DE19718517A1 - Microelectronic component with diamond layer - Google Patents

Abstract

In a microelectronic component with an external surface diamond layer produced by gas phase deposition, the diamond layer (34) is located on the component surface (6) remote from the original growth substrate (35) and has edges exhibiting an abrupt thickness change to \-10 (preferably \-50)% of the diamond layer thickness. Also claimed is a process for diamond application onto a microelectronic component by (a) depositing the component (33) on a growth substrate (35), especially of single crystal silicon, optionally using material from the growth substrate; (b) selectively providing the substrate surface (6) with growth seeds for the diamond layer; and (c) carrying out gas phase deposition of diamond in the seeded region. Preferably, the gas phase deposition is carried out by CVD, especially by an arc-jet process.

Description

The invention relates to a microelectronic component with an egg ner diamond layer and a method for its production according to the preamble of claim 1 and claim 8, respectively both from the generic DE 44 27 715 C1 emerges as known.

DE 44 27 715 C1 is based on a method for Manufacture of a composite substrate known in which on a Growth substrate first shoot a diamond layer directly that will. Then a semiconductor on the diamond layer layered. On the semiconductor layer or under the functional assistance of the semiconductor layer will be on then several microelectronic components arranged. As Components are individual components such as Di odes, transistors, capacitors, inductors etc. but also Component groups, such as. Integrated circuits (IC), Ver stronger to understand memory etc. So that when growing up Semiconductor layer the number of defects below the construction parts, i.e. in the area of the component root, is reduced, the diamond layer has edges outside the component roots on. Through these edges arranged between the components which the diamond layer is at least thinner than in the area of Component roots, the quality of the following is checked different semiconductor layer above the diamond layer improves. Through this quality improvement of the semiconductors layer is at least in the area of the component roots shot rate in the production of components is reduced. After known manufacture of the components and their subsequent  The components will then be in contact with each other special by sawing, if necessary before or after separating the growth substrate by selective etching can be removed. Despite this improvement, the end is shot rate still high, so these components still are very expensive. Furthermore, the manufacture of such Edging diamond layer technologically complex and therefore also expensive. Furthermore, the reject rate is deswe still high, because it is still due to tension, for example there is a detachment of the diamond layer from a component.

The object of the invention is the underlying micro electronic component and the manufacturing process for it To improve component in that the manufacturing costs for a microelectronic component with the best possible quality the component is lowered.

The task is invented for an underlying component appropriately by the characterizing features of claim 1 or with regard to the method with the characteristic method resolved steps of claim 8. Despite the ge dangerous high temperature when separating in particular po lycrystalline diamond on the already finished and directly on the growth substrate manufactured in a known manner part, the reject rate is reduced, reducing the overall cost for the production of the components are reduced. Furthermore, that is Manufacturing process for the components known per se and also very inexpensive to implement, the same applies to the parting the diamond layer, on its structure (edges) no longer must be respected. Although it can, despite the division of the the component arranged diamond layer in several individual and diamond districts spatially separated from each other due to, for example, tensions between the diamond regions and the substrate surface, etc. - to detach slide not come from the component. However, this affects only a few ge of the diamond districts, so that the diamond layer as such in  their function as electrical insulation and good thermal conductivity layer remains intact.

Advantageous embodiments of the invention are the dependent claims Chen removable. Otherwise, the invention is based on in the embodiments shown in the figures. It shows

Fig. 1 is a member having disposed thereon and from Diamantbe circuses formed diamond layer,

Fig. 2 is a schematic diagram of a CVD apparatus for deposition of diamond on substrates,

Fig. 3 is a detailed drawing of a substrate holder,

Fig. 4 is a detail drawing of a nozzle for the CVD method using Arcjet,

Fig. 5 is a detailed drawing of a cover.

In Fig. 1 a section is shown of a transverse to the flat side of a guided from a largely made of monocrystalline semiconductor material in particular silicon or gallium arsenide substrate 35 tums wax-section of a micro-electronic component 33 according to the invention.

The component 33 is produced using the material of the growth substrate 35 in a functional manner. A functional use is to be understood in such a way that, in the area of a component 33, the growth substrate 35 has, for example, one or more buried functional layers 38 . The buried functional layers 38 can be, for example, n- or p-doped semiconductor layers or intrinsically conductive semiconductor layers, the doping being carried out in the usual way, in particular by diffusion and / or ion implantation.

