Search

Objective The aim of this study was to evaluate the effect of the interval between CRT and surgery on radiation proctitis, the pathologic response, and postoperative morbidity. Methods This was a cohort study from a phase III, randomized controlled trial (FOWARC study, NCT01211210). Data were retrieved from the leading center of the trial. Patients were divided into the short‐interval (≤7 weeks) group and the long‐interval (>7 weeks) group. The rate of radiation proctitis, pathologic complete regression (pCR) and morbidities were calculated for each group. Multivariate analysis was used to verify the impact of interval on radiation proctitis. Results Surgery was performed in 60 patients after an interval of ≤7 weeks and in 97 patients after an interval of >7 weeks. The two groups according to interval were comparable in terms of baseline demographic and clinicotherapeutic characteristics. Radiation proctitis was identified by imaging in 9 (15.0%) patients in short‐interval group and in 31 (32.0%) patients in long‐interval group (P = .018). Multivariate analysis confirmed the correlation between long interval and radiation proctitis (P = .018). The long interval was significantly associated with longer median operation time compared to the short interval (P = .022). The rates of pCR and postoperative complications were not different between two groups. Conclusions A longer interval after CRT may be associated with higher rate of radiation proctitis and longer operation time. Moreover it did not increase the rate of pCR., A longer interval after CRT may be associated with higher rate of radiation proctitis and more difficult surgical resection. Moreover it did not increase the rate of pCR.

Antiprogrammed cell death protein-1 (PD-1) immunotherapy has substantially broadened in scope for the treatment of colorectal cancer (CRC). However, comparative safety, efficacy and survival outcome of anti-PD-1 therapy in CRC patients with and without hepatitis B virus (HBV) infection remain unclear.This multicenter, retrospective cohort study included 180 advanced-stage CRC patients with available serological markers for HBV infection treated with anti-PD-1 therapy at the Sixth Affiliated Hospital, Sun Yat-sen University and Sun Yat-sen University Cancer Center between December 2016 and December 2019. A propensity score-matched analysis was performed to compare the safety, efficacy, and survival outcome between HBV and non-HBV groups.The incidences of deficient mismatch repair and metastatic disease were significantly different between HBV and non-HBV groups (both P0.05). After propensity score-matched analysis, any grade immune-related adverse events and grade ≥ 3 immune-related adverse events were 47% vs 38% (P = 0.25) and 5% vs 6% (P = 1.0) between HBV and non-HBV groups, respectively. The overall response rate was 39% with 17 complete responses and 13 partial responses for the HBV infection cohort and 39% with 11 complete responses and 19 partial responses for the non-HBV infection cohort (P = 1.0). Two-year progression-free survival rates were 38% vs 40% (P = 0.596) and 2-year overall survival rates were 55% vs 63% (P = 0.401) for HBV vs non-HBV infection cohorts.The incidences of toxicity, efficacy and survival outcome were similar between patients with HBV infection and non-HBV patients receiving anti-PD-1 therapy, which supports to include CRC patients with HBV in clinical trials of anti-PD-1 therapy.

Purpose: Although many biological processes are involved in the modification of N6-methyladenosine (m6A), the exact role of m6A in the development of malignant tumors remains unclear. Methyltransferase 3 (METTL3) is a major RNA N6-methyladenosine methyltransferase. We aimed to explore the role of METTL3 in colorectal cancer (CRC) carcinogenesis and disease progression. Methods: In this study, immunohistochemistry was performed with a tissue microarray. qRT-PCR and Western blots were used to evaluate the expression of METTL3 in CRC cells. The effect of METTL3 on cell proliferation, migration and invasion of CRC cells was examined by IncuCyte Live Cell Analysis System and transwell assay, respectively. Results: The results suggested that positive expression of METTL3 was significantly associated with longer survival time (P=0.011). We next demonstrated that overexpression of METTL3 could inhibit proliferation, migration and invasion in CRC cells, while downregulation of METTL3 shows the opposite result. Furthermore, downregulation of METTL3 resulted in activation of p-p38 and p-ERK. Moreover, the inhibitors of p38 or ERK kinase could significantly reverse the effect of migration and invasion, which was induced by knockdown of METTL3. Conclusion: We concluded that METTL3 played a tumor-suppressive role in CRC cell proliferation, migration and invasion through p38/ERK pathways, which indicated that METTL3 might be a novel marker for CRC carcinogenesis, progression and survival.

