JP2014067773A - Silicon substrate etching method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silicon substrate etching method which can solve stagnation of an etchant and improve deterioration in an etching rate on a wafer surface by improving replaceability of the etchant.SOLUTION: In an etching method of a silicon substrate of forming an intended recess by fixing a chamber with a silicon substrate which has an etching mask layer on a first surface so as to expose the etching mask layer in the chamber and by etching the silicon substrate through the etching mask layer by an etchant flowing in the chamber from an upstream side to a downstream side, the etching mask layer includes an etching opening 2 corresponding to the recess and a dummy opening 3 on an upstream side of the etching opening and aligned with the etching opening.

Description

  The present invention relates to a silicon substrate etching method for etching a silicon substrate using an etchant.

  As the integration of semiconductor devices and the density of ink jet heads increase, wafer diameters have been increased. In the case of a 6-inch to 8-inch wafer, it was possible to simultaneously wet-etch a plurality of wafers even with a batch-type apparatus immersed in a bath filled with a heated etching solution. However, when a wafer exceeding 8 inches is etched, or when etching is performed with higher accuracy even at 6 inches or 8 inches, it is required to use a single wafer type apparatus.

  Patent Document 1 discloses a single wafer type apparatus having a structure in which an etching solution continuously flows on a wafer surface while forming a laminar flow state in parallel with the surface of a semiconductor wafer.

JP-A-6-349800

  In the conventional configuration, in order not to leak the etching solution, a stagnation such as a decrease in flow rate has occurred in the etching solution flowing from the upstream side by a seal member provided on the outer peripheral portion of the wafer. Although stagnation occurs depending on conditions such as the speed of the etching solution, it has occurred particularly near the seal member (near the outer periphery of the wafer). Then, due to the stagnation that occurs, there is a portion where the substituting property of the etching solution is lowered on the wafer, and the etching rate on the wafer surface may be lowered.

  Accordingly, the present invention provides a method for etching a silicon substrate that can improve the stagnation of the etching solution and improve the substitution property of the etching solution, thereby improving the decrease in the etching rate on the wafer surface. Objective.

Therefore, the present invention provides
A chamber and a silicon substrate having an etching mask layer on a first surface are fixed so that the etching mask layer is exposed in the chamber, and the etching mask is removed by an etching solution flowing from the upstream side to the downstream side in the chamber. A silicon substrate etching method for forming a target recess by etching the silicon substrate via:
The etching mask layer has an etching opening corresponding to the recess, and a dummy opening arranged upstream of the etching opening and arranged with the etching opening.

  According to the configuration of the present invention, there is provided a silicon substrate etching method capable of improving the stagnation generated in the etching solution and improving the substitution property of the etching solution, thereby improving the decrease in the etching rate on the wafer surface. can do.

  In particular, according to the preferred configuration of the present invention, it is possible to improve the lowering of the etching rate that occurs in the vicinity of the outer periphery of the wafer by improving the substituting property of the etching solution in which the stagnation such as a decrease in the flow velocity occurs in the outer peripheral portion of the wafer. This makes it possible to make the etching rate different in the wafer surface uniform and perform etching with an accurate opening width.

It is a schematic diagram which shows the structural example of the single wafer type wet etching apparatus which can be used by this embodiment. It is a schematic diagram which shows an example of the silicon substrate in the conventional manufacturing method. It is a schematic diagram which shows an example of the silicon substrate in this embodiment. It is the schematic diagram and graph which show the etching rate distribution of the silicon substrate in the conventional manufacturing method. It is the schematic diagram and graph which show the etching rate distribution of the silicon substrate in this embodiment. It is typical sectional drawing which shows the process example of the etching method of the silicon substrate in this embodiment. It is typical sectional drawing which shows the process example of the etching method of the silicon substrate in this embodiment.

(Embodiment)
Hereinafter, embodiments of the present invention will be described with reference to the drawings. Hereinafter, the present embodiment will be described by taking a liquid discharge head as an example, but the present invention is not limited to this embodiment.

