JP2016043447A - Manufacturing method of mems structure and mems structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of an MEMS structure and the MEMS structure capable of performing separation of a support substrate from a wafer in a short time and suppressing a cost.SOLUTION: A manufacturing method of an MEMS structure includes: a first process for forming an etching stopper layer on a mother substrate; a second process for forming a first opening pattern on the etching stopper layer; a third process for forming a plurality of device layers on the etching stopper layer; a fourth process for establishing a support substrate; a fifth process for forming a second opening pattern which exposes an adhesive layer on a position corresponding to the first opening pattern from a second surface opposite to a first surface of a mother substrate; and a sixth process for etching the adhesive layer to separate the support substrate from the second opening pattern according to a wet-etching method. Therein, the first opening pattern corresponds to a dicing line and the mother substrate is divided into a plurality of pieces by the second opening pattern.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a method for manufacturing a MEMS structure and a MEMS structure.

  2. Description of the Related Art In recent years, devices such as ultra-small vibrators and sensors have been formed using MEMS (Micro Electro Mechanical Systems) technology. In manufacturing such a device, the wafer has been thinned, and a process for supporting the thinned wafer with a support substrate has been developed. In such a support process, the thinned device wafer is temporarily fixed on the support substrate, and after the necessary processing is performed on the device wafer, the support substrate is peeled off from the device wafer.

  When peeling off the support substrate, it is important to reduce physical damage to the device wafer. Therefore, a method of peeling off by a wet process is generally adopted.

  When the device wafer is separated after the support substrate is peeled off, a dicing apparatus such as laser dicing or stealth dicing as shown in Patent Document 1 and Patent Document 2 is used.

JP 2012-156217 A JP 2011-256409 A

As described above, when the wet process method is used as a method of peeling the support substrate from the device wafer, if the device wafer and the support substrate are peeled from the bonding side surface, the laminated structure is put into the peeling solution for a long time. It is necessary to immerse. For this reason, there is a demand for a method capable of peeling in a short time.
Further, since dicing apparatuses such as laser dicing and stealth dicing are expensive, a method that can be manufactured at low cost is required.

  The present invention has been made in view of the above problems, and can provide a method for manufacturing a MEMS structure and a MEMS structure that can peel a support substrate from a wafer in a short time and reduce costs. .

  One method of manufacturing a MEMS structure according to the present invention includes a first step of forming an etching stopper layer on a first surface of a mother substrate, and a first opening pattern exposing a part of the first surface. A second step of forming a stopper layer, a third step of forming a plurality of device layers on the remaining etching stopper layer, and a support substrate on the first surface side through an adhesive layer A fourth step and a fifth step of forming a second opening pattern exposing the adhesive layer at a position corresponding to the first opening pattern from a second surface of the mother substrate facing the first surface. And a sixth step of etching the adhesive layer from the second opening pattern and peeling the support substrate by a wet etching method, and the first opening pattern corresponds to a dicing line. The mother substrate by the second opening pattern is characterized in that it is divided into a plurality of pieces.

According to this manufacturing method, when the support substrate is peeled off by the wet etching method, the support substrate and the mother substrate are bonded together through the second opening pattern formed in the mother substrate and the first opening pattern formed in the etching stopper layer. The adhesive layer can be efficiently dissolved. Thereby, it becomes possible to peel the support substrate from the mother substrate in a short time.
In addition, since the mother substrate is divided into a plurality of pieces simultaneously with the peeling of the support substrate, the dicing process can be omitted. Therefore, it is excellent in productivity and a MEMS structure can be manufactured at low cost.

  In the method for manufacturing a single MEMS structure, any one of the plurality of device layers is preferably formed on each of the plurality of pieces.

  According to this manufacturing method, a plurality of MEMS structures are obtained.

  In the method for manufacturing a single MEMS structure, in the fifth step, a third opening pattern that exposes the etching stopper layer at a position corresponding to each of the plurality of device layers may be formed.

  According to this manufacturing method, the manufacturing process can be shortened by simultaneously forming the second opening pattern and the third opening pattern in the fifth process.

  In the method for manufacturing a single MEMS structure, the first opening pattern may be formed so that corners of the plurality of pieces are rounded.

