on which leads are formed of the above laminate 51. Resin material provided with photosensitivity is used for the insulating layer 52 and a desired pattern is formed by applying, exposing and developing it. Reference numbers 61 and 62 denote an opening of the insulating layer 52 for exposing a part in which ball electrode 56 of each lead 53 is to be formed and the insulating layer 52 is selectively etched so that the opening 61 is provided.
(E) Next, as shown in FIG. 7E, solder balls 56 to be external terminals are formed on the surface of each lead 53 using the insulating layer 52 as a mask. The solder balls 56 are formed by nickel plate 80 to 110 μm thick for example and solder or gold plate 0.1 to 5 μm thick for example or palladium.
(F) Next, as shown in FIG. 7F, a part inside a part 58 to be an outside ring of the thick copper layer 62 located on the rear side of the laminate 51 is removed by selectively etching from the rear side. In the above etching, etchant including ferric chloride composed of the mixed solution of aqueous ammonia the chemical formula of which is NH4OH NH3 and the concentration of which is 15% or more for example and cupric chloride the chemical formula of which is CuCl2 and the density of which is 20% or more for example is used. The reason is that the above etchant erodes copper, however, it does not erode nickel and a nickel layer 63 can function as an etching stopper.
(G) Next, as shown in FIG. 7G, the underplate layer 64 under the leads 53 and the etching stop layer 63 which is an etching stopper and composed of nickel or a nickel alloy are etched using the leads 53 and the suspending parts 60 (The suspending parts 60 are not shown in FIGS. 7. See FIG. 9.) as a mask. In the above etching, the mixed solution of sulfuric acid and the solution of hydrogen peroxide for example is used. Hereby, each lead 53 and each suspending part 60 are separated and are released from a state in which they are mutually electrically short-circuited. A reference number 65 denotes the main part of the lead frame 51 and the main part 65 seems as if it were separated from the outside ring 58 in FIG. 7G, however, it is because the suspending parts 60 are not shown in the sectional view of FIG. 7G and actually, the main part is integrated with the outside ring 58 via the suspending parts 60.
(H) Next, if necessary, as shown in FIG. 7H, a bump 66 is formed at the end 53 a of each lead 53. Therefore, a bump may be formed on the side of a semiconductor device 54 and no bump may be formed.
FIGS. 8A to 8D show the assembly of the lead frame 51 the processes shown in FIGS. 7 of which are finished and the semiconductor device 41 in the order of processes.
(B) Next, as shown in FIG. 8B, the bump 66 at the end 3 a of each lead 53 is connected to the electrode pad 55 of the semiconductor device 41 by single point bonding for example.
US6140153 * May 26, 1998 Oct 31, 2000 Sony Corporation Lead frame, the manufacturing method, semiconductor device and the manufacturing method
US6240632 * Sep 19, 1996 Jun 5, 2001 Sony Corporation Method of manufacturing lead frame and integrated circuit package
WO1998034278A1 Jan 21, 1998 Aug 6, 1998 Nippon Denkai, Ltd. Lead frame material
US7371616 * Jan 5, 2006 May 13, 2008 Fairchild Semiconductor Corporation Clipless and wireless semiconductor die package and method for making the same
U.S. Classification 257/673, 257/676, 257/738, 257/E23.019, 361/813, 257/E23.124, 257/E23.041, 257/E23.036, 257/690, 361/723, 257/E23.055, 257/E23.14, 257/E23.034, 257/E23.054
International Classification H01L23/50, H01L23/12, H01L21/48, H01L23/485, H01L23/495, H01L23/31, H01L23/24
Cooperative Classification H01L2924/00014, Y10T29/49121, H01L24/48, H01L23/49582, H01L21/4828, H01L23/49531, H01L23/3128, H01L23/485, H01L2924/1532, H01L23/49534, H01L23/49572, H01L2924/01078, H01L2924/01046, H01L2224/48095, H01L23/3107, H01L2924/01079, H01L23/49524, H01L2924/15311, H01L23/24
European Classification H01L23/31H2B, H01L23/495D, H01L23/495M1, H01L23/485, H01L23/495C8, H01L23/495J, H01L23/495C4, H01L23/24, H01L23/31H, H01L21/48C3E