  FIG. 1A is a schematic diagram illustrating a configuration example of a chamber of a single wafer wet etching apparatus according to the present embodiment. FIG.1 (b) is a schematic diagram which shows the state seen from the A direction in Fig.1 (a). FIG.1 (c) is an enlarged view of the part enclosed by the dotted line B in FIG.1 (b). FIG. 1D is a cross-sectional view taken along a dotted line a-a ′ in FIG. FIG. 1E is a cross-sectional view taken along a dotted line b-b ′ in FIG.

  In FIG. 1A, a wet etching apparatus 8 has a chamber 4 having a flow path inside. The silicon substrate 1 is fixed to the chamber 4. The silicon substrate 1 is supported by a support member 5, and the support member 5 receives a stress that presses the silicon substrate against the chamber 4 by an air cylinder 6. The direction of the arrow indicates the direction in which the etching solution flows, and the etching solution flows from the upstream side (lower side in FIG. 1A) to the downstream side (upper side in FIG. 1A).

  An etching mask layer (not shown) is provided on the surface of the silicon substrate. The silicon substrate 1 is provided with a seal member 10 so that the etching mask layer is exposed in the chamber 4, that is, in the etching solution flow path 7. It is fixed to the chamber 4 in a liquid-tight manner. The etching mask layer is provided with an etching opening corresponding to a target recess (in this embodiment, a liquid supply port) and a dummy opening arranged upstream of the etching opening and arranged with the etching opening.

  The seal member 10 may be disposed as a part of the configuration of the wet etching apparatus, or may be disposed as a separate member.

  In the wet etching apparatus 8, the etching liquid flows on the surface of the silicon substrate 1, so that the silicon substrate 1 is etched to form a target recess (liquid supply port in the present embodiment) on the silicon substrate surface. In addition, in order to eliminate the need to cover the non-etched surface with a protective layer or the like, it is desirable that only one surface of the silicon substrate 1 be in contact with the etching solution.

  Further, in the present embodiment, it is preferable that the silicon substrate and the chamber are disposed in a liquid-tight manner using a seal member, and the seal member is not particularly limited, but for example, an O-ring, rubber, or the like. An elastic member, an adhesive material, or the like can be used. The seal member is disposed near the outer periphery of the silicon substrate.

  The wet etching apparatus 8 may be an open type or a closed type, but is preferably a closed structure from the viewpoint of heat retention and safety.

  The silicon substrate 1 may be set in the apparatus such that the substrate surface is perpendicular to the horizontal direction, or may be set in the apparatus so that the substrate surface is in the horizontal direction, or the substrate surface is inclined. You may set to an apparatus so that it may incline. However, when an etching solution that generates bubbles from the silicon substrate 1 during etching is used, the substrate surface of the silicon substrate 1 is set in a vertical direction or an oblique direction with respect to the horizontal direction in consideration of ease of bubble removal. It is desirable to set it in the apparatus.

  As shown in FIGS. 1A, 1D, and 1E, an etching solution flows from an upstream side to a downstream side in a region (flow path 7) surrounded by a silicon substrate 1, such as a wafer, a chamber 4, and a seal member 10. It flows toward.

  The etching solution used for the etching treatment of the silicon substrate 1 is not particularly limited. For example, a strong alkali such as tetramethylammonium hydroxide (TMAH), potassium hydroxide (KOH), or sodium hydroxide (NaOH) is used. A solution can be used. Moreover, you may use an etching liquid individually by 1 type or in mixture of 2 or more types. In order to improve the etching rate, one or more kinds of additives may be added to the etching solution. Furthermore, in order to further improve the etching rate, the temperature of the etching solution is preferably adjusted to 40 ° C. or higher and 98 ° C. or lower, more preferably 70 ° C. or higher and 95 ° C. or lower.

  Next, the etching opening 2 and the dummy opening 3 will be described in detail with reference to FIGS.