  According to this manufacturing method, the stress applied to the corners in the laminated structure on the etching stopper layer can be relaxed. As a result, the adhesion between the mask used when forming the second opening pattern corresponding to the first opening pattern of the etching stopper layer on the mother substrate and the mother substrate is improved, and peeling or the like can be prevented.

  One MEMS structure according to the present invention includes a semiconductor substrate, a first layer formed on a first surface of the semiconductor substrate, and a device layer formed on the first layer, The semiconductor substrate has a penetrating portion from the second surface facing the first surface to the first layer at a position where the device layer is formed. The corners of the first layer and the corners of the semiconductor substrate are rounded.

  According to this configuration, since the stress such as the laminated structure at the corners of the semiconductor substrate can be relaxed during manufacturing, a highly reliable MEMS structure can be obtained.

  In the one MEMS structure described above, it is preferable that the first layer functions as a diaphragm.

  According to this configuration, by causing the first layer to function as a diaphragm, the number of components is reduced, and the MEMS structure can be obtained at low cost.

The perspective view which shows schematic structure of the MEMS structure of one Embodiment which concerns on this invention in a partial cross section. The top view which shows schematic structure of a MEMS structure. The fragmentary sectional view which shows schematic structure of a device layer. The figure which shows the flow of the manufacturing method of the MEMS structure in 1st Embodiment. Process drawing which shows the manufacturing method of the MEMS structure in 1st Embodiment. Process drawing which shows the manufacturing method of the MEMS structure in 1st Embodiment. Process drawing which shows the manufacturing method of the MEMS structure in 1st Embodiment. The top view which shows the dicing line and etching stopper layer of the silicon mother board | substrate in 1st Embodiment. Process drawing which shows the manufacturing method of the MEMS structure of 2nd Embodiment. The top view which shows the dicing line and etching stopper layer of the silicon mother board | substrate in 2nd Embodiment.

  Embodiments of the present invention will be described below with reference to the drawings. In each drawing used for the following description, the scale of each member is appropriately changed to make each member a recognizable size.

(MEMS structure)
FIG. 1 is a perspective view showing a schematic configuration of a MEMS structure 1 according to an embodiment of the present invention in a partial cross section. FIG. 2 is a plan view showing a schematic configuration of the MEMS structure 1. FIG. 3 is a partial cross-sectional view showing a schematic configuration of the device layer 4.

  As illustrated in FIG. 1, the MEMS structure 1 includes at least a silicon substrate 2 as a semiconductor substrate, an etching stopper layer (first layer) 3, and a device layer 4. The MEMS structure 1 is formed by MEMS technology.

  The silicon substrate (semiconductor substrate) 2 is a thin plate-like member formed from single crystal silicon. The thickness of the thin silicon substrate 2 is, for example, 100 μm or less. As shown in FIG. 2, the four corners 2q in the plan view of the silicon substrate 2 are rounded.

  As shown in FIG. 1, the silicon substrate 2 has an opening (penetrating portion) 2 </ b> A penetrating in the thickness direction of the silicon substrate 2. The opening 2A corresponds to the third opening pattern of the present invention. The opening 2 </ b> A is formed at a position corresponding to the device layer 4 in the center of the silicon substrate 2, and opens on the second surface 12 b side of the silicon substrate 2.

  The etching stopper layer 3 is formed on the first surface 12 a of the silicon substrate 2. As shown in FIG. 2, the four corners 3q in the plan view of the etching stopper layer 3 are also rounded.

  The etching stopper layer 3 functions as an etching stopper when the opening 2A is formed in the silicon substrate 2. The total film thickness of the etching stopper layer 3 is, for example, about 200 to 5000 nm.

  The etching stopper layer 3 is composed of a plurality or a single insulating film. As an example of the material for forming the etching stopper layer 3, an insulating material having high toughness such as titanium oxide, aluminum oxide, zirconium oxide, silicon nitride, silicon oxide, and stainless steel is used. In this embodiment, for example, the etching stopper layer 3 is formed using zirconium oxide.

  As an example, the device layer 4 is a so-called element body including a piezoelectric element 5 and wirings for driving the piezoelectric element 5 as shown in FIG.