Programmed death ligand-1 (PD-L1) is involved in inhibiting of T lymphocyte proliferation, producing cytokine, cytolytic activity, and suppressing of the immune response. Genes with molecular alterations involved in DNA mismatch repair promote cancer initiation and tumor progression. Clinical studies show that colorectal cancer (CRC) patients harboring microsatellite instability (MSI) have a higher anti-programmed cell death protein 1/PD-L1 immunotherapy response ratio compared with microsatellite stable subgroup patients. The underlying mechanism has however remained unclear. Here, we found that compared with microsatellite stable samples, PD-L1 was glycosylated and highly expressed both in MSI CRC cell lines and tissue samples. Specifically, PD-L1 was N-glycosylated at its N35, N192, N200, and N219 sites, and the four glycosylation sites were all responsible for PD-L1 degradation. Additionally, non-glycosylated PD-L1 underwent rapid degradation compared with glycosylated PD-L1 through the 26S proteasome pathway. The faster degradation of the non-glycosylated PD-L1 was ascribed to its binding to glycogen synthase kinase 3β via ubiquitination. This degradation phenotype was, however, not observed for glycosylated PD-L1. Significantly, glycosylated PD-L1 was up-regulated by activated epidermal growth factor receptor in MSI CRC cells. Together, our results indicate that epidermal growth factor receptor stabilized PD-L1 via glycosylation in MSI CRC cells, uncovering a novel role of PD-L1 in MSI CRC immunosuppression and disease progression. The study was approved by the Clinical Ethics Review Committee at the Six Affiliated Hospital of Sun Yat-sen University, China (Approval No. 2019ZSLYEC-005). Key words: epidermal growth factor receptor; glycogen synthase kinase 3β; glycosylation; microsatellite instability; microsatellite stability; programmed death ligand-1

Prior reports have indicated that defective mismatch repair (MMR) has a favorable impact on outcome in colorectal cancer patients treated with surgery, immunotherapy, or adjuvant chemotherapy. However, the impact of MMR status on response to neoadjuvant radiotherapy in rectal cancer is not well understood. Here we report that dMMR was associated with improved disease-free survival (DFS) (P = 0.034) in patients receiving neoadjuvant chemotherapy (NCT). Patients with dMMR tumors who received neoadjuvant chemoradiotherapy (NCRT) achieved significantly worse DFS (P = 0.026) than those treated with NCT. Conversely, NCRT improved DFS (P = 0.043) in patients with pMMR tumors, especially for stage III disease with improved DFS (P = 0.02). The presence of dMMR was associated with better prognosis in rectal cancer patients treated with NCT. NCT benefited patients with dMMR tumors; while NCRT benefited patients with stage III disease and pMMR tumors. Patients stratified by MMR status may provide a more tailored approach to rectal cancer neoadjuvant therapy.

Purpose: To investigate the predictive biomarker value of estrogen receptor 1 (ESR1) expression in tumor tissue on adjuvant chemotherapy in curatively resected colorectal cancer (CRC). Methods: A total of 467 CRC patients in 2007–2010 were retrospectively evaluated. Clinical information and follow-up data were retrieved from hospital registries and patient files. What's more, we used an external independent cohort (n = 511) from GSE39582 for further validation. Overall survival was estimated by the Kaplan–Meier method, and the survival curves were compared by log-rank tests. Cox proportional hazards models were used for multivariate analyses to calculate the hazard ratios (HRs) and test independent significance. Immunohistochemistry and Western blot were applied to detect protein expression of ESR1 in CRC patients and cell lines. The stable knockdown and overexpressed cells were transduced with the lentivirus. Cell viability was measured by an MTS reagent. Results: The predictive value of ESR1 was investigated in locally advanced CRC patients. Kaplan–Meier analysis indicated that ESR1 expression was significantly correlated with OS in patients receiving adjuvant chemotherapy from these cohorts, with p = 0.015 and p < 0.001, respectively. ESR1 expression was significantly correlated with 5-flurouracil (5-FU)-based adjuvant chemotherapy in training with an HR of 1.792 (95%CI: 1.100–2.921, p = 0.019). Downregulation of ESR1 was related with enhanced chemosensitivity to 5-FU in CRC cell lines, while upregulation of ESR1 was correlated with decreased chemosensitivity. Conclusions: The present study manifest clinical validity of ESR1 expression as a predictive biomarker on 5-FU-based adjuvant chemotherapy in stage II–III CRC.

