METHOD FOR PRODUCING SINGULATED ENCAPSULATED COMPONENTS

Abstract

A method for producing singulated encapsulated components. The method includes the steps of application of a frame structure on a substrate surface of a substrate, wherein the frame structure surrounds components arranged on the substrate surface; bonding of a cover substrate on the frame structure; hardening of the frame structure; and singulation of the encapsulated components, wherein the frame structure is formed from an adhesive.

Claims

1-8. (canceled)

9. A method for producing singulated encapsulated components, said method comprising: application of a frame structure on a substrate surface of a substrate, wherein the frame structure surrounds components arranged on the substrate surface; bonding of a cover substrate on the frame structure; hardening of the frame structure; and singulation of the encapsulated components, wherein the frame structure is formed from an adhesive, wherein the singulated encapsulated components are treated with plasma and/or reactive gas, wherein the plasma and/or gas treatment is conducted after the hardening of the frame structure, and wherein the plasma and/or gas treatment leads to a chemical conversion of an outer surface of the frame structure.

10. The method according to claim 9, wherein the adhesive is a silicone adhesive.

11. The method according to claim 9, wherein the singulated encapsulated components are treated in such a way that on the outer surface of the frame structure a glass-like structure arises.

12. The method according to claim 11, wherein the glass-like structure is an SiO.sub.2 structure.

13. The method according to claim 9, wherein the hardening of the frame structure takes place before the bonding of the cover substrate on the frame structure.

14. The method according to claim 9, wherein the adhesive of the frame structure is applied by inkjet processes, printing processes, casting, coating, spraying, extruding, spray coating, spray lacquering and/or lacquering.

15. A singulated encapsulated component, produced with a method according to claim 9.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0109] FIG. 1a: shows a plan view of a product substrate with components,

[0110] FIG. 1b: shows a cross-sectional view of a product substrate in a first embodiment,

[0111] FIG. 1c: shows a cross-sectional view of a product substrate in a second embodiment,

[0112] FIG. 2a: shows a product substrate after a first process step of a method according to the invention in a first embodiment,

[0113] FIG. 2b: shows a side view of the product substrate from FIG. 2a,

[0114] FIG. 2c: shows a side view of a product substrate after a first process step of a method according to the invention in a second embodiment,

[0115] FIG. 3a: shows a side view of a frame structure of a product substrate in a first embodiment,

[0116] FIG. 3b: shows a side view of a frame structure of a product substrate in a second embodiment,

[0117] FIG. 3c: shows a side view of a frame structure of a product substrate in a third embodiment,

[0118] FIG. 4a: shows a side view of an encapsulated and singulated component in a first embodiment,

[0119] FIG. 4b: shows a side view of an encapsulated and singulated component in a first embodiment after a process step of a post-treatment of the surfaces for the surface conversion to form dense SiO.sub.x,

[0120] FIG. 4c: shows a plan view of an encapsulated and singulated component according to the invention after the last process step of the post-treatment of the surfaces for the surface conversion to form dense SiO.sub.x,

[0121] FIG. 5a: shows a diagrammatic representation of a first embodiment of the device according to the invention for the post-treatment of the encapsulated components,

[0122] FIG. 5b: shows a diagrammatic representation of a second embodiment of the device according to the invention for the post-treatment of the encapsulated components,

[0123] Identical components or components with the same function are denoted by the same reference numbers in the figures. The figures are not represented true to scale so as to improve the representation.

DETAILED DESCRIPTION OF INVENTION

[0124] A product substrate 1 is represented in FIG. 1a, on surface 1o whereof components 2 located thereon have been produced. According to FIG. 1b, these components 2 can also contain electrically conductive connections 3, 3′.

[0125] In a further embodiment according to FIG. 1c, components 2′ are optical structures, in particular microlenses, on and/or with a carrier substrate 1′. Processed substrates 1, 1′ have precisely defined free areas if between components 2, 2′, in order to be able to carry out the encapsulation process completely on the wafer level.

[0126] In a first step of an exemplary method according to the invention according to FIG. 2a, a frame structure 4 is deposited between components 2.

[0127] The encapsulation process according to the invention is based on a two-part encapsulation, i.e. with a frame structure 4 surrounding components 2, 2′ and a cover substrate 5 placed thereon according to FIGS. 2b and 2c.

