Abstract:
A method for measuring microgalvanically produced components having a three-dimensional, depth-lithographically produced structure, which provides a single- or multilayer component which is constructed using galvanic metal deposition, the metal being deposited around a structure of photoresist defining the desired orifice contour of the component; in the process, a photoresist region, which selectively interrupts the structure of the component to be manufactured, being incorporated during the microgalvanic production; at least the interrupting photoresist region being dissolved out of the interrupted component; and a contactless measuring of the orifice structure of the interrupted component being undertaken in the region of a previously existing resist edge of the photoresist region using a measuring device.

Description:
FIELD OF THE INVENTION 
     The present invention provides a method for measuring microgalvanically produced components. 
     BACKGROUND INFORMATION 
     German Published Patent Application No. 196 07 288 discusses microgalvanically produced components, which are used in the form of orifice disks for injectors, i.e., generally to produce fine sprays, e.g., having large spray angles. The individual layers or functional planes of the orifice disk are constructed one upon the other using galvanic metal deposition (multilayer electroplating). The layers are galvanically deposited in succession, so that each succeeding layer is permanently bonded by galvanic adhesion to the underlying layer, and all layers, together, then form a single-piece orifice disk. To provide better handling of a multiplicity of orifice disks when applying the various manufacturing process steps, two positioning location holes, in the form of circular through holes, are provided on one wafer, per orifice disk, for example, near the outer boundary edge of the orifice disk and extend over the entire axial height of the orifice disk. This facilitates the process of successively building up a plurality of galvanic layers over time. It is only possible to inspect or remeasure the inner orifice structure of such a microgalvanically produced component by using destructive manufacturing processes (grinding). 
     SUMMARY 
     The present invention provides a method for measuring microgalvanically produced components wherein, in a simple manner, actual, precise dimensions of the inner structure of the component may be checked and measured, so that information pertaining to the configuration and contour definition of the component is quickly and reliably accessible. For this, in the context of microgalvanically producing the components, in only few selected components, which are otherwise placed, for example, in very large piece numbers on a wafer or panel, photoresist regions or lines are inserted interrupting the structure of these selected components in desirable fashion. Once the photoresist is dissolved, the inner structures of the particular component are easily exposed and are thus able to be measured quite simply in a contact-free and non-destructive manner. 
     Angles, cavities, rear spaces and offsets of the component&#39;s orifice structure, as well as its layer thicknesses may be measurable in contactless fashion. 
     On a single wafer, galvanic metal deposition may be used to produce identical single- or multilayer components, which are manufactured as complete components without the photoresist regions interrupting the desired orifice structure, together with the components having the interrupting photoresist regions. If it is intended for the components to be remeasured merely by taking random samples, then a ratio of 3 to 5:1000 of interrupted components to complete components of the same type configuration, may be established on one wafer. This permits an assessment of the dimensional accuracy and quality of the manufactured components on the entire wafer. 
     An exemplary embodiment of the present invention is represented in simplified form in the drawing and is explained in detail in the following description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a partial representation of an injector having a microgalvanically produced component in the form of an orifice disk. 
         FIG. 2  is a plan view of a microgalvanically manufacturable orifice disk. 
         FIG. 3  is a plan view of the orifice disk of  FIG. 2 , manufactured to include an inner photoresist region, so that the actual orifice disk is interrupted. 
         FIG. 4  is a sectional view of the interrupted orifice disk in the region of a resist edge in accordance with arrows IV in FIG.  3 . 
         FIG. 5  is a schematic diagram of a measuring and evaluation arrangement. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a partial representation of a valve in the form of an injector for fuel injection systems of mixture-compressing, spark-ignition engines. The valve includes an orifice disk  23  which represents an exemplary embodiment of a microgalvanically produced component that is measurable in accordance with the present invention. It should be noted that orifice disk  23 , which is described in greater detail below, is not exclusively provided for use on injectors; similar components may also be used, in fact, for paint nozzles, inhalers, ink-jet printers, or for freeze-drying processes, to eject or inject liquids, such as beverages, or to atomize medications. Orifice disks  23  manufactured using multilayer electroplating are quite generally suited for producing fine sprays, for example having large angles. 
     Orifice disks  23  themselves, in turn, also constitute only one specific embodiment of a microgalvanically produced component. Microgalvanically produced components having forms, contours, size ratios and intended applications that differ completely from the described orifice disk  23  may also be manufactured and measured in accordance with the present invention. 
     The injector, partially illustrated in  FIG. 1 , has a tubular valve-seat support  1 , in which a longitudinal opening  3  is formed concentrically to a longitudinal valve axis  2 . Arranged in longitudinal opening  3  is a, for example, tubular valve needle  5 , which is securely connected at a downstream end  6  to a, for example, spherical valve closure member  7 , on whose periphery, for example, five flattened regions  8  are provided to allow the fuel to flow past. 