On the buried functional layers 38 , electrically insulating insulating layers 37 are arranged which, for example, consist of SiO ₂ or undoped diamond and which are expediently deposited epitaxially from a gas and / or liquid phase.

In the plane of the flat side of the growth substrate 35 , conductor tracks 39 are arranged between the insulation layer 37 and the buried functional layers 38 , which are preferably made of aluminum.

Above an insulation layer 37 a further functional layer 36 is arranged, which are advantageously separated from a gas phase and / or a supersaturated liquid in a generally known deposition process.

The growth substrate 35 and the functional layers 36 , 37 and 38 of the component 33 arranged directly on it form a substrate 2 with an outer substrate surface 6 .

Individual diamond regions of the polycrystalline diamond layer 34 are arranged on the substrate surface 6 and also at least partially above half of conductor tracks 39 . The diamond layer 34 is deposited in particular from a gas / plasma phase in polycrystalline form by means of a CVD arcjet process.

The diamond areas of the diamond layer 34 are spatially separated from each other, so that even after the deposition of the diamond layer 34, the substrate surface 6 of the substrate 2 is still partially exposed. In particular, such exposed areas of the substrate surface 6 are seen at contact points 40 at which the component 33 is electrically contacted.

The division of the diamond layer 34 into individual spatially separated diamond regions, among other things, at least reduces the tension between the diamond layer 34 and the substrate surface 6 of the component 33 arranged underneath.

In Fig. 2 is a schematic diagram of a device for loading coating a substrate 2 , in the present invention, a composite structure of a microelectronic component, with a diamond layer, namely in the manner of a Supersonic nic DC arcjet system. It is a CVD system for 6-inch wafers with a power range between 1 and 5 kW.

The cylindrical reactor 10 (recipient) consists of non-stainless steel in a double-walled design, whereby a cooling treatment by means of water is possible, which is connected via a water connection 13 to the reactor.

In order to evacuate the interior of the reactor 14 , the device has a pump system 15 with three individual pumps, which is provided with a pressure control 31 . The achievable pressure is approx. 10 ^-3 mbar. A rotary vane pump and two Wälzkol benpumpen are provided as pumps.

Furthermore, the device has a gas supply system 16 with which the gases required for a plasma (argon and water) and the process gases required for diamond growth, in particular oxygen and methane, can be introduced into the reactor interior 14 in a targeted manner.

To determine the temperature of the substrate 2 above 400 ° C., it can be useful if the device has a thermal pyrometer.

A substrate holder 1 is arranged within the preferably evacuable reactor 10 and is provided for receiving a pretreated and already germinated substrate 2 in a planar and heat-conductive manner. The physical design of the substrate holder 1 is shown in Fig. 3.

The substrate holder 1 has, inter alia, a solid, rotationally symmetrical and cross-sectionally T-shaped block 17 made of Cu. In the middle of the block, a thermocouple 12 , which is preferably made of chrome / aluminum (Cr / Al), is passed through for measuring the temperature of the substrate 2 . The free area of the larger cross section of the block 17 - hereinafter referred to as substrate side 3 - faces the substrate 2 . In order to be a thinner cross-section, a heat sink 18 made of Cu is arranged in close and heat-conducting contact. The cooling body 18 has channels 19 for a cooling liquid, in particular water, through which fluid can flow, which are connected to a cooling system 32 .

Due to the good thermal conductivity copper and inside the coolant flow can with such a substrate holder 1 a disposed thereon and conductive in particular with a good heat-layer, for example. Of conductive silver, provided substrate 2 during a coating with diamond to temperatures clotting ger 450 ° C to be tempered. However, with such cooling, the substrate 2 , at a maximum water temperature of approx. 368 ° K, can only be tempered between 400 ° C and 500 ° C. Furthermore, the possible temperature control is also limited to a range of approx. 85 ° C.

Instead of the conductive silver, a narrow gap can also be arranged between the substrate 2 and the substrate side, through which a gas flows, the tempering then being carried out by convection. Since this gap is usually below 1 mm, this case is also to be understood as direct heat conduction in the sense of this application.

