What is the expected penetration rate for 5G smartphones in the total smartphone market in 2021 
g demand for our advanced technologies in the next several years. We expect global smartphone units to grow 10% year-over-year in 2021. We forecast the penetration rate for 5G smartphone of the total smartphone market to rise from 18% in 2020 to more than 35% in 2021.
We expect the silicon content of a 5G smartphone to continue to increase as compared to a 4G smartphone. We continue to expect faster penetration of 5G smartphone as compared to 4G over the next several years as 5G smartphone benefit from the significant performance and with a latency improvement of 5G network to drive more AI applications and more cloud services. We believe 5G is a multi-year megatrend that will enable a world where digital computation is increasingly ubiquitous, which will fuel the growth of all four of our growth platforms in the next several years.
As we enter the 5G era, a smarter and more intelligent world will require massive increases in computation power and greater need for energy-efficient computing, and therefore, require leading-edge technologies. Thus, HPC is an increasingly important driver of TSMC's long-term growth and the largest contributor in terms of our incremental revenue growth. With our technology leadership, we are well positioned to capture the growth from the favorable industry megatrend. We now expect our long-term revenue growth to be 10% to 15% CAGR from 2020 to 2025 in US dollar terms.
Now, I will talk about the N3 status. N3 will be another full node stride from our N5 with up to 70% logic density gain, up to 15% performance gain and up to 30% power reduction as compared with 5-nanometer. Our N3 technology will use FinFET transistor structure to deliver the best technology maturity, performance and cost for our customers. Our N3 technology development is on track with good progress. We are seeing a much higher level of customer engagement for both HPC and smartphone application at N3 as compared with N5 and N7 at a similar stage. Risk production is scheduled in 2021 and volume production is targeted in second half of 2022. Our 3-nanometer technology will be the most advanced foundry technology in both PPA and transistor technology when it is introduced. Thus, we are confident our 3-nanometer will be another large and long-lasting node for TSMC.
Finally, I will talk about TSMC's 3D fabric. TSMC has developed an industry-leading and comprehensive wafer-level 3DIC technology roadmap to enhance system-level performance. Our differentiated chiplet and heterogeneous integration technologies drive better power efficiency, as smaller form factor benefit for our customer, while shortening their time to market. This technology, including CHIPS stake in solution, such as SoIC, as well as our advanced packaging solutions, such as InFO and CoWoS. We observe chiplets are becoming an industry trend. We are working with several customers on 3D fabric to enable chiplet architecture. SoIC's full volume production is targeted in 2022. SoIC is expected to be first adopted by HPC applications, where bandwidth performance, power efficiency and form factor are aggressively pursued. We expect revenue from our back-end services, which include InFO's advanced packaging and testing to grow at a rate higher than corporate average in the next few years.
This concluding our key message. Thank you for your attention.
Jeff Su -- Director of Investor Relations
Thank you, C.C. This concludes our prepared statements. Before we start the Q&A session, I would like to remind everybody to please limit your questions to two at a time to allow all the participants an opportunity to ask their questions. Should you raise to -- wish to raise your question in Chinese, I will translate into English before our management answers your question.
[Operator Instructions] Now, let's begin the Q&A session. Operator, please proceed with the first caller on the line.
Questions and Answers:
Operator
Yes. The first one to ask question, Gokul Hariharan from J.P. Morgan.
Gokul Hariharan -- J.P. Morgan -- Analyst
Thank you for taking my question. Happy New Year and f
g demand for our advanced technologies in the next several years. We expect global smartphone units to grow 10% year-over-year in 2021. We forecast the penetration rate for 5G smartphone of the total smartphone market to rise from 18% in 2020 to more than 35% in 2021.
We expect the silicon content of a 5G smartphone to continue to increase as compared to a 4G smartphone. We continue to expect faster penetration of 5G smartphone as compared to 4G over the next several years as 5G smartphone benefit from the significant performance and with a latency improvement of 5G network to drive more AI applications and more cloud services. We believe 5G is a multi-year megatrend that will enable a world where digital computation is increasingly ubiquitous, which will fuel the growth of all four of our growth platforms in the next several years.
As we enter the 5G era, a smarter and more intelligent world will require massive increases in computation power and greater need for energy-efficient computing, and therefore, require leading-edge technologies. Thus, HPC is an increasingly important driver of TSMC's long-term growth and the largest contributor in terms of our incremental revenue growth. With our technology leadership, we are well positioned to capture the growth from the favorable industry megatrend. We now expect our long-term revenue growth to be 10% to 15% CAGR from 2020 to 2025 in US dollar terms.
Now, I will talk about the N3 status. N3 will be another full node stride from our N5 with up to 70% logic density gain, up to 15% performance gain and up to 30% power reduction as compared with 5-nanometer. Our N3 technology will use FinFET transistor structure to deliver the best technology maturity, performance and cost for our customers. Our N3 technology development is on track with good progress. We are seeing a much higher level of customer engagement for both HPC and smartphone application at N3 as compared with N5 and N7 at a similar stage. Risk production is scheduled in 2021 and volume production is targeted in second half of 2022. Our 3-nanometer technology will be the most advanced foundry technology in both PPA and transistor technology when it is introduced. Thus, we are confident our 3-nanometer will be another large and long-lasting node for TSMC.
 Finally, I will talk about TSMC's 3D fabric. TSMC has developed an industry-leading and comprehensive wafer-level 3DIC technology roadmap to enhance system-level performance. Our differentiated chiplet and heterogeneous integration technologies drive better power efficiency, as smaller form factor benefit for our customer, while shortening their time to market. This technology, including CHIPS stake in solution, such as SoIC, as well as our advanced packaging solutions, such as InFO and CoWoS. We observe chiplets are becoming an industry trend. We are working with several customers on 3D fabric to enable chiplet architecture. SoIC's full volume production is targeted in 2022. SoIC is expected to be first adopted by HPC applications, where bandwidth performance, power efficiency and form factor are aggressively pursued. We expect revenue from our back-end services, which include InFO's advanced packaging and testing to grow at a rate higher than corporate average in the next few years.
This concluding our key message. Thank you for your attention.
Jeff Su -- Director of Investor Relations
Thank you, C.C. This concludes our prepared statements. Before we start the Q&A session, I would like to remind everybody to please limit your questions to two at a time to allow all the participants an opportunity to ask their questions. Should you raise to -- wish to raise your question in Chinese, I will translate into English before our management answers your question.
[Operator Instructions] Now, let's begin the Q&A session. Operator, please proceed with the first caller on the line.
Questions and Answers:
Operator
Yes. The first one to ask question, Gokul Hariharan from J.P. Morgan.
Gokul Hariharan -- J.P. Morgan -- Analyst
Thank you for taking my question. Happy New Year and f