JP2014041899A - Method for manufacturing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that since resin containing a hard silica system filler or the like vigorously flows to a gate part communicating with a cavity part in a mold die, and the abrasion of those surfaces is easily advanced, it is thought to be valid that the gate part, that is, gate insert is constituted of materials whose hardness is higher than that of materials constituting the cavity part or the like for increasing abrasion resistance, and that since copper ion such as a copper system lead frame is diffused to a cobalt part as the binder part of a sintered body in a portion where the copper system lead frame and the gate insert are brought into contact with each other, the binder part becomes fragile, and peels in cleaning or the like.SOLUTION: In a transfer mold process in a method for manufacturing a semiconductor device, a portion where the gate insert of a mold die is brought into contact with at least a copper system lead frame is coated with a coat member film having copper diffusion preventing property.

Description

  The present application relates to a method for manufacturing a semiconductor device (or a semiconductor integrated circuit device), and more particularly to a technique effective when applied to a resin sealing technique.

  Japanese Unexamined Patent Publication No. 2010-263066 (Patent Document 1) relates to resin sealing of a semiconductor device. This discloses a transfer mold die body whose surface is chrome-plated, and a gate insert made of tungsten-based cemented carbide installed in the gate portion thereof.

  Japanese Laid-Open Patent Publication No. 6-151490 (Patent Document 2) similarly relates to resin sealing of a semiconductor device. There is disclosed a technique for cluster diamond coating almost the entire inner surface of a transfer mold.

JP 2010-263066 A JP-A-6-151490

  In the mold, in the gate part communicating with the cavity part, the resin containing hard silica filler etc. flows vigorously, so that the wear of these surfaces easily proceeds. Therefore, in order to increase the wear resistance, a mold that constitutes the gate part, that is, the gate insert, with a material harder than the material that constitutes the cavity part (for example, tungsten carbide-cobalt carbide) is effective. It is said that.

  The inventors have examined such a mold and found that the following problems occur. That is, in the portion where the copper-based lead frame (for example, copper lead frame) and the gate insert are in contact, the copper ions of the copper-based lead frame diffuse into the cobalt portion that is the binder portion of the sintered body. This is a problem that the binder part becomes brittle and peels off during cleaning or the like.

  Means for solving such problems will be described below, but other problems and novel features will become apparent from the description of the present specification and the accompanying drawings.

  An outline of representative ones of the embodiments disclosed in the present application will be briefly described as follows.

  In other words, an outline of an embodiment of the present application is that a surface having a property of preventing diffusion of copper in at least a portion of a gate insert of a mold die that comes into contact with a copper-based lead frame in a transfer molding process in a manufacturing method of a semiconductor device. It is coated with a coating member film.

  The effects obtained by the representative ones of the embodiments disclosed in the present application will be briefly described as follows.

  That is, according to one embodiment of the present application, damage to the gate insert can be reduced.

It is a process flowchart which shows the outline of the assembly & resin sealing process in the manufacturing method of the semiconductor device of one embodiment of this application. It is a wafer perspective view of the assembly & resin sealing process (at the time of dicing process completion) in the manufacturing method of the semiconductor device of one embodiment of this application. It is a perspective view of a unit device region of a lead frame in an assembly and resin sealing step (die bonding step) in the method of manufacturing a semiconductor device according to an embodiment of the present application. It is a perspective view of a unit device region of a lead frame in an assembly & resin sealing step (wire bonding step) in the method for manufacturing a semiconductor device of one embodiment of the present application. It is a perspective view of a unit device region of a lead frame in an assembly and resin sealing step (resin sealing step) in the method of manufacturing a semiconductor device according to an embodiment of the present application. It is a perspective view of the unit device of the assembly & resin sealing process (device separation process) in the manufacturing method of the semiconductor device of one embodiment of this application. 1 is a schematic cross-sectional view (in a state where a mold is opened) showing the structure and function of an upper and lower mold used in a resin sealing step that is a main part of a method for manufacturing a semiconductor device according to an embodiment of the present application. FIG. 2 is a schematic cross-sectional view (in a state where the mold is closed and the resin is filled) showing the structure and operation of the upper and lower molds used in the resin sealing step, which is the main part of the method of manufacturing a semiconductor device according to an embodiment of the present application. is there. It is a metal mold | die top view for demonstrating the structure of the lower metal mold | die used for the resin sealing process which is the principal part of the manufacturing method of the semiconductor device of one embodiment of this application. It is a metal mold | die bottom view for demonstrating the structure of the upper metal mold | die used for the resin sealing process which is the principal part of the manufacturing method of the semiconductor device of one embodiment of this application. It is a top view (for explanation of each part of a lead frame) of a lead frame (bonding wire etc. are omitted) in a resin sealing process which is a main part of a manufacturing method of a semiconductor device of one embodiment of this application. It is a top view (for explanation of each part relation of a lead frame, a mold, etc.) of a lead frame (bonding wire etc. are omitted) in a resin sealing process which is a main part of a manufacturing method of a semiconductor device of one embodiment of this application. FIG. 13 is an enlarged transparent top view of the lower left quarter of the unit region of the lead frame (lead frame & chip composite) of FIG. 12 (displayed so that the structure of the lower cavity block can be seen). FIG. 14 is a partially enlarged transparent top view of the inflow gate portion of FIG. 13 (for explaining the contact portion with the lead frame). FIG. 14 is a partially enlarged transparent top view of the inflow gate portion of FIG. 13 (for explaining the lead clamp surface). FIG. 15 is a perspective view of the lower mold viewed from the direction of the arrow VP in FIG. 14 (the height direction is the arrow VP in FIG. 19) (the lead frame is not shown for easy viewing). FIG. 17 is an enlarged perspective view of the gate insert piece of FIG. 16 and its surroundings. FIG. 16 is a cross-sectional view of the periphery of the gate portion of FIG. 8 corresponding to the A-A ′ cross section of FIGS. FIG. 16 is a sectional view of the periphery of the gate portion of FIG. 7 (when a lead frame is placed) corresponding to the P-P ′ section of FIGS. 14 and 15. FIG. 16 is a sectional view of the periphery of the gate portion of FIG. 8 (the sealing resin is not shown for the sake of clarity) corresponding to the P-P ′ section of FIGS. 14 and 15. FIG. 18 to FIG. 20 and other details of the gate insert piece main body portion for explaining details of the structure and material of the gate insert piece used in the resin sealing step in the method of manufacturing a semiconductor device according to the one embodiment of the present application. FIG. FIG. 15 is a schematic enlarged sectional view of T-T ′ of the gate insert piece and the lead frame in FIG. 14 (other parts are not shown for the sake of clarity; the same applies hereinafter). FIG. 23 is a schematic enlarged cross-sectional view corresponding to FIG. 22 showing a state where the surface coat member film of the gate channel is removed as a result of using the gate insert piece of FIG. 22. FIG. 23 is a schematic enlarged cross-sectional view corresponding to FIG. 22 illustrating an example in which a surface coat member film is not formed on a partial surface of a gate insert piece for reasons such as a method for forming a surface coat member film. The periphery of the gate corresponding to FIG. 20 for explaining Modification 1 (local coating) relating to the structure and material of the gate insert piece used in the resin sealing step in the method of manufacturing a semiconductor device according to the one embodiment of the present application It is sectional drawing. FIG. 26 is a schematic enlarged cross-sectional view corresponding to FIG. 22 and showing a cross section (T-T ′ cross section of FIG. 14) of the gate insert piece of FIG. 25. The gate corresponding to FIG. 22 for explaining the modification 2 (clamp surface whole surface coating) concerning the structure & material of the gate insert piece used in the resin sealing step in the manufacturing method of the semiconductor device of the one embodiment of the present application FIG. A gate portion corresponding to FIG. 22 for explaining Modification 3 (overall surface coating) relating to the structure and material of the gate insert piece used in the resin sealing step in the method of manufacturing a semiconductor device according to the embodiment of the present application. FIG. It is a mold mold schematic cross section for demonstrating the metal mold | die cleaning process relevant to the resin sealing process in the manufacturing method of the semiconductor device of the said one Embodiment of this application. It is a metal mold | die principal part schematic sectional drawing showing the outline of the said one Embodiment.

[Outline of Embodiment]
First, an outline of a typical embodiment disclosed in the present application will be described.

