WO2011095386A2 - Production method for a porous micro needle assembly having rear face connection and corresponding porous micro needle assembly - Google Patents

Abstract

The invention relates to a production method for a porous micro needle assembly having rear face connection and corresponding porous micro needle assembly. The method comprises the following steps: forming a micro needle assembly (4) having at least one micro needle (4a; 4b) on the front face (VS) of a semiconductor substrate (1) which rises from a supporting region (1b) of the semiconductor substrate (1); forming a masking layer (2) on the rear face of the semiconductor substrate (1), wherein the masking layer (2) has a through passage (3a; 3b) in the rear face region (RS'; RS") of the at least one micro needle (4a; 4b); and porosifying the micro needle assembly (4) and at least one part of the supporting region (1b) in an anodic etching process, which etches the micro needle assembly (4) and the supporting layer (4) selectively opposite the masking layer (2), wherein a current flow (I) runs through the through passage (3a; 3b) starting from the micro needle assembly (4); wherein the at least one micro needle (4a; 4b) and a region of the supporting layer (1b) located above the through passage (3a; 3b) in the rear face region (RS'; RS") thereof are positioned so that a porous micro needle (4a1; 4b') is created having the through passage (3a; 3b) as a rear face connection.

Description

 description

title

 A method of manufacturing a porous microneedle assembly with backside connector and corresponding porous microneedle assembly

State of the art

The present invention relates to a manufacturing method for a porous micro-needle assembly with backside connector and a corresponding porous microneedle assembly.

Although applicable to any micromechanical devices, the present invention and its underlying background with respect to micromechanical devices in silicon technology will be explained. Porous microneedle arrays, which consist for example of porous silicon, are used in the field of "transdermal drug delivery" as an extension of medicament patches, as a carrier of a vaccine or for the recovery of body fluid (so-called "Transdermal fluid") for the diagnosis and Analysis of body parameters (eg glucose, lactate, ..) used.

Transdermal patches for small molecules (such as nicotine) are widely known. In order to extend the scope of such transdermal applications of drugs, so-called chemical enhancers or various physical methods (ultrasound, heat pulses) are used, which help to overcome the protective coat of the skin.

Another method for this purpose is the mechanical penetration of the outer layers of the skin (stratum corneum) by means of fine porous microneedles combined with the administration of an active substance, preferably via an active substance plaster into which the microneedles can already be integrated, or via a metering device which has a targeted Delivery (bolus, pause, increase, ..) of active ingredients allows. DE 10 2006 028 781 A1 discloses a method for the production of porous micro-needles arranged on a silicon substrate in an array for the transdermal administration of medicaments. The method includes forming a microneedle array having a plurality of microneedles on the front side of a semiconductor substrate rising from a support region of the semiconductor substrate, and partially porosifying the semiconductor substrate to form porous microneedles, the porosification starting from the front side of the semiconductor substrate and a porous one Reservoir is formed. Fig. 2 is a schematic cross-sectional view for explaining a known from DE 10 2006 028 781 A1 manufacturing method for a porous micro-needle assembly with backside connection.

In the known manufacturing method of Fig. 2, reference numeral 100 denotes a partially porosified silicon substrate having an upper porosified region 100a and a lower non-porosified region 100b. An array of porous microneedles 40 rises from the porosified region 100a. In this known example, an additional etch process provides a feedthrough 150 in the microneedles 40 which allows drug delivery from the back side of the silicon substrate 100.

Advantages of the invention

The production process according to the invention for a porous microneedle arrangement with backside connection and the corresponding porous microneedle arrangement defined in claim 1 have the advantage that both a porosification is achieved in a single anodic etching process and a backside connection to the through openings of the masking layer is obtained ,

The idea underlying the present invention consists in focusing the electric current density in the anodic etching process by the back masking.

By electro-polishing effects in areas of greatly increased local current density immediately above the passage openings, a reservoir access can be achieved without the porous structure peels off due to the electropolishing of the semiconductor substrate. In particular, such a local electropolishing can be achieved solely by field line focusing without an increase in the external current density compared to the known case. The thus created porous rear accessible structure is characterized by a simple process management and is therefore inexpensive to produce. The porous structure is also mechanically fixed in the area of the supporting layer. The features listed in the dependent claims relate to advantageous developments and improvements of the subject matter of the invention.

According to a preferred refinement, the anodic etching process is carried out in such a way that, after porosification, a non-porous residual region of the support layer remains on the masking layer laterally of the passage opening.

According to a further preferred development, the anodic etching process is carried out in such a way that, after porosification, a flank region of the non-porous residual region of the support layer is formed, which drops off towards the passage opening.

drawings

Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description.

