Semiconductor wafer fabrication methods

Abstract

A method for fabricating a semiconductor wafer includes the following steps: (a) preparing a main substrate and a carrier substrate; (b) depositing a bonding layer on a top surface of the carrier substrate; (c) performing ion implantation from the top surface of the main substrate downwards to form a release region; (d) thermally bonding the top surface of the main substrate to the bonding layer to form a first intermediate; (e) thermally separating the first intermediate along the release region to obtain a second intermediate comprising the carrier substrate, the bonding layer, and a thinned main substrate layer; (f) planarizing the thinned main substrate layer to obtain an epitaxial substrate; (g) performing epitaxial and semiconductor device fabrication processes on the epitaxial substrate to obtain a third intermediate; and (h) laser pyrolysis of the third intermediate to obtain a semiconductor wafer.

Claims

1. A method for fabricating a semiconductor wafer, comprising: a step (a) preparing a main substrate with a thickness of 300-500 μm and made of silicon carbide, and a carrier substrate made of silicon carbide; a step (b) depositing a bonding layer with a thickness of 10-100 nm on a top surface of the carrier substrate, wherein the bonding energy between the bonding layer and the silicon carbide is 1-5 J / m², and the bandgap of the bonding layer is between 0.5 eV and 3.2 eV; a step (c) performing ion implantation from the top surface of the main substrate downwards to form a release region at a depth of more than 0 μm and not more than 100 μm from the top surface of the main substrate; and a step (d) bonding the top surface of the main substrate to the bonding layer formed on the carrier substrate by thermal bonding to form a first intermediate. Step (e) involves setting a predetermined temperature on the first intermediate and thermally separating the main substrate of the first intermediate from the carrier substrate along the peeling region to obtain a second intermediate comprising the carrier substrate, the bonding layer formed on the carrier substrate, and a thinned main substrate layer; Step (f) involves planarizing the thinned main substrate layer of the second intermediate to obtain an epitaxial substrate having an epitaxial surface; Step (g) involves performing epitaxial and semiconductor device fabrication processes on the epitaxial surface to form a semiconductor device layer to obtain a third intermediate; and Step (h) involves applying a pulsed laser with a wavelength between 380 and 1100 nm from the carrier substrate of the third intermediate toward the semiconductor device layer to perform laser thermal decomposition on the bonding layer, thereby separating the thinned main substrate layer from the carrier substrate to obtain a semiconductor wafer.

2. The method for fabricating a semiconductor wafer as described in claim 1, wherein, The silicon carbide is selected from conductive 4H-type silicon carbide or semi-insulating 4H-type silicon carbide.

3. The method for fabricating a semiconductor wafer as described in claim 1, wherein, In step (b), the bonding layer material is selected from indium oxide or indium nitride.

4. The method for fabricating a semiconductor wafer as described in claim 1, wherein, The ion implantation can be either hydrogen ion (H+) implantation or helium ion (He+) implantation.

5. The method for fabricating a semiconductor wafer as described in claim 1, wherein, The temperature range for this thermal bonding method is between 100 and 500°C.

6. The method for fabricating a semiconductor wafer as described in claim 1, wherein, The predetermined temperature in step (e) is between 500 and 1000°C.

7. The method for fabricating a semiconductor wafer as described in claim 1, wherein, The planarization process is performed using a chemical mechanical planarization (CMP) process.

8. The method for fabricating a semiconductor wafer as described in claim 1, wherein, The energy density of this pulsed laser ranges from 100 mJ / cm² to 10000 mJ / cm².

9. The method for fabricating a semiconductor wafer as described in claim 8, wherein, The frequency of this pulsed laser is between 10 Hz and 1 MHz.

10. The method for fabricating a semiconductor wafer as described in claim 1, wherein, The bonding layer has a first absorption coefficient for the pulsed laser, while the carrier substrate has a second absorption coefficient for the pulsed laser, wherein the first absorption coefficient is greater than the second absorption coefficient.

Images