  2 and 3 are schematic plan views showing the side of the silicon substrate 1 on which the etching mask layer is provided. 4 (a) and 5 (a) are enlarged views of a part of the silicon substrate, and FIGS. 4 (b) and 5 (b) are silicon substrates in FIGS. 4 (a) and 5 (a). 1 is a graph showing a change in flow velocity in the vicinity of 1 AA ′.

  FIG. 2 is a view showing an arrangement example of the etching openings 102 when forming the liquid supply port in the conventional manufacturing method. FIG. 3 is a view showing an arrangement example of the etching opening 2 and the dummy opening 3 when forming the liquid supply port in the present embodiment.

  Conventionally, as shown in FIG. 2, a plurality of etching openings 102 are arranged in parallel. On the other hand, in the present embodiment, as shown in FIG. 3, the dummy is located at a position upstream of the target etching opening 2 arranged in the silicon substrate (on the etching mask layer) and close to the seal member. An opening 3 is provided. Unlike the etching opening 2 for forming a target recess (liquid supply port in the present embodiment), the dummy opening 3 is formed with a concave shape not intended by the etching solution from the dummy opening 3. The dummy opening 3 is preferably provided at a position close to the seal member. This is because the position at which the stagnation of the etchant varies depending on the flow rate of the etchant, but is likely to occur particularly near the seal member.

  The etching opening and the dummy opening are preferably rectangular. Moreover, it is preferable that the width of the dummy opening in the longitudinal direction is the same as or larger than the width of the etching opening in the longitudinal direction. Moreover, it is preferable that the etching opening and the dummy opening are formed in parallel in a direction parallel to the flowing direction of the etching solution.

  In the figure, the etching opening 2 and the dummy opening 3 are arranged so that their longitudinal directions are maintained in a direction perpendicular to the direction in which the etching solution flows. In other words, the silicon substrate 1 is disposed in the chamber 4 so that the longitudinal directions of the etching opening 2 and the dummy opening 3 are perpendicular to the direction in which the etching solution flows.

  A plurality of rectangular etching openings are arranged in parallel on the wafer. Further, in adjacent etching openings, a plurality of etching openings are arranged in a row so that the ends in the longitudinal direction are close to each other, and a dummy opening is provided on the most upstream side of the row.

  Since the dummy opening 3 is not provided in the conventional form of FIG. 4A, the flow velocity decreases (stagnation) near the seal member. That is, stagnation is caused by a step between the chamber and the silicon substrate. More specifically, a stagnation occurs near the step due to a step existing between the inner wall of the chamber and the silicon substrate surface. On the other hand, in this embodiment shown in FIG. 5 (a), since the dummy opening 3 is provided, as shown in FIG. 5 (b), there is no reduction or improvement in the flow velocity (stagnation) in the vicinity of the seal member. Yes.

  The silicon substrate may be arranged in the chamber so that the longitudinal direction of the etching opening 2 is perpendicular to the flow of the etching solution, or may be arranged in parallel. However, as described above, it is preferable to arrange the etching opening 2 so that the longitudinal direction thereof is perpendicular to the flow of the etching solution.

  The shape of the etching opening 2 is not particularly limited, and examples thereof include a rectangular shape, a square shape, a circular shape, and an elliptical shape. The shape of the etching opening 2 is particularly preferably rectangular.

  Further, the shape of the dummy opening 3 arranged on the upstream side of the etching opening 2 is not particularly limited, and may be the same shape as the etching opening 2 or may be a different shape. However, from the viewpoint of the stagnation improvement effect, it is preferable that the shape be wider in the direction perpendicular to the direction in which the etching solution flows than in the etching opening. For example, when the shape of the etching opening 2 is rectangular, the width in the longitudinal direction of the etching opening 2 is, for example, 10 to 40 mm, and the width in the lateral direction is, for example, 0.2 to 2.0 mm. Moreover, when the shape of the dummy opening 3 is a rectangular shape, the width in the longitudinal direction is, for example, 11 to 60 mm, and is preferably 1.1 to 1.5 times the width in the longitudinal direction of the etching opening 2. . When the shape of the dummy opening 3 is rectangular, the width in the short direction is, for example, 0.2 to 2.0 mm.