In the drawings: FIG. 2 shows schematic cross-sectional representations for explaining an embodiment of the production method according to the invention for a porous micro-needle arrangement with rear-side connection; FIG. and

Fig. 2 is a schematic cross-sectional view for explaining a DE

 10 2006 028 781 A1 known manufacturing method for a porous micro-needle assembly with backside connection.

Description of exemplary embodiments

In the figures, like reference numerals designate the same or functionally identical elements. Fig. 1 ac show schematic cross-sectional views for explaining an embodiment of the manufacturing method according to the invention for a porous micro-needle assembly with backside connection. In Fig. 1, reference numeral 1 denotes a silicon semiconductor substrate having a front side VS and a back side RS.

On the front side VS of the semiconductor substrate 1, a microneedle arrangement 4 is formed by an etching process known for example from EP 0 625 285 B1, which has a plurality of microneedles 4a, 4b which rise from a support region 1b of the semiconductor substrate 1. At the edge of the substrate, an edge region 1 a rises from the support area 1 b. The edge region 1 a forms a lateral support structure for subsequent separation of the microneedle assembly. On the rear side RS of the semiconductor substrate 1, a masking layer 2 is formed with through-holes 3a, 3b, which are located in a respective backside region RS 'or RS "of the microneedles 4a and 4b. Preferably, the masking layer 2 is formed before the formation of the microneedles 4a, 4b is applied to the backside RS of the semiconductor substrate 1 and the through-holes 3a, 3b are formed therein.

The masking layer 2 should be resistant to the anodic etching process when porosifying the microneedle array 4, ie have a sufficiently high selectivity with respect to the microneedle array 4. In other words, the masking layer should be electrically insulating and have good HF (hydrofluoric acid) resistance. As the masking layer 2, for example, an SiC layer, an SiN layer or a polymer layer (eg, SU8) may be used.

The height H of the microneedles 4a, 4b is typically in the range 100-400 μm, the height h of the underlying support region 1b of the substrate 1 is preferably a few 10-100 μm. The passage openings 3a, 3b of the masking layer 2 typically move in the range of a few to a few 10 μm diameter or edge length.

With further reference to FIG. 1 b, a porosification of the microneedle assembly 4 and a part of the edge region 1 a and of the support region 1 a is carried out in an anodic etching process which selectively places the microneedle assembly 4, the edge region 1 a and the support region 1 b opposite the masking layer 2 etches. In this case, silicon of the semiconductor Substrate 1 electrochemically etched in HF (hydrofluoric acid) -containing electrolyte under the action of an electric current flow I, whereby pores are formed in the silicon.

In the said etching process, the concentration of hydrofluoric acid is typically between 20% and 50%, advantageously between 22% and 28%. The current density is between 5 mA / cm ² and 300 mA / cm ² , advantageously between 80 and 300 mA / cm ² , most preferably between 120 and 200 mA cm ² . The current density can also be varied advantageously over the etching depth. The duration of the etching process depends on the height h of the support region (10 μιη to 100 μιη). For a height h = 10 μιη, the etching time can be less than one minute. For h = 100 μιη 15 minutes can be needed up to more than 45 minutes. The support structure must ensure a certain stability, which is why it should advantageously not fall below 50μιη, resulting in etch times of typically 10 to 15 minutes. In area A, the electric field lines reach the needle assembly 4 or the porous microneedle assembly 4 'very homogeneously. Due to the back masking layer 2, the field lines are increasingly focused with increasing etch depth, as illustrated in areas A and C by arrows becoming increasingly narrower. This focusing drastically increases the electrical current density. In this way, even the critical current density can be exceeded in region C, above which the porosification passes into an electropolishing process.

The state shown in Fig. 1 b corresponds to the state at the end of the anodic etching process, which is illustrated in Fig. 1 c without the current density arrows.

The microneedles 4a, 4b are transferred into porosified microneedles 4a ', 4b' of the porous microneedle assembly 4 '. A region of the support layer 1b lying in the rear side region RS 'or RS "above the passage opening 3a or 3b is porosified in such a way that the respective porous microneedle 4a' or 4b 'is connected to the corresponding through opening 3a or 3b as the rear side connection. Above the through-opening 3a or 3b, after porosification by electropolishing, a completely removed region 7 of the support layer 1b is formed, This local electropolishing combined with the creation of the removed region 7 as a reservoir is advantageous for the introduction of the active ingredient Current density can be achieved in comparison to the known case, but at the same time an electropolishing is achievable, prevents the porous structure peels off the silicon substrate by the electropolishing.

Side of the through holes 3a, 3b remains due to the depletion of the field lines of the electric current density, a non-porous residual region 8 of the support layer 1 b on the

Masking layer 2. A flank region 9 of this non-porous remaining region 8 of the support layer 1b falls in a funnel shape in accordance with the course of the field lines towards the through-opening 3a, 3b. This also supports the introduction of the active substance into the porous microneedle assembly 4 'or the adhesion of the porous microneedle assembly 4' to the remaining support layer 1b.

