JP4882350B2 - Manufacturing method of semiconductor device - Google Patents

Description

  The present invention relates to a method for manufacturing a semiconductor device.

In recent years, in portable electronic devices such as mobile phones, notebook personal computers, and personal data assistance (PDA), various electronic components such as semiconductor devices provided in the interior in response to demands for miniaturization and weight reduction. The size is reduced. Against this background, for example, a three-dimensional mounting technique has been proposed in which a plurality of semiconductor chips (semiconductor devices) are stacked in the thickness direction to increase the mounting density of the semiconductor chips.
In a semiconductor chip used for such three-dimensional mounting, for example, a through hole is provided in a chip substrate, and both sides of the chip substrate can be conducted by a through electrode embedded in the through hole (for example, Patent Documents). 1).

Conventionally, when a through electrode is formed on a semiconductor chip, a hole is formed from the active surface (surface on which the integrated circuit is formed) side of the semiconductor chip toward the back surface, and a conductive material is embedded in the hole. The chip substrate is thinned from the back surface side to project the conductive material on the back surface side to form a through electrode. Further, this semiconductor chip has lands connected to other semiconductor devices or the like on the active surface side.
JP 2004-207317 A

  In recent years, it has been desired to provide a semiconductor chip having a land formed on the back side. Therefore, unlike the prior art, a method is conceivable in which a hole is formed from the back side of the chip substrate and a conductive material is embedded in the hole, thereby simultaneously forming the through electrode and the land on the back side. In this method, an electrode pad is formed on a chip substrate via an insulating film, and a hole is formed from the back surface side of the chip substrate directly above the electrode pad toward the electrode pad. At this time, since the electrode pad is formed on the active surface of the chip substrate via the insulating film, it is necessary to remove the insulating film in order to make the electrode pad and the conductive material buried in the hole conductive. is there. An insulating film is formed on the inner wall surface of the hole so that the chip substrate and the conductive material are insulated.

  However, if the insulating film on the electrode pad is etched, the insulating film formed on the inner wall surface of the hole described above is also etched, and the chip substrate is exposed in the hole, thereby insulating the conductive material. Can no longer be obtained. Therefore, it is necessary to selectively etch only the insulating film covering the electrode pad without etching the insulating film covering the inner wall surface of the hole.

  The present invention has been made in view of such circumstances, and it is possible to selectively etch only the insulating film covering the electrode pad without etching the insulating film covering the inner wall surface of the hole. An object of the present invention is to provide a method for manufacturing a semiconductor device.

In the method of manufacturing a semiconductor device according to the present invention, an electrode pad is provided on an active surface side of a substrate via an insulating layer, and the insulating is formed from a back surface side opposite to the active surface formed on the substrate immediately above the electrode pad. In a method of manufacturing a semiconductor device in which a through electrode is formed by embedding a conductive material in a hole reaching a film, a step of covering an inner surface of the hole with an insulating layer, and covering the hole on the back side of the substrate In this way, a resist layer is provided, and the resist layer is heat-treated so that the thickness of the resist layer on the central portion of the hole is different from that on the central portion of the hole. The step of making it thinner than the film thickness and the thickness of the film thickness of the central part of the hole part are etched, and the opening part smaller than the opening diameter of the hole part is formed in the resist layer on the central part of the hole part And before the opening is formed Etching the insulating layer using a resist layer as a mask; etching the insulating layer; then peeling the resist layer; and embedding a conductive material in the hole to form the through electrode; In the heat treatment step, the gas in the hole is expanded to bulge the central portion of the resist layer into a dome shape, and in the etching step, the resist layer is etched into the dome shape. The opening is formed by selectively removing a portion having a smaller film thickness than other portions by being raised.
In the method of manufacturing a semiconductor device according to the present invention, an electrode pad is provided on an active surface side of a substrate via an insulating layer, and the insulating is formed from a back surface side opposite to the active surface formed on the substrate immediately above the electrode pad. In a method for manufacturing a semiconductor device in which a through electrode is formed by embedding a conductive material in a hole reaching a film, a resist layer is provided on the back side of the substrate so as to cover the hole, and the resist layer is subjected to heat treatment Forming the opening smaller than the opening diameter of the hole in the resist layer on the central part of the hole, and using the resist layer in which the opening is formed as a mask, the insulating layer And etching the insulating layer, and then peeling off the resist layer and filling the hole with a conductive material to form the through electrode. At this time, an opening smaller than the opening diameter of the hole may be formed in the resist layer by photolithography.