1. A semiconductor device manufacturing method including the following steps:
(A) A copper-based lead frame on which the semiconductor chip is mounted is formed by the lower mold and the upper mold so that the semiconductor chip is accommodated in a mold cavity formed between the lower mold and the upper mold. The step of clamping;
(B) After the step (a), the sealing resin is transferred into the mold cavity through the gate formed on the lower mold or the upper mold with the copper lead frame clamped. And forming a resin sealing body in which the semiconductor chip is sealed by filling the mold cavity with the sealing resin;
(C) After the step (b), the lower mold and the upper mold are opened, and the copper-based lead frame is taken out between them.
here,
(I) A gate insert piece is set in the gate portion of the lower mold or the upper mold,
(Ii) The gate insert piece is formed of a hard material harder than the lower mold or the upper mold around the gate insert piece, and includes the following:
(X1) gate flow path;
(X2) lead clamp surfaces provided on both sides of the gate channel;
(X3) A surface coat member film having a property of preventing the diffusion of copper is formed on a portion of at least the lead clamp surface that comes into contact with the copper-based lead frame when it is clamped.

  2. In the method of manufacturing a semiconductor device according to Item 1, the surface coat member film is formed on at least the entire surface of the lead clamp surface.

  3. In the method of manufacturing a semiconductor device according to Item 1, the surface coat member film is formed on the entire surface of the gate insert piece.

  4). In the method for manufacturing a semiconductor device according to any one of Items 1 to 3, the cemented carbide material constituting the main body portion of the gate insert piece is a tungsten carbide-based sintered body.

  5. In the method for manufacturing a semiconductor device according to any one of Items 1 to 3, the super hard material constituting the main body portion of the gate insert piece is a tungsten carbide-cobalt based sintered body.

  6). In the method for manufacturing a semiconductor device according to any one of Items 1 to 5, the surface coat member film is formed of a chromium member film.

  7). In the method of manufacturing a semiconductor device according to any one of Items 1 to 5, the surface coat member film is a hard chrome plating film.

  8). In the method for manufacturing a semiconductor device according to any one of Items 1 to 5, the surface coat member film is formed of a titanium member film.

  9. In the method for manufacturing a semiconductor device according to any one of Items 1 to 5 and 8, the surface coat member film is a titanium member film formed by thermal spraying.

  10. In the method for manufacturing a semiconductor device according to any one of Items 1 to 5, the surface coat member film is formed of a sintered diamond member film.

11. The method for manufacturing a semiconductor device according to any one of Items 1 to 10, further including the following steps:
(D) After the step (c), a cleaning resin sheet is sandwiched between the lower mold and the upper mold, heated and compressed, and then the cleaning resin sheet is peeled off, whereby the lower mold and Cleaning the surface of the upper mold.

  12 In the method for manufacturing a semiconductor device according to any one of Items 1 to 11, the lower mold and the main body of the upper mold are made of die steel.

[Description format, basic terms, usage in this application]
1. In the present application, the description of the embodiment may be divided into a plurality of sections for convenience, if necessary, but these are not independent from each other unless otherwise specified. Each part of a single example, one part is the other part of the details, or part or all of the modifications. Moreover, as a general rule, the same part is not repeated. In addition, each component in the embodiment is not indispensable unless specifically stated otherwise, unless it is theoretically limited to the number, and obviously not in context.

  Further, in the present application, the term “semiconductor device” or “semiconductor integrated circuit device” mainly refers to various types of transistors (active elements) alone, and resistors, capacitors, etc. as semiconductor chips (eg, single crystal). A silicon substrate) or a semiconductor chip packaged. Here, as a representative of various transistors, a MISFET (Metal Insulator Semiconductor Effect Transistor) typified by a MOSFET (Metal Oxide Field Effect Transistor) can be exemplified. At this time, as a typical integrated circuit configuration, a CMIS (Complementary Metal Insulator Semiconductor) integrated circuit represented by a CMOS (Complementary Metal Oxide Semiconductor) integrated circuit combining an N-channel MISFET and a P-channel MISFET. Can be illustrated.

  The wafer process of today's semiconductor device, that is, LSI (Large Scale Integration), can be usually divided into two processes. That is, the first consists of carrying in a silicon wafer as a raw material to a premetal process (formation of an interlayer insulation film between the lower end of the M1 wiring layer and the gate electrode structure, contact hole formation, tungsten plug, embedding, etc. This is a FEOL (Front End of Line) process. The second is BEOL (Back End of Line) starting from the formation of the M1 wiring layer until the formation of the pad opening in the final passivation film on the aluminum-based pad electrode (including the process in the wafer level package process). It is a process.

  The “semiconductor device” includes a single electronic device such as a power transistor.

  2. Similarly, in the description of the embodiment and the like, the material, composition, etc. may be referred to as “X consisting of A”, etc., except when clearly stated otherwise and clearly from the context, except for A It does not exclude what makes an element one of the main components. For example, as for the component, it means “X containing A as a main component”. For example, “silicon member” is not limited to pure silicon, but also includes SiGe alloys, other multi-component alloys containing silicon as a main component, and members containing other additives. Needless to say.

  3. Similarly, suitable examples of graphics, positions, attributes, and the like are given, but it is needless to say that the present invention is not strictly limited to those cases unless explicitly stated otherwise, and unless otherwise apparent from the context. Therefore, for example, “square” includes a substantially square, “orthogonal” includes a case where the two are substantially orthogonal, and “match” includes a case where the two substantially match. The same applies to “parallel” and “right angle”. Therefore, for example, a deviation of about 10 degrees from perfect parallel belongs to substantially parallel.

  In addition, for a certain region, “whole”, “whole”, “whole area” and the like include cases of “substantially whole”, “substantially general”, “substantially whole area” and the like. Therefore, for example, 80% or more of a certain region can be referred to as “substantially the whole”, “substantially general”, and “substantially the entire region”. The same applies to “all circumferences”, “full lengths”, and the like.

  Further, regarding the shape of a certain object, “rectangular” includes “substantially rectangular”. Therefore, for example, if the area of the portion different from the rectangle is less than about 20% of the whole, it can be said to be almost rectangular. The same applies to “annular” and the like.

  Also, with regard to periodicity, “periodic” includes almost periodic, and for each element, for example, if the deviation of the period is less than about 20%, each element is said to be “almost periodic”. it can. Furthermore, if what is out of this range is, for example, less than about 20% of all elements that are targets of the periodicity, it can be said to be “substantially periodic” as a whole.

  Note that the definitions in this section are general, and when there are different definitions in the following individual descriptions, priority is given to the individual descriptions for this part. However, the definition, provisions, etc. of this section are still valid for parts that are not stipulated in the individual description part, unless explicitly denied.

  4). In addition, when a specific number or quantity is mentioned, a numerical value exceeding that specific number will be used unless specifically stated otherwise, unless theoretically limited to that number, or unless otherwise clearly indicated by the context. There may be a numerical value less than the specific numerical value. In the present application, regarding the number, “many” is a concept including “plurality”.

  5. “Wafer” usually refers to a single crystal silicon wafer on which a semiconductor device (same as a semiconductor integrated circuit device and an electronic device) is formed, but an insulating substrate such as an epitaxial wafer, an SOI substrate, an LCD glass substrate, and the like. Needless to say, a composite wafer such as a semiconductor layer is also included.

  6). In the present application, the “copper-based lead frame” or “copper lead frame” is a metal member containing copper as a main component, and usually contains 95% by weight or more of copper. Specific examples include oxygen-free copper, Cu—Sn alloy, Cu—Zr alloy, Cu—Fe alloy, Cu—Ni—Si alloy, Cu—Cr—Sn—Zn alloy, and the like.

  The “super hard material” is also called a cemented carbide, and is an alloy made by sintering hard metal carbide powder. Representatively, WC-Co cemented carbide (tungsten carbide-cobalt cemented carbide) obtained by mixing and sintering tungsten carbide powder and cobalt as a binder (for example, WC: 94 vol%, Co: 6 vol%). However, if necessary, titanium carbide, tantalum carbide or the like may be added. In addition, a slight amount of nickel, platinum, palladium, or the like may be added as a accelerating agent for sintering. Accordingly, in the present application, a tungsten carbide-based sintered body or a tungsten carbide-based carbide material including tungsten carbide cemented carbide member containing various additives is mainly used. Called “super hard material”. Of these, those having cobalt as the main binder member are called “tungsten carbide-cobalt-based sintered bodies” or “tungsten carbide-cobalt-based cemented carbide”. Besides, there are tungsten carbide-tantalum carbide-cobalt cemented carbide, tungsten carbide-titanium carbide-cobalt cemented carbide, tungsten carbide-titanium carbide-tantalum carbide-cobalt cemented carbide, and the like. Usually, the cobalt content in these materials is in the range of several volume% to several tens volume%. Therefore, normally, the composition of WC in the grain boundary component excluding the binder component in the tungsten carbide cemented carbide (the whole grain boundary component is 100) is in the range of 60% by volume to 100% by volume.

  “Die Steel” is a tool material used for molding plastics and the like. For example, carbon steel or, if necessary, a small amount of tungsten, chromium, molybdenum, tungsten, nickel, Vanadium or the like is added (the total amount of additives is less than 10% by weight).