  The piezoelectric element 5 includes a vibration plate 41, a lower electrode 42, a piezoelectric layer 43, and an upper electrode 44. In the present embodiment, a part of the etching stopper layer 3 described above that is exposed in the opening 2A of the silicon substrate 2 functions as the diaphragm 41 in particular.

  Examples of the material for forming the lower electrode 42 include nickel, iridium, gold, platinum, tungsten, titanium, palladium, silver, tantalum, molybdenum, chromium, a composite film of strontium and ruthenium, and a composite film of lanthanum and nickel. A selected conductive material is used. The film thickness of the lower electrode 42 is, for example, about 20 to 400 nm.

  As a material for forming the piezoelectric layer 43, for example, lead zirconate titanate (PZT) is used.

  As a material for forming the piezoelectric layer 43, other piezoelectric materials may be used. In the present embodiment, the piezoelectric layer 43 completely covers the lower electrode 42 under the upper electrode 44. This prevents a short circuit between the upper electrode 44 and the lower electrode 42 due to the action of the piezoelectric layer 43.

  As a material for forming the upper electrode 44, for example, nickel, iridium, gold, platinum, tungsten, titanium, palladium, silver, tantalum, molybdenum, chromium, a composite film of strontium and ruthenium, lanthanum and nickel, and the like. A conductive material selected from a composite film or the like is used. The film thickness of the upper electrode 44 is, for example, about 50 to 400 nm.

  The upper electrode 44 may use the same type of metal material as the lower electrode 42, or may use a different type of metal material from the lower electrode 42.

In the present embodiment, the configuration including the piezoelectric element 5 as an example of the device layer 4 has been described, but the configuration is not limited thereto.
The device layer 4 is a so-called element body composed of a vibrator, a sensor element, wirings and electrodes for driving them, and is not limited to the configuration of the device layer 4 described above, and may be of any structure, shape, and application Good.

  Next, a method for manufacturing the MEMS structure 1 as described above will be described.

[Method for Manufacturing MEMS Structure in First Embodiment]
FIG. 4 is a diagram illustrating a flow of a method for manufacturing the MEMS structure according to the first embodiment. 5 to 7 are process diagrams showing the method for manufacturing the MEMS structure according to the first embodiment. FIG. 8 is a plan view showing a dicing line L of the silicon mother substrate (mother substrate) 10, and shows an enlarged intersection portion of the dicing line L. FIG.

(Etching stopper layer 3 forming step: first step)
First, as shown in FIGS. 4 and 5A, an etching stopper layer (first layer) 3 is formed on the first surface 10a of the thin silicon mother substrate 10 (step S1). The etching stopper layer 3 functions as a stopper when etching the second surface 10b side of the silicon mother substrate 10 in a later process.

(Etching stopper layer 3 patterning step: second step)
Next, as shown in FIGS. 4 and 5B, photolithography and dry etching are performed on the etching stopper layer 3 to form the first opening pattern 13 corresponding to the dicing line L of the silicon mother substrate 10. (Step S2). Dry etching is terminated when the etching stopper layer 3 is penetrated.

  Thus, the etching stopper layer 3 existing on the dicing line L of the silicon mother substrate 10 is partially removed, and the first surface 10a of the silicon mother substrate 10 is exposed from the first opening pattern 13 formed thereby. Is done.

(Device layer 4 formation step: third step)
Next, as shown in FIGS. 4 and 5C, a plurality of device layers 4 are formed on the etching stopper layer 3 (step S3). The device layer 4 is arranged for each predetermined structure forming region R set on the silicon mother substrate 10. The plurality of structure forming regions R are regions partitioned by dicing lines L.

  In the present embodiment, as shown in FIG. 8, the first opening is formed so that the corner 3q of the etching stopper layer 3 remaining on the silicon mother substrate 10 is round in a plan view viewed from the normal direction of the silicon mother substrate 10. A pattern 13 is formed.