This is for a coating at lower temperatures, such as especially when it comes to diamond coating from ferti against microelectronic components and in particular from microelectronic with aluminum conductor tracks Components are necessary, at least partially unsatisfactory.  

In order to improve this circumstance, the substrate holder 1 according to the invention has on its substrate side 3 an air-conditioning disc 4 through which a tempering gas flow flows, on the inside (flow channels 11 ), on which the substrate 2 is arranged. Between the climate disc 4 and the substrate side 3 , a heat insulating layer 20 may be arranged.

Since the air plate 4 at least indirectly abutting with webs 21 on the substrate side 3, the heat between the air is disc 4 and the substrate side 3 of the block 17 only contact area directed, directly. The heat transfer takes place over the entire area between the block 17 and the heat sink 18 .

Further, a ridge-shaped design of the air washer 4 wherein the tempering gas, is passed in particular through the air forming between the substrate side 3 and the air disc 4 channels 22 is possible.

All possibilities and also their combinations have in common that the total dissipation of heat in the substrate holder 11 is less compared to a heat flow with a full-surface support. This is advantageous because, in unfavorable cases, the cooling effect can become too great, as a result of which the substrate temperature then becomes too low.

Although the spec. Heat capacity of the tempering gas in about only 25% of the spec. Heat capacity of water, a substrate 2 at least indirectly arranged on the climate disk 4 and thus on the holder surface 5 of the substrate holder 1 can surprisingly be tempered to temperatures below 400 ° C., preferably less than 350 ° C. and particularly preferably less than 300 ° C. .

As a result, microelectronic components in a diamond coating are at most slightly, in particular negligibly, loaded. Due to the lower temperature when coating microelectronic components with diamond, the reject rate is significantly reduced. Furthermore, the temperature interval within which the substrate 2 can be tempered is also increased.

Although the advantage of the substrate holder 1 according to the invention is described using an Arcjet method, it can also be used in the same way for all other CVD methods.

The substrate 2 opposite to a nozzle 23 is disposed, the coating for producing a diamond substrate 2 with the gas jet is suitable. Such nozzles 23 were originally developed for space travel, the dissociation of the carrier gas from hydrogen representing a high loss in this use case. . In contrast, the degree of dissociation of the carrier gas, which is referred to as process or precursor gas in the epitaxy of diamond from the gas phase, is important.

The structure of the nozzle 23 is shown in Fig. 4. The nozzle 23 has an axially and centrally inner and axially movable union cathode 9 , which has a melting point of 3410 ° C. and consists of a tungsten alloy with 2% thorium. The cathode 9 is designed in the form of a nozzle needle and at the same time acts as a closing needle of the nozzle opening 24 .

In the area approximately the center of the cathode 9 , a gas inlet opening 25 is arranged for one or possibly several later forming a plasma gas, in particular hydrogen. At the outlet side of the nozzle 23 Be an anode 8 is arranged. The actual nozzle opening 24 is formed by an insert, the so-called con strictor 26 , which belongs to the anode 8 . In the area of the constrictor 26 , the electric discharge arc required for the plasma formation is stabilized.

In the region of the needle tip of the cathode 9, ie the closure of the nozzle orifice 24, a concentrically arrange the cathode 9 th Injektorscheibe 27 is arranged as a gas inlet for one or more gases of the plasma, while outside of the nozzle opening 24 is a Injektorscheibe 28 for the process gases (CH ₄ and O ₂ ) is arranged.

The anode 8 of the nozzle is dome-shaped and is arranged in the region of the nozzle opening concentrically around the cathode 9 . The anode 8 absorbs the electrode current and is exposed to strong thermal loads. In order to reduce the loads, the contact area of the anode 8 is greatly increased, which increases the pressure gradient in the expansion area. The high pressure gradient increases the free path length and the contact area of the anode 8 is smeared.

Between the inlet and outlet of the nozzle 24 , the pressure drops from approximately 1 bar to approximately 0.3 mbar, that is, between 3 and 4 decades. The plasma gas formed is greatly expanded, whereby the plasma, which was originally approx. 20,000 to 30,000 ° K hot, is cooled to approx. 5,000 ° K. The static pressure at the nozzle outlet is greater than the pressure in the reactor. The jet speed reaches about one to three times the speed of sound due to the strong expansion of the plasma.