  The “chrome member film” is a metal film containing chromium as a main component (for example, a metal film of 90% by weight or more of chromium). Similarly, the “titanium member film” is a metal film containing titanium as a main component (for example, a metal film of 90% by weight or more of titanium).

  The “hard chrome plating film” is a kind of chromium member film, and is a metal film having a Vickers hardness of 750 or more formed by electrolytic plating.

  The “sintered diamond member film” is a non-metallic member film made of a sintered body obtained by sintering diamond powder having a particle diameter of about several micrometers to several tens of micrometers under ultra high pressure and high temperature.

  “Surface coat member film having the property of preventing copper diffusion” means a film having an effect of preventing copper diffusion in a temperature range equal to or lower than the resin mold temperature, A film that can be coated on the surface.

  In the present application, among the mold components, the cavity block and the main mold part in the vicinity of the cavity block may be simply referred to as “mold (lower mold, upper mold)”. This is because the mold component is composed of a large number of blocks and parts, and it is difficult to accurately represent all of them.

[Details of the embodiment]
The embodiment will be further described in detail. In the drawings, the same or similar parts are denoted by the same or similar symbols or reference numerals, and description thereof will not be repeated in principle.

  In the accompanying drawings, hatching or the like may be omitted even in a cross section when it becomes complicated or when the distinction from the gap is clear. In relation to this, when it is clear from the description etc., the contour line of the background may be omitted even if the hole is planarly closed. Furthermore, even if it is not a cross section, it may be hatched to clearly indicate that it is not a void.

  In addition, regarding the designation in the case of the alternative, when one is referred to as “first” or the like and the other is referred to as “second” or the like, it is exemplified in association with the representative embodiment. Of course, for example, “first” is not limited to the illustrated option.

1. Description of outline of assembly & resin sealing step in manufacturing method of semiconductor device of one embodiment of the present application (mainly FIGS. 1 to 6)
It goes without saying that the assembly and resin sealing step shown below is an example and can be variously changed.

  FIG. 1 is a process flow diagram showing an outline of an assembly and resin sealing step in a method of manufacturing a semiconductor device according to an embodiment of the present application. FIG. 2 is a perspective view of the wafer in the assembly and resin sealing step (when the dicing step is completed) in the semiconductor device manufacturing method according to the embodiment of the present application. FIG. 3 is a perspective view of the unit device region of the lead frame in the assembly and resin sealing step (die bonding step) in the method of manufacturing a semiconductor device according to the embodiment of the present application. FIG. 4 is a perspective view of the unit device region of the lead frame in the assembly and resin sealing step (wire bonding step) in the semiconductor device manufacturing method according to the embodiment of the present application. FIG. 5 is a perspective view of the unit device region of the lead frame in the assembly and resin sealing step (resin sealing step) in the method of manufacturing a semiconductor device according to the embodiment of the present application. FIG. 6 is a perspective view of a unit device in an assembly & resin sealing step (device separation step) in the semiconductor device manufacturing method according to the embodiment of the present application. Based on these, the outline of the assembly and resin sealing process from the completion of the wafer probe inspection which is the final step of the wafer process to the step of completing the resin sealing and separating into individual devices will be described. In the following, for convenience of illustration, only the unit device area is mainly shown.

  As shown in FIG. 1, the wafer 1 (FIG. 2) for which the wafer probe inspection has been completed is put into an assembly process 101. First, backgrinding (wafer backside grinding) 111 is performed to bring the wafer thickness to a desired thickness in the range of 300 to 5 micrometers, for example. Next, as shown in FIG. 2, the wafer 1 is divided into individual chips (semiconductor chips) 2 with the back surface fixed to the adhesive sheet, for example, by dicing or the like (dicing step 112 in FIG. 1). .

  Next, as shown in FIG. 3, for example, an adhesive or the like is placed on the die pad 14 (FIG. 11) in the almost central portion of the unit device region 3 a of the matrix-like lead frame 3 (FIG. 9 or 10). The chip 2 obtained by the dicing process is die bonded (die bonding process 113 in FIG. 1). Here, the chip 2 is mounted on the die pad 14 so that the back surface of the chip 2 (surface opposite to the device surface) faces the die pad 14. The die pad 14 is smaller than the semiconductor chip 2 in plan view, and the corner portions 4a, 4b, 4c of the outer frame portion 4 of the lead frame 3 are formed by four die pad support bars 8 (8a, 8b, 8c, 8d). , 4d. A plurality of leads are arranged between the die pad support bars 8a, 8b, 8c, and 8d, and are connected to the outer frame corner portions 4a, 4b, 4c, and 4d at both ends by a linear dam bar portion 7. Yes. Each lead is roughly divided into an inner lead portion 5 and an outer lead portion 6 with the dam bar portion 7 as a boundary (however, after the dam cut, a portion of the inner lead portion 5 in the vicinity of the dam bar portion 7 is substantially It becomes a part of the outer lead portion 6). Adjacent to each die pad support bar 8a, 8b, 8c, 8d, there is an end inner lead portion (adjacent inner lead portion) 5b, and there are a number of general inner lead portions 5a in the other portions. The end inner lead portion 5b and the general inner lead portion 5a are collectively referred to as the inner lead portion 5. As the inner lead material, a copper-based alloy containing copper as a main component is usually used. Specific examples of the copper-based alloy include a Cu-Fe-based alloy, a Cu-Cr-Sn-Zn-based alloy, and a Cu-Zr-based alloy. In this example, for example, a Cu-Fe alloy (iron: 2.1 to 2.6% by weight, zinc: 0.05 to 0.2% by weight, phosphorus: 0.015 to 0.15% by weight, copper: 97% by weight or more) can be exemplified as a preferable one. Next, as shown in FIG. 4, bonding pads (for example, aluminum-based) on the device surface (main surface) of the semiconductor chip 2 and inner ends of the inner lead portions 5 are connected with, for example, a gold-based bonding wire 9. Wire bonding is performed (wire bonding step 114 in FIG. 1). Here, the assembly process 101 is completed, and the lead frame 3 (lead frame & chip composite) is put into the resin sealing process 102.

  As shown in FIG. 5, the resin sealing step 115 (FIG. 1) is executed by the molding apparatus 51 (FIG. 7) (sealing temperature is about 170 to 190 degrees Celsius), and the resin sealing body 11 is formed. Is done. The resin sealing body 11 has a substantially flat upper surface 11u (the lower surface is substantially the same), four peripheral tapered surfaces 11t (the lower half is also substantially the same), and a corner surface 11c (the lower half is also the same). Yes. Here, the planar shape of the resin sealing body 11 is a rectangular shape, and specifically, a rectangular shape with a corner portion chamfered. The die pad support bar 8a is formed from the center of the resin sealing body 11 toward the corner portion, and penetrates substantially the center portion of the package corner surface formed by the upper half corner surface 11c and the lower half portion. doing.

  After the resin sealing step 115, a separation process is performed between the runner resin 78r and the gate resin 87r (see FIG. 18) by the gate break step 116 shown in FIG. & Chip composite) is taken out of the molding apparatus 51 (in FIG. 5, the sealing member peripheral resin member such as the gate resin 87r is not shown to avoid complexity). Subsequently, a curing bake 122 (about 170 to 190 degrees Celsius for several hours) is performed to make the resin a final curing completion stage, and the resin sealing step 102 is completed. The lead frame 3 (lead frame & chip composite) that has completed the resin sealing step 102 is put into the cutting and forming step 103.

  In the cutting and forming process 103, as shown in FIG. 1, first, a gate for removing a sealing body peripheral resin member such as the gate resin 87r of each outer frame corner portion 4a, 4b, 4c, 4d of the lead frame 3 A cutting step 117 is performed. The gate cutting step 117 is executed, for example, by cutting off the cut-off portions 12a, 12b, 12c, and 12d shown in FIGS. 11 to 14 from the upper side to the lower side (from the upper surface to the lower surface of the lead frame).

  Next, as shown in FIG. 1, the dam cutting step 118 is executed, and almost all of the unnecessary dam bar portion other than the portion shared with the lead between the leads (the dam cutting portion 19 is illustrated in FIG. 14) is cut. Removed. The dam cutting step 118 is executed by cutting, for example, from the top to the bottom (from the top surface to the bottom surface of the lead frame) with a cutting die. Subsequently, a lead plating process 119 is performed as a surface treatment of the outer lead portion 6. Usually, solder plating is performed. Examples of the lead-free solder material include Sn-Bi, Sn-Cu, or Sn-Ag tin-based solder.

  Subsequently, when necessary, as shown in FIG. 6, the lead forming step 120 and the device separation step 121 are usually executed almost continuously. Here, the main dimension of the resin sealing body 11 of this example is illustrated. If the thickness is less than 1.5 millimeters, for example, about 1.4 millimeters, about 1 millimeter, etc., and the planar shape is substantially square, one side is about 10 to 18 millimeters, and the lead pitch is It is about 0.8 to 0.2 millimeters. The number of pins is mainly about 200 to 600 pins.

