JP2014094504A - Silicon substrate processing method, and manufacturing method of substrate for liquid discharge head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silicon substrate processing method in which etching time can be reduced while securing flatness of a substrate surface.SOLUTION: A silicon substrate processing method, in which open holes are formed on a silicon substrate having a first surface and a second surface being an opposite surface against the first surface by using etching liquid, comprises: a step for forming first non-open holes in the first surface of the silicon substrate; a step for filling into the first non-open holes solid particles which is soluble in the etching liquid; a step for forming second no-open holes in the second surface of the silicon substrate; and a step for forming the open holes by applying etching processing to the silicon substrate in which the first non-open holes filled with the solid particles and the second no-open holes are formed from the second surface with using the etching liquid.

Description

  The present invention relates to a method for processing a silicon substrate, and preferably to a method for manufacturing a substrate for a liquid discharge head.

  As the density and accuracy of ink jet recording heads are increasing, higher nozzle ejection accuracy is required. Flatness of the wafer surface is required in order to increase the accuracy of nozzle processing that becomes a portion for ejecting ink. Further, in order to reduce costs and increase tact time, shortening of each processing step is required, and in particular, shortening of an ink supply port forming step for forming a through hole in a silicon substrate is required. Patent Document 1 discloses a method for manufacturing a liquid discharge head in which recesses are formed by irradiating laser light on the front and back surfaces of a silicon substrate, and a liquid supply port is formed by anisotropic etching.

JP 2011-51253 A

  Although the technique described in Patent Document 1 can shorten the etching time, a large number of holes are opened on the surface of the silicon substrate, and a desired flatness cannot be ensured when a liquid nozzle material is applied. There is a case. Even when a dry film is used to maintain flatness, it is difficult to ensure desired processing accuracy and film thickness accuracy.

  Accordingly, an object of the present invention is to provide a silicon substrate processing method capable of shortening the etching time while ensuring the flatness of the substrate surface.

The form of the present invention is:
A method of processing a silicon substrate, wherein a through hole is formed using an etchant in a silicon substrate having a first surface and a second surface opposite to the first surface,
Forming a first non-through hole in the first surface of the silicon substrate;
Filling the first non-through holes with solid particles dissolved in the etching solution;
Forming a second non-through hole in the second surface of the silicon substrate;
The silicon substrate on which the first non-through hole and the second non-through hole filled with the solid particles are formed is etched from the second surface using the etchant, thereby allowing the penetration. Forming a hole;
A method for processing a silicon substrate, comprising:

The form of the present invention is:
A method for manufacturing a substrate for a liquid discharge head comprising a silicon substrate having a liquid supply port for supplying the liquid to a liquid flow path communicating with a discharge port for discharging liquid,
The liquid supply port is formed by the silicon substrate processing method, wherein the liquid discharge head substrate is manufactured.

  According to the configuration of the present invention, it is possible to provide a silicon substrate processing method capable of shortening the etching time while ensuring the flatness of the substrate surface. Further, according to a preferred embodiment of the present invention, it is possible to provide a method for manufacturing a substrate for a liquid discharge head capable of shortening the etching time while ensuring the flatness of the substrate surface. In addition, according to a more preferred embodiment of the present invention, the flatness of the substrate surface can be ensured by filling the solid particles in the non-through holes on the substrate surface, similarly to the substrate having no through holes. A nozzle material can be disposed on the substrate. Moreover, etching time can be shortened because the alkali-soluble solid particles in the non-through holes are dissolved during etching.

It is typical sectional process drawing for demonstrating the processing method of the silicon substrate concerning this embodiment. It is typical sectional process drawing for demonstrating the processing method of the silicon substrate concerning this embodiment. It is a typical perspective view which shows the structural example of a liquid discharge head.

  In this specification, an inkjet recording head substrate will be described as an example of application of the present invention. However, the scope of application of the present invention is not limited to this, and liquid for biochip production and electronic circuit printing is used. The present invention can also be applied to a discharge head substrate. As the liquid discharge head substrate, in addition to the inkjet recording head substrate, for example, a head substrate used for manufacturing a color filter may be used.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIGS. 1A to 1G are cross-sectional process diagrams for explaining the manufacturing process of the inkjet recording head substrate according to this embodiment, and correspond to the cross-sectional view taken along the line AA of FIG. FIG. 3 is a schematic perspective view for illustrating a configuration example of a substrate for an ink jet recording head.

