# US 12,765,333 B2 · Method for producing a pretreated composite substrate, and pretreated composite substrate

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- Number: US 12,765,333 B2
- Document ID: US12765333B2
- Status: Granted
- Kind: B2
- Application number: 18/267,564
- Filed: 2021-12-10
- Published: 2024-02-15
- Granted: 2026-10-13
- Earliest claimed: 2020-12-18
- Assignees: Mi2-Factory GmbH
- Applicants: Mi2-Factory GmbH
- Inventors: Constantin Csato; Florian Krippendorf
- Web page: https://patentgrep.com/patent/US12765333B2

## CPC

- H10P 90/00: Preparation of wafers not covered by a single main group of this subclass, e.g. wafer reinforcement
- H10P 10/128: {by direct semiconductor to semiconductor bonding}
- H10P 30/2042: {into crystalline silicon carbide}
- H10P 30/21: {of electrically active species}
- H10D 62/822: comprising only Group IV materials heterojunctions, e.g. Si/Ge heterojunctions
- H10D 62/8325: {Silicon carbide}
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

A method for producing a pretreated composite substrate, which is used as the basis for further processing into electronic semiconductor components, includes doping a first layer of SiC in a donor substrate by ion implantation using an energy filter; generating a predetermined breaking point in the donor substrate; and producing a bonded connection between donor substrate and acceptor substrate, the first layer being arranged in a region between the acceptor substrate and a remaining part of the donor substrate. Lastly, the donor substrate is split in the region of the predetermined breaking point to generate the pretreated composite substrate. The pretreated composite substrate has the acceptor substrate and a doped layer, which is connected to the acceptor substrate and includes at least a portion of the first layer of the donor substrate.

## Claims

### Claim 1

A method for producing a pretreated composite substrate which serves as a basis for further processing into electronic semiconductor components, the method comprising the steps of:
a) providing a donor substrate comprising monocrystalline SiC, wherein the donor substrate has a first layer extending from a first surface of the donor substrate to a predetermined doping depth, followed by a remaining portion of the donor substrate;
b) doping the first layer in the donor substrate in its entirety by ion implantation using an ion beam of ions of N, P, or Al, which passes through an energy filter, wherein the energy filter is a microstructured membrane having a predefined structure profile for adapting a dopant depth profile and/or defect depth profile caused by the implantation in the first layer in the donor substrate, wherein the doping creates a predetermined dopant depth profile and/or a predetermined defect depth profile in the first layer of the donor substrate, wherein the doping of the first layer extends from the first surface of the donor substrate, which faces the ion beam, up to the predetermined doping depth, wherein the doping of the first layer with the ions of N, P or Al affords p-doping or n-doping with a doping concentration in the first layer of 1E15 cm−3 to 5E17 cm−3;
c) creating an intended breakage site in the donor substrate by additional ion implantation that is different from the step of doping the first layer, electron irradiation, or laser irradiation;
d) providing the acceptor substrate and producing a bond between the donor substrate and the acceptor substrate, wherein the first layer is arranged in a region between the acceptor substrate and the remaining portion of the donor substrate;
e) splitting the donor substrate in the region of the intended breakage site to create the pretreated composite substrate, wherein the pretreated composite substrate comprises the acceptor substrate and a doped layer bonded thereto, wherein the doped layer comprises at least a section of the first layer of the donor substrate.

### Claim 2 (depends on 1)

The method of claim 1, wherein the first layer has a thickness of 3 to 15 μm.

### Claim 3 (depends on 1)

The method of claim 1, wherein the donor substrate is a crystal composed of high-quality semi-insulating SiC material of high purity.

### Claim 4 (depends on 3)

The method of claim 3, wherein the donor substrate is composed of SiC of the 4H, 6H or 3C polytype.

### Claim 5 (depends on 3)

The method of claim 3, wherein the surface of the donor substrate facing the ion beam has a deviation of less than 6° from a perpendicular to the c direction.

### Claim 6 (depends on 3)

The method of claim 3, wherein the donor substrate has a thickness of more than 100 μm up to 15 cm.

### Claim 7 (depends on 1)

The method of claim 1, wherein the donor substrate has a carrier wafer and an epitaxial layer, wherein the epitaxial layer is undoped or has a doping of less than 1E15 cm−3 and wherein the first layer is part of the epitaxial layer.

### Claim 8 (depends on 7)

The method of claim 7, wherein the epitaxial layer has a thickness of more than 10 μm.

### Claim 9 (depends on 7)

The method of claim 7, wherein the surface of the epitaxial layer facing the ion beam has a deviation of less than 6° from a perpendicular to the c direction.

### Claim 10 (depends on 7)

The method of claim 7, wherein the epitaxial layer is composed of SiC of the 4H, 6H or 3C polytype.

### Claim 11 (depends on 1)

The method of claim 1, wherein the doping of the first layer affords a substantially constant dopant depth profile and/or defect depth profile.

### Claim 12 (depends on 1)

The method of claim 1, wherein the doping of the first layer affords a dopant depth profile and/or defect depth profile which declines in steps, wherein the steps are formed in a near-surface region of the first layer, which faces the ion beam, by up to 40% of the total depth of the first layer.

### Claim 13 (depends on 12)

The method of claim 12, wherein a difference in concentration between the highest and lowest steps is at least a factor of 10.