  This example is QFP (Quad Flat Package). However, by using a molding apparatus in which a cavity is formed only in one of the lower mold and the upper mold, the resin sealing body 11 is formed only on one side of the lead frame 3, and the lower surface of the resin sealing body 11 is formed. The present invention can also be applied to a rectangular package (including a package having a square planar shape) such as a QFN (Quad Flat Non-Leaded Package) in which the outer lead portion is exposed from the (mounting surface). Furthermore, as another form, the present invention can be applied almost as it is to a package in which the die pad support bar 8a is formed toward the corner portion of the resin sealing body and the inner lead portion 5 is disposed next to the die pad support bar 8a. it can.

2. Outline description of a mold, a resin tablet, and a resin sealing device used in the resin sealing step in the method of manufacturing a semiconductor device according to the embodiment of the present application (mainly FIGS. 7 to 10).
In this section, an outline of a mold and a resin sealing device used in the molding step 115 of FIG.

  FIG. 7 is a schematic front sectional view (in a state where the mold is opened) showing the structure and operation of the upper and lower molds used in the resin sealing step which is the main part of the method of manufacturing a semiconductor device according to one embodiment of the present application. . FIG. 8 is a schematic cross-sectional view showing the structure and function of the upper and lower molds used in the resin sealing step, which is the main part of the method for manufacturing a semiconductor device according to one embodiment of the present application. FIG. 8 shows a state where the mold is closed, the transfer and filling of the sealing resin 50 are completed, and the pressure is being applied. FIG. 9 is a top view of a mold for explaining the structure of a lower mold used in a resin sealing process, which is a main part of the method for manufacturing a semiconductor device according to an embodiment of the present application (a matrix-shaped lead frame is used as a reference). (Illustrated). FIG. 10 is a bottom view of a mold for explaining the structure of an upper mold used in a resin sealing process, which is a main part of a method for manufacturing a semiconductor device according to an embodiment of the present application (a matrix-shaped lead frame is used as a reference). (Illustrated).

  As shown in FIGS. 7 to 10, the sealing portion of the molding device 51 (resin sealing device) includes a lower mold 52 and an upper mold 53 (generically referring to a lower mold 52 and an upper mold 53 arranged above and below each other). Etc.) and so on. This mold is set in a press mechanism which is a main part of the molding apparatus 51. The lower mold 52 and the upper mold 53 (the mold main body portion excluding the main body portion, the gate insert piece and the coating portion) are made of die steel having a Vickers hardness of about 700, for example.

  As shown in FIGS. 7 to 10 (mainly FIG. 7), a lower plate 52 is provided with a contact plate 54 for transmitting the force from the press mechanism. On the upper surface of the abutting plate 54, a stopper 64 for storing the ejector pin 76, an ejector pin drive spring 68, a support pillar 66 for holding the cavity holder 62, and a lower backing push-up for pushing up the lower backing plate 58 are pushed up. The lower rod backing push-up hole 124 through which the lower rod 123 and the lower die backing push-up rod 123 pass is installed. The abutting plate 54 is provided with an ejector pin holder 56 held by an ejector pin drive spring 68, and an ejector pin 76 and a return pin 72 are fixed to a backing plate 58 thereon. The return pin 72 acts so that the ejector pin 76 is taken into the mold when the mold is closed. A protruding ejector pin stopper 92 is provided on the backing plate 58 and regulates the protruding amount of the ejector pin 76. On the support pillar 66, a cavity holder 62 is provided, and a gate block 61a (61), that is, a cavity block 88 in which the gate insert piece 40a (40) is set in the inflow gate portion is installed. A cavity 85a (85), a resin reservoir 87a (87), a runner portion 78, and the like are formed on the upper surface of the chase block 80 (FIG. 7) including the cavity block 88, the cavity holder 62, and the like. A guide wedge 74 used for alignment of the upper and lower molds is provided at the upper end of the cavity holder 62. The pot block 82 of the lower mold 52 is provided with a pot portion 84, and the resin tablet charged therein is heated and transferred by the plunger 86 and the plunger driving pin 70 in a heated state. Examples of the composition of the resin tablet by weight% include, for example, about 10 to 30% of a resin basic component composed of an epoxy resin, a phenol novolac curing agent, a phosphorus or amine catalyst, and a filler such as fused silica powder. It is about 70 to 90%. Furthermore, a flexible material such as silicone is about a few percent, a trace amount of an interfacial control component consisting of a coupling agent such as an epoxy silane compound, an internal mold release agent such as an ester compound, and a small amount of a colorant such as carbon black. is there.

  On the other hand, an upper plate 53 is provided with a contact plate 55 for transmitting the force from the press mechanism, and a stopper 65 for accommodating the cavity ejector pins 77 is provided on the lower surface of the contact plate 55. In addition, an ejector pin driving spring 69, a support pillar 67 for holding the cavity holder 63, and the like are installed. The abutting plate 55 is provided with an ejector pin holder 57 held by an ejector pin drive spring 69, and a cavity ejector pin 77, a cal ejector pin 79 and a return pin 73 are fixed to a backing plate 59 below this. Yes. The return pin 73 acts so that when the mold is closed, the ejector pin 77 and the cal ejector pin 79 are taken into the mold. A protruding ejector pin stopper 93 is provided under the backing plate 59 to regulate the protruding amount of the ejector pin 77 and the cal ejector pin 79. A cavity holder 63 is provided under the support pillar 67, and a gate block 61b (61), that is, a cavity block 89 in which the gate insert piece 40b (40) is set in the inflow gate portion is installed. . A cavity 85b (85), a resin reservoir 87b (87), a cull portion 83, and the like are formed on the lower surface of the chase block including the cavity block 89, the cavity holder 63, the cull block 81, and the like. A guide wedge 75 that engages with the guide wedge 74 and aligns the upper and lower molds is provided at the lower end of the cavity holder 63.

  As shown in FIG. 9, for example, in the case of a matrix-like lead frame 3, when performing the sealing, the two lead frames 3 are placed in the lower cavity 85a corresponding to each unit device region 3a. Set on the lower cavity block 88 to be aligned. When the positions of the two lead frames 3 are projected onto the lower surface of the upper cavity block 89, the result is as shown in FIG.

  1 is actually executed, the lead frame 3 is set as shown in FIGS. 9 and 19 (or FIG. 21) with the mold opened as shown in FIG. In the state where the resin tablet is put into 84, the mold is closed as shown in FIG. 8 and the mold clamping force (for example, about 80 tons) is applied, and after the resin tablet melting time (for example, about 10 seconds) elapses, Begin resin infusion. The resin injection pressure can be exemplified by a suitable range of about 9.8 MPa to 19.6 MPa, for example, centering on about 12.7 MPa. When the molding process is executed, the portions that touch the sealing resin 50 such as the cavity blocks 88 and 89 are heated to about 175 degrees Celsius. Filling is completed in about 10 seconds from the start of resin injection, for example. Thereafter, in a state where the mold is clamped, for example, in a state where a filling pressure similar to the previous resin injection pressure is applied, a curing process (curing in the mold) is performed for about 100 seconds, for example. Thereafter, when the mold is opened, the ejector pins 76, 77, and 78 are automatically actuated to perform mold release. This series of cycle times is, for example, about 120 seconds.

3. Outline description of lead frame used in assembly & resin sealing step in manufacturing method of semiconductor device of one embodiment of the present application (mainly FIG. 11 to FIG. 13)
In this section, the relationship between the lead frame used in the assembly and resin sealing process described in sections 1 and 2 and the surroundings will be further described. Here, a copper-based lead frame (lead frame thickness is, for example, about 0.125 millimeters) whose main component is copper will be specifically described.

  It should be noted that the planar shape and the like of the lead frame described here are merely examples, and it is needless to say that various modifications can be made depending on the type as necessary.

  FIG. 11 is a top view (for explaining each part of the lead frame) of the lead frame (bonding wires and the like are omitted) in the resin sealing step, which is the main part of the method of manufacturing a semiconductor device according to the embodiment of the present application. FIG. 12 is a top view of a lead frame (bonding wires and the like are omitted) in a resin sealing process, which is a main part of the method of manufacturing a semiconductor device according to an embodiment of the present application (for explaining the relationship between each part of the lead frame and the mold). It is. FIG. 13 is an enlarged transparent top view (displayed so that the structure of the lower cavity block can be seen) of the lower left quarter of the unit region of the lead frame (lead frame & chip composite) of FIG.