The mode of operation of the nozzle 23 - that is to say the arcjet - is briefly discussed below. An electric field is established in the nozzle 23 between the cathode 9 and the anode 8 . The electrons coming from the cathode 9 are strongly accelerated. Part of the kinetic energy of the electrons is released via collision processes to the gas that later forms the plasma - hereinafter referred to as hydrogen - which causes the hydrogen to ionize and dissociate.

In the middle of the needle-shaped cathode 9 , the hydrogen is introduced tangentially to the cathode 9 , whereby the hydrogen is swirled. Because of the converging geometry of the gas space between the anode 8 and the housing surrounding it, the hydrogen is accelerated and comes into contact shortly before the constrictor 26 between the discharge arc emanating from the cathode tip. The relatively high pressure in the area of the constrictor 26 leads to a high impact rate and thus to a good thermal contact between the electrodes of the discharge arc and the hydrogen and to the formation of the plasma. After the nozzle 23 , the plasma jet expands so that its energy density decreases.

The process or precursor gas is introduced into the rapidly flowing plasma from the front, that is to say the outflow-side, injector disc 28 , the energy of which increases in the plasma and is guided by the gas flow in the direction of the substrate 2 , where it deposits as a diamond.

A cover 7 is arranged between the nozzle 23 and the substrate surface 6 to be coated, which cover is shown in more detail in FIG. 5. The plate-like cover 7 has approximately a triangular shape. The cover 7 is held pivotably about a pivot axis 29 aligned parallel to the surface normal of the substrate 2 . At an edge region, the cover 7 has a preferably circular coating opening 30 which is adapted to the shape of the substrate. At the other area, the same distance from the pivot axis as the coating opening. Except for the coating opening 30 , the cover is designed to be closed, the diameter of the coating opening 30 preferably corresponding approximately to the diameter of the substrate 2 , in particular being approximately larger.

The germinated substrate surface 6 of the substrate 2 is covered with the cover 7 before the plasma is ignited and is only removed again after the plasma and / or the coating-effecting gas stream made of precursor material has stabilized. The time of covering after the ignition of the plasma is between 5 and 30 minutes, preferably between 10 and 20 minutes, particularly preferably about 15 minutes. The cover 7 is expediently cooled, at least while the substrate 2 is being covered . The cooling he expediently follows by means of a liquid coolant, preferably water, that flows through channels which are arranged in the cover.

Furthermore, it is advantageous to switch on before igniting the plasma only an inert gas, preferably an inert gas, especially before draws argon (Ar) in gaseous form between an anode and a cathode inflow in gaseous form, ignite the argon and out of it To generate Ar plasma. In the Ar plasma is during an over lead phase hydrogen initiated, ignited and as plasma Ma material used, the argon after the transition phase is provided.

In this procedure, the process gas used as the precursor material is flowed into the plasma at the earliest with the H ₂ , in particular early after the transfer phase, it being particularly useful at lower temperatures, together with the process gas used as the precursor material Intake oxygen (O ₂ ).

The method for producing a microelectronic component 33 according to the invention is discussed below. First, the cleaned and pretreated growth substrate 35 is installed in the reactor 10 and the reactor 10 is evacuated. After evacuation, the component 33 is produced in a known manner with regard to its structure, in particular its layer structure, with the aid of the growth substrate 35 by means of an epitaxial method. As already mentioned, the growth substrate 35 and the functional layers 36 , 37 and 38 of the component 33 arranged directly on it form the substrate 2 , which is to be provided on its outer substrate surface 6 with the diamond layer 34 .

After the production of the substrate 2 , an immunization layer, for example a AZ 4533 photoresist with a layer thickness of 1 to 5 μm, is applied to the substrate surface 6 that repels from the growth substrate 35, for example by means of a lithographic method C is baked. Germination of the substrate surface 6 is prevented or at least made more difficult in the area of the immunization layer. An aggravation is to be understood here such that, after germination, the germ density present in these areas is too high for the formation of a closed diamond deposition.

Instead of the mentioned procedure for germination other types of selective germination are also possible. That's the way it is especially possible in the places where the slide layer should be arranged to apply a photoresist, the is mixed with growth nuclei for the diamond layer. Here So there is no suppression of germination, but rather given by the photoresist.