[0128] Frame structure 4 is produced from the adhesive, which is used for the bonding to cover substrate 5.

[0129] In the side view according to FIG. 2b, it can be seen that a wide frame structure 4 has been deposited. There is a free space 1f′ between components 2 and frame structure 4. The singulation of the components after the encapsulation according to FIG. 2b takes place for example along intersection lines S.

[0130] In a further example of embodiment according to FIG. 2c, individual frame structures 4′ are deposited in each case between components 2, so that the singulation of the components takes place after the encapsulation between two frame structures 4′. See in this regard intersection lines S′.

[0131] The height of frame structure 4 can be varied greatly depending on requirements or depending on component type 2, 2′. If a cavity above components 2, 2′ is required or desired, the required height of frame structure 4 is optimised in each individual case.

[0132] The height of frame structure 4 is understood to mean the total height of frame 4, 4′, 4″, 4′″ including any adhesive layers still required.

[0133] Frame structure 4, 4′, 4″, 4′″ is produced from the adhesive material which is used for the bonding to cover substrate 5. Thus, in the preferred embodiment, only an adhesive material is used to produce the frame structure.

[0134] After the deposition of the frame structure, a height difference H arises between components 2, 2′ and frame structure 4, 4″ according to FIGS. 3a and 3b. In the embodiment according to FIG. 3b, height difference H is almost zero, since frame structure 4″ and components 2 are almost the same height.

[0135] In another embodiment according to FIG. 3c, frame structure 4′″ can be built up by the deposition of a plurality of layers of material. According to the invention, the adhesive as the material for frame structure 4′″ can partially or completely cross-link after each deposited layer, i.e. hardening for example by UV radiation or supply of heat. In an alternative embodiment, depending on the viscosity and/or flow properties of the adhesive, a plurality of layers can first be deposited upon one another before complete hardening takes place.

[0136] According to the invention, the hardening is preferably based on a polymerisation of the adhesive. The polymerisation is started by a so-called initiator. If electromagnetic radiation is used for the hardening, at least one of the two substrates, in particular the cover substrate, is transparent or sufficiently transparent for electromagnetic radiation of the wavelength in which cross-linking of the adhesive occurs.

[0137] In a special embodiment, the complete hardening of the frame structure can also take place before the bonding of the product substrate and the cover substrate. In this embodiment, a layer of adhesive is applied congruent on the already hardened frame structure before the bonding of the product substrate and cover substrate and is hardened after the bonding.

[0138] The hardening process takes place by electromagnetic radiation, preferably by UV-light and/or under the effect of thermal radiation. The electromagnetic radiation has a wavelength in the range between 10 nm and 2000 nm, preferably between 10 nm and 1500 nm, more preferably between 10 nm and 1000 nm, most preferably between 10 nm and 500 nm.

[0139] A heat treatment takes place at less than 750° C., preferably at less than 500° C., still more preferably at less than 250° C., most preferably at less than 100° C., with utmost preference at less than 50° C. A heat treatment preferably takes place via thermal conduction through the sample holder. Heating of the surrounding atmosphere or a combination thereof is however also conceivable.

[0140] In a second process step, the bonding of the product substrate and the cover substrate takes place by gluing the frame structure to the diffusion-tight cover substrate according to FIGS. 2b and 2c, wherein the adhesive forms the frame structure. Pressure and/or temperature can also be used in the bonding of the product substrate with the adhesive. In the case of a transparent cover substrate, the hardening of the frame structure/the adhesive can take place after the bonding of the product substrate and the cover substrate.

[0141] The singulation of the encapsulated components takes place in a further process step. FIG. 4a shows a singulated and encapsulated component 6. Unit 2 is framed at the sides by frame structure 4. The finished and encapsulated components located on the ready-processed substrate are separated during the singulation. The singulation of the components can take place by dicing, laser processes (laser dicing) or plasma processes (plasma dicing).

[0142] The outer surface of frame structure 4o does not enable encapsulation of high quality and hermeticity. In order to enable long-term stability of the components, the singulated and encapsulated components are subsequently treated in a last process step. In particular, a chemical conversion of outer surface 4o of frame structure 4 is achieved. As a result of the inventive subsequent chemical and/or physical treatment of the surface of frame structure 4o of the already singulated and encapsulated components, a simplified method for the encapsulation at the wafer level is used, which enables encapsulation of high quality and hermeticity.