According to the method for manufacturing a semiconductor device of the present invention, when the resist layer provided so as to cover the hole is heat-treated, the gas in the hole expands, and the resist layer covering the hole has a dome shape with a raised central portion. It becomes. At this time, in the dome-shaped resist layer, the film thickness of the raised central part is thinner than other parts.
Then, the resist layer covering the hole is patterned by photolithography with an opening diameter smaller than the opening diameter of the hole, for example, about 80% of the hole. When dry etching is performed on the insulating layer covering the electrode pad using the resist layer as a mask, the thin resist layer is removed, and the resist layer is viewed in plan view. It will be in the state which blocked the inner side of the part in the shape of a bowl. Therefore, when the inner surface of the opening is covered with, for example, an insulating film, only the insulating layer between the electrode pads can be selectively etched without affecting the insulating film covering the inner surface. it can. And the penetration electrode formed in the hole part via the insulating layer becomes what electrically connected the active surface side and back surface side of the said board | substrate favorably.

In the method for manufacturing the semiconductor device, an opening smaller than the opening diameter of the hole may be formed by etching the resist layer.
In this manner, when the resist layer provided so as to cover the hole is heat-treated, the gas in the hole expands, and the resist layer covering the hole has a dome shape with a raised central part. At this time, since the dome-shaped resist layer is thinner in the raised central portion than in the other portions, the resist layer is formed by, for example, O ₂ plasma etching to form a thin dome central resist. Only the layer can be removed, and an opening smaller than the opening diameter of the hole is formed in the center of the resist layer. When dry etching is performed on the insulating layer covering the electrode pad using the resist layer as a mask, the inner surface of the hole is blocked in a bowl shape in a state in which the resist layer is viewed in plan. Therefore, when the inner surface of the opening is covered with, for example, an insulating film, only the insulating layer between the electrode pads can be selectively etched without affecting the insulating film covering the inner surface. it can. And the penetration electrode formed in the hole part via the insulating layer becomes what electrically connected the active surface side and back surface side of the said board | substrate favorably.

In the method of manufacturing a semiconductor device, it is preferable that the hole is filled with the conductive material and another electrode pad is formed on the back side of the substrate.
In this way, when the through electrode is formed by embedding the conductive material, another electrode pad is formed on the back side of the substrate, so that the other electrode pad is mounted on the back side of the substrate, for example. It can be used for connection with parts.

In the method for manufacturing a semiconductor device, it is preferable that the inner surface of the hole is covered with an insulating layer as a pre-process for providing the resist layer on the back side of the substrate.
In this case, when the silicon substrate is used as the substrate, for example, the inner surface of the hole is covered with the insulating layer, so that the conductive substrate and the through electrode are electrically connected to each other. It becomes possible.

In the method for manufacturing a semiconductor device, it is preferable that the hole is formed from the back side of the substrate.
In this way, it eliminates the complexity of the process of removing the film from the back surface side to the bottom surface of the electrode pad, which occurs when the through electrode is formed, so that good conduction between the conductive material and the electrode pad is achieved. Can be made.

  An embodiment of a method for manufacturing a semiconductor device of the present invention will be described below with reference to the drawings. Here, FIG. 1 and FIG. 2 are diagrams showing a manufacturing process of the semiconductor device 100. In the present embodiment, as shown in FIG. 3, a plurality of semiconductor devices 100 are collectively formed on the same silicon wafer (substrate) 500, and then diced (cut) into individual pieces. Although the semiconductor device 100 is obtained, FIGS. 1 and 2 show only a process of forming one semiconductor device in a simplified manner for the sake of simplicity.

First, on a surface of a semiconductor substrate (substrate) 10 made of a silicon wafer, an integrated circuit made up of a transistor, a memory element, and other electronic elements (not shown) is formed by a known method, and the surface on which these integrated circuits are formed. Is the active surface 10 a of the semiconductor substrate 10.
Then, as shown in FIG. 1A, electrode pads 12 are formed on the semiconductor substrate 10 with the insulating layer 22 interposed therebetween.

The insulating layer 22 is made of SiO ₂ or the like, and is for preventing the occurrence of current leakage between the through electrode 30 and the semiconductor substrate 10 and erosion due to oxygen, moisture, or the like.
The electrode pad 12 is made of, for example, Al. However, the electrode pad may be formed by laminating a plurality of layers, and the electrical characteristics and physical properties required for the electrode pad 12 may be used. It can be appropriately changed according to the physical characteristics and chemical characteristics.

