SOI Receiver Substrate Oxidation for Higher RF Breakdown Voltage
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Solution Overview
Problem
The existing semiconductor-on-insulator structure fabrication processes for radiofrequency applications face challenges in achieving sufficient breakdown voltage while maintaining low production costs, with direct bonding requiring high implantation energy and consuming the donor substrate, and reverse bonding resulting in a low breakdown voltage due to the oxide layer's properties.
Innovation Solution
A reverse-bonding process where the charge-trapping polysilicon layer is oxidized at temperatures between 750° C. and 875° C., with a gradual temperature decrease, to form an oxide layer with increased breakdown voltage, and the transfer of a semiconductor or ferroelectric layer from a donor substrate to a receiver substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct bonding is used to form the oxide layer on the donor substrate, then the breakdown voltage is improved, but the implantation energy requirement increases and donor substrate reusability deteriorates
Solution Approach 1:
The patent inverts the conventional direct bonding approach by forming the oxide layer on the receiver substrate's polysilicon charge-trapping layer instead of on the donor substrate. This reverse bonding approach allows the oxide to be formed at lower energies while maintaining the necessary breakdown voltage characteristics for RF applications.
Solution Approach 2:
The patent changes the location and formation conditions of the oxide layer by forming it in-situ on the polysilicon charge-trapping layer of the receiver substrate. This parameter change enables oxide formation without high-energy implantation through the oxide, thereby reducing energy requirements while achieving the needed electrical performance.
2Ease of manufacture
If reverse bonding is used to form the oxide layer on the receiver substrate, then production costs are reduced and donor substrate reusability is improved, but the breakdown voltage deteriorates
Solution Approach 1:
The patent optimizes the oxidation parameters by forming the oxide layer in-situ on the polysilicon charge-trapping layer at controlled temperatures and atmospheres. This parameter optimization enables the oxide to achieve sufficient breakdown voltage for RF applications while maintaining the cost and reusability advantages of reverse bonding.
Solution Approach 2:
The polysilicon charge-trapping layer serves as an intermediary substrate on which the oxide layer is formed in-situ. This intermediary approach allows the oxide to be formed with favorable electrical characteristics for RF applications while avoiding the drawbacks of both conventional direct bonding and standard reverse bonding approaches.
3Quantity of substance
If high implantation energy is used in direct bonding, then the oxide layer can be formed on the donor substrate, but the implantation current density decreases and production cost increases
Solution Approach 1:
The patent inverts the bonding sequence to form the oxide layer on the receiver substrate before bonding, eliminating the need for high-energy implantation through the oxide layer. This inversion enables oxide formation at lower energies with higher current densities, improving productivity and reducing costs.
Solution Approach 2:
The oxide layer is formed in advance on the polysilicon charge-trapping layer of the receiver substrate before the bonding process. This preliminary action allows the oxide to be formed under optimized conditions without the constraints of subsequent high-energy implantation, thereby improving current density and reducing production costs.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The process enhances the breakdown voltage of the oxide layer, reduces production costs, and improves the reusability of the donor substrate, enabling more efficient semiconductor-on-insulator structure fabrication for radiofrequency applications.
Implementation Method 1
oxidizing the charge-trapping layer to form an oxide layer, arranged on the charge-trapping layer
Implementation Method 2
implanting atomic species in the donor substrate so as to form a weakened zone
Implementation Method 3
bonding the donor substrate to the receiver substrate
Data Source
AI summary
A process for producing a receiver substrate for a semiconductor-on-insulator structure for radiofrequency application comprises the following steps:—providing a semiconductor substrate comprising a base substrate made of monocrystalline material and a charge-trapping layer made of polycrystalline silicon arranged on the base substrate;—oxidizing the charge-trapping layer to form an oxide layer arranged on the charge-trapping layer. The oxidation of the charge-trapping layer is performed at least partly at a temperature lower than or equal to 875° C., in the following manner:—starting the oxidization at a first temperature (T1) between 750° C. and 1000° C.;—decreasing the temperature down to a second temperature (T2), lower than the first temperature (T1), between 750° C. and 875° C.;—continuing the oxidization at the second temperature (T2).