     The injector may be actuated, e.g., electromagnetically. A schematically indicated electromagnetic circuit having solenoid coil  10 , an armature  11 , and a core  12  is used for axially moving valve needle  5  and, as such, for opening the injector against the spring force of a restoring spring and, respectively, for closing the injector. Armature  11  is connected, for example, by a welded seam produced by a laser to the end of valve needle  5  facing away from valve-closure member  7 , and is aligned with core  12 . 
     A guide opening  15  of a valve-seat member  16 , which is imperviously mounted by welding in the downstream end of valve-seat support  1  in longitudinal opening  3 , is used to guide valve-closure member  7  during axial movement. Valve-seat member  16  is concentrically and fixedly connected to a, for example, cup-shaped orifice-disk carrier  21 , which rests at least with an outer annular region  22  directly against valveseat member  16 . 
     A microgalvanically produced component, here orifice disk  23 , is placed upstream from a through hole  20  in orifice-disk carrier  21  such that the disk  23  completely covers through hole  20 . A peripheral and impervious first welded seam  25 , formed by a laser, joins valve-seat member  16  and orifice-disk carrier  21 . Orifice-disk member  21  is joined, for example, by a peripheral and impervious, second welded seam  30  to the wall of longitudinal opening  3  in valve-seat carrier  1 . 
     Orifice disk  23  is clamped in dimensionally accurate fashion, for example, into a cylindrical outlet orifice  31  of valve-seat member  16  following a frustoconically tapered valve-seat surface  29 . Orifice disks  23  illustrated in  FIGS. 2 through 4  are constructed in a plurality of metallic functional planes using galvanic deposition (multilayer electroplating). The depth-lithographic production using electroplating technology produces special features in the contour definition, such as:
         functional planes having a constant thickness over the disk surface;   as a result of the depth-lithographic pattern delineation, substantially vertical cuts in the functional planes which form each of the hollow spaces traversed by flow (deviations of about 3° from optimally vertical walls may be caused by production engineering);   desired undercuts and overlappings of the cuts due to the multilayer structure of individually patterned metal layers;   cuts of any desired cross-sectional shapes having largely axially parallel walls;   one-piece configuration of the orifice disk, since the individual metal depositions are performed in immediate succession.       

     In a plan view,  FIG. 2  illustrates an exemplary embodiment of an orifice disk  23  as may be manufactured, for example, on a wafer or panel, side-by-side in the hundreds. Orifice disk  23  is configured as a flat, circular component which has a plurality of, for example three functional planes or layers in axial succession. On this are built up, starting from a lower functional plane  35 , for example, two further functional planes  36  and  37 , a plurality of functional planes being able to be produced in a single galvanic step using the so-called lateral overgrowth technique. 
     Top functional plane  37  has a rectangular inlet orifice  40  of a greatest possible size. Four quadratic outlet orifices  42  are provided in lower functional plane  35 , each, for example, at the same distance to longitudinal valve axis  2  and, thus, to the center axis of orifice disk  23 , and also symmetrically disposed thereto, for example. In the context of a projection of all functional planes  35 ,  36 ,  37 , outlet orifices  42  lie in one plane, with an offset outside of inlet orifice  40 . The offset may vary in size in different directions. 
     To ensure a fluid flow from inlet orifice  40  to outlet orifices  42 , a channel  41 , which constitutes a cavity, is formed in middle functional plane  36 . Channel  41  having a circular contour is of such a size, which, viewed in the projection, completely covers inlet orifice  40  and outlet orifices  42 . 
     In  FIGS. 3 and 4 , the orifice disk is illustrated with the same contour definition as orifice disk  23  illustrated in  FIG. 2 , however, in accordance with the present invention, the orifice disk  23  has an easily measured shape configured as an interrupted orifice disk  23 ′. 
     In the following sections, the actual method for manufacturing orifice disks  23  in accordance with  FIGS. 2 through 4  is explained below. The method steps used in galvanic metal deposition to manufacture an orifice disk may be inferred, for example, from German Published Patent Application No. DE 196 07 288. 
     The method starts with providing a flat and stable carrier plate that may be made of metal (titanium, copper), silicon, glass, or ceramic, for example. At least one auxiliary layer is optionally first electrodeposited on the carrier plate. This is, for example, a galvanic starting layer (e.g. Cu) that is needed for electrical conduction for the later microelectroplating. 
     The galvanic starting layer may also be used as a sacrificial layer, in order to later allow a simple separation of the orifice-disk structures by etching. The auxiliary layer (typically CrCu or CrCuCr) is applied by sputtering or by currentless metal deposition. Following this pretreatment of the carrier plate, a photoresist is applied over the entire surface of the auxiliary layer. 