  The electrode pad 12 is connected to the integrated circuit described above. After forming the electrode pad 12 on the semiconductor substrate 10 in this manner, although not shown, a support member made of a glass substrate or the like through an adhesive on the active surface 10a side of the semiconductor substrate 10 on which the electrode pad 12 is formed. To support. Thereby, when the semiconductor substrate 10 is thin-processed as will be described later from the back surface 10b side, it is possible to prevent the semiconductor substrate 10 from being cracked.

  As the adhesive, it is desirable to use a curable adhesive such as a thermosetting adhesive or a photocurable adhesive. Thereby, it is possible to firmly attach the support member while absorbing irregularities on the active surface 10a of the semiconductor substrate 10. Furthermore, when a photocurable adhesive such as an ultraviolet curable adhesive is used as the adhesive, it is preferable to employ a translucent material such as glass as the support member as described above. In this case, the adhesive can be easily cured by irradiating light from the outside of the support member.

  In this way, by performing, for example, CMP (Chemical Mechanical Polishing) from the back surface 10b side of the semiconductor substrate 10 with the semiconductor substrate 10 attached to the support member, as shown in FIG. The semiconductor substrate 10 is polished to a thickness of about 100 μm. In the following manufacturing process, though not shown, a through electrode described later is formed with the semiconductor substrate 10 held on the support member.

After forming the semiconductor substrate 10 to a predetermined thickness, as shown in FIG. 1C, a hole H3 is formed up to the interface between the semiconductor substrate 10 and the insulating layer 22 on the back surface 10b side of the substrate.
Specifically, a resist or the like is first applied to the entire back surface 10b of the semiconductor substrate 10 to pattern the shape of the hole H3. Next, dry etching is performed on the semiconductor substrate 10 using the patterned resist as a mask. As such dry etching, RIE (reactive ion etching) or the like can be employed. Then, if the resist is peeled off, the hole H3 can be formed on the back surface 10b side of the semiconductor substrate 10. Further, the insulating layer 22 exposed at the bottom of the hole H3 and covering the electrode pad 12 is removed by dry etching as shown in FIG.

  Subsequently, as shown in FIG. 1E, an insulating layer 23 is formed on the back surface 10b of the semiconductor substrate 10 and on the inner side surface and the bottom surface of the hole H3. As a method for forming the insulating layer 23, for example, a CVD method or the like can be employed. As a method of forming the insulating layer 23, the insulating layer 23 may be formed by thermally oxidizing the semiconductor substrate 10 made of silicon to cover the entire back surface 10b of the semiconductor substrate 10 and the inner side surface of the hole H3. .

Next, as shown in FIG. 2A, a resist layer 32 is provided on the back surface 10b side of the semiconductor substrate 10 so as to cover the hole. The resist layer 32 is heat-treated.
The resist layer 32 is applied by spin coating. And after apply | coating a resist, heat processing (baking process) are performed.
As the heat treatment method, for example, a hot plate or a warm air circulation oven can be used.
The conditions for using a hot plate are, for example, heat treatment at 100 ° C. for about 3 to 5 minutes. In the case of a warm air circulation oven, a heat treatment is performed at 90 ° C. for about 30 minutes.

  As described above, when the heat treatment is performed on the resist layer 32, the resist layer 32 is provided so as to cover the hole H3. Therefore, the gas in the hole H3 expands, and the resist covering the hole H3 is formed. As shown in FIG. 2B, the layer 32 has a dome shape with a raised central portion.

Subsequently, the dome-shaped resist layer 32 covering the hole H3 is patterned by photolithography. By setting the opening diameter to 80% of the hole opening diameter, for example, the opening SH is formed as shown in FIG.
As will be described later, the opening SH may be formed by etching the dome-shaped resist layer 32 covering the hole H3.

After the opening SH is formed in the resist layer 32, the insulating layer 23 exposed on the bottom surface of the hole H3 and covering the electrode pad 12 is dried by using the resist layer having the opening as a mask. Remove by etching.
Here, since the opening SH formed in the resist layer 32 is smaller than the opening diameter of the hole H3 as described above, when dry etching is performed using the resist layer 32 as a mask, the opening SH is formed. The resist layer 32 is in a state where the inner surface of the hole H3 is shielded in a bowl shape in a plan view. Further, in this embodiment, although the inner surface of the opening SH is covered with the insulating layer 23, the resist layer 32 reliably prevents the inner insulating layer 23 from being etched, and the insulating layer Only 23 can be selectively removed.