  The structure and the like of the unit device area 3a of the lead frame 3 will be described with reference to FIGS. As shown in FIG. 11, there is a die pad 14 at the center, and the semiconductor wafer 2 is fixed thereon, and the die pad 14 is unitized by four die pad support bars 8 (8a, 8b, 8c, 8d). It is connected to the outer frame corner portions 4a, 4b, 4c and 4d of the device region 3a. There is an offset bent portion 16 in the middle portion of each die pad support bar 8a, 8b, 8c, 8d, and the inner side (offset region 15) is slightly lower than the outside. This is to ensure the resin thickness necessary for wire bonding. Between the adjacent die pad support bars 8a, 8b, 8c, and 8d, a large number of leads composed of the inner lead portion 5 and the outer lead portion 6 are arranged densely. The outer frame corner portions 4a, 4b, 4c and 4d at both ends are connected and held. Each inner end of the inner lead portion 5 is a free end, but the outer end of the outer lead portion 6 is usually connected to the outer frame portion 4. A portion where the resin sealing body 11 is formed is indicated by a broken line in the drawing as a square with a corner dropped or a rectangle close to a square. Further, in the outer frame corner portions 4a, 4b, 4c, and 4d, regions 12a, 12b, 12c, and 12d cut out in the gate cutting step 117 described with reference to FIG. The outer frame corner portion 4a is provided with a resin reservoir opening 17, and a die pad support bar 8a extends substantially linearly toward that portion. On the other hand, in the other outer frame corner portions 4b, 4c, 4d, the die pad support bars 8b, 8c, 8d exhibit a Y-shaped branch 18.

  Next, FIG. 12 will be described. This figure is essentially the same as FIG. 11, but focuses on clarifying the relationship between the resin sealing body 11 and the sealing body peripheral resin member described with reference to FIGS. That is, in the outer frame corner portion 4a, when the resin filling is completed, a runner portion resin 78r is formed corresponding to the mold runner portion 78, and the gate resin corresponding to the resin reservoir 87 and the gate channel 60 is formed. 87r is formed. On the other hand, in the other outer frame corner portions 4b, 4c, 4d, an air vent resin (relatively thin) is formed corresponding to the air vents 45b, 45c, 45d. Usually, the thickness of the air vent portions 45b, 45c, 45d is about 10 to 40 micrometers.

  FIG. 13 is an enlarged view of 1/4 of the unit device region 3a that basically includes the outer frame corner portion 4a of FIG. 11 or FIG. This figure mainly shows the relationship between the lead frame 3 and the upper surface of the lower mold, the outer end portion of the end inner lead portion (adjacent inner lead portion) 5b and the gate portion 61 (inflow gate). It is for showing the relationship with the gate insert piece 40a (40) set in the part 61a). As shown in FIG. 13, there is a wide cavity 85 on the upper right, and a dam bar clamp surface 71 is provided on the left and lower periphery. The surface pressure escape retreating portion 42 is retreated, for example, about 100 to 200 micrometers from the dam bar clamp surface 71.

  The gate section 61 (inflow gate section 61a) and its periphery will be described in more detail in the next section.

4). Detailed description of lead frame and mold die (around gate part) used in assembly & resin sealing step in manufacturing method of semiconductor device of one embodiment of the present application (mainly FIGS. 14 to 20)
The planar and three-dimensional shapes and the like of the lead frame and the mold described here are merely examples, and it goes without saying that various modifications can be made as necessary or depending on the type.

  In the following, if there is the same thing in the upper and lower sides, in principle, only one will be explained, but the matter to be explained is clearly stated that it is not, and it is clear that it is not so It goes without saying that the same applies to the other.

  FIG. 14 is a partially enlarged transparent top view of the inflow gate portion of FIG. 13 (for explaining the contact portion with the lead frame). FIG. 15 is a partially enlarged transparent top view of the inflow gate portion of FIG. 13 (for explaining the lead clamp surface). 16 is a perspective view of the lower mold viewed from the direction of the arrow VP in FIG. 14 (the height direction is the arrow VP in FIG. 19) (the lead frame is not shown for easy viewing). FIG. 17 is an enlarged perspective view of the gate insert piece 40 (40a) of FIG. 16 and its surroundings. 18 is a sectional view of the periphery of the gate portion of FIG. 8 corresponding to the A-A ′ section of FIGS. 13 to 15. FIG. 19 is a sectional view of the periphery of the gate portion of FIG. 7 (when a lead frame is placed) corresponding to the P-P ′ section of FIGS. 14 and 15. 20 is a cross-sectional view of the periphery of the gate portion of FIG. 8 (the sealing resin is not shown for the sake of clarity) corresponding to the P-P ′ cross section of FIGS. 14 and 15. Based on these, the details of the lead frame and mold die (around the gate portion) used in the assembly and resin sealing step in the method of manufacturing a semiconductor device according to one embodiment of the present application will be described.

  As shown in FIG. 15, there is a gate channel 60 at the center of the gate insert piece 40 (40a), and there are lead clamp surfaces 41 (FIG. 16 or FIG. 17) with hatching on both sides. FIG. 14 shows a portion 43 where the lead clamp surface 41 presses the inner lead portion of the lead frame 3 with hatching. As shown in FIG. 14, the width WG (on the cavity side) of the gate channel 60 is set to be narrower than the width WP of the corner portion 11c of the resin sealing body. For example, when the width WP of the corner portion 11c is about 800 micrometers, the width WG (on the cavity side) of the gate channel 60 is preferably about 300 to 700 micrometers. An example of the depth (on the cavity side) of the gate channel 60 is about 100 to 400 micrometers.

  Next, the points described with reference to FIGS. 14 and 15 will be further described with reference to the perspective views shown in FIGS. As shown in FIG. 16 and FIG. 17, when the lower gate insert piece 40a is taken as an example, the lead clamp surface 41 of the gate insert piece 40 as a whole is positioned slightly higher when the dam bar clamp surface 71 is used as a reference surface. Yes (ie protruding). The cavity side inner surface 40c of the gate insert piece 40 (40a) constitutes the inner surface of the cavity 85 as it is.

  Next, a mold cross-sectional structure around the gate portion 61 (inflow gate portion 61a) will be described with reference to FIGS. FIG. 18 is a vertical cross section (at the time of resin filling completion) that cuts through the center of the gate channel 60 and the runner portion 78 shown in FIG. In this example, the lower gate insert piece 40a and the upper gate insert piece 40b are set in both the lower cavity block 88 and the upper cavity block 89, respectively. The main body portions 40w of the lower gate insert piece 40a and the upper gate insert piece 40b are made of a cemented carbide material such as a tungsten carbide-cobalt based sintered body (specifically, a WC-Co cemented carbide material). In this example, the entire surface is covered with a surface coat member film 44 of a hard chrome plating film (thickness, for example, about 2 to 5 micrometers) or the like. The Vickers hardness of the hard chrome plating film is, for example, about 800 to 1000. Moreover, as a particle size of the tungsten carbide-cobalt based sintered body, for example, about 1.5 to 2.5 millimeters (belonging to so-called “medium particle cemented carbide”) can be exemplified as a suitable one. Tungsten carbide-based sintered bodies are frequently used as superhard materials, have high wear resistance, and are easily available. In particular, the tungsten carbide-cobalt-based sintered body is a typical form thereof and is effective as a base material for a gate insert piece. The chromium member film has a relatively high hardness and has an advantage that a stable coating can be easily formed. In particular, the hard chrome plating film is widely used in the mold field, and the gate insert piece can be easily coated.

  Note that even if “the entire surface” is mentioned, it is allowed that there is a portion that is not formed for reasons of electrolytic plating. The package thickness T is, for example, about 1 millimeter.

  FIG. 19 (further enlarged than FIG. 18) is a vertical cross section (after the lead frame is set and before the mold is clamped) that longitudinally cuts the lead clamp surface 41 shown in FIG. Here, the protruding length PL of the lead clamp surface 41 with the dam bar clamp surface 71 as a reference surface is, for example, about 10 to 20 micrometers.

  20 is a cross-sectional view of the same cross section as FIG. 19 before the mold clamping is completed and the resin is injected. As can be seen, the lead clamp surface 41 holds the lead frame 3 during mold clamping.

  As described above, as described above, the main feature of one embodiment of the present application is that the lower gate insert piece 40a and the upper gate insert piece 40b are made of cemented carbide such as tungsten carbide-cobalt based sintered body. The entire surface of each main body portion 40w is covered with a surface coat member film 44 made of a hard chrome plating film or the like. With this structure, when the copper-based lead frame 3 is clamped by the lower mold 52 and the upper mold 53, the surface of the main body portion 40w of each of the lower gate insert piece 40a and the upper gate insert piece 40b. Does not come into contact with the copper-based lead frame 3, and the surface coat member film 44 comes into contact with the copper-based lead frame 3, so that the copper ions of the copper-based lead frame are cobalt which is the binder part of the sintered body. It will not spread to any part. As a result, the binder part of the sintered body becomes brittle and can solve the problem of peeling during cleaning or the like.