### Claim 14 (depends on 12)

The method of claim 12, wherein the depthwise extent of the flank regions of the steps is predominant over the depthwise extent of the stepped plateaus.

### Claim 15 (depends on 1)

The method of claim 1, wherein the doping of the first layer affords a continuously declining dopant depth profile and/or defect depth profile.

### Claim 16 (depends on 15)

The method of claim 15, wherein the continuously declining dopant depth profile and/or defect depth profile is a profile according to the following formula:
D(z)=D_max·(1−1/√{square root over ( )}(1+∝·(1−z/b))·f)+D_0
wherein
Dmax is a maximum doping concentration,
α is a value between 10 and 10 000,
z is a distance from the surface,
b is a layer thickness,
f is a tolerance factor between 0.95 and 1.05, and
D0 is a background doping.

### Claim 17 (depends on 1)

The method of claim 1, further comprising the step of creating a contact layer in a surface region of the first layer, or of applying a contact layer to the surface of the first layer, and wherein the bonding between the donor substrate and acceptor substrate is established via the contact layer, resulting in the following sequence: acceptor substrate, contact layer, remaining portion of first layer or first layer, remaining portion of the donor substrate.

### Claim 18 (depends on 17)

The method of claim 17, wherein the contact layer is created by ion implantation.

### Claim 19 (depends on 17)

The method of claim 17, wherein a dopant concentration in the contact layer is at least 100 times greater than an average dopant concentration in the remainder of the first layer or in the first layer.

### Claim 20 (depends on 17)

The method of claim 17, wherein a dopant concentration in the contact layer is more than 1E17 cm−3.

### Claim 21 (depends on 19)

The method of claim 19, wherein the intended breakage site is in an end region of the first layer close to the predetermined doping depth, wherein the end region is not thicker than 1 μm.

### Claim 22 (depends on 1)

The method of claim 1, wherein the intended breakage site is in the region of the remaining portion of the donor substrate, and wherein, in addition, after step e), the further step of performing ion implantation using an energy filter into the composite substrate is performed in a supplementary layer from the side remote from the acceptor substrate.

### Claim 23 (depends on 22)

The method of claim 22, wherein the ion implantation into the supplementary layer of the composite substrate extends at least up to the doped layer.

### Claim 24 (depends on 23)

The method of claim 23, wherein the ion implantation into the composite substrate is performed in such a way that the combination of the two dopant depth profiles and/or defect depth profiles of the first layer and of the supplementary layer is a constant profile, a profile that rises stepwise toward the acceptor substrate, or a profile that rises continuously toward the acceptor substrate.

### Claim 25 (depends on 1)

The method of claim 1, wherein the intended breakage site is created by ion implantation of split-triggering ions.

### Claim 26 (depends on 25)

The method of claim 25, wherein the split-triggering ions are introduced over the entire width of the donor substrate.

### Claim 27 (depends on 25)

The method of claim 25, wherein the split-triggering ions are introduced only over a portion of the width of the donor substrate.

### Claim 28 (depends on 27)

The method of claim 27, wherein the split-triggering ions are introduced only in at least one edge region of the donor substrate.

### Claim 29 (depends on 25)

The method of claim 25, wherein the split-triggering ions are selected from the following: H, H2, He, B.

### Claim 30 (depends on 29)

The method of claim 29, wherein the split-triggering ions are high-energy ions having an energy between 0.5 and 10 MeV.

### Claim 31 (depends on 25)

The method of claim 25, wherein a particle dose of the split-triggering ions is in each case between 1E15 cm−2 and 5E17 cm−2.

### Claim 32 (depends on 25)

The method of claim 25, wherein the energy spread of the ion beam of the split-triggering ions is less than 10−2.

### Claim 33 (depends on 1)

The method of claim 1, wherein the splitting of the donor substrate is triggered by a thermal treatment of the composite substrate at a temperature of between 600° C. and 1300° C.

### Claim 34 (depends on 1)

The method of claim 1, wherein the bonding is established by a thermal treatment of the composite substrate at a temperature of between 800° C. and 1600° C.

### Claim 35 (depends on 1)

The method of claim 1, wherein both the establishment of the bonding and the splitting of the donor substrate are effected by a thermal treatment, with both steps being conducted simultaneously.

### Claim 36 (depends on 1)

The method of claim 1, wherein the step of establishing the bonding is preceded by a wet-chemical pretreatment, plasma pretreatment or ion beam pretreatment of at least one of the surfaces to be bonded.

### Claim 37 (depends on 1)

The method of claim 1, wherein the acceptor substrate is thermally stable up to at least 1500° C. and has a coefficient of linear expansion that deviates by not more than 20% from the coefficient of linear expansion of SiC.

### Claim 38 (depends on 37)

The method of claim 37, wherein the acceptor substrate is formed from polycrystalline SiC or graphite.

### Claim 39 (depends on 1)

The method of claim 1, wherein the step of splitting is followed by an aftertreatment of the surface of the composite substrate in the region of the intended breakage site by polishing and/or removal of defects.

### Claim 40 (depends on 1)

The method of claim 1, wherein implantation defects in the pretreated composite substrate are annealed at temperatures between 1500° C. and 1750° C.