Background Prognostic assessment is crucial for optimal treatment. The aim of our study was to investigate the potential impact of estrogen receptor-α (ER-α) and progesterone receptor (PR) on the prognosis of colorectal cancer (CRC) patients who received curative resection. Methods Retrospective evaluation of two independent cohorts of CRC patients maintained prospectively in 2009–2010 (training set) (n = 148) and 2007–2009 (internal validation set) (n = 485). Furthermore, we used an external independent CRC cohort from The Cancer Genome Atlas (TCGA) (n = 511) for further validation. ER-α and PR expression as well as other potential prognostic factors were retrospectively evaluated in training set with respect to overall survival (OS), local relapse free survival (LRFS) and distant metastasis free survival (DMFS). The prognostic factors found in training set will be validated in two validation cohorts. Results On univariate analysis for the training set, OS, LRFS and DMFS were not associated with PR expression. While patients with ER-αexpression were found to have poor prognosis. In addition, multivariate analysis showed that ER-αexpression maintained significance with respect to OS (HR, 5.06; p = 0.002), LRFS (HR, 8.81; p = 0.002) and DMFS (HR, 8.07; p = 0.004). Similarly, ER-α expression showed prognostic significance with respect to OS with hazard ratios (HRs) of 1.572 (95% CI: 1.001–2.467, p = 0.049) and 1.624 (95% CI: 1.047–2.520, p = 0.031) for the internal and external validation cohort, respectively. Conclusion ER-α expression was a biomarker of poor prognosis and it might inform treatment decision for high risk CRC patients. However, PR expression was not associated with survival outcomes.

BACKGROUND: Metastatic colorectal cancer (mCRC) is a heterogeneous disease. Predictive biomarkers are in great demand to optimize patient selection at high risk for death and to provide a novel insight into potential targeted therapy. METHODS: The present study retrospectively analyzed the gene expression profiles of tumor tissue samples from 4 public CRC cohorts, including 1 RNA-Seq data set from The Cancer Genome Atlas (TCGA) CRC cohort and 3 microarray data sets from GEO. Prognostic analysis was performed to test the predictive value of prognostic gene signature. RESULTS: Of 192 patients, 108 patients (56.3%) were men and median age was 65 years. A prognostic gene signature that consisted of 15 unique genes was generated in the discovery cohort. In the meta-validation cohorts, the signature significantly classified patients into high-risk and low-risk groups with regard to overall survival (OS) in mCRC patients with advanced stage disease and remained as an independent prognostic marker in multivariable analysis (1.57; 95% CI: 1.16–2.11; P=0.003) after adjusting for clinical parameters and molecular types. Gene Set Enrichment Analysis showed that several biological processes, including angiogenesis (P

This study aimed to investigate the association between Epstein-Barr virus (EBV)-related biomarkers and TNM classification according to the seventh edition of AJCC/UICC staging system for nasopharyngeal carcinoma. Serum VCA-IgA and EA-IgA titers and plasma EBV-DNA load were quantified at baseline in 779 patients; the rates of positivity and titers/load were compared by TNM classification. The VCA-IgA-positive rate was significantly associated with advanced N classification and stage; the EA-IgA-positive rate with advanced T and N classifications and stage; the EBV-DNA-positive rate with advanced T, N and M classifications and stage. The percentage of triple-positive patients was higher in patients with advanced TNM classification. The VCA-IgA titer and EA-IgA titer correlated positively with T classification, N classification and disease stage (1:117 in Stage I, 1:188.4 in Stage II, 1:231.12 in Stage III, 1:265.91 in Stage IV, and 1:18.34 in Stage I, 1:32.11 in Stage II, 1:34.77 in Stage III, 1:37.65 in Stage IV, respectively). EBV DNA load correlated positively with T, N and M classification and stage [median lg (EBV DNA): 0 (IQ range 0-1.85) in Stage I, 1.32 (0-3.51) in Stage II, 3.33 (0-4.30) in Stage III, 3.83 (2.85-4.71) in Stage IV]. Serum VCA-IgA/EA-IgA titers and plasma EBV DNA correlated strongly with TNM classification according to the seventh edition of the AJCC/UICC; however, plasma EBV DNA load could accurately predict metastatic disease. EBV serological biomarkers may enhance the accuracy of TNM staging and help to avoid excessive imaging examinations in routine evaluation.