As can also be seen from FIG. 1 c, part of the edge region 1 a of the semiconductor substrate is also porosified, but the remaining region is sufficient to effectively support the singulation.

Although the present invention has been described above with reference to preferred embodiments, it is not limited thereto, but modifiable in many ways. In particular, the materials are only given by way of example and can be replaced by other materials which fulfill the required porosity selectivity criteria.

Claims

claims 1 . Manufacturing method for a porous micro-needle assembly (4 ') with backside connection comprising the steps of: forming a microneedle assembly (4) with at least one microneedle (4a, 4b) on the front side (VS) of a semiconductor substrate (1) extending from a support region (1b); ) of the semiconductor substrate (1); Forming a masking layer (2) on the back side (RS) of the semiconductor substrate (1), wherein the masking layer (2) has a through opening (3a; 3b) in the backside area (RS ') of the at least one microneedle (4a; 4b) ; and Porosifying the microneedle assembly (4) and at least a portion of the support region (1 b) in an anodic etching process, which the microneedle assembly (4) and the support layer (1 b) selectively etched against the masking layer (2), wherein a current flow (I ) extends from the microneedle array (4) through the passageway (3a; 3b); wherein the at least one microneedle (4a, 4b) and a region of the support layer (1b) located in the rear side region (RS ', RS ") above the through-opening (3a, 3b) are porosified such that a porous microneedle (4a'; 4b ') with the passage opening (3a; 3b) is formed as a backside connection. 2. The production method according to claim 1, wherein the anodic etching process is carried out in such a way that, after porosification, a non-porous residual region (8) of the support layer (1b) remains on the masking layer (2) laterally of the passage opening (3a; 3. Production method according to claim 2, wherein the anodic etching process is carried out in such a way that after porosification a flank region (9) of the non-porous residual region (8) of the support layer (1b) is formed, which drops towards the passage opening (3a; 3b). 4. Production method according to claim 1, 2 or 3, wherein the anodic etching process is carried out such that after porosification above the passage opening (3a, 3b), a completely removed region (7) of the support layer (1 b) is formed. A manufacturing method according to any one of the preceding claims, wherein the microneedle assembly (4) comprises a plurality of microneedles (4a; 4b) each having a respective through hole (3a; 3b) formed by porifying into a plurality of porous microneedles (4a '; 4b ') are transferred with a respective passage opening (3a, 3b) as the rear side port. A manufacturing method according to any one of the preceding claims, wherein the masking layer (2) is a polymer layer. 7. A manufacturing method according to one of the preceding claims, wherein the microneedles (4a, 4b) have a height (H) in the range 100 to 500 μιη and / or wherein the support region (1 b) a height of 10 to 100 μιη and / or the Through openings (3a, 3b) have a diameter of 1 to 10 μιη. A porous microneedle assembly (4 ') having a backside connector comprising: a porous microneedle assembly (4') having at least one porous microneedle (4a ', 4b') extending from a partially porosified support region (1b) on the front side (VS) of a Lift semiconductor substrate (1); a masking layer (2) on the backside (RS) of the semiconductor substrate (1) having a through hole (3a; 3b) in the backside area (RS ') of the at least one microneedle (4a; 4b); (RS ') of the at least one porous microneedle (4a', 4b ') above the through hole (3a; 3b) lying portion of the support layer (1 b) is porosified such that the through hole (3a, 3b) forms the rear side port , 9. microneedle assembly (4 ') according to claim 8, wherein the side of the through hole (3a, 3b), a non-porous residual region (8) of the support layer (1 b) on the masking layer (2) is present. 10. microneedle array (4 ') according to claim 9, wherein a flank region (9) of the non-porous residual region (8) of the support layer (1 b) is present, which to the passage opening (3a, 3b) falls out. 1 1. micro needle assembly (4 ') according to claim 8, 9 or 10, wherein above the passage opening (3a, 3b), a completely removed region (7) of the support layer (1 b) is present. 12. The microneedle array (4 ') according to one of the preceding claims 8 to 11, wherein a plurality of porous microneedles (4a'; 4b ') having a respective through hole (3a; 3b) is provided as the rear side terminal. 13. microneedle array (4 ') according to any one of the preceding claims 8 to 12, wherein the masking layer (2) is a polymer layer. 14 microneedle assembly (4 ') according to any one of the preceding claims 8 to 13, wherein the porous microneedles (4a', 4b ') have a height (H) in the range 100 to 500 μιη and / or wherein the support region (1 b) a Height of 10 to 100 μιη and / or the passage openings (3a, 3b) have a diameter of 1 to 10 μιη.