Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
  • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
  • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
  • H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
  • H01L21/306—Chemical or electrical treatment, e.g. electrolytic etching
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/02002—Preparing wafers
  • H01L21/02005—Preparing bulk and homogeneous wafers
  • H01L21/02032—Preparing bulk and homogeneous wafers by reclaiming or re-processing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J19/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
  • B01J19/10—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing sonic or ultrasonic vibrations
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
  • H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
  • H01L21/76—Making of isolation regions between components
  • H01L21/762—Dielectric regions, e.g. EPIC dielectric isolation, LOCOS; Trench refilling techniques, SOI technology, use of channel stoppers
  • H01L21/7624—Dielectric regions, e.g. EPIC dielectric isolation, LOCOS; Trench refilling techniques, SOI technology, use of channel stoppers using semiconductor on insulator [SOI] technology
  • H01L21/76251—Dielectric regions, e.g. EPIC dielectric isolation, LOCOS; Trench refilling techniques, SOI technology, use of channel stoppers using semiconductor on insulator [SOI] technology using bonding techniques
  • H01L21/76256—Dielectric regions, e.g. EPIC dielectric isolation, LOCOS; Trench refilling techniques, SOI technology, use of channel stoppers using semiconductor on insulator [SOI] technology using bonding techniques using silicon etch back techniques, e.g. BESOI, ELTRAN