5. Detailed description of the structure and materials of the gate insert piece used in the resin sealing step in the method of manufacturing a semiconductor device according to the embodiment of the present application (mainly FIGS. 21 to 24)
The gate insert piece usually has a taper that becomes narrower in the direction of insertion for convenience of insertion or the like. However, in the following example, the taper is not shown for convenience of illustration.

  FIG. 21 is a gate insert piece main body of FIGS. 18 to 20 for explaining details of the structure and material of the gate insert piece used in the resin sealing step in the method of manufacturing a semiconductor device according to the embodiment of the present application. It is a fine structure figure of a part. FIG. 22 is a schematic enlarged sectional view of T-T ′ of the gate insert piece and the lead frame of FIG. 14 (other portions are not shown for the sake of clarity. The same applies hereinafter). FIG. 23 is a schematic enlarged cross-sectional view corresponding to FIG. 22 showing a state where the surface coat member film of the gate channel is removed as a result of using the gate insert piece of FIG. FIG. 24 is a schematic enlarged cross-sectional view corresponding to FIG. 22 showing an example in which the surface coat member film is not formed on a part of the surface of the gate insert piece for reasons of the method of forming the surface coat member film. Based on these, the details of the structure and material of the gate insert piece used in the resin sealing step in the method of manufacturing a semiconductor device according to the embodiment of the present application will be described.

(1) Detailed description of gate insert piece structure and materials (basic structure by plating or the like) (mainly FIGS. 21 and 22):
The fine structure of the gate insert piece main body portion 40w is as shown in FIG. 21 when a tungsten carbide-cobalt-based sintered body (super hard material) is taken as an example (specifically, a WC-Co super hard material). . As shown in FIG. 21, tungsten carbide particles W as a main material are dispersed in a cobalt phase C as a binder. In other words, the gap between the tungsten carbide grain boundaries W is filled with the cobalt phase C. Note that the Vickers hardness of the tungsten carbide-cobalt-based sintered body (superhard material) is, for example, about 1500.

  Next, FIG. 22 shows a cross section orthogonal to the gate channel 60 (FIG. 17) of the gate insert piece 40 of FIG. 20 (here, the lower gate insert piece 40 a as an example). As shown in FIG. 22, a surface coat member film 44 is formed on the entire surface of the gate insert piece 40 (40a). Therefore, a surface coat member film 44 having a property of preventing the diffusion of copper is formed at least on the portion of the lead clamp surface 41 that contacts the copper-based lead frame 3 when it is clamped. Become.

  In such a case, the surface coat member film 44 is formed on the entire main surface 48 (the upper surface of the lower gate insert piece 40a, the lower surface of the upper gate insert piece 40b) of the gate insert piece 40 (40a, 40b). Will be.

  In such a structure, the surface coat member film 44 is formed on the entire surface of the gate insert piece 40 (40a, 40b) (including the case where there is a portion that is not formed in a relatively small area portion). Therefore, it has the merit that it is easy to manufacture. In particular, it is particularly advantageous when formed by a plating method.

(2) Explanation of structural change due to use of the gate insert piece of the basic structure (mainly FIG. 23):
What is shown in FIG. 23 can be considered to indicate a point in time that changes due to the use of the cross-sectional structure of the gate insert piece (40a) shown in FIG. That is, as shown in FIG. 23, as a result of the surface coating member film 44 in the gate channel 60 being removed by the sealing resin flow, all or part of the surface coating member film 44 in the gate channel 60 disappears. It is a thing. Even in such a structure, at least a portion of the lead clamp surface 41 that contacts the copper-based lead frame 3 when the copper-based lead frame 3 is clamped is a surface coat member film 44 that has a property of preventing copper diffusion. Can be used in the same manner as in FIG. This is because the gate insert piece main body portion 40w originally has higher wear resistance to the sealing resin than the surface coat member film 44 (for example, tungsten carbide-cobalt based sintered body). This is because such a case is preferable as a piece.

  Further, such a structure is formed by forming the surface coat member film 44 only on the portion shown in FIG. 23 from the beginning. Further, as shown in FIG. 22, the surface coat member film 44 may be formed on the entire surface, and then the surface coat member film 44 in the gate channel 60 may be removed. In any of these cases, the surface coat member film 44 is formed on at least the entire surface of the lead clamp surface 41. Of course, at least a portion of the lead clamp surface 41 that is in contact with the copper-based lead frame 3 when it is clamped is formed with a surface coat member film 44 having a property of preventing copper diffusion. Become.

(3) Modification example (mainly FIG. 24) due to reasons for manufacturing the gate insert piece having the above basic structure:
Even when the surface coat member film 44 as shown in FIG. 22 is to be formed, the back surface of the gate insert piece 40 (40a), etc., as shown in FIG. The coat member film 44 may not be formed. In addition to electrolytic plating, generally, PVD (Physical Vapor Deposition) having directivity, ie, sputtering film formation, ion plating, thermal spraying, plasma spraying (Thermal Plasma Spraying), etc. It is easy to become a typical film formation. Moreover, such a structure can also be formed intentionally. Similarly to the above, in any of these cases, the surface coat member film 44 is formed on at least the entire surface of the lead clamp surface 41. Of course, at least a portion of the lead clamp surface 41 that is in contact with the copper-based lead frame 3 when it is clamped is formed with a surface coat member film 44 having a property of preventing copper diffusion. Become.

  When the surface coat member film non-formation portion has a relatively small area (for example, less than about 20% of the whole), the surface coat member film is formed on the entire surface of the gate insert piece 40 (40a). It can be said that.

6). Description of various modifications related to the structure and material of the gate insert piece used in the resin sealing step in the method of manufacturing a semiconductor device according to the embodiment of the present application (mainly FIGS. 25 to 28)
In this section, various modifications relating to the structure and material of the gate insert piece described in FIGS. 19, 20 and 22 to 24 will be described.

  FIG. 25 corresponds to FIG. 20 for explaining Modification 1 (local coating) relating to the structure and material of the gate insert piece used in the resin sealing step in the method of manufacturing a semiconductor device according to the one embodiment of the present application. It is a gate part periphery sectional drawing. 26 corresponds to FIG. 22 and is a schematic enlarged cross-sectional view showing a cross section (T-T ′ cross section of FIG. 14) of the gate insert piece of FIG. 25. FIG. 27 is a view for explaining a modification 2 (clamp surface entire surface coating) regarding the structure and material of the gate insert piece used in the resin sealing step in the method of manufacturing a semiconductor device according to the one embodiment of the present application. It is a corresponding gate part periphery sectional drawing. FIG. 28 corresponds to FIG. 22 for explaining Modification 3 (upper surface full surface coating) relating to the structure and material of the gate insert piece used in the resin sealing step in the method of manufacturing a semiconductor device according to one embodiment of the present application. FIG. Based on these, various modifications relating to the structure and material of the gate insert piece used in the resin sealing step in the method of manufacturing a semiconductor device according to the one embodiment of the present application will be described.

(1) Description of Modification Example 1 (Local Coat) on the gate insert piece coating structure (mainly FIGS. 25 and 26):
When the lead frame 3 is clamped, the portion of the gate insert piece 40 (40a, 40b) in contact with the lead frame 3 basically appears only on the lead clamp surface 41. Therefore, as shown in FIGS. 18 to 20, 22 and the like, the surface coat member film 44 is not necessarily formed on the entire surface of the gate insert piece 40 (40a, 40b). Accordingly, as shown in FIGS. 25 and 26, when the lead frame 3 is actually clamped in the lead clamp surface 41, the surface coat member film 44 is formed only on the portion in contact with the lead frame 3. You may make it do. In such a case, a surface coat member film 44 having a property of preventing the diffusion of copper is formed at least on the portion of the lead clamp surface 41 that contacts the copper-based lead frame 3 when it is clamped. Will be.

(2) Description of Modification 2 (Clamp Surface Entire Surface Coat) Regarding Gate Insert Piece Coat Structure (Mainly FIG. 27):
The example of FIG. 26 is effective, but it is based on the premise that the shape of the lead frame 3 in the part that interferes with the gate insert piece 40 (40a, 40b) does not change. However, in general, the shape of the lead frame 3 in the portion that interferes with the gate insert piece 40 (40a, 40b) usually varies depending on the type, so that the surface coating member is provided on the entire surface of the lead clamp surface 41 as shown in FIG. It is effective to form the film 44. In such a structure, it can be said that the surface coat member film 44 is formed at least on the entire surface of the lead clamp surface 41. Of course, at least a portion of the lead clamp surface 41 that is in contact with the copper-based lead frame 3 when it is clamped is formed with a surface coat member film 44 having a property of preventing copper diffusion. Become. Therefore, with such a structure, even if the planar structure of the lead frame 3 is changed, the same gate insert piece 40 (40a, 40b) can be used.