Recent findings have reported that human serum microRNAs (miRNAs) can be used as prognostic biomarkers in various cancers. We aimed to explore the prognostic value of serum miRNAs in nasopharyngeal carcinoma (NPC) patients. The level of serum miRNA was retrospectively analyzed in 512 NPC patients recruited between January 2001 and December 2006. In the discovery stage, a microarray followed by reverse transcription-quantitative polymerase chain reaction was used to identify differentially altered miRNAs in eight patients with shorter survival and eight patients with longer survival who were well matched by age, sex and clinical stage. The identified serum miRNAs were then validated in all 512 samples, which were randomly divided into a training set and a validation set. Four serum miRNAs (miR-22, miR-572, miR-638 and miR-1234) were found to be differentially altered and were used to construct a miRNA signature. Risk scores were calculated to classify the patients into high- or low-risk groups. Patients with high-risk scores had poorer overall survival [hazard ratio (HR), 2.54; 95% confidence interval (CI), 1.57-4.12; p < 0.001] and distant metastasis-free survival (HR, 3.28; 95% CI, 1.82-5.94; p < 0.001) than those with low-risk scores in the training set; these results were confirmed in the validation and combined sets. The miRNA signature and TNM stage were independent prognostic factors. The combination of the miRNA signature and TNM stage had a better prognostic value than the TNM stage or miRNA signature alone. The four-serum miRNA signature may add prognostic value to the TNM staging system and provide information for personalized therapy in NPC.

This paper presents a new and improved solution for random yield improvement at the post-routing stage. The proposed solution is better suited for current processes, where a clustering effect has been observed resulting in differing particle densities in the metal and empty regions of the chip. To account for this clustering effect, we introduce the concept of weighted critical area to serve as a proxy for random yield loss. A new algorithm for weighted critical area minimization is also introduced. The proposed optimization solution derives a weighted critical area based on the user-specified particle densities. It then uses this weighted critical area information to dynamically select the appropriate critical area reduction technique in each local region to guarantee a reduction of the weighted critical area in both the local region and the whole layer. This makes the algorithm flexible and readily applicable to different process lines. It consistently improves the random yield irrespective of the particle densities in the metal and empty regions of the chip.

Background To assess the feasibility of elective neck irradiation to level Ib in nasopharyngeal carcinoma (NPC) using intensity-modulated radiation therapy (IMRT). Methods We retrospectively analyzed 1438 patients with newly-diagnosed, non-metastatic and biopsy-proven NPC treated with IMRT. Results Greatest dimension of level IIa LNs (DLN-IIa) ≥ 20 mm and/or level IIa LNs with extracapsular spread (ES), oropharynx involvement and positive bilateral cervical lymph nodes (CLNs) were independently significantly associated with metastasis to level Ib LN at diagnosis. No recurrence at level Ib was observed in the 904 patients without these characteristics (median follow-up, 38.7 months; range, 1.3–57.8 months), these patients were classified as low risk. Level Ib irradiation was not an independent risk factor for locoregional failure-free survival, distant failure-free survival, failure-free survival or overall survival in low risk patients. The frequency of grade ≥ 2 subjective xerostomia at 12 months after radiotherapy was not significantly different between low risk patients who received level Ib-sparing, unilateral level Ib-covering or bilateral level Ib-covering IMRT. Conclusion Level Ib-sparing IMRT should be safe and feasible for patients without a DLN-IIa ≥ 20 mm and/or level IIa LNs with ES, positive bilateral CLNs or oropharynx involvement at diagnosis. Further investigations based on specific criteria for dose constraints for the submandibular glands are warranted to confirm the benefit of elective level Ib irradiation.