[0143] The treated frame structure thus serves not only as a mechanical stabiliser, but also as protection against particles and media occurring in the atmosphere and/or in the surroundings, in particular fluids, more specifically liquids or gases, in particular water (humidity) and oxygen.

[0144] FIGS. 4b and 4c show respectively in a side view and in a plan view outer frame structure 8 changed by the post-treatment of the encapsulated components according to the invention. According to the invention, adhesives on a silicone base are particularly preferred for producing the frame structure, such as for example PTMS adhesives or POSS-containing adhesives, which after hardening comprise on their surfaces or in layers close to the surfaces Si—O and/or Si—OH units, which can be converted by chemical and/or physical processes during the post-treatment to form an SiO.sub.x surface layer or an SiO.sub.2 layer.

[0145] According to the invention, the outer layer of the frame structure becomes quartz-like. The thickness of the SiO.sub.x layer can be controlled by the duration of the treatment. The treatment is continued only until such time as the frame structure of the encapsulation by the formation of the SiOx surface layer reaches the desired hermeticity in the sense of diffusion-tightness. The formation of the SiOx surface layer or SiO.sub.2 layer on the outer frame structure enables hermetic encapsulation despite different materials of the frame structure and of the substrates.

[0146] In a last process step, the post-treatment of the encapsulated components takes place.

[0147] FIG. 5a shows a process chamber for performing the post-treatment of the encapsulated components according to a first embodiment. Following the singulation, the encapsulated components do not necessarily have to be exposed.

[0148] If the singulated and encapsulated components are still fixed on a tape, in particular on a dicing tape clamped in a dicing frame, all the singulated components of a substrate or wafer can be treated simultaneously on the wafer level, without more time-consuming individual chip handling being required. Devices already existing for the handling of wafers can advantageously be used, as a result of which the post-treatment processes in a process chamber 9, 9′ are simplified.

[0149] In a first embodiment, it is necessary for the further treatment of the encapsulated components to increase the spacing of the separated components by expanding the dicing tape. Expansion frames, for example, are used for this purpose. This permits improved access to the side walls, i.e. to the frame structure of the encapsulated components, and thus enables a more efficient post-treatment.

[0150] In process conditions in which tapes are no longer suitable, e.g. high temperatures and/or chemical and/or physical etching rates, the encapsulated components are processed in individual chip handling processes in a second embodiment. Devices and methods for placing a layer of singulated and encapsulated components in defined positions on a substrate are known in the prior art.

[0151] Thus, according to the invention, a plurality of singulated and encapsulated components can also be treated simultaneously in this embodiment.

[0152] In a third embodiment, the singulated and encapsulated components can also be transported and handled loose in a suitable receiving device.

[0153] According to FIGS. 5a and 5b, the loading of process chamber 9, 9′ with the diced encapsulated component structures located for example on an expanded dicing tape takes place via a loading device, preferably an airlock 10. A receiving device 13 serves to fix the dicing frame or the substrate in process chamber 9, 9′. Table 12 is designed in particular such that, during the loading with the dicing frame or substrate, the latter can be moved upwards and a robot arm can deposit the substrate. More generally, table 12 is moved in a z-direction according to requirements.

[0154] Furthermore, a rotation and/or tilting of receiving device 13 is possible. A spatially fixed coordinate system for the table movements is represented by way of example in FIG. 5b.

[0155] Process chamber 9, 9′ can preferably be evacuated and heated. The heating can take place by heated receiving device(s) 13 and/or by radiant heating with suitable heat sources (not represented). Process chamber 9, 9′ is provided with a suction and/or vacuum system 11. The receiving device according to FIGS. 5a and 5b is suitable for dicing frames or substrates. Alternatively, a basket as a receiving device is also possible.

[0156] Receiving device 13 and/or process chamber 9, 9′ can be heated and temperature-controlled in a temperature range between 0° C. and 1000° C., preferably between 0° C. and 500° C., more preferably between 0° C. and 400° C., most preferably between 0° C. and 350° C. Receiving device 13 can in particular comprise holes. These holes can be smaller than the encapsulated components.