  In this way, when the insulating layer 23 provided on the bottom surface of the hole H3 is selectively removed from the insulating layer 23 covering the side surface and the bottom surface of the hole H3, if the present invention is adopted, the hole is formed. Only the insulating layer 23 on the bottom surface can be reliably removed without etching the insulating layer 23 on the side surface of the portion H3.

After the insulating layer is removed by etching, the resist layer 32 is peeled off as shown in FIG. 2D, and a through electrode 30 is formed by embedding a conductive material in the hole H3. At this time, an electrode pad used as a mechanical connection portion when another device or the like is mounted may be formed.
Specifically, a material having a low electrical resistance such as Cu (copper) or W (tungsten) can be suitably used as the conductive material. Note that a base film may be formed in the hole H3 when the conductive material is embedded.
After forming the through electrode 30 in the semiconductor substrate 10 in this way, the silicon wafer (substrate) 500 is diced (cut) into individual semiconductor devices 100 by the dicing device 210 as shown in FIG. Each semiconductor device 100 is peeled from a support member (not shown).

  According to the semiconductor device manufacturing method of the present embodiment, as described above, the electrode pad is formed using the dome-shaped resist layer 32 having an opening smaller than the opening diameter of the hole H3 on the center of the hole H3 as a mask. 12 is dry-etched on the insulating layer 23 covering the top surface of the insulating layer 23, so that the electrode pad generated when the through electrode 30 is formed from the back side without affecting the insulating layer 23 covering the inner surface of the hole H3. Thus, only the insulating layer 23 interposed between the layers 12 can be selectively removed. Therefore, the through electrode 30 provided in the hole H3 is a good conductor between the active surface 10a side and the back surface 10b side of the semiconductor substrate 10.

Note that photolithography was used to form the opening SH in the resist layer 32, but etching may be used instead.
First, dry etching such as O ₂ plasma is performed on the dome-shaped resist layer 32 covering the hole H3. At this time, as described above, the dome-shaped resist layer 32 is in a state where the central portion is raised by the expanded gas, so that the film thickness in the central portion of the resist layer 32 is thinner than the other portions. ing.
Therefore, only the thin dome-shaped central portion can be selectively removed by irradiating O ₂ plasma, and the opening diameter of the hole H3 is formed in the resist layer 32 on the central portion of the hole H3. A smaller opening SH is formed.

After the opening SH is formed in the resist layer 32, the resist layer having the opening is used as a mask to expose the bottom surface of the hole H3 and cover the electrode pad 12 in the same manner as the above process. By removing the insulating layer 23 by dry etching, the through electrode 30 is formed by embedding a conductive material in the hole H3.
Also by such a method of manufacturing a semiconductor device, only the insulating layer 23 interposed between the electrode pads 12 generated when the through electrode 30 is formed from the back surface side can be selectively removed and provided in the hole H3. The penetrating electrode 30 provides good conduction between the active surface 10 a side and the back surface 10 b side of the semiconductor substrate 10.

  The semiconductor device obtained by the method for manufacturing a semiconductor device of the present invention is not limited to a circuit board or the like provided with a through electrode on a substrate on which a semiconductor element or the like is formed. It can also be applied to devices.

(Semiconductor device)
Next, the configuration of the semiconductor device 100 manufactured by the semiconductor device manufacturing method according to the above-described embodiment will be described. FIG. 4 is a diagram showing the semiconductor device 100 formed by the manufacturing method described above.
As shown in FIG. 4, the semiconductor device 100 includes a through electrode 30 made of a conductive material embedded through an insulating layer 23 in a hole H3 provided in a semiconductor substrate 10 made of silicon having a thickness of about 100 μm. The electrode pad 12 is provided on the active surface 10 a side of the semiconductor substrate 10 and is electrically connected to the through electrode 30.
Further, an insulating layer 22 is interposed between the electrode pad 12 and the semiconductor substrate 10, but a part of the insulating layer 22 is removed by the above-described manufacturing process, so that the electrode pad 12 and the through electrode 30 are connected. Good conduction. In addition, the semiconductor device 100 includes an electrode pad 13 formed in the same process as the through electrode 30 on the back surface 10 b side of the semiconductor substrate 10.
According to the semiconductor device 100, since the semiconductor device 10 is configured by the semiconductor substrate 10 on which the through electrode 30 that is reliably formed by the manufacturing method described above is formed, the reliability is high and the cost is reduced. It is what was planned.