After the application of the immunization layer, the remaining free substrate surface 6 is germinated. The substrate surface is preferably germinated mechanically and / or by using ultrasound.

In ultrasonic germination, the substrate is placed in a tank with a diamond-water suspension and irradiated with ultrasound. Here, the substrate surface 6 is preferably provided with the growth nuclei in the area outside the immunization layer.

In the mechanical seeding a sunk into mud of isopropanol and diamond powder to the substrate surface 2 is applied and rubbed in the grains of the diamond powder into the substrate surface 6 and is polished. Here too, the substrate surface 6 is preferably provided with the growth nuclei outside the immunization layer.

After germination, the immunization layer is removed and the diamond layer 34 - as already described - is deposited. In particular, the immunization layer can be removed during or before the deposition of the diamond layer 34, for example by dissolving in acetone incinerators in the oxygen plasma, by plasma etching or purely thermally.

The table below shows the test parameters for various substrate materials and their results. All substrates were pretreated in a comparable manner, in particular cleaned in particular and germinated in accordance with the method described later; the germ density and the size of the growth germs were comparable. The following designations are used for the table:
No .: number of the sample,
Sub .: material of the substrate, the microelectronic component being a MOSFET in SI / SiO ₂ technology, which was still fully functional before and after the coating,
CH ₄ / H ₂ : ratio of methane to hydrogen in percent [%],
O ₂ / CH ₄ : ratio of oxygen to methane in percent [%],
H ₂ flow: gas flow of hydrogen in [s / m],
I _D : current flow in the nozzle between the anode and the cathode in amperes [A],
T _S : substrate temperature during diamond deposition in [° C],
P _D : average power on the Arcjet in [kW],
t _W : process duration in [min],
d _S : middle layer thickness of the diamond layer in [µm],
v _S : growth rate or rate in [µm / h] and
Adhesion: Adhesion of the diamond layer on the respective substrate.

As can be seen from the table, all substra high growth speeds or rates are achieved, compared to the growth known at these temperatures speeds or rates are about a decade higher.

All of the samples listed showed good diamond adhesion layer with the substrate. The liability with the So-called scotch tape test (ST test) determined. With this Let's test the diamond layer with an adhesive strip (brand name Tape or scotch). Disengages when the Adhesive tape does not remove the diamond layer from the substrate liability considered sufficient.

The method according to the invention or the one according to the invention Device can be used in particular for diamond coating components and tools used for tribological purposes will. It is also used for diamond coating of cutting or cutting tools, in particular of cutting tools such as indexable insert, drill, etc. possible Lich. It is particularly suitable for components and tools that are made of tungsten carbide with Co (WC-Co). In particular Wise can also use microelectronic components that have a compo Sit structure coated with diamond in an acceptable time without their functionality being jeopardized. Since the Be stratification takes place at temperatures below 450 ° C This can also be conveniently found for microelectronics  cal components with metallic, especially aluminum manufactured, conductor tracks are provided.

The method according to the invention and the front according to the invention are also used for diamond coating of components and Cheap tool made of light metals and / or their Le alloys, in particular aluminum and / or magnesium, and / or of semiconductor materials, in particular silicon, and / or Metal alloys, especially WC-Co, are made.

Claims (24)