  The target recess is formed from the etching opening 2 through the silicon substrate 1, but the target recess shape is formed from the silicon substrate surface exposed to the dummy opening 3. In order not to reduce the strength of the silicon substrate 1, it is desirable to form the dummy openings 3 so that the concave shape does not penetrate the silicon substrate 1, as shown in FIG. 6 corresponds to the A-A ′ cross section of FIG. 5. More specifically, as shown in FIG. 6C, an etching mask layer 11 having a dummy opening 3 and an etching opening 2 is formed on the back surface (lower surface in the drawing) of the silicon substrate. The dummy opening 3 is formed so as to be located near the outer periphery of the silicon substrate rather than the etching opening 2. The dummy opening 3 is shaped such that the concave shape formed from the dummy opening 3 does not penetrate through the substrate in the subsequent crystal anisotropic etching. Subsequently, as shown in FIG. 6D, a flow path forming member having a liquid flow path 13 and a liquid discharge port communicating with the liquid flow path is formed on the surface (upper surface in the drawing) of the silicon substrate. Subsequently, as shown in FIGS. 6E and 6F, the liquid supply port 20 (target recess) is formed by performing crystal anisotropic etching from the back side of the silicon substrate. Further, a concave shape 30 that is not intended from the dummy opening 3 is formed so as not to penetrate the substrate. During the etching, the etching opening 2 is arranged so that the longitudinal direction thereof is perpendicular to the flow of the etching solution. Further, the silicon substrate is fixed to the chamber 4 so that the dummy opening 3 is positioned upstream of the etching opening 2 from the etching opening 2.

  Further, as one method for etching so that the concave shape formed from the dummy opening 3 does not penetrate the substrate, there is a method as shown in FIG. In the method shown in FIG. 7, the leading hole 14 is formed on the etching start surface exposed to the etching opening 2 using a laser, and the leading hole is not formed on the silicon substrate surface exposed to the dummy opening 3.

  The present embodiment is preferably applicable to a method for manufacturing a liquid discharge head having a liquid discharge port, a liquid flow channel communicating with the liquid discharge port, and a liquid supply port for supplying liquid to the liquid flow channel. It is. At this time, the liquid supply port can be formed as a target recess.

Example 1
An example of the silicon substrate etching method of this embodiment will be described with reference to FIG.

  First, HIMAL-1200CH (trade name: manufactured by Hitachi Chemical Co., Ltd.) is applied as an etching mask layer 11 to the surface to be etched of the silicon substrate 1 (also referred to as the lower surface or the second surface in the drawing) by spin coating. Applied. Thereafter, a positive resist THMR-iP5700 (trade name: manufactured by Tokyo Ohka Kogyo Co., Ltd.) was applied onto the etching mask layer 11 by a spin coating method to form a resist layer 12 (FIG. 6B).

  Subsequently, the resist layer 12 was exposed by irradiating ultraviolet light with an exposure apparatus, and further developed, thereby forming an etching pattern corresponding to the etching opening and a dummy pattern corresponding to the dummy opening on the etching mask layer 11. . Next, the etching mask layer 11 was dry-etched using the resist layer 12 as a mask, and an etching opening 2 and a dummy opening 3 were formed in the etching mask 11. At this time, the dummy opening 3 was formed with a smaller width than the etching opening 2. Thereafter, the resist layer 12 which became unnecessary was removed (FIG. 6C).

  Next, on the surface opposite to the etching surface (also referred to as the upper surface or the first surface in the drawing), the flow path forming member constituting the ink flow path 13 and the ejection port was formed (FIG. 6D). .