Definitions

• a method of removing material fragments present on the surface of a multi-layer structure is a method of removing material fragments present on the surface of a multi-layer structure.
• the present invention relates to the field of producing multilayer semiconductor structures (also called composite structures or "multilayer semiconductor wafers" in English) made by transfer of at least one layer on a final substrate.
• a layer transfer is obtained by bonding, for example by molecular adhesion, a first plate (or initial substrate) on a second plate (or final substrate), the first plate being generally thinned after bonding.
• the transferred layer may further comprise all or part of a component or a plurality of microcomponents.
• the present invention relates to the problem of material fragments that appear on the exposed surface of the transferred layer during the manufacture of a multilayer structure formed by gluing.
• This phenomenon of contamination has in particular been observed following a chemical etching step carried out on the first plate of a multi-layer structure, for example during the thinning of this first plate, and particularly when it does not occur. It has not been possible to completely stabilize the bonding interface.
• the technique frequently used in the manufacture of multilayer structures to clean the surface of a transferred layer after a chemical thinning step is to perform a rinsing (or cleaning) step by means of a pressurized jet.
• a jet of water or any rinsing solution
• spray cleaning a technique sometimes referred to as "spray cleaning".
• EP1662560 describes a method of treating an SOI plate having on its front face a peripheral rim bordering a circular recess. This method comprises in particular the elimination of this edge by polishing by means of a machine provided for this purpose.
• This polishing machine comprises in particular a tank in which there is a rinsing solution. To clean the plate after polishing, the treated plate is immersed in the rinsing solution and ultrasonic waves are propagated in the solution.
• the present invention proposes a method for removing fragments of material present on the exposed surface of a first layer bonded to a second plate, the fragments to be eliminated having a size greater than 2 ⁇ m, the method comprising a step of immersing at least the first layer in a liquid solution and a step of propagation, in the solution, of ultrasonic waves, the frequency and the power of the ultrasonic waves being adapted to create a cavitation effect in the liquid solution to remove fragments from the exposed surface.
• the size of a fragment may correspond in particular to its length, its width or its diameter.
• the method of the invention makes it possible to eliminate the fragments of relatively large material deposited on the surface of a multilayer structure during its manufacture, and in particular after a chemical etching.
• the method is also advantageous in that the application parameters (ultrasound frequency, ultrasonic power, etc.) are controllable and reproducible. This method thus makes it possible to industrialize the cleaning of multilayer structures having undergone chemical etching, for example during a thinning step.
• the fragments of material come, for example, from a preliminary chemical etching step performed on the first layer.
• the frequency and power of the ultrasonic waves are preferably adjusted according to the viscosity of the liquid solution. As indicated in more detail later, it is thus possible to optimize the efficiency of the disposal method of the invention.
• the liquid solution may be a rinse solution.
• the liquid solution may be an etching solution.
• the process of the invention directly in a bath of an etching solution used to etch the first plate of the multilayer structure chemically.
• the etching solution serves as a propagation medium for the ultrasonic waves. In this way, only one tray and one liquid solution is required to effect chemical etching and to remove material fragments deposited on the surface of the first plate.
• the liquid solution may further comprise at least one of the following solutions; a solution of TMAH, a solution of KOH, and a solution of H 3 PO 4 .
• the fragments to be eliminated correspond to fragments of the first plate formed during a prior step of etching the first plate.
• the fragments of material to be removed may comprise at least one of the following residues: oxide residues from an oxide layer located at least at the bonding interface between the first plate and the second plate, silicon residues from the peripheral edges of the first plate and microcomponent residues from the peripheral edges of the first plate.
• the invention also relates to a method of manufacturing a multilayer structure comprising the following successive steps:
• thinning of the first plate comprising at least one step of chemical etching of the first plate
• the method being characterized in that it further comprises, after the chemical etching step, the removal of material fragments present on the exposed surface of the first plate according to one of the described embodiments of the removal method. above.
• the method may further include a step of oxidizing the first plate prior to the bonding step.
• This additional oxidation step allows in particular to place an oxidation layer at the bonding interface between the first plate and the second plate so as to facilitate the bonding of the two plates.
• the chemical etching step is carried out in a bath of an etching solution, and the liquid solution used during the removal of the fragments corresponds to the etching solution.
• FIGS. 1A to 1D are schematic views showing the realization of a SOI multilayer structure
• FIG. 2 represents, in the form of a flowchart, the main steps of the embodiment method illustrated in FIGS. 1A to 1D;
• FIG. 3 shows schematically a method of removing fragments of material according to the invention.
• the present invention generally applies to the removal of unwanted material fragments from the exposed surface of a multilayer structure during its manufacturing process.
• a multilayer structure or composite structure is produced by gluing a first plate to a second plate constituting the support of the first plate.
• the plates composing a multilayer structure are generally in the form of slices or "wafers" with a generally circular outline and may have different diameters, in particular diameters of 100 mm, 200 mm or 300 mm. However, it can also be plates of any shape, such as a rectangular plate, for example.
• These plates preferably have a chamfered edge, namely an edge comprising an upper chamfer and a lower chamfer. These chamfers are generally rounded. However, the plates may have chamfers or edge-shaped of different shapes such as a bevel shape.
• FIGS. 1A to 1B An example of a method of manufacturing a multilayer structure is now described with reference to FIGS. 1A to 1B.
• 111a is formed by assembling a first plate 108 with a second plate 110.
• the first plate 108 corresponds to an SOI structure comprising a buried oxide layer 104 interposed between two silicon layers (ie, the upper layer 101 and the lower layer 102).
• the second plate 110 is here in sapphire.
• the first and second plates 108 and 110 here have the same diameter. They could, however, have different diameters.
• At least one of the two plates 108 and 110 has been oxidized before bonding.
• This oxidation makes it possible in particular to have an oxide layer sandwiched between the two plates once the bonding has been performed.
• This oxidation is carried out by means of a thermal treatment in an oxidizing medium.
• the first plate 108 is oxidized before bonding, so as to form an oxide layer 106 over the entire surface of the first plate.
• a layer of bonding oxide is thus found at the bonding interface between the first plate 108 and the second plate 110 and allows a better bonding between them.
• the first plate 108 has a chamfered edge, namely an edge comprising an upper chamfer 122a and a lower chamfer 122b.
• the second plate 110 similarly has an edge comprising an upper chamfer 124a and a lower chamfer 124b.
• step E1 the assembly of the first plate 108 and the second plate 110 is achieved by means of the molecular adhesion technique well known to those skilled in the art.
• bonding techniques can however be used, such as anodic bonding, metallic bonding, or adhesive bonding.
• the principle of molecular bonding is based on the direct contact of two surfaces, that is to say without the use of a specific material (glue, wax, solder, etc.).
• a specific material glue, wax, solder, etc.
• Such an operation requires that the surfaces to be bonded are sufficiently smooth, free of particles or contamination, and that they are sufficiently close together to allow initiation of contact, typically at a distance of less than a few nanometers.
• the attractive forces between the two surfaces are high enough to cause molecular adhesion (bonding induced by all attractive forces (Van Der Waals forces) of electronic interaction between atoms or molecules of the two surfaces to be glued).