Background Pregnancy-associated nasopharyngeal carcinoma (PANPC) has been associated with poor survival. Recent advances in radiation technology and imaging techniques, and the introduction of chemotherapy have improved survival in nasopharyngeal carcinoma (NPC); however, it is not clear whether these changes have improved survival in PANPC. Therefore, the purpose of this study was to compare five-year maternal survival in patients with PANPC and non-pregnant patients with NPC. Methods After adjusting for age, stage and chemotherapy mode, we conducted a retrospective case-control study among 36 non-metastatic PANPC patients and 36 non-pregnant NPC patients (control group) who were treated at our institution between 2000 and 2010. Results The median age of both groups was 30years (range, 23–35years); median follow-up for all patients was 70months. Locoregionally-advanced disease accounted for 83.3% of all patients with PANPC and 92.9% of patients who developed NPC during pregnancy. In both the PANPC and control groups, 31 patients (86.1%) received chemotherapy and all patients received definitive radiotherapy. The five-year rates for overall survival (70% vs. 78%, p =0.72), distant metastasis-free survival (79% vs. 76%, p =0.77), loco-regional relapse-free survival (97% vs. 91%, p =0.69) and disease-free survival (69% vs. 74%, p =0.98) were not significantly different between the PANPC and control groups. Multivariate analysis using a Cox proportional hazards model revealed that only N-classification was significantly associated with five-year OS. Conclusion This study demonstrates that, in the modern treatment era, pregnancy itself may not negatively influence survival outcomes in patients with NPC; however, pregnancy may delay the diagnosis of NPC.

To propose a novel clinical typing classification focusing on the distinct progression patterns of nasopharyngeal carcinoma (NPC), to supplement our knowledge of the clinical-biological behavior, to provide useful knowledge for treatment planning, and to contribute to basic research in NPC.632 consecutive patients were retrospectively reviewed and analyzed according to the novel typing system. We considered that NPC can be divided into 5 types as follows: limited (L), ascending (A), descending (D) ascending- descending (mixed) (AD), and distant metastasis types (M). The distribution of these clinical types, their association with Epstein-Barr virus (EBV) serology and prognostic value were explored.55 (8.70%), 59 (9.34%), 177 (28.01%), 321 (50.79%) and 20 (3.16%) patients were classified as Type L, A, D, AD and M, respectively. EBV (VCA)-IgA titers, EBV early antigen (EA)-IgA serum titers, and capsid antigen lg(EBV DNA) were positively associated with the clinical typing (p0.05). The 3-year overall survival (OS) rates for Types L, A, D, AD and M were 100, 100, 95.10, 88.20 and 59.30%, respectively (p0.001). A prognostic model was constructed based on pretreatment lg (EBV DNA) and clinical type, which were independent predictors of OS (multivariate Cox proportional model). The prognostic model stratified patients into 4 risk subgroups. The 3-year OS rates of the low, intermediate, high and extremely high risk groups were 99.5, 90.0, 85.5 and 53.2%, respectively (p0.001). Compared with the low-risk group, the risk of death was 4.96, 8.75 and 35.9 in the intermediate, high and extremely high risk groups, respectively (p0.001). The model also predicted OS independently of TNM classification.This novel clinical typing system and prognostic model can supplement TNM classification, and may help design novel treatment strategies, evaluate risk stratification and investigate the varied biological characteristics of NPC.

In this paper, we present a temperature-aware simulation environment, iTAS, which has been developed for the design of thermally reliable ultra-large scale integrated (ULSI) chips. This environment provides advisory information from the early chip design phase to the post-layout analysis phase. Several important applications, including temperature-sensitive timing analysis, efficient on-chip hot-spot identification, and thermally reliable package design are addressed, iTAS can be used not only for reliability checking, but also for better thermal engineering to enhance the overall chip performance.

In this paper, we present a new chip-level electrothermal timing simulator for CMOS VLSI circuits. Given the chip layout, the packaging specification, and the periodic input signal pattern, it finds the on-chip steady-state temperature profile and the resulting circuit performance. A tester chip has been designed for verification of ILLIADS-T, and very good agreement between simulation and experiment was found. Using this electrothermal simulator, temperature-dependent reliability and timing problems of VLSI circuits can be accurately identified.

In this paper, we present a new electromigration reliability diagnosis tool (iTEM) for CMOS VLSI circuits. Unlike previous electromigration reliability tools, iTEM can estimate the interconnect temperature rise due to joule heating and heat conduction from the substrate using a newly developed lumped thermal model. By including the temperature effect, iTEM provides much more accurate electromigration reliability diagnosis. Moreover, it is computationally efficient, and can analyze circuit layouts containing tens of thousands of transistors on a desktop workstation.

