JP2016127244A - Semiconductor device manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device manufacturing method which can improve breakdown resistance.SOLUTION: According to an embodiment, a semiconductor device manufacturing method including a first process, a second process and a third process is provided. In the first process, a developing solution is supplied to a laminate including a substrate, a first film provided on the substrate and a second film provided on the first film to form an opening in the second film and part of the first film exposed from the opening is removed. In the second process after the first process, a first solution having solubility to the first film is supplied to the opening and part of the second film is removed. In the third process after the second process, a second solution having solubility to the first film lower than that of the first solution is supplied to the laminate.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a method for manufacturing a semiconductor device.

  For example, in an insulated gate bipolar transistor (IGBT) used at a high voltage, a protective film such as a polyimide film is provided on the surface of the element.

  In manufacturing a semiconductor device, an opening is formed in the polyimide film in order to connect an element such as a transistor and a wiring. A process such as photolithography is used to form the opening. During the formation of the opening, foreign matter may be generated on the polyimide film. Such foreign matter may affect the breakdown tolerance and reliability of the semiconductor device.

Japanese Patent Laid-Open No. 10-12605

  Embodiments of the present invention provide a method of manufacturing a semiconductor device that can improve the breakdown tolerance.

  According to the embodiment of the present invention, a semiconductor device manufacturing method including a first step, a second step, and a third step is provided. In the first step, a developer is supplied to a laminate including a substrate, a first film provided on the substrate, and a second film provided on the first film. Then, an opening is formed in the second film, and the first film exposed in the opening is partially removed. In the second step after the first step, a first liquid having solubility in the first film is supplied to the opening to remove a part of the second film. In the third step after the second step, a second liquid having a lower solubility in the first film than the first liquid is supplied to the stacked body.

FIG. 1A to FIG. 1C are schematic cross-sectional views in order of the processes, illustrating the method for manufacturing a semiconductor device according to the embodiment. 2A to 2C are schematic cross-sectional views in order of the processes, illustrating the method for manufacturing a semiconductor device according to the embodiment. FIG. 3A and FIG. 3B are schematic cross-sectional views in order of the processes, illustrating the method for manufacturing a semiconductor device according to the embodiment. FIG. 4A to FIG. 4D are schematic cross-sectional views in order of the processes, illustrating a method for manufacturing a semiconductor device according to a reference example.

Each embodiment will be described below with reference to the drawings.
The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between the parts, and the like are not necessarily the same as actual ones. Further, even when the same part is represented, the dimensions and ratios may be represented differently depending on the drawings.
Note that, in the present specification and each drawing, the same elements as those described above with reference to the previous drawings are denoted by the same reference numerals, and detailed description thereof is omitted as appropriate.

FIG. 1A to FIG. 1C are schematic cross-sectional views in order of the processes, illustrating the method for manufacturing a semiconductor device according to the embodiment.
FIG. 2A to FIG. 2C are schematic cross-sectional views in order of the processes, illustrating the method for manufacturing the semiconductor device, following FIG.
FIG. 3A and FIG. 3B are schematic cross-sectional views in order of the processes, illustrating the method for manufacturing the semiconductor device, following FIG.

  As shown in FIG. 1A, the method for manufacturing a semiconductor device according to the embodiment includes a substrate 10, a polyimide film 11 (first film), and a resist film 12 (second film). A semiconductor wafer 20 (laminated body) is used.

  The substrate 10 is a semiconductor substrate including a semiconductor such as silicon. The substrate 10 is provided with a semiconductor element such as an IGBT.

  The polyimide film 11 is provided on the substrate 10. The polyimide film 11 includes non-photosensitive polyimide. The polyimide film 11 functions as a protective film for the semiconductor element provided on the substrate 10. The thickness of the polyimide film 11 is 5 micrometers (μm) or more. By increasing the thickness of the polyimide film 11, the breakdown voltage of the semiconductor device can be improved.

  The resist film 12 is provided on the polyimide film 11. The resist film 12 is a film containing a photosensitive substance called a resist. A positive resist is used for the resist film 12. The resist includes, for example, a novolac resin.

  First, selective exposure using a mask is performed by an exposure apparatus to transfer a desired pattern to the resist film 12. Thereby, the resist film 12 is provided with an exposed portion 12a and a non-exposed portion 12b.

  Thereafter, the semiconductor wafer 20 is held with the resist film 12 facing upward, and the following development process (first process), cleaning process (second process), and rinsing process (third process) are performed.