(Installation process of support substrate 15: fourth process)
Next, as shown in FIGS. 4 and 5D, the support substrate 15 is placed on the silicon mother substrate 10 via the adhesive layer 14 (step S4). The adhesive layer 14 is formed so as to cover the first surface 10 a of the silicon mother substrate 10 exposed from the first opening pattern 13, the etching stopper layer 3, and the device layer 4. The adhesive layer 14 is preferably resistant to a process for processing the second surface 10b side of the silicon mother substrate 10 and has a small stress change during the back surface processing process.

(Formation process of resist pattern M)
Next, as shown in FIGS. 4 and 6A, a resist pattern M is formed on the second surface 10b of the silicon mother substrate 10 (step S5). A dicing pattern opening h and a trench processing pattern opening g are formed in the resist pattern M, respectively. Each of the trench processing pattern openings g is formed for each structure forming region R on the silicon mother substrate 10.

  The trench processing pattern opening g has a size of 20 μm to several hundred μm, for example. For example, the dicing pattern opening h has a size of less than 20 μm.

(Patterning process of silicon mother substrate 10: fifth process)
Next, as shown in FIGS. 4 and 6B, photolithography using a photomask and dry etching are sequentially performed to pattern the silicon mother substrate 10 (step S6).

  In the trench processing pattern opening g, the etching process is stopped by the etching stopper layer 3, and an opening 2A as a third opening pattern is formed. In this way, a plurality of openings 2A that expose the etching stopper layer 3 at positions corresponding to the plurality of device layers 4 are formed.

  On the other hand, in the portion of the dicing pattern opening h, a second opening pattern 2B corresponding to the dicing line L is formed.

  The second opening pattern 2B is formed following the first opening pattern 13 formed in the etching stopper layer 3. The second opening pattern 2B communicates with the first opening pattern 13 of the etching stopper layer 3 to form one through groove. At least a part of the adhesive layer 14 is exposed from the second opening pattern 2 </ b> B and the first opening pattern 13.

  In this way, the opening 2A is formed together with the structure forming region R, and the second opening pattern 2B corresponding to the dicing line L is formed. By forming the plurality of openings 2A and the second opening pattern 2B in the same pattern process, the manufacturing process is shortened.

  As can be seen from FIG. 6B, the size of the opening is different between the trench processing pattern opening g and the dicing pattern opening h. For this reason, it is conceivable that the etching gas enters in different ways, and the etching rate differs between the openings g and h. That is, the pattern breakage progresses stepwise between the trench processing pattern opening g and the dicing pattern opening h.

  In order to relieve the stress at this time, in this embodiment, the corner portion Mq in the plan view of the dicing pattern opening h shown in FIG. 6B is changed to the corner portion 3q of the etching stopper layer 3 shown in FIG. It was formed in a round shape following the above.

  As a result, the stress generated at the corners of the stacked structure on the etching stopper layer 3 during the patterning of the silicon mother substrate 10 is relaxed. Therefore, the adhesiveness among the resist pattern M, the silicon mother substrate 10 and the etching stopper layer 3 is improved, and peeling or the like is prevented.

(Photomask removal process)
Next, as shown in FIGS. 4 and 6C, the resist pattern M on the second surface 10b of the silicon mother substrate 10 is removed by plasma ashing (step S7). At this time, since part of the adhesive layer 14 may be removed through the dicing pattern opening h, ashing conditions are set so that the adhesive layer 14 does not penetrate. By leaving the adhesive layer 14 on the dicing line L, the laminated structure can be held on the support substrate 15.

  The silicon mother substrate 10 from which the resist pattern M has been removed has a plurality of openings 2A formed for each structure forming region R and a second opening pattern 2B for dicing corresponding to the dicing line L. .

(Support substrate peeling step: sixth step)
Next, the support substrate 15 is peeled off by wet etching (step S8).
As shown in FIGS. 4 and 7A, the entire silicon mother substrate 10 is immersed in a peeling container 17 containing a peeling solution 16.

  At this time, the silicon mother substrate 10 may be immersed in the peeling container 17 in a state where the silicon mother substrate 10 is supported using a jig 50 as shown in FIG. The jig 50 has a plurality of receiving portions 51 on one surface.

  Each of the plurality of receiving portions 51 is inserted into each opening 2 </ b> A of the silicon mother substrate 10. The plurality of receiving portions 51 are formed by the mask having the reverse pattern of the trench processing pattern opening g described above.