• the first plate 108 may comprise microcomponents (not shown in the figures) at its bonding face with the second plate 110, particularly in the case of the three-dimensional integration technology of components (3D-integration) which requires the transfer of one or more layers of microcomponents on a final support, or in the case of transfer of circuits such as in the manufacture of illuminated imagers on the rear face.
• microcomponents not shown in the figures
• the composite structure 111a then undergoes a moderate annealing of reinforcement of the bonding interface (for example at 400 ° C. for 2 hours), the purpose of which is to reinforce the bonding between the first plate 108 and the second plate 110 (step E2) .
• a moderate annealing of reinforcement of the bonding interface for example at 400 ° C. for 2 hours
• the first plate 108 is generally thinned so as to form a transferred layer of a predetermined thickness (for example, about 10 ⁇ m) on the support plate.
• This thinning operation generally comprises a chemical phase.
• FIGS. 1C and 1D illustrate an exemplary step of thinning the first plate 108.
• the thinning step generally comprises two distinct substeps.
• the first plate 108 is first thinned mechanically using a grinding wheel or any other tool able to mechanically use the material of the first plate ("grinding" in English) (step E3).
• This first sub-step thinning eliminates most of the upper layer 102 so as to retain a residual layer 112 ( Figure 1C).
• step E4 A second sub-step of thinning corresponding to a chemical etching of the residual layer 112 (step E4) is then carried out.
• This step consists of placing the structure composite 111b in a bath comprising an etching solution 126 ( Figure 1D).
• a solution of TMAH is used to etch the silicon of the first plate 108.
• Other etching solutions may however be envisaged, these being chosen in particular according to the composition of the first slimming plate.
• a solution of KOH or H 3 PO 4 can be used depending on the situation under consideration.
• the buried oxide layer 104 interposed between the layers 101 and 102 of the first plate serves as a stop layer during chemical etching.
• the chemical etching is thus interrupted at the level of the oxide layer 104.
• the chemical etching thus makes it possible to eliminate the residual layer 112 remaining after the mechanical thinning.
• the chamfered edges of the first and second plates cause adhesion problems at the periphery between these two plates.
• an annular portion at the periphery of the first plate 108 situated in the vicinity of the lower chamfer 122b has a poor bonding (or even complete absence of bonding) on the second plate 110.
• the reduction of the thickness of the first plate during the mechanical and chemical thinning steps then significantly weakens the edges of the first plate in the vicinity of the lower chamfer 122b.
• the lateral etching action during chemical etching further weakens the unglued (or poorly bonded) peripheral area of the first plate. This increased embrittlement generally leads to uncontrolled breaks at the periphery of the first thinned plate. These breaks cause the formation of debris or fragments of material that may then be deposited on the exposed surface of the first thinned plate 116.
• fragments containing oxide and possibly silicon can pollute the exposed surface of the first thinned plate 116 ( Figure 1D).
• Breaks occur in particular during chemical etching during thinning, and when the remaining thickness of the first plate no longer supports its own weight periphery. It appears that once this critical stage is reached, a peripheral portion of the first plate in the vicinity of the lower chamfer 122b collapses, thereby producing undesirable material fragments 118.
• these fragments of material 118 are generally of relatively large size. Typically, these fragments have a size of at least 2 ⁇ m. The large size of these fragments is explained in particular by their mechanism of formation by collapse as described above. Because of their large size, these fragments can not be effectively removed by conventional ultrasonic cleaning.
• fragments 118 may contain circuit residues originating from any microcomponents buried in the first plate at its bonding face with the second plate 110.
• the Applicant has therefore developed a method of removing fragments of material that may appear on the surface of a multilayer structure during its manufacture.
• An exemplary implementation of the method of the invention is described with reference to FIGS. 2 and 3.
• the multilayer structure 111c is rinsed and then placed in a tank 128 (or bowl) containing a rinsing solution 130, as illustrated in FIG. 3.
• This rinsing solution may correspond, for example, to Deionized water (EDI). However, other rinsing solutions may also be considered.
• Ultrasonic waves that is to say mechanical and elastic waves diffused for example by a liquid and whose frequency is greater than 20 kHz, are then propagated in the rinsing solution in which the composite structure 111c is immersed,
• ultrasonic waves can be produced, for example, by oscillating piezoelectric transducers at a specific frequency and power (eg use of a sonicator).
• Other types of ultrasound transducers may, however, be envisaged within the scope of the invention (magnetostrictive transducers, pneumatic generators, etc.).
• the emission of ultrasound waves under particular conditions leads to an effect called acoustic cavitation in the rinsing tank 128. More specifically, the ultrasonic waves cause significant depressions in the rinsing solution 130. When these depressions reach a critical threshold they give rise to bubbles in the rinsing solution 130. These bubbles are commonly called cavitation bubbles.
• the cavitation bubbles being particularly unstable, they implode when they meet the exposed surface of the first thinned plate 116. By imploding, these bubbles can emit a shock wave sufficient to break, loosen and disperse the fragments of material 118 present on the exposed surface of the first thinned plate 116.
• the material fragments 118 are removed by the rinsing solution 130.
• the amplitude of the depressions making it possible to obtain this cavitation phenomenon is notably controlled according to the frequency and the power of the emitted ultrasonic waves.
• the Applicant has determined that to obtain a cavitation effect capable of removing fragments of at least 2 ⁇ m in size, the frequency of the ultrasonic waves must be low. In other words, this frequency must be set in a range between 20 kHz and 1000 kHz. The closer the frequency is to the lower limit of the range (.120 kHz), the more the method of the invention makes it possible to eliminate large fragments.
• the frequency of the ultrasonic waves is between 20 kHz and 500 kHz, or even between 20 kHz and 100 kHz.
• the frequency is between 700 kHz and 1000 kHz.
• the viscosity of the rinsing solution 130 also has an impact on the amplitude of the depressions produced. Indeed, the higher the viscosity of the rinsing solution 130, the more the cavitation effect is difficult to obtain. It is therefore necessary to minimize the viscosity of the liquid solution in which the ultrasonic waves propagate.
• the viscosity of the liquid solution should be less than or equal to 30 mPa ⁇ S (ie 30 cps) at 25 ° C. Note that in this document, the term "viscosity" means the dynamic viscosity of a medium.
• the frequency and the power of the ultrasonic waves will therefore be adjusted according to the viscosity of the rinsing solution 130.
• the adjustment of the power of the ultrasonic waves makes it possible to modify the power of removal of the fragments of material 118.
• the power is set, for example, between 600W and 1200W.
• Rinse solution (possibility to add adjuvants in the used rinsing solution, possible recirculation of the rinsing solution in the tank).
• an oxide layer (from 500 ⁇ to 2 ⁇ m fragments of
• the etching solution 126 (of TMAH, for example) serves as a propagation medium for the ultrasonic waves and the cavitation effect is concomitant with the etching action of the etching solution 126.
• the process of the invention is applicable to any type of multilayer structure, and more particularly to multilayer structures whose plates have chamfered edges (or edge drops of any shape) and which can not be brought to high temperatures to perfectly stabilize I Bonding Interface.
• the invention applies in particular to structures of the SOS type.
• the elimination process according to the invention therefore advantageously makes it possible to eliminate the fragments of material which are deposited, or which are likely to be deposited, on the surface of a multilayer structure, and more particularly on the exposed surface of the transferred layer (ie the first thinned layer).
• the method of the invention is particularly suitable for removing particles of relatively large size, that is to say whose size is typically greater than 2 .mu.m.
• the method thus makes it possible to eliminate fragments of a few microns or even a few centimeters.
• the method of the invention is also advantageous in that the application parameters are controllable and reproducible. This technique can thus be optimized and automated for industrial purposes (unlike the conventional pressurized jet rinsing process).
• an ultrasound tank can advantageously be integrated into a production line of multilayer structures in order to implement the method of the invention.