  As shown in FIG. 1B, a developing solution 13 is supplied to the resist film 12 of the semiconductor wafer 20 to develop the resist film 12. Specifically, the developer 13 is dropped from the developing nozzle 40 while rotating the semiconductor wafer 20 about the rotation shaft 30. As a result, the developer 13 spreads in the radial direction of the semiconductor wafer 20 and spreads over the entire surface of the resist film 12.

  The developer 13 is a positive resist developer. As the developer 13, an organic strong base aqueous solution is used. For example, the developer 13 contains trimethylhydroxyethylammonium hydroxide (choline).

  Such a developer 13 dissolves the exposed portion 12a of the positive resist. Therefore, in this development step, the exposed portion 12a is selectively removed from the resist film 12, and the non-exposed portion 12b remains. Thereby, an opening 12 e is formed in a part of the resist film 12.

  Further, the developer 13 has a property of dissolving the polyimide film 11. For this reason, a part (first portion 11a) of the polyimide film 11 exposed in the opening 12e is also selectively removed. Thus, in the embodiment, the development of the resist film 12 and the opening of the polyimide film 11 can be processed simultaneously.

  Thereafter, as shown in FIG. 1C, the rotation of the semiconductor wafer 20 is stopped. The developer 13 is present on the surface of the semiconductor wafer 20, and this state is maintained for a desired time.

  As described above, the developer 13 dissolves the polyimide film 11. For this reason, a part of the polyimide film 11 is further dissolved by the developer 13 in a state where the rotation is stopped. As a result, side etching occurs in the polyimide film 11 as shown in FIG. That is, the portion (second portion 11b) provided adjacent to the first portion 11a of the polyimide film 11 is further removed.

  A side etched portion 12s shown in FIG. 2A is formed in the non-exposed portion 12b. The side etching part 12s is a part located in the vicinity of the opening part 12e, and is a part provided on the side-etched polyimide film 11.

  Thereafter, as shown in FIG. 2B, the first liquid 14 is supplied to the semiconductor wafer 20. Thereby, the resist film 12 and the polyimide film 11 are washed. Specifically, the first liquid 14 is dropped from the nozzle 41 while rotating the semiconductor wafer 20 around the rotation shaft 30. As the first liquid 14, a liquid having high solubility in the polyimide film 11 (liquid that dissolves the polyimide film 11) is used. For example, as the first liquid 14, a liquid containing the same components as the developer 13 for the resist film 12 is used.

  When the first liquid 14 flows on the semiconductor wafer 20, a part of the resist film 12 is crushed by the pressure of the first liquid 14. That is, the resist film 12 is cracked in the side etching portion 12s, and a fragment 12p is generated. The fragments 12p are washed away from the semiconductor wafer 20 by the first liquid 14 and removed.

Thereafter, the rinsing liquid 15 (second liquid) is supplied to the semiconductor wafer 20 to clean the resist film 12. As shown in FIG. 2C, the semiconductor wafer 20 is rotated around the rotation shaft 30, and the rinse liquid 15 is dropped from the rinse nozzle 42. At this time, the rinse nozzle 42 is moved along the radial direction. The rinsing liquid 15 dropped on the semiconductor wafer 20 spreads in the radial direction of the semiconductor wafer 20 to wash away the first liquid 14 and the like from the semiconductor wafer 20.
For example, pure water can be used for the rinse liquid 15. The solubility of the rinsing liquid 15 in the polyimide film 11 is lower than the solubility of the first liquid 14 in the polyimide film 11. Note that “low solubility” includes that the rinsing liquid 15 does not dissolve the polyimide film 11.

  After this rinsing step, as shown in FIG. 3A, rotary drying is performed to rotate the semiconductor wafer 20. By this rotary drying, the rinsing liquid 15 remaining on the surface of the semiconductor wafer 20 is moved outward in the radial direction by centrifugal force and removed from the wafer 20.

  After the drying step, the resist film 12 is peeled off as shown in FIG. The resist film 12 is removed using a solvent containing butyl acetate.

  In this way, the semiconductor device 100 according to the embodiment is completed. Thereafter, a sealing material such as a resin is provided on the polyimide film 11 to form a semiconductor package.

  When a semiconductor device having the polyimide film 11 is manufactured, foreign matter may be generated on the polyimide film 11. When a foreign substance is generated on the polyimide film 11, the adhesion between the resin provided on the polyimide film 11 and the polyimide film 11 is lowered. As a result, the semiconductor device is likely to be broken, and there is a possibility that reliability is lowered. Further, in the appearance inspection at the wafer level, when a foreign substance is generated, it is judged as a defect and the yield may be lowered.