     In this context, the thickness of the photoresist may correspond to the thickness of the metal layer to be produced in the later electroplating process, i.e., to the thickness of the lower layer or functional plane  35  of orifice disk  23 . The metal pattern to be produced is to be inversely transferred to the photoresist with the aid of a photolithographic mask. One possibility is to expose the photoresist directly via the mask using UV exposure (UV depth lithography). 
     The negative pattern ultimately produced in the photoresist for the later functional plane of orifice disk  23  is galvanically filled with metal (e.g. Ni, NiCo) (metal deposition). As a result of the electroplating, the metal is applied closely to the contour of the negative pattern, so that the predefined contours are reproduced. To produce the structure of orifice disk  23 , it is necessary to repeat the steps starting with the optional application of the auxiliary layer, depending on the number of layers desired, two functional planes being produced, for example, in one galvanic step (lateral overgrowth). For the layers of one orifice disk  23 , different metals may also be used, yet are only applicable in each case in a new electroplating step. Orifice disks  23  are subsequently separated. For this, the sacrificial layer is etched away, thereby causing orifice disks  23  to lift off from the carrier plate. The galvanic starting layers are then removed by etching, and the remaining photoresist is dissolved out of the metal structures. 
     Microgalvanically constructed components, such as orifice disks  23 , may be produced in large numbers (e.g., up to &gt;1000 units) on a wafer or panel. After orifice disks  23  are separated from the carrier plate, they are available for their particular intended application. However, the inner orifice structure of such a microgalvanically produced component is then no longer accessible. For testing and measuring purposes, however, a very simple and inexpensive method may be provided for measuring the components, at least by random sampling. In other methods heretofore, orifice disks  23 , such as the one illustrated in  FIG. 2 , were only able to be checked and remeasured by using destructive manufacturing processes. This required expensive embedding and grinding of the components selected for remeasuring. Grinding the finished components may disadvantageously produce burrs which may falsify the measuring result. Moreover, there is an increased risk of deformation of the components to be measured during embedding and grinding. 
     For that reason, in accordance with the present invention, immediately upon microgalvanically producing the components, for example orifice disks  23 , photoresist regions  45 , which may also be characterized as resist lines or resist cores, are inserted into only few selected components  23 ′ on the wafer (for example, for 3 to 5 of 1000 components). The incorporation of selective photoresist regions  45  is undertaken via specially formed masks at selected components  23 ′, at the beginning, so that the metal structure to be built up, beginning from lower functional plane  35 , is already growing along this photoresist region  45 . Thus, selected components  23 ′ are produced in interrupted fashion over an entire structure (FIG.  3 ). Once photoresist region  45  is dissolved out, the inner structures of the particular component  23 ′ are exposed. 
     As illustrated in  FIG. 3 , it is practical to lay photoresist region  45  such that it intersects the orifice structures intended for measurement following manufacturing. Thus, in the case of orifice disk  23 ′ illustrated in  FIG. 3 , photoresist region  45  is incorporated such that it intersects, at the same time, functional planes  35 ,  36 ,  37  in the region of inlet orifice  40 , of channel  41 , and of outlet orifices  42 . 
       FIG. 4  illustrates a sectional view of interrupted orifice disk  23 ′ in the region of a resist edge  46  in accordance with arrows IV in FIG.  3 . Thus, this view does not illustrate a section in the sense of a machine-cutting through orifice disk  23 ′, but rather a side view of the orifice disk part produced in this manner at the beginning. Thus, the easily exposed orifice contour is able to be measured in non-destructive fashion. Typical measurable dimensions of an orifice disk  23  are, for example, layer thickness a, height h of channel  41 , offset x of inlet orifice  40  and outlet orifices  42 , the so-called rear space z, thus the flow region of channel  41  projecting over outlet orifices  42 , as well as inlet edge angle  47  of inlet orifice  40  and outlet edge angle  48  of outlet orifices  42 . 
     The components present following separation are sorted into complete components  23  and interrupted components  23 ′. Interrupted components  23 ′ are brought to a measuring device  50 . A schematic measuring and evaluation system is indicated in FIG.  5 . The contactless measuring of components  23 ′, which are clamped, for example, on a workpiece support, may be performed using various measuring devices  50 . Scanning electron microscopes, profile projectors having vertical illumination, optical cameras, such as CCD cameras or infrared cameras, microscopes having position-sensing systems or microfocus measuring systems having laser scanning (UBM) may be suited for this purpose. The recorded measured values are processed and analyzed, for example, in an evaluation unit  51 , the measuring accuracy and quality of the manufactured components  23  being thereby assessed.