[0157] Receiving device 13 can also comprise sensors (not represented), with the aid of which physical and/or chemical properties can be measured. These sensors can for example be temperature sensors.

[0158] The embodiment according to FIG. 5a shows a process chamber 9, preferably a plasma chamber. There are various methods for producing plasmas, which differ markedly with regard to the type of energy coupling. A DC discharge can be produced by the application of a direct voltage. Capacitively coupled MHz discharges (CCP capacitively coupled plasma) are used for plasma etching and plasma coating. Ion flows and plasma density can be controlled separate from one another by using a plurality of frequencies. In the case of an inductively coupled discharge (ICP inductively coupled plasma), the plasma density is increased still further, since the plasma acts as a secondary winding of a transformer.

[0159] The plasmas produced by means of oxygen, nitrogen, noble gases or more complex organic gaseous compounds can modify the substrate surface both by ion bombardment and also by surface reactions by means of ions and/or radicals present in the plasma. Plasma processes are preferably used which enable chemical interactions with the frame material.

[0160] FIG. 5a shows a first embodiment of a plasma chamber 9 with a supply of reactive particles from a downstream plasma reactor 16. Such reactors are used to completely switch off the physical share of plasma etching. A plasma, preferably an oxygen plasma 17, predominates in the interior of process chamber 9. According to the invention, individual gases as well as mixtures thereof can be used to produce plasmas. In a preferred embodiment, oxygen plasma (O.sub.2-plasma) is used.

[0161] A second embodiment of a plasma chamber contains for example a parallel plate reactor with symmetrical electrodes (not represented in the figures). In this embodiment, chemical and physical interactions take place with (amongst other things) the frame material. Irrespective of the structure of the plasma chamber, the process parameters of the O.sub.2-plasma treatment are optimised in such a way that a surface conversion of the exposed frame structure, which is made of adhesive on a silicone base, takes place to form dense SiO.sub.2. For this purpose, process parameters such as a gas mixture, temperature and duration of the O.sub.2-plasma treatment are optimised in such a way that a successful and durable surface conversion to form dense SiO.sub.2 takes place. Hermetic sealing of the already hardened outer frame structure of the encapsulated components is thus achieved. Tilting of receiving device 13 enables, where required, an optimised plasma access to the lateral frame structures of the singulated and encapsulated components.

[0162] In a third embodiment of a plasma post-treatment according to the invention, an additional component is introduced in the O.sub.2-plasma process, in order to achieve a more rapid surface conversion of the exposed frame structure to form dense SiO.sub.2 or SiO.sub.x by reaction with the surface of the frame structure. The additional component can be a mixture of a plurality of substances or an individual chemical compound. The additional component is preferably introduced as gas.

[0163] In process chamber 9, 9′ according to FIGS. 5a and 5b, further preferably gaseous components can be introduced by means of valves 14, 14′.

[0164] In an embodiment according to the invention, siloxanes are used as a chemical compound. This includes for example disiloxane, hexamethyldisiloxane (HMDS) and octamethyltrisiloxane.

[0165] FIG. 5b shows a further embodiment of a process chamber 9′ for the post-treatment of the singulated and encapsulated components. In process chamber 9′ according to FIG. 5b, the outer surfaces of the frame structures undergo, after singulation, a UV-light/ozone (O.sub.3) treatment. A receiving device 13 serves to fix the dicing frame or the substrate in process chamber 9′. Table 12 is designed in particular such that, when the dicing frame or substrate are loaded, the latter can be moved upwards and a robot arm can deposit the substrate. More generally, table 12 is moved in a z-direction according to requirements. Furthermore, a rotation or tilting of receiving device 13 is possible. A spatially fixed coordinate system for the table movements is represented in FIG. 5b.

[0166] Oxygen is introduced into the process chamber by means of one of valves 14, 14′. Radiation sources 15 enable the irradiation of the encapsulated components with UV-light. If UV-radiation with a wavelength below 200 nm strikes oxygen, ozone is formed. The ozone is itself decomposed by UV-light thereby forming highly reactive, free oxygen radicals.