FIG. 5 is a diagram showing a schematic configuration of a circuit board structure including the semiconductor device 100 formed by the manufacturing method described above.
As shown in FIG. 5, the semiconductor device 100 is mounted on a circuit board 200 to form a circuit board structure. The circuit board structure is mounted on a device such as an electronic device.
The circuit board 200 is provided with a connection terminal 110, and the connection terminal 110 and the electrode pad 12 on the active surface 10 a side of the semiconductor device 100 are connected via a brazing material, for example, a solder layer 40, thereby providing a semiconductor. The apparatus 100 is mounted.

As the solder layer 40, for example, lead-free solder such as tin and silver is used. As a method for forming the solder layer 40 (deposition method), for example, wet plating methods such as electrolytic plating, immersion plating, and electroless plating, chemical vapor deposition methods (CVD) such as thermal CVD, plasma CVD, and laser CVD, vacuum deposition, and the like. Examples thereof include dry plating methods such as sputtering and ion plating, thermal spraying, and metal foil bonding. Among these, the wet plating method is particularly preferable. According to the wet plating method, the solder layer 40 is easily formed.
For example, lead-free solder is used for the solder layer 40, but metal paste, molten paste, or the like can also be used.

Further, as shown in FIG. 5, another component or the like may be mounted on the through electrode 30 on the back surface 10 b side of the semiconductor device 100. Examples of such other components include electronic components such as an IC chip. The electronic component 300 includes bumps 160 for connecting to the semiconductor device 100 through the solder layer 40. The bump 160 is disposed at a position overlapping the through electrode 30 provided in the semiconductor device 100 in a plan view. For the connection between the IC chip and the through electrode 30, the solder layer such as the brazing material described above can be employed. Further, the electrode pad 13 formed in the same process as the through electrode 30 on the back surface 10 b side of the semiconductor substrate 10 is mechanically connected to the electronic component 300 through the solder layer 40.
Even in such a circuit board structure, since the highly reliable semiconductor device 100 formed by the above-described manufacturing method is mounted, the device itself is also highly reliable and the cost can be reduced. It becomes.

It is a figure explaining the manufacturing process of a semiconductor device. FIG. 2 is a diagram for explaining a manufacturing step for the semiconductor device following that of FIG. 1; It is a figure which shows the dicing process in the manufacturing process of a semiconductor device. It is a figure which shows schematic structure of the semiconductor device obtained by the manufacturing method of the semiconductor device. It is a figure which shows the circuit board structure provided with the semiconductor device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Board | substrate, 10a ... Active surface, 10b ... Back surface, 12 ... Electrode pad, 13 ... Electrode pad (other electrode pads), 23 ... Insulating layer, 30 ... Through electrode, 32 ... Resist layer, 100 ... Semiconductor device, H3 ... hole, SH ... opening

Claims (3)

An electrode pad is provided on the active surface side of the substrate through an insulating layer, and a conductive material is formed in a hole formed in the substrate immediately above the electrode pad and reaching the insulating film from the back side opposite to the active surface. In a manufacturing method of a semiconductor device in which a through electrode is formed by embedding
Covering the inner surface of the hole with an insulating layer;
So as to cover the hole portion on the back side of the substrate a resist layer is provided, wherein the resist layer is heat treated, the hole in the central portion on the resist layer thickness of the central portion of the hole of A step of making the thickness of the resist layer thinner than other portions different from
Etching the thickness of the film thickness of the central portion of the hole, forming an opening smaller than the opening diameter of the hole in the resist layer on the central portion of the hole,
By using the resist layer in which the opening is formed as a mask, etching the insulating layer,
After etching the insulating layer, peeling the resist layer, embedding a conductive material in the hole to form the through electrode , and
In the heat treatment step, by expanding the gas in the hole, the central portion of the resist layer is raised to form a dome shape,
In the etching step, the opening is formed by selectively removing a portion having a smaller film thickness than other portions by being raised in the dome shape by etching the resist layer. Device manufacturing method.   2. The method of manufacturing a semiconductor device according to claim 1, wherein the conductive material is embedded in the hole and another electrode pad is formed on the back side of the substrate. 3. The method of manufacturing a semiconductor device according to claim 1, wherein the hole is formed from a back surface side of the substrate.

Images