  As a cause of the generation of foreign matter on the polyimide film 11, the following reference example is given by paying attention to the side etching portion 12 s of the resist film 12.

FIG. 4A to FIG. 4D are schematic cross-sectional views in order of the processes, illustrating a method for manufacturing a semiconductor device according to a reference example. 4A to 4D correspond to drawings in which the periphery of the polyimide film 11 partially side-etched and the side-etched portion 12s in FIG. 2A is enlarged.
In the reference examples shown in FIGS. 4A to 4D, the cleaning process (resist crushing) described in FIG. 2B is not performed after the development process described in FIG. A rinsing step is performed.

FIG. 4A to FIG. 4C illustrate the semiconductor device in the rinsing process after the developing process.
As shown in FIG. 4A, when the rinsing process is performed after the developing process, the side etching portion 12s of the resist film 12 remains. In this state, the rinsing liquid 15 (pure water) is dropped on the semiconductor wafer 20 and the semiconductor wafer 20 rotates. The arrows in the figure schematically represent the flow of the rinsing liquid 15.

  As shown in FIG. 4B, the resist film 12 is crushed in the side etching portion 12s by the water pressure of pure water, and fragments 12p are generated. At this time, a part 11f of the polyimide film 11 is attached to the broken piece 12p. A part 11f of the polyimide film 11 is a part that was not completely dissolved by the developer in the developing process. For this reason, for example, a part 11f of the polyimide film 11 adheres to the fragments 12p in a viscous state.

  Since the solubility of the pure water in the polyimide film 11 is low, the debris 12p flows into the pure water with a part 11f of the polyimide film 11 attached, and adheres on the resist film 12 as shown in FIG. . At this time, it is considered that a part 11f of the polyimide film 11 adhered to the broken piece 12p works like an adhesive.

  After this rinsing step, rotary drying is performed in the same manner as in the manufacturing method according to the embodiment. Thereafter, a resist stripping step shown in FIG. In the resist stripping step, a solvent 16 that dissolves the resist is used. As the solvent 16, a liquid that does not dissolve the polyimide film 11 is used in order to maintain the pattern formed on the polyimide film 11.

  As described above, a part 11 f of the polyimide film 11 is attached to the fragments 12 p attached on the resist film 12. This part 11 f is not dissolved by the solvent 16. For this reason, in the resist stripping process, the solvent 16 is not sufficiently supplied to the resist film 12 which is hindered by the part 11f and located below the part 11f. A part of the resist remains after the resist stripping step. Due to the mechanism described above, it is considered that the resist to which polyimide is adhered remains as foreign matter.

  Here, in order to suppress generation | occurrence | production of the foreign material on the polyimide film 11, the method of forming the resist film 12 thickly and making it hard to crush is also considered. However, if the resist film 12 is too thick, the dimensional accuracy of the resist pattern may be insufficient. In addition, due to the limit of the thickness of the resist film (for example, about 5 μm), this method is often insufficient as an improvement method.

  On the other hand, the manufacturing method according to the embodiment includes a cleaning step with the first liquid 14 between the developing step in FIG. 2A and the rinsing step in FIG. The first liquid 14 has solubility in the polyimide film 11. For this reason, the polyimide adhering to a part of the fragments 12p is dissolved by the first liquid 14. Thereby, it can suppress that the fragment 12p adheres on the resist film 12. FIG. The debris 12p is washed away by the first liquid 14 in this washing step. Even if the debris 12p is not sufficiently removed in this cleaning step, in the subsequent resist peeling step, the polyimide adhering to the debris 12p is dissolved, so that a sufficient solvent is supplied to the resist. For this reason, generation | occurrence | production of the foreign material on the polyimide film 11 can be suppressed. By suppressing the foreign matter, the breakdown tolerance of the semiconductor device can be improved. For example, when a resin is formed on the polyimide film 11, the adhesion between the polyimide film 11 and the resin can be improved. By improving the adhesion, the breakdown tolerance of the semiconductor device can be improved.

  The cleaning process using the first liquid 14 is preferably performed before the rinsing process. When the cleaning process using the first liquid 14 is performed after the rinsing process, the polyimide film 11 is further dissolved by the first liquid 14. For this reason, the dimension of the polyimide film 11 will change. Further, when the cleaning process using the first liquid 14 is performed after the rinsing process, the fragments 12p have already adhered to the resist film 12 during the rinsing process using the rinsing liquid 15 as in FIG. It has been. Thereafter, even if cleaning with the first liquid 14 is performed, the resist as a fragment 12p may inhibit the polyimide as an adhesive material to be sufficiently dissolved. Therefore, the resist is crushed and washed before the rinsing step. Thereby, generation | occurrence | production of a foreign material can be suppressed.