With advances in imaging and radiotherapy, the prognostic value of skull-base invasion in nasopharyngeal carcinoma (NPC) needs to be reassessed. We aimed to define a classification system and evaluate the prognostic value of the classification of magnetic resonance imaging (MRI)-detected skull-base invasion in NPC treated with intensity-modulated radiotherapy (IMRT). We retrospectively reviewed 749 patients who underwent MRI and were subsequently histologically diagnosed with nondisseminated NPC and treated with IMRT. MRI-detected skull-base invasion was not found to be an independent prognostic factor for overall survival (OS), distant metastasis-free survival (DMFS), local relapse-free survival (LRFS), or disease-free survival (DFS; p > 0.05 for all). Skull-base invasion was classified according to the incidence of each site (type I sites inside pharyngobasilar fascia and clivus vs. type II sites outside pharyngobasilar fascia). The 5-year OS, DMFS, LRFS, and DFS rates in the classification of skull-base invasion in NPC were 83 vs. 67 %, 85 vs.75 %, 95 vs. 88 %, and 76 vs. 62 %, respectively (p

Recent findings have reported that human serum microRNAs (miRNAs) can be used as prognostic biomarkers in various cancers. We aimed to explore the prognostic value of serum miRNAs in nasopharyngeal carcinoma (NPC) patients. The level of serum miRNA was retrospectively analyzed in 512 NPC patients recruited between January 2001 and December 2006. In the discovery stage, a microarray followed by reverse transcription-quantitative polymerase chain reaction was used to identify differentially altered miRNAs in eight patients with shorter survival and eight patients with longer survival who were well matched by age, sex and clinical stage. The identified serum miRNAs were then validated in all 512 samples, which were randomly divided into a training set and a validation set. Four serum miRNAs (miR-22, miR-572, miR-638 and miR-1234) were found to be differentially altered and were used to construct a miRNA signature. Risk scores were calculated to classify the patients into high- or low-risk groups. Patients with high-risk scores had poorer overall survival [hazard ratio (HR), 2.54; 95% confidence interval (CI), 1.57-4.12; p0.001] and distant metastasis-free survival (HR, 3.28; 95% CI, 1.82-5.94; p0.001) than those with low-risk scores in the training set; these results were confirmed in the validation and combined sets. The miRNA signature and TNM stage were independent prognostic factors. The combination of the miRNA signature and TNM stage had a better prognostic value than the TNM stage or miRNA signature alone. The four-serum miRNA signature may add prognostic value to the TNM staging system and provide information for personalized therapy in NPC.

To report a novel approach for craniospinal irradiation (CSI) using a supine isocentric technique.Patients were treated in the supine position using CT simulation. Half-beam-blocked lateral cranial fields and superior spinal fields have the same isocentre, and their beam divergences match. Tangential irradiation provides a non-divergent junction for the other two full-beam spinal fields. Shielding for cranial fields was generated, and dose distribution was calculated using a three-dimensional planning system. When sacral spinal fields were required, two lateral opposite fields were designed to protect the urogenital organs. All treatment portals were filmed once per week.At a median follow-up of 49.8 months, 5 relapses and no cases of radiation myelitis developed in 26 consecutive patients. In the junctions of the brain-spine or spine-spine field, no failure occurred. Three failures occurred in the primary site alone, two in the spinal axis alone.The results of our study have shown that our novel approach for CSI was not associated with increased failures at the field junction and deaths. In addition, no radiation myelitis, pneumonia, severe damage to the heart and gastrointestinal tract, and second cancers occurred in our study.This new approach is an optimal alternative in cancer centre without tomotherapy because of its convenience for immobilization, repeatability, optimal dose distribution and satisfactory clinical outcome.

With feature sizes on chips shrinking at advanced process nodes, the difficulty in manufacturability and reliability of chips is extremely increasing. It has necessitated better planarization of chip surface topography to improve both functional and parametric yields. The common solution to minimize topography variation is to perform metal fills in empty spaces in the layout. However, these dummy metals will increase the capacitances between wires and then invoke delay and coupling/ crosstalk noise problems. Furthermore, the impact of ECP (electroplating) should be included in the copper CMP model in order to have accurate metal fill results. In this paper, we adopt and implement an approach to considering especially the key layout parameters that affect the post-ECP topography. We further apply a greedy-based method to place the floating dummy metals in the positions with minimal additional coupling capacitances. The experimental results are encouraging. Our method not only considers the thickness range of post-ECP, it can also add much less additional coupling capacitances over a density-driven metal fill method.