Landscapes

• Engineering & Computer Science (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• General Physics & Mathematics (AREA)
• Manufacturing & Machinery (AREA)
• Computer Hardware Design (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Power Engineering (AREA)
• Physics & Mathematics (AREA)
• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Toxicology (AREA)
• General Health & Medical Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Cleaning Or Drying Semiconductors (AREA)
• Weting (AREA)
• Recrystallisation Techniques (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=42797115

Family Applications (1)

Country Status (8)

Families Citing this family (1)

Family Cites Families (5)

• 2010
  • 2010-02-26 FR FR1051367A patent/FR2956822A1/fr active Pending
• 2011
  • 2011-02-07 KR KR1020127022089A patent/KR20120137475A/ko not_active Application Discontinuation
  • 2011-02-07 US US13/580,860 patent/US20130045584A1/en not_active Abandoned
  • 2011-02-07 WO PCT/FR2011/050238 patent/WO2011104461A2/fr active Application Filing
  • 2011-02-07 EP EP11707462A patent/EP2539922A2/fr not_active Withdrawn
  • 2011-02-07 CN CN2011800104804A patent/CN102763191A/zh active Pending
  • 2011-02-07 SG SG2012059895A patent/SG183298A1/en unknown
  • 2011-02-07 JP JP2012554392A patent/JP2013520829A/ja not_active Withdrawn

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events