  Similarly to the above, the structure as shown in FIG. 27 may be formed intentionally or over time through the structure as shown in FIG. 28.

(3) Description of modification 3 (upper surface entire surface coating) relating to the gate insert piece coating structure (mainly FIG. 28):
In the structure as shown in FIG. 27, in consideration of the film formation method of the surface coat member film 44, rather, as shown in FIG. 28, the surface coat member is entirely formed on the main surface 48 of the gate insert piece 40 (40a, 40b). The film 44 may be formed. Even in such a structure, it can be said that the surface coat member film 44 is formed at least on the entire surface of the lead clamp surface 41. Of course, at least a portion of the lead clamp surface 41 that is in contact with the copper-based lead frame 3 when it is clamped is formed with a surface coat member film 44 having a property of preventing copper diffusion. Become.

  Such a structure is advantageous in ensuring the accuracy of the gate insert piece 40 as a component because no coating is provided around the gate insert piece 40. Further, there is an advantage that the surface coat member film 44 can be easily formed by PVD such as spraying.

7). Supplementary explanation about the above-described embodiment (including modifications) and general considerations etc. (refer mainly to FIG. 29, FIG. 30, FIG. 1, etc.)
FIG. 29 is a mold sectional view schematically illustrating a mold cleaning process related to a resin sealing process in the method of manufacturing a semiconductor device according to the embodiment of the present application. FIG. 30 is a schematic cross-sectional view of the main part of the mold showing the outline of the embodiment. Based on these, supplementary explanations and considerations common to each section will be given.

  In addition, it cannot be overemphasized that the following description makes a part of said one Embodiment (a modification is included).

(1) Background of interference between gate insert piece and copper lead frame:
As described above, the embodiment is directed to a method for manufacturing a semiconductor device using a resin sealing technique. Usually, the cavity blocks 88 and 89 (FIG. 7 or FIG. 8) for semiconductors and the peripheral mold main parts (that is, the lower mold and the upper mold) are made of steel for molding molds. As a specific material, for example, die steel can be exemplified. This is because the die steel is relatively hard, has good workability, and is well balanced in terms of cost (in addition, other steel materials may be used as necessary). The components of the die steel are exemplified by weight%. For example, carbon is about 1.3%, chromium is about 4.2%, tungsten is about 6%, molybdenum is about 5%, vanadium is about 3%, cobalt is about 8%, and the rest is iron. It is. The linear expansion coefficient is 12.3 × 10 ⁻⁶ / ° C. In many cases, the surface of the mold body (for example, the cavity inner surface, the dam bar clamp surface, etc.) is subjected to chrome plating (for example, hard chrome plating) or the like.

As described above, the cavity blocks 88 and 89 (molds 52 and 53) are made of a relatively hard steel material, but the gate portion 61 (the inflow gate portion 61a and the outflow gate portion 61b) has a hard filling. Since the sealing resin 50 containing the gas passes through the thin gate channel 60 at a high speed, the wear becomes relatively intense. As the size of the gate portion increases over time, the portion of the gate resin 87r close to the resin sealing body 11 is enlarged, and the resin sealing body 11 (package body) is damaged in the gate cut 117 (FIG. 1). Is likely to occur. Therefore, as described above, a cemented carbide is used for the gate insert piece 40. As a specific material, for example, when an example of a component of the tungsten-based cemented carbide is expressed by weight%, it is about 85% tungsten, about 10% cobalt, and about 5% carbon. This linear expansion coefficient is 5.39 × 10 ⁻⁶ / ° C. Thus, the linear expansion coefficient of the gate insert piece 40 is approximately about half that of the steel material for mold metal, and has a value of 30% to 70% as a range.

  The large difference between the two linear expansion coefficients makes it difficult to adjust the height of the dam bar clamp surface 71 (FIG. 16) and the lead clamp surface 41 of the gate insert piece 40 in a molding process performed by heating around 175 degrees Celsius. To. In order to avoid this, if the gate insert piece 40 is made smaller, the lead clamp surface 41 is in a retracted position, which causes a serious result of resin leakage. If it is made larger to avoid this resin leakage, the gate insert piece 40 will now protrude beyond the dam bar clamp surface 71, and the clamping force will concentrate on that portion. As a result, in the portion where the gate insert piece 40 and the lead frame 3 are geometrically interfered with each other, various reactions and undesired physicochemical processes proceed.

(2) Supplementary explanation on mold cleaning (refer mainly to FIGS. 29 and 1):
In each of the above embodiments, a dehalogenated sealing resin is mainly used. However, in a sealing process using a dehalogenated sealing resin as compared with a halogen-containing sealing resin, mold contamination is caused. Becomes intense. On the other hand, a cleaning resin sheet 49 is generally used as shown in FIG. 29 in order to increase the efficiency of mold cleaning performed intermittently during the repetition of the molding process. That is, as shown in FIG. 29 and FIG. 1 (mold cleaning step 131), the lower mold 52 and the upper mold 53 (the mold temperature is the same as that of resin sealing, for example, about 160 to 180 degrees Celsius. ), For example, an elastomer-based cleaning resin sheet 49 (cleaning resin sheet) is interposed therebetween, and the lower mold 52 and the upper mold 53wp are closed and compressed, that is, clamped. During this time, vulcanization of the elastomer-based cleaning resin sheet 49 (rubber-based cleaning sheet) proceeds and the contaminants and the rubber component are integrated. Thereafter, the lower mold 52 and the upper mold 53 wp are opened, and the elastomer-based cleaning resin sheet 49 is peeled off to perform mold cleaning. Here, as the elastomer-based cleaning resin sheet 49, for example, a material obtained by adding a removal aid or the like to unvulcanized rubber can be exemplified as a suitable one. As unvulcanized rubber, natural rubber, chloroprene rubber, butadiene rubber, nitrile rubber, silicone rubber, fluorine rubber, butyl rubber, polyisoprene rubber, styrene butadiene rubber, etc. are used alone or as a main component, and a vulcanizing agent is further added. What was added can be illustrated as a suitable thing. As the removal aid, glycol ethers, imidazoles and the like can be exemplified as suitable ones.

  As a mold cleaning method, other methods may be adopted, or a cleaning sheet other than the elastomer type may be used by the method shown here.

(3) Description of outline of the embodiment (mainly FIG. 30):
Although the cleaning method for compressing the elastomeric sheet as described in subsection (2) is effective in terms of residue removal by repeating the molding process, the damage to the mold and other auxiliary parts is relatively low. It tends to increase. For example, taking a gate insert made of a tungsten carbide-cobalt-based sintered body as an example, the copper ions of the copper-based lead frame are in contact with the copper-based lead frame (for example, copper lead frame) and the gate insert. However, since it diffuses into the cobalt part which is the binder part of the sintered body, there is a problem that the binder part becomes brittle and peels off during cleaning or the like.

  In order to solve such a problem, the transfer molding process of the resin-encapsulated semiconductor device using the copper-based lead frame 3 is executed with the configuration shown in FIG. . That is, the copper lead frame 3 on which the semiconductor chip 2 is mounted between the lower mold 52 and the upper mold 53 is clamped so that the semiconductor chip 2 is located at a position corresponding to the mold cavity 85. The sealing resin 50 is transferred and filled. Under the present circumstances, the gate insert piece 40 comprised by the super hard material etc. is installed in the gate part through which the high-speed flow of the sealing resin 50 passes. A surface coat member film 44 having a property of preventing copper diffusion is formed on at least a portion of the lead clamp surface 41 of the gate insert piece 40 that is in contact with the copper-based lead frame 3 during clamping. Yes. That is, conventionally, in order to effectively use the hardness of the gate insert piece, it has been considered out of the question to apply a coating generally considered to be “softer” than that. However, since the resin flow does not flow on the clamp surface of the gate insert piece from the beginning, this part is softer than the base material in order to satisfy other requirements. (Low) in general, it seems that there is no problem overall.

  By adopting such a configuration, copper ions on the surface of the copper-based lead frame 3 diffuse to the surface of the surface coating member film 44, and the surface coating member film 44 is changed to a fragile structure so that mold cleaning or the like can be performed. At this time, the fragile portion is peeled off, and as a result, the lead clamp surface 41 is retracted, and it is possible to prevent the occurrence of problems such as failure of normal clamping.