Design-for-manufacturing (DFM) is becoming an actual design practice among IC manufacturers, designers and EDA companies. Layout assessment by design-rule-check (DRC) using EDA tools is a common practice today to ensure well-manufactured design geometries. Standalone DFM tools, which require iteration loops of DFM analysis and fixing, do not fit well in design flows and are considered cumbersome. A better layout assessment method for DFM issues is required: one that gives actionable feedback, and that can be used with automatic optimization in early design stages. The latter is needed to avoid costly design re-spins that will consume critical time-to-market as well as use a lot of engineering resources, reticles and wafer material costs. For example, a DFM checking tool may report the hotspot types and locations, but this information is not sufficient for designers to decide tradeoffs between different fixing choices and to take care of trade-off between physical and electrical design constraints at the same time. When model-based properties are introduced such as lithographic contour, the tradeoffs between rule-based and model-based properties can only be resolved by the automatic and concurrent optimization. This work demonstrates a methodology of DFM scoring of layout based on preferred rules compliance, lithography GATE printability, as well as the layout fixing. The electrical impact on gates is analyzed and showed reduced variability (compared to nominal behavior) in gate performance. Designers can get visual feedback of the layout quality, as well as improvement suggestions. Takumi TKE software is used to demonstrate automatic and concurrent optimization. The method applies to both cell-level and custom designs.

In this paper, we present the first chip-level electrothermal simulator, iCET. For a given chip layout, packaging material, user-specified input signal patterns, and thermal boundary conditions, it automatically finds the CMOS on-chip steady-state temperature profile and the resulting circuit performance. iCET has been tested on several circuits and it can efficiently analyze layouts containing tens of thousands of transistors on a desktop workstation.

In this paper, we present a fast thermal reliability diagnosis tool (iTHREAD) for CMOS VLSI chips. Unlike existing circuit-level electrothermal simulators, it finds the steady-state temperature distribution, the hot spots, as well as the resulting power consumptions in an extremely efficient way. By using a fast timing simulator with accurate temperature-dependent device models and a novel 3-D analytical thermal simulator, it can easily handle very large circuits. With iTHREAD, temperature-dependent reliability and timing problems of VLSICs can be accurately and quickly predicted. It can be further applied to guide the module placement, timing verification, and many other IC reliability diagnoses.

In this paper, we present a chip-level electrothermal simulator, ILLIADS-T. It aims at finding the steady-state CMOS VLSI chip temperature profile and the corresponding circuit performance. With this tool, temperature-related reliability problems of VLSI chips can be accurately predicted to guide the module placement, packaging, as well as the timing verification.

In this paper, a new thermal simulator is developed to predict the steady-state and transient temperatures inside a VLSI chip subjected to heating by single or multiple heat sources. It uses a mixed 3D finite-difference and 1D analogous thermal circuit method, taking into account any combination of boundary conditions, shape of heat sources, and packaging. An analytical method is also presented and compared to the numerical method. With this tool, the chip temperature can be predicted accurately to provide design guidelines for VLSI module placement and chip packaging.

In this paper, we present a new electromigration reliability diagnosis tool (iTEM) for CMOS VLSI circuits. Unlike previous electromigration reliability tools, iTEM can estimate the interconnect temperature rise due to joule heating and heat conduction from the substrate using a newly developed lumped thermal model. Including the temperature effect, iTEM provides more accurate electromigration reliability diagnosis. Moreover, it is very fast and can analyze circuit layouts containing tens of thousands of transistors on a desktop workstation.

In this paper, we present a hierarchical reliability-driven CAD system for the design of electromigration resistant circuits. The top of the hierarchy aims at quickly identifying those critical interconnects with potential electromigration reliability problems. Then the detailed electromigration analysis of critical interconnects is carried out by an accurate and computationally efficient simulation tool (ITEM). This top-down approach provides a feasible solution to the complicated electromigration diagnosis problem.