  Thereafter, the silicon substrate 1 is sandwiched between the chamber 4 and the support member 5 and the support member 5 is pressurized by the air cylinder 6, and sealed with an O-ring (not shown) resistant to the etching solution so as not to leak. Then, the silicon substrate was set in the etching apparatus 8 (see FIG. 1A). Then, an etching solution was supplied into the chamber from below the chamber 4 and only one surface of the silicon substrate 1 was wet-etched. An aqueous solution of 22 parts by weight of TMAH was used as an etching solution. Further, the etching solution flowing out from the chamber 4 was received in an overflow tank (not shown). Then, a heating heater (not shown) is placed in the overflow tank to keep the etching solution at 83 ° C., and the etching solution is always supplied into the chamber 4 by a circulation pump (not shown). Etching was performed. By the wet etching, the liquid supply port 20 was formed from the etching opening 2, and the concave shape 30 not penetrating from the dummy opening 3 was formed (FIGS. 6E and 6F).

  Finally, the etching mask layer 11 was removed to obtain a silicon substrate having a liquid supply port as a target recess.

  As a result of etching the silicon substrate by the above method, the stagnation of the etchant flowing near the periphery of the silicon substrate was reduced, and the etching uniformity was improved.

(Example 2)
In this example, the wet etching was performed after the lead hole was formed on the silicon substrate surface exposed to the etching opening 2 by laser. The laser for providing the leading hole was a third harmonic of a YAG laser (wavelength 355 nm), and the conditions were a frequency of 100 kHz and an output of 10 W. Note that the laser was not applied to the silicon substrate surface exposed to the dummy opening (FIG. 7E).
Thereafter, as in Example 1, a silicon substrate was set in the etching apparatus 8 and wet etching was performed. Finally, the etching mask layer 11 was removed to obtain a silicon substrate having a liquid supply port as a target recess.

  As a result of etching the silicon substrate by the above method, the stagnation of the etchant flowing near the periphery of the silicon substrate was reduced, and the etching uniformity was improved.

1: Silicon substrate 2: Etching opening 3: Dummy opening 4: Chamber 5: Support member 6: Air cylinder 7: Etching solution 8: Etching apparatus 10: Seal member

Claims (12)

A chamber and a silicon substrate having an etching mask layer on a first surface are fixed so that the etching mask layer is exposed in the chamber, and the etching mask is removed by an etching solution flowing from the upstream side to the downstream side in the chamber. A silicon substrate etching method for forming a target recess by etching the silicon substrate via:
The method of etching a silicon substrate, wherein the etching mask layer includes an etching opening corresponding to the recess, and a dummy opening arranged upstream of the etching opening and arranged with the etching opening.   The method for etching a silicon substrate according to claim 1, wherein a concave shape formed by etching with the etching solution from the dummy opening does not penetrate the silicon substrate.   The method for etching a silicon substrate according to claim 1, wherein the chamber and the silicon substrate are fixed via a seal member.   The method for etching a silicon substrate according to claim 3, wherein the dummy opening is formed at a position upstream of the etching opening and close to the seal member.   The method for etching a silicon substrate according to claim 1, wherein the etching opening and the dummy opening have a rectangular shape.   6. The method of etching a silicon substrate according to claim 5, wherein the etching opening and the dummy opening are formed in parallel in a direction parallel to the direction in which the etching solution flows.   The method for etching a silicon substrate according to claim 5 or 6, wherein a width in the longitudinal direction of the dummy opening is the same as or larger than a width in the longitudinal direction of the etching opening.   8. The silicon substrate according to claim 5, wherein the silicon substrate is disposed in the chamber such that a longitudinal direction of the etching opening and the dummy opening is a direction perpendicular to a direction in which the etching solution flows. Etching method.   9. The method of etching a silicon substrate according to claim 1, wherein a plurality of the etching openings are arranged in the etching mask layer.   The silicon substrate etching method according to claim 1, wherein the recess penetrates the silicon substrate.   The method for etching a silicon substrate according to claim 1, wherein the etching of the silicon substrate is crystal anisotropic etching. A method for manufacturing a liquid ejection head, comprising: a liquid ejection port; a liquid channel communicating with the liquid ejection port; and a liquid supply port for supplying liquid to the liquid channel,
A method for manufacturing a liquid discharge head, wherein the liquid supply port is formed as the concave portion by using the method for etching a silicon substrate according to claim 1.

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