  Note that the configuration of the jig 50 shown in FIG. 7A is an example, and the present invention is not limited to this.

  As the peeling solution 16, a conventionally known peeling solution that makes the adhesive layer 14 soluble can be appropriately selected and used according to the forming material of the adhesive layer 14 to be used.

  When the silicon mother substrate 10 is immersed in the stripping solution, the adhesive layer 14 touches the stripping solution 16 through the portion of the adhesive layer 14 that is not covered with the etching stopper layer 3, that is, the opening 13h of the etching stopper layer 3. The adhesive layer 14 dissolves. The support substrate 15 is peeled from the first surface 10 a of the silicon mother substrate 10 by dissolving the entire adhesive layer 14 in the peeling solution 16.

  In the present embodiment, each of the silicon substrates 2 separated from the silicon mother substrate 10 is separated at the same time when the support substrate 15 is peeled off. That is, each of the plurality of device structures 11 is separated and received by each receiving portion 51 of the jig 50 as shown in FIG. Thereby, it is possible to take out the plurality of device structures 11 at a time by pulling up the jig 50.

  A plurality of MEMS structures 1 as shown in FIG. 7C are thus completed.

  As described above, in this embodiment, the first opening pattern 13 corresponding to the dicing line L is formed in the etching stopper layer 3, and the second opening pattern 2B for dicing is formed in the silicon mother substrate 10. It was. Thereby, in the peeling process of the support substrate 15, the peeling solution 16 enters from the first opening pattern 13 and the second opening pattern 2 </ b> B, and the adhesive layer 14 that bonds the silicon mother substrate 10 and the support substrate 15 is efficiently used. Can be dissolved well.

  The region corresponding to the dicing line L in the surface of the adhesive layer 14 as well as the side surface of the adhesive layer 14 is exposed to the peeling solution 16 so that the adhesive layer 14 dissolves in a short time. That is, since the number of penetrations of the stripping solution 16 increases according to the number of dicing lines L in the vertical and horizontal directions, the peelability of the support substrate 15 can be improved as compared with the conventional stripping method in which only the side surface of the adhesive layer 14 is exposed to the stripping solution 16. Improves in each stage. Therefore, it is possible to peel the support substrate 15 from the silicon mother substrate 10 in a short time. In this way, productivity is improved because the immersion time in the peeling process is short.

  Further, according to the above manufacturing method, since the silicon mother substrate 10 is separated into pieces in the second opening pattern 2B at the same time when the support substrate 15 is peeled off, the subsequent dicing process is omitted. Can do. Thereby, an expensive dicing apparatus becomes unnecessary and mass production of the MEMS structure 1 can be performed at low cost.

[Method for Manufacturing MEMS Structure in Second Embodiment]
Next, a manufacturing method of the MEMS structure in the second embodiment will be described.
The basic steps of the manufacturing method in the present embodiment shown below are substantially the same as the manufacturing steps in the first embodiment, but are different in the processing steps of the etching stopper layer 3.

  Therefore, in the following description, the processing step of the etching stopper layer 3 and the subsequent manufacturing steps will be described in detail, and description of common portions will be omitted. Moreover, in each drawing used for description, the same code | symbol shall be attached | subjected to the same component as FIGS.

  FIG. 9 is a process diagram illustrating a method for manufacturing a MEMS structure according to the second embodiment. FIG. 10 is a plan view showing the dicing line L and the etching stopper layer 3 of the silicon mother substrate 10 in the second embodiment.

  First, as shown in FIG. 9A, a silicon mother substrate 10 having an etching stopper layer 30 and a plurality of device layers 4 formed on the first surface 10a is prepared.

  Next, as shown in FIG. 9B, a partial opening pattern 23 corresponding to the dicing line L of the silicon mother substrate 10 is formed in the etching stopper layer 30. The partial opening pattern 23 is formed along the dicing line L, and has a plurality of openings 23h and a plurality of connecting portions 23j.

As shown in FIGS. 9B and 10, the partial opening pattern 23 is formed so as to partially leave a part of the etching stopper layer 30 existing on the dicing line L.
That is, the etching stopper layer located on the dicing line L while leaving a part of the etching stopper layer 3 located on the dicing line L in the plane of the etching stopper layer 3 viewed from the normal direction of the silicon mother substrate 10. It is formed by removing a part of 3.