(4) Supplementary explanation and consideration about the gate insert piece surface coating material and the like (see FIGS. 14 to 30):
The surface coat member film 44 of the gate insert piece 40 can be a candidate as long as it has a diffusion barrier effect on copper. That is, usually copper diffusion barrier metals such as titanium, chromium, tungsten, tantalum, titanium nitride, tantalum nitride, titanium carbonitride (TiCN), titanium aluminum nitride (TiAlN), aluminum chrome nitride (TiCrN), aluminum chrome (AlCr) or the like. Further, although not a metal, sintered diamond or the like is considered to have similar characteristics. However, in consideration of adhesion and wear resistance with a super hard material as a base material, that is, tungsten carbide (tungsten carbide), titanium, chromium, titanium nitride, titanium carbonitride (TiCN), titanium aluminum nitride ( Examples of suitable materials include TiAlN), aluminum chrome nitride (TiCrN), aluminum chrome (AlCr), and sintered diamond. Of these, titanium (titanium member film), titanium nitride, titanium carbonitride (TiCN), titanium aluminum nitride (TiAlN), aluminum chrome nitride (TiCrN), aluminum chrome (AlCr), etc. It is preferable to coat by PVD (Physical Vapor Deposition) (sputtering or other PVD may be used). This is because methods such as thermal spraying are relatively easy to form on specific parts of complex parts. Titanium (titanium member film) has advantages such as good release properties of the sealing resin.

  In addition, about chromium (chromium member film | membrane), since hard chromium plating (electrolytic plating) is used abundantly in a metal mold | die etc., formation by plating (electrochemical film-forming method) is suitable. These materials are generally considered to be relatively low in cost.

  Sintered diamond is preferably formed by sintering under high temperature and pressure. The Vickers hardness of the sintered diamond is about 5000 to 10,000. Sintered diamond is disadvantageous in terms of cost compared to metal-based materials, but is suitable in terms of characteristics.

8). Summary The invention made by the present inventor has been specifically described based on the embodiments. However, the invention of the present application is not limited thereto, and it goes without saying that various changes can be made without departing from the scope of the invention.

  For example, in the above embodiment, the case where the outer size of the die pad 14 is smaller than the outer size of the semiconductor chip 2 has been described as an example. However, the present invention is not limited thereto, and the outer size of the die pad 14 is Needless to say, the present invention can be applied to a lead frame 3 larger than the outer size of the semiconductor chip 2.

  Moreover, in the said embodiment, although the example where the gate part was provided in both the lower die and the upper die was shown, the present invention is not limited thereto, and the lower die or the upper die is not limited thereto. Needless to say, the present invention can be applied to one provided only on one side.

  Furthermore, in the above-described embodiment, one of the pair of molds is called a lower mold and the other is called an upper mold. For example, in the case of arranging in a horizontal direction, the lower mold is the first mold. The mold and the upper mold may be read as the second mold, and the arrangement of the mold and the like is not limited to the direction of gravity.

1 Semiconductor wafer 2 Semiconductor chip (chip area)
3 (Matrix-like) lead frame 3a Unit device area of matrix-like lead frame 4 Outer frame portion 4a, 4b, 4c, 4d Outer frame portion corner portion 5 Inner lead portion 5a General inner lead portion 5b End inner lead portion ( Adjacent inner lead part)
6 Outer lead part 7 Dam bar part 8, 8a, 8b, 8c, 8d Die pad support bar 9 Bonding wire 11 Resin sealing body (package main body) or its outer edge 11c Corner part (corner surface) of resin sealing body or corresponding cavity inner surface 11t Peripheral taper surface of resin sealing body 11u Upper surface of resin sealing body (or its outer edge)
12a, 12b, 12c, 12d Cut-off part 14 Die pad 15 Offset area (tab lowering area)
16 Offset bending part 17 Resin reservoir opening 18 Y-shaped branch 19 Dam cut part (example)
40 Gate insert piece 40a Lower gate insert piece 40b Upper gate insert piece 40c Cavity side inner surface of gate insert piece 40w Gate insert piece main body portion 41 Lead clamp surface 42 Surface pressure relief retreating portion (or outer edge thereof)
43 Part where lead clamp surface holds lead frame 44 Surface coat member film 45b, 45c, 45d Air vent part (or resin of air vent part)
46 Flow Cavity 46r Resin of Flow Cavity 47 47 Portion of Lead Clamp Face Opposing Retreat Part 48 Main Surface of Gate Insert Piece 49 Cleaning Resin Sheet 50 Sealing Resin 51 Molding Device 52 Lower Mold 53 Upper Mold 54 Lower Pad Plate 55 Upper pad 56 Lower ejector pin holder 57 Upper ejector pin holder 58 Lower backing plate 59 Upper backing plate 60 Gate flow path 61 (61a, 61b) Gate portion (inflow gate portion, outflow gate portion)
62 Lower cavity holder 63 Upper cavity holder 64 Lower ejector pin stopper (for storage)
65 Upper ejector pin stopper (for storage)
66 Lower support pillar 67 Upper support pillar 68 Lower ejector pin drive spring 69 Upper ejector pin drive spring 70 Plunger drive pin 71 Dam bar clamp surface 72 Lower return pin 73 Upper return pin 74 Lower guide wedge 75 Upper guide wedge 76 Lower cavity ejector pin 77 Upper cavity ejector pin 78 Runner portion 78r Runner portion resin 79 Cal ejector pin 80 Chase block 81 Cull block 82 Pot block 83 Cull portion 84 Pot portion 85 Cavity 85a Lower cavity 85b Upper cavity 86 Plunger 87 Resin reservoir 87a Lower resin reservoir 87b Upper resin reservoir 87r Gate resin 88 Lower cavity block 89 Upper cavity block 92 Lower ejector pin stock Pa (for protrusion)
93 Upper ejector pin stopper (for protrusion)
DESCRIPTION OF SYMBOLS 101 Assembly process 102 Resin sealing process 103 Cutting and forming process 111 Back grinding process 112 Dicing process (wafer dividing process)
113 Die Bonding Process 114 Wire Bonding Process 115 Resin Sealing Process 116 Gate Break Process 117 Gate Cut Process 118 Dam Cut Process 119 Lead Plating Process 120 Lead Molding Process 121 Device Separation Process 122 Cure Baking Process 123 Lower Mold Backing Rod 124 Lower Mold Backing Push-up hole 131 Mold cleaning process C Co binder part (cobalt phase)
PL Protrusion length T Package thickness W Tungsten carbide particles or grain boundaries WG Gate channel width (on the cavity side) WP Package corner surface width

Claims (12)

A semiconductor device manufacturing method including the following steps:
(A) A copper-based lead frame on which the semiconductor chip is mounted is formed by the lower mold and the upper mold so that the semiconductor chip is accommodated in a mold cavity formed between the lower mold and the upper mold. The step of clamping;
(B) After the step (a), the sealing resin is transferred into the mold cavity through the gate formed on the lower mold or the upper mold with the copper lead frame clamped. And forming a resin sealing body in which the semiconductor chip is sealed by filling the mold cavity with the sealing resin;
(C) After the step (b), the lower mold and the upper mold are opened, and the copper-based lead frame is taken out between them.
here,
(I) A gate insert piece is set in the gate portion of the lower mold or the upper mold,
(Ii) The gate insert piece is formed of a hard material harder than the lower mold or the upper mold around the gate insert piece, and includes the following:
(X1) gate flow path;
(X2) lead clamp surfaces provided on both sides of the gate channel;
(X3) A surface coat member film having a property of preventing the diffusion of copper is formed on a portion of at least the lead clamp surface that comes into contact with the copper-based lead frame when it is clamped.     2. The method of manufacturing a semiconductor device according to claim 1, wherein the surface coat member film is formed at least on the entire surface of the lead clamp surface.     2. The method of manufacturing a semiconductor device according to claim 1, wherein the surface coat member film is formed on the entire surface of the gate insert piece.     4. The method of manufacturing a semiconductor device according to claim 3, wherein the super hard material constituting the main body portion of the gate insert piece is a tungsten carbide based sintered body.     4. The method of manufacturing a semiconductor device according to claim 3, wherein the super hard material constituting the main body portion of the gate insert piece is a tungsten carbide-cobalt based sintered body.     6. The method of manufacturing a semiconductor device according to claim 5, wherein the surface coat member film is composed of a chromium member film.     6. The method of manufacturing a semiconductor device according to claim 5, wherein the surface coat member film is a hard chrome plating film.     6. The method of manufacturing a semiconductor device according to claim 5, wherein the surface coat member film is composed of a titanium member film.     9. The method of manufacturing a semiconductor device according to claim 8, wherein the surface coat member film is a titanium member film formed by thermal spraying.     6. The method of manufacturing a semiconductor device according to claim 5, wherein the surface coat member film is a sintered diamond member film. 8. The method of manufacturing a semiconductor device according to claim 7, further comprising the following steps:
(D) After the step (c), a cleaning resin sheet is sandwiched between the lower mold and the upper mold, heated and compressed, and then the cleaning resin sheet is peeled off, whereby the lower mold and Cleaning the surface of the upper mold.     8. The method of manufacturing a semiconductor device according to claim 7, wherein a main body portion of the lower mold and the upper mold is made of die steel.

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