1. Microelectronic component with a surface delimiting the component on the outside and surface deposited from a gas phase on an upper surface, characterized in that the diamond layer ( 34 ) on the surface of the component facing away from the original growth substrate ( 35 ) - in the following Substrate surface ( 6 ) called - is arranged and that the diamond layer ( 34 ) has edges on which the layer thickness changes by at least 10% of the layer thickness of the diamond layer ( 34 ), in particular at least 50% of the layer thickness of the diamond layer ( 34 ), abruptly changes . 2. Component according to claim 1, characterized in that the diamond layer ( 34 ) has isolated and spatially separated diamond regions with respect to their surface. 3. Component according to claim 1, characterized in that the diamond layer ( 34 ) is network-like and that the diamond layer ( 34 ) has elevations or depressions. 4. Component according to claim 1, characterized in that the diamond layer ( 34 ) outside of already done and / or intended contact points ( 40 ) of the components ( 33 ) has edges and that the component ( 33 ) in the area of the contact points ( 40 ) is free of diamond or has diamond in a negligible amount. 5. Component according to claim 1, characterized in that the diamond layer ( 34 ) is polycrystalline. 6. Component according to claim 1, characterized in that the diamond layer ( 34 ) protrudes at least in regions over the edge of the component ( 33 ). 7. The component according to claim 1, characterized in that the growth substrate ( 35 ) from a largely monocrystalline semiconductor material, in particular silicon (Si) or gallium arsenide (GaAs). 8. A method for applying diamond on a microelectronic component in which a growth substrate, in particular made of monocrystalline silicon, is provided with a slide layer from a gas phase and with the microelectronic component, characterized in that on the growth substrate ( 35 ) and optionally using the material of the growth substrate ( 35 ), the component ( 33 ) is deposited first, that the substrate surface ( 6 ) is then selectively provided with growth nuclei for the diamond layer and that after the germination in the area of growth Germination is carried out a vapor deposition of diamond. 9. The method according to claim 8, characterized in that the substrate surface ( 6 ) of the components is partially provided with an immunization layer, which at least complicates nucleation for diamond, preferably prevented, and that after the immunization in areas, the substrate surface ( 6 ) in Area outside the immunization layer is provided with growth nuclei for the later diamond layer ( 1 ). 10. The method according to claim 8, characterized in that the seeding is carried out mechanically and / or by sonicating a growth nuclei for the later diamond layer ( 1 ) containing liquid with ultrasound. 11. The method according to claim 8, characterized in that for seeding on the substrate surface ( 2 ) a vorzugwei se slurried diamond powder with a grain diameter up to 200 microns in particular is applied and that the grains of the diamond powder mechanically rubbed into the substrate surface ( 2 ) or be polished in. 12. The method according to claim 8, characterized, that the immunization layer before and / or during the gas phases the diamond is removed. 13. The method according to claim 8, characterized in that the diamond layer ( 34 ) is provided with edges which have an edge height which is at least 10% of the layer thickness of the diamond layer ( 34 ), preferably at least 50% and particularly preferably at least 90% of the Layer thickness of the diamond layer ( 34 ). 14. The method according to claim 8, characterized in that the diamond layer ( 34 ) is provided with elevations made of diamond and / or diamond-like material or with depressions. 15. The method according to claim 8, characterized in that the diamond layer ( 34 ) is divided into individual and spatially separate diamond areas. 16. The method according to claim 8, characterized in that the diamond layer ( 34 ) by means of CVD (chemical-vapor-de position), in particular by means of an arcjet process on the component ( 33 ) is deposited. 17. The method according to claim 8, characterized in that the diamond layer ( 34 ) is applied polycrystalline. 18. The method according to claim 8, characterized in that the diamond layer ( 34 ) by means of a plasma CVD process, in particular an arcjet process, at temperatures below 450 ° C, preferably below 350 ° C and particularly preferably below 300 ° C is deposited. 19. The method according to claim 8, characterized in that the deposition of diamond is carried out by means of an arcjet process that a gas, preferably a noble gas, and particularly preferably argon (Ar) is passed to generate a plasma, then electrically ignited and from this a plas ma is generated that the H _{2 is} introduced into the inert gas plasma during a transition phase, ignited and used as a plasma material, and that the inert gas is turned off after the transition phase. 20. The method according to claim 19, characterized in that oxygen (O ₂ ) is flowed into the reactor at least together with the gas used as the precursor material. 21. The method according to claim 19, characterized in that before the ignition of the plasma the germinated substrate surface ( 6 ) before the plasma and / or in front of a substrate ( 2 ) with diamond coating acting gas stream of precursor material is at least indirectly covered and after stabilization of the plasma and / or the coating gas flow from the precursor material of the cover is removed. 22. The method according to claim 21, characterized, that after the ignition of the plasma, the cover between 5 and 30 min, preferably between 10 and 20 min, particularly preferred is maintained for about 15 minutes. 23. The method according to claim 21, characterized, that the cover at least while covering the substrate cooled, in particular through which a liquid coolant flows will. 24. The method according to claim 8, characterized in that the substrate is tempered to a temperature of less than 450 ° C, preferably less than 350 ° C and particularly preferably less than 300 ° C during the deposition of the diamond layer ( 34 ).