  By forming the partial opening pattern 23, the first surface 10a of the silicon mother substrate 10 along the dicing line L is partially exposed from the plurality of openings 23h.

  Thereafter, the patterning process of the silicon mother substrate 10 and the removal process of the resist pattern M are continuously performed.

  Next, the peeling process of the support substrate 15 is performed. In the peeling process of the support substrate 15, when the silicon mother substrate 10 is immersed in the peeling container 17 as shown in FIG. 9C, the peeling solution enters from the plurality of openings 23 h of the partial opening pattern 23 and the adhesive layer 14. Dissolves. When all the adhesive layers 14 are dissolved, the support substrate 15 is peeled off from the silicon mother substrate 10.

  In the present embodiment, even after the support substrate 15 is peeled off, the silicon mother substrate 10 is not separated into pieces by the plurality of connecting portions 23j of the etching stopper layer 3, and the circular state is maintained.

  Next, as shown in FIG. 9D, after the silicon mother substrate 10 is pulled up from the peeling container 17, the connecting portion 23j is cut to separate the silicon mother substrate 10 into individual pieces. In this way, a plurality of MEMS structures 1 having the silicon substrate 2 are completed.

  As described above, in this embodiment, by partially leaving a part of the etching stopper layer 3 on the dicing line L, silicon can be used without using the jig 50 used in the first embodiment. The mother substrate 10 can be pulled up from the peeling container 17.

  As described above, the preferred embodiments according to the present invention have been described with reference to the accompanying drawings, but the present invention is not limited to the examples. It is obvious for those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the claims. It is understood that it belongs to.

  DESCRIPTION OF SYMBOLS 1 ... MEMS structure, 2 ... Silicon substrate (semiconductor substrate), 2a ... 1st surface, 2b ... 2nd surface, 2A ... Opening part (penetrating part, 3rd opening pattern), 2B ... 2nd opening pattern, 3, 30 ... Etching stopper layer, 3 ... Etching stopper layer (first layer), 3q ... Corner, 4 ... Device layer, 10 ... Silicon mother substrate (mother substrate), 10a ... First surface, 10b ... Second surface, 13h, 23h ... opening, L ... dicing line, R ... structure forming region, 13 ... first opening pattern, 14 ... adhesive layer, 15 ... support substrate, 41 ... diaphragm

Claims (6)

A first step of forming an etching stopper layer on the first surface of the mother substrate;
A second step of forming, in the etching stopper layer, a first opening pattern exposing a part of the first surface;
A third step of forming a plurality of device layers on the remaining etching stopper layer;
A fourth step of installing a support substrate on the first surface side through an adhesive layer;
A fifth step of forming a second opening pattern that exposes the adhesive layer at a position corresponding to the first opening pattern from a second surface facing the first surface of the mother substrate;
A sixth step of etching the adhesive layer from the second opening pattern by a wet etching method and peeling the support substrate;
The first opening pattern corresponds to a dicing line;
The method of manufacturing a MEMS structure, wherein the mother substrate is divided into a plurality of pieces by the second opening pattern.   2. The method of manufacturing a MEMS structure according to claim 1, wherein one of the plurality of device layers is formed on each of the plurality of pieces.   3. The MEMS structure according to claim 1, wherein in the fifth step, a third opening pattern is formed to expose the etching stopper layer at a position corresponding to each of the plurality of device layers. Production method.   4. The method of manufacturing a MEMS structure according to claim 1, wherein the first opening pattern is formed so that corners of the plurality of pieces are rounded. 5. A semiconductor substrate;
A first layer formed on a first surface of the semiconductor substrate;
A device layer formed on the first layer,
The semiconductor substrate has a penetrating portion from the second surface facing the first surface to the first layer at a position where the device layer is formed,
The MEMS structure according to claim 1, wherein a corner portion of the first layer and a corner portion of the semiconductor substrate are round in a state in which the device layer is viewed in plan.   The MEMS structure according to claim 5, wherein the first layer functions as a diaphragm.

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