  As shown in FIG. 3, the inkjet recording head substrate has a silicon substrate 1 on which ejection energy generating elements 10 are formed in two rows at a predetermined pitch. On the silicon substrate 1, a flow path forming member 6 constituting an ink flow path (liquid flow path) and an ink discharge port (liquid discharge port) 7 that opens above the discharge energy generating element 10 is formed. The flow path forming member 6 constitutes an upper wall and a side wall of an ink flow path that communicates from an ink supply port (liquid supply port) 8 as a through hole to each ink discharge port 7. An ink supply port 8 formed by anisotropic etching of silicon is provided so as to open between two rows of the ejection energy generating elements 10. This ink jet recording head substrate applies an ink liquid from the ink discharge port 7 by applying a pressure generated by the discharge energy generating element 10 to the ink (liquid) filled in the ink flow path via the ink supply port 8. Recording is performed by ejecting droplets and attaching them to a recording medium.

  Next, a method for manufacturing a silicon substrate of the present invention will be described by explaining a method for manufacturing an ink jet recording head substrate of the present embodiment with reference to FIG.

  First, as shown in FIG. 1A, a silicon substrate 1 having an ejection energy generating element 10 on a first surface (front surface) is prepared, and a back surface (surface opposite to the surface from the surface of the substrate 1) A plurality of first non-through holes 2a not penetrating is formed toward the second surface.

  The first non-through hole 2a can be formed by, for example, laser beam irradiation, dry etching, drilling, or the like, but debris 3 may be generated by laser beam irradiation and burrs may be generated by drilling. The laser beam used for processing is not particularly limited as long as it can absorb multiphotons with respect to silicon which is a material of the substrate.

  The place where the first non-through hole 2a is formed is preferably a position that becomes the center of the ink supply port. Further, a sacrificial layer (not shown) may be provided. By forming the sacrificial layer, the surface opening of the ink supply port can be accurately defined. The sacrificial layer contains aluminum and can be etched with an etching solution (alkali solution) of the silicon substrate. Examples of the material for the sacrificial layer include aluminum (Al), aluminum silicon (AlSi), aluminum copper (AlCu), and aluminum silicon copper (AlSiCu).

  The diameter of the first non-through hole 2a is desirably φ5 μm to 100 μm. When the diameter of the first non-through hole 2a is 5 μm or more, it is preferable because the solid particle or liquid easily enters the first non-through hole 2a when the solid particle or liquid is filled in a subsequent process. . Further, when the diameter of the first non-through hole 2a is 100 μm or less, it is preferable because it takes a relatively short time to form the first non-through hole 2a having a desired depth. The depth of the first non-through hole 2a is preferably formed to a depth in the range of 50 to 98% with respect to the thickness of the substrate. When the depth of the first non-through hole 2a is 50% or more with respect to the thickness of the substrate, it is preferable because an etching time performed in a subsequent process is shortened. When the depth of the first non-through hole 2a is 98% or less, the possibility that the first non-through hole 2a penetrates to the back surface of the silicon substrate 1 or the back surface is altered is low. Therefore, it is preferable.

  The first surface and the second surface of the silicon substrate 1 preferably have a plane orientation of (100).

  Next, as shown in FIG.1 (b), the solid particle 4 which melt | dissolves in the etching liquid used by a post process is filled in the 1st non-through-hole.

  The filling of the solid particles is not particularly limited, but can be performed, for example, by polishing the surface of the silicon substrate 1 using the solid particles 4. In addition, as described above, if there are debris 3 or burrs generated when the first non-through hole 2a is formed on the surface of the silicon substrate 1, the debris 3 and burrs are removed and removed in the first non-through hole 2a. The solid particles 4 that also function as an abrasive can be filled.

  The material of the solid particles 4 may be any material that can be dissolved in an etching solution during etching. Examples thereof include silicon (Si), aluminum (Al), aluminum silicon, aluminum copper, aluminum silicon copper, and glass.

  The volume average particle size of the solid particles is preferably 0.01 μm or more and 100 μm or less.

  The solid particles 4 are preferably filled by chemical mechanical polishing using a slurry in which the solid particles 4 are suspended in a liquid such as water or a solvent. The slurry concentration is preferably 1% by mass or more and 50% by mass or less. When the slurry concentration is 1% by mass or more, it is preferable because the time for filling the non-through holes 2a with the solid particles 4 is shortened. A slurry concentration of 50% by mass or less is preferable because the slurry has high fluidity and is easy to handle. At this time, the polishing pressure, rotation speed, particle diameter, particle hardness, slurry concentration, etc. are tuned so as not to damage the surface of the silicon substrate 1 so that scratches (small scratches) and dishing (unevenness) do not occur. It is desirable to perform filling under conditions. Furthermore, in order to further improve the filling property, a liquid that solidifies after filling into the first non-through hole 2a may be used. Examples of the liquid include a resin having the same material as the mold pattern described later, a novolac resin, an epoxy acrylate resin, and a silicon-based alkali-soluble resin. Further, in order to fill the first non-through hole 2a with the solid particles 4 or the liquid containing the solid particles 4, the filling may be performed under vacuum. Moreover, you may pass through a drying process after filling.