[0167] According to the invention, adhesives on a silicone base are in particular used to produce the frame structure, such as for example PDMS adhesives or POSS-containing adhesives, which after hardening comprise on their surface or in layers close to the surface Si—O and/or Si—OH units, which can be converted to form an SiO.sub.x surface layer by photochemical processes during the UV/ozone treatment. These photochemical processes preferably take place at room temperature.

[0168] Process parameters are optimised in such a way that a thin SiO.sub.x surface layer can arise. In a further embodiment, an additional gaseous component can also be introduced via valves 14, 14′ in this process similar to the plasma treatment. Similar to the process chamber from FIG. 5a, a suction system and/or a vacuum system 11 as well as an airlock 10 are also present here.

[0169] In alternative embodiments of process chamber 9′, radiation source(s) 15 can also be IR-light and/or laser. Radiation source 15 can, as required, comprise a plurality of (parallel) light sources as well as just one single radiation source. This radiation source can be designed to be mobile. In a further embodiment, the frame structure is treated in particular with a laser after singulation of the components.

[0170] According to the invention, use is preferably made at least predominantly, preferably exclusively, of coherent photon sources, in particular microwave sources, preferably masers, or lasers constituted as coherent photon sources for visible, IR, UV and x-ray light. With a low fluence (radiation energy per unit area with constant pulse duration) below the ablation limit, changes in the chemical composition of the frame material surface can thus be achieved.

[0171] The encapsulated and singulated components, in particular the frame structures, are exposed to a predefined wavelength and/or power and/or pulse duration, wherein the predefined process parameters are preferably matched to the given material. This embodiment is advantageous, since the penetration depth and the processes can be influenced by the wavelength and/or the pulse times and/or the laser power. The photon sources can be operated in a continuous operation or preferably in a pulsed operation. The pulse times are in particular less than 1 s, preferably less than 1 ms, still more preferably less than 1 μs, most preferably less than 1 ns. The times between successive pulses are preferably greater than 1 ms, more preferably greater than 10 ms, most preferably greater than 1 s. Tilting of receiving device 13 also enables, where required, an optimised radiation access to the (lateral) frame structures of the singulated and encapsulated components.

[0172] In a special embodiment, process chamber 9, 9′ according to the invention is arranged as a module in a cluster system. The module, in which the process chamber according to the invention is located for the post-treatment of the encapsulated components, can, depending on requirements, be evacuated preferably independently of the (vacuum) cluster system, to a pressure of less than 1 bar, preferably less than 10.sup.−3 mbar, more preferably less than 10.sup.−5 mbar, most preferably less than 10.sup.−8 mbar.

[0173] After unloading the processed encapsulated components from the process chamber, the latter can be removed individually from the dicing tape.

[0174] In particular, the material of the frame structure or adhesive material and the post-treatment process are matched to one another in such a way that the desired material conversion to form dense SiO.sub.x takes place in an optimised manner. An advantage of the invention includes increasing by the post-treatment the hermeticity, and therefore the quality and useful life of the encapsulated components produced with adhesive as a bonding layer in the W2 W process.

LIST OF REFERENCE NUMBERS

[0175] 1 Product substrate/carrier substrate [0176] 1o Substrate surface [0177] 1f, 1f′ Exposed surface [0178] 2, 2′ Components [0179] 3, 3′ Contacts and/or electrically conductive connections [0180] 4, 4′, 4″, Frame structure 4′″ [0181] 4o Outer surface of the frame structure on the encapsulated and singulated component structures [0182] 5 Cover substrate [0183] S, S′ Intersection line [0184] H Height difference between structure of frame structure and component structure [0185] 6 Encapsulated and singulated component [0186] 7 Encapsulated and singulated component after the post-treatment of the (frame structure) surfaces [0187] 8 SiO.sub.x surface layer [0188] 9, 9′ Process chamber [0189] 10 Airlock [0190] 11 Suction and/or vacuum system [0191] 12 Table [0192] 13 Receiving device for singulated and encapsulated components (dicing frame, substrate, basket, etc.) [0193] 14, 14′ Gas valve [0194] 15 Radiation source(s) (IR-light and/or UV-light and/or laser etc.) [0195] 16 Supply of reactive particles from a downstream plasma reactor [0196] 17 (O.sub.2)-plasma