  The first liquid 14 is preferably the same liquid as the developing solution for the resist film 12. Thereby, complication of the manufacturing process can be suppressed.

  In the cleaning process using the first liquid 14, the semiconductor wafer 20 is rotated. Thereby, the relative speed of the first liquid 14 with respect to the side etching portion 12s is increased. For example, the relative speed of the first liquid 14 with respect to the resist film 12 in the cleaning process is higher than the relative speed of the developer 13 with respect to the resist film 12 in the developing process. Thereby, the side etching part 12s can be easily crushed in the cleaning process using the first liquid 14.

  In a semiconductor device that requires a high breakdown voltage, it is preferable to increase the thickness of the polyimide film 11 to reduce the electric field strength applied to the element portion. However, since the polyimide film 11 is wet-etched as described above, side etching increases with the thickness of the polyimide film 11. The larger the side etching, the more likely the fragments 12p of the resist film 12 are generated. For this reason, in a semiconductor device having a thick polyimide film 11, there is a tendency that foreign matters are likely to be generated. However, according to the present embodiment, even when the polyimide film 11 is thick, the debris 12p is washed away by the cleaning process using the first liquid 14, so that foreign matter is hardly generated. This makes it possible to stably produce a high breakdown voltage semiconductor device.

  In the embodiment, since the resist film 12 is crushed and washed, the resist film 12 can be formed thin. Thereby, dimensional accuracy can be improved. Further, the polyimide film 11 can be made thick without being limited by the limit of the thickness of the resist film 12.

The embodiments of the present invention have been described above with reference to specific examples. However, embodiments of the present invention are not limited to these specific examples. For example, regarding the specific configuration of each element such as a substrate, a polyimide film, a resist film, a developer, and a rinsing solution, those skilled in the art can similarly implement the present invention by selecting appropriately from a known range, As long as an effect can be obtained, it is included in the scope of the present invention.
Moreover, what combined any two or more elements of each specific example in the technically possible range is also included in the scope of the present invention as long as the gist of the present invention is included.

  In addition, based on the semiconductor device manufacturing method described above as an embodiment of the present invention, all semiconductor device manufacturing methods that can be implemented by those skilled in the art as appropriate are included in the gist of the present invention. It belongs to the scope of the present invention.

  In addition, in the category of the idea of the present invention, those skilled in the art can conceive of various changes and modifications, and it is understood that these changes and modifications also belong to the scope of the present invention. .

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 10 ... Substrate, 11 ... Polyimide film (first film), 11a ... First part, 11b ... Second part, 12 ... Resist film (second film), 12a ... Exposed part, 12b ... Non-exposed part, 12e ... Opening part, 12p ... fragment, 12s ... side etching part, 13 ... developing liquid, 14 ... first liquid, 15 ... rinsing liquid (second liquid), 16 ... solvent, 20 ... semiconductor wafer (laminated body), 30 ... Rotating shaft, 40 ... developing nozzle, 41 ... nozzle, 42 ... rinse nozzle, 100 ... semiconductor device

Claims (6)

A developer is supplied to a laminate including a substrate, a first film provided on the substrate, and a second film provided on the first film, and the second film is supplied. Forming a first opening and partially removing the first film exposed in the opening;
A second step of removing a part of the second film by supplying a first liquid having solubility in the first film to the opening after the first step;
After the second step, a third step of supplying the laminate with a second liquid having solubility in the first film that is lower than the first liquid;
A method for manufacturing a semiconductor device comprising:   The method of manufacturing a semiconductor device according to claim 1, wherein the second step includes crushing the part of the second film with the first liquid.   The method for manufacturing a semiconductor device according to claim 2, wherein the second step includes removing the part of the crushed second film from the stacked body.   The relative speed of the first liquid supplied in the second step with respect to the second film is higher than the relative speed of the developer supplied in the first step with respect to the second film. The manufacturing method of the semiconductor device as described in any one of 1-3.   5. The manufacturing of a semiconductor device according to claim 1, wherein the second step includes rotating the stacked body while dropping the first liquid on the stacked body after the first step. Method.   The method for manufacturing a semiconductor device according to claim 1, wherein a component contained in the first liquid is the same as a component contained in the developer.

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