  Next, as shown in FIG. 1C, a mold pattern 5 is formed on the surface of the silicon substrate using a dissolvable material. The mold pattern 5 serves as an ink flow path mold.

  More specifically, for example, a photosensitive resin such as a positive resist is applied by spin coating, direct coating, spraying, or the like to form a resin layer, and the resin layer is exposed and developed to obtain a desired The mold pattern 5 having the ink flow path pattern is formed. In addition, you may form the contact | adherence layer (not shown) for improving the adhesiveness of the silicon substrate 1 and the flow-path formation member 6 before apply | coating photosensitive resin.

  Next, as shown in FIG. 1 (d), the flow path forming member 6 having the ink discharge ports 7 is formed on the silicon substrate 1 and the mold pattern 5.

  More specifically, for example, a coating resin (for example, a negative resist) that is a material of the flow path forming member 6 is applied onto the mold pattern 5 by a spin coat method, a direct coat method, a spray method, or the like. Then, the flow path forming member 6 having the ink discharge ports 7 is formed by exposing and developing the coating resin.

  Next, as shown in FIG. 1 (e), a second non-through hole 2 b is formed on the back surface (second surface) of the silicon substrate 1. The second non-through hole 2b has a function as a leading hole, and an etching solution in a later process enters the second non-through hole 2b.

  The means for forming the second non-through hole 2b may be the same as or different from the means for forming the first non-through hole 2a formed on the surface. The place where the second non-through hole 2b is formed is preferably formed at a position different from the first non-through hole 2a formed from the surface of the silicon substrate 1 in the substrate surface direction. The depth of the second non-through hole 2b is preferably formed to a depth in the range of 50% to 98% with respect to the thickness of the substrate. Moreover, it is preferable that the depth of the first non-through hole 2 a and the depth of the second non-through hole 2 b overlap with each other in the range of 10% to 96% with respect to the thickness of the silicon substrate 1.

  Next, as shown in FIG. 1F, an ink supply port 8 as a through hole is formed in the silicon substrate 1 by performing an etching process from the back surface of the silicon substrate 1.

  In this etching process, the etching proceeds from the second surface and the second non-through hole 2b and reaches the first non-through hole 2a. And the solid particle with which the 1st non-through-hole 2a was filled melt | dissolves in etching liquid, and also advances etching. The ink supply port is formed in a region including the first non-through hole and the second non-through hole.

  As the etching treatment, anisotropic etching using an etchant made of a strong alkali solution such as tetramethylammonium hydroxide (TMAH), potassium hydroxide (KOH), or sodium hydroxide (NaOH) can be used. In addition, these solutions may be used alone, or two or more kinds of liquids may be mixed and one or more kinds of additives may be added to improve the etching rate. Furthermore, the etching solution is desirably heated to 40 ° C. or higher and 100 ° C. or lower, more preferably 70 ° C. or higher and 95 ° C. or lower in order to further improve the etching rate. Thereby, the solid particles 4 filled in the first non-through holes 2a are easily dissolved in the etching solution, and the etching time can be shortened because the etching solution enters the first non-through holes 2a. .

  Next, as shown in FIG. 1G, the mold pattern 5 is dissolved and removed.

  More specifically, for example, the mold pattern 5 is removed from the silicon substrate 1 by immersing the silicon substrate 1 in a solvent such as methyl lactate, cyclohexanone, or acetone in which the mold pattern 5 is dissolved. The silicon substrate may be processed batchwise with the solvent stored in a container, or may be processed continuously with the solvent always flowing. The temperature of the solvent is preferably higher than room temperature in order to improve the removability of the mold pattern 5, and is preferably lower than the flash point of the solvent from the viewpoint of safety.

  As a result, as shown in FIG. 1, an ink jet recording head substrate 1 having a flow path forming member having an ink discharge port and an ink flow path and a substrate having an ink supply port 8 is obtained. The inkjet recording head substrate 1 was cut and separated into chips by a laser sorter, a dicing sorter, or the like, and electric wiring for driving the energy generating elements 10 was joined to each chip. Subsequently, an ink jet recording head can be manufactured by bonding a chip tank member for supplying ink.

  FIG. 2 is a process cross-sectional view for explaining the method of manufacturing the ink jet recording head substrate of this embodiment.

  In the form shown in FIG. 2, the protective film 9 is formed on the surface of the silicon substrate 1 on which the ejection energy generating element 10 is formed before the first non-through hole 2a is formed. The material of the protective film 9 can be processed at the same time when the non-through hole 2a is formed in the silicon substrate 1, and is preferably easily removed. For example, rubber-based resin, polyvinyl alcohol, protech and the like can be mentioned. As the rubber resin, a cyclized rubber resin is preferable.

  The first non-through hole 2a is formed through the protective film 9 with a laser beam or the like. The filling of the solid particles can be carried out by the above-described method, and is not particularly limited. For example, the solid particles 4 are formed by polishing and flattening the first surface by chemical mechanical polishing using the solid particles. One unthrough-hole 2a can be filled. In this embodiment, as shown in FIGS. 2C and 2D, even if solid particles and debris 3 remain on the first surface, they can be easily removed by removing the protective film 9. be able to.

  About the post-process after removing the protective film 9, an ink jet recording head substrate can be manufactured by the same method as that shown in FIG.

Example 1
An example of a method for manufacturing an ink jet recording head substrate according to this embodiment will be described with reference to FIG.

  First, as shown in FIG. 1A, a YAG laser triple wave (THG: wavelength 355 nm) is formed on the surface of a silicon substrate 1 having a thickness of 725 μm, on which a discharge energy generating element 10 has been previously formed on the first surface side. ) Was used to form a first non-through hole 2a having a diameter of 25 μm and a depth of 650 μm.

  Next, as shown in FIG. 1B, the surface of the silicon substrate 1 is polished with a polishing solution by chemical mechanical polishing to remove the debris 3a generated by the laser light irradiation, The solid particles 4 used for polishing were filled in the through holes 2a. As the solid particles 4, alumina particles having a volume average particle diameter of 1 μm were used.

  Thereafter, an aromatic polyamide-based resin was applied by spin coating, and patterning was performed using a positive resist as a mask to form an adhesion layer.

  Next, as shown in FIG. 1C, a resin composition in which polymethylisopropenyl ketone (PMIPK), which is a positive resist, is dissolved in a cyclohexanone solvent is used as a soluble material, and the resin composition is spun. It apply | coated on the silicon substrate 1 by the coating method. Subsequently, after evaporating cyclohexanone as a solvent to form a PMIPK film, the mold pattern 5 having a desired flow path pattern is formed by exposing and developing the resin layer 5 by irradiating ultraviolet light with an exposure device. Formed.

  Next, as shown in FIG. 1D, a coating resin was applied on the mold pattern 5 and the silicon substrate 1 by a spin coating method. As the coating resin, a resin composition in which an epoxy resin as a negative resist and a photocationic polymerization catalyst were dissolved in a xylene solvent was used. Thereafter, xylene as a solvent was evaporated to form a coating resin, and then exposure and development with a stepper were performed to form a flow path forming member 6 having high-precision ink discharge ports 7.

  Next, as shown in FIG.1 (e), the back surface of the silicon substrate 1 was irradiated with the laser beam, and the 2nd non-through-hole 2b with a depth of 650 micrometers was formed.

  Next, as shown in FIG. 1 (f), an anisotropic etching process was performed from the back surface of the silicon substrate 1 using an aqueous solution of 22% by mass of TMAH heated to 83 ° C. to form an ink supply port 8. The time taken for the anisotropic etching process was 3 hours.

  Next, as shown in FIG. 1 (g), the silicon substrate 1 was immersed in methyl lactate at 40 ° C., and the mold pattern 5 was eluted from the ink supply port 8.

  Through the above-described steps, an ink jet recording head substrate on which nozzles for discharging ink flowing from the ink supply port 8 from the ink discharge port 7 are formed. The flatness of the surface (orifice surface) of this ink jet recording head substrate was ± 5%.

  Then, the substrate is cut and separated into chips by a dicing sorter, electrical wiring for driving the ejection energy generating element 10 is joined to each chip, and then a chip tank member for ink supply is joined to perform ink jet recording. A head was produced. As a result of printing with this ink jet recording head, good printing results were obtained.

(Example 2)
Another example of the method for manufacturing the ink jet recording head substrate of this embodiment will be described with reference to FIG.

  First, a cyclized rubber-based resin was applied as a protective film 9 on the surface of the silicon substrate 1 on which the ejection energy generating element 10 was formed by a spin coating method. Next, the first non-through hole 2a having a diameter of about 25 μm was formed by penetrating the protective film 9 and using a laser beam of a third harmonic of a YAG laser (THG: wavelength 355 nm). Thereafter, solid particles 4 which are alumina particles having a volume average particle diameter of 1 μm were filled in the first non-through holes 2a using a chemical mechanical polishing apparatus. Subsequently, the debris 3 and the solid particles 4 on the surface were removed together with the protective film 9. Thereafter, an ink jet recording head substrate was produced in the same manner as in Example 1. The time required for anisotropic etching was 3 hours, and the flatness of the surface of the ink jet recording head substrate was ± 5%.

  Then, the substrate is cut and separated into chips by a dicing sorter, electrical wiring for driving the ejection energy generating element 10 is joined to each chip, and then a chip tank member for ink supply is joined to perform ink jet recording. A head was produced. As a result of printing with this ink jet recording head, good printing results were obtained.

(Comparative Example 1)
Inkjet recording is performed in the same manner as in Example 1 except that the surface of the silicon substrate 1 is irradiated with laser light to form the first non-through hole 2a, and then the mold pattern 5 is formed without filling the solid particles. A head substrate was manufactured. As a result of the evaluation, the time required for anisotropic etching was 3 hours. However, the thicknesses of the mold pattern 5 and the flow path forming member 6 varied, and the flatness of the surface of the inkjet recording head substrate was ± 15. %Met.

(Comparative Example 2)
An ink jet recording head substrate was produced in the same manner as in Example 1 except that zirconia oxide particles that were not alkali-soluble were used as the solid particles 4. As a result of the evaluation, anisotropic etching took 5 hours, and the flatness of the surface of the inkjet recording head substrate was ± 5%, but the solid particles 4 adhered to the ink discharge ports 7, Yield increased.

DESCRIPTION OF SYMBOLS 1 Silicon substrate 2a 1st non-through-hole 2b 2nd non-through-hole 3 Debris 4 Solid particle 5 Type pattern 6 Flow path formation member 7 Liquid discharge port (ink discharge port)
8 Liquid supply port (ink supply port)
9 Protective film 10 Discharge energy generating element

Claims (11)

A method of processing a silicon substrate, wherein a through hole is formed using an etchant in a silicon substrate having a first surface and a second surface opposite to the first surface,
Forming a first non-through hole in the first surface of the silicon substrate;
Filling the first non-through holes with solid particles dissolved in the etching solution;
Forming a second non-through hole in the second surface of the silicon substrate;
The silicon substrate on which the first non-through hole and the second non-through hole filled with the solid particles are formed is etched from the second surface using the etchant, thereby allowing the penetration. Forming a hole;
A method for processing a silicon substrate, comprising:   The method for processing a silicon substrate according to claim 1, wherein the solid particles are filled into the first non-through holes while the first surface of the silicon substrate is polished and planarized using the solid particles. The first non-through hole is formed through a protective film formed on the first surface of the silicon substrate,
The method for processing a silicon substrate according to claim 1, wherein the protective film is removed after the solid particles are filled in the first non-through holes.   The method for processing a silicon substrate according to claim 1, wherein the first non-through hole is formed by laser light irradiation.   5. The method for processing a silicon substrate according to claim 1, wherein the first non-through hole is formed so as to penetrate a sacrificial layer provided on the first surface of the silicon substrate.   The method for processing a silicon substrate according to claim 1, wherein the filling of the solid particles is performed by filling the first non-through holes with a slurry containing the solid particles.   The method for processing a silicon substrate according to claim 6, further comprising a drying step after the slurry is filled into the first non-through hole.   The method for processing a silicon substrate according to claim 1, wherein the filling of the solid particles is performed under vacuum.   The method for processing a silicon substrate according to claim 1, wherein the solid particles are alkali-soluble.   The method for processing a silicon substrate according to claim 1, wherein the volume average particle size of the solid particles is 0.01 μm or more and 100 μm or less. A method for manufacturing a substrate for a liquid discharge head comprising a silicon substrate having a liquid supply port for supplying the liquid to a liquid flow path communicating with a discharge port for discharging liquid,
A method for manufacturing a substrate for a liquid discharge head, wherein the liquid supply port is formed by the silicon substrate processing method according to claim 1.

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