SMIC process is 7nm, says Tech Insights

Technology News | August 30, 2022

By Peter Clarke

Teardown specialist consultancy Tech Insights (Ottawa, Canada) has classed the N+1 process from Chinese foundry Semiconductor Manufacturing International Corp. (SMIC) as a 7nm process, albeit on a relaxed pitch for polysilicon, fin and metal interconnect.

Tech Insights has produced a series of reports on the process and asserts “SMIC 7nm is not part of the 10nm grouping; it falls into the 7nm group with respect to standard cell height. From the height and width of the SMIC standard cells, SMIC scaling puts their technology in the same 7nm group as Intel, TSMC and Samsung.”

However, in the documents shown under open access Tech Insights makes no reference to M1 metal pitch, which is one of the key defining parameters of a process.

Rapid progress

SMIC was not expected to proceed so quickly to 7nm manufacturing because it has been denied access to extreme ultraviolet lithography equipment from monopoly supplier ASML Holding (see US seeks to expand ban on ASML’s China sales).

As result SMIC has had to develop its process using only deep-UV immersion lithography equipment. This is likely to make production of 7nm, while technically possible, more complex, lower yielding and considerably more expensive.

Tech Insights acknowledged that the SMIC 7nm process shows more relaxed scaling for contacted poly, metal and fin pitches, setting it apart from TSMC N7+ and Intel 10nm – all of which use single diffusion break (SDB) and design technology co-optimization (DTCO). However, a more relaxed scaling means fewer transistors and gates per unit area.

Tech Insights also states: “We believe it is a notable achievement for SMIC to take only two years to reach 7nm (from 14nm) without access to the most advanced western equipment and technologies.” By comparison Tech Insights reckons TSMC took three years to get from 16nm to 7nm and Samsung took five years to get from 14nm to 7nm with an intermediate 10nm.

The analysis shows a number of similarities between the SMIC 7nm and TSMC 7nm processes.

Comparison of SMIC and TSMC 7nm manufacturing processes. Source: Tech Insights.

Recently Tech Insights revealed that the MinerVa Bitcoin mining chip is based on this N+1 7nm process (see Opinion: Misplaced outrage over near-7nm SMIC chip).

Tech Insights reckons that the application is less sensitive to process variation and makes use of a higher threshold voltage for transistors in the more typical logic circuits.

Lack of EUV, EDA

Due to the US trade restrictions, SMIC may not have access to the complete set of supporting IP libraries typically provided by EDA vendors such as Synopsys and Cadence. However, basic standard cell IP is available from other vendors and SMIC does not appear to have been prevented from supporting a full 7nm manufacturing process technology.

However, ARM processor optimized packages (POPs) are a key factor in foundries’ process optimization and US sanctions may have blocked support for SMIC and this would have a significant impact on SMIC’s ability to produce a broader range of ASICs at 7nm, Tech Insights said.

Tech Insights concluded that despite being denied EUV lithography equipment SMIC has incorporated a number of technology elements and design technology co-optimization (DTCO) integration into a 7nm manufacturing process with relaxed scaling. This will reduce China’s reliance on the Western technologies and support more advanced domestic fabless design and manufacturing. However, the denial of access to EUV lithography and advanced EDA software may prevent